| 摘要 |
PURPOSE:To prevent burrs from arising in the crossing sections of large and small diameter sections, by setting the inner diameter of each large diameter section to a value equal to the inner diameter of the small diameter sections at both end thereof, and by gradually increasing the inner diameter of the large diameter section toward the center section thereof. CONSTITUTION:Wall surfaces defining relieves 101 are formed in an arcuate surface so that the diameter of each relief is set to be equal to that of small diameter sections defening a bearing hole 91 while it is gradually increased from each end to the center section thereof. Accordingly, the angle between the wall surface defining each relief 101 and each small diameter section of the bearing hole 91 becomes acute. Therefore, it is possible to effectively prevent burrs from arising at each of crossing sections of large and small diameter sections in the bearing hole 91. |
