MANUFACTURING METHOD FOR MAIN METAL FITTING ASSEMBLY OF SPARK PLUG, MANUFACTURING METHOD FOR SPARK PLUG, AND MANUFACTURING DEVICE FOR MAIN METAL FITTING ASSEMBLY OF SPARK PLUG

摘要

PPROBLEM TO BE SOLVED: To accurately form screw threads of a screw section at a fixed position against a ground electrode at the time of forming of the screw section on a main metal fitting. PSOLUTION: A main metal fitting assembly 35 of a spark plug includes the cylindrical main metal fitting 3 extending in an axis CL1 direction and having the screw section 15, and the ground electrode 27 extending from the tip of the main metal fitting 3. A manufacturing process of the main metal fitting assembly 35 of a spark plug includes an arrangement process, a rolling process, and a positioning process. In the arrangement process, an intermediate assembly 31 having the ground electrode 27 is arranged between a plurality of rolling dies D1, D2 wherein respective processing surfaces face each other. In the rolling process, the screw section 15 is formed by rolling the intermediate assembly 31 with the rolling dies D1, D2 while the intermediate assembly 31 is interposed between the rolling dies D1, D2. After the arrangement process, positioning of the ground electrode 27 along a peripheral direction is carried out in the positioning process. PCOPYRIGHT: (C)2011,JPO&INPIT