The main objective of the entire steel rolling process is to create finished or semi-finished products by deforming slabs or billets to reduce their section. This process is used in the production of sheets, strips, profiles, and tubes for the automotive, construction, energy, and manufacturing sectors, ensuring high productivity and quality of the final product. Among the different types, hot rolling is the most widespread because it makes the metal more ductile and malleable, making it easier to form into a wide range of shapes.
Requirements:
Monitoring the position of hydraulic actuators
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Hydraulic circuit pressure measurement
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Requirement:
Monitoring the position of hydraulic actuators
Accurate measurement of the instantaneous position of the pistons, and therefore the opening between the rolls, is essential for effective control of the hydraulic actuators of the rolling mill. A high-resolution signal allows the control system to make continuous micro-corrections, ensuring consistent quality throughout all stages of the process. In an environment such as hot rolling, characterized by high temperatures, strong vibrations, and extreme stresses, the reliability and robustness of the measuring element become fundamental to ensuring operational stability and repeatable performance.
Solution:
WRA magnetostrictive linear position sensors ensure accurate and reliable position measurement in the hydraulic actuators of hot rolling mills. The contactless technology eliminates mechanical wear, ensuring long operating life and low maintenance requirements. The configuration for installation inside the cylinder and the wide range of strokes available simplify integration into the hydraulic systems of rolling mills.
Main features:
- Strokes from 50 to 4000 mm
- Linearity 0.01% FS
- IP67 protection rating
- Analog output, SSI, Ethercat, ProfiNET
With this solution, Gefran supports hot rolling processes by ensuring precision and operational continuity of the plants.
Requirement:
Hydraulic circuit pressure measurement
In systems that directly regulate the opening between the rolls in rolling mills, pressure sensors must guarantee precise and stable measurements even at high pressures, often exceeding 350 bar. Their accuracy is essential for controlling the force on the hydraulic actuators and maintaining the roll opening with micrometric precision. They must withstand pressure shocks, vibrations, and high temperatures, which are typical of the rolling environment. High immunity to electrical disturbances ensures a clean and reliable signal. Compatibility with hydraulic oils and long operating life complete the requirements necessary to ensure consistent quality and process stability.
Solution:
The KS series pressure sensors are the ideal solution for measuring pressure in hydraulic circuits that control roll opening in a hot rolling mill. Thanks to advanced technology, a latest-generation steel membrane film sensing element, and a compact stainless steel design, these sensors offer maximum robustness and reliability.
Main features:
- SIL2 certification
- Measuring range from 4 bar to 1000 bar
- Available with analog output and IO-Link communication
With the KS series pressure sensors, Gefran supports hot rolling processes by ensuring precision and operational continuity of the plants.
Operating principle:
Hot rolling is a process of plastic deformation of steel in which the material is worked at temperatures generally between 1100 °C and 1250 °C, a condition that makes it more ductile and easily moldable. After heating in the furnace, slabs and billets reach optimal ductility and flow through a series of rotating cylinders inside the rolling mills, which progressively reduce their thickness, transforming them into uniform and mechanically efficient products.
At each pass through the different rolling mills, the length of the material increases while the cross-section decreases through controlled plastic deformation. The quality of the process depends on the control of three fundamental parameters: the temperature, necessary to maintain the ductility of the material; the speed of the cylinders, which affects productivity and surface quality; and the distance between the rolling cylinders, which determines the dimensional accuracy of the final product.
At the end of the process, the material undergoes controlled cooling, an essential step to stabilize the mechanical properties of the steel before winding or cutting operations .
Requirements and technology:
In hot rolling of steel, precise control of the position of the rolls in the rolling mill is essential to ensure dimensional quality, process stability, and waste reduction. High temperatures and high rolling forces make it necessary to compensate in real time for variations due to thermal expansion, roll wear, and material fluctuations.
Modern hot rolling lines use advanced automatic systems that, by adjusting the opening between the rolling rolls using high-dynamic hydraulic actuators, allow the thickness of the rolled product to be maintained within very tight tolerances.
In this context, it is essential to measure the position of the hydraulic piston and therefore the gap between the rollswith extreme precision , in order to ensure continuous and accurate adjustment of the rolling process. Precise position control allows for uniform products, improvedprocess efficiency, and high quality standards.
Gefran meets these requirements with a complete range of magnetostrictive position sensors, designed to ensure high-precision linear measurement, long-term reliability, and various installation configurations for integration into rolling mill hydraulic systems.