| 摘要 |
PROBLEM TO BE SOLVED: To prevent the generation of a flaw in a molded article by achieving the good filling with an injection material. SOLUTION: The center pin 20 of a male mold 22 is inserted in the through- hole 16a of a female mold 16 to demarcate a cylindrical cavity 24. A plurality of gas venting grooves 30 opened upwardly to be spaced apart from each other are formed in the base 18 of the male mold 22 radially centering around the center pin 20. The annular gas sump groove 32, with which all of the gas venting grooves 30 communicate, concentric to the center pin is provided in the base 18 so as to be opened upwardly. Both of the gas venting grooves 30 and the gas sump groove 32 are hermetically closed from above by the femal mold 12 at a time of injection molding and the gas venting groove 32 communicates with the cavity 24 through the gas venting grooves 30. The opening depth of the communication parts with the cavity of the gas venting grooves 30 is set to a dimension smaller than the thickness dimension of a magnetic powder.
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