GB529800A - Improvements in and relating to hydraulic valves for controlling the hydraulic traverse of machine tools - Google Patents

Abstract

529,800. Hydraulic machines. TOWLER, J. M., and TOWLER, F. H. June 8, 1939, No. 16761. [Class 69 (ii)] A hydraulic valve for controlling the hydraulic traverse of machine tools of honing, grinding, shaping, or planing machines is constructed as a, sliding valve 1 Fig. 1, which is set so as alternately to connect the ends of the cylinder 3 to a pressure pipe 4 and outlet pipes 8, 9 in connection with a supply pump or other souce of hydraulic pressure, and the valve 1 is held alternately in its extreme positions by suction means. As shown in Fig. 1, the valve is fitted with cylindrical members 17, 18 adapted to be received in recesses 15, 16 formed at opposite ends of the bore in which the valve piston reciprocates, and flexible diaphragms 19, 20 close on the sides of the recesses 15, 16 which are immersed in liquid in chambers 21, 22 and owing to the displacement of the liquid in the recesses causing a vacuum the valve is held in position by the fluid pressure on the diaphragms. The valve rod 14 is fitted with tappets 12, which can be set at a predetermined distance apart to vary the stroke of the piston 7, and springs 13 are arranged in front of the tappets so that an abutment 10 on the piston rod 11 first compresses the spring 13 before the rod 14 is acted upon with sufficient pressure to break the vacuum and permit of movement of the rod 14. When movement does take place it has a fly-over action owing to the release of the energy stored in the spring 13. To permit of hand-actuation by a lever 26, the vacuum holding the rod 14 can be broken by opening a valve 25 which connects the recesses 15, 16, and thus equalizes the pressure in the recesses. This permits of inching the machine tool. In modifications the members 17, 18 may be arranged near together on one side of the valve as shown in Fig. 5, and the diaphragms may be dispensed with and the members fit closely in the recesses 15, 16. These recesses lead to passages 51 with non-return valves to permit of displacement of liquids so as to produce a vacuum. The vacuum is broken by an auxiliary valve 52 operated by an abutment 10. Two abutments 10 are employed and a common spring 13 serves two tappets 12. The hand-operated means for rendering the suction devices inoperative also may serve to break the current supply to the motor driving the hydraulic pump. In further modifications (a) the vacuum may be broken by a mechanical striker carried by the abutment 10 which forces the edges 19, 20 away from the recesses 15, 16 ; (b) the recesses 15, 16, Fig. 7 are formed so as to receive between them a member 57 formed with members 17, 18 with diaphragms 19, 20.