Three-Dimensional Elliptical Vibration-Assisted Cutting Freeform Surface Path Planning And Surface Topography Investigation

Three-dimensional elliptical vibration-assisted turning(3D-Elliptical Vibration Cutting,3D-EVC)is an ultra-precision machining technology proposed in recent years.Due to its unique intermittent cutting and friction reversal characteristics,it can be used to manufacture Since the 3D-EVC technology was proposed,its research focus has mainly focused on device design,system control,cutting force and cutting temperature,etc.There is a lack of relevant research on the problems of path planning in complex curved surface processing.Research.This dissertation is based on the problems existing in the current traditional tool path planning algorithm,the optimization of the machined surface morphology and turning parameters.The main work is as follows:(1)Analyze the motion principle of 3D-EVC and introduce the self-developed 3D-EVC device and its structural composition in our research group.By analyzing the isometric and equidistant path planning algorithms,a path planning optimization algorithm is proposed to solve the problems of uneven residual height in the free-form transition area,decreased surface quality of machined surface,and interference cutting.A model is established based on the isometric and equidistant path planning method,which inserts a circular arc into the transition area and solves the optimized tool position points after path optimization.Using a sine surface as the specific research object,the path is simulated and verified by simulation software.(2)Using the tool contour replication principle,a 3D model of the surface of 3D-EVC turning is constructed,and three surface evaluation indicators of peak-to-valley height PV,root-mean-square deviation Sq,and three-dimensional contour arithmetic mean deviation Sa are established.The method of two-dimensional wavelet analysis is used to decompose,reconstruct,and numerically analyze the various scale components of the three-dimensional surface morphology data.The surface morphology accuracy obtained by the proposed optimized path algorithm is verified and compared with simulation software.The effects of turning parameters and elliptical vibration parameters on machined surface quality are discussed by single-factor method.(3)In view of the problem that the traditional particle swarm optimization algorithm is prone to premature convergence to local optimal and slow convergence speed in the later stage of iteration,an improved particle swarm optimization algorithm based on simulated annealing algorithm is proposed,and its performance is tested by testing functions.A relationship model between 3D-EVC parameters and surface morphology is established,and the minimum surface roughness value is taken as the objective function for optimization.The optimized results are calculated by simulation software.(4)3D-EVC turning experiments are conducted,and a representative sine surface is selected as an example for tool path generation and machining.After machining,the machined workpiece is inspected using a white light interferometer.The surfaces obtained from different algorithms are compared to verify the feasibility of the proposed tool path optimization algorithm and the accuracy of the machined surface morphology.The best optimization parameter sets obtained from the parameter model optimization by the traditional particle swarm optimization algorithm and the improved particle swarm optimization algorithm are respectively used for cutting experiments.The machined workpiece is inspected using a white light interferometer for comparison analysis to verify the performance of the proposed improved particle swarm optimization algorithm.