Research On The Mechanism Of Error Averaging Effect Of The Rolling Guide Pair In CNC Machine Tool

Geometric precision forward design is one of the leading technologies in the design and manufacture of high-end CNC machine tools.The error averaging mechanism and analysis method between motion pair and installation surface of rolling guide is a bottleneck problem.In the present research,the object study is a rolling guide pair of the high-precision horizontal machining center.Based on Hertz contact theory,a transfer function model and an error mapping model between the rolling guide pair and the linear motion pair are established.The error mechanism of the rolling guide pair is revealed quantitatively.With the aid of finite element simulation and advanced experimental method,the correctness of the theoretical method is verified.The following contributions have been made.Theoretical research on the mechanism of error averaging effect of the rolling guide pair.Based on Hertz contact theory,the contact state of the rolling guide pair is analyzed.Then bearing forces caused by the straightness errors of rolling guide are obtained via constructing geometric error model of single carriage.The relationship between them is described as a transfer function in the spatial frequency domain and its characteristics are analyzed.It clarifies so called error averaging effect of the rolling guide system quantitatively.On the basis of this,the force state of the four carriages is analyzed under the guide of straightness errors of rolling guide,and the static model of them is established.The model reflects the error averaging effect between the rolling guide rail pair and the position and orientation error of the moving pair.Finite element simulation of error averaging effect of the rolling guide pair.An equivalent static stiffness model of a single carriage is established based on spring damping unit method.On this foundation,a mapping model between the straightness errors of rolling guide pair and the pose errors of the moving part is constructed by finite element method.The results show that wavelength,phase,stiffness and span are the main affecting factors on the error averaging effect.The research achievements can guide the precision design between motion pair and rolling guide mounting surface,optimize the assembly process,and improve the accuracy of the tolerance distribution of the whole machine.An experimental platform is built to verify the error averaging effect of the rolling rail pair.The installation error,the raceway surface error,carriage motion error and pose error of moving part are tested.The experiment results show the transfer error of the various machine core components in the assembly process.Finally,the research effectiveness is proved.