Lost Motion Analysis And Tolerance Design Of Precision Planetary Reducer

With the continuous development of modern mechanical equipment in the direction of high speed,precision and heavy load,the requirements for the transmission device are higher and higher.Precision planetary reducer is an important part of mechanical transmission device.Because of its high transmission precision,large transmission ratio and strong bearing capacity,it is widely used in all kinds of high-end equipment.Lost motion is an important index to evaluate the transmission accuracy of precision planetary reducer.Its size directly affects the repeated positioning accuracy of mechanical equipment.In the design stage of precision planetary reducer,how to consider the error factors that affect lost motion and assign reasonable tolerances to each error factor to ensure that the lost motion of reducer is within the accuracy requirements,so as to meet the performance of mechanical equipment,This has always been one of the difficulties in the development of high-end equipment.The existing research establishes the mathematical model between the error factors and lost motion of planetary gear transmission through projection method and lumped mass method to calculate the lost motion of precision planetary reducer,but does not consider the influence of geometric eccentricity error and position error of multiple planetary gears on lost motion,which can not be ignored.Therefore,this paper takes the single-stage NGW planetary reducer as the research object,considers the influence of these error factors,uses the gear contact analysis method to establish the lost motion calculation model of planetary gear transmission,and on this basis,carries out the tolerance design for each error parameter(1)Taking single-stage NGW planetary reducer as the research object,the structure composition of the gear reducer is introduced,the error source of the planetary gear transmission mechanism is described.The error factors of gear thickness reduction,radial runout of gear,the position of the pin shaft of the planetary carrier and the clearance of the planetary gear hole are considered.The influence of these factors on the contact clearance of gear pair is analyzed,The corresponding probability distribution model is established.(2)According to the definition of lost motion of gear transmission system,the lost motion calculation model of planetary gear transmission is established through the contact analysis method of planetary gear transmission.Based on the established lost motion calculation model,the influence of four error factors,such as tooth thickness reduction,gear radial runout,planetary carrier pin position and planetary gear hole clearance,on the lost motion of planetary gear transmission mechanism is quantitatively analyzed,and the lost motion distribution of the corresponding planetary gear transmission mechanism within the tolerance range is simulated by Monte Carlo method.(3)According to the established error calculation model,the tolerance optimization design is carried out for each error parameter.The tolerance cost and tolerance qualification rate of each error parameter are the optimization objectives,the specified lost motion accuracy requirements are the constraints,the tolerance of each error parameter is the optimization variable,and the tolerance optimization distribution model is established,and the genetic algorithm is used to solve the problem,The correctness of the model is proved by an example.The test bench for measuring lost motion of planetary reducer is designed.The correctness of the model is verified by experiments.(4)Based on VB software development platform,the software of lost motion analysis and tolerance design of planetary gear transmission is developed.The above research content is of guiding significance to the research and development of precision planetary reducer which can meet the requirements of specified precision of lost motion.