Multi-ply paper forming fabric with ovate warp yarns in lowermost ply

Claim 1

A forming fabric for use at the wet end of a paper making machine to receive wet pulp and form the same into a consolidated web by affording discharge of the free water content of the wet pulp, comprising a multi-ply fabric having a width corresponding to the width of the paper making machine and a length in the form of a continuous loop corresponding to the length of the path of travel of the fabric through the paper machine, the uppermost ply of said multi-ply fabric comprising a self-sustaining weave construction having monofilament warp yarns of a given diameter interwoven with shute yarns in a weave pattern selected to produce the desired surface texture in the paper produced from the web formed on said fabric, the lowermost ply of said multi-ply fabric comprising a series of generally ovate warp yarns having a vertical dimension in the range of 1.0 to 1.5 times the diameter of the warp yarns of the uppermost ply, and shute yarns interwoven with said ovate warp yarns to produce a self-sustaining fabric construction which is characterized by a high degree of porosity without substantial voids, said ovate warp yarns in the lower ply having a horizontal width in the shute direction substantially greater than said vertical dimension, and binder shute yarns interconnecting the upper and lower plies, and being interwoven with the upper ply adjacent to a shute yarn of the upper ply at a point where said shute yarn passes over a warp yarn of said upper ply, and being interwoven with the lower ply adjacent a shute yarn of the lower ply at a point where said shute yarn of the lower ply passes under an ovate warp yarn of the lower ply.