Patent ID: 8707750

Claim:
A method for deforming a cross section of at least one longitudinal section of an oblong object consisting predominantly of relatively hard material, comprising: clamping the at least one longitudinal section near its ends with clamping devices with faces facing each other and subsequently upsetting the at least one longitudinal section in a controlled manner by an axial pressure force in between the faces into at least one predefined shortened and thickened longitudinal section and simultaneously exerting along practically an entire contour sheath of the at least one longitudinal section an inwardly directed counter pressure by counterpressure means in such a way that, with progressive deformation during shortening by upsetting to the at least one thickened longitudinal section, the total volume of the at least one longitudinal section to be deformed, bounded by the contour sheath and the faces remains substantially constant while said counter-pressure means move outward in a controlled manner.