管模间隙对21-6-9高强不锈钢管数控绕弯成形质量的影响

基于ABAQUS/Explicit有限元平台,建立了21-6-9高强不锈钢管数控绕弯成形过程的三维弹塑性有限元模型,并验证了模型的可靠性.利用该模型研究了不同管模间隙对管材数控绕弯过程壁厚变化及截面畸变的影响规律.结果表明:增加管材-芯棒间隙、管材-防皱块间隙或减小管材-压块间隙、管材-弯曲模间隙可以减小壁厚减薄率;减小管材-芯棒间隙或增加管材-压块间隙可以减小壁厚增厚率,而其他管模间隙对壁厚增厚率的影响不显著;减小管材-压块间隙、管材-弯曲模间隙或增加管材-防皱块间隙可以减小截面畸变率,而增加管材-芯棒间隙,截面畸变率呈现先减小后增加的变化规律;获得了规格为Φ15.88 mm×t0.84 mm×R47.64 mm的21-6-9高强不锈钢弯管件较佳的管模间隙值. 

Effect of Clearance Between Tube and Dies on Forming Quality in NC Bending Process of High Strength 21-6-9 Stainless Steel Tube

Based on the platform of ABAQUS/Explicit, a 3D elastic plastic finite element model of high strength 21-6-9 stainless steel tube NC bending process was established, and its reliability was validated. Then, the influence laws of different clearances between tube and dies on wall thickness change and cross section distortion were obtained by the model. The results show that increasing tube-mandrel clearance, tube-wiper die clearance or decreasing tube-pressure die clearance, tube-bending die clearance can reduce wall thinning ratio; reducing tube-mandrel clearance or increasing tube-pressure die clearance can decrease wall thickening ratio, while other clearances between tube and dies hardly have an effect on wall thickening ratio; reducing tube-pressure die clearance, tube-bending die clearance or increasing tube-wiper die clearance can make the cross section distortion of tube weaken, while increasing tube-mandrel clearance, the cross section distortion firstly reduces then increases. And the optimal clearances values among dies and tube are obtained for Φ15.88 mm×t0.84 mm×R47.64 mm high strength 21-6-9 stainless steel bent tube. The results may provide a theoretical basis for parameters selection and die design during tube NC bending precision forming process.