Patent GB-309365-A (GB)
Title: Improvements in or relating to indexing mechanism for metal cutting and the like machine tools
IPC: B23Q5/00
Filed: 1928-09-10
Abstract: 309,365. Randles, G. E. Sept. 10, 1928. Drilling - machines. - In indexing- mechanism of the type wherein a rotary element is indexed, the element is moved transversely to its axis and parallel to its axis during indexing. As applied to a vertical drilling-machine a number of work-holding fixtures such as W, Fig. 1, are attached to a turret 25, Fig. 4, rotatably supported on a carrier 22 which is movable in a guideway 21 on a base 20 adapted to be bolted to the work-table 2. The turret 25 is supported by a ball bearing 37, Fig. 4, adjustable at 39, on a central pillar 35 carrying a roller 36 resting on a cam shaped portion 41 of a transverse bar 40 slidable in the carrier 22. The cam bar 40 is moved axially to raise the. turret prior to indexing by a cam 57, Fig. 7, on a main cam bar 50 which is attached by a slotted connection 54, Fig. 1, to the lower end of lever 51 having a fixed pivot 52 and a vertical slot 53 engaged by a roller 11 on the drill-head 3. The upper end 53<1> of the slot is inclined so that when the drill-head reaches its uppermost position the lever 51 will be rocked and the turret raised from its support. The axial movement of the bar 40 is limited by an adjustable stop 59, Fig. 7. Two pair of toggle links 60, 62 are arranged one at each side of the carrier 22, the links being hinged together at 64, to the carrier at 63 and to the base 20 at 61. A lug 65, Fig. 7, on one of the links 60 carries a roller 66 engaging a slot 67 in the end of the cam bar 50, the arrangement being such that after the turret has been raised the toggles will be broken and the carrier will be moved on the base 20 to the dotted position shown in Fig. 1. This movement causes a pinion 85, Fig. 9, journaled in the carrier, to roll on a rack 86 secured to the base, the pinion carrying the arm 82 of a Geneva, mechanism and causing a roller 82" on the arm to engage a radial slot 80 in a Geneva wheel 70 rotatable on the hub 31 of the turret. Annular teeth 73 on the wheel 70 are in mesh with four pinions rotatably mounted on studs projecting from the base and serving to impart rotation to a spur gear 75 keyed to the turret. For a six station turret there are 10 of the radial slots 80 and the ratio of the gearing 73 &c. is 6 : 10. In operation, when the drill-head reaches the top of its stroke the cam bar 50 is actuated to raise the turret until bushes in the turret are clear of cylindrical locating plugs on the carrier 22, during which motion the Geneva wheel 70 is raised to the position shown in Fig. 9, in which the roller 82" registers with one of the radial slots 80. 'The toggles are then broken and the carrier is given a rectilinear movement on the base to cause the pinion 85 to roll on the rack 86 and rotate the wheel 70 one, index division, thus indexing the turret. Further movement of the carrier on the base causes the roller 58, Fig. 7, on the cam bar 40 to contact with a fixed cam 68 on the base and return the cam bar to its original position, thus lowering the turret on the positioning plugs and disengaging the wheel 70 from the roller 82". As the drill-head commences its downward stroke the lever 51 is returned to its vertical position and the cam bar 50 straightens the toggles so as to restore the turret to its working position and place the new work-holding fixture W beneath the drill T, this movement of the carrier also restoring the arm 82 of the Geneva mechanism to its inoperative position. The arm 82 has a circular portion 87, Fig. 9, which engages arcuate recesses in the Geneva wheel 70 to lock it in its lowered position.