The Development Of Automatic Bead Welding System For Hot Wire TIG

The metallurgical composite bimetallic tube produced by bead welding,which has excellent mechanical properties and corrosion resistance,is significant for the normal exploitation and transportation of marine oil and gas,especially for that in the deep sea with strong corrosive medium.In order to realize welding automation,enhance welding efficiency and guarantee welding quality,relying on the national science and technology major projects(Marine deep-water engineering of major equipment and supporting engineering technology),large oil and gas fields and gas layer development projects,this paper aims to develop an automatic welding system for hot wire TIG applied in bead welding of the pipe joint inner wall,hence it has important practical application value.The automatic welding system for hot wire TIG consists of mechanical system,control system and welding system.In this paper,the mechanical system take vertical and ring weld as basic feature under analysis and comparison according to the technical index of the system and the working object.The mechanical system is composed of a welding machine head(three-dimensional linear motion mechanism),a horizontal rotary platform(one dimensional spin motion mechanism),a cross operating machine and wire feeding mechanism.The avoidance of use of water electrical gas slip ring structure and the wire disc mounted on the welding head of mechanical system,not only simplify the welding head structure,but also reduce cost of the equipment,and the operation reliability of system has been also increased significantly.The control system developed in this paper takes PLC as the core to control movement and welding.The calculation formula for arc blowout angle,which is changed with the change of welding torch tungsten height h,is proposed based on measurable geometric parameters(piercing pipe radius rn,piercing pipe height hn,main pipe radius R)for three-way or four-way pipe,and it has been applied in PLC program to realize automatic arc blowout and arcing when the torch travels to the piercing pipe(void)edge under the direction of welding.With the design of PLC program,it has been realized the functions that welding parameters monitoring and setting based on realtime communication with main welder and heater welder,adjusting of welding torch and workpiece position,automatic revolved workpiece inner wall bead welding,determining the positions of welding torch and workpiece and automatic voltage control which guarantees final welding quality.The man-machine interactive system,which is developed in this paper,is based on the touch screen,covers all control functions of the system.It is including five kinds of interfaces,which are main interface,parameter setting interface,welding adjustment interface,welding interface and warning interface.It has been shown that the automatic bead welding system for hot wire TIG can automatically weld the pipe joint inner wall based on welding experiments.The welding seam is continuous and uniform,the movement of system is precision and the welding of system is stable.