Geometric Error Classification And Modeling Techniques Of CNC Machine

With the rapid development of modern machinery manufacturing technology, precision and ultra-precision machining technology has become the main trend of modern machinery manufacturing industry. As the machinery manufacturing industry’s base tools, the accuracy of CNC machine tools is an important indicator of impacting the machining accuracy. In a variety of high-speed, precision machining bed, because the machine precision error caused the problem of declining increasingly prominent, how to quickly and efficiently build machine error model and the elimination of errors has become an increasingly urgent task. This thesis focuses on CNC machine tools’s error, research and analysis error classification, issue of establishing model and other related issues. The purpose is to provide accurate and effective error compensation data and the theoretical basis for research.In order to improve the machining accuracy. The main contents of this paper are:1. By gathering class and structure information of machine tools which commonly used now and according to different structure, classified machine tools.This paper also gives a three-dimensional structure diagram and determined the machine coordinate system. Because the machine error during the study, not to consider the nature of the machining, process scope, size, dimensions, etc., but the structure of the machine configuration:a few axis machine tools, motion axis is what and so on.2. By analyzing the three-axis and five-axis CNC machine tools’s main error source, this paper analysis the relationship between CNC machine tools’s elements of the error and error movement. By analyzing the moving shaft and the rotatable shaft’s sources of error, we found machine error elements of the sliding joint and the revolute joint. Because different error needs to be treated different, so first proposed a classification method according to the error whether can be compensated.Among them, error that can not be compensated need to give priority consideration in the pre-production process.The main error sources through analysis of CNC machine tools, CNC machine tools to collate the error, the error is divided into structural error (or non-compensation error) and motion errors (or compensation error) two categories.3. According to the needs of error compensation, based on the screw theory and a few degrees of freedom mechanical system common geometric error modeling methods, namely the integration of the modeling method, a geometric error sources and a detachable universal error model. It separable error sources can affect compensation and non-compensation posture errors.this modeling approach were used in the three-axis and five-axis machine tools, three-axis motion errors were established five-axis machine tools and comprehensive mathematical model.This paper made a deep study in the machine configuration, machine error analysis and error modeling, proposed a more complete theoretical system and practical techniques. The paper results can provide theoretical guidance and reference for the manufacturing and precise operation of the machine can help improve the precision CNC machining.