Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F1/00—Wet end of machines for making continuous webs of paper
  • D21F1/0027—Screen-cloths
  • D21F1/0036—Multi-layer screen-cloths

Definitions

• the present invention is directed to a composite papermaking fabric which is preferably used in the forming section but could also be used in the dryer section.
• composite fabric refers to a fabric comprising two woven structures one of which is the paper side fabric or upper fabric and the other of which is the machine side fabric or lower fabric.
• the paper side fabric includes a support surface which surface receives and supports the paper forming pulp during the paper forming operation.
• the lower or contact fabric separates the support fabric from the machine rollers during the paper forming operation and includes a roller contact or contact surface. Both fabrics must be stable and provide the required drainage.
• the support fabric must also provide an even support surface without unduly high knuckles or unduly deep knuckle depressions so as to not mark the paper during the paper forming operation.
• the upper and lower fabrics are bound together with a binder yam which in the instant case comprises fabric bom warp yam.
• fabric bom warp yam indicates that the binder yam while binding the upper and lower fabrics together also weaves in the machine direction with and is an integral part of the weave pattern of both the upper and lower fabrics.
• warp yarn refers to yams which weave in a single specified layer of the fabric and in the machine direction.
• weft yam refers to ya s woven transverse of the warp yams.
• Another object of the invention is a papermaking fabric in which the support surface is formed in a one up, one down weave pattern.
• Another object of the invention is a composite papermaking fabric in which fabric bom warp yams bind the upper and lower fabrics together and weave with weft ya s to form the lower fabric.
• Another object of the invention is a composite papermaking fabric in which the weft yam of the upper fabric at the binding points are supported against downward movement.
• Another object of the invention is the provision of a composite papermaking fabric in which no pairing of weft ya s appear on either surface.
• Another object of the invention is the provision of a composite papermaking fabric in which no pairing of wa ⁇ and fabric bom wa ⁇ yams appear on either surface.
• the present invention is directed to a composite papermaking fabric having an upper fabric which includes a fiber support surface and is formed of wa ⁇ yams, fabric bom wa ⁇ yams and weft yams.
• the support surface is woven in a one up, one down
• the papermaking fabric also includes a lower fabric formed of fabric bom wa ⁇ yams and weft yams interwoven to provide a weft yam dominated contact surface.
• Each fabric bom wa ⁇ yam is controlled to weave over at least one of the upper fabric weft yams during each repeat of the weave pattern forming binding points which act to bind the upper fabric with the lower fabric.
• the preferred weave pattern requires that each fabric bom wa ⁇ yam weave over two of the upper weft yams to form two binding points which are spaced longitudinally of the weave pattern.
• the binding points preferably form a broken twill line across the weave pattern and the width of the papermaking fabric. But it is also possible that the binding points form a straight twill line across the paperside weave pattern.
• the upper wa ⁇ yams float beneath the upper weft yams at each of the binding points forming a support beneath the upper weft yams which acts to maintain knuckle height uniform across the support surface.
• the fabric bom wa ⁇ yams weave with the weft yams of the lower fabric in preferably a broken twill pattern forming a plurality of even weft floats on the contact surface. There is a plurality of the weft yam floats formed by each lower weft yam per weave pattern repeat.
• a composite papermaking fabric comprising an upper fabric formed with a support surface woven In a one up, one down weave pattern and a lower fabric formed with a weft dominated contact surface.
• the papermaking fabric comprises a plurality
• the wa ⁇ yams weave beneath each of the upper weft yam at the selected locations forming the binding knuckles providing support beneath the upper weft yam and the binding knuckle which support assists in maintaining the binding knuckles parallel with the remainder of the knuckles of the support surface.
• the weft yam weaving with the fabric bom wa ⁇ yams form the contact surface with two floats on the contact surface per pick throughout a weave pattern repeat.
• Fig 1 is a cutaway perspective view showing the support surface of the papermaking fabric through a portion of the weave pattern.
• Fig 2 is a cutaway perspective view showing the contact surface of the papermaking fabric through a portion of the weave pattern.
• Fig 3 is a side view showing the relationship of wa ⁇ yarn 1 and fabric bom wa ⁇ ya 2 with all of the weft yams through the weave pattern.
• Fig 4 is similar to Fig 3 showing the relationship of wa ⁇ yam 3 and fabric bom wa ⁇ yam 4 with the weft yams through the weave pattern.
• Fig 5 is similar to Fig 3 showing the relationship of wa ⁇ yam 5 and fabric bom l o wa ⁇ yam 6 with the weft yams through the weave pattern.
• Fig 6 is similar to Fig 3 showing the relationship of wa ⁇ yam 7 and fabric bom wa ⁇ yam 8 with the weft yams through the weave pattern.
• Fig 7 is similar to Fig 3 showing the relationship of wa ⁇ yam 9 and fabric bom wa ⁇ yam 10 with the weft yams through the weave pattern.
• Fig 8 is similar to Fig 3 showing the relationship of wa ⁇ yam 11 and fabric bom wa ⁇ yam 12 with the weft yams through the weave pattern.
• Fig 9 is similar to Fig 3 showing the relationship of wa ⁇ yam 13 and fabric bom wa ⁇ yam 14 with the weft yams through the weave pattern.
• Fig 10 is similar to Fig 3 showing the relationship of wa ⁇ yam 15 and fabric 20 bom wa ⁇ yam 16 with the weft yams through the weave pattern.
• Fig 11 is a diagram of the weave pattern of the support surface.
• Fig 12 is a diagram of the weave pattern of the contact surface.
• Figs 1 and 2 represent sectional perspective views of the composite papermaking in which the upper fabric A is formed with a paper pulp support surface C as shown in Fig 1 and the lower contact fabric B which is formed with a lower roller contact surface D as shown in Fig 2.
• upper fabric A and more specifically, support surface C is woven in a one up, one down weave pattern allowing the support surface to present an even array of wa ⁇ knuckles separated on each side by a weft knuckle. This is best illustrated in Fig 11 where each O represents a wa ⁇ yam passing over a weft yam on the support surface. Each passover forms a wa ⁇ knuckle.
• each weft ya passing over a wa ⁇ yam on the support surface is represented by a blank square. These passovers form weft knuckles. Each O represents a binding point where the wa ⁇ yam passing over the weft yam is an fabric bom wa ⁇ yam.
• the fabric is woven utilizing eight wa ⁇ yams numbered 1 , 3, 5, 7, 9, 11 , 13 & 15 and with eight fabric born wa ⁇ yams numbered 2, 4, 6, 8, 10, 12 & 16 per weave pattern repeat which is a so called 16 shaft weave.
• the present invention is not limited to the weave repeat shown in the figures. It's understood that the weave repeat in general can be 16 shaft or greater. Therefore the weave repeat could be for example a 20 shaft or a 24 shaft or a 28 shaft or a 32 shaft or a 40 shaft weave.
• the weave pattern repeat also weaves with forty weft yams numbered 1-40.
• the x represents the binding points or the positions in which an fabric bom wa ⁇ yam passes over an upper weft yam weaving with the support fabric A to bind the support fabric A with the contact fabric B forming the composite fabric.
• binding points which form binding knuckles 70, are identified in Figs 1 and 3-10.
• Figs 3-10 are side views of each of the wa ⁇ and fabric bom wa ⁇ yams weaving with the weft yams 1-40 through a complete repeat of the weave pattem.
• the ratio of upper weft yams to lower weft yams is 3 : 2. It is understood that this ratio is not limiting the scope of the invention, therefore the ratio exemplary also could be 2 : 1 or 5 : 3.
• wa ⁇ yams 1 , 3, 5, 7, 9, 11 , 13 & 15 weave only with weft yams 2, 3, 5, 7, 8, 10, 12, 13, 15, 17, 18, 20, 22, 23, 25, 27, 28, 30, 32, 33, 35, 37, 38 & 40 forming support fabric A.
• the weave pattem at selected points brings the upper wa ⁇ yams to float beneath five consecutive of the upper weft yam picks, such as wa ⁇ yam 1 at the pick of weft yams 15, 17, 18, 20 & 22 in Fig 3 and warp yarn 5 at the pick of weft yams 5, 7, 8, 10 and 12 in Fig 5. It is along these floats that the fabric bom wa ⁇ yams are brought up to pass over two spaced picks, such as fabric bom wa ⁇ yam 2 over picks 17 & 20 in Fig 3 and fabric bom wa ⁇ yam 6 over picks 7 and 10 in Fig 5, binding upper fabric A with lower fabric B. Throughout the remainder of the weave pattern, each of the fabric bom wa ⁇ yams
• the wa ⁇ yams weave during each repeat of said weave pattern with a predominant or major portion of the upper weft yams and that the fabric bom wa ⁇ yams weave only with a minor portion of the upper weft yams to form the upper fabric weave pattem. It is to be understood that a major portion means a portion of more that 50% and a minor portion means a portion of less than 50%.
• the associated upper wa ⁇ yam passes beneath the pick where the binding point is formed with the fabric bom wa ⁇ yam.
• wa ⁇ 1 passes beneath weft yam or picks 17 & 20 at binding points 70.
• wa ⁇ yam or pick 5 passes beneath weft yams 7 & 10 at binding point 70.
• the weave pattern of the support fabric A predominantly is formed by the weaving of the wa ⁇ yams 2, 3, 5, 7, 8, 10, 11 ...
• applicant in general came to the conclusion that for creating a smooth and uniform support surface C it is necessary that the upper (paper side) weft yams which interweave with fabric bom wa ⁇ yams or wa ⁇ yams and thereby only form a minor portion of the support fabric A need to be supported against vertical downward movement. Therefore, e.g. wa ⁇ yam 1 floats beneath (paper side) weft yams 17, 18 & 20.
• This vertical support acts to help maintain the crest of the knuckles formed at binding points 70 elevated and on an even and substantially parallel plane with the remainder of the knuckles forming the support surface C. Also, by passing the upper warp yams beneath the upper weft at the binding points no adjacent knuckles appear on the support surface at the binding points.
• FIGs 2-10 & 12 contact fabric B will now be discussed.
• contact fabric B is woven in a broken twill pattem with each fabric bom wa ⁇ yarn passing beneath four weft yams at spaced locations on contact surface D.
• Each fabric bom wa ⁇ yam either floats above the lower weft yams and beneath the wa ⁇ and weft yams of the upper or support fabric A or passes over the two of the upper picks forming binding points 70 throughout the remainder of each weave pattem as earlier discussed.
• the ya s selected for forming the disclosed may comprise yams of the same diameter or of varying diameters if desired. For example, it may be desirable to weave the support fabric with weft yams of less size than the weft yams forming the contact fabric.
• the wa ⁇ and the fabric bom wa ⁇ yams preferably are of the same size.
• Variation in yam size may be selected depending upon the performance requirements.
• the materials chosen for the yams can vary depending upon the performance needs of the formed papermaking fabric. Generally stability is of the utmost importance, it being desired that the drainage capability be maintained throughout the life of the papermaking fabric. Also, wearability is another vital factor due to cost.
• polyester yams which exhibit excellent stability characteristics may be selected to form the support surface and as the fabric bom wa ⁇ yams.
• the running or contact surface weft yarns may all or partly be polyamide yams due to greater wearability characteristics.
• the contact side weft yams may be of a larger diameter than the support fabric weft yams.
• Other synthetic materials and size combinations may be selected to form the wa ⁇ , weft, and fabric bom wa ⁇ yams of the invention dependent upon the required performance needs of the fabric.

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• Woven Fabrics (AREA)
• Paper (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=33477412

Family Applications (1)

Country Status (2)

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• 2004
  • 2004-02-24 WO PCT/EP2004/050194 patent/WO2004104295A1/en active Application Filing
  • 2004-02-24 EP EP04713898A patent/EP1631717A1/de not_active Withdrawn

Non-Patent Citations (1)

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