A Kinematic Geometry Model For Measuring And Evaluating Accuracy Of Machine Tool Guide Rail

In this paper,the kinematic geometry model of machine tool linear guide measurement has been studied.Based on the degradation model of non complete measurement,single sensor and double sensor evaluation has been carried out in single guide single slider and double slider assembly mode,and the research of two axis linkage workbench error compensation method based on complete measurement model combined with machine tool interpolation mode has been carried out in this paper.The main research methods and contents are as follows(1)The principle of kinematic geometry for linear guideway measurement of machine tool is proposed.According to the motion chain relationship that must be satisfied among the measured motion parameters,geometric elements to be measured and sensor measurement parameters,the kinematic geometry model of linear guideway measurement(closed-loop vector basic equation)is established.The solution mode of the equation is divided into error motion measurement,error motion measurement and error motion measurement Sensor calibration,geometry and installation error measurement are three categories,and the completeness measurement conditions of motion parameters of linear guide error of machine tool are determined: the closed-loop vector basic equation composed of sensor measurement parameters and measured geometric elements is projected in the measurement coordinate system,and the number of independent scalar equations is equal to the number of independent variables,and the independent variables are six degree of freedom motion parameters.(2)The degenerative form of the kinematic geometry model of linear guideway measurement motion has been studied,and the general applicability of the kinematic geometry model in the measurement of linear error motion has been discussed.The test of straightness measurement of guideway supported by single and double sliders by single and double sensors has been designed.Under the measurement of double sensors,the straightness of guideway supported by single slider depicts the shape of guideway,and the straightness of guideway supported by double sliders reveals the track of straightedge.Both of them belong to space error motion and degenerate to plane error motion trajectory,which can provide theoretical basis for improving linear motion accuracy of worktable;Based on the model degradation form,the difference of motion geometry meaning between single sensor measurement parameters and guideway straightness index is analyzed.Corresponding to the measurement requirements of Bryan principle,the kinematic geometry connotation of Abbe principle and Bryan principle is extended.A comparative test was designed to measure the error motion parameters of the four-slider moving pair with double guideway and single guideway.There were differences in the error motion parameters between the moving pair after assembly and the guideway before assembly.The measured kinematic geometry model could be the basis for further research on the elastic error model(3)A straightness evaluation model with adaptability,uniqueness and comparability is proposed.Based on the degenerated kinematic geometry model of double table measurement,the ideal reference line with adaptability and uniqueness is obtained by adaptive fitting with the maximum value of the normal error of the straight line as the objective,and the normal error index of the straight line is clear,unified and comparable;Furthermore,the minimum point solution model of rigid body straightness error is proposed,so that the evaluation does not depend on the position of coordinate system.(4)Based on the complete measurement of the two axis error,the discrete Fourier transform has been introduced to fit the discrete data into the error continuous curve while retaining the frequency characteristics and fluctuation characteristics of the data.An error compensation method for the two axis machine tool has provided by the inverse solution of the model.On the basis of the error motion solving model,the spatial motion differential geometry theory has been introduced,and the vector expression of the instantaneous spiral axis of the two-axis linkage table has been deduced,which introduced a new idea for the error motion analysis of the machine tool moving pair.