管材径压胀形装置开发及试验研究

Design and Experimental Research on Tube Hydroforming Device in Radial Crushing

相对常规的液压成形,径压胀形具有一些独特的优点.开发了一套管材径压胀形装置,在其上开展将圆形截面管材径压胀形成三角形截面试件的试验研究,分析管端约束方式、成形液压力及摩擦力等对成形管件的截面轮廓形状、壁厚分布、破裂位置、材料填充性、管件失效形式的影响.研究结果表明,随着液压力的增大,材料模具填充性会越好,但截面形状对称性及壁厚分布均匀性变差;管端约束力大时,截面轮廓形状的对称性、壁厚分布的均匀性均较好,但材料填充性变差;良好的润滑可以有效改善截面轮廓形状的对称性、壁厚分布的均匀性及材料的填充性,从而推迟管件的破裂;不适当的成形液压力会使管件出现填充不足、压塌或者破裂等缺陷.

Tube hydroforming with radial crushing bears some advantages over the conventional hydroforming,i.e.without radial crushing.A simple and practical experimental tool was designed for the former hydroforming and a series of experiments were conducted on the tool where circular tubes were crushed into workpieces with triangle cross-sections.The influence of the constraint states at the tube ends,hydraulic pressure and the friction states on the bulge tube profile,the wall-thickness distribution,the potential bursting location,the corner-filling ability,failure modes of the bulge tube workpiece was investigated.The results show that a larger internal pressure can increase corner-filling ability while decrease the symmetry of the bulge tube profile and uniformity of wall-thickness distribution;severe constraints at the tube ends make these effects inversed.The results also indicate that the corner-filling ability,the profile symmetry and the wall-thickness uniformity can be improved and the bursting can be delayed by a good lubrication;however,an unreasonable forming pressure might lead to a poor corner-filling ability,premature collapsing or bursting during the forming process.