Influence of Cone Semi-Angle on the Formability Limitation of the Hole-Flanging Process

A hole-flanging process on a circular plate with a predeter-mined smaller hole in its centre has been analysed using the incremental updated Lagrangian of the elasto-plastic finite-element code. An extended r-minimum technique was employed such that each incremental step size is determined not only by the yielding of an element Gaussian point, but also by the change in the boundary conditions along the tool–metal interface. Coulomb’s friction law was adopted to solve the frictional effect of the tool–metal interface. This work aims to investigate

the influence of the cone semi-angle of various truncated conical punches on the limitation of formability in the hole-flanging process. Experimental results, using a low-carbon (BA _ CO2) sheet plate with a thickness of 1.18 mm, have been obtained and compared with the corresponding theoretical results. It was found that the limitation of formability during the forming process is not affected by the cone semi-angle of the truncated conical punch but the finish shape and maximum punch load are dependent on the cone semi-angle.