3D Reconstruction Of Turbine Guide Vane And Welding Repair Path Planning Based On Point Cloud

Guide vane is an important flow part of turbine,and its working profile is complicated.In the long running process,the guide vane will produce cavitation and abrasion due to the impact of water flow,so the damaged parts are often repaired by welding.There are some practical problems in traditional welding repair,such as bad repair conditions,low repair efficiency,long repair cycle,and easy to damage workers’ physical and mental health.Therefore,based on point cloud data processing technology and combining 3D digital measurement technology with robot technology,this paper studies 3D reconstruction of guide vane and robot welding path planning,effectively improving the repair efficiency of guide vane welding and complex intelligence level.The main research contents of this paper are as follows:(1)Kinematic model establishment of scanning system and robot.By establishing the coordinate system of robot welding guide vane,the definition and transformation of each coordinate system are realized.Through the establishment of line laser scanning system,the three dimensional measurement principle of line laser scanning is analyzed.The kinematics of welding robot was modeled by standard D-H parameter modeling method,and the forward and inverse kinematics were solved.Based on the Robotics Toolbox of MATLAB,the robot working space and linear motion trajectory were simulated,which laid a theoretical foundation for subsequent robot welding guide vane experiments.(2)Guide vane point cloud data processing and 3D model reconstruction.Based on the analysis of point cloud correlation processing algorithm and reconstruction algorithm,the original point cloud information of guide vane is collected by three-dimensional digital scanning system,and the topological relationship between point cloud data is verified.Then the rough processing of point cloud data is completed by manual clipping.Analyze and select a suitable filtering algorithm to denoise the guide vane point cloud data.The point cloud simplification algorithm is analyzed,and the optimal algorithm is selected by comparing the experimental results of two kinds of simplification algorithms.The least square method is used to smooth the simplified point cloud data.Then the greedy projection triangulation algorithm is used to reconstruct the guide vane’s 3D model.The reconstruction results show that the 3D model of turbine guide vane with good quality and integrity can be obtained by combining the 3D scanning system and the point cloud data processing algorithm.(3)Welding path planning based on point cloud slicing technology.A guide vane oriented robot welding repair path generation method is studied.Combined with guide blade welding repair technology,the welding path scheme was designed.By identifying the pose of guide vane 3D point cloud data and converting it to the robot base coordinate system,the subsequent robot welding path extraction process was simplified.The point cloud slice intersection algorithm and B-spline curve fitting method were used to plan the welding path,and the path planning experiment was carried out on the guide vane surface to be repaired,which laid the foundation for the subsequent efficient extraction of welding repair path information.(4)Robot welding system construction and experimental verification.Based on the collected point cloud data of guide vane repairing surface,a set of point cloud detection and processing system is developed in combination with the point cloud processing algorithm proposed in this paper.Combined with guide vane welding parameters,the test and processing of guide vane point cloud data were completed by using the constructed experimental platform of welding repair robot,from which the welding path planning information was extracted and the path points to be repaired were imported into the controller of the welding robot,and then three groups of different path process path welding experiments were carried out.The tracking effect of welding robot welding gun on repair path and the repair effect of guide vane welding were verified.The experimental results show that the designed welding and repairing system can shorten the welding and repairing time of guide blades from 6 working hours to about 40 minutes.The subsequent machining time of guide vane is shortened from 3 working hours per piece to about 30 minutes.The ultrasonic inspection results show that the welding quality is good.The circumferential runout of the three journal journals of the guide vane is all within 0.03 mm,which meets the technical and quality requirements of the enterprise,thus significantly improving the repair and welding efficiency and quality of the guide vane.