Patent GB-932905-A (GB)
Title: Automatic control arrangements for copying and other lathes
Inventor: HADEKEL RUBEN
IPC: B23Q15/10
Filed: 1958-09-12
Abstract: 932,905. Copying lathes. SPERRY GYROSCOPE CO. Ltd. Aug. 21, 1959 [Sept. 12, 1958 (4)], Nos. 29351/58, 29352/58, 29354/58 and 29355/58. Class 83 (3). Machine tools in which a workpiece-supporting member and a cutting tool supporting member are relatively rotatable about an axis and relatively displaceable towards and away from the axis are provided with automatic control means to control the relative speed of rotation as the radial distance changes so as to maintain a constant rate of cut corresponding to a set rate, said control means being arranged to respond to changes in the radial distance and in the output of a device driven to provide an output that varies in accordance with the relative rotational speed. The lathe has a headstock 11 driven by a variable-stroke hydraulic motor 12, a saddle 13 which carries a copy-slide 14, and a facing-slide 15. The saddle is traversed by a lead-screw 16 driven by an hydraulic motor 17. The copy-slide is inclined at 60 degrees to the work-axis and is moved by an hydraulic piston and cylinder 18 controlled by a stylus 71 and a template fixed to the lathe bed (not shown). The facing slide is moved transversely by an hydraulic piston and cylinder 19. The hydraulic motor 12 which drives the headstock 11 is supplied with fluid from a pump 21 driven by an electric motor 22, the fluid being controlled by a valve 23 which is either solenoid or manually operated. All other components are supplied with fluid from a second pump 24 driven by an electric motor 25. The speed of the headstock motor 12 can be controlled by means of a stroke control unit 26 controlled from a servo-valve 27 in accordance with the output of an amplifier 28. The speeds of the lead-screw, the copying- slide cylinder &c. 18 and the facing-slide cylinder 19 can be controlled by respective servovalves 29, 32, 34, which are operated in accordance with the output of respective amplifiers 31, 33 and 35. The saddle is arranged to be fed proportionally to the headstock speed under the control of a velocity servo system (see Specification 932,906). The speed of the leadscrew 16 is kept proportional to a set feed per revolution and to the headstock speed. Copying. Compensation for cutting shoulders and steep slopes is effected during copying by a servomotor system (see Specification 932,906), which varies the speed of the saddle feed motor in dependence on the copying slide feed, thus the lead-screw speed is then kept proportional to the headstock speed and the rate of feed of the copying slide. Facing. The facing slide is also fed at a preset rate proportional to the headstock speed by electrical means. Constant cutting speed. In order to maintain a constant cutting speed as the tools move towards and away from the axis of the work, control means (see Specification 932,906) are provided to adjust the speed of the headstock motor 12 in accordance with the distance from the axis of whichever of the two tools, facing or copying, is in operation. Automatic and gauging stop means are provided for stopping the longitudinal and transverse movements of the tools and for returning the slides to their starting positions. The gauging or dead stops cause a build-up of pressure in the slideoperating cylinder which is used to operate electrical means for reversing.