双啮合针齿凸轮分度机构的结构优化及有限元分析

发布时间：2018-11-06 17:31

【摘要】：双啮合针齿凸轮分度机构是一种新型的间歇机构,其输入轴、针齿轴和输出轴三轴共线,具有结构简单紧凑、可承受大载荷、能够完成较大分度以及传动平稳等优点,因此其应用前景将会相当广泛。本文是在现有样机的基础上,对其啮合效率进行理论分析后,然后利用遗传算法对机构的内部结构的体积和平均传动效率进行多目标优化,并对样机的关键部件内摆线轮和凸轮进行了疲劳仿真分析,同时又对机构进行了相关的动力学分析。首先,本文通过考虑摩擦力的影响,根据凸轮与内摆线轮的廓线方程,对机构的针齿与内摆线轮和凸轮之间的相对滑动速度进行了分析和求解,结合机构的实际传动情况对机构的整体传动效率进行了计算,求出了机构在一个分度期内的瞬时啮合效率,并对影响机构平均效率的主要参数进行了分析。其次,以样机内部结构的体积和机构的平均啮合效率为优化目标,根据机构的几何特性和传动原理,确定Rz1、Rz2、e、Bng、Btg、Bzg为设计变量,在满足强度等要求的基础上建立约束条件,建立机构的多目标优化模型,利用遗传算法对模型进行了求解。再次,根据材料的疲劳参数属性,利用有限元分析的方法对机构的内摆线轮和凸轮进行了疲劳寿命预测,并针对凸轮安全系数较小,没有达到设计寿命的问题给出了改进方案。最后,建立了等价动力学模型,对机构中的凸轮和内摆线轮在运动过程中的等效总等效扭转刚度变化曲线进行了求解和分析,给出了两者的瞬时固有频率变化范围,又利用Workbench对整机进行模态分析,研究其各模态下的振型,并预测了内摆线轮与凸轮与系统振动发生共振的可能性。
[Abstract]:Double meshing needle cam indexing mechanism is a new type of intermittent mechanism. Its input shaft, needle tooth shaft and output shaft are three axis collinear. It has the advantages of simple and compact structure, large load, large indexing and stable transmission, etc. Therefore, its application prospect will be quite extensive. In this paper, based on the existing prototype, the meshing efficiency of the mechanism is theoretically analyzed, and then the volume of the internal structure and the average transmission efficiency of the mechanism are optimized by genetic algorithm. The fatigue simulation of the inner cycloid wheel and cam, the key parts of the prototype, and the dynamic analysis of the mechanism are also carried out. Firstly, according to the profile equation of the cam and the inner cycloid wheel, the relative sliding velocity between the needle tooth and the inner cycloid wheel and the cam is analyzed and solved by considering the influence of friction. Combined with the actual transmission of the mechanism, the overall transmission efficiency of the mechanism is calculated, the instantaneous meshing efficiency of the mechanism in a indexing period is obtained, and the main parameters affecting the average efficiency of the mechanism are analyzed. Secondly, taking the volume of the internal structure of the prototype and the average meshing efficiency of the mechanism as the optimization objectives, according to the geometric characteristics of the mechanism and the transmission principle, the Rz1,Rz2,e,Bng,Btg,Bzg is determined as the design variable. On the basis of meeting the requirements of strength and so on, the constraint conditions are established, and the multi-objective optimization model of the mechanism is established. The genetic algorithm is used to solve the model. Thirdly, according to the fatigue properties of the material, the fatigue life of the inner cycloid wheel and cam of the mechanism is predicted by the finite element analysis method, and an improved scheme is given to solve the problem that the safety factor of the cam is small and the design life is not reached. Finally, the equivalent dynamic model is established, and the equivalent total equivalent torsional stiffness curve of the cam and the cycloid wheel in the mechanism is solved and analyzed, and the range of the instantaneous natural frequencies of the cam and the inner cycloid wheel is given. The modal analysis of the whole machine is carried out by using Workbench, and the vibration modes under each mode are studied, and the possibility of resonance between the inner cycloid wheel and the cam and the system vibration is predicted.
【学位授予单位】：天津科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH112.2

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