Patent ID: 8651769

Claim:
A friction bolt with a tube ( 1 ) that can be widened and that is folded inward in a longitudinal direction, the tube having a longitudinal plane of symmetry ( 11 ) running in the longitudinal direction, the tube comprising: i) an outer part ( 3 ) with an essentially circular cross-sectional shape, the outer part ( 3 ) having a radius (R 2 ); ii) an inner part ( 5 ) arranged inside the outer part ( 3 ), the inner part ( 5 ) having lateral wall areas ( 9 ) with a radius of curvature (R 1 ); and iii) a gap ( 7 ) that extends in the longitudinal direction of the tube ( 1 ), the outer part ( 3 ), in an area of the gap ( 7 ), turns into the inner part ( 5 ), wherein the lateral wall areas ( 9 ) extend from a shape concentric to the outer part ( 3 ) to the longitudinal plane of symmetry ( 11 ), wherein the radius of curvature (R 1 ) of the lateral wall areas ( 9 ) is equal to 250% to 350% of the radius (R 2 ) of the outer part ( 3 ), and wherein the tube ( 1 ) is a longitudinally-welded tube ( 1 ), with a weld ( 13 ) in the outer part ( 3 ) of the tube ( 1 ) arranged laterally offset relative to the longitudinal plane of symmetry ( 11 ) of the tube ( 1 ).