PURPOSE: To prevent the spring back of a flange part due to residual stress by heating the opening end part of thermoplastic resin pipe cut into a constant length at the temperature higher than the heat deformation temperature in only a specific degree.
CONSTITUTION: The opening end part 2 of a pipe is mounted within the cavity 3 in a state of being heated beforehand at a temperature of 20 °C or higher than the heat deformation temperature. Next, it descends while compressed air is blown into the pipe from the blowout hole 5 of a core 4 having a configuration of fitting with the upper end of the cavity 3 and the cavity 3 and core 4 are brought into coincidence with each other. In this state, the opening end part 2 is cooled and fixed wholly and in consequence formed into a flange 6. Thereby, the occurrence of deformation or creases on the pipe body is prevented at the time of flange formation and the spring back of the flange part 6 can also be prevented which is caused by the residual stress after molding.
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FURUSE TATSUO
TAKASAKI TOMOAKI
