Simplified three-dimensional simulation of rotary piercing of seamless pipe by rigid-plastic finite-element method

摘要

A method for simulating three-dimensional deformation in rotary piercing of pipes from roundbars with skewed rolls in a realistic computing time is proposed on the basis of the rigid-plasticfinite-element method using generalised plane-strain modelling. In this method, the rotary piercing isapproximated as a roll forging process, and the elongation of the workpiece in the rolling direction iskept uniform in the cross-section. The effect of the twisting shear deformation is included in thegeneralised plane-strain modelling to improve the accuracy of the calculated results. The calculatedshapes of the deformed workpiece are in good agreement with the experimental ones for plasticineworkpieces. In addition, the occurrence of a central crack in the rotary piercing is predicted from thecalculated history of the hydrostatic stress and equivalent strain by means of the criterion of ductilefracture.