| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a main piece integrated with an insulator by caulking a packaging part in which the service life of a die is prolonged by forming the packaging part with a die, and cracks in caulking the packaging part can be prevented. SOLUTION: The outer circumferential surface of a packaging part 131a is formed by forming the packaging part 131a and a smaller diameter leg part 122 in separate steps during cold forging. Since the wall thickness of a die 23 can be sufficiently ensured, a large rounding R can be formed in the vicinity of a packaging part forming part on the inner circumferential surface of the die 23, the deformation resistance of a stock is thus reduced, the fluidity of the material in the vicinity of the packaging part forming part is improved, shrinkage is made to hardly occur, and cracks occuring in caulking the packaging part can be prevented. |
