Kinematics Analysis And Mechanical Simulation Of Mechanism Of 3-UPRP Parallel Machine Tool

Parallel mechanism has irreplaceable advantages over the serial mechanism in stiffness and cumulative error because of its closed chain character,so it is widely used in flight simulators,micro operators,parallel machine and so on.Especially the parallel machine can make up for the disadvantages of the traditional machine and computer numerical control machine in multi-axis motion and complex curve surface machiningA new 3-UPRP parallel mechanism with two rotational and one translational applied to parallel machine is presented in this paper.Firstly,the configuration of 3-UPRP parallel mechanism of the main structure of parallel machine is introduced in detail.The DOF(degree of freedom)of 3-UPRP parallel mechanism is analyzed using the screw theory and the modified DOF formula.The position solution of parallel mechanism is solved through the closed-loop vector method and the workspace of the parallel mechanism is analyzed.The workspace of the parallel mechanism is enlarged by arranging the translational kinematic pairs near the moving platform in different planes.The maximum and minimum values of the three driven pairs of the parallel mechanism are permutated and combined.The workspace boundary of the moving platform vertex of the parallel mechanism is obtained through simulation,and the velocity curve and acceleration curve of the parallel mechanism under the workspace boundary is obtained.The statics of the parallel mechanism is studied by the vector method and the dismantlebar method.According to the static equilibrium equations,the force circumstance of each kinematic pair of the parallel mechanism can be obtained.The mass of each rod of the parallel mechanism is set to be small enough to make the movement speed of the parallel mechanism very small,in other words,the static analysis of the parallel mechanism is simulated under the premise of neglecting the inertial force of the parallel mechanism component.In static stiffness,according to the relationship between compliance and stiffness,the compliance matrix of each member in the branch of the parallel mechanism tool is analyzed firstly.The stiffness matrix of the parallel mechanism is obtained by the method of coordinate transformation matrix.The stiffness characteristics of the parallel mechanism are simulated by using the finite element software ANSYS Workbench.Finally,the dynamics of the parallel mechanism is studied by Lagrangian dynamics.The first-order influence coefficient matrix of the parallel mechanism is solved by the virtual mechanism.The dynamic model of the parallel mechanism is obtained and make the dynamic simulation by software ADAMS.Simulation analysis shows that the new 3-UPRP parallel mechanism proposed in this paper has good processing performance and has certain guide significance for optimization and control of parallel machine.