Patent GB-516397-A (GB)
Title: Improvements in or relating to hydraulic control apparatus
IPC: B23Q5/26
Filed: 1938-06-25
Abstract: 516,397. Hydraulic operation of machine tools. VICKERS, INC. June 25, 1938, No. 18904. Convention date, July 26, 1937. [Class 69 (ii)] A hydraulically operated machine tool having a system comprising a pressure source, a hydraulic motor provided with two ports used alternatively for pressure and exhaust, and a variable speed reciprocating member, is provided with a control panel comprising a housing provided with a longitudinal, valve recess, and interconnecting liquid passageways, a slidable control valve in said valve recess, means on said reciprocating port for actuating said control valve at various stages of the cycle of movement of said reciprocating member, and two throttle valves in said panel, the exhaust end of the motor being connected to the reservoir through one of the throttle valves in one position of the control valve, and the said exhaust end of the motor being connected to the reservoir through both of the throttle valves in series in another position of the said control valve. A machine tool part 12, Fig. 2, is reciprocated by a double-acting differential piston 10 working in a cylinder 8 connected by lines 30, 32 to a control panel 7; a constant delivery pump 5, driven by a motor 6, and provided with a relief valve 25, supplies pressure liquid through line 26 to the panel 7, the latter being disconnected by line 38 with the reservoir 9 from which the pump draws. The control panel 7, comprises, Fig. 1, a valve member 16, a valve 22 of the kind described in Specification . 399,609, and throttle valves 18, 19 adjustable by hand-wheels 20, 21 (Fig. 2). The valve 16 is movable at will by a handle 17 and is also moved automatically by adjustable tappets 13, 14, 15 on the machine part 12. The valve 16 is first moved by hand to the "rapid advance" position; liquid is then supplied to both sides of the piston 10, giving a rapid traverse. Tappet 14 then moves the valve 16 to the " First (or Coarse) Feed" position; liquid is supplied to the upper end of cylinder 8 through line 30, and exhausts from the lower end takes place through line 32 and through valve 22, throttle valve 18 and line 39. Tappet 13 subsequently moves the valve 16 to the "Second (or Fine) Feed" position; the exhaust from the lower end of the cylinder 8 is then through line 32 and through valve 22, both throttle valves 18, 19 and line 39; the valve 19 exerts greater throttling than valve 18, so that the former determines the rate. At the end of the advance stroke, the valve 16 is shifted by hand to the " Reverse position; pressure liquid is supplied to the lower end of the cylinder 8 through line 32, and exhausts freely from the upper end through line 30. At the end of the return stroke a tappet 15 moves the valve 16 to " Stop" position, in which the pump and both ends of cylinder 8 are put to exhaust. A tappet 50 may be provided, which at the end of the advance stroke closes a switch 51 to energize a solenoid 52 actuating the valve 16, to give automatic reversal at the end of said advance stroke. An electrical time lag device 53 may be included. Remote control switches 54, 55 for Reversal and Forward may be provided. If the machine part 12 reciprocates vertically, a counterweight 48 . may be provided. Alternatively a valve 49 may be placed in the line 32, permitting free inlet to the lower end of cylinder 8, but restricting exhaust therefrom. In a modification, a variable-delivery pump is employed, of the type in which a spring urges the delivery-varying member to its maximum output position, and the pressure on the delivery side acting against this spring to reduce the output; a modified control panel is then employed, such that for the rapid advance or traverse stroke, liquid is supplied only to the upper end of the cylinder 8, while liquid exhausts freely from the lower end thereof. Specification 399,609 is referred to.