| 摘要 |
PROBLEM TO BE SOLVED: To provide an extrusion molding die controlling the flow of thermoplastic resin and stabilizing the quality of a seamless product.SOLUTION: In the extrusion molding die, a shaft-like mandrel having a circumferential surface 3 is inserted into a cylindrical die body to guide the thermoplastic resin supplied to a gap between the mandrel and a die body, in the extrusion direction F from one end of the mandrel toward the other end. On the circumferential surface 3 of the mandrel, an introduction passage 17 and a plurality of spiral grooves 19 are formed. The introduction passage 17 includes a parent passage 171 and subsidiary passages 172 branched into two from the parent passage, and a passage area of the subsidiary passages 172 is made equal to the area obtained by bisecting the passage area of the parent passage 171. |
