| "Develop infinity products with limited billets" has been applied to many iron and steel works. There are many difficulties during the process of producing broad wing plate steel, such as different standards of products, complication of pass shape and hard description of the law about deformation in the box passes and metal flows. So it is very important to study the parameters of the pass and techniques for the spread of the wing plate steel.With the aid of commercial finite element analysis code ANSYS/LS-DYNA, this paper simulated the former three rolling process of wing plate steel in a box pass. Every simulation in this paper is 3-D DEM (Dynamic Explicit Method) coupled elastic-plastic analysis. After establishing the FEM model, the selection of material, the determination of element types and the meshing, deciding the initial and boundary conditions, the simulation etc, the variety laws of rolled billet spread and the distribution of strain and stress field affected by some pass and technique parameters were received, and the forced-spread function of the waist was discussed. This paper provides examples for the simulation of the special shaped steel rolling process by DEM. At the same time, the current pass and technique parameters were optimized, the optimized results indicate that it satisfies the manufacture of the exceed 220mm wing plate steel. The paper has some conclusions as follows:(1) Three rolling processes were simulated, the first one is the process of rolling the square billet in a box pass whose waist is bowing and large pitch, the second is the process of rolling the billet whose waist is bowing and large pitch in a alike pass, and the third is the process of rolling the billet whose waist is bowing and large pitch in a box pass whose waist is bowing and smallpitch. The difficulty of the billet biting in SEM (Static Implicit Method) was solved, the simulating results are almost in good agreement with the practice ones. It indicates that explicit dynamics finite element method can be effectively applied in the simulation of the billet rolling process with different shapes and the research on the optimization of the pass.(2) The waist obliquity of the K10 pass, i.e. the spread increases with the increase of the obliquity was discovered.(3) The variety law of rolled billet spread affected by the waist height and waist width of the K10 and K9 pass, i.e. the spread increases with the increase of the waist width and waist height was discovered. The relation between the spread and the waist width and waist height was regressed and the regressed equation was received. The deformation of work piece and stress field together with strain field of cross section of the work piece in rolling area were analyzed.(4) The variety laws of rolled billet spread affected by the friction coefficient were studied. When the friction coefficient varied, the billet spread changed accordingly, but it changed slightly.(5) The variety law of rolled billet spread affected by the arc radius of the K8 pass was studied. When the arc radius varied, the billet spread changed accordingly, and it changed slightly.(6) The effects of the waist obliquity, the waist width, the waist height and some other factors on the rolled billet are different, in the condition of the simulation in this paper, the waist width of the pass is the most principal influential factor, next is waist width and the waist obliquity of the pass, the friction influence is slight. The parameters of the pass and techniques for manufacturing exceed 220mm wing plate steel were decided.(7) The industry examination of the first pass cogging of rolling was carried out in the same conditions with the simulation, and the waist obliquity is 45° and 55° in each examination. The industry examinations of the second and the third pass cogging of rolling were carried out too. The numerical simulation results are almost in goodagreements with the industry examinations.
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