A study on the tuning of CNC parameters to improve contour precision for NC Machine Tools

This paper deals with a practical servo tuning method for high speed and high acceleration feed drives in the latest NC machine tools. CNC-servo systems in machine tool drives generally have current-velocity-position feedback controls, a feedforward controller and a command generator. Techonological progress in hardware and software makes it possible to implement a high response servo control for commercial feed drives. When feed drives are built in a complicated structure, however, vibration problems tend to occur in practical applications. Particularly vibrations at low frequencies deteriorate the contoing accuracy. In order to search the most adequate combination of CNC-servo parameters, a quick and accurate tuning method is required. This paper proposes a systematic tuning method based on simulation and measurement technology. The effectiveness of the proposed tuning method is validated by a case study involving a commercial machining center.