Spreading anchor

A spreading anchor wherein comprising an anchor rod (2) having a stem (12) provided, at a front end thereof when viewed in a setting direction, with a cone (3) widening outwardly towards a free end thereof;

• and a longitudinally displaceable sleeve (4) pushed over the anchor rod (2) and having at a front end (8) cutting tabs (5) which are provided with cutters, are separated from each other by gaps, extend from a plastic hinge (11) toward the cone (3), and are spread radially upon sliding of the sleeve (4) over the cone (3), the sections of the cutting tabs (5), which extend from free ends thereof in a direction toward the plastic hinge (11), having an outer surface (6) remote from the cone (3) and formed at least in a cutting region thereof as a substantially toroidal surface, the cutters, which are provided at a free end surface of the front end (8) of the cutting tab (5), extend transverse to an axis (A) of the stem (12), the cutting tab (5) has a rear surface (7) having a contour, which matches the toroidal surface of the section of the outer surface (6) to a greatest possible extent and which passes into a contour of an inner surface (13) of the sleeve (13) which extends parallel to the axis, whereby a curvature (.kappa.) closer to the contour of the rear surface (7) has a center which coincides with the curvature center (m) of the toroidal outer surface (6).

A spreading anchor according to claim (3), wherein the rear surface (7) along a longitudinal extent thereof is formed by sections of cylindrical and conical surfaces an arrangement of which is so selected that the rear surface (7) at least sectionwise flatly abuts the cone (3) in a spread condition of the cutting tab.