| 摘要 |
PROBLEM TO BE SOLVED: To extend the life of an injection mold, to prevent the filling irregularity of a resin at the time of injection molding of magnetic pole pieces, and to prevent the generation of magnetic force irregularity in the respective magnetic pole pieces of a magnet. SOLUTION: A non-magnetic precipitation cured type stainless steel is used as a material, and ageing treatment is applied to stainless steel of at least a fixed mold 41 and a movable mold 42. At least the cavity surface 51 of the movable mold 42 is subjected to nitriding treatment to be brought to a magnetic layer. The cavity surfaces 51 of both of the fixed mold 41 and the movable mold 42 are coated with hard layers 41A and 42A. Flow rate regulation valves 9 are provided to respective runners 7 to provide the injection mold 4 wherein the inner periphery of a cavity is heated prior to injection molding. COPYRIGHT: (C)2004,JPO
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