升速轧制对热轧带钢层流冷却出口温度的影响

采用传热学原理建立了层流冷却温度有限差分模型,并用现场实测数据对水冷换热系数进行了自适应修正.对德盛1 150 mm热轧带钢层流冷却过程的温度变化进行了数值模拟,建立了一套层流冷却温度仿真系统,分析和研究升速轧制时带钢在层流冷却中温度变化的趋势.结果表明,层冷出口温度受带钢的速度影响较大,在升速过程中,如果不采用集管动态喷水调节,带钢温度出现前低后高的现象,并且随着加速度的增加带钢前后温差越大.以此为依据,现场过程自动化系统L₂级硬件采用过程服务器,基础自动化系统L₁级硬件采用西门子PLC,L₂级和L₁级软件分别在C++和Step7V5.4下编程实现,并采用了带钢头尾宏跟踪和过程自动化系统采用带钢样本微跟踪的控制策略,对处于变速及高速运动中的带钢沿长度方向逐点实施控制,用动态调节的冷却集管系统来保证在速度变化期间带钢层流冷却出口温度的稳定性.

Influence of Accelerating Rolling on the Laminar Cooling Exit Temperature in Hot Strip Mill

The principle of heat transfer is adopted for the strip temperature finite difference model and the heat transfer coefficient of water is amended based on measured data.The temperature change is numerically simulated in the process of Desheng 1 150 mm hot strip laminar cooling.The simulation system is established to study the change trend of laminar cooling temperature in accelerating rolling.Results show that the coil temperature is significantly influenced by the speed of strip,the strip temperature gradually increases from the front to the back,and the temperature deviation increases with the acceleration without dynamic regulation of the cooling pipe system during acceleration.Based on the conclusions,the L2-level hardware is a process server,the L1-level hardware is Siemens PLC for the online control system and the softwares of L1 and L2 are programmed by C++ and Step7V54.The successful control strategy online tracking of head and tail of the hot strip in the basic automation and the elements micro-tracking in process automation are introduced,variable motion of the strip is controlled along the length point by point,and dynamic regulation of the cooling pipe system is used to ensure the stability of coiling temperature during the change in speed.