基于热-力耦合的粗轧过程头部弯曲规律

Head bending law during rough rolling process based on thermo-mechanical coupling

头部弯曲是热轧粗轧过程中常见的缺陷,生产过程中严重影响板带产品质量和轧制稳定性。实际生产中由于轧件上下表面温降和轧制工艺参数的不对称,轧件在经过粗轧后容易出现头部弯曲现象。为实现头部弯曲规律的模型化描述,基于传热学理论及刚塑性变分原理,利用ABAQUS软件建立了粗轧轧制过程热力耦合有限元模型。系统分析了在轧制线不对中的情况下轧件温度分布对头部弯曲的影响,及在轧制线不对中且轧件上下表面存在温差的情况下辊速比、压下率和入口厚度对头部弯曲的影响,最后通过拟合得到了各工艺因素对轧件头部弯曲的影响规律,实现了轧件头部弯曲的预测。仿真研究结果表明,随着上下表面温差的增加,轧件下扣逐渐加重;辊速比、压下率和入口厚度均对头部弯曲有影响,且相互耦合;随着辊速比的增加,弯曲角度逐渐变大,轧件头部由扣转翘;随着厚度的增加,轧件头部逐渐趋于平直;随着压下率的增加,弯曲角度在一定范围内波动;现场实测数据表明,基于所建立的预测模型,预测角度偏差在±5°之内的比例达到90.10%,验证了所建立模型的有效性,实现了头部弯曲的准确预测,能够为粗轧过程工艺优化提供参考。

Head bending is a common defect in the process of hot rough rolling process.It affects the quality and rolling stability of strip products during the production process seriously.In actual production,due to the asymmetry of the temperature drop on the upper and lower surfaces of the rolled piece and the rolling process parameters,the rolled piece is prone to head bending after rough rolling.In order to realize the modeling description of the head bending law,based on the heat transfer theory and the rigid-plastic variational principle,the thermo-mechanical coupling finite element model is established by ABAQUS.In the case of misalignment of the rolling line,the effect of the temperature distribution of the rolled piece on the head bending,and the effect of roll speed ratio,reduction rate and entry thickness on the head bending under the condition of misalignment of rolling line and temperature difference between upper and lower surfaces of rolled piece were systematically analyzed.Finally,the effect of various process factors on the head bending was obtained by fitting,and the prediction of the head bending was realized.The simulation results show that with the increase of the temperature difference between the upper and lower surfaces,the downward bending of the rolled piece gradually increases;the roll speed ratio,the reduction rate and the entry thickness all have an effect on the head bending,and are coupled with each other;with the increase of the roll speed ratio,the bending angle gradually becomes larger,and the head the rolled piece changes from the downward bending to upward bending;with the increase of the thickness,the head of the rolled piece gradually tends to be straight;with the increase of the reduction rate,the bending angle fluctuates within a certain range.The field measurement data shows that based on the established prediction model,the proportion of the predicted angle deviation within±5°is 90.10%,which verifies the validity of the established model and achieves accurate prediction of head bending.It can provide a reference for the process optimization of the rough rolling process.