Measurement accuracy reaches 300μm! Radar technology for steel rolling mills

Green steel is steel produced using carbon-neutral or low-carbon energy sources such as hydrogen. It can not only reduce carbon dioxide emissions but is also regarded as a “gold standard” for the steel industry to reduce its impact on climate change. But on the other hand, green steel production requires considerable investment. Even if production costs have begun to loosen, the current price is still 20%-30% higher than traditional steel.

A typical example of investment-intensive solutions to quickly reduce production costs and carbon emissions while improving rolling quality and factory productivity is the optimization and automation of the rolling process through high-precision and powerful radar systems. Obviously, this is not a process for producing green steel, but an additional smart way to quickly reduce costs and carbon emissions.

In harsh industrial environments, a German company, a supplier of high-performance sensor technology, has developed a radar solution that effectively measures the thickness or width of long and flat products. This robust, low-maintenance radar technology can measure semi-finished metal products with an accuracy of 300 μm and, with necessary modifications, can be used in metal rolling mills.


Intelligent online diameter gauge, hot rolling, Measurement accuracy reaches 300μm! Radar technology


1. Steel is vital to the economy, but it is an energy-intensive product


Every economic sector requires high-quality metal products, so the current role of rolling mills remains irreplaceable. By reheating and rolling, the metal product acquires the desired strength and ductility. Whether it is steel, aluminium, copper, or other metal products, they have been widely used in many industries such as washing machines, cars, watches, computers, houses, or bridges.

To this day, the production and rolling of steel remains an energy-intensive process that consumes fossil fuels. Improving the energy efficiency of rolling mills is crucial to lowering production costs and reducing carbon footprints, thereby making the steel and metals industry sustainable in the future.

The industry urgently needs an effective sensor technology for online measurement of steel to measure the dimensions of slabs, steel beams, rails, billets, bars, steel piles or other semi-finished products. However, in the harsh production environment of the metal industry, this Automating task is still quite challenging. Therefore, manual inspection of the width and thickness of semi-finished products with callipers is still the main procedure in some workshops of rolling mills. However, the resolution of ordinary callipers is often limited to 1mm. Therefore, in harsh operating environments, automation can not only effectively eliminate safety hazards but also help achieve high-precision requirements. In addition, manual measurement can only be performed after the metal product is rolled. During the production process, if the product size is found to not match the specifications and it is too late to adjust the rolling parameters, forced adjustments may also hurt the rolling infrastructure and machines causing lasting damage.


2. Sensitive optical sensors involve X-ray safety issues


Due to the temperature of metal products as high as 1300°C, the automation of traditional optical systems such as laser sensors is severely limited under harsh light conditions, as well as factors such as steam, dust, and vibration.

Sensitive optical and electronic equipment must be protected from overheating, and lenses require frequent cleaning. Not only are these tasks labour-intensive, but they also incur significant downtime costs. In addition, hot liquid metal, changes in reflectivity, rough surfaces on metal products, and dusty environments can cause frequent measurement failures or errors. Finally, for optical systems to work in these environments, large amounts of pressurized air are often required for cleaning, an energy-intensive task that can result in high energy costs.

Traditional measurement systems not only rely on X-ray technology or radioactive gamma emitters but also have other disadvantages: First, for the radiation measurement system to be accurate enough, each metal alloy measurement needs to be calibrated, which is a complex task and time-consuming work; secondly, the radiation measurement system cannot be used for width measurement, and the accuracy of the system decreases as the thickness of the product increases; thirdly, due to the conflict between Russia and Ukraine, affected by geopolitics, there is an extreme shortage of radioactive caesium sources required for slab and the thick plate measurement whose thickness is about 50mm or more. Fourthly, ionizing radiation poses a threat to the safety and health of factory workers. Access to the factory area where the radioactive source is located needs to be strictly restricted, which is another time-consuming process. This is a laborious approach and has certain safety risks.


3. Robust and durable radar sensors are ideal for the metal industry


In contrast, radar sensor solutions pose no health concerns and can safely measure the width of slabs, billets, blooms and other semi-finished products during the early stages of rolling. Thanks to powerful radar technology and smart radar AI algorithms, even 1300°C molten iron products can be measured reliably with a measurement accuracy of up to a few microns and a measurement rate of up to 300Hz. Radar sensors are ideally suited to the harsh conditions of the metal industry because water vapour, dust, smoke or poor lighting conditions do not affect the measurement results. In addition, the company is also testing a thickness measurement system with an error of less than 0.02mm.

To measure the dimensions, two radar distance sensors are placed on both sides of the product. The width or thickness of a metal product is calculated by adding the two distances and subtracting the known distance between the two sensors. Since the measurement is independent of the selected material, there is no need to calibrate the sensor when inspecting different metals, alloys or surface types, such as rough-machined or polished metals.

Heavy-duty housing made of stainless steel protects the sensor from extreme temperatures if required, while a heat-resistant shield protects the sensor from radiant steel products. This flake is transparent to radar waves and therefore does not affect the reliability and accuracy of measurements.

Radar sensor systems require little maintenance or cleaning and are easily integrated into manufacturing processes, meaning rolling mills can be easily retrofitted. In addition, because radar waves have a longer wavelength than optical sensor technologies such as lasers, they are not affected by small particles in dust or mist, resulting in reliable measurement results.


4. Improve efficiency and productivity


Radar systems can automate the monitoring of rolling processes, thereby increasing the efficiency and productivity of rolling mills. Since metal products with defective dimensions can be identified online, rolling parameters can be adjusted promptly to avoid production line shutdowns, scrapped raw materials, or damage to rolling equipment. This not only saves valuable maintenance time and improves product quality, but also makes the factory consume more money. Less energy and less carbon dioxide emissions. A detailed analysis of the implementation of radar solutions at customer sites shows that the payback period is approximately 3-6 months, taking into account end-of-life products, maintenance time and effort, and energy consumption. Retrofitting radar sensors in traditional steel rolling mills, it can help to quickly reduce energy consumption and carbon dioxide emissions in steel production.


5. Practical applications


Applications for this solution include width and thickness measurement in rolling mills, precise positioning of production equipment, level measurement of liquid metals, automation of slag removers in batch heating furnaces or positioning of strips in coating and pickling lines.

Previously, ArcelorMittal, in collaboration with the company, successfully implemented a radar sensor solution for precise dimension measurement of semi-finished steel products. With the help of radar sensors, ArcelorMittal can automate product monitoring and measure slabs early in the rolling process even under the harsh conditions of hot rolling mills, regardless of the effects of dust, steam, vibration and steel temperatures of up to 1,300°C. , square billet and bloom size, the error is less than 1mm. As a result, this online dimensional measurement protects rolling mill machinery, reduces costs and carbon emissions, and increases plant utilization and safety.


Source of the article: World Metal Herald – “Special Radar Technology Solutions for Steel Rolling Mills”


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