Prediction of Heat Generation and Temperature Distribution in High Speed Preloaded Ball Screws

Abstract

The general trend in the field of machine tools is to increase the speed of feed axes with the aim of reducing manufacturing times, high speed machining is a significant example of such increase. Ball screws have proven their ability to fulfill requirements of workpiece positioning accuracy, nevertheless, the heat generated in the screw-nut interaction increases proportionally with the speed of the axes. As a result, an increase in temperature takes place, which causes thermal expansion of the ball screw, producing positioning errors and decreasing the service life of the ball screws, therefore it is important to have effective methods for predict the temperature.The main objective of the present work is to predict the heat generated in the screw-nut contact based on analytical models in order to estimate the temperature distribution in the nut. For this purpose a heat transfer FE model of a preloaded high speed ball screw nut has been developed. Additionally, experimental heating tests have been performed to validate the FE numerical model. In this way, the temperature predictions obtained at different working conditions have less than 6% of deviation comparing with the experimental results.