Rotary flexure and air bearing support for rotary indexing system
View Patent ↗A highly position-stabilized indexable table or “dial” in which the dial is supported relative to a steel surface on a frame by one or more air bearings. A flexure mechanically connects the indexing motor to the dial in such a way as to be torsionally non-compliant, but axially compliant to decouple the dial from the motor shaft along the Z-axis. In one embodiment, the air bearings are mounted to the frame at uniformly angularly displaced positions under the dial. In another embodiment, the bearings are partially integrated into the dial. Negative (suction) preload can be used in either embodiment to increase air bearing stiffness and/or to allow inverted processing; i.e., mounting part fixtures on an undersurface of the dial.
1. An indexable dial system for translating workpieces in and out of a processing station comprising:
a dial having an axis of rotation;
a motor for selectively indexing the dial about said axis;
air bearing means supporting said dial; and
a flexure mechanically connecting said motor to said dial, said flexure being essentially torsionally non-compliant about said axis but compliant along said axis.
2. A system according to claim 1 wherein the air bearing means comprises a plurality of air bearings at spaced locations around said axis.
3. A system as defined in claim 2 further comprising a frame supporting said motor, said plurality of air bearings being attached to said frame under said dial.
4. A system as described in claim 1 wherein said air bearing means is formed in part in the underside of said dial.
5. A system as defined in claim 1 further including means for providing a negative pre-load on said air bearing means.
6. A system as defined in claim 1 further comprising a frame and wherein said air bearing means are mounted to said dial, said air bearing means further comprising vacuum means for providing pneumatic forces tending to draw said dial toward said frame.
7. A system as defined in claim 1 wherein the air bearing means is arranged to hold the dial against the force of gravity such that the dial is inverted.