MOLDING DIE FOR MOLDING TUBULAR FORM AND MANUFACTURE OF TUBULAR FORM

摘要

PROBLEM TO BE SOLVED: To mold a tubular form with superior strength and rigidity in the circumferential direction. SOLUTION: An annular runner 3 is formed between the inner mold 1 and the outer mold 2 of a molding die 44. The upstream part of the inner mold 1 serves as a rotary mold part 11 which rotates centered around a shaft C in parallel with the extrusion direction of resin and the downstream part serves as a stationary mold part 12. The runner face of the stationary mold part 12 has a helical groove 9 formed extending in an opposite direction to the rotation direction of the rotary mold part 11, as viewed from the extrusion direction of resin. In addition, an annular runner outlet is provided in the downstream extremity 12e of the stationary mold part 12. A molding material mixture containing reinforcing fiber and a crosslinking thermoplastic resin is extruded from the mold 44. Thus it is possible to orientate the reinforcing fiber in the circumferential direction and obtain an inhibitory effect upon the rotation of the tubular form.