| 摘要 |
PURPOSE:To obtain a hollow cam shaft which has sufficient rigidity, strength and accuracy, by utilizing a hollow cam shaft formed by bulge working, as a forming die, inserting other metallic pipe into its inside, and performing the bulge working. CONSTITUTION:A steel pipe 1 of a metallic pipe which has performed drawing to the tip in advance is placed on a die 3, and the tip drawn part is closed by a stopper 5. A punch 4 and the die 3 are formed as one body, and to the rear end of the steel pipe 1, a pressurized liquid injecting nozzle 6 is made to press- contact, and a pressurized liquid is injected. The steel pipe 1 bulges to the outside in the recessed part of the punch and the die, and the first hollow shaft 12 provided with a cam part, a journal part and a shaft part is formed. Subsequently, the stopper 5 is moved backward, also the nozzle 6 is shunted, a steel pipe 13 of other metallic pipe is inserted into the first hollow shaft 12, a drawing part 14 is closed by the stopper 5, and from the nozzle 6, the pressurized liquid is injected. The steel pipe 13 bulges out to the inside surface of the first hollow shaft 12, by which the second hollow shaft is formed, and desired hollow shaft is obtained. |
