考虑材料参数变化的高强钛管数控弯曲回弹行为研究

目的研究钛管数控弯曲回弹角、回弹半径的变化规律,揭示回弹角和回弹半径变化特征的形成机制。方法基于有限元软件平台,建立考虑收缩应变比-弹性模量变化的Ti-3Al-2.5V钛管数控弯曲成形及回弹全过程的有限元模型。结果回弹角随弯曲角和相对弯曲半径的增加而增加;回弹半径在弯曲角小于30°时,随弯曲角的增加而先变化很小,后显著增加;弯曲角大于30°时,回弹半径随弯曲角的增加而逐渐减小。回弹半径随相对弯曲半径的增加而增加。弯曲角越大,应力分布区域越大,回弹变形越大;相对弯曲半径越大,弯管中处于弹性变形的区域占总变形区域的比例较大,回弹变形越大。结论考虑两参数变化时对回弹角和回弹半径的变化趋势无显著影响,但获得的回弹角和回弹半径均大于忽略两参数变化时的值;考虑收缩应变比-弹性模量变化时,弯曲变形区沿外脊线的拉应力大于忽略两参数变化时的拉应力,卸载回弹时,管材发生大的弹性恢复,表现为回弹角和回弹半径的增加。

Springback Behavior of High Strength Titanium Tube in Numerical Control Bending Considering Variation of Material Parameters

The paper aims to study the variation law of springback angle and radius of titanium tube in numerical control bending, and to reveal the formation mechanism of the variation characteristics of springback angle and radius. Based on the finite element software platform, a finite element model for the numerical control bending forming and springback of Ti-3Al-2.5V titanium tube was established, considering the variation in the contractile strain ratio and elasticity modulus. The springback angle increased with the increase of bending angle and relative bending radius. When the bending angle was less than 30°, the springback radius first changed little with the increase of bending angle, and then increased significantly. When the bending angle was greater than 30°, the springback radius decreased gradually with the increase of bending angle. The springback radius increased with the increase of the relative bending radius. The larger the bending angle, the larger the stress distribution area, and the larger the springback deformation. The larger the relative bending radius, the larger the proportion of the elastic deformation area to the total deformation area in the bending tube, and the larger the springback deformation. The change trend of the two parameters has no significant effects on springback angle and radius, but the springback angle and radius obtained are larger than the value when ignoring the change of the two parameters; when considering the change of contractile strain ratio and elasticity modulus, the tensile stress along the outer ridge of the bending deformation zone is greater than the tensile stress when ignoring the change of two parameters; and when the springback is unloaded, the tube has a large elastic recovery, which is manifested by an increase in the springback angle and radius.