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为了提高锥形件超塑成形效率,提出了叠层超塑成形工艺及高温进出炉成形方案,并采用正反向超塑成形方法以提高壁厚分布均匀性。通过对超塑成形过程自由胀形阶段与贴模成形阶段进行的力学解析,得到了最佳等效应变速率条件下的气压加载曲线。以此为基础,对单层正向成形、单层正反向成形及双层正反向成形进行了920℃超塑成形实验研究。结果表明,正反向成形可显著改善锥形件壁厚均匀性。在双层正反向成形条件下,锥形件最大截面圆度为0.05 mm,最小壁厚为1.01 mm,型面尺寸及壁厚分布均满足使用要求,下层零件的壁厚均匀性较差。叠层超塑成形工艺及900℃装出炉方案可行有效,可使锥形件超塑成形效率提高1倍以上。
In order to improve the superplastic forming efficiency of the conical member, a laminated superplastic forming process and a high temperature in-and-out furnace forming scheme are proposed, and a forward and reverse superplastic forming method is adopted to improve the uniformity of the wall thickness distribution. Through the mechanical analysis of the stage of free bulging and the stage of plastic forming of the superplastic forming process, the air pressure loading curve under the optimal equivalent strain rate was obtained. Based on this, the experimental study of superplastic forming at 920 ℃ was carried out on single-layer forward forming, single-layer forward and backward forming and double-layer forward and backward forming. The results show that the positive and negative forming can significantly improve the conical wall thickness uniformity. Under the conditions of double-layer positive and negative forming, the maximum circularity of the conical part is 0.05 mm and the minimum wall thickness is 1.01 mm. The size and thickness distribution of the profile meet the requirements of use, and the thickness uniformity of the lower part is poor. The laminated superplastic forming process and the 900 ° C loading and unloading furnace are feasible and effective, which can increase the superplastic forming efficiency of conical parts more than one time.