Chuck with dual independently actuable sets of jaws

Abstract

A chuck for a chucking machine has a rotatably supported toroidal body having first and second sets of jaws projecting inward from its inner periphery, the first and second sets of jaws being axially spaced from one another. Each of the sets of jaws has its own actuating mechanism comprising a lead screw engaging each jaw for the movement thereof. All of the lead screws of a set are controlled by a ring gear actuable by a fluid pressure motor to simultaneously advance or withdraw all the jaws of a set. At least the second set of jaws has a slip clutch associated with each lead screw to allow engagement of all jaws with the workpiece regardless of irregularities in the workpiece surface. Separate locking means are provided for each sets of jaws comprising a collar associated with each lead screw, a locking member biased against each collar to apply locking force to the associated jaw and a fluid pressure motor to release the locking force of the locking members of a set to allow advance or withdraw of the jaws by the lead screw. Each jaw has an associated counterweight engaged through a pinion gear to help maintain clamping force at high rotational speeds. The chuck has fluid supply means to the fluid pressure motors including at least one annular channel in the toroidal body open on one axial side, a stationary annular face seal in the stationary portion of the chuck adjacent the open side of the annular channel, a fluid supply passage through the face seal and means for biasing the base seal toward the annular channel for sealing only during the passage of pressurized fluid therethrough for actuation of a fluid pressure motor.