GB668345A - Improvements relating to pneumatically actuated mechanism for controlling the feed of machine tools - Google Patents

Abstract

668,345. Machine tool details. HUGHES, Ltd., G. H., and CRAWSHAW, A. L. Sept. 15, 1950 [Oct. 7, 1949; Nov. 17, 1949], Nos. 25762/49 and 29392/49. Class 83 (iii). A pneumatically - actuated mechanism for controlling the feed of a machine tool comprises a pneumatic cylinder 3 and an associated spring-loaded valve 27 for determining the direction of traverse in the cylinder of a doubleacting piston connected to a rack 5 and pinion 7, whereby the feed is imparted to the tool, means 22 for maintaining the valve mechanism in one position against the spring action and means associated with the piston for releasing the valve after a variable predetermined stroke. The pistonrod 4 carries a member 9 fitted with an adjustable stop-nut 11. At the end of a feed-stroke the nut 11 'abuts a nut 13 adjustable on a tube 12. The tube 12 carries a bevelled collar 17 which releases the lever 22 and allows the valve 27 to be reversed by its spring. The feed-stroke is initiated by the movement of a rod 20 within the tube 12 by means of a projection 29 attached to a hand-lever. The movement can be reversed at any time by a plunger 34. The rate of feed can be adjusted by a hydraulic device comprising a piston 36 which allows free flow in one direction and which carries adjustable stops 38, 40 on its rod 36a. Adjustment of the. nut 38 determines the point at which the rate of feed is decreased and a valve 42 adjusts the subsequent feed-speed. The thrust on the tool is adjusted by a valve in the supply-line to the cylinder 3. A damping cylinder 43 is associated with the hydraulic device. In a modification, the reversal of the valve 27, Fig. 2, is effected by a solenoid 47 actuated by a micro-switch 48. A second micro-switch 51 provides for fully automatic control.