GB992689A - Indexing mechanism - Google Patents

Abstract

992,689. Machine-tool details. T. I. (GROUP SERVICES) Ltd. Sept. 11, 1961 [Aug. 6, 1960], No. 27343/60. Heading B3B. An indexing mechanism comprises a reciprocating member adapted to rotate a second member from one position to another position on a forward stroke, and to actuate tool control means on the return stroke. A spindle 14 rotatably carries a disc 19 having teeth which engage four pinions 21 keyed to spindles 22, and has a second disc 18 keyed thereto. Spindle 14 is adapted to receive a square or circular workholder and the work is secured to the upper face of the holder. In a modification, the workholder is in the form of a regular prism with the work secured to the sides. An axial passage in the spindle supplies air for locking the work to the holder. A reciprocable bar 33 is moved by the piston-rods 34 of hydro-pneumatic cylinders 35, and carries a peg 37 slidable axially in a bush 38, which co-operates with aligned holes in blocks 41, slidably mounted in guides 42 on discs 18, 19 so that as bar 33 moves from one end position to the other, the disc rotates through exactly 90 degrees. Two latches 44, 45 are provided to disconnect peg 37 from either disc 19 or 18 at the end positions of bar 33, and they are pivoted by a double acting pneumatic piston 50. Each spindle 22 has keyed thereto, at least one removable cam 25, which upon rotation of the spindle 22 actuates spring-loaded rods 31 which control the tools for operating on the work. In operation, Fig. 3, peg 37 is in engagement with lower disc 18, and rod 44 is in engagement with upper disc 19. Bar 33 is moved in the direction of the arrow, and peg 37 rotates disc 18 and spindle 14 through 90 degrees, with disc 19 being held stationary. At the end of the forward stroke, the piston in the right-hand cylinder 35 opens a pneumatic switch to operate a change-over valve which supplies air to piston 50, and causes it to move downwardly to disengage latch 44, and engage latch 45. As latch 45 is raised it pushes peg 37 into engagement with disc 19, and the downward movement of piston 50 operates a pneumatic switch 54 which reverses the supply of air to cylinders 35, and bar 33 moves in the opposite direction. During the return stroke, disc 19 rotates through 90 degrees to rotate spindles 22 through 360 degrees, and disc 18 is held stationary. At the end of this stroke, the piston in left-hand cylinder 35 opens a pneumatic switch to cause piston 50 to move upwardly thus returning latches 44, 45, and peg 37, to their initial positions, Fig. 3, a further pneumatic switch 53 being actuated, causing the cycle to be repeated. The stroke of bar 33 and the number of blocks 41 may be varied to provide, e.g., eight index positions.