Research On Modification Method Of Cycloidal Gear In High Precision Cycloidal Reducer

High-precision cycloidal reducer,also known as RV reducer(Rotary Vector reducer),is a relatively new type of precision reducer in recent years,which is widely used in high-precision transmission.The reducer is a two-stage reducer designed based on cycloid pinwheel transmission.The involute spur gear planetary transmission is first transmitted through the input shaft,and the motion of the first stage is transmitted to the second-stage cycloid pinwheel transmission through the crankshaft.It is precisely because of this special transmission mode that it has outstanding advantages such as large transmission ratio range,high load-carrying capacity,high transmission precision,and compact structure,and is widely used in high-end manufacturing fields represented by industrial robots.After practice tests,the cycloidal gear in the form of a standard cycloid is affected by some unavoidable factors such as machining errors,installation errors,and temperature changes during actual use,which will cause serious problems such as interference between the cycloidal gear and the pin wheel,jamming,high temperature,poor lubrication,etc.,so it needs to be modified.The machining error is an important factor affecting the actual cycloidal profile and the theoretical profile,so it is of positive scientific value to study the influence of machining errors on the tooth profile of cycloidal gears and modify the cycloidal gears from the perspective of machining errors.In this paper,the cycloid pinwheel transmission in RV transmission is taken as the research object,and the cycloidal gear is modified and optimized from the perspective of machining error compensation and load-carrying capacity.The influence of machining errors on the tooth profile of the cycloid is analyzed,and its randomness is fully considered.At the same time,the influence of cycloid gear tooth profile shape change on the load-carrying capacity of cycloidal gear is also considered.The transmission performance of the modified cycloid is analyzed,and the machining process of the cycloid is also simulated and analyzed.First,the sources of machining errors are studied according to the machining method of the cycloidal gear,and the machining errors are summarized into three types of errors: machining errors caused by the grinding wheel,machining errors caused by machine tools and machining errors caused by workpiece installation.According to the geometrical relation of machining error’s influence on cycloidal gear profile variation,the influence of each machining error on cycloidal gear’s tooth profile during machining is deduced.At the same time,according to the principle of small errors,each machining error is superimposed to obtain a comprehensive error,and the error compensation is performed.In addition,according to the sensitivity of each processing error to the cycloidal gear profile shape,the machining error item with the greatest influence is found.Secondly,the randomness of processing errors is fully considered.This paper adopts Monte Carlo simulation method,conducts a large number of samples through computer,and makes mathematical statistics on the sampling results.The integrated variation of the cycloidal gear profile is obtained finally and its normality is tested by the Kolmogorov-Smirnov test method.The cycloid tooth profile variation caused by machining errors is compensated,and the compensated cycloid tooth profile parameter equation is obtained.However,due to the combination of equidistant and radial-moving modification,the modified cycloid tooth profile cannot completely coincide with the compensated cycloid tooth profile.So,a mathematical model of machining error compensation cycloidal gear profile is established,that is,the average value of the deviation distance of m points is used to judge the degree of deviation between the two curves.At the same time,the change of the load-carrying capacity of the cycloidal gear caused by the modification is considered,and the load-carrying capacity model of the cycloidal gear is established.The multi-objective optimization algorithm is utilized to optimize the two models above,and finally the cycloidal gear modification parameters with comprehensive performance are obtained.Then,the transmission performance of the modified cycloidal gear is studied.The change of transmission hysteresis of the cycloidal gear caused by the modification is analyzed by means of geometric analysis,and it is judged whether the backlash meets the design requirements.The lubrication performance of the modified cycloidal gear is analyzed by numerical calculation method,and the lubrication state is judged by film thickness ratio.Through the virtual prototype technology of the RV reducer,the model of the complete reducer is analyzed by the method of finite element analysis.In addition,the load-carrying capacity of the modified cycloidal gear is also analyzed.Finally,the machining process of the cycloidal gear is highly simulated through the simulation machining platform.The three-dimensional models of gear grinding machine tools,grinding wheel cutters,blanks and other components in the actual cycloidal gear processing process are established.In the process of simulation pre-processing,the machining error in the actual machining process is taken into account,which realizes a high degree of simulation of the machining process of the cycloidal gear.After the processing is completed,the machining quality is analyzed.