Research On The Accuracy Retention Analysis Technology Of Typical Meta-action Unit In Machining Center

Precision retention is not only the main content of the research on the key quality characteristics of CNC machine tools,but also the key to improve the comprehensive competitiveness of domestic machine tools.The poor accuracy retention of CNC machine tools has always been the deficiency of domestic machine tools,and it is one of the main bottlenecks that hinder domestic machine tools from joining the international advanced ranks.For this reason,the national major science and technology project of "High-end CNC Machine tools and basic Manufacturing equipment" and other science and technology programs have funded the research on the precision degradation mechanism and accuracy maintenance of key parts for several years in a row.However,at present,the analysis of accuracy maintenance of CNC machine tools is still focused on the degradation theory of a single part,which has not formed a set of systematic analysis system,and cannot be directly applied to enterprise production guidance.Based on this,with the support of the key projects of the National Natural Science Foundation of China,this paper studies the precision retention analysis technology of the machining center based on the meta-action theory,and the main contents include the following aspects.First,the related concepts of meta-action unit and structured decomposition technology are introduced.Then,the concepts related to Meta-action accuracy degradation are defined,and referring to the failure mode and effect analysis(FMEA)method,Meta-action accuracy degradation modes and effect analysis(ADMEA-MA)methods are proposed;then several common Meta-action accuracy degradation modes are defined,and The content and use flow of the meta-motion accuracy degradation mode and effect analysis(ADMEA-MA)are introduced in detail.Finally,taking the numerical control rotary table of the horizontal machining center as an example,the FMA structure is decomposed,and the precision degradation mode and influence analysis of the rotary motion of the rotary table are carried out.Second,on the basis of completing the accuracy degradation mode and effect analysis of the key meta-action unit,further study on the meta-action unit accuracy degradation model and wear degradation model.First of all,according to the Meta-action accuracy degradation mode,quantitative analysis of the Meta-action accuracy degradation is carried out,the precision degradation modeling of the typical Meta-action unit of the machining center is carried out.Then,focusing on wear degradation,the closed friction pair under the influence of abrasive particles is analyzed.Based on the mechanism of wear degradation,an accurate wear degradation model considering the influence of abrasive particles was established.Finally,the accuracy of the wear degradation model considering the influence of abrasive particles was verified by the wear test data of the ball screw pair.Third,according to the production demand of enterprises,a state space model forecasting method based on the combination of data-driven and physical methods is established.The model which accords with the changing law can be obtained according to the degradation law and historical operation data of mechanical equipment,and then the parameters reflecting the state of the equipment in the model can be updated in real time by using the particle filter method,so as to make the prediction model closer to the actual running state of the equipment,and then the accurate state prediction and residual life estimation can be obtained.Finally,the availability of the prediction model is verified by the vibration data of the spindle.