Research On Dynamics Of Parallel Double Crank Mechanism With Clearance

Due to assembly requirements,machining errors or long-term wear and tear between the various parts of the mechanism,there will always be a certain gap between the components in the mechanism,and the gap will cause contact and collision between the components,which will greatly affect the dynamic characteristics and life of the mechanism.It may even cause dynamic output oscillations,reduced motion accuracy,reduced service life,and even functional failure of the mechanism.Based on the structure of the output mechanism of the cycloid planetary reducer and the principle of short-period transmission,this paper focuses on the analysis of the gap between the crankshaft and the cycloid in the cycloid planetary reducer,and the contact between the small-period motion accuracy of the cycloid and the hinge gap.The impact of force.(1)Simulate the relative motion relationship between a single crankshaft and the shaft hole to model the single-degree-of-freedom single-clearance mechanism,and perform the kinematics modeling of the mechanism to obtain the center of mass displacement,velocity and acceleration coordinates of the rotating shaft in the mechanism.According to the Lagrangian formula,the mechanism is modeled dynamically,and the formula of the critical angular velocity of the rotating shaft in the mechanism is obtained.Parametric modeling of the connecting pin to control the gap size,calculation of the contact stiffness coefficient based on Hertz contact theory,dynamic simulation analysis of the mechanism using Recur Dyn software,analysis of different gap values,different input speeds,different contact friction coefficients and differences The influence of working conditions such as damping coefficient on the dynamic characteristics of single-gap single-degree-of-freedom mechanism and the contact force at the gap.(2)Focus on the analysis and analysis of the influence of a parallelogram in the threecrank parallelogram output mechanism with clearance in the RV-110 E reducer on the motion accuracy of the cycloid wheel.The solid model of the single-input parallel double-crank mechanism is carried out,and the kinematics of the mechanism is built.The model obtains the displacement,velocity,and acceleration coordinates of the center of mass of the moving link in the ideal state without clearance and the state with clearance respectively,and the dynamic modeling of the mechanism obtains the two sides of the moving link in the ideal state without clearance and in the state with clearance.The pin hole x-axis direction and y-axis direction contact force formula.The dynamic simulation analysis of the mechanism,considering multiple gap states,analyzes the effects of the above-mentioned working conditions on the dynamic characteristics of the moving connecting rod of the mechanism and the contact force at the gap.(3)In order to accurately simulate the state that the two crankshafts in the RV-40 E reducer are simultaneously used as inputs,the entity modeling of the dual-input dual-crank mechanism,the dynamic simulation analysis of the mechanism,and the accurate simulation of the input of the RV-40 E reducer State,the influence of the parallelogram in the output mechanism on the motion accuracy and contact force of the cycloid is analyzed.(4)Based on the RV transmission output mechanism is a single-degree-of-freedom parallel mechanism composed of three double-crank parallelogram mechanisms,the entity modeling of the three parallel double-crank parallel mechanisms with single input is carried out,and the kinematics modeling of the mechanism obtains the displacement of the moving triangle center of mass,Speed and acceleration coordinates.Considering the coupling of multiple gaps,the effects of the aforementioned working conditions on the dynamic characteristics of the moving triangle in the parallel mechanism and the contact force at the gap are analyzed.(5)Based on the RV-110 E reducer that uses three crankshafts as inputs at the same time,the three-input three-crank mechanism is solidly modeled,and the input state of the RV-110 E reducer is accurately simulated,and the above-mentioned working conditions are analyzed for the three output mechanisms.The dynamic characteristics of the moving triangle and the influence of the contact force at the gap in a double-crank parallelogram single-degree-offreedom parallel mechanism.