Study On The Kinematic Modeling And Geometric Error Compensation Of Turning And Milling Composite NC Machine

The rapid development of modern processing has promoted the development of numerical control machine tools in the direction of high precision、high efficiency、high speed and compounding.The turning and milling composite NC machine has many advantages,and it has become a major direction of modern machining center.At the same time,with the increasing requirement for the surface quality of components,both domestic and foreign scholars have carried out a great deal of researches on how to improve the processing accuracy.Without increasing the manufacturing accuracy grade,the geometric error compensation can not only improve the precision of the existing machine tools but also has the advantages of low development cost and low difficulty Therefore,based on the kinematics model of the machine tool,studying and compensating the geometric errors have great significance to the development of industry.With the processing demand of the products,Anhui Hongqing Precision Machinery Co.Ltd.developed the TMS-200 s turning and milling composite NC machine,and carried out related key researches with CIMS Institute of Hefei University of Technology on this machine.This paper takes this machine as the research object,and couducts deep study on four aspects including kinematic modeling、geometric error analysis、calculating the compensation amount and designing the geometric error compensation software.The details are as follow:1.Analyzing the topological structure of the turning and milling composite NC machine,based on the multi-body system theory and homogeneous transformation matrix(HTM),the theoretical kinematics model under the milling mode and the turning mode are established according to the kinematic chain of the machine.In order to solve the multi-solution under milling mode,an angel judgment optimization algorithm is proposed to deal with the problem of angle mutation.The simulations on free-form surface and the multi-diameter shaft are conducted through the software VERICUT.The results prove the correctness of the kinematic model and the angle optimization algorithm;2.The position dependent geometric errors(PDGEs)and the position independent errors(PIGEs)are studied.The actual kinematic model after considering geometric errors between the work-piece and tool is established.The deviation of the position vector and the direction vector of the tool in the work-piece coordinate are calculated.The majority errors of this machine are indentified by sigle-step measurement based on the laser interferometer and the error prediction models of the position dependent errors are established;3.The geometric errors of axised are analyzed in the differential perspective and the compensation amount of each axis in the machine coordinate system is calculated by the differential method.According to the actual kinematic model,the deviation of position vector of tool before and after compensation iscompared.It is proved that the geometric error compensation is helpful to reduce the position vector.4.The geometric error compensation strategies are summarized.The geometric error compensation software is designed and developed based on the GUI module in Matlab,which simplifies the error compensation process.