Research On The Method Of Roll Bending Process Of Complicated Section Extrusion

The bending process of complicated extrusion is widely applied in the production. The advantages of roll bending are simple equipment, easy operation, wide application and so on. The process and rules of complicated section extrusion of the roll bending are analyzed detailedly by using the theoretical and the finite element analysis.Based on the principle of roll bending and the different characteristic of roll bending process, the complicated extrusion and the roll bending technology are both researched on the basis. According to the shape of the extrusion section, the extrusion is divided into the symmetric and asymmetric extrusion, then open, closed and open-closed extrusion. The open and symmetric extrusion is studied in the study of this thesis. Bending processing methods are divided based on the axis of extrusion, the condition of the webs bending and the change of the radius. The three–dimensional, harvested edge and unchanged radius processing methods is studied in the study of this thesis.The section of inertia moment, neutral layer, bending section coefficient and wrest resistant section coefficient are seen as the geometry parameters of complicated extrusion. The theoretical calculation of the complicated section of inertia moment is difficult and uncertainly correct. The solution of the principal moment is applied in the two-dimensional software. Compared and referred the solution of neutral layer of other bending style, the calculation formula of the stress and strain neutral layer is got.The material parameters of complicated parameters are assured. The stress-strain relationship of the material is the double line and work hardening curve is the index style. The processing parameters of roll bending include into the displacement and speed of the center roller.Based on the principle and characteristic of roll bending and according to the Elastic-Plastic Principle, the force model of the extrusion roll bending is established, and according to the true stress-strain relationship, the stress-strain model of the extrusion roll bending. The minimum radius of curvature is calculated, because of the condition of single tensile instability.The basic algorithm constitutive relation boundary conditions and spring back based on the elastic-plastic theory are summarized. The elastic-plastic finite element model of the complicated extrusion roll bending is established by the finite element method. The residual stress of bending parts is analyzed. The stress and strain distribution regularity is studied and the stress and strain of the extrusion and section variety because of the different displacement and speed of the center roller. The change of the angle of the extrusion section and the condition of the distortion of the extrusion section are studied. The distribution of residual strain based on the bending extrusion springback is studied on the two parts of the extrusion length and web. The springback value between the theoretical and the simulation is compared. The research results are helpful in effectively advancing the process quality and precision of roll bending...