材料期刊网

使用低压气吹超塑性金属片形成复杂轮廓已广泛应用于航空及汽车工业中，其普遍定义为超塑成形法(SPF)。超塑成形的优点包括低成本及模具便宜易制并且成品具有低残留应力。另一方面，超塑成形的产品易造成厚度分布不均匀。然而，也有降低此缺点的技术。采用超塑性 AA5083板材以低压气吹使 V 型板材成形至深凹不平的 V 型槽。先使用机械辅助热弯曲使板材成 V 型后再进行气吹。在热弯曲阶段，如果弯曲的深度超过一定水平将导致挫曲。挫曲和几何轮廓将影响所形成产品厚度分布以及皱褶发生位置，但是将获得更好的厚度分布。皱褶可经由规划以达到更好的均匀厚度分布，但皱褶位置需要产生于半成品的修剪线外。因此，控制热弯曲阶段以获得一个合适的预成形板材得以气吹成形是至关重要的。

Employing low pressurized gas for shaping superplastic metal sheets into complex contours has long been adopted in the aero/auto industries and it is commonly recognized as superplastic forming (SPF). The most undesired feature of SPF would be an uneven thickness distribution in the final formed part. However, there are techniques that lessen this disadvantage. Low pressurized gas was used to make a V-shaped trough containing deep uneven concavities using superplastic AA5083. The auxiliary yet influential procedure of mechanically hot bending the flat sheet into a V-shape precedes the gas-forming process. In this first quick hot-bending operation, buckling will occur if the depth of bending exceeds a certain level. The degree of buckling and associated contours will affect the thickness distribution as well as the wrinkling location in the gas-formed product. A better thickness distribution is obtainable at the cost of wrinkle formation. Wrinkling can be purposely arranged to achieve better uniform thickness distribution, but it needs to be located outside the trim line of the gas-formed semi-product. Therefore, it is critical to manipulate the hot bending procedure to yield a suitable pre-form allowing a successful sequential gas-forming process.