Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
  • B21B1/30—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a non-continuous process
  • B21B1/32—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a non-continuous process in reversing single stand mills, e.g. with intermediate storage reels for accumulating work
  • B21B1/36—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a non-continuous process in reversing single stand mills, e.g. with intermediate storage reels for accumulating work by cold-rolling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
  • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2261/00—Product parameters
  • B21B2261/02—Transverse dimensions
  • B21B2261/04—Thickness, gauge
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2261/00—Product parameters
  • B21B2261/20—Temperature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2275/00—Mill drive parameters
  • B21B2275/02—Speed
  • B21B2275/06—Product speed
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
  • B21B27/06—Lubricating, cooling or heating rolls
  • B21B27/10—Lubricating, cooling or heating rolls externally
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
  • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
  • B21B37/76—Cooling control on the run-out table
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
  • B21B38/006—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product for measuring temperature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
  • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
  • B21B45/0203—Cooling
  • B21B45/0209—Cooling devices, e.g. using gaseous coolants
  • B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
  • B21B45/0218—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes for strips, sheets, or plates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
  • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
  • B21B45/0239—Lubricating
  • B21B45/0245—Lubricating devices
  • B21B45/0248—Lubricating devices using liquid lubricants, e.g. for sections, for tubes
  • B21B45/0251—Lubricating devices using liquid lubricants, e.g. for sections, for tubes for strips, sheets, or plates

Definitions

• the invention relates to a method for cold rolling a strip in a reversing rolling mill using a feedforward control and an online control of a cooling beam. Furthermore, the invention relates to a method for determining the sensitivity of a cooling beam on a reversing rolling mill for cold rolling strip.
• the terms 'inlet side' and 'outlet side' in a reversing rolling mill refer to the strip running direction in a rolling pass currently under consideration, so that between two consecutive rolling passes the attribution of a trade is swapped between 'inlet side' and 'outlet side'.
• a reversing rolling mill considered within the scope of the invention has two coiling devices, whereby the strip is unwound from one of the two draw coilers and wound onto the other draw coiler in each pass. Furthermore, such a reversing rolling mill has cooling and lubrication beams, by means of which the work rolls of the reversing rolling mill and/or the strip can be directly cooled and lubricated by releasing an emulsion to support the strip thickness reduction process and dissipate the resulting forming heat.
• the coolant and lubricant is typically a lubricating emulsion, for example, water with a proportion of up to 5% pure lubricant.
• the emulsion is always applied on the inlet side, viewed in the rolling direction, before passing through a respective stand of the reversing rolling mill, since applying the emulsion on the outlet side after passing through a rolling stand would result in this emulsion being carried over to a subsequent rolling stand or to the respective coiler.
• this omission of emulsion application on the outlet side means that the forming and frictional heat generated in the strip is often not sufficiently dissipated after passing through the rolling stand. Coiling the strip after each pass also ensures that this heat is particularly well preserved - in contrast to a tandem rolling mill, where the strip passes through all stands one after the other without intermediate coiling and is only then wound into a coil.
• a reversing rolling mill considered within the scope of the invention is controlled by a so-called offline model that determines setup values for the reversing rolling mill.
• Setup values are generally default values for the individual sections of the reversing rolling mill for rolling a specific strip.
• the offline model can specify a number of passes through the group of rolling stands of the reversing rolling mill, which are also referred to as 'rolling passes'.
• default values can include, for example, flow rates for cooling and lubrication beams, by means of which lubrication and cooling of the work rolls or the roll gap takes place, as well as specifications for the rolling stands or their drives with regard to thickness reduction and a rolling speed in the individual rolling passes.
• the invention relates to a reversing rolling mill with a group of one or more rolling stands for cold rolling the strip in one or more rolling passes i and at least one coiling device for winding and unwinding the strip on each side of the group of rolling stands before and after the individual rolling passes.
• the reversing rolling mill comprises at least one cooling and lubricating beam for applying a cooling and lubricating agent on the inlet side on each side of each individual rolling stand.
• the reversing rolling mill comprises at least one cooling beam on at least one side between the group of rolling stands and the coiling device. The cooling beam(s) are for applying a cooling agent to the underside of the strip.
• the application of coolant to the underside of the strip serves to achieve a temperature change ⁇ T in the strip.
• the term 'side' refers to a vertical plane through a rolling stand, with the strip passing essentially horizontally through the rolling stand during rolling.
• the group of rolling stands may comprise only one rolling stand, but it may also comprise two rolling stands (double reversing stand) or even more.
• the key point is that the strip passes through the group of rolling stands as a whole in an alternating (horizontal) direction, so that in two consecutive rolling passes, the entry and exit directions of the strip are reversed with respect to the individual rolling stands.
• strip rolled in a reversing mill becomes significantly hotter than if it were rolled in a tandem mill with the same degree of deformation.
• Strip temperatures above 160°C are particularly undesirable, as this can have a negative impact on strip quality and place special demands on the equipment used.
• the oil from the emulsion used burns on an overly hot strip surface, leaving stains.
• Roll gap lubrication is also negatively affected, as the oil in the emulsion loses viscosity.
• Flatness control becomes difficult when the strip is too hot.
• the corresponding coil deposits suffer from high coil temperatures and wear out more quickly.
• coils that are too hot must cool down before they can be processed further, which reduces the throughput of the reversing mill in question.
• a cooling device for the underside of a strip during rolling in a cold rolling mill wherein the strip underside is subjected to low-pressure turbulence cooling.
• a cooling box for a strip in a cold rolling mill is also from the JP S61 242715(A ).
• the strip passes through the cooling box and is cooled on its top and bottom surfaces by cooling water.
• the cooling box forms a narrow flow channel for the cooling water on both the top and bottom surfaces of the strip and has corresponding sealing rollers that seal the cooling box against the escape of cooling water.
• the WO 2014/095268 A1 To improve heat transfer between a strip-shaped rolled stock and a cooling medium applied to it, proposes a cooling device with a cooling chamber extending in the direction of strip travel, which extends the exposure time of the cooling medium.
• the supply of the cooling medium can be regulated depending on various parameters, such as the temperature of the rolled stock or the residual cooling medium remaining on the rolled stock after passing through the cooling device.
• the WO 2021/048038 A1 It is known to specify a temperature window for a rolled stock during cold rolling in a rolling mill with several rolling stands and to ensure that the rolled stock temperature remains within the temperature window during rolling by means of various control and regulation measures.
• the measures include heating the rolled stock before a rolling pass, cooling and lubricating work rolls or the rolled stock itself using appropriate cooling and lubrication beams, creating an appropriate pass schedule distribution to take into account the forming heat generated during rolling, and controlling and regulating a rolling speed to take into account the frictional power losses generated in a rolling stand.
• the effect of these control and regulation measures on the rolled stock temperature can be simulated in advance, i.e.
• the setup values for the respective sections of the cold rolling mill can be adjusted accordingly.
• the temperature of the rolled stock can be measured during rolling and a control or regulation measure can be adjusted online.
• the object of the present invention is therefore to prevent undesirably high temperatures during strip rolling in a reversing rolling mill using simple structural and control-related means without negatively impacting throughput. Furthermore, the determination of target values for maintaining a specified maximum temperature for the strip to be rolled should be simplified.
• a maximum temperature T max is first specified for the strip in the form of a forward control of the cooling beam before at least one, preferably before all rolling passes i, and a first setup value ⁇ i for a flow rate ⁇ of coolant for all cooling beams is set to a value 0.
• the cooling beam(s) located on the inlet side of the group of rolling stands always remain inactive in each rolling pass i.
• the maximum temperature T max can, for example, be based on empirical values with regard to strip cracks during rolling and can be selected depending on the material composition of the strip and is preferably in a range of 120°C to 160°C.
• the sensitivity ⁇ has the meaning of a temperature difference that is caused by the activated, outlet-side cooling beam(s) as a function of at least its(their) flow rate ⁇ in the strip.
• the sensitivity ⁇ is assumed to be a previously known functional relationship between the temperature change ⁇ T induced in the strip and at least the flow rate ⁇ and a strip speed v B.
• the strip speed v B can also be assumed to be known for the rolling pass i, since it is determined in advance by an offline model, for example, as part of the pass plan creation.
• the strip speed v B can be a strip inlet speed v i,in or a strip outlet speed v i,ex of the strip rolled in the respective rolling pass i.
• the functional relationship can, for example, be an empirically determined relationship between the temperature change ⁇ T induced in the respective belt and the set flow rate ⁇ and the belt speed v B.
• the sensitivity ⁇ can also be determined on the basis of a physical model as a function between the induced temperature change ⁇ T and the set flow rate ⁇ and the belt speed v B.
• the setup value ⁇ i can, for example, be determined such that the strip is cooled down by the activated cooling beam exactly to the maximum temperature T max , i.e. that the characteristic temperature T c of the strip after it has passed the cooling beam corresponds exactly to the maximum temperature T max .
• the setup value ⁇ i can also be selected such that the characteristic temperature T c of the strip after it has passed the cooling beam is always below the maximum temperature T max , particularly in the case of an only roughly known functional relationship between the temperature change ⁇ T on the one hand and the flow rate ⁇ and the strip speed v B on the other hand.
• the specification of the first setup value ⁇ i is carried out, for example, by transmission from a separate calculation unit to a control unit of the reversing rolling mill, which controls its individual sections (such as the rolling stands, the coiling devices, the cooling and lubrication beams as well as the cooling beam(s).
• the method according to the invention only the setup values for the chilled beams located on the outlet side are stored in a
• the relevant rolling pass i is changed, but not the other setup or default values for the remaining sections of the reversing rolling mill; in particular, a pass schedule for the strip remains unchanged.
• the cooling beam(s) on the exit side thus act merely as an additional actuator, which is why the method according to the invention is particularly well suited as a retrofit solution for an existing reversing rolling mill: such a mill can, for example, be retrofitted with additional cooling beams for cooling an outgoing strip at relatively low investment expense, whereby an existing offline model, which is already adapted to the technological conditions of the mill, does not have to be modified.
• the cooling beam(s) concerned on the outlet side are only activated when the maximum temperature T max is exceeded, which is why the method according to the invention represents a minimal, independent control-technical intervention in the operation of the reversing rolling mill, which advantageously only minimally increases the complexity of the plant control.
• the strip thickness d B can again be assumed to be known for the rolling pass i - analogous to the strip speed v B - where the strip thickness d B can be a strip entry thickness d i,in or a strip exit thickness d i,ex with respect to one of the rolling stands of the reversing rolling mill.
• the setup value ⁇ i is determined such that the sensitivity ⁇ corresponds to the temperature change ⁇ T in the strip according to equation (1).
• the strip speed v B and the strip thickness d B of the strip rolled in the respective rolling pass i can be taken into account, so that the temperature change ⁇ T can advantageously be set very precisely.
• cooling of the strip can be carried out particularly energy-efficiently by appropriately determining the setup value ⁇ i and cooling it only to such an extent that the temperature change ⁇ T essentially corresponds to the difference between the characteristic temperature T c and the maximum temperature T max , so that the cooling only compensates for the exceedance of the specified maximum temperature T max .
• the characteristic temperature T c is determined on the basis of an empirical model or a physical model.
• the characteristic temperature T c can be quickly determined or interpolated, for example, from input parameters, including material properties, parameters of the pass schedule and production parameters (including, for example, a strip inlet speed v i,in and/or a strip outlet speed v i,ex and/or a rolling force in the rolling pass i) of a respective strip, if for respective areas of the mentioned Input parameters corresponding values for the characteristic temperature T c are available, for example, in the form of previously determined calculation values or in the form of empirical values or operator inputs.
• a characteristic temperature T c can advantageously be calculated directly and particularly accurately on the basis of the same or similar input parameters; in this context, for example, the WO 2021/048038 A1 to determine the exit temperature of a rolling stock behind a rolling stand before the actual rolling process on the basis of the entry temperature of the rolling stock in conjunction with modelable physical heat flows.
• the characteristic temperature T c is determined by means of a physical model under the assumption that the flow rate ⁇ is zero, based on a predetermined strip exit speed v i,ex and a predetermined strip exit thickness d i,ex for the strip and based on two setup values ⁇ i for the at least one cooling and lubricating beam, starting from an initial temperature T 0 of the strip, a temperature distribution ⁇ of the strip is determined by solving a heat conduction equation of the physical model in a region B that comprises at least a section of the strip. The characteristic temperature T c is then derived or determined from the temperature distribution ⁇ .
• the characteristic temperature T c that the strip has or would have after the rolling pass with the exit-side cooling beam deactivated can advantageously be predicted particularly precisely, so that any necessary application of coolant to the strip can be particularly targeted and adjusted.
• the characteristic temperature T c can, for example, be a function coordinate of the temperature distribution ⁇ can be the averaged temperature value of the strip or a temperature value at a strip surface.
• the temperature distribution ⁇ is a function of the temperature within the strip as a function of the spatial coordinates.
• the coordinate system of the heat conduction equation is not fixed with respect to the strip itself, which is moved through the rolling stands in the rolling pass i.
• the rolling speeds relative to the individual rolling stands are only included as parameters in the heat conduction equation or in the boundary conditions of the region B.
• the heat conduction equation can therefore be solved in the considered region B with appropriate initial and boundary conditions for the strip.
• the initial temperature T 0 for the first rolling pass for example, a value corresponding to the ambient temperature can be used, since the strips in question are usually stored for a longer period in the reversing rolling mill before rolling.
• a constant temperature distribution of the strip upon entry into the considered area B can be assumed, since the temperature quickly evens out in the strip thickness direction during the winding processes between the rolling passes.
• the characteristic temperature value T c determined for the immediately preceding rolling pass can be used as the initial temperature T 0 , since the strip is wound into a coil on the reversing rolling mill immediately after each rolling pass and in this state negligible heat is released to the environment during the period between two rolling passes.
• the initial temperature T 0 can also be set based on empirical values, since the average strip temperature usually approaches an upper saturation temperature after just a few rolling passes: therefore, an initial temperature T 0 for further rolling passes can be obtained with a good approximation, for example, from the temperature measurement of a strip with a comparable final thickness immediately after its rolling on the reversing rolling mill.
• the cooling and lubricating agent applied during rolling by at least one cooling and lubricating beam dissipates heat from the work rolls or from the strip and is included in the heat conduction equation as a boundary condition via corresponding heat transfer coefficients. Furthermore, the heating due to the plastic deformation of the strip as well as the friction between the strip and the work rolls in the roll gap must be considered in the form of so-called source terms. The consideration of such boundary conditions and source terms is, for example, evident from the WO 2021/048038 A1 or from F. Hell: Fundamentals of Heat Transfer, VDI-Verlag 1982, ISBN number 978-3-18-400529-0, Chapter 2.2 and 2.3, formulas (81) to (83) in conjunction with Figure 25 and Tables VI and VII.
• the region B in which the heat conduction equation is solved extends, viewed in the strip travel direction, at least from the beginning of a first effective region W of the first cooling and lubricating beam on the inlet side to at least the end of a second effective region W' of the last cooling beam on the outlet side.
• the first and second effective regions W, W' therefore essentially comprise those regions in which the cooling and lubricating agent or the coolant comes into contact with the surface of the strip.
• Both regions are spatially limited because the beams only have a limited spray width in the strip travel direction, because the cooling and lubricating agent is only applied on the inlet side and is therefore only transported by the strip to the rolling stands, from where it is laterally and because the coolant is only applied to the underside of the belt, where contact with the belt surface is also spatially limited in this area due to the effect of gravity.
• the work rolls of the rolling stands are also included in the heat conduction equation.
• the volume of the strip considered in region B the volume of the work rolls themselves, or rather, their heating, is also taken into account.
• the heat conduction equation is applied as a one-dimensional differential equation and the temperature distribution ⁇ is determined in the thickness direction of the strip. Since the thickness d of a strip rolled on the respective reversing rolling mill is usually (between 0.1 mm and 7 mm) and thus significantly smaller than its width (at least 600 mm) and its dimension along the considered area B (several meters), heat flows in the longitudinal and width directions of the strip can be neglected to a good approximation.
• the computational effort required to determine the temperature distribution ⁇ can be kept low.
• a maximum temperature T max for the strip is specified before at least one of the rolling passes i.
• an instantaneous outlet temperature T i,ex " of the strip is recorded cyclically, i.e. repeatedly at respective time intervals ⁇ t , in each case by means of a temperature recording device.
• a first setup value ⁇ i for the outlet-side cooling beam(s) is determined in the respective time interval ⁇ t based on an aforementioned sensitivity ⁇ , which in turn is known as a function of at least the flow rate ⁇ and a strip speed v B known for the rolling pass i.
• the strip speed v B can in turn be a strip speed determined in advance, for example as part of the pass plan creation.
• This method according to the invention advantageously enables an even more precise setting of an outlet-side strip temperature because, instead of a mathematically determined temperature value, an instantaneous temperature value T i,ex " - i.e. a temperature value determined or recorded for the respective moment - is used to determine the flow rate ⁇ . Because the recording of the outlet temperature and the corresponding adjustment of the flow rate of the outlet-side cooling beam(s) takes place periodically at time intervals ⁇ t , any changes in the rolling conditions, such as a changing strip inlet temperature or an irregular lubricating and cooling effect of the cooling and lubricating beam(s) over the strip length, can be immediately controlled.
• the time intervals ⁇ t preferably have an interval duration of a maximum of 10 ms, whereby the adjustment of the flow rate ⁇ to the instantaneous outlet temperature T i,ex " advantageously takes place particularly promptly.
• the sensitivity ⁇ is additionally known as a functional relationship with a strip thickness d B .
• the strip thickness d B can again be assumed to be known for the rolling pass i - analogous to the method according to the invention relating to forward control of a cooling beam. Accordingly, in this embodiment, the first setup value ⁇ i determined in such a way that the sensitivity ⁇ corresponds to the temperature change ⁇ T in the band according to equation (1). and can therefore advantageously be adjusted very precisely.
• FIG 2A , FIG 2B and FIG 4 cold rolling mill 1 shown as in FIG 1 can be designed, but can also have a different number of rolling stands 10, 11, coiling devices 30, 31, 32, cooling beams 20, 21 or cooling and lubricating beams 13, 14, 13', 14', without affecting the method described with reference to the respective figure.
• FIG 1 shows a cross-section through a reversing rolling mill 1, which is designed as a double reversing rolling mill and comprises a group of two rolling stands 10 and 11, each having an upper work roll 12 and a lower work roll 12' as well as an upper and a lower backup roll 18 and 18' respectively.
• the upper and lower work rolls 12 and 12' of the rolling stands 10 and 11 each form a roll gap through which the strip 2 is passed in one or more rolling passes along a so-called pass line 4 for the purpose of thickness reduction.
• the reversing rolling mill 1 has a coiling device 30.
• two further coiling devices 31 and 32 of the reversing rolling mill 1 are arranged.
• a cooling beam 20 and 21 is arranged in front of and behind the rolling stands 10 and 11, respectively, for discharging a coolant 22 onto a bottom side 2' of the strip 2.
• the cooling beam 20 on the outlet side is currently active, whereby in principle the contact area between the coolant 22 emitted by the cooling beam 20 or 21 and the underside 2' of the belt 2 forms a second effective area W' of the respective cooling beam 20, 21.
• a respective temperature detection device 40 or 41 is arranged at a distance a behind the end of the second effective area W' of the respective cooling beam 20, 21 above the belt 2.
• a deflection roller 35 is arranged below the fitting line 4 behind the cooling beam 20 or 21.
• the strip 2 is guided downwards by the respective deflection roller 35 toward the corresponding coiling device 30, 31, 32, whereby any adhering residues of coolant 22 applied to the strip by means of the cooling beam 20 or 21 are stripped off.
• FIG 2A shows an embodiment of the method according to the invention relating to a forward control on a reversing rolling mill 1 according to FIG 1 ; for reasons of clarity, only the most important trades are provided with identifiers.
• the tape running direction 5 runs in the FIG 2A rolling pass i shown from left to right: the strip 2 is unwound from the coiler 30 with a strip thickness d B , which is identical to a strip inlet thickness d i,in , enters the group of rolling stands 10, 11 with a strip inlet speed v i, in or exits it again with a strip outlet speed v i,ex and a strip outlet thickness d i,ex and is wound up on the closer coiler 31; the respective directions of rotation of the coiler 30 and 31 are indicated by corresponding arrows.
• the coiler 32 is on the FIG 2A shown rolling pass, but can, for example, already be loaded with a strip 3 to be subsequently rolled.
• the calculation unit 60 can automatically determine the corresponding strip outlet speed v i,ex and strip outlet thickness d i, ex, for example, via the pass reduction in the relevant rolling pass i.
• the setup value ⁇ i for the outlet-side chilled beam 21 is determined using a sensitivity ⁇ , whereby according to the invention a characteristic Temperature T c of band 2 has been determined which exceeds a maximum temperature T max .
• FIG 2B shows an embodiment of the method according to the invention relating to an online control on a reversing rolling mill 1 according to FIG 1 ; for reasons of clarity, only the most important trades are given identifiers. Furthermore, only the differences to the Fig. 2A described procedures.
• an offline model 100 is implemented on a separate calculation unit 60, which determines second setup values ⁇ i - again comprising a strip entry speed v i,in and/or a strip exit speed v i,ex as well as a strip entry thickness d i,in and/or a strip exit thickness d i,ex in the rolling pass i - for at least one rolling pass i (again symbolized by curved brackets) for the individual sections of the reversing rolling mill 1 and transmits these to a control unit 50 of the reversing rolling mill 1.
• a maximum temperature T max for the strips is specified.
• ⁇ i As opposed to FIG 2A no first setup value ⁇ i is determined in advance for the cooling beams 20 and 21, but instead, in the considered rolling pass i, a current outlet temperature T i,ex " of the strip 2 is recorded cyclically at time intervals ⁇ t by means of a temperature recording device 40, 41 and transmitted to the control unit 50: in the FIG 2B
• the temperature detection device 40 would measure an inlet-side temperature of the strip 2, which, however, is not used further in the specific case, which is why the corresponding connecting arrow to the control unit 50 is shown in dashed lines.
• the current outlet temperature T i,ex " is compared with a given maximum temperature T max : if the current outlet temperature T i,ex " is greater than the maximum temperature T max (which is the case for the FIG 2B shown case applies), a default value ⁇ i for a flow rate ⁇ of coolant 22 through the cooling beam 21 located on the outlet side, using a sensitivity ⁇ , which is known as a functional relationship between the temperature change ⁇ T caused in the strip 2 by the activated cooling beam 21 and the flow rate ⁇ set on the cooling beam 21, the strip outlet speed v i,ex and the strip outlet thickness d i,ex .
• the corresponding strip outfeed speed v i,ex and strip outfeed thickness d i,ex can be determined via the pass reduction in the respective rolling pass i.
• the repeated, cyclical determination of the set value ⁇ i in each time interval ⁇ t is in FIG 2B indicated by a corresponding round arrow symbol within the control unit 50.
• control unit 50 sets the flow rate ⁇ of coolant 22 through the outlet-side cooling beam 21 to the determined preset value ⁇ i , while the inlet-side cooling beam 20 remains deactivated during the entire rolling pass i and therefore in FIG 2B is shown in dashed lines.
• a current strip outlet speed v i,in " or current strip outlet speed v i,ex " can also be used to determine the default value ⁇ i , which is FIG 2B indicated by symbols in curly brackets.
• FIG 3A shows a flow chart for an embodiment of a method according to the invention relating to a feedforward control.
• second setup values ⁇ i are determined by an offline model 100 for the individual sections of the reversing rolling mill 1 - excluding the cooling beams 20, 21.
• a sensitivity ⁇ is known which describes the effect of the cooling beams 20, 21 of the considered rolling pass in the reversing rolling mill 1 on a temperature change ⁇ T of the strip 2 cold-rolled therein due to the effect of the outlet-side cooling beam 20, 21.
• the sensitivity ⁇ depends at least on a flow rate ⁇ of coolant 22 applied to the underside 2' of the strip 2, which corresponds to the specified value ⁇ i to be determined for the respective cooling beam 20, 21, and a strip speed v B - specifically on the strip exit speed v i,ex , with which the strip 2 passes the respective exit-side cooling beam(s) 20, 21 after passing through the group of rolling stands 10, 11.
• a functional dependence of the sensitivity on a strip thickness d B - specifically on the strip outlet thickness d i,ex , - is assumed, which is also assumed to be known.
• a maximum temperature T max is specified for a rolling pass i under consideration and a first setup value ⁇ i for a flow rate ⁇ of coolant 22 through the at least one outlet-side cooling beam 20, 21 is initially set to a value 0: the outlet-side cooling beam 20, 21 is thus initially assumed to be inactive.
• a characteristic temperature T c of the strip 2 - e.g. a temperature at the bottom 2' or at the top 2" of the strip 2 - is determined based on an empirical model 110.
• T c a characteristic temperature at the bottom 2' or at the top 2" of the strip 2 - is determined based on an empirical model 110.
• the effect on the temperature of the strip in the rolling pass i with deactivated (outlet-side) cooling beams is simulated based on empirical values.
• the first The setup value ⁇ i for the outlet-side cooling beam 20, 21 in the considered rolling pass i is determined based on the sensitivity ⁇ such that the sensitivity ⁇ corresponds to the temperature change ⁇ T induced in the strip 2, which in the specific embodiment is assumed to be the difference between the characteristic temperature T c and the maximum temperature T max .
• a larger value for the temperature change ⁇ T can be selected, which would result in a stronger cooling of the strip 2 below the maximum temperature T max .
• the determined first setup value ⁇ i for the outlet-side cooling beam(s) 20, 21 are transmitted together with the second setup values ⁇ i, for example, to a plant control system 50 as soon as the rolling pass i is carried out.
• the transmission of data is in FIG 3A symbolized by thin arrows.
• the optional execution of the last step depending on the exceedance of the maximum temperature T max is shown in FIG 3A represented by corresponding dashed arrows.
• an outlet-side cooling beam 20, 21 is only activated (and subsequently the strip 2 is supplied with coolant 22) when a previously determined characteristic temperature T c exceeds the predetermined maximum temperature T max ; all other settings for the reversing rolling mill corresponding to the second setup values ⁇ i remain unchanged.
• FIG 3B shows a flow chart for an embodiment of a method according to the invention relating to a feedforward control which determines a characteristic temperature Tc based on a physical model 120. In the following, only the differences to FIG 3A received.
• an initial temperature T 0 is assumed, which the strip 2 reaches in the considered rolling pass i immediately before entering the group of rolling stands 10, 11. Then, starting from the assumed initial temperature T 0 of belt 2, a temperature distribution ⁇ (in the sense of a spatial temperature distribution) of belt 2 is determined using the second setup values ⁇ i : this is again done under the assumption of an inactive outlet-side cooling beam 20, 21 (corresponding to the fact that the first setup value ⁇ i is initially set to the value 0).
• the physical model 120 comprises a heat conduction equation for a temperature distribution ⁇ of the strip 2, wherein the heat conduction equation is solved in a region B for which suitable physical boundary conditions are applied for the considered rolling pass i.
• boundary conditions are defined within the framework of FIG 4 described in more detail.
• a characteristic temperature T c of the strip 2 - e.g., a temperature at the bottom 2' or at the top 2" of the strip 2 - is derived from the temperature distribution ⁇ .
• FIG 3C shows a flowchart for an embodiment of a method according to the invention relating to online control. Again, only the differences to FIG 3A received.
• the second setup values ⁇ i determined by an offline model are transmitted once before the start of the rolling pass i to the control unit 50.
• an outlet temperature T i,ex " of the strip 2 is recorded cyclically, i.e. repeatedly at time intervals ⁇ t, by means of a temperature recording device 40, 41. If the recorded outlet temperature T i,ex " exceeds the predetermined maximum temperature T max , a first setup value ⁇ i for the flow rate ⁇ of coolant 22 through the cooling beam(s) 20, 21 on the outlet side in the rolling pass i under consideration is determined based on a previously known sensitivity ⁇ ; otherwise, the first setup value ⁇ i is set to the value 0. The value ⁇ i determined in this way is again transmitted to the control unit in each time interval ⁇ t 50 and the outlet temperature T i,ex " is recorded again in the following time interval.
• the first setup value ⁇ i is determined based on the sensitivity ⁇ in such a way that the sensitivity ⁇ corresponds to the temperature difference between the recorded outlet temperature T i,ex " and the specified maximum temperature. Again, alternatively, a larger value can be selected for this temperature difference, which would result in a stronger cooling of the belt 2 below the maximum temperature T max .
• the sensitivity ⁇ is known as a functional relationship between the flow rate ⁇ of coolant 22 through the cooling beam 20, 21, a strip speed v B (specifically the strip outlet speed v i,ex ) and additionally the strip outlet thickness d i,ex .
• the strip run-out speed v i,ex and the strip run-out thickness d i,ex are determined for the rolling pass i, for example, by the offline model 100 and are therefore known.
• an instantaneous value v i,ex " recorded directly in the respective time interval ⁇ t can also be used as the argument value of the sensitivity ⁇ (in FIG 3C symbolized by curly brackets), which allows a particularly precise determination of the first setup value ⁇ i .
• FIG 4 shows a section of a reversing rolling mill 1, to which the method according to the invention relating to a forward control is applicable and which comprises only one rolling stand 10 with two work rolls 12, 12' and two backup rolls 18, 18'.
• the active inlet-side cooling and lubrication beams 13, 13', 14, 14' are shown, since the corresponding outlet-side cooling and lubrication beams, as in FIG 1
• the boundary conditions of the method according to the invention relating to a feedforward control are explained in particular, which determines the characteristic Temperature Tc was determined using a physical model 120.
• these boundary conditions can easily be applied to a multi-stand reversing rolling mill by a person skilled in the art.
• coolant and lubricant 16 is discharged onto the work rolls 12, 12' or in the direction of the roll gap according to two setup values ⁇ i .
• the coolant and lubricant 16 applied by the upper cooling and lubrication beams 13, 14 onto the upper work roll 12 or into the roll gap forms a backed-up liquid volume on the upper side 2" of the strip 2, which is diverted transversely from the strip 2 and extends in the strip travel direction over a first effective area W.
• the coolant and lubricant discharged by the lower cooling and lubrication beam 13' in the direction of the roll gap only comes into contact with the underside 2' of the strip 2 for a relatively short time due to the effect of gravity, where it forms a third effective area W".
• the area B is indicated, in which a heat conduction equation of the physical model 120 is solved.
• the area B includes, in addition to a longitudinal section of the strip 2, those areas of the work rolls 12, 12' that are taken into account when solving the heat conduction equation.
• the strip 2 enters the rolling stand 10 from the right in the strip running direction 5 with a strip entry thickness d i,in and is rolled therein to a strip exit thickness d i,ex .
• a temperature distribution ⁇ of the strip 2 in the thickness direction d B is determined, which is shown top left in FIG 4 is indicated.
• the heat conduction equation includes that section of the strip 2 which begins in the strip running direction 3 in front of the inlet-side cooling and lubricating beams 13, 13', 14, 14' and ends on the outlet side behind the second effective area W' of the outlet-side cooling beam 20, whereby the cooling beam 20 is used for the solution According to the heat conduction equation, it is not active.
• region B includes the thickly outlined zones of the upper and lower work rolls 12 and 12', which only circumscribe a ring-segment-shaped region of the work rolls 12, 12'.
• the surfaces of the work rolls 12, 12' exposed to coolant and lubricant 16 on the inlet side, as well as the third effective area W" on the underside of the strip, are in FIG 4 marked with the identifier 92: there, the coolant and lubricant 16 forms only a thin liquid film on the respective surface, so that a heat transfer coefficient ⁇ corresponding to a laminar boundary layer of coolant and lubricant 16 can be applied as a boundary condition in the heat conduction equation.
• a heat transfer coefficient ⁇ ' corresponding to a turbulent boundary layer of coolant and lubricant 16 is applied.
• Heat transfer coefficients ⁇ , ⁇ ' for such configurations are known, for example, from formulas (81) to (83) of the aforementioned book by F. Hell (Fundamentals of Heat Transfer).
• thermal insulation is applied as a boundary condition for the radially extending sections of the ring-segment-shaped areas of the work rolls 12, 12' as well as for the interface of the strip 2 emerging from the area B (in FIG 4 designated 94).
• the heat conduction equation is uniquely determined by the initial value and boundary conditions 90 to 95 described, and a temperature distribution ⁇ of the strip can be determined in the region B, particularly in the direction of the strip thickness d B .

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• 2024
  • 2024-02-12 EP EP24157137.1A patent/EP4599953A1/fr active Pending
• 2025
  • 2025-02-07 WO PCT/EP2025/053174 patent/WO2025172170A1/fr active Pending

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