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ALUMINIUM ROLLINg INDUSTRY Fig. 10: Tail end performance Fig. 11: Width changes DSR is more consistent – to get the last fraction of performance the DSR is required. At the wtail end the DSR also yields noticeable benefits, as shown in Fig. 10. Width changes: It has been found that with the DSR it is possible to switch rolling widths by considerable amounts (in excess of 600 mm) and to still achieve excellent flatness without any warm-up (transition) coils. This is a considerable benefit for mills where there are frequent product changes. This is illustrated below in Fig. 11. Operational experience Threading: The fact that the load is applied directly where it is needed makes threading with a DSR equipped mill very straightforward. The operator is equipped with two simple potentiometer type controls by which he can adjust the force distribution by adjusting the quadratic and quartic components of the force distribution. With these, and the ability to thread in force control, the head end of the strip can be threaded very easily, even down to the thinnest gauges. Grinding: The grinding interval of the DSR is similar to if not slightly longer than a con- ventional solid back-up. When grinding a DSR a slightly smaller amount of material is removed compared with grinding a solid backup. Experience in steel plants indicates that approximately two and a half times as many tonnes of material can be rolled per millimetre of DSR turndown compared with a solid roll. Note that on all the recent DSR cold mills only one ground camber has been required for the workrolls – something that considerably simplifies operations for the roll shop. economic benefit of the DSR Based on a review of a typical new large cold mill producing around 100,000 tonnes a year we have estimated potential benefits upwards of well over USD5m a year. This of course does depend on the product mix. The savings are approximately evenly divided between the benefits from improvements to the head and tail performance and the ability to minimise out of specification material at width changes. Future considerations Four trends have emerged in the rolling industry. The first is a growing demand for automotive body sheet. The second is renewed demand for maximum production flexibility to minimise work in progress and thus hold down working capital requirements. The third trend is for increased strip widths – mills of just over three metres wide are being considered for automotive and aerospace materials. The fourth trend is for the operating range of mills to be extended – many cold mills for example now extend into what was previously a thin strip mill region. This places considerable demands on the mill actuator capability and the controllability of the mill. The DSR is well positioned to face all of these challenges. Car makers will demand the ultimate in flatness. No other actuator has the range of the DSR or its dynamic response. 6-high mills have to have the roll offset adjusted from the Level 2 model prior to rolling thereafter the roll offset is not dynamic in any meaningful sense. It has been said that the sideshift can be adjusted at 1/2,000 of the rolling speed but Siemens are not aware that this is actually done in practice. The DSR pads have a dynamic response of around 30 ms and it is this fast dynamic response that provides the capability of addressing head end flatness issues as shown above. A further consideration with autobody sheet is that it generally has its final pass on EDT (Electro Discharge Textured) rolls. This is similar to the process in steel where shot blasted rolls are used in the final stand of a tandem mill to generate the desired surface finish for steel autobody sheet. Whether it is steel or aluminium these passes are typified by very light reductions. This means that the mill will run cooler and differential spray control will have little to work with. In such a situation a DSR will prove invaluable; given both its greater control range compared to other actuators and the fact that the DSR increases the bend range. In this paper we have shown how width changes can easily be accommodated – clearly demonstrating how the DSR can play its part in maximising production flexibility. Further we have shown how the DSR has the largest control range of any currently available actuator. Finally let’s consider the question of strip width. At greater than three metres wide will actuators such as 6-high still have a meaningful operating range? Or as we tend towards the widths encountered in the paper industry is the actuator that has its roots in that industry the way ahead? Do you want to know more about Siemens and DSR technology? Come and visit us at the Aluminium China 2013 in Shanghai on 2-4 July: Hall W1, Stand C70. ■ 52 ALUMINIUM · 5/2013
technology A hot topic: Specifying linings for industrial kilns and furnaces Dave Barrington, general manager, Morgan Advanced Materials Selecting the most effective insulation material for furnace applications is a key consideration and one that can deliver a major performance advantage and measurable commercial return. When the impact of thermal conductivity on longterm cost and energy efficiency is taken into account, the benefits of an effective insulation material soon become apparent. A range of materials is available for the market, yet it can be difficult to understand the benefits of one material when compared to another. However, whatever insulation material is chosen, its key attribute should be low thermal conductivity, which will enable it to restrict the flow of heat from the furnace to the external environment. Heat loss from a high temperature source such as a furnace is dominated by infra-red radiation. This is blocked by the fibres contained in a fibrous insulation material. The larger the number of fibres, the more effective the insulation will be. A superior insulation material will therefore have the best possible fibre index and contain a minimal number of ‘shot’ (unfiberised globular glass fibre) particles. Some materials on the market feature high shot content and coarse fibres, neither of which are beneficial for blocking high temperature thermal radiation. When specifying insulating materials for use as back-up lining in kilns and furnaces, which have castable or brick forming the hot face, designers and specifiers must look beyond the initial purchase cost of the insulating materials to ensure their system will deliver optimum long-term performance and return on investment. The main options for these applications are typically calcium silicate or low biopersistent fibre-based boards. Calcium silicate has been commercially available for more than 50 years, its high compressive strength makes it well suited to kiln car bases. The compressive strength of calcium silicate might seem like a key benefit, and while it can endure heavy loads, its lack of flexibility does mean the material can be prone to cracking when put under certain strains that are difficult for the material to withstand. Fibrebased boards derive their strength from the interlinking of fibres during manufacture. The more fibres that are available to link together, then the greater the strength and durability Calcium silicate edge of the board. The advantages to a board with high fibre count include easy installation and handling, excellent strength and resistance to cracking. testing thermal conductivity Low biopersistent fibre-based boards were introduced to the market in the mid 1990s. The latest versions combine high-specification low biopersistent fibres, fillers and organic binders. These boards are engineered to maximise the content of insulating low biopersistent fibres by reducing the size and amount of ‘shot’, and so deliver significantly reduced thermal conductivity offering enhanced energy-saving properties. Recent tests carried out at the most common operating temperatures for furnace backup board – between 600 and 800 ºC – revealed that in the key area of thermal conductivity, the latest low biopersistent fibre-based board outperformed calcium silicate by an average of 20 percent at 600 ºC and 15 percent at 800 ºC. While calcium silicate typically costs less than low biopersistent fibre-based board, the wasted heat and associated energy costs more than outweigh the lower initial purchase cost. The physical properties of the two materials should also be evaluated by specifiers. Morgan Advanced Materials low biopersistent fibre-based Superwool Plus Blok delivers greater process advantages and more energy-efficient solutions in furnace applications Calcium silicate corner Calcium silicate is brittle, making it prone to chipping, crumbling and breakage during transportation, handling and stacking. These issues are made worse during machining and installation. Calcium silicate also creates considerably greater levels of dust than low biopersistent fibre-based board when chopped, shaped or handled, which potentially exposes operatives to the inhalation of a particulate. Dealing with this requires the use of appropriate respiratory protective equipment, which adds to the cost. the advantages to a water-resistant system A further key issue with these products is that of water absorption, as one installation option is to apply a castable material directly onto the back-up lining material. While low biopersistent fibre based board products are treated to be water repellent (hydrophobic), calcium silicate boards are highly water absorbent. This can result in the castable becoming dry and not curing correctly. It can also result in water becoming trapped in the back-up lining, leading to possible material damage. Therefore, in addition to accelerating heat loss and requiring more energy, the calcium silicate board will physically deteriorate and compromise the effectiveness of the system, resulting in a shorter product lifespan and potentially unsafe working conditions. Leading low biopersistent fibre-based boards do not require a water vapour barrier. the true cost of energy efficiency Demand for energy around the world is steadily increasing year-on-year, and looks set to continue to rise in years to come. There are numerous reasons for companies to prioritise the energy efficiency of their operations, including surcharges on energy bills, tax credits for energy-saving initiatives and increased © Margan Advanced Materials ALUMINIUM · 5/2013 53
Page 1 and 2: Special: Aluminium rolling industry
Page 3 and 4: editorial Volker Karow Chefredakteu
Page 5 and 6: CoNteNtS “We want to make the mar
Page 7 and 8: NeW s IN BrI ef Aluminium China 201
Page 9 and 10: NeW s IN BrI ef Assan Alüminyum aw
Page 11 and 12: WIrtsCHAft Aerosoldosenindustrie mi
Page 14: WIrtsCHAft Produktionsdaten der deu
Page 17 and 18: Al Casting Confidence Built on inno
Page 19 and 20: E conoM ics quantitatively most imp
Page 22 and 23: E conoM ics scrap exports between 2
Page 24 and 25: E conoM ics Fig. 7 tion cases where
Page 26 and 27: ALUMINIUMwALzINDUSTRIe wegweisende
Page 28 and 29: ALUMINIUMwALzINDUSTRIe Aufwicklung
Page 30 and 31: ALUMINIUMwALzINDUSTRIe Aufwicklung
Page 32 and 33: ALUMINIUMwALzINDUSTRIe Visuelle Kon
Page 34 and 35: ALUMINIUMwALzINDUSTRIe Interview mi
Page 36 and 37: ALUMINIUMwALzINDUSTRIe Mertens: Uns
Page 38 and 39: ALUMINIUMwALzINDUSTRIe Prozent, und
Page 40 and 41: ALUMINIUMwALzINDUSTRIe schlüssen a
Page 42 and 43: Tap into cost-effective, Right at t
Page 44 and 45: ALUMINIUM ROLLINg INDUSTRY Practica
Page 46 and 47: ALUMINIUM ROLLINg INDUSTRY Philly B
Page 48 and 49: ALUMINIUMwALzINDUSTRIe © Georg Que
Page 50 and 51: ALUMINIUM ROLLINg INDUSTRY Fig. 4:
Page 54 and 55: technologie Relative thermal conduc
Page 56 and 57: technologie PowerWheel - Metallschw
Page 58 and 59: AnWenDUng Avantgardistische Archite
Page 60 and 61: company news worldwide © Dubal alu
Page 62 and 63: company news worldwide construction
Page 64 and 65: esearcH Filiformkorrosion und dauer
Page 66 and 67: esearcH System beschichtet. Untersu
Page 68 and 69: lieferverzeichnis 1 Smelting techno
Page 70 and 71: lieferverzeichnis • Rolling and e
Page 72 and 73: lieferverzeichnis H+H HerrMAnn + Hi
Page 74 and 75: lieferverzeichnis • Annealing fur
Page 76 and 77: lieferverzeichnis • Roll exchange
Page 78 and 79: lieferverzeichnis • Coil & Colour
Page 80 and 81: lieferverzeichnis • Burner System
Page 82: VORSCHAU / PREVIEW IM NÄCHSTEN HEF

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