Abstract: Method and apparatus are disclosed wherein a required threaded hole is formed in a hydroformed part with a single tool while the part remains in a hydroforming die cavity. In forming the threaded hole, a hole is first pierced in the wall of the part and then an annular region of the part extending about the hole is extruded inwardly to form an integral tubular neck defining a hole of predetermined depth. The hole is then expanded in a sizing operation to a diameter determined by the required thread to be formed therein by material displacement and the required thread is then formed in the wall of the hole in a material displacing manner.

Abstract: A punch for piercing and sealing hydroforming parts has a roll forming surface that produces an internal rolled edge portion in a formed part immediately following the punch piercing the part wherein the rolled edge portion acts to effect a tight high pressure seal between the part and the punch as the punch continues to form a required hole in the part. The roll-forming surface extends either partially or completely about the punch in determining the extent of the rolled edge portion in the part that it produces and is located between an end portion that effects the piercing operation and a larger finishing portion that completes the formation of the required hole.