Machine tool chucking device

Claim 1

A WORK HOLDER ADAPTED TO RECEIVE A WORKPICE HAVING A FRUSTO-CONICAL END COMPRISING A SPINDLE HAVING ONE END AGAINST WHICH THE WORKPIECE IS ADAPTED TO BE SEATED, A COLLET COMPOSED OF A PLURALITY OF FINGERS ANNULARLY SPACED ABOUT SAID SPINDLE AND ADAPTED TO MOVE LONGITUDINALLY RELATIVE TO SAID SPINDLE, SAID COLLET HAVING AN INNER TAPERED ANNULAR SURFACE CONVERGING TOWARD AND ADJACENT THE ENDS OF SAID FINGERS, MEANS FOR RECIPROCATING SAID COLLET LONGITUDINALLY RELATIVE TO SAID SPINDLE SO THAT SAID ENDS OF SAID FINGERS PROJECT BEYOND SAID END OF SAID SPINDLE WHEN EXTENDED AND ARE SUBSTANTIALLY FLUSH THEREWITH WHEN RETRACTED, AN ANNULAR MEMBER LONGITUDINALLY FIXED WITH RESPECT TO SAID SPINDLE, CIRCUMVENTING SAID FINGERS AND IN CLOSELY SPACED RELATIONSHIP THEREWITH, SAID ANNULAR MEMBER HAVING A SURFACE TAPERING INWARDLY TOWARD SAID ONE END OF SAID SPINDLE, SAID FINGERS HAVING A TAPERED SURFACE COMPLEMENTARY TO THAT OF SAID ANNULAR MEMBER AND NORMALLY IN ENGAGEMENT THEREWITH, WHEREBY FORWARD MOVEMENT OF SAID COLLET CAUSED SAID FINGERS TO RADIALLY CONTRACT SO THAT SAID INNER EXTENDING TAPERED SURFACES ON SAID FINGERS GRASP THE FRUSTO-CONICAL END OF SAID WORKPIECE TO HOLD IT AGAINST ROTATION RELATIVE TO SAID SPINDLE, THE ANGLE OF SAID INNER TAPERED ANNULAR SURFACE ON SAID COLLET WHEN IN EXTENDED POSITION BEING IN THE NONLOCKING RANGE AND COMPLEMENTARY TO THAT OF SAID FRUSTO-CONICAL END OF SAID WORKPIECE SO THAT SAID WORKPIECE IS FORCED INTO SEATING POSITION.