Research On Design Of NG-TIG Welding Torch

Narrow-gap welding of low-pressure rotors of nuclear power is one of the key technologies in the manufacture of nuclear power equipment. With large-scale in size of nuclear power equipment, the thickness and groove depth of the low pressure welding rotor have increased significantly. As a core component of welding equipment, the narrow-gap welding torch mostly relies on import, which may be restricted in technology by foreign countries. Therefore, it is necessary to develop our own domestic narrow-gap welding torch with independent intellectual property rights. This paper focuses on basic design and research of NG-TIG welding torch.After systematic study on narrow-gap welding procedure features of large-scale low-pressure rotor, such as poor visibility of weld bead in deep narrow gap, multiple weld beads and layers, strict control of lack of sidewall fusion and other welding defects,a design of NG-TIG welding torch is carried out based on heat conduction theory. The ANSYS software is used to calculate the temperature distribution of the welding torch while the current is 250A, the input water is 25℃, the output water is 35℃and the rate of cooling water flow is 0.6m/min. A NG-TIG welding torch with 8mm thickness, 13mm width, "V" shaped water loop and two gas chambers is designed. A NG-TIG welding torch test platform is set up, which gives a guarantee for the test and research of narrow-gap TIG welding torch under single influence factor on weld quality.The welding torch is designed as combined and adjustable. The effect of the distance between tungsten electrode and work piece, the positions of gas chambers on welding quality are studied. Finally the proper structure parameters of the welding torch for high quality weld joint are obtained, this provides the valuable reference for the design of real narrow-gap welding torch.