Patent ID: 6939424
Filing Date: 2005-09-06
Classification: B29C

Abstract:
1. A method for making a spirally-wound tube from a hollow thermoplastic profile having a substantially rectangular cross-section, wherein the method comprises: feeding the thermoplastic profile to a drum such that the thermoplastic profile comes onto a stationary section of the drum, wherein a spaced sliding means is arranged along a periphery of the stationary section; winding the thermoplastic profile around the drum; welding adjacent loops of the thermoplastic profile together on the stationary section so as to form the spirally-wound tube, wherein an inner weld joint and an outer weld joint are formed by the welding of adjacent loops, and wherein the inner weld joint and the outer weld joint are arranged to run along a spiral groove running around the stationary section; smoothing the inner weld joint by using extra heat and a stationary body resting against the inner weld joint; smoothing the outer weld joint by using extra heat and a stationary body resting against the outer weld joint; transferring the tube to a rotary driven section which causes the tube to rotate and pulls the thermoplastic profile around the stationary section; and feeding the spirally-wound tube axially forward by means of freely rotating, radial press rolls influencing the thermoplastic profile during an initial winding around the drum.