正四角筒深絞り性に及ぼす材料硬化度と工具形状の相乗効果 : 最適n値と素板形状の検討

概要

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The square shell deep-drawability of pure aluminum is studied systematically. Square blanks with various n-values and h_<uni> blanks with a low n-value are used in the experiments. The h_<uni> blanks are determined by a slip line field method, and give drawn cups with uniform heights. For square blanks, the limiting drawing ratio (LDR) decreases markedly in the following cases. (1) Punch corners are sharp in a higher n-value, (2) A punch is nearly cylindrical in a lower n-value. The maximum LDR is obtained from the appropriate selection of an n-value and punch shape. These facts are explained from drawing force, fracture force and the fractured cups which are classified according to the initiation and propagation of the cracks of the cups. When an n-value is very low, the LDR of the h_<uni> blanks is higher than that of the square blanks for each shape of punches, and much higher, in particular, in the nearly cylindrical shapes. In the use of punches with those shapes, wall breakage in the square blanks does not occur in the h_<uni> blanks.
1993-04-25