Thermomechanical analysis of a piercing mandrel for the production of seamless steel tubes

Abstract

The heat transfer of a piercing mandrel for the production of seamless steel tubes is analysed, and the consequent thermal stresses are examined. The process of tube manufacture is described, and the problem to be addressed is identified. The analysis is based on a mathematical model with the essential boundary conditions, heat transfer coefficients in this case. For the solution of this mathematical model, the finite element method (FEM) is employed given the geometry of the tip of the mandrel and its initial and boundary conditions. The commercial software of the FEM employed makes it possible to find the temperature fields of the mandrel tip, as well as the temperature histories of some points of interest, which agree with thermographic readings. Evaluation of the material, based on the temperature field, shows that creep effects are important in wearing out of the mandrel tip and affect the number of tubes manufactured. Additionally, the methodology developed herein makes it possible to estimate the lifespan of the mandrel tip during the tube piercing stage, and to propose improvements for cooling of the mandrel tip.