Simulation Research On Machining System Of Multi Axis NC Machine Tool

The machining accuracy of NC machine tools is mainly restricted by three aspects: the thermal error caused by thermal deformation of machine tool structural parts,geometric errors caused by machine tool installation and wear and stiffness error due to cutting force in machining.This paper analyzes and researches on improving the accuracy of machine tool system.In order to provide reliable data support for the design precision of CNC machine tool.The research object of this dissertation is the five axis NC machine tool with two axis of rotation whose primary axis is B-axis and C-axis.The transformation relation between moving parts is established based on the multi-body theory and the theory of homogeneous coordinate transformation.Then the geometric error model of the NC machine tool system is established.Based on the analysis of the geometric error measurement of CNC machine tools and modern computer simulation technology,a new simulation method of measuring the geometric errors of CNC machine tools based on SimMechanics is presented.The geometric errors of the moving axes and the rotating axes are simulated and then the feasibility of the new method is analyzed.The main research work is as follows:(1)Based on the analysis of the main error sources and error classification of five axis NC machine tools This dissertation expounds the importance of geometric error to the accuracy of machine tools.The geometric error elements of the moving axes and the rotating axes are analyzed.(2)Based on the multi-body system theory and taking the five axis NC machine tool with double rotating axes as the research object.The topological structure of NC machine tools is described by using low order array.The homogeneous matrix is used to represent the geometric relationship between the parts of the CNC machine tool.The kinematics model of NC machine tool is established.On this basis,the geometric error model of five axis NC machine tool is established.(3)The theoretical basis for the testing method of ball bar is analysed.According to the detection principle of the ball bar,this paper presents a method for detecting the geometric errors of CNC machine tools by computer simulation.(4)The system simulation model of five axis NC machine tool is established by Solidworks&SimMechanics.The ideal model and geometric error model of five axis NC machine tool are simulated respectively.The simulation results are compared to verify the feasibility of the new method.