Equipment of the design of PJSC NKMZ for heat treatment of sheet

Abstract

It is shown that improving the design of the roller-type machine towards providing the quenching and interrupted cooling modes (RQM) in the sheet rolling technology allows to expand the technological capabilities and manageability of the process. This provides decreased equipment weight and reduced time to reach the design performance. The feature of the process is that during the movement of the processed rolled stock, the RQM is divided into intensive and low-intensive cooling zones. The maximum cooling rate (over 120 deg/s) is achieved in the intensive cooling zone using the slit-type collector with the jet torch directed to the surface of the rolled stock at an angle of no more than 250 and the two-chamber collectors with flat-flame nozzles with the jet torch directed to the surface of the rolled stock at an angle of no more than 600. Using dual-chamber collectors significantly increased the manageability of the heat treatment process since the water consumption variation range has increased by at least 1.9 times. It is shown that the cooling system design in conjunction with the automated water supply control system allows to optimally distribute flows along the length and width of the sheet, and also establish favorable water supply ratios in the top and bottom of each cooling section. Due to the proposed technical solutions, the average cooling rate in intensive cooling zones extends throughout the section and amounts to at least 60°C/s in quenching of sheets with the thickness of up to 16 mm, and to a depth of 5-6 mm in quenching of 30 mm thick sheets. Flatness deviation of 8-50 mm thick sheets after quenching is fully compliant with the requirements of normal flatness in accordance with GOST 19903 and EN 10029.