| 摘要 |
PROBLEM TO BE SOLVED: To prevent the bearing storage part of a yoke from being deformed after a shaping process. SOLUTION: In the manufacturing method of a yoke 1 having a bearing storage part 5 in the shape of a tube with a bottom at the blocking wall 4 of a yoke body 2, and in the shaping process of the bearing storage part 5 using a shaping punch 21 and a shaping die 41, there are formed in the shaping punch 21 an inner diameter restraining part 29 in a R-chamfering shape and, in the shaping die 41, an outer diameter restraining part 55 in a C-chamfering shape. The inner diameter restraining part 29 of the shaping punch and the outer diameter restraining part 55 of the shaping die can prevent deformation from remaining which is caused by compression on the material of the bearing storage part 5 in the shaping; therefore, it prevents the entrance side from reducing and the depth side from expanding in diameter in the bearing storage part 5 after the shaping, thereby enabling improved cylindricity to be maintained. Consequently, by preventing the reduction on the entrance side and the expansion on the depth side in the post-shaping bearing storage part, function of the bearing in the storage part can be protected against degradation, enabling performance to be enhanced in the motor for which the yoke is used.
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