Research On The Accuracy Reliability Model Of Heavy Nc Machine Tool

After decades of development, through continuous incorporation of foreign advanced technology and independent innovation, deomestic heavy-duty CNC machine tools has made great progress in the high speed, precision and combined machining. However, there exists a large gap between domestic machine tools and international advanced machine tools regarding reliability and accuracy. Frequent occurrence of early failures, multiple types of failure modes and tremendous difficulty of failure identification are significant issues that the limit the development of domestic heavy-duty CNC machine tools. Based on the status of the low level reliability and precision of domestic heavy duty machine tools, it is necessary to make further research on their reliability and accuracy, to provide key technologies for reliability and precision improvement of domestic heavy duty machine tools. Based on the above background, this paper presents a coherent research of synthesis error modeling and precision reliability modeling. The paper main contents are as follows:(1) A brief review of reliability of machine tools is presented firstly, and the research difficulties and key generic skills needed to solve are summarized as well.The error modeling of machine tool ration to reliability problems is also presented.(2) The multi-body kinematics error modeling theory is studied, including the describing of homogeneous coordinate transformation theory and process of multi-body systems kinematics error modeling in detail.(3) The synthesis error modeling is implemented on a heavy duty CNC floor-type milling and boring machine based on the multi-body kinematics error modeling theory. It includes the establishment of topological structure and the lower body array, and the characteristic matrix of TK6916 B. Based on this modeling, the synthesis error modeling of TK6916 B is constructed.(4) By adopting the method of the mixed programme, a quick error modeling software package is developed with the mixed programme of C#-MATLAB. This software package can establish the error model through inputting the coordinate and parameters, and the value of the synthesis can also be calculated.(5) The motion error modeling process of mechanisms is studied. Based on the stress-strength interference model, the precision reliability model of mechanism is established. Then, based on this method the precision reliability model of the TK6916 B is obtained and analyzed.