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.

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.