The “Integration of Steelmaking, Continuous Casting and Rolling” plan integration and scheduling technology, automatic control technology and comprehensive shape control technology have been developed into key common technologies in the production process of hot-rolled wide strip steel, which are important for energy saving, product quality control, and enterprise economy. Increased efficiency is decisive.
The advantages of the integrated new process are highlighted
In the strip steel production process, the steelmaking, continuous casting, and hot rolling processes are particularly closely connected. The matching of logistics and information flow between the three is not only a guarantee for normal production, but also for reducing energy consumption and production costs, and improving product quality. In response to the actual needs of new integrated production technology and energy saving and emission reduction in the three major processes of steelmaking, continuous casting, and hot rolling in the production process of strip steel, the integration of production management organization, business process reengineering, process integration plan optimization and integration plan system research on dispatching system research and development is particularly important
In many years of theoretical research and industrial practice, the industry has proposed a new overall solution for the “Integration of Steelmaking, Continuous Casting and Rolling” for strip steel production, and has developed a complete operating platform and series of technologies for production planning integration and dynamic scheduling systems, mainly including the following several aspects: the overall framework and solutions of the production planning integration and scheduling system. The framework takes order tracking as the core concept and adopts a hierarchical structure design, which is not only suitable for the reorganization of existing production lines, but also for the construction of new production lines. The overall solution includes abstract modeling, mathematical description, definition of functional modules and business processes between modules for the three major processes of refining, casting and rolling. Each functional module can be appropriately tailored, adapted, and reorganized according to the specific requirements of different enterprises to meet the requirements of enterprise personalized design. Through the message integration center and other communication interfaces, seamless connection with the enterprise ERP system and the production control system for refining, casting and rolling can be realized, which not only maintains the independence of the system, but also integrates the entire enterprise information system.
The integrated planning and scheduling model of smelting, casting and rolling suitable for different production processes and the corresponding optimization algorithm. These algorithms mainly include hot rolling CCR batch planning algorithm based on constraint programming, HCR batch planning optimization algorithm based on genetic algorithm, HCR slab warehousing decision optimization algorithm based on improved genetic algorithm, and DHCR batch planning optimization algorithm based on improved ant colony algorithm, Mixed assembly planning optimization algorithm, steelmaking-continuous casting scheduling algorithm based on constraint programming and integrated operation scheduling simulation algorithm, etc., solve the three major process logistics matching and connection problems, provide a basis for the implementation of the integrated plan, and greatly simplify In the process of decision-making, the daily planning time can be shortened from a few hours during manual preparation to 30 minutes.
The three major process control schemes and implementation technologies of dynamic scheduling and strategic dynamic adjustment based on rule-based reasoning. The dynamic scheduling technology based on rule-based reasoning mainly realizes the dynamic connection and matching of the logistics between the casting and rolling mills through the logistics control and dynamic regulation of the connection area, and automatically eliminates the difference in the production rhythm during the multi-casting machine and multi-stream feeding, ensuring the production of DHCR Implementation of the process. The strategic dynamic adjustment technology solves the problem that the production plan must be dynamically adjusted due to the interruption of the production plan caused by equipment failure and process abnormality. The technology solves the problems in production practice through decision support system and simulation system.
The integrated planning integration and scheduling technology is used in the second hot rolling production line of Wuhan Iron and Steel, achieving an average hot charging rate of more than 75%, an average slab entering temperature of more than 650℃, and a maximum daily hot charging rate of 85.23%; used for the 1580 hot stripping Rolling, hot charging rate is greater than 90%, and the average slab entering temperature is greater than 750°C.
Plate shape control technology improves quality and reduces consumption
Plate shape is a very important quality indicator of wide-band steel. If the shape control technology configuration is complete and advanced, the ability of the production line to actively control the strip shape can be increased to meet the shape control requirements under various rolling conditions. The configuration of the comprehensive shape control technology of the wide strip hot rolling mill mainly includes the following contents:
All racks of the roughing and finishing mills adopt variable contact support roll technology to automatically eliminate the “harmful contact zone” between the rolls, convert the low lateral rigidity roll gap into a high lateral rigidity roll gap, and increase the mill’s resistance to shape interference factors , Improve the shape control performance of the rolling mill and reduce the consumption of rolls.
High-efficiency variable crown work roll technology is used in the upstream stands of the finishing mill (such as F1～F4), and the shape adjustment ability of the rolling mill is linearly related to the strip width, which greatly increases the overall shape control ability of the rolling mill At the same time, enhance the ability to control the narrow gauge.
Conventional work rolls are used in the downstream stands, and the wear of the rolls is evened through the reciprocating cycle of the rolls to meet the requirements of free-plan rolling. In order to take into account the shape control in the entire rolling unit, a special variable-stroke conventional work roll shifting strategy is designed. For special products, such as silicon steel, asymmetric work roll technology can also be used in the last frame or the last two frames to achieve the dual functions of shape control and wear control, and effectively control the shape of the strip edge.
The upstream and downstream roll shape configuration strategy that considers the shape control characteristics of hot strip mills adopts a fully functional shape control model that can adapt to flexible roll shape configuration, including a shape setting model at the process control level, a shape self-learning model and The flatness feedback control model of the basic automation level, the crown feedback control model, the roll bending force feed forward control model, the shape and thickness decoupling model and the cooling flatness compensation strategy after rolling realize high-precision automatic flatness control.
The advanced plate shape control function effectively guarantees the shape quality of the product, making the shape control accuracy of the strip steel reach a very high level, and the production line has a strong adaptability to free schedule rolling, and the rolling volume can reach the same width. 70 kilometers, the reverse width jump can reach 300 mm. The realization of free schedule rolling can not only reduce the consumption of rolls and reduce auxiliary production time, but it is also beneficial to increase the hot charging rate and thereby reduce energy consumption.
Automatic control technology improves product accuracy
Automatic control technology has an important influence on the product performance, production efficiency, and yield of hot rolled wide strip steel, and determines the advanced level of the hot strip production line. After years of digestion, absorption and innovation in China, a complete set of hot tandem rolling process models and control modules have been successfully developed and successfully applied to multiple hot tandem rolling production lines such as Wuhan Iron and Steel 1700mm and Chongqing Iron and Steel 1780mm, achieving good control effects. The development and application of automatic control systems have also laid a solid foundation for future technological upgrades and advancements
Automatic control system hardware configuration. In order to meet the requirements of rapid and precise control of hot strip rolling, the configuration of the control system must fully consider the characteristics of hot strip rolling production process and the development trend of automatic control system hardware and software to ensure the advancement, reliability, openness and Easy to maintain.
Advanced control functions. This mainly includes functions such as procedure calculation, AGC subsystem, finishing temperature control, and coiling temperature control. Procedure calculation. Regulation calculations have a decisive influence on the thickness control accuracy of the strip head. According to the characteristics of the production process, the rolling piece needs to be calculated multiple times during the period from the furnace to the coiling completion, including pre-calculation, re-calculation, post-calculation, and model adaptation.
AGC subsystem. The system has developed various AGC control algorithms and combined use strategies, including thickness gauge AGC, monitoring AGC, feedforward AGC, etc. In addition, in order to improve the thickness control accuracy and stabilize the threading and throwing process, a variety of compensation schemes are adopted, such as synchronous control of the cylinders on both sides, servo valve flow compensation, steel biting impact compensation, roll eccentric compensation, etc. The key parameters of AGC are adjusted and optimized using advanced algorithms such as expert systems and neural networks.
Finish rolling temperature control. The finishing temperature control includes two parts: the head finishing temperature control and the full length finishing temperature control. The purpose of the final rolling temperature control of the rolling head is to control the temperature of the rolling head when it leaves the finishing mill within the required range, and to provide good initial conditions for the temperature control of the full-length final rolling. In the pre-set calculation of the finishing rolling, the system calculates the appropriate temperature acceleration according to the predicted temperature change of the full length of the strip at the entrance of the finishing rolling, and controls the fluctuation trend of the temperature of the full length of the strip through the acceleration.
Coiling temperature control. Compared with the traditional statistical regression model, the system uses a temperature forecast model based on the finite difference algorithm. The relationship between the heat transfer boundary conditions, the heat transfer in the thickness direction, the thermal properties of the strip and the temperature drop of the strip can be considered in more detail.
Automatic control technology can help shorten the hot test time, reach production as soon as possible, and improve product accuracy. Moreover, complete control functions, high-precision quality control models and preset model process parameters are also conducive to the automatic expansion of production line specifications, including High-grade non-oriented silicon steel, high-grade pipeline steel, advanced high-strength steel and other varieties can achieve stable production, and a major breakthrough has been achieved in the production of thin-gauge stainless steel.