Patent ID: 7320567

Claim:
Clamping device for clamping a tool ( 8 ), or tool holder in a working spindle ( 4 ), comprising a drawbar ( 10 ) arranged to be displaced within the working spindle ( 4 ), a clamping set ( 12 ) arranged in the working spindle ( 4 ) and displaceable between a clamping position and a released position by means of the drawbar ( 10 ), a spring arrangement ( 14 ) provided for the drawbar ( 10 ) to generate the drawing force for the clamping set ( 12 ) and a releasing unit ( 49 ) by means of which the clamping set ( 12 ) may be moved into the released position by the drawbar ( 10 ) against the force of the spring arrangement ( 14 ), characterized in that the releasing unit ( 49 ) may be operated by an electrical actuator ( 62 , 63 , 53 , 54 ) including a motor ( 62 , 63 ) having a stator ( 63 ) and a rotor ( 62 ), and also including a linear motion unit ( 53 ; 54 ) to convert the rotary movement of the motor ( 62 , 62 ) to a linear movement to displace a piston ( 66 ) into and out of displacing engagement with the drawbar ( 10 ), the linear motion unit ( 53 , 54 ) including a non-rotary threaded spindle ( 53 ) and a rotary threaded spindle sleeve ( 54 ) inside the rotor ( 62 ).