Research On The Motion Accuracy Of Linkage Mechanism In The Case Of Coupled Tolerances

Through several years' development,machinery industry development gradually to the high-precision and the high automation.Previous researchers on the precision of the motion error of the mechanism were mostly concentrated on the dimensional errors and the joint clearances.In fact,combined the process of manufacturing and processing,the motion precision of mechanism are usually affected by the multidimensional factors(concludes the various types of tolerances,the installation precision of the installation process,zero error before working and the environmental factors in the operation process,etc).So,some important factors in the manufacturing process were considered in this paper,a set of the quantitative optimal method for the motion precision of the mechanism was provided,and has important guiding significance for practical engineering applications.A large number of domestic and foreign literature were summarized,the dimensional tolerances,fit tolerances,installation precision,zero error,etc.in the manufacturing and installation process were analyzed,the error modeling method of the planar and the spatial linkage mechanism was got,and the optimal design method was provided.The main results are as follows:(1)The problems of the relationship between design and manufacturing were analyzed,the influence of dimensional tolerance and fit tolerance on the motion precision of the system was considered in the design phase,then based on the Monte Carlo simulation,the planar linkage mechanism optimal design model for manufacturing was set up.The method is furthermore applied in the optimization of the schemes with different fit tolerances,the prediction of motion errors in the design phase is achieved,a set of the quantitative evaluation system for mechanism optimal design is provided.(2)The relationship between the grade of tolerance and manufacturing cost was analyzed,the influence of design variables on the motion precision of the mechanism was analyzed,the lowest manufacturing cost at guarantee the motion precision premise was obtained.(3)Installation precision and the zero error of basic parts in the installation process was analyzed.The installation precision and zero error were considered into design variables to the optimal design.The range of motion precision of the whole mechanism was controlled after installation.(4)The analysis method of planar linkage mechanism was extended to spatial mechanism,and the influence of the motion accuracy with the non-parallel axes of the mechanism was analysis,through the optimal design,various types of tolerance were distributed reasonably,the end of the robot in different directions of motion accuracy control is achieved.Based on the above researches,a set of coupled tolerances optimal design method of linkage mechanism was proposed.