EP2651578B2 - Rolling mill for producing steel for tubes and thin strip - Google Patents

Description

The invention relates to a rolling train, in particular a CSP plant for producing strip, in particular tubular steel, and/or thin strip, comprising a casting device for producing a thin slab and a rolling train for rolling the thin slab into a strip or thin strip.

The production of steel strip or sheet steel by hot rolling has been adequately described in the prior art. Corresponding disclosures can be found, for example, in the article by P. Uranga, AI et al. "Improvement of Microstructural Homogeneity in Themomechanical Processed Nb Steels by Thin Slab Casting", 43rd Mechanical Working and Steel Processing Conference, Charlotte, ISS, Vol. 39, pages 511 to 529 ; in the post by C. Klinkenberg, et al. "Processing of Niobium Microalloyed API Grade Steel on a Thin Slab Plant", Materials Science Forum Vols. 500 to 501, 2005, pages 253 to 260 , and in the post by SV Subramanian, et al. "Process modeling of microalloyed steel for near net shane casting" Proc. Of the Int. conf On Thermomechanical Processing: "Mechanics, Microstructure ed. by EJ Palmiere et al., The University of Sheffield. Sheffield, 2003, pages 148 to 156 .

A generic system is in the EP 0 721 813 A1 disclosed. Similar solutions disclose the EP 2 258 491 A1 , the WO 2007/073841 A1 and the DE 10 2008 029 581 A1 .

CSP (Compact Strip Production) plants are casting-rolling plants in which two separate process stages for the production of steel strips are closely linked, namely casting the liquid steel into thin slabs in the casting plant and rolling the thin slabs into steel strips in the rolling plant. The previously cast strand is usually rolled directly using the casting heat or by setting the desired rolling temperature by means of a soaking furnace or a heating device between the casting plant and the rolling train.

Conventional rolling trains of a thick slab plant have at least one roughing stand or heavy-plate stand and a finishing train arranged at some distance behind this roughing stand or heavy-plate stand. While in the roughing stand or heavy-plate stand the thin slab is usually reversingly rolled into an intermediate strip with a predetermined thickness, rolling takes place in the finishing train in tandem operation, with the finishing train being designed as a continuous train. While the distance between the individual stands of such finishing trains is usually constant and is usually around 5.5 meters, the distance between the roughing stand or heavy-plate stand and the first stand of the finishing train is usually many times higher in order to ensure reversing rolling operation in the roughing stand or heavy-plate stand to be able to Distances between the roughing stand or heavy-plate stand and the finishing train of around 50 meters or more are not uncommon in this context.

Due to a usually aligned arrangement of thick slab discharge roller table of the slab furnace, roughing stand or heavy plate stand and finishing train, conventional rolling mills are very long and more powerful stands are required, which means that the investment costs are high. In terms of energy, the conventional rolling mills are inferior to the CSP plants. Especially when producing thin strips, the entry temperature to the finishing train is very low here, which makes thin strip rolling difficult. The production of tube sheets in a conventional hot strip mill is also very time-consuming because of the necessary temperature control and reduces the production of a conventional hot strip mill.

It was therefore an object of the invention to provide a rolling train of the type described at the outset, by means of which the disadvantages described above can at least be reduced. In the sense of the invention, this object is achieved with a rolling train comprising the features of claim 1. Advantageous embodiments of the invention are defined in the dependent claims.

The rolling train according to the invention, in particular a CSP plant, preferably consists of a compact rolling train for the production of metal strips, primarily tubular steel and/or thin strip, in which the temperature between two successive finishing stands Fi and Fi+1 is influenced with the aid of a rapid heating device, in particular induction heating can be. In addition to the rapid heating device, a straightening unit, namely a roll straightener, is provided between two successive finishing stands Fi and Fi+1. Furthermore, a pair of shears and/or optionally a descaler or another strip cooling device can be arranged between the stands Fi and Fi+1. All facilities are placed so compactly that they fit between 5 and 25 m between scaffolding. Furthermore, before the rapid heating device, the stand Fi is preferably provided with actuators for influencing the curvature of the strip and/or skis on the strip head.

Together with a straightening unit, namely the roll straightener, and/or the shears and the above-mentioned actuators, safe passage through the rapid heating device, in particular induction heating, with a minimum passage dimension in the thickness direction can be guaranteed in the limited installation space. Depending on the process, the rapid heating device, shears and/or descaler can be used depending on the product to be rolled or can be moved out of the rolling line transversely, or alternatively a roller table with or without thermal insulation or a table can be arranged there. The shears can also be provided between the stands for thin-strip rolling in order to be used at the head and/or at the end and to ensure that the heads and ends of the formed strip are as straight as possible.

As a result of the additional equipment between the stands, the normal stand spacing of ≥ 5.5 m, for example, increases. To eliminate possible additional secondary scale formation, a single-row descaler is preferably provided, which is compact in design and is preferably arranged in front of stand Fi+1 behind the rapid heating device. When rolling strips with higher surface requirements (e.g. thin strip rolling), the descaler can be activated before stand Fi+1. When manufacturing tubes, the descaler can optionally be deactivated or moved out of the rolling line.

In order to save installation space, a looper can optionally be dispensed with, instead of which a minimum tension control with or without a tension measuring roller can be provided.

Compared to a conventional rolling train with induction heating between roughing and finishing train, the use of a rolling train according to the invention, preferably the rolling train of a CSP plant with the corresponding additional units, significantly reduces the installation space of a rolling train overall. The use of additional units within the finishing train, which can optionally be moved into the rolling line, can advantageously support the rolling process overall, both with regard to the process control and with regard to the microstructure adjustment in the rolled product. In the sense of the invention, these additional units require little installation space and are arranged between two finishing stands which are 5-25 m apart. In other words, the space required between two stands with the additional units is much smaller than the intermediate strip length rolled there.

The thin slab preferably produced in the casting device of a CSP plant preferably has a thickness of ≦120 mm. This provides a CSP plant which is capable of producing the desired range of products from thick tube strip to thin strip without the use of a reversing roughing stand and preferably solely using a large number of finishing stands as a rolling train.

As an example and preferred embodiment, the process and manufacture of tube strip in a CSP plant can be described. The TM process (thermomechanical process) in CSP plants usually consists of the step of one or more transformations of the austenitic starting structure in the recrystallizing temperature range to produce a uniform, fine, recrystallized austenite structure, and the subsequent step of one or more transformations of the recrystallized, austenitic microstructure to produce an austenitic microstructure that is as flat as possible, rich in dislocations and non-recrystallized (so-called pan-cake microstructure). These steps are also referred to as austenite conditioning.

Finally, in a further step, the austenitic structure conditioned by means of the first step is cooled to produce a fine-grained structure in the finished hot strip or hot sheet during the phase transformation. The microstructure of the finished hot-rolled strip or hot-rolled sheet then consists of a combination of ferrite, pearlite, bainite and martensite, whereby the content of these four microstructure components can be between 0% and 100%:

Following the above description of the TM process, the above step of forming in the non-recrystallizing temperature range of the austenite can also be omitted. In this case, the conditioning of the austenite takes place entirely in the austenite's recrystallizing temperature range.

The difficulty with thermomechanical hot rolling, however, is that in order to produce the uniformly finely recrystallized austenite grain, the greatest possible deformation must be applied in the recrystallizing area. A finely recrystallized microstructure is characterized by the fact that both the former, non-uniform cast structure and individual coarse grains or microstructure areas are completely converted into a uniform, finely recrystallized microstructure with small scatter around the mean grain size. Frequently, these conditions are not met or not fully met, leading to an insufficient conditioned austenite structure.

If the step of hot rolling in the recrystallizing temperature range of austenite is followed by a step in the non-recrystallizing temperature range of austenite, with a large ratio of the thickness of the finished hot strip or hot sheet and the thickness of the slab or intermediate strip, there is often only little residual deformation for the subsequent deformations in thermomechanical treatment. Even if individual stands are switched off, this is sometimes not enough to convert any residues of the cast structure and individual coarse grains or microstructure areas into a uniform, flat pan-cake microstructure of non-recrystallized austenite grains. Insufficiently conditioned austenite is also present in this case.

However, insufficiently conditioned austenite disadvantageously leads to individual, coarser grains outside the normal distribution around the mean crown size and/or to microstructure areas in the finished hot strip or hot sheet, the substructure of which is characterized by small-angle grain boundaries. However, such structural areas lead to poorer mechanical properties of the finished strip or sheet, in particular to reduced toughness.

According to the description of the TM process given above, the deformation occurs in the recrystallizing The austenite range is of crucial importance for the properties of the finished steel strip or sheet. Although the degree of deformation required in the first step of the thermomechanical treatment can be partially replaced by an increased entry temperature, this possibility is limited by the maximum furnace temperature as well as by the cooling at roll contact and by thermal radiation between the stands when several stands are involved in this step are.

A CSP plant is preferred in which a heating device is arranged between at least two stands Fi and Fi+1 of the rolling train, in particular between the first stand F1 and the second stand F2. If required, this heating device can also be designed so that it can be moved out of and back into the rolling train. An induction heating device, in particular with one to four inductor elements, is particularly preferred. Overall, the most compact design possible with a high power density is sought in such a heating device. The component through which the power is introduced into the band is referred to as the inductor element. One or a plurality of inductor elements can thus form an induction heater.

On the plant side, the rolling plant is preferably used as a continuous train, within which the forming steps described above in the exemplary embodiment are applied at high temperature and, if necessary, with the support of the heating device between the finishing stands and with optional cooling, rolling at low temperature. No roughing stand or heavy-plate stand, as is usual in a thick slab plant, is used here.

The forming steps are preferably coupled, ie all the stands involved are engaged at the same time after the thin slab or intermediate strip infeed. In this case, the roll stands are run in tandem operation, i.e. in an operating mode in which the thin slabs or the intermediate strip pass through all the roll stands at the same time. However, individual scaffolding can also be driven up here and therefore not participate in the forming work.

In continuous operation, a method can be used in which the cast strand does not have to be cut to length into slabs, but rather is fed continuously, preferably through a tunnel furnace, to the hot rolling mill and for this purpose the hot strip is finish-rolled, cooled and cut to length before the coiler and then is wound into coils. This mode of operation reduces the amount of scrap, since there are no top and bottom ends of strip. In addition, thinner strip thicknesses, preferably with a thickness of. < 1 millimeter can be generated, since the risk of cobbles when thin strips enter the last stands of the hot rolling mill is limited to the start-up. In endless rolling, the infeed speed of the first active stand is reduced to the casting speed, which can lead to increased temperature losses before and/or during hot rolling. Therefore, higher rolling temperatures and thus heating of the strip are required for rolling in order to avoid final rolling temperatures in the ferrite phase and/or in the two-phase region austenite plus ferrite.

In principle, such a method and the devices explained also allow the production of steel grades with a reduced austenite phase region, for example with silicon contents of >1.0 percent. Higher rolling temperatures are then required for rolling in order to reliably avoid final rolling temperatures in the ferrite phase and/or in the two-phase region of austenite plus ferrite. Steel grades of this type can easily be produced on the CSP plant according to the invention.

As already described above, during the production of the strip or thin strip, an induction heating system is advantageously installed between the front stands or at least inserted into the area between the front stands. Induction heating is preferably used between the first and second and/or the second and third stand of a finishing train.

However, an induction heater is characterized by a comparatively small passage dimension in the thickness direction and is a sensitive component. When rolling in a finishing train, especially in the first stands, so-called skis or other strip curvatures or imperfections often occur at the head, which endanger the safe passage of the tubular strip or thin strip through the induction heating or other units (shears, descaler) between two finishing stands . In addition, the above-mentioned ski-up or -down phenomenon can make it very difficult to thread the pre-rolled intermediate strip into a subsequent stand. In the worst case, the intermediate strip damages units between the two finishing stands.

According to the invention, the ski is minimized or eliminated by means of a roller straightening machine. However, it is extremely preferred if the pre-rolled intermediate strip head is cut by means of a suitable shearing device within the system according to the invention. Optionally, a pre-rolled intermediate strip can also be cropped at the head and ends with such shears if thin finished strips are to be produced in batch operation.

In a further preferred embodiment of the plant according to the invention, depending on the rolled strip material, descaling in Rolling direction behind the heating of the intermediate strip, optionally after the strip has passed through the heating device and a downstream pair of driver rollers before the entry of the intermediate strip in one or more further finishing rolling stands. This ensures that an almost contamination-free thin strip or tube strip can be finish-rolled without scale damaging the strip or thin-strip surface.

In order to ensure that the intermediate strip passes safely through the devices between two finishing stands, a number of possible actuators are preferably provided according to the invention, which can be used individually or in any combination:
Measures on the roll stand itself include installing a twin drive and different settings for the roll speed on the top and bottom rolls depending on, for example, the entry thickness, the reduction in thickness, the material or the temperature, as well as different diameters of the top and bottom work roll ah.

In order to influence the temperature distribution of the rolled product in the thickness direction, the slab or strip cooling system upstream of the rolling stand Fi can be adjusted in such a way that a temperature profile that is as symmetrical as possible is created over the thickness of the rolled product or is influenced by targeted temperature trimming of the skis. Alternatively, trimming of the slab temperatures on the top and bottom is also possible for this purpose in front of the stand with a heating device.

Furthermore, it is planned to adjust the table height in front of the finishing stand Fi, so that a defined slab or strip entry position in the roll gap (e.g. middle of the rolling stock = middle of the roll gap) is ensured.

The installation of a straightening unit can also prevent the occurrence of an uneven strip course (ski, bulge, curvature) with particularly simple and controllable means. According to the invention, this device for correcting or avoiding a ski or a belt curvature in the form of a straightening unit is a roller straightening machine.

As already mentioned above, a ski can be cut out of the rolling stock using scissors.

Finally, the occurrence of unevenness in the intermediate strip can preferably be detected by means of suitable surface distance sensors, in particular before it enters the heating device. Suitable sensors are mechanical, optical or other sensors known to those skilled in the art. Based on an alarm signal from a controller connected to the sensors, suitable measures to eliminate or reduce the detected uneven strip course can be initiated or the intermediate strip or slab can be rejected again.

Moreover, not only can the heating device be protected from damage caused by bending of the strip in the manner described above; Damage, in particular to induction heaters, by cooling water remaining on the strip or thin strip can also be avoided by using suitable blow-off devices, which are also particularly advantageously arranged between the roll stands of the finishing train according to the invention or can be moved into this location.

The above-mentioned additional units and measures for fighting skis can preferably be used in a CSP finishing train for various application examples. However, use between the finishing stands of a conventional rolling train is also conceivable and provided.

Figur 1

ein erstes nicht erfindungsgemäßes Ausführungsbeispiel, in dem zwischen zwei Gerüsten einer schematisch dargestellten Warmbandstraße eine Induktionsheizung und ein Treiberrollenpaar angeordnet sind,

Figur 2

ein weiteres Ausführungsbeispiel gemäß der Erfindung mit in Walzrichtung vor der Heizvorrichtung angeordnete Einrichtung zur Korrektur/Vermeidung eines Skis am Zwischenbandkopf.

Figur 3

ein weiteres Ausführungsbeispiel gemäß des erfindungsgemäßen Warmwalzwerks mit einer zwischen einer Einrichtung zur Korrektur/Vermeidung eines Skis am Zwischenbandkopf und einem Zunderwäscher hinter der angeordneten Heizvorrichtung, welche sämtlich zwischen zwei Walzgerüsten eines Warmwalzwerks angeordnet sind,

Figur 4

ein nicht erfindungsgemäßes Ausführungsbeispiel eines erfindungsgemäßen Warmwalzwerks mit in Walzrichtung hintereinander angeordneter Schere, Schnellaufheizung, Treiberrollenpaar sowie Entzunderer, und

Figur 5

ein weiteres Ausführungsbeispiel eines erfindungsgemäßen Warmwalzwerks.

The induction heating and additional units can be fixed or moved in and out of the rolling line from the side. Thermal insulation hoods can be provided there as a replacement for units that have been moved out. The invention is explained in more detail below with reference to some figures, in which several exemplary embodiments of the CSP system are shown. In the figures shows:

figure 1

a first exemplary embodiment, not according to the invention, in which an induction heater and a pair of driver rollers are arranged between two stands of a hot strip mill shown schematically,

figure 2

a further exemplary embodiment according to the invention with a device for correcting/avoiding a ski on the intermediate strip head arranged in front of the heating device in the rolling direction.

figure 3

a further exemplary embodiment according to the hot rolling mill according to the invention with a heating device arranged between a device for correcting/avoiding a ski on the intermediate strip head and a descaler behind the heating device, all of which are arranged between two roll stands of a hot rolling mill,

figure 4

an exemplary embodiment of a hot rolling mill according to the invention with shears arranged one behind the other in the rolling direction, rapid heating, a pair of driver rollers and a descaler, and

figure 5

another embodiment of a hot rolling mill according to the invention.

figure 1 1 shows a part of a hot rolling mill 2 in a first embodiment, in which the metal strip 1 runs through a first illustrated roll stand denoted Fi and a second illustrated roll stand denoted Fi+1. The distance between stands Fi and Fi+1 is between 5 and 25 m. Directly after exiting finishing stand Fi, strip 1 runs into an induction heater 8 and then into a pair of driver rollers 12 . With this pair of driver rollers 12, a strip tension can be applied to the strip 1 (even before it reaches the strip head in the subsequent stand) and, in addition, any water remaining on the strip 1 can be easily squeezed out. A minimum tension control can be set up between stands Fi and Fi+1. The pair of pinch rollers 12 helps to set an exact setting speed on the stand Fi+1. Alternatively, a tension measuring roll or looper (not shown) is arranged between the stands to ensure mass flow. Finally, in the rolling direction W behind the roll stand Fi+1, a cooling section 11 is arranged for an application example, with which the strip 1 heated in the heating device 8 to a temperature above the recrystallization temperature is cooled to a temperature range in the non-recrystallization range for a previously heated application example. The two devices 8 and 12 can also be arranged in reverse. The arrangement of pairs of driving rollers 12 in front of and behind the heating device 8 is also conceivable.

figure 2 shows an embodiment of a hot rolling mill 2 according to the invention, of which only the finishing stand Fi and the finishing stand Fi+1 are shown. A heating device 8 for rapid heating of the metal strip 1 by means of induction heating is in turn arranged between the roll stands Fi, Fi+1. A device 14 for correcting/avoiding a ski on the intermediate strip which has left the finishing stand F1 is arranged in the rolling direction W between the finishing stand F1 and the heating device 8. According to the invention, such a device 14 for correcting/avoiding a ski-up or ski-down is a roller straightening machine. Devices 14 of this type are intended to correct, ie eliminate or at least reduce to a minimum considered acceptable, the phenomenon of, for example, a lifted strip head after exiting a roll stand (so-called ski-up). This primarily serves to avoid downtimes due to inaccurate or non-existent threading of the intermediate strip head into downstream units, for example the rapid heating device 8, other units (shears, descaler) or any other roll stand Fi+1. To avoid the ski phenomenon, the hot rolling mill 2 has separate drives for the upper work roll Fia and the lower work roll Fib that are not coupled to one another, at least in one roll stand, preferably the first roll stand Fi. As a result, with suitable control of the drives, the ski-up or ski-down phenomenon can already be limited to minimum values during rolling.

figure 3 shows a further embodiment of a hot rolling mill 2 according to the invention, in which a device 14 for correcting a ski on the intermediate strip head, followed by a rapid heating device 8, is arranged between the first roll stand Fi shown and the second roll stand Fi+1 shown. A descaler 15 is again arranged between the rapid heating device 8 and the roll stand Fi+1, via which scales adhering to the surfaces of the strip 1 can be safely removed again before the strip 1 enters the roll stand Fi+1. Optionally, this embodiment of the invention can also have a pair of driver rollers (not shown) and/or a cooling system (not shown).

figure 4 shows a non-inventive embodiment of a hot rolling mill 2, in which a pair of shears 13, a rapid heating device 8, a pair of driver rollers 12 and a descaler 15 are arranged between the first roll stand Fi shown and the second roll stand Fi+1 shown in the rolling direction W of the strip 1. While the rapid heating 8, the pair of driver rollers 12 and the descaler 15 in a similar manner as in the embodiments according to FIGS Figures 2 to 4 work, the scissors 13 are mainly used to cut off the head of the strip and, if necessary, the end of the strip where roll tongues or bends (so-called skis) can occur. Thus, on the one hand, the scissors 13 replace the devices shown in the previous embodiments (not shown here) for correcting/avoiding a ski, the scissors 13 also advantageously support the further rolling process by cutting off tongues, which have a harmful effect on the run in the subsequent rolling process of strip 1 and for the work rolls of the following stands.

In figure 5 an embodiment of a hot rolling mill 2 according to the invention is shown, in which a finishing stand Fi, a device 14 for correcting/avoiding a ski-up, a shear 13 and a rapid heating system 8 are arranged in the rolling direction W of the strip 1 . After exiting the rapid heating, the metal strip 1 enters a pair of driver rollers 12, through which residual water resting on the strip 1 is squeezed out. After leaving the pair of driver rollers 12, the metal strip 1 enters the descaler 15, in which residual scale which has formed on the surfaces of the strip 1 is safely removed before the strip 1 enters the finishing stand Fi+1. Finally, depending on the application, the hot strip 1 previously heated in the rapid heating device 8 can be cooled again in the cooling system 11 and rolled out to the finished strip thickness.

The rapid heating device 8 and the scissors 13 can alternatively also be arranged in the opposite direction, viewed in the direction of travel of the strip.

If the stand spacing is to be further reduced, the rapid heating device 8 and the descaler 15 can be arranged at the same location, viewed in the direction of strip travel, and alternatively pushed laterally into the rolling line so that either the descaler 15 or the rapid heating device 8 can be used.

Claims (16)

1. Rolling train for producing metal strips, preferably tubular steel and/or thin strip, in which a rapid heating device (8) and a further auxiliary unit are arranged between two successive finishing stands (Fi, Fi+1),
   characterised in that
   the spacing of the stands (Fi, Fi+1) between which the rapid heating device (8) is arranged is 5 to 25 metres and that the at least one further auxiliary unit arranged additionally to the rapid heating device (8) is a straightening unit, namely a roller straightening unit (14).
2. Rolling train according to claim 1, characterised in that the roll stand (Fi) upstream of the rapid heating device (8) and/or regions in front of and behind this roll stand (Fi) are equipped with setting elements for influencing strip camber and/or strip ski at the strip head.
3. Rolling train according to one of the preceding claims, characterised in that the roll stands (Fi, Fi+1) are finishing stands of a preferably compact continuous train.
4. Rolling train according to any one of the preceding claims, characterised in that it is preferably a rolling train in a CSP plant which produces thin slabs with a thickness of ≤ 120 millimetres.
5. Rolling train according to any one of the preceding claims, characterised in that a heating device, particularly an induction heating device, preferably with 1 to 4 inductor elements, is arranged between the first and the second stands (F1, F2) and/or between the second and third stands (F2, F3) or movable into place therebetween.
6. Rolling train according to any one of the preceding claims, characterised in that at least one drive roller pair is arranged between a stand (Fi) and the succeeding stand (Fi+1) or is movable into place therebetween.
7. Rolling train according to any one of the preceding claims, characterised in that a device for correction or avoidance of a ski at the intermediate strip is arranged between a stand (Fi) and a succeeding stand (Fi+1), preferably in front of the heating device, or is movable into place therebetween.
8. Rolling train according to claim 7, characterised in that the device for correction or avoidance of a ski is a holding-down roller, holding-down plate, holding-down strut, bending-straightening driver, strip-head straightening channel or strip-head pressing device.
9. Rolling train according to any one of the preceding claims, characterised in that at least one roll stand (Fi) has separate drives for the upper and lower working rolls (Fia, Fib).
10. Rolling train according to any one of the preceding claims, characterised in that strip cooling means or strip heating means, by means of which the temperature distribution over the slab thickness or strip thickness can be set for influencing the ski and strip camber, is arranged in front of a roll stand (Fi).
11. Rolling train according to any one of the preceding claims, characterised in that a roll stand (Fi) has at the inlet side table height adjustment means by way of which the strip running position is adjustable.
12. Rolling train according to any one of the preceding claims, characterised in that a cutter is arranged between at least two roll stands (Fi, Fi+1) or is movable into place therebetween.
13. Rolling train according to any one of the preceding claims, characterised in that a scale washer is arranged between at least two roll stands (Fi, Fi+1) or is movable into place therebetween.
14. Rolling train according to any one of the preceding claims, characterised in that the spacing between two successive stands (Fi, Fi+1) is less than the intermediate strip length rolled between the stands.
15. Rolling train according to any one of the preceding claims, characterised in that thermal insulating hoods are arranged or are movable into place between at least two roll stands (Fi, Fi+1), particularly as a replacement for previously removed units between the roll stands (Fi, Fi+1).
16. Rolling train according to any one of the preceding claims, characterised in that the rolling train is connected with a process model by way of which the different measures and settings for influencing ski are controllable and regulable.

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