基于最大m值法的超塑性胀形最佳压力加载方式  

Best pressure loading mode of superplastic bulging based on maximum m value method

作　　者：徐雪峰[1] 李轩颖 陈清根[1] 林兵兵 李玲玲 赵爽 徐龙 

机构地区：[1]南昌航空大学航空制造工程学院,南昌330063 [2]中航工业洪都航空工业集团公司,南昌330024

出　　处：《塑性工程学报》2016年第5期69-76,共8页Journal of Plasticity Engineering

基　　金：国家自然科学基金资助项目(51405219);江西省青年科学基金资助项目(20132BAB216022)

摘　　要：采用最大m值法拉伸试验获得了随应变变化的最佳应变速率关系曲线,以控制钣金超塑胀形气压加载,使得板料变形集中部位的实际等效应变速率等于变化的最佳应变速率,而非等于恒应变速率拉伸获得的最佳应变速率定值,从而获得比目前基于恒应变速率超塑胀性更优良的成形性能。以2A12铝合金为研究对象,采用最大m值法拉伸实验获得其最佳应变速率关系曲线,以控制超塑性胀形,并与恒应变速率胀形进行比较;为改善壁厚均匀性,设计了正反胀形模具与工艺,并结合有限元软件MSC.Marc 2010,对整流罩进行单向和正反向胀形模拟,并进行实验验证。结果表明,对于单向胀形,基于最大m值法的简化应变速率胀形,其成形时间仅为760s,较恒应变速率胀形3 360s大幅缩短,而二者的减薄率分别为70.4%和70.9%,在降低减薄率的同时,极大的提高了胀形效率;基于最大m值法的简化应变速率正反胀形,零件最小壁厚为1.157mm,较基于最大m值法的简化应变速率单向胀形零件的最小壁厚0.887mm有一定程度增加,而不均匀性则由69.97%降为28.9%,有效改善了壁厚均匀性;实验证明,采用最大m值法的胀形件的最小壁厚有所提高,均匀性得到了有效改善,且壁厚分布与模拟结果相吻合。The optimal strain rate curve with strain variation was obtained by tensile experiments by using the maximum mvalue method to control the time-pressure curve in superplastic bulging,which makes the equivalent strain rate of the concentrated deformation area of the plate equal to the change of the optimal strain rate all the time and instead of the constant value through the constant-strain rate tensile experiments,and then gets the better forming property.Taking tensile experiment with the maximum mvalue of 2A12 aluminum alloy as an example,the method of the optimized strain rate bulging was proposed to determine the time-pressure curve in the process of superplastic bulging,and compared with the constant strain rate bulging.To further improve the uniformity of the wall thickness,the die and process of direct-reverse bulging were designed and modeled by using the finite element software MSC.Marc 2010,and the model was verified by the experiments.The results show that：for unidirectional bulging process,the analysis time of the simplified strain rate bulging based on the maximummis only 760 s,which is far shorter than the 3 360 sof the constant strain rate bulging,while the thinning rates are 70.9% and 70.4%,respectively,so the maximum m value method can greatly improve efficiency of the bulging in the case of reducing ratio of thinning.The minimum wall thickness of the part of the simplified strain rate in the direct-reverse bulging based on the maximummis 1.157 mm,greatly thicker than the minimum wall thickness 0.887 mm of the unidirectional bulging based on the maximumm,however,the non-uniform degree of the wall thickness decreases from 69.97% to 28.9%,which effectively improve the wall thickness uniformity.The experiments show that the minimum wall thickness of the fairing increases,the uniformity is effectively improved and the numerical distribution of the wall thickness agrees with the experimental results by using maximum mvalue method.

关 键 词：2A12铝合金 压力加载方法 最大m值法 超塑性胀形 

分 类 号：TG135.3[一般工业技术—材料科学与工程]