| 摘要 |
PURPOSE:To easily heighten the surface hardness by forming a hardening layer on the grooved surface of a cast iron drum, and exposing an intermediate layer harder than the surface by grinding in a traverse drum of a high speed yarn winder. CONSTITUTION:A spherical graphite cast iron drum body is formed by vacuum casting or the like. After that, metal texture of a grooved surface thereof is exposed by abrasive working and mirror-surface like finished by buff polishing. Subsequently, the drum is installed in a vacuum furnace, and nitrogen gas is injected to invasion diffuse an iron nitride to the surface layer under 1-20Torr, at 400-600 deg.C for 1-10hr of glow discharge time. Thus, a nitride layer about 15-20mum is formed. After that, the grooved surface is ground about 10mum by high speed buff polishing to expose an intermediate layer of the nitride layer. Thus, the surface hardness of 800-1,000Hv before grinding is increased to 1,100-1,200Hv after grinding. |
