Research On Robot Path Generation And Optimization For Laser Cladding Forming

As a motion platform in laser cladding forming(LCF),the application of multi-joint robot can improve the flexibility and cladding capability of cladding system,and promote the LCF application for individuation manufacturing,parts repair,green remanufacturing and so on.However,the laser cladding forming system based on multi-joint robot exists problems with uneven distribution of mesh model,inefficiency of teaching programming as well as mutation and collapse occur during cladding.For these problems,combining laser cladding technology and robot technology,the model topological relation is established by extracting the Stereo lithography(STL)model information,and the generating methods of position information and posture information of the robot cladding path are put forward.The single-level and multi-level optimization of robot cladding paths are employed and the experimental verification is conducted.The main research contents of the thesis are as follows.In order to balance the relationship between error influence parameters and cladding paths,an optimizing model of error influence parameters based on the particle swarm optimization(PSO)is established.According to the model expectation,the optimal value intervals of influence parameters that satisfies expectation error are seeked.For the problem of uneven distribution for STL model during laser cladding forming,which affects the cladding path quality,a mesh model optimization method based on the discrete Laplace is employed to improve the uniformity of the triangular face in the model.On this base,the regular degree calculation model is established to quantify the optimization by radius ratio method.To improve the cladding capability of LCF system and generation efficiency of cladding paths,a generating method of robot cladding paths is proposed based on the intersecting edge topological relation.According to the geometry information and normal vector information of the STL model,the intersecting edge information is obtained and the topological relation of model is established.Through the removal of redundant points for STL model and the sort of robot path points,the position information of robot path points are obtained.The direction of the robot cladding paths is unified by the method of extremal bounding box.According to the geometric relationship between the normal vector information of STL model and the robot cladding path points,combined with robot posture representation method of roll pitch and yaw,the posture information of robot path points is achieved and the generation from CAD model of parts to robot paths for laser cladding is realized.Based on the analysis of the robot cladding paths,the single-layer optimization and multi-layer optimization of robot cladding paths are respectively carried out.To solve the mutation problem between the path points of layer shapes,an optimization method based on the single-layer path interpolation method of layer shape is proposed.The position interpolation model and posture angle interpolation model of the path points are established.The layer shape is optimized according to the constraint conditions of the robot cladding paths.To solve the problem of collapse during the laser cladding forming process,the reason for collapse is analyzed and a robot cladding paths optimization method based on the multi-layer path interpolation is proposed.The relationship between the adjacent two path layers is established by Haudorff distance.The position of interpolations and the number of interpolations are obtained according to the optimization model of robot cladding paths,meanwhile,the optimization of the robot cladding paths is complete to ensure a smooth work for LCF.According to the generation of robot cladding paths,the robot cladding paths generation software RCF is developed.The CAD models of robot and the peripheral equipment have been established.A simulation platform of LCF system based on multi-joint robot with six DOF(degrees of freedom)has been built.Through the LCF simulation,the issues of singular points and collision are inspected and the verification experiments are conducted by importing the simulated data into the robot controller.The overlap calculation model is established and overlap testing experiment is finished.The validity of the robot cladding paths generation method of the topological relation based on the intersecting edge is verified by the LCP experiment of different parts,and the correctness of optimization method based on the path interpolation verified by the optimization contrast experiment of robot cladding paths.