Study On Vibration Characteristics And Efficiency Of A Two-step Sine Movable Tooth Drive

Movable tooth drives have the advantages of light weight,high transmission efficiency,wide range of transmission ratio and large bearing capacity,and are especially suitable for oil drilling rig and robot arm,etc.In this paper,free vibration analysis,modal analysis and transmission efficiency analysis are carried out for a two-step sine movable tooth drive.The two-step sine movable tooth transmission prototype is produced by which the related experiments are completed.The dynamic model of the two-step sine movable tooth drive is built.The whole system is simplified into four subsystems for free vibration analysis.The differential equations of motion for each subsystem are built,and then the differential equations of motion for the whole system are given.The natural frequency of the whole system is calculated,and the influence of parameter change on the natural frequency is analyzed.The system is divided into rotational mode and movable tooth mode by analyzing the mode vector of the vibration mode.The sensitivity and changes of the natural frequencies along with the system parameters are analyzed.The results show that the meshing stiffness between sinusoidal raceway and movable teeth has great influence on the natural frequency and sensitivity of the system.ANSYS software is used for modal analysis of the two-step sine movable tooth drive,and the first twenty natural frequencies and mode shapes of the drive are obtained.The effects of the system parameters on the natural frequencies and the vibration modes are investigated by changing the design parameters of the mechanism.The results show that the main vibration forms of the two-step sine movable tooth drive are the vibration of first-stage guide frame,second-stage guide frame and movable teeth,and the vibration of the second-stage guide frame varies obviously with the parameters.According to force analysis of the movable tooth meshing pair of the two-step sine movable tooth transmission,the expression of the output torque of the movable toothtransmission system is deduced,and then the formula for calculating the transmission efficiency of the system is given.The transmission efficiency of the system is analyzed by using the efficiency formula,and the variation law of the transmission efficiency of the system is obtained.The results show that in order to improve the transmission efficiency,the amplitude of sine tracks and the circumferential radius of the center of the movable tooth should be increased,and the transmission ratio should be allocated reasonably.A 3D model of the two-step sine movable tooth drive is developed using UG 10.0software and a model machine is produced by which the transmission efficiency experiment and vibration characteristics experiment are carried out.The maximum transmission efficiency is 85% and the average transmission efficiency is 60%.The experimental efficiency is close to the calculation efficiency and the difference between the measured frequency and the calculated natural frequency of the first order is 3% which verifies the correctness of the theoretical analysis.