METHOD AND APPARATUS FOR PRODUCING ORIENTED PLASTIC STRAP USING ROLLERS

摘要

An apparatus for simultaneously milling and stretching a sheet workpiece (122) includes a pair of opposed rollers (142, 144) defining a nip (146) therebetween and through which said sheet workpiece (122) is passed to be simultaneously milled and stretched in a single pass. The opposed rollers are driven in opposite directions and at sufficiently different lineal surface velocities to simultaneously mill and stretch the workpeice within the nip. Means (188, 194) for heating opposite side portions of the sheet workpiece (122) upstream of the nip (146) and at axial positions across its width are located predetermined distances from opposite side edge portions of the sheet workpiece. This increases the degree of flatness of the workpiece across its width after it has been simultaneously milled and stretched by eliminating any concave portions and bump transitional points defined between said concave portions and a main central portion of it. These tend to form at and within the vicinity of said axial positions located said predetermined distances from said opposite side edge portions of the sheet workpiece (122).