Controller for CNC-operated machine tools

PCT No. PCT/US93/12344 Sec. 371 Date Aug. 11, 1995 Sec. 102(e) Date Aug. 11, 1995 PCT Filed Dec. 27, 1993 PCT Pub. No. WO94/14569 PCT Pub. Date Jul. 7, 1994A controller for optimization of metal-working on CNC-operated machine tools, includes a first unit for monitoring the torque of the main drive of the machine tool to establish the actual, instantaneous cutting torque, a second unit for setting the rated cutting torque in the teaching mode in dependence on the main-drive torque as monitored, a third unit for calculating the feed rate required to maintain the cutting torque at a constant level and controlling the feed drive, and a fourth unit responsive to the monitored main-drive torque and providing feed rate limiting signals to the third unit for protecting the tool against breakage. The unit for calculating the feed rate is addressed by a compensator unit responsive to signals from a comparator unit comparing the torque as set with the actual, instantaneous torque as indicated by the first unit and to signals from an identifier unit calculating the instantaneous cross- sectional area of the cut in response to signals from both the first, main-drive torque monitoring unit and the feed-rate calculating unit. A method for optimization of metal-working on CNC-operated machine tools is also described.