Patent ID: 8635894

Claim:
Process for producing hollow bolts comprising the following steps: forming a longitudinal bore in a shank of the bolt; forming longitudinal grooves extending along a length of the shank from near the head of hollow bolt to a lower end of the shank, the longitudinal grooves being spaced apart from each other by longitudinal elevations; after forming the longitudinal grooves and the longitudinal elevations on the shank, the method further comprising the step of: rolling circumferential notches onto the shank of the hollow bolt, in a manner such that the circumferential notches are separated from each other by circumferential elevations, and the longitudinal grooves including a cross-section (C), wherein part of material of the shank displaced during forming of the circumferential notches by rolling flows into the longitudinal grooves without deformation of an annular perimeter of the longitudinal bore, and wherein the step of rolling the circumferential notches further comprising: providing cylinder-shaped bottoms in each of the circumferential notches, and providing V-shaped gaps which are spaced apart from each other along an outer circumferential edge of the circumferential elevations, wherein the V-shaped gaps are provided only in positions spaced radially outwardly and apart from where the longitudinal grooves were previously formed.