Quality strip is about metallurgical precision – high strength and toughness at alloying levels that keep costs down and preserve weldability. It is also about precise thickness across the full width, as well as consistent flatness to assure fit-up in fabrication. For the successful coil producer, the mill is more than the rolling stand(s) at its core. Ancillary processes, in cooling and levelling in particular, are vital to quality, and the control of a distributed process is the key to efficient asset utilization. Beyond the operations and the engineering, there is a business – one that supplies some of the most safety-critical applications, and the most demanding customers in all of industry. When you are looking for a reliable and expert partner for your venture in this market place, Primetals Technologies is this partner.
Designing a steckel mill is far more than an exercise in mechanical engineering – it is a special and unique example of combining operational efficiency and metallurgical function. Steckel-plate and coil products derive their properties from the combination of the deformation and temperature path they follow, and this means that flexibility to roll a broad mix in a single mill is built into the layout and the mill parameters. These design factors have to be right for all time. Getting them right starts with a complete understanding of process metallurgy, and translating this into a complete and robust design relies on experience. Primetals Technologies has more experience than anyone of the design and supply of modern wide plate mills, allowing us to develop and use engineering tools specifically for the Steckel mill.
Tools for Successful Design
- Bespoke Process Models (incorporating metallurgy as well as roll-bite mechanics and heat transfer)
- Facilities Design Methods (leading to maximized asset utilization under optimal deformation-temperature paths)
- Finite Element Analysis and Simulation (modern engineering tools to prove and optimize equipment performance)
A twin stand mill with a rougher stand before the steckel mill is suitable for an output of 800,000 tonnes a year.
- Mill types: 4-high work roll shift mill; 4-high Pair Cross mill (PC mill) with on-line roll profiler and dynamic PC option for dynamic Automatic Profile and Flatness Control (APFC).
- High-speed threading: 2m/sec or higher to maintain top and tail temperatures
- Short gap time: Time between passes less than 3 seconds except first two passes
- Stable rolling: Hydraulic servo side-guide and appropriate furnace coiling tension
- Quality control: Head & tail thickness compensation, AGC, APFC, AWC, CTC, QOC (Quick Open Control)
The best designed and installed steckel mills guarantee a long operating life, through changing markets as well as emerging and improving technology. The key to a sustainable asset is modular technology, allowing upgrades to be made as efficiently as possible in both time and cost terms. The integration skills of Primetals Technologies and our broad base of engineering disciplines, from machine design through process control and metrology, make us an ideal partner in the maintenance and development of the steckel mill as a lasting asset. The potential of the modular approach is wide-ranging too. It can equip a new operator for a low-volume market at entry with scope for future capacity growth, or it can guide an established operator into new product markets. Future-proofing of a customer's business may be the greatest challenge for any technology provider, but in steckel mills, Primetals Technologies is your partner to provide it.
Examples of Modular Technology
- Profile and Flatness Control
- Transformation Monitor
- Shear Technologies
- Steckel Coiler Furnace
- Coiler Technologies
- Addition of rougher stand before mill
- Addition of two or three stand finishing mill
- Plate transfer device
Fig.1- The steckel mill is a reversing mill with a heated coiler at each end
Fig.2- The steckel mill is suitable for lower tonnages
Thanks to integrated process models today's demands for flexible and economic production of steel strip can only be met by electrical and automation solutions based on technological process modeling, high-performance control systems, and a comprehensive understanding of hot rolling technology.
Therefore electrical and automation solutions meet new and challenging requirements to help ensure reliable, reproducible quality to be able to produce plate more accurately than ever before.
In order to master these requirements we offer solutions which already feature Industry 4.0 readiness through seamless integration of:
- Production Management Systems (Level3)
- Model based Process Automation including neural networks (Level2)
- Advanced Automation solutions (Level1)
- Most powerful mill drives for higher throughput
The combination of this together with a profound knowledge of the rolling process provides:
- Interleaving for thermo-mechanical rolling sequencing
- Advanced mill pacing to reduce no-load times
- De-tapering to achieve head/tail thickness accuracy
- Model predicted roll alignment to minimize strip camber
- Optimum support of operating personnel with an easy-to-understand human-machine interface
- Embedded system diagnostics for efficient maintenance and quality assurance
- Modular design of software landscape to minimize familiarization and maintenance time