MOUTHPIECE DEVICE AND PRODUCTION OF SYNTHETIC RESIN PIPE

摘要

PROBLEM TO BE SOLVED: To provide a mouthpiece device and a synthetic resin pipe producing method capable of preventing the generation of a stripe or the like on the outer peripheral surface of a pipe and enhancing cooling efficiency to enhance productivity. SOLUTION: The gap between the outer peripheral surface of a mandrel A1 on a deep side and the inner peripheral surface of a die ring B1 is formed so as to become gradually wide from an upstream side to a downstream side and a plurality of helical grooves 12 are provided on the outer peripheral surface of the mandrel A1 so as to become gradually shallow in the depth thereof from the upstream side to the downstream side. The molten resin extruded from an extruder is extruded from the annular passage between the mandrel A1 and the die ring B1 while passed through the helical grooves 12 and a pipe molded into a tubular shape is guided to a cooling water tank to cool the outer peripheral surface of the pipe and this pipe is passed through the die ring B1 while the stagnated air in the pipe is sucked and discharged to cool the pipe from its inner peripheral surface.