Research On The Equipment And Welding Technology Of Narrow-Gap-Welding Of Thick-Plate 6061 Aluminium Alloy

Because of its excellent physical and chemical properties, aluminum alloy has been widely used in the field of aerospace, aviation and rail passenger cars in recent years. With the improvement of thick plate production technology, more and more aluminum alloys are applied in the aerospace field. Therefore, the demand for the welding of aluminum alloy thick plate is increased. However, the traditional welding method applied on aluminum alloy would cause serious faultiness, such as severe deformation after welding, the porosity and crack tendency, the mechanical properties of welded joints is poor.In order to solve the problem of Aluminum Alloy welding deformation, we adopt the narrow gap groove and solve the narrow gap welding sidewall fusion problem is the most important thing. The existing narrow gap welding torch has the problem like serious fever of welding torch will appear after welding for a long time and poor arc stability in welding process. In order to solve the problems above, we designed and optimized the narrow gap welding torch. Make improvements from the torch cooling, gas protection, conductive mechanism, conductive mouth and swing positioning system and other institutions, preparing for narrow gap welding of thick plate Aluminum Alloy.(1)First we have completed the design and optimization of the improved arc narrow gap welding torch, the optimized torch can maintain stable welding process of thick plate in three positions of flat, vertical and horizontal, can meet the welding requirements.(2)Studied on the stress conditions of the narrow gap welding pool, after adding the swing mechanism, the temperature field and the stress of the welding pool have changed. The influences of the angle of swing, the speed of the swing, the residence time on the side wall and the welding speed on the flow properties of the welding pool have been analyzed. Using the high-speed camera system research, we have studied the influence of swinging angle, swinging speed and the impact of residence time on the side wall on droplet transfer. In order to improve the welding process stability and the welding pool, we should try to increase the swing angle and the residence time on the side wall, and the swing speed should not be too large or too small.(3)According to the orthogonal experiment theory, the L16(45) orthogonal test table is designed. The influence of various parameters on the penetration depth of the side wall is swing angle> welding speed> residence time > wire feeding speed > swing speed. According to the conclusion of the orthogonal experiment, we designed single variable experiment and studied the influences of swing angle, welding speed, residence time, wire feeding speed, swing speed on the welding formation. According to the results of orthogonal test and single variable test, the technological parameter range of narrow gap welding of thick plate aluminum alloy was obtained.(4)Single pass multilayer welding of 40 mm thick 6061-T6 aluminum alloy was carried out, and we analyzed the phenomenon of side wall incomplete fusion in the welding joint and optimized the welding process parameters, I got the small heat affected zone and the good formation of welding joints. I analyzed the upper part, middle part and lower layer of the microstructure of multi-layer welding seam.