EP4028181B1 - Cold rolling stock in a rolling mill train with multiple roll stands - Google Patents

Description

The invention relates to the cold rolling of a rolling stock in a rolling train with a plurality of roll stands.

In a roll stand, a rolling stock, usually a metallic rolled strip, is rolled in a roll gap between two work rolls of the roll stand in order to reduce the thickness of the rolling stock. A plurality of roll stands are often arranged in a so-called rolling train, through which the rolling stock passes in succession in order to successively reduce the thickness of the rolling stock. The rolling of the rolling stock in one of the roll stands is referred to as a rolling pass. In a rolling train with several roll stands, several rolling passes are carried out one after the other. The reduction in the thickness of the rolling stock in a rolling pass is referred to as reduction of the rolling pass. During cold rolling, the rolling stock is rolled at a rolling stock temperature below the recrystallization temperature.

Among other things, for applications in the technical field of electromobility, electrical sheets with a high proportion of silicon are becoming more and more important. The high degree of brittleness of these electrical sheets can lead to numerous difficulties, especially during cold forming, such as frequent strip tears and therefore unstable production conditions during cold rolling. By increasing the rolling stock temperature of the rolling stock, its brittleness can be reduced.

On the other hand, the rolling stock temperature during cold rolling must not exceed the recrystallization temperature of the rolling stock due to the principle involved. In addition, the rolling stock temperature during cold rolling should generally also be limited for other reasons. For example, in cold rolling mostly a lubricant is applied to the work rolls of the roll stands and/or to the rolled stock to reduce friction between the rolled stock and the work rolls. The lubricant is or contains a rolling oil that can crack at high temperatures, for example above 200°C. Furthermore, the cold rolling can be followed by processing steps for processing the cold-rolled rolling stock, for example coating the rolling stock, for which an excessively high rolling stock temperature is disadvantageous (in the case of coating the rolling stock, for example, reduced adhesion of the coating). Furthermore, a high rolling stock temperature can lead to increased wear of plant equipment, for example plastic-coated deflection rollers for the rolling stock or deposit saddles for the rolled stock, or to thermal deformation of the work roll contour in the axial direction, which impairs the flatness of the rolling stock.

The JP H01 218710 A proposes heating a rolled strip entering a cold rolling stand to a temperature between 100°C - 500°C and applying lubricant to the work rolls of the rolling stand on the entry side and water as a coolant on the exit side. On the one hand, the heating is intended to reduce the deformation resistance of the rolled strip, and on the other hand, the application of cooling water is intended to prevent destruction of the lubricating film on the work rolls due to overheating and excessive thermal deformation of the work rolls.

The invention is based on the object of specifying a method and a rolling train for cold-rolling a rolling stock with a plurality of roll stands, which are improved with regard to the tempering of the rolling stock during rolling and/or after rolling.

The object is achieved according to the invention by a method having the features of claim 1 and a rolling train having the features of claim 12.

Advantageous configurations of the invention are the subject matter of the dependent claims.

• Erwärmen des Walzguts vor dem ersten Walzstich auf eine Einlauftemperatur,
• Kühlen der Arbeitswalzen wenigstens eines Walzgerüsts durch Aufbringen eines Walzenkühlmittels auf die Arbeitswalzen, wobei ein Walzenkühlmittelstrom und/oder ein Walzenkühlmitteldruck des Walzenkühlmittels gesteuert oder geregelt wird,
• Kühlen des Walzguts zwischen wenigstens zwei aufeinander folgenden Walzstichen durch Aufbringen eines Walzgutkühlmittels auf das Walzgut, wobei ein Walzgutkühlmittelstrom und/oder ein Walzgutkühlmitteldruck des Walzgutkühlmittels gesteuert oder geregelt wird,
• Aufbringen eines Schmiermittels auf die Arbeitswalzen oder/und auf das Walzgut bei wenigstens einem Walzstich, wobei ein Schmiermittelstrom und/oder ein Schmiermitteldruck des Schmiermittels gesteuert oder geregelt wird,
• Erstellen und Umsetzen einer Stichplanverteilung für die Stichabnahmen der einzelnen Walzstiche, und
• Steuern oder Regeln einer Walzgeschwindigkeit, mit der das Walzgut die Walzstraße durchläuft.

In the method according to the invention for cold-rolling a rolling stock in a rolling train with a plurality of roll stands through which the rolling stock passes in succession, an upper limit temperature and/or a lower limit temperature for a rolling stock temperature of the rolling stock is specified for at least one selected rolling pass, in particular for each rolling pass and the rolling stock temperature is controlled and/or regulated by the following control or regulation measures in such a way that the rolling stock temperature in each selected rolling pass does not exceed the upper limit temperature specified for the rolling pass and/or does not fall below the lower limit temperature specified for the rolling pass:

• heating of the rolling stock to an entry temperature before the first rolling pass,
• Cooling of the work rolls of at least one roll stand by applying a roll coolant to the work rolls, with a roll coolant flow and/or a roll coolant pressure of the roll coolant being controlled or regulated,
• Cooling of the rolling stock between at least two successive rolling passes by applying a rolling stock coolant to the rolling stock, with a rolling stock coolant flow and/or a rolling stock coolant pressure of the rolling stock coolant being controlled or regulated,
• Application of a lubricant to the work rolls and/or to the rolling stock in at least one rolling pass, with a lubricant flow and/or a lubricant pressure of the lubricant being controlled or regulated,
• Creation and implementation of a pass plan distribution for the pass reductions of the individual rolling passes, and
• Controlling or regulating a rolling speed at which the rolling stock runs through the rolling train.

The invention therefore provides for the rolling stock temperature to be monitored in at least one pass so that it does not exceed a pass-specific upper limit temperature and/or does not fall below a pass-specific lower limit temperature. As a result, breakdowns such as strip tears can generally be reduced and the throughput of a rolling train can thus be increased. In particular, the production conditions for the cold rolling of critical rolling stock, such as electrical steel sheets with a high silicon content, are being improved or even created in the first place. Furthermore, by suitably specifying the limit temperatures, the final temperature of the rolling stock at the exit of the rolling train can be specifically influenced, as a result of which flexible further processing of the cold-rolled rolling stock can be achieved. Furthermore, by suitably specifying the limit temperatures, an inlet temperature of the rolling stock that is required at the entrance to the rolling train can be minimized, thereby saving energy for heating the rolling stock before the first rolling pass. Furthermore, the system equipment can be protected by a suitable specification of the limit temperatures in order to reduce its wear.

The control or regulation measures mentioned are particularly suitable for influencing the rolling stock temperature during cold rolling. For example, heating the rolled stock before the first rolling pass reduces the brittleness of the rolled stock and thus the risk of strip tears in the rolled stock.

Cooling work rolls and/or the rolling stock between rolling passes counteracts heating of the work rolls and the rolling stock during cold forming of the rolling stock. In the case of roll cooling by means of roll coolant dispensed onto the work rolls, the amount of heat removed from the work rolls can be determined from the modeling of the heat transfer (determination of the heat transfer coefficient between a roll surface and the roll coolant) and is, for example out of F. Hell: Fundamentals of heat transfer, VDI-Verlag 1982, ISBN number 978-3-18-400529-0, pages 77-85 known. Alternatively, the heat transfer coefficient can also be determined empirically as a function of the roll coolant flow and the roll coolant pressure (so-called table model). From this, the temperature of the work rolls can be determined, from which in turn the heat flow between the rolling stock and the work rolls - i.e. the amount of heat given off by the rolling stock to the work rolls - in the roll gap can be determined and regulated by appropriate control or regulation of the roll coolant flow and/or the roll coolant pressure , so that the rolling stock temperature in the roll gap can be set in a targeted manner. In the same way, when cooling the rolling stock by means of rolling stock coolant applied to the rolling stock, the amount of heat removed from the rolling stock to the rolling stock coolant can be determined by modeling the heat transfer, if the flow of rolling stock coolant and the rolling stock coolant pressure are known, either by a model-based determination mentioned above as an example, or by an empirical determination of the heat transfer coefficient between the rolling stock coolant and the surface of the rolling stock to which it acts as a function of the rolling stock coolant flow and the rolling stock coolant pressure. From this, in turn - by appropriate control or regulation of the rolling stock coolant flow and/or the rolling stock coolant pressure - the heat flow from the rolling stock and consequently the temperature of the rolling stock can be specifically adjusted in those areas of the rolling mill in which the rolling stock is directly exposed to rolling stock coolant.

Applying a lubricant to the work rolls and/or to the rolling stock during at least one rolling pass reduces the friction between the rolling stock and the work rolls and thus counteracts heating of the rolling stock and/or the work rolls. The more lubricant applied, the lower the frictional power loss during rolling. Latter is basically calculated from an applied rolling force, a coefficient of friction and a difference in speed between the rolled strip and the work rolls in the roll gap of the respective roll stand. The rolling force is usually specified by a system automation of the rolling train to achieve the desired pass reduction on the relevant stand and is therefore known. Alternatively, the current rolling force, for example in the case of thickness control, can also be continuously measured online via devices that generate the rolling force on the roll stand in question (e.g. hydraulic cylinders). To determine the differential speed in the roll gap, for example, formula (3.13) in H. Hoffmann: Handbook Forming, 2012, ISBN 978-3-446-42778-5 known, in which the entry and exit speed of the rolling stock at the roll stand and the roll gap geometry, which depends on the roll diameters of the work rolls and the reduction in pass at the corresponding stand, is included. Empirical values, for example, can be used to determine the coefficient of friction in the roll gap. For example, the parameters surface quality, material properties and application of lubricant that are known for a specific rolling process determine the coefficient of friction. Alternatively, modeling of the coefficient of friction is also possible JBAF Smeulders: Lubrication in the Gold Rolling Process Described by a 3D Stribeck Curve, AISTech 2013 Proceedings known.

The reduction in thickness of the rolling stock to be achieved in the rolling train is divided between the individual rolling stands by means of a pass plan distribution for the pass reductions of the individual rolling passes. In principle, the rolling stock is heated in each roll stand by the plastic deformation of the rolling stock. The heat of deformation occurring in the rolling stock can be determined by a person skilled in the art in a simple manner from the pass reduction at the respective roll stand and from the material properties of the rolling stock. Through a suitable choice of pass reductions, all stands of the rolling train taken into account, it can be achieved, for example, that a predetermined temperature range for the rolling stock temperature is maintained over the entire rolling train.

The rolling speed is a speed at which the rolling stock runs through the roll stands of the rolling train. The rolling speed can directly influence the above-mentioned friction losses at the individual roll stands, since the differential speeds in the individual roll stands are also directly affected by the rolling speed. The rolling speed therefore also influences the rolling stock temperature in the individual rolling passes.

In order to influence the rolling stock temperature during cold rolling in a rolling train with several roll stands, through which the rolling stock passes in succession, several control or regulation measures are available according to the method according to the invention, which influence the rolling process via a corresponding manipulated variable and which make it possible to To keep rolling stock temperature throughout the passage of the rolling stock through the rolling train within a certain temperature range, which is defined by a lower and an upper limit temperature. These manipulated variables include the heat output of a heating device for setting an inlet temperature of the rolled strip before the first rolling pass, the cooling parameters for setting the amount of heat that is dissipated from the rolling stock through the contact of the rolling stock with the work rolls and through the rolling stock coolant applied to the rolling stock, the lubrication parameters for setting the friction power loss in the roll gap of the respective roll stands, the pass plan distribution for setting the forming heat generated during pass reduction in the respective roll stands, and the rolling speed, which also influences the friction power loss during pass reduction in the individual roll stands.

In the case of the above-mentioned control or regulation measures, the resulting rolling stock temperatures can be determined, for example, using a simulation by a computing unit in advance, i.e. before the rolling process itself is actually carried out. This computing unit can be identical to the controller that carries out the control or regulation measures on the rolling train in the real rolling process.

• ermittelt wird: beispielsweise wird
• die aufgrund der am ersten Walzgerüst voreingestellten Kühlparameter aus dem Walzgut and die Arbeitswalzen und an das Walzgutkühlmittel abgeführte Wärmemenge ermittelt,
• es wird weiterhin die aufgrund der am ersten Walzgerüst voreingestellten Schmierparameter sowie der am ersten Walzgerüst voreingestellten Walzgeschwindigkeit die Reibungsverlustleistung im Walzspalt des ersten Walzgerüsts ermittelt, und
• es wird die aufgrund der voreingestellten Stichplanverteilung am ersten Walzgerüst entstehende Umformungswärme aus der Stichabnahme am ersten Walzgerüst und aus den Materialeigenschaften des Walzguts ermittelt.

In concrete terms, this means that, for example, based on preset values for the individual manipulated variables, first the temperature profile of the rolling stock - over a specific rolling pass or over the entire rolling train

• is determined: for example, is
• determines the amount of heat dissipated from the rolling stock to the work rolls and to the rolling stock coolant based on the cooling parameters preset on the first roll stand,
• furthermore, based on the lubrication parameters preset on the first roll stand and the rolling speed preset on the first roll stand, the power loss due to friction in the roll gap of the first roll stand is determined, and
• the heat of deformation occurring on the first roll stand due to the preset pass plan distribution is determined from the pass reduction on the first roll stand and from the material properties of the rolling stock.

On the basis of these determined heat flows, the resulting temperature of the rolling stock downstream of the first rolling stand after application of the rolling stock coolant can be determined, starting from an inlet temperature of the rolling stock that is preset by means of a heating device or otherwise determined. The temperature of the rolling stock determined in this way behind the first roll stand can be used as a starting point to calculate the temperature of the rolling stock behind the second roll stand on the basis of the temperature on the second roll stand in the same way preset rolling speed, pass reduction as well to determine cooling and lubrication parameters. This successive determination of the rolling stock temperature can be continued until the rolling stock emerges from the last roll stand of the rolling train.

If it is determined that the upper or lower temperature limit has been exceeded or fallen below, one of the above-mentioned control or regulation measures can be applied with values that deviate from the preset values for the respective manipulated variable and the rolling stock temperature can be calculated again to check whether the specified limit temperatures are maintained with changed parameters for the control or regulation measures. The check can be carried out again after each change in the set manipulated variables.

For example, if it is determined that the temperature of the rolling stock is exceeded at a specific roll stand, the lubrication applied and/or the cooling on this stand can be increased in order to reduce the frictional power loss and/or increase the amount of heat removed from the rolling stock.

In the case of a so-called 'global optimization problem', a solution is sought in which several criteria are to be taken into account simultaneously with the specification of a target function, with the target function weighting the individual criteria individually and these criteria, for example, a desired temperature control across the entire rolling mill, an optimized pass schedule in With regard to desired material properties, the highest possible throughput rate through the rolling train, compliance with a specific rolling force distribution or the lowest possible use of coolants and lubricants. The computing effort to find a solution to a global optimization problem increases disproportionately with the number of variable parameters.

The independent and non-inventive execution of one or more of the above control or regulation measures does not necessarily provide the optimal solution in relation to such a global optimization problem, but an independent implementation of the execution of one or more of the above control or regulation measures is different from each other, for example as Retrofitting solution for existing control systems of rolling mills, since the verification of whether an applied control or regulation measure ensures compliance with the limit temperatures is in any case only proportional to the roll stands of the rolling mill, but does not depend on the number of variable parameters themselves. The computing power required in such a case can therefore also be provided by a controller of the rolling train itself. For example, when changing the cooling parameters on a specific roll stand, only the rolling stock temperatures in the region of the roll stand downstream of the roll stand in question have to be redetermined. But even if there is an additional change in the pass schedule or the rolling speed, which affect all of the roll stands in the rolling train, the number of heat quantities to be newly determined in the manner described above is to be used to check compliance with the limit temperatures by this total number of roll stands limited.

In one embodiment of the invention, a model-based calculation of the entry temperature of the rolling stock, the cooling and lubrication parameters, the pass schedule distribution and the rolling speed takes place as a solution to a global optimization problem with the specification of a target function. In a global optimization problem, there can be a large number of solutions, among which the most suitable one is determined, for example, only after taking into account other criteria, for example by additionally maximizing the rolling speed or maintaining a specific rolling force distribution on the roll stands 3 to 7, also based on a model.

In one embodiment of the invention, an upper limit temperature in the range between 140° C. and 250° C. and/or a lower limit temperature in the range between 20° C. and 140° C. is specified for at least one rolling pass. Such an upper limit temperature can in particular prevent the aforementioned cracking of rolling oil that is used as a lubricant or a component of a lubricant. The lower limit temperature depends on the material and is therefore adapted to the rolling stock.

In a further embodiment of the invention, a common upper limit temperature and/or a common lower limit temperature are specified for all rolling passes. This simplifies the method according to the invention compared to an embodiment with limit temperatures dependent on the rolling pass.

In a further embodiment of the invention, the rolling stock is heated to an entry temperature before the first rolling pass with a heating device, in particular with an induction heater. In the case of inductive heating of the rolling stock, the heating of the rolling stock can be determined simply from the power of the induction heating, the efficiency and the exposure time, which results from the rolling stock speed and the overall length of the heating, as well as material properties of the rolling stock, in particular its specific thermal capacity.

In a further embodiment of the invention, the work rolls of at least one roll stand are cooled by applying a roll coolant to the work rolls only on the outlet side. The exit side of a roll stand is understood to mean that side of the roll stand on which the rolling stock leaves the roll stand. Correspondingly, the entry side of a roll stand is understood to mean that side of the roll stand on which the rolling stock enters the roll stand. A downstream application of a roll coolant to the work rolls is more efficient than an entry-side application, since due to the direction of rotation of the work rolls, the heat generated by the rolling process is dissipated immediately, while for an entry-side roll cooling, the relevant point of the work roll must first cover about half a revolution.

In a further embodiment of the invention, a lubricant is applied to the work rolls and/or to the rolling stock in at least one pass by producing a mixture of the lubricant and a carrier gas in an atomization device and spraying the mixture onto the work rolls and/or onto lubricant nozzles the rolling stock is sprayed. Such an application of lubricant is, for example, from EP 2 651 577 B1 known and has the advantage over the application of a lubricating emulsion, for example, that the lubricant can be applied very precisely and sparingly.

In a further embodiment of the invention, a lubricant is only applied to the work rolls and/or to the rolling stock in at least one rolling pass on the inlet side. This is particularly advantageous in the case of rolling passes in which coolant is only applied on the outlet side, because then no lubricant is washed off the coolant and lubricant is thus saved.

In a further embodiment of the invention, a parameter value is determined offline for at least one parameter of a control or regulation measure using a calculation model of at least part of the rolling mill and the parameter is set to the parameter value during operation of the rolling mill. The parameters that can be determined by a computational model include an inlet temperature of the rolling stock, cooling parameters (e.g. roll coolant flows, roll coolant pressures, rolling stock coolant flows and rolling stock coolant pressures), lubrication parameters (e.g. lubricant flows and lubricant pressures), a pass schedule distribution (i.e. the Pass reductions of the individual rolling passes), as well as a rolling speed.

In these refinements of the invention, at least a subset of the parameters for controlling or regulating the rolling stock temperature is determined (in particular calculated) in advance.

In a further refinement of the invention, at least two parameter values determined offline are determined as a solution to a global optimization problem with specification of a target function. In addition to maintaining the upper and lower limit temperatures, this advantageously allows at least one further criterion to be taken into account during the rolling process of the rolling stock.

In a further embodiment of the invention, at least one measured value of the temperature of the rolling stock is recorded during operation of the rolling train, and at least one parameter of a control or regulation measure is set online as a function of at least one measured value. In this embodiment of the invention, at least a subset of the parameters for controlling or regulating the rolling stock temperature is set online as a function of a measured rolling stock temperature of the rolling stock. This can particularly affect the cooling and lubrication of the work rolls and/or the rolling stock.

• eine von der Steuerung steuer- oder regelbare Heizvorrichtung, die eingerichtet ist, das Walzgut vor dem ersten Walzstich zu erwärmen,
• ein von der Steuerung steuer- oder regelbares Kühlsystem, das eingerichtet ist, ein Walzenkühlmittel auf die Arbeitswalzen wenigstens eines Walzgerüsts und/oder ein Walzgutkühlmittel zwischen wenigstens zwei aufeinander folgenden Walzstichen auf das Walzgut auszugeben,
• ein von der Steuerung steuer- oder regelbares Schmierungssystem, das eingerichtet ist, bei wenigstens einem Walzstich ein Schmiermittel auf die Arbeitswalzen oder/und auf das Walzgut auszugeben, und bevorzugt
• wenigstens eine Messeinheit, die zum Erfassen einer Walzguttemperatur des Walzguts an einer beliebigen Stelle der Walzstraße eingerichtet ist.

A rolling train according to the invention comprises a plurality of roll stands for cold-rolling a rolling stock and a controller that is set up to carry out the control or regulation measures mentioned above. The rolling mill includes:

• a heating device that can be controlled or regulated by the controller and is set up to heat the rolling stock before the first rolling pass,
• a cooling system that can be controlled or regulated by the controller and is set up to apply a roll coolant to the work rolls of at least one roll stand and/or a Dispense rolling stock coolant onto the rolling stock between at least two consecutive rolling passes,
• a lubrication system that can be controlled or regulated by the controller and is set up to dispense a lubricant onto the work rolls and/or onto the rolling stock during at least one rolling pass, and preferred
• at least one measuring unit that is set up to detect a rolling stock temperature of the rolling stock at any point of the rolling train.

The advantages of such a rolling train correspond to the above-mentioned advantages of the method according to the invention.

• FIG 1 schematisch ein Ausführungsbeispiel einer erfindungsgemäßen Walzstraße,
• FIG 2 ein Ablaufdiagramm eines Ausführungsbeispiels des erfindungsgemäßen Verfahrens.

The properties, features and advantages of this invention described above, and the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of exemplary embodiments, which will be explained in more detail in connection with the drawings. show it

• FIG 1 schematically an embodiment of a rolling train according to the invention,
• FIG 2 a flowchart of an embodiment of the method according to the invention.

Figure 1 (FIG 1 ) shows schematically an exemplary embodiment of a rolling train 1 according to the invention with five roll stands 3 to 7 for cold rolling a rolling stock 2. Each roll stand 3 to 7 has two work rolls 9, 10 arranged one above the other, which are spaced apart from one another by a roll gap 11. To roll the rolled stock 3, the work rolls 9, 10 are set in rotation by a motor and the rolled stock 3 is pulled by the rotating work rolls 9, 10 in a rolling direction 13 through the roll gaps 11.

At the in figure 1 shown embodiment of a rolling train 1 also has each roll stand 3 to 7 for each Work roll 9, 10 has two back-up rolls 15 to 18, which are arranged one above the other on a side of the respective work roll 9, 10 facing away from the rolling stock 2, with a first back-up roll 15, 17 contacting the second back-up roll 16, 18 and the work roll 9, 10 .

Each roll stand 3 to 7 carries out a rolling pass in which the thickness of the rolling stock 2 is reduced by the so-called pass reduction of the rolling pass. A heating device 19 is arranged at the entrance to the rolling train 1 and is set up to heat the rolling stock 2 before the first rolling pass, which is carried out by a first roll stand 3 . The heating device 19 is designed, for example, as an induction heater with which the rolling stock 3 can be inductively heated.

The rolling train 1 also has a cooling system which is set up to apply a roll coolant 21 to the work rolls 9, 10 of the roll stands 4 to 6 which carry out the second, third and fourth pass, and a roll coolant 23 between the second and the third pass, output the third and the fourth rolling pass and the fourth and the fifth rolling pass on the rolling stock 2. The cooling system comprises an upper cooling beam 25 and a lower cooling beam 27 for each of the roll stands 4 to 6. With the upper cooling beam 25, roll coolant 21 is on the outlet side on the upper work roll 9 of the respective roll stand 4 to 6 and rolling stock coolant 23 on an upper rolling stock surface of the rolling stock 3 spendable. With the lower cooling beam 27 , roll coolant 21 can be discharged onto the lower work roll 10 of the respective roll stand 4 to 6 and rolling stock coolant 23 can be discharged onto a lower surface of the rolled stock 3 . Each cooling bar 25, 27 comprises, for example, a plurality of roll coolant nozzles, with which the roll coolant 21 can be discharged onto the respective work roll 9, 10, and/or a plurality of rolling stock coolant nozzles which the rolling stock coolant 23 can be dispensed onto the rolling stock 2.

The roll coolant 21 is, for example, water or a cooling emulsion. The rolling stock coolant 23 is also water or a cooling emulsion, for example, and can agree with the roll coolant 21 . A cooling emulsion consists of a cooling liquid and a lubricant, for example water as the cooling liquid and oil as the lubricant, and possibly emulsifiers. The main component of the cooling emulsion is the cooling liquid, while the lubricant content of the cooling emulsion is only a few percent, for example two to three percent. For example, the amount of roll coolant 21 applied to the two work rolls 9, 10 of a roll stand 4 to 6 (in total, i.e. to both work rolls 9, 10 together) in liters per minute corresponds approximately to a motor power of the roll stand 4 to 6 in kW, with the Motor power is the power of a motor driving the work rolls 9, 10 of the roll stand 4 to 6.

The rolling train 1 also has a lubrication system which is set up to dispense a lubricant 29 onto the work rolls 9, 10 of all roll stands 3 to 7 on the inlet side. The lubrication system has an upper lubricating bar 31 and a lower lubricating bar 33 for each roll stand 3 to 7 . Lubricant 29 can be dispensed with the upper lubricating bar 31 on the inlet side onto the upper work roll 9 of the respective roll stand 3 to 7 . With the lower lubricating bar 33, lubricant 29 can be dispensed onto the lower work roll 10 of the respective roll stand 3 to 7 on the inlet side. For example, each lubricating bar 31, 33 includes an atomization device in which a mixture of the lubricant 29 and a carrier gas can be generated, and a plurality of lubricant nozzles with which the mixture can be sprayed onto the respective work roll 9, 10. In this case, the lubricant 29 is, for example, pure rolling oil and the carrier gas is air, for example. For example, a maximum of two liters of rolling oil are dispensed onto each work roll 9, 10 per minute. Alternatively, the lubricant 29 is a lubricating emulsion consisting of a carrier liquid and rolling oil and possibly emulsifiers, and each lubricating bar 31, 33 has lubricant nozzles with which the lubricating emulsion can be dispensed onto the respective work roll 9, 10.

Arranged under the roll stands 3 to 7 are collecting devices 35 which are set up to collect roll coolant 21 , rolling stock coolant 23 and lubricant 29 flowing out of the roll stands 3 to 7 . The mixture of roll coolant 21, rolling stock coolant 23 and lubricant 29 collected by the collecting devices 35 is preferably broken down into its components, which are then reused.

The rolling train 1 also has a number of measuring units 37 which are each set up to record a rolling stock temperature of the rolling stock 2 . A measuring unit 37 is arranged between the heating device 19 and the first rolling stand 3, further measuring units 37 are arranged respectively between two adjacent rolling stands 3 to 7, and a measuring unit 37 is at the end of the rolling train 1 behind the rolling stand 7 which carries out the fifth rolling pass. arranged.

The rolling train 1 also has a controller 39 with which the heating device 19, the cooling system, i.e. the roll coolant flows, roll coolant pressures, rolling stock coolant flows and rolling stock coolant pressures emitted by the cooling beams 25, 27, and the lubrication system, i.e. those from the lubricating beams 31, 33 lubricant flows and lubricant pressures that are output in each case can be controlled or regulated in order to control or regulate the rolling stock temperature of the rolling stock 2 in each rolling pass. For this purpose, a temperature window for the rolling stock temperature between a upper limit temperature and a lower limit temperature are specified, and the rolling stock temperature is controlled and/or regulated in such a way that the rolling stock temperature in each rolling pass assumes a temperature value lying in the temperature window specified for the rolling pass. In addition to controlling or regulating the heating device 19, the cooling system and the lubrication system, a pass plan distribution for the pass reductions of the individual rolling passes is created and implemented. The roll stands 3 to 7, that is, the gap heights of the roll gaps 11 of the roll stands 3 to 7 are set according to the pass schedule distribution. Furthermore, a rolling speed at which the rolling stock 2 runs through the rolling train 1 is controlled or regulated in order to influence the temperature of the rolling stock in the rolling passes. The rolling speed is adjusted by the speeds of the work rolls 9,10.

The parameters of the temperature control and/or regulation are an inlet temperature of the rolling stock 2 to be set with the heating device 19, the roll coolant flows output by the cooling beams 25, 27, roll coolant pressures, rolling stock coolant flows and rolling stock coolant pressures (cooling parameters), which are output by the lubricating beams 31, 33 in each case Lubricant flows and lubricant pressures (lubrication parameters), the pass schedule distribution and the rolling speed. These parameters are each determined, for example, offline using a computer model of at least part of the rolling train 1 . For example, a model-based calculation of the inlet temperature of the rolling stock 2, the cooling and lubrication parameters, the pass schedule distribution and the rolling speed is carried out as a solution to a global optimization problem with a target function being specified. There can be a large number of solutions, among which the most suitable one can only be found, for example, taking into account further criteria, for example by additionally maximizing the rolling speed or maintaining a specific rolling force distribution on the roll stands 3 to 7, is also determined based on the model. The parameters determined in this way (offline parameters) are each set manually or by the controller 39 . Alternatively, some or all parameters (online parameters) can be regulated online depending on the measured values of the measuring units 37 such that the rolling stock temperature in each rolling pass assumes a temperature value within the temperature window specified for the rolling pass. For example, the pass schedule distribution, the entry temperature of the rolling stock 2 and the rolling speed are determined offline, while the cooling and lubrication parameters are controlled online depending on the measured values from the measuring units 37 .

Figure 2 (FIG 2 ) shows a flowchart 100 of an exemplary embodiment of the method according to the invention for cold-rolling a rolling stock 2 in a rolling train 1 with method steps 101 to 106.

In a first method step 101, a temperature window for the rolling stock temperature of the rolling stock 2 in the rolling pass is specified for each rolling pass.

In a second method step 102, as described above, the offline parameters are determined using a computer model of at least part of the rolling train 1, for example the pass schedule distribution, the inlet temperature of the rolling stock 2 and the rolling speed.

In a third method step 103, the cold rolling of the rolling stock 2 in the rolling mill train 1 is started with the offline parameters determined in the second method step 102 and predetermined initial values of the online parameters.

In a fourth method step 104, a rolling stock temperature of the rolling stock 2 is determined for each rolling pass. For example, the rolling stock temperature is recorded for a rolling pass with at least one measuring unit 37 or the rolling stock temperature in the rolling pass is calculated, for example, as described above, with a calculation of the heat flow between the rolling stock and the work rolls in the roll gap based on a modeling of the heat transfer and/or with a calculation of the deformation heat that occurs when the rolling stock is heated by the plastic deformation of the rolling stock.

In a fifth method step 105, a check is made as to whether the temperature of the rolling stock in each rolling pass assumes a temperature value within the temperature window specified for the rolling pass. If the check reveals that the temperature of the rolling stock in each rolling pass assumes a temperature value within the temperature window specified for the rolling pass, the fourth method step 104 is carried out again. Otherwise, a sixth method step 106 is carried out.

In the sixth method step 106, the value of at least one online parameter is changed in order to bring the rolling stock temperature into the specified temperature window in each rolling pass in which the rolling stock temperature is outside the temperature window specified for the rolling pass. After the sixth method step 106, the fourth method step 104 is carried out again.

Although the invention has been illustrated and described in detail by preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived therefrom by a person skilled in the art without departing from the protective scope of the invention as defined by the claims.

Reference List

1

rolling mill

2

rolling stock

3 to 7

mill stand

9, 10

stripper

11

roll gap

13

rolling direction

15 to 18

backup roll

19

heating device

21

roll coolant

23

rolling stock coolant

25, 27

chilled beam

29

lubricant

31, 33

smudge bar

35

collection device

37

unit of measure

39

steering

100

flowchart

101 to 106

process step

Claims (13)

1. Method for the cold rolling of rolled stock (2) in a rolling train (1) having multiple rolling stands (3 to 7) through which the rolled stock (2) passes in succession, wherein

   - an upper limit temperature and/or a lower limit temperature for a temperature of the rolled stock (2) is predetermined for at least one rolling pass,

   - and the rolled-stock temperature is open-loop and/or closed-loop controlled by the following open-loop or closed-loop control measures in such a way that the rolled-stock temperature in the at least one rolling pass does not exceed the upper limit temperature predetermined for the rolling pass and/or does not fall below the lower limit temperature predetermined for the rolling pass:

   - heating the rolled stock (2) to a run-in temperature by means of a heating device (19) before the first rolling pass, wherein the heat output of the heating device (19) is set,

   - cooling the working rollers (9, 10) of at least one rolling stand (3 to 7) by applying a roller coolant (21) to the working rollers (9, 10), wherein a flow of the roller coolant (21) and/or a pressure of the roller coolant (21) is open-loop or closed-loop controlled, wherein the amount of heat discharged from the working rollers (9, 10) when the working rollers (9, 10) are being cooled and the amount of heat discharged from the rolled stock (2) to the working rollers (9, 10) are ascertained,

   - cooling the rolled stock (2) between at least two rolling passes which follow one another by applying a rolled-stock coolant (23) to the rolled stock (2), wherein a flow of the rolled-stock coolant (23) and/or a pressure of the rolled-stock coolant (23) is open-loop or closed-loop controlled and the amount of heat discharged from the rolled stock (2) to the rolled-stock coolant (23) when the rolled stock (2) is being cooled is ascertained,

   - applying a lubricant (29) to the working rollers (9, 10) or/and to the rolled stock (2) in at least one rolling pass, wherein a flow of the lubricant (29) and/or a pressure of the lubricant (29) is open-loop or closed-loop controlled and a frictional power loss in the rolling gap of the respective rolling stand (3 to 7) is ascertained,

   - compiling and implementing a pass sequence distribution for the pass reductions of the individual rolling passes, wherein the resulting heat of forming when the rolled stock (2) plastically deforms is ascertained from the pass reduction at the respective rolling stand and from the material properties of the rolled stock (2), and

   - open-loop or closed-loop controlling a rolling speed at which the rolled stock (2) passes through the rolling train (1), wherein the resulting frictional power loss in the respective rolling stand (3 to 7) is ascertained.
2. Method according to Claim 1, wherein an upper limit temperature in the range of between 140°C and 250°C is predetermined for at least one rolling pass.
3. Method according to Claim 1 or 2, wherein a lower limit temperature in the range of between 20°C and 140°C is predetermined for at least one rolling pass.
4. Method according to one of the preceding claims, wherein a common upper limit temperature is predetermined for all of the rolling passes.
5. Method according to one of the preceding claims, wherein a common lower limit temperature is predetermined for all of the rolling passes.
6. Method according to one of the preceding claims, wherein the heating device (19) is designed as an induction heater.
7. Method according to one of the preceding claims, wherein a lubricant (29) is applied to the working rollers (9, 10) or/and to the rolled stock (2) in at least one rolling pass by creating a mixture of the lubricant (29) and a carrier gas in an atomization device and spraying the mixture onto the working rollers (9, 10) and/or onto the rolled stock (2) by means of lubricant nozzles.
8. Method according to one of the preceding claims, wherein a parameter value is ascertained offline for at least one parameter of an open-loop or closed-loop control measure on the basis of a calculation model of at least part of the rolling train (1) and the parameter is set to the parameter value during operation of the rolling train (1).
9. Method according to Claim 8, wherein at least one parameter value ascertained offline is a run-in temperature of the rolled stock (2) and/or a cooling parameter and/or a lubrication parameter and/or a pass sequence distribution and/or a rolling speed.
10. Method according to Claim 8 or 9, wherein at least two parameter values ascertained offline are ascertained as a solution to a global optimization problem with predetermination of a target function.
11. Method according to one of the preceding claims, wherein at least one measured value of the rolled-stock temperature is recorded during operation of the rolling train (1), and at least one parameter of an open-loop or closed-loop control measure is set online as a function of at least one measured value.
12. Rolling train (1) having multiple rolling stands (3 to 7) for the cold rolling of rolled stock (2) and a controller (39), comprising

    - a heating device (19) that can be open-loop or closed-loop controlled by the controller (39) and is configured to heat the rolled stock (2) before the first rolling pass,

    - a cooling system that can be open-loop or closed-loop controlled by the controller (39) and is configured to dispense a roller coolant (21) onto the working rollers (9, 10) of at least one rolling stand (3 to 7) and/or a rolled-stock coolant (23) onto the rolled stock (2) between at least two rolling passes which follow one another, and

    - a lubrication system that can be open-loop or closed-loop controlled by the controller (39) and is configured to dispense a lubricant (29) onto the working rollers or/and onto the rolled stock (2) in at least one rolling pass,

    - wherein the controller (39) is configured to carry out the open-loop or closed-loop control measures of the method according to one of the preceding claims.
13. Rolling train (1) according to Claim 12 having at least one measuring unit (37) that is configured to record a temperature of the rolled stock (2) at any desired point on the rolling train (1).

Images