VIZ-STEEL – installation of flatness measurement systems

At the VIZ-STEEL plant in Yekaterinburg, which is part of the NLMK Group, installation work was completed in March 2019 on the project equipping the 1200-1 and 1200-2 cold rolling lines with four strip flatness measurement systems, capable of automated flatness control and data recording during the cold rolling of transformer steel strips.

The project was carried out by the company UVB TECHNIK s.r.o. (Czech Republic) with the subcontractor JSC „JE“ Mashprom.

Both modernized rolling mills 1200-1 and 1200-2 are single-purpose 20-roller mills of the ŠKODA Plzeň brand, designed for cold rolling of metal strips with front and rear tensioning in reverse mode.

Dimensions of the rolled strip:

• maximum input thickness – 0,85 mm;
• minimum output thickness – 0,10 mm;
• width – 600-1050 mm,
• maximum outer coil diameter – 1800 mm
• maximum coil weight- 16500 kg.

Rolling Mill Specifications:

• total stroke of the belt on the winder – 20-180 kN,
• maximum rolling speed – 10,0 m / s,
• length of the cylinder – 1200 mm

Flatness, i.e., straightness on the surface of the strip, is an important characteristic of transformer steel, which affects the quality of applying the electrical insulating coating for subsequent redistribution. In the past, rolling mills did not have the ability to control this parameter, which resulted in the risk of finished products having geometric defects.

A key solution to this problem was the use of a next-generation system for measuring flatness during rolling. Shapemetery STM-1200 records tensile differences across the strip width during the rolling process. The processed information is sent to the control panel of the rolling line. Using this data, the operator adjusts the pressure of the rolling stand segments.

Measuring the flatness of rolled strip allows:

1. Monitor the flatness of cold-rolled strips in real time by the operators;
2. Increase the speed and simplify the setup of the rolling mill in the initial stage of rolling;
3. Improve the accuracy of controlling strip flatness parameters during stable rolling operation;
4. Storing data on the flatness of cold-rolled strips will allow further analysis and optimization of cold rolling conditions.

Flatness measurement systems are based on measuring the tension distribution across the width of the strip for flatness measurement – STM-1200 meters from UVB TECHNIK s.r.o. provide continuous measurement of strip flatness and total strip tension created by the winding rolls in the range of 20 to 180 kN. The accuracy of flatness measurement corresponds to a double standard deviation 2σ (95.4%): ± 2 I-Unit (± 20 μm / m).

The implementation of an automated flatness measurement system will allow VIZ-Steel to significantly increase the proportion of finished products of quality 1 and flatness class 1 in the strips produced.

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