| Metal flow lines have an important impact on the structural strength and service life of products.However,traditional forming processes such as casting and welding for inner ring-ribbed shells are difficult to ensure that the flow lines at the ribs are free of defect distribution,leading to the inability of products to meet the requirements of bearing capacity and reliability.Extrusion forming technology can ensure continuous and uniform rib streamline distribution along the shape,and improve product mechanical properties and load carrying capacity.Traditional metal streamline research pays more attention to reducing streamline defects and only conducts qualitative analysis.However,there is a lack of quantitative analysis for streamline defects.Currently,China urgently needs to transform the high-end manufacturing industry,focus on research on digital intelligent manufacturing,transform the traditional empirical process development model into a digital scientific development model supported by data and scientific research,improve the actual production conversion rate of material molding research,and achieve cost reduction and efficiency increase in product development.More research on artificial intelligence combined with material science is needed.In this paper,a single inner ring-rib shell made of 7A04 aluminum alloy and its extrusion process were designed,and a 2D finite element model was established.The evolution of metal flow lines and the formation mechanism of flow line defects during the extrusion process of inner ring ribs were analyzed.The effects of rib filling methods,blank structure,and rib structure on the metal flow lines were discussed.A quantitative analysis model for flow line eddy current defects was defined.Combined with the simulated shear strength of inner ring ribs,the influence trend of different parameters on eddy current defects and simulated shear strength was obtained.Compared with upsetting extrusion,radial extrusion increased the degree of eddy current and decreased the shear strength;The height to width ratio of the outer diameter model blank increases,the degree of eddy current decreases,and the simulated shear strength increases.When the aspect ratio of the inner diameter model blank increases from 1.5to 2.5,the degree of eddy current increases and the shear strength decreases;When the aspect ratio increases to 3.5,the eddy current disappears and the streamline is randomly distributed,resulting in a significant decrease in the simulated shear strength;With the increase of the aspect ratio of the equal-width model reinforcement,the degree of eddy current increases,and the shear strength decreases.As the height to width ratio of the reinforcement in the contour model increases,the degree of eddy current increases,and the shear strength decreases.The comparison shows that the improvement of eddy current defects in a single variable model contributes to improving shear strength.The 50 sets of finite element simulation results based on the orthogonal test method are used to learn the relationship between the filling method of the rib,the blank structure,the rib structure and the shear strength through the machine learning method,and the results of the shear strength of the inner ring rib are previewed.The streamline bending degree is added to the eigenvalues to optimize the prediction model.The mean squared errors of the two models over 10 predictions were 0.104 and 0.047,respectively,with the latter reducing by 45%.It proves that the streamline bending degree can be referred to the process design.Among them,the change of shear strength has the highest numerical correlation with the bending degree of the streamline of the rib,followed by the structural parameters of the billet,which is relatively insensitive to the filling method of the rib and the structure of the rib.Through such a method,the calculation efficiency can be improved,and the shear strength of the inner ring reinforcement under given conditions can be predicted quickly and accurately.On this basis,this method can also be extended and applied to the research of other forming processes.Using the blank structure as a variable,the upsetting extrusion process and the rib structure with a rib height of 60 mm and a rib width of 10 mm were used to extrude aluminum alloy inner ring rib components.The overall size and surface quality of the components were good,and the inner ring rib parts were filled fully,verifying the feasibility of the extrusion forming scheme.For the outer diameter model of the blank,the aspect ratio is increased from1.5 to 3.5,and the shear strength is increased by 20%.The height to width ratio of the inner diameter model of the blank was increased from 1.5 to 3.5,and the shear strength decreased by 20%,consistent with the trend of the simulation results.The shear strength test verifies the accuracy of the influence trend of the blank structure on the simulated shear strength and the referential nature of the simulated shear strength.The distribution law of macro flow lines in key parts is the same as that of simulated metal flow lines,verifying the accuracy of finite element simulation and the referential value of simulated metal flow lines and quantitative analysis of metal flow line defects. |
