Error Identification Method And Simulation For CNC Turning Machine Tool Based On The Machined Workiece Surace Topography

The level of CNC machine tools is an important symbol of a country’s mechanization and modernization,representing a country’s scientific level,innovation ability and comprehensive ability.As the core basic equipments for manufacturing,CNC machine tools have received more and more attention.Supported by the National Basic Research Program of P.R.China"Research on Quality Manufacturing Technology for Key Mechanism with High Strength and Large Components"(973 Program,No.2011CB706505),and the National Science Foundation of China "Theory and Method for Tolerance Design Based on the Parallel Decomposition of Function-Structure"(51275464),this paper aims to bridge the gap between the machine tool error and the surface topography/texture generation.The developed error synthetic model for the CNC turning machine leads to the surface topography prediction.The multi-scale profile analysis of face turning surface topography can identify the vibration situation during cutting.And the methods for identification of the slide error motion are presented with the help of the surface height data.It helps better understanding for the surface topography and texture formation and provides an approach to identify the turning machine error.In chapter 1:The background and significance of the research are described.The development of error synthetic model and error identification for CNC machine tool as well as the modeling approach of turning surface topography are reviewed.And the research contents and general framework are presented.In chapter 2:The error sources of the CNC turning system are analyzed.Based on the multi-body system theory,the error synthetic model for the CNC turning machine is developed,which describes mathematically the relationship between the relative displacement error of the cutting tool with respect to the workpiece and the original error of the machine parts.In chapter 3:On the basic of machine tool kinematics and cutting theory,a prediction model for turning surface topography is proposed,with the consideration of error synthetic model of turning machine,machining parameters,tool geometry and other factors leading to relative displacement between machine tool and workpiece.In chapter 4:The influence of typical tool-workpiece relative vibration on surface topography is analyzed in detail.The machined surface contains a large number of surface features related to the process that the surface has undergone.A method for the identification of the tool-workpiece relative vibration is proposed based on the multi-scale profile analysis of face turning surface topography.Multi-scale decomposition of the machined surface is implemented by using bi-dimensional empirical mode decomposition(BEMD).Then the identification of relative vibration is carried out by the profile analysis of the BIMFs selected according to surface features in the radial and circumferential sections.In chapter 5:One-probe method with the help of the turned(self-cut)cylinder workpiece is presented for identification of the horizontal error motion(X-directional error motion)of the Z-slide.The displacement probe mounted on the opposite position of the cylinder workpiece with respect to the cutting tool is moved by the Z-slide to scan the workpiece at uniform angles along the Z-axis.The Z-slide error can be obtained by an averaged output of the probe over one rotation without the influence of the spindle error and the surface form error of the cylinder.The surface height of the face turning surface in the radial direction is measured,and the horizontal error motion(Z-directional error motion)of the X-slide can be identified by an averaged measurement data without the influence of the spindle error.In chapter 6:The software for error identification of the turning machine based on turned surface topography is developed by using MATLAB.In addition,the error motion of X-slide and Z-slide are measured by the methods proposed,which are proved to be effective by contrast with error compensation experiments.In chapter 7:The research contents and innovations of this paper are summarized and the further research works are prospected.