U.S. patent number 3,810,280 [Application Number 05/115,606] was granted by the patent office on 1974-05-14 for method and apparatus for longitudinal compressive treatment of flexible material.
This patent grant is currently assigned to SAID Walton, by said Munchbach. Invention is credited to George E. Munchbach, Richard R. Walton.
United States Patent |
3,810,280 |
Walton , et al. |
May 14, 1974 |
METHOD AND APPARATUS FOR LONGITUDINAL COMPRESSIVE TREATMENT OF
FLEXIBLE MATERIAL
Abstract
Longitudinal compressive treatments for producing a wide variety
of effects in travelling lengths of sheet materials such as textile
fabrics, yarns, paper, film, foil and other webs by confining the
material against a drive surface by means of a confining surface
and driving the material into engagement with a retarder located
beyond the trailing edge of the confining surface and also in
spaced relation to the drive surface. The retarding surface is
provided by material which is essentially inextensible in the
machine direction and is provided with a multiplicity of portions
which grip and release the passing material. The confining surface
is at least in part spaced closer to the drive surface than is the
retarder. The forwardly driven material impinges against a column
of already compressed material under the trailing portion of the
confining surface and under the retarder. The drive surface propels
the continuously formed column from beneath the surfaces.
Inventors: |
Walton; Richard R. (Boston,
MA), Munchbach; George E. (Roslindale, MA) |
Assignee: |
SAID Walton, by said Munchbach
(N/A)
|
Family
ID: |
22362396 |
Appl.
No.: |
05/115,606 |
Filed: |
February 16, 1971 |
Current U.S.
Class: |
26/18.6;
264/282 |
Current CPC
Class: |
D06C
21/00 (20130101) |
Current International
Class: |
D06C
21/00 (20060101); D06c 021/00 () |
Field of
Search: |
;26/18.6 ;264/282 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Mackey; Robert R.
Attorney, Agent or Firm: Hulbert; William R.
Claims
What is claimed is:
1. In a machine capable of treating a traveling length of flexible
material, the combination, in the running condition of the machine,
comprising:
a drive member providing a movable drive surface for contacting one
side of the material,
means providing a confining surface and a retarding surface,
said last named two surfaces being arranged for contacting the
other side of the material and being in immediate succession and
opposite and spaced from said drive surface,
said drive surface and said confining surface together defining a
first passage for said material,
means for pressing the means defining said confining surface
tightly against said material at a point within but near the end of
said first passage so as to press said material in untreated
condition into driven engagement with said drive surface along a
line and propel it forwardly within said first passage in slipping
engagement with said confining surface,
said drive surface and said retarding surface defining together a
second passage, immediately following said first passage, into
which said material may enter from said first passage, said
retarding surface and said drive surface being so mutually spaced
at least at the entrance portion of said second passage that said
material will enter therein and pass therethrough essentially
without changing its path of travel and therein engage and be
retarded by said retarding surface,
said retarding surface having a multiplicity of projecting portions
operable successively to grip and release the material thereby to
locally retard the material as it passes through said second
passage to exert sufficient retarding force thereon to cause a
continuously replenished column of at least partially treated
material to build up,
said retarding surface being essentially non-extensible and
immobile in the direction of travel of the material,
said first passage having at least near its exit a dimension in the
direction of the thickness of the material which is no greater than
any similar significant dimension of said second passage,
whereby untreated material driven forward by said drive surface
beneath said confining member will continuously impinge upon said
column, the point of impingement comprising a treatment point, said
treatment point being located in a zone defined by the exit portion
of said first passage and the initial portion of said second
passage,
the mutual spacing of said drive and confining surfaces and that of
said drive and retarding surfaces and their frictional surface
characteristics being so related to the retarding characteristics
of said retarding surface that at said treatment point the
forwardly propelled material supported by said surfaces has
sufficient columnar strength to extrude said column of treated
material from the passage portions in which it is contained.
2. The machine of claim 1 including a resilient means supporting
said retarding surface in the direction of the thickness of the
material being treated.
3. The machine of claim 1 wherein said projecting portions comprise
projections formed of hard grit grains bonded to a non-extensible
backing sheet.
4. The machine of claim 1 wherein all portions of said retarding
surface which engage said material are spaced at least as far from
said drive surface as the portion of said retarding surface which
first effectively retards said material.
5. The machine of claim 1 wherein said drive surface comprises a
surface having ridges and grooves, the grooves having a component
in the direction of travel of the material, said grooves at said
treatment point providing spaces in which the material may
initially slide backward relative to said drive surface and
compress before leaving said grooves.
6. The machine of claim 1 wherein said drive surface is of
cylindrical form and said retarding surface commences less than 10
arc degrees from said treatment point.
7. The machine of claim 1 wherein the means defining said retarding
surface comprises a fabric.
8. The machine of claim 1 wherein the means providing said
retarding surface is a layer member, said drive surface is curved
and a bent metal member lies over said layer member positioning
said retarding surface with respect to said drive surface.
9. The machine of claim 8 wherein a backing layer of resilient
material lies over said retarder layer member and said bent metal
member comprises a sheet form metal keeper member over said backing
layer.
10. The machine of claim 1 wherein said retarding surface is
provided by a sheet form member and wherein said pressing means
lies above the region of the exit portion of said first passage,
said pressing means being adjustable relative to said sheet form
member backwardly and forwardly in the direction of travel of the
material so as to vary the proportion of force it applies upon said
confining surface and upon said retarding surface.
11. The machine of claim 1 wherein said confining surface is
provided by a primary member comprising a sheet of
deformation-resistant metal, the body thereof having a first
thickness and tapering to a reduced thickness at the exit of said
first passage, said retarding surface being provided by a retarder
member overlying said primary member at least in part.
12. The machine of claim 1 wherein said retarding surface is backed
by a layer of a material deformable in the direction of the
thickness of said flexible material being treated, extending over
said confining surface and deformed about the trailing edge of the
means defining said confining surface to position said retarding
surface with respect to said drive surface.
13. The machine of claim 12 including an outer sheet form member of
deformation resistant and force-transmitting material overlying
said layer, and a presser having a narrow pressing surface
engageable with said outer member in a position to transmit
pressing forces to a predetermined region beneath said confining
surface through the thickness of the intervening members, said
presser including mechanism for adjusting the position of
engagement of said presser with said outer member in the direction
of travel of said material.
14. The machine of claim 1 wherein there is provided an abrupt
enlargement in the direction of the thickness of the material of
the spacing between said retarding surface and said drive surface
immediately beyond the exit of said first passage to permit creping
of the overall sheet of the material, the machine being capable of
producing a time-varying densification of the material as the
resistance of the column of compressed material varies with the
varying stages of crepe formation.
15. The machine of claim 1 wherein said treatment point is located
in said first passage and said first passage beyond said treatment
point is enlarged in the direction of the thickness of the material
to permit creping of the overall sheet of the material, the machine
being thereby capable of producing a time-varying densification of
the material under said confining surface as the resistance of the
column of compressed material varies with the varying stages of
crepe formation.
16. The machine of claim 15 wherein there is provided an abrupt
enlargement in the direction of the thickness of the material of
the spacing between said retarding surface and said drive surface
immediately beyond the exit of said first passage to assist the
aforementioned time-varying densification of the material.
17. The machine of claim 15 wherein the surface defining the
enlarged portion of said first passage is continuous with said
confining surface.
18. The machine of claim 15 wherein, at least immediately preceding
said retarding surface, the spacing of the surfaces defining the
enlarged portion of said first passage is substantially greater
than the spacing of said confining surface from said drive surface
in the region immediately preceding said point of treatment,
enabling expansion of the material in the direction of its
thickness before reaching said retarding surface.
19. The machine of claim 15 wherein within said first passage the
spacing of said confining surface from said drive surface abruptly
increases and extends increased to said retarding surface.
20. The machine of claim 19 wherein said confining surface is
provided by more than one member in overlapped relation.
21. A method of treating a traveling length of flexible material
comprising:
providing a movable drive surface for contacting one side of the
material,
providing a confining surface and a retarding surface arranged for
contacting the other side of the material and being in immediate
succession and opposite and spaced from said drive surface, said
retarding surface having a multiplicity of projecting portions and
being essentially non-extensible and immobile in the direction of
material travel,
said drive surface and said confining surface together defining a
first passage for said material,
pressing said material in untreated condition into driven
engagement with said drive surface at a point in the exit portion
of said first passage to propel it forwardly within said first
passage in slipping engagement with said confining surface,
said drive surface and said retarding surface defining together a
second passage immediately following said first passage, said
retarding surface and said drive surface being so mutually spaced
at least at the entrance portion of said second passage that said
material will enter therein and pass therethrough essentially
without changing its path of travel,
in said second passage successively gripping and releasing said
material by means of said projecting portions thereby locally
retarding said material as it passes through said second passage to
cause a continuously replenished column of at least partially
treated material to build up,
said first passage having at least near its exit a dimension in the
direction of the thickness of the material which is no greater than
any similar significant dimension of said second passage,
whereby untreated material driven forward by said drive surface
beneath said confining member will continuously impinge upon said
column, the point of impingement comprising a treatment point, said
treatment point being located in a zone defined by the exit portion
of said first passage and the initial portion of said second
passage,
the mutual spacing of said drive and confining surfaces and that of
said drive and retarding surfaces and their frictional surface
characteristics being so related to the retarding characteristics
of said retarding surface that at said treatment point the
forwardly propelled material supported by said surfaces has
sufficient columnar strength to extrude said column of treated
material from the passage portions in which it is contained.
22. The method of claim 21 employed in treating textiles wherein
said retarding surface is arranged to nap the surface of the
material in the process of retarding it.
23. The method of claim 21 including slidably confining said
material substantially to its original thickness at said treatment
point and releasing said compressed material to expand its
thickness at a point spaced downstream of said treatment point.
24. The method of claim 21 including slidably confining said
material following said treatment point at a spacing greater than
the respective spacing at said point of treatment with a low
friction confining surface prior to exposing said material to said
retarding surface.
25. The method of claim 21 for bulking or softening a length of
fibrous material wherein said drive surface is provided with
material gripping projections and said material is slippably
confined against said drive surface and at least portions thereof
pressed into the intervals between said projections by said
confining surface, and including the step of maintaining the
relationship of the surfaces such that the drive surface slides
with respect to the material so that the projections tend to pull
fibers at one side of the material forwardly and out of said
intervals while the retarding surface has a relatively opposite
effect on fibers at the other side of the material.
Description
This invention relates to longitudinal treatment to produce desired
effects in thin materials such as woven, knitted and nonwoven
fabrics, yarns (which may be a warp of side-by-side yarns), papers,
films, foils and other webs and strands of deformable material. The
effects obtained include improvements in hand, softness, cover,
thickness, bulk, ability to drape, and extensibility.
At the present time, in spite of numerous attempts over many years
by workers in the field, so far as we are aware there are
essentially only two compressive treatment processes in commercial
use (leaving aside the age-old method of creping by scraping a web
from a drum by a doctor blade). These are the well-known
"Sanforizing" process involving longitudinally compressing the
material by the retractive action of thick moving belts which
straighten after passing around a roll, and the machines of our
earlier work all of which are still in use commercially, some more
extensively than others. See U.S. Pat. Nos. 2,765,513; 2,765,514,
3,260,778, 3,066,046, 2,761,490, 2,915,109 as well as others.
It has been the purpose of our work over many years to create a
machine and process that would go beyond experimentally
demonstrating desired effects to provide the key to practical
operation, with leeway to tolerate variables that occur. In this
way we have been successful, and a number of machines employing
different principles we have developed are in operation in mills
today.
We have recognized, however, that use of longitudinal treatments of
thin materials would greatly increase if there were a practical
machine and process which could be used on very wide webs, e.g., 10
feet wide and more; could operate at high speeds, e.g., for papers
and nonwovens at speeds of 300 feet per minute and higher; could
tolerate a wider range of temperatures, e.g., from ambient up to
200.degree. to 400.degree. F. without affecting the relationship of
the machine elements; would not involve rapid wear of parts so as
to operate for needed lengths of time without adjustment; would not
require high accuracy of alignment; as a standard machine design,
could be used on a wide variety of materials and treatments; would
increase the degree of treatment obtained; and which could be
simple and capable of operation by personnel of average skill.
It is an object of the present invention to provide a machine and
process meeting these needs and capable of producing uniform
effects while accommodating variables of the materials such as
density, thickness, uniformity, temperature-sensitivity, limpness
and prior history.
Other objects are to realize effects not heretofore realized on a
practical commercial basis and to make other effects easier to
obtain.
Specifically it is an object to provide an improved machine and
process that can uniformly alter a web by forces exerted
essentially only within its plane.
A very specific object of the invention is to provide a method and
means for improving the cover and bulk of textile materials and the
hand and texture of such materials as paper and nonwoven
products.
The invention concerns machines having opposed members for
contacting respective sides of the material, in the case of uniform
treatment of webs the members normally being uniform across the
width of the travelling web. According to the invention, on one
side of the material is located a drive member providing a movable
drive surface and on the other side there is a retarder member
spaced from the movable drive surface and having a retarding
surface to engage the exposed face of and retard the material while
the material is exposed to the drive surface. On the same side as
the retarder member is a primary material confining member
immediately preceding the retarder member and defining an inlet to
the space between the retarder member and the drive surface. The
primary member has a preferably smooth confining surface engaging
the exposed surface of the material to cause the material to be
driven forwardly by the driving surface and is at least in part
spaced closer to the driving surface than the retarding surface.
The retarding surface is provided with a multiplicity of portions
operable successively to grip and release the material thereby to
locally retard the material in its passage between the drive
surface and the retarding surface, and the retarding surface is
further characterized in being essentially non-extensible in the
direction of travel of the material.
In one form of the invention we provide a resilient means
supporting the retarder member in the direction of the thickness of
the material being treated.
In any of the forms of the invention the retarding portions may
comprise projections formed of hard grit grains bonded to a
non-extensible backing sheet or may be defined by hard metal.
The movable drive surface, according to the invention, may be the
surface of a rubber roll, or the knurled surface of a steel roll,
or the roughened surface of a travelling belt, or otherwise be
provided by a member having suitable frictional material engaging
characteristics.
When the machine is adapted to treat compressible materials the
drive member and primary member are arranged to drive the material
in essentially uncompressed condition to an initial treatment point
wherein compression thereof commences prior to its reaching the
retarding surface, the confining surface being further positioned
to define with the drive surface a passage beyond the initial
treatment point, the parts being positioned to slidably confine a
compressed column of material in the passage and direct the same
forward for exposure to the retarding surface.
For treatment of some materials all portions of the retarding
surface which engage the material are spaced at least as far from
the drive surface as the portion of the retarding surface which
first effectively retards the material. For treating compressible
materials, we may use a drive surface comprising a surface having
ridges and grooves, the grooves having a component in the direction
of travel of the material and providing at the initial treatment
point spaces in which the material may initially slide backward
relative to the drive surface and compress before leaving the
grooves.
In an embodiment for treating compressible materials, the drive
surface is of cylindrical form and the retarding surface commences
less than 10 arc degrees from the initial treatment point.
In many cases the member defining the retarding surface may
comprise a fabric or be a layer member, the drive surface being
curved and the machine having a bent metal member over the retarder
member positioning the retarding surface with respect to the
driving surface. In the latter case a backing layer of resilient
material may lie over the retarder layer member and in either case
the bent metal member may comprise a resilient or non-resilient
sheet form metal keeper member over the backing layer.
In other embodiments the retarder member is a sheet form member,
and a presser member is provided for pressing toward the drive
surface at a point above the region where the primary member ends,
the position of the presser member being adjustable backward or
forward relative thereto in the direction of travel of the material
so as to vary the proportion of force it applies upon the primary
member and upon the retarder member.
The primary member may comprise a sheet of deformation-resistant
metal, the body thereof having a first thickness and tapering or
stepped to a reduced thickness at its forward edge, the retarder
member overlying the primary member and extending downstream over
and beyond the trailing edge of the primary member.
In another form of the invention the retarding surface is backed by
a layer of a material deformable in the direction of the thickness
of the primary member and deformed about the trailing edge of the
primary member to position the retarding surface with respect to
the drive surface. In this case the machine may include an outer
sheet form member of deformation resistant and force-transmitting
material overlying the layer, and a presser having a pressing
surface engageable with the outer member positioned to transmit
pressing forces to a predetermined region beneath the confining
surface or beneath the retarding surface or beneath both such
surfaces through the thickness of the intervening members. The
presser includes mechanism for adjusting backwardly or forwardly
the position of engagement of the presser with the outer member in
the direction of travel of the material.
In machines for treating compressible materials wherein the
material is advanced to an initial treatment point and then through
a passage between the confining surface and the drive surface to
the retarding surface, the passage may be enlarged in the direction
of the thickness of the material to permit creping of the overall
sheet of the material, the machine being thereby capable of
producing a time-varying densification of the material under the
confining surface as the resistance of the column of compressed
material varies with the varying stages of crepe formation. In this
case the surface defining the enlarged portion of the passage may
be continuous with the confining surface or separately formed.
Likewise, at least immediately preceding the retarder member, the
spacing of the surface defining the enlarged portion of the passage
may be substantially greater than the spacing of the confining
surface from the drive surface in the region immediately preceding
the initial point of treatment, enabling expansion of the material
in the direction of its thickness before reaching the retarder. In
either case, the spacing of the confining surface from the drive
surface within the passage may abruptly increase and the increased
spacing extend all the way to the retarder member. Likewise, the
confining surface may be provided by more than one member in
overlapped relation. The time-varying densification of the material
may alternatively be made to occur by providing an abrupt
enlargement in the direction of the thickness of the material of
the spacing between the retarding surface and the drive surface
immediately downstream of the trailing edge of the confining
surface rather than in the aforementioned passage. For some effects
abrupt enlargements may be provided both in the passage to the
retarding surface and in the region under the retarding surfce.
To achieve other special effects the primary and retarder members
may be arranged at an angle to the path of travel of the material,
so that the trailing edge of the confining surface and the leading
portion of the retarding surface are angularly disposed to the path
of travel of the material. This arrangement may be employed both in
embodiments wherein the drive member is a roll, in which case the
edges define a helical segment upon the surface of the roll, and in
embodiments wherein the drive member is planar, as an endless belt.
When a belt is employed and the treatment occurs in a planar
section thereof, the adjustments of relative pressure between the
driving surface and the other surfaces may be made by mechanisms
pressing against the back side of the belt.
The invention also features the method of treating a travelling
length of flexible material comprising confining the material
against a moving drive surface by means of a confining surface so
that the material will be driven forward in essentially
uncompressed condition to a point of initial treatment and
providing a retarding surface on the same side of the material as
the confining surface but beyond its trailing edge and in spaced
relation to the drive surface. The retarding surface is essentially
non-extensible in the direction of travel of the material and has a
multiplicity of portions operable to successively grip and release
and thereby to locally retard the travelling material, while the
confining surface is at least in part spaced closer to the drive
surface than is said retarding surface. The forwardly driven
material while still uncompressed and beneath and engaged by said
confining surface is caused to impinge upon a column of already
compressed material at the initial treatment point and is then
propelled as a continuously formed column of compressed material
from beneath the confining and retarding surfaces.
For treating textiles, the retarding surface may be arranged to nap
the surface of the material in the process of retarding it.
The method of the invention is applicable to bulking or softening a
length of fibrous material by providing the driving surface with
material gripping projections. The material is slippably confined
against such driving surface and at least portions thereof pressed
into the intervals between the projections by the confining
surface; the relationship of the surfaces is maintained such that
the driving surface slides with respect to the material so that the
projections tend to pull fibers at one side of the material
forwardly and out of the intervals while the rough surface has a
relatively opposite effect on fibers at the other side of the
material.
To achieve certain effects with some materials the method of the
invention includes the step of slidably confining the material
substantially to its original thickness at a point of initial
treatment, and then releasing the compressed material to expand its
thickness at a point spaced beyond the point of initial treatment.
The method may include slidably confining the material following
the initial treatment point at a spacing greater than the
respective spacing at such point with a low friction confining
surface prior to exposing the material to the rough retarding
surface.
The invention also contemplates a method of treating a travelling
length of flexible material including confining the material
against a moving drive surface by means of a confining surface so
that the material will be driven forward by the drive surface,
providing a retarding surface which is essentially non-extensible
in the direction of travel of the material and located on the same
side of the material as the confining surface but beyond it
trailing edge and in spaced relation to said drive surface and
wherein the confining surface is at least in part spaced closer to
said drive surface than is said retarding surface. We cause the
forwardly driven material while still uncompressed and beneath and
engaged by the confining surface to impinge upon a column of
already compressed material at an initial treatment point beneath
the confining surface located upstream of the trailing edge and
propel the continuously formed column of compressed material from
beneath the surfaces.
In all forms of the invention, the material may be drawn out from
the end of the effective retarding surface at a rate greater than
the unassisted rate of extrusion from the machine, thereby
controlling the geometry of the passage and the degree of
treatment.
The foregoing and other objects, features and advantages of the
invention will be apparent from the following detailed description
of presently preferred embodiments thereof taken in conjunction
with the accompanying drawings wherein:
FIG. 1 is a diagrammatic highly magnified perspective view of a
preferred embodiment of the invention;
FIG. 2 is a diagrammatic view of higher magnification than FIG. 1
of the action of a projection of the retarding surface upon a fiber
or thread;
FIG. 3 is a diagrammatic, highly magnified vertical cross-section
of a preferred embodiment treating a knitted fabric and
FIG. 4 is a plan view of the fabric at various stages of treatment;
with FIGS. 3 and 4 having the points of treatment aligned;
FIG. 3a diagrammatically illustrates the directions of the forces
believed involved at the point of exit of the material from beneath
the retarder.
FIG. 5 is a highly magnified cross-section view of a preferred
embodiment of the invention including the members defining the
effective surfaces; FIG. 5a is a diagrammatic cross-section and
force diagram, illustrating forces acting upon the material in FIG.
5; FIG. 6 is a perspective view on a smaller scale of the effective
parts of the machine of FIG. 5;
FIGS. 7, 8, 9, and 10 are views similar to FIG. 5 of other
embodiments of the invention;
FIG. 11 is a view similar to FIG. 6 illustrating a retarding
assembly curved along the axial extent of a drive roll;
FIG. 12 may be regarded either as a plan development of the surface
of a drive roll, illustrating an embodiment similar to FIG. 11 or a
plan view of a machine employing a planar drive surface;
FIG. 13 is a diagrammatic view illustrating a double action effect
of the rough retarding surface in a softening or other such
treatment;
FIG. 14 is a diagrammatic view of an overall machine operable
according to the invention;
FIG. 15 is a view similar to FIG. 5 of another preferred
embodiment;
FIG. 16 is a cross-sectional view similar to FIG. 5 of another
preferred embodiment;
FIGS. 17, 17a, and 17b and FIGS. 18, 18a, and 18b are photographs
of materials treated according to the invention.
DETAILED DESCRIPTION
In FIG. 1 there is diagrammatically shown a driving surface 10
moving in the direction of arrow D, a confining surface 12 and a
retarding surface 14. It is assumed for this figure that surface 10
is provided by a moving member and both surfaces 12 and 14 are
provided by stationary members, none of which are shown. A web of
flexible material 16 to be treated is shown over the moving drive
surface 10 and under the confining and retarding surfaces 12 and
14, all of these surfaces having a uniform widthwise extent
corresponding to such width of the web as is to be treated
uniformly. The degree of magnification of this view will be
understood from the fact that the actual thickness of the material
is usually less than 0.015 inch and sometimes less than 0.005 inch.
Where a curved drive surface is employed, its radius of curvature
may be 2 to 6 inches. The degree of compression of the material at
its various stages is illustrated in a diagrammatic manner by the
sections which are intended to represent equal masses of
material.
The confining surface is adapted to slippably engage and press the
material against the drive surface to confine and drive it forward
in region A in longitudinally uncompressed condition to point O,
the initial point of treatment.
The machine is shown in running condition after the treatment has
stabilized. It will be appreciated that starting conditions may be
quite different. The retarding surface 14 lies along the driving
surface 10. The confining surface 12 is at least in part closer to
the driving surface than is the retarding surface 14. The retarding
surface 14 is rough relative to the confining surface 12 and
commenses at T, in this embodiment, within one inch (for textile
materials of the order of 0.005 inch to 0.015 inch thick within
about one-fourth inch) of the point O. (In other embodiments e.g.,
with stiff materials, the initial point of treatment may be nearly
coincident with the initial point of the effective retarding
surface).
At the point of treatment the longitudinally uncompressed material
is driven against a column of temporarily or permanently compressed
material, maintained in retarded state by the retarding action of
rough retarding surface 14. The material, as it leaves confinement
under confining surface 12, is freed to expand at least somewhat,
and is able to remain in its expanded condition throughout its
transit under retarding surface 14. Through the cooperation of the
roughness of that surface, with its relatively large spacing from
the drive surface, the retarding action can be maintained with
light downward pressure, without danger of causing refeed due to
excessive pressure of the web against the drive surface and without
undue wear of the retarding surface where wear would cause a
detrimental change in the treatment. Advantageously, from the
initial area of contact of the retarding surface with the material,
the effective retarding surface lies substantially parallel or
diverges relative to the drive surface, or at least does not
constrict the compressed material or require it to extrude through
a minimum passage.
The material illustrated in FIG. 1 is compressible, for instance it
could be knitted nylon tricot, or a host of other textile and
textile-like products. For many treatments of such materials the
transit of such materials at point T from under confining surface
12 to the retarder surface involves a latent tendency for the
material to curl upwardly and back, in response to the dragging
action of the confining surface, with resultant balling up and
jamming of the material. This tendency is defeated by the location
of the initial treatment at a point substantially in advance of the
transition to the retarding surface. As shown this is accomplished
with an extension of the confining surface through passage B, in
which is confined a column of longitudinally compressed material.
Thus the initial treatment of the material occurs within the
confines of the confining surface 12 where the material is
significantly densified, achieving greater columnar strength, and
also acquiring a tendency to expand. When this column reaches
transition point T at the end of the passage, its strength resists
the tendency to buckle, while its newly acquired expansion tendency
causes it to expand up against the regarding surface. Densification
at least to some degree within the passage B is a critical
requirement for numerous textiles which otherwise would not acquire
the necessary columnar strength before encountering the retarding
surface, while it is essentially non-critical, but in some cases
desirable to achieve certain effects, in the case of denser
materials already possessing the requisite columnar strength.
According to the present invention, the retarder is substantially
rougher than the roughness of the confining surface either before
or following the initial point of treatment, and in many instances
is preferably rougher than the drive surface, all measured in the
direction of travel of the machine.
Preferably for textiles and textile-like materials the roughness of
the retarding surface is in the range of 100 to 500 RMS (Root Mean
Square microinch) while for paper and paper-like products the
roughness is in the range of 200 to 800 RMS (the particular
roughness selected will vary with the relationship of all operating
surfaces and the nature of the material and its desired
treatment).
In comparison a preferred confining surface has a roughness under
20 RMS and a preferred drive surface for textiles comprising a roll
coated with tiny hard particles has a roughness less than 100 RMS
and for papers a roughness less than 130 RMS.
The length of the retarding surface is not critical over a
considerable range, being in general longer than the length of such
densification passage B as is used, or the distance between initial
treatment and initial effective retardation. In certain instances,
however, especially dealing with treatment of stiff materials and
employing roughnesses in the higher part of the range, the length
of the retarding surface in region C may be varied as a control for
the nature of the treatment obtained. In other instances, e.g., for
bulking textiles while minimizing shortening, it is also desired to
shorten the retarding surface and have it rougher than would be the
case where a substantial amount of longitudinal shortening is
affirmatively desired.
A wide variety of materials may be used to provide the retarder
projections or retarder surface roughness of the invention. The
retarding surface must be essentially non-extensible in the
direction of travel of the material in order to perform the proper
retarding effect and obtain uniformity and other advantages. For
many treatments it is essential that the retarder member also be
resiliently supported in the direction of the thickness of the
material, which helps to obtain a self-adjusting proper geometry.
The elements defining the projections or the roughness preferably
comprise hard, wear-resistant material. Preferably the material
forming the retarder surface has an elongation of less than 5
percent under tensions of 1,000 psi.
Materials, such as filled urethane, which have dense and stable
surfaces, exhibit the property of retarding by slip-stick action
and with long wearing properties.
It is advantageous to many treatments that the retarding surface
not only have its retarding effect, essential for the application
of longitudinal compression to the material, but that it also have
a napping effect, by which it is meant that the retarding surface
should momentarily interlock with the material locally to the
extent that the material is locally deformed. Referring to FIG. 2,
which is a fragmentary, diagrammatic, highly magnified
cross-sectional view, a projection P of the retarding surface 14
engages a thread or fiber F of the material undergoing treatment
and causes it to be separated and deformed from the yarn or bundle
Y to which it originally conformed. This effect, multiplied
thousands of times over each small area of the material,
advantageously contributes to the total treatment, for instance,
where it is desired to soften and improve the bulk or cover of
nylon knitted fabrics, or to give nonwoven fabrics softeness and a
better hand or drape.
Referring to FIGS. 3 and 4 a treatment of knitted nylon tricot, 40
.times. 40 denier, ten thousandths of an inch thick is illustrated.
In region A the longitudinally uncompressed fabric 16, illustrated
by a single chain or wale in the plan view of the face of the
fabric in FIG. 4, is driven forwardly to the point 0 of initial
treatment. Here it is confronted by a column of longitudinally
compressed or densified fabric while it is still confined by a
slippable confining surface in region B, in this case by the smooth
extension of the confining surface 12. Within the length of one
chain loop the fabric is converted from an elongated uniform chain,
in which the threads of the yarn are tightly bundled together
(region A) to a densifed condition where tht total density of
threads is increased while the individual fibers are buckled and
bent away from each other, although still retaining a recognizable
bundle outline (region B).
After the densified fabric 16a slides to the end of the confining
surface 12, it expands and is contacted by the rough retarding
surface 14 which has a napping characteristic. Here, in region C,
the longitudinally unyieldable roughness of the surface 14
penetrates into the body of the fabric to apply retarding forces
sufficient to retard the material and maintain the compressed
column in region B. The fabric continues to be driven forward in
region C, causing relative movement of the fabric under and past
the projections of the retarding surface, the movement under the
retarding projections being somewhat analogous to a ratcheting
movement. While this occurs, the retarding surface is also
effective to nap the fabric by dislodging individual threads from
their bundles and displaying them in a more random condition. The
treated fabric 16b has a barely if at all recognizable chain
structure, and the fabric (despite being originally formed of
straight nylon monofilament) has now a soft and textured
appearance.
In this example the untreatd fabric may have a thickness of for
instance 0.010 inch and the thickness of the treated fabric may
range from a slight increase up to 0.020 or 0.030 inch thickness
depending upon a number of factors within the control of the
operator.
Where it is desired mainly to bulk or thicken a textile, and not to
shorten it, advantageously the effective length of the retarding
surface 14 is kept short, i.e. one-eighth or one-sixteenth inch in
length, and the thickening occurs at the end of the confining
surface. The material is subjected to severe shearing forces at its
surfaces, causing actual rearward stretching or even localized
tearing of the top surface relative to the bottom surface. These
forces and shear distortion are illustrated acting on a section of
the material in FIG. 3a. When the material emeges from under such a
short extent of retarder it immediately "blooms" into a bulky form,
and has a distinct tendency to roll back in the direction of the
curved arrow shown in FIGS. 3 as a result of the oppositely acting
forces upon the face and back of the material, such forces and
their directions being indicated by the straight arrows.
In important instances it is required that the body of the fabric
not be visibly creped, it being desired to achieve treatment of the
threads and yarns individually. We have made this possible by the
densification of the fabric in region B in which the columnar
strength of the fabric is increased while the material is tightly
confined at its faces before it is exposed to the retarding
surface. With maintenance of this geometry the fabric is resistant
to bodily buckling as it is pushed through the successive
passages.
Referring to FIG. 5 a non-creping treatment with moderate bulking
is achievable with the construction shown. The drive surface 10 is
formed by a cylindrical roll 20, of a diameter on the order of 4
inches for treatment of narrow width materials, up to about 1 foot
width, and of increased diameter for wider webs. A sandwich of
stationary elements extends over the roll from a stationary support
not shown, at the left in FIG. 5. This sandwich includes a primary
member 22 whose lower surface defines the confining surface 12, a
nonresilient fabric member 24 having a coated grit facing (e.g.,
emery cloth) defining retarding surface 14, and a relatively thick
and unyielding keeper sheet 28. A spring steel keeper 26 is
inserted between keeper sheet 28 and the member 24 and extends
along the back of the latter. It has an unstressed curvature of a
radius less than the radius of the roll 20. The entire sandwich
extends as a cantilever over the roll and a presser member 30 is
adjustably positioned over the sandwich to press it against the
roll. As indicated by the arrows the presser member is adjustable
toward the roll surface to vary its pressure and it is adjustable
relative to the sandwich back and forth in the lengthwise direction
of the latter, to vary the relative point of application of
pressure. By the latter adjustment the proportion of downward force
applied to the confining surface to the downward force applied to
the retarder member beyond primary end 23 is variable in an action
we refer to as "teeter totter." The forces applied to the confining
surface are normally much greater than those applied to the
effective retarding member, and an adjustment one way or the other
of the presser member of .025 inch in the direction of the travel
of the material can have a desirable effect in controllably varying
the treatment. Such adjustment affects the degree to which the
emery member deforms about the end 23 of the primary. To some
extent it also shifts the point M of initial effective contact of
the emery with the material to be retarded.
In the embodiment of FIG. 5 the primary member 22 is formed from a
sheet of invar metal originally of 0.020 inch thickness, having a
slope ground to form a lower surface which causes the forward part
of the member to taper from the full thickness down to the end 23
of 0.004 inch over a distance of approximately one-quarter inch.
The retarding member 24 comprises emery cloth having an
uncompressed thickness of about 0.010 inch, and with the rough
surface of the emery facing against the top surface of the member
22. The emery extends beyond end 23 a distance e.g., of one-eighth
to three-eighths inch depending on the treatment and roughness of
the emery chosen. The keeper 26 is a length of spring steel of
0.005 inch thickness, and one-half inch width, bent in the
widthwise direction on a radius smaller than the radius of the
drive surface, and having its width arranged in the direction of
travel of the drive surface.
With application of pressure by the pressure member 28 as shown, in
the region of end 23 of the primary, the confining surface 12 is
pressed tightly toward the drive surface and effects forward drive
of the material 16, without longitudinal compression, up to an
initial point of treatment 0 under the confining surface 12. The
material is compressed against a column of longitudinally
compressed material which is confined by the forward extension of
the confining surface. As the material proceeds forward under this
tapering extension, the material is able to gradually expand while
being channeled forwardly without opportunity to buckle bodily upon
itself. When it reaches the end 23 of the primary member it has
stabilized as a lengthwise moving column of nearly the same height
as the height under the retarding surface. It therefore readily
bridges the small space at the end 23 of the primary member and
engages the retarding surface 14 at point M while moving nearly
parallel thereto. From point M the retarding surface itself resists
any tendency of the material to turn up, while at the same time the
retarding surface applies retarding forces in the manner described
previously.
The effect of the spring keeper member 26 is to maintain the
retarding surface in the approximate curvature of the drive surface
without at any place permitting the spacing under the retarding
surface to narrow down or constrict the column in the region of
effective retardation. In fact, with this embodiment, although
loading of the pressing edge of presser member 30 may be around 50
pounds per linear inch of presser edge widthwise of the machine,
one can easily raise the forward edge 27 of the spring keeper 26
with one finger, illustrating the relatively light downward forces
required while enabling the rough retarding surface to perform its
function. With this arrangement therefore the treated material
retains substantially its fully expanded thickness throughout the
length of the retarding surface.
The fore and aft adjustability of the relative position of the
presser member on the sandwich, indicated by arrow L in FIG. 5,
enables a control of the pressure applied by the retarding surface
14; through the force transmitting action of rigid keeper 28 and
spring keeper 26, increased pressure on the retarding surface has
the effect of increasing the over-all retarding force and the
degree of treatment.
In FIG. 5 as in the embodiment of FIG. 1, the point 0 of initial
treatment is close to the beginning of the retarding surface, for
the knitted tricot specifically mentioned this dimension being
one-eighth inch or less. In general for treatments where
substantial longitudinal compression is desired of densifiable
materials, the length of the retarding surface is substantially
longer, but not necessarily so where bulking or napping are the
effects to be achieved.
In certain instances, as with nylon tricot, the drive surface is
heated and transfers heat into the material in region A to prepare
it for treatment. After treatment it is desirable to continue
application of the heat to set the material in its new form.
Referring to FIG. 5a (which is adjacent FIG. 12 in the drawings)
principal forces which are apparently acting upon the material in
the embodiment of FIG. 5 are illustrated. Force F.sub.1 represents
the impact of the material against the column of compressed
material at the point of initial treatment. This force is generated
through the gripping of the material by the driving surface at
points preceding point 0, these forces being transmitted through
the uncompressed material. F.sub.2 represents the further driving
force attributable to the portion of the driving surface in the
region of point 0. It represents the fact that the gripping effect
of the drive surface upon the material must be overcome by the
retarded column of compressed material in order for compressive
treatment to commence and for the drive surface of the roll to slip
freely forward under the compressed column. F.sub.2 has a slight
upward component representing the upward wedging effect of the
gripping projections of the roll surface as they slide forward.
F.sub.3 represents the confining forces exerted by the confining
surface 12. The compressed column of material has a tendency to
expand in all directions, an effect which can be considerable when
the material being treated has a resilient consistency. F.sub.3 has
a slight rearward component representing the drag effect. The
smoothness of the confining surface (e.g., roughness less than 20
RMS) and its low coefficient of friction, assisted e.g., by a
teflon impregnation, help to keep this drag effect small.
Throughout the exposure of the material to the moving drive surface
10 there is a slight tendency for that surface to pull the material
forward, represented by force F.sub.4. This pull is a function of
the pressure with which the material presses against the drive
surface. As indicated above, e.g., in the discussion of keeper 26,
this pressure can be very light, keeping force F.sub.4 small.
When the compressed column moves from under end 23 of the confining
surface, it expands and immediately engages the rough retarding
surface 14, whereupon a significant retarding force is applied
along that surface. The localized retarding forces at points along
the retarding surface are represented by F.sub.5 while the
cumulative effect of the retarding surface downstream beyond that
shown is represented by F.sub.6.
In this connection it is to be noted that because the retarding
surface is essentially non-extensible in the machine direction, its
projections remain stationary under the force exerted by the moving
material and prevent non-uniform retarding patterns or bunching to
occur; this feature also causes the force applied to the
projections to produce an upward turning couple, i.e., a forward
force on the projection produced by the material, and an equal
reaction force acting rearward along the thickness of the emery,
this tendency being yieldingly resisted by a vertically resilient
support. Note that this turning tendency varies during treatment
and produces a self-adjusting effect to provide uniform
treatment.
It is found that with the shortness of the treatment zone as
mentioned (region B, FIG. 1), the forces can act together to
dramatically alter the structure of the material, the degree of
treatment varying with the selection and relationship of the
various elements. With curved drive surfaces it is to be noted that
the limited arcuate extent of the region B assures that the major
forces applied by the drive surface preceding or at the point of
initial treatment 0 are substantially aligned with the passage
under the rough retarding surface, and thus can more readily cause
the material to move therethrough without buckling.
In increasing order of the degree of treatment the following
retarding surfaces have been employed in the arrangement of FIGS. 5
and 5a for treatment of knitted and other textiles, all of these
retarding members being emery cloth sold by Behr Manning of Troy,
New York, under the tradename Metalite, having a thickness on the
order of 0.010 inch.
description RMS new RMS in use crocus cloth (polishing 100-130
90-110 cloth with fine abrasive grit) 500 J 200-240 170-200 400 J
270-300 230-270 320 J 300-500 230-280
these roughness readings were made with a profilimeter on the
abrasive side of these materials, the side which is ordinarily
disposed against the material. Durable fabric of essentially
inelastic qualities may itself be used as a retarding surface; one
such demonstration employed a tightly woven mesh fabric having a
profilimeter reading of 450-650 new, 400-450 used. Metal screening
and other materials having the requisite gripping characteristics
may also be used.
Another point worthy of mention is the discovery that used emery
surfaces which appear worn-out in fact have a very desirable effect
and are actually preferred. When new emery surface is employed it
is preferable to pre-treat the retarding surface by rubbing toilet
tissue or other fibrous material on the emery, to leave a deposit
of tiny fibers. We are not fully sure why this has good results,
but it is believed that the fibers duplicate the condition, for new
emery, of the emery in use, where certain free fibers serve
somewhat as a lubricant over the roughest portions of the surface.
The "lubricating" effect of retained fibers is demonstrated
especially in the small region where the emery bends about the end
of the primary member. It is usually preferred to have the emery
surface lie parallel to the drive surface or to slightly diverge
all along its effective length. But in order for the emery to reach
its initial point of effectiveness at the desired height, it
usually must be bent down over the end of the primary member. The
latter in some cases is as thick as 0.005 to 0.010 inch or more.
Undue retarding is avoided at this initial sloped portion of emery
apparently because of an increase of retained loose fibers that
accumulate on the sloped surface.
For many treatments the roll surface should not be as rough as the
emery surface; the above embodiment employs a drive surface having
a roughness ranging between 80 and 90 RMS.
Referring to FIG. 6, there are shown the working components of a
machine in accordance with the invention. The roll is steel and its
gripping characteristics is achieved by a plasma coating of
tungsten carbide; it is driven in the direction of the arrow,
receiving material to be treated on the left side and delivering
treated material to the right. The sandwich includes a support
plate 31 and the aforementioned primary member 22, retarding member
24 (non-resilient, high tensile strength emery cloth), upper keeper
member 28 and spring keeper 26. These are all clamped together and
mounted in a support (not shown). In this embodiment the presser
member 30, although adjustable vertically for adjustment of
pressure, is not shown adjustable horizontally. The relative
horizontal adjustment between presser and the sandwich is achieved
by movement of the sandwich support in the direction of the arrows,
to achieve the teeter totter adjustment as desired.
The limited arcuate extent .alpha. (less than 10.degree.) of the
spacing between the initial point of treatment of the material and
the commencement of the effective retarding surface enables the
substantial alignment of driving and retarding vectors (see FIG.
5a) which is believed to contribute significantly to the nature and
controllability of the treatment.
Referring now to FIG. 7, using this embodiment the treated material
can be confined substantially to its original untreated thickness.
In this case the confining surface is defined by the primary member
22a which is extremely thin, e.g., 0.002 inch thickness (which may
be supported by the retarding member 24a lying directly above it).
The retarding member comprises a fabric with a suitable
wear-resistant surface 14a. The other elements may be the same as
in the preceding embodiment. The incoming material is pressed
against the drive surface by the primary confining surface 12a,
compressing the material in the direction of its thickness but not
in the longitudinal direction. As it proceeds, it is confronted by
the column of longitudinally compressed material and treatment
occurs, with probable lifting of the primary to a slight extent,
but not allowing the expansion afforded by the tapered primary of
FIG. 5. The surface of the retarding member in this case is
smoother than in the preceding case, so that not so much
longitudinal densification of the column occurs. Where the
treatment is employed mainly for physical working or softening of
the material, even this amount of compression may be pulled out
further along in its movement, so that the resultant product need
not be shortened much from its incoming state.
While the invention of course is not limited to any one material,
it is helpful to an understanding of the invention to pursue the
same material through a number of treatments to show some of the
effects that can be obtained. Those given so far have referred to
nylon tricot. An embodiment similar to FIG. 7, with a primary
member 0.004 inch thick, a rougher emery, e.g., metalite 280J of
short extent beyond the primary, e.g., one-eighth inch, can be used
to bulk the same nylon tricot from 0.010 inch to 0.015 inch
thickness with shortening of less than 15 percent and good softness
and cover on both sides, with temperatures around 250.degree.F or
higher.
Using the embodiment of FIG. 8 an extreme degree of bulking of the
fabric is possible. A nylon tricot material of 0.010 inch thickness
was bulked to a thickness of 0.026 inch, with a fleecy felt like
consistency; when the material was stretched to remove some of its
longitudinal compression it retained its bulky character to a
significant degree.
In FIG. 8 a roll provides the drive surface 10 which is defined by
a series of side-by-side knurls and grooves extending at an angle
of 50.degree. to the axis of the roll. The knurl grooves have a
depth on the order of 0.005 inch.
The primary member 22b comprises invar of .012 inch thickness, the
retarding member 24b a sheet of emery designated 320J with a
surface roughness of 280 RMS, a flexible keeper member 26b in the
form of a medium durometer silicone rubber of one-eighth inch
thickness and a Swedish blue steel upper keeper member 28 engaged
by the presser member 30 as described above.
Employing the same nylon tricot material as used for the preceding
examples, the material is pressed against the drive surface in
region A, in this instance the material being pressed into the
grooves so that the ridges are formed in the material which the
roll pushes forward. As the material reaches the initial point of
treatment 0) it still fills the knurls, and the first action is for
the roll to slip forward with the material sliding back relative to
the knurl, while at the same time being driven strongly forward.
Soon the action of the following knurl projection and the
confronted column of densified material wedges the material out of
the knurl, and up against the extension of the confining surface.
As it proceeds forward the faster advancing knurl surface provides
momentary expansion spaces so that the net space accommodating the
compressed column exceeds the clearance space between the confining
surface and the imaginary cylindrical surface projected through the
outer tips of the knurl projections. Thus even under the primary
member there is produced a column of considerable thickness, which
has inherent resistance to buckling. The end 25a of the primary
member is cut at a 45.degree. angle sloping upwardly forwardly, and
this helps to ease the expanding material out from under the
confining surface 12 and to direct it forward into contact with the
retarding surface. Also it is suspected that the nature of the
compressive action achieved by the knurls at point 0, which is at
an angle across the face of the material, results in ridges of high
compression in the material itself, which arrive progressively at
the sudden opening from under the primary. Thus a portion of a
given ridge which has already progressed under the rough retarding
surface and confining portion of the given ridge still lying under
the confing surface, restrain that portion of the ridge which is
emerging at 25a, and prevent backward curling or other movements
that might promote buckling and unwanted crepe in the body of the
material as a whole.
In this embodiment, as in the foregoing, the drag exerted by the
material on the retarding surface and the fact that the substance
of the retarding member is dimensionally stable, wear-resistant and
therefore not detrimentally extensible under working loads, keeps
the retarding surface in position without any unpredictable
narrowing of the passage or other actions which would make the
process difficult to maintain under mill conditions.
Rubber behind this emery cloth or other dimensionally stable sheet
on the other hand has virtue in helping to conform the emery to the
curvature of the drive roll, along the length of the retarding
passage. It also helps conform the emery about the edge 25a of the
primary member, decreasing the size of any open space in that
region-- and helping in that regard to combat the problem of
unwanted creping and to position the beginning of the effective
length of the retarder surface. In cases where the desired effect
is to bulk a web, the keeper member 28 may be very thin, and allow
the retarder assembly to flex upwardly. In such instances the
portion of the retarding surface nearest the confining surface
accomplishes most of the retarding, outward portions serving to
buffer the column to ensure uniform treatment across the web
width.
FIG. 9 is an embodiment in which essentially two steps of treatment
can be accomplished before the material is exposed to the retarding
surface. Where, as is the case with many knitted and other
materials, the material is not dense, i.e., is porous or loose,
densification of the material in the longitudinal direction takes
place at an initial point of treatment preceding the end 23a of the
primary member. A column of longitudinally compressed but not
substantially thickened material extends from 0 to primary end 23a,
under the extension of the primary surface. Following edge 23a a
second extension 25 or roof of low friction slippable material,
invar or teflon impregnated blue steel, extends forward. The column
of material, despite its tendency to curl upward, is guided forward
instead by oblique contact with this low friction surface;
meanwhile the natural tendency for the material to expand in
thickness causes the column to fill the volume under the roof. This
thickened column (now having more resistance to bend bodily because
of increased thickness) is then projected forward under edge 27 of
the roof and into exposure with the retarding surface, where it
further expands and is napped as described above. This device has
also demonstrated the capability of bulking nylon tricot, and is
particularly effective when used with the knurled roll referred to
in FIG. 8. The length of the keeper 28 may be as long as the emery
and stiff where high compaction is required; where high bulking
with lower compaction is desired, the shortened keeper shown, or a
thinner keeper is employed, thus shortening the effective length of
the retarding surface.
The length of the roof for treating nylon tricot is preferably in
the range of about 0.030 to 0.080 inches length; with a drive roll
of 4 inch diameter, 0.040 inch roof length is preferred, with a
roll of 12 inch diameter, 0.060 inch roof length is preferred.
In certain instances it is advantageous to adjust the presser 30
forward, e.g., to the dotted line position. In this case the
extension 25 is bent downward and causes more densification to
occur. In a similar arrangement, but with a much longer extension
25, the extension itself may serve as the primary and define the
point of initial treatment, and by this construction a simple
throw-away package of emery and extension may be removably inserted
between relatively thick permanent members.
In other instances from those mentioned above, it is desired to
impart a crepe or surface treatment to the body of the material as
a whole. Referring to FIG. 10, a creping action is illustrated. For
use with hard and stiff materials such as a non-woven fabric or
water laid or laminated type, a drive surface 10 of a roughness of
the order of 110 to 130 microinch RMS is employed, formed by
tungsten carbide particles bonded to a steel roll surface. For
non-wovens, ranging from 0.005 to 0.015 inch thickness a primary
member 22c of 0.010 inch thickness is employed. Also for such
hard-surfaced materials an emery retarding surface 14c of grit size
on the order of 320 mesh or less is employed. Over the emery a
keeper 26c of Swedish blue steel plate of 0.010 inch thickness is
employed, and for use with wide sheets a drive roll of 12 inch
diameter is employed.
The nonwoven may be dense enough itself to be driven forward for
the treatment desired at point 0, but in other instances as with
other textiles, densification may occur under the primary surface
in the manner described in the foregoing embodiments, with the
initial treatment at point 0'. When the web is driven forward from
under the primary it enters a substantially widened space and due
to forces acting previously upon it, as well as the resistance of
the retarded column, it tends to turn up.
In doing so it engages the projections of the retarding surface
moving at a substantial angle against the plane of the emery. The
projections, together with the confronted column of retarded
material, are effective to momentarialy stop this material.
Meanwhile, more material is forced forward from under the primary
surface. Since the preceding material has curled to the upper part
of the space, the subsequent material folds forward beneath it.
With still more material being forced into the spaced by the
continuing action of the drive surface on the densified sheet, the
folded material is pushed forward and the cycle commences again.
The result of this action is a series of folds in which the upper
portions 40 of the folds slant backwardly and the lower portions 42
slant forwardly, due to the action of the projections of the
retarding surface.
As in the preceding embodiments the emery surface does not converge
or form a restriction along its effective length, the projections
of the emery being sufficient to retard while the emery surface is
maintained throughout at a distance from the drive surface greater
than the spacing of the confining surface from the drive
surface.
When treating non-dense materials to a creping or other treatment
which creates either small, localized folds or larger folds, the
intermittent action as pictured in FIG. 10 affects the degree of
densification occurring under the confining surface. When the
bottom leg of a crepe fold lies at the end of the primary, as
shown, a first resistance force is transmitted back to the initial
treatment point 0. When the material collapses upwardly to form the
next crepe, the resistance force suddenly decreases. This has its
effect in the densification occurring under the confining surface,
the degree of densification varying along the length (i.e., with
time) with the varying stages of the creping action. This can have
desirable effects both for decorative appearance and physical
qualities of the material.
Referring again to FIG. 10, the member 24b is adjustable in the
machine direction, as indicated by the arrow, thereby providing a
means of controlling the degree of densification and longitudinal
compression of the crepe column, e.g., in cases of using coarse
emeries, by adjustment of the amount of emery extending forwardly
beyond the edge of the primary member.
The action of the emery, even upon paper and non-woven articles,
includes a napping effect in which fibers of the web along the
upper surface of the web are individually retarded, and rearranged,
imparting softness and change of appearance to the web. The action
of the emery, along with the other surfaces, also is to carry out
the treatment in an accurately maintained geometry, with the
desired, but no more than desired, thickening of the web and
coarseness of the folds.
For use on non-woven materials, the following emery surfaces, for
instance are useful, manufactured by 3M Corporation under the trade
name TriMite.
Grade Roughness 180 C 500-600 RMS 320 TE6 200-350 RMS
the material-contacting surface 12c of the primary member 22c, in
comparison, had a roughness of less than 20 RMS.
For treating material at an angle to its direction of travel the
embodiment of either FIGS. 11 or 12 may be employed. They differ in
showing different preferred drive surfaces. In each instance a
primary member 60 defining the confining surface has a forward edge
62 set at an angle to the axis of the roll and also curved or
flexed to conform to the roll; that is to say at an angle to the
projection of the axis on to the roll surface. In FIG. 11 the edge
is in a plane set at a constant angle, thus describing a helical
segment upon the roll surface. The retarding member 64 projects
beyond that edge and terminates in a further edge 66 also set at an
angle to the axis, lying parallel to primary edge 62. A suitable
keeper means 68 lies over the retarder member and a presser member
70 also set at the same angle presses the assembly against the
drive roll. Treatment with this machine has a widthwise as well as
length-wise effect, and successive passes through two such
machines, but with the machines having the angle set in opposite
directions, can impart two-way stretch and other two-way qualities
to the material being treated.
Referring to FIG. 13 and 14, there is shown diagrammatically a
system in which the longitudinal treatment has substantially no
effect upon the length of the treated product. As in the preceding
embodiments, such as FIG. 10, the material 16 is driven forward
against a column of compressed material 16a and is thereby
compressed either by densification, folding or a combined effect,
and the rough surface 14d of the retarder 24d is effective to
uniformly retard the column of compressed material even when the
material has such hard surfaces as do paper and paper-like
products. Thus the length of the column of compressed material may
represent an uncompressed length of twice the extent. In this
embodiment however a drive device 80 (FIG. 14) coordinately drives
the drive surface 10 at e.g., only 2 percent faster surface speed
than take-up roll 90. The effect of the take-up roll, after running
conditions are established, is to pull upon the material and take
up e.g., 98 percent as much length as has been fed to the
machine.
The rough retarding surface 14d now has a further function in
providing resistance to the pulling tendency of the take-up roll
90, joining with it to form a stretching means in which material,
when released from the column, is stretched e.g., to nearly twice
its compressed length, as indicated by numeral 16b.
Referring to FIG. 13, in magnified view, it is thus seen that the
effect of the rough retarder surface is to upply a compressional
resistance R and stretching tension S at opposite ends of the
retarding passage. In between, the projections of the rough
retarding surface momentarily lock or ratchet upon the moving
column and retain it in position so that both compression and
stretching can proceed in a uniform manner.
As an example a stiff paper-like non-woven fabric of 0.015 inch
thickness and a "boardy" feel was processed. This non-woven
consisted of a lamination of five layers, a layer of scrim threads,
sandwiched between two non-woven wet laid sheets and two external
sheets of tissue paper. The resultant product after treatment was
very soft and had good draping qualities, with numerous lines
representing the tiny crepe that had been applied and then
removed.
In FIG. 15 there is shown another arrangement for softening
non-woven fabrics. The primary member 100 is a 0.010 inch thickness
Teflon impregnated Swedish blue steel sheet, the retarding member
110 is a dimensionally stable sheet of 180J emery, slightly greater
than 0.010 inch thick, and a further blue steel member 120 of 0.008
inch thickness lies above the emery and extends beyond the trailing
edge thereof. Above this member is a resilient member 130 comprised
of one-eighth inch thickness natural rubber and above it lies a
final 0.010 inch thickness blue steel keeper plate 132. The presser
member 134 comprises three 0.050 inch thickness plates,
cantilevered to form a presser edge 125, and a 0.010 inch auxiliary
presser 136 extends forwardly therefrom, helping to conform the
assembly to the curvature of the drive surface 10. The latter is
provided by a steel roll of 12 inch diameter having a rough surface
formed by tungsten carbide particles bonded thereto, with a
roughness of 130 RMS. The edge 125 of the presser member presses
upon the keeper 132 at a point one thirty-second inch forward of
the top center, Tc, of the roll, the assembly projecting forward
from a support to be tangent to the roll at Tc in the unstressed
condition as shown in FIG. 14. The end of the primary 100 is
approximately aligned with the edge 125 of the presser member, the
emery extending forward thereof a distance of approximately
five-sixteenths inch. To adjust the relative position of the
presser member adjustment screws 140 (FIG. 14) can move the
assembly, including the primary, forward and back relative to the
presser member.
The extension 120a of the metal member beyond the emery can serve
to press the web against the drive surface to refeed the web and
pull out some of the compression in the web where this is desired.
It has the virtue of effecting this tension while resisting the
tendency for the web to narrow or "neck in" during pulling.
Referring back to FIG. 14 again, examples of coordinate treatments
are shown. The supply roll 160 feeds the web to corrugating roll
pair 170 which forms fine longitudinal corrugations. Examples of
other pretreatments are the radiant heater 172, the steam heated or
chilled roll 174 and the steam, water or chemical spray 176.
Following the treatment, a dust collector and treater 178 and a
heat set or chill roll 180 are shown.
Referring to FIG. 16 there is shown a backing member 200 of special
properties. Under the first application of compression of the
presser member 202 it permanently deforms into a thin rigid load
transferring member, which helps in assuring positive drive of the
material. At the end of the primary member 100 it is deformed and
conforms the emery 206 about the trailing edge thereof. However,
its extension beyond the trailing primary edge, is under much less
compression and behaves as a resilient member, giving the preferred
support to the retarder surface. One such suitable material is a
leather substitute sold by Dupont under the name "Corfam."
FIG. 17 is a photograph of considerable magnification of that side
of a treated material which engaged the drive surface. The point of
initial treatment O, under the confining surface is spaced a short
distance from point M, the point of initial contact with the
effective retarding surface (slightly beyond the end of the primary
member indicated by T in e.g., FIG. 1). FIGS. 17a and 17b are views
of greater magnification respectively of the back and face of the
same treated fabric.
FIGS. 18, 18a, and 18b similarly show the same kind of material
which has been treated by being creped.
These examples were prepared by stopping the machine in the midst
of treating, and leaving the presser member and the other members
in place under full operating load. The drive surface heat over
this duration fused the fibers in the state in which they were
found, thus preserving the relationship as defined by the
machine.
In other embodiments numerous other specific details may be
employed. For example, as a durable retarding surface a thin metal
mesh or metal or other hard fiber weave may be employed in which
the crossing elements form projections; or a finely perforated
dimpled or scratched metal plate may be employed with the surface
discontinuities at the openings forming surface roughness; or a
rough-surfaced metal plate may be employed having, for instance,
tiny tungsten carbide particles adhered thereto through the plasma
coating technique or more preferably, the gun shot technique. Other
durable materials may be employed, such as hard and durable
fabrics.
The particular roughness to be employed will be determined to a
large degree by the particular product and process in question;
thus for knitted fabric roughnesses around 100 to 200 RMS are
appropriate, and for hard kraft papers roughnesses of 600 RMS or
above are appropriate; but other roughnesses will be appropriate
for other materials and other treatments.
In preferred forms the retarder defines a general or closed
retarding surface, but in some instances a multiplicity of brush or
needle-like projections may be employed as the retarder. In one
such instance a multiplicity of retractable needles, or a card
clothing arrangement of projections can be employed to provide a
first degree of retardation at start up of a process, with
predetermined retraction to achieve a lesser degree of retardation
during the running conditions. (In another arrangement card
clothing projections can also be arranged to define the confining
surface.)
Another control of retardation lies in the take-up device, it being
possible by proper rate of takeup to remove the treated material to
control both the final shortening of the product and to some degree
the geometry of the retarding surface where it is resiliently
supported in the direction of the thickness of the material being
treated.
Other factors involved in retardation are the amount of pressure
applied against the retarding surface and the length of the
effective retarding surface. Actually, use of very light pressure
on the retarding surface is operable, it being sufficient to hold
the retarding surface to approximate the form of the driving
surface or even to diverge therefrom, following the initial point
of contact of the retarding surface with the material. It is one of
the advantages of the invention that the column of compressed
material need not be necked down or forced to extrude through a
minimum passage--where high wear can occur--the generally parallel
but rough surface being sufficient to maintain the compressed
column in position. In situations where this is critical, it is
possible to control the degree of treatment by change in the
roughness character of the retarding surface or in the lengthening
or shortening of the effective exposed length by a suitable
adjustment device or by controlled rate take-up of the
material.
The characteristics of the drive surface are also to be determined
in the light of the particular process and result desired. It is
possible to drive textiles with less drive surface roughness than
is required for hard-surfaced materials such as kraft papers and
plastic or metal films and foils. Other considerations may concern
the interaction of the drive surface and the particular material
employed, and thus in some instances a smooth roll may have an
adequate driving characteristic for a particular treatment, for
example in the case where the material or the drive surface has or
is given adhesive qualities. The roll in such case may be very
smooth, but in most cases it is desired to be rough or prickly, and
in certain instances such as described above, grooves in the drive
surface can contribute desirably. A significant advantage of the
invention lies in its elimination of a blade or doctor to retard
the travelling web. The use of such a blade is a limiting factor in
choosing the surface characteristics of a drive roll. If the roll
is too rough, it will produce rapid mutual wear of both roll and
blade; if too soft, e.g., rubber, it will cause the blade to dig
into the roll surface. According to the present invention this
limitation disappears and any desired driving surface
characteristic may be employed, such as projecting knobs, smooth
rubber, knurls, etc.
The nature of the primary or confining surface is of consequence,
and in general should be smooth and be of a material having a low
coefficient of friction. Also, the invention permits high speed
operation, and in certain instances the friction heating of the low
friction confining surface can be a factor, leading to the choice
of Teflon impregnation or use of other materials having favorable,
low coefficients of friction. The nature of the desired treatment
also influences the construction of this primary or confining
member. Where the preferred layer form of primary and overlying
retarder members are employed, the thickness of the primary member
sets the spacing of the emery at the tip of the primary. Where it
is desired to impart a gross crepe or decorative pleated effect,
these can be obtained simply by choice of an adequate thickness of
the primary member. However, where such gross crepes are to be
suppressed, it is desired to avoid any abrupt large spacing. At the
same time it is often desired to have thick primary members so that
they can be handled with ease by mill personnel without danger of
damaging them. Getting the emery down to the appropriate spacing
for initial contact with the material is facilitated by the tapered
margin on a thick plate according to FIG. 5, and the use of a
conformable material as a backing according to FIG. 9.
Where it is desired to achieve special effects, this primary member
may be slotted or grooved, to provide discontinuities or variations
in the treatment, and similar variations can occur in the retarder
area.
Pretreatment of the material can have important effects, and the
nature of possible treatments is made quite wide because of the
invention. Thus a pretreatment with a lubricant such as a silicone
spray is possible to ensure smooth movement of sticky and other
difficult materials; the retarding effects of the projections or of
the rough retarding surface being still operable even in the
presence of such treatment substances.
Temperature control is to be observed for temperature-sensitive
products. Thus in the case of making nylon tricot stretchy in the
machine direction temperatures of pretreatment or during the
treatment may be maintained slightly below the softening
temperature, e.g., at 350.degree.. However, for the purpose of
improving cover and bulk without so much permanent densification,
it is found that operation at around 250.degree. F for this
particular material has distinct advantages. In the case of cotton
knit, controlled prestretching and steaming are essential to ensure
proper plasticity and dimensional stability.
In the case of papers and numerous other products, it is important
to maintain a suitable moisture content to ensure uniform
production; in such cases humidity chambers or other such
pretreatments are indicated, with or without chemical treatment and
temperature control. Much, as we have said, depends upon the final
result that is desired.
Important advantages are also obtainable with mechanical
pretreatment of the materials. In one important instance materials
to be "worked" or rendered stretchy in the cross as well as machine
direction are pretreated to have a multiplicity of fine
corrugations running lengthwise of the material. These longitudinal
flutes after passing under the confining and retarding surfaces can
result in a two-way stretch or softening of the material.
Post-treatment of the materials to preserve or take advantage of
the properties obtained from the present machine and process are
also advantageous. Tension treatment and heat setting are perhaps
most common, but chemical treatments, chilling and special coatings
are also of advantage in numerous instances. It is to be noted in
this connection that in certain instances the main elements of the
machine are useful. Thus where a heated roll is employed to define
the driving surface, an extended first portion of the confining
surface can assist in preheating the material and/or an extended
portion of the retarding surface can assist in continuing to
confine the treated material against the roll after treatment, for
purposes of post-heating.
In another preferred embodiment, instead of a driven roll, a
driving member in the form of a belt drive surface is employed. For
instance, in the treatment of nonwovens and papers, large endless
belts having belt widths greater than five feet are feasible. The
belts may have appropriate gripping or driving surfaces. The
material is confined against either the flat or the curved portion
of the belt. For obtaining angular treatment a retarder set at an
angle to the direction of travel can be employed in the flat
portion of the belt, with considerable simplicity. FIG. 12
illustrates this arrangement when the development of the drive
surface is taken as the belt here being discussed.
The retarder as described above can be employed to retard materials
driven on other surfaces, such as for instance paper being driven
and creped on the conventional hot surface of a Yankee Dryer.
From the foregoing description of preferred embodiments of the
invention it is apparent that there are a host of variables which
affect the specific structure and geometry to be employed for
treating any given material for the purpose of producing any
specific desired effect in the end porduct. For example, the drive
surface may vary from smooth to very rough, the particular
character thereof being chosen depending on the nature of the
material being run and the desired end result. The drive surface
geometry may vary from flat to sharply curved, depending on whether
it is provided by a belt or rolls of different diameters. The
various parts of the machine which engage the material may be
heated to any desired temperature for the treatment contemplated,
but the heat applied to the material is not only a function of
temperature but the time of exposure of the material to the heated
elements and this in turn is a function of machine speed. This fact
creates start-up and stopping problems where higher temperatures
are employed, even though the temperatures are satisfactory under
running conditions. It will be understood that these are but a few
examples of the many variables (at least 50) which we have
identified and which include: the characteristics of the drive
surface, of the confining surface and of the retarding surface, the
dimensions and mutual spacings thereof, the innumerable kinds of
materials which may be treated, and the profound differences
between starting and running conditions.
* * * * *