Abstract: The stretch reducing process is divided into the rolling deformation of the stand and the remeshing generation between the stands taking the tension between the adjacent stands as the boundary conditions by means of the group modeling principle in order to study the metal deformation of hot rolling seamless tube in the process of stretch reducing. A higher-order fitting function is established to accurately describe the roll pass surface. A friction element model is applied to simulate the contact friction. Furthermore, the nonlinear equations are solved with a secant modulus method. On the basis of above theories, a elastic-plastic finite element model of stretch reducing process is developed, which is used to establish a FE model and to simulate the metal deformation of the stretch reducing unit of some factory. Through comparison, the shape of the product section simulated is similar to that of the actual rolled product, which is a slight hexagon shape. Moreover, the variation of wall thickness is the same. The geometry simulated is agreed very well with that of the measured. These show that the developed elastic-plastic finite element model for tube stretch reducing process met the requirements of engineering calculation, which provided an effective research method for predicting the section shape and finishing size accuracy.

Key words: Finite element method, Geometric size, Prediction model, Seamless tube, Secant modulus method