GB1343999A - Apparatus for automatically controlling a machine tool - Google Patents

Abstract

1343999 Programmed control of machine tools SIEMENS AG 13 Oct 1971 [28 Oct 1970] 47726/71 Heading G3N An apparatus for automatically controlling a machine tool comprises a device for producing an indication when the residual travel path of the tool is less than p times a preset travel step, where p is an integral number, the arrangement being such that, in response to said indication, the residual path of travel is sub-divided in p further travel steps which are equal or approximately equal. As shown, a limit switch 6 activates an interpolator to release for each travel step a pulse train to an electro-hydraulic stepping motor 7 driving the tool. The pulse train is also fed to count down a counter 2, which is preset to the total length of travel of the tool, and to a steplength counter 4. At the end of a step the residual count in counter 2 is set into a counter 3 and compared in a device 5 with the contents of the counter 4. When at the end of a step the state of the register 3 is less than a predetermined number p times the state of the counter 4, an order is given by the device 5 for the reduction of the step length. The transmission of the state of the counter 2 into the register 3 being blocked by opening a switch 8 for the next step. In the next step the interpolator 1 issues pulses until p times the constant residual value of the counter 3. This is repeated until the end of the machining operation. The remaining path is thus divided into p parts. The final step being a few per cent smaller than the other steps since the interpolator 1 is stopped when the value O is reached in the counter 2.