| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for a biaxially-stretched thermoplastic resin pipe which can control a stretch ratio in an axial direction using a single take-up machine without a lubricant at all in biaxially stretching a thermoplastic resin pipe, unnecessitates re-heating the thermoplastic resin pipe, greatly cuts down molding equipment and gives an excellent stretch ratio and accuracy of dimension. SOLUTION: A thermoplastic resin pipe 9 extruded from a die 2 of an extruder 1 is quickly chilled followed by being slowly cooled to adjust a temperature to a predetermined stretching temperature. The thermoplastic resin pipe 9 is enlarged by inserting a large diameter die 6 connected to the die 2, having a diameter gradually increasing toward a running direction of the thermoplastic resin pipe 9 and having a maximum diameter almost equal to the inner diameter of the stretched thermoplastic resin pipe 9 to be formed and is stretched by taking up the enlarged thermoplastic resin pipe 91 with a take-up machine 8.
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