| Friction welding technology, which is a kind of methods of pollution-free advanced welding with high quality, and high efficiency, has been applied and developed in many countries as a vigorously promoted technology. Therefore, the basic research and applied research of the technology are widely carried out at home and abroad. This article summarizes many researches on friction welding numerical simulation at home and abroad. The gear machine shaft of helicopter landing was as the research material. The finite element numerical simulation model of friction welding was established using the finite element theory and numerical simulation technology. The numerical simulation was carried out by continuously driving friction welding process. The effects of technological parameter on various physical parameters were studied for determining the quality of welding field. We got the appropriate welding process parameters when the method of numerical simulation by computer was used to be instead of a large number of actual welding process tests. The optimal welding process was got, combined with a small amount of welding technology experiment.The friction welding is a thermal cycle process, which has a characteristic of friction heat, deformation at high temperature and the continuous cooling. Based on the analysis of heat conduction and plastic mechanics and the related theory, the mathematical models of temperature field and stress strain field were established with a continuously driving friction welding process.At metal plastic forming process, the factors of the size of the workpiece shape, variable thermal physical parameters and friction coefficients were considered, combined with large deformation-thermal viscoplastic theory. The element calculation models of thermodynamic coupling finite and two-dimensional axisymmetric were established at the friction welding process of high strength alloy steel, using the rigid-plastic finite element method and finite element software ABAQUS.By using the model, the temperature field with stress and strain and the axial shortening amount was to calculate at the high strength steel of35Ni4Cr2MoA in the process of continuously driving friction welding. The calculation results in view of the three stages of welding are analyzed, through the relevant experiment to verify the practicability of the model. The numerical simulation of flow law of metal and expansion and formation of plastic zone of welding joint are studied by using the finite element models. We found that the ring high temperature zone is first in outer diameter, and then at the inner diameter, finally on the friction surface. The width of the plastic zone of high temperature at outside diameter is larger than that at the middle area. The effects of the key technical parameters of the friction welding quality (rotate speed and friction pressure) were calculated and analyzed on Influence law of the friction torque and speed of deformation and weld temperature field. Suitable range of stable friction torque and speed range of drive friction welding are fit for35Ni4Cr2MoA. It is conclusion that the appropriate range of friction and deformation velocity was coincided with the range of appropriate friction torque.The effects of the welding process parameters on amount of the axial shortening were calculated and analyzed. The wilding Joint shapes were calculated and compared under different friction pressure and time. We analyzed the effects of the friction pressure and time on coupling temperature field for providing basic research of the friction welding.According to the influence law of welding process parameters on friction welding process, the orthogonal experimental program for high strength steel of35Ni4Cr2MoA was made for welding test. The welding joint was analyzed through joint microstructure and mechanical properties test. There is obviously influence of friction pressure and upset pressure on impact toughness. Through comprehensive analysis, it is concluded that friction welding technology parameters were derived the optimization continuously. |
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