Moscow Polytechnic University, Moscow, Russia

S. A. Tipalin, Cand. Eng., Prof., Dept. of Materials Forming and Additive Technologies, e-mail: tsa_mami@mail.ru
Yu. G. Kalpin, Dr. Eng., Prof., Dept. of Materials Forming and Additive Technologies
N. A. Kupriyanova, Graduate Student, Dept. of Materials Forming and Additive Technologies

In the process of cutting sheet material, pre-processing and transportation of sheet blanks, their curvature is possible. To recovering their shape, the editing operation by compression is used at a pressure lower than the yield strength of the semi-finished product material. The process of editing a bimetallic billet with small curvature from layers differing in their physical properties is considered, at the next assumptions: we neglect of material hardening, the Bauschinger effect, friction of the semi-finished product on the stamp’s surface due to the smallness of plastic deformations during editing; we suppose, that the stress and deformation’s neutral layers at straightening of the curved billet coincide with each other and there are no initial residual stresses in the layers. As a result of the stress-strain state analysis, the mathematical dependencies were obtained that allow us to calculate the deformations and stresses in various layers of the semifinished product at compression by flat strikers, as well as were obtained the detail’s residual curvature after the operation and the necessary pressure forces, which are necessary to select the appropriate equipment. The analysis of picture changes in the stress distribution pattern in the process of increasing the tool pressure on the billet is performed, and the calculation features for finding the appearing deformation are mathematically presented. The character of changing in the bending moment from the applied compressive pressure between the flat strikers on the bimetallic billet at different initial bending radii is graphically presented. As an example, the process of editing the “tank cap” detail, used in the chemical industry and consisted from bimetal (of the layers of 45 and 65G steels), is considered. In this material, the thickness ratio of the soft and hard layers is 4:1, and the total thickness of bimetallic billet equals 20 mm. During the calculations, it was found that when creating a pressure close to the yield strength of the soft layer, the detail’s buckling decreases from 3.5 mm to 2.4 mm.

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