Finite element analysis of tube flaring process with a conical tool

The extended r(min) technique is incorporated into an incrementally updated Lagrangian formulation (ULF) of an elasto-plastic finite element computer code in order to handle contact boundary conditions to analyse the axisymmetric tube flaring process with a conical tool. A modified Coulomb friction law was adopted to calculate the influence of the friction coefficient on the tube flaring process. The effects of size and mechanical properties of tubes, as well as lubricants and tool semi-angle on flaring load were studied. It was found that good lubrication is effective in reducing flaring load. An optimum tool semi-angle (tool load is lower) in flaring is determined by frictional and bending activity at the tool inlet. In addition, the forming behaviour of the tube end is investigated to understand whether outward curling takes place and how much influence the tool semi-angle and tube size (initial thickness/initial mean diameter of tube) have on outward curling mode.