Method and apparatus for the production of double-walled hollow sections by means of internal high-pressure forming

Abstract

The invention relates to a method and apparatus for the production of double-walled hollow sections by means of internal high-pressure forming, a first hollow section being inserted into a second hollow section, after which the double-walled hollow section thus formed is subjected to high internal fluid pressure in such a way in an internal high-pressure forming die that the double-walled hollow section is expanded. During this process, an air gap is formed between the first, inner, hollow section and the second, outer, hollow section. In order to produce double-walled hollow sections with an air gap between the inner and the outer hollow section in a simple manner and with a reduced process time, the proposal is to position the inner hollow section in a defined manner in the outer hollow section during insertion, forming a gap, to introduce an intermediate layer between the inner hollow section and the outer hollow section, filling the gap, and, after expansion of the double-walled hollow section by internal high-pressure forming, to dissolve the intermediate layer out of the hollow section via an opening formed at least in one of the hollow sections, opening up the gap as an air gap.

Dependencies are inferred from the claim text.