Patent ID: 6867396

Claim:
An apparatus for inductively heating a sleeve section of a tool holder holding a shank of a rotary tool in a press fit in a central holding opening of the sleeve section coaxially with an axis of rotation of the tool holder and releasing the shank upon heating, the apparatus comprising: a) an induction coil arrangement with at least one induction coil for heating the sleeve section, wherein the at least one induction coil includes a coil core of magnetizable material and is arranged eccentrically offset from the sleeve section without wrapping around the sleeve section; b) a yoke arrangement of magnetizable material for concentrating magnetic flux of the induction coil arrangement onto and distributed around of the sleeve section such that the magnetic flux enters and exits the sleeve sections at positions situated at an axial spacing from one another, wherein the coil core of the at least one induction coil is connected to the yoke arrangement magnetically conducting; and c) means for supplying electric current of periodically varying magnitude to the induction coil arrangement.