| Improve the cooling capacity of post-rolling cooling equipment,make full use of "water is the cheapest alloying element",reduce the amount of alloying elements,play the post-rolling cooling process on the structural control of the phase transformation process of steel materials,reduce costs and increase efficiency,has become the current heat The main direction of technical transformation and equipment upgrade of continuous rolling process.Based on the new ultra-rapid cooling system retrofit project of Shagang’s 1700mm hot-rolled strip production line,this paper studies the development and implementation of ultra-rapid cooling control system and builds a high-precision hot-rolled strip cold rolling based on ultra-rapid cooling technology system.The main research contents include:super-fast cooling device process layout,seamless connection technology of ultra-fast cooling and laminar cooling system,calculation model of post-rolling cooling heat transfer,ultra-fast cooling system control strategy,ultra-rapid cooling basic automation control system,and alloy steel reduction process research.(1)Through the analysis of the ultra-rapid cooling device and the process conditions and transformation requirements of Shagang’s 1700mm strip steel production line,the ultra-rapid cooling process layout transformation plan and performance requirements are proposed;according to the application requirements,the ultra-rapid cold and laminar flow after rolling The connection mode of the cooling control system was studied,and the communication mode between the control information of the system and the parallel operation strategy between the control systems were established.For the requirements of temperature precision control,the ultra-fast cooling mode,laminar flow mode and enhanced cooling were determined.Mode,as well as a variety of flexible cooling modes for four cooling modes of quenching mode.(2)Based on the analysis of the cooling process,based on the principle of thermal energy transfer,the basic model of cooling heat transfer after strip rolling,the mathematical model of air-cooling heat transfer and the mathematical model of water-cooling heat transfer are established,taking into account the nonlinearity and time-varying characteristics of temperature changes.The various forms of thermal energy exchange cannot be accurately measured and calculated.In the paper,the mathematical model of heat transfer process is equivalent by adjusting the correction of the blackness coefficient.Based on this,the temperature calculation mathematics is established.The model,and further based on the actual application,using the regression model and other methods,established the air-cooled heat transfer coefficient model and the water-cooled heat transfer coefficient model.(3)In order to meet different specifications,different steel grades and different mechanical properties,and the requirements of the product for coiling temperature,the post-rolling cooling system needs to have various control strategies.According to the characteristics of the ultra-fast cooling system,the post-rolling cooling control system is divided into five parts:pre-set calculation,dynamic correction setting calculation,speed feedforward control,feedback control and self-learning calculation.Through the analysis of water pump,valve and pipeline characteristics and water supply requirements,the closed-loop constant-pressure water supply control strategy of the open-loop-cooling phase of the inverter speed-increasing phase and the open-loop preset-flow closed-loop control strategy of the flow regulating valve were developed.In the process of the water supply pressure,the ultra-fast cold water supply flow-pressure decoupling control strategy was developed.In order to eliminate the influence of UFCT control and measurement accuracy on CT control accuracy,the UFCT and CT decoupling control strategy was developed.According to the requirements of different process requirements for ultra-fast cooling calculation strategy,an ultra-fast cold temperature precision control strategy with calculation mode and index mode was developed.(4)Based on field application requirements and control strategies,an ultra-rapid cooling basic automation control system was developed.The paper elaborates on the ultra-fast cooling system Siemens S7-400 system,pump station Siemens S7-400 system,rolling line ABB AC450,and HMI configuration software data communication structure and communication mode;combined with control requirements and equipment performance characteristics,designed The basic automation PLC control program structure and the control mode and operation mode of the main equipment;combined with the system requirements,developed the sample number calculation function,data acquisition function,and alarm functions;using the Siemens configuration software,developed the basic automation and process automation HMI screen.(5)After the design of the ultra-rapid cooling system is applied to the site,combined with the equipment characteristics,cooling capacity and process requirements of the ultra-rapid cooling system,the implementation content,process flow and debugging scheme of the ultra-rapid cooling alloy reduction are established;Metallographic organization and mechanical properties analysis were carried out.Statistics and analysis were carried out on the different specifications of batch production,tensile strength,yield strength,impact toughness,and distribution of elongation properties after fracture.The analysis structure showed that after the transformation,The ultra-fast cooling system runs stably,and the reduction effect meets the requirements of upgrading and efficiency. |
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