The CCM mould tube is a core equipment of the casting machine production. For a long time, a thin plate plant has installed an eddy current sensor on the fixed side of the CCM mould tube to detect the molten steel level. Its measured value is an important control parameter for the casting machine production. In this way, once the eddy current sensor fails or fluctuates, the measurement signal will be interrupted, which will affect the production rhythm of the casting machine and even cause a stop-casting accident. The accident lasted for more than 500 minutes, and the steel billet in the fan-shaped section was scrapped. The purpose of improving the copper mould tube liquid level detection system is to prevent such accidents from happening.
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“In extreme environments, it is even more difficult to keep the eddy current sensor in a stable working state.” Li Xin, the regional technical supervisor of the smelting department of the thin plate plant, led the reporter to the scene and saw that the molten steel was being injected into the CCM mould tube, and the immersion nozzle was roasted red, and it seemed to be integrated with the molten steel from a distance. The eddy current sensors installed on both sides of the tube were also subjected to high-temperature tests. To ensure the stable working state of the sensor, the thin plate plant changed the practice of only detecting on the fixed side in the past through the self-improvement of employees, and installed an eddy current sensor on the loose side of the CCM mould tube as a hot standby sensor, realizing the “fixed side + loose side” double-side liquid level detection. At the same time, the project modified the eddy current sensor control program of the casting machine, added a special program for online monitoring, correction and fault determination; upgraded the casting machine monitoring system, set the eddy current sensor status information and switch alarm prompts, and realized real-time feedback on the status of eddy current sensors, immersion nozzles, stoppers and other equipment.
“This practice is the first in the national steel industry.” Li Xin said the uniqueness of the improved new system. The “tailor-made” PLC system can realize automatic compensation and correction to ensure that the values of the two eddy current sensors remain basically consistent. According to the numerical comparison results, the system can automatically determine the fault and quickly switch the sensor to ensure the stable and smooth production of the casting machine. According to statistics, after the implementation of the “CCM Mould Tube Liquid Level Detection System Improvement” project, it has “turned danger into safety” many times, played a positive role in reducing accident time and quality scrapping, increasing production, etc., and achieved an annual benefit of more than 1.2 million yuan.
