Research On Spatial Error Modeling, Compensation And Inversion Methods Of Horizontal Machining Center

As the "industrial machine" of modern manufacturing and processing industry,CNC machine tool is an important symbol to measure the national manufacturing industry.With the development of technology,the requirement of machine tool processing accuracy is getting higher and higher.At present,due to the large volumetric error(VE)of machine tools,the problem of inadequate parts processing accuracy seriously restricts the development of domestic CNC machine tools industry,and has become a major common problem to be solved urgently in the field of precision of digital manufacturing equipment in China.Therefore,it is of great theoretical significance and engineering value to study and establish a complete prediction model of VE,and to explore the strategy and implementation technology of machine tool VE compensation based on this model.VE is determined by machine tool geometric error elements(GEE),which directly affects machine tool VE prediction accuracy.At present,the research on the VE of machine tools mainly focuses on the forward analysis level,that is,establishing the VE model of machine tools,identifying the GEE related to the VE model,and compensating the VE.In order to reduce the VE of machine tools and improve the processing accuracy,there are relatively few discussions on the inverse inversion of the VE,and the accurate identification of crucial GEE of machine tools is the core work of the inverse inversion of VE.At the level of forward analysis of VE,most of the VE models have the problem of missing some geometric error elements,which directly affects the prediction accuracy of VE.In the process of error compensation,there are limitations of compensation residual in the current compensation technology,which directly affects the improvement of compensation effect.Previous studies have limitations on both aspects of volumetric error modeling completeness and its inversion accuracy and efficiency,resulting in lacking economics,reasonability and robust for machine tool precision design stage.Therefore,a horizontal machining center is selected as study object,aiming at the problems existing in current technology,the research of volumetric error compensation technology and crucial GEE is carried out.The main results are as follows:(1)Multi-body system theorem and homogeneous coordinate transformations are borrowed as analysis approaches.On the basis that initial positions and original errors eigen matrix are fully considered,VE model is guaranteed to have total machine tool GEE.(2)The mapping relationship between geometric error elements and measurement deviation is constructed,and the GEE are identified by measurement experiments.(3)Aiming at the residual error limitation in traditional NC code VE compensation technique,NC code coordinates optimization design problem is described to replace the former reversal accumulation process.Genetic algorithm(GA)is then utilized to solve the proposed optimization problem so that VE compensation residual error is eliminated.A horizontal machining center is selected as study object,on which both numerical and experimental analyses are performed to verify the proposed modeling methodology and compensation technique.(4)Next,based on the traditional sensitivities analyses,actual contribution degrees of GEE are defined and calculated,which is the fundamental basis to identify the crucial GEE of VE in each direction accurately and efficiently.(5)Based on the platform of MATLAB GUI,a software for VE compensation of CNC is developed.Engineers can generate NC compensation codes by setting relevant parameters and importing measurement data.Research results can be regarded as theorem and engineering supports for investigations on numerical manufacturing equipment precision problems.