Information
-
Patent Grant
-
H1974
-
Patent Number
H1,974
-
Date Filed
Tuesday, August 11, 199826 years ago
-
Date Issued
Tuesday, July 3, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Jordan; Charles T.
- Baker; Aileen J.
Agents
-
-
US Classifications
Field of Search
US
- 139 383
- 139 20
- 139 408
- 139 425
- 034 116
- 034 123
- 162 358
- 442 181
- 442 268
- 442 203
- 442 206
- 442 208
-
International Classifications
- D03D1500
- D03D1300
- D03D2300
- B32B526
- D03C1300
-
Abstract
A papermaker's fabric having a system of primary machine direction yarns which form seaming loops at each end of the fabric and a system of secondary machine direction yarns. A system of cross-machine direction yarns are interwoven with the primary and secondary systems of machine direction yarns in a weave pattern that provides adjacent balancing yarns that maintain the seam loops in substantially vertical alignment.
Description
BACKGROUND OF INVENTION
1. Field of the Invention
The present invention generally relates to a woven fabric for use in a paper, cellulose or board manufacturing machine that is seamed by interlocking loops along each of two fabric edges to form an endless woven fabric.
2. Description of the Prior Art
As will be known to those skilled in the art, papermaking machines generally include three sections which are referred to as the forming, press and dryer sections. A felt is generally employed to transport the formed, wet sheet through the press and dryer sections of the papermaking equipment. The felt must be particularly adapted to specific conditions encountered in papermaking.
Typically, such felts include a supporting base, such as a woven fabric, and a paper carrying or supporting layer fixed to the base. The paper carrying or supporting layer is generally softer and smoother than the base layer. The support layer is often a non-woven batt material which has been affixed to the base and has homogeneous characteristics as to permeability, compaction and drainage. Slight irregularities or imperfections in the support layer are undesirable in virtually all papermaking operations. Inconsistencies in the felt thickness, gauge or weight can cause undesirable vibrations during operation of the equipment.
In press fabrics, the batt material is often anchored to a base fabric which is provided with end loops to join the fabric. Many of these fabrics are woven as endless loops in patterns that provide the seaming loops at each end of the fabric. Standard woven loop base constructions frequently include two layers of weft yarns in a low density, symmetrical construction. However, these base fabrics typically provide limited batt anchorage and sheet support due to low surface contact area. This necessitates the use of a third, topical laminate structure, having a higher density of weft or warp yarns. The laminate is generally bound to the primary base by means of filament entanglement during a post weaving needling process. This process can be costly and time consuming.
Another problem associated with endlessly woven seamed fabrics is seaming of the fabric. Standard endlessly woven loop seam products are made with stacked weft pairs, formed by looping around a forming monofilament. A common problem associated with this type of loop formation is non-uniform loop alignment, both in the vertical and horizontal axis, when the forming wire is removed. This misalignment creates a seam that is difficult to mesh.
FIGS. 1-3
show representative loop misalignments experienced in common prior art endlessly woven seams. Generally, as a loom weaves the loops in an endless weave construction, it naturally offsets the returning weft position slightly from its outgoing weft position. It is possible to maintain the weft yarns in a stacked relationship throughout the fabric through the balanced weave of the warp yarns. However, the last warp yarn
2
does not have a balancing yarn on one of its sides and, therefore, an unbalanced crimp force is applied to the weft yarns in the loop area, as shown by the arrows in FIG.
2
. As a result, the two weft yarn passes which form each loop are not balanced by warps and the loops tend to be misaligned.
A similar misalignment of the loops occurs in flat woven fabrics wherein the tie back portion of the warp yarn is offset from the outgoing portion of the warp yarn during loop formation.
The present invention combines two high density structures during the weaving process, with the primary base construction being used to form endless type seam loops. This is achieved by means of unique weave patterns that stitch in a higher density weft layer of yarns to provide greater batt anchorage and maintain a stacked weft arrangement in the base for uniform, vertically aligned, loop formation.
SUMMARY OF THE INVENTION
The present invention generally relates to a papermaker's fabric of a type having a system of primary machine direction yarns which form seaming loops at each end of the fabric. The fabric also includes a system of secondary machine direction yarns and a system of cross-machine direction yarns. The cross-machine direction yarns are interwoven with the primary and secondary systems of machine direction yarns in a weave pattern that provides adjacent balancing yarns that maintain the seam loops in substantially vertical alignment. A method of forming the papermaker's fabric is also provided.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a top plan view of prior art end loops.
FIG. 2
is an elevation view of the prior art end loops along the line
2
ā
2
in FIG.
1
.
FIG. 3
is a side elevation view of the prior art end loops along the line
3
ā
3
in FIG.
1
.
FIG. 4
is a schematic perspective view of a portion of the fabric according to the present invention.
FIG. 5
is an end elevation view of a portion of the fabric according to the present invention.
FIG. 6
is a schematic view showing the weaving progression of the weft yarns.
FIG. 7
shows a position of the weft yarn after the fabric of
FIG. 6
is removed from the loom and opened.
FIG. 8
is a cross section taken along the line
8
-
8
in FIG.
6
.
FIG. 9
is a weave pattern diagram for the preferred embodiment of the base fabric of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment will be described with reference to the drawing figures wherein like numerals represent like elements throughout.
Referring to
FIGS. 4 and 5
the preferred fabric
100
generally comprises a base fabric
110
with batt material
112
attached thereto. The base fabric
110
comprises three layers of machine direction (MD) yarns
114
,
116
and
118
interwoven with a system of cross-machine direction (CMD) yarns
120
. MD layers
114
and
116
are woven in stacked pairs and form seam loops
122
at each end of the base fabric
110
. The third layer MD yarns
118
extend above MD layers
114
and
116
and are substantially parallel thereto. In the preferred embodiment, two third layer MD yarns
118
are provided for every pair of stacked MD yarns
114
and
116
.
The fabric
110
is preferably endless woven using a two shuttle loom. The first shuttle weaves the lower and intermediate MD layers
114
and
116
and the second shuttle weaves the upper MD layer
118
. As shown in
FIG. 6
, the base fabric
110
is woven on the loom doubled over upon itself. That is, the base fabric
110
is woven with an upper weaving layer
130
and a lower weaving layer
132
which are opened after weaving as shown in
FIG. 7
to provide a base fabric
110
which is approximately twice the length of the fabric on the loom. Reference to position of the yarns relative to one another is the relative position after the fabric is opened, unless otherwise specified.
The CMD yarns
120
interweave with all three MD yarn layers
114
,
116
and
118
. As shown in
FIGS. 5 and 8
, the CMD yarns
120
preferably include two CMD subsystems
120
a, b.
Upper CMD subsystem yarns
120
a
weave exclusively with the middle and upper MD layers
116
and
118
and the lower CMD subsystem yarns
120
b
weave exclusively with lower and middle MD layers
114
and
116
.
The base fabric
110
has a weave which preferably repeats on sixteen (16) CMD yarns and thirty-two (32) MD yarns. As shown in
FIG. 8
, CMD yarns
1
,
4
,
5
,
8
,
12
,
13
and
16
make up the upper CMD subsystem
120
a
and CMD yarns
2
,
3
,
6
,
7
,
10
,
11
,
14
and
15
make up the lower CMD yarn subsystem
120
b.
The upper CMD subsystem yarns
120
a
weave exclusively with the intermediate and upper layer MD yarns
116
and
118
. Each upper subsystem CMD yarn
120
a
preferably weaves, relative to the intermediate and upper MD layers
116
,
118
, over two, under four, over two and under four in a given repeat. For example, as shown in
FIG. 8
, warp yarn
16
weaves over MD yarns
4
and
5
, under MD yarns
8
,
12
,
13
and
16
, over MD yarns
20
and
21
, and under MD yarns
24
,
28
,
29
and
32
. The lower CMD subsystem yarns
120
b
preferably weave in a standard āNā pattern relative to the lower and intermediate MD layers
114
,
116
. For example, CMD yarn
14
weaves over weft yarns
5
and
6
, between MD yarns
13
and
14
, under MD yarns
21
and
22
, and between MD yarns
29
and
30
in a given repeat.
As can be seen in
FIG. 8
, the intermediate MD yarns
116
interweave with both CMD subsystem layers
120
a,b,
to integrate the fabric. This weave pattern integrates the three MD layers
114
,
116
,
118
while maintaining the seam loops
122
in substantial vertical alignment. Loop alignment is maintained by the balanced weave of the end upper CMD yarn
120
a
which counterbalances the unbalanced crimp force of the end lower CMD yarn
120
b.
The fabric
110
may be flat woven or endless woven. The preferred method of endless weaving the fabric
110
will be described with reference to
FIGS. 6-9
.
FIG. 9
shows a weave pattern diagram for the base fabric
110
wherein the filled boxes indicate where a warp yarn or cord is over a respective weft yarn. Weaving of the fabric will be described with reference to positioning of the cords only, but it will be understood that the warp heddles are positioned for each shuttle pass in accordance with the desired weave pattern.
The base fabric
110
is preferably woven using a two shuttle loom. Referring to
FIGS. 6-9
, the first shuttle is thrown across the loom with all of the cords LC, RC
1
, and RC
2
lowered. The right cord RC
1
is then raised and the first shuttle is thrown back across the loom, thereby looping around the end right cord RC
1
. This first shuttle pass is depicted as 1 and 2 in FIG.
6
. The end right cord RC
1
remains raised and the second shuttle is thrown across the loom from the side opposite the first shuttle. The three left cords LC, RC
1
, and RC
2
are raised as the second shuttle is thrown back across the loom. This second shuttle pass is depicted as
3
and
4
in FIG.
6
. The first shuttle then weaves weft yarns
5
and
6
. The left cord LC and the inner right cord RC
2
are raised and the first shuttle is thrown across the loom. All three cords LC, RC
1
, and RC
2
are raised and the first shuttle is thrown back across the loom, thereby weaving weft yarns
5
and
6
in the lower fabric layer and looping around the end right cord RC
1
. To weave weft yarn
7
, both right cords RC
1
and RC
2
are raised and the second shuttle is thrown across the loom. The left cord LC and the end right cord RC
1
are raised and the second shuttle is thrown back across the loom to weave weft yarn
8
. At the transition of each shuttle back to the upper weaving layer
130
, a turning fold is formed as is known in endless weaving. The shuttles weave in the same pattern across the width of the fabric
110
with the heddles being adjusted to provide the desired weave pattern.
To open the fabric
110
after the desired width is formed, the right end cord RC
1
is removed and the left and inner right cords LC and RC
2
are replaced with yarns consistent with the remainder of the warp yarns. Removal of RC
1
provides the loops
122
at both ends of the fabric. As can be seen in
FIG. 6
, in the preferred weaving arrangement, the upper weft yarn passes
3
,
4
and
7
,
8
will be joined at the loop end of the woven fabric
110
as represented at
150
. To facilitate opening of the fabric
110
, these weft yarns are cut at
150
. It will be understood that various other weaving patterns can be used which will leave these ends separate, thereby eliminating the need for cutting of the upper weft layer yarns.
As can be seen in
FIG. 9
, the upper layer MD yarns
118
substantially increase the number of entanglement points on the upper surface of the base fabric
110
. The increase in entanglement points allows greater adherence of the batt material
112
to the base fabric
110
.
Claims
- 1. An improved papermaker's fabric of a type having a system of primary machine direction (MD) yarns which form seaming loops at each end of the fabric, the improvement characterized by:a system of secondary MD yarns that at least equal in number the number of primary MD yarns; and a system of cross-machine direction yarns (CMD) interwoven with the primary and secondary systems of MD yarns in a weave pattern that provides adjacent balancing yarns that maintain the seam loops in substantially vertical alignment.
- 2. The fabric according to claim 1 wherein the primary MD yarn system includes stacked lower and middle layer MD yarns and the secondary MD yarn system includes a single layer of upper MD yarns.
- 3. The fabric according to claim 2 wherein the CMD yarn system includes two sub-systems, the first CMD sub-system yarns weaving exclusively with the upper and middle layer MD yarns and the second CMD sub-system yarns weaving exclusively with the middle and lower layer MD yarns.
- 4. The fabric according to claim 3 wherein each first CMD sub-system yarn weaves in a repeat pattern of over two, under four, over two and under four relative to the upper and middle layer MD yarns.
- 5. The fabric according to claim 3 wherein each second CMD sub-system yarn weaves in a repeat pattern of over, between, under, between relative to the stacked pairs of middle and lower layer MD yarns.
- 6. The fabric according to claim 1 wherein the fabric repeats on sixteen CMD yarns.
- 7. The fabric according to claim 1 wherein the fabric repeats on thirty-two MD yarns.
- 8. The fabric of claim 1 wherein the fabric is flat woven.
- 9. The fabric of claim 1 wherein the fabric is endless woven.
- 10. The fabric of claim 9 wherein the fabric is woven using a two shuttle loom.
- 11. The fabric of claim 1 wherein batt material is attached thereto.
- 12. The fabric according to claim 3 wherein the first CMD sub-system yarns weave in repeat pattern of over one, under one with respect to the middle layer MD yarns.
US Referenced Citations (6)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0262467 |
Apr 1988 |
EP |
9211412 |
Jul 1992 |
WO |
9927181 |
Jun 1999 |
WO |