The Research Of The Assembly Precision Of Cnc Machine Tools Considering The Joint Surface Characteristics

CNC machine tools are mainly used for the processing of precision and tiny machine parts, so the accuracy of the CNC machine tools are required higher. Besides the factor of the machine parts’ precision, the most important part is the deviation of CNC machine tools in the assembly process. If the analysis and calculation of the deviation in the assembly process could be worked out in the design stage, reasonable and perfect assembly sequence would be found, so that the accuracy of CNC machine tools improves greatly.In order to achieve the goal, this paper studied the deviation source of machine tools in the process of assembly, what’s more, divided it into three categories. Then, to calculate the first type of deviation source which is caused by its shape and position deviation, and the second type of deviation source with the gap deviation in the actual assembly, we can make use of an already existing calculation method. To calculate the three type of deviation source which is caused by combination surface, the finite element analysis and response surface model are used. Then, based on the transfer matrix, a method is used to solve the problem of transmission deviation. Finally we could get the final assembling deviation caused by the three types of deviation sources. According to the degree of dimensional variation theory, the quality of the system on the assembly sequence and assembly accuracy can be evaluated.Especially, in the assembly process of CNC machine tools, combining surface would produce an extra deformation which is caused by the additional gravity. Considering this extra deformation, deformation transfer matrix needs to refresh, in this way, assembly accuracy can be predicted more accurately.At last, an assembly case of CNC machine tool is solved to prove the above methods is tenable.