Workpiece Setup Optimization Based On Kinematics,Dynamics And Workspace Of Five-axis Machine Tool

Because of a series of advantages,such as high efficiency,high accuracy and variable cutter axis direction,five-axis CNC machine tools have inherent advantages in processing complex parts with high accuracy requirements,such as aero-engine blades.However,compared with three-axis CNC machine tools,five-axis CNC machine tools also have characteristics such as nonlinear error and singularity phenomenon.Singularity will not only reduce the processing quality of the workpiece,but also cause some damage to the machine tool due to infinite acceleration.Aiming at the singularity phenomenon,the current solutions mainly consider the singularity problem in the tools path planning stage.And after the tools path is generated,the singular points are deleted from the tools path and inserted into the appropriate tool positions.This paper presents a method to solve the singularity by adjusting the attitude of the workpiece’s setup;on the basis of solving singular problems,the dynamic performance of five-axis machining is analyzed,and the feeding speed of the machine tool is optimized,aiming at minimizing the maximum acceleration of the rotating shaft in the whole machining process,so as to improve the feeding rate of the machine tool as much as possible and shorten the time required for the whole machining.At the same time of solving the first two problems,consider the position of the workpiece’s setup,so that the working space required for processing(the smallest bounding box of the workpiece in the whole machining tool position state)is the smallest.The optimization algorithm of workpiece’s setup mainly includes the following procedures: suppose the workpiece does not move during machining,and the cutter moves in five-axis machining.Extracting the cutter locations and the cutter axis directions from a tools path file;Moving the starting point of the cutter shaft vector to a certain unit sphere origin(the unit sphere is called Gaussian sphere),then the end point falls on the sphere,and discrete points on the gauss sphere are obtained.Finding the boundary of discrete points and fitting it into spline curves.Offset the spline curve on the spherical surface,and remove self-intersection from the offset curve.Defining an objective function aiming at solving singular problems and optimizing dynamic performance,and finding the best attitude of the workpiece’s setup by using genetic algorithm;Define the objective function aiming at the minimum workspace what five-axis machining need,and use genetic algorithm to find the best position of the workpiece’s setup.Finally,simulation experiments are carried out on the algorithm proposed in this paper to compare whether there are singular problems of workpieces in different processing attitudes,and at the same time,the dynamic performance of workpieces in different attitudes and the minimum working space required in different positions are compared,which verifies that the algorithm proposed based on this research can solve singularity and optimize the dynamic performance of processing at the same time,and make the required working space minimum.