Study of Extension for Forming Limit of Sheet Metal at High Temperature

研制了一台以高温盐浴液体为加压介质的胀形机样机。实验研究了液体温度、材料和板料厚度对液体压力、成形极限、胀形轮廓和应变分布的影响。通过有限元数值模拟，可以更清楚地了解胀形机理。的温度从200 ° C变为450 ° C。测量了不同温度下的液体压力、胀形高度和应变分布。随着液体温度的升高，压力降低。450 ℃时的压力值变为室温时的10%。当鼓包高度为20mm时，不同温度下的鼓包形貌和分布差异不大。当胀形高度较高时，变形主要发生在胀形顶部附近。采用胀形方法可以提高胀形极限。

A prototype bulging machine which was used at high temperature salt bath liquid as pressure substance was made. The efforts for temperature of the liquid, materials and thicknesses of the sheet metal were experimentally examined for the pressure of the liquid, the forming limit, the bulging profiles and the strain distribution. The bulging mechanism could become clear by numerical simulation using finite element method. The temperature of is changed from 200ﾟC to 450ﾟC. The pressure of liquid, the height of bulging and strain distribution were measured at various temperature of the liquid. As the temperature of liquid was higher, the pressure decreases. The pressure value at 450ﾟC became 10% of the value at room temperature. When the bulge height is equal to 20mm, the bulge profiles and distribution made little difference at various temperatures. As the bulging height were higher, the deformation was caused at the vicinity of the bulging top. The bulging limit could be extended by the bulging method.