Influence of the tool clearance in the cylindrical cup-drawing process

Abstract

This paper applies the incremental updated Lagrangian formulation (ULF) of elasto-plastic finite element computer code, incorporating the extended r min technique to handle the contacted boundary condition, to analyze tha axisymmetric cylindrical cup-drawing process. Coulomb's friction law was adopted to solve the friction effect of the tool-metal interface. Two lubricants, zinc stearate and press oil, were used in the experiments. The material was low-carbon steel (BA-DDQ), with a thickness of 1.2 mm. The main feature of this work is to investigate the influence of the clearance between the die and the punch on the formability in the cup-drawing process. Tool clearances of 1.04t, 1.15t, and 1.22t were tested in the experiments. From comparison of results, such as the punch load, the thickness distribution and the limiting drawing ratio (LDR), for the simulation and experiment, the clearance of 1.15t secured the largest LDR value, whilst the clearance of 1.04t generated a greater ironing effect in the process. The good agreement of the experimental and theoretical results not only validates the correctness of the computer simulation, but also can supply a useful reference for the design of tools in the industry.