Patent Application
20250135529
The present invention relates to a method for regulating a strand casting plant,
wherein a measured variable is determined, which correlates with the variation of the casting level forming in the mold, this measured variable is processed with incorporation of at least one computation rule and is used to reduce the variations of the casting level,
The invention also comprises a corresponding device.
The method can be used in continuous strand casting. In general, the method can be advantageously applied in all strand casting methods having high casting speeds, because a highly dynamic regulation/control of the casting level is increasingly required here. The term “strand casting” includes the casting of slabs and strips, in particular the casting of thin slabs, such as the casting of thin slabs in direct combination, that is to say combination of a strand casting plant with a hot rolling mill.
In continuous strand casting, it is generally of great significance from a metallurgical aspect for the formation of a uniform, crack-free strand shell and a homogeneous, fault-free slab that casting level variations are within a required narrow tolerance range. Because of various phenomena which influence the casting level, a regulation is necessary to keep it constant. These phenomena include
1. Transient flows into the mold via the inflow unit:
2. Change of the volume of liquid steel in the mold:
3. Transient flows out of the mold:
All of these listed phenomena result in changes of the casting level and these changes have to be counteracted. Since many of the phenomena occur very suddenly and unexpectedly, the dynamic range of the regulation plays a very large role.
In the case of special steel qualities, for example, peritectic steels or ferritic rustproof steels, irregularly occurring raising and lowering of the bath level (=cyclic) increasingly occurs during the continuous strand casting procedure, which is known as “bulging” or “mold level hunting”. During the bulging, a determinable relationship can be established between a measured variable correlating with the bulging and the casting level movement. It is a feature of this cyclically occurring disturbance that it takes place in the case of a specific casting speed at a period duration which approximately corresponds to the average roller division (i.e., the spacing of the rollers in the transportation direction of the strand) of at least one region of the strand guide. The bulging occurs to a particular extent in strand casting plants in which the roller division in the strand guide is constant over long portions (i.e., multiple successive rollers in the transportation direction of the strand have equal spacing in relation to one another). In addition to the fundamental wave, harmonic waves also occur. It has been possible to establish that the bulging only occurs above a critical casting speed to be determined empirically, which is in turn dependent on the equipment used and on the operating mode. However, a restriction of the casting speed is not acceptable from the aspect of a continuous trend toward capacity increases. Typical casting speeds, e.g. in the casting of thin slabs in direct combination, are up to 6 m/min and above.
Bulging leads to an irregular thickness of the strand shell, which may be problematic in particular in the casting of thin slabs in direct combination on account of the smaller thickness of the cast strand in comparison with a cast slab and the high casting speed.
The regulation of the casting level by the setting of the inflow unit of the mold only has a low dynamic range, see for example WO 2007/042170 A1, where the power consumption measured value of the rollers of the strand guide is used for setting the amount of steel supplied to the strand casting mold. It is therefore not possible, for example, to offset the frequencies of greater than or equal to 0.6 Hz, which occur in continuous strand casting from a speed of greater than or equal to 2 m/min, and which cause irregularities in the steel product and thus reduce the quality of the product. This problem of “high-frequency bulging”, i.e., the bulging compensation of the bulging at frequencies greater than or equal to 0.6 Hz, is solved for example by WO 2018/108652 A1.
WO 2018/108652 A1 therefore proposes a method as mentioned in the introduction which reduces variations of the casting level both as a result of cyclically opposing movements of the inflow unit—at relatively low frequency—and as a result of cyclically opposing change of the roller spacing of rollers of the strand guide—at relatively high frequency.
It has been found that with the compensation value determined in the process for the roller spacing of the rollers of the strand guide, when this compensation value is fed to the adjustment device of the rollers, the whole extent of the expected reduction of the variations of the casting level often cannot be achieved.
It is therefore an object of the present invention to overcome the disadvantages of the prior art and to propose a method for regulating a strand casting plant, by means of which the variations of the casting level greater than or equal to 0.6 Hz can be even better reduced.
This object is achieved according to the invention by a method for regulating a strand casting plant as claimed in claim 1,
It is provided in this case that the actual value of the roller spacing is used as one of the input variables for this observer, in order to compensate for a phase shift and/or amplitude of the actual value of the roller spacing.
In principle, a movement which adjusts out the variations is thus effectuated by the computation rule by means of the adjusted rollers of the strand guide. The mutual spacing of opposing rollers, between which the strand is guided, has a direct effect on the liquid core of the strand and directly changes the casting level, the variations of the casting level are immediately corrected. A more accurate and dynamic regulation of the casting level is thus enabled. Smaller variations of the casting level in turn effectuate a quality improvement of the strand and/or the slab final product, for example, a reduction of inclusions or an avoidance of cracks. Therefore, in-phase oscillations having higher frequencies can also be generated by changes of the roller spacing. The movement of the inflow unit, in contrast, which establishes the quantity of liquid metal which enters the mold, is transmitted more slowly to the casting level, because liquid metal located below the inflow unit still flows into the mold when the position of the inflow unit is changed. An in-phase change of the position of the inflow unit can therefore only be achieved at lower frequencies using the inflow unit and/or only a lower regulator quality can be achieved by this additional dynamic range, which cannot be offset.
According to the invention, a control and/or regulation of the casting level can be achieved by the change of the mutual spacing of opposing rollers. The strand is located between opposing rollers. The method only requires adjustable rollers which are arranged before the complete solidification point. The complete solidification point is, viewed along the strand guide, the location where the core of the strand or the slab is already solid. A regulation or control of the casting level is only possible before the complete solidification, however, i.e., where the strand or the slab is still liquid in the core. The rollers, the mutual spacing of which is changed to reduce the variations of the casting level, can be, but do not have to be, the rollers which are driven to draw the metal strand out of the mold.
The mutual spacing of opposing rollers of the strand guide is cyclically changed according to the invention. “Cyclically changed” means that opposing rollers periodically change the mutual spacing thereof in relation to one another.
In this case, the method according to the invention can be used as the single regulation and/or control method for the casting level (in combination with the flow rate regulation of the inflow unit), or also in combination with other regulation and/or control methods for the casting level by the inflow unit. In the case of a combination of regulation and/or control methods, the individual regulation and/or control methods can be operated independently of one another.
Although the method in WO 2018/108652 A1 is good at achieving in-phase reduction of oscillations having higher frequencies most of the time, there are operating situations where the behavior of the strand casting plant, namely of the adjustment device for the rollers, deviates from the models stored in the observer. The adjustment device then fails to operate in-phase or with the envisaged amplitude. The reasons for this are, for example, wear of the mechanical and/or hydraulic components of the adjustment device, changes in the strand thickness or steel properties, friction in the hydraulic cylinder or in mechanical parts of the adjustment device and thermal deformation in components of the adjustment device. A change in the strand width, i.e. the width of the thin slab, for example, may also bring about a deviation from the models because, as the width increases, the pressure in the hydraulic cylinders of the adjustment device has to be increased in order to obtain the same strand thickness.
In order to be able to achieve a good compensation in particular of the high-frequency casting level variations in these operating situations, too, the actual value of the roller spacing is taken into account in the calculation of the compensation value for the roller spacing. Therefore, the compensation value necessary for this unforeseeable operating situation is then produced in order that the high-frequency casting level variations are nevertheless compensated for as much as possible.
In particular if the bulging is (also) to be offset, the cyclic changes can be in a frequency range up to greater than or equal to 0.6 Hz, preferably up to 5 Hz. The change of the roller spacing can thus take place at frequencies which are also greater than or equal to 0.6 Hz, and which are in particular up to 5 Hz.
Thus, for example, if only the regulation and/or control method acting on the rollers is applied, the cyclic changes of the roller spacing can be in the frequency range from 0 to 0.6 Hz, 0 to 1 Hz, 0 to 2 Hz, 0 to 3 Hz, 0 to 4 Hz, or 0 to 5 Hz. If the regulation and/or control method according to the invention for reducing the variations of the casting level is combined with other regulation and/or control methods for reducing the variations of the casting level, the other method or methods could thus cover a lower frequency range (for example, of 0 to 0.6 Hz), while the method according to the invention only covers the higher frequency range (for example, from 0.6 to 1 Hz, 0.6to 2 Hz, 0.6 to 3 Hz, 0.6 to 4 Hz, or 0.6 to 5 Hz).
In a further preferred embodiment variant of the method according to the invention, it is provided that multiple roller segments each having one or more rollers are arranged on both sides along the strand guide (i.e., opposing one another with respect to the strand), wherein at least one roller segment is adjusted normally in relation to the strand guide direction. The term roller segment also includes so-called grids, which are typically arranged directly below the mold. “Normally in relation to the strand guide direction” means any adjustment here which extends essentially normally in relation to the strand guide direction. This comprises both a pivot and also a parallel displacement of a roller segment. The strand guide is generally divided into multiple segments along the strand guide direction, each segment contains two opposing roller segments.
A roller segment arranged close to the mold is advantageously adjusted. It can thus be provided that at least one roller segment of the first segment is adjusted. It can thus be provided that the uppermost roller segment, i.e., the one located closest to the mold, is adjusted. The greatest amplification of the actuator, which engages directly, enables the highest dynamic range. The factor with respect to the change of the roller spacing in the uppermost segment and its influence on the casting level is typically approximately 1:10 to 1:13 (pivotable segments) or 1:20 (segments moving in parallel). This means that a drop of the casting level in the mold around 1 mm to 1.3 mm or 2 mm, respectively, is effectuated by an increase of the roller spacing by 0.1 mm. In this way, only very small changes of the roller spacing are necessary, which can be effectuated in a very short time to be able to compensate for high frequencies of the bulging of up to 5 Hz.
Due to the selective adjustment of individual roller segments each having multiple rollers normally in relation to the strand guide direction, the spacing between rollers situated opposite to one another is reduced in opposition to the variations of the casting level to offset frequencies of the variations of the casting level. Due to this compensation, the stability of the continuous strand casting is significantly increased and high casting speeds are enabled with uniform quality of the steel product.
According to one preferred embodiment variant of the method according to the invention, it is provided that at least one roller segment is pivoted. The pivot axis is preferably closer to the mold in this case, so that the part of the roller segment more remote from the mold is deflected more strongly. The outer roller segment, i.e., the one on the outwardly curved side of the strand guide, could be fixed in this case, for example, it could be implemented by a stationary outer frame. The opposing roller segment, i.e., the one on the inwardly curved side of the strand guide, is pivoted. It has an inner frame for this purpose, for example, which carries the rollers and is pivotably mounted. It would also be conceivable that the inner roller segment is fixedly attached and the outer roller segment is pivoted in relation to the inner roller segment.
Particularly good results in the compensation of the casting level variations can be achieved if multiple roller segments each having one or more rollers are arranged on both sides along the strand guide, wherein at least the inner roller segment located closest to the mold is pivoted normally in relation to the strand guide direction about the axis of rotation of a roller of this roller segment located closest to the mold. By virtue of the small distance from the mold, the pivoting of the topmost roller segment affects the casting level particularly rapidly.
Alternatively to the pivoting of roller segments, it can be provided that at least one roller segment is adjusted in parallel alignment in relation to an opposing roller segment arranged along the strand guide, whereby again a selective adaptation of the roller spacing between individual roller segments and rollers is enabled. The outer roller segment, i.e., the one on the outwardly curved side of the strand guide, could be fixed in this case, for example, it could be implemented by a stationary outer frame. The opposing roller segment, i.e., the one on the inwardly curved side of the strand guide, is then translationally displaced in the direction of the outer roller segment. It would also be conceivable here that, vice versa, the inner roller segment is fixed, while the opposing outer roller segment is translationally displaced.
The volume of liquid metal in the core of the strand can be determined by the spacing of the rollers of two opposing roller segments and an inference can thus be drawn about a relative casting level change.
According to one particularly preferred embodiment variant of the method according to the invention, at least one roller segment is adjusted by an adjustment device, which comprises at least one hydraulic or electromechanical actuator (for example, hydraulic cylinder or electrical spindle drive). To enable an optimum reaction time with respect to the setting of the roller spacing in regard to casting level variations, a proportional valve is preferably used for at least one hydraulic cylinder.
One embodiment of the invention provides that frequencies of the variations of the casting level in a frequency range from 0 to 5 Hz are detected and the variations are offset by means of cyclic opposing change of the roller spacing of rollers of the strand guide. In this embodiment variant, there is thus no offset of the variations of the casting level by the inflow unit for the mold.
An embodiment of the invention alternative thereto provides
This embodiment variant has the advantage that lower-frequency variations of the casting level can be offset by regulating the inflow unit of the mold, as already previously according to the prior art, while only the higher-frequency variations of the casting level are offset by the regulation of the spacing of the rollers. The possibility thus exists of retrofitting existing regulators for the lower-frequency variations with an additional regulator of the spacing of the rollers.
In this case, the regulation for the inflow unit and/or the regulation for the roller spacing can be implemented with the aid of a so-called observer, as is disclosed in AT 518461 A1. According to regulating technology, an observer is understood as a system which reconstructs non-measurable variables (states) from known input variables (for example, manipulated variables or measurable disturbance variables) and output variables (measured variables) of an observed reference system. For this purpose, it simulates the observed reference system as a model and tracks the measurable state variables, which are therefore comparable to the reference system, using a regulator. A model is thus prevented from generating errors which grow over time.
The method variant having two frequency ranges preferably comprises a first observer, which determines a first compensation value for a target position of the inflow unit on the basis of frequencies of the first frequency range, and a second observer, which determines a second compensation value for a target value of the roller spacing of the rollers of the strand guide on the basis of frequencies of the second frequency range, wherein the actual value of the roller spacing is simply used according to the invention as one of the input variables for this second observer.
In this way, the casting level in the mold is regulated both by the inflow into the mold and also by the guiding of the metal strand, preferably in the uppermost segment, after the mold. In addition, it is advantageous that due to the separation of the observers onto various actuators (on the one hand, the first compensation value for the target position of the inflow unit in the case of the first observer and, on the other hand, the second compensation value for the roller spacing of the rollers of the strand guide), no interference between the observers and/or no negative influencing of the observers among one another can occur.
In one particularly preferred embodiment variant of the method having two frequency ranges, the first observer operates in a frequency range less than or equal to 0.6 Hz and the second observer operates in a frequency range greater than or equal to 0.6 Hz, preferably between 0.6 and 5 Hz. The advantage results due to the separated frequency ranges of the two observers that interference cannot occur between the observers due to overlap of the frequency windows, whereby, for example, the target value for the actuator of the casting level regulation remains equal to (in the case of no bulges) or less than in the case without secondary compensation. In this way, casting level variations are additionally reduced and quality losses of the steel product are greatly decreased. Due to the use of the method according to the invention, high casting speeds can be used with high quality of the steel product, whereby the productivity of plants for continuous strand casting, in particular for continuous thin slab production in direct combination, is significantly increased.
One possible device for carrying out the method according to the invention comprises means for introducing a metal melt into a mold, a strand guide comprising rollers, and a measuring unit for measuring variations of the casting level, which is connected to a control unit. In this case, an adjustment device connected to the control unit is provided, which is designed to reduce, in particular offset, variations of the casting level by cyclic change of the roller spacing, opposing the variations of the casting level, of opposing rollers of the strand guide, wherein the control unit comprises at least one observer which is designed in such a way that, based on frequencies of the variations of the casting level, a compensation value for a target value of the roller spacing of the rollers is determined and the actual value of the roller spacing is used as one of the input variables for this observer, in order to compensate for a phase shift and/or amplitude of the actual value of the roller spacing.
As already mentioned in conjunction with the method, it can be provided that the adjustment device is designed for cyclic changes of the roller spacing in a frequency range up to greater than or equal to 0.6 Hz, preferably up to 5 Hz. The adjustment device can comprise at least one hydraulic or electromechanical actuator, such as a hydraulic cylinder or an electrical spindle drive. Of course, the adjustment device can be designed for cyclic changes of the roller spacing in a frequency range from 0 Hz, preferably up to 5 Hz, for example, also using hydraulic or electromechanical actuators, such as a hydraulic cylinder or an electrical spindle drive.
As also already mentioned in conjunction with the method, it can be provided that multiple roller segments each having one or more rollers are arranged on both sides along the strand guide, wherein at least one roller segment is adjustable by means of the adjustment device normally in relation to the strand guide direction.
For example, at least one roller segment can be adjustable in the uppermost, i.e., first segment. In this case, at least one roller segment can be pivotable; or at least one roller segment is adjustable in parallel alignment in relation to an opposing roller segment arranged along the strand guide. The roller segments are preferably adjusted in such a way that no sudden segment transitions (=thickness changes) arise, this is referred to as a “linked method”.
Preference is given to that embodiment where multiple roller segments each having one or more rollers are arranged on both sides along the strand guide, wherein at least the inner roller segment located closest to the mold is pivotable normally in relation to the strand guide direction by means of the adjustment device about the axis of rotation of a roller of this roller segment located closest to the mold.
In accordance with the method variant having two frequency ranges, one variant of the device according to the invention provides that frequencies of the variations of the casting level in a first frequency range are detectable by means of the measuring unit, and these variations can be offset by means of cyclic opposing movements of an inflow unit of the mold, and further frequencies of the variations of the casting level in a second frequency range are detectable by means of the measuring unit and these variations can be offset by means of cyclic opposing change of the roller spacing of rollers of the strand guide by means of the adjustment device, wherein the second frequency range is greater than the first frequency range.
This can again be executed, for example, by means of a first and/or a second observer. The second observer comprises the same components as the first observer and functions similarly, with the difference that it specifies a second compensation value, not the inflow unit for the mold, but rather the adjustment device which is located in—preferably the uppermost segment of—the strand guide.
The method according to the invention or the device according to the invention is applicable to existing strand casting plants having the above-mentioned requirements and represents a significant improvement of the quality of continuously cast steel with a significantly higher casting speed and thus increased productivity. Suppressing highly dynamic effects is enabled by this new type of casting level regulation, for example, highly dynamic bulging at frequencies greater than 0.6 Hz, even when unforeseen operating situations occur, for example as a result of wear or deformation of the adjustment device for the rollers, or simply unwanted changes in the strand thickness or the steel properties.
The invention will be explained in greater detail on the basis of an exemplary embodiment. The drawings are exemplary and are to illustrate the concept of the invention, but are in no way to restrict it or even reproduce it exhaustively. In the figures:
According to
The liquid metal 3 located in the mold is cooled by means of cooling units (not shown), so that it solidifies on walls la of the mold 1 and thus forms a strand shell. A core 6 is still liquid, however. It only solidifies later. The strand shell 5 and the core 6 together form a metal strand 7. The metal strand 7 is supported and drawn out of the mold 9 by means of a strand guide 8. The strand guide 8 is downstream of the mold 1. It comprises multiple roller segments 8a, which in turn comprise rollers 8b. Only a few are shown of the roller segments 8a and the rollers 8b in
The liquid metal 3 forms a casting level 9 in the mold 1. The casting level 9 is to be kept as constant as possible. Therefore
The roller spacings, which correspond to the strand thickness d shown, can be intentionally adapted by means of pivot axis 23 and/or adjustment device 24. This can take place, as shown here in
Possible guide rollers, which are directly connected to the mold and would be arranged above the uppermost roller segment 8a shown here, are not shown in
Alternatively to the pivoting, the left uppermost roller segment 8a, i.e., for example, its outer frame, could be fixed and the right upper roller segment 8a, i.e., for example, its inner frame, could be displaced in parallel normally to the strand guide direction toward the left roller segment 8a and away from it. The roller spacing of all roller pairs thus changes by the same absolute value in each case. This could also be carried out using one or more hydraulic cylinders (distributed along the strand width and/or along the strand guide direction).
In
The control unit 11 implements—see
The control unit 11 furthermore implements a first observer 14. The height h of the casting level 9 and its target value h*, the further signals and a final target position p* for the inflow unit 4 are supplied to the first observer 14. The first observer 14 determines a first compensation value k. The first compensation value k is added to the preliminary target position p′* and the final target position p* is thus determined. The manipulated variable S, using which the inflow unit 4 is activated, is then determined on the basis of the deviation of the actual setting p from the final target position p *. In general, the control unit 11 implements a lower-order position regulator (not shown) for this purpose.
For the sake of good order, it is to be emphasized once again that the first and second observers 14, 25 are not persons, but rather function blocks implemented in the control unit 11.
The difference between the preliminary target position p′* and the final target position p* corresponds to the first compensation value k determined by the first observer 14. Since the first compensation value k is determined by the first observer 14 and it is therefore known to the first observer 14, alternatively to the final target position p*, the preliminary target position p′* can also be supplied to the first observer 14. Because of the circumstance that the first compensation value k is known to the first observer 14, the first observer 14 can thus readily determine the final target position p* from the preliminary target position p′ *. A tapping point 15, at which the (preliminary or final) target position p′*, p* is tapped can thus be located before or after a node point 16 as needed, at which the first compensation value k is added to the preliminary target position p′ *. The tapping point 15 is to be located before a node point 16′, however, at which the pilot control signal pV is added on.
The first observer 14 comprises a determination block 17. The height h of the casting level 9, the further signals, and the final target position p* are supplied to the determination block 17. The determination block 17 comprises a model of the strand casting plant. By means of the model, the determination block 17 determines on the basis of the further signals and the final target position p* an expected height (i.e., computed with model support) for the casting level 9. On the basis of the expected height, the determination block 17 then determines an expected variation value dh (i.e., computed with model support) for the height h of the casting level 9, i.e., the short-term variation. For example, the determination block 17 can perform averaging of the height h of the casting level 9 and subtract the resulting mean value from the expected height. The determined variation value δh thus reflects the expected variation of the height h of the casting level 9. On the basis of the variation value δh, the determination block 17 then determines the first compensation value k.
The procedure previously explained in conjunction with
The secondary signal Z can be a withdrawal force F, using which the metal strand 7 is withdrawn from the mold 1 by the rollers 8b of the strand guide 8. The withdrawal force F is oriented parallel to the draw-off speed v. Alternatively, it can be the draw-off speed v itself. These two alternatives are preferred. However, it is also possible to use, for example, a force signal E′, which is applied to (at least) one of the roller segments 8a of the strand guide 8, as the secondary signal Z. The direction to which the force signal F′ is related is orthogonal to the draw-off speed v. The secondary signal Z can again alternatively be a local strand thickness d, which is measured by means of a measuring unit 21 (see
As already previously mentioned, the second observer 25 comprises identical components as the first observer 14, analyzes frequencies of the bulging after the mold 1, and specifies a second compensation value k′ for the adjustment device 24, namely the compensation value for the target value SET of the roller spacing. This target value SET is a static target value which generally corresponds to the desired strand thickness. A monitoring loop is shown in
This second compensation value k′ is fed to the regulator 28 for roller adjustment, which calculates a manipulated signal 29 for the roller spacing from a target value SET and an actual value ACT and passes this manipulated signal 29 to the adjustment device 24. In addition, the actual value ACT is then also passed to the second observer 25, which takes this into account in the calculation of the second compensation value k′.
Instead of the first observer 14, which controls and/or regulates the inflow unit 4 of the mold 1, another regulating method could be provided.
Only a single regulating method could also be provided, which only controls and/or regulates the adjustment device 24 of the rollers 8b, while the inflow unit 4 of the mold 1 is not used at all for adjusting out the variations of the casting level. This single regulating method could be the second observer 25. In this case, the second observer 25 would generally cover a greater frequency range than in the case of two regulating methods. This frequency range could then cover, for example, the frequencies from 0 to 0.6 Hz, 0 to 1 Hz, 0 to 2 Hz, 0 to 3 Hz, 0 to 4 Hz, or 0 to 5 Hz.
Typical strand thicknesses d during thin slab casting are around 100 mm, and typical casting speeds are between 2 and 6 m/min. The constant roller division over relatively long portions of the strand guide in the transport direction is typically in the range of around 200 mm. Casting speed and roller division then yield the frequencies of the fundamental wave and of the harmonic waves of the oscillations of the casting level which are to be offset by the method according to the invention and the device according to the invention.
1 mold
1
a walls of the mold
2 immersion pipe
3 liquid metal
4 inflow unit
5 strand shell
6 core
7 metal strand
8 strand guide
8
a roller segments
8
b rollers
9 casting level
10 measuring unit
11 control unit
12 adjustment unit
13 casting level regulator
14 first observer
15 tapping point
16, 16′ node points
17 determination block
18, 19 analysis elements
20 temperature sensor
21 measuring unit
22 selection element
23 pivot axis
24 adjustment device
25 second observer
26 controller for frequencies of the second frequency range
27 controller for frequencies of the first frequency range
28 regulator for roller adjustment
29 manipulated signal for roller spacing
ACT actual value of the roller spacing
D complete solidification point
d strand thickness
EST roller spacing calculated in advance
F withdrawal force
F force signal
h height of the casting level
h* target value for the height of the casting level
k first compensation value
k′ second compensation value
p position of the inflow unit
p*, p′* target positions
pv pilot control signal
S manipulated variable for the inflow unit 4
SET target value of the roller spacing
S1, S2 threshold values
T temperature
V draw-off speed
Z secondary signal
δh variation value
| Number | Date | Country | Kind |
|---|---|---|---|
| 21192957.5 | Aug 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/073152 | 8/19/2022 | WO |
