Author(s)

J.M. Freeman. A.J. White & D.G. Ford

Abstract

Ball-screw thermal errors - a finite element simulation for on-line estimation J.M. Freeman, AJ. White & D.G. Ford Precision Engineering Research Group, The School of Engineering, University of Huddersfield, England Abstract Ball-screws are often used in machine tools with only a rotary encoder feedback on the end of the screw. Since this provides position feedback to the controller, any errors in the screw affect the accuracy of the machine. Also, these errors may change significantly when heating of the screw occurs during machining. This is often overcome by using a linear scale to provide the feedback. Unfortunately, fitting such scales to many machines may be mechanically difficult and costly. This paper describes the development of a system that utilises a minimum of temperature measurements as inputs to a thermal simulation model of the ball- screw. Thus it is possible to estimate on-line the thermal errors of the ball-screw, assuming that position measurements of the nut

Keywords