Automatic adjustable power chuck system and method

The method of system 18 wherein the step of restoring said system to operation in the machining mode comprises the steps of:

• de-actuating said rotational power source;
• energizing said electromagnetic clutch means to connect said rotational power source rotor to the machine tool spindle;
• deactivating said rotary encoder means;
• de-energizing said electromagnetic brake means to disconnect said rotational power source stator from the machine tool spindle to prevent jaw adjustment;
• and
• storing in said processor means the position of said clamping jaws.

An automatic power chuck system, operable in machining and jaw adjustment modes for use in gripping a workpiece on a machine tool spindle, said system comprising:

• a power chuck having clamping jaws for gripping the workpiece in adjustable fashion with adjustable gripping force, said clamping jaws being being capable of grasping a workpiece and being adjustably mounted and radially displaceable in a chuck body;
• a set of teeth integrally formed with said clamping jaws intermeshing with a clamping jaw actuating means rotatingly mounted in said chuck body,
• a rotational power source comprising a stator and rotor for driving said clamping jaw actuating means in the jaw adjustment mode via a gear reduction means having an input and output member, said output member of said gear reduction means engaging said clamping jaw actuating means, said rotor being connected to said input member of said gear reduction means, said stator being connected to the machine tool spindle and said chuck body only during the jaw adjustment mode, wherein said gear reduction means, said clamping jaw actuating means and said rotor form an integral unit and rotate in unison with said machine tool spindle in the machining mode;
• and
• control means comprising rotary encoder means and processor means, said encoder means being rotatingly connected to said rotational power source rotor with a predetermined kinematic ratio between said rotary encoder means and said clamping jaws, said encoder means providing said processor means with position signals relating to said rotor for controlling the position of said clamping jaws during the jaw adjustment mode,
• wherein said processor means is operable to calculate the position of said clamping jaws and the speed of said rotational power source in accordance with said encoder means position signals,
• and wherein said processor means is operable to control said gripping force by adjustment of the rotational torque of said rotational power source in accordance with said predetermined kinematic ratio.