Steel intelligence and digital technology in cold rolling mills

1. Hot dip galvanizing intelligent workshop in cold rolling mill

Walking into the hot-dip galvanizing smart workshop of a cold rolling mill in China, the production line here is smart enough to run automatically without turning on the lights, making it a veritable ‘black light factory’. When you turn on the lights, you will find that the driving vehicle above the workshop is shuttling back and forth holding cold-rolled steel coils about 2 meters in diameter. Driving usually requires workers to operate. Through intelligent empowerment, unmanned driving itself knows how to find the required steel coils from the warehouse area according to the production plan, and then transport them to the designated location.


Cold rolling mill, crane control system


From 2017 to 2019, this cold rolling workshop implemented an overall intelligent transformation, and the two hot-dip galvanizing units achieved intelligent upgrades.

Moving forward along the production line, 32 technical transformation projects come into view one by one.

1) Coil Unbaling Robot.

In the past, steel coils needed to be manually bundled and unbundled to move between different processes. Especially when unbundling, workers need to use powerful pliers to cut the steel rolling belt, which is time-consuming and labor-intensive, and also poses safety risks: a steel coil that is as tall as a person and weighs about 25 tons can easily injure people the moment it bounces off. After transformation, this work is handed over to robots, which is efficient and safe.

​2) Inspection Robot

Steel coils are wrapped around countless rollers during operation. In the past, in order to detect abnormalities in the rollers, workers in each shift had to walk from the first floor to the seventh floor for inspection. One trip took 2 to 3 hours. Now, The inspection robot can automatically perform inspections every 4 hours and prompt workers to perform inspections and repairs when encountering abnormalities. Work efficiency is improved and the labour load is reduced.

3) Zinc pot electromagnetic skimming system.

During the galvanizing process, zinc oxide impurities are formed when liquid zinc comes into contact with air. To ensure the quality of finished products such as automobile sheets, zinc oxide must be suppressed, driven away and scooped out. In the past, workers had to wear insulating suits and use long-handled ladles to scoop out impurities one by one. After the transformation, the zinc oxide was gathered together using electromagnetic skimming technology, and then fished out by a slag-removing robot, making it unmanned.

Furnace closed loop, alkali recovery, energy environment intelligent online, zinc layer closed loop, humidification and slag suppression, edge thickness gauge, sampling robot… One after another intelligent applications have greatly reduced the labor required in the production line. Each line only requires four operators per shift, and they are centrally controlled in the centralized control room in the middle of the workshop. They monitor various production parameters of the entire line in front of computers and large screens, which greatly reduces the workload. In addition, smart manufacturing also brings benefits such as cost reduction, efficiency improvement, energy saving and consumption reduction. According to reports, since the transformation of this digital workshop, comprehensive pollutants per ton of steel have dropped by 30%, production efficiency has increased by 30%, production capacity has increased by 20%, energy consumption per ton of steel has dropped by 15%, and processing costs have dropped by 10%.

2. Unmanned system at the entrance of pickling cold rolling mill unit

·Automatic recognition of steel coil number, automatic quality inspection, automatic detection of centring height, core-pulling loose coil, and leading angle. The application of these five intelligent technologies at the entrance of the pickling cold tandem rolling unit realizes the automatic detection of key operation scenarios in the entrance area. Identification, regional winding and unwinding are fully automatic.


Cold rolling mill automation


Machine vision and radar point cloud analysis are used to automatically identify key operating scenes in the entrance area and realize fully automatic operation of winding and unwinding in this area. After the implementation of the project, the number of operating employees at the unit entrance has been reduced by 4, the operation time of loading and threading the support entrance has been reduced by more than 20 seconds, the overall operating efficiency has increased by 15%, and the annual output of the production line has increased by more than 2,000 tons. At present, since the production operation, the comprehensive recognition accuracy of the system’s artificial intelligence perception module is greater than 99%, the centring height detection error is less than 5mm, and the minimum detection length of edge cracks and edge damage defects is 3mm, which provides accurate guidance for the fully automatic production of the system. and feedback.

The unmanned system at the entrance of the pickling cold rolling mill unit can automatically adjust on-site equipment and achieve closed-loop control of the entire system. Operators are also liberated from the control work of cutting heads and tails and casing stuck steel. The leading detection and tracking technology realizes full automatic control, which also makes the head and tail cutting operations more precise, effectively reduces waste, and increases the yield rate by 0.25%.

This technology can also be applied to galvanizing, colour-coating, flattening, and rewinding production lines to achieve unmanned transformation of intelligent on-duty areas such as entrances, exits, and loopers, significantly reducing manual duplication of labour, improving production efficiency, and promoting the steel manufacturing industry. high-quality development.

3. Digital transformation of acid rolling workshop of cold rolling mill

In recent years, a certain acid-rolling workshop has changed its management ideas from traditional manual management to digital management. Last year, the factory established a digital management and control system to achieve precise management of energy media usage and emissions, effectively promote energy conservation and emission reduction and “dual carbon” work, reduce employee labour intensity, and reduce costs by 1.26 million yuan.

This year, the workshop will continue to build new models of digital management.

At present, the acid rolling mill unit has completed the development and application of visual supervision and management of safety facilities and fire protection equipment, an automatic supervision system for periodic inspection of process equipment, and visual management systems such as post inspection, mobile phone control, media control, environmental protection control, and work closure, which have greatly improved Improve management and control efficiency and reduce management costs.

It is understood that the acid rolling workshop has independently established a number of data collection and analysis modules. Through big data analysis, it “sees through” each intelligent dashboard and clearly presents the real-time status of each module in the form of charts.

Post operators only need to check the data intelligent dashboard to quickly identify problems, respond quickly and take measures to achieve targeted and precise policies, greatly improving management effectiveness and production efficiency.

In order to achieve the goals of energy conservation and emission reduction, this year the acid rolling workshop carried out the development and application of media control and environmental control management systems. Through the shift record function of the platform, the acid wastewater, rinsing water, strong alkali wastewater and weak alkali wastewater of each shift can be read. The emission data is made into a polyline and histogram dashboard. At the same time, the daily emission alarm limit is set to realize the flow alarm push function.

At present, the wastewater discharge data of the entire pickling mill unit is visualized, emission monitoring and alarms are provided, and monthly reports are automatically generated. Wastewater discharge has been reduced by 75% year-on-year, and the wastewater discharge management efficiency of the pickling rolling unit has been further improved.

In the past, the original scrubber control method of the pickling mill unit was not associated with the large-flow one-touch drainage of the No. 1 rinse tank. Too much rinse water was often discharged to the scrubber due to operator negligence, resulting in overflow due to excessive liquid level in the scrubber.

The new control method correlates the conductivity of the No. 1 rinsing tank and the scrubber to avoid artificial factors adding additional wastewater discharge. At the same time, by calculating the usage of rinsing water in the acid rolling unit, a corresponding automatic control system is designed to ensure that the rinsing process indicators fluctuate within the normal range and minimize the consumption of rinsing water. After the new control system went online in January this year, monthly rinse water emissions dropped by 38% year-on-year.

In addition, the acid mist emission control system has been improved to avoid scrubber overflow, as well as control the collection and utilization of steam condensate water, reduce external emissions, and significantly reduce the inflow of acidic wastewater sources. This year, the average monthly emission of acidic wastewater can be reduced by 2800m³-3000m³.

The acid rolling workshop optimized the segmented control of oil and gas lubrication oil volume and the structure of the oil and gas lubrication distributor of the 1550mm acid rolling mill unit to effectively reduce oil and gas consumption and ensure the lubrication effect. The average monthly fuel consumption dropped by 27.65%.

At the same time, chrome-plated rollers are used and the coating is thickened to reduce roller wear and sludge production. The daily average sludge production has dropped from 3.75 barrels to 366kg last year, a daily average decrease of 60.4% from last year.

The acid rolling workshop improves the energy efficiency of wastewater discharge management of the acid rolling unit through new technologies such as visual data analysis; through the use of chrome-plated rollers, the introduction of new control systems and other new processes, the acid rolling waste emissions are reduced, which not only achieves the goal of energy conservation and emission reduction but also saves money. Human resources have greatly improved the management and control level of acid rolling energy media and effectively promoted the in-depth development of environmental protection work in cold rolling mills.

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