U.S. patent number RE33,195 [Application Number 06/170,403] was granted by the patent office on 1990-04-10 for fabrics for papermaking machines.
This patent grant is currently assigned to Asten Group, Inc.. Invention is credited to Frank Biasone, Robert L. McDonald.
United States Patent |
RE33,195 |
McDonald , et al. |
April 10, 1990 |
**Please see images for:
( Certificate of Correction ) ** |
Fabrics for papermaking machines
Abstract
A fabric, adapted for use in a belt of a papermaking machine, is
formed of interwoven machine direction wrap and cross-machine
direction shute type strands, at least the shute strands being
woven in a repetitive pattern of passing over at least three
adjacent warp strands and then passing under at least two adjacent
warp strands so as to form a 3/2 type weave pattern.
Inventors: |
McDonald; Robert L. (Appleton,
WI), Biasone; Frank (Appleton, WI) |
Assignee: |
Asten Group, Inc. (Charleston,
SC)
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Family
ID: |
26866047 |
Appl.
No.: |
06/170,403 |
Filed: |
July 21, 1980 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
931290 |
Aug 4, 1978 |
04184519 |
Jan 22, 1980 |
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Current U.S.
Class: |
139/425A;
139/383A; 162/903 |
Current CPC
Class: |
D21F
1/0027 (20130101) |
Current International
Class: |
D03D
11/00 (20060101); D21F 1/00 (20060101); D03D
015/00 (); D21F 001/10 (); B01D 039/10 () |
Field of
Search: |
;139/425A,425R,383A,42C
;162/DIG.1,360 ;245/2,8 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Grammar of Textile Design, by H. Nisbet; 3rd Edition, Revised and
Enlarged, D. Van Nostrand Co., Inc. New York, pp. 52 & 56.
.
Monel Wire Screen and Filter Cloth-Bulletin H-3 6M 7-38, The
International Nicker Co., Inc., 67 Wall St., New York, N.Y., p. 7
relied on. .
Textile Design and Colour, by William Watson, published by
Longmans, Green & Co., 39 Paternoster Row, London 1912, pp. 5-6
relied on..
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Primary Examiner: Kee Chi; James
Attorney, Agent or Firm: Volpe and Koenig
Claims
We claim:
1. A papermaking fabric comprising interwoven first machine
direction and second cross-machine direction strands, the
improvement in which the fabric constitutes a five-shed weave
pattern wherein at least said second strands are woven in a
repetitive pattern of passing .[.at cross-over points.]. under at
least three adjacent first strands and then passing .[.at
cross-over points.]. over at least two next adjacent first strands
.Iadd.and adjacent parallel second strands are offset one strand in
the repetitive pattern .Iaddend.so as to form a 2/3 .Iadd.twill
.Iaddend.type weave pattern, said second strands at one surface of
the fabric being exposed .[.between said cross-over points
thereat.]. as knuckles each having a length equal to .[.a group of
five.]. .Iadd.said at least three .Iaddend.adjacent first strands
to thereby render said one surface substantially rough and wear
resistant, and said second strands at the opposite surface of the
fabric being exposed .[.between said cross-over points thereat.].
as knuckles each having a length equal to .[.a group of four.].
.Iadd.said at least two next .Iaddend.adjacent first strands to
thereby render said opposite surface likewise substantially rough
and wear resistant, whereby the fabric at both said surfaces has
improved paper pick-up characteristics as well as an improved
working life.
2. The fabric according to claim 1, wherein both said first and
second strands are interwoven in the repetitive pattern.
3. The fabric according to claim 1, wherein said first strands are
woven in a repetitive pattern of passing at cross-over points over
at least three adjacent second strands and then passing at
cross-over points under at least two next adjacent second strands
so as to form the 3/2 type weave pattern.
4. The fabric according to claims 1, 2 or 3, wherein said first and
second strands each comprise a synthetic polymeric
monofilament.
5. The fabric according to claim 3, wherein there are about 10 to
about 120 of each said first and second strands per inch of the
fabric. .Iadd.
6. The papermaking fabric omprising interwoven first machine
direction and second cross machine direction strands, the
improvement in which the fabric constitutes a five-shed weave
pattern wherein said second strands are woven in a repetitive
pattern of passing under at least three adjacent first strands and
then passing over at least two next adjacent first strands so as to
form a 2/3 type weave pattern, and said first strands are woven in
a repetitive pattern of passing over at least three adjacent second
strands and then passing under at least two next adjacent second
strands so as to form the 3/2 type weave pattern, said second
strand at one surface of the fabric being exposed as knuckles each
having a length equal to said at least three adjacent first strands
to thereby render one surface substantially rough and wear
resistant and said second strands at the opposite surface of the
fabric being exposed as knuckles having a length equal to said at
least two next adjacent first strands to thereby render said
opposite surface likewise substantially rough and wear resistant,
whereby the fabric at both said surfaces has improved paper pickup
characteristics as well as improved working life. .Iaddend.
.Iadd.
7. A papermakers fabric comprising interwoven first machine
direction and second cross machine direction strands, the
improvement in which the fabric comprises a six shed weave pattern
wherein at least said second strands are woven in a repetitive
regular twill pattern of passing over three and then under three of
said first strands such that the knuckles of said second strands on
opposite surfaces of said fabric are of approximately equal length,
whereby the fabric has improved paper pick up characteristics and
improved working life on both of said opposite surfaces. .Iaddend.
.Iadd.8. A papermakers fabric according to claim 7 wherein said
first machine direction strands are woven in a repetitive regular
twill pattern of passing over three and then under three of said
second strands such that the knuckles of said first strands on
opposite surfaces of said fabric are of approximately equal length.
.Iaddend. .Iadd.9. A papermaking fabric according to claim 7
wherein there are about ten to about one hundred twenty of each of
said first machine direction strands and said second machine
direction strands per inch of the fabric. .Iaddend. .Iadd.10. The
papermakers fabric according to claim 7 wherein said first machine
direction strands have a diameter of about 0.004 to about 0.030
inches and said second cross machine direction strands have a
diameter of about 0.0045 to about 0.035 inches. .Iadd.11. A
papermakers fabric comprising interwoven first machine direction
and second cross machine direction strands, the improvement in
which the fabric comprises a seven shed weave pattern wherein at
least said second strands are woven in a repetitive regular twill
pattern of passing over at least three of said first strands and
under the remainder of said first strands such that the knuckles of
said second strands on opposite surfaces of said fabric have a
difference in length not greater than one of said first strands,
whereby the fabric has improved paper pick up characteristics and
improved working life on both of said opposite surfaces. .Iaddend.
.Iadd.12. A papermakers fabric according to claim 11 wherein said
first machine direction strands are woven in a repetitive regular
twill pattern of passing over at least three of said second strands
and under at least three of second strands such that the knuckles
of said first strands on opposite surfaces of said fabric have a
difference in length not greater than one of said second strands.
.Iaddend. .Iadd.13. The papermakers fabric according to claim 11
wherein said first machine direction strands have a diameter of
about 0.004 to about 0.030 inches and said second cross machine
direction strands have a diameter of about 0.0045 to about 0.035
inches.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to fabrics for use on
papermaking machines and more particularly to Fourdrinier, or
forming fabrics.
In the manufacture of sheetlike structures of materials such as
paper, kraft, board, pulp, asbestos and the like, it is common
practice to utilize a Fourdrinier papermaking machine having an
endless belt of a generally flat fabric formed from woven metal
wires or synthetic polymeric yarns of materials such as polyamides,
polyesters and the like. The synthetic yarns can be either
monofilament or multifilament yarns.
In operation of the machine, an aqueous suspension of pulp fibers
is deposited onto the moving forming fabric. As the forming fabric
travels, some of the water content of the suspension drains through
the porous fabric so as to form a generally self-supporting
continuous web of material. The drainage of the water through the
belt may be assisted by mechanisms such as suction boxes or the
like. As the web reaches the end of the belt, the web is "picked
up" from the forming fabric and is subsequently subjected to a
series of rolling and drying operations to yield the final
sheet-like product.
The woven forming fabric of the papermaking machine must possess a
variety of characteristics to properly function in the papermaking
process. The forming fabric should be sufficiently fluid permeable
so as to allow for the drainage of water from the fiber suspension
but sufficiently closed so as to prevent the passage of significant
amounts of fibers contained in the suspension. Since the forming
fabric is under tension and is subjected to bending as it passes
over the rolls, the strength and resistance to fatigue and wear of
the fabric must be high so as to insure the longest possible
working life. In addition, the strands of fabric should be
dimensionally stable relative to one another so that the fabric
will not have varying drainage characteristics which can affect the
uniformity of the final product.
Various types of weaving patterns for forming fabrics for use in
papermaking machines are known in the art. Generally these patterns
have the identical symmetry in the warp and shute directions. For
example, U.S. Pat. No. 3,858,623 to Lefkowitz discloses a prior art
pattern wherein the warp and weft, or shute, yarns pass over one
yarn, beneath the two adjacent yarns and then over the next yarn.
For convenience, this pattern may be referred to as a one-two type
pattern. The above-mentioned patent further discloses another
pattern for papermaking machine fabrics which can be defined as a
one-three type pattern. In addition, U.S. Pat. No. 3,211,606 to
Watson discloses a papermaking fabric of woven wires having a
repetitive four strand, two-two type pattern and U.S. Pat. No.
1,927,498 to Lindsay discloses a one-two type pattern for a woven
metal wire belt for a papermaking machine. Similar types of
papermaking fabrics are also disclosed in U.S. Pat. Nos. 2,903,201
to Halden et al, 2,755,047 to Henke, 3,139,119 to Buchanan,
3,143,150 to Buchanan, 3,159,530 to Heller et al and 3,421,230 to
Ward.
Various problems are associated with the use of the above-mentioned
fabrics as belts in papermaking machines. For example, the fabric
having the so-called one-three type of repetitive pattern in the
weave tends to have one relatively smooth surface and one
relatively rough surface. Such fabric tends to have relatively
short life when run with the smooth surface against the suction
boxes. For example, the one-three type fabrics that are used in the
production of heavier papers typically only have a usable life of
about thirty days at normal production speeds. The smoother surface
of the fabric also tends to erode the covers of the suction box in
a papermaking machine which therefore requires frequent grinding of
the covers to maintain adequate suction of the belt. Furthermore,
such fabrics do not allow the dewatered web to be "picked up" or
released easily from the smoother surface when they are run with
the rougher surface against the suction box covers. The same
problems are encountered to a greater or lesser extend in the use
of the other fabric weave types such as a two-two or a one-two.
These other fabric weave types also may have inadequate drainage
characteristics.
SUMMARY OF THE INVENTION
It, therefore, is an object of the present invention to provide a
fabric adapted for use as a forming fabric in a papermaking machine
which has a longer useful life, allows for increased output from
the macine and significantly reduces the necessity for grinding the
covers of the suction boxes of the machine.
A further object of the present invention is to provide a fabric
for papermaking machines which has good drainage characteristics.
Another object of the present invention is to provide a fabric,
which when used in a papermaking machine, has good "pick up" or
release characteristics.
It has been found that these objectives of the present invention
can be achieved by employing a forming fabric that has a two-three
type weave pattern or a pattern having a greater number of threads
included in the repetitive weave.
More specifically, these objects are achieved by using a forming
fabric made in accordance with the present invention that has
interwoven warp and shute strands of material, each warp strand
extending transversely to the shute strands and at least one of the
types of strands woven in a repetitive pattern of passing over a
group of at least three adjacent strands of the other type and then
passing under a group of at least two adjacent strands of the other
type.
Preferably both types of strands of the fabric are woven in a
repetitive pattern wherein each shute strand is in a repetitive
pattern of passing under a group of three adjacent warp strands and
passing over a group of two adjacent warp strands next to the group
of three warp strands and each warp strand is in a repetitive
pattern of passing over a group of three adjacent shute strands and
passing under two adjacent shute strands next to the group of three
shute strands.
Further objects, advantages and features of the present invention
will become more fully apparent from a detailed consideration of
the arrangement and construction of the constituent parts as set
forth in the following specification taken together with the
accompanying drawing.
DESCRIPTION OF THE DRAWINGS
In the drawings,
FIG. 1 is an enlarged fragmentary plan view of a papermaking fabric
in accordance with the present invention,
FIG. 2 is a cross-sectional view of the fabric of FIG. 1 taken
along line 2--2, thereof and
FIG. 3 is a cross-sectional view of the fabric taken along line
3--3 of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, there is shown a papermaking fabric
portion 10 in accordance with the present invention. Fabric 10
comprises warp strands 12 and shute strands 14 of suitable material
such as metallic wire or synthetic polymeric monofilament. It is
preferable that strands 12 and 14 are all of the same type material
such as polyester or polyamide monofilament although the fabric of
the present invention may be workable with strands of different
materials.
Warp strands 12 and shute strands 14 of fabric 10 are woven in a
repetitive five shed weaving pattern such that each strand passes
over or under a group of three adjacent strands and then passes
over or under an adjacent group of two adjacent strands. Adjacent
parallel strands are offset one strand in the repetitive pattern so
that a twill type fabric is produced, i.e., a fabric woven so as to
have an appearance of diagonal lines. This offset may be defined as
each warp or shute type strand of the fabric, in each repetitive
pattern, passes over or under only two strands of the group of
three adjacent strands passed over or under by an adjacent parallel
strand of the same type.
The weave pattern is more clearly illustrated in FIGS. 2 and 3. In
FIG. 2, warp or machine directional strand 12 sequentially passes
under a group of two adjacent shute or cross-machine directional
strands 14, passes over a group of three adjacent shute strands and
then passes under a group of two more adjacent shute strands, etc.
In FIG. 3, a shute or cross-machine strand 14 passes over a group
of two warp or machine directional strands 13, beneath a group of
three adjacent warp strands and then over two more adjacent warp
strands, etc. It should be noted that warp or machine direction
strands and shute or cross machine direction strands also described
apply to flat woven fabric. In endless woven fabric the shute
strands are machine direction and the warp strands are cross
machine direction. As is apparent from an examination of FIG. 1,
each strand of the fabric, in each repetitive pattern for that
strand, passes over only two of the three transverse strands passed
over by the adjacent parallel strand.
While the terms "over" and "under" have been used to describe the
manner in which the warp and shute strands are interwoven relative
to each other, it should be realized that the terms are only
relative to the particular orientation of the woven fabric.
Therefore, as used herein, the terms are used for convenience and
clarity of description and are intended to only indicate the
relative position of a strand to a transverse strand or
strands.
In a presently preferred fabric woven in the pattern as shown in
FIGS. 1-3, each cross machine direction strand 14 has a slightly
larger diameter than the diameter of each machine direction strand
12. Preferably, machine direction strand 12 has an average diameter
of about 0.004 to about 0.030 inches and each cross machine
direction strand 14 has an average diameter of about 0.0045 to
about 0.035.
In a preferred use of fabric 10 shown in FIGS. 1-3, the fabric is
oriented on a papermaking machine such that shute strands 14 are in
the cross-machine direction and the surface of the fabric having
the knuckles .Iadd.16 .Iaddend.or exposed shute strands passing
.[.over.]. .Iadd.under .Iaddend.three warp strands 12 is down and
in contact with the suction box of the machine.Iadd., and the
knuckles 18 or exposed shute strands passing over two adjacent warp
strands are up and in contact with the paper web. .Iaddend.Thus the
wear surface of the fabric 10 has been increased through longer and
larger wear knuckles .Iadd.16 .Iaddend.formed by shute strands 14
which thereby provides additional working life for the fabric.
To be useful in a Fourdrinier section of a papermaking machine the
fabric should have an air permeability of about 500 to 850 cubic
feet per minute (CFM) per square foot of fabric at about one half
inch water pressure drop. It has been found that a fabric having
between 10 to 120 strands per inch, both in the warp and shute
direction, provides sufficient permeability or porosity for water
drainage. Since, as was stated above, the average cross machine
direction strand diameter is larger than the machine direction
strand diameter in the preferred fabric, preferably the number of
machine direction strands per inch is greater than the number of
cross machine direction strands per inch although it is within the
scope of the present invention to have an equal number of less
machine direction strands than cross machine direction strands per
inch.
As with other known forming fabrics for papermaking machines, the
fabric of the present invention can be flat woven and then formed
into a seamed endless belt or the fabric can be woven directly into
an endless belt. In addition, the fabrics in accordance with the
present invention also may be utilized in papermaking applications
other than a belt for a Fourdrinier section of a papermaking
machine such as in wet felts and dryer felts.
While the above-described fabric in accordance with the present
invention utilizes a so-called two-three type weave pattern, it is
within the scope of the invention to provide fabrics having a
greater number of strands per repetitive patterns such as
three-three, three-four and the like.
The fabric of the present invention provides several advantages
over known fabrics for use in papermaking machines. To be more
specific, the two-three type fabric of this invention has an
exceptionally long useful life, is able to run at high speeds and
production rates, and significantly reduces the necessity for
regrinding the covers of suction boxes. These advantages of the
two-three fabric of the present invention may result from, among
others, a significantly increased exposed wear surface in the
fabric through longer wear knuckles and the use of larger diameter
strands for both the warp and shute strands which causes less unit
pressure on the suction box covers while the required air
permeability of the fabric is retained.
The above-mentioned advantages are illustrated in the following
specific example of a fabric in accordance with the present
invention. It should be understood that the example is given for
the purpose of illustration only and the example does not limit the
invention as has heretofore been shown and described.
EXAMPLE
A fabric woven in accordance with the present invention was formed
into an endless belt having a width of about 92 inches and a total
length of about eighty feet. The fabric was made from polyester
monofilament strands, the warp strands having an average diameter
of about 0.0105 inches and the shute strands having an average
diameter of about 0.013 inches. The fabric averaged about 56 warp
strands per inch and about 40 shute strands per inch and had an air
permeability of about 700 CFM per square foot of fabric.
The fabric belt was installed in a Fourdrinier machine used for
making 26 to 36 pound corrugated medium and the machine ran at
speeds of up to 1450 feet/minute. The belt was used for 108 days of
machine operation as compared to approximately 60-65 days of
operation for other belts used on the same machine. The belt had
reached the end of its useful life due to an unrepairable hole in
the belt. At certain periods during operation of the machines, the
machine produced more corrugated medium per day than the machine
had every produced previously with other types of fabric belts, in
one particular month averaging about 158 tons of product per day.
In addition, the polyethylene suction box covers of the machine
required no grinding during the entire period which is in contrast
to the conventional necessity of grinding the covers about every
twenty days when using belts of other fabric types.
While the present invention has been described with reference to a
particular embodiment thereof, it will be understood that numerous
modifications may be made by those skilled in the art without
actually departing from the spirit and scope of the invention as
defined in the appended claims.
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