| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a roller shaft and a flapper with no burrs even though resin parts of the roller shaft and the flapper have large wall thickness, simply at a remarkably reduced const while having a strong torque. SOLUTION: A roller shaft 1 is composed of a metal shaft 2 and resin rollers 5, 6, 7 fitted on the metal shaft 2. The resin rollers 5, 6, 7 are formed by such a method that core parts 8, 9, 10 are integrally molded around the metal shaft through injection molding, and thereafter, the surfaces of the core parts and the outer surface of the shaft are integrally molded thereto with outer shell parts 11, 12, 13. During the manufacture thereof, dies having a primary molding part which can integrally molding the core parts of the rollers on the metal shaft, and a secondary molding part 17 which can integrally mold the outer shell parts around the outer surfaces of the roller core parts and the shaft. A molded product in the primary molding part is inserted in the secondary molding part so that the primary molded product and a completed product can be simultaneously molded. Further, a flapper 21 can be molded in a similar configuration.
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