A fast tool servo design for precision turning of shafts on conventional CNC lathes

A technique for precision turning of shafts on conventional CNC turning centers is presented. The shaft is semi-turned on a conventional CNC lathe. The precision finish turning operation is delivered by a piezoelectric based fast tool servo which is mounted on the same CNC lathe's turret. The precision tool tip motion is delivered by a proposed sliding mode controller which is robust to changes in the cutting process and hysteresis in the piezo actuator. Sliding mode controller is also quick to compensate the cutting force disturbances, and keeps the tool tip at the desired location within the displacement measurement sensor resolution (±0.1 μm). The fast tool servo system is packaged in a PC, and its effectiveness is demonstrated on a bearing location turning.

[1]  Eiji Shamoto,et al.  Ultaprecision Diamond Cutting of Hardened Steel by Applying Elliptical Vibration Cutting , 1999 .

[2]  Shane Y. Hong,et al.  Improvement of Chip Breaking in Machining Low Carbon Steel by Cryogenically Precooling the Workpiece , 1998 .

[3]  Tsu-Chin Tsao,et al.  Dynamic variable depth of cut machining using piezoelectric actuators , 1994 .

[4]  M. E. Preston,et al.  Piezoelectric ceramic actuators: A review of machinery applications , 1990 .

[5]  Yuichi Okazaki,et al.  A micro-positioning tool post using a piezoelectric actuator for diamond turning machines , 1990 .

[6]  Wen-Hong Zhu,et al.  Virtual decomposition based control for generalized high dimensional robotic systems with complicated structure , 1997, IEEE Trans. Robotics Autom..

[7]  Jean-Jacques E. Slotine,et al.  Adaptive sliding controller synthesis for non-linear systems , 1986 .

[8]  Eiji Shamoto,et al.  Study on Elliptical Vibration Cutting , 1994 .

[9]  Dong-Sik Kim,et al.  Waviness compensation of precision machining by piezo-electric micro cutting device , 1998 .

[10]  Naoya Ikawa,et al.  A New Micro-Cutting Device with High Stiffness and Resolution , 1990 .

[11]  Eiji Shamoto,et al.  DEVELOPMENT OF ULTRAPRECISION POSITIONER BY MEANS OF WALKING DRIVE , 1993 .

[12]  Petros G. Petropoulos.  The effect of feed rate and of tool nose radius on the roughness of oblique finish turned surfaces , 1973 .

[13]  U. Itkis,et al.  Control systems of variable structure , 1976 .