MOLD FOR EXTRUSION MOLDING OF HOLLOW PIPE

摘要

PROBLEM TO BE SOLVED: To suppress irregularity of wall thickness caused by irregularity of a temperature distribution and to simplify adjustment of the irregularity of the wall thickness. SOLUTION: A mandrel 3 is arranged at the center part of a mold substrate 1 and a cap 11 is attached to the mandrel 3 through a retainer 15 so as to surround the column part 3c of the mandrel 3. An annular flow rate adjusting member 12 is held between the cap 11 and the mold substrate 1 in a rotatable manner. The material flow channel 13 between the cap 11 and the mandrel 3 has a constant gap over the entire periphery thereof. The flow rate adjusting member 12 has a circular inner peripheral surface 12b eccentric with respect to the outer peripheral surface 12a thereof and the material flow channel 19 between the mandrel 3 and the flow rate adjusting member 12 has a passage cross-sectional area non-uniform in the peripheral direction thereof. Extrusion molding is performed by rotating the flow rate adjusting member 12 in a direction setting off the non-uniform wall thickness of a molded article generated by a temperature or the like to obtain the molded article having wall thickness almost constant over the entire periphery thereof. COPYRIGHT: (C)2003,JPO