Apparatus for manufacturing an untwisted synthetic resin string

Claim 1

An apparatus for manufacturing an untwisted synthetic resin string comprising a stretching means for stretching a strip of thermoplastic resin film at least longitudinally thereof, a roll-forming means disposed to the rear of the stretching means for inwardly rolling only one side edge of the stretched film strip, and a heat-setting means disposed to the rear of the roll-forming means, the roll-forming means including a plurality of rolling members each having a curved rolling surface only at one end thereof and a flange at the other end thereof to prevent lateral displacement of the film strip, the rolling members being arranged side by side transversely of the direction of advance of the film strip and spaced apart by specified distances along the direction in such arrangement that the rolling surfaces are reduced in the radius of curvature thereof and positioned closer to the centerline of travel of the film strip toward the direction of advance of the film strip, the heat-setting means being so arranged that only the free edge of the untwisted rolled strip sent out from the roll-forming means and having a spiral cross section is thermally adhered to its outer layer, permitting the interior of the rolled strip to remain loose.

Claim 2

An apparatus for manufacturing an untwisted synthetic resin string comprising a stretching means for stretching a strip of thermoplastic resin film at least longitudinally thereof, a roll-forming means disposed to the rear of the stretching means for inwardly rolling only one side edge of the stretched film strip, and a heat-setting means disposed to the rear of the roll-forming means, the roll-forming means including a plurality of rolling members each having a curved rolling surface only at one end thereof and a flange at the other end thereof to prevent lateral displacement of the film strip, the rolling members being arranged side by side transversely of the direction of advance of the film strip and spaced apart by specified distances along the direction in such arrangement that the rolling surfaces are reduced in the radius of curvature thereof and positioned closer to the centerline of travel of the film strip toward the direction of advance of the film strip, the heat-setting means being so arranged that only the free edge of the untwisted rolled strip sent out from the roll-forming means and having a spiral cross section is thermally adhered to its outer layer, permitting the interior of the rolled strip to remain loose.