| 摘要 |
PURPOSE:To reduce the working man-hour, and to improve the yield of a material by reducing a shaft diameter by bringing other part than a valve head part, in a heat resisting steel stock, to cold shaft drawing, and subsequently, executing the preupsetting and head upsetting. CONSTITUTION:A steel stock is prepared by cutting a heat resisting steel stock having a shaft diameter required for forming a desired head part 6, to a prescribed length. A valve stem part 10 is formed by executing cold shaft drawing through a die 12 and a punch 13, to other corresponding part than a valve head part of this stock. Subsequently, preupsetting of the valve head part 3 is executed to one end 2 of the base material by an electric reduce forging method, and also, a final head part 6 is formed by performing hot press upsetting. According to this method, shaft machining such as machining and grinding is not required, and also, a large head part 6 against the shaft diameter can be formed. Accordingly, the working man-hour is reduced and the yield of a material can be improved.
|
