Research Of Assembly Quality Evaluation And Control Technology Based On Meta-action Of CNC Machine Tool

CNC machine tools is a set of machine, electricity, liquid, control all kinds of subjects and fields of complex high-tech products and the important manufacturers of other equipment in equipment manufacturing industry. The requirements of users on the reliability, precision, and precision life(RPPL) of CNC machine tools is very high. The assembly impact on the quality of the products is comprehensive, product performance is decided by the assembly process for the most part. Currently for CNC machine tools, only consider the accuracy in assembly process has been unable to meet the requirements and need to set up RPPL integration control solutions.Based on the support of National Natural Science Foundation and National major sciencific and technology special project, making the domestic machining center for the study, the integrated control of CNC machine tools assembly process was studied. The main contents are as follows:(1)CNC machine tool is decomposed into many meta-action by PFMA(Pedigree-Functions-Movement-Action). Based on the most basic meta-action obtained by PFMA, the meta-action assembly unit is defined to be the basis unit for assembly quality research to simplify the follow-up research. At last,take the spindle motor function components of one CNC machining tools as an example to complet the structural decomposition.(2)Based on the concept of entropy, the “unit quality entropy” is proposed to construct the quality evaluation model of meta-action assembly unit. Then from the six aspects of human, machine, material, method, enviroment and measurement, the reason of assembly quality loss is analyzed. Based on the assembly quality loss analysis and assembly quality evaluation model of meta-action assembly unit, the evaluation technology for meta-action assembly unit about RPPL is discussed to obtain the synthesis assessment index. Finally, the effectiveness of the method is verified by the analysis of the spindle rotating meta-action assembly unit.(3)Make the synthesis assessment index of meta-action assembly unit the as the basis of the data, combining with fuzzy clustering method to extract the main control direction(one or more indicators of RPPL) of meta-action assembly unit, simplify the control requirements that each unit needs to be controlled. Then, based on the generalized information entropy, an evaluation model is established to for the simplifide unit assembly process. After that, combining the results of the evaluation by the model and fuzzy clustering method to extracte the control direction(one of RPPL) of each process. Then, put control method for the assembly process based on integrated control. Last, taking the spindle motor function as an example, the effectiveness of the method is verified in detail.