聚氨酯橡胶硬度对薄壁三通管内高压成形的影响

Influence of polyurethane rubber hardness on internal high pressure forming for thin-walled T-tube

以外径为Φ24 mm、壁厚为1.5 mm、长度为120 mm的H85黄铜管为例,以壁厚增减量不超过30%为合格品作为前提,以生成最大支管胀形高度的橡胶硬度为最佳参数,结合胀形实验和有限元仿真共同分析了60~90 HA范围内7种不同硬度的聚氨酯橡胶棒对等径三通管成形质量的影响。研究结果表明:随着橡胶硬度的逐渐增大,支管胀形高度增大,壁厚差减小,壁厚分布越均匀;当橡胶硬度大于85 HA时,支管顶部减薄率大于30%;当橡胶硬度小于70 HA时,直管端部和底部增厚率大于30%。此次研究中,橡胶硬度为85 HA时,成形三通管的最大壁厚为1.899 mm、最小壁厚为1.06 mm、支管胀形高度为17.132 mm,成形效果最佳。管坯整体壁厚分布规律为支管顶部减薄、直管端部增厚,且增厚区明显大于减薄区。

For H85 brass tube with outer diameter of Φ24 mm, wall thickness of 1.5 mm and length of 120 mm, taking the increase or decrease amount of wall thickness without exceeding 30% as a qualified product and the rubber hardness generating the maximum branch tube bulging height as the best parameter, combining the bulging experiment and finite element simulation, the influences of the polyurethane rubber rods with seven different hardnesses in the range of 60-90 HA on the forming quality of equal-diameter T-tube were analyzed. The research results show that with the gradual increasing of rubber hardness, the bulging height of branch tube increases, the wall thickness difference decreases, and wall thickness is more evenly distributed. When the rubber hardness is greater than 85 HA, the thinning rate at the top of branch tube is greater than 30%, and when the rubber hardness is less than 70 HA, the thickening rates at the end and bottom of straight tube are greater than 30%. Furthermore, when the rubber hardness is 85 HA in this study, the forming effect is the best with the maximum wall thickness of 1.899 mm, the minimum wall thickness of 1.06 mm and the bulging height for branch tube of 17.132 mm for the T-tube formed. In addition, the distribution law of the overall wall thickness for tube billet is that the top of branch tube is thinned and the end of straight tube is thickened, and the thickened area is obviously larger than the thinned area.