Precision And Torsional Rigidity Analysis Of Double Meshing Tooth Needle Cam Indexing Mechanism

Double meshing tooth needle cam indexing mechanism is a new type of secondary transmission indexing cam mechanism. It has compact structure, which can achieve large indexing number, etc. So there is a broad range of application. To achieve the indexing performance more accurately, it is important to ensure the high position accuracy and motion accuracy. And the torsional rigidity of the mechanism has great influence on the natural frequency and vibration performance. Therefore, to analyze the torsional rigidity of the mechanism is of positive significance to improve the vibration performance of the institution.First of all, based on the organization structure and transmission principle of the mechanism, using the principle of action line increment method, we established the output error calculation model. Respectively, we discussed the calculation situation of the output error when a single tooth and much teeth engaged in gear. Used of the MATLAB software,we got the transmission error curve at the time of single error working alone. And discussed the influence of each parameter to the angle error of the mechanism, such as the distribution circle radius of needle teeth, points degree of the cam and so on, the results show that, the smaller distribution circle radius of the needle is more favorable to the output accuracy of the mechanism.Secondly, through integrated use of dynamic substructure method, concentrated mass method and equivalent model of the mechanism, we made the institutions dismembered and got the equivalent substitution of the institutions. The machining errors, assembly errors and elastic deformation are converted into equivalent errors, and then the transmission error dynamics analysis model was established. The forces of each component are obtained by solving the equivalent error. The motion differential equations of each component are listed according to the force and moment balance condition. The transmission error of the mechanism under the influence of all influence factors can be got by solving the motion differential equation. The quality of each component and the moment of inertia were calculated. In the end, introduced the method of solving the error equivalent model of transmission error which was established in the above.Finally, considering the effect of torsional stiffness on the dynamics performances of the mechanism, using the Herz formula, the meshing stiffness of the cycloidal needle wheel part and the needle teeth CAM part was calculated. At the same time, the effect of the input shaft's torsional stiffness and turning arm bearing's torsional stiffness on the torsional stiffness of the whole machine were considered. Based on the proposed transmission error dynamics analysis model,the equivalent torsional stiffness model was established based on the series of the equivalent spring and the parallel relationship. At the same time, the influence of each parameter (such as the distribution circle radius of the needle teeth, the motion law of follower)on the total mechanism's equivalent torsional stiffness was analyzed. The established equivalent torsional model provided a new method for calculating the whole torsional stiffness of CAM dividing mechanism. The results of the calculation can be used for further study of dynamic performance of double meshing tooth needle cam indexing mechanism.