Coupled Thermal And Structural Analysis Of RV Reducer

The three core technologies of robot include reducer, control system, servo motor, RV reducer as a robot joint is more and more showing its powerful superiority. At present, the RV reducer Market is monopolized by foreign products, domestic products are still in the stage of product development and can not form a large volume, series of products. Domestic products mainly have short life and low rotation accuracy, through the thermal structure coupling analysis of RV reducer to find ways to improve the performance of RV reducer. In this paper, the theoretical analysis, finite element model establishment and thermal structure coupling analysis of RV reducer are introduced in detail. The main contents are as follows:1. According to the transmission principle and working mode of RV Reducer, based on the calculation of the transmission ratio of the planetary gear conversion mechanism method, The general theoretical calculation formula of the RV reducer’working frequency is derived. So a general, quick and effective calculation method is provided for the calculation of the rotation frequency of the transmission parts of the RV reducer.2. According to the principle of gear meshing and the principle of coordinate transformation, the equation of curtate cycloid and its tooth profile are summed up. The change rules of the curtate cycloid’s concavo convex characteristic, inflection point, undercutting point, curvature, radius of curvature and the pressure angle of cycloid wheel’s tooth profile are got with the analysis of Matlab. The increasement of short width coefficient part with the decreasement of short amplitude cycloid’s inner concave part, the undercutting point occurs in minimum of the radius of curvature’s absolute value of convex part, the decreasement of the maximum needle tooth’s radius which does not let the cycloid wheel to be undercut part with the increasement of short width coefficient, the pressure angle at each point of cycloid tooth profile is changing, the pressure angle at tooth’s top and the tooth’s root is large, the pressure angle at the inflection point is small. The results of research provide theoretical basis for the design and manufacture of the cycloid wheel.3. The function of the cycloid wheel’s parameters is more refined by the introduction of the concept of modulus in the involute gear. And the function of each parameter is classified, which is identified that the parameters which affect the transmission capacity are the modulus and the short amplitude coefficient and the parameters which affect the load-transmitting performance are short amplitude coefficient, needle tooth radius and transmission ratio. The distribution diagram of the cycloid tooth profile’s pressure angle is drawn by MATLAB. The variation law of minimum pressure angle that changes along with each parameter is obtained. The result is that the influence of short amplitude coefficient on the minimum pressure angle of the gear is the most, and the influence of the tooth radius is the less, and the minimum pressure angle of the transmission ratio is minimum. These laws make the design idea of the cycloid wheel more clearly, and it also provides a theoretical basis for the design of the series of products in the future.4. combined with the characteristics of the front gear profile and the characteristics of the gear wheel drive, the theoretical mechanics analysis of the RV reducer is carried out, and the method to improve the bearing capacity of the crank shaft is found. Increase the number of crank shaft can effectively reduce the crank bearing force, good cycloid gear pressure angle of the bearing force is relatively stable, enlarging crank shaft distribution radius can reduce the force on the bearing every moment; these analyses are benifit for next thermal-structure coupling analysis and the whole structure improvement and provide a theoretical basis.5. The temperature field and stress field of the RV reducer are obtained though Parametric modeling and thermal structural coupling analysis of RV reducer by using ANSYS APDL, and the stress situation of the gear and the stress of the bearing are analyzed. It is can be seen from the temperature field that crank bearing at the highest temperature. It is can be seen from stress field that the phenomenon of partial set of cycloidal gear meshing, crank bearing, needle roller bearing and bearing have deflected angle, for needle roller bearings, skew angle is the main reason that needle wear and squeeze split. The test bench is built to verify the temperature field of the RV reducer. The experiment results show that the temperature field is accurate.