Patent GB-646494-A (GB)
Title: Hydraulic copying milling or like machines
IPC: B23Q35/18
Filed: 1945-11-26
Abstract: 646,494. Copy-mining machines. TURCHAN, M., and WALKER, C. Nov. 26, 1945, No. 31859. [Class 83 (iii)] [Also in Group XXIX] A hydraulic copy-milling machine comprises a directional control valve B for either directing constant-pressure fluid to a cross-feed cylinder I and tracer-controlled fluid to a longitudinalfeed cylinder H or directing tracer-controlled fluid to the cross-feed cylinder and constantpressure fluid to the longitudinal-feed cylinder and also a throttle valve 58 within and operated by the tracer 16 for receiving the exhaust fluid from the cylinder under constant-pressure fluid control in order to control its rate of feed. General arrangement.-The work E consists of a plate in which an elliptical hole W, X, Y, Z is to be formed by a stationary rotatable cutter D and it is mounted on a table F movable in three mutually perpendicular directions by hydraulic cylinders G, H, I under control of a tracer 16 engaging a pattern (not shown) so that the work is moved against the cutter in a path corresponding to the elliptical outline of the pattern. The fluid actuating the horizontal feed cylinders H, I is directed by a manually-operated direction-control valve B so that when the work is. traversed along the longer axis of the ellipse in either direction tracer-controlled fluid is supplied to the cross-feed cylinder I and constant-pressure fluid, imparting a leading motion to the work-table, is supplied to the longitudinal-feed cylinder H whereas, when the shorter axis of the ellipse is traversed, tracer control is in the longitudinal-feed cylinder H and the leading motion is given by the cross-feed cylinder I. Hand control valves 86, 87, 88 are provided for regulating or cutting out the flow of fluid to each cylinder. Tracer valve.-The tracer head is adjustably mounted on a tracer arm by a dove-tail 15 and comprises a main valve 42 and throttle valve 58, actuated by a hollow tracer spindle 33 and controlling the horizontal feed cylinders and a third valve 18, actuated by a spindle 12 within the spindle 33 and controlling the vertical feed cylinder G. The spindle 12 has a tracer tip 11 adjustably secured to it and is supported by a ball-race 36 on a cone 34 adjustably-threaded within the hollow spindle 33 and locked by a set-screw 35 that spreads a lateral split in the cone. The spindle 12 engages the valve 18 through a ball 31 and a spring 63 is interposed between the valves 18 and 58. A spring 23 tending to force the whole valve assembly downwards is fitted round a valve stem 17 between the valve 18 and an adjusting nut 22 and a cam handle 26 bears on a disc 27 on the valve stem so that the valve 18 can be raised manually. The spindle 33 has an adaptor nut 49 and adaptor 48 screwed to it and is limited to lateral movement at right angles, to the tracer axis by a flanged sleeve 32 engaging ball-bearings 53 interposed between it and a housing 54. This lateral movement is translated into axial movement of the valve 42 by the engagement of a cone 50 on the sleeve 32 with a complementary conical surface 52 on the valve through a ball-race 51. Umbrella members 38 and 39 prevent oil seepage from running down the spindles and direct it to a gutter 40 whence it is withdrawn by a vacuum connection 41 to a hydraulic unit A. Direction-control valve.-The direction-control valve B has a rotatable shaft 81, Fig. 4, with annular recesses communicating with axial passages 82-85, Fig. 5, through which pipes 71, 72, 75, 76 from the horizontal feed-cylinders can be connected with ports 77-80 in the end of the valve body, these ports leading to the tracer and to a pressure supply pipe 65. By turning the valve through a series of quarter turns by a hand wheel, tracer-controlled and constant-pressure fluid are directed to provide feeds in the required directions as the tracer traverses round the pattern. Operation.-With the cutter D at point W on the work, tracer control is in the cross-feed cylinder I and constant-pressure fluid is supplied to the longitudinal-feed cylinder H to feed the table towards the cylinder. During the initial movement from the position W, the edge of the pattern tends to recede from the tracer but the springs 23, 63 force the valve downwards and pressure-fluid from conduit 66 goes through ports 46, 43 to port 78 on the valve B, which is set as shown in Fig. 5, so that fluid is conducted through passage 83 and pipe 75 to cylinder I to move the table towards the cylinder; the tracer adaptor 48 thus tends to maintain contact with the edge of the pattern. Fluid exhausted from the cylinder I through pipe 76 is returned through passage 82 and port 80 in the valve B, ports 44, 47 in the valve 42 and by a return pipe 60<SP>1</SP> to the hydraulic unit A. When the mid-point of the ellipse between W and X is reached, the pattern bears against the adaptor 48 and raises the valve 42 so that the pressure flow is through ports 46, 44 and return flow is through 43, 45, the cross-feed thus being automatically reversed. From W to X, the constant-pressure fluid connection to cylinder H is through 65, 79, 84, 71 and exhaust fluid returns through 72, 85, 77 to port 61 at the throttle valve 58. The annular opening 59 in the valve 58 overlaps the land between the port 61 and the port 60 leading to the return pipe 60<SP>1</SP> and as the tracer is deflected up or down the connection between ports 61, 60 is restricted or even cut off. Therefore, if there is a slight change in direction of the tracer control, the leading motion will be slowed down to the desired rate of feed and, if the change is abrupt, will be stopped, preventing damage to the cutter or work. When the point X is reached, the valve B is turned by a quarter turn in a clockwise direction and tracer control is changed to the longitudinal-feed cylinder H and constantpressure fluid is directed to the cross-feed cylinder I, which is then regulated by the throttle valve 58. When point Y is reached, the valve B is turned by a further quarter turn, restoring tracer control to the cross-feed cylinder I and constant-pressure fluid to the cylinder H, which then feeds the table away from the cylinder. At point Z, the valve is turned a further quarter turn, bringing the cutter round again to point W where the valve is turned back to its original position. The pattern employed may be recessed and the tracer tip 11 bearing on the bottom of the pattern controls the valve 18 which, in turn, controls the cylinder G to raise and lower the table F. By cutting out the cross-feed cylinder by means of the valve 87, longitudinal cuts can be made across the work, the tracer tip controlling the copying of the bottom of the pattern and reversal of the longitudinal stroke being made by turning the valve B through a half revolution. Specification 646,495 is referred to.