| CNC machine tools have a significant impact on the country’s economic development in aerospace,medical,automotive and other industries.However,the design,manufacturing and assembly level of CNC machine tools in my country is still far behind that of developed countries,resulting in low accuracy of machine tools.Therefore,there is an urgent need to improve the accuracy of CNC machine tools.Five-axis linkage CNC machine tools have a wide range of uses,but they contain many error items.The error of the rotary axis has a greater impact on the accuracy of the machine tool.Geometric errors are one of the main error sources of CNC machine tools.Accuracy is of great significance.Therefore,this paper studies the geometric error of the rotary axis of the DMU 80 T five-axis machine tool.The main research contents and innovations are as follows:(1)The error modeling of the rotating axis of a five-axis CNC machine tool is studied.First,the conformal geometric algebra is used to define the geometric error of the two rotating axes of the DMU 80 T five-axis CNC machine tool independent of position.The geometric error of each rotating axis independent of position is defined as 2 displacement errors,1 rotation angle error,and 1 direction error;then based on the topological structure of the five-axis CNC machine tool,the positions of the tool tip point and the workpiece point in the reference coordinate system are respectively obtained,thereby obtaining the ideal kinematics model of the machine tool It is compared with the actual error model;finally,it is compared with the ideal kinematics model established by the homogeneous transformation matrix method to verify the validity of conformal geometric algebraic modeling.The establishment of the entire machine tool kinematics model does not require matrix operations.The conformal geometric algebraic operations are applied to machine tool kinematics modeling.The meaning is clear,the expression is simple,the calculation amount is simplified and the calculation efficiency is improved,and it has high practicability.(2)For the error identification of the rotation axis of a five-axis CNC machine tool,firstly carry out the double-rotation axis uniform speed linkage track double ball-bar experiment,establish an overdetermined equation set based on the double ball-bar data and the machine tool error model and apply Levenberg-Marquardt optimization The algorithm decouples the error;then the obtained result is substituted into the error model,and the fitting effect is verified by the residual error between the double ball-bar data and the fitted curve;finally the obtained error result is converted into the ISO 230-1 definition Compare the geometric error obtained by using the homogeneous transformation matrix to verify the accuracy of the result.(3)A compensation strategy based on the conformal geometric algebraic model to compensate the position and angle errors of CNC machine tools is proposed.First,the ideal and actual poses from the B-axis rotation center to the tool tip point and the C-axis rotation center to the workpiece point are respectively obtained.Ideal pose and actual pose;then according to the ideal pose and actual pose,the compensation amount in the three linear axis directions is obtained,and the angle between the poses is further solved to obtain the compensation amount of the two rotation axis angles;finally according to The movement amount in the direction of each linear axis and the rotation angle of the rotary axis realize the correction of the machine code. |
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