| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem wherein a re-bonded surface is again separated when a material is passed through the land part of an outer die in an expanding direction, that is, in a diameter widening direction and left in a molded product to become a void flaw after baking. SOLUTION: An extrusion molding die 12 is composed of the outer die 10 having a through-hole 20 for molding the outer periphery of the hollow body and the inner die 11 arranged in the through-hole 20 to mold the hollow part of the hollow body and constituted so as to extrude the material through the gap between the outer die 10 and the inner die 11 to mold the hollow body. The through-hole 20 has a taper part 10a tapered toward an extrusion direction and the land part 10b continued to the taper part 10a and tapered toward the extrusion direction so as to have an inclination smaller than that of the taper part 10a. A straight part 11a is provided to the inner die 11 at least at the position corresponding to the land part 10b and the ratio (Ko/Ki) of the gap between the inner and outer dies 10 and 11 at the inlet and outlet of the land part 10b is 0.875-below 1. COPYRIGHT: (C)2005,JPO&NCIPI |
