Patent GB-1186641-A (GB)
Title: Indexing Mechanism and Process
IPC: B23K11/31
Filed: 1968-04-11
Abstract: 1,186,641. Welding by pressure; machine tool details. FORD MOTOR CO. Ltd. 11 April, 1968 [12 April, 1967], No. 17488/68. Headings B3B and B3R. [Also in Division B4] An indexing mechanism for indexing equipment comprises a track 10, stop means 26 on the track, a frame 28 for movement along the track and for carrying the equipment, a first motive device 52 on the frame acting parallel to the track, a frame positioning member 39 on the frame to engage the stop means 26 on the track, an indexing carriage 60 on the frame for movement relative to the frame by the first motive device 52, the carriage including a second motive device 68 and a carriage positioning member actuated by the second motive device 68 to engage the stop means 26, and a control circuit actuating the first motive device 52 to index the carriage while the frame positioning member engages the stop means, the frame undergoing an indexing movement after movement of the carriage. The track 10 comprises a base 12 with channels 22, 24 and the stop means comprises a toothed rack 26 fixed to the base 12 between the channels. The frame 28 has on a main portion 34 rollers 30, 32 engaging the channels and carries on the main portion 34 a pneumatically-operated spotwelding gun 43 for welding a fixed member 44. An attached trailer portion 36 of the frame carries a horizontal pneumatic cylinder 52 having its piston-rod 53, Fig. 2, connected to the base 59 of a carriage 60 slidable on the main portion 34 of the frame above an opening 38 in the portion 34 directly above the rack 26. A longitudinally extending arm 61 is positioned above the base 59 on a vertical pin 63, Fig. 2, on the base 59 and a slot 62 in the arm rides in the U-shaped upper portion 40 of a frame positioning member 39 having teeth 41 at its lower end and being slidable in a bore in the main portion 34 of the frame. A journal 42 between the legs of the portion 40 locates the arm 61. A vertically acting pneumatic cylinder 68 on the carriage 60 is attached to the arm 61 and its piston-rod 70, Fig. 2, extends through the opening 38 where teeth 72 on the bottom of the rod may engage the rack 26, a flange 74 on the rod being arranged to contact the base 59 after teeth 72 engage rack 26 but before the piston in cylinder 68 reaches the. limit of its travel so that further movement lifts the cylinder 68 and arm 61 off the base 59 to disengage teeth 41 of member 39 from the rack 26. An air valve 54 with operating solenoids 56, 58 is mounted above cylinder 52 and a direction reversing switch 46 and weld interrupting switch 48 are attached to the frame. Limit switches 78, 79 are provided on the frame to be engaged by the carriage at its end positions. The control circuit is such that with the electrodes of the spot-welder initially opened, the rod 70 is lowered to engage the rack 26, the member 39 is raised to disengage the rack and carriage 60 is at the left-hand end of its movement as in Fig. 1. The start button is pressed and air to cylinder 68 lowers the frame positioning member 39 and raises carriage positioning member 70, air is supplied to cylinder 52 to index carriage 60 to the right-hand end of its travel on the frame and air is supplied to clamp the electrodes on to the work and a weld is made. The electrodes are then unclamped, the rod 70 is lowered to clamp the carriage and the member 39 is raised to unclamp the frame. The frame is then drawn to the right by the cylinder 52 to the position shown in Fig. 1. Welds are made in sequence under the control of a timer until the limit switch 46 contacts a ramp 47 to reverse the direction of travel. The snotwelding gum may be slidable on the frame and guided by ramps to follow vertical changes in the work or multiple electrodes may be employed. Spot-welds may be made on vehicle body parts and the mechanism may alternatively be used for drilling, stapling, nailing, tacking or stitching apparatus.