摘要 |
PURPOSE:To improve fatigue strength and to reduce a cost of a disk, by cutting a groove on a sieve surface thereof at the surface roughness of approximately 0.8 to 0.4 concentrically with a center of rotation using a numerically controlled lathe, and by grinding the sieve surface so as to generate residual stress at a stage of superfinishing. CONSTITUTION:A pulley 4 is composed of a fixed disk 10 and a moving disk 12, a metallic belt 14 being contacted to them inbetween. On a sieve surface to which the belt 14 of disks 10, 12 is contacted, a spiral groove is cut by a numerically controlled lathe at a surface roughness of approximately 0.8 to 0.4, concentrically with a center of rotation. Then, finishing grinding is applied to the sieve surface by lapping in such a way that residual stress is generated in disks 10, 12. In this way, fatigue strength of disks 10, 12 is improved, and no need for special cutting panel or grinding panel leads to reduction of cost. |