Patent ID: 8062141
Filing Date: 2011-11-22
Classification: B21K,C21D,F16B,Y02P

Abstract:
1. A process for making a clinch fastener including a body portion having a top face and a bottom face connected by a peripheral body face extending about the body portion and an axially extending pilot portion surrounding a central bore which may be a smooth bore thread blank or pre-threaded, comprising the steps, a) providing said fastener having a substantially uniform as formed or as through-hardened hardness, b) selectively hardening a transverse extent of said pilot portion to form an inner zone adjacent said bore and an outer zone adjacent an outer periphery of said pilot portion having differing hardness values, c) said inner zone having a hardness substantially equal to that of the fastener as formed or as through-hardened, and d) said outer zone having a hardness greater than that of said inner zone whereby said fastener may be used to pierce and/or plastically deform metal members having hardness values greater than the hardness values of metal members with which a similar fastener having said as formed or as through-hardened hardness may be used.