Yongseok Cho, POSCO, Korea, Republic of

Co-Author:
Younhee Kang, POSCO

Abstract:
The ZRM (Sendzmir Mill) is the cold rolling mill which consists of 20 rolls to produce the stainless steels and the electrical steels. The work roll of the ZRM is so small to reduce the thickness of the strip efficiently. At the beginning of the rolling, the roll force set-up was performed for the desired thickness of the strip. If the set value of the roll force is not correct for the outlet thickness, the thickness deviation is high, furthermore the strip is broken during rolling. For the ZRM process, sound prediction of the roll force is vital for achieving the desired thickness because the stability of the rolling substantially affected by it. In this paper, mathematical model is presented for the prediction of the roll force at the beginning of the rolling. The model consists of a numerical model for the prediction of the roll force, a sub-model for the prediction of the mechanical property of the strip by the deep learning, which is the deep neural networks. It is called numerical model based deep learning. From the combination of these models, the roll force at the beginning of the rolling can be predicted to produce the desired thickness of the strip. The numerical model based deep learning has several advantages compared with typical deep learning. The prediction accuracy has been improved from the physical tendency of the numerical model. In addition, from reduced number of inputs of the deep learning model, the learning time was decreased. The prediction accuracy of the proposed model is examined through comparison with actual data.

Michael Breuer, SMS group, Germany

Co-Author:
Falk Töpfer, SMS group

Abstract:
When speaking of cold strip rolling, especially carbon strips, normally final gauges between 1.5 mm and 0.40 mm are referred to. Cold rolling of thinner strips keeps special challenges for the plant technology and the process control. In addition to the targeted final thicknesses, it is also important to attain the strip quality and the required product properties, such as flatness or surface quality. Rolling jobs which involve special challenges are preferred performed in reversing mills because here the rolling process is more manageable and a strip break has less impact on the production. The limitation on reversing cold mills, however, is the limited production capacity which, in the case of single-stand mills, is around 300,000 tons per year and in the case of two-stand Compact Cold Mills, around 600,000 tons, depending on the processed strip widths and strip gauges. A tandem mills productivity is even higher at a better yield rate together with a more simple process steps. There are regions on the world market - and this includes the Asia/Pacific region - which have a very high demand for cold-rolled thin strip in a thickness range of 0.50 mm to 0.15 mm. Two of the main applications for this material are roofing and packaging. With the capacities installed in this region alone, the demand cannot be met completely. SMS group supplied two coupled pickling and tandem roll mills especially for this demand. This paper provides an overview on the challenges and experiences we made during commissioning of this two PLTCMs. Focus is on mechanical equipment and process control items.

Jean-Pierre Robinet, CLECIM SAS, France

Co-Author:
Stanislas Mauuary, CLECIM SAS

Abstract:
Megatrends such as Electromobility shape the industrial world, this is today a well-known direction for steel producers’ development. For decades since the 80ies, Clecim has been present in Rolling and Processing of high silicon steels, always reinventing its products to fit with the new requirements. From industrial transformers to electromobility, the tolerances of silicon steel have gone more drastic in shape, flatness, thermal treatments and rolling precision. Of course, Clecim SAS remains true to its origins of rolling mill builder with the evolution of its Power 6-Hi mill for those products: smaller rolls, powerful coilers and torque, adaptive cooling solutions and of course, the necessary work roll and intermediate roll actuation with bending and shifting allow our mills to cope with flatness and quality in thin high strength gauges - always wider. The experience at the root of the edge drop management lies in process knowledge already acquired between 2004 and 2010 and enable Clecim to propose revamps of customers 4 Hi mills adapting the necessary actuators to limit edge losses. On Processing Lines, the advanced side trimmer and scrap choppers, able of online width adjustment complete the care for smooth edges and Asolid-state welding machines able to cut and weld laser wise have been the trademark and specialty of Clecim for more than one decade. Now, the new LW21L is designed for silicon very thin gauges and can match the sharp edge of the tolerances demands for final products dedicated to car motors, especially on stack of stator & rotor. The SIAS® DeepLearning including its pinhole channel offers the full set of analysis tools to detect the smallest defect. Today, Clecim SAS is proud to present you the evolution of its machines for electromobility business in details and the results achieved.

Sebastian Richard, SMS group, Germany

Co-Author:
Matthias Krüger, SMS group
Karsten Rues, SMS group
Christoph Helle, SMS group

Abstract:
In cold rolling mills vibrations of mechanical parts and/or strip can interfere several quality parameters like thickness, shape or surface quality. Since vibrations tend to occur at higher speeds, the rolling speed of single- or multi-stand mills for steel and aluminum has to be limited quite often. Among other mechanisms at cold rolling mills the so-called 3rd Octave and 5th Octave Chatter are the most important vibration issues. They are introduced by explaining related mechanisms and showing results of operational measurements. Subsequently some well-known measures against chatter issues and their consequences are listed and explained, like online Chatter monitoring with Auto-Slow-Down (ASD-) functionality. After giving a general survey about vibration issues in cold rolling mills and related conventional counter measures, the paper focusses on the development of SMS group to counteract 3rd Octave Chatter. The so-called X-Pact® Active Chatter Damping (ACD) uses Piezo electric elements as actuators which are located in an actuator box placed underneath the bottom backup roll chocks of a mill stand. A first pilot unit was put into operation in 2017 in a four-stand aluminium tandem cold rolling mill from SMS group. The optimization of the system and its integrated force measurement, including related tests and improvements to the mechanical design, was completed by April 2018. Permanent operation of the system is ongoing until today. The paper provides an overview of various operating results of the system during its normal operation. These are showing the reduction of vibration amplitudes and the increase of rolling speed with an active system. Beside of this, also the behavior of the system in the context of different vibration and excitation mechanisms is shown by practical examples. The parallel product development, with focus on product series implementation and improvements regarding performance and durability, is already applied in the actually sold applications.

Keiji Mizuta, Primetals Technologies Japan, Japan

Co-Author:
Takanori Nagai, Primetals Technologies Japan
Hirokazu Kose, Primetals Technologies Japan

Abstract:
The cooling speed over a certain level and the consistency of temperature profile are essential for the thermal cycle in the continuous annealing line (CAL) for an advanced high-strength steel strip (AHSS.) Because this particular cycle usually involves multiple water sprays, optimization of the spray pattern and nozzle arrangement, which affect the cooling speed and temperature, is expected to complete the requirements.The test to cool a rotating hot drum is conducted numerous times with various spray patterns and nozzle arrangements on the experimental equipment that replicates the process in the subject cycle as necessary and sufficient. A heated steel drum is rotated at the speed corresponding to the running speed of the strip. The water films formed on the inner surface and the intermittent cooling process are produced under the almost same conditions as in the actual cycle in the CAL. For the horizontal cooling pass, the drum is placed in an inverted position and given an appropriate taper angle so that the vertical distribution of the water film thickness formed by centrifugal force due to the rotation simulates the distribution of the water film across the width of the steel strip.Through those trials performed enough times, the ideal spray pattern and nozzle arrangement to cool an 800℃ strip of 1 mm in thickness to 100℃ at 1000K/sec or better and within ±10K of temperature consistency are identified.

Simon Mittlboeck, Primetals Technologies Austria, Austria

Co-Author:
Georg Keintzel, Primetals Technologies Austria
Konrad Krimpelstaetter, Primetals Technologies Austria

Abstract:
"This paper deals with the development of a new technology for reducing and eliminating resonance vibrations in hot strip mills and thin-slab casting and rolling plants. The new system – called Vibration Dissipator - allows to stabilize and improve the overall process stability by reducing the vibration behavior of single finishing mill stands. The Vibration Dissipator is based on two combined physical effects. First effect represents the impact of a classical absorber, being an added vibratory element that is designed to “swallow” the resonance vibration. Second, an energy dissipating element which broadens the effective suppressing frequency range. The solution consists of special designed hydraulic elements, such as a combination of a capacity, a resistance and an inductance. This arrangement of design elements can be realized as a passive or semi-active energy dissipating hydraulic solution. A pure passive Vibration Dissipator was already successfully implemented on finishing stand 3 of an industrial hot rolling mill. The actual development targets focus on a semi-active concept with an adaptable hydraulic capacity. With this concept, it is possible to adjust the desired frequency of the Vibration Dissipator in a defined range. Since the frequency of these vibrations can change during the production, our concept allows a smooth adjustment to the actual frequency within seconds, in order to achieve an optimized damping effect. With our developed frequency identification system, it is possible to identify the actual frequency of the vibration which is currently appearing at the stand. Such a system consists of accelerometers and a sophisticated algorithm to evaluate the frequency. This frequency identification system is already implemented at another technological package from Primetals Technologies."

Ossama Sharaf El-Din, Al Ezz Dekheila Steel Co., Egypt

Co-Author:
Abd El-Moneim Sewaif, EZDK

Abstract:
Improvement of Material Yield in EZDK Wire Rod Mill Plant EZDK wire rod mill plant was supplied by the German plant producer SMS, started commissioning in 1986 with one strand which was upgraded in 1996 with the second strand to reach over 900,000-ton annual production for sizes ranging between 5.5~16 mm for low, medium and high carbon steel products. The improvement of the material yield in any rolling mill plant is crucial for improving efficiency and reducing costs. In EZDK wire rod mill plant, starting in 2019 an ambitious campaign was launched to optimize the wire rod yield figures. As yield is dependent upon many factors, such as cobbles, total scrap generation, crop loss and scale loss the campaign focused on many aspects in order to achieve its target. Both technical and managerial techniques were put into practice in order to minimize the wastes created during the product's manufacturing process, how to get sure that your getting the maximum output of the inputs (billets) through controlling the reheating furnace settings to reduce the generated scale, reducing the material cobbles, and minimizing the no. of defected/scrapped coils was the challenge. We are committed to providing accurate and timely information on the material wastes on daily/ weekly and monthly basis through developing a daily monitoring system that allows us to track material wastes in real-time, it wasn’t only about the technical points only but also how to change the minds of the people to believe that the reducing the wastes will make the difference. By doing this, we could reach to a worldwide figure in the material yield (98.0%) for two consecutive years (2020, 2021) according to Badische best practice study, achieving the second place worldwide, looking forward to do better through applying further improvements.

Michael Breuer, SMS group, Germany

Co-Author:
Georg Padberg, SMS group
Wolfgang Fuchs, SMS group
Heiko Reichel, SMS group

Abstract:
CO2-neutrality is the imperative of this time to protect and preserve our environment. The steel industry is particularly focused on it, because by its very nature the manufacturing processes are energy-intensive. For steel manufacturers, this requirement leads to strategic reorientation. As plant supplier, SMS group is challenged to develop and offer innovative solutions right across the entire process chain. One challenge is to identify and utilize all energy saving potentials in the production process. The second and major task is to substitute fossil fuels by electrification and by use of green fuels. The hot rolling process is comparatively energy-intensive. The largest consumer of energy is the heating process. A major focus thus needs to be placed on the interface between the upstream processes and the hot rolling process, where optimization measures for energy saving can be made. Also for the hot rolling process itself, it is important to evaluate each individual energy consumer for his optimization potential. For some process stages and components there are already proven solutions which gain new significance in the context of fossil free production and to tap into their inherent potential. One example is the installation of mandrel-less coilbox in the roughing mill area. A coilbox comes with numerous advantages and improves the process control. However, a coilbox reduces the overall plant length and the energy consumption in the finishing mill. Another example is smart descaling, which takes place in the roughing and in the finishing mill area. Smart descaling means width and steel-grade dependent descaling. The water pressure and the water volume are specifically controlled and applied, resulting in water and energy savings. These are just two examples, among other things - including new developments, which we intend to evaluate as part of the paper with regard to their energy saving potential.

Tim-Oliver Mattern, Carl Bechem GmbH, Germany

Abstract:
This paper covers the practical improvements that have been achieved in a tube mill just from changing from traditional grease to Polyurea technology. Tubes are either formed and welded or seamless rolled. Both processes require many steps and mill equipment that is exposed to load, heat and cooling fluids. In this harsh environment the equipment needs to work reliably without unexpected and expensive breakdowns. Most of the equipment is grease lubricated and while traditional greases have provided predictable performance in the past, their deficiencies often result in increased consumption to simply maintain basic reliability expectations.

Tizian Rotherm, SMS group, Germany

Co-Author:
Christian Dornscheidt, SMS group

Abstract:
In strip processing lines, the ends of the strip have to be joined together to form an endless strip, which is necessary for a continuous process. Laser welding fulfills this task perfectly. The X-Roll® laser welder is capable of welding a wide field of steel grades, even those deemed as hard-to-weld. This is possible due to the patented inductive heat treatment system. Other technical highlights are a low cycle time, automatic welding parameter calculation, the quality assurance system, and a fast knife cassette exchange-procedure. The laser source can be either a carbon dioxide or a solid-sate laser resonator. The solid-state laser offers advantages such as less operational costs and a more flexible design. Yet the carbon dioxide laser is the more established technology on the market. As part of our processing lines, the X-Roll® laser welder utilizes synergy effects to optimize and stabilize the production. The X-Roll® laser welder is not only confined to new lines, it can also be suited for a revamp in an existing processing line. Due to the slim design of the machine, the replacement of obsolete flash butt welding machines or older laser welding machines can be done with low effort. This enhances the variety of input material. Older welding machines are often not capable of welding modern steel grades in a reliable manner, since the alloying content of the strip material effects its weldability. The paper will include information about solid state lasers, weld-seam heat treatment, revamps, preventive maintenance and possibilities of digitization. Reference implementations will be shown as well.

Robert Wolff, Lechler GmbH, Germany

Co-Author:
Jürgen Frick, Lechler GmbH

Abstract:
As the backbone of the largest industrial economies, the steel industry will continue to improve its energy efficiency with a view to meeting the new ambitious CO2 emission reduction targets set by many governments around the world. High pressure descaling is a major consumer of electrical energy in the hot rolling process; in addition, the trend towards ever-increasing water pressures in descaling has led to increased pump capacities and a corresponding rise in energy consumption and costs. Lechler’s innovative SCALEMASTER ECO+ nozzle can help turning around this trend and reduce energy consumption in hot rolling considerably, lower CO2 emissions and save operation costs. Furthermore, certain new conceptual ideas of nozzle arrangements utilizing the optimized descaling nozzles enable the surface quality of rolled material to be considerably improved compared to existing installations. The paper will elaborate on results of laboratory and field tests, product details and application engineering aspects for both the designer of systems and the user of descaling systems.

Marco Rinaldi, Danieli Corus B.V, Italy

Co-Author:
Marco Rinaldi, Danieli Corus B.V
Andrea Biliotti, Danieli Centro Combustion
Giuseppe Ambrogini, Acciaierie Bertoli Safau

Abstract:
The efficient operation of a reheating furnace depends not only on mechanical, thermal, chemical and automation, but also on the synergy with the rolling mill and all these aspects combined. Danieli has recently achieved outstanding results at ABS’ QWR 4.0 plant, which have been possible thanks to the integration of new and existing technological equipment installed in a reheating furnace. Key for such improvement is the complete integration of the reheating furnace with the rolling mill, leading to the “integrated reheating furnace” concept, which enabled an integrated view not only of the furnace but also of the furnace within the plant itself. This achievement is the result of accurate furnace control, to optimize material quality (decarburization and/or austenitic grain size), emissions rules (CO and NOx), metallic yield (scale) and productivity at the same time. The furnace set-up and control were made possible using a bloom-heating thermo-mathematical model dynamically modified by both a thermo-mechanical model—based on measured and theoretical torques/temperatures at rolling mill— and emissivity, based on combustion ratio of each zone.

Clément Muller, Fives Group, France

Abstract:
Steel manufacturers are continuously developing higher performance steel grades by optimizing the chemistry at the steelwork and by changing the process parameters, in particular the heat cycles to be applied in the annealing furnaces. In hot dip galvanizing lines, the production of the latest Gen3 AHSS require higher annealing temperatures which are difficult to be achieved by using gas fired radiant tubes. The Galvannealing induction heating of the AHSS grades is also becoming an issue, due to the retained high fraction of austenite which results in poor magnetic properties for a heating by a conventional inductor. To fulfil the requirements of these new steel metallurgies, the transverse flux induction is the unique industrial solution. Fives has been developing the EcoTransFlux™ technology since more than 20 years, first for rapid heating of stainless steel in strip processing lines. Today, this advanced technology is becoming a key equipment for processing the latest Gen3 AHSS and also for developing high-grade electrical steel products for EV market. This paper presents the main features and performances of Celes transverse flux induction technology as well as different industrial applications and references.

Michael Aigner, Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG, Austria

Co-Author:
Henk Bolt, Tata Steel Nederland Technology B.V
Danny Beentjes, Tata Steel Nederland Technology B.V
Thomas Trickl, Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG
Leonel Elizondo, Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG
Michael Brandner , Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG
Armin Paar, Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG
Maximilian Reiter, Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG

Abstract:
Graphitic HSS roll grades such as ESW’s brand VANIMO can be considered as the latest developments for the last finishing stands in hot strip mills. These roll grades are developed on the basis of the alloying concept of (Carbide Enhanced) Indefinite Chill work roll materials. During the development of VANIMO, the amounts and types of carbide-forming elements were increased and adjusted in the direction of cast HSS roll grades. The microstructure of graphitic HSS roll grades, therefore, consists of tempered martensite, cementite, and several different carbide types as well as a well-defined amount of free graphite. The main purpose of graphitic HSS roll grades is the combination of the high surface quality of Indefinite Chill alloys as well as the high wear resistance of HSS roll grades. The development and introduction of this very advanced roll grade at Tata Steel’s Direct Sheet Plant in The Netherlands were done in close cooperation between the customer and the roll supplier. Several systematic steps were taken to increase the wear performance from Carbide-Enhanced Indefinite Chill grades to the more advanced grades to reach the highest alloyed roll grade VANIMO. In every development step, the surface quality of the roll grades was carefully monitored. This paper describes the improvement of the wear performance for roll grades in the last finishing stands in the Direct sheet plant by introducing higher alloyed roll grades, up to VANIMO. Different appearances of the strip surfaces in relation to the work roll material are presented and the root causes for these phenomena are explained. Finally, some possible strategies to improve the surface quality of graphitic HSS roll grades are presented.

Sebastien Flament, CRM Group, Belgium

Co-Author:
Henk Bolt, Tata Steel Nederland Technology B.V
Gisele Walmag, CRM Group

Abstract:
Back-up rolls (BURs) in cold and temper rolling mills often exhibit very inhomogeneous wear rates over their barrel length. Wear rates and resulting BUR wear profiles are usually not understood and (thus) not well predicted. The BUR wear profile has, in turn, a large effect on the local work roll/back-up roll (WR/BUR) contact stress distribution along the BUR barrel length. This crucial parameter for rolling contact fatigue is also unknown as well as also highly inhomogeneous. Consequently, also the onset of local rolling contact fatigue (RCF) at the BUR surface is poorly predicted and may in fact differ strongly between consecutive mill campaigns of the same BUR, so that mills struggle to define adequate (= safe and economical) practical maximum BUR campaign length limits. An assessment of BUR wear and rolling contact fatigue phenomena by examination of worn BUR surfaces in association with rolling mill process data and profiles has enabled to determine the degradation mechanism of various rolls in different kinds of cold rolling and temper mills, stand positions and materials. This analysis, based on light optical microscopy, hardness, roughness and profile measurements was performed on-site at Tata Steel in IJmuiden. Further analysis of BUR wear and contact fatigue damage accumulation in the sub-surface region was enabled by microscopic analysis in cross section of samples extracted from two scrapped BURs, an ICDP BUR and a 3%Cr forged steel BUR. This paper will give an overview of back-up rolls degradation, surface aspects, mechanisms and important differences of selected cold and temper rolling mills.

Thomas Rasmussen, Åkers Sweden AB, Sweden

Co-Author:
Jonas Lagergren, SSAB AB
Stefan Wahlund, Union Electric Åkers
Johan Eliasson, Swerim AB
Hans Magnusson, Swerim AB

Abstract:
A new High Speed Steel (HSS) concept for heavy-duty cast roll materials has been developed. Target was to develop a suitable casting and alloying concept to yield an optimized structure of the HSS material, but still using established production processes. More specifically, the current alloying concept needed to be modified so that unwanted phase transformation of softer phases, ferrite and pearlite, should be pushed to longer times, in order to reach the harder phases martensite and bainite upon cooling after austenitization. With guidance from computational thermodynamics different alloying concepts were studied by simulating continuous cooling diagrams (CCT), with interest on critical cooling rates and with respect to the available process window. To validate and confirm these alloying ideas, small scale laboratory ingots were produced, and industrial heat-treatments were simulated by dilatometry. From dilatation experiments and characterization, it was confirmed that the optimized alloying was able to push unwanted phase transformations to longer times, which resulted in improved mechanical properties. Different tempering trials were studied by varying double and triple cycles. Different tempering temperatures was then decided and evaluated by both hardness and impact testing. Based on small-scale laboratory work and the confirmation of alloying ideas, together with a suitable casting and modified heating concept, a full-scale Plate Mill Work Roll has been produced. This new HSS roll concept is now running in a hot plate mill, results are here presented.

Thomas Trickl, Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG, Austria

Co-Author:
Michael Brandner, Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG
Leonel Elizondo, Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG
Michael Aigner, Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG
Armin Paar, Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG

Abstract:
Materials development for rolling application has become a multi-disciplinary exercise, trying to merge know-how and competence of experts from various fields. ESW follows this path for all developments related to shell material. This paper presents the framework of the current activities in HSS material development for hot strip mills. In this present project, a European HSM, R&D institutions and ESW are working on improving performance and surface capabilities of HSS material. Special emphasis is laid on the work in the area of heat treatment. Here, the project goal was to develop a simulation model to identify critical points of time, time savings and to predict alternative heat treatment routes not previously used for HSS compound work rolls. The simulation was set up in an axisymmetric 2D model in the FEM software Abaqus. For model setup, thermophysical data as well as data from a temperature field measurement were used. The temperature field was recorded by an instrumented work roll containing 12 measuring thermoccouples at different axial and radial positions, during an entire heat treatment. The model was also validated with data from CCT and TTT diagrams as well as dilatometer and residual stress measurements.

Hartmut Pawelski, SMS group, Germany

Co-Author:
Alexander Ring, Thyssenkrupp Rasselstein GmbH
Martin Höß, Thyssenkrupp Rasselstein GmbH
Holger Pulst, SMS group
Christian Wietzig, SMS group

Abstract:
In the cold rolling business, the trend towards thinner and/or materials with higher strength or generally improved mechanical properties is unbroken. For the DCR process (double cold reduction) in tin plate industry, this means production of grades DR9.5 (AISI/ASTM 623) or beyond, final thickness towards 0.1mm, and reduction up to 50% in a single pass. When roll gap lubrication conditions and strip tensions already are at an adequate level, reduction of work roll diameter remains the most efficient way to achieve these goals. For an existing mill, normally this affords an extensive revamp. To overcome this situation, a cassette with two smaller rolls was developed, which exactly substitutes one of the large work rolls in the first stand of a DCR mill, so that in fact a 5-hi configuration is created. The change between 4-hi and 5-hi mode and back is as simple as a normal work roll change. In the presentation, the theoretical aspects of combination of small and large work roll diameter and the influence of these asymmetric conditions on process parameters, material flow and properties are discussed. A prototype system was designed by SMS group. It was built in cooperation with thyssenkrupp Steel - Packaging Steel (Rasselstein) in Andernach and successfully tested in the first stand of Rasselstein‘s DCR mill NWW4. Technological features regarding drive situation, horizontal forces and flatness control are described. Measured process data is presented, which illustrates the potential, regarding roll force decrease in combination with high strip thickness reductions.

Livio Taccani, Tenova S.p.A., Italy

Abstract:
Over the recent years industry trends pushed further the roll shop automation from automatic to automated, making the roll grinding process more independent from the human intervention. Pomini Tenova, with a solid ground of three decades of successful experience in designing and delivering total automated solutions, combines the adoption of proven solutions with modern technologies effectively matching to the actual industry trend. Several automation engineering developments, enhanced roll inspection systems, application of latest digital technologies as well as high level software controlled CNC loading dedicated cranes, allow a smooth workflow of rolls across the roll shop with enhanced operational safety, repeatability and plant productivity.

Matteo Tomba, PERT Srl, Italy

Co-Author:
Nicola Tomba, PERT Srl

Abstract:
Grinding balls are used in mining, coal, and concrete making plants, to grind materials by impact, abrasion and crushing. Compared to casted/forged balls, rolling process guarantees the best product performance in terms of ball geometry and shape, higher productivity and lower production costs, better material yield. Inline heat treatments will ensure the required ball hardness, minimizing or avoiding any offline treatment. Balls sizes which can be rolled on PERT grinding ball rolling mills are ranging from diameter 15 mm to 150 mm, with hourly productivity, depending on ball size, ranging from 1 ton/h up to 35 ton/h. The described case history, will show at the audience all the project developments for an integrated mill starting from billet to the final steel ball production.

Kazutoshi Kitagoh, Toshiba Mitsubishi-Electric Industrial Systems Corporation, Japan

Co-Author:
Toshihito Shimotani, Toshiba Mitsubishi-Electric Industrial Systems Corporation
Masaki Nakaema, Toshiba Mitsubishi-Electric Industrial Systems Corporation
Min Zhang, Shougang Jingtang United Iron & Steel Co., Ltd.
Jixin Li, Shougang Jingtang United Iron & Steel Co., Ltd.
Zhankui Dong, Shougang Jingtang United Iron & Steel Co., Ltd.

Abstract:
We introduce and discuss two technical features of hot rolling in an endless line with the excellent application results. The first feature is functionality to establish rolling stability with high quality of products in endless rolling. The second feature is automation to enable multiple rolling modes. In an endless line, continuous caster and rolling equipment are directly connected via a tunnel furnace. There is a shear between caster and tunnel furnace. The line can be operated in 3 modes – “endless“, “semi-endless“ and “coil to coil“ rolling. With endless rolling, there is no shear cut between caster and tunnel furnace. The advantage of endless rolling is that ultra-thin coils can be produced stably with high product quality since, unlike a conventional hot rolling, there is no loss of tension at head/tail end. With semi-endless rolling, the caster output is cut into long slabs. The coiler entry shear is used to create several coils from a single slab. With coil to coil rolling, the caster output is cut into slabs. The mill and caster can operate at different speeds in semi-endless and coil to coil rolling. When rolling speed needs to be changed to satisfy production or operational requirements, coil to coil or semi-endless rolling can be selected. The multiple rolling modes feature provides flexible selection of rolling mode on a single line and expands both product types and operational flexibility. Finally, we show excellent control results in the actual line with the above technical features.

Kerstin Baumgartner, Primetals Technologies Austria, Austria

Co-Author:
Simon Grosseiber, Primetals Technologies Austria
Andreas Jungbauer, Primetals Technologies Austria
Jürgen Scholler, Primetals Technologies Austria

Abstract:
"The newest member of the Arvedi ESP family closes the gap between ultra-thin and thick gauges in endless production, being designed for 0.8 mm up to 25.4 mm with a yearly capacity of more than 3 Mt on a single strand. This paper introduces newest developments and features implemented in this latest ESP reference, such as the longest ESP caster ever sold with 8.5 t/min mass flow, the latest cutting edge split-core EMBR design and bulging compensation with the bender anti-bulging system. Special features of the rolling mill are the revolutionary inline work roll change system in the finishing mill, enabling to even double the current ESPs world-records regarding maximum rolled strip length within one TSCR sequence. Moreover, the Ultra Early Power Cooling system allows rapid cooling of thick gauges to coiling temperature already within the finishing mill before even reaching the cooling section in the run-out table, thus facilitating superior mechanical properties for demanding applications. These technological packages enable a fully endless production of the most challenging product mix ever seen on thin slab casting and rolling plants, while keeping the core features of Arvedi ESP lines like zero-carbon emission hot rolling and the well-known excellent coil quality. "

Björn Kintscher, SMS group, Germany

Co-Author:
Cosimo Cecere, SMS group
Tim Kleier, SMS group
Tristan Töpfer-Bergner, SMS group

Abstract:
In view of global warming and the international agreements on climate targets, the topic of sustainability is more urgent than ever and the steel industry must make its contribution to CO2 reduction. At the same time, demand for "green" steel is increasing, as the automotive industry, for example, has to consider the CO2 footprint of their products over the entire life cycle. The CSP® technology has been known since its introduction as a particularly efficient way to produce high-quality hot strip. With its further development, CSP® is not only offering the energy-optimized way of hot rolled coil production, but is also continuously closing the gap of achievable products compared to the conventional route. Recent modernization upgrades of the CSP® plants revealed new improvements and benefits to increase productivity, improve plant reliability, reduce energy consumption and lower the carbon footprint. Even though modernizations are the most common approach in Europe, a new steel plant is built - and as such, it is a novelty since decades. In 2025, the first carbon-neutral CSP® Nexus plant will go on stream as part of the H2 Green Steel project in Northern Sweden. The CSP® Nexus technology does not only move forward in terms of energy optimization but even makes the big step into carbon free steel production. In addition, it takes full advantage of high throughput casting and the latest developments in hot rolling, such as endless operation where beneficial. Thus, CSP® Nexus increases and enhances the product mix compared to other combined casting and rolling plants in terms of steel grades and strip dimensions. This paper will give an overview on technology of the CSP® Nexus plant for H2 Green Steel and the possibilities of the Nexus concept. In addition, it will highlight the approach for the modernization of existing CSP® plants.

Yuan Fang, Baowu Group, China

Abstract:
Twin roll strip casting and rolling is one of typical near net shape steel manufacture process. Baostrip® for low carbon steel have made breakthrough progress and achieved remarkable results during past 20 years. Baostrip® has gone through two stages. The first phase, which took more than 10 years, involved understanding the effects of the process parameters, chemical composition, and inclusion of steel on the initial heat transfer, sub-rapid solidification, castability, phase transformation, structure, and mechanical performance. A pilot plant equipped with 1200-mm-wide twin-roll caster was built for developing side dam, nozzle, and casting roll. The liquid steel is supplied by a 15t electric arc furnace, ladle furnace and Vacuum Oxygen Degass. More than 300 heats were trialed and more data, experience, and knowledge were obtained. A variety of steel grades such as silicon steel, low-carbon steel, high-strength low-alloy steel, medium-carbon steel, and medium-Mn steel were successively trialed. A series of models were built to control the uniform solidification on the casting-roll surface and uniform wear of the side dam, as well as to minimize fluctuation of the casting pool level and stabilize the separation forces.The second phase commenced in 2012. An industrial demonstration production line was put into operation in 2014, and has made remarkable achievements. Last year, Baostrip® obtained the first construction contract of commercial strip casting and rolling plant. This paper summarizes the results we obtained in the industrialized demonstration plant, and introduces the new project, and analyses development direction and ways of strip casting and rolling technology in future.

Grzegorz Winiarski, Lublin University of Technology, Poland

Co-Author:
Tomasz Bulzak, Lublin University of Technology
Konrad Lis, Lublin University of Technology
Łukasz Wójcik, Lublin University of Technology

Abstract:
Railway axle forgings are most often made using two technologies, which include open forging and rotary forging. However, these methods are relatively inefficient and the products obtained are characterised by large allowances for machining. Therefore, new and more efficient forming methods involving rolling are being developed. Of the many methods, skew rolling appears to be particularly beneficial for this group of products. The advantages of skew rolling prompted a study of this technology to determine the influence of selected technological parameters on the process and product quality. The work was carried out based on numerical calculations. The numerical model consists of 3 identical rollers, which are evenly distributed around the billet in the form of a bar section. The axes of the rollers are angled about the axis of the billet by a small angle. One end of the billet is fixed in a chuck that supports the rolling process. Three sets of rollers were used, differing in the geometry of the roll-forming zone (conical, radial concave and radial convex). On the basis of the analysis of the results obtained, it was found that the shape of the roll has the greatest influence on the quality of the external surface of the product and the value of the maximum force applied to the chuck that pulls the billet during rolling. The use of a conical rollers results in forging with the highest external surface quality. A forging rolled using a concave rollers has the worst surface quality. With regard to force parameters, it was found that the lowest value of the maximum force applied to the chuck is required for the conical rollers. On the basis of the research carried out, it was concluded that the skew rolling technology analysed can be used to produce railway car axle forgings.

Konrad Lis, Lublin University of Technology, Poland

Co-Author:
Grzegorz Winiarski, Lublin University of Technology
Tomasz Bulzak, Lublin University of Technology
Łukasz Wójcik, Lublin University of Technology

Abstract:
The forming of railway axles is carried out using forming techniques. Rotary forging and open forging are used to produce railway axles. However, in order to increase the efficiency of the process by reducing the time needed to manufacture the product, as well as its energy intensity, it is necessary to propose an alternative forming method. To this end, research work is being carried out at the Lublin University of Technology, including the development of cross wedge rolling technology using flat tools, as well as skew rolling using three cone rollers. A test stand in the form of a numerically controlled inclined roller mill has been developed, enabling the forming of products whose final shape is obtained as a result of the sequential movement of three work tools. The machine developed is characterised by its high versatility of use due to the numerical control system used, which makes it possible to manufacture products on the basis of their envelope outline. The aim of the study was to analyse the geometric dimensions of the railway axle forgings obtained by the skew rolling method. Measurements were taken of the shape deviations, including the roundness of the individual steps, as well as the straightness of the axles. A non-contact measuring method using the GOM Scan 1 optical measuring system was used.