PIPE EXTRUSION DIE AND RESIN PIPE

摘要

A pipe extrusion die which regulates a flow of molten resin owing to a resin reservoir, and equalizes the flow rate of the resin extruded through any portion of the circumferential passage in the die. This prevents the occurrence of unevenness of the wall thickness of a resin pipe. The pipe extrusion die is provided with a constriction portion, which includes a core, a shell fitted around the core, and a resin reservoir formed between the core and shell and constituting a part of a flow passage in which a molten resin flows as a raw material for pipes. This resin reservoir is provided in at least one of the core and shell, and has a ring-shaped form extending around the axis of the die. The resin reservoir has a semicircular cross section.