Aluminum Alloy Sheet With Ultrasonic Agitation Welding Equipment And Technology Research

Sheet structure is the main features of lightweight aluminum components, friction stir welding has great economic advantage in such technology and has a great prospect in the forming of welded aluminum components. However, in the process of aluminum alloy sheet friction stir welding, the heat capacity and thermal inertia in the welding zone is small, the stability of temperature in the welding process can be easily affected by the soldering station contact interface, cooling medium and thermal conductivity of the welding pieces, and so easy to produce weld defects such as osteoporosis, at the same time the deformation of welds can be easily produced because the weldment itself is very thin and the effect of residual stress, so the two problems become the technology bottlenecks of sheet friction stir welding. Based on the previous research of ultrasonic stir welding, the ultrasonic stirring plate welding system was developed in this paper, mixing head was improved according to aluminum alloy sheet welding, the dynamic compaction rollers and water spray cooling devices was designed, and integrated with the friction stir welding, expected to solve the problem of thin plate welding.Aviation aluminum alloy sheet has been successfully welded by ultrasonic stir welding in this paper.1.8mm thick 2524 and 2.5mm thick 2219 aluminum alloy was adoped in the experiment and appropriate welding parameters and cooling conditions of high-strength aluminum alloy sheets were explored through a large number of ultrasonic stir welding experiments, some comparative experimints were done between ultrasonic stir welding and friction stir welding, through the comparison and analysis of the weld appearance, mechanical properties,microstructure,microhardness and fracture scanning found that the weld properties of ultrasonic stir welding was superior to friction stir welding.The experiments reselts showed that the best weld was available when welding parameters was 1600r/min,120mm/min.The average tensile strength of 2524 aluminum alloy welded by ultrasonic stir welding was 399.5MPa,which reach to 89.9% of the base metal, and the average tensile strength of 2219 aluminum alloy was 393.5 MPa which reach to 89.4% of the base metal, the ultrasonic stir welding samples average tensile strength was similar with friction stir welding but had a great stable strength properties, the higest and lowest of 2524 tensile strength only lOMPa different, and the higest and lowest of 2219 only 3MPa different.The defect rate of FSW samples reached to 40% while ultrasonic stir welding almost no defects, the deformation of welds by ultrasonic stir welding can be controlled below 0.5mm. Experiments showed that the ultrasonic stir welding can improve the weld strength,increase the stability of the weld quality and control the joint deformation dffectivly.Weld quality was significantly improved after the introduction of ultrasound from the results contrasted, ultrasound as a supplementary energy could play a certain positive effects to the welding process and weld quality. On one hand, the conductivity of the ultrasonic and dielectric absorption of ultrasonic energy, which made the ultrasound can be builded in the weld forward side and the weak role place of mixing head (defect-prone office), so to inhibiting the formation of defects. On the other hand, ultrasonic vibration can bring the metal particles around the mixing head vibrated frequenly, and the acceleration was great, the flow resistance can be reduced, and the flow of the metal around the mixing head was enhanced, which can inhibit the welding deformation in a certain extent.