GB534447A - Improvements in work holding or chucking mechanism - Google Patents

Abstract

534,447. Drilling ; screwing; turret workholders. FAIRWEATHER H. G. C. (National Acme Co.). Feb. 29, 1940. No. 3787. [Class 83 (iii)] In a work-holder for drilling and screwing machines adapted for holding articles such as pipe sockets, means are provided for gripping the work and indexing it in two positions 180 degrees apart so that both ends may be operated upon in sequence by the tool. The work is gripped by jaws 1 moved radially in a body 8 by a rotary cam plate 6. For small work the jaws are clamped by a wedge and screw 3 in a holder 2 mounted in a jaw block 5, for intermediate sized work the jaws are mounted in spacers 16 in the block 5, and for large work the jaws are clamped directly by a wedge 3<SP>1</SP> in the block. The blocks are guided by ribs 10 in grooves in the side plates 12 which are attached to the body 8, and members 13, attached by screws 13' to the side plates, carry felt wipers 14 engaging the jaw blocks 5 to exclude cuttings &c. from the cam surfaces. Ejectors 15 attached to the members 13 centralize the work and prevent it from adhering to the jaws when the holder is opened. The cam plate is rotated by a hydraulic plunger 17 operating in a cylinder 18 provided with packing 20 and end covers 21. A pin 19 engages a groove in the plunger to prevent its rotation. The body 8 has trunnions 23<SP>1</SP> bushed at 23 to rotate in bearings 24, 25 in the base of the machine and is indexed by a gear 27 on one trunnion. This gear engages a pinion 32, Fig. 3, driven from a hydraulic motor 29 through gearing 31. An indexing plunger 44 coacts with notches 39 in a disc 38 attached to the trunnion and is moved into engaging position by a spring 48 and is withdrawn by a lever 43 actuated by a hydraulic piston 42. When oil is admitted to cylinder 41 the plunger is removed from the disc and after the piston 42 has uncovered a port 46<SP>1</SP>, oil is allowed to pass from the motor 29 by pipe 46 to an exhaust pipe 47, thereby starting the motor to rotate the gear 27. The plunger 44 rides on the periphery of the disc 38 which recedes towards the notches 39 so that the piston 42 is gradually retracted to reduce the motor speed as the index position is approached, the rotation being finally stopped when the plunger drops into the notch. Pressure is cut off from the cylinder 41 when the plunger is clear of the notch in the disc, and the supply to this cylinder may be controlled by the tool head when it reaches the end of its retractive stroke, or by another part of the machine such as a cam &c. or by hand.