GB1380362A - Control means to control machining of workpieces on lathes or the like - Google Patents

Abstract

1380362 Automatic control of machining GILDERMEISTER AG 15 March 1972 [16 March 1971] 12152/72 HeadingG3N A program control system stores a desired final contour for a workpiece being machined. The load on the machine tool is measured and compared with a nominal value, the difference being used to control the relative longitudinal and transverse tool feed rates, while maintaining the magnitude of the feed vector at a predetermined value. In the system shown, the spindle 5 of a lathe has a chuck 17 holding a workpiece 6 for machining by a tool 7 controlled by a slide 8 with a longitudinal (Z) drive motor 15 and transverse (X) drive motor 16. Signals from a torque measuring device I and a rotational speed device 3 are fed to a multiplier 4 and their product is supplied to control circuits 10, 11 which compare the input product with a set value and use the result of the comparison to adjust the relative energization of the feed motors 15, 16 through a switching arrangement 14 which can reverse or exchange the control signals in accordance with the machining quadrant. The circuits 10, 11 have sinusoidal or linear characteristics in relative quadrature so that the feed vector is rotated according to the measured speed and torque values but its magnitude is substantially unaltered at a value set by an input circuit 12. The tool may be pivoted to maintain it in the most effective machining position relative to the feed direction. Geometrical correction factors may also be supplied by an input stage 13. In operation, the cutting cycle is repeated until a stored contour is achieved, comparison between actual and desired contour being made during the machining operation. An accelerated feedrate may be employed in areas where the final contour has been previously reached. Generally the system operates in a manner which maintains the chip thickness approximately constant.