文档介绍：外文原文
IMPROVING ACCURACY C MACHINE
TOOLS PENSATION
FOR THERMAL ERRORS
Abstract: A method for improving accuracy C machine tools pensation for the thermal errors is studied. The thermal errors are obtained by 1-D ball array and characterized by an auto regressive model based on spindle rotation speed. By revising the workpiece NC machining program , the thermal errors can pensated before machining. The experiments on a vertical machining center show that the effectiveness pensation is good.
Key words : CNC machine tool Thermal pensation
0 INTRODUCTION
Improvement of machine tool accuracy is essential to quality cont rol in manufacturing processes. Thermally induced errors have been recognized as the largest cont ributor to overall machine uracy and are probably the most formidable obstacle to obtaining higher level of machine accuracy. Thermal errors of machine tools can be reduced by the st ructural improvement of the machine tool it self through design and manufacturing technology. However , there are many physical limitations to accuracy which can not be e solely by production and design techniques. So pensation technology is necessary. In the past several years , significant effort s have been devoted to the study. Because thermal errors vary with time during machining ,most previous works have concent rated on real-pensation. The typical approach is to measure the thermal errors and temperature of several representative point s on the machine tools simultaneously in many experiment s , then build an empirical model which correlates thermal errors to the temperature statues by multi-variant regression analysis or artificial machining , the errors are predicted on-line according to the pre-established model and corrected by C cont roller in real-time by giving additional signals to the feed-drive servo , very few practical cases of real-pensation have been reported to be applied mercial machine tools today. Some difficulties hinder i