Research On Key Technology Of Automatic Welding Robot For Boiler Inner Wall Pipe Based On Vision

With the continuous improvement of automation in welding field,industrial robot is a representative work of automation,which can replace human beings to complete many tasks.Therefore,robots are usually applied to the actual welding process,which makes the automation process of welding field step forward a great step forward.The weld track intersecting of pipe and pipe-intersecting-intersecting line is a complex space rotation curve,which is difficult to track,and the requirements for robot structure and control system are relatively complex;in the welding process of the intersecting line,it needs to experience many welding methods such as horizontal welding,inverted welding and vertical welding,which requires higher requirements for the flexibility of robot.Nowadays,there are a lot of pipe pipe joint welds in the petroleum,chemical and boiler industries.The existing robots can not meet their needs,and the welding quality is poor,which can not meet the requirements of the chemical boiler industry.In this paper,a special robot for automatic welding of the pipe and pipe intersecting line of boiler inner wall is designed based on vision,aiming at the working environment and complexity of the welding seam of the pipe pipe in the inner wall of boiler.Aiming at the reality of low quality of the pipe pipe,the welding method matching the best welding current and the best welding speed is proposed,and a lot of relevant experiments are done to verify its feasibility;in order to ensure the feasibility of the robot To ensure the welding seam tracking and welding quality,a new method of center detection based on Hough transform is proposed to improve the positioning accuracy.(1)Design a special robot for automatic welding of the inner wall of boiler based on the visual pipe and pipe.According to the particularity of the working environment and the intersecting line,a special welding robot structure for the six DOF pipe pipe joint line welding is analyzed and designed.The structure is modeled by croe4.0.The working principle and system scheme of the robot are introduced,and the selection of each part of the robot is completed.(2)The welding method matching the best welding current and the best welding speed is proposed.The model of the pipe pipe joint line,the robot motion model,the welding gun model and the D-H linkage coordinate system are established.The forward and inverse kinematics of the robot are solved,and the best welding current matching and the best welding speed matching method are proposed.According to the variety of welding types of the intersecting lines,a lot of related experiments are carried out on the horizontal welding,vertical welding,horizontal welding,vertical welding,vertical welding,vertical welding and vertical welding to horizontal welding respectively,which verifies its feasibility.(3)A circle detection algorithm based on Hough transform is proposed.A visual center location method based on Hough transform is proposed.According to the similarity between ellipse and center of circle,the longest line line between relative points above the circle is found,and the center point is calculated,and the center coordinate of the circle is obtained.The feasibility of the above innovation method is verified by the experiment platform of the boiler inner wall based on the visual pipe and pipe joint welding automation machine.The experimental results show that the welding quality is good,the efficiency is high,the system is stable,and the experiment verifies the rationality of the welding machine designed in this paper.