控制厚度分布的变摩擦正反向超塑成形

为研究摩擦力在超塑成形中对工件厚度分布的影响规律,以正反向超塑成形侧壁厚度均匀的TC4深筒形件为背景,采用MARC有限元数值模拟分析了预成形模和终成形模的表面摩擦系数在正反向超塑成形时对成形件壁厚分布的影响.结果表明:合理地增大预成形模的表面摩擦力能显著增加预成形的局部减薄作用,对于提高零件最终壁厚分布均匀性有利.同时,终成形模摩擦力的减小,可以使板料趋于整体变形,壁厚分布趋于均匀.根据数值模拟结果进行了变摩擦正反向超塑成形试验,制得了厚度分布在1.50～1.78mm范围内的航天用TC4钛合金深筒形件,比普通正反向超塑成形件厚度分布(1.18～2.24mm)有了很大改善.

Friction changing of direct-reverse superplastic forming to control the thickness distribution

In order to study the influence of friction on the thickness distribution of workpiece in superplastic forming,based on a TC4 deep cylinder with uniform side wall thickness achieved by direct-reverse superplastic forming,the influence of surface friction of preforming die and final forming die on thickness distribution was analyzed with MSC.MARC.Results show that increasing the friction coefficient of preforming die can efficiently reduce the thickness of the regions which need to be thinned,resulting in the final uniform thickness distribution along the component.Decreasing the friction coefficient of forming die can make the sheet tend to be integral formation,also resulting in uniform thickness distribution.According to the simulation results,the experiment on friction changing of direct-reverse superplastic forming was performed.The aerospace TC4 deep cylinder with uniform thickness of 1.50-1.78 mm was fabricated successfully.Compared to the thickness distribution of 1.18-2.24 mm of common direct-reverse superplastic forming,the thickness of friction changing is more uniform.