US Patent 7922257 Circular-shank tool comprising a tool holder

A circular-shank tool including a tool holder for improving the centering of the shank of the circular-shank tool in the locking sleeve by a configuration of the retaining elements and to improve an ability of the shank to rotate in the sleeve. To achieve this, the retaining elements are distributed between two stamped edges that lie transversely with respect to a longitudinal axis of the locking sleeve and are stamped inwards or indented, the stamped edges extend over part of the circumference of the locking sleeve and are interspaced at a distance that corresponds to the width of the peripheral groove in the shank of the circular-shank tool and the retaining elements form a coaxial concave centering section facing the convex groove base of the peripheral groove.