Numerical Simulation And Experiment Study On Mechanic Expanding Of Large-diameter Spiral Pipe End

In order to satisfy the urgent requirement of large diameter line pipe with high quality, a study was made on the process of spiral pipe end expanding by means of FEM numerical simulation and experiment. Based on large deformation elasto-plasticity theory, U.L. method, planar strain and axisymmetric FEM model, the FEM nume馽al simulation research on the mechanical expanding process was carried out, through the powerfrl, modem, general-purpose nonlinear analysis finite element program, MARC. According to numerical simulation results, there is an evident feature of partial deformation in the pipe being expanded. According to different deformation feature, the process of pipe end expanding is divided into three stages梤ounding, expanding and unloading. Based on roundness error and wall thickness reduction, the die structure parameters and expanding process parameter were optimized. The relationship between expanding ratio and shape quality of pipe expanded was given, the relationship between expanding dies and shape quality of pipe expanded was disclosed also and the reasonable range of those parameters were given The test pieces include ten spiral pipes, with diameter of 406mm, wall thickness of 7.3mm and length of 500mm.The experiment was done on YD-31 5 hydraulic press. The curve of expanding force vs. expanding stroke and the curve of expanding force vs. expanding ratio were given. To ensure shape quality, the practical formula of expanding stroke was given.