Research On Dynamic Heat Transfer Mechanism And Device Structure Design Of 1580 Hot Rolling Segmented Cooling

The precise control of hot rolling strip crown has always been a pressing problem in the industry.It is necessary to introduce hot rolling segmented cooling technology into the strip crown control system to solve the problems of uneven roll temperature distribution and large strip transverse thickness deviation.The1580 hot rolling production line is taken as the research object,designing a segmented cooling device to deeply studied the influence of different structural parameters on cooling uniformity.At the same time,the dynamic heat transfer mechanism of the hot rolling segmented cooling is explored by finite element simulation.It provides an improvement scheme for the technology upgrading of the roll coolant system in hot rolling production line,and finally realizes the local precise control of the shape and crown.Firstly,a step-type(continuous transition type)hot rolling segmented cooling device was innovatively designed,which could realize the segmented quantitative control of the thermal profile.Based on the mathematical model,the concept of equivalent heat transfer coefficient is introduced,and the flow field simulation model of hot rolling segmented cooling device is established.The calculation accuracy of the simulation model was verified by the flow test results.According to the different structural characteristics of hot rolling segmented cooling device,the flow field characteristics are simulated,considering the unity of the internal streamline and the uniformity of the spray speed at the outlet of nozzle,so as to realize the uniform cooling of the roll horizontal positions.Secondly,the thermal-mechanical coupling model of hot rolling segmented cooling system was established.Considering the influence of complex boundary conditions on heat transfer characteristics of rolls,the heat transfer coefficient curves of different modes are used as link to realize the indirect coupling with flow field simulation model,so as to analyze the dynamic heat transfer mechanism.By comparing the calculated results of model with industrial test data,the coincidence between the simulated values of temperature field and plate convexity reaches 92% and 95% respectively,which verify the feasibility of the simulation method and the accuracy of the simulation results.According to the model: The adjustable range of transverse temperature difference extends to 2.4℃-18.7℃;The adjustable range of roll thermal crown extends to 36.4μm-84.8μm;Strip C40 crown control range is 26.8-40.5μm;Finally,the mathematical model and simulation are combined with measured value to obtain the variation laws of roll thermal effect and influences on plate convexity under different segmented cooling modes.After the application of segmented cooling system,the transverse temperature difference of roll surface is reduced by 5.5℃-10.8℃,Strip qualified rate increased by 16%.The research results show that the segmented cooling system of hot rolling not only can reduce the transverse temperature difference of roll surface,but also control the crown of the finished strip to improve the qualified rate of the product,which provides the theoretical basis and application reference for the application of intelligent control system with segmented cooling in hot rolling.