| Aluminum alloy plate is a kind of plate with high specific modulus and specific strength, widely used in mechanical equipment and aerospace industry. Especially in the field of aeronautics and astronautics, faced with mighty competition from titanium alloy, composite materials and other new materials, the aluminum alloy still maintains the competitive advantages owning to its low cost. With the development of science and technology, aluminum alloy plate gradually becomes large-scale, integrated,homogenous-microstructure and high quality, and the demand of aluminum alloy plate is growing in various fields. Snake hot rolling, which is a new rolling technology used for production of thick aluminum alloy plates, obtains many academic attention and there are a lot of relevant research on it. However, most of the study on snake hot rolling focuses on the one-pass snake hot rolling while the study on multi-pass rolling is relatively rare. During real production, multiple pass reductions constitute the whole snake hot rolling process. Therefore, it’s necessary to carry out investigations on the multi-pass snake hot rolling technology so as to explore the method for improving it and provide new ideas for processing technique of thick aluminum alloy plates.7075 aluminum alloy is taken as the research object in this paper, the finite element numerical simulation technique is applied to investigate the modeling technique of one-pass and multi-pass snake hot rolling, and the analysis about the effect of distribution of every pass reduction, asymmetric intensity of temperature field on equivalent stress and equivalent strain along the direction of thick plate thickness is performed as well, which provides the suggestions and reference for the processing technique of multi-pass snake hot rolling.The main results and conclusions obtained in this paper are listed as follows:The bite condition and constitutive model of snake rolling, boundary conditions and other key technologies involved in FEA model are studied. The comparison between simulation results and reference results shows the relative error is within10%, which demonstrates the validity of the model.The effect of pass reduction distribution on equivalent stress and equivalent strain along the thickness direction during multi-pass snake hot rolling is studied.Different with symmetric rolling, the strain curve of snake rolling shows it is asymmetric about the center of thickness, the equivalent strain on the lower layer of plate is obviously larger than that of upper layer because of the larger velocity of the lower roll. Among all the pass reduction distributions, the symmetrically increasing distribution can cause the maximum equivalent strain while the monotonically increasing distribution leads to the minimum.The effect of pass reduction distribution on shear strain of center point during multi-pass snake hot rolling is studied. Among all the pass reduction distributions, the symmetrically decreasing distribution can cause the maximum shear strain while the monotonically increasing distribution leads to the minimum, which means the symmetrically decreasing distribution is more benefit for the deformation of the center of plate so as to thinning the grain size.The equivalent stress distribution curve in multi-pass snake hot rolling is asymmetric that the equivalent stress on the lower layer of plate is obviously larger than that of upper layer because of the larger velocity of the lower roll. Among all the pass reduction distributions, the symmetrically increasing distribution can cause the maximum equivalent stress while the monotonically decreasing distribution leads to the minimum.The effect of asymmetric intensity of temperature field on residual stress and strain during multi-pass snake hot rolling is discussed. The results indicate that the asymmetric intensity of temperature field has certain influence on residual stress and strain of rolling piece, but there is not the positive correlation between them. |
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