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针对铝合金中厚板室温下反拉深易破裂问题,提出了温热反拉深成形方法。以4.5 mm厚的5A06铝合金板材为研究对象,分别进行室温、280和360°C下的反拉深实验和数值模拟研究,分析温度、压边力和压边间隙对反拉深变形过程中破裂和起皱缺陷的影响规律。采用Abaqus/Explicit软件对温热反拉成形进行了热力耦合数值模拟,得到反拉深变形过程中应力及温度的分布。结果表明:弯曲效应导致凹模内圆角与直壁区过渡处在厚度方向存在径向应力梯度,当温度升高至280°C时,该应力梯度由室温下505 MPa降为72 MPa,减小了85.7%。提高成形温度能明显降低径向应力梯度,从而避免了破裂的发生。当温度高于280°C时,外侧凹模圆角处的切向应力增大,该处起皱缺陷易于发生。当温度升高至360°C时,材料由于过度软化而发生破裂。采用1.5t(t=4.5 mm)压边间隙时,能消除高温成形过程中破裂和起皱缺陷,并成功成形420 mm深的筒形件。
Aiming at the problem of anti-pull and easy-break of aluminum alloy plate at room temperature, a hot anti-drawing method is proposed. Taking 4.5 mm thick 5A06 aluminum alloy plate as the research object, the anti-drawing experiments and numerical simulations at room temperature, 280 and 360 ° C were carried out respectively. The influence of temperature, blank holder force and blank clearance on the anti-drawing process Rupture and wrinkling defects of the law. Abaqus / Explicit software was used to simulate the thermomechanical anti-pull forming by means of thermomechanical coupling. The distribution of stress and temperature during anti-drawing deformation was obtained. The results show that the bending effect leads to the radial stress gradient in the thickness direction at the transition between the fillet and the straight wall. When the temperature rises to 280 ° C, the stress gradient decreases from 505 MPa to 72 MPa at room temperature Small 85.7%. Increasing the forming temperature can significantly reduce the radial stress gradient, thus avoiding the occurrence of rupture. When the temperature is above 280 ° C, the tangential stress at the fillet of the outer die increases, where wrinkling defects tend to occur. When the temperature rises to 360 ° C, the material cracks due to over-softening. With a 1.5t (t = 4.5 mm) blank holder clearance, rupture and creasing defects during high temperature forming are eliminated and a 420 mm deep cylindrical part is successfully formed.