Influence of lubricant on limit drawing ratio in cup-drawing process: A stabilization matrices scheme

摘要

The four-node quadrilateral element incorporating stabilization matrices is applied to analyze the prediction of the limit drawing ratio of cylindrical cup-drawing for different lubricants. Two typical commercial lubricants, zinc stearate lubricant and press oil lubricant, were used in the experiments. Experiments of the drawing process were performed in a hydraulic sheet-forming machine. In all simulations, the theoretical curve of punch load versus punch travel, thickness distribution along a cup generatrix, and deformation history showed good agreement with the experimental results. The generalized r{sub}(min) strategy, employed to determine punch travel in each step, was proven adequate to trace the penetration and separation phenomena between the node and tool boundary in the entire cup-drawing process. The use of the zinc stearate lubricant resulted in smaller punch load and higher limit drawing ratio than the press oil lubricant did. Hence, the effect of the zinc stearate lubricant was better than the press oil lubricant in this study.