无缝钢管冷轧成型过程的数值模拟

Numerical simulation of seamless steel tube under cold rolling

本文采用非线性有限元法对无缝钢管的冷轧成型过程进行了数值模拟,得到了钢管在整个冷轧过程包括稳定轧制和钢管冷轧脱模后各个位置的位移场和应力应变场.根据数值计算结果绘制了钢管的轴向、环向及径向应力分布,并根据应力分布特点解释了钢管在冷轧过程中,不同的减径量如何影响成品管直径和壁厚精度的机理.数值计算结果表明:不同减径量情况下,稳定轧制阶段减径量的大小对钢管内外壁径向应力影响较小;对于环向应力,减径量越大,钢管外壁环向拉应力越大,而内壁环向压应力则越来越小;轴向应力同样与减径量的大小成反比例关系.残余应力沿圆周方向有明显不同,较小的轴向拉应力和较大的径向拉应力有利于轧制后轴向变形,较小的减径量有利于接近理论壁厚,但冷轧脱模后钢管直径大于理论直径.研究成果对于无缝钢管冷轧成型工艺设计以和轧辊孔型设计具有参考价值.

In this paper, the numerical simulation of the forming process of seamless steel tube formed with cold rolling process was conducted by nonlinear finite element method. The distributions of the displacement, stress and strain of the whole forming process of the steel tube were obtained. According to the numerical calculation results, the distributions of the axial stress, circle stress and radial stress and three - dimensional stress states of the steel tube at different areas were drawn. The mechanism that the reduction of tube diameter influences the precision of both the diameter and wall thickness of the tube was explained according to the stress distributions. The numerical calculation resuhs show that in the stable rolling stage, for the radial stress, the amount of the reduction of the tube has few impacts on radial stress of both inner and outer tube sur- face. For the hoop stress, the more diameter reduction of tube, the hoop tensile stress of the outer surface of tube will be higher, but the hoop compressive stress of the inner surface of tube will be lower. The axial stress also has the same trend which is inversely proportional to the amount the diameter reduction. Variation of residual stress appears in the circumferen- tial direction, the small axial tensile stress and large radial tensile stress are good for the deformation of tube under roiling. Small diameter reduction is good for the tube thickness approaching to that in theory, but the diameter of tube will large than that in theory after rolling process. The results of the research can be applied to the design of both the hole shape of roll and the forming process.