Performance Analysis And Optimization Of A Hybrid Machine Tool With Large Rotation Angle

The hybrid machine tool combines the advantages of the parallel/series mechanism and compensates for their respective disadvantages.This paper proposes a structure of a large-angle hybrid machine tool.The machine tool can complete five degrees of freedom machining operations in the machining workspace.At the same time,it can achieve larger corner rotation.The paper analyzes and optimizes the performance of the hybrid machine tool with large rotation angle in the following aspects:First,the structure of the hybrid machine tool with large rotation angle is presented.The parallel module of the hybrid machine tool is distributed asymmetrically.The first and second branch chains are PRT type motion branch chains,the third branch chain is P-2SS type motion branch chain.Second,the kinematics of the hybrid machine tool with large rotation angle is researched.Based on the vector method and numerical method,the equations of the forward and inverse solutions,velocity and acceleration of the hybrid machine tool are established.Through MATLAB software programming,all the positive and inverse solution of the positions and orientations and the simulation velocity and acceleration variations are obtained.Third,the performance of hybrid machine tool with large rotation angle is analyzed.Based on the Jacobian matrix method,the positions of the boundary singularity,local singularity and structural singularity of the hybrid machine tool are obtained.The numerical search method is used to program the movement workspace of the hybrid machine tool and the range of the rotatio n angle can reach(-30?~ 80?).The stiffness matrix and dexterity matrix of the hybrid machine tool are derived.An example is given and plotted in stiffness and dexterity atlas.Fourth,the dynamic performance of the hybrid machine tool with large rotation angle is studied.The dynamic equations for the hybrid machine tool are established using Kane method.The dynamics of the machine tool is simulated using ADAMS and MATLAB software.Fifth,with the velocity,stiffness and dexterity of the hybrid machine tool as the optimization objectives,based on the integration of Isight optimization software with MATLAB software,a multi-objective reliability optimization design model of the hybrid machine tool is established.A well-distributed Pareto solution set is obtained.An example of optimization is given to reflect the effectiveness of the optimization.