U.S. patent application number 10/068848 was filed with the patent office on 2002-08-08 for fabric hydroenhancement method & equipment for improved efficiency.
Invention is credited to Greenway, J. Michael, Lawrence, Jackson, Malaney, Frank E., Sternlieb, Herschel, Ty, Frederick.
Application Number | 20020104203 10/068848 |
Document ID | / |
Family ID | 25532113 |
Filed Date | 2002-08-08 |
United States Patent
Application |
20020104203 |
Kind Code |
A1 |
Greenway, J. Michael ; et
al. |
August 8, 2002 |
Fabric hydroenhancement method & equipment for improved
efficiency
Abstract
Improvements in hydroenhancement efficiency are obtained by
operating a manifold in relative movement to fabric transported
under the manifold so as to deliver a low energy to the fabric per
pass in multiple passes on the fabric. For example, a low energy
per pass of 1/10 to 1/48 the total energy delivered in 10 passes or
more can obtain good enhancement results as compared to
conventional hydroenhancing at higher total energy levels delivered
in fewer passes. This results in greater enhancement efficiency and
reduction in wasted energy, and also improves fabric coverage and
reduces fabric shrinkage. The low-energy-per-pass, multiple-pass
approach can be implemented with improved hydroenhancing equipment
of reduced equipment size and cost which simulate multiple passes
on the fabric. In one embodiment, a jigging hydroenhancing
equipment transports the fabric back and forth under a stationary
manifold between a pair of unwind/windup reels to simulate multiple
passes on the fabric. Other embodiments employ a manifold or
manifold system that is reciprocated, oscillated, or rotated to
simulate multiple passes on the fabric. Other variations for
improving hydroenhancement include angling the manifold at a
diagonal to the fabric travel direction, using a high density
number or double rows of jets to eliminate interference patterns,
using combined upstream and downstream manifolds together for
improved coverage on the fabric, and providing a baffle in the
manifold in proximity to the jet strip to generate constantly
fluctuating jets for improved utilization of enhancement
energy.
Inventors: |
Greenway, J. Michael;
(Westwood, MA) ; Lawrence, Jackson; (Nashville,
NC) ; Sternlieb, Herschel; (Brunswick, ME) ;
Ty, Frederick; (Walpole, MA) ; Malaney, Frank E.;
(Charlotte, NC) |
Correspondence
Address: |
OSTRAGER CHONG & FLAHERTY LLP
825 Third Avenue
New York
NY
10022
US
|
Family ID: |
25532113 |
Appl. No.: |
10/068848 |
Filed: |
February 11, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10068848 |
Feb 11, 2002 |
|
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08986132 |
Dec 5, 1997 |
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Current U.S.
Class: |
28/104 ;
28/167 |
Current CPC
Class: |
D04H 18/04 20130101;
D06C 29/00 20130101 |
Class at
Publication: |
28/104 ;
28/167 |
International
Class: |
D04H 001/46 |
Claims
We claim:
1. An improved hydroenhancing equipment, comprising: a manifold
having a row of jet orifices which emit a curtain of fluid jets at
a given level of total delivered energy per weight of fabric;
transport means for transporting the fabric in a travel direction
at a given speed relative to the manifold so that the curtain of
fluid jets impacts on the fabric; wherein the manifold is operated
in movement relative to the transporting of the fabric such that
the curtain of fluid jets is delivered to the fabric at a low
energy per pass which is a selected fraction of the given level of
total delivered energy and in a high number of passes on the fabric
which is a multiple corresponding to the selected fraction, whereby
an improved conversion of delivered energy to enhancement energy is
obtained on each pass and waste of energy is reduced.
2. An improved hydroenhancing equipment according to claim 1,
wherein the manifold is stationary and a pair of unwind/windup
reels are provided as said transport means for jigging the fabric
back and forth a number of times under the manifold to simulate
multiple passes on the fabric.
3. An improved hydroenhancing equipment according to claim 2,
wherein another stationary manifold is arranged on an opposite side
of the fabric, so that both sides of the fabric are treated in one
process run.
4. An improved hydroenhancing equipment according to claim 2,
wherein a small-diameter support roll is arranged to support the
fabric on a side opposite from the manifold and is aligned relative
to the manifold at an angle to the vertical direction so as to
allow for drainage of fluid downward away from the path of the
fabric around the support roll.
5. An improved hydroenhancing equipment according to claim 4,
wherein water drainage means is provided for the drainage of fluid
downward away from the path of the fabric and forms part of a
compact containment structure containing the manifold and support
roll.
6. An improved hydroenhancing equipment according to claim 2,
wherein said transport means jigs the fabric back and forth in a
range of from 9 to 23 times, depending on fabric weight, line speed
and fluid pressure.
7. An improved hydroenhancing equipment according to claim 1,
wherein the manifold is reciprocated back and forth a number of
times in a cross direction relative to the travel direction of the
transported fabric to simulate multiple passes per given area of
the fabric.
8. An improved hydroenhancing equipment according to claim 7,
wherein the manifold is formed as a short, compact section having a
width less than the width of the fabric and is reciprocated across
the travel direction of the fabric to apply the fluid jets in
overlapping swathes on the fabric.
9. An improved hydroenhancing equipment according to claim 8,
wherein the fabric has a given width and is transported at a given
line speed, and the manifold has a jet curtain width of one-third
the fabric width and is reciprocated in the cross direction at a
speed of about 48 times the line speed in order to simulate 16
passes per given area of the fabric.
10. An improved hydroenhancing equipment according to claim 8,
wherein the short section of manifold is reciprocated at a diagonal
angle to the fabric travel direction for eliminating the generation
of interference patterns in the fabric.
11. An improved hydroenhancing equipment according to claim 1,
wherein two manifolds are spaced apart in parallel extending across
the width of the fabric and are coupled together by a spring
element and oscillated in opposite phase to each other to simulate
multiple passes on the fabric while conserving oscillation
energy.
12. An improved hydroenhancing equipment according to claim 11,
wherein the two manifolds are arranged on the same side of the
fabric to double the number of passes with each oscillation.
13. An improved hydroenhancing equipment according to claim 12,
wherein the two manifolds are oscillated at 6 Hertz with an
oscillation amplitude of 2.4" to provide the equivalent of 24
passes over fabric moving at a line speed of 10 fpm.
14. An improved hydroenhancing equipment according to claim 11,
wherein the two manifolds are arranged on opposite sides of the
fabric to treat both sides of the fabric in one process run.
15. An improved hydroenhancing equipment according to claim 11,
wherein the two manifolds are angled across the fabric travel
direction and oscillate on a diagonal for eliminating the
generation of interference patterns in the fabric.
16. An improved hydroenhancing equipment according to claim 1,
wherein the manifold is a drum manifold having a plurality of jet
strips with respective rows of jet orifices mounted around the
periphery thereof, said drum manifold being rotated to apply the
fluid curtains from the plurality of jet strips in overlapping
swathes to simulate multiple passes on the fabric.
17. An improved hydroenhancing equipment according to claim 16,
wherein the drum manifold is arranged at a diagonal angle to the
fabric travel direction to eliminate the generation of interference
patterns in the fabric.
18. An improved hydroenhancing equipment according to claim 16,
wherein the drum manifold has three jet strips mounted thereon and
is rotated to have a surface velocity in the fabric travel
direction at four times the speed of fabric transport so as to
simulate nine passes over the fabric in a process run.
19. An improved hydroenhancing equipment according to claim 16,
wherein the drum manifold has three jet strips mounted thereon and
is rotated to have a surface velocity opposite to the fabric travel
direction at four times the speed of fabric transport so as to
simulate 15 passes over the fabric in a process run.
20. An improved hydroenhancing equipment according to claim 1,
wherein two manifolds are spaced apart in parallel on opposite
sides of the fabric and are coupled together by a spring element
and oscillated in opposite phase to each other, in order to
simulate multiple passes on both sides of the fabric in a process
run while conserving oscillation energy.
21. An improved hydroenhancing equipment according to claim 20,
wherein means are provided in conjunction with said unwind and
windup reels for dispensing and accumulating the fabric in
incremental advances under the manifolds as the fabric is supplied
from and wound on reels continuously.
22. An improved manifold for hydroenhancing fabric, comprising: a
manifold body having a main plenum in a central portion thereof and
at least one cavity formed in a peripheral portion thereof and
extending in an axial direction of the manifold body for removably
mounting a flow module assembly therein; a flow module having an
upper wall defining an inlet for receiving high pressure fluid from
said main plenum of said manifold body, a lower wall having means
for holding a jet strip having a row of jet orifices for emitting
fluid jets from the manifold, and module walls defining an interior
plenum therein for distributing a flow of the high pressure fluid
received through the inlet to the orifices of the jet strip;
wherein said manifold body cavity has cavity walls of a shape
corresponding to the external shape of the flow module walls so as
to allow insertion of the flow module into said cavity along the
axial direction with a clearance space therebetween; and a pair of
rigid, elongated sealing strips which are forcibly inserted in the
axial direction between the cavity walls of the manifold body and
the walls of the inserted flow module on opposite sides of the
lower wall of the flow module holding said jet strip therein, for
holding said flow module tightly in said cavity and sealing the
cavity.
23. An improved manifold according to claim 22, wherein said flow
module includes a baffle positioned in close proximity to the jet
strip for creating turbulence in the fluid flow to the jet strip
such that the jets emitted from the jet orifices have a constantly
fluctuating cross-sectional shape and direction.
24. An improved manifold according to claim 23, wherein said baffle
is a metal plate bent to form a rigid channel shape with a central
constriction for the flow of fluid from the inlet to the jet
orifices.
25. An improved manifold according to claim 22, wherein said flow
module has a elongated circular groove formed in a top surface of
its upper wall around said inlet to said flow module, and an O-ring
is fitted into said groove for sealing the top surface of the flow
module and the cavity.
26. An improved manifold according to claim 22, wherein the cavity
walls and the walls of the flow module are corresponding angled for
seating of the flow module in the cavity and sealing the flow
module against the cavity walls.
27. An improved manifold according to claim 22, wherein said
manifold body is formed as a drum having a plurality of cavities on
its periphery for removably mounting a corresponding plurality of
flow module assemblies and respective jet strips therein.
28. An improved manifold according to claim 27, wherein said drum
manifold is rotated at a predetermined speed so as to simulate
multiple passes of the jet streams of the plurality of jet strips
on a fabric.
29. An improved hydroenhancing equipment, comprising: a combination
manifold having combined rows of jet orifices for emitting
respective curtains of fluid jets to impact on a fabric; a
transport surface for transporting the fabric in a given travel
direction relative to the manifold; wherein the combination
manifold includes a downstream manifold relative to the fabric
travel direction for emitting fluid jets pointing straight downward
on the fabric, and an upstream manifold relative to the fabric
travel direction for emitting jets canted at an angle toward the
fabric travel direction to impact toward the impact zone of the
downstream manifold for greater blooming of yarns in the impact
zone of the fabric.
30. An improved hydroenhancing equipment according to claim 29,
wherein the upstream manifold is provided with orifices having a
dense spacing of jets greater than a spacing of yarns in the fabric
to eliminate interference patterns.
31. An improved hydroenhancing equipment according to claim 30,
wherein the upstream manifold is provided with orifices arranged in
a double row of 60 jets/inch, the upstream manifold is canted at a
45.degree. angle toward the fabric travel direction, and has an
impact on the fabric equivalent to a jet density of 168
jets/inch.
32. An improved method of hydroenhancing fabric using a manifold
having a row of jet orifices which emit a curtain of fluid jets at
a given level of total delivered energy per weight of fabric to
impact on a side of the fabric as it is transported in a travel
direction at a given speed relative to the manifold, wherein the
improvement comprises operating the manifold in movement relative
to the transporting of the fabric such that the curtain of fluid
jets delivers a low energy to the fabric per pass which is a
selected fraction of the given level of total delivered energy and
in a high number of passes over the fabric which is a multiple
corresponding to the selected fraction, whereby an improved
conversion of delivered energy to enhancement energy is obtained on
each pass and waste of energy is reduced.
33. An improved method of hydroenhancing fabric according to claim
32, wherein the manifold comprises at least one stationary manifold
extending across the width of the fabric, and the fabric is
transported under the manifold at a high speed such that the total
delivered energy to the fabric per manifold is 0.0625 hp-hr/lb or
lower.
34. An improved method of hydroenhancing fabric according to claim
32, wherein the energy delivered to the fabric per pass is in the
range of about {fraction (1/10)} to {fraction (1/48)} of the total
delivered energy, and the number of passes on the fabric is 10 or
higher.
35. An improved method of hydroenhancing fabric according to claim
32, wherein a fabric made of polyester spun yarn is treated with a
total delivered energy of 0.25 hp-hr/lb or lower in 16 passes or
higher and has a fabric coverage (measured in terms of air
permeability) in the range of about 60 cfm/ft2 or lower.
36. An improved method of hydroenhancing fabric according to claim
32, wherein the manifold is reciprocated back and forth in a cross
direction relative to the transport direction of the fabric to
simulate multiple passes on the fabric in a process run.
37. An improved method of hydroenhancing fabric according to claim
32, wherein the manifold is reciprocated at a diagonal angle to the
fabric travel direction to eliminate the generation of interference
patterns in the fabric.
38. An improved method of hydroenhancing fabric according to claim
32, wherein two manifolds are spaced apart in parallel extending
across the width of the fabric and are oscillated in opposite phase
to each other to simulate multiple passes on the fabric.
39. An improved method of hydroenhancing fabric according to claim
38, wherein the two manifolds are arranged on the same side of the
fabric to double the number of passes with each oscillation.
40. An improved method of hydroenhancing fabric according to claim
38, wherein the two manifolds are arranged on opposite sides of the
fabric to treat both sides of the fabric in one process run.
41. An improved method of hydroenhancing fabric according to claim
38, wherein the two manifolds are oscillated at a diagonal angle to
the fabric travel direction to eliminate the generation of
interference patterns in the fabric.
42. An improved method of hydroenhancing fabric according to claim
32, wherein the manifold is a drum manifold having a plurality of
jet strips mounted thereto and is rotated to apply jet curtains in
overlapping swathes to simulate multiple passes on the fabric.
43. An improved method of hydroenhancing fabric according to claim
42, wherein the drum manifold is arranged at a diagonal angle to
the fabric travel direction to eliminate the generation of
interference patterns in the fabric.
44. An improved method of hydroenhancing fabric according to claim
32, wherein the manifold is stationary and the fabric is
transported back and forth under the manifold a number of times
between a pair of unwind/windup reels to simulate multiple passes
on the fabric.
45. An improved method of hydroenhancing fabric according to claim
44, wherein two stationary manifolds are arranged on opposite sides
of the fabric to treat both sides of the fabric in a process
run.
46. An improved method of hydroenhancing fabric according to claim
32, wherein two manifolds are arranged on opposite sides of the
fabric and are coupled together and oscillated to simulate multiple
passes on both sides of the fabric in a process run.
47. An improved method of hydroenhancing fabric according to claim
32, wherein the manifold is provided with a high jet density of
from 100 to 200 jets/inch in the row of jet orifices for treating
woven fabric having a yarn density of 40 warp-yarns/inch or more in
order to eliminate the generation of interference patterns in the
fabric.
48. An improved method of hydroenhancing fabric according to claim
47, wherein the high jet density is provided by arranging the jet
orifices in two rows offset from and in close proximity to each
other.
49. An improved method of hydroenhancing fabric according to claim
32, wherein the manifold is provided with jet orifices which emit
fans jets forming a continuous water curtain on the fabric in order
to eliminate the generation of interference patterns in the fabric.
Description
TECHNICAL FIELD
[0001] This invention generally relates to the field of
hydroenhancing surface properties of textile fabric by subjecting
it to hydrojet treatment, and more particularly, to improving the
efficiency of fabric hydroenhancement methods and equipment.
BACKGROUND OF INVENTION
[0002] Prior hydroenhancement technology teaches that certain
properties of woven or knitted fabrics, such as cover, yarn
blooming, surface texture, hand, drape, etc., can be enhanced by
impacting the surface of the fabric with rows of jet streams from a
series of overhead manifolds as the fabric is conveyed on a support
surface, as illustrated in FIG. 2, for example. Such conventional
hydroenhancing equipment is described in greater detail in
commonly-owned U.S. Pat. No. 4,967,456 of Sternlieb et al., issued
on Nov. 6, 1990, entitled "Apparatus and Method For Hydroenhancing
Fabric", which is incorporated herein by reference.
[0003] Generally, the conventional view has been that the degree of
enhancement is related to the amount of energy imparted to the
fabric. That is, the more energy delivered to the fabric, the more
pronounced the enhancement effect. For example, U.S. Pat. No.
3,493,462 to Bunting teaches that the degree of surface treatment
is related to the total energy E expended per weight of fabric in a
pass under a hydrojet manifold, as calculated by the following
equation:
E=0.125 (YPG/sb), in hp.-hr./lb. of fabric, where
[0004] Y=number of hydrojets (orifices) per linear inch of
manifold,
[0005] P=pressure of fluid in the manifold, in p.s.i.g.,
[0006] G=volumetric flow of fluid in cu.ft./min. per orifice,
[0007] s=speed of passage of fabric under the manifold, in
ft./min., and
[0008] b=weight of fabric treated, in oz./sq.yd.
[0009] This equation provided by Bunting is a standard calculation
used in the industry for energy expended in the hydrotreatment of a
fabric.
[0010] The degree of enhancement imparted to the fabric can be
measured in terms of the cover of the fibers in the fabric. Cover
has an inverse relation to the air permeability of the fabric,
which is measured in cu.ft./min./sq.ft. (cfm/ft.sup.2). The graph
in FIG. 1 illustrates the relationship, as is known conventionally,
between the total energy expended in hydrotreatment and the
resulting air permeability property of the treated fabric. The
graph shows that as the total energy expended (in hp-hr/lb)
increases, the air permeability (in cfm/ft.sup.2) of the fabric
decreases and, hence, the degree of enhancement, i.e., the cover of
the fabric, increases.
[0011] Conventional equipment for hydroenhancing fabric has
employed high-speed processing lines having one or more manifolds
in parallel across the width of fabric conveyed in a machine
direction on a conveyor, as shown in FIG. 2, for example. A fabric
web 12 is advanced through a weft straightener 14, which aligns the
fabric weft prior to processing, onto conveyor belt 22 driven on
rollers 24 in a machine direction (arrow indicating a downstream
direction) through a hydroenhancing station 16. A plurality of
manifolds 30 are spaced apart and aligned in parallel extending in
a cross direction (normal to the plane of the figure) across the
width of the conveyed fabric. Each manifold has a row of jet
orifices 32 which emit jets of water downwardly to impact on one
side of the fabric 12. The belt 22 has a porous support surface
(such as a wire or plastic mesh) for supporting the fabric while
allowing fluid to drain down to a collector system 19. The opposite
side of the fabric may be treated in the same run by another
hydroenhancing station 18 having a drum conveyor 34 and a series of
manifolds 30 spaced around the drum circumferentially. Following
hydroenhancement, the fabric 12 is advanced to a tenter frame 20
for drying under tension to produce a uniform fabric of specified
width. A more detailed description of such hydroenhancing equipment
is provided in commonly-owned U.S. Pat. No. 4,967,456 of Sternlieb
et al., issued on Nov. 6, 1990, entitled "Apparatus and Method For
Hydroenhancing Fabric", which is incorporated herein by
reference.
[0012] Conventional techniques for obtaining suitable
hydroenhancement of fabric include using high pressures of fluid
jetted from the manifold, large-diameter jet orifices or lowered
processing speeds to impact high energies of fluid per area of
fabric per unit of time, and/or multiple manifold configurations.
However, the requirements for handling high fluid pressures or
fluid energies or multiple manifolds can increase the equipment
size and complexity, as well as equipment and maintenance costs,
significantly. The use of high total delivered energies, say in the
range of 1.0 or 2.0 hp-hr/lb, is also less efficient, as
improvements in fabric enhancement tend to taper off with further
increases in energy. The use of high delivered energies can also
cause greater fabric shrinkage, and can exacerbate the problem of
interference patterns generated on the surface of the fabric by
making traces of the jet streams more prominent in contrast to the
yarn spacing in the fabric.
[0013] Hydroenhancement technology is related to technology for
hydroentanglement or hydraulic needling of a web of fibers to
produce autogenously bonded nonwoven fabric. In hydroentanglement
technology, it has been the practice to obtain the desired degree
of fiber entanglement with high energy input to the web of fibers.
For the production of large quantities of hydroentangled fabric,
large-scale, high-speed hydroentanglement lines and
multiple-manifold equipment have been employed to deliver the
needed hydroentanglement energies to continuously running webs.
This type of large-scale equipment has also been used for
hydroenhancement. However, it has a large capital cost which may
only be justified for operations that can utilize very high output
rates. For diversified product lines, the enhancement of different
types of fabric in medium to small quantities requires equipment
that is less capital intensive, adaptable to different fabrics, and
more efficient to operate.
[0014] It is therefore a principal object of the present invention
to improve the efficiency of fabric hydroenhancement by employing
equipment that is smaller in size, can be adaptably configured for
different types of fabrics, and delivers fluid energies for
hydroenhancement in an optimized manner without wasting energy. It
is a specific object of the invention to obtain comparable or even
improved enhancement of fabrics with equipment that is greatly
reduced in cost to build, operate, and maintain. A further object
is to provide improved methods and equipment for fabric
hydroenhancement that allow greater flexibility in making process
adjustments for enhancing different types of fabrics and types of
surface treatments. Still further objects of the invention include
reducing warp yarn shrinkage and eliminating interference patterns
in hydroenhancement of fabric.
SUMMARY OF INVENTION
[0015] In the present invention, the efficiency of fabric
hydroenhancement can be improved by treating fabric with fluid jets
at low levels of fluid energy per pass in multiple passes over the
fabric. This can be carried out with compact equipment designed to
simulate multiple passes on the fabric, which is of smaller scale
and significantly reduced cost than conventional hydroenhancing
equipment.
[0016] In a preferred embodiment of improved hydroenhancing
equipment in accordance with the invention, referred to herein as
"jigging equipment", a length of fabric is conveyed back and forth
between a pair of unwind/windup reels on a sinuous path between a
pair of manifolds for treating opposite sides of the fabric in
multiple passes. The manifolds may be aligned at an angle to the
vertical relative to support rolls supporting the fabric in order
to allow convenient drainage of fluid away from the path of the
fabric around the support rolls. This can eliminate the need for
vacuum-suction removal of fluid. As an improvement to reduce
equipment size, small-diameter solid support rolls may be used in
treating certain type of fabrics.
[0017] The jigging equipment is configured to be self-contained and
small in size. Only two manifolds are used to treat both sides of
the fabric. This eliminates the need for the large and costly type
of conventional processing lines that employ multiple manifolds and
an extensive conveyor and fluid removal system for treating fabric
in one continuous run. Suitable hydroenhancement of fabric can be
obtained, for example, by conveying it back and forth 5 to 12 times
(depending on fabric construction and the enhancement desired)
between the reels with a manifold fluid pressure of 1800 psi. The
total energy can be as low as 0.12 hp-hr/lb (0.062 hp-hr/lb per
side). The low-energy, multiple-pass approach converts more of the
delivered fluid energy to enhancement energy for greater efficiency
and reduction in wasted energy, and also improves fabric coverage
and reduces fabric shrinkage.
[0018] Other preferred embodiments of improved hydroenhancing
equipment utilize a manifold or manifold system that is
reciprocated, rotated, or oscillated relative to the fabric
transport to simulate multiple passes on the fabric. In one
version, a short section of manifold is reciprocated across or at
an angle to the fabric travel direction to apply a jet curtain in
overlapping swathes on the fabric in order to simulate multiple
passes. The speed of reciprocating the manifold is selected
relative to the fabric travel speed to obtain the desired number of
passes per area of fabric per unit of time.
[0019] In another version of the improved hydroenhancement
equipment, a pair of manifolds are coupled together and oscillated
to simulate multiple passes on the fabric while conserving
oscillation energy. The two manifolds can be arranged on the same
side of the fabric to double the number of passes, or on opposite
sides of the fabric for two-sided treatment in one run. The
manifolds may be placed at an angle to the fabric travel direction
(and warp yarns) for eliminating interference patterns in the
fabric.
[0020] In another version, a plurality of jet strips are mounted on
a rotating drum manifold to apply multiple jet curtains in
overlapping swathes on the fabric in order to simulate multiple
passes. The drum manifold may also be arranged at an angle to the
fabric travel direction for eliminating interference patterns in
the fabric. Each jet strip may be mounted in a jet module that is
inserted in a cavity on the periphery of the drum and held in place
by pressure-fitting sealing strips.
[0021] As another feature of the invention, a manifold for the
improved hydroenhancing equipment, of the type having a plenum for
receiving input fluid under pressure and communicating through a
row of distribution holes to an output end mounting a jet strip
with jet orifices formed therein, has a baffle interposed
downstream of the row of distribution holes and in close proximity
to the jet strip for inducing turbulence in the fluid flow to cause
the jets emitted from the jet orifices to have a constantly
fluctuating cross-sectional shape, direction, and structure. For
example, the resulting jets may be emitted as randomly spiralling
ribbons. This results in distributing the delivered energy of the
jets over a constantly changing impact area on the fabric for more
efficient utilization of enhancement energy, and also improved
enhancement of fabric including reducing or eliminating
interference patterns in the fabric.
[0022] Another, combined-manifold embodiment of improved
hydroenhancing equipment employs paired manifolds, with a
downstream manifold having jets pointing vertically downward on the
fabric and an upstream manifold having jets biased at an angle
toward the fabric travel direction. The combined-manifold
configuration results in improved utilization of delivered energy
and fabric cover. A dense spacing of jets, or a double row of jets,
may be used to eliminate interference patterns. The manifolds may
also be angled across the fabric travel direction to eliminate
interference patterns.
[0023] The low-delivered-energy, multiple-pass technique can also
be implemented with conventional hydroenhancing equipment by
increasing the process (line) speed to reduce the energy per pass
delivered to the fabric and processing the fabric with multiple
manifolds and/or in multiple runs. Good results have been obtained
by operating a conventional line with multiple manifolds operated
at conventional fluid pressures and energy levels but at high line
speeds so that the delivered energy per side is lowered. Good
enhancement with low energy delivered by multiple manifolds.
[0024] Other objects, features, and advantages of the present
invention are described in further detail below, with reference to
the following drawings:
BRIEF DESCRIPTION OF DRAWINGS
[0025] FIG. 1 illustrates relationship as known conventionally
between energy expended in hydrotreatment and the resulting
coverage (measured in terms of air permeability) of the fabric.
[0026] FIG. 2 is a schematic illustration of a conventional
hydroenhancing line for enhancing the surface properties of fabric
by hydrojet treatment.
[0027] FIG. 3 shows one embodiment of improved hydroenhancing
equipment employing a pair of stationary manifolds on opposite
sides of the fabric and a pair of unwind/windup reels for
simulating multiple passes on the fabric by jigging the fabric back
and forth from one reel to the other.
[0028] FIG. 4 is a schematic diagram of a preferred embodiment of
the jigging hydroenhancement equipment having support drums
provided with vacuum suction elements for water removal.
[0029] FIG. 5 is a schematic diagram of another embodiment of
improved hydroenhancing equipment employing a compact,
reciprocating manifold for simulating multiple passes on a fabric
which enables the fabric to be enhanced in a cross direction in a
continuous process.
[0030] FIG. 6 shows a modification of the manifold of FIG. 5
arranged to reciprocate at an angle to the fabric travel direction
which enables the fabric to be enhanced in a diagonal direction in
a continuous process.
[0031] FIG. 7 illustrates schematically how operation of the
reciprocating manifold in the cross or diagonal direction avoids
the generation of interference patterns with warp yarns in the
fabric.
[0032] FIG. 8 is a schematic diagram of another embodiment of
improved hydroenhancing equipment employing a pair of oscillating
manifolds on the same side of the fabric for simulating multiple
passes on the fabric and enables the fabric to be enhanced in a
diagonal direction in a continuous process.
[0033] FIG. 9 shows a further version of improved hydroenhancing
equipment employing a pair of oscillating manifolds on opposite
sides of the fabric for simulating multiple passes on the
fabric.
[0034] FIG. 10 shows another embodiment of improved hydroenhancing
equipment employing a rotating multi-strip drum manifold for
simulating multiple passes on the fabric.
[0035] FIG. 11 is a detailed schematic view of the rotating
multi-strip drum manifold for simulating multiple passes on the
fabric.
[0036] FIGS. 12, 13, and 14 illustrate the effect of arranging the
drum manifold at an angle to the fabric travel direction to
eliminate interference patterns.
[0037] FIG. 15 is a perspective view of a flow module for the
rotating multi-strip drum manifold of FIG. 10.
[0038] FIG. 16 is a cross-sectional view of the flow module
inserted in the rotating multi-strip drum manifold of FIG. 10.
[0039] FIG. 17 is a schematic view of another embodiment of
improved hydroenhancing equipment employing two manifolds combined
together for improved hydroenhancement and fabric coverage.
[0040] FIG. 18 is a graph of air permeability versus number of
passes for different levels of total energy delivered, using the
low-delivered-energy, multiple-pass method of the present
invention.
[0041] FIGS. 19A, 19B are graphs of warp and weft shrinkage (in
percentages) versus number of passes at different levels of total
delivered energy, using the low-delivered-energy, multiple-pass
method of the present invention.
DETAILED DESCRIPTION OF INVENTION
[0042] The present invention proceeds from the realization that
equipment costs can be reduced and improvements in efficiency of
fabric hydroenhancement can be obtained by treating fabric with
fluid jets at low levels of fluid energy delivered to the fabric
per pass in multiple passes over the fabric. This is in contrast to
the conventional approach of using large-scale hydroenhancing lines
which treat fabric with relatively high amounts of total energy
delivered in one processing run.
[0043] It is theorized that in conventional hydroenhancing systems,
when high fluid energies are used, there is an initial blooming of
yarns when the fluid initially strikes the fabric, but most of the
remaining energy is wasted. The application of low energy per pass
in multiple passes in the present invention is counter-intuitive to
the conventional approach of applying high fluid energy with
multiple manifolds. Delivering low energy to the fabric per pass in
multiple passes results in more "enhancement energy" being used for
blooming yarn in the fabric and less energy being wasted. A desired
level of enhancement can be obtained cumulatively by subjecting the
fabric to limited treatment in multiple passes.
[0044] The low-energy-per-pass, multiple-pass approach of the
invention can be implemented using improved equipment which is
compact in size and of reduced cost. The improved equipment is
characterized by delivering a low energy per pass and simulating
multiple passes on the fabric. Certain preferred embodiments are
described below. However, it should be understood that the
low-energy-per-pass, multiple-pass approach may be adapted to other
types of hydroenhancing equipment which utilize the same principles
dislcosed herein.
[0045] I. Compact, Jigging Hydroenhancing Equipment
[0046] Referring to FIG. 3, one embodiment of improved
hydroenhancing equipment for carrying out the low-energy-per-pass,
multiple-pass method of the present invention is shown having a
pair of stationary manifolds 40a, 40b which impact a row of fluid
jet streams onto respective opposite sides of the moving fabric 12
against respective support rolls 42a, 42b. The components are
arranged compactly within an overall containment structure 48. The
fabric 12, guided around guide rolls 41, is jigged back and forth a
number of times under the manifolds to simulate multiple passes, by
unwinding it from one of the reels 44, 46 and winding it up on the
other reel, and vice versa.
[0047] As an improved feature, the support rolls 44, 46 may be
small-diameter solid rolls which have been found to be suitable for
hydroenhancing some types of fabric. For example, the rolls may
have a diameter of about 4 inches and a smooth or textured surface.
With the small-diameter rolls, the manifolds can be aligned at an
angle to the vertical direction relative to the rolls, in order to
allow convenient drainage of fluid downward away from the path of
the fabric around the support roll. A simple water catch pan 47 can
be used to collect water drained away from the jets of the manifold
42a impacting the fabric. The bottom of the overall containment
structure 48 can be used to collect water drained away from the
jets of the manifold 42b. The collected water is filtered and
recirculated, or discharged to sewer. The simple water collection
arrangement eliminates the need for the more typical vacuum-suction
removal of fluid.
[0048] Suitable hydroenhancement of fabric can be obtained using
this "jigging equipment" by operating the manifolds at relatively
low energy levels and jigging the fabric back and forth a number of
times to simulate multiple passes. Typical operating parameters for
the jigger equipment are given below:
1 Fabr. Wt. Speed (ypm) Pressure Passes Energy (oz/yd.sup.2) (ypm)
(psi) # (hp-hr/lb) 4 100 1800 9 0.5 6 100 1800 14 0.5 8 100 1800 18
0.5 10 100 1800 23 0.5 5.7 326 1800 12 0.125
[0049] The jigging equipment is configured to be self-contained and
small in size taking less floor space. Two manifolds can treat both
sides of the fabric in one run. Multiple manifolds may also be
used, if desired. An even number of passes results in the fabric
being wound on the same roll it started from, whereas an odd number
of passes results in its being wound on the other roll. Line speeds
may vary between 40 and 350 ypm. It is estimated that a production
efficiency per unit cost of jigging equipment of about five times
that of conventional equipment can be achieved.
[0050] A preferred embodiment of jigging hydroenhancement equipment
which can be used with all types of fabric is shown in FIG. 4
having stationary manifolds 60a, 60b which emit jet streams against
respective support drums 62a, 62b on respective opposite sides of
the fabric 12 conveyed back and forth between the pair of
bi-directional unwind/windup reels 64, 66. The support drums 62a,
62b are of the more conventional type having a porous drum surface
and vacuum-suction boxes on the inside of the drums for removal of
fluid.
[0051] II. Compact, Reciprocating Manifold
[0052] Another embodiment of improved hydroenhancement equipment
has a compact manifold or manifold system that is reciprocated,
rotated, or oscillated relative to the transported fabric to
simulate multiple passes on the fabric. This type of compact system
is of smaller scale and can have a greatly reduced cost as compared
to a conventional hydroenhancing line.
[0053] Referring to FIG. 5, one version of the improved
hydroenhancing equipment employs a short, compact section of
manifold 50 that is reciprocated in the cross direction (CD) back
and forth across the width FW of the fabric 12 being transported on
a conveyor (not shown) in a downstream fabric travel direction
(machine direction) MD. The resulting path of the short manifold
section 50 is a zig-zag path 51 traversing back and forth at a
relatively acute angle across the width of the fabric. The manifold
has a row of jets that generates a water curtain of a width MW
applied in overlapping swatches on the fabric. The ratio of
traversing speed of the manifold 50 to the moving speed of the
fabric and the manifold width MW are selected to enable the water
curtain to deliver a low energy per pass in multiple passes on the
fabric. For example, to simulate 16 passes over a fabric having a
width FW of 6 feet and moving at a line speed of 10 fpm, a manifold
having a curtain width MW of 2 feet can be reciprocated at a speed
of 480 fpm to traverse the fabric 16 times in the time it takes the
fabric to move 2 feet in the MD.
[0054] The traversing mechanism (not shown) for reciprocating the
manifold 50 can be of any conventional type. The hydroenhancing
station may employ an open mesh belt for the fabric transport, as
well as other processing components used conventionally. Since the
manifold has a shorter width MW (2 feet) for the partial row of
jets, as compared to a conventional manifold extending across the
full width (6 feet) of the fabric, the manifold structure is
required to handle much less water volume and pumping and
pressurization capacity than the conventional equipment.
[0055] As illustrated in FIG. 6, the manifold 50 can be arranged,
in a further modification, to reciprocate at a diagonal angle to
the travel direction MD of the fabric. This would have the
advantageous effect of eliminating interference patterns that might
be generated between the spacing of the jets with the regular
spacings of the yarn. It would also provide greater flexibility for
adjusting the traversing/fabric speed ratio, and thus the levels of
energy delivered per pass and the numbers of passes applied per
given time.
[0056] Instead of orifices delivering jets in columnar streams, the
manifold can employ a row of fan jets, for example, as described in
commonly-owned U.S. Pat. No. 4,995,151 of Siegel et al., issued on
Feb. 26, 1991, entitled "Apparatus and Method For Hydropatterning
Fabric", incorporated herein by reference. The larger diameter of
the fan jets and simpler structure can further reduce equipment
costs. The use of fan jets can eliminate the generation of
interference patterns since the overlapping fan jets create a
continuous water curtain that will not trace lines on the
fabric.
[0057] Diagonal enhancing may be particularly advantageous in the
case of continuous filament fabrics. In conventional equipment, a
stationary manifold emitting jet streams of a fixed inter-jet
spacing can result in tracing regularly spaced lines in the machine
direction on the moving fabric. As illustrated in FIG. 7, the
regular spacings of the MD-tracing jets and the MD-aligned warp
yarns can produce a recurring moire pattern of machine direction
stripes in the fabric, referred to as moire. With the compact
reciprocating manifold of the invention, the fluid jets are applied
back and forth at high speed in the cross direction CD or at a
diagonal, so that moire patterns are eliminated.
[0058] III. Oscillating Manifold or Manifold System
[0059] Referring to FIG. 8, another version of improved
hydroenhancing equipment has a pair of manifolds 50a, 50b coupled
by spring elements 54 that are oscillated to simulate multiple
passes on one side of the fabric 12 conveyed in the machine
direction MD on a conveyor 52. The manifolds are arranged to
oscillate 180.degree. in opposite phase (toward and away from each
other) in order to alternately store and use mutual oscillation
energy. The spring elements are selected to have a spring constant
for the desired frequency and amplitude of oscillation. In this
way, the driving energy needed to maintain the manifolds in
oscillation will be minimized. The two manifolds are arranged to
extend across the full fabric width FW in order to eliminate any
edge effects that might occur with the oscillation movements. The
manifolds are also arranged to oscillate diagonally at an angle to
the fabric travel direction (MD) to eliminate interference
patterns.
[0060] Oscillation of the manifolds can be obtained with similar
parameters as a conventional needle loom, for example, one which
oscillates at 20 Hertz with an amplitude of 2.4". The mass of the
needle plate for the typical loom is less than the mass of the
manifold, therefore the manifold would oscillate at a lower
frequency, e.g., 6 Hertz. The combined manifolds simulate twice the
number of passes on the fabric with each oscillation. Oscillating
two manifolds on a diagonal at 6 Hertz with an amplitude of 2.4"
provides the equivalent of 5 passes on fabric moving at a line
speed of 48 fpm, or 24 passes on fabric moving at a line speed of
10 fpm. It is estimated that a production efficiency, in terms of
yards of fabric per year per dollar of equipment cost, of four
times that of conventional hydroenhancing equipment with multiple
manifolds can be achieved with the oscillating manifolds
arrangement.
[0061] A full-width diagonal manifold oriented at 45.degree. across
the fabric would not necessarily require a jet density of the usual
60 jets/inch. The 45.degree. angle enables a 43 jets/inch jet strip
in the manifold to have the same effective jet density as a 60
jets/inch jet strip aligned to trace in parallel with the MD. On
the other hand, a 60 jets/inch jet strip at 45.degree. angle would
have the same effective jet density as an 85 jets/inch jet strip
aligned with the MD. The increase in effective jet density in the
latter case would also contribute to the elimination of
interference effects. As an example, the total energy delivered by
two diagonal manifolds operating at 1500 psi equipped with a 43
jets/inch jet strip with 0.005" holes enhancing a 200 gm/yd.sup.2
fabric at a mean process speed of 24 fpm is 0.326 hp-hr/lb.
[0062] To treat both sides, the fabric after a first run under both
manifolds is either flipped over for enhancing the other side in a
second run, or a second enhancing stage can be provided downstream
of the first stage for treating the other side in one process run.
Providing a second enhancing stage would increase the cost of the
equipment, but would facilitate continuous processing of
fabric.
[0063] FIG. 9 shows another version of an oscillating manifold
system for simulating multiple passes for fabric enhancement with a
minimum of equipment cost. A pair of oscillating manifolds 70a, 70b
are arranged to jet fluid streams onto the opposite sides of the
moving fabric 12 which is entrained around respective porous drums
72a, 72b and driven from unwind reel 76 to windup reel 74. The
manifolds, which are arranged across the fabric, are coupled by a
spring element 73 and are mutually oscillated in opposite phase
(toward and away) from each other to simulate multiple passes on
the fabric, while also conserving oscillation energy. The fabric is
enhanced in incremental lengths advanced to the manifold station
and treated during a given time period for a prescribed number of
manifold oscillations. A "J" box 77 from the unwind reel 76 and an
accumulator 78 to the windup reel 74 are provided for dispensing
and accumulating fabric with each incremental advance as the reels
are driven continuously.
[0064] With this oscillating, opposite-side manifolds arrangement,
both sides of the fabric can be treated with multiple simulated
passes in one process run. A two-manifold machine of this type can
be configured to enhance fabric at 0.25 hp-hr/lb total delivered
energy in 12 simulated passes at a mean process speed of 30 ft/min.
With this version, it is estimated that a production efficiency 20%
greater than even the previously described jigged-transport system
can be obtained.
[0065] IV. Rotating Multi-Strip Manifold
[0066] A further version of improved hydroenhancing equipment
having a low equipment cost employs a rotating multi-strip manifold
for simulating multiple passes on fabric. Referring to FIG. 10, a
plurality of jet strips 80 are spaced uniformly around the
periphery of a rotating drum manifold 82. Each jet strip is
comprised of a row of jet orifices supplied with high pressure
fluid from a central plenum for emitting a curtain of fluid jets
against the surface of the fabric. The fabric 12 is transported on
a support screen 84 of an endless conveyor system circumferentially
around the drum manifold 82. The drum manifold is rotated at a
higher speed than the transport speed of the support screen 84, so
that the jet curtains can impact on the fabric in overlapping
swathes to simulate multiple passes. A second rotating drum
manifold (not shown) may be arranged downstream for treating the
other side of the fabric.
[0067] The number of passes simulated by the rotating drum manifold
depends upon the number of jet strips and the relative speed and
direction of drum speed to fabric transport speed. For example, a
drum manifold having three jet strips rotated in the same direction
at a surface velocity four times that of the fabric transport speed
will simulate nine passes on the fabric (3 rotations per unit of
travel.times.3 jet strips). Rotation of the drum manifold counter
to the travel direction of the fabric will increase the number of
simulated passes that the fabric will receive. For example, if the
drum manifold rotates in the counter direction with a surface
velocity four times that of the fabric transport speed, then the
manifold will rotate five times per length of fabric travel to
simulate 15 passes on the fabric.
[0068] As illustrated in FIG. 12, the drum manifold may be arranged
at an angle (30.degree. indicated angle of the drum centerline CL)
to the fabric travel direction, resulting in the jet curtains being
continually displaced in the cross direction on each pass. This
ensures that the jets of the drum manifold do not trace lines in
the same positions on the fabric on each pass, thereby eliminating
the interference effect (moire) with regular yarn spacings in the
fabric.
[0069] FIG. 13 shows an example of the effective velocity Vr of the
jet curtain, having an effective angle of 43.degree., summed from
the drum velocity Vw at a 30.degree. angle in the same direction of
the fabric travel velocity Vf. FIG. 14 shows the effective velocity
Vr, having an effective angle of 23.degree., summed from the drum
velocity Vw at a 30.degree. angle in the opposite direction of the
fabric velocity Vf. Rotating the drum manifold in the same
direction as the fabric thus results in a greater angle of diagonal
enhancing for avoiding interference patterns.
[0070] Referring to the detailed view in FIG. 11, the rotating drum
manifold preferably has jet strips 80 mounted in respective flow
modules 86 that slide into correspondingly shaped module cavities
81 formed in the periphery of the drum manifold 82. Elongated
O-rings 88 are placed in a closed-loop groove 93 in the top surface
of the modules (see FIG. 15) to provide a seal around distribution
holes 89 communicating from the main plenum 90 of the drum manifold
to the inlet into each of the flow modules. High pressure water
enters the main plenum 90 and flows through the plenum filter 92 to
the flow modules 86 and then through the jet strips 80 to form the
jet curtains used for fabric enhancing. A baffle structure 83 is
provided in the interior plenum for creating a turbulent flow to
the jet orifices in accordance with another aspect of the invention
(described further below).
[0071] In FIG. 11, the jet discharge area of the flow modules may
employ low pressure or negative air pressure for suctioning off
water impacted on the fabric. An alternate arrangement is to
generate an air pressure of 1 psi that would produce the same
differential pressure as a vacuum box on the opposite side of the
fabric with a 1 psi vacuum. Ports 93 with openings in the discharge
area of the jet orifices can either communicate with vacuum
chambers 94 for the removal of water or with low positive pressure
to blow the excess water through the fabric. The incorporation of
water removal with the jet manifold structure would further reduce
the overall equipment size and cost.
[0072] Clearance is provided between the flow module and the cavity
walls so that the O-ring does not drag excessively along the top
surface of the cavity 81 upon insertion. The walls of the module 86
and the cavity 81 are correspondingly angled to properly seat the
module and seal it against the cavity walls, as shown in FIG. 16.
Rigid sealing strips 87 are forcibly inserted between the lower
rails of the cavity 81 and the lower surface of the inserted module
in order to take up the clearance space for tightly fitting the
flow module in the cavity and pressing the O-ring into contact with
the top surface of the cavity. The sealing strips 87 also seal the
cavity from the lower discharge area of the flow module. An end cap
91, shown in FIG. 15, is provided at one axial end of the flow
module 86 to facilitate replacement of the jet strip 80 without
having to remove the flow module from the drum manifold.
[0073] The close tolerances of the cavity 81 and the angled sides
of the flow module 86 can be fabricated using a specially designed
broach. The cavity is first machined out until close to the final
dimensions. The broach is then forced along the cavity to remove
the final material, achieving the angled sides in the process. The
top surface which provides the O-ring seal is smoothly finished
with grinding. This design for the flow module allows the module
components to be assembled and the module to be held in the drum
manifold by friction or interference fit without any bolts, thereby
lowering machining costs considerably.
[0074] V. Low-Energy, Multiple-Pass Method on Conventional
Equipment
[0075] The low-energy-per-pass, multiple-pass method can also be
implemented with conventional hydroenhancing equipment, such as
illustrated in FIG. 2, by increasing the process (line) speed to
attenuate the energy delivered to the fabric per pass and
processing the fabric in multiple passes by using a sufficient
number of manifolds and/or number of runs.
[0076] With conventional hydroenhancing equipment, a line speed of
up to 500 ft/min or higher may be used. The jet orifices may have
diameters in the range of from 0.005 to 0.010 inches and
center-to-center spacings of from 0.017 to 0.034 inches. The
manifolds may supply jets with pressures in the range of from 200
to 3,000 psi. Enhancement may be obtained with a total delivered
energy from 0.1 hp-hr/lb to 2.0 hp-hr/lb. A processing line may
have one, two, four, six or more manifolds arranged in series. A
typical configuration might employ two or four manifolds, with jets
of 0.005 inch orifice diameter spaced 0.017 inch apart (60
jets/inch), fluid pressure of 1500 psi, line speed of about 30 fpm,
and total delivered energy of 0.46 hp-hr/lb. As shown in FIG. 1,
treatment by conventional hydroenhancement equipment of spun yarn
fabric at delivered energies ranging from 0.1 to 2.0 hp-hr/lb per
weight of fabric results in fabric coverage (as measured in terms
of air permeability) of from 140 to 50 cfm/ft.sup.2.
[0077] The low-energy-per-pass, multiple-pass method implemented
with conventional hydroenhancing equipment can obtain significantly
more efficient utilization of delivered energy as enhancement
energy. The test results summarized on Table I were conducted on a
fabric referred to in the industry as Samuelson PFP Classic Style,
made of polyester spun yarn having a basis weight of 158
gm/yd.sup.2 (gsy). It was treated with conventional hydroenhancing
equipment having two manifolds, each with 60 orifices/inch of 0.005
diameter, and fluid pressure at 1500 psi. The total energy
delivered from both manifolds was varied in different trials over a
range from 0.125, 0.250, 0.50, to 1.0 hp-hr/lb (half this amount
per manifold). The energy delivered to the fabric per pass was
reduced to a fraction of the manifold energy level by increasing
the line speed from 10 fpm on up to 488 fpm, and the number of
passes was increased in increments from 2 passes to 100 passes. The
fabric was treated with an equal number of passes per side. The
weight (in grams and ounces), thickness (in mils), air permeability
(in cfm/ft.sup.2), warp shrinkage and weft shrinkage (in percent)
of the resulting fabric were measured.
[0078] Based upon the quantitative results of Table I, the graph in
FIG. 18 shows the relationship between air permeability versus
number of passes at different manifold energy levels. The graph
shows that, at any given manifold energy level, there is a marked
decrease in air permeability (corresponding to increase in fabric
coverage) as the energy delivered to the fabric per pass was
lowered (by increased line speed) and the number of passes was
increased. For example, for a manifold energy level of 1.0
hp-hr/lb, air permeability was reduced from about 90 cfm/yd.sup.2
obtained in two passes (at 10 fpm) to about 45 cfm/yd.sup.2
obtained in 16 passes (at 77 fpm) For fabric treated with a
manifold energy at 0.25 hp-hr/lb, air permeability was reduced from
about 94 cfm/yd.sup.2 obtained in two passes (at 38 fpm) to about
57 cfm/yd.sup.2 obtained in 32 passes (at 488 fpm). The graph shows
that air permeability increased slightly for 32 passes at 0.5
hp-hr/lb and 64 passes at 1.0 hp-hr/lb. Due to the high speed of
the passes creating anomalous results, the tests were repeated with
correction for possible screen shifting, and the repeat results
showed that air permeability at the higher number of passes was
reduced to or below the level at 16 passes, as was expected.
[0079] A further comparison was made of the fabric treated at
different manifold energy levels. A fabric enhanced at a manifold
energy level of 0.25 hp-hr/lb using 24 passes at 488 fpm was
visually inspected and found to be superior in surface cover
compared to fabric enhanced at a manifold energy level of 1.0
hp-hr/lb using 2 passes at 10 fpm. Similarly, a fabric enhanced at
a manifold energy level of 0.125 hp-hr/lb using 12 passes at 488
fpm was superior to a fabric enhanced at a manifold energy level of
1.0 hp-hr/lb using 2 passes at 10 fpm. The air permeability results
shown in the graph of FIG. 18 confirm these observations.
[0080] In a conventional process, the energy delivered to the
fabric per pass at a manifold energy level of 1.0 hp-hr/lb in 2
passes at 10 fpm line speed is 0.5 hp-hr/lb/pass. In the invention
process, the energy delivered to the fabric per pass at a manifold
energy level of 0.125 hp-hr/lb using 12 passes at 488 fpm line
speed is 0.0104 hp-hr/lb/pass. Therefore, for comparable
enhancement results obtained, the energy per pass at 1.0 hp-hr/lb
in the conventional process is 48 times greater than the energy per
pass at 0.125 hp-hr/lb in the invention process. These results
indicate that the low-delivered-energy, multiple-pass method of the
invention enables more of the delivered energy to be converted into
enhancement energy to obtain a comparable or better product, as
compared to conventional hydroenhancing methods using higher levels
of delivered energy to the fabric in fewer passes.
[0081] The above-described tests also show that a comparable
enhancement result (measured in terms of air permeability) was
obtained in the invention using 1/8 the manifold energy level as
compared to the conventional process. It can be surmised that using
a high level of manifold energy, as practiced conventionally,
results in a large proportion of it being wasted and only a little
being converted into enhancement energy. For example, the graph in
FIG. 18 shows that the air permeability results for treatment with
1.0 and 0.5 hp-hr/lb total energy delivered were similar, therefore
at least half of the total energy delivered at 1.0 hp-hr/lb was
wasted. Also, the air permeability results for the 0.25 hp-hr/lb
energy level at 24 passes is only slightly more than the air
permeability results for the 0.5 and 1.0 hp-hr/lb energy levels at
the same number of passes. Generally, the highest hydroenhancing
efficiency (least energy wasted) for comparable enhancement results
was obtained at lower manifold energies of 0.25 to 0.125 hp-hr/lb
(0.125 to 0.0625 hp-hr/lb per manifold) in 16 passes or higher.
[0082] A surprising result of the invention method was an
unexpected reduction in fabric shrinkage. A certain amount of
shrinkage is normally associated with fabric enhancement. It is
theorized that the blooming of the yarns under fluid impact causes
the paths of the fibers in the yarns to change, which in turn
causes the yarns overall to shrink. The graphs in FIGS. 19A and 19B
show the percent of warp (machine direction) and weft (cross
direction) shrinkage obtained versus the number of passes at
different levels of total delivered energy. The graphs show that
fabric shrinkage increases initially and reaches a peak at about 16
passes then decreases significantly. The reduction in shrinkage at
the higher numbers of passes may be due to straightening of the
fiber paths under repeated impacts. Shrinkage at a lower total
energy level of 0.125 hp-hr/lb was significantly lower overall than
at higher energy levels. Reduced shrinkage in the weft direction is
advantageous in that it requires less tentering after enhancing,
since tentering stretches the yarn and reduces the level of
bloom.
[0083] VI. Improved Coverage, Reduced Shrinkage, Elimination of
Moire
[0084] As a further aspect of the invention, it is found that
improvements in fabric coverage (measured in terms of lower air
permeability), reduced shrinkage, and elimination of interference
(moire) patterns are obtained by providing jet streams from a
manifold with a constantly fluctuating cross-sectional shape. It is
theorized that the situs of jet impact on the fabric results in the
movable fibers in that area being immediately displaced, but the
impact situs must be moved to a new position to make contact with
other movable fibers to make use of the subsequently delivered.
energy. Fluctuation or oscillation of the jet cross-sectional shape
constantly changes the situs of jet impact over more fibers so that
more of the manifold delivered energy is used as fabric enhancement
energy.
[0085] In accordance with this aspect of the invention, the
manifold in any of the systems described above can be modified to
produce jets of constantly fluctuating cross-sectional shape, in
order to distribute the delivered energy of the jets over a broader
impact area for improved enhancement results. Regular jet flow is
generally columnar and may have only slow fluctuations in shape
over time. Constant fluctuations in the cross-sectional shape of
the jets can be generated by placing a baffle 83 in the interior of
the flow module below the inlet holes and in close proximity to the
jet strip, as shown in FIG. 11, so as to induce turbulence which
causes fluctuations in the jet streams emitted from the manifold.
The baffle can have any type of design which is effective in
inducing turbulence to cause fluctuations in the jet streams. One
type of design is shown in FIG. 11 consisting of a metal plate bent
to form a rigid channel shape with a central constriction for the
flow of fluid from the inlet to the jet orifices.
[0086] The turbulence induced by the baffle in the fluid flow in
the manifold results in random disturbances to the jets emitted
from the jet orifices so that they form randomly spiralling ribbons
t oscillate in cross-sectional shape and direction. The spiralling
ribbons distribute their impact energies over constantly changing
impact areas on the fabric for improved enhancement and more
efficient utilization of enhancement energy. The baffle may be used
with conventional hydroenhancing equipment, as well as with the
improved equipment previously described. A more detailed
explanation of this feature is provided in commonly owned U.S.
patent application Ser. No. ______, entitled "Turbulence-Induced
Hydroenhancing for Improved Efficiency", filed simultaneously
herewith, which is incorporated herein by reference.
[0087] It is also found that fabrics enhanced with fluctuating jets
exhibit considerably less shrinkage than fabrics enhanced using
regular jet flow. Tests have shown that warp shrinkage can be
reduced from a high of 10% to about 2%, and weft shrinkage from
about 14% to about 6%. The reduction in shrinkage is found to occur
at all energy levels. The constant fluctuation of the jets improves
fabric enhancing even at low process speeds and a low number of
passes.
[0088] The constant fluctuation of the jets also substantially
reduces the generation of interference (moire) patterns in the
fabric. As indicated in FIG. 7, the regular spacing of jets aligned
with the machine direction can interfere with the regular spacing
of the warp yarns so as to generate repeating stripe patterns in
the fabric. With jets of fluctuating cross-sectional shape, the
impact area of the jets will be constantly moved over the yarn
spacings, so that interference patterns are reduced or eliminated.
As described previously, interference patterns can also be
eliminated by orienting the manifold at an angle to the fabric
travel direction.
[0089] Interference patterns can also be reduced by increasing the
density of the jets relative to the warp yarn spacing. For example,
interference patterns are produced by jets with a density of 40
jets/inch on a fabric having 60 warp-yarns/inch or more. The
interference patterns can be eliminated by using a high jet
density, e.g., 100-200 jets/inch. A jet density of 104 jets/inch
was found to eliminate interference patterns for fabrics with warp
yarn counts as fine as 98 ends/inch. For the higher jet densities,
e.g., 120 jets/inch or more, it may be more convenient to use a
double row of jets, i.e., two rows of 60 jets/inch, to avoid the
high tolerances or machining required.
[0090] Another technique to eliminate moire can employ a row of
orifices delivering fan jets to create a continuous water curtain,
instead of orifices delivering jets in columnar streams, the
manifold for example, as described in commonly-owned U.S. Pat. No.
4,995,151 of Siegel et al., issued on Feb. 26, 1991, entitled
"Apparatus and Method For Hydropatterning Fabric", incorporated
herein by reference.
[0091] The larger diameter of the fan jets and simpler structure
can further reduce equipment costs. The use of fan jets can avoid
the generation of interference patterns since the overlapping fan
jets tend to lessen or eliminate the tracing of lines on the
fabric.
[0092] Improved fabric coverage and elimination of interference
patterns can also be obtained by using a combined manifold
arrangement as shown in FIG. 17. With the fabric 12 moving in the
fabric travel direction (arrow) on the support surface 22, a
downstream manifold 30b having jets pointing straight downward on
the fabric is employed in combination with an upstream manifold 30a
having jets canted at an angle (bias) toward the fabric travel
direction. The straight water curtain impacts on the fabric holding
the yarns in place while the bias curtain impinges at an angle to
impact toward the impact zone of the downstream manifold for
greater blooming of the yarns in the fabric. A dense spacing of
jets or a double row of jets may also be used for eliminating
interference patterns. For example, a double row of jets of 60
jets/inch density and 0.005 inch jet diameter in the upstream
manifold canted at a 45.degree. angle toward the fabric travel
direction would have the effect of a jet density of 168 jets/inch
in a conventional manifold, yielding extraordinary coverage. The
manifolds may also be angled across the fabric width, as described
previously. The combined-manifold configuration results in better
coverage of the fabric and utilization of delivered energy. It may
be used with conventional hydroenhancing equipment, as well as with
the improved equipment previously described.
[0093] It is understood that many modifications and variations may
be devised given the above description of the principles of the
invention. It is intended that all such modifications and
variations be considered as within the spirit and scope of this
invention, as defined in the following claims.
* * * * *