| Tubular busbars which overcome the shortcomings of rectangular busbars that heat production and short circuit electric power are too large have been widely used in the power industry.As a new type of solid phase welding technology,friction stir welding has broken the welding limitations of low melting point metals.The subject of this paper is based on the industry background and technical background described above,and starting from the project signed by the research team and Tianjin Wolfat Electric Company.In combination with the requirements of tubular busbar forming,features of large load torque,complex weld shape,high process requirements and so on during friction stir welding,a lot of researches have been carried out on the mechanical structure,control method of welding equipment,welding process and so on.Tubular busbars friction stir welding equipment has been successfully developed,and a stable welding process has been proposed.This article mainly contains the following aspects:(1)Combined with the characteristics of welding process,in view of the characteristics of heavy load and high torque of welding tool during welding process,an integrated welding tool rotation design idea was proposed.Utilized the gantry accommodating device to enhance the turning rigidity of the welding tool,which making the welding machine simple,flexible and practical,and different welding experiments can be performed by controlling parameters related to the quality of the weld formation.(2)The design idea of realizing the welding inclination angle by translational motion was proposed on the basis of fully studying the structure of the friction stir welding equipment and the shape characteristics of the pipe at domestic and foreign.Utilized translation axis instead of rotation axis reduced the complexity of the equipment and improved the operational stability of the equipment.It also determined that the equipment was mainly composed of the following systems,including:support system,power system,welding tool system,auxiliary system,control and safety system.(3)Broke through the traditional hydraulic fixing method,the unique workpiece clamping device was designed to protect the pipe,which simplified the equipment and reduced the cost in order to solve the difficulty of large torque during the welding process.Combined with the characteristics of the process,the box-type support system was designed.The pad,the tooth sleeve and the V-shaped groove were designed to meet the requirements of large load and multidiameter welding.The power system including the rotating mechanism,the slewing mechanism and the lifting mechanism was designed to successfully realize the process of rotation,pressing,welding and arcing.The welding tool system integrating water cooling,gas protection and thermocouple temperature measurement was designed to solve the problem of oxidation,high temperature instability and temperature blind zone in the welding process.An auxiliary system including a gear sleeve opening and closing mechanism,an arc closing mechanism and a guide roller pressure roller mechanism was designed,which made the equipment transmission flexible and the loading of the workpiece quick.(4)Control and safety system design.Utilized the Fagor 8055I CNC system and its supporting hardware,the CNC and its built-in PLC were used to realize the control of the local closed-loop and the remote I/O module.The development of the welding equipment control software was completed by using the Fagor programming language.(5)The influence of different process parameters on the weld surface defects and internal defects was explored by using the equipment designed,assembled and commissioned.The microstructure of the weld under specific process conditions was analyzed,including welding speed,rotation speed,the plunge depth,inclination and so on,and a defect-free welding process was proposed. |
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