摘要
尽管超塑胀形作为一种金属成形方法正日渐受到世界各国的普遍关注，但对超塑约束胀形理论的研究报道却还很少，尤其对胀形过程的有限元模拟研究就更为罕见。针对这种情况，采用大变形刚粘塑性有限元法模拟了轴对称零件向圆筒形凹模内超塑约束胀形的变形过程，着重研究了工具工件之界面摩擦对胀形件厚度分布不均匀性和胀形板料向凹模角部充填性的影响．结果表明，随着摩擦的降低，胀形件的侧向较厚部分能有所减薄，可以改善整个胀形件的厚度均匀性，但当摩擦因子Ａｍ≤０．２（相当于摩擦系数μ≤０．１２）时，胀形件极顶部分的减薄过大；摩擦较小时，胀形板料向凹模角部的充填性较好；在考虑到极点附近厚度适度减薄和胀形板料对凹模角部充填性好的前提下，工艺上应当适当减小摩擦，其最佳状态是μ值约为０．３．为了检验所用刚粘塑性有限元法模拟的可靠性，将计算结果与试验结果作了对比，发现两者相当吻合。
There has been considerable interest in the subject of the superplastic bulging , which isconsidered to be a kind of sliecial metal forming methed. However, up to now, the theoreticalanalysis for the superplastic constrained bulging has only a few research reports. Especially, thefinite element simulation on the constrained bulging can be found much less. In this paper, a rigidviscoplastic finite element method with large deformation is used to simulate the deformationprocess of the superplastic constrained bulging of axisymmetrical circular sheets into cylinder dies.The main purpose of the present work is to study the boundary friction effects between the bulged,sheets and the dies on the inhomogeneity of thickness distribution and the filling ability of the sheetstoward corners of the dies. The simulation results shown that as the friction effect decreases, thethicker parts of the sheets contacting with side-walled dies are thinned , and the inhomogeneity of thewhole bulged sheets is improved. But, when the friction factor 4m≤ 0. 2 (i. e. the frictioncoefficient μ≤0. 12) , the bulged sheets near the polar top of the dies are thinned too much. Inaddition , when the friction factor A. is smaller, the filling ability of the sheets toward the cornerscan be improved. So, considering the two aspects of the above mentioned friction effects, ingeneral , the boundary friction factor should be suitably decreased. The best value is about 0. 3. Inorder to check the reliability of the present rigid viscoplastic finite element method, the calculatedresults are compared with experimental ones. The former is found to be in agreement with thelatter.
出处
《摩擦学学报》
EI
CAS
CSCD
北大核心
1994年第4期320-327,共8页
Tribology
基金
国家自然科学基金
关键词
轴对称件
超塑约束胀形
刚粘塑性
摩擦效应
axisymmetrical circular sheets, superplastic constrained bulging, rigid visco-plasticity , finite element method, friction effect
