| 摘要 |
A quick fixture changing apparatus for the fourth axis turn table of a machine tool. A pneumatic servomechanism exerts force on a drawbar, which is releasably attached to the fixture plate. The drawbar passes through the central opening of the turn table, so that the servomechanism, drawbar, and fixture are all axially aligned. An intermediate fixture plate is permanently mounted to the turn table, and has dowels for aligning the work holding fixture plate. When pneumatic pressure is relaxed, the fixture plate is manually lifted from the fourth axis. Tedious threading of fixture plates is eliminated. A new fixture plate, which has been prepared during the prior machining operation, can then be mounted on the dowels. Air pressure is restored, and the new fixture is securely locked in place. With 80 psi (5.5 kPa) operating pressure, a servomechanism of 6 inch (15 cm) diameter can develop a clamping force of 1800 lb (800 N). Displacement under the forces of machining is successfully resisted by the clamping force in combination with alignment dowels. A manual valve controls pneumatic pressure for both clamping and relaxing. A rotary joint enables the pneumatic supply to remain connected to the servomechanism. In one embodiment, the piston of the servomechanism is directly attached to the drawbar. In an alternative embodiment, a wedge moved by the servomechanism occupies a slot formed in the drawbar. This arrangement defeats potential compression of the air within the servomechanism. The novel clamp requires ordinary compressed air apparatus, and provides significant savings in labor time.
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