Cold deep hole forming device

摘要

A cold deep hole forming device is capable of forming, by cold forging a deep hole for an involute spline, etc. with high accuracy and in a simple way, even in a member to be formed that is partially different in thickness. A supporting base 1A supports the member W to be formed and a punch 1B forms the deep hole H in the member W. A clamp holder 3 is provided on the outer circumference of the punch 1B. A clamp 2 is composed of split clamping pieces 21 disposed in the clamp holder 3. When forming deep hole H in the member W with the punch 1B, the clamping pieces 21 are made to move in the direction of the center under fluid pressure so as to constrain the member W to be formed at its outer circumference having a small diameter portion WT.