APPARATUS FOR PRODUCING HOLLOW SHAFT

PROBLEM TO BE SOLVED: To safely make a linear tooth part formable(spline, serration, etc.) at high precision on the peripheral surface, even in the case that the uneven thickness exists in a hollow blank. SOLUTION: A die 13 formed with a linear projecting and recessing forming part 12 and a center die 15 formed with a center hole forming part 14, are continuously arranged in a holder 17, and in the die 13, a mandrel 16 is disposed in the axial hole 19 of the center die 15 through an elastic body 21 under state of inserting a small diameter shaft part 20. When the hollow blank W is pushed into the annular gap between the die 13 and the mandrel 16 with a punch 10, the mandrel 16 is parallel shifted while elastically deforming an elastic body 21 following to the uneven thickness of the hollow blank W, and in this result, on the outer peripheral surface of the hollow blank W, the linear tooth part is formed at high precision and the breakage of the mandrel 16 is prevented. Further, at the last step of the formation, the center hole is simultaneously processed on the inner peripheral edge part at the tip edge part of the hollow blank W with the center hole forming part 14. COPYRIGHT: (C)2006,JPO&NCIPI