The instant invention is directed to a composite papermaking fabric formed to provide improved wearability, stability and uniform porosity.
Composite papermaking fabrics are widely used and well known throughout the papermaking industry as is illustrated by U.S. Pat. No. 5,152,326 to Vohringer and U.S. Pat. No. 5,544,678 to Barrett. In composite papermaking fabrics, which comprise upper support and lower contact fabrics, it is a primary object to protect the binding yarns or those which bind the upper and lower fabrics together, from wear. This is necessary because once a binder yarn breaks, the upper and lower fabrics separate destroying the papermaking fabric.
Traditionally, the binder yarns are protected by using smaller yarns and crossing them over the lower fabric yarns adjacent a large knuckle. This approach sometimes interferes with drainage as the binders do not form a part of the basic weave pattern of the upper and lower fabrics.
Another approach is to incorporate the binder yarns into the weave pattern of the upper and lower fabrics. This approach, while improving drainage, subjects them to increased wear. Even when they are incorporated into the weave pattern as smaller yarns, certain areas along their binding length are not protected.
Accordingly, it is an object of the present invention to provide a composite papermaking fabric with improved drainage, stability and wearability.
Another object of the instant invention is a composite papermaking fabric in which the binding yarns form a part of the basic weave pattern of the upper and lower fabrics.
Another object of the invention is the provision that the binder yarns form floats on the contact surface which are protected against wear along their entire length.
Another object of the invention is a composite papermaking fabric in which the binding yarn floats are arranged between protective floats along their entire length.
Another object of the invention is the provision of a composite papermaking fabric which is woven in a 40 pick repeating pattern.
Another object of the invention is the provision of a composite papermaking fabric which is woven in a 70 pick repeating pattern.
The invention is directed to composite papermaking fabrics having an upper support fabric including upper warp and weft yarns and a lower contact fabric including lower warp and weft yarns with the upper fabric being woven in a first weave pattern forming a support surface and the lower fabric being woven in a broken twill weave pattern forming a contact surface. The composite fabrics include paired binder yarns weaving in alternating sequences with the upper fabric in the first weave pattern and in the lower fabric in the broken twill weave pattern while acting to bind the upper and lower fabrics together.
The contact surface may include a plurality of side by side and at least paired cross-machine direction yarns which form floats passing outwardly of a plurality of adjacent machine direction yarns across the broken twill weave pattern. Certain of the at least paired cross-machine direction yarn floats include at least one of the lower weft yarns and one of the binder yarns. In the paired floats formed by the at least one of the lower weft yarns and one of the binder yarns, the float formed by the one binder yarn is shielded along its entire length by the float formed by the one lower weft yarn. The at least paired cross-machine direction floats may each pass under three adjacent machine direction yarns. The at least paired cross-machine direction floats may comprise a pair of the lower weft yarns and a single binder yarn with the binder yarn being adjacent each of the lower weft yarns.
The lower weft yarns along with the lower warp yarns may be larger in diameter than the binder yarns, the upper weft yarns and the upper warp yarns.
In certain instances, the at least paired cross-machine direction floats may pass under five adjacent machine direction yarns, and in other instances they may pass under three cross-machine direction yarns.
The weave pattern provides that each binder yarn of the pair of binder yarns form at least one float of the paired floats formed across the width of the broken twill weave pattern. Certain ones of the paired cross-machine floats may comprise only adjacent ones of the lower weft yarns.
The upper warp and weft yarns along with the binder yarns are of equal diameter. Also, the upper warp and weft yarns, the lower warp and weft yarns and the binder yarns are formed of one of or a combination of polyester and nylon yarns.
Each of the at least paired cross-machine floats is formed to include at least one of the lower weft yarns.
A composite papermaking fabric which is woven in at least a 40 pick repeating pattern having an upper support fabric including upper warp and weft yarns and a lower contact fabric including lower warp and weft yarns. The weave pattern weaves the upper fabric in a plain weave forming a support surface and the lower fabric in a broken twill weave which forms the contact surface. The composite fabric includes paired binder yarns which weave in alternating sequences with the upper fabric in the plain weave and in the lower fabric in the broken twill weave. The binding yarns act to bind the upper and lower fabrics together.
The contact surface includes a plurality of at least paired cross-machine direction yarns forming floats passing outwardly of a plurality of adjacent of the lower warp yarns across the weave pattern. Certain of the at least paired cross-machine direction yarn floats include at least one of the lower weft yarns and one of the binder yarns. In the cross-machine paired floats formed by the lower weft yarns and the binder yarns, the float formed by the binder yarn is shielded along its entire length by the float formed by the lower weft yarn.
The composite papermaking fabric is woven in one of a 40 pick weave pattern and a 70 pick weave pattern. The cross-machine direction floats comprise two yarns in 40 pick weave pattern and three yarns in the 70 pick weave pattern. The binder yarn float is located adjacent and below a single float formed by the lower weft yarn in the 40 pick weave pattern and between and below two floats formed by the lower weft yarns in the 70 pick weave pattern.
The at least paired cross-machine floats may pass under differing numbers of machine direction yarns within the weave pattern.
The construction designed to carry out the invention will hereinafter be described, together with other features thereof.
The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown and wherein:
In composite papermaking fabrics a primary concern is wear on the contact surface and more particularly wear of the binding yarns due to contact with the machine rollers. In order to lessen wear of the binder yarns steps are taken to shield them from contact with the machine rollers while maintaining an even support surface, good fabric stability and drainage.
In the instant case, generally a portion of the yarns forming the lower or contact fabric are preferably of a wear resistant synthetic material such as nylon and have a larger diameter than the remainder of the yarns. Preferably the contact fabric yarns are between 0.15–0.30 mm in diameter with about 0.19 mm being the preferred size for the warp yarns and 0.30 mm being the preferred size for the weft yarns.
The support or upper fabric is preferably woven with more stable yarns such as polyester although nylon may also be used. The yarn diameters for the upper or support fabric is between 0.08–0.25 mm with 0.13 mm for the warp and weft being preferred.
The binder yarns are preferably nylon or polyester and are of a diameter within the range of the upper fabric warp and weft yarns with 0.13 mm being the preferred size.
It is noted that other synthetic materials may be utilized as the yarn forming material, the selection being made in accordance to the necessary yarn characteristics and price.
Turning now to
The upper warp yarns C along with the upper weft yarns E weave only with the upper or support fabric A and lower warp and weft yarns D and G weave only with the lower or contact fabric B. The binder yarns H, H′ weave with both the upper and lower warp yarns in opposing sequences.
Turning now to
As shown, upper weft yarns weave on opposite sides of each row formed by the binder yarns. It is noted that the composite fabric weave concept of this invention includes having more than one upper weft yarn on opposite sides of each binder row.
Turning now to
Binder yarns H, H′ weave in a similar manner passing outwardly of and beneath the same warp yarns as the adjacent lower weft yarns forming floats I, I′ across the weave pattern. It is noted that while binder yarn H is forming float I, binder yarn H′ is weaving in a plain weave with support fabric A and when binder yarn H′ weaves to form floats I′, binder yarn H is weaving with the support fabric. The floats G, I & I′ each pass outwardly of three adjacent lower warp yarns so that a float G formed by lower weft F appears adjacent the entire length of each float I or I′ formed by binder yarns H, H′ as is clearly shown at Z in
Turning now to
Turning now to
Beginning with pick 1 which is an upper weft yarn weaving only with upper warp yarns 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 through pick 40 which is a binder yarn weaving with both the upper and lower warp yarns 1–20, the inter-relationship of each weft or binder yarn relative to the warp yarns is shown.
Pick 2 is shown passing beneath warp yarns 15, 17, 19 forming a first float G and also beneath warp yarns 5, 7, 9 forming a second float G as it passes across the weave pattern. In the adjacent row formed by binder yarns H, H′, pick 3 weaves first with upper warp yarns 14, 16, 18 and 20 before passing beneath lower warp yarns 5, 7, 9 forming float 1. Pick 4 first passes beneath warp yarns 15, 17, 19 before then weaving with upper warp yarns 4, 6, 8, 10. The binder yarns cross between warp yarns 3, 4 and 11, 12.
The sequence is repeated throughout the weave pattern utilizing different ones of upper and lower warp yarns weaving with the weft and binder yarns forming ten rows of paired floats along the weave pattern, each row comprising two sets of paired floats across the weave pattern.
Turning now to
Generally the fabric of
Turning to
Lower fabric K, as shown in
Turning again to
Turning now to
Picks 3–70 continue the progression of multi-yarn floats over the weave pattern.
While a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.
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Number | Date | Country | |
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20050067040 A1 | Mar 2005 | US |