Patent ID: 7677074
Filing Date: 2010-03-16
Classification: B21J,B21K,F16B

Abstract:
1. Method for the manufacture of hollow body elements for attachment to components consisting of sheet metal, said hollow body elements having a substantially square or rectangular outline, by cutting individual elements to length from a section present in form of one of a profile bar and a coil after prior punching of apertures into the section, using a progressive tool having a plurality of working stations in each of which respective operations are carried out, the method comprising: a) in a first step, starting from a section rectangular in cross-section, an upsetting process is carried out which leads to a cylindrical recess having a diameter and a recess base at a first broad side of the section and to a hollow cylindrical projection having an inner space with an inner diameter and a space base at a second broad side of the section opposite to the first broad side with a web of material being present between said recess base and said space base and the projection being surrounded by a ring recess, wherein, during this step, the diameter of the cylindrical recess and the inner diameter of the hollow cylindrical projection are made substantially the same, b) in a second step, said web of material is punched out to form a through-going aperture having a diameter which substantially corresponds to said diameter of said recess and to said inner diameter, c) in a third step, which is combinable with the second step b), the hollow cylindrical projection is flattened at its free end for the formation of a piercing section and an undercut at an outer side of said hollow cylindrical projection, the hollow body element being subsequently separated from the section.