| 摘要 |
PROBLEM TO BE SOLVED: To prevent the inward tilt of a ring portion when a hole is made using a piercing punch for a recessed portion formed inside a ring portion on the external periphery side of a workpiece. SOLUTION: When an inner race 1 of a constant speed ball joint is punched by the piercing punch 7, the external periphery of the stem portion 15 on the base end side of the cutting edge portion 13 at the tip end of the piercing punch 7 supports the ring portion 3 on the external periphery side of the inner race 1 so as to restrict the inward deformation of the ring portion 3. COPYRIGHT: (C)2007,JPO&INPIT
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