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Multi-point forming (Multi-point forming, abbreviated MPF) is a new way of sheet metal forming the basic principle is to mold the whole into a series of regularly spaced discrete basic body, relying on the basic body of the ball head plate envelope surface to achieve a three-dimensional shape. Compared with the traditional mold forming technology, eliminating the need for a large number of multi-point forming mold design, manufacturing and commissioning time and shorten the development cycle of new products, reduce production costs. Currently, the technology has been in front of high-speed trains, ships outer plate, vehicle cover, urban sculpture pieces and many other fields has been widely used. In this way the basic body shape is loaded subject, because the basic body in sheet metal applied concentration, forming parts defects may appear on the indentation. By placing between the workpiece and the basic elastic pad, the use of large deformation produced by the elastic pad, filling the gap between the basic body, can become concentrated loads distributed loads, thus significantly increasing the load bearing area of ??the workpiece, the indentation suppressed. However, not only affects the thickness of the elastic pad indentation inhibitory effect, and the precision of the molded parts has a great impact, forming the desired results to be obtained, must be reasonably selected elastic pad. As computer applications as well as the maturity of nonlinear finite element method, numerical simulation of sheet metal forming technology has been greatly developed. Currently, the technology to optimize the mold design, predict forming defects such applications more widely. In multi-point plate forming process, because the basic state of contact between the body and the plate changing, and complex loading conditions, the application of dynamic explicit finite element algorithm has obvious advantages. Therefore, this paper based on the dynamic explicit finite element LS-DYNA software, from the finite element model, the choice of material model, boundary conditions determine other aspects of the multi-point forming process was simulated, systematic study of the multi-point indentation forming process defects and suppression method, main contents and conclusions are as follows: In a multi-point forming process, a certain radius of curvature different surfaces, either steel or aluminum, cylindrical or spherical surface, because the basic body and board material contact area is small, the contact pressure, there will produce indentation on the forming quality to a certain extent; through the thickness of the elastic pad with different shapes for different multi-point forming process simulation to study the elastic pad on dimpling effect, the results show that by indentation elastic pad technology to eliminate the effect is obvious, when the elastic pad is thinner on the indentation no significant inhibition, along with its thickness increases, the indentation has been significantly inhibition, when the elastic pad thickness reaches a certain value, the indentation can be completely eliminated; using an elastic member forming the shape of the pad is compared to the target shape errors occur, the primitive matrix must be established when the forming surface to be corrected. First, the numerical simulation method to calculate the full sheet after forming elastic pad deformation and the deformation of elastic cushion to determine the basic tone body shape, to form a new envelope, in the use of the newly formed multi-point die on the workpiece multi-point forming, you will get a more precise shaping part, these results on the application of multi-point forming technology with a reference value and significance.
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