U.S. patent application number 13/979738 was filed with the patent office on 2014-01-02 for textile materials comprising tapes in two oblique orientations and its method and means for production.
This patent application is currently assigned to TAPE WEAVING SWEDEN AB. The applicant listed for this patent is Nandan Khokar. Invention is credited to Nandan Khokar.
Application Number | 20140004296 13/979738 |
Document ID | / |
Family ID | 44872676 |
Filed Date | 2014-01-02 |
United States Patent
Application |
20140004296 |
Kind Code |
A1 |
Khokar; Nandan |
January 2, 2014 |
TEXTILE MATERIALS COMPRISING TAPES IN TWO OBLIQUE ORIENTATIONS AND
ITS METHOD AND MEANS FOR PRODUCTION
Abstract
A variety of textile materials comprising tapes oriented in two
oblique orientations relative to the textile's length and width
directions, called OFT for Oblique Fibre Textiles, are disclosed.
Such OFTs are provided with secondary structural
integrity/stability, in addition to primary structural
integrity/stability, for improved resistance to formation of
openings/gaps. OFTs comprising tapes, particularly Spread Fibre and
Highly Drawn Polymeric types, are needed in a number of
applications such as ballistic mitigation, composite materials,
safety products etc. because they provide improved performance,
material properties/functions and aesthetics. Such OFTs can be used
either independently or in combination with other textile
materials. Different types of OFTs are producible by a novel OFT
forming process which is technically unlike weaving and braiding
processes.
Inventors: |
Khokar; Nandan; (Goteborg,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Khokar; Nandan |
Goteborg |
|
SE |
|
|
Assignee: |
TAPE WEAVING SWEDEN AB
Boras
SE
|
Family ID: |
44872676 |
Appl. No.: |
13/979738 |
Filed: |
January 20, 2012 |
PCT Filed: |
January 20, 2012 |
PCT NO: |
PCT/EP2012/050820 |
371 Date: |
September 23, 2013 |
Current U.S.
Class: |
428/104 ;
428/124; 428/196; 442/149; 442/186 |
Current CPC
Class: |
Y10T 428/2405 20150115;
B29C 70/22 20130101; D04C 3/48 20130101; D04C 3/00 20130101; Y10T
442/3041 20150401; Y10T 428/2481 20150115; Y10T 428/24215 20150115;
D03D 41/008 20130101; D03D 13/002 20130101; Y10T 442/2738 20150401;
D04C 1/02 20130101; D03D 41/00 20130101 |
Class at
Publication: |
428/104 ;
442/186; 428/196; 428/124; 442/149 |
International
Class: |
D04C 1/02 20060101
D04C001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 20, 2011 |
EP |
11151534.2 |
Claims
1. A fabric comprising tapes, wherein a first set and a second set
of tapes are arranged in an intersecting and overlapping fashion,
the tapes of the first set and the second set being structurally
linked with each other, wherein all the tapes are arranged in
oblique orientations in relation to the fabric length direction,
said fabric further comprising, at least in a middle part of said
fabric, a plurality of connection points or connection areas
connecting at least some of the overlapping tapes of the first and
second set together.
2. The fabric of claim 1, wherein the first set of tapes are
arranged substantially parallel to each other in a first oblique
orientation in relation to the fabric length direction, and wherein
the second set of tapes are arranged substantially parallel to each
other in a second oblique orientation in relation to the fabric
length direction.
3. The fabric of claim 1, wherein the first set of tapes are, on
average, arranged in a first oblique orientation in relation to the
fabric length direction, and the second set of tapes are, on
average, arranged in a second oblique orientation in relation to
the fabric length direction, said first and second oblique
orientations being non-perpendicular to each other, thereby forming
either an acute or obtuse angle between said first and second
orientations.
4. The fabric of claim 3, wherein the tapes of first and second
oblique orientations mutually form an angle in the range 20-85
degrees or 95-160 degrees, and preferably in the range 40-80
degrees or 100-140 degrees, and most preferably in the range 60-80
degrees or 100-120 degrees.
5. The fabric of claim 1, wherein the connection points or
connection areas are provided to overlapping tapes by at least one
of: spot needling, spot entangling, spot gluing, adhesion, fusing
and spot welding.
6. The fabric of claim 1, wherein the connection points or
connection areas are distributed evenly over the fabric.
7. The fabric of claim 1, wherein the connection points or
connection areas are provided on all the tapes.
8. The fabric of claim 7, wherein the connection points or
connection areas are provided in each overlap between the tapes of
the first and second set of tapes.
9. The fabric of claim 1, wherein the plurality of connection
points or connection areas are arranged in one or several straight
connections lines, each of said at least one straight connection
lines comprising a plurality of connection points or connection
areas.
10. The fabric of claim 9, wherein at least one, and preferably
several, of the straight connection line(s) extend in the length
direction of the fabric.
11. The fabric of claim 9, wherein at least some of the straight
connection lines extend in different directions.
12. The fabric of claim 11, wherein at least some of the connection
lines extend in directions parallel to the tapes of the first and
second sets of tapes.
13. The fabric of claim 1, wherein at least some of the tapes are
either spread fibre tapes or highly drawn polymeric tapes.
14. The fabric of claim 1, wherein at least one tape is folded,
said folded tape extending in at least two different oblique
directions in relation to the length direction of the fabric.
15. The fabric of claim 14, wherein a folding of said at least one
folded tape is arranged at one side of the fabric, thereby forming
an at least partly closed longitudinal edge.
16. The fabric of claim 14, wherein foldings of at least two folded
tapes are arranged at a distance from the sides of the fabric,
thereby forming a slit opening in the fabric.
17. The fabric of claim 1, wherein the fabric is further provided
with a surface coating on at least one side by of at least some of
the tapes, said surface coating making the fabric adherent.
18. The use of a fabric according to claim 1 for at least one of
ballistic mitigation and safety products.
19. A composite material comprising a fabric according to claim 1.
Description
FIELD OF INVENTION
[0001] The inventions disclosed herein pertain in general to the
bias textiles/fabrics and their production. In particular, the
inventions relate to Oblique Fibre Textiles (OFT) comprising tapes
which are incorporated in two opposite oblique orientations.
BACKGROUND
[0002] A sheet-like fabric/textile material comprising yarns, tows,
rovings, filaments, so-called `flat` yarns and `tape` yarns etc. in
bias orientations in relation to fabric's length (or width)
direction is producible directly by the existing flat braiding
process as flat braids. A bias fabric can be also obtained
indirectly, for example, by cutting helically a tubular woven
material produced by the circular weaving process. Another indirect
way is by cutting diagonally a portion out of a large flat woven
material. A bias fabric, producible indirectly by modified weaving
method is also disclosed in U.S. Pat. No. 6,494,235. However, the
bias fabrics resulting from all these direct and indirect methods
are practically unusable because they develop openings/gaps during
handling/processing due to lack of suitable structural
integrity/stability. This critical fundamental problem needs a
suitable solution because bias fabrics are needed to bear load in
oblique directions in many applications. Further, the performance
of such bias fabrics is poor because they are not produced using
tapes, especially of the spread fiber and highly drawn polymeric
types, as a result of which such bias fabrics, comprising one or
other type of yarns (i.e. tows, rovings, filaments, so-called
`flat` yarns and `tape` yarns etc.), have relatively high crimp
frequency and angle, uneven surface, high areal weight, poor
draping, high thickness, low fibre content, fewer exposed fibres,
high openings/gaps due to improper fibre distribution, high
handling difficulties etc. due to use of one or other type of
indicated yarns. Therefore, for a variety of technical
applications, such as ballistic mitigation, a safety product,
composite materials etc., a high-performance and also functional
bias fabric/textile material, that is free from the indicated
drawbacks, is needed. Improved bias fabrics are also needed in
practically useable large widths and continuous lengths for
industrial applicability.
[0003] There is therefore a need for having a variety of novel bias
fabric materials comprising tapes, including the spread fibre and
highly drawn polymeric types of tapes, for improved performance and
structural integrity to resist formation of openings/gaps during
normal handling/processing. Also, new applications need functional
bias fabrics.
SUMMARY
[0004] It is therefore an object of the present invention to
provide a bias fabric comprising tapes to alleviate the
above-discussed problems of the prior arts.
[0005] This object is achieved by means of a fabric as defined in
the appended claims.
[0006] According to a first aspect of the invention, there is
provided a fabric comprising tapes, wherein a first set and a
second set of tapes are arranged in an intersecting and overlapping
fashion, the tapes of the first set and the second set being
structurally linked with each other, wherein all the tapes are
arranged in oblique orientations in relation to the fabric length
direction, said fabric further comprising, at least in a middle
part of said fabric, a plurality of connection points or connection
areas connecting at least some of the overlapping tapes of the
first and second set together.
[0007] The fabric is preferably elongate, i.e. it has a length
which is longer than the width, whereby the fabric length direction
coincides with the elongated direction. Further, the fabric length
direction preferably coincides with the production direction in
which the fabric has been produced.
[0008] Hereby, the two sets of tapes that are obliquely oriented in
relatively opposite directions with respect to either of the two
representative diagonals, which could be either equal or unequal
(major and minor), of any of the unit quadrilaterals that are
created by overlapping of intersecting tapes. Further, one of the
two representative diagonals could be more or less parallel to the
fabric-length direction.
[0009] The first set of tapes are preferably arranged substantially
parallel to each other in a first oblique orientation in relation
to the fabric length direction, and the second set of tapes are
preferably arranged substantially parallel to each other in a
second oblique orientation in relation to the fabric length
direction.
[0010] Further, the first set of tapes are, on average, preferably
arranged in a first oblique orientation in relation to the fabric
length direction, and the second set of tapes are, on average,
preferably arranged in a second oblique orientation in relation to
the fabric length direction, said first and second oblique
orientations being non-perpendicular to each other, thereby forming
either an acute or obtuse angle between said first and second
orientations.
[0011] The first and second oblique orientations preferably
mutually form an angle in the range 20-85 degrees or 95-160
degrees, and even more preferably in the range 40-80 degrees or
100-140 degrees, and most preferably in the range 60-80 degrees or
100-120 degrees.
[0012] The connection points or connection areas are preferably
provided to overlapping tape areas/portions by means of at least
one of: spot needling, spot entangling, spot gluing, adhesion,
fusing and spot welding.
[0013] The connection points or connection areas are preferably
formed without using any extra yarn or the like. Further, the
connection points/areas are preferably arranged to remain flat,
thereby not adding to the thickness of the fabric. Hereby, the
connection points/areas do not create surface unevenness in the
fabric by way of including extra yarns or the like.
[0014] The connection points or connection areas are preferably
distributed evenly over the fabric.
[0015] The connection points or connection areas are preferably
provided on all the tapes.
[0016] The connection points or connection areas are preferably
provided in each overlap between the tapes of the first and second
set of tapes.
[0017] The connection points or connection areas preferably form
discrete points/areas, being unconnected to each other apart from
being applied to the same fabric. Further, the connection points or
connection areas are preferably discontinuous between the
corresponding quadrilaterals along their diagonal directions, and
preferably do not connect the quadrilaterals formed by the
overlapping and intersecting tapes of the fabric to one
another.
[0018] The plurality of connection points or connection areas are
preferably arranged in one or several straight connection lines,
each of said at least one straight connection lines comprising a
plurality of connection points or connection areas. Preferably, at
least one, and most preferably several, of the straight connection
line(s) extend in the length direction of the fabric. It is also
preferred that at least some of the straight connection lines
extend in different directions. It is also preferred that at least
some of the connection lines extend in directions parallel to the
tapes of the first and second sets of tapes. Preferably, the
connection areas can vary from one or several points to adhesion
covering entire area of the overlapping tapes.
[0019] According to one embodiment, at least some of the tapes are
either spread fibre tapes or highly drawn polymeric tapes.
[0020] It is further preferred that at least one tape is folded,
said folded tape extending in at least two different oblique
directions in relation to the length direction of the fabric. The
folding of said at least one folded tape may be arranged at one
side of the fabric, thereby forming an at least partly closed
longitudinal edge. Foldings of at least two folded tapes may
further be arranged on different sides of the fabric, thereby
forming at least partly closed longitudinal edges on two sides of
the fabric. Further, foldings of at least two folded tapes may be
arranged at a distance from the longitudinal edges of the fabric,
thereby forming a slit opening in the fabric.
[0021] The fabric is further preferably provided with a surface
coating on at least one side of at least some of the tapes, said
surface coating making the fabric adherent.
[0022] Preferably, the discrete length of each of the tapes is
longer than the width of the fabric. It is also preferred that the
discrete length of each of the tape is shorter, and preferably
substantially shorter, than the length of the fabric.
[0023] According to another aspect of the invention, there is
provided a use of the above-discussed fabric for at least one of
ballistic mitigation and safety products.
[0024] According to still another aspect of the invention, there is
provided a composite material comprising a fabric of the
above-discussed type.
[0025] The present inventions provide novel bias fabrics producible
directly using all types of tapes, including the spread fibre and
highly drawn polymeric types, and which preferably present the
following features, either independently or in certain
combinations: [0026] Discrete lengths of tapes are incorporated in
two angular orientations in relation to fabric-length direction;
[0027] The discrete lengths of tapes constituting the bias fabric
are either equal or unequal depending on whether the angles of
their incorporation relative to fabric's longitudinal direction are
equal or not. [0028] The discrete length of tapes are longer than
the width of the bias fabric's body; [0029] The discrete tapes are
in either straight or folded-straight forms; [0030] The bias
textile material possesses directionally oriented secondary
structural integrity/stability, in addition to the primary
integrity/stability, to resist developing openings/gaps during its
manufacturing and subsequent handling/processing; [0031] The tapes
constituting the bias textile material, particularly the spread
fibre and highly drawn polymeric types, provide uniform thickness,
lower areal weight, thinner and wider construction exposing
relatively greater number of constituent filaments/fibrils in
comparison with conventional yarns, tows, rovings, filaments,
so-called `flat`/tape yarns etc.; [0032] The bias fabric has either
open longitudinal edges, or both longitudinal edges partly sealed,
or one longitudinal edge wholly sealed; [0033] The bias fabric is
provided with either longitudinally or laterally oriented slits
without cutting the tapes and the associated fibre discontinuities;
and [0034] The built-in slits in the bias fabric are located either
along the fabric's longitudinal axis or offset from the
longitudinal axis.
[0035] The need for having bias fabrics incorporating tapes,
particularly the spread fibre and highly drawn types, instead of
yarns, tows, rovings, filaments, so-called `flat` yarns and `tape`
yarns etc., is not only to make available a textile material that
exhibits strength in two oblique directions relative to the
textile's length and width directions, but also to realize certain
other important performance, functional and commercial advantages.
Accordingly, novel bias fabrics, which are hereinafter commonly
referred to as OFT for `Oblique Fibrous Textiles`, are provided
herewith. That the features of OFT disclosed herein are technically
different from the available bias fabrics will become clear in the
following.
Differences Between the Invention and the State of Art Relating to
Material
[0036] From the foregoing description it would be obvious that
textile materials in the form of OFT are preferred for
manufacturing a variety of composite materials, ballistic
mitigation products, safety products (e.g. parachutes,
wall-strengtheners) etc. For all these technical applications
presently woven materials comprising yarns, rovings, `flat` yarns,
tape yarns, tows etc. are extensively used for their unique
weave-structure performance advantages compared with the knitted
and non-woven materials. Flat braided materials are not practically
producible in large widths that are generally preferred for
industrial/technical applications and hence their applicability is
also insignificant. However, woven materials provide strength in
only warp and weft directions (i.e. fabric length and width
directions respectively), and undergo shear deformation if forces
are applied in oblique/angular/bias directions relative to the warp
and weft directions.
[0037] Composite materials, ballistic mitigation products and
safety products are produced by plying sheets of woven materials in
relatively different orientations to realize a product that can
bear load from different directions. However, such plying of woven
sheets in different orientations makes it imperative to cut smaller
parts from a larger woven sheet. The bias-oriented cut woven sheet
is thus a discontinuous material that limits the possibilities of,
for example, continuous inline automated pre-pregging and
production of items requiring no discontinuities of either fibres
or fabric structure in the required area/s of the product, for
example when constructing the belly and wings of an aircraft. The
precision of cutting and plying operations depends on the skills of
the workers whereby achieving consistent quality becomes impossible
in an industrial setting. Further, the production time, labour and
costs tend to increase in a discontinuous process in addition to
generation of substantial waste material which adversely impacts
the environment. Today there is no suitable continuous bias textile
material available that resists developing openings/gaps, provides
performance and functions, and is useable for overcoming the
indicated problems in a practicable way.
[0038] Apart from having a continuous running length and
practically useful width of bias textile material that provides
strength in two oblique directions relative to textile's length (or
width) direction, there are certain other important performance and
function related technical demands that an OFT must also fulfill.
These material related demands cannot be fulfilled with available
materials and methods of bias fabric production as presented
below.
[0039] (a) Uniformly tensioned constituents of an OFT: Filaments,
yarns, tows, rovings, so-called `flat` yarns and `tape` yarns etc.
(hereinafter collectively called `flat` yarns) that occur
relatively highly tensioned than others in a fabric intended
particularly for technical application are mainly responsible for
causing material failure. This is because fabrics in technical
applications are invariably subjected to a variety of forces from
different directions and the fibres that occur most tensioned
within the fabric are the first ones to break/fail under certain
load/force. Such fibre breakages trigger the onset of eventual
fabric failure as the next highly tensioned fibres have to
successively bear the load and breakage of fibres progresses until
finally a complete material failure results. The catastrophic
consequences of fabrics comprising tensioned fibres in applications
such as composite materials, ballistic protection, parachutes etc.
cannot be over emphasized.
[0040] As is well known, the weaving, knitting and braiding
processes introduce tensions and related problems in fabrics. This
is because the inherent working design of these conventional
processes requires the input fibres to be maintained constantly
under certain tension for their satisfactory working and also for
the machine's satisfactory operations. Invariably, the input fibres
are required to be supplied in large sized and number of packages
such as spools, beams, cones, cheeses etc. because the fabrics are
required to be produced in large, but definite, continuous lengths.
Such long lengths of input fibres invariably have tension
variations in them because they cannot be completely controlled for
a variety of technical and human reasons.
[0041] The existing fabric-forming processes thus inevitably start
with unequally tensioned input fibres and induce additional
tensions in the input fibres during fabric's production as the
fibres interact with a variety of moving machine parts. Such
tensions keep on increasing until the fibre's breaking point is
reached (whereby the discontinuity of fibres causes fabric faults).
Maintaining constantly equal tension in all fibres during fabric
production is thus impossible in existing processes. It will be
therefore desirable to have a fabric-forming process for
manufacturing OFT in which additional tension variations are not
induced in the fibres of the OFT during production to improve
material's performance. For such a process to be practically
viable, it should be able to produce OFT continuously using
specified discrete lengths of individual fibrous material in a
suitable form without requiring the constituent fibres to be always
under tension as a condition for fabric production. The present
invention provides a novel method and means for obtaining
innovative OFTs the constituent tapes of which occur completely
tensionless.
[0042] (b) Relatively lower areal weight and thinner OFT: Fabrics
are now being increasingly demanded for achieving further weight
reductions and improved draping in the said technical applications.
For example, it is becoming important now to reduce the dead-weight
of a composite material, i.e. the weight of the excess matrix that
gets collected in the valleys of the weave crimp of traditional
woven materials. This excess matrix does not contribute to anything
useful. Its collection in the valleys of weave crimp happens
because the traditional yarns and the so-called `flat` yarns/`tape`
yarns/tows/rovings are inherently thicker in the middle than at the
edges (i.e. having ellipse-like or flat oval/race track-like
cross-sectional shape) due to the uneven fibre distribution in the
width direction of the roving/yarn/`flat` yarn/`tape` yarn/tow. As
a consequence of their relatively narrow width and high thickness,
the crimp frequency and crimp angle in the fabric tend to be
significantly high as a result of which the fabric exhibits a
relatively higher areal weight, higher mean thickness and an uneven
surface resulting from peaks and valleys of crimp. These and other
shortcomings can be overcome by producing OFT using Spread Fibre
Tapes (henceforth called SFT) because such tapes are extremely
uniform in thickness due to its structure and they are also
substantially thin whereby the crimp frequency and crimp angle can
be virtually eliminated. An OFT produced using tapes, such as SFT,
has previously not been known.
[0043] (c) Structurally stable OFT: Because available bias fabrics
do not have fibres oriented in fabric's length and width directions
(like a woven fabric), its structure can easily open up or form
gaps, even narrow down, during manufacture and handling such as
that encountered normally when forces act on it longitudinally and
laterally. Whereas in a woven fabric the warps easily slip out from
selvedge sides if not properly integrated/locked-in with wefts
leading to initiation of openings/gaps closer to selvedges than
middle part, in bias fabric the situation is entirely different
because there is no material that runs adjacent and parallel to its
longitudinal sides to slip out. In bias fabric the openings/gaps
are initiated in a middle part of the fabric instead of its
longitudinal sides. For example, a certain length of a bias fabric
easily develops openings/gaps, initially in its middle part, under
its own weight when passed over two horizontal rolls. Formation of
openings/gaps in middle part of bias fabric happens even if its
longitudinal sides are closed/sealed as it sags most in middle part
as the constituent materials there tend to shift laterally. The
mechanism of formation of openings/gaps in woven and bias fabrics
is hence characteristically different and requires correspondingly
different solutions to overcome the problems.
[0044] Further, while use of tapes for producing OFT is considered
beneficial as mentioned above, its use also means relatively lower
frequency, or fewer points, of connections between the tapes,
compared with the use of indicated yarn types (i.e. rovings,
filaments, tows, so-called `flat` yarns and `tape` yarns, etc.),
because such tapes will be relatively wider than any type of
indicated yarns. Because the use of tapes will entail infrequent or
fewer connections between tapes, there will be a correspondingly
reduced stability of the fabric structure, whereby openings/gaps
will be easily created when handling/processing them. An OFT
produced with tapes can be thus practically difficult to use.
[0045] Therefore, to obtain a satisfactory OFT, certain additional
directionally oriented secondary structural integrity/stability,
apart from its primary structural integrity/stability, becomes
necessary to impart, at least in its middle part, for improved
resistance to lateral shifting and developing openings/gaps to
render it practically useful. It is also important that an OFT
exhibits similar structural features in its length and width
directions. A uniform thickness OFT is also necessary for realizing
satisfactory products, e.g. ballistic impact mitigation, composite
materials etc. All these requirements can be met by imparting OFT a
secondary structural integrity/stability, in addition to the
primary structural integrity/stability, through a directionally
oriented consolidation procedure. While the primary stability would
come naturally from the manner by which the process organizes and
assembles the tapes in the OFT, the secondary structural stability
additionally imparts strength in OFT's thickness direction by
methods such as spot entangling/needling for fibre migration, spot
gluing, adhesion, fusing, spot welding etc., depending on the tape
material being processed, to improve OFT's resistance to formation
of openings/gaps. The secondary structural integrity/stability
imparted to an OFT can be directionally oriented for providing low
to high level resistance to forming of openings/gaps, applied in
areas where preferred, and suitably dimensioned from a point to a
larger area according to the requirements of a given application.
An OFT that is made of tapes and is structurally well integrated
and stable through secondary integrity/stability has previously not
been known.
[0046] (d) Functional OFT: Previously there has been available no
bias fabric that is functional in any way. Due to the inherent low
load-bearing strength in its length and width directions, an OFT
should incorporate certain features that will enhance its use
functionally. For example, it should be capable of being applied
easily and quickly in applications such as reinforcing heritage
buildings and rapidly deployable impact resistant vehicles. In
applications where an OFT would be required to be suspended, such
as to cover hangar and stadium, it should have built-in arrangement
that can facilitate its use directly and easily. Also, for properly
guiding OFT during processing, for example coating, it should be
provided with at least one sealed linear longitudinal edge.
Accordingly, the OFT disclosed herein addresses such functional
issues by way of being provided with suitable features, such as
adhesive that enables it to adhere to surfaces, sealed linear
longitudinal edge, and built-in slits that allow it to be
mechanically connected by passing bands through the slits. An OFT
offering such functionalities has previously not been known.
[0047] An OFT comprising SFT will also exhibit additionally, not
only a lower areal weight, but also highly straight and parallel
constituent filaments that are oriented in tape's length direction,
and greater number of exposed filaments for easier and quicker
wetting (these features are considered now to be imperative
requirements for many technical applications, particularly where
fibres are required to be coated/embedded). By producing an OFT
using SFT in a manner that SFT is not subjected to unceasing
tension as a condition for fabric production, the
requirements/demands can be substantially and directly
fulfilled.
[0048] Further, an OFT composed of thermoplastic material, in the
forms of Highly Drawn/Stretched Polymeric Filaments and Highly
Drawn/Stretched Polymeric Tapes (hereinafter collectively referred
to as HDPT), can be also considered for bearing enormous
loads/forces because of their highly straightened, parallel and
uniformly distributed constituent molecular chains (which can be
considered akin to SFT). For example, an OFT comprising HDPT can
bear impact loads in the two oblique directions relative to the
fabric's length and width. An OFT produced using HDPT has
previously not been known.
[0049] While carbon fibres are extensively used as reinforcements
in the manufacture of composite materials, certain polymeric
materials are the choice materials for ballistic mitigation
application. Such polymeric materials could be either HDPT or
highly drawn polymeric fibres made in the form of an SFT.
[0050] An OFT comprising either SFT or HDPT or their combinations
and also a process and means for producing OFT, have previously not
been known. A background for explaining advantages of OFT produced
using either SFT or HDPT or their combinations and its practical
significance in industry are presented below.
[0051] Carbon fibres are widely used in the form of yarns, rovings,
tows, so-called `flat` yarns and `tape` yarns etc. to produce a
variety of fabric areal weights. For example, at present low areal
weight woven fabrics are usually produced by weaving low count tows
such as 1k and 3k (wherein k designates 1000 filaments). Higher
count tows produce correspondingly heavy areal weight woven fabrics
with a corresponding increase in uneven surface and mean fabric
thickness, which are undesirable from the point of increasing the
dead-weight of composite material as explained earlier. On the
other hand, woven fabrics produced using lower tow counts are many
times more expensive than those produced using higher tow counts in
addition to the said problems. Their drawbacks are only relatively
lower in magnitude. It is therefore necessary that for reducing the
fabric cost, the relatively lesser expensive fibres of higher tow
counts be used while at the same time low areal weight and
high-performance fabrics be realized.
[0052] Similarly, different polymeric materials are used in the
form of `flat` yarns of different counts (tex, denier), to produce
different areal weights of fabrics. As explained above, fabrics
made using higher count `flat` yarns of polymeric materials exhibit
correspondingly heavy areal weight fabrics, uneven surface and
increased mean thickness of the fabric, and thus have relatively
lower performance.
[0053] The filaments constituting the tows/rovings/`tape`
yarns/`flat` yarns etc. are given a light twist for keeping them
together for handling convenience. Hence filaments of a tow have
some freedom to shift laterally. As a consequence, the tows undergo
change in their cross-sectional shape when subjected to pressure,
like when bending over a cylinder. In fact the tows in their bobbin
form appear `flat` (the cross-section being generally represented
as flat oval or race track-like), unlike yarns which are generally
regarded to be either circular or oval in cross-section. Such
yarns/rovings/tows/`tape` yarns/`flat` yarns etc., which are
generally referred to as `flat` yarns/`tape` yarns, are known to be
not truly flat because of inherent uneven distribution of the
constituent filaments whereby the thickness of the so-called `flat`
yarn in the mid flat region of its cross-section is significantly
greater than that at the edges.
[0054] Further, the filaments constituting the
yarn/roving/tow/`tape` yarn/`flat` yarn do not run linearly and
parallel to tow's/`tape` yarn's/`flat` yarn's length
direction--there is a constant internal crisscrossing of fibres.
This haphazard arrangement of filaments is one of the main reasons
for tension variations within these `flat` yarns. Also, there is a
limit to how flat and wide a `flat` yarn can be made when subjected
to pressure. The `flat` yarn on a bobbin is already `flat` and wide
to the maximum. Such rovings, yarns, tows, so-called `flat` yarns
and tape yarns etc. are therefore generally called `flat` yarns,
`tape` yarns etc. For all practical purposes, these `flat`/`tape`
yarns are extensively used and treated as they are, i.e. just like
conventional yarns, for example in weaving and braiding processes
to produce fabrics for different applications. These processes
require practically no modifications for handling such
`flat`/`tape` yarns. The fabrics produced using such
`flat`/`tape`yarns that have crisscrossing fibres/filaments and
uneven thickness are therefore possessed of drawbacks and
associated problems described in the foregoing.
[0055] Spread Fibre Tape (SFT), as the name indicates, is produced
by spreading the constituent filaments/fibres of a `flat` yarn. As
a consequence, a relatively thinner and wider material in tape form
is obtained. The degree of fibre spreading is done according to the
application needs and also in accordance with the areal weight of
the fabric to be achieved. Thus, the lower the areal weight is
desired, the higher will be the degree of spreading the
filaments/fibres of the `flat` yarn (of course up to a practical
limit). Such spreading will result in a wider, thinner and a highly
uniform thickness fibre tape due to the highly uniform distribution
of fibres. An important consequence of such spreading action is
that the inherent internal crisscrossing or migration of
fibres/filaments and false twists etc. within the `flat` yarn get
eliminated and the filaments/fibres become highly linear, parallel
and oriented in the tape's length direction. Such a highly
organized arrangement of filaments/fibres renders the SFT free from
inherent tension variations arising from defects such as internal
twists, crisscrossing of filaments and uneven fibre distribution.
Another very important outcome of spreading the fibres of the
`flat` yarn is that the resulting SFT has well-distributed
fibres/filaments and exposes relatively more number of filaments
than the parent `flat` yarn. An SFT, being thinner and wider, is
thus very flimsy and delicate compared to its parent `flat` yarn.
Clearly SFT is structurally different from the yarns, rovings,
tows, so-called `flat` and `tape` yarns etc. Accordingly, an SFT
cannot be handled and treated in the same way as the `flat`/`tape`
yarn is treated.
[0056] Typically, for a given count of roving/tow/`flat`
yarn/`tape` yarn, and the degree of spreading performed, the
comparative thickness of SFT could be at least 50% lower, the width
at least 50% greater, and the number of exposed filaments at least
50% greater than that of the parent `flat`/`tape` yarn. U.S. Pat.
No. 3,795,944, U.S. Pat. No. 5,042,122 and U.S. Pat. No. 5,057,338,
U.S. Pat. No. 4,994,303, U.S. Pat. No. 5,094,883, U.S. Pat. No.
5,101,542, U.S. Pat. No. 5,200,620, U.S. Pat. No. 6,049,956, U.S.
Pat. No. 6,032,342 and JP 3382603 are examples of different
processes specifically developed for spreading the filaments of a
roving/tow/`flat` yarn/`tape` yarn etc. It will be clear now to the
practitioner of art that SFT and yarns, rovings, tows,
`flat`/`tape` yarns etc. are characteristically structurally
different and hence they exhibit different features in terms of
thickness, areal weight, linearity and parallel disposition of
constituent filaments/fibres and the number of exposed
filaments/fibres.
[0057] As mentioned earlier, an SFT has a fragile or delicate
structure and hence requires greater care and different handling
arrangements than those required for rovings/tows/`tape`
yarns/`flat` yarns. This is because any mishandling and unbalanced
forces will collapse SFT back into a yarn, roving, tow,
`flat`/`tape` yarn etc. Clearly SFT cannot be processed in the same
way as a yarn, roving, tow, `flat`/`tape` yarn etc. An OFT produced
using SFT will be therefore advantageous because they will be
naturally free from criss-crossing fibres, twists etc., and hence
free from inherent tensions, besides being of relatively lower
areal weight, greater surface evenness, flatness and lower mean
fabric-thickness than the fabric comprising yarns, rovings, tows,
`flat`/`tape` yarns etc. Further, as an OFT made using SFT will be
relatively thinner, they can be draped into desired shapes
relatively easily. Furthermore, because OFT comprising SFT will
have relatively more number of well-distributed and exposed
filaments, a correspondingly higher and quicker wetting of fibres
will be enabled when coated or embedded. Most importantly, because
SFT comprises filaments/fibres that are linear, well-distributed
and parallel, the OFT produced using them shall have uniform
tension if the fabric-forming process is such that it does not
require constant tensioning of SFT as a condition during production
of OFT.
[0058] Further, because of their relative thinness and large width,
an OFT incorporating SFT will be substantially flat and have
virtually no crimp. Also, due to the thinness and flatness of SFT,
the OFT will have substantially lower mean thickness resulting in
virtually no dead-weight matrix accumulation. As a consequence, the
problem of dead-weight of composite materials will be substantially
reduced, if not wholly eliminated. A composite material
incorporating SFT will perform better because of the relatively
higher wetting (i.e. adhering) of the well-distributed and exposed
filaments by the matrix. The adhesion of greater number of
filaments to the matrix will result in correspondingly increased
distribution and transference of loads from the matrix to the
fibres when the composite material is subjected to loading/forces,
whereby improved performance will result.
[0059] The advantages described above for SFT can be also
correspondingly found with the use of HDPT. When polymeric sheets
are highly drawn/stretched, their molecular chains tend to become
correspondingly highly stretched, straighter, parallel,
well-distributed and oriented in the length direction of the
sheet/tape. Also, during the drawing/stretching process the
molecular chains slide past each other laterally and result in an
extremely thin (measurable in terms of micrometer) sheets or tapes.
Such HDPT can be thin to the point of becoming translucent, if not
transparent (depending on the type of polymeric material drawn).
These highly linear molecular chains, called fibrils, thus occur on
the surface of the ultra thin HDPT. In fact such fibrils directly
adhere to an ordinary adhesive tape and peel off readily from the
surface of HDPT as extremely fine filaments and can be considered
something akin to the exposed fibres in SFT. Due to such high
linearity of the molecular chains an HDPT can bear relatively high
impact loads.
[0060] To enlarge the scope of practical usefulness from the
indicated benefits of SFT and HDPT it is naturally desirable to
compose an OFT with not only tapes that exhibit relatively uniform
thickness, low areal weight, highly straight and parallel
constituent filaments/fibrils and greater number of
well-distributed exposed filaments/fibrils, but also by employing a
fabric-forming process that will not require constant or unceasing
tensioning of SFT and HDPT as a condition during OFT production. An
OFT of the described foregoing features and functions, and its
method and means for production, as well as applications and
advantages, have previously not been known.
[0061] To bring forward the novelty of OFT according to this
invention, relevant known bias materials available through
different ways of manufacture are cited below. As shall be noticed
in due course, these known fabrics and their methods of production
are characteristically different from the present inventions.
Differences Between the Invention and the State of Art Relating to
Process
[0062] It would be apparent from the foregoing description that OFT
production requires a completely new approach. The limitations of
existing methods are explained below.
[0063] Although the flat braiding process directly creates a narrow
fabric by incorporating obliquely yarns, rovings, tows,
`flat`/`tape` yarns etc., its working arrangement cannot produce an
OFT using tapes, including SFT, HDPT and their combinations without
distorting/crumpling them. The braiding process is therefore
irrelevant to consider any further in the context of the present
invention.
[0064] A fabric piece comprising either yarns or rovings or tows or
`flat`/`tape` yarns etc. in oblique orientations in relation to its
length (or width) direction can be obtained indirectly by cutting
out obliquely a portion from a larger woven material and called a
`bias` material. However, such a material then has poor strength in
its length and width directions and cannot be handled ordinarily as
it easily develops structural openings/gaps. Also, as is well
known, constant tensioning of warp and weft is indispensable for
processing them in the weaving process. Also, the tensions in the
warp and weft directions are never equal. Therefore, a woven
material will inherently continue to suffer from the effects of
tension differences in the fibres of the warp and weft directions
induced by a variety of weaving process variables controlling each
of them. Such tension-related defects are either visible (for
example, one or more warps, or wefts, appearing `tight` with
different crimp level compared to others, flat appearance due to
stretching, breakage/discontinuity/fibre pull-out etc.) or
determinable (for example, by measuring lengths of fibres of warps
or wefts, observing behaviour under certain conditions of
heat/humidity/wetting, and by loading fabric to the point of first
fibre breakage etc.). Such effects of tension-related defects
continue to remain even in the woven fabric even after it has been
taken off the weaving machine due to locking-in of yarns, rovings,
tows, `flat`/`tape` yarns etc. by interlacing. These inherent
tension related defects are unacceptable for critical technical
applications. Obviously, an obliquely cut `bias` piece of fabric
obtained from a large woven material will inherit the same
tension-related defects and shortcomings and will perform poorly in
the desired technical applications. Most importantly such a `bias`
material will have no secondary structural integrity/stability, for
example that accorded by spot entangling/needling, adhesion, fusion
etc., in its middle part making its handling and processing
impossible. Also, such a fabric will not be functional in any
way.
[0065] Further, because such a woven `bias` material is cut out
from a large woven fabric, it will be small and of finite area
making it of little practical use and value. It will not enable,
e.g., continuous inline automated pre-pregging and production of
items requiring continuity of fibres and fabric structure.
Moreover, in such a bias material the 90.degree. relationship
between the warp and the weft of a woven fabric will always remain
unaltered. An important limitation with the approach of cutting out
pieces from a large woven material is the non-availability of
practically useable continuous and wide bias materials. Cutting
narrow strips and pieces and placing them together will still have
fibre discontinuities and also fabric structure discontinuities.
Also, the woven material from which the bias piece is cut out
becomes a waste.
[0066] Clearly, the woven material is characteristically different
from the preferred OFT and the existing flat weaving processes
cannot be employed to produce OFT.
[0067] The traditional circular weaving process provides an
indirect solution for obtaining a continuous bias material. A woven
tubular fabric could be cut helically as disclosed in U.S. Pat. No.
4,299,878. Upon opening and laying the helically cut material flat,
a long-length material comprising yarns in angular orientations in
relation to its length and width directions is obtained. However,
such a woven tubular fabric can be produced using only
yarns/rovings/tows/`flat`/`tape` yarns etc. and not tapes,
including SFT and HDPT types, because the working arrangement of
the circular weaving process cannot handle and process tapes,
without introducing twists and other deformations. Their handling
requires new techniques which have previously not been known.
Moreover, the helically cut `bias` material cannot be free from the
tension-related defects because the circular weaving process
requires unceasing tensioning of the yarns, rovings, tows,
`flat`/`tape` yarns etc. during processing.
[0068] Clearly, the circular weaving process cannot handle tapes,
especially SFT and HDPT types, to produce tubular OFT from which a
bias material could be obtained by helical cutting. This process is
therefore irrelevant to consider any further.
[0069] U.S. Pat. No. 6,494,235 describes an indirect method for
producing a bias fabric comprising `flat` yarns. The described bias
fabric is produced indirectly by modifying the conventional weaving
procedures. While the described modified weaving process could
perhaps process yarns/rovings/tows/`tape` yarns/`flat` yarns etc.
with difficulty, it definitely cannot process tapes, especially of
SFT and HDPT types, as explained below. Moreover, because the
indicated bias material is produced indirectly by employing the
weaving process, there will be the inherent tension differences in
the warps and wefts. Such a bias fabric composed of `flat` yarns
and produced by the traditional weaving procedures will have
tension-related defects and shortcomings discussed earlier and
hence are unsuitable for use in technical applications. As with the
other bias materials described in the foregoing, such a bias
material also has no secondary structural integrity/stability and
they are thus prone to readily develop openings/gaps. It also has
no functional features.
[0070] It will be apparent to one skilled in the art that the
weaving arrangements described in U.S. Pat. No. 6,494,235 for
producing a bias fabric are impracticable for the following
reasons.
[0071] (a) It produces the bias fabric using `flat` yarns by
drawing it out from only one spool/source. Thus, the warps are
drawn out one length at a time and fed one by one into the nips of
two parallel belt drives so as to continuously cyclically create a
working warp sheet. Apparently, a warp set up is performed and the
individual `flat` warp yarns can never be had close to each other
as is normally required for obtaining a satisfactory high fibre
content performance material. The resulting woven fabric will be
thus loose and already have openings/gaps. Further, because all the
`flat` yarns are drawn out from only one supply source, the bias
fabric can never be composed of two or more different materials,
and the process cannot be efficient.
[0072] (b) The two distanced belt drives can never keep the
spanning length of `flat` warp yarns taut enough from sagging under
its own weight. `Flat` warp yarns hanging in the middle section of
the two belt drives will sag relatively more than those at the
entry end side as the gripping force in the belts' middle section
will be relatively lower. Consequently, the `flat` warp yarns will
be differently tensioned and also be of different lengths making
the process' working difficult, if not impracticable.
[0073] (c) The `flat` warp yarns held between the two belts, will
tend to slip out from the belts due to pulling when subjected to
shedding. There is also no tensioning arrangement provided therein
to level the warp yarns after the shed closes. As a consequence,
the `flat` warp yarns will remain loosely hanging when the shed
closes and cause difficulties in subsequent operations,
particularly the subsequent shedding whereby the weaving process
cannot proceed any further satisfactorily.
[0074] (d) The `flat` yarn warps are not threaded through any heald
eye for shedding because they are required to flow in the direction
of the fabric width (from entry selvedge side to the opposite)
every cycle and each one of them should come into its specific
position to be lifted up by the shedding arrangement. This is
practically never achievable because the loose and sagging `flat`
warp yarns will never come clearly into those individually required
specific shedding positions. Consequently, when the shedding
arrangement operates, the said vertical `combs` would tear through
the misaligned `flat` warp yarns and will never properly lift them
up. The risk of `flat` warp yarns getting
damaged/narrowed/deformed/entangled in the shedding process is thus
unavoidable. Further, the loose `flat` warp yarns would get caught
with the shedding arrangement that is located under them and
thereby pulled out from the two belts that hold and drive them. An
improper shed will obstruct weft insertion and cause weaving
difficulties and halt the process.
[0075] (e) In this process the farthest (i.e. at the selvedge)
`flat` warp yarn from the feeding side of the `flat` warp yarns in
the two belt drives is subsequently used as the `flat` weft yarn.
To draw this last `flat` warp yarn into the created shed as a weft,
it has to be gripped by a gripper. Such a `flat` weft yarn, which
is initially occupying the position of the last `flat` warp yarn,
is inherently disposed at right angle orientation to the weft
drawing-in direction of the weft gripper. When the gripper draws
the `flat` weft yarn into the shed, the trailing end of the weft
(which just functioned as warp) will slip out from the nip of the
corresponding drive belt and there will be no control over the
released `flat` weft yarn. As a consequence, the `flat` weft yarn
will snarl/twist/curl etc. and get deformed immediately due to
inherent tension variations in the `flat` yarn and thereby create
weaving difficulties as a result of which the `flat` yarn cannot be
incorporated flatly and without twist. Also, the length of such a
weft will be a constant and more or less equal the width of the
warp sheet. Hence the warp length will roughly equal the fabric
width produced at the instant.
[0076] (f) Although a guiding pin/finger is provided for the `flat`
warp yarn to change its direction by 90.degree. when drawn into the
shed as a `flat` weft yarn that is held by the gripper, its bending
around the pin will cause further twist/deformation to the `flat`
weft yarn (which is also indicated therein; column 12, lines 49-52)
as the gripper draws it into the shed. The `flat` yarn weft will
also get deformed by the gripper itself because part of it will
remain gripped in its earlier `feeding` direction/orientation (as a
warp it is at 90.degree. to weft insertion direction) and remainder
of it will be bent 90.degree. in the `drawing into shed`
direction/orientation. A solution to this problem, arising from the
use of guiding pin/finger, is also proposed therein (`associating a
finger with a tongue`; column 12, lines 53-57), but that is also
impracticable. By the provided alternative arrangement, the free
segment of the leading side of the `flat` weft yarn is required to
be wrapped around the pin by the tongue to change its direction by
90.degree.. If this free segment of `flat` weft is already held by
the weft gripper then it is impossible to carry out its wrapping
about the pin because it is not free anymore (from the weft
gripper) to wrap/enfold about the pin. If the free segment is not
held by the gripper then after the tongue wraps the `flat` weft
yarn about the pin (to change direction by 90.degree.), the weft
gripper will not be able to contact, receive and grip the free
segment of `flat` weft because its orientation will no more be at
right angle to the weft gripper anymore as before. Also, the
gripping position of the `flat` weft yarn's free segment when
wrapped about the pin will shift from its earlier straight (i.e.
not wrapped) position when the gripper can engage it. As a
consequence, the gripper cannot engage the wrapped free segment of
the `flat` weft yarn in the 90.degree. bent orientation whereby
weaving cannot proceed. Further, the wrapping action of `tongue`
will cause damage to, and deformation of, the `flat` weft yarn.
[0077] (g) The described arrangement for beating-up the `flat` weft
yarn is a combination of `combs` that are fixed vertically to the
shedding bars as described therein. However it performs the
beating-up in the conventional reciprocating manner whereby the
inserted `flat` weft yarn is beaten towards the fabric-fell
position. Such a beating action cannot process a weft tape,
especially one that is fragile/delicate such as SFT and HDPT types,
because it will immediately cause lateral crumpling and narrowing
of the weft tape and hence damage/deform it. Obviously the
described weaving method cannot process tapes, including SFT and
HDPT types.
[0078] (h) The selvedge produced is of the `tucked-in` type as the
`flat` weft yarn already exists as a pre-cut `flat` warp yarn.
However, such a selvedge creates non-uniform fibre distribution in
the woven material because the folded-in/tucked-in length of `flat`
weft is only for a small distance inside the selvedges whereby more
fibre gets incorporated at the selvedge sides than in the remainder
part/body of the produced fabric. Such uneven fibre distribution
readily lends itself to low pick/weft density and thereby creation
of openings/gaps in the produced woven fabric. Also, because the
warp and weft are of the same material, there is no possibility of
incorporating relatively lower `flat` yarn count at the selvedges
to compensate for achieving higher weft packing as is the usual
practice when producing tucked-in selvedge during usual weaving.
Whereas the tucked-in selvedge is formable using
yarns/tows/rovings/`flat`/tape yarns etc. by folding it adjacent to
itself, it cannot be employed to fold a tape over itself in the
same manner to create the selvedge. Doing so will crumple/deform
the tape and also cause the selvedges to be doubly thicker.
[0079] (i) The described take-up arrangement advances first the
just produced woven fabric in the laid `flat` yarn weft's width
direction, and then winds the fabric at an angular direction, to
the fabric fell and not directly in its direction of
advancement/fabric-length. Clearly, fabric winding performed at an
angle to the fabric-fell misaligns/off sets fabric take-up and thus
angular winding arrangement will naturally cause structural
deformation of the produced woven fabric due to the unbalanced
forces acting on the produced fabric. To overcome this shortcoming,
extra yarns in fabric's length direction are incorporated to
strengthen the produced fabric in its length direction for winding
it up. However, such inclusion of extra yarns creates uneven
thickness in the fabric. Such a woven fabric will be relatively
thicker wherever such longitudinal yarns run compared with other
areas. Further, the inclusion of these extra yarns also immediately
causes uneven fibre distribution in the fabric. Areas of fabric
where such yarns are incorporated will have higher fibre
concentration than the other areas where such yarns are not
included. A bias material with these defects is clearly unsuitable
and undesirable for technical applications.
[0080] (j) The described method cannot incorporate extra yarns in
the fabric's width direction whereby the described bias material's
mechanical properties will be dissimilar in the fabric-width and
fabric-length directions. Such an unbalanced construction is also
not desirable.
[0081] Clearly, the described modified weaving process cannot
produce a bias fabric using tapes. Also, such a modified weaving
arrangement can neither process tapes, nor has any means for
imparting secondary integrity/stability to the bias material nor
has any means to engineer any functionality. Accordingly, the woven
material produced therewith has neither any secondary structural
integrity/stability arrangement to prevent structural opening and
gaps nor any functional features. Further, because the woven fabric
described therein is produced using `flat` yarns, the crimp
frequency and crimp angle will be relatively higher in such a woven
fabric. Consequently, the accumulation of matrix in the valleys of
the weave crimp will create the undesirable dead-weight problem as
explained earlier. Further, the described woven fabric produced
using `flat` yarns cannot be of lower areal weight and mean fabric
thickness. Also, the described operational arrangements and
procedures, being complex and cumbersome, are obviously not suited
for processing any type of tapes, including SFT and HDPT.
[0082] In any case, the disclosed method, which clearly follows the
traditional weaving procedures, is capable of producing the woven
material using `flat` yarn warps and wefts of only one material
type which are mutually oriented at right angle to each other
during the weaving process. Such a method is evidently limited in
that it cannot be practically employed for directly producing bias
materials wherein the warp and weft `flat` yarns are mutually
oriented in either obtuse angle or acute angle relationship. Such a
process also cannot produce other possible structures such as those
with folded tapes to be described herein.
[0083] Although the `flat` yarn described in U.S. Pat. No.
6,494,235 is said to be free from twists, it is not necessarily
free from internal crisscrossing of filaments and twisting of
filaments which cause non-uniform distribution of fibres and
tension variations. These defects make the `flat` yarn uneven in
thickness. The use of `flat` yarn also cannot provide relatively
large number of well distributed and exposed filaments for
increased and quicker wetting.
[0084] That the fabric according to U.S. Pat. No. 6,494,235
described above uses `flat` yarns, and not tapes, including SFT and
HDPT, also becomes apparent from U.S. Pat. No. 6,585,842
(attributable to the same applicant and also one of the inventors)
wherein a multiaxial fibrous web comprising a plurality of
unidirectional sheets is disclosed. The textile material according
to U.S. Pat. No. 6,585,842 is produced by spreading tows to form
unidirectional sheets which are then superposed in different
orientations relative to each other and bonded together to obtain
the textile material. The methods described therein for spreading
the tows and laying them superposed in different orientations are
specifically designed for handling spread fibres and distinctly
different from the one described in U.S. Pat. No. 6,494,235.
Clearly, the `flat` yarns described in U.S. Pat. No. 6,494,235 are
not tapes, including SFT and HDPT types. It will be also clear now
to the person skilled in the art that the weaving method and means
described in U.S. Pat. No. 6,494,235 are not suitable for handling
and processing tapes, including SFT and HDPT types, and the
described bias material is produced using `flat` yarns and not
tapes, including SFT and HDPT types.
[0085] It is relevant to point out here that the fabric according
to U.S. Pat. No. 6,585,842 is crimpless and it has no natural
primary structural integrity/stability such as that coming from,
for example, interlacing (by weaving), interlooping (by knitting)
and intertwining (by braiding). A bias fabric lacking natural
primary structural integrity/stability will delaminate (i.e. layers
will separate). And lack of secondary structural
integrity/stability will cause fabric deformation/distortion (i.e.
openings and gaps) when forces act on it.
[0086] Clearly, an OFT comprising tapes, including SFT and HDPT
types and their combination types has previously not been known.
Also, a method and means for producing OFT using tapes, including
SFT and HDPT types have previously not been known.
[0087] U.S. Pat. No. 3,426,804, US 2005/0274426 are other examples
to indicate methods available for producing bias fabrics. That
these methods cannot process tapes, including SFT and HDPT types,
is too obvious for a person skilled in the art and hence require no
further consideration.
[0088] U.S. Pat. No. 6,450,208 and WO2006/075961 exemplify a method
for weaving tape-like warps and wefts. The woven material according
to U.S. Pat. No. 6,450,208 comprises tapes of sandwich and other
special constructions. The woven material according to
WO2006/075961 comprises partially stabilized tapes. A woven
material comprising either SFT or HDPT, and having secondary
structural integrity/stability, is not known from these documents.
According to these documents the woven fabric comprises tapes
orientated in fabric's length and width directions. WO2006/075961
also discloses a fabric construction wherein the weft tapes are
obliquely oriented in relation to the warp tapes that run oriented
in the fabric-length direction. This fabric structure should not be
mistaken for a bias fabric and OFT because it does not have any
fibres that are oriented in the correspondingly opposite bias
weft-direction as a result of which such a fabric cannot bear any
load/forces in that bias direction. From these documents neither a
method and means for producing an OFT nor an OFT are known. Because
these woven fabrics comprise tape-like warps and wefts oriented in
fabric's length and width directions respectively, the usual
handling of such woven fabric presents no difficulties as a woven
fabric can bear loads/forces in its longitudinal and lateral
directions. Accordingly, such woven materials do not require any
secondary structural integrity/stability in its body to resist
development of openings/gaps.
[0089] For laying the principles of the OFT forming process
according to the present inventions on a technically correct basis,
it is also important to consider here certain relevant aspects of
the weaving and braiding processes and the related characteristics
of the fabric structures producible by them because the disclosed
method according to the present inventions is considered
technically noncompliant with weaving and braiding processes.
[0090] The 2D-weaving process is designed for producing an
interlaced material using two clearly defined sets of
yarns/tapes--the warps (orientated in fabric-length direction) and
the wefts (orientated in the fabric-width direction). Its
fundamental operations are shedding followed by weft inserting, to
interlace the warps and the wefts in mutually orthogonal
relationship. While the warp occurs parallel to fabric-length
direction, the weft is at 90.degree. orientation to the warps. The
shedding operation creates a shed, which is like a tunnel formed
using the warps. The planes of the two openings of the shed are
located at the selvedge sides of the fabric being produced and the
planes of these openings are oriented more or less perpendicular to
the fabric-fell. Seen axially in the direction of the opening, the
shed usually resembles either a parallelogram/rhombus or a triangle
depending on the specifics of the employed shedding elements and
geometry. The opening of shed is thus always defined by a closed
geometrical figure.
[0091] The length of the shed equals approximately the reed-width
of the fabric being produced. Further, because the shed's openings
are at the selvedge sides, the weft insertion has to be necessarily
performed using the side openings. Thus, the weft is inserted
incrementally, oriented in its length direction, from one opening
of the shed to the opposite opening. The entire length of weft is
never laid in the shed at once. Subsequent to weft insertion, the
reed beats-up the weft to the fabric-fell position. Clearly weft
insertion and beating-up are two different operations and hence
require different means for effectuation (while the former requires
either a shuttle or rapier or projectile or pressurized fluid, the
latter requires a reed). The take-up of the produced woven material
corresponds with the `diameter` of the weft yarn or width of the
weft tape and thus the fabric is invariably advanced in the
direction of the weft's width while the warp is drawn in its length
direction. Lastly, weaving is designed to produce a finite length
of interlaced material by virtue of the warp supply being of
specific length. Thus, once the supplied length of warps is woven,
a new set of warps has to be either joined to the previous one
(which produces a joint in the fabric) or setup freshly again. In
any case, the weaving process is technically not capable of
producing endless woven fabric. Further, the body of a woven
material being produced at any instant is four-sided such as that
represented by a rectangle (two length sides and two width
sides).
[0092] The flat braiding process, to compare with the weaving
process, is designed for producing an intertwined material using
one set of yarns--the braiding yarns. Its fundamental operation
comprises moving yarn spools in an endless path and in a manner
that their paths crisscross each other to intertwine the yarns
angularly relative to the braid's length direction. Through such a
working, and to obtain an acceptable braid quality in terms of
areal yarn density, the braiding process naturally has a convergent
layout (areal yarn density at the spools/packages side is
relatively lower than that at the fabric-formation zone). Further,
the braiding process inherently requires the braiding yarns to be
under constant tension and constant abrasion with each other. Such
an abrading action between the braiding yarns is deleterious,
particularly to the brittle fibre types, as they get significantly
damaged, especially at the fabric-forming zone where the yarns tend
to be in intense contact with each other due to their increased
proximity/density.
[0093] Another disadvantage with such a convergent layout is that
the braiding process, whether flat or rotary, inherently cannot
handle tapes without causing their deformation (crumpling,
creasing, folding, wrinkling etc.). Thus, braiding process is
relatively limited in its processing capability compared with
weaving. Further, for a given braiding angle, the braiding process
cannot enable relatively tighter packing of the yarns in the fabric
beyond a certain point as there is no beating-up operation involved
(such as in weaving). All the constituent yarns of a flat braid
intertwine with each other and run continuously from one edge to
opposite creating self-locked edges in braid's length direction.
However, this is not possible with tapes without crumpling or
deforming them. The braids are relatively narrow fabrics compared
with usual woven materials which are relatively enormously wider.
Such narrowness of the braid fabric is due to the natural
limitation of the braiding process design. All braiding yarns run
continuously from the start of the fabric to its end. Clearly the
braiding process is designed to produce a finite length of
intertwined material by virtue of the braiding yarn supply from
spools being of specific length. Thus, once the supplied length of
yarns is braided, a new set of braiding yarns has to be either
joined to the previous one, which will create knots in the braid,
or a new one set up again. Thus, the braiding process is
technically not capable of producing endless braided material. Here
again, the body of a flat braided material being produced at any
instant is four sided such as that represented by a rectangle (two
length sides and two width sides).
[0094] From the foregoing descriptions of the weaving and braiding
processes it will be clear that both these processes cannot produce
OFT using tapes, including SFT and HDPT types.
Further Features and Advantages of the Present Invention
[0095] In the light of presented technical aspects, it is obvious
that it will be beneficial to make available an OFT comprising
tapes, including SFT, HDPT and their combination types, whereby the
OFT provides, among other performance and function related
benefits, maximum strength in two opposite oblique orientations
relative to the fabric-length (or width) direction and also certain
secondary structural integrity/stability, preferably directionally
oriented, for improved resistance to formation of openings/gaps
during normal handling/processing and thereby be industrially
relevant and useful.
[0096] The present invention makes available OFT fabrics that
enable strengthening of large surfaces of buildings and other
similar constructions, composite materials for producing
lightweight and strong parts such as large mobile dish antennas,
rapidly deployable heat/chemical/radiation etc. shields and
ballistic mitigation products. The use of OFT for aesthetics is
another objective. In short, the novel OFT fabrics will be highly
advantageous wherever weight savings and bias directional
performance are necessary. Obviously, OFTs comprising not just
carbon and polymeric materials, but also other materials such as
organic, inorganic, synthesized, metallic and natural fibres,
including their combinations, to suit the requirements of a given
application, can be considered. The novel OFTs can be used either
independently or in combination with other suitable fabrics, for
example by plying with different fabric materials. Such OFTs can
occur either between the plies or at the exteriors or in
combination.
[0097] A bias fabric inherently lacks strength in the fabric-length
and fabric-width directions compared with a woven material (wherein
warp and weft can respectively bear the loads in those directions).
However, the provided OFT solves this inherent problem and
advantageously provides an improved bias fabric that does not
easily develop structural openings/gaps and can be handled. Such an
OFT does not include extra yarns etc. The bias fabric can be also
provided with the capability to adhere to other surfaces, at least
temporarily, so that it can be handled and worked upon subsequently
while kept in desired position and thereby not destroy/impair its
structural characteristics. In a preferred embodiment, both faces
of the OFT are enabled to adhere, at least temporarily, to surfaces
of other materials or bodies, through use of suitable tapes. This
will be helpful when, for example, OFT as reinforcement has to be
positioned on other materials, or vice-versa, in particular
orientations relative to the other. The OFT may be used in numerous
different types of applications. For example, it will be highly
useful for protecting a vehicle or a building (i.e. its occupants)
by sticking one or more sheets of the OFT of suitable material
quickly and temporarily over the vehicle/building and cover it for
mitigating the full impact of an impact. This is further
facilitated by providing adhesion of OFT to other surfaces and it
could be achieved, for example, by suitably including an adhesive
formulation directly in the OFT itself (e.g. through use of
suitable tapes) so that it can be activated either by pressure or
chemical reaction (including application of water) or heat or a
suitable combination of them.
[0098] The OFT may also be preferably provided with slits so that
suitable bands can be passed through it for supporting/attaching
the OFT to other surfaces when necessary. Incorporation of slits
will uniquely render OFT functional.
[0099] The OFT may also be preferably provide with either one
wholly sealed longitudinal edge, or both longitudinal edges partly
sealed, for its reliable and durable guiding and handling, for
example during its subsequent processing such as unrolling and
pre-pregging.
BRIEF DESCRIPTION OF DRAWINGS
[0100] The preferred embodiments of the novel OFT and its unique
method and means for production are illustrated through the
following drawings.
[0101] FIGS. 1a-j illustrate the steps of Starting Phase of the
method for producing OFT.
[0102] FIGS. 2a-j illustrate the steps of Continuing Phase of the
method for producing OFT.
[0103] FIG. 3 exemplifies an OFT construction.
[0104] FIG. 4 illustrates a layout of the essential components of
the device preferred for producing OFT.
[0105] FIGS. 5a-b exemplifies the working bed of the OFT producing
device.
[0106] FIG. 6 exemplifies the arrangement of the tape supply spools
at either sides of the bed.
[0107] FIGS. 7a-d exemplify different possibilities of arranging
the tape supply spools in relation to the working bed.
[0108] FIG. 8 exemplifies the arrangement of the tape holders and
tape cutters.
[0109] FIGS. 9a-b exemplify different styles of cutting the
tape.
[0110] FIGS. 10a-b exemplify an arrangement for drawing out the
tape from the spool.
[0111] FIG. 11 exemplifies the main components and mounting
arrangement of the tape gripper.
[0112] FIGS. 12a-b exemplify different styles of fixing the gripper
to match the corresponding styles of tape's cut.
[0113] FIG. 13 exemplifies a tape holding and laying unit.
[0114] FIGS. 14a-f exemplify relevant details of different
arrangements for displacing the fore ends of the laid tapes.
[0115] FIGS. 15a-k exemplify an arrangement for consolidating the
produced OFT and some examples of directionally oriented
consolidations.
[0116] FIGS. 16a-b exemplify an arrangement for aiding the
advancement of OFT for taking-up.
[0117] FIGS. 17a-c exemplify three different OFT types wherein the
tapes are orientated in two equal and opposite oblique directions
relative to the fabric-length (or width) direction and the angle
subtended mutually by the tapes are acute, right and obtuse angles
respectively.
[0118] FIGS. 18a-b exemplify an arrangement for advancing and
collecting/winding OFT.
[0119] FIG. 19 exemplifies an OFT wherein the tapes are orientated
in two unequal and opposite oblique directions relative to the
fabric-length (or width) direction and the angle subtended mutually
by the tapes is an obtuse angle.
[0120] FIGS. 20a-e exemplify steps for folding tape to produce an
OFT wherein a folded tape is orientated in two equal and opposite
oblique directions relative to the fabric-length (or width)
direction for producing OFT with one continuously closed
longitudinal edge.
[0121] FIGS. 21a-c exemplify the steps for producing an OFT with
one continuously closed longitudinal edge.
[0122] FIG. 22 exemplifies an OFT wherein longitudinally oriented
slits are provided along the longitudinal axis of OFT.
[0123] FIGS. 23a-e exemplify the production steps for obtaining an
OFT with longitudinally oriented slits along the longitudinal axis
of OFT.
[0124] FIG. 24 exemplifies an OFT wherein longitudinally oriented
slits are provided off set from the longitudinal axis of OFT.
[0125] FIG. 25 exemplifies an OFT wherein laterally oriented slits
are provided along the longitudinal axis of OFT.
[0126] FIG. 26a-j exemplify the production steps for obtaining an
OFT with laterally oriented slits along the longitudinal axis of
OFT.
[0127] FIGS. 27a-e exemplify an OFT with longitudinally and
laterally oriented slits, and various alternatives to incorporate
additional bands/tapes through the slits.
[0128] FIGS. 28a-c exemplify three different types of OFT wherein
both longitudinal edges are partly closed and partly open.
[0129] FIGS. 29a-k exemplify the production steps of one cycle for
obtaining an OFT with both longitudinal edges partly closed and
partly open.
[0130] FIGS. 30a-c exemplify the plan views of an alternative
arrangement for producing specific area OFTs of obtuse, right and
acute angles wherein certain parts are in adjoining location.
[0131] FIGS. 31a-c exemplify production steps for obtaining
specific area acute angle OFT.
[0132] FIGS. 32a-f exemplify the plan view of alternative
arrangements for producing a specific area OFT material in an
alternative manner and the corresponding production steps.
[0133] FIGS. 33a-b exemplify the plan views of an alternative OFT
production method wherein the tape laying unit swivels in a
horizontal plane.
[0134] FIGS. 34a-b exemplify an end view of an alternative OFT
production method wherein the tape laying unit swivels in a
vertical plane.
[0135] FIGS. 35a-b exemplify an alternative arrangement for
angularly displacing the laid tapes' fore ends.
[0136] FIG. 36 exemplifies an alternative arrangement for advancing
forward produced OFT.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0137] The preferred embodiments of the present inventions relating
to the method of and means for producing OFT and also the OFT
constructions producible thereof will be described in the
following. However, it is to be understood that features of the
different embodiments are exchangeable between the embodiments and
may be combined in different ways, unless anything else is
specifically indicated. It may also be noted that, for the sake of
clarity, the dimensions of certain components illustrated in the
drawings may differ from the corresponding dimensions in real-life
implementations of the invention.
Production Method
[0138] Production of OFT comprising tapes, including SFT and HDPT,
according to this invention involves the Starting and Continuing
Phases. The various steps involved in the Starting Phase are first
described in reference to FIGS. 1a to 1j and those of the
Continuing Phase in reference to FIGS. 2a to 2j. These
illustrations show the plan view and represent one mode of OFT
production.
Starting Phase
[0139] The starting phase preferably comprises the following steps:
[0140] 1) Positioning each of the two tape supply spools (1a, 1b),
with a defined angle between their axes, at either side of the
working bed (2) as shown in FIG. 1a. [0141] 2) Drawing out
specified length of tape (3a.sub.1) from spool (1a) towards bed (2)
as shown in FIG. 1b. [0142] 3) Cutting tape (3a.sub.1) from its
supply spool (1a) as shown in FIG. 1c. [0143] 4) Placing cut tape
(3a.sub.1) on working bed (2) as shown in FIG. 1d. [0144] 5)
Drawing out specified length of tape (3b.sub.1) from spool (1b)
towards bed (2) as shown in FIG. 1e. [0145] 6) Cutting tape
(3b.sub.1) from its supply spool (1b) as shown in FIG. 1f. [0146]
7) Placing cut tape (3b.sub.1) over tape (3a.sub.1) on working bed
(2) as shown in FIG. 1g. [0147] 8) Drawing out specified length of
tape (3a.sub.2) from spool (1a) towards bed (2) as shown in FIG.
1h. [0148] 9) Cutting tape (3a.sub.2) from its supply spool (1a) as
shown in FIG. 1i. [0149] 10) Placing cut tape (3a.sub.2) over tape
(3b.sub.1) and adjacently parallel to the previously laid tape
(3a.sub.1) on working bed (2) as shown in FIG. 1j and consolidating
the created primary structural integrity/stability with a suitable
secondary structural integrity/stability.
Continuing Phase
[0150] The commencement point of the Continuing Phase, as shown in
FIG. 2a, is after the first three tapes have been laid according to
the procedure described in the Starting Phase. The Continuation
Phase involves the following procedures. [0151] 1) Displacing the
fore end of tape (3a1) in its thickness direction and creating
front-face opening in relation to non-displaced fore end of
adjacent tape as shown in FIG. 2b. [0152] 2) Drawing out specified
length of tape (3b2) from spool (1b) towards bed (2) as shown in
FIG. 2c. [0153] 3) Cutting tape (3b2) from its supply spool (1b) as
shown in FIG. 2d. [0154] 4) Positioning cut tape (3b2) in the
created front-face opening, i.e. over tape (3a2) and below raised
fore end of tape (3a1), laying it adjacently parallel to the
previously laid tape (3b1) and reverting back raised fore end of
tape (3a1) as shown in FIG. 2e. [0155] 5) Displacing the fore end
of tape (3b1) in its thickness direction and creating front-face
opening in relation to non-displaced fore end of adjacent tape as
shown in FIG. 2f [0156] 6) Drawing out specified length of tape
(3a3) from spool (1a) towards bed (2) as shown in FIG. 2g. [0157]
7) Cutting tape (3a.sub.3) from its supply spool (1a) as shown in
FIG. 2h. [0158] 8) Positioning cut tape (3a.sub.3) in the created
front-face opening, i.e. over tape (3b.sub.2) and below raised fore
end of tape (3b.sub.1), laying it adjacently parallel to the
previously laid tape (3a.sub.2) and reverting back raised fore end
of tape (3b.sub.1) as shown in FIG. 2i. [0159] 9) Consolidating the
created primary structural integrity/stability with a suitable
secondary structural integrity/stability. [0160] 10) Repeating
endlessly steps 1-9 of Continuing Phase by displacing the fore ends
of preferred laid tapes in their thickness direction in a
predefined patterning order and creating front-face opening in
relation to adjacent non-displaced tapes, laying cut tapes
(3a.sub.n) and (3b.sub.n) in the created front-face openings from
corresponding directions and adjacently parallel to the previously
laid tapes and reverting back raised fore ends of corresponding
tapes and consolidating the created primary structural
integrity/stability with a suitable secondary structural
integrity/stability to produce OFT continuously as shown in FIG.
2j.
[0161] The steps for consolidating the created structure for
resisting formation of openings/gaps, advancing forward the
produced OFT for winding-up in a roll form, though not listed
above, will be performed at appropriate moments for achieving
practical continuity of the process as shall be described later. An
OFT is represented generally in FIG. 3.
[0162] The listed steps are for general guidance and do not have to
be necessarily performed in the indicated sequence. For example,
the Starting Phase could commence by drawing out tape (3b.sub.1)
instead. Also, variations can be introduced in the described steps
of the novel process to achieve practical efficiency. For example,
the fore end of a laid tape can be displaced while the tape from
the spool is being drawn out, or tapes from both the spools can be
drawn out half way simultaneously, or cutting of drawn out tape can
be performed when produced OFT is being advanced forward for
winding into roll etc.
[0163] Alternatively, in the Starting Phase, initially two tapes of
the same oblique direction could be laid adjacently. Then, one of
the fore ends be displaced in its thickness direction to create
front-face opening, in conjunction with the other tape the fore end
of which is not raised, to receive a tape of the other oblique
direction. From this point on, the described Continuing Phase could
commence suitably, as described, by displacing the preferred fore
end of the initially laid two tapes of the other oblique
direction.
[0164] From the foregoing description of the method the following
important novelties can be immediately observed: [0165] 1) The
process employs essentially two tape supply sources, such as
working spools (which can be of either same or different materials,
types, properties etc.). [0166] 2) The process does not involve
traditional setting-up of materials, such as that associated with
weaving and braiding. [0167] 3) The process is endless, i.e. the
process need not be technically stopped to start afresh with new
setting up so long as the two supply sources of tapes, such as
spools, are replenished, either automatically or manually.
Alternatively, cut tape lengths could be continuously stored in and
drawn/supplied from a magazine. [0168] 4) The process does not
follow the procedures of weaving process because: [0169] (a) It is
not possible to perform weaving using only two supply spools--one
for warp and one for weft. [0170] (b) There are no defined sets of
warps and wefts. [0171] (c) The fore ends of the laid tapes that
are to be displaced in their thickness direction occur along the
respective two longitudinal edges of the fabric whereby no shed is
created between the two longitudinal edges. [0172] (d) There is no
shed created of any defined closed shape and there is no weft
insertion performed from one open side of a shed to the opposite.
[0173] (e) The laid tapes are tensionless and not required to be
maintained in a tensioned condition during OFT production. [0174]
(f) There are two production phases--Starting and Continuing.
[0175] 5) The process does not follow the procedures of braiding
process because: [0176] (a) It is not possible to perform braiding
using two stationary spools. (By using two moving spools the
issuing tapes will only twist with each other and not intertwine.)
[0177] (b) The two spools remain stationary and are not traversed
in any endless tracks. [0178] (c) The tapes are not under constant
abrasion with each other. [0179] (d) The tapes do not run
continuously between the fabric edges. [0180] (e) The laid tapes
are tensionless and not required to be maintained in a tensioned
condition during OFT production. [0181] (f) There are two
production phases--Starting and Continuing. [0182] 6) The process
involves consolidation of the created primary structural
integrity/stability with a suitable secondary structural
integrity/stability for improved resistance to formation of
openings/gaps and deformation. [0183] 7) The produced OFT is
advanced forward for winding by a distance defined by the length of
longitudinal diagonal of the rhombus-shaped pattern of the OFT, and
not the width of the tape. The OFT is not advanced forward for
winding in the constituent tape's width direction. [0184] 8) The
process can combine tapes of different materials, types, properties
etc. at will. [0185] 9) The process does not require the tapes to
be maintained under constant tension as a condition for processing
them into OFT. [0186] 10) The process associates partly the tape of
one direction that is being laid with the earlier laid tapes of the
other direction emanating from the body of the produced OFT and the
remainder of this tape is laid free to associate with the tape of
the other direction that will be laid subsequently. [0187] 11) The
length of each tape required for producing an OFT is governed by a
definite relationship between fabric width and angle of tape's
incorporation in OFT. [0188] 12) The process directly lays at once
the entire length of each of the required tapes during OFT
production and such laid tapes occur in a tensionless state in
OFT.
[0189] It is preferable that the described process is carried out
in a horizontal format to produce the novel textile material.
However, if there are space restrictions then OFT can be produced
in either an inclined format or vertical format using suitable
means without departing from the spirit of the described
process.
[0190] To the practitioners of weaving and braiding it will be
amply clear now that the described process does not comply
technically with the established principles, procedures and
operations of either weaving or braiding processes. Also, the novel
process described herein is technically not both weaving and
braiding processes at the same time. It is also technically not a
part-combination of both weaving and braiding processes in any way.
That the described novel process is technically neither weaving nor
braiding is in itself a novelty of this process. The simplicity of
the described process, in comparison to the weaving and braiding
processes, makes it all the more practically relevant and
industrially attractive. Accordingly, a suitable practical device,
working on the new fabric-forming principle, for producing OFT, is
presented next.
Production Device
[0191] The preferred embodiments of the novel practicable device
for producing OFT using tapes, including SFT and HDPT types and any
other kind and combination of tapes, are described in reference to
FIG. 4, which shows the plan view in general.
[0192] The relative positions of the essential and different
constituent arrangements of the novel device for producing OFT are
shown in FIG. 4. The device comprises the following:
[0193] 1. Arrangement for supporting textile formation (11)
[0194] 2. Arrangements for supplying tapes (12)
[0195] 3. Arrangements for cutting tapes (13)
[0196] 4. Arrangements for drawing out tapes from spools (14)
[0197] 5. Arrangements for laying the cut tapes (15)
[0198] 6. Arrangements for displacing fore ends of the laid tapes
(16)
[0199] 7. Arrangements for consolidating produced material (17)
[0200] 8. Arrangement for advancing produced material (18)
[0201] 9. Arrangement for collecting produced material in a roll
(19)
[0202] Each of these indicated arrangements of the device and their
features are individually described below.
1. Arrangement for Supporting Textile Formation (11)
[0203] As shown in FIG. 4, arrangement (11) for supporting textile
formation is central to the production of OFT. In FIG. 5a are
shown, by way of example, the basic components of this arrangement
(11). It comprises a working bed (11) part of which is stationary
(11a) and provided with finger-like projections (11b) at one end
side. Bed (11) supports movable bed/plate (11f) shown in FIG. 5b.
Plate (11f) is also provided with matching fingers (11g) as shown
in FIG. 5b. Plate (11f) can be reciprocated relative to the bed
(11a) in the longitudinal direction of bed (11a) for enabling
forward advancement of OFT for take-up. The arrangement (11) is
thus composed of stationary and movable parts. The distance of
reciprocation of plate (11f) is controlled by suitable drives (not
shown). The distance by which plate (11f) has to be reciprocated
would depend on the width of the tapes used for producing the OFT
and the angle of their orientation relative to the longitudinal
direction of arrangement (11). For example, when using tapes of 50
mm width, the distance of reciprocation of plate (11f) will be
about 100 mm when tapes' orientation is 60.degree.; 71 mm when
tapes' orientation is 45.degree. and 58 mm when the tapes'
orientation is 30.degree.. As can be noticed, the distance of
reciprocation of plate (11f) is always greater than the width of
the tapes used and it corresponds approximately to the distance
that the produced OFT has to be advanced for winding into a roll.
Arrangement (11) thus also functions to assist in advancing forward
the produced OFT for take-up.
[0204] The stationary bed (11a) and the movable plate (11f) are
respectively provided with fingers (11b) and (11g) or similar
arrangement. The heights of fingers (11b) and fingers (11g) are
preferably equal so that they can together provide a bridge of
uniform plane and continuous surface for the OFT being produced
over them. This way OFT can be supported in a sliding manner by
plate (11f) and without its constituent fibres getting hooked or
damaged or pulled out during reciprocation of plate (11f).
Alternatively, the height of fingers (11g) of plate (11f) could be
relatively greater than that of fingers (11b) of bed (11a). The OFT
is essentially formed on bed of arrangement (11) which is composed
of stationary and movable components. Accordingly, arrangement
(11), shown in FIGS. 5a and 5b constitute the textile formation
support of this novel process. Arrangement (11) has two ends, which
may be regarded as the feeding end (i.e. the end farthest from
fingers (11b/11g) and winding end (i.e. the end closest to fingers
(11b/11g).
[0205] The surfaces of plate (11f) and fingers (11b) and (11g) are
preferably in one plane and of low friction type such as that
obtained by either coating it with PTFE (or the like) or fixing a
suitable sheet of PTFE (or the like) over it. The advantages with
the latter being easier, quicker and lower cost of replacement. As
all other involved arrangements will be physically related to this
arrangement (11), it is preferred that this arrangement is robust
and stable to support them. Bed (11a) need not be necessarily
heavy; it could be as well produced using suitable lightweight
composite materials. The bed (11a) and plate (11f) could be also
made using perforated plates, not only to reduce weight but also to
keep the tapes laid over them detachably attached, such as possible
by using vacuum pressure. A construction as this could be
beneficial especially when arrangement (11) is preferred to be had
either inclined or vertical due to certain needs as indicated
below.
[0206] Preferably bed (11a) is employed horizontally as shown in
FIGS. 5a and 5b. The height of bed (11a) from the floor could be of
either fixed type or raising-lowering type depending on the
convenience requirements of the operating personnel. In case of
either production floor space restrictions or other special needs
of the operating personnel, the bed could be either tilted at a
convenient incline or even made vertical (together with the other
arrangements that will be physically connected to it). The bed
(11a) has dimensions suitable for accommodating whole lengths of
tapes that will be laid obliquely in two orientations over it for
OFT production. The arrangement (11) is constructed in a manner
that all its edges are smooth and rounded to prevent the
constituent fibres of the produced OFT from getting hooked and
damaged, for example when OFT is fed in sliding manner over the
surfaces of fingers (11b and 11g) and plates (11a and 11f) for
taking-up.
[0207] On the two longitudinal sides (11c) and (11d) of bed (11a)
are provided suitable provisions (11e), for example threaded holes,
projections, recesses, slots etc., to support arrangements (16),
that are preferred for displacing the fore ends of the laid tapes,
as indicated in FIG. 5a. These arrangements (16), to be described
later, are preferred to be located at the sides (11c and 11d) of
bed (11a) for operational reasons and shall be described later.
[0208] As normally OFT of different widths shall be preferred to be
produced, it is considered advantageous to have bed (11a) and plate
(11f) made in a manner that its width can be suitably altered and
set prior to commencing the desired production. Such an alteration
of the bed's width could be realized by constructing it modularly.
For example, bed (11a) and plate (11f) can be made in suitable
longitudinal sections of different widths so that they can be
placed adjacently to each other and joined to achieve the preferred
width of bed (11a) and plate (11f). There is another benefit in
having the possibility of varying the width of bed (11a). For
example, operating personnel can easily access the material during
production in case attention is needed. A relatively small width
material produced on a wide bed will be obviously difficult to
reach. In any case, as will become clearer later, the total working
width of the arrangement (11) will be the combined width of bed
(11a) and the two arrangements (16) attached at its sides (11c) and
(11d).
[0209] In an alternative arrangement, a conveyor belt may be used,
whereby the upper part of the conveyor belt of preferred width
could be used over bed (11a) and reciprocating plate (11f), for
producing OFT over it, while the lower part of conveyor belt passes
under bed (11a). Such a conveyor belt could be turned by a pair of
suitable rolls, one mounted at feeding end of bed (11a) and the
other at the OFT winding end. An advantage with using a conveyor
belt is that it can be continuously moved in preferred increments
or steps. However, its main disadvantage is that it tends to curve
in its width direction (over long spans) and hence the surface of
the conveyor belt is difficult to be maintained plane. Getting the
belt equally tensioned longitudinally at both sides also presents
difficulties and it can become a cause for skewing the OFT during
production.
[0210] In another alternative arrangement, if preferred, a paper
sheet, or the like, could be continuously supplied from a large
roll from feeding end and passed over plate (11f) and OFT directly
produced over it. This way the fed paper can also directly function
as an interleaving material between the layers of OFT when it is
wound into a roll. The paper can be substituted by any other
material, such as polymeric film and laminated paper.
2. Arrangements for Supplying Tapes (12)
[0211] In FIG. 4 is shown, by way of example, the relative position
of arrangement (12) that is preferred for supplying tapes for
producing the novel OFT materials. As shown in FIG. 6, two tape
spools (12a) and (12b) are mounted on respective
shafts/holders/chucks (12c) and (12d) which are located at the
sides of arrangement (11) described earlier. The axes of both these
spools are respectively maintained at an angle relative to the two
longitudinal sides of arrangement (11). Both these angles .theta.
made by the axes of the spools (12a) and (12b), shown in FIG. 6,
can be either equal or unequal, but preferably in opposite oblique
directions, according to the desired obliqueness of the tapes that
are to be incorporated in the OFT. Preferably, each of the two axes
are maintained at a practically convenient height from the floor
for convenience in mounting/dismounting spools.
[0212] The axes of spools (12a) and (12b) could be maintained in
different relations to the top surface of arrangement (11) as
exemplified in FIGS. 7a to 7d, wherein only one spool is shown for
explanation. The position of the spool axis A can be either above
(FIGS. 7a and 7b), or at the same level (FIG. 7c) or below (FIG.
7d) the top surface of arrangement (11). Such positioning
possibility of the spools is possible because the position of the
exit guide rolls (12e) can be maintained constant in relation to
the surface of arrangement (11). As exemplified in FIGS. 7a and 7b,
the tape can be drawn out from spool (12a) from either `under` or
`top` sides of the spool while the axis A remains above the top
surface of arrangement (11). It is not necessary to locate the
spools besides the arrangement (11) as shown in FIG. 6; depending
on the constructional and floor space reasons the spools can be
located either over or under the bed of arrangement (11). Also, the
axis of the spools can be had either parallel or at an angle to the
surface of arrangement (11). Such positioning possibilities of the
spools uniquely provide savings in operational floor area
requirements and ease of accessibility considering the required
space restrictions and engineering and operational conveniences. In
any case, as can be inferred, it is not necessary to draw the tapes
only from spools (12a) and (12b); specific cut-length of tapes
could be also stored in a suitable magazine and supplied for
uninterrupted production of OFT.
[0213] The spools (12a) and (12b) are respectively mounted on
shafts/chucks (12c) and (12d), as shown in FIG. 6, which are fixed
to suitable pedestals (not shown). These pedestals could be fixed
to a base plate or mounted on two arms that could extend from the
arrangement (11) (not shown). While the inner ends of the arms
could be connected to arrangement (11), the outer ends of these
arms could bear the pedestals for supporting the holders/chucks
(12c) and (12d). The arms could be preferably of the telescopic
kind so that the spools (12a) and (12b) can be easily positioned
either close to or away from arrangement (11) according to needs.
The pedestals could be mounted on the arms in a manner that each
one of them can be individually swiveled and locked respectively
into desired positions so that the angle of the axes of the spool
(12a) and (12b) could be directly and easily adjusted and set.
Alternatively, the inner ends of the arms could be suitably
connected in a way, such as gears, that movement of one of the arms
produces a corresponding movement in the other. Means for locking
the arms in the desired positions could be suitably located.
[0214] The turning of the spools (12a) and (12b) to pay out the
tapes in the direction of arrangement (11) can be controlled by
available conventional electrical, mechanical, pneumatical etc.
systems.
[0215] While the essentials of arrangement (12) have been described
above, certain other aspects relating to special needs and
automation are considered next.
[0216] At times special tape materials, such as prepregs and tacky,
might be preferred to be processed. Such tapes are usually supplied
with a foil that prevents the layers of the tapes wound in a spool
from sticking to each other. For handling such foil tapes,
additional pedestals can be fixed to the base plate or arms (or
extensions thereof) so that collection of the waste foil paid out
by the spools (12a) and (12b) can be directly wound onto other
spools that are respectively mounted close to the working
spools.
[0217] When processing tapes that incorporate powdery substance,
suitable suction units could be mounted at appropriate positions
for continuous removal of the powder, if needed. Likewise, if wet
tapes are to be processed, suitable drying heaters/blowers could be
mounted at appropriate positions.
[0218] To enable automation, spool changers could be incorporated.
For example, robotic arms could pick fresh spools from a magazine
and mount them onto the shafts/chucks (12c) and (12d) projecting
from respective pedestals. Another approach would be to have the
spools directionally arranged in a magazine that could be brought
into position for the shafts/chucks (12c) and (12d) to directly
receive such spools once the running spools near exhaustion. Still
another way would be to have a pedestal with, e.g. four or six,
shafts/chucks fixed to it in as many orientations. By angularly
turning the pedestal, the spools mounted on the shafts/chucks can
be brought into the desired working position. Yet another way to
replenish the exhausted spools with fresh ones would be to have
additional pedestals, loaded with fresh spools, which could then be
turned and brought into the working position. Fresh spools could be
loaded in advance on the shafts/chucks of pedestals at the
`non-working or passive` positions while the `working or active`
spools are running. As the running spools get expended, the
additional pedestals could be brought into position automatically.
Through use of any type of automated spool changer, an OFT can be
produced using any tape material, type, form, properties etc. Also,
such changes can be effected at will and in any sequence whereby an
endless variety of OFT can be easily and directly produced.
[0219] Alternatively, as indicated earlier, specific cut lengths of
tapes could be continuously stored in a magazine and suitably
presented for laying on arrangement (11).
3. Arrangements for Cutting Tapes (13)
[0220] As the novel OFT is produced using only specific discrete
lengths of tapes, inclusion of devices for cutting the tapes that
are drawn out from the spools (12a) and (12b) become indispensable.
In FIG. 4 is shown, by way of example, the relative position of the
arrangements for cutting tapes (13). Accordingly, as shown in FIG.
8, the cutting device exemplified includes the cutters (13a) and
(13b) and also means for clamping (13c) and (13d). Both these
cutting units are suitably located, preferably besides arrangement
(11). Further, the cutters (13a) and (13b) are positioned in the
vicinity of the exit rolls/bars (12e). These cutters can be
reciprocated if necessary. Further, the cutters (13a) and (13b) are
mounted in a manner that they can be turned/swiveled and locked
into desired angular position in relation to the length direction
of the tapes paid out by the spools (12a) and (12b). As shown in
FIG. 9a, the cut edge (13e) of the tape is 90.degree. relative to
its length direction. In FIG. 9b is shown the cut edge (13f) of the
tape at an angle relative to its length direction. Such an angular
cut is preferred to have cut edges of the angularly laid tapes
oriented in line with the corresponding longitudinal edge of the
OFT.
[0221] This arrangement for tape cutting (13), in addition to
cutters (13a) and (13b), also includes clamps (13c) and (13d), FIG.
8, to hold the fore ends of the drawn out tapes in position (for
subsequent operation) and also for the cutters (13a) and (13b) to
cut them reliably. These clamps (13c and 13d) can be also
correspondingly turned/swiveled and locked in position just as the
cutters (13a and 13b).
[0222] The cutting devices (13a) and (13b) can be preferably of
either contact type (e.g. mechanical, thermal) or contact-less type
(e.g. laser). The type of cutting device to be selected will depend
on the material composition of the tape to be used in the
production of OFT.
4. Arrangements for Drawing Out Tapes from Spools (14)
[0223] The relative positions of the arrangements (14), which are
preferred for drawing out the tapes from the respective spools, are
shown in FIG. 4. As essentially two tape supply sources, for
example working spools (12a) and (12b), are preferred for producing
OFT, this arrangement (14) comprises two units which work
identically. For the purpose of explaining, the working of only one
of the units is exemplified in FIGS. 10a and 10b.
[0224] As shown in FIGS. 10a and 10b, this arrangement essentially
comprises a linear driving member (14a) onto which is fixed a
gripper block (14b) for gripping/clamping the tape as is described
below. The tape gripper (14b) can be moved back and forth (i.e.
reciprocated) by the linear driving member (14a) between two
desired positions that defines the length of the tape to be drawn
out from the spool (12b) for producing OFT. These two positions are
a constant for a given width of the OFT to be produced. This way
the gripper (14b) grips the fore end of the tape issuing from the
spool (12b) in a flat condition and draws it out linearly.
[0225] To draw out the tape from spool, as shown in FIGS. 10a and
10b, the gripper block (14b) moves towards the pair of holders
(13d) and receives the free fore end of the tape that is held in
position and presented by the pair of holders (13d). At this moment
cutter (13b) is moved away from the path of the moving gripper
(14b). After the gripper (14b) has held the presented tape's fore
end, it is moved towards the direction of arrangement (11) whereby
the tape gets drawn out from the spool (12b). The gripper (14b) is
reciprocated through suitable electro-mechanical or pneumatic
driving units (14a). The tapes are normally drawn out alternately
from the two oppositely arranged supply sources, such as spools
(12a) and (12b) by respective grippers to produce the OFT.
[0226] For enabling the drawn out tape to be positioned in the path
for subsequent handling by the tape laying arrangement to be
described next, gripper block (14b) and pair of holders (13d) are
mounted in a manner (not shown) such that they can be raised and
lowered through conventional methods, and thereby correspondingly
raise and lower the drawn out tape held between them. Accordingly,
gripper block (14b) and pair of holders (13d) occur at a relatively
lower level when drawing out the tape from spool and at a
relatively higher level after the preferred tape length has been
drawn out. This way, the drawn out tape is raised for being caught
by the tape laying arrangement (15) to be described next.
Alternatively, an arrangement for only shifting/deflecting the
drawn tape could be considered to position the tape in the
preferred gripping path of arrangement (15).
[0227] In FIG. 11 is exemplified an arrangement for gripping the
fore end of the tape in a flat condition. This unit essentially
comprises a base member (14c) and a clamping member (14e), which
respectively form the lower and upper lips of the gripper. The base
member (14c) has suitable provisions, such as slots (14d), for
positioning and fixing it in the preferred position on plate (14h).
The upper lip (14e), which is pivoted about axis (14g) through its
leg (14f), can be moved to open and close the mouth, in relation
with lower lip (14c), by suitably moving the leg (14f) through a
suitable triggering member (not shown) such as available pneumatic,
mechanical, electro-mechanical etc. devices at appropriate
positions and moments. The entire described gripper assembly is
fixed to the driving block (14b) in a manner that it can be
swiveled about axis (14i).
[0228] The lower lip (14c) and upper lip (14e) are long enough to
receive a range of tape widths in a flat condition. This way the
same gripper can be used for a large range of tape widths. The lips
(14c) and (14e), which form the mouth of the gripper, always hold
the tape in a flat condition when drawing out the tapes from the
spools (12a) and (12b). The top surface of lower lip (14c) is
suitably positioned at a level that enables easy and direct
receiving of the free fore end of the tape held and presented by
the pair of holders (13d) (shown in FIG. 10).
[0229] The lips (14c) and (14e) always close and jointly draw out
the tape from the spool in the direction of arrangement (11). This
direction of drawing out tape is preferably at 90.degree. relative
to the respective supply spool axis. Accordingly, the longitudinal
side of each of the linear driving units (14) subtends the same
angle in relation to arrangement (11) as the drawn out tapes from
the corresponding spools (12a) and (12b).
[0230] A unique feature of the described gripper is that it can be
swiveled into desired position about axis (14i) and locked by
suitable arrangement (not shown) as illustrated in FIGS. 12a and
12b (which are the plan views of the device shown in FIG. 11). The
possibility of swiveling gripper assembly is advantageous for
receiving tapes that are cut either straight (.theta.1), as shown
in FIG. 12a, i.e. the cut angle is 90.degree. to tape length
direction, or at an angle (.theta.2), as shown in FIG. 12b, i.e.
the cut angle is other than 90.degree. to tape length direction.
Through such an arrangement the cut edge of tape and the fore sides
of the gripper base (14c) and clamp (14e) can be maintained
parallel and thereby a complete gripping of the tape's cut side
ensured. The FIGS. 12a and 12b also represent the same gripper's
ability to grip different tape widths T1 and T2.
[0231] It may be pointed out here that the length of tape drawn out
by the described arrangement (14) for producing a given OFT is
always longer than the width of the body of the OFT being
produced.
5. Arrangements for Laying the Tapes (15)
[0232] In FIG. 4 are exemplified the relative positions of the pair
of arrangements (15) which are preferred for laying the tapes on
arrangement (11) once the preferred length of the tape has been
drawn out by the pair of units (14) described above. As shown, each
of the two arrangements (15) are identical and are located at
either sides of arrangement (11) and they respectively lay the
drawn out tapes, preferably alternately, for producing OFT.
[0233] The constructional features of arrangement (15) are shown by
way of example in FIG. 13. Its front part is like a fork or yoke
(15a) with two forward extending fingers (15c) and (15c'). A stem
(15b) extends at the back side of the fork (15a). Stem (15b) is
supported and constrained in a sliding fashion (not shown) such
that unit (15) can be reciprocated linearly in a guided manner
through suitable arrangements. Alternatively, the fork (15a) could
be directly connected to a linear drive in a suitable manner for
its reciprocation. Further, unit (15) is mounted in a manner that
it can be swiveled and locked in preferred position (not shown) to
match its orientation with the desired angle of tape's
incorporation in the OFT. Apart from being able to be oriented,
unit (15) is also provided with a suitable arrangement (not shown)
to move it to a new position to correspond with different lengths
of tapes that might be used depending on their angle of
incorporation in the OFT. To hold different lengths of tape for
laying on arrangement (11), the fork (15a) is preferably of the
telescopic type. Should there be a need for producing a textile
with stretched tapes, the telescopic yoke can be made to
lengthen/expand for stretching the tape, for example by a pneumatic
device.
[0234] On the underside of fingers (15c) and (15c') are clamping
plates (15d) and (15d') respectively as shown in FIG. 13. These
clamping plates (15d) and (15d') are linked to actuators (15e) and
(15e') respectively in a suitable manner whereby these plates can
be individually drawn either toward (closing position) or away
(opening position) from the respective fingers to receive and grip
a range of tape widths directly. This action allows gripping the
tape in its width direction between the two gripping fingers (15c,
15d) and (15c', 15d).
[0235] The gripping fingers (15c, 15d) and (15c', 150 grip or catch
the tape drawn out by arrangement (14) described in the previous
section as follows. Arrangement (15) is retracted such that the
tape drawn out by arrangement (14) can be raised without
encountering any hindrance, particularly from gripping fingers
(15c, 15d) and (15c', 15d) and fork (15a) of arrangement (15). The
tape drawn out by arrangement (14) is raised to a level such that
the gripping fingers (15c, 15d) and (15c', 15d) can receive the
tape in their open mode. Arrangement (15), with its gripping
fingers (15c, 15d) and (15c', 15d) in open mode, is inched towards
the drawn out tape. When the front edge of the tape is in the same
vertical plane as the front edges of the gripping fingers (15c,
15d) and (15c', 15d), the clamp plates (15d) and (15d') are
activated by respective units (15e) and (15e') into close mode. The
drawn out tape is thus held between the gripping fingers (15c, 15d)
and (15c', 15d). The tape is released from gripper lips (14c and
14e) by opening them and cut from its supply source after it has
been gripped by the gripping fingers (15c, 15d) and (15c', 15d) of
unit (15).
[0236] The tape held by unit (15) is released after being laid
adjacently parallel to the previously laid tape by opening fingers
(15c, 15d) and (15c', 15d). The release/removal of the tape from
fingers (15c, 15d) and (15c', 15d) can be assisted, if necessary,
by suitably incorporating pressing bars to keep the tape in
position by pressing/holding it at a few places when unit (15) is
drawn back.
[0237] The pair of units (15) is preferably at the same level
during their working. Each of these units (15) is oriented in a
manner whereby preferably one of the longitudinal edges of the tape
held by each of these units (15) faces in the direction of
arrangement (11). Each of the units (15) lays the entire length of
tapes at once on the bed of arrangement (11). Once the tape is
delivered and released by unit (15) on the bed of arrangement (11)
for incorporation in the OFT, there is no tension in the tape.
Thus, this novel OFT forming method and means does not require the
tapes to be unceasingly tensioned as a condition during production
of OFT.
[0238] It is desirable that yoke (15a) and stem (15b) are made of
relatively lightweight material such as tubes and composite
materials. It is also important that the reciprocation of yoke
(15a) does not cause the tape held in its fingers to
vibrate/flutter unduly highly. The length of gripping fingers (15c,
15d) and (15c' and 15d') are long enough to receive different
widths of tapes directly. An advantage with the use of relatively
wider tapes is the corresponding increase in the production rate of
OFT.
[0239] In an alternative and less preferable method, only one unit
(15) could be used in the described manner whereby it is swung
alternately between two different positions to grip the individual
tapes supplied by the two spools and lay them successively on the
bed of arrangement (11) from two corresponding directions. In a
still less preferable arrangement, only one unit (15) could be used
in the described manner to grip tapes from only one tape supply
source such that single unit (15) swings between two different
positions alternately to lay the tape on arrangement (11) from two
corresponding directions. However, both these methods are
considered inefficient and complex and therefore undesirable.
6. Arrangement for Displacing Fore Ends of the Laid Tapes (16)
[0240] In FIG. 4 are shown the relative positions of a pair of
arrangements (16) for displacing the fore ends of the laid tapes in
their thickness direction. Each of the two arrangements (16) is
located at the two longitudinal sides of arrangement (11) as
indicated earlier in reference to FIG. 5a. This pair of arrangement
(16) is preferred for displacing the fore ends of select tapes that
are laid on the bed of arrangement (11) for producing the OFT. The
pair of arrangements (16) are identical in their workings and
displace the fore ends of select laid tapes in the tape's thickness
direction to create a front-face opening. The arrangements (16m)
shown in FIGS. 14a to 14c, and (16n) shown in FIGS. 14d to 14f,
respectively, are two examples of the means for displacing the fore
ends of tapes. Other possibilities will be listed later on.
[0241] As shown in FIG. 14a, arrangement (16m) comprises a housing
(16a) which has a plurality of slots (16b). The surface of housing
(16a) is preferably smooth and plane so that fibres can slide over
it without getting hooked/caught by, for example, uneven edges. If
required the surface of housing (16a) can be coated with a low
friction material such as PTFE. The slots (16b) are arranged in
series and in a manner that the opposite sides of two adjacent
slots occur in a line (16c). Further, the axis (16d) of each of the
slots (16b) is at an angle .PHI. relative to the longitudinal side
of housing (16a) and this angle corresponds with the angle of
facing tape's width direction.
[0242] Each of the slots (16b) contains a block (16e), preferably
having curved top. Blocks (16e) preferably have a sliding fit with
the respective slots (16b). The width of blocks (16e) is preferably
lesser than the width of the tapes to be processed. These blocks
are preferably smooth and coated with a low friction material such
as PTFE. The function of these blocks (16e) is to displace the fore
ends of the tapes resting over it in the direction of tape's
thickness. Each of these blocks (16e) can be reciprocated, either
independently or collectively in suitable groups according to the
structural pattern to be created in OFT, by available mechanical or
pneumatical or electromechanical devices. The top side of blocks
(16e) can be completely drawn inside slot (16b) such that its top
surface and the surface of housing (16a) are level as depicted by
block (16e') in FIG. 14a. Housing (16a) has suitable provisions,
such as holes (16f), for attaching it to arrangement (11) through
suitable provisions (11e) shown in FIG. 5a.
[0243] In an alternative construction, the blocks (16e), instead of
being in one piece, could be made by joining suitable plates so
that the width of block can be varied as desired, within a range,
by adding or taking away required plates. Suitable round-ended
fingers/pins/bars/plates could be also used in place of
blocks--e.g. when processing relatively narrow tapes. Alternatively
a hinged lid-like arrangement could be provided at the top side of
the housing. When flipped open, it would displace the fore end of
tape and when pressed closed, it would be level with the housing's
surface providing a plane surface to enable the fore ends of tapes
to slide over.
[0244] The top side of block (16e) is preferably curved so that at
least a minimum contact, such as tangential, is achieved when the
fore ends of tapes (T1) are displaced by it in tape's thickness
direction as shown in FIG. 14b. Alternatively, a flat plate/block
could be also used to displace the fore ends of the tapes resting
over it in the direction of tape's thickness. When top of blocks
(16e) occur at the surface of housing (16a), the corresponding fore
ends of the tapes (T2) occur relatively below the fore ends of the
upwardly displaced tapes (T1). As a consequence of selective
displacement of the fore ends of tapes (T1) relative to remaining
fore ends of tapes (T2) that are not displaced, it becomes possible
to create a front-face opening to gain entry for laying tape easily
and directly on arrangement (11) by using arrangement (15) for
producing OFT. Displacement of fore ends of tapes in the said
manner enables to move the tape being laid in its lateral direction
(i.e. the direction of its width). This is unlike weft insertion
associated with weaving wherein the weft always moves in its axial
or length direction.
[0245] It may also be pointed out here that it is sufficient to
raise only every alternate block (16e) shown in FIG. 14b to
displace the alternate fore ends of tapes. This is because as the
OFT is advanced forward, the fore end of tape will also advance to
the next block which can be raised again to displace the fore end
of the new tape.
[0246] Relatively stiff tapes of most types and materials can be
processed satisfactorily by the described action of blocks (16e).
However, when processing certain types of tapes, such as flexible,
flimsy and fragile/delicate, it is possible that the displaced
tapes could get dislodged from the respective blocks, especially
when the new tape is entered in the created front-face opening, and
thereby cause difficulties in OFT production. This problem is
overcome, for example, by incorporating a suction unit (16h) that
is placed over unit (16m) as shown in FIG. 14c. Suction unit (16h)
maintains the fore ends of tapes in raised position after the
blocks (16e) are drawn back into their slots (16b). The blocks
(16e) thus serve to feed the fore ends of the tapes to the suction
unit (16h). The suction unit (16h) and fore end displacing unit
(16m) together preferably constitute the preferred arrangement
(16). The suction action, which can be automatically turned on and
off as required, is enabled by connecting unit (16h) to a suitable
negative air pressure source (not shown) through nipples (16i),
which function either individually or in suitable groups.
[0247] The suction unit (16h) is preferably positioned a little
over and near the vicinity of the fully projecting blocks (16e).
The suction pressure can be just sufficient to hold the fore end of
the tape which is any way lying on the bed of arrangement (11).
When the fore ends of tapes are displaced in the tape's thickness
direction by activating desired blocks (16e), the raised fore ends
of tapes get attracted to suction unit (16h) and can be held
temporarily in that position. The projecting blocks are
subsequently drawn into its housing (16a) to create a full
front-face opening and the new tape can be entered into this
opening as described earlier. Once the to-be-laid tape has gained
entry in the front-face opening, and preferably before the tape is
laid adjacently parallel to the previously laid tape, the suction
unit (16h) is preferably lowered through suitable arrangement (not
shown) and preferably presses the fore ends of the held tapes over
drawn-in blocks (16e) while the negative air pressure is cut off to
let the fore-ends of the tapes become free. By this method
dislodgment of the displaced tapes can be prevented and thereby
ensure satisfactory production of OFT. Alternatively, individual
suction units could be directly used to lift up and lower down the
fore ends of tapes without involving the use of blocks (16e).
[0248] Yet another fore end displacing arrangement is shown by way
of example in FIGS. 14d to 14f. In this arrangement, a plurality of
clamps (16n) is used for displacing the fore ends of tapes.
Essentially each clamp comprises a body (16r) to support the fixed
clamping jaw (16u), the movable clamping jaw (16s) and a connector
(16t) to move the jaw (16s). The connector (16t) is controlled by a
suitable actuator (not shown). A series of clamps (16n) are fixed
to supporting arms (16x) and (16y), as shown in FIG. 14e. The
clamps fixed to arm (16y) are inverted in relation to those fixed
to arm (16x). The distribution of all these clamps can be
preferably relatively alternating and uniform as shown in FIG. 14e.
In the setup shown, while the lower arm (16y) is fixed to the
longitudinal side of arrangement (11) (not shown in FIGS. 14e and
14f) and remains stationary, the upper arm (16x) can be moved up
and down, either linearly or angularly about a pivot. Preferably
the width of clamp (16n) is less than the width of the tape being
processed.
[0249] The fore ends of the tapes (not shown in FIGS. 14e and 14f)
are supported by the alternating clamp jaws (16s) and (16u) which
are arranged to be in one plane in their open position, as can be
inferred from FIG. 14e. The uniform one plane provided by the jaws
(16s and 16u) enables the fore ends of the tapes to slide
unhindered from one clamp to the next (when OFT is advanced
forward) and also to get them clamped between the jaws (16s and
16u). When all the tapes are individually clamped by respective
clamps (16n), the upper arm (16x) is moved upwards as shown in FIG.
14f, whereby the fore ends of tapes clamped to the respective
clamps are correspondingly moved upwards in their thickness
direction. In relation to the fore ends of the tapes that are
clamped to the respective clamps fixed to the stationary lower arm
(16y), the upwardly moved fore ends create a front-face opening
that can receive tape (16z) as can be inferred from FIG. 14f.
[0250] Alternatively, the fore ends of the tapes could be
downwardly displaced in relation to adjacent tapes by suitably
modifying the indicated constructions (16m) and (16n).
[0251] In any case, as the produced OFT gets advanced forward for
winding into a roll, the free fore ends of the tapes will also
correspondingly advance forward and change positions relative to
blocks (16e)/clamps (16n). Arrangement (16) thus uniquely allows
the fore ends of tapes to change positions relative to its
constituent blocks/clamps. Apparently, no free fore end of any tape
will ever get displaced by the same block (16e)/clamp (16n). Thus,
each displacement of the fore end of a tape is done by a different
block/clamp which is uniquely technically and characteristically
unlike the shedding operation of the weaving process wherein the
same warp is controlled all the way by the same heald.
[0252] As can be understood now, the described operation for
displacing the fore ends of the laid tapes to create front-face
opening does not create any shed, as in weaving, that can be
defined by a closed geometrical figure such as rhombus and
triangle.
[0253] A person skilled in the art can understand now that other
methods such as mechanical gripping, pinching, clipping, clamping,
hooking, magnetic action, chemical adhesion, pneumatic blowing,
vacuum gripping, electrical repellency, magnetic repellency etc.
are possible to employ, either singly or in suitable combination,
for achieving the preferred displacement of the individual fore
ends of the tapes in their thickness direction and for maintaining
the fore ends of the tapes in the displaced positions. The method
to be employed for either displacing or maintaining the fore ends
of the tapes will depend on the needs and type of tape material to
be processed. In any case, the fore ends of the displaced and
not-displaced tapes will be held in a firm manner such that the
tape being laid between them will not cause their pulling and
dislodging from the occupied positions. Such functional reliability
will ensure trouble-free operations for producing OFT.
[0254] It will be obvious to a person skilled in the art that to
achieve relatively higher OFT production speed it is important to
keep the displacement of the fore ends of the tapes as small as
practically possible because smaller displacements take
correspondingly lesser time. The displacement of the fore ends of
the tapes could be just small enough to clearly receive the
thickness of the tape to be laid as there is no gripper that needs
to be passed through the front-face opening (as happens in
weaving). Given that SFT and HDPT tapes are rather thin, the fore
ends would be preferred to be displaced by a correspondingly very
small distance. This process thus provides the unique possibility
wherein the free fore ends of tapes need to be displaced by only a
relatively small distance whereby the tapes are not subjected to
any tensioning as happens in weaving process when the warps are
shed. Also, because the displaced fore ends of the tapes can be
reverted to their original positions immediately after the new
to-be-laid tape has entered a little distance in the front-face
opening, the total operation times can be substantially reduced.
Because the created opening is unlike a shed in the weaving
process, the fore ends need not be kept in raised position until
the new tape is laid adjacently close to the previous tape on bed
of arrangement (11).
[0255] Blocks (16e)/clamps (16n), as also any other device that
might be employed, can be activated in either a regular sequence or
a random sequence through a suitable programme to selectively
displace the fore ends of the tapes to create the desired
corresponding primary structural integrity/stability pattern in
OFT. Obviously such a possibility allows to uniquely create
different primary structural integrity/stability patterns with the
tapes drawn from the left and right side spools. Thus the primary
structural integrity/stability pattern on left half of OFT can be
entirely different from that on the right half side.
[0256] It will be amply clear now that arrangement (16) and its
working is technically unlike the shedding arrangement and
operation associated with the weaving process.
7. Arrangements for Consolidating Produced Material (17)
[0257] In FIG. 4 is shown the relative position of a pair of
arrangements (17), which is located over arrangement (11). This
arrangement (17), shown by way of example, is preferred for
consolidating the intersecting and overlapping tapes laid on bed of
arrangement (11) when producing OFT according to this invention.
The consolidation action is preferred to this process because the
created primary structural integrity/stability of OFT is weak in
its longitudinal and lateral directions because of absence of
fibrous materials oriented in its length and width directions. Such
a consolidation step is preferred to impart interconnection between
over-lapping tapes and provide the secondary structural
integrity/stability to OFT to resist formation of opening/gaps in
subsequent handling/processing operations. Preferably the
interconnections are in the forms of connecting points and
connecting areas. The OFT's consolidation is achieved by units
(17a) and (17b) shown in FIGS. 15a and b. It is preferable that the
consolidation is performed at least in a middle part of the
produced OFT as that part initially develops openings/gaps.
[0258] The pair of units (17a) and (17b), which are identical in
working, are described in reference to FIG. 15. The construction
described in FIGS. 15a and 15b is by way of example. Units (17a)
and (17b) are incorporated preferably in a `V` configuration. The
angle between them matches with the angle of the tapes incorporated
in OFT. It is preferable to have arrangement (17) in a split
construction as shown, instead of a single piece construction. This
is because the split construction enables the same parts to be used
as their relative angles can be easily altered to correspond with
the angles of tape's incorporation in OFT.
[0259] Each of the units (17a) and (17b) is essentially modular in
construction (not shown) comprising smaller individual units though
it is shown in FIGS. 15a and 15b to be a collective whole. These
bar-like units (17a) and (17b) preferably alternately press the
respective just-laid tape in the produced OFT on bed (11a).
Preferably the width of the bar-like units (17a) and (17b) is not
greater than the width of the tape being processed. Units (17a) and
(17b) have stems (17c) and (17d), which are connected by suitable
arrangements (not shown) to their respective actuators. The entire
arrangement is finally connected to the mainframe of arrangement
(11). Through such a construction, units (17a) and (17b) always
maintain a constant positional relationship with bed (11a).
[0260] Further, units (17a) and (17b) are preferably constructed to
incorporate either heating/welding elements (e.g. thermal,
infra-red and ultrasonic) or needling elements (e.g. hooked and
barbed wire) or fibre entangling elements (e.g. nozzles for
pressurized gas and liquid) or glue/adhesive applying elements or
fluid spraying elements or vibratory elements etc. Such elements
are incorporated individually and in a manner that their
orientation can be easily rearranged according to needs. Through
use of one or more of these elements, the intersecting and
overlapping tapes are additionally connected and thereby the
produced OFT imparted the secondary structural integrity/stability,
at least in a middle part, and effectively consolidated in its
thickness direction and rendered structurally sound for subsequent
handling. The choice of element to be employed in units (17a) and
(17b) to achieve cohesiveness/interconnection between the laid
intersecting and overlapping tapes will depend on the type of tape
material being processed and the end application needs. The
consolidation units (17) thus preferably provide at least one of
mechanical, chemical, thermal etc. type of secondary structural
stability/integrity to OFT.
[0261] The described consolidation of OFT is preferably
directionally oriented so that the fibres/fibrils are subjected to
the least possible disruption while maximum secondary structural
integrity/stability is achieved in the preferred direction/s.
Directionally oriented consolidation is achieved by incorporating
in units (17a and 17b) the preferred elements (heating, welding,
needling, entangling, glue/adhesive applying, spraying, vibratory
etc.) in desired orientation/s. Through such a directionally
oriented consolidation procedure, the areas of interconnection
between over-lapping tapes can vary from relatively small areas of
overlapping tapes (such as a point) to large (such as entire
overlapping area).
[0262] The connection points or connection areas are preferably
directionally oriented in one or several straight connection lines.
Preferably each straight connection line comprises a plurality of
connection points or connection areas. Preferably, the connection
points or connection areas extends at least in the length direction
of the fabric although their extension in different directions and
in directions parallel to the laid tapes of the two oblique
directions of tapes can be will be beneficial. Preferably, the
connection areas can vary from one or several points to
interconnecting entire area of the overlapping tapes.
[0263] Such interconnection is thus correspondingly oriented in the
desired direction/s (e.g. relative to OFT's length direction) and
can be of either uni-linear or bi-linear or multiple direction
types. Knowing what subsequent process OFT would be subjected to,
the consolidation can be performed in suitable directional
orientation/s that is aligned in the direction/s of the expected
forces of that process. If a high resistance is required to prevent
the OFT from developing openings/gaps then entire overlapping areas
can be interconnected such as by bonding. Through such secondary
structural integrity/stability, in addition to the primary
structural integrity/stability, sufficient strength is realized in
OFT to withstand the normal handling/processing. As a result there
is improved resistance to development of openings/gaps and at the
same time the mechanical properties of tapes constituting OFT, and
that of OFT itself, is not diminished.
[0264] Further, depending on the type of consolidation to be
performed (e.g. needling and entangling), suitable recesses or
cavities can be provided on arrangement (11) in appropriate forms
and places to match with those on the underside of units (17a) and
(17b) to enable needles, fluid jets etc. perform properly. Because
the working of units (17a) and (17b) and arrangement (11) have a
constant relative position relationship, the preferred recesses and
cavities can be machined on different plates which can be
interchanged and fixed at the predetermined positions on
arrangement (11) as and when required.
[0265] The construction of each of the units (17a) and (17b) can be
preferably modular so that the same units can be rearranged and
rendered useful to process tapes of different widths directly.
Further, units (17a) and (17b) be preferably coated with a suitable
material, e.g. with non-sticky and low friction material such as
PTFE. Units (17a) and (17b) could be also provided with suitable
shoes that can be easily taken off for cleaning, changing settings
etc. These shoes can be also suitably spring loaded to ensure
proper contact with the tapes under it. Further, the sole of these
shoes could be of either hard or soft types and either plain or
suitably designed for creating a pattern or logo through pressure
impression, heat embossing etc.
[0266] After a tape has been laid to form OFT on arrangement (11),
the respective unit (e.g. 17a) is activated on the section of the
just-produced OFT to consolidate the laid tape and the tapes with
which it associates by interconnecting at least some of their
overlapping areas. The next tape from the other direction is laid
on arrangement (11) to form OFT and the other unit (17b) is then
activated on the section of the just-produced OFT to consolidate
the newly associated tapes as described before. Alternatively,
tapes from two directions can be laid to form OFT on arrangement
(11) one after another and then units (17a) and (17b) can be
simultaneously activated on the produced OFT to consolidate them
for imparting secondary structural integrity/stability. Likewise,
units (17a) and (17b) can be moved away from the produced OFT after
performing consolidation procedure either one after another or
simultaneously.
[0267] As can be observed, through the described consolidation
process the produced OFT has its constituent tapes uniquely
interconnected, and preferably only at the desired overlapping
areas of the tapes, in the produced OFT's thickness direction and
thereby imparted a certain additional structural
integrity/stability or cohesiveness, in addition to the primary
structural integrity/stability. As a consequence, there is certain
material flow in the thickness direction of the tapes. For example,
if tapes of fibrous materials are used and the needling
consolidation arrangement is employed, then some fibres would flow
between the upper and lower tapes' thickness directions wherever
the consolidation is performed. Similarly, if spot gluing/adhesion
is performed then there will be flow of glue/adhesive in the
thickness direction of the OFT. Such flow of material (fibres,
glue, adhesive etc.) will provide certain secondary
interconnectivity/cohesiveness in the tapes' thickness direction
and thereby render OFT additionally structurally stable/integrated
for subsequent processing and handling needs. Flow of material also
happens when interconnectivity between tapes is achieved, e.g. when
tapes of either a polymeric material or fibrous tapes comprising
polymeric and non-polymeric materials are used such that they can
be consolidated thermally by fusing. In this case there will be a
flow of some molten polymeric material in thickness direction which
will fuse the upper and lower tapes together wherever thermal
consolidation is performed. Likewise, if an adhesive is used for
consolidation then, for example, connectivity between the surfaces
of contacting tapes can be achieved in the thickness direction of
the tapes through adherence. Likewise, if an adhesive bearing tape
is used then the adhesive can be activated by pressure (or
heat/water etc. if so required) to help bond the upper and lower
laid tapes in the their thickness direction and thereby impart
secondary structural stability/integrity to OFT. Such adhesive can
be also activated partly for consolidation and partly later for
adhering the OFT to other surface/s.
[0268] The consolidation of OFT described above is preferably
performed at places where needed and not necessarily all over OFT.
For example, it might be sufficient to perform consolidation only
in a middle part of OFT, or in a certain patterned way. Depending
on the end use or application of OFT it might be preferable to
consolidate at the OFT edges as well. Further, the degree of
consolidation can be also performed according to needs. For
example, the needling area and the welding area can be relatively
small and large. The consolidation can be also directionally
oriented to impart consolidation in expected direction of
force.
[0269] Accordingly, in FIGS. 15c to 15k are shown some examples of
different forms of directionally oriented secondary structural
integrity/stability achievable through the described consolidation
units (17). FIGS. 15c and 15d respectively show linear
consolidation oriented in longitudinal and lateral directions of
the OFT and such structural integrity/stability is performed at
some tape overlapping regions/areas in a middle part of OFT. FIG.
15e shows bi-linear consolidation performed jointly in both
orientations and at desired regions. FIGS. 15f and 15g show
combination of longitudinal and lateral linear consolidations in
two orientations in different styles. FIG. 15h shows multiple
direction consolidation at desired places of OFT. FIGS. 15i and 15j
respectively show single and multiple spot consolidations at select
regions of OFT. FIG. 15k represents another multiple direction type
of consolidated OFT wherein large overlapping areas are
interconnected, such as possible by adhesive bonding.
[0270] As can be inferred, the described consolidation process
accords secondary structural stability/integrity, and preferably
only at the desired overlapping areas of the tapes, to OFT equally
in its length and width directions and imparts additional strength
to OFT for resisting formation of openings/gaps when processing and
handling it. Through the described consolidation procedure
inclusion of extra longitudinal yarns in OFT is rendered
unnecessary. Thereby, the attending drawbacks of incorporating
extra yarns, such as uneven fibre distribution in OFT and uneven
thickness of OFT described earlier, is eliminated. A bias fabric
having secondary structural stability/integrity, through the
described consolidation procedures, has previously not been
known.
8. Arrangement for Advancing Forward Produced Material (18)
[0271] Because the produced OFT has no fibrous materials
(yarns/filaments) that are incorporated in the orientation of the
fabric-length direction, the produced OFT cannot be pulled in the
fabric-length and width directions without causing its deformation
or damage. Therefore, it becomes preferred to feed OFT in a
tensionless manner and advance it positively forward for winding it
into a roll for subsequent handling and transportation.
[0272] In FIG. 4 is shown the relative position of arrangement
(18), which is located over arrangement (11). This arrangement
(18), shown in FIGS. 16a and 16b by way of example, is preferred
for aiding the forward advancement of OFT in conjunction with
arrangement (11) (shown in FIGS. 5a-b). Arrangement (18) is
essentially composed of three elements; the first element (18a) is
shown in FIG. 16a, and the other two (18c) and (18e) are shown in
FIG. 16b. Advancing of OFT is achieved jointly by these elements
(18a, 18c and 18e) shown in FIGS. 16a and 16b and arrangement (11)
(i.e. through stationary bed (11a) and reciprocating plate (11f))
shown in FIGS. 5a and 5b.
[0273] The construction of elements (18a, 18c and 18e) shown in
FIGS. 16a and 16b are by way of example. Thus, instead of having
elements (18a, 18c and 18e) in plate form, they could be realized
using suitably arranged bars so that their area of contact with
OFT, which they shall press against reciprocating plate (11f), is
as small/large as preferred. Having the elements (18a, 18c and 18e)
in a modular construction is preferable than a single piece
construction because the angular part of elements (18a, 18c and
18e) can be easily matched with the angle of the laid tapes. The
modular construction will be also advantageous when producing an
OFT that incorporates tapes at unequal angles.
[0274] The `V` shaped projection on element (18a) provides the
preferred clearance for laying the tapes from the two directions
close to the previously laid tapes that are already incorporated in
the body of OFT.
[0275] Elements (18a, 18c and 18e) can be provided with suitable
stems (18b, 18d and 18f) respectively, as shown in FIGS. 16a and
16b. The purpose of these stems is to connect the element (18a, 18c
and 18e) to their respective actuators (not shown) for their
raising and lowering to press OFT for forwarding and for releasing
OFT after it has been forwarded. The length and number of stems
will depend on the design of other working systems. The elements
(18a, 18c and 18e) are finally connected to reciprocating bed (11f)
through suitable construction (not shown) whereby a constant
positional relationship is always maintained between them.
[0276] While element (18a) will press on the body of OFT, elements
(18c and 18e) will press on the tapes that are freely extending
from the body of OFT. Such pressing of OFT material and also the
extending tapes on reciprocating bed (11f) is preferred not only to
reliably move forward the produced OFT to the winding unit, but
also to correspondingly reliably advance forward in a controlled
manner the freely extending tapes from the body of OFT. Without the
action of elements (18c and 18e), the freely extending tapes from
OFT's body will drag in an uncontrolled manner leading to their
disorientation and positional change, which in turn will cause
problems in the subsequent steps of the process, particularly
displacement of the fore ends of the laid tapes by arrangement
(16). The elements (18a, 18c and 18e) can work either
simultaneously or independently in desired sequences.
[0277] Elements (18a, 18c and 18e), whether in plate or bar forms,
need not be necessarily flat. The side facing OFT can have uniform
projections so that they can exert uniform pressure on OFT without
making a full surface contact. Such a construction will prevent
lateral displacement of OFT and the freely extending tapes from the
body of OFT such as when elements (18a, 18c and 18e) are lowered
and raised. The air between OFT and the elements (18a, 18c and 18e)
will escape easily in a non-planar construction, than with a planar
construction, and thereby not cause the attending creation of any
vacuum when lifting up.
[0278] The projections on elements (18a, 18c and 18e) can have
smooth surfaces besides preferably a coating of anti-stick material
such as PTFE. These projections could be also suitably perforated,
or provided with channels, so that the air between OFT and these
elements (18a, 18c and 18e) can easily escape when the elements are
lowered for pressing OFT and the freely extending tapes from the
body of OFT and thereby ease the raising of elements (18a, 18c and
18e) without lifting up OFT and the freely extending tapes.
[0279] Alternatively, elements (18a, 18c and 18e) could be replaced
with an arrangement that applies preferred air pressure on OFT.
Such an arrangement could be considered as a contact-less
arrangement and it need not be lowered and raised.
[0280] To advance OFT forward for winding in a controlled manner,
elements (18a, 18c and 18e) are supported in a sliding arrangement
(not shown) and suitably connected to the reciprocating plate
(11f). Through such construction, elements (18a, 18c and 18e) have
defined reciprocating positions corresponding with that of the
reciprocating plate (11f). Thus elements (18a, 18c and 18e), when
resting over OFT and reciprocating plate (11f), can be moved
equally and simultaneously with the reciprocating plate (11f) to
advance forward the OFT for winding. Likewise during retraction of
reciprocating plate (11f) the raised elements (18a, 18c and 18e)
can be moved back equally and simultaneously with the reciprocating
plate (11f) to be in correct position for the subsequent cycle of
the process.
[0281] In addition to the above parts, there is also incorporated a
pressing plate/bar (19k), as shown in FIG. 18a. This plate (19k) is
located over the flat stationary area of arrangement (11), i.e. on
bed (11a) and near the projecting fingers (11b). The purpose of
this plate (19k) is to press OFT against the stationary area of
arrangement (11) to hold the forwarded OFT in position and prevent
it from being pulled back when elements (18a, 18c and 18e) and
reciprocating plate (11f) are retracted after jointly aiding OFT's
forward advancement for winding it into a roll. Thus, the pressing
plate (19k) is activated to press the forwarded OFT against the
stationary area before elements (18a, 18c and 18e) are raised/drawn
away from OFT's surface. The plate (19k) is raised/drawn away from
OFT after elements (18a, 18c and 18e) press OFT on bed (11f) to
effect forward movement of produced OFT.
[0282] The foregoing description describes forward advancement of
OFT during Continuing Phase (after OFT's body has attained its full
width). However, initially when the OFT production commences in the
Starting Phase the body of OFT starts to grow longitudinally and
laterally. To handle the issuing tapes from the relatively small
body of OFT, certain constructional features are temporarily
needed, although it could be managed manually if preferred. This
essentially includes suitable extensions to elements (18a, 18c and
18e). Thus, the elements (18a, 18c and 18e) could be initially
connected with similar, but suitably dimensioned, temporary
elements through joining/connecting arms. The purpose of these
temporary elements is to assist the forward advancement of the
tapes extending in the direction opposite to the growing body of
OFT. Once the body of OFT attains its full width and passes the
winding side of arrangement (11), these extensions can be removed
and the extending tapes cut. The OFT advanced forward is then
preferred to be wound into a roll.
[0283] A novel feature of the OFT advancing method is that the
distance by which OFT is advanced forward is greater than the used
tape's width as indicated earlier. This unique situation arises
from the incorporation angle of the tapes in OFT. The angle
subtended by the constituent tapes of OFT could be either acute
angle or right angle or obtuse angle as shown in FIGS. 17a to 17c.
Thus, for the same width of tapes, the distance of advancement for
OFT incorporating tapes in an acute angle relationship (x.degree.
in FIG. 17a) will be L1, which will be greater than when the tapes
are incorporated in a right angle relationship (y.degree. in FIG.
17b) which is L2, and this distance in turn will be greater than
when the tapes are incorporated in an obtuse angle relationship
(z.degree. in FIG. 17c) which is L3. Thus, for the same tape width,
the distance for advancing forward OFT will vary according to the
angle of tapes' incorporation in OFT.
[0284] The distance for advancing forward OFT would roughly
correspond with the length of the longitudinal diagonal (the one
parallel to the fabric-length direction) of the
`square/parallelogram/rhombus` created by the intersecting and
overlapping tapes.
9. Arrangement for Collecting Produced Material in a Roll (19)
[0285] Even though OFT is consolidated for handling, its strength
in longitudinal direction could be relatively lower at times
compared with a fabric that incorporates fibres oriented in its
length direction, such as the woven material. As indicated earlier,
the produced OFT requires careful handling during its collection in
a suitable package, such as when winding it into a roll. Further,
because OFT is produced using discrete lengths of tapes, it becomes
preferred to keep the winding distance as short as possible so that
the OFT does not develop openings/gaps or come loose. Therefore,
the roll of OFT should be preferably produced as close as possible
to the point where the full body width of OFT gets formed. It is
also important to ensure that OFT proceeds in a more or less linear
path to prevent its skewing and also to obtain a satisfactory
package and quality for subsequent handling and intended
application.
[0286] In FIG. 4 is shown the relative position of arrangement
(19), which is located at the OFT winding side of arrangement (11).
This arrangement (19), shown by way of example, winds up the
produced OFT in a tensionless manner. FIG. 18a shows different
parts of arrangement (19), which mainly comprises an exit guide
roll (19a), a J-shaped tray (19b) and a winding shaft (19g). FIG.
18b shows the path followed by OFT (19m) between arrangement (11)
and finished roll (19n).
[0287] The axis of exit roll (19a) is parallel to the winding side
edge of arrangement (11). Also, it is preferably located below the
top surface of bed (11a) so that the produced OFT can preferably
pass tangentially over the exit roll (19a) from bed (11a).
[0288] A J-shaped tray (19b), which is suspended below exit roll
(19a), as shown in FIG. 18a, extends parallel to the exit roll
(19a). It is preferably produced using a suitable sheet metal. The
top side of J-shaped tray (19b) is pivoted (not shown) at the front
end of bed (11a) and can be tilted upwards and locked into a
suitable angular position .theta., as shown in the inset of FIG.
18a. The angle of tilt would depend on the stiffness and areal
weight of the OFT being produced. Thus, a relatively pliable and
lighter areal weight OFT will have a correspondingly different
angular tilt. The exit side of J-shaped tray (19d) is either
directly shaped into a suitable curve or fixed to a suitably curved
member (such as a suitable tube) to provide a gentle and smooth
exit to OFT (19m). Further, the depth of J-shaped tray (19b) can be
varied according to the stiffness and areal weight of the OFT being
produced.
[0289] The surface of J-shaped tray (19b) is preferably as smooth
as possible and also preferably coated with a
low-friction/anti-sticking material such as PTFE. Preferably two
end plates (19c and 19c') are fixed to J-shaped tray (19b) to
provide linear guidance to OFT (19m). The positions of these end
plates (19c and 19c') can be altered according to the width of OFT
being produced. This way the longitudinal edges of OFT will remain
linearly guided in its path. If preferred, guide rings or the like
can be also mounted on exit roll (19a) to control the path of OFT
(19m). To exercise further control for keeping the OFT (19m) in a
linear path, additional end plates could be included where
preferred on the J-shaped tray (19b). Alternatively, J-shaped tray
could be also made using perforated sheet metal to keep the OFT
(19m) pressed on to its surface by applying suitable vacuum
pressure from the other side.
[0290] While use of one J-shaped tray (19b) is considered
sufficient, additional J-shaped trays could be also had in tandem
if preferred for greater process control. In such a situation the
OFT would pass from one tray to the next before being wound into a
roll.
[0291] For winding up the produced OFT (19m), two factors are
important to consider: (a) virtually no tension can be applied to
OFT (19m) in its length and width directions, and (b) the OFT
production process is, technically speaking, endless. In these
circumstances, it is preferred to have a suitable system for
winding the produced OFT (19m) in tensionless condition into rolls
of specified lengths one after another.
[0292] Accordingly, as shown in FIG. 18a, a novel OFT winding
system (19s) is provided, which comprises two arms (19e and 19e')
fixed to middle shaft (19f) that can be turned around its axis (X).
The ends of arms (19e and 19e') carry shafts (19g) and (19h) as
shown in FIG. 18a. Each of these shafts (19g) and (19h), which can
be rotated about their respective axes (Y) and (Z) through suitable
driving arrangement (not shown), can be attached to and detached
from the respective sides of the arms (19e and 19e'). Thus, the
positions of shafts (19g) and (19h), relative to J-shaped tray
(19b), can be inter-changed by turning the middle shaft (19f) about
its axis (X) by 180.degree..
[0293] To start with, as shown in FIG. 18b (inset), preferably
shaft (19g) is located over exit end (19d) of the J-shaped tray
(19b) so that the produced OFT (19m) is more or less vertically
tangential to shaft (19g). The leading end of OFT (19m) is adhered
to the core sitting on shaft (19g), which in turn is incrementally
rotated through suitable drive (not shown) in the appropriate
direction. The turning of shaft (19g) is synchronized with the
movement of OFT advancing arrangements (18a, 18c and 18e) and
reciprocating plate (11f). As OFT (19m) gets wound over its core
that sits on shaft (19g), the diameter of OFT roll (19n) increases.
To maintain the produced OFT vertically tangential at all times to
the roll being produced, winding unit (19s) is gradually moved away
from the J-shaped tray (19b) in suitable increments. A suitable
over-riding clutch (not shown) is incorporated in the drive to
shaft (19g) to prevent any pulling of the produced OFT (19m). Such
a winding arrangement (19s) eliminates sagging of the produced OFT
(19m) under its own weight and thereby enables its tensionless
winding.
[0294] Once a preset length of OFT (19m) is wound into a roll
(19n), the production of OFT is either briefly slowed down or
paused and shaft (19g) is turned through suitable drive to unwind
some length of OFT (19m). The middle shaft (19f) is then turned
180.degree. such that the just unwound OFT (19m) and interleaving
film/foil (19p) extends from the position of axis (Z) to the
winding position of axis (Y). The film/foil (19p) is cut off from
its supply roll (19q) at a suitable place to expose the underside
of OFT (19m) to the new core which lies touchingly under it. The
new core sitting on shaft (19h), which presently occupies the
earlier position of shaft (19g), adheres to the unwound OFT through
a suitable adhesive that is applied over it before turning shaft
(19f). OFT is then cut at a suitable place so that the produced
roll can be taken off.
[0295] The film/foil (19p) is preferably passed through a positive
feeding arrangement that constantly delivers preferred length of
film/foil, corresponding with the length of OFT advanced forward,
for tensionless winding of OFT. The film/foil (19p), coming from
its supply (19q), is also affixed to the new core and the OFT
production commenced again. By this procedure the production of OFT
(19m) continues without tensioning and causing misalignment of OFT
(19m) in any way. Also, by suitably slowing down tape laying and
fabric advancing steps in relation to the described winding
procedure, a continuity of OFT production can be achieved without
having to halt the process for achieving relatively higher
productivity.
[0296] To prevent the layers of OFT from getting stuck to each
other in the OFT roll (19n) that is being produced, an interleaving
film or foil (19p) of a suitable material is supplied from roll
(19q). The film/foil (19p) can be passed between the nip of a pair
of rolls (not shown) so that by turning these rolls the preferred
measured length of film/foil (19p) can be correspondingly paid out.
Through such an arrangement the take-up of OFT and film/foil (19p)
is equal and no tension is imparted to the OFT (19m). Incorporation
of interleaving film/foil (19p) between the OFT layers in the roll
(19n) renders subsequent handling of OFT safer as the unrolled OFT
also gets supported by the film/foil (19p).
Working of the Device and Fabric Production
[0297] The various systems of the OFT forming device described
above work collectively in coordination according to the method
comprising the Starting and Continuing Phases described earlier.
The production of OFT, wherein the constituent tapes occur in a
tensionless state and in angular orientation relative to the
fabric-length and -width directions, will become apparent to the
person skilled in the art from the following outline.
[0298] The working of the device outlined below is general and only
by way of illustration. It can be modified in different ways
according to the needs of a situation. The working that is
described below, which can be run by using a suitable programme,
relates to creation of OFT structure wherein the tapes intersect
and overlap each other alternately. As the OFT forming device
comprises two identical sets of working arrangements for laying the
tapes from two directions, the description below will therefore
have greater focus on one set of arrangements than the other, which
may be considered as the left and right sets of arrangements. FIG.
4 represents the OFT forming device in general.
[0299] The width of the working bed (11) is prepared according to
the width of OFT (19) preferred to be produced. The left and right
side tape spools (12) are mounted on their respective shafts/chucks
and positioned according to the desired angular orientation of the
tapes to be incorporated in OFT (19). The leading ends of the tapes
are drawn out from the two spools (12), guided over exit rolls and
fed to respective holding clamps for positioning. Cutters (13) are
positioned according to the desired angle of cut preferred in the
tapes.
[0300] Starting Phase
[0301] Tape from the left spool is drawn out by arrangement (14).
The gripper of arrangement (14) holds the drawn out tape. The tape
laying arrangement (15) is moved into position such that its
fingers grip the fore and aft ends of the drawn out tape, which is
then cut by the cutter (13). The tape laying arrangement (15) is
then moved in the direction of bed (11) carrying the tape. Upon
reaching the defined end position, arrangement (15) releases and
lays the tape on bed (11) whereby the tape occurs in a tensionless
state. The laid tape's fore end that is closer to the right side
spool, rests over the fore end displacing element of right side
arrangement (16). Tape laying arrangement (15) is then retracted to
its starting position. The described procedure is performed with
the respective right side arrangements whereby the right side tape
is laid above the previously laid left side tape on bed (11) such
that its fore end which faces the left side spool rests over the
fore end displacing element of left side arrangement (16).
[0302] The left side tape is subsequently laid adjacently parallel
to the previously laid left side tape and above the laid right side
tape. These laid tapes are suitably consolidated by arrangement
(17) at the overlapping areas created by the upper and lower tapes
and advanced forward by arrangements (11) and (18) jointly. With
the laying of these three tapes the Starting Phase of the process
is completed.
[0303] Continuing Phase
[0304] The first laid left side tape's fore end that is facing the
right side tape spool is displaced in its thickness direction by
arrangement (16) of the right side. The right side tape, which is
by now drawn out from its spool and gripped by the fingers of the
right side tape laying arrangement (15), is cut and moved towards
bed (11) and laid in a tensionless condition adjacently parallel to
previously laid right side tape whereby it associates with earlier
laid tapes by partly occurring below the first laid left side tape
and partly above the second laid left side tape. The remainder of
the laid tape lies exposed on bed (11). The displaced fore end of
the left side tape is reverted to its initial position on bed
(11).
[0305] Next, the first laid right side tape's fore end that is
facing the left side tape spool is displaced in its thickness
direction by arrangement (16) of the left side. The left side tape,
which is by now drawn out from its spool and gripped by the fingers
of the left side tape laying arrangement (15), is cut and moved
towards bed (11) and laid in a tensionless condition adjacently
parallel to previously laid left side tape whereby it associates
with earlier laid tapes by partly occurring below the first laid
right side tape and partly above the second laid right side tape.
The remainder of the laid tape lies exposed on bed (11). The
displaced fore end of the right side tape is reverted to its
initial position on bed (11).
[0306] These laid tapes are suitably consolidated by arrangement
(17) at the overlapping areas and advanced forward by arrangements
(11) and (18) jointly.
[0307] The produced OFT is advanced forward causing the tapes
extending from the just produced OFT's body to new positions in
reference to the tapes' fore end displacing elements of arrangement
(16). Thus, the fore ends of the second laid left and right tapes
would now rest over the fore end displacing elements of the left
and right sides of arrangement (16) that displaced the previous
tapes of the respective sides.
[0308] The fore ends of the laid left and right side tapes are
alternately displaced and fresh tapes from the two respective sides
are laid, consolidated and advanced forward as described
earlier.
[0309] As more tapes are laid the body of OFT grows in both
longitudinal and lateral directions until it reaches its desired
maximum width whereupon the body of OFT would resemble a square
with two of its opposite corners located in the longitudinal centre
of OFT (i.e. pointing in OFT's length direction) and the other two
opposite corners located at OFT longitudinal edges (i.e. pointing
in OFT's width direction). Continuation of the process from this
point on, in the described procedure, will make the body of OFT
grow only longitudinally (not laterally or in width direction).
Consequently, the shape of OFT body will change from square to
hexagon-like wherein the two longitudinal edges of OFT will be the
two parallel sides of the hexagon. The body of OFT is thus not
rectangle-like at any instant.
[0310] The described process of OFT formation according to this
invention can continue without end so long as tapes are made
available for laying from two directions. While replenishing
exhausting spools with fresh ones automatically in the OFT forming
device is one option, the other could be, for example, storing
continuously cut tapes of preferred length in a certain manner in a
suitable magazine and automatically presenting the ends of each
tape to the tape laying arrangement (15).
[0311] It will be obvious now to a person skilled in the art that
the indicated steps involved in OFT forming device according to
this invention can be suitably incorporated in a programme to run
the process. The device uses no components that can be considered
to be like those used in weaving, knitting, braiding and non-woven
processes. Further, the OFT forming device has relatively very few
and simple working components. The described OFT process and its
production device can be modified in many different ways without
deviating from the principle of this novel process and the
procedures described above to make it efficient and productive.
They can be also modified for versatility as described next.
Process and Device Alterations for Producing Different Fabric
Structures
[0312] The description given above sets the fundamental outlines of
the novel process, which can be employed to produce OFTs having
alternating, and also any other, intersecting and overlapping
pattern of the tapes of two directions that are incorporated in
equal angles relative to the longitudinal sides of arrangement (11)
in three styles:
a) The tapes mutually subtend acute angle between them (x.degree.)
as shown in FIG. 17a, or b) The tapes mutually subtend 90.degree.
between them (y.degree.) as shown in FIG. 17b, or c) The tapes
mutually subtend obtuse angle between them (z.degree.) as shown in
FIG. 17c.
[0313] By making the angles of the two supply tape's different in
relation to the longitudinal side of arrangement (11), an OFT
having alternating, as also any other, intersecting and overlapping
of the tapes in unequal angles is producible as shown in FIG. 19.
Such an `unequal angle` OFT can be also produced in three different
styles, as indicated above, wherein the tapes mutually subtend
acute, right and obtuse angles respectively. Because the tapes are
laid in unequal angles relative to the longitudinal side of
arrangement (11), the length of tapes of two directions will also
be unequal.
[0314] Within the working principle of the OFT forming process
described above, and with certain modifications to the OFT forming
device and operations to be described below, tapes can be folded to
create entirely new OFT products directly. It is important to
consider these aspects here for two reasons because through such a
change: 1) a single tape is folded and simultaneously laid in two
oblique directions, and 2) characteristically different OFT
structures, compared with the ones described above, can be
produced.
[0315] The particular operational and device changes concern
essentially folding the tapes, either when they are being laid or
preferably after they have been laid on arrangement (11). In
accordance with the preferable way, a working principle for folding
tapes is shown in FIGS. 20a-20d. First, as shown in FIG. 20a, a
tape (T) which is laid straight on bed (11), has its lower and
upper ends at reference sides P1 and P2 respectively. The lower end
(X) of tape (T) is held by the gripper of the tape folding unit
(G), which can be turned back and forth as indicated in the
figures. If preferred, folding unit (G) can be also axially
reciprocated (not indicated in FIGS. 20a-20d)) to compensate for
any length changes of the tape during folding operation. More than
one tape folding unit (G) can be employed in the process and from
different directions if necessary. Next, as shown in FIG. 20b, a
flat finger (F) is brought into position over tape (T) to
press/hold it at the point where it is preferred to be folded.
Finger (F) then presses and holds tape (T) on bed of arrangement
(11) as shown in FIG. 20b. The tape folding unit (G) is then turned
so as to transport the end (X) of tape (T) from reference side P1
to the opposite reference side P2 as shown in FIG. 20c whereby the
tape (T) gets folded at the edge of flat finger (F). The gripper of
folding unit (G) then releases the end (X) of tape (T). After the
tape folding is completed, the flat finger (F) is removed from
between the folded tape (T) as shown in FIG. 20d and the folding
unit (G) reverted to its initial position at P1 for receiving the
subsequent tape needing folding. The tape's fold is then pressed
for creasing, if necessary. Thus, the same straight tape folds and
extends straight in two opposite directions simultaneously and
between the two longitudinal edges of OFT.
[0316] Alternatively, a simple conventional pick-and-place robot
can be installed to fold the tape. Yet another way would be to
modify the construction of the tape laying unit (15) such that in
place of the left gripper (15c-15d) in reference to FIG. 13, a tape
direction changing pin is fixed, say at 45.degree. orientation (not
shown). The gripper (15c-15d) can be fixed at the rear end of stem
(15b) through an extending arm so as to hold the tape's
rear/trailing end and maintain the tape parallel to stem (15b).
When the front/leading end of the tape has been held by the right
side gripper (15c'-15d') the tape gets turned at the direction
changing pin as its rear/trailing end is held by the gripper
(15c'-15d') which is located/fixed on an arm extending from stem
(15b). This way the tape gripped between the two grippers will
occur pre-folded at 90.degree. and can be directly laid on bed of
arrangement (11). Thus, the same tape will extend in two opposite
directions simultaneously and between the two longitudinal edges of
OFT as described in the foregoing.
[0317] By including the tape folding step presented above, a
characteristically different OFT structure shown in FIG. 20e is
created. The OFT shown in FIG. 20e is unique in that its one
longitudinal edge is completely closed/sealed. The main steps in
the production of such an OFT is shown in FIG. 21a-c, which are
self-explanatory. A tape of given length is laid and folded midway
whereby it occurs in two different and opposite directions as shown
in FIG. 21a. For explanation, the folded tape occurs such that half
of it is up-sloping and the remainder half is down-sloping. The
down-sloping/lower fore end of the first tape thus faces its supply
spool and rests over the first element of the fore end displacing
arrangement (not shown in FIG. 21a). The lower fore end of the
first down-sloping tape is then displaced in tape's thickness
direction and the next/second tape is laid parallel and adjacent to
the up-sloping half of the first laid tape and folded such that its
up-sloping half occurs under the first tape's down-sloping half.
The folds of the two tapes form a straight longitudinal edge as
shown in FIG. 21b. After consolidating the overlapping tapes the
produced material is forwarded such that the down-sloping fore end
of the laid second tape faces its supply spool and rests over the
fore end displacing block/clamp of the fore end displacing
arrangement (not shown in FIG. 21b). In the next cycle, the lower
fore end of the second down-sloping tape is then displaced in
tape's thickness direction and third tape is laid parallel and
adjacent to the up-sloping half of the first laid tape and folded
such that its up-sloping half occurs under the second tape's
down-sloping half. The folds of the three tapes form a straight and
closed/sealed longitudinal edge as shown in FIG. 21c. After
consolidating the intersecting and overlapping tapes, the produced
material is forwarded such that the down-sloping fore end of the
laid third tape rests over the next fore end displacing block/clamp
of arrangement (not shown in FIG. 21c).
[0318] By continuing the described procedure, the number of
down-sloping tapes will increase in longitudinal direction of
arrangement (11) and the body of OFT will also correspondingly
increase until its preferred width is reached. The fore ends of the
down-sloping tapes concerned will be displaced by the blocks/clamps
of the arrangement (16) and new tapes laid and folded as described
earlier. As can be inferred now, continuous repetition of the
described steps will result in an OFT having one closed/sealed
longitudinal edge as shown in FIG. 20e. It would be also apparent
that the described OFT structure is produced by using only one
source of tape supply and one set of certain working arrangements
which would directly reduce the cost of the device considerably.
Also, because the same tape lies folded in two directions at the
same time, the production of OFT tends to increase considerably. An
important feature of the produced OFT is that the thickness of
folded tapes and that of the OFT body remains same.
[0319] It will be apparent now to a skilled practitioner of the art
that through the principle of folding operation described above and
with further suitable modifications, if both left and right side
tape supply sources and working arrangements are used, then by
folding tapes in longitudinal and lateral directions of arrangement
(11), as described in the foregoing, the following different OFT
structures can be produced:
1) OFT incorporating two sets of folded tapes whereby
slits/openings are created within the body of OFT such that:
[0320] a) The slits/openings are oriented in OFT's length direction
(`vertical`) and such slits occur along OFT's longitudinal axis as
shown in FIG. 22, the main production steps of which are
illustrated in reference to FIGS. 23a to 23e, which are self
explanatory. Thus, after some full length tapes have been laid in
the manner described earlier (FIG. 23a), the subsequent tapes are
folded towards left side (FIG. 23b) and right side (FIG. 23c). Full
length tapes are next laid for as many times as necessary from both
sides (FIGS. 23d and 23e) whereby OFT with a vertical slit along
longitudinal axis shown in FIG. 22 is produced.
[0321] b) The slits/openings are oriented in OFT's length direction
(`vertical`) and such slits occur offset from OFT's longitudinal
axis as shown in FIG. 24 following steps similar to the ones
described in the foregoing.
[0322] c) The slits/openings are oriented in OFT's width direction
(`horizontal`) as shown in FIG. 25. In producing this type of OFT,
the laid tapes are folded in desired directions by incorporating
the folding unit in preferred orientation. The sequential steps are
illustrated in FIGS. 26a to 26m which are self explanatory and
require no detailing other than indicating that certain tapes will
occur temporarily partly over a previously laid tape of that
orientation (if it is not directly supplied and inserted as folded
tape) and then folded. As could be inferred from FIGS. 26f and 26i,
the last laid tape is directly shown to be folded though it
occurred temporarily partly over previously laid tape of that
orientation before being folded as illustrated.
[0323] d) The slits/openings are oriented in both the fabric length
(i.e. vertical) and width (i.e. horizontal) directions as shown in
FIG. 27a.
[0324] The slits/openings may be used to mechanically connect the
fabric to additional tapes/bands, of either fibrous or non-fibrous
types, by passing the additional tapes/bands through the
slits/openings. Examples of such arrangements are illustrated in
FIGS. 27b-e. Such structures constitute a multiaxial structure.
2) OFT incorporating two sets of folded tapes whereby the folds
occur intermittently along both longitudinal edges in three
different styles as shown in FIGS. 28a to 28c, the main production
steps of which are illustrated in reference to FIGS. 29a to 29k
which are self explanatory and not detailed further. These FIGS.
29a-k represent one cycle of producing both longitudinal edges
partly sealed. FIGS. 28a-c show OFTs wherein the two longitudinal
edges are partly closed and partly open. The OFT in FIG. 28a has
its tapes' ends protruding out of the longitudinal edges. The OFT
in FIG. 28b has its tapes ends cut in an angular manner such that
the cut ends are in line with the OFT's longitudinal edges. The OFT
in FIG. 28c has its tapes' ends within the longitudinal edge of OFT
(i.e. the tapes' ends do not protrude out of the OFT's edges).
[0325] It may be pointed out here that the `vertical` and
`horizontal` slits/openings in OFT mentioned above could occur in
either series or parallel relative to either fabric length or width
directions. Further, the frequency of such `vertical` and
horizontal` slits/openings could be had in either regular or
irregular manner in a given length of fabric.
Possibilities of Producing OFTs Using Different Materials
[0326] It will be obvious now to those skilled in the art that the
described method and device can be employed to produce OFTs
comprising either one or more or combination of different materials
of tapes from a selection of the following: [0327] (i) Fibrous
material (textile ribbons/bands/nets, natural and
polymeric/synthesized fibres, organic fibres/filaments and
inorganic fibres/filaments, metallic fibres/filaments/wires, and
including paper and paper based), [0328] (ii) Non-fibrous material
(polymeric film/sheet, metal foils, veneer, materials responsive to
heat, pressure, light and sound (e.g. to generate specific memory
and electrical signals, audio and video storing media etc.) and
combination of any two or more types etc., [0329] (iii)
Construction type (opaque, translucent, transparent, coloured,
smooth surface, textured, frictional surface, even edges, uneven
edges, parallel edges, non-parallel edges, variable width,
perforated, embossed, corrugated, either with or without chemical
formulation in powder, coated and infused forms, including
inclusion of nano carbon particles, adhesive bearing, stiff,
pliable, hard, soft, electricity conducting/insulating, heat
conducting/insulating, light conducting, dry, wet, sticky/tacky,
and combination of any two or more types etc., single layer type,
two or more layered type, with either regular or irregular
orientations of fibres/fibrils, sandwich type either with or
without layers comprising parallel, directionally oriented,
randomly oriented fibres, suitably connected different materials,
constructions and width combination types), and [0330] (iv)
Tape-width (that is either equal in both oblique directions, or
unequal in both oblique directions, or combination of these two
types, uniform, variable, and combination of any two or more types
etc.). Further, such tapes could be of single, two or more layered
types, and of suitable different materials, constructions and width
combination types indicated above.
Characteristic Technical Differences Between OFT Forming and
Relevant Conventional Processes
[0331] It will be obvious now to all the skilled practitioners of
textiles, particularly those associated with weaving and braiding
processes, that the OFT forming process described herein does not
technically correspond with the established principles of weaving
and braiding processes for reasons indicated earlier, and those
given in the following.
[0332] In comparison to the main aspects of the weaving process,
the OFT forming process differs in that: [0333] There are no
fundamental `shedding followed by weft inserting` operations
involved. [0334] There are no defined sets of input materials, like
warp and weft, and hence no such setting-up is performed. [0335]
There is no fixed relation between materials constituting the
fabric as happens with weaving process wherein warp (90.degree.)
and weft (0.degree.) have a permanent relationship. [0336] There is
no closed geometrical shape of tunnel or shed created in
fabric-width direction. [0337] There is no incremental insertion of
any weft-like material in any shed. [0338] There is no beating-up
required. [0339] There is no linear fabric-fell between the
longitudinal edges of OFT. [0340] There is no fabric width
expansion required, such as through use of temples. [0341] There is
no forward advancing of produced fabric for taking-up/winding in
the laid tape's width direction. [0342] There is no tensioning of
fabric involved in either its length and width directions or during
its take-up. [0343] There is no continuous running of any
constituent material in the fabric from start to finish, such as
warps and braiding yarns. [0344] There is no jointing of materials
necessary for producing any length of fabric.
[0345] In comparison to the main aspects of the flat braiding
process, the OFT forming process differs in that: [0346] There is
no simultaneous withdrawal of the two sets of input tapes. [0347]
There is no traversal of any tape spools. [0348] There are no
endless tracks/paths for traversing the spools. [0349] There is no
continuity of tape between fabric and tape supply spools during
production. [0350] There is no angular convergence of input tape
materials at the fabric-forming zone from their supply spools.
[0351] There is no alteration of distance between the planes of
spools and fabric formation to change the angle of tape's
incorporation. [0352] There is no linear fabric-fell between the
longitudinal edges of OFT. [0353] There are no pressing rollers
through which fabric passes to maintain its width and longitudinal
alignment. [0354] There is no continuous tension to be maintained
on the two input tapes. [0355] There is no continuous self-binding
of the fabric edges. [0356] There is no continuous running of tapes
constituting the fabric from start to finish. [0357] There is no
jointing of materials necessary for producing any length of fabric.
The other novel features of the OFT forming process are: [0358]
Fabric production involves laying of tapes with the Starting Phase
followed by the Continuing Phase. [0359] About one half of each
tape length that is laid forms the fabric while the remainder half
extends freely from the body of the fabric and lies exposed (at
full width of OFT body). [0360] The tapes within and extending from
fabric body remain in a tensionless condition between fabric's
opposite longitudinal edge sides. [0361] Free ends of desired tapes
of one orientation that extend from OFT's body are displaced to
receive newer tapes of other orientation to form OFT. [0362] Free
ends of desired tapes can be folded to create novel functional
OFTs. [0363] The body of OFT first grows longitudinally and
laterally until the full width is reached and thereafter it grows
only longitudinally. [0364] The body of produced fabric resembles
either a stretched hexagon or a trapezoid (OFT having one
longitudinal edge wholly sealed/closed) wherein the parallel
longitudinal edges extend more than the other remaining sides.
[0365] It can process any kind of material, from soft/delicate to
stiff/rigid types, without requiring any change. [0366] OFTs of
different constituent materials can be produced by simply changing
to corresponding material spools without stopping process for a new
production set up. [0367] OFT with either one continuously sealed
edge, or two discontinuously sealed edges, or continuously open
edges can be produced. [0368] OFT with either vertical or
horizontal or combination slits can be produced.
Other Usefulness of the OFT Forming Process
[0369] The OFT forming process described in the foregoing
incorporates the tape's fore end displacing arrangement (16) in a
mutually opposite configuration. They are located at the two
longitudinal sides of arrangement (11) whereby they occur parallel
to each other. However, they could be also arranged along two
adjoining sides of arrangement (11), or preferably incorporated in
bed of arrangement (11) itself, whereby they occur at an angle to
each other. Such an angle could be either obtuse (x.degree.) or
right (y.degree.) or acute (z.degree.) as shown in FIGS. 30a-30c,
which are the plan views. Through such repositioning and suitable
modifications of certain arrangements of the OFT forming process a
fabric of specific length and width comprising tapes at
corresponding angles can be produced directly.
[0370] Such a modified OFT forming device can be highly useful in,
for example, batch production of certain tapes of
difficult-to-process materials such as brittle and fragile (e.g.
boron, ceramic and metal coated fibres). These and other such fibre
materials, due to their brittleness/fragility, are difficult to
process by traditional routes into fabric materials. Furthermore,
these fibre materials, which are not mass produced compared with
other fibres such as carbon, glass, polymeric and metallic, are
usually not available in large lengths normally needed for
traditional textile processing. A modified OFT forming device can
be thus useful in producing fabrics of specific areas using such
special materials.
[0371] Purpose-made fabrics of materials such as boron, ceramic and
metal coated fibres are needed for certain applications and in
relatively very small quantities and application-specific
dimensions (length and width) making their production by
traditional processes impracticable, uneconomical and susceptible
to damages. Further, because materials such as boron, ceramic and
metal coated fibres are relatively highly expensive, their wastage
should be significantly minimized, if not altogether eliminated
during production.
[0372] In the circumstances, the principle of OFT forming process
can be advantageously employed. FIGS. 31a-c exemplify a modified
arrangement for producing a fabric of specific area wherein the
tape's fore end displacing arrangements (16a and 16b) are located
in adjoining manner making an acute angle between them (FIG. 31a).
As can be inferred from FIG. 31b, the first tapes from each
direction are laid on arrangement (11) by the tape laying
arrangement (15a and 15b) one by one, with the second (short) tape
resting over the first (long) one. Next, the fore end of the first
long tape is displaced by arrangement (16b) and a second short tape
laid adjacent and parallel to the previously laid first short tape
and partly under the first long tape. Subsequently, the fore end of
the first short tape is displaced by arrangement (16a) and a second
long tape laid adjacent and parallel to the previously laid first
long tape and partly under the first short tape to result in fabric
shown in FIG. 31b. Continuing with the process by displacing the
fore ends of laid tapes in preferred manner and laying long and
short tapes correspondingly, a specific area fabric material shown
in FIG. 31c is thus directly produced.
[0373] Because the area of the desired fabric material to be
produced is specific, there is no need to include the forward
advancing and winding arrangements. The structure of the produced
material can be held together, for example, by either a suitable
consolidation method described earlier or by fixing a suitable
adhesive tape at its four sides.
[0374] There is another possibility by which the described OFT
forming process could be exploited to advantage. Through this
possibility tapes can be laid from four directions of arrangement
(11) by using either one or two pairs of mutually oppositely
arranged arrangements for tape laying (15). Thus, when using one
pair of mutually opposite arrangements for tape laying (15a' and
15v'), it could be first positioned, for example, parallel to the
longitudinal sides of arrangement (11), as shown by the dashed
lines in FIG. 32a, and made to lay and pre-organize tapes
corresponding to the fabric's length direction on arrangement (11)
so that they occur between oppositely placed tape fore end
displacing arrangements (16a and 16b) as shown in FIG. 32a. Then,
this pair of arrangement for tape laying (15a' and 15b') could be
moved to the adjoining positions, shown as (15a and 15b) in FIG.
32a, to lay tapes from the end directions of arrangement (11). The
fore ends of the odd numbered pre-organized tapes facing the left
side tape laying arrangement (15a) and the fore ends of the even
numbered pre-organized tapes facing the right side tape laying
arrangement (15b) can be displaced simultaneously by arrangements
(16a and 16b). A pair of cross direction tape, one from each side,
can be then laid simultaneously into the created front-face
openings, one from each of the opposite end sides and up to the
middle of the pre-organized tapes as shown in FIG. 32b.
[0375] Next, the fore ends of the even numbered pre-organized tapes
facing the left side tape laying arrangement (15a) and the fore
ends of the odd numbered pre-organized tapes facing the right side
tape laying arrangement (15b) can be displaced simultaneously by
arrangements (16a and 16b). A pair of cross direction tapes, one
from each side, can be then laid simultaneously into the created
front-face openings one from each of the opposite sides and
adjacent and parallel to the previously laid tapes as shown in FIG.
32c.
[0376] The described process can be repeated wherein the stroke
length of tape laying arrangements (15a and 15b) is suitably
shortened/reduced after each tape laying until the preferred
specific area fabric material is produced as shown in FIG. 32d.
[0377] In another alternative possibility, an arrangement for tape
laying (15) could be permanently arranged at each of the four sides
of arrangement (11) and the specific area fabric produced on the
above-described lines. Here, the arrangement for tape laying does
not have to be moved to the adjoining position because one mutually
opposite pair of arrangement for tape laying functions to lay and
pre-organize tapes on arrangement (11) in one direction and the
other pair subsequently performs tape laying-in from the other
directions.
[0378] As can be inferred now, the production of the specific area
fabric materials with the constituent tapes making either acute or
right or obtuse angles between them can be accomplished in a
relatively short time as a pair of cross direction tapes is laid
simultaneously from opposite directions. Here again, there is no
need to incorporate the forward advancing and winding arrangements.
The structure of the obtained material can be held together, for
example, by fixing a suitable adhesive tape at its four sides.
[0379] There also exists the possibility of producing OFT by laying
a group of tapes of first direction and then displacing their fore
ends to lay the tapes of the second direction successively while
tapes of first directions of next group are laid simultaneously to
lend some continuity to process to produce OFT of larger specific
area.
[0380] The described OFT forming process could be also employed to
produce trellis structures wherein the tapes of each angular
direction are not laid adjacently close to each other, but
separated by a desired distance. By suitably consolidating the
overlapping areas of tapes of two directions a stable open OFT
structure can be produced directly.
[0381] Further, the openings of the trellis structure can receive
tapes/bands, of either fibrous or non-fibrous types, that are
oriented in either one or both representative diagonal directions
of any of the unit quadrilaterals that are created by overlapping
and intersecting of tapes to result in a fabric that has tapes
oriented in more than two directions. Such a structure constitutes
a multiaxial structure.
[0382] Following the described principle of the OFT process, a
person skilled in the art could modify and exploit it
advantageously further to produce fabrics comprising tapes in, for
example, three orientations, such as those indicated in FIGS. 32e
and 32f, which could be used, for example, in combination with
other fabrics to improve mechanical performance, draping and
shaping etc.
Modification Possibilities
[0383] The various arrangements described in the foregoing for
producing OFT are by way of examples to illustrate the working
principle. It will be obvious to the person skilled in the art that
one or more of the described arrangements can be modified to suit a
given situation for producing OFT. Given below are some examples to
illustrate how certain arrangements can be changed/modified.
[0384] (a) Arrangement for laying tapes: Instead of the linearly
reciprocating arrangement (15) shown in FIG. 13, an angularly
reciprocating arrangement can be used. In the plan view shown in
FIG. 33a, one end of arm (15a) is pivoted at point (P) such that
the arm (15a) can be made to swing in a horizontal plane by a
suitable driving arrangement (not shown). Arm (15a) is provided
with a pair of suitable fingers (15c) at both its end sides to grip
a tape (12a') drawn out from spool (12a). Thus, as shown in FIG.
33b, when arm (15a) is swung towards bed (11), the tape (12a') held
between the pair of fingers (15c) can be laid on bed (11) in the
preferred angular orientation relative to the length (or width)
direction of bed (11). In the next cycle of the process, arm (15b)
would receive tape from spool (12b) in its pair of fingers and
swung in a horizontal plane towards bed (11) to lay the held tape
in preferred angular orientation on bed (11).
[0385] Likewise, another alternative way would be to have arms that
can be swung in a vertical plane as shown in FIGS. 34a and 34b. A
pair of arms (15) (only one arm is shown in FIGS. 34a and 34b in a
side view), located above bed of arrangement (11), can be turned up
and down about pivot point (R), as shown in FIG. 34b, to lay the
tape held in its pair of fingers (15c) on bed of arrangement (11)
(which is provided with suitable recesses (not shown) to prevent
the pair of fingers (15c) hitting the bed of arrangement (11)).
Whereas in the indicated FIGS. 34a and 34b the arrangement of arm
(15) is shown to move 180.degree., it could be alternatively
arranged to move, for example 90.degree., in which case the axis of
spool (12) would be at right angle to bed of arrangement (11). This
type of arrangement can be advantageous to save floor space as the
spools (12) and the respective means for drawing out the tape (14a)
with gripper (14b) can be suitably positioned above bed (11).
[0386] In another arrangement for laying tapes, either the arm
(15a) could be supported in a fulcrum, whereby orientation of tapes
being laid by it can be changed by altering the relative angular
position of the arm, or the fingers (15c) supported on arm (15a)
can be relatively displaced, e.g. in different/opposite directions,
in relation to each other whereby orientation of the tapes being
laid by them can be changed. In any case, the resulting OFT fabric
will comprise tapes of at least one orientation direction
incorporated in relatively differing angles.
[0387] (b) Arrangement for displacing fore-ends of the laid tapes:
Instead of displacing the fore ends of the laid tapes by blocks
(16e)/clamps (16n) of arrangement (16m) linearly as shown in FIGS.
14b and 14f, an arm (16h) pivoted at point (S) can be used to
angularly displace fore ends of tapes. As shown in FIG. 35a, a
series of suitably spaced out clamps (16k) can be provided on arm
(16h) to individually hold the corresponding select fore ends of
the tapes occurring on bed (11). A series of suitably matching
spaced out clamps (16k') are fixed to bed (11). Arm (16h), pivoted
at point (S), can be swung in a vertical plane through a suitable
driving arrangement (not shown). Thus, as shown in FIG. 35b, when
arm (16h) bearing clamps (16k) is swung away from bed (11), the
fore ends of tapes (not shown) can be displaced in its thickness
direction and thereby create front-face opening with the tapes that
are held by clamps (16k') which remain stationary as they are fixed
to bed (11). As the clamp fixed nearer to the free end of swinging
arm (16h) will be displaced more than the clamp fixed nearer to the
pivoted end in reference to the top surface of arrangement (11),
there will be corresponding varying displacements of the fore ends
of the laid tapes. However, such varying displacements of fore ends
of tapes will not cause any production difficulties because only a
small front-face opening's clearance is sufficient for receiving
the thickness of the tape being laid.
[0388] Another alternative would be to hold the preferred fore ends
of laid tapes by a set of suitable clamping arrangements fixed to
an arm that can be swung in a horizontal plane over bed (11) to
bend/curve backwards the clamped tapes (i.e. towards OFT body's
direction). Such backward bending/curving of tapes of each oblique
direction can be done alternately up to the respective sides of the
V-shaped fabric-fell position.
[0389] Yet another alternative would be to have a pair of shafts
with plurality of clamps attached to each one of them. Each of
these shafts can thus individually control the fore ends of the
tapes occurring at each of the two longitudinal sides of
arrangement (11). Each of these shafts, placed over arrangement
(11), can be turned about its axis and thereby raise and lower the
clamped fore ends of the tapes.
[0390] Yet another alternative would be to have the fore end
displacing blocks/clamps arranged to traverse, for example on an
endless chain/belt so that they move up to a point, as OFT is
advance forward, remaining engaged with the fore ends of tapes
until necessary for displacing the fore ends and then release them
and traverse empty up to the opposite point to again engage with
the new fore ends of the newly laid tapes.
[0391] (c) Arrangement for supplying tapes from spools: Instead of
locating the spools (12a) and (12b) angularly at the sides of bed
(11) shown in FIGS. 6 and 8, they could be also positioned at an
end side of bed (11) as shown in FIG. 33a. By this arrangement the
two spools (12a) and (12b) can be had with their axes at right
angles to the longitudinal sides of bed (11). Thus, the tape drawn
out from them will be parallel to the corresponding longitudinal
sides of bed (11). This arrangement can be used, for example when
the swinging arms (15a and 15b), described in point (a) above in
this section and in reference to FIGS. 33a-b, is employed for
laying tapes on bed (11). Through this arrangement the width of the
OFT forming device can be made relatively smaller.
[0392] (d) Arrangement for supplying tapes from magazine: Instead
of drawing out tapes of preferred length from spools, pre-cut tapes
could be stored in a suitable magazine that makes available
unendingly the tapes to the arrangement for tape laying (15). Such
a magazine could be in the forms of, for example, either a rotary
drum that has clamps at its end sides to hold and present pre-cut
tapes to the tape laying arrangement (15), or a conveyor belt
carrying pre-cut tapes in a defined order from which the tapes
could be lifted by suitable means and presented to the tape laying
arrangement (15), or suitable receptacle in which tapes are
continuously stacked from one side and drawn out from the other
side for presentation to the tape laying arrangement (15) by
friction wheels etc. Through these and other arrangements of
unending pre-cut tape supply, the OFT manufacturing process can
technically produce OFT endlessly.
[0393] (e) Arrangement for advancing OFT forward: The movable and
stationary parts of arrangement (11), described earlier in
reference to FIGS. 5a and 5b, can be modified as shown in FIG. 36.
The body of OFT and the fore ends of tapes extending from the body
of OFT occur over the movable part M. They can be pressed by
correspondingly suitable pressing parts against movable part M for
advancing the OFT forward. The stationary part V matches with the
`V` shaped part of movable part M. The angle of `V` will preferably
correspond with the angle subtended by tapes. In this arrangement
the movable part M will be located closer to the winding side of
arrangement (11) and the stationary part V closer to the feeding
side. The movable and stationary parts, M and V respectively, can
be suitably supported to form the working bed for commonly
providing one plane/level surface for production and forward
advancement of OFT.
Process Alteration Possibilities
[0394] It will be immediately obvious now to a practitioner of the
art that the described OFT manufacturing process using tapes can be
modified in certain different ways to produce an OFT using not only
SFT and HDPT, but also other fibrous and non-fibrous materials such
as yarns, tows, `flat` yarns, strings, threads, twines etc. of
natural, synthetic, organic, inorganic, metallic, polymeric etc.
materials.
[0395] For example, instead of directly laying at once the
preferred whole length of tape from the front-face opening and
adjacently parallel to the previously laid tape as described
earlier, an OFT could be alternatively produced by drawing the
tapes, tows, `flat` yarns etc. from one side of the opening to the
opposite and then positioned closely parallel to the previously
laid tapes, tows, `flat` yarns etc.
[0396] Another way in which the described process can be altered is
when producing OFT fabrics of specific area. All the tapes of one
oblique direction could be initially laid adjacent to each other
and then tapes of the other direction could be laid successively by
carrying out preferred displacement of the fore ends of the
initially laid tapes from only one side of bed (11) and their
consolidation suitably performed.
[0397] Yet another way in which the process can be modified is
folding the extended ends of a tape at the corresponding
longitudinal edge side and joined (e.g. by thermal welding, gluing,
adhering etc.) to another tape that lies in the same oblique
orientation as the folded part of the tape. Such tape-to-tape
joining can be performed within the body of OFT (i.e. at a
preferred distance from the longitudinal edge). If such procedure
of joining of tape ends is performed continuously nearer to both
longitudinal edges, a fully closed longitudinal edge at both OFT
sides can be created. However, there will be a discontinuity of the
tapes in the OFT and also the OFT will be thicker at the tape
joints.
[0398] Yet another way in which the process can be modified is
inclusion of, for example, knitting needles at a suitable point
between the arrangements (18) and (19), i.e. arrangements for
advancing forward produced OFT material and for collecting produced
OFT material in a roll. This way, OFT material will be
loop-stitched by the knitting needles before being wound into a
roll. Through use of such knitting needles the OFT material could
be additionally loop-stitched in either its length or width, or
both these directions, before being wound into a roll. Such
loop-stitching could be done at, e.g interstices/openings created
between four adjacent tapes, i.e. the opening surrounded by four
tapes, whereby the yarns of the loop-stitch float at the fabric's
surfaces.
Usage
[0399] It will be obvious now to the people skilled in the art that
the novel OFTs described herein have unique constructional features
and hence can be used either independently or in combination with
other fabrics for realizing improved performance, material
properties and aesthetics of their products. Therefore, products
incorporating either one or more of the disclosed OFTs will exhibit
corresponding unique enhancements than possible to achieve
presently. For example, OFT can be used either individually or in
combination with other materials, such as by plying, to
obtain/impart strength in different directions, incorporating OFT
on top of a ply for aesthetic looks, wrapping or covering an object
for improved drape and performance etc.
[0400] Further, it will be also obvious now that the described
method and means for producing OFT is not limited to processing
only tapes. It could be suitably modified to process even certain
types of tows, rovings, `flat` yarns, `tape` yarns etc. OFTs
produced using such materials could be used in applications where
performance requirements are relatively lower.
[0401] The described method and means is equally capable of
producing OFTs using tapes of either similar or dissimilar
materials whereby OFTs of differing properties can be directly
manufactured.
[0402] Because OFT can be produced continuously by the described
method and means, it becomes possible to combine production of OFT
with, for example, a laminating or coating unit whereby the
produced OFT can be directly processed and converted into its
subsequent product. For example, an OFT can be coated with either
an adhesive formulation or film or pattern etc. on either one or
both faces continuously.
[0403] The described method and means is not limited to producing
flat OFTs. It can be also employed for producing an OFT that has a
contoured form such as that of `umbrella`. To produce a particular
contoured OFT, the bed of arrangement (11) can be correspondingly
shaped and different lengths of tapes can be drawn and laid on the
shaped-bed according to the described procedures to obtain directly
an OFT of the preferred curved form. Availability of OFTs in ready
forms will lend itself directly to quicker and cost-effective
production of high-performance items.
[0404] As can be inferred from the foregoing description, the
invention disclosed herein makes available several unique types of
OFT comprising tapes, including SFT and HDPT types, for numerous
applications and products. The various novel details can be altered
in many different ways without departing from its spirit. These
OFTs can be used either individually or in combination with other
materials, for improving performance, material properties/functions
and aesthetics. Therefore, the foregoing description only
illustrates the basic idea of the invention and it does not limit
the claims listed below.
* * * * *