Process for manufacturing holes on the circumference of hollow sections

Abstract

A process for manufacturing holes on the circumference of a hollow section situated in an internal high pressure forming tool uses the action of a punch integrated in the forming tool. A desired breaking point is formed on the hollow section, which follows the edge contour of the operating face of the punch; and after the withdrawal of the punch, the hollow section material surrounded by the desired breaking area, acted upon by internal high pressure, is extracted from the hollow section from the inside to the outside, forming a hole. In order to produce holes on the circumference of hollow sections, in which the shape of the outer circumference of the hollow section is maintained, the wall of the hollw section is weakened to form an unstable thin area. The punch penetrates into the wall of the hollow section at an internal high pressure which corresponds to the forming pressure for forming a hollow blank inserted in the forming tool. When the punch is withdrawn, the internal high pressure, tears the hollow section material surrounded by the thin area out of the hollow section in the withdrawal direction of the punch.

Dependencies are inferred from the claim text.