Study On Numerical Simulation Of Lateral Bend Forming Technology

The cold bend steel take cold and hot rolling strip steel as raw material, through the processing method such as the drawing, stamping, fold bending and roll bending machine, all kinds of section shape profile is formed on normal temperature. In the application of cold bend steel, the steel with certain radian is applied extensively in many fields, such as building, automobile manufacture, mining mechanical manufacture, agricultural and light industry machinery manufacture, which plays an important role in the development of national economy.The literal bending is a new processing method of bending section steel. Its main idea is adjusting twin-roll into a certain angle, causing the blank to have inhomogeneous deformation in thickness direction. The metal in thickness direction is forced to flow along the longitudinal direction. As the pressing volume is different in width direction, the extension length between two edge is different, causing the long side edge to have in-plane bending to the short side. Then blank is bended. Relative to the traditional bending method, the lateral bend forming has saved lots of time and capital for die design, die manufacture and debugging. In addition, the lateral bend forming is static pressure deformation process, which can reduce noise and improve working condition. Meanwhile, the lateral bend forming belong to continuous forming, which can realize mechanization and automation.With computer application and maturity of nonlinear finite element, the numerical simulation technology is developed quickly. In the process of lateral bend forming, the pressing volume, the width, thickness, shape and material of blank are the main parameters, which influence the curvature radius and forming force of formed parts greatly. So a dynamic explicit finite element software LS-DYNA is introduced to simulate the lateral bend forming process, including the establishment of finite element model, the choice of material model, the establishment of boundary conditions and the treatment of contact friction and so on. The main contents and results are as follows:1) The research on the finite element model of section steel and hourglass control in lateral bend forming.In the process of lateral bend forming, the bending of formed parts is mainly through the deformation in thickness direction. The deformation of section steel in thickness and length direction is relatively great. Therefore solid element SOLID 164 is especially suited to analysis. The element has eight nodes and has property of stress stiffening and large deformation, can be used in all kinds of field. The element use single point integration in default, which is beneficial to large deformation. But single point integration can easily cause hourglass effect, and result in a status that is stabilization in mathematics but can not be realized in physics. The element with hourglass effect usually hasn't stiffness and the mesh present zigzag. In the simulation, the hourglass effect is controlled through modifying keyword (the hourglass control type and hourglass coefficient), and the forming effect is good.2) The numerical simulation of curvature radius for formed parts. Through changing the pressing volume, the width, thickness and material ofsection steel, the curvature radius of formed parts is studied. The results show as follows. Firstly, with the increment of the pressing volume, the curvature radius of formed parts is increased without other parameter changed, and the difference of curvature radius for formed part is decreased. Secondly, with the increment of thickness, the curvature radius of formed parts is increased. Besides this, with the decrement of pressing volume, the change of curvature radius is relatively remarkable. Third, the curvature radius of formed parts increased with the growth of width. The last one, the higher yield limit of the material is, the bigger curvature radius is. The numerical results provide significant guidance to control curvature IV radius of formed parts.3) The numerical simulation of the forming force in lateral bend forming.The forming force is mostly affected by the pressing volume, the thickness, width, material and shape of section steel. Through the simulation of the forming force with different kinds of section steel, the results are as follows. First, in the thickness and width of angel steel invariable situation, with the increment of the pressing volume, the forming force is increased. Second, with the increment of thickness, the forming force is decreased without other parameter changed. Third, the higher yield limit of the material and the wider section steel are, the bigger forming force is. The last one, with the same thickness and width of blank, the forming force of angle steel is bigger than sheet metal. Through the simulation of forming force, it makes good help for choosing forming equipment and developing forming equipment's potential.