Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
RAPID FABRIC FORMING
FIELD OF THE INVENTION
The invention teaches a process and apparatus to rapidly form a flat or
shaped fabric and the fabric formed therebv consisting of groups of varn
denselv
covering an area.
TECHNICAL BACKGROUND
Textile fabric is often formed from strands, or filaments, of yarn by
weaving or knitting or the like to hold the strands together. Processes of
weaving
and knitting where strands are guided over and under adjacent strands are slow
and do not permit much variety in forming fabric shapes. In a loom for weaving
fabrics, the weft yarns are added one at a time. These processes typically
result in
flat or cylindrical fabrics. There is a need for a process that, in addition
to making
flat or cylindrical fabrics, permits more variety in forming fabrics with
random
three dimensional shapes, for instance, that would permit forining an article
of
clothing, such as a shirt, without having to cut pieces of fabric and seam
them
together. The cutting of fabric into irregularly shaped patterns wastes a lot
of
fabric, plus cutting and sewing add steps over forming the fabric article
directly.
The same problem is present in making flexible engineered shapes such as
automotive air bags, sail boat sails, industrial filter bags, or the like. In
these
cases, the need for seams to form three dimensional shapes presents problems
with
structural strength and/or permeability so the seams must be carefully made.
There is a need for a way to rapidly form a flexible fabric from strands of
yam; there is a need for a way to rapidly form a three dimensional, flexible,
fabric
article without cutting a flat fabric and seaming.
There is also a problem making complex shapes for composite structures
that may be impregnated with a hardenable resin. It is sometimes desired to
lay
down the filaments in a three dimensional shape before adding the resin or
during
resin addition. Present means for doing so involve complex forms with
retractable
support means to hold the filaments in place before the resin hardens. There
is a
need for a simpler way to preform these fabric shapes without seams. Such
seams
would compromise the strength of the composite structure.
A series of Oswald patents (U.S. 4,600,456; U.S. 4,830,781; and
U.S. 4,838,966) lay down a pattetn of partially vulcanized rubber coated
strips, or
cords, to make a loop of preformed reinforcing belt for a vehicle tire. The
strips
or cords are stuck together wherever they touch to make a relatively stiff
structure.
The cords are laid in a "zig-zag repeating pattern with succeeding lengths of
the
strips being displaced from each other. The cord lengths are interleaved with
lengths of cords disposed at an opposite angle... This interleaving
relationship
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results in a woven structure". The stickiness of the partially vulcanized
rubber
apparently holds the cords in place to a forming surface and to each other
until the
belt is assembled with other elements of the tire and molded under heat and
pressure to form a completed tire.
The process practiced by Oswald and others uses one or a few cords that
are traversed back and forth across the belt numerous times to complete one
circumference. This is believed to result in a multilayered structure where
the
cords in any one layer are sparsely arrayed, but they do not completely cover
the
belt area. It is only after repeated zig-zag passes over the belt area that
the area
becomes sparsely covered with cord. Due to the repeated zig-zag passes of only
a
few cords, it is believed that within any one layer there are cords layed down
in
two different directions that do not cross one another. Cords that cross one
another would be in different layers. These structural features of the
reinforcing
belts are symptomatic of a process that lays down only a few cords at a time
and
must make repeated passes over the belt area to get coverage of the area.
There is
a need for a simple non-weaving process that can make fabric structures by
laying
down many yams simultaneously over a fabric area to sparsely cover it rapidly,
and to stack several of such sparse yarn coverages to densely cover the area.
SUMMARY OF THE INVENTION
The invention concerns a fabric product and its variations, processes for
making the product and variations on such processes and several forms of
automated devices for making preferred forms of the product. Included in the
invention are the following embodiments:
A fabric structure comprising:
a plurality of groups of yarn densely covering an area and the yarns
within one group following substantially parallel paths (defined to include
loops
in a yam path) and the yarns in one group arranged to cross yams in another
group;
a plurality of subgroups comprising each group, each subgroup
comprising a plurality of yams sparsely covering said area, and the yarns in
one
subgroup of one group offset from the yarns in the other subgroups in said one
group;
a plurality of connections between the top subgroup of the structure
and the bottom subgroup of the structure either directly or through the yarns
in
other subgroups.
In other embodiments, there are unconnected regions separate from the
connections and the inherent flexibility of the yams in the structure is
retained in
the unconnected regions.
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In other embodiments, the connections are spaced apart bonded regions
and there are unbonded regions separate from the bonded regions and the
inherent
flexibility of the yarns is retained in the unbonded regions.
In further embodiments, the yams in a subgroup follow substantially
parallel paths that cause each of the yarns to cross itself within a subgroup
and to
cross its neighbors within a group.
In other embodiments, the yarns in a subgroup of one group are folded
over to become the yarns in a subgroup of another group and thereby to cross
them.
In other embodiments, a film or nonwoven sheet is placed between two
adjacent subgroups within the structure.
In other embodiments, there are three groups of yam employed in the
fabric structure to make a stacked triaxial fabric structure.
Also claimed herein is a method of forming such an interlaced structure
comprising:
laying down a first yarn subgroup having a plurality of yams
oriented in a first angular direction free of crossings, the yarns in the
first
subgroup following substantially parallel paths that are spaced apart in a
repeating
pattern to sparsely cover a predetermined fabric area;
stacking a second yarn subgroup next to the first yarn subgroup, the
second yam subgroup having a plurality of yarns oriented in a second angular
direction free of crossings, the yarns in the second subgroup following
substantially parallel paths that are spaced apart in a repeating pattern to
sparsely
cover the predetermined fabric area;
continuing alternately stacking a plurality of first yarn subgroups and
a plurality of second yam subgroups comprising the substeps of:
offsetting the plurality of yams in any one subgroup of the
plurality of first subgroups from the plurality of yarns in all other
subgroups of the
first plurality of subgroups, and laying down all the yams in one of the first
plurality of subgroups before laying down the yams in another subgroup;
offsetting the plurality of yams in any one subgroup of the
plurality of second subgroups from the plurality of yams in all other
subgroups of
the second plurality of subgroups and laying down all the yarns in one of the
second plurality of subgroups before laying down the yarns in another
subgroup;
stopping the stacking when all of the plurality of first subgroups
form a first yarn group comprising yams that densely cover the predetermined
fabric area, and when the stacking of all of the plurality of second subgroups
form
a second yarn group comprising yarns that densely cover the predetenmined
fabric
area; and
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connecting the yarns in the top subgroup in the stack to the yarns
in the bottom subgroup in the stack to thereby contain the other subgroups in
the
stack and form an interlaced fabric structure.
The method as above further comprising: urging the stacked subgroup
of each group to nest together into a consolidated structure where the yams in
one
group bend over the yams in the adjacent groups.
The method as above wherein the connecting step comprises bonding
said subgroups at spaced regions and providing unbonded regions separate from
the bonded regions wherein the inherent flexibility of the yarns is retained
in the
unbonded regions.
Connecting the outermost subgroups may also include connecting strands
from the innermost subgroups. The connecting means may consist of loops of
yarn, spots of adhesive, bonded joints (such as those formed by squeezing the
outermost groups together and applying ultrasonic energy to the squeezed
yams),
staples and clips.
The invention is also a three dimensional shaped product and a process of
rapidly forming a three dimensional shaped fabric where the yarns in the
subgroups are not necessarily generally parallel, but are regularly spaced to
follow
the contours of the shape. The three dimensional, shaped, interlaced, fabric
structure, comprises:
a stack of a first plurality of subgroups, a second plurality of
subgroups, and a third plurality of subgroups, each subgroup having yams
spaced
apart to define a sparse covering of a fabric area, the yams generally
parallel, and
the yams following a curved path in space;
the stacked subgroups arranged in a predetermined array with
reference to a common axis and a common reference plane perpendicular to said
axis;
the first subgroups arranged at a first angle with respect to said
reference plane and positioned at a first rotational angle about said axis,
the
second subgroups arranged at a second angle with respect to said reference
plane
and positioned at a second rotational angle about said axis, the third
subgroups
arranged at a first angle with respect to said reference plane and positioned
at a
third rotational angle about said axis, wherein the yams in any one of the
first,
second and third subgroups cross the yarns in another of the first, second and
third
subgroups; within each first, second and third plurality of subgroups, the
yarns of
one subgroup are offset from the yams of the other subgroups to thereby form a
group of yams for each of the respective subgroups, the group for any
respective
subgroups densely covering a fabric area;
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the top subgroup in the stack is connected to the bottom subgroup in
the stack to thereby form a three-dimensional, shaped interlaced, fabric
structure.
Further taught herein is a fabric forming device for forming a fabric
structure from a plurality of yarns, comprising:
(a) an endless loop conveyor having a traveling support surface for
supporting the fabric structure being formed, the surface having opposed edges
parallel to the direction of travel and holders along each edge to temporarily
hold
the yarn to resist lateral motion of the yarn, the conveyor having a
controllable
motor for propelling the traveling support;
(b) a plurality of guide bars adapted for movement across the
surface from edge to edge, each bar containing a plurality of guides for
repeatedly
guiding a plurality of yarns from the holders along one edge to the holders
along
the opposed edge and back to the one edge, the guide bars having a
controllable
actuator for propelling the bars back and forth across the support surface;
(c) a plurality of bonders arranged across the support surface
between the support surface edges and beyond the last guide bar in the
direction of
travel of the surface, the bonders adapted to bond one yarn to another yam
where
they cross;
(d) a controller for coordinating the controllable motor; and
actuators to continuously form a fabric structure on the support surface of
the
conveyor.
A further embodiment is a yarn dispensing device for laying down yarn
accurately on a compound curvature, when using a mechanical actuator,
comprising the following elements:
(a) a mechanical guide actuating means;
(b) a yarn guide comprising a frame that supports a hollow shaft
through which yarn can pass;
(c) a slide, attached to the yarn guide, and also attached to the
guide actuating means;
(d) a block mounted on said hollow shaft which supports a
plurality of flexible springs that intersect at a common point;
(e) at the point of intersection of the springs is a hollow tip with a
hemispherical end through which the yarn can pass, said springs permitting
motion of the tip in an axial or angular direction, the rotation of said shaft
allowing the tip to roll over any surface it contacts while it is also free to
deflect
axially and angularly, so as to accurately place a yarn on the surface while
the
yarn passes through a hole in the hollow shaft and a hole in the hollow tip.
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BRIEF DESCRIPTION OF THE FIGURES
Figures I A-E show plan views of a progression of yarn laydown to form a
basic two group (two-directional or biaxial) flexible fabric from a plurality
of
multiple-yam subgroups.
Figures 2A-E show plan and side views of the yarn subgroups of basic
cells of the fabric.
Figures 3A-C show plan and elevation views of variations in yarn
arrangement in a cell.
Figures 4A-D show plan views of additional biaxial fabric structures.
:10 Figures 5A-B show two different plan views of a three group (three-
directional or triaxial) flexible fabric.
Figure 6 shows an apparatus for continuously forming a two dimensional
biaxial yam fabric with the yarns oriented at an acute angle to the machine
direction, and a fabric thus formed.
115 Figure 7 is an enlarged view of a portion of the. fabric of Figure 6.
Figures 8A-B show another apparatus for continuously forming a two
dimensional biaxial yarn fabric similar to that of Figure 7.
Figure 9 is an enlarged view of a portion of a fabric formed by the
apparatus of.Figure 8.
Figures 10A-B show a table apparatus for making a single batch of two
dimensional or three dimensional fabric structure and a sample of a piece of
three
dimensional biaxial fabric structure.
Figure 11 A shows a mandrel apparatus for making a single batch of two-
dimensional or three dimensional fabric structure.
Figure 11 B shows a mandrel apparatus for making a tubular batch of fabric
structure.
Figure 1 I C shows a flattened view of a tubular fabric structure made on
the apparatus of Figure 11B.
Figure 11 D shows a special device for laying down yam.
Figure.12 shows another mandrel apparatus for making a single batch of
three dimensional fabric structure.
Figure 13 shows another apparatus for continuously forming a two
dimensional biaxial fabric structure with the yarns.oriented at 0 degrees and
90 degrees to the machine direction.
Figure 14 shows a diagrammatic view of a cell of fabric.
Figure 15 shows a generalized yam dispensing svstem for a shaped
mandrel.
Figures 16A-16D show the general orientation of.a single subgroup of a
single group onto the shape of Figure 15.
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Figures 17A-17D show the orientation of a single subgroup of three
groups onto the shape of Figure 15.
Figures 18A-18E show the orientation of successive subgroups of each
group being deposited to densely cover the shape of Figure 15 and form the
shaped fabric.
Figures 19A-19E show a system for making a shirt fabric.
Figure 20 shows a special device for laying down yarn on mandrels with
compound curves.
DETAILED DESCRIPTION
Figures 1 A-E show a simplified basic structure and process for forming a
two-directional or biaxial yarn fabric 22 (Figure 1 E) of the invention on a
planar
surface 23. In Figure lA, two yarns 30 and 32 are laid down in a first
direction,
such as a ninety degree direction 34. Yarns 30 and 32 are spaced apart a cell
distance, or space, 33 which may be about 3-20 yarn diameters (preferably 4-
16,
and most preferably 4-8); about four diameters are shown here to provide 4
positions for yarns to be laid down spaced from, or offset from, the other
yarns in
that direction. In Figure 1B, two yarns 36 and 38 are laid down in a second
direction, such as a zero degree direction 40, and on top of the first yarns.
Yarns
36 and 38 are also spaced apart a cell distance, or space, 42 which is the
same
magnitude as cell distance 33 for these yarns of the same width. For yarns of
different widths or for special effects, cell distances 33 and 42 may be
different.
In Figure 1 C, two yarns 44 and 46 are spaced apart at distance 33 and in
direction
34, and are placed adjacent yarns 30 and 32 respectively, and on top of yams
36
and 38. Two yarns 48 and 50 are then spaced apart at distance 42 and in
direction
40, and are placed adjacent yarns 36 and 38 respectively, and on top of yams
44
and 46. In Figure 1D, two yarns 52 and 54 are spaced apart at distance 33 and
in
direction 34, and are placed adjacent yarns 44 and 46 respectively, and on top
of
yarns 48 and 50. Two yarns 56 and 58 are then spaced apart at distance 42 and
in
direction 40, and are placed adjacent yarns 48 and 50 respectively, and on top
of
yarns 52 and 54. In Figure 1 E, two yarns 60 and 62 are spaced apart at
distance
33 and in direction 34, and are placed adjacent yarns 52 and 54 respectively,
and
on top of yams 56 and 58. Two yarns 64 and 66 are then spaced apart at
distance
42 and in direction 40, and are placed adjacent yarns 56 and 58 respectively,
and
on top of yarns 60 and 62.
This completes the yarn lay-down and a basic planar fabric structure 22
has been created of a plurality of yatns that are held in place now only by
friction
and gravity. It remains to secure the yams in place. This is done in the
simplest
manner by attaching the top yarns 64 and 66 to the bottom yarns 30 and 32
where
they cross at points 68, 70, 72, and 74. This now traps all the yarns in the
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structure together so they can not be removed in the manner in which they were
assembled.
The structure shown in Figure l E is also shown in Figure 2A expanded
slightly and the ends of the yarns extended for purposes of further
discussion. The
structure as illustrated in Figure 2A has a characteristic structure, or cell
61, that
would be repeated in a large area of the fabric; it is shown outlined by heavy
dashed lines. There is a crossing point between the uppermost yarns and
lowermost yarns in each cell of this structure, such as point 68 in cell 61
where an
uppermost yarn 66 crosses a lowermost yam 32.
Figure 2B shows a side elevation view 2B-2B of fabric 22 in Figure 2A
where the yams are shown as rigid elements. It will be appreciated that since
the
yams are flexible, if untensioned they will bend over and under one another in
the
structure and collapse to about a two-to-four yam thickness so it will be
difficult
to pull unbonded yarns from the structure. This over and under path of a yarn
in a
structure is referred to in the fabric art as interlace. The more interlace
that is
present, the more the fabric is stable and the yams tend to stay in place
without
shifting and opening up holes in the fabric. That is, the fabric has good
integrity.
This is a desirable feature for maintaining the covering ability of the fabric
over an
area. A representation of a fully collapsed structure is depicted in Figure 2C
where the individual yarns in each subgroup 1-8 are identified. The fully
collapsed thickness at 57 is about the thickness of an individual yam of one
group
in one direction, 34, stacked on top of an individual yam of the other group
in the
other direction, 40. This fully consolidated thickness is about two yarn
diameters
thick which may be achieved by urging the yarns together with an increased
amount of bonding. By controlling the bonding to be the minimum as shown in
Figure 2A, the fabric structure may be much bulkier and achieve a thickness 59
of
3-4 yarn diameters. This is 1'/z-2 times bulkier than if the same yarn were
used in
a woven structure. Alternatively, a less expensive, lower bulk yam with less
texture and/or crimp could be used in the structure of the invention to
achieve the
same bulky fabric as a woven structure using a more expensive high-bulk yarn.
This is a unique advantage of the fabric of the invention.
It is useful to develop some special definitions to discuss the general
features of the invention referring to Figures I E, 2A and 2B:
yarn - a predominantly one dimensional, elongated, flexible, fabric
element essentially continuous in length such as a strand, fiber, filament,
wire,
rope, tape, ribbon, tow, thread, tube, string, or the like made up of one or
more
subelements that may be continuous in length (such as a continuous multi-
filament yam) or discontinuous in length (such as a staple yarn).
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cell - a cell is the smallest section of a fabric where the yarn pattern -
appears to repeat over most of the fabric structure, and where, for
convenience, the
topmost varn, such as yarn 66, lies along one side of the cell and the next
topmost
yarn, such as yarn 60, lies along the other side of the cell (other repeating
units of
the cell could be chosen if desired). In Figure 2A. a complete cell is shown
as cell
61. In some structures, the edges of the fabric mav only have partial cells,
or there
may be several cells in a fabric with slightly different yarn laydown patterns
that
will repeat in the fabric. In some fabrics, there may be highly variable or
very
large cell repeats and it may not be useful to designate a cell; the entire
fabric may
be referred to as a cell.
group of yam - a group of yarn comprises all the yarns in a fabric
or cell in a given direction, such as a zero degree direction or a ninety
degree
direction. In Figure 2A, the zero degree yarn group for all cells is
designated by
the Roman numeral I, and the ninety degree yam group for all cells is
designated
15, by the Roman numeral II. The yams in a group fotm a dense covering of yarn
over an area and the yams in a group follow substantially parallel paths which
may include curved paths or looped paths where a given yarn may cross itself.
To
achieve the most dense covering, the yams would all be non-intersecting and
preferably parallel; for less dense covering, this is not necessary.
cell space - the cell space is the length of the side of a cell that
determines the space available for the number of non-intersecting, non-
overlapping yams in a group. For simple repeating cells, this dimension
defines
the yam spacing between sparsely spaced yams in a subgroup (see below). For
group II, the cell space is shown at 33; for group I, the cell space is shown
at 42.
Within the cell space 33 or 42 shown in Figures 1 A, I B, and 2A, there are
four
positions for the yarns in that group that are offset from one another. For
the cell
shown in Figure 2A identified using the conventions developed, the cell space
33
is seen between the top yarns 64 and 66.
subgroup of yarn - a subgroup is a plurality of yams making up a
sparce subdivision of a group. The yams in a group are stacked in subgroups
with
yarns of other groups. In Figures 2A, 2B and 2C the total of eight subgroups
'for a
complete cell are labeled 1-8 shown at different levels of the stack
in Fig. 2(b), with all the yarns in a subgroup given the same
number; subgroups 1, 3, 5, 7 make up group I for cell 61 and subgroups 2, 4,
6, 8
make up group II for cell 61. Each subgroup considered by itself is a sparse
covering of yarns over the fabric area. For instance, the yarns labeled I make
up
subgroup I and they are spaced apart at cell spacing 33. The yams labeled I
comprise the lowermost_subgroup of group I and also the cell, and they are
stacked against the yams labeled 2 in the lowermost subgroup of group II in
the
cell. The yams in the different subgroups in group I are non-intersecting,
that is,
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in a plan view they do not lay on top of one another. although in special
cases
involving yarn loops, an individual yarn in a subgroup may cross itself and
other
subgroup yarns as in Figure 2E.
yam position - the yarn position in a given group refers to the
location in a cell where a yarn is placed relative to a preselected reference
yarn in
the same group. Within the distance of a cell space. there are a finite number
of
yarn positions available for the yams in the subgroup of a group that are
substantially parallel and offset from one another. In a preferred convention,
an
X-axis is placed over an uppermost yarn in the cell and a Y-axis is placed
through
an origin defined by the intersection of the uppermost yarn and a yam in the
next
subgroup that crosses the uppermost yarn. For the sake of convention, the cell
would be defined as the repeating unit of yarn structure that has one edge
adjacent
the X-axis and the X-Y origin in the lower left corner of the cell. The yarn
position for a subgroup can then be defined as the fraction of the total
number of
possible yarn positions spaced from the reference yarn, with the reference
yarn
being in the zero-th position. If the paths of the yams are not straight,
unlike the
example of Figures lA-E and 2A, the X-axis would align with the predominant
non-straight path which may be the axis of symmetry of the yarn path, in the
case
of a sinusoidal or zigzag path. In cell 61 of Figure 2A, the uppermost yarn 66
in
subgroup 8 of group II is selected as the reference yarn and is coincident
with an
X-axis 71. The yarn 60 in the next subgroup 7 of the cell 61 crosses the
reference
yarn 66 in subgroup 8. Where it crosses reference yarn 66 defines an origin 75
through which a Y-axis 77 passes. The subgroup positions of the group I yams
within the cell 61 are labeled 0/4, 1/4, 2/4, 3/4 with subgroup 8, represented
by the
uppermost yarn 66, in the 0/4 position and the sign determined by the
direction of
the Y-coordinate where the yarn crosses the Y-axis. The subgroup positions of
the group II yams within the cell 61 are labeled 0/4, 1/4, 2/4, 3/4, with
subgroup 7,
represented by the next yarn 60, in the 0/4 position and the sign determined
by the
direction of the X-coordinate where the yarn crosses the X-axis. Referring to
Figures 2A and 2B, the yarns in subgroup I of group II, such as yarn 32, are
in the
1/4 position in the cell shown, which is the +1 location of 4 possible
positions.
Referring to Figures 2A and 2D, the yarns in subgroup 6 of group I, such as
yarn
56, are in position 3/4 in the cell shown, which is the +3 location of 4
possible
positions.
A matrix can be created to describe the arrangement of yams in a cell of a
structure. For instance, for the fabric illustrated in Figures 2A, 2B, and 2C,
the
matrix for the two groups of yams, 0 and 90, would look like the following:
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no of pos. subgroup 3rd group other group
for subgroup offset shift from shift from
jyCoup/direction subgroup yams position orig. orig.
11/0 top 8 4 0/4 n/a . n/a
1/90 next 7 -t 0/4
11/0 6 4 3/4
1/90 54 3/4
i1J0 4 4 2/4
1/90 3 4 2/4
II/0 2' 4 114
1/90 1 4 1 /4
In Figure lE, four yarns are used to fill space 33: yarn 30, 44, 52, and 60.
From a practical standpoint, the size of each space 33 and 40 determines the -
length of unsecured yam on the top,and bottom surfaces of the fabric
structure,
such as length 76 in the zero degree uppermost yarn 64, and length 78 in the
ninety degree Iowermost yarn 30 in Figure IE. As this space increases when
more
subgroups of yarns are added to the structure, the unsecured yam length grows
and may present a snagging problem in the finished fabric structure. On the
other
hand, it may be desirable to have such an unsecured yarn on the surface of the
fabric for some applications. In satin fabrics made by conventional weaving
processes, there are many long segments of unsecured yam on the surface of
such
a fabric to create a special style and hand. When it is desired to minimize
the
length of unsecured yam on the surface of the fabric, however, four to eight
yarn
diameters is the preferred determinant for space 33 and 40 and the number of
subgroups. Sixteen to twenty yarn diameters is probably a maximum cell space
from a practical standpoint. If a thicker structure is acceptable or desired,
two
complete fabric structures can be assembled one on top of the other and then
the
outer subgroups connected so the number of subgroups is increased without
increasing the unsecured yam length on the fabric surface.
There are various patterns possible for laying down tlie subgroups of yarn.
All yarns in one subgroup are in place before the succeeding subgroup is put
in
place, which characterizes the yarns in a subgroup. Figure 2A shows the basic
module of fabric structure shown in Figure 1 E where the sequence of subgroup
placement going from left to right is 1-3-5-7 in each ninety degree group and
going from bottom to top of the figure is 2-4-6-8 in each zero degree group.
In
Figure 3A, the sequence of subgroup placement going from left to right is 1-5-
7-3
in each ninety degree group; the sequence of subgroup placement going from
bottom to top of the.figure is 2-6-8-4 in eachzero.degree group...Figure 3B is
an
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elevation view 3B-3B of Figure 3A and shows the position of the subgroups in
cell 79 in Figure 3A. Figure 3C shows another pattern where the ninety degree
yarns were shifted as in Figure 2A (1-3-5-7) and the zero degree yams were
shifted as in Figure 3A (2-6-8-4). As can be seen. various patterns of yarn
shifts
in each subgroup are possible to vary yarn patterns or structural features as
desired, and the zero degree and ninety degree subgroups may be shifted
differently. Another variation is shown in Figure 4A where the yarns in
succeeding subgroups are placed in the middle of the cell space remaining to
produce a different looking pattern of yarns. In general, the placement in
Figure 4A is less preferred; rather it is preferred to place the yarns in
succeeding
subgroups adjacent a yarn in a preceding subgroup. This results in improved
accuracy of yarn placement and restraint of yam movement in the direction of
the
adjacent yarn during buildup of the structure before bonding. Figure 4B shows
still another pattern.
The actual steps followed by a yarn placement device for sequentially
placing the subgroups may also be varied further as desired. For instance,
referring to Figure 2A and the ninety degree group, a device may step through
the
numerical sequence 1, 3, 5, 7 as seen in brackets 63, or 65, or 67, or 69; the
zero
degree group may be varied similarly. The steps followed will not affect the
appearance and structure of the pattern in the mid-section of the fabric
structure,
but may be used to determine the appearance along the edge of the fabric.
Means of connecting the top and bottom yarns are possible other than by
connecting only the points of overlap. In one preferred embodiment, an
ultrasonic
horn is traversed across the structure diagonally in a path 51, such as
through
point 68 and point 74 (Figure 1 E), to continuously bond all the yarns in the
path to
their overlapping neighbors. A parallel path 53 would run through point 70 and
another parallel path 55 would run through point 72 so a plurality of
ultrasonically
bonded pathways would exist to hold the structure together. Alternatively, the
bond pathways could run from point 68 to 70 or 68 to 72. In practice, the
paths
would not have to pass directly through points 68, 70, 72 and 74 to
effectively trap
the yarns in the structure. What is important is that the top yarns and bottom
yarns are connected to other yarns that are eventually connected to one
another, so
the top yarns are eventually connected by a series of connections to the
bottom
yarn. This "pathway process" of connecting is beneficial in that precise
location
of the bonds at the top and bottom yarn overlap points is not required,
although it
is still preferred. Such a spacing of paths as just discussed results in a
bonding
frequency that is low enough to retain the inherent flexibility of the yams in
the
structure in spite of the high frequency of molten polymer fused bonds. The
bond
pathways form a bonded region in the fabric structure and can be used to
control
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CA 02267790 2005-06-20
the fabric bulk. Between the bond pathways, such as paths 51 and 55 there is
an
unbonded region 49 where the yarns remain unbonded and unconnected so the
inlierent flexibility of the yatn used in the structure is retained. It will
be
appreciated that to make a fabric structure of a practical size, a great many
vams
would be used and many bonded regions and unbonded regions would be
employed.
Figure 4C shows a small area of a portion of a fabric with a pattem that
resembles that in Figure I E (also 2A). The small area fabric portion 22 shown
in
Figure 1 E/2A, referred to as a simple cell/single step pattern (or just the
simple
cell pattern), can be made with four passes of two yarns in each group, such
as
four passes of two feed yatns 30 and 32 in the ninety degree direction;
alternated
with four passes of two feed yarns 36 and 38 in the zero degree direction. In
each
subgroup the succeeding yams are placed next to the previous yarns at a single
yarn step away. This fabric could be rapidly made in this manner. An
equivalent
=15 fabric portion 24 shown in Figure 4C was made with eight passes of only a
single
feed yarn in each group, such as eight passes of feed yam 41 in the ninety
degree
direction alternated with eight passes of feed yam 43 in the zero degree
direction.
If the numbered sequence shown at 45a is followed for the ninety degree feed
yarn
41, and the numbered sequence shown at 45b is followed for the zero degree
feed
yam 43, a pattern very similar to that in Figure IE/2A is produced. The
pattern in
the fabric portion made as in Figure 1 E/2A shows four cells of fabric with
four
yarns per cell side, and the pattern in the fabric portion made as in Figure
4C
shows one cell of fabric with eight yarns per cell side. Some visual
differences in
the fabric can be observed looking at the lower right quadrant of the two
fabrics
where it is seen that in Figure 2A (same as 1 E), subgroup 5 passes under
subgroup
6, and subgroup 7 passes under subgroup 8; but in the equivalent fabric in
Figure 4C, subgroup 11 passes over subgroup 1-0 and subgroup 15 passes over
subgroup 14.
This pattern in Figure 4C is referred to as the split cell/single step pattern
(or
just the split ceI1 pattern) since the second.yarn layed down in each group of
yarns,
41a and 43a, splits the cell distance, such as distance 47, into some cell
fraction,
such as 1/2 cell, as shown by the equal split cell distances 47a and 47b. The
succeeding yarns in each group, such as yarns 41 b and 43b, are then layed
down
_ . . . _. , next to previous yams, such as yarns 41 and 43 respectively, at a
single yarrt step
away in the first split cell distances, such-as 47a. Also succeeding yarns in
each
group, such as yarns 41c and 43c, are then layed down next to previous yams,
such as yarns 41a and 43a respectively, at a single yam step away in the
second
split cell distances, such as 47b. In this way, the two or more split cell
fractions
are built up together. When the cell is completed, the top and bottom yam
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intersection is bonded as at 73. Additional bond lines similar to those shown
at
51, 53, and 55 in Figure I E could also be utilized to bond more of the yarns
to
each other, as shown at 73a, 73b, and 73c in Figure 4C. More or fewer bond
iines
may be utilized as desired. For the simple cell/single step pattern and split
cell/single step pattern, and any other similar pattern which produces good
yarn
interlace, it may be possible to use fewer than the suggested one bond per
cell
over a large fabric pattern that has many cells and bonds.
Figure 4D shows, for comparison, a fabric 26 made using the simple cell
pattern as in Figure I E/2A but using eight yarns per cell distance instead of
only
four. Only a single feed yarn for each group of yarns would be needed for the
area
of fabric shown in this single cell. The numbered sequence shown at 27a is
followed for the ninety degree feed yam 25, alternating with the numbered
sequence shown at 27b which is followed for the zero degree feed yarn 28. This
single cell pattern covers the same area as the four cell area of Figure 1E/2A
or the
single cell area Figure 4C, but it has a large number of long unsecured yarn
lengths which may be undesirable for some applications. When placing down a
large number of yams per cell (8 or greater), it is preferred to use the split
cell
pattern to minimize the number of long unsupported yarn lengths.
It has been found that the pattern of yams illustrated in Figure 1 E/2A and
4C provide particularly good interlacing of yarns so the fabric structures
tend to
hold their shapes better without yams shifting and holes opening up in the
fabric.
There are some significant differences in the two yam laydown patterns,
however.
The simple cell of Figure 1E/2A utilizes more feed yams per inch of fabric
than
the split cell of Figure 4C, and if the practice of providing at least one
bond per
cell is followed, more bonds would be used per area of fabric. The use of more
feed yams may require a larger yarn creel and more yarn guides as will be
appreciated when various apparatuses will be discussed below. This use of more
feed yarn per inch, however, results in more rapid fabric development using
the
simple cell pattern. The split cell pattern, on the other hand, provides the
same
good interlacing of yams as the simple cell pattern and offers more
flexibility in
forming different yarn structures with any given apparatus at the tradeoff of
fabric
forming time. In general terms, the fabric structure of the invention is an
interlaced fabric structure comprising:
- a plurality of first yam subgroups having a plurality of yarns
oriented in a first angular direction free of crossings, the first yarn
subgroups
forming a stack with a plurality of second yarn subgroups having a plurality
of
yams oriented in a second angular direction free of crossings;
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- the yarns in each subgroup following substantially parallel paths
that are spaced apart in a repeating pattern to sparsely cover a common
predetermined fabric area;
- the yarn subgroups are alternately stacked with a first subgroup
next to a second subgroup. wherein the yams in the first subgroup cross the
yams
in the second subgroup;
- the yarns in any one subgroup of the plurality of first subgroups are
offset from the yarns in all other subgroups of the first plurality of
subgroups;
- the yams in any one subgroup of the plurality of second subgroups
are offset from the yarns in all other subgroups of the second plurality of
subgroups;
- the stacking of all of the plurality of first subgroups forming a first
yarn group comprising yarns that densely cover the predetermined fabric area,
and
the stacking of all of the plurality of second subgroups forming a second yam
group comprising yarns that densely cover the predetermined fabric area; and
- the yarns in the top subgroup in the stack, are connected to the
yarns in the bottom subgroup in the stack, to thereby contain the other
subgroups
in the stack in an interlaced fabric structure.
In the case of the simple cell, single step pattern, the interlaced fabric
structure also includes:
- the yanns in successive ones of the plurality of first subgroups in
the stack are offset from each other by the width of a yarn in that subgroup
of the
fabric; and
- the yarns in successive ones of the plurality of second subgroups in
the stack are offset from each other by the width of a yarn in that subgroup
of the
fabric.
In the case of the split cell pattern, the interlaced fabric structure also
includes:
- the plurality of first subgroups are arranged in the stack to define a
total number of offset yarn steps equal to the number of subgroups making up
the
plurality of first subgroups (the distance of such a yarn step is equivalent
to the
yarn diameter of a yam in the subgroup as it appears in the fabric), and
wherein
successive ones of the plurality of first yarn subgroups are placed at a
plurality of
equal subintervals of yam steps from each other;
- and subsequent ones of the plurality of first yarn subgroups are
progressively placed in the subintervals with the plurality of yarns in
successive
ones of the plurality of first subgroups being offset one yam step from each
other;
- the plurality of second subgroups are arranged in the stack to define
a total number of offset yarn steps equal to the number of subgroups making up
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the plurality of second subgroups, and wherein successive ones of the
plurality of
second yarn subgroups in the stack are placed at a plurality of equal
subintervals
of yarn steps from each other;
- and subsequent ones of the plurality of second yarn subgroups in
the stack are progressively placed in the subintervals with the plurality of
yarns in
successive ones of the plurality of second subgroups being offset one yarn
step
from each other.
The connection means for fabrics of the invention may be by ultrasonic
bonding as discussed if the yarns are a thermoplastic polymer and the top and
bottom yams are compatible polymers that will bond together by fusion. The
connection (or bonding) means may also be a hot melt adhesive, a solvent that
softens the yarn polymer and permits the yarns to fuse together, a room
temperature curing adhesive, a solvent based adhesive or other impregnating
type,
a mechanical fastener such as a staple, strap, or tie, or other such means.
In the case of a bonded connection, all of the yams in the structure do not
need to be thermoplastic yarns to act as binder yarns. The binder yarns
necessary
to provide the sticky polymer, partially dissolved polymer, molten polymer, or
the
like to act as an adhesive, or binder, for the bond may be distributed
throughout
the structure in a variety of ways. A binder yarn is a yarn that would
mechanically
or adhesively engage another binder yarn or a non-binder yarn during bonding.
A
non-binder yarn is one that would not mechanically or adhesively engage
another
non-binder yarn during bonding. In a simple case, some or all of the yarns for
the
structure can be made from non-binder fibers which are covered with binder
fibers
by twisting or wrapping. An example of such a wrapped yam is a yarn with a
multifilament non-thermoplastic core which is wrapped with a multifilament
sheath that contains some or all thermoplastic filaments. The sheath can be
continuous filaments or staple fibers. In the case of staple fibers, the
sheath can be
a blend of binder and non-binder fibers, such as thermoplastic nylon staple
fibers
and non-thermoplastic aramid or cotton staple filaments. Such a yarn
construction
can be made using a "DREF 3 friction spinning machine" available from
Textilmachinenfabrik Dr. Ernst Fehrer AG of Linz, Austria. A blend of 5-25% by
weight thermoplastic binder fibers in the sheath may work well for this
application. Other binder and non-binder polymers may be used for the fibers
in
the yam as desired. When bonding using such a sheath/core yarn, it is to be
expected that the sheath filaments would be affected by the bonding process
while
the core filaments would not. The core filaments could be relied on to carry
the
load in the structure after bonding. In some cases, it may be desirable to
form
bonds at all yarn crossings to form a stiff board-like fabric structure. This
may be
16
CA 02267790 2005-06-20
accomplished by heating and urging together all the binder fiber in the
structure so
essentially all the yarns are bonded together..
Another way to distribute binder adhesive material to bond the structure
together is to provide.binder yarn for one or more upper subgroups of. for
instance. the zero degree group of yarns: and for one or more bottom subgroups
of, for instance, the ninety degree group of yarns. These top and bottom varns
may be the sheath/core yarns described above. Another way to distribute binder
material is to use a binder containing yam for some fraction of each subgroup
of,
for instance, zero and ninety degree yams, such as every other or every tenth
yam
in each subgroup. One structure that has been found to work well is to make
the
top and next subgroups of yarns and the bottom and next subgroups of yarns
with
binder fibers. During bonding, the top and next subgroup, and bottom and next
subgroup binder yarns are adhesively joined and other non-binder yarns may be
mechanically engaged, such as_ by embedding; enveloping, encapsulating, or
the.
like. This additional engagement of non-binder fibers results in load paths
extending from the top to the bottom subgroups of yarn even where the top and
bottom subgroups don't directly contact each other.
When using a distribution of binder fiber in the structure of the invention,
it has been found that a distribution of about 5%-60% binder fiber by total
fiber
weight is useful, and preferably a distribution of about 10%-20% by total
fiber,
weight works well to provide good fabric integrity while retaining good fabric
softness (minimize fabric stiffness and boardiness). In some cases, it may be
desirable to have an all binder (thermoplastic) yarn structure and control the
bonds
to be predominantly at some or all of the intersections between the top and
bottom
subgroups of yarns in the structure without having to carefully locate the
intersections between these two subgroups.
When using ultrasonics, for instance, to=provide bonding energy to
thermoplastic yarns, it may be possible to achieve this preferential bonding
by
using thick or "fat" yarns for the top and bottom subgroups of yams. When.
squeezed between a broad-faced ultrasonic horn and anvil, the intersection of
the
fat yarns will receive more squeezing pressure than the adjacent thinner yarns
so
the ultrasonic heating will occur preferentially at the fat yarn intersections
with
minimum bonding of the thinner yam intersections.
The connected fabric structure needs to have a controlled number of
connections to achieve adequate strength, control bulk of the fabric, and to
retain
the inherent flexibility of the yarns used in the fabric. Too few connections
and
fabric integrity is compromised; too many connections and the fabric
flexibility is
compromised and bulk is reduced. The number of connections can be some
fraction of the total number of yarn crossings in the structure. For good
integrity,
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bulk control, and good flexibility, the number of connections must be
controlled
within limits. Figure 14 is a diagrammic view of a unit cell 380 of fabric
structure, and the cross marks represent the yarn crossings in the cell. The
cell
380 represents a biaxial fabric structure with eight yarns per direction for a
total of
(8X8) 64 crossings per cell. The lines 382, 384, 386, and 388 represent
possible
edges for a bond path through the cell. The circle 390 represents a single
bond
between a yarn on the top of the structure and a yarn on the bottom of the
structure, which would be the minimum number of bonded crossings for the cell.
Between lines 384 and 386 would be a single-crossing-width bond path which
would be a medium number of bonded crossings for a cell; between lines 384 and
388 would be a double-crossing-width bond path which would be a high number
of bonded crossings for a cell; and between 382 and 388 would be a triple-
crossing-width bond path which would be a very high number of bonded crossings
for a cell.
Below is a table of variables and values for determining the fraction of
bonded crossing to total crossings. "N" represents the number of yarns per
direction in a square unit cell; in the unit cel1380 this number is 8. "Min"
is the
bonding fraction if only one crossing is bonded out of N2 total crossings;
"Med" is
the bonding fraction if a single-crossing-width bond path is used that bonds N
crossings out of N2 crossings; "Hi" is the bonding fraction if a double-
crossing-
width bond path is used that bonds N+(N-1) crossings out of N2 crossings; "V
Hi"
is the bonding fraction if a triple-crossing-width bond path is used that
bonds
N+(N-1)+(N-1) crossings out of N2 crossings.
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BONDING FRACTION TABLE
Min @ Med@b Hi((D. V Hi@
# Bonded Crossings = I N N+(N-1) N+2(N- I)
Fraction of Bonded Crossing = I/N2 I/N (2N-1)/N2 (3N-2)/N2
N (# Yarns
per direction
Comments in unit cell)
3 .111 .333 .556 .778
preferred 4 .063 .250 .438 .625
preferred 5 .040 .200 .360 .520
most preferred 6 .028 .167 .306 .444
most preferred 7 .020 .143 .265 .388
most preferred 8 .016 .125 .234 .344
most preferred 9 .012 .111 .210 .309
most preferred 10 .010 .100 .190 .280
prefetred 11 .008 .091 .174 .256
preferred 12 .007 .083 .160 .236
preferred 13 .006 .077 .148 .219
preferred 14 .005 .071 .138 .204
preferred 15 .004 .067 .129 .191
preferred 16 .004 .063 .121 .180
17 .003 .059 .114 .170
18 .003 .056 .108 .160
Overall, it has been discovered that a bonding fraction within the range of
from about .003 to .778 is preferred. A bonding fraction within a range of
about
.008 to .520 is most preferred, or, that is, about 1% to 50% of the available
crossings bonded or otherwise connected. This fraction can be controlled by
the
number of yarns in a cell and the number of bonds in a cell, which can be
controlled by the width of the bond path and the number of bond paths within a
cell. If there is more than one bond path within a cell, the bond paths should
be
narrow.
Referring to the bond fraction table above that was prepared with the
simple cell process as a model, it should be noted that a fabric using 16
yarns per
cell that is at one end of the preferred scale may be most preferred when made
using the split cell/single step process. This is so, since the interiacing is
improved and the number of long unsecured yarn lengths is reduced for a given
number of yarns per cell by this process. In general, if more interlacing is
provided in a fabric of the invention, the number of bonds per cell can be
reduced
and still maintain good fabric integrity. For instance, if the split cell
fraction is
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1/2, the 16 yarn per cell, split cell fabric may be equivalent (in preference)
to the 8
yarn per cell, simple cell fabric in the table.
Figure 5A shows another flexible fabric structure where the yarns are
layed down in groups in three directions, at 0 degrees. 60 degrees and
120 degrees, to make a triaxial structure. For purpose of discussion, one
parallelogram-shaped basic cell of the structure, that repeats throughout, is
shown
at 88 with sides shown by dashed lines which are oriented along the zero and
sixty
degree direction. Alternatively, the basic repeating cell could also have been
selected as one with sides oriented along the zero and one hundred twenty
degree
direction. The top subgroup yarn 81 defines the location of the X-axis and the
intersection of yarn 81 with the next subgroup yarn 83 defines the origin 85
and
thereby the Y-axis. The cell space for the zero degree group is shown at 89;
the
cell space for the sixty degree group is shown at 90; The cell space for the
one
hundred twenty degree group is shown at 92. Each cell space has four possible
positions for yarn in the subgroups. The third subgroup yarn 87 crosses the
X-axis at about 0.5/4 which defines the third group shift from the origin. The
top
and bottom yarn subgroups, 12 and 1 respectively, are joined where they cross
and
overlap at points 80 and 82 both of which fall at the edge of the cell. Other
overlap bond points in the structure, when developed into a larger area
fabric,
would be at the cross-hatched points, such as 84 and 86. Notice that the
subgroup
2 yarns lay between the yams of the top subgroup 12 and bottom subgroup 1
yarns
and are at least partially involved in the bond. Figure 5B shows a larger
piece 95
of similar triaxial fabric, but made using eight yarns in each cell space,
multiple
cells, and a third group shift from the origin equal to zero, so equilateral
triangles
are formed by yarns of the three groups.
Using the position conventions discussed above, the matrix for the
structure of Figure 5A would be the following:
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no. of pos. subgroup 3rd group other
for subgroup offset shift from group shift
group/direction subgroup yams position orig. from orig.
1/0 top 12 4 0/4 n/a n/a
I I/ 120 next 11 4 0/4 n/a n/a
111/60 10 4 0/4 0.5/4 n/a
f /0 9 4 1 /4
11/120 8 4 1/4
111/60 7 4 1 /4
1/0 6 4 2/4
11/120 5 4 2/4
111/60 4 4 2/4
1/0 3 4 3/4
II/120 2 4 3/4
111/60 1 4 3/4
In general terms, the triaxial structure of the invention is similar to a
biaxial structure of the invention with the addition that the interlaced
fabric
structure further comprises:
- a plurality of third yarn subgroups having a plurality of yarns
oriented in a third angular direction free of crossings, the third yarn
subgroups
forming a stack with the first and second yarn subgroups wherein the yarns in
the
third yarn subgroup cross the yams in the first and second subgroups;
- the stacking of all of the plurality of third subgroups forming a
third yarn group comprising yams that densely cover the predetermined fabric
area.
In Figure 6, is shown an apparatus for continuously forming a biaxial
fabric structure with basic cells similar to those of Figures lE and 2A. The
apparatus consists of an elongated yarn support surface, such as a flat
perforated
belt 91, driven by motor 107, having an array of pins, such as pin 93, along
one
edge 94 and a parallel array of pins, such as pin 96 along the opposite edge
98 of
belt 91 for positively holding yams against the forces of yam reversal.
Beneath
the belt is arranged a vacuum plenum 97 attached to a source of vacuum 99 for
holding the yam in place on belt 91. Shown along edge 98 are a plurality of
yam
guide blocks 100, 102, 104, and 106 that are each mounted on guide means, such
as guides 101 and 103, and each having drive means, such as actuator 105 for
block 100, for traversing across belt 91 from one edge 98 to an opposed edge
94.
Each yarn guide block has a plurality of yarn guides, such as guide 173 in
block
100, for guiding a yam accurately onto the belt, such as yarn 111 coming off
of
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yarn supply package 113. Dashed outlines 100'. 102', 104' and 106' at edge 94
show the position the blocks would take after traversing belt 91. A plurality
of
ultrasonic horns. such as horn 108. at location 110 are positioned across the
belt
91 to act on yarn laid thereon to fusion bond the overlapping yams to one
another
at spaced positions in a deposited fabric. The belt and a rigid support 109
underneath act as the ultrasonic anvil to couple the energy through the yarn.
As
soon as the yam cools from the ultrasonic bonding, the fabric structure can be
stripped off the pins or hooks along the edge of the belt and the belt can be
recirculated while the fabric is wound in a roll on a core (not shown). The
winding tension for the fabric would be controlled to avoid distortion of the
fabric
along the direction of the belt which is along the fabric diagonal (bias) and
along
the axis of the bond path.
A representation of a two-group, biaxial, deposited fabric 112 is shown on
the belt. The representation shows the pattern of yarn laid down as the
process
starts up and the belt moves from right to left in the direction of arrow 114
as the
blocks move substantially perpendicularly across the belt together from edge
98 to
edge 94 in a manner coordinated with the belt motion along the belt elongated
axis; and continue back and forth as represented by arrows 116. What is shown
is
what was produced at start-up and then was stopped and the belt backed up to
align the start pattern with the guide blocks. For a true representation,
block 100
(and the other blocks) would be shown shifted to the right in the figure to a
location just beyond block 106. At the left end 118 of fabric 112 the top
subgroups of yarn are laid down by themselves, since at start-up none of the
other
subgroups are in place yet. At the right end 120 of the fabric 112, all
subgroups
are in place for a fully formed fabric by position 122 and the fabric will
thereafter
be continuously fully formed as the belt and blocks continue moving as
described.
The speed of the belt and the speed of the blocks are controlled and
coordinated
by a controller 115 communicating with motor 107 and the actuator for each
block, such as actuator 105. This ensures that the yarn passing through the
guide
blocks and laying on the belt forms a straight path at a 45 degree angle with
the
centerline and edge of the belt so there is a first group of yarn at +45
degrees as at
119 and a second group of yarn at -45 degrees as at 121. By varying the
controlled motions, other angles of laydown and curved paths are also
possible.
The first and second (lower) subgroups of yarn are laid down by block 106, the
third and fourth (middle) subgroups of yarn are laid down by block 104, the
fifth
and sixth (middle) subgroups of yarn are laid down by block 102, and the
seventh
and eighth (upper) subgroups of yarn are laid down by block 100. A given yam
across the fabric may alternate between subgroups in the cells going back and
forth across the fabric. In this example, the belt is moving and the blocks
move
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only back and forth across the belt and the belt moves continuousiv from right
to
left. The same pattern can be generated if the belt is considered stationary
and
unusually long, and the blocks move back and forth diagonally at 45 degrees
along the belt from left to right.
The pattern of over and under yarns varies in the fabric as evidenced by
cells 124, 126, and 128. Figure 7 shows this portion of fabric 112 enlarged
for
discussion. The yarns are shown slightly spaced apart in each group for
clarity.
In Figure 7, yarn 130 is the eighth subgroup top yarn in cells 124 and 126,
but is
the seventh subgroup yarn in cell 128. Likewise, yarn 132 is the sixth
subgroup
yarn in cells 124 and 126, but the fifth subgroup yarn in cell 128. Similar
changes
occur in the remaining subgroups. This deviation from a perfectly regular
pattern
within a fabric, unlike the pattern in Figures 1 E and 2A, does not affect the
structural integrity of the fabric and is an example of some acceptable
variations in
the patterns of the invention. The adjacent cells 134, 136, and 138 are all
identical
and are the same as the cells of Figures 1 E and 2A. Each yarn has a subgroup
assignment and a position assignment in a cell. However, both the subgroup
assignment and position assignment may vary from cell to cell in a given
fabric
structure, or they may remain constant, and in both cases still follow the
basic
rules for practicing the invention which are:
- a plurality of substantially parallel yarns in a group are arranged to
densely cover an area with the yams of one group arranged to cross the yarns
of
another group;
- each group is comprised of a plurality of subgroups, with each
subgroup having a plurality of yams sparsely arranged;
- the plurality of yarns in one subgroup of one group are offset from
the plurality of yams in the other subgroups of the same group;
- the yams of the top subgroup and bottom subgroup are connected
to each other at spaced locations either directly, or indirectly through the
yarns in
the other subgroups.
The top to bottom bond point for cell 124 is at 140; the bond point for cell
126 is at 142; the bond point for cell 128 is at 144. For a partial cell 146
at the
edge of the fabric, the bond point is at 148. All these bond points would be
covered by ultrasonic paths aligned with the arrows 150 at the left end of
Figure 7.
Four yams in each guide are sufficient to cover the belt for a four-yarn-
cell-space fabric at the width shown and for a 45 degree pattern. In Figure 6,
the
space covered by one yarn, such as yarn 152. going from belt side 94 over to
belt
side 98 and back across the belt 91 takes up a distance along the belt as
shown at
154. Four yarns, such as yams 152, 156, 158, and 160 in guide 100, fill this
space
for subgroups 8 and 7. If a wider belt were used where the opposite edge 98
was
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at 162, the space covered by yarn 152 going back and forth across belt 91
would
take up a distance along the belt as shown at 164. This would require
additional
yarns 166, 168, 170, and 172 to fill this space for subgroups 7 and 8. Guide
100
would have to be extended to hold 8 yarns instead of only 4 for this wider
fabric,
and block 102 would have to be shifted aiong the length of the belt 91 to make
room for the larger block 100. Block 102 and the other blocks 104 and 106
would
be extended and shifted similarly. The first yarn guide hole 171 in block 102
is
shown spaced from the last yarn guide hole 173 in block 100 by a distance 175
of
one cell diagonal plus one yarn position diagonal to lay down the subgroup 5
and
6 yarns in offset positions from the subgroup 7 and 8 yarns laid bown by block
100. This spacing is similar for the succeeding guide blocks along the side of
belt
91. This spacing may be less or more by units of a cell diagonal depending on
how much room is needed for the guide blocks.
This spacing of guide blocks and coordinated motion between the blocks
and the belt results in the 45 degree diagonal pattern of yam wherein the
positions
of each of the diagonal yarns are adjacent the other yams (rather than
overlapping
them) to thereby densely cover the yarn support surface on the belt with the
yarns.
If a more dense, thicker structure is desired, additional guide blocks may be
employed and another dense structure built up on top of the first one to make
a
layered structure. In general terms, the process just described for forming an
interlaced fabric structure comprises:
(a) providing an elongated fabric support surface having an
elongated axis and opposed lateral edges parallel to the axis, and arranging
the
surface adjacent a plurality of yarn guide blocks arranged along opposed
lateral
edges of the elongated surface;
(b) providing a plurality of guides on said guide block, each guide
adapted to guide a yarn from a yarn source to the support surface;
(c) engaging the yarns at one edge of said support surface;
(d) providing relative motion between the support surface and each
of the plurality of guide blocks so that the guide blocks deposit yarn from
the
guides onto the surface in a first diagonal direction relative to the edge of
the
surface and in a predetermined direction along the support surface;
(e) engaging the yams at an opposed edge of said support surface;
(f) reversing the relative motion of the guide blocks and support
surface so that the guide blocks deposit yarn from the guides onto the surface
in a
second diagonal direction relative to the edge of the surface and in said
predetermined direction;
(g) arranging said guide blocks and guides and arranging said
relative motion so that when said yarns from said blocks are deposited on said
24
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WO 98/17852 PCT/US97/18641
surface. the diagonal positions of each said yarn are offset from the other
yams to
thereby densely cover the support surface with said yarns in one cvcle of
relative
motion from one edge to the opposite edge and back to the one edge.
With the arrangement shown with separate guide blocks, the position of
subgroup yarns in the cell space can be varied by displacing the blocks along
the
length of the belt 91. With a space between the guide blocks and the manner of
laying down yams to form a fabric, it is possible to add materials between the
subgroups of yarns within a fabric structure. For instance, a roll of film 117
could
be arranged to continuously feed film between blocks 104 and 106, around a
guide
119, and onto the fabric 112 between the subgroups of yam laid down by block
106 (subgroups I and 2) and block 104 (subgroups 3 and 4). In another
instance,
machine direction yarns 121 and 123 could be arranged to continuously feed
yarn
between blocks 102 and 104, through guides 125 and 127 respectively, and onto
the fabric 112 between the subgroups of yarn laid down by block 104 (subgroups
3 and 4) and block 102 (subgroups 5 and 6). Such insertions of material
between
subgroups is a unique capability of the fabric of the invention. In the case
illustrated, the addition of the film and machine direction yarns can reduce
the
deflection of the bias fabric in the machine direction or can achieve other
special
purposes. Other materials, such as nonwoven fabrics, wires, elastomeric
fabrics or
yarns, webs of natural or synthetic materials, scrims, etc., can be inserted.
There is another way of using guide blocks to lay yarn down continuously
to form a fabric on a belt. The blocks could be arranged in alternate
locations
along the edge of belt 91 and be arranged to travel in opposite directions
across
the belt as the belt is moving as shown in Figures 8A and 8B. In Figure 8A,
the
blocks 100 and 104 are arranged along edge 94 of belt 91 and blocks 102 and
106
are arranged along edge 98. As the belt 91 moves from right to left as seen
going
from Figures 8A to 8B, the blocks cross the belt to the opposite side, thereby
laying yarn down on the belt in a diagonal path. Repeated operation of the
blocks
back and forth as the belt continues to run will produce a pattern such as
seen in
enlarged fabric 174 of Figure 9. This pattern is slightly different from the
fabric
112 of Figures 6 and 7. Looking at cells 176, 178, and 180, cells 176 and 178
are
five subgroup cells while cell 180 is an eight subgroup cell. In cell 176,
yarn 181
is in subgroup 5; yarns 182 and 184 are in the same subgroup, subgroup 4; yams
186 and 188 are both in subgroup 3; yarns 190 and 192 are both in subgroup 2
and
yam 194 is in subgroup 1. Looking at cell 180, yarn 181 is in subgroup 7; yam
186 is in subgroup 5; yam 188 is in subgroup 3 and yarn 194 is in subgroup 1.
Cell 180 has the same arrangement as the basic cell of Figures 1 E and 2A. In
order to form proper bond points from the top subgroup 5 to the non-
intersecting
bottom subgroup I in cell 176, there must be a bond point 196 between yarn 181
CA 02267790 1999-04-06
WO 98/17852 PCT/US97/18641
of group 5 and yarn 182 of group 4 plus a bond point 198 between yarn 182 and
yarn 194 of group 1. With the ultrasonic bonding paths as shown by the arrows
at
200, there will be an additional bond point 202 between yarn 181 of subgroup 5
and yarn 192 of subgroup 2 and a bond point 204 between yarn 192 and yam 194
of subgroup 1. Through a chain of bond points in cell 176, the top subgroup 5
is
connected to the bottom subgroup 1 even though the top and bottom subgroups
don't cross one another. The arrangement of ultrasonic bond paths to achieve
proper spaced bonds for the fabric 112 of Figures 6 and 7 is different from
the
bond paths for the fabric 174 of Figure 9.
Figure l0A shows another apparatus for producing two dimensional
fabrics of the invention. It is suitable for making a batch fabric instead of
a
continuous fabric. It is a simplier apparatus than that of Figure 6. A single
guide
block 206 is oscillated back and forth by actuator 207 over a table 208 that
also
oscillates back and forth by actuator 209 in a direction at right angles to
the
direction of oscillation of block 206. Parallel rows of pins 210 and 212 hold
the
yarn at the reversals. Vacuum may also be applied to the plate if desired. The
block and table make numerous cycles back and forth in a manner coordinated
with each other to produce dense groups of yarn crossing one another. A single
ultrasonic bonding horn 211 is then repeatedly passed over the fabric in paths
parallel to the oscillation direction of table 208 to make spaced bond paths
to
connect the top and bottom subgroups of yams together. The fabric is then
peeled
off the edge pins 210, 212. By adding motion to the guide 206 in a vertical
direction by actuator 205, a three dimensional fabric could be made over a
three
dimensional form 203 mounted on table 208. Figure l OB shows the curved yarn
paths in a fabric 213 that may be employed to cover a three dimensional form.
Figure 11 A shows another apparatus for producing two dimensional
batches of fabric structure. It is similar to the apparatus of Figure 10
except
instead of laying yarn down on a table, the yam is placed on a mandrel 214 by
a
guide block 216. Instead of the guide block 216 oscillating back and forth as
in
Figure 10, the guide block 216 is stationary and the mandrel 214 oscillates in
a
rotary motion by motor 215 as indicated by arrow 217 at the same time the
table
208' moves the mandrel past the guide block by actuator 209'. A single row of
pins 218 holds the yarn between reversals in both directions as the mandrel
rotates. The result is a fabric having a cylindrical tubular shape during
fabrication.
After all yarns are laid down, a single ultrasonic horn 219 repeatedly follows
an
axial path along the mandrel at different circumferential locations over the
fabric
as it is oscillated back and forth via the table and mandrel. This results in
parallel
bond paths to connect the top and bottom groups together. Alternatively, the
horn
could follow a circumferential path at different axial locations along the
mandrel.
26
CA 02267790 1999-04-06
WO 98/17852 PCT/US97/18641
W11en peeled off pins 218. the result is a flat fabric. This fabrication on a
cylindrical mandrel has an advantage over the flat plate of Figure l0A in that
yarn
tension can be used to hold the yarns securely against the mandrel.
Figure 11 B shows an apparatus similar to that in Figure 11 A except the
mandrel 214 would rotate continuously in one direction to make a cylindrical
batch of fabric. In Figure 1 l B, a rotating mandrel 220 is mounted on
moveable
table 208" oscillated by actuator 209". A circular yarn guide support 222
holds a
plurality of guides, such as yarn guide 224, that are spaced apart around the
circumference of the mandrel 220. Support 222 is held stationary relative to
the
mandrel and table. A yarn strand, such as strand 226 from stationary package
228,
is fed through each guide, such as 224, and is secured to end 230 of the
mandrel
where the support and mandrel are aligned before the mandrel starts to rotate
and
the table starts to move. Since the yarn packages are stationary, the yarn can
be
supplied endlessly using a resupply package (not shown) and yarn transfer
tails on
the packages. The mandrel 220 has a plurality of rings 232 and 234 of closely
spaced pins near the ends 230 and 236, respectively, of the mandrel as shown.
These engage the yarn at the ends of the traverse when the table reverses
direction.
At the end of each traverse as the yarn engages the pin rings, the table stops
moving and the mandrel is moved through a few degrees of rotation to make sure
the yarn is firmly engaged by the pins before the table reverses direction.
The
mandrel may be moved precisely by a stepping motor, such as motor 238. The
yarn must also align with the desired offset position of the cell before
laying down
next to an adjacent yarn.
The yarn laydown pattern and the motion of the table and mandrel will be
discussed further referring to Figure 11 C which is an imaginary view of the
mandrel as if it were flattened out into a two dimensional form. At the left
of the
figure is mandrel end 236 and pin ring 234, and at the right of the figure is
mandrel end 230 and pin ring 232. The dashed lines in the figure trace the
yarn
paths on the back side of the flattened mandrel; the solid lines trace the
yarn paths
on the front side. The yarns illustrated are only those that are seen to start
on the
front side of the figure at points 240, 242, 244, and 246; and of these, only
the
yam starting at point 240 has its path traced throughout one complete laydown.
These start points are those where the yarn is laid down by guides such as
guide
224 in support 222. Four other yarns from support 222 would be tracing out
similar paths starting on the back side of the flattened mandrel at the same
spacing
as the yarns shown on the front side. These points represent the first yam
position
0/4 of four possible positions for a first group in a cell space for the
fabric. Yarn
at point 240 follows path 248 as mandrel 220 rotates and translates relative
to yam
guide support 222; while yarns at points 242, 244, and 246 follow paths 250,
252,
27
CA 02267790 1999-04-06
WO 98/17852 PCT/US97/18641
and 254, respectively. Tracing path 248 for laying down yarn in a first group,
path 248 passes to the back side of the tlattened mandrel at 256 and returns
to the
front side at 258 and reaches the ring of pins 232 at 260. SimiIarly, another
first
group yam from point 242 would reach the ring 232 at point 262: yarn from
point
244 would reach the ring 232 at point 264; and yam from point 246 would reach
the ring 232 at point 266.
Assuming the yarn is instantly engaged by the pin ring 232, the mandrel
rotation continued, and the mandrel translation reversed immediately, the yarn
path 248' would start back along the mandrel from point 260 to lay down yarn
in
the second group. If this ideal situation did not exist, the translation of
the
mandrel would stop while the mandrel rotation continued for a few degrees to
anchor the yam in the pins. The points at the right end 230 of the mandrel
represent the first yarn position 0/4 for a second group in a cell space for
the
fabric. Yam path 248' passes to the back side of the flattened mandrel at 268
and
returns to the front side at 270, and reaches the ring of pins 234 at point
272. It
now must be decided what pattern of yam positions are desired in the fabric.
Assuming the next yam position desired is the 1/4 position, and the mandrel
will
continue rotating in the same direction, the yarn landing at position 272
wants to
be in position 274 before reversing the translation of the mandrel. The
translation
of the mandrel will stop when the yam reaches point 272 and will dwell there
while the mandrel rotates a few degrees until the yarn reaches point 274; and
the
translation will then reverse and the yarn will follow path 248". This will
cause
the yarn to land in the right pin ring 232 at point 276 which is also in the
1/4
position of the cell space. If this is the desired pattern for the second
group cell
space, the mandrel translation can immediately reverse and the yarn will
return
along path 248"'. If it is desired to change the yarn position for the cell,
the
translation of the mandrel can stop and the mandrel can continue rotating for
a few
degrees until the yarn is in the desired position in the cell space, and then
the
translation reverses and the yam follows on a new path. The yam pattern in a
cell
can then be different for the first group yams and the second group yams. This
pattern will continue until the yarn from point 240 lands back at pin ring 234
at
position 278. At that point all the yarn positions for the cell space are
occupied by
subgroups of yarns and the cylindrical batch of fabric structure is ready for
bonding.
An ultrasonic bonding hom (not shown, but similar to horn 219 in
Figure 11) can make repeated passes along the axis of the mandrel by
translating
the mandrel without rotation under the stationary horn and rotating the
mandrel
through several degrees at the end of each pass. Alternatively, the bonding
can be
along circumferential paths. After bonding, the pin rings may be removed (by
28
CA 02267790 1999-04-06
WO 98/17852 PCT/US97/18641
retracting or other means) and the fabric pushed off the mandrel.
Alternatively,
one end of the fabric may be cut at one pin ring and only the opposite pin
ring
removed. By pushing the fabric, it will expand, since the fabric is oriented
on a
bias relative to the mandrel axis, so it will be easy to slide the fabric off
the
mandrel. In general terms, the process just described for forming an
interlaced
fabric structure comprises:
(a) providing an elongated fabric support surface on a rotatable
mandrel having a rotational axis and opposed lateral ends substantially
perpendicular to said axis, and
(b) orienting the surface adjacent a circumferential yarn guide ring
substantially perpendicular to said axis, the ring arranged adjacent a lateral
end of
the fabric support surface;
(c) providing a plurality of guides on said guide ring, each guide
adapted to guide a yarn from a yam source to the support surface, the guides
equally spaced to deposit yarn at equal intervals around the mandrel
circumference;
(d) engaging the yarns at one end of said support surface;
(e) providing relative motion between the support surface and the
guide ring so that the ring deposits yarn from the guides onto the surface in
a first
diagonal direction relative to the ends of the surface from one end to the
opposed
end and in a predetermined rotational direction along the support surface
thereby
sparsely covering the fabric area on the mandrel surface with yarns in said
first
direction;
(f) engaging the yarns at an opposed end of said support surface;
(g) reversing the relative motion of the guide ring and support
surface so that the guide ring deposits yarn from the guides onto the surface
in a
second diagonal direction relative to the ends of the surface from said
opposed end
to said one end and in said predetermined rotational direction along the
support
surface thereby sparsely covering the fabric area on the mandrel surface with
yams in said second direction;
(h) arranging said guide ring and guides and arranging said
relative motion so that when the yarns from said guides on the guide ring are
subsequently deposited on said surface, the diagonal positions of subsequently
deposited yarns are offset from previously deposited yarns in each first and
second
diagonal direction to thereby densely cover the support surface with said
yarns
after repeated cycles of relative motion from said one end to the opposed end
and
back to said one end.
In some cases, it is desired to use the same circular guide support 222
(Figure 11 B) for structures having different numbers of yams per cell so a
29
CA 02267790 2005-06-20
different guide support does not need to be installed for routine changes in
varn
denier or the like. One way to accomplish this flexibility is to use a special
laydown pattern for yarns as discussed above referring to the split
cell/single step
process which would work well with this apparatus to make cells that would
S appear to have. and would perform as if there were, fewer numbers of yarns
in
each cell:
Another possibility is a method of operating the mandrel motor 238 and
table actuator 209" to apply a multiple pass of yarns from guide support 222
to
make actual changes in the number of yams per subgroup in the structure. For
instance, to double the number of yarns per subgroup, the yarns, such as yarns
226
and 226', could be layed down in a path designated by dashed lines 227 and
which
would add one yarn between the original yams laid down by the guide. This
would be accomplished as follows:
a. rotate the mandrel in a clockwise direction as. designated by arrow
221, and translate the mandrel past the guide support 222 as shown so that a
sparse subgroup of yarn, such as a zero degree subgroup formed of yarns such
as
yarn 226 and 226', is laved down on the mandrel from pin ring 232 to pin ring
234;
b. stop the translation and rotate the mandrel further by one half the .
distance between the yarn guides 224;
c. reverse the rotation of the mandrel to rotate counter-clockwise and
translate the mandrel past the guide support 222 so that the yarn, such as yam
226
and 226', is layed down on the mandrel from pin ring 234 to 232 and between
the
solid line yams to add yarns to the sparse zero degree subgroup;
d. stop the mandrel translation and continue the counter-clockwise
rotation by a distance to place a yarn guide 224 in position for the next
subgroup,
such as a ninety degree subgroup;
e. continue the counter-clockwise rotation and translate the mandrel
past the guide support 222 so that a sparse subgroup of yarn, oriented in a
ninety
degree subgroup formed of yarns such as yarn 226 and 226', is layed down on
the
mandrel from pin ring 232 to pin ring 234;
f. stop the translation and rotate the mandrel further in a counter-
clockwise direction by one half the distance between the yarn guides 224;
g. reverse the rotation of the mandrel to rotate clockwise and -
translate the mandrel past the guide support 222 so that the yarrt, such as
yam 226
and 226', is layed down on the mandrel from pin ring 234 to 232 and between
the
just-layed-down ninety degiee subgroup yarns to add yams to the sparse ninety
degree subgroup;
- - . ..- -... J .. ': :..-. ~:_. ' - .-~.:. =.- . . 30
CA 02267790 2005-06-20
h. stop the mandrel translation and continue the clockwise rotation
by a distance to place a varn guide 224 in position for the next subgroup,
such as
another zero degree-subgroup;
i. repeat the process a-h just described to add more subgroups as
,5 desired.
This altered process is different from the simple cell process for fonnirig
subgroups on the mandrel 220 where the guide has all the vams necessarv for a
subgroup and the mandrel rotates in the same direction as it lays yarn back
and
forth between the pin rings. The altered process just described adds yams to a
subgroup by the continued rotation of the mandrel half the distance (or some
other
fraction) between the yarn guides 224, and then reversing the rotation of the
mandrel to add yarns to that subgroup. If two more yams were to be added
between guided yams instead of the one more yarn just described in the example
above, the continued rotation would only be one third the distance between
guides
I5 ~ and this step would be repeated at the next pin ring. Similarly, if three
more yarns
were to be added, the continued mandrel rotation would only be one fourth of
the
distance between guides and this step would be repeated at the next two pin
rings.
When laying down yams in this manner where the direction of rotation of the
mandrel is reversed, it is important to minimize backlash in the apparatus and
to
minimize the unguided yarn length between the yam guide and the mandrel
surface.
There is a concern when laying down yam on the mandrel of Figure 11 B
that the path from the guide to the surface of the mandrel be as short as
possible so
the lay down position on the mandrel can be accurately predicted and
controlled.
This is a concern in any of the yarn laydown devices. One way to accurately
lay
down the yams with precision is to use the device in Figure I ID which is
shown
in an end view of a mandrel 230' and circular guide support 222'. To
illustrate a
general case, the mandrel 230' is shown as an oval shape. It will be
appreciated
that.the mandrel shape may also vary along its axis. Support 222' holds a
plurality
.30 of guides, such'as guide 224'.that guides yarn 226. Each guide,
referringto guide
224', includes a hollow shaft 280, a radiused guide tip. 282, a spring 284,
and a
retainer 286. = The shaft passes through a hole 288 in support 222': -Spring
284 is
placed over shaft 280 between support 222' and tip 282 to thereby urge the tip
. _ . ... _ , -__ -_.-
_.
toward the mandrel 23D. _ Yarn 226 passes through hollow shaft 280 and out
through tip 282 and directlyonto mandrel 230'. In this way, the yarn is laid
directly onto the mandrel much as if it were "painted" on the mandrel surface.
This. insures accurate placement of the yarn on the mandrel. The shaft moves
freely in hole 288 in support 222'-to allow the guide tip to ride over any
variations
in the shape of the mandrel while the spring keeps tip 282, and the yarn 226
31 .
CA 02267790 1999-04-06
WO 98/17852 PCT/US97/18641
issuing therefrom, securely in contact with the mandrel surface. The tip 282
may
advantageously be coated with a low friction coating for ease of sliding over
the
mandrel and the yarns laying thereon.
Figure 20 shows another device for laying down yarn accurately on a
compound curvature, such as a spherical surface, when using a robot or other
mechanical actuator. There is a problem that the robot does not always follow
complex curved paths in a continuous smooth motion and some irregular stepped
motion is produced. It is useful to have some compliance in a yarn guide tip
to
keep it in contact with a curved mandrel surface during deviations in the path
of
the guide actuator or robot. Yarn guide 470 is attached to a slide 472 which
is
attached to a robot face plate 474. The slide is useful for fine positioning
adjustments by way of screw 476 to set the initial deflection of the guide
when
programming the robot path. The guide 470 comprises a frame 478 that supports
a hollow shaft 480 for rotation. A block 482 mounted on shaft 480 supports
four
thin flexible springs 484, 485, 486, and 487 (located behind 486). Attached at
the
intersection of the springs is a hollow tip 488 with a hemispherical end 489.
The
springs permit motion of the tip in the axial direction 490 and in a conical
direction defined by angle 492. Rotation of shaft 480 allows the tip to roll
over
any surface it contacts while it is also free to deflect axially and
angularly. This
allows the tip to accurately place a yarn 494 on the surface while the yam is
passing through the hole 496 in hollow shaft 480 and the hole 498 in hollow
tip
488.
Figure 12 shows an apparatus that is used to make a simple three
dimensional tubular batch fabric using a lathe-type device or a textile yarn
winding device where the mandrel 290 rotates continuously by motor 291, but
without translating, and the circular guide support 292 traverses along the
mandrel
axis back and forth driven by a cam or screw 294 rotated by a motor 293.
Coordination of motors 291 and 293 provides control of the fabric structure.
The
pin rings of Figure 11 B may be eliminated by providing shoulders 295 and 296
to
engage the yarn at the reversals and by keeping the bias angle low relative to
the
shoulder. This is a variation of the device shown in Figure 11 B which may
allow
fabrication of fabrics of the invention with slight modification of existing
mandrel
systems.
Figure 13 shows an apparatus that is used to make a continuous fabric
where the two groups of yarn are oriented parallel and perpendicular to the
direction of motion of the laydown belt. One group of yarns is supplied as a
plurality of subgroups each comprising a plurality of yarns in a warp
direction;
and another group is supplied as a plurality of subgroups each comprising a
plurality of yarns in a weft direction. A plurality of spaced ultrasonic bond
paths
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CA 02267790 1999-04-06
WO 98/17852 PCT/US97/18641
connect the top and bottom subgroups together. The wett direction yarns are
supplied by a process and apparatus similar to that disclosed in U.S.
4,030.168 to
Cole hereby incorporated herein by reference.
In Figure 13 is an apparatus 500 for laying down subgroups of yarns 502,
504, 506, and 508 in the machine direction (MD) and combining them with
subgroups of yams 510. 512, 514, and 516 in the cross-machine direction (XD)
on
a conveyor surface 517 to continuously form a pre-bonded fabric structure 518.
The subgroups of yarns 502, 504, 506 and 508 are guided onto the conveyor
surface 517 by guides extending across the surface 517, such as guide bar 503
for
subgroup 502. The guides, such as guide bar 503, may comprise rollers each
having circumferential guide grooves (not shown) to act as individual yarn
guides
to guide each of a plurality of yarns spaced across the guide between the
opposed
edges of the conveyor surface for arranging the subgroup of yams with respect
to
other MD yarns deposited on the conveyor surface. The guides, such as guide
bar
503, may also comprise a group of spaced eyelets on a bar to guide each of a
plurality of yarns in the subgroup of the group arranged in the machine
direction.
The subgroups of yarns 510, 512, 514 and 516 are guided onto the conveyor
surface 517 by looped guides along the two opposed edges of belt 517, such as
looped guides 505 on the near side and 507 on the far side for guiding
subgroup
510. The looped guides have spaced yam holders or clamps (not shown) for
holding the spaced relationship between the yams in the subgroup of the group
arranged in the XD direction. The holders or clamps would release the yarn
after
it is deposited on the fabric support surface of the conveyor and on any MD
yarns
already placed there. Preferably the XD yams are not released by the clamps
until
they are engaged by the next MD yams. In some cases, the MD yams may be
placed under tension and be able to provide enough support for the XD yams so
that a separate support surface is not required. An alternative to the endless
loop
conveyor surface illustrated may be a circular drum support surface, as long
as the
yams can be adequately held on the surface, such as with MD yam tension or a
vacuum, during rotation of the drum. The conveyor would be driven and have a
vacuum applied similarly to the conveyor described in Figure 6. Fabric 518 is
consolidated and connected by a plurality of spaced apart bonders located at
position 520 to form a continuous fabric 522 of the invention. Contact roller
524
presses against conveyor roller 526 to positively drive the fabric without
slippage
on conveyor surface 517. The subgroup 502 comprises a sparsely spaced
plurality
of yarns that are spaced apart by a repeatable cell distance and are laid
directly on
a conveyor surface 517. The subgroup 504 comprises a sparsely spaced plurality
of yarns that are also spaced apart by the same cell distance and are offset
one
yam position (into the paper) from subgroup 502; subgroup 506 comprises a
33
CA 02267790 1999-04-06
WO 98/17852 PCTIUS97/18641
sparsely spaced plurality of yams that are spaced apart by the same cell
distance
and are offset from both 502 and 504; and subgroup 508 comprises a sparsely
spaced plurality of yams that are spaced apart by the same cell distance and
are
offset from all of subgroups 502, 504. and 506. The subgroup 510 comprises a
sparsely spaced plurality of yams with all the yams, such as yarns 526 and
528,
spaced apart a repeatable cell distance 530, which distance is the same for
the
spacing of all the yams in the other subgroups 512, 514, and 516. This spacing
determines the number of possible yarn positions for the yarns in the
subgroups
510, 512, 514, and 516.
This controlled spacing and offset is best seen as the subgroups come
together to form a fabric structure. The yarns in subgroup 510 are spaced
apart at
a cell distance at 532; the yarns in subgroup 512 are offset from subgroup 510
by
a repeatable offset 534 and are spaced apart by the cell distance at 536; the
yarns
in subgroup 514 are offset from subgroup 512 by a repeatable offset 538 and
are
spaced apart by the cell distance at 540; and the yarns of subgroup 516 are
offset
from subgroup 514 by a repeatable offset 542 and are spaced apart by the cell
distance at 544. These yarns are shown in a position pattern of 0/4, 1/4, 2/4,
and
3/4 going sequentially from subgroup 510 to subgroup 516. This sequence could
be different, such as 0/4, 3/4, 1/4, and 2/4, depending on the pattern and
structure
desired. The same pattern sequence variations are also possible in subgroups
502,
504, 506, and 508 without regard to the patterns in subgroups 510-516. Films
and
other fiber materials may be inserted between subgroups of yarn as was
suggested
in Figure 6. In general terms, the process just described for forming an
interlaced
fabric structure comprises:
(a) providing an elongated fabric support surface having an
elongated axis and opposed lateral edges, wherein a machine direction (MD) is
defined in the direction of the elongated axis and a cross-machine direction
(XD)
is defined between opposed edges;
(b) laying down at the support surface a plurality of yarn
subgroups having yarns oriented in the MD, each subgroup layed down at spaced
locations along the elongated axis, the yams in each one MD subgroup located
at
offset positions in the XD different from other MD subgroups;
(c) laying down at the support surface a plurality of yam
subgroups having yarns oriented in the XD, each subgroup layed down at spaced
locations along the elongated axis, an XD subgroup spaced from a respective MD
subgroup, the yarns in each one XD subgroup located at offset positions in the
MD different from other XD subgroups;
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(d) moving the support surface in a predetermined direction
aligned with the elongated axis to bring together the yarns deposited from all
MD
and XD subgroups to form a stack;
(e) urging the subgroups together and connecting the top subgroup
in the stack to the bottom subgroup in the stack to thereby form an interlaced
fabric structure.
A variation of the process described in relation to Figure 13 is to
preassemble the two orthogonal and adjacent subgroups, such as subgroups 502
and 510 to form a scrim. The four scrims 502/510, 504/512, 506/514, and
508/516 would be joined with the offsets between subgroups described above to
make the same fabric structure. The preassembled subgroups could be
temporarily assembled into the scrims with a size adhesive which is removed
after
final assembly and connecting of the upper and lower subgroups, or the
connections between the preassembled subgroups could remain in the final
fabric
structure.
The flexible fabric of the instant invention can be made directly into a
three dimensional shape referring to Figure 15 to Figure 18E. A flexible
fabric
can be made directly to shape by laying each subgroup directly onto a shaped
surface. Figure 15 shows an example of using a generalized dispensing system
to
create the fabric. A generalized actuator, in this case, a six degree of
freedom
robot 401, carries a single yarn dispenser 402, similar to that shown in
Figure 20,
to the desired positions and orientations to deposit a yarn 403 onto a shaped
mandrel 404. The robot may also carry a plurality of yarn dispensers to
deposit a
plurality of spaced yarns simultaneously onto the shaped mandrel.
For a general shape, each group of yarns will include yarns that are curved
in space. Preferably, neighboring yarns in the group are generally parallel
and the
yarns of a group densely cover the region of the surface bounded by the
outermost
yarns of that group; a given group may not necessarily cover the entirety of
the
desired final shape. Figure 16A shows a plan view of the mandrel, Figure 16B
and 16D show elevation views, and Figure 16C an isometric view. Referring to
the figures, paths 410 are curved paths in space for one subgroup of one group
of
yarns on a spherical mandrel 411. This subgroup path 410 consists of arcs 412,
413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, joined by connectors
424,
425, 426, 427, 428, 429, 430, 431, 432, 433, 434. Figure 16B clearly shows how
the connectors join the arcs of subgroup path 410, such as connector 424 which
joins arc 412 to arc 413.
The orientation of the subgroup paths 410 with respect to the mandrel 411
is given by two angles: a rotation about the z-axis 435 and an inclination
about the
x-y plane 436. To find the angle 435, start at the beginning of arc 412 at
point 437
_- ~ ----r-------
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in the lower right of Figure 16D. Define a tangent vector 438 that travels
along
arc 412 leftwards in Figure 16D towards the first connector 424. The
orientation
of 'this tangent vector at Y=0 in Figure 16D is shown in the vector 439, seen
also
in Figure 16A. Angle 435 is defined as the angle from the positive x-axis 442
to
vector 439, in the plan view 16A, which for the case shown is at -90 degrees.
The
subgroup paths, 410 are inclined to the x-y plane 440 at an angle 4' 36. which
for
the case shown is at +75 degrees. The angle 436 is inclined less than 90
degrees
to insure that the yams at the equator of this spherical mandrel cross in an
intersecting relationship from subgroup to subgroup, rather than being nearly
parallel if angle 436 were at 90 degrees.
Figures 17A-17D show two other subgroup paths 450 and 451 created by
rotating the subgroup paths 410 about the z-axis. The plan view angle,
equivalent
to angle 435, for path 450 is +30 measured to vector 452 and for path
451 is +150 measured to vector 453. In this example, the
three groups of subgroups are evenly spaced, with the plan view angle of path
450 being +120 from path 410 and the plan view angle of path 451 being
-120 from path 410. The number of groups and the necessary angles 435 and 436
for each group may be varied to provide the required structural properties of
the
shaped fabric.
The subgroup path 410 defines the skeleton of paths for the entire group of
yarns in this general direction. Other subgroups in this group are found by
placing
yarns in offset positions along the surface, generally parallel to the sparse
yarns of
the skeleton 410. In general, the subgroups of a directional group are not
simply
shifted versions of each other, as in the flat case; they have slightly
different
shapes. Other subgroups for the yarns in the other group directions 450 and
451
are found by offsetting the subgroup paths 450 and 451 similarly along the
surface
of the mandrel for those general directions. =
Figures 18A-18E illustrate a surnmation and completion of what was
discussed referring to the yarn paths of Figures 16A-D and.17A-D.
Figures 18A-E show the progression of yarn from a single subgroup in
Figure 18A; to the first subgroups of three groups in Figure 18B; to the first
two
subgroups of three groups in Figure 18C; to the first three subgroups of three
groups in Figure 18D; to four subgroups of three groups in Figure 18E, in this
case, densely covering the desired surface region to form shaped.fabric
structure
._t
462. In _this exarnple, the yarns in each subigroup are spaced 4 yarns apart,
and
each subgroup is offset from the previous group by a single position. A
similar
procedure can be used for groups with different number of yarns (say 3 to 8
yarns)
separating the yarns in each subgroup, or a different offset sequence for
successive
subgroups (say 0/4. 2/4, 1/4, 3/4 instead of the 0/4, 1/4, 2/4, 3/4 sequence
shown):
36 ,
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Each family of subgroup paths 410, 450, or 451. making up each of the
three groups ofyarn paths need not cover the,entire final surface region
desired,
and need not be similar to each other, as in this example. For a general shape
with
less symmetry, the different groups will not be similar. One may choose as
many
groups in as many general directions as necessary to cover the desired surface
region such that at every point, there are at least two groups of crossing
yarns, and
the crossing angle is sufficient to meet the mechanical property requirements
of
the fabric. Figure 18E shows that the flexible fabric structure 462 may
combine
triaxial regions 460, having three yarn directions, with biaxial regions 461,
having
two yam directions.
To fabricate the fabric, (referring.to Figures 15, 16A-D, and 17 A-D) the
generalized actuator may be taught or progratnmed to dispense yarn along the
subgroup paths defined for each group. The dispenser may dispense a single
yarn
by traversing sequentially the arc 412, then the connector 424, then the arc
413,
then the connector 425, etc., then the arc 422, then the connector 434, then
the arc
423. Alternately, a dispenser can dispense all the arcs 412, 413, 414, 415,
416,
417, 418, 419, 420, 421, 422, 423 simultaneously in one pass. Alternately, a
dispenser can dispense selected numbers of the arcs, such as the arcs 412,
413,
414 in one pass; and complete remaining arcs in succeeding passes of arcs 415,
416, 417, then 418, 419, 420, and then 421, 422, 423; using some or all of the
connectors 424, 425, 426, 427, 428, 429, 430, 431, 432, 433, 434.
Alternatively
to laying yarn down in the connectors paths, the yarns may be cut at the end
of an
arc and reattached to the mandrel at the beginning of the next arc. In this
way
yarn from succeeding subgroups would not accumulate at the connector paths.
Subgroups in the other directions may be laid down by teaching or
programming the robot along those paths, or in certain symmetric cases such as
this one, by rotating the mandrel about the z-axis.441 by the desired angle
435 and
repeating the program for path 410. Generally foi non-symmetrical shapes,
however, subsequent subgroups would be taught or programmed independently
since they are not simple translation offsets of the path= 4.10 for the first
laid
subgroup of the first group.
Yarn tension control is important during the dispensing along these paths
to maintain the yarn onto the generally curved path. Excessive tension will
cause
the yam.to deviate significantly from the desired path. --Preferably; a
teniporary
aid, either mechanical or adhesive, is used on the mandrel surface and on
yarns in
preceding subgroups to maintain the yam on the desired path. For instance, a
pressure-sensitive adhesive may be sprayed on the mandrel at the start and on
each
succeeding subgroup of yarn to aid in holding the applied yarns in place. To
further assist, a roller may be used on each subgroup to press the adhesive
covered
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yarns onto the mandrel and each other. These aids may remain in the final
fabric.
or be removed after the final connecting step.
The final step is to connect the final subgroup to be laid down in each
region, the top subgroup, with the first subgroup to be laid down in that
region.
the bottom subgroup. at the crossing points between the two subgroups. In
general, the top and bottom subgroups are arranged to be crossing one another.
Since each group does not necessarily cover the entire surface (but covers a
substantial portion greater than 1/3 and preferably greater than 1/2 of the
fabric
area), the top and bottom subgroups may be different subgroups from different
groups in the triaxial and biaxial regions. It is also possible to connect
yams in
the top subgroup with yarns in the bottom subgroup by connecting the top and
bottom yarns to yarns in intermediate subgroups at a plurality of spaced
locations,
rather than making precise direct connections between the top and bottom
subgroup yarns. Such a process was discussed when describing the flat fabric
structures.
In general terms, the above process makes a three dimensional, shaped,
interlaced, fabric structure, comprising:
a stack of a first plurality of subgroups, a second plurality of
subgroups, and a third plurality of subgroups, each subgroup having yams
spaced
apart to define a sparse covering of a fabric area, the yams generally
parallel, and
the yarns following a curved path in space;
the stacked subgroups arranged in a predetermined array with
reference to a common axis and a common reference plane perpendicular to said
axis;
the first subgroups arranged at a first angle with respect to said
reference plane and positioned at a first rotational angle about said axis,
the
second subgroups arranged at a second angle with respect to said reference
plane
and positioned at a second rotational angle about said axis, the third
subgroups
arranged at a first angle with respect to said reference plane and positioned
at a
third rotational angle about said axis, wherein the yams in any one of the
first,
second and third subgroups cross the yams in another of the first, second and
third
subgroups;
within each first, second and third plurality of subgroups, the yams of
one subgroup are offset from the yarns of the other subgroups to thereby form
a
group of yams for each of the respective subgroups, the group for any
respective
subgroups densely covering a fabric area;
the top subgroup in the stack is connected to the bottom subgroup in
the stack to thereby form a three-dimensional, shaped interlaced, fabric
structure.
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The fabric of the invention can also be wound on a composite rectangular
parallelepiped form to make biaxial three dimensional fabric structures
referring
to Figures 19A-D. Figure 19A shows a composite rectangular mandrel 300 that is
the general configuration of the desired shape, which in this case would be a
short
sleeve shirt. The mandrel may be a solid form made of connected rectangular
parallelepiped pieces, such as torso piece 3 10, and an shoulder piece 3 12
detachably connected with rods or screws or clamps (not shown). The mandrel
may also be a frame structure outlining the shape, or an
expandable/collapsable
structure to assist in removal of the finished fabric.
To handle the form, and rotate it around three axes for ease of fabric
forming, there are two pairs of gripper devices arranged in a framework (not
shown) surrounding the mandrel. A suitable framework for supporting the
grippers for rotation and translation and a variable speed motor for driving
them
can be provided by one skilled in machinery art and will not be discussed
further
here. Referring to Figure 19A, a first pair of opposed grippers 302 and 303
are
arranged to support the mandrel 300 for rotation about first mandrel axis 314.
A
second pair of opposed grippers 304 and 305 are arranged for supporting the
mandxe1300 for rotation about second mandrel axis 316. Referring to Figure
19B,
the mandrel can be reoriented 90 degrees from the position in Figure 19A and
the
second pair of opposed grippers 304 and 305 are arranged for supporting the
mandrel 300 for rotation about third mandrel axis 318. Each pair of grippers
are
moveable rotationally and axially toward and away from one another; that is,
gripper 302 can rotate and move axially toward and away from gripper 303, and
gripper 303 can also rotate and move axially toward and away from gripper 302.
In Figure 19A, grippers 304 and 305 have both moved axially to engage
the ends of mandrel piece 312 to rotate mandrel 300 about axis 316. The face
of
each gripper of the pair engaging the ends of the mandrel may be covered with
a
resilient high friction surface to securely grip the mandrel and any fabric
laid
there, or they may be covered with pins or needles to engage the ends of the
mandrel and fabric. There is a first yarn guide 306 for winding a first yarn
307
onto mandrel 300 about axis 316. The guide 306 is supported and propelled by a
rotating threaded rod 320 for transverse motion parallel to axis 316. The rod
is
supported by simple supports and driven by a variable speed motor not shown.
The rotation of the mandrel grippers 304/305 and rod 320 are coordinated by a
controller 321 so in one revolution of grippers 304/305 the yarn 307 moves one
cell distance 322 along the mandrel 300 to lay down a first subgroup of yarn
in the
direction 324 on the mandrel. After covering the mandrel with one subgroup of
yarn, the winding stops and grippers 302 and 303 engage the mandrel and
grippers
304 and 305 retract. Grippers 302/303 rotate the mandrel 90 degrees and stop,
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grippers 304 and 305 re-engage the mandrel. and grippers 302 and 303 retract.
This places the mandrel in the position shown in Figure 19B.
Referring to Figure 19B, grippers 304 and 305 have both moved axially to
engage the sides of mandrel piece 312 to rotate mandrel 300 about axis 318.
The
first yarn guide 306 is now arranged for winding yarn 307 onto mandrel 300
about
axis 318. The guide 306 will now be supported and propelled by the rotating
threaded rod 320 for transverse motion parallel to axis 318. The rotation of
the
mandrel grippers 304/305 and rod 320 are coordinated so in one revolution of
grippers 304/305 the yarn 307 moves one cell distance 332 along the mandrel
300
to lay down a first subgroup of yarn in the direction 334 on the mandrel.
When winding yarn about axis 318 of mandre1300, in order to lay down
the yarn on the mandrel in the underarm of the shirt form, a special yarn
deflector
is used that is best seen in Figure 19D, which is a side view of the mandrel
and
grippers shown in Figure 19B. As the mandrel 300 is rotated, at one point the
yarn 307 lies along dashed path 336 and across underarm 338 of the mandrel. At
this point, a yarn deflector 340 moves from a retracted position 342 to an
extended
position 344 and tucks the yarn into the underarm where an insert 346 having
temporary fasteners, such as hooks or adhesive, engages the yarn and holds it
in
position in the underarm. The deflector 340 then quickly returns to the
retracted
position 342 and the mandrel continues rotating and yarn continues being Iaid
down. As the mandrel continues rotating and the other underarm 348 comes into
the vicinity of the deflector 340, this cycle is repeated and the deflector
tucks the
yarn into underarm 348 where it is engaged by temporary fastener insert 350.
Referring to Figure 19C, grippers 302 and 303 have both moved axially to
engage the ends of mandrel 300 to rotate it about axis 314, and grippers 304
and
305 have retracted. The face of each gripper of the pair 302/303 engaging the
ends of the mandrel may be covered with a resilient high friction surface to
securely grip the mandrel and any fabric laid there, or they may be covered
with
pins or needles to engage the ends of the mandrel and fabric. There is a
second
yarn guide 326 for winding a second yarn 328 onto mandrel 300 about axis 314.
The guide 326 is supported and propelled by a rotating threaded rod 330 for
transverse motion parallel to axis 314. The rotation of the mandrel grippers
302/303 and rod 330 are coordinated so in one revolution of grippers 302/303
the
yarn 328 moves one cell distance 333 along the mandrel 300 to lay down a first
subgroup of yarn in the direction 335 on the mandrel.
To make a densely covered mandrel using four subgroups of yarn in each
of the three directions, the following sequence of operations is preferred,
although
other sequences are possible:
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- the mandrel is gripped by grippers 304/305 as in Figure 19B and the
yarn 307 is attached to a corner 352 of the mandrel;
- grippers 304/305 rotate mandrel 300 about mandrel axis 318 and yarn
307 is traversed by moving guide 306 to achieve a cell distance of
332;
- the yarn is stopped at about position 354 and is cut and attached to the
mandrel;
- grippers 302/303 engage the mandrel 300 and grippers 304/305 retract
as in Figure 19C and the yarn 328 is attached to a corner 356 of the
mandrel;
- grippers 302/303 rotate mandrel 300 about mandrel axis 314 and yarn
328 is traversed by moving guide 326 to achieve a cell distance of
333;
- the yarn 328 is stopped at about position 358 and is cut and attached to
the mandrel;
- grippers 304/305 engage the mandrel 300 and grippers 302/303 retract
as in Figure 19A and the yam 307 is attached to a corner 360 of the
mandrel;
- grippers 304/305 rotate mandrel 300 about mandrel axis 316 and yam
307 is traversed by moving guide 307 to achieve a cell distance of
322;
- the yarn 307 is stopped at about position 362 and is cut and attached to
the mandrel;
- grippers 302/303 engage the mandrel and grippers 304/305 retract and
grippers 302/303 rotate mandrel 300 to the position in Figure 19B;
- grippers 304/305 engage the mandrel and grippers 302/303 retract as
in Figure 19B and the yarn 307 is attached near corner 352 except at
an offset position of one, two, or three yarn diameters from position
352;
- yarn is wound once more about mandrel axis 318 at the offset position
and is cut and attached near position 354;
- grippers 302/303 engage the mandrel 300 and grippers 304/305 retract
as in Figure 19C and the yam 328 is attached near corner 356 of the
mandrel except at an offset position of one, two, or three yam
diameters from position 356;
- yam is wound once more about mandrel axis 314 at the offset position
and is cut and attached near position 358;
- grippers 304/305 engage the mandrel 300 and grippers 302/303 retract
as in Figure 19A and the yarn 307 is attached to a near corner 360 of
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the mandrel except at an offset position of one. two, or three yarn
diameters from position 360;
- yarn is wound once more about mandrel axis 316 at the offset position
and is cut and attached near position 362;
- the above process continues with succeeding yarns wound about a
given mandrel axis being offset from preceeding yarns until the
mandrel is densely covered with the four subgroups of yarns in the
three directions. On any given face of the mandrel, there will be yarns
in only two directions, thereby forming a biaxial fabric structure on
each face;
- on each face of the mandrel, the outermost subgroup of yarns are
connected to the innermost subgroup of yarns where the outermost
yams cross the innermost yams, by application of an ultrasonic horn
only at the crossovers, with the mandrel acting as an ultrasonic anvil.
Alternatively, a plurality of spaced ultrasonic horns could be traversed
over each face of the mandrel in a diagonal path relative to the
directions of the yarns on that face, similar-to what was taught with the
flat fabric structures;
- after connecting is complete, the mandrel can be removed from the
grippers and the sleeve ends of the fabric shirt can be cut open and
mandrel piece 312 disengaged from piece 310 and piece 312 slid out
of the cut sleeve opening;
- the waist end of the fabric shirt can be cut open and mandrel piece 310
slid out of the cut waist opening;
- the cut ends of fabric may be removed or may be used to form cuffs on
the sleeves and waist of the shirt.
Using the above technique, three dimensional fabric articles of clothing
can be made easily using relatively simple mandrels. By winding in a simple
manner about three axes of the mandrel, a bidirectional yarn, three
dimensional
fabric can be made without cutting and seaming separate fabric pieces as in
the
prior art. This produces unique articles of fabric clothing without seams.
Figure 19E illustrates the yarn pattern as seen on a corner of the mandrel at
the end of a sleeve at corner 364 as also seen in Figure 19A. The mandrel axes
are
labelled at 366. Several of the first subgroup of yams laid down about the
mandrel axis 318 are labelled 1; several of the second subgroup of yams laid
down about the mandrel axis 314 are labelled 2. Several of the third subgroup
of
yams laid down about mandrel axis 316 are labelled 3. The subgroups are
labelled in the order in which they are laid on the mandrel. For subgroups
above
three, only one yarn in the subgroup is labelled to illustrate the pattern
that
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develops on the mandrel. The group of yarns laid down about mandrel axis 318
are labeled with the number I for the first subgroup. the number 4 for the
fourth
subgroup, the number 7 for the seventh subgroup. and the number 10 for the
tenth
subgroup. The group of yarns laid down about mandrel axis 314 are labeled with
the number 2 for the second subgroup. the number 5 for the fifth subgroup, the
number 8 for the eighth subgroup, and the number 11 for the eleventh subgroup.
The group of yarns laid down about mandrel axis 316 are labeled with the
number
3 for the third subgroup, the number 6 for the sixth subgroup, the number 9
for the
ninth subgroup, and the number 12 for the twelfth subgroup. Although yarns are
wound about three axes of the mandrel, on mandrel face 368, the yarns form a
biaxial structure; on mandrel face 370, the yarns form a biaxial structure;
and on
mandrel face 372, the yarns form a biaxial structure.
Points 374 and 376 on face 368 show some typical bond points between
the outermost subgroup 11 and the innermost subgroup 1. Points 378 and 380 on
mandrel face 370 show some typical bond points between the outermost subgroup
12 and the innermost subgroup 2. Points 382 and 384 on mandrel face 372 show
some typical bond points between the outermost subgroup 12 and the innermost
subgroup 1. In general terms, the process just described for forming an
interlaced
shaped fabric structure comprises:
(a) providing a rectangular parallelipiped fabric support surface
rotatable in three orthogonal axes thereby defining three orthogonal yarn
laydown
directions X, Y, and Z;
(b) laying down a first subgroup of yarns to sparsely cover the
support surface in said X direction;
(c) laying down a second subgroup of yarns to sparsely cover the
support surface in said Y direction and form a stack with the yarns in the X
direction;
(d) laying down a third subgroup of yarns to sparsely cover the
support surface in said Z direction and form a stack with the yarns in the X
direction and the Y direction;
(e) repeating the laying down and stacking for each of the first,
second and third subgroups and offsetting the yarns in subsequent subgroups
from
all yarns in previous subgroups until each of the plurality of subgroups forms
a
group of yarns in the respective direction for that subgroup that densely
covers the
mandrel surface;
(f) connecting the top subgroup in the stack to the bottom
subgroup in the stack thereby forming a shaped interlaced fabric structure.
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EXAMPLES
EXAMPLE 1
A fabric structure was made from a sheath/core yarn of 710 total denier
which included a 400 denier core of continuous multifilaments of nylon 6,6
flat
yarn having 6 denier per filament. The core was wrapped with a sheath of
staple
fibers comprised of a nylon 6.6 copolymer containing 30% by weight of units
derived from MPMD (2-methyl pentamethylene diamine) which had a melt point
lower than the core polymer. The staple fibers being wrapped on the core were
a
sliver of 1.5 inch staple length and 1.8 dpf. This yarn was made on a "DREF 3
Friction Spinning Machine" manufactured by Textilemachinenfabrik Dr. Emst
Fehrer AG of Linz, Austria. The fabric structure had 16 subgroups arranged as
in
Figure 2A and was wound on a device as in Figure 11 B. The fabric cell
distance
contained 8 yams. The bonds were made circumferentially using an ultrasonic
generator made by the Dukane Co., model #351 Autotrak, which was operated at
40kHz with a force against the mandrel of about 4-5 lbs. The horn speed along
the mandrel was such that about 0.2 joules per bond of ultrasonic energy was
applied to the fabric. The bond paths were spaced about 0.2 inches apart and
the
horn tip was about 0.1 inch wide and 0.75 inches long with a slightly concave
surface across the 0.1 dimension for about 0.5 inches of the length. At the
concave end of the bonding surface, there was a radius to eliminate the
leading
corner and the concavity followed the radius. The horn did not make full
contact
along the 0.75 inch dimension due to the radius of the mandrel. The horn made
highly bonded regions at the edges of the concave surface. It is believed that
an
improvement in bonding would be realized with a narrower horn of about
0.04 inches width with a flat bonding surface instead of a concave one.
After bonding, the fabric was removed from the mandrel and was given a
tensile test in a direction parallel to one group of the yams. The maximum
theoretical tensile strength of this fabric without any bonds was computed to
be
148 lbs/inch by multiplying the yarn strength of 4.6 lbs by 32 yams per inch.
The
bonded fabric of the invention had an actual grab strength of about 120
lbs/inch.
It is believed that the sheath/core yam bonded by primarily melting the lower
melting sheath, while the core filaments remained essentially undisturbed, so
the
strength of the fabric was not significantly diminished due to bonding. In
another
test of a fabric made with 630 denier nylon 6,6 multifilament yarn without the
low
melting sheath structure, the theoretical unbonded fabric tensile strength was
370 lbs/inch, and the actual bonded grab strength was 120 lbs/inch. This
indicated
a significant reduction in strength for the bonded multifilament yarn compared
to
the strength reduction with the bonded low melting sheath. The low melting
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sheath offers a significant strength improvement when ultrasonic bonding is
used
for connecting the yarns.
EXAMPLE 2
A fabric structure was made with limited permeability by inserting film
sheets in the fabric structure during fabrication. A sample was made using 630
denier continuous multifilament yarn wound on the device of Figure 11 B and
bonded with the ultrasonic system described in Example 1. The fabric cell
distance contained 8 yarns. The film sheet was about a 3-5 mil thick Bynel
polypropylene film. The fabric was made by first laying two subgroups on the
mandrel followed by a sheet of film, followed by 12 subgroups of yarn,
followed
by another sheet of film, followed by 2 subgroups of yarn. The fabric was then
bonded in the manner of Example 1. The fabric was removed from the mandrel
and when examined by blowing air at the fabric, it was found that very little
air
passed through the fabric and this occurred only at the bonded region.
EXAMPLE 3
A reinforced fabric structure was made by adding a sheet of spunbonded
nonwoven fabric in the structure during fabrication. The yarn was the same
yarn
as in Example 2. The nonwoven was a low melt copolymer polyamide weighing
about 1 oz/sq yd. The fabric was made in the manner of Example 2. Fourteen
subgroups of yarn were wound on the mandrel, the nonwoven sheet was laid on
the mandrel and two subgroups of yam were wound over the nonwoven. The
fabric was bonded in the manner of Example 1. The fabric was removed from the
mandrel and was found to have improved strength and reduced deflection in the
bias direction.
EXAMPLE 4
A preform for a composite panel was made using a non-thermoplastic yarn
and sheets of thermoplastic film. The yarn was 840 denier continuous
multifilament aramid (KevlarTM) flat yarn. The film sheet was a 2-3 mil thick
polyester film. The fabric was made in the manner of Example 2. Two subgroups
of yarn were wound on the mandrel, followed by a film sheet, followed by four
subgroups of yarn, followed by a film sheet, followed by four subgroups of
yam,
followed by a film sheet, followed by four subgroups of yarn, followed by a
film
sheet, followed by two subgroups of yam, for a total of 16 subgroups of yam
and
four film sheet. The film made up about 15% by weight of the fabric. The
fabric
was bonded in the manner of Example 1. The fabric was removed from the
mandrel and was found to have adequate integrity for handling as a composite
preform.
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EXAMPLE 5
A fabric was made with a cotton sliver web inserted durine fabrication to
make a fabric that was soft to the touch. The yarn was the same as used in
Example 2. The cotton was a sliver formed into a web of about 8 x I 1 inches
and
about 0.5 oz/sq yd weight. The fabric was made in the manner of Example 2.
Eight subgroups of yarn were wound on the mandrel, followed by the cotton web.
followed by eight subgroups of yarn. The fabric was bonded in the manner of
Example 1. The fabric was removed from the mandrel and was found to be a soft
coherent structure, but it could be separated along the cotton web. It is
believed
that the integrity of the structure could be improved by adding some nylon 6,6
staple, or a low melting copolymer nylon 6,6 staple, to the cotton sliver by
blending before making the cotton web. It is believed this would improve the
bonding of the nylon yams together through the cotton web.
EXAMPLE 6
A fabric structure was made with natural fibers as the inner subgroups and
thermoplastic fibers as the first and last subgroups. The structure used 8
feed
yams with 28 subgroups. The natural cotton yams had a denier of 1600, while
the
thermoplastic yarns were nylon 6,6 of 630 total denier. The laydown sequence
was as follows: first subgroup was nylon 6,6; next 26 subgroups were cotton;
and
the last subgroup was nylon 6,6. The structure was then bonded by tracing the
path of each yam in the last subgroup with the ultrasonic horn, bonding along
the
length to bond each intersection of the first and last subgroup.
EXAMPLE 7
A fabric structure was made of DacronTM yams (1.3 dpf, 255 total denier)
consisting of repeating groups of subgroups. The fabric consisted of a two-
layered fabric structure where one layer is a stack of two groups of subgroups
that
form a densely covered area, and the other layer is an identical group of
subgroups
that form a second densely covered area. The resulting fabric had a basis
weight
equivalent to a fabric consisting of the same number of total subgroups that
were
parallel but offset with no subgroups on top of one another, but gave a
bulkier feel
and appearance.
For comparison, three separate fabrics were made to explore the effect of
different fabrication techniques on the bulk of the finished fabric. All
fabrics were
made using the above yarn placed in 16 guides in the ring of the device of
Figure 11 B. All fabrics were bonded the same using the circumferential
bonding
process of Example 1. Fabric A was comprised of two groups of yarns having a
combined total of 18 subgroups, and with 9 yams per cell space to make a
1 oz/yd2 fabric. Fabric B was comprised of two groups of yarns having a
combined total of 36 subgroups, and with 18 varns per cell space to make a
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2 oz/yd2 fabric. The yarns in Fabric B were more closelv packed in the same
cell
space as were the yarns of Fabric A. Fabric C was comprised of a two-layered
fabric structure where a first layer like Fabric A was formed, and then a
second
layer like Fabric A was formed on top of the first layer to make a fabric with
a
combined total of 36 subgroups of yarn to make a 2 oz/yd2 fabric. The two
layers
were bonded only after both layers were wound onto the mandrel. The 3 fabrics
were removed from the mandrel and were examined visually and by hand for
bulk. Fabric A seemed to have the least bulk; Fabric C had the most bulk;
Fabric B had a bulk level between that of Fabric A and Fabric C. It was
surprising
that packing more yarn into a cell space produced more bulk (comparison of
Fabric A and Fabric B) and that a two-layered structure with the same quantity
of
yarn produced more bulk (comparison of Fabric B and Fabric C). Since all
fabrics
were bonded the same, this indicated that yam packing and layering can also be
used to control bulk.
EXAMPLE 8
Miscellaneous samples were made using two ply, bulked, continuous
filament (BCF) nylon 6,6 carpet yarn of 2500 denier and 19 denier per
filament;
and using staple nylon 6,6 carpet yarn. The bonding energy for this large
denier
yarn may be as much as 1-2 joules of ultrasonic energy per yam crossing.
Miscellaneous samples were also made using 150 denier, 0.75 denier per
filament
textured polyester yarn. Flat and three dimensional samples were also made
manually using 1/8-1/4 inch diameter rope or cord and plastic ties for
connecting
the yarns where the outermost subgroups cross.
The fabric structure of the invention can be made by a variety of ways,
including by manual and automated means, either in a batch or continuous
manner, and using a wide variety of yarns and connecting means.
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