GB588179A - Improvements in indexing mechanism for a machine table - Google Patents

Abstract

588,179. Drilling-machines ; turrets. BURGESS, A. F. (Barnes Drill Co.). Feb. 2, 1945, No. 2681. [Class 83 (iii)] In a mechanism for indexing, a reversible electric-motor drives a yieldingly mounted worm-gear in conjunction with a series of tripoperated switches to turn the turret to its indexed position, reverse and stop the motor. The rotatable table of a turret 10 is provided with worm-wheel teeth 26 meshing with a worm 46 splined and slidably mounted on a shaft 43, the worm body being extended to accommodate a yoke 61 integral with a notched shaft 60. A spring 50 urges the worm towards a collar 49 fixed to the shaft 43, the shaft being driven through bevel-gearing from a reversible electric-motor M, mounted on the stationary frame 32 of the turret. Inserts 24 are secured to the turret ring at the required indexing positions, each insert having a projection 27 with an inclined face 29 and a straight face 28. The inclined face works against a mating face on a turret locking-member 35 slidably mounted in the turret frame 32 and urged into contact with the face 29 by a spring 37. A stopmember 25 is also slidably mounted immediately above the locking-member 35 and is similarly spring-loaded to cause a projection 30 to engage the straight faces 28 of the inserts 24, the projection 30 being shaped to permit the inserts 24 to force it out of interference as the turret rotates in a clockwise direction. The locking-member 35 is provided with a roller 64 which, in conjunction with the notched shaft 60, moves the member 35 away from the path of the inserts 24, as the shaft moves laterally. The roller 64 also operates a limitswitch LS-2. The internal periphery of the turret is provided with a trip 57 at each indexing position to operate two limit switches LS-1 and LS-1a. In circuit with the motor is a push-button starter for energizing a starting- switch circuit, after which the limit-switches open this circuit and close a reversing-circuit until the limit-switch LS-2 cuts in to stop the motor at the finish of the indexing operation. On closing the starting circuit, the worm is rotated and moves axially up to collar 49 after which the worm drives the turret, the shaft 60 having moved with the worm to displace the locking-member 35. With an insert 24 slightly past its true indexing position the limitswitches reverse the motor thereby reversing the turret against the stop-member 25, after which the worm moves back past its original position to compress the spring 50 to a predetermined limit, when the switch LS-2 operates to stop the motor, the locking-member 35 having been returned to its inner position, and wedging the projection 27 against the stopmember 25, thereby securing the turret in its true indexed position.