| 摘要 |
A plurality of axial grooves are formed on the outer circumferential surface of a shaft member by applying an arcuate edge defined between an end surface and outer circumferential surface of a rotatable cylindrical forming tool having a generally smooth surface. Typically, the rotational center of the forming tool is tilted backward as it is moved along the length of the shaft member. Owing to the plastic flow of the material of the shaft member, a pair of ridges are formed on either side of the groove. The end surface of the forming tool causes a more pronounced plastic flow than the outer circumferential surface of the forming tool so that one of the ridges is greater in height and higher in hardness than the other. This provides various benefits when this shaft member is press fitted into a bore of an armature core or the like.
|
