直接法によるアルミニウム板の自由成形

板材の放電成形に関する研究 (第1報)

抄録

The fundamental forming properties and the behaviour are experimentally studied on the free forming of circular aluminum sheets (A1100-O, 1/2H) clamped at their periphery and formed by the direct method usually acting the impulsive pressure on the blank. The pressure distributions obtained are generally highest at the centre and lower for the periphery. In this forming, the relations among the polar deflection h of blanks formed, the mean forming velocity vh during forming at the pole, the die diamter d (35-70 mm) and the material thickness t₀ (0.6-1.0 mm) are approximately found as follows : h is proportional to d^0.5 and t₀^-1, and vh is to d^-0.5 and t₀^-0.5 at each charged energy W_c, and material, and the ratio h/vh (total forming time τ _f) is constant at each d, t₀ and material independently to h or W_c. Therefore in this method, vh cannot be controlled for forming at h and is more increased as larger deformation resistance of blanks for forming as the same h. The strain inclinations from the centre to the periphery of blanks formed are smaller in O than in 1/2H, and larger than those of the hydrostatical method in O, but smaller in 1/2H at the same h.