Patent ID: 8309895

Claim:
A device for clamping and unclamping of tools including a tool shaft comprising: a tool holder having a sleeve section comprising a center receiver opening for receiving the tool shaft, the sleeve section being configured to be inductively heated, the sleeve section being configured to retain the tool shaft seated in the receiver opening in a press fit and being configured to release the tool shaft upon heating of the sleeve section; and an induction coil assembly with at least one induction coil, the induction coil assembly being configured to be fed by an electric current for heating the sleeve section, the induction coil assembly includes a concentrator body which is magnetically conductive and electrically nonconductive or substantially electrically nonconductive, wherein the concentrator body concentrates a magnetic flux of the at least one induction coil onto a portion of a tool side end of the sleeve section, and wherein the concentrator body supports an induction attachment made of electrically conductive material and magnetically nonconductive material, the induction attachment being positioned on an outer end surface of the concentrator body and extending axially and radially from the concentrator body, the induction attachment being spaced by the concentrator body from the sleeve section so that the induction attachment reduces or eliminates a scatter field in a direction where an operator using the tool holder is located when changing tools, and including a retainer holding the induction attachment on the concentrator body.