Research On Profile Error Systematic Analysis And Prediction Of Globoidal Cam Based On The Multi-body System

Globoidal cam mechanism has been extensively applied in many automatic machines for its ability of achieving many complex moving forms. As the key parts, the machining precision and surface quality of globoidal cam directly determine the working performance and quality of this mechanism. At present, the NC machining is the main processing method for globoidal cam at home and abroad. Compared with abroad, there is still a large gap in the R&D capabilities about precise globoidal cam. The main causes are that the structure of globoidal cam working profiles are complex and difficult to machining, especially the NC programs are only based on the simple geometry tool path strategy and without considering the synthetic influence of other original errors, such as machine tool error, clamping error, tool error, etc. The profile machining error of globoidal cam is unable to realize scientific prediction and available control. How to reveal the synthetic influence of original errors on globoidal cam machining precision, realize efficient-scientific prediction and available control to profile machining error of globoidal cam have become a key task in the R&D about precision globoidal cam mechanisms. Thus, it is urgent necessary to do some researches on systematic analysis and prediction for globoidal cam profile error to provide scientific basis for tool path optimization and error effective-control. Therefore, the profile error synthetic model of globoidal cam has been built in this paper with the help of multi-body error-modeling theory, meshing theory of spatial mechanisms and Matlab tool, etc.. And the influence law of each original error on profile machining precision of globoidal cam has been deeply analyzed. The main works in this thesis can be concluded as the following:1) This paper provides an overview for the machining error analysis about the globoidal cam, the application of multi-body system to machining error analysis and the geometric error modeling of NC machine tool. Then, the theoretical profile equation is deduced and the basis is established for the subsequent study.2) The machine tool spatial geometric error factors are analyzed. Aimming at the DMU80T (a five-axis vertical boring-milling machining center), the spatial geometric error model of this machining center is built after the structure and kinematic-geometric errors being analyzed.3) The profile error synthetic model of globoidal cam is built. According to the generation method and one-side machining method, and combination with the structure and configure of the machine tool , the error profile equations of globoidal cam including machine tools'kinematic errors are deduced for the generation method and one-side machining method respectively based on the multi-body error-modeling theory and spatial meshing theory of globoidal cam mechanisms. Simultaneously, the normal error definition, calculation method and calculation process of globoidal cam are given.4) The analysis of example simulation is done. Based on the above research works, the profile error synthetic analysis program of multi-axis NC machining for globoidal cam is compiled by using Matlab tool. The calculation results of example simulation reflect the synthetic influence law of each original error on globoidal cam profile machining error.In conclusion, the researches in this paper provide a theoretical basis for the efficient-scientific prediction of the profile error of globoidal cam, and establish basis for the machining tool path optimization and high efficient & precision machining globoidal cam based on error compensation.