MANUFACTURE OF ACCURATE METALLIC DISK

PURPOSE:To turn the upside and downside faces of metallic disk into good flatness and smoothness by coining by making the surface roughness of the pressure face of a working die in the specified range rougher than the roughness of pressure face of a static die. CONSTITUTION:At press coining where the limit of expansion in the direction of diameter of metallic material is regulated with a die ring provided on the periphery of the pressure face of the static die, a disklike metallic material is coined by making the surface roughness of the pressure face of the working die rougher than the surface roughness of pressure face of the static die in the range of double and under. The material on the working die side of the material to be coined is liable to metal flow, but it is prevented by roughening the surface roughness. The accurate metallic disk with the good flatness and smoothness of the upside and downside face of metallic disk and the uniform and high quality is manufactured.