Automated Control Systems for Thermal Hardening of Rolled Products in Rolling Mill Train
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ted Control Systems for Thermal Hardening of Rolled Products in Rolling Mill Train Yu. I. Lipunova, *, K. Yu. Eismondta, and E. V. Nekrasovaa aOAO
VNIIMT, Yekaterinburg, 620137 Russia *e-mail: [email protected] Received March 23, 2020
Abstract—This article discusses specific operation features of automated process control systems (APCS) designed for a controlled cooling device of rolled products focused on accelerated cooling and engineering features of equipment. The objectives and structure of two-level APCS have been defined, and control algorithms of the cooling mode have been described for controlled the cooling facility in a rolling mill train. Keywords: automated control system, rolled products, thermal hardening, controlled cooling, rolling mill DOI: 10.3103/S0967091220050071
Thermomechanical treatment in a rolling mill train, which combines rolling with subsequent thermal hardening by controlled accelerated cooling to preset temperature, is sufficiently efficient, since it allows to achieve the required set of service properties of rolled products using a minimum amount of alloying elements. Accelerated cooling immediately after finishing a train of rolling mill is the main method of thermal treatment by means of heat contained in metal [1, 2]. In most cases, this process is controlled by feeding coolant (water jet most often) onto metal surface [3]. Such cooling method allows to provide both the required properties of metal and their homogeneity on the surface of rolled products [4]. Controlled cooling device (CCD) in a rolling mill train allows to perform the following technological procedures: discontinued cooling after rolling, quenching, quenching with self-tempering, accelerated cooling of semi-finished rolled products between roughing and finishing rolling, and others. In order to achieve a steady level of the required mechanical properties during thermal hardening after rolling heating, it is required to accurately provide the final temperature of cooling and temperature rate variation during accelerated cooling of rolled products. The main temperature control parameters of rolled products, that is, intensity and duration of cooling, are determined by water flow rate to section and the conveyance rate of rolled products across the facility. In order to provide the preset cooling mode of rolled products, it is required to coordinate the CCD operation with adjacent systems, in particular with a roll mill stand, roller tables, pinch rolls, as well as continuous data exchange about the thermal treatment procedure, position and current temperature of rolled products, as well as some
others. Therefore, the production process stability in controlled cooling facilities can be provided by an automated control system. In recent years, OAO VNIIMT experts in cooperation with some specialized companies were involved in the design and commissioning of CCD equipped with APCS: —CCD in the plate rolling train 5000 (OAO Severstal’) [5]; —thermal hardening of reinforcing bars in the medium section mill train 350 (OAO S
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