双金属复合无缝钢管冷轧成型过程的数值研究

The numerical simulation of bimetallic seamless steel tube cold rolling process

采用非线性有限元法对不锈钢/碳钢双金属复合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成型过程包括稳定轧制阶段和钢管冷轧脱模以后的位移场和应力应变场。计算结果显示,冷轧成型过程的应力分布十分复杂,在环向没有对称性。本文根据计算结果绘制了钢管的径向、环向及轴向应力分布图。在稳定轧制阶段,径向应力在内层钢管内壁,减径量越大,径向应力越小;环向应力在碳钢和不锈钢界面位置和内层不锈钢管的内壁,减径量越大,环向应力越小;轴向应力与减径量的大小成反比关系。采用冷轧成型工艺生产双金属无缝钢管,成品钢管的直径精度较高,壁厚精度低于直径精度。参数研究表明,计算直径接近理论值,受减径量的影响相对较小;计算壁厚与理论值有一定误差,钢管壁厚精度随减径量的增加而降低。对于本文计算的外径为202 mm,壁厚为11 mm的双金属复合管,在减径量为2 mm时的壁厚相对误差仍小于5%。同时,双金属复合管外层碳钢钢管壁厚变化量相对较大而内层不锈钢管的壁厚变化相对较小。论文的研究成果对于双金属复合钢管冷轧成型工艺设计、孔型和轧辊设计具有参考价值。

The numerical simulation of the forming process of bimetallic 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 stress distribution of cold rolling is very complicated and there is no symmetry in the hoop. The dis- tributions of the axial stress, circle stress and radial stress of the steel tube at different areas were drawn. In the stable stage, on the inner surface, the more diameter is reduced, the smaller the radial stress is. On the inter- face and the inner surface, the more diameter is reduced, the smaller the circle stress is, and the axial stress is inversely proportional to the amount the reducing diameter. The wall thickness precision of steel tube after roll- ing is higher than diameter precision. For a bimetallic seamless steel tube with external diameter of cb202 mm and wall thickness of 11 mm, relative error of wall thickness still under 5% when sizing reduction of 2 mm. The numerical calculation results show that the diameter reduction has fewer impacts on diameter precision than wall thickness precision. The results of the research can be applied to the design of both the die and the forming process.