Dynamics Research Of 3-CPR Parallel Mechanism With Clearance Of Kinematic Pair

With the progress of science and technology,China’s manufacturing industry needs to develop and expand.Therefore,the requirement of precision mechanical system is more and more high.There are many dynamic factors affecting the mechanical system,among which the clearance of motion pair is an important aspect.The clearance of the moving pair will increase the error of the mechanical system,reduce the stability of the system,aggravate the wear of parts,and shorten the working time of the machine.Because of the gap between the kinematic components,contact and collision inevitably occur in the process of motion.Therefore,the correct description of the kinematic collision process of mechanism is the basis of studying the dynamic characteristics of mechanical system.In this paper,the three-dimensional clearance model of kinematic pair is simplified and applied to the 3-CPR spatial parallel mechanism with three translation.The dynamic characteristics of the 3-CPR mechanism were analyzed under different clearance conditions,and the 3-CPR software simulation model was established.The main research contents are as follows:According to the simplified 3D motion pair model of the rotating joint,the vector model was obtained by the vector description and structure description.The judgment method and criterion of relative motion state of moving joint are established by mathematical method,and the relative impact velocity of clearance joint is determined.The 3-CPR inverse kinematics solution,the velocity,acceleration and deformation equations of the spatial parallel mechanism are analyzed.On this basis,the 3-CPR ideal dynamics equation of the spatial parallel mechanism was established by Newton-Euler method,and the dynamics characteristics of the mechanism itself were analyzed by numerical simulation.The simplified clearance model of rotating pair was embedded into the clearance dynamics model of 3-CPR mechanism,and the clearance dynamics model of3-CPR mechanism was established.The numerical solution method and process of the clearance dynamics model were described in detail.The 3-CPR clearance dynamics model of the spatial parallel mechanism was numerically simulated.According to the calculated data,the influence of clearance on the dynamics characteristics of the spatial parallel mechanism 3-CPR was studied.According to the influence of displacement,velocity,acceleration and other performance indexes on the clearance of the kinematic pair of the parallel mechanism under a given trajectory,some constructive suggestions are put forward to improve the kinematic characteristics of the parallel mechanism.The three-dimensional solid model of the research object 3-CPR is established by the three-dimensional software Solid Works,and then the 3-CPR gap simulation model is established by the dynamic simulation software ADAMS.The.mnf neutral file of the mechanism bar is established by the ANSYS software to replace the rigid parts.The rigid-flexible hybrid simulation model of the 3-CPR parallel mechanism was established,and the joint simulation system was established by MATLAB and ADAMS.The influence of different structural parameters and variables on the dynamic characteristics of the3-CPR parallel mechanism was analyzed,and the established clearance dynamics model was verified.