| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently secure the service life of the working surface 22 of a pressing die 17 by improving this pressing die 17 which is used for forming a caulked part 11 in the inner end part of a hub main body 6. SOLUTION: The hardness of the working surface 22 is≥60HRC (Rockwell C hardness) and mirror finishing is applied to this working surface 22. By adopting this constitution, the above problem is solved. COPYRIGHT: (C)2006,JPO&NCIPI
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