| 摘要 |
PURPOSE:To simply form the good quality, high strength hollow rod by die working with a wall thickness restricting member inserted into a tube stock and using a half-forming product whose wall thickness is thickened at some places on the inner surface. CONSTITUTION:A half-formed product 10' having small inner diameter parts 11a and large inner diameter parts 11b at some placed in the axial direction is obtained by passing a metal tube stock 10 of steel, etc. through a die 12 with a wall thickness restriction member 11 inserted into the stock 10. The inward projecting wall thickened parts are projected onto the outside of the product 10' after pulling out the member 11 from the product 10'. When the product 10' having outside projection parts is again passed through the die 12, a half-formed product having inside thickened projections 10a is obtained. A prescribed machining is performed after an end side from a thickened part is contracted. Therefore, the good quality, high strength one-piece hollow piston rod is simply formed.
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