Patent GB-525558-A (GB)
Title: Improvements in or relating to radial drilling machines
IPC: B23Q1/30
Filed: 1939-01-26
Abstract: 525,558. Drilling-machines. VICKERS, Inc. Jan. 26, 1939, No. 2668. Convention date, Jan. 26, 1938. [Class 83 (iii)] [Also in Groups XXIV and XXIX] In a radial drilling machine having a head movable along an arn vertically slidable on a rotatable sleeve and having a pump supply ing fluid to motors for clamping the arm, mov ing the arm vertically and clamping the sleeve all the motors being controlled by individua valves actuated by hand, an additional valve is provided for byepassing the output of the pump when none of the valves is supplying fluid to its motor. The machine comprises a base 10 carrying a pillar 12 on which is rotatable a sleeve 14, the arm 16 on which the drill head 18 is radially slidable being movable vertically on the sleeve. The head 18 is provided with a spindle driving motor' and another motor 54 on the arm drives a pump 56, Fig. 5, for supplying the hydraulic circuits. The sleeve is split at its lower end and is clamped to the pillar by an adjustable bolt 34 actuated by an eccentric on a spindle 30 which has splined thereon a pinion rotatable by a rack on a hydraulic plunger reciprocable in a cylinder 42 on the arm. The arm is split at 44 and is clamped to the sleeve by levers 46 having a toggle action so that they will remain clamped after they have been actuated by a hydraulic cylinder 50. The head 18 is traversed along the arm by a screw 64 rotated through gearing from a hydraulic motor 58, and a second motor 60, Figs. 2 and 5, rotates the elevating nut engaging a screw 72 secured to the sleeve 14. The nut consists of two parts 68, 76, both driven from the motor, the first engaging-the arm 16 through a thrust bearing 70 to elevate it and the second being pressed upwards by a spring 78 engaging the lower surface of the arm. Thus as wear of the threads occurs the nut 76 is raised relatively to the nut 68 and oscillates a lever 84 connected to a plunger 82, Fig. 5, which is thereby moved to admit pressure from an external source 266 to a valve 272. As this valve is raised against its spring, the supply from the pump 56, proceeding by pipes 100, 126, is byepassed to the exhaust line 276, 110, and consequently the elevating motor 60 cannot be started. The control panel 86 has two valves 106, 108 linked together by a member 158 and actuated by a hand lever 90 to control the armelevating motor 60. Another valve 194 is actuated by a hand lever 88 to control the head-traversing motor 58 and a further valve 168 is actuated by a hand lever 92 to control the sleeve-clamping cylinder 42. The pump 56 supplies valves 106, 108 through pipes 100, 126, and 140, and'valves 168, 194 through pipes 164, 190, the valves 106, 108 and 194 each having two operative positions and being biassed to the neutral position shown by springs 160 whilst the valve 168 can remain in either of its operative positions. In the position shown, oil from the pump 56 passes freely to exhaust through pipes 164, 242 valve 240 and exhaust cunduit 244, the valve 240 being held open due to the upper chamber 236 thereof being open to exhaust through pipes 234, 226, ports 156, 154, pipe 220, ports 216, 218, pipe 182, port 178, pipe 250, valve 254, pipe 258, valve 260 and pipe 264, since all the valves are in series. A high pressure relief valve 246 connects the chamber 236 of valve 240 to exhaust by means of a pipe 248, but is replaced by a low pressure relief valve 230 when the ports 222, 224 allow communication between pipes 228, 234 due to movement up or down of the valve 194. In order to elevate the arm 16, lever 90 is actuated to lift valves 106, 108, thus cutting off the byepass through valve 240 by closing port 156 and allowing oil from the pump to flow by pipes 100, 104, 126 to the right hand end of cylinder 50 to release the arm clamps 46. A byepass valve 136 remains closed since the resistance to movement of the clamps is insufficient to open it, but when the piston in cylinder 50 stalls, the valve is opened to allow oil to flow from pipe 126 to pipe 140, ports 142, 146, and pipe 152 to the elevating motor 60. When the arm has been raised sufficiently the lever 90 is released and the valves 106, 108 return to neutral position, oil flowing from the pump by ports 102, 130 to pipe 134 to reverse cylinder 50 and re-clamp the arm. A valve 260 is connected by a lever 262 to the clamping piston 50 so that the connection between pipes 258, 264 will be severed whilst the clamps are released, thus preventing the byepass valve 240 from reducing the oil pressure until the clamps have been reengaged. To lower the arm the valves 106, 108 are lowered by the lever 90 and after the valve 136 opens, the flow to the motor 60 is reversed to rotate the nuts 68, 76 in the opposite direction. For traversing the head 18 outwardly on the arm the lever 88 is actuated to raise the valve 194 thus shutting the byepass valve 240 by means of the port 218 and allowing oil from the pump to flow by pipe 164, port 166, adjustable reducing valve 188, pipe 190, ports 198, 196 and pipe 213 to the motor 58 for rotating the screw 64, motion in the opposite direction being produced by lowering of the valve 194. 'The valve 194 also connects ports 222, 224 so that the chamber 236 of the byepass valve 240 is connected to a low-pressure relief valve 230 by pipes 228, 234 thus ensuring, together with the reducing valve 188, a lower operating pressure for the motor 58 than for the motor 60. To unclamp the sleeve 14, the lever 92 is actuated to move the valve 168 downwards, admitting oil from the pump by pipe 164, ports 166, 169 and pipe 184 to cylinder 42 and rotating the shaft 30 to release the clamp. The plunger 42 is connected by a lever 256 to a valve 254 so that as soon as the plunger has completed its stroke the valve will be thrown over to connect the pipe 182 to exhaust through port 180, pipe 252, valve 254, pipe 258, valve 260 and pipe 264, thus opening the valve 240 and byepassing the pump output although the valve 168 is left in its displaced position. To clamp the sleeve, the valve 168 is raised by lever 92 beyond the neutral position shown in Fig. 5. The speed of operation of the motors 58, 60 and plungers 42, 50 may also be governed by the degree of opening of the valves 106, 108, 194, 168. The byepass valve 240 is of the kind described in Specification 393,761, and the oil sump 94 may be provided in a hollow part of the arm 16.