| 摘要 |
PURPOSE:To improve the lief strength of a wheel in the machining of the nut seat of the bolt hole of a wheel by giving roller burnishing to at least the edge part of the nut seat and obtaining specular finishing. CONSTITUTION:In a wheel 1, a nut hole 2 including the rough shape of a nut seat 3 is machined from both sides with a step drill edge, and roller burnishing is given to at least the edge part 5 of the nut seat 3. In this roller burnishing, the rotating roller 6 of a tool body 7 is pressed against the nut seat 3, i.e., a spherical seat 4 and the edge part 5 via a coned disk spring 8 to carry out specular finishing, hardening the surface by machining, generating compression residual stress to improve strength, and improving the life strength of the nut- seat surface itself. Thereby, the plate thickness of the wheel can be made small reducing its weight due to the improved life strength. |
