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In this study, an effective artificial neural network (ANN) model was established to predict the bending deformation in a welded square thin-walled aluminum alloy tube structure. The input variables of the ANN model include four controllable positional parameters of welding, whereas the bending deformations in the X-axis and Y-axis directions are considered the target outputs. To estimate the bending distortion rapidly and accurately, a supervised multilayer feed-forward backpropagation (BP) neural network was proposed. A total of 270 finite element (FE) numerical simulations were performed to generate a database for training the designed ANN model. Moreover, a series of experiments were conducted to confirm the accuracy of the FE models. The predicted values from the designed BP neural network and the FE simulation results were compared to evaluate the performance of the proposed ANN model. The comparative study demonstrated that the proposed BP neural network model can accurately predict welding-induced bending deformations within an available range of welding position parameters. [ABSTRACT FROM AUTHOR]

The Lorentz force distribution on a tube is the dominant factor that determines the tube deformation behavior in the electromagnetic forming process. However, the existing forming technologies in this field are mainly based on a single-coil system, which results in a relatively fixed Lorentz force distribution and makes it difficult to control the forming process or the final tube shape. To solve this problem, a three-coil forming system composed of three sub-coils and two pulsed power supplies is developed for tube forming in this work. Both numerical simulation and experimental results show that the three-coil system can be easily applied to alter the Lorentz force distribution through adjusting the discharge voltage of sub-coils, providing an effective way to improve the deformation uniformity and control the deformation shape. It is found that an AA6061-O aluminum alloy tube with an inner diameter of 76 mm and a thickness of 2 mm can be deformed with a homogeneous deformation range of about 23.56 mm via the three-coil system in the experiments, while the range is only about 11.48 mm under the same conditions when using the conventional single-coil system. Meanwhile, it is demonstrated that the three-coil system can achieve a variety of tube shapes including concave and convex profiles with different uniformity. The developed method and obtained results are of good value for expanding the application of electromagnetic tube forming. [ABSTRACT FROM AUTHOR]

Connection technique of copper and aluminum is a key challenge in refrigeration industry. In this paper, rotary swaging connection process is proposed to connect cooper tube and aluminum tube in physical way. We find the length of overlapped area has a great effect on the joint reliability, and it should exceed the deformation region length. The joint strength is approximately determined by necking. With the reduction of the diameter at the necking area, joint strength first increases and then decreases. Some experiments are carried out to test the joining strength. It is shown that the joints are reliable enough, and joining by rotary swaging method is effective to combine copper and aluminum tubes. [ABSTRACT FROM AUTHOR]

Flow forming technology is widely used in the production of the axisymmetric industrial parts. The advantage of flow forming process over other manufacturing methods such as press forming is use of simple tooling, reduced forming loads due to localized deformation, and enhanced mechanical and surface quality of finished parts. In this study, the effects of thickness reduction on the mechanical properties and spinning accuracy are experimentally investigated on 7075-O aluminum tube. A prototype spinning machine has been designed and manufactured. The effects of spinning accuracy, surface roughness, percentage of elongation, yield strength, and the ultimate strength as a function of thickness reduction are experimentally examined. The experimental results show that with increment of thickness reduction, the yield strength, ultimate strength, surface hardness, and crystal refining increase, and on the other hand, it has adverse effect on diameter growth, geometrical accuracy, surface roughness, and percentage elongation of spun tube. [ABSTRACT FROM AUTHOR]