投审稿入口

基于CNN+BiGRU神经网络连退平整后带钢宽度预测

Width prediction of strip steel after continuous annealing and temper rolling based on CNN+BiGRU neural network

  • 摘要: 连退平整后带钢宽度直接影响其生产成本。为了解连退平整后带钢宽度的变化情况, 建立了一个基于卷积神经网络结合双向门控循环单元(CNN+BiGRU)神经网络连退平整后带钢宽度预测模型。首先, 分析了连退平整过程中宽度的变化机理, 在连退过程中, 带钢宽度主要受温度、张力和速度等因素影响; 在平整过程中, 则主要受轧制压力和前后张力等参数影响。其次, 进行了数据特征选择及预处理, 根据连退过程的颈缩量预测模型及采利科夫公式, 筛选出炉内不同工艺段的温度、张力以及平整段的17个工艺参数, 作为模型输入特征; 为保证预测准确性, 采用Min-Max归一化法对数据进行归一化处理, 之后使用Tukey's fences方法对数据降噪。接着, 建立了CNN与BiGRU结合的神经网络结构, 该结构包含2个卷积层和2个门控循环单元(GRU)层, 卷积过程采用ReLU作为激活函数, 2个GRU各包含4个门控单元并进行串联输出。然后, 进行了模型的训练与结果验证, 通过对比单独CNN、单独GRU、CNN+GRU、随机森林(RandomForest)以及轻量梯度提升机(LightGBM)等模型性能, 发现CNN+BiGRU结构在综合性能上优于其他模型。训练中CNN+BiGRU模型的决定系数R2为0.983 9、平均绝对误差EMA为3.492 66、均方根误差ERMS为11.616 7、平均绝对百分比误差EMAP为0.29%。对训练后的模型进行各特征参数的沙普利加性解释(SHAP)值计算, 发现轧制力是影响宽度的最重要特征, 其SHAP值接近7, 远高于其他参数, 均热段张力和炉内张力分别为第2和第3重要特征。这为宽度调节提供了以平整控制进行粗调、以连退过程进行精调的方案。最后, 将训练好的模型应用于现场, 并开发出自学习功能以实现模型的定期更新。通过收集不同钢种的预测精度, 发现预测值可控制在±3 mm以内。对比不同钢种的宽度变化发现, 对于强度较高的钢种, 应以连退过程作为宽度调节的主要手段; 对于强度较低的钢种, 则以平整调节为主要手段。研究结果实现了连退平整后带钢宽度的精准预测, 为宽度调节提供了有效方案, 具有较好的应用价值。

     

    Abstract: The width of strip steel after continuous annealing and leveling directly affects production costs. To understand the variation in strip width after continuous annealing and leveling, a prediction model based on a convolutional neural network combined with a bidirectional gated recurrent unit (CNN+BiGRU) neural network was developed. First, the mechanism of width variation during the continuous annealing and leveling process was analyzed. During continuous annealing, the strip width is primarily influenced by factors such as temperature, tension, and speed, whereas during leveling, it is mainly affected by parameters such as rolling pressure and front/back tension. Subsequently, data feature selection and preprocessing were conducted. Based on the necking prediction model for the continuous annealing process and the Zaretsky formula, 17 parameters, including temperatures and tensions in different process sections of the furnace as well as process parameters in the leveling section, were selected as input features for the model. To ensure prediction accuracy, Min-Max normalization was applied to standardize the data, followed by data denoising using Tukey's fences method. Next, a CNN and BiGRU combined neural network structure was constructed, comprising two convolutional layers and two gated recurrent unit (GRU) layers. The ReLU activation function was used in the convolutional process, with each of the two GRU layers containing four gated units and connected in series for output. The model was then trained and validated. By comparing the performance of standalone CNN, standalone GRU, CNN+GRU, Random Forest, and LightGBM models, the CNN+BiGRU structure was found to outperform the others in overall performance. During training, the CNN+BiGRU model achieved a coefficient of determination R2 of 0.983 9, with mean absolute error (EMA) of 3.492 66, root mean square error (ERMS) of 11.616 7, and mean absolute percentage error (EMAP) of 0.29%. After training, the Shapley additive explanations (SHAP) values of each feature parameter were calculated. It was found that rolling pressure is the most important feature influencing width, with a SHAP value close to 7, significantly higher than other parameters. The tensions in the soaking section and within the furnace ranked second and third in importance, respectively. This finding provides a width adjustment strategy where leveling control serves as the coarse adjustment, and the continuous annealing process is used for fine-tuning. Finally, the trained model was applied in a real production environment, and a self-learning function was developed to enable periodic model updates. By collecting the prediction accuracy of different steel grades, it is found that the predicted value can be controlled within ±3 mm. Comparing width variations across different steel grades revealed that for higher-strength steel grades, the continuous annealing process should be the primary means of width adjustment, whereas for lower-strength steel grades, leveling adjustments should take precedence. The research results realize the accurate prediction of strip width after continuous annealing and leveling, which provides an effective scheme for width adjustment and has good application value.

     

/

返回文章
返回