High-Precision Machining by Measuring and Compensating the Error Motion of Spindle's Axis of Rotation in Radial Direction

摘要

This paper deals with cutting force monitoring forhigh precision machining. The authors have employeddisplacement sensors to monitor the cutting forces, as they arecheap and small enough to be built in the spindle structure. Amonitoring method, which utilizes sensitive displacementsensors, is discussed. The sensors are installed in X Ydirections near the front bearings of the spindle, to detect thesmall displacements of a spindle caused by cutting forces.Monitoring tests are carried out under end milling operationsand the cutting forces are estimated from the displacementsignals by the simple signal processing technique. However, asthe displacement sensor measures the variation of the gap sizebetween the sensor head and the target surface, it also recordsdisplacements due to error motion of a spindle's axis ofrotation in radial direction and roundness errors of the targetsurface. By comparing the cutting force estimated fromdisplacement sensors with the cutting force measured by usinga dynamometer, the machine tool spindle error motions isinvestigated, and its compensation scheme is proposed. The testresults show that the monitoring system is reliable for theadaptive control of machining accuracy for end millingprocess.