COLD ROLLING ROLLED STOCK IN A MILL TRAIN WITH MULTIPLE ROLL STANDS

Abstract

A method for cold rolling rolled stock (2) in a mill train (1) with multiple roll stands (3 to 7). An upper limit temperature and/or a lower limit temperature is provided for a rolled stock temperature of the rolled stock (2) for at least one rolling pass, and the rolled stock temperature is controlled and/or regulated by at least one control or regulating measure such that during the at least one rolling pass, the rolled stock temperature does not exceed the upper limit temperature specified for the rolling pass and/or the rolled stock temperature does not fall below the lower limit temperature specified for the rolling pass.

Claims

1. A method for the cold rolling of rolled stock in a rolling train having multiple rolling stands through which the rolled stock passes in succession in multiple rolling passes, wherein an upper limit temperature and/or a lower limit temperature for a temperature of the rolled stock is predetermined for at least one rolling pass, and the rolled-stock temperature is open-loop and/or closed-loop controlled by at least one of 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 to a run-in temperature by means of a heating device before the first rolling pass, wherein the heat output of the heating device is set, cooling the working rollers of at least one rolling stand by applying a roller coolant to the working rollers, wherein a flow of the roller coolant and/or a pressure of the roller coolant is open-loop or closed-loop controlled, wherein the amount of heat discharged from the working rollers when the working rollers are being cooled and the amount of heat discharged from the rolled stock to the working rollers are determined, cooling the rolled stock between at least two rolling passes which follow one another by applying a rolled-stock coolant to the rolled stock, wherein a flow of the rolled-stock coolant and/or a pressure of the rolled-stock coolant is open-loop or closed-loop controlled and the amount of heat discharged from the rolled stock to the rolled-stock coolant when the rolled stock is being cooled is determined, applying a lubricant to the working rollers or/and to the rolled stock in at least one rolling pass, wherein a flow of the lubricant and/or a pressure of the lubricant is open-loop or closed-loop controlled and a frictional power loss in the rolling gap of the respective rolling stand is determined, compiling and implementing a pass sequence distribution for the pass reductions of the individual rolling passes, wherein the deformation heat of resulting from the plastic deformation during the pass reduction of the rolled stock is determined from the pass reduction at the respective rolling stand and from the material properties of the rolled stock, open-loop or closed-loop controlling a rolling speed at which the rolled stock passes through the rolling train, wherein the resulting frictional power loss in the respective rolling stand is determined.

2. The method as claimed in claim 1, wherein an upper limit temperature in the range of 140° C. and 250° C. is predetermined for at least one rolling pass.

3. The method as claimed in claim 1, wherein a lower limit temperature in the range of 20° C. and 140° C. is predetermined for at least one rolling pass.

4. The method as claimed in claim 1, wherein a common upper limit temperature is predetermined for all of the multiple rolling passes.

5. The method as claimed in claim 1, wherein a common lower limit temperature is predetermined for all of the multiple rolling passes.

6. The method as claimed in claim 1, wherein the heating device is embodied as an induction heater.

7. The method as claimed in claim 1, wherein a lubricant is applied to the working rollers or/and to the rolled stock in at least one rolling pass by creating a mixture of the lubricant and a carrier gas in an atomization device, and spraying the mixture onto the working rollers and/or onto the rolled stock by means of lubricant nozzles.

8. The method as claimed in claim 1, wherein a parameter value is determined 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 and the parameter is set to the parameter value during operation of the rolling train.

9. The method as claimed in claim 8, wherein at least one parameter value determined offline is a run-in temperature of the rolled stock and/or a cooling parameter and/or a lubrication parameter and/or a pass sequence distribution and/or a rolling speed.

10. The method as claimed in claim 8, wherein at least two parameter values determined offline are determined as a solution to a global optimization problem with predetermination of a target function.

11. The method as claimed in claim 1, wherein at least one measured value of the rolled-stock temperature is recorded during operation of the rolling train, and at least one parameter of an open-loop or closed-loop control measure is set online as a function of the at least one measured value.

12. A rolling train having multiple rolling stands for the cold rolling of rolled stock and a controller, comprising: a heating device that can be open-loop or closed-loop controlled by the controller and is configured to heat the rolled stock before the first rolling pass, and/or a cooling system that can be open-loop or closed-loop controlled by the controller and is configured to dispense a roller coolant onto the working rollers of at least one rolling stand and/or a rolled-stock coolant onto the rolled stock between at least two rolling passes which follow one another, and/or a lubrication system that can be open-loop or closed-loop controlled by the controller and is configured to dispense a lubricant onto the working rollers or/and onto the rolled stock in at least one rolling pass, and/or wherein the controller is configured to execute at least one of the open-loop or closed-loop control measures of the method as claimed in claim 1.

13. The rolling train as claimed in claim 12 having at least one measuring unit that is configured to record a temperature of the rolled stock at any desired location in on the rolling train.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] FIG. 1 schematically shows an exemplary embodiment of a rolling train according to the invention,

[0054] FIG. 2 shows a flow diagram of an exemplary embodiment of the method according to the invention.

DESCRIPTION OF EMBODIMENTS

[0055] FIG. 1 (FIG. 1) schematically shows an exemplary embodiment of a rolling train 1 according to the invention having five rolling stands 3 to 7 for the cold rolling of rolled stock 2. Each rolling stand 3 to 7 has two working rollers 9, 10, which are arranged one above the other and are spaced apart from one another by a rolling gap 11. To roll the rolled stock 3, the working rollers 9, 10 are set in rotation by a motor and the rolled stock 3 is pulled by the rotating working rollers 9, 10 in a rolling direction 13 through the rolling gaps 11.

[0056] In the exemplary embodiment of a rolling train 1 shown in FIG. 1, each rolling stand 3 to 7 further has for each working roller 9, 10 two back-up rollers 15 to 18, which are arranged one on top of the other on a side of the respective working roller 9, 10 that faces away from the rolled stock 2, with a first back-up roller 15, 17 making contact with the second back-up roller 16, 18 and the working roller 9, 10.

[0057] Each rolling stand 3 to 7 carries out a rolling pass in which the thickness of the rolled stock 2 is reduced by what is referred to as the pass reduction of the rolling pass. A heating device 19 is arranged at the entrance of the rolling train 1 and is configured to heat the rolled stock 2 before the first rolling pass, which is carried out by a first rolling stand 3. The heating device 19 is for example embodied as an induction heater, by means of which the rolled stock 3 can be inductively heated.

[0058] The rolling train 1 also comprises a cooling system which is configured to dispense a roller coolant 21 onto the working rollers 9, 10 of the rolling stands 4 to 6, which carry out the second, the third and the fourth rolling pass, and to dispense a rolled-stock coolant 23 onto the rolled stock 2 between the second and the third rolling pass, the third and the fourth rolling pass, and the fourth and the fifth rolling pass. The cooling system comprises an upper cooling bar 25 and a lower cooling bar 27 for each of the rolling stands 4 to 6. By means of the upper cooling bar 25, roller coolant 21 can be dispensed on the run-out side onto the upper working roller 9 of the respective rolling stand 4 to 6 and rolled-stock coolant 23 can be dispensed onto an upper surface of the rolled stock 3. By means of the lower cooling bar 27, roller coolant 21 can be dispensed on the run-out side onto the lower working roller 10 of the respective rolling stand 4 to 6 and rolled-stock coolant 23 can be dispensed onto a lower surface of the rolled stock 3. Each cooling bar 25, 27 comprises, for example, multiple roller-coolant nozzles, by means of which the roller coolant 21 can be dispensed onto the respective working roller 9, 10, and/or multiple rolled-stock-coolant nozzles, by means of which the rolled-stock coolant 23 can be dispensed onto the rolled stock 2.

[0059] The roller coolant 21 is, for example, water or a cooling emulsion. The rolled-stock coolant 23 is likewise water or a cooling emulsion, for example, and can match the roller 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 of emulsifiers. In this respect, 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 roller coolant 21 applied to the two working rollers 9, 10 of a rolling stand 4 to 6 (in total, i.e. to the two working rollers 9, 10 together) in liters per minute corresponds approximately to a motor power of the rolling stand 4 to 6 in kW, with the motor power being the power of a motor that drives the working rollers 9, 10 of the rolling stand 4 to 6.

[0060] The rolling train 1 moreover has a lubrication system which is configured to dispense a lubricant 29 on the run-in side onto the working rollers 9, 10 of all of the rolling stands 3 to 7. The lubrication system has an upper lubricating bar 31 and a lower lubricating bar 33 for each rolling stand 3 to 7. By means of the upper lubricating bar 31, lubricant 29 can be dispensed on the run-in side onto the upper working roller 9 of the respective rolling stand 3 to 7. By means of the lower lubricating bar 33, lubricant 29 can be dispensed on the run-in side onto the lower working roller 10 of the respective rolling stand 3 to 7. For example, each lubricating bar 31, 33 comprises an atomization device in which a mixture of the lubricant 29 and a carrier gas can be created, and multiple lubricant nozzles by means of which the mixture can be sprayed onto the respective working roller 9, 10. Here, the lubricant 29 is pure rolling oil, for example, and the carrier gas is air, for example. For example, a maximum of two liters of rolling oil per minute are dispensed onto each working roller 9, 10. As an alternative, 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 by means of which the lubricating emulsion can be dispensed onto the respective working roller 9, 10.

[0061] Arranged under the rolling stands 3 to 7 are collecting devices 35 which are configured to collect roller coolant 21, rolled-stock coolant 23 and lubricant 29 that flow off from the rolling stands 3 to 7. The mixture of roller coolant 21, rolled-stock coolant 23 and lubricant 29 that is collected by the collecting devices 35 is preferably broken down into its constituents, which are then reused.

[0062] The rolling train 1 furthermore has multiple measuring units 37 which are each configured to record a temperature of the rolled 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 arranged at the end of the rolling train 1 downstream of the rolling stand 7, which carries out the fifth rolling pass.

[0063] The rolling train 1 also has a controller 39 by means of which the heating device 19, the cooling system, i.e. the flows of the roller coolant, the pressures of the roller coolant, the flows of the rolled-stock coolant and the pressures of the rolled-stock coolant that are respectively dispensed by the cooling bars 25, 27, and the lubrication system, i.e. the flows of the lubricant and pressures of the lubricant that are respectively dispensed from the lubricating bars 31, 33, respectively can be open-loop or closed-loop controlled in order to open-loop or closed-loop control the temperature of the rolled stock 2 in each rolling pass. For this purpose, a temperature range for the rolled-stock temperature between an upper limit temperature and a lower limit temperature is predetermined for each rolling pass, and the rolled-stock temperature is open-loop and/or closed-loop controlled in such a way that the rolled-stock temperature in each rolling pass takes on a temperature value within the temperature range predetermined for the rolling pass. In addition to the open-loop or closed-loop control of the heating device 19, of the cooling system and of the lubrication system, a pass sequence distribution for the pass reductions of the individual rolling passes is compiled and implemented. The rolling stands 3 to 7, i.e. the gap heights of the rolling gaps 11 of the rolling stands 3 to 7, are set according to the pass sequence distribution. Furthermore, a rolling speed at which the rolled stock 2 passes through the rolling train 1 is open-loop or closed-loop controlled in order to influence the rolled-stock temperature in the rolling passes. The rolling speed is set by the rotational speeds of the working rollers 9, 10.

[0064] The parameters of the open-loop and/or closed-loop control of the temperature are a run-in temperature of the rolled stock 2 to be set by means of the heating device 19, the flows of the roller coolant, the pressures of the roller coolant, the flows of the rolled-stock coolant and the pressures of the rolled-stock coolant that are respectively dispensed by the cooling bars 25, 27 (cooling parameters), the flows of the lubricant and the pressures of the lubricant that are respectively dispensed by the lubricating bars 31, 33 (lubrication parameters), the pass sequence distribution and the rolling speed. These parameters are respectively determined, for example, offline on the basis of a calculation model of at least part of the rolling train 1. For example, a model-based calculation of the run-in temperature of the rolled stock 2, the cooling and lubrication parameters, the pass sequence distribution and the rolling speed is conducted as a solution to a global optimization problem, with predetermination of a target function. This result in a multiplicity of solutions, among which the most appropriate one is likewise determined on the basis of a model, for example by taking into account further criteria, for example by additionally maximizing the rolling speed or maintaining a certain rolling-force distribution on the rolling stands 3 to 7. The parameters (offline parameters) determined in this way are each set manually or by the controller 39. As an alternative, some or all of the parameters (online parameters) can be regulated online as a function of the measured values from the measuring units 37 in such a way that the rolled-stock temperature in each rolling pass takes on a temperature value within the temperature range predetermined for the rolling pass. For example, the pass sequence distribution, the run-in temperature of the rolled stock 2 and the rolling speed are determined offline, while the cooling and lubrication parameters are regulated online as a function of the measured values from the measuring units 37.

[0065] FIG. 2 (FIG. 2) shows a flow diagram 100 of an exemplary embodiment of the method according to the invention for the cold rolling of rolled stock 2 in a rolling train 1, having method steps 101 to 106.

[0066] In a first method step 101, for each rolling pass a temperature range for the temperature of the rolled stock 2 in the rolling pass is predetermined.

[0067] In a second method step 102, as described above the offline parameters are determined on the basis of a calculation model of at least part of the rolling train 1, for example the pass sequence distribution, the run-in temperature of the rolled stock 2 and the rolling speed.

[0068] In a third method step 103, the cold rolling of the rolled stock 2 in the rolling train 1 is started using the offline parameters determined in the second method step 102 and predetermined initial values of the online parameters.

[0069] In a fourth method step 104, for each rolling pass a temperature of the rolled stock 2 is determined. For example, to this end the rolled-stock temperature is recorded for a rolling pass by means of at least one measuring unit 37, or the rolled-stock temperature in the rolling pass is calculated, for example as described above, by means of a calculation of the heat flow between the rolled stock and the working rollers in the rolling gap on the basis of a modeling of the heat transfer and/or by means of a calculation of the resulting deformation heat due to the plastic deformation of the rolled stock when the rolled stock is being rolled.

[0070] In a fifth method step 105, a check is made as to whether the rolled-stock temperature in each rolling pass takes on a temperature value within the temperature range predetermined for the rolling pass. If the check reveals that the rolled-stock temperature in each rolling pass takes on a temperature value within the temperature range predetermined for the rolling pass, the fourth method step 104 is carried out again. Otherwise, a sixth method step 106 is carried out.

[0071] In the sixth method step 106, the value of at least one online parameter is changed in order to bring the rolled-stock temperature into the predetermined temperature range in each rolling pass in which the rolled-stock temperature is outside the temperature range predetermined for the rolling pass. After the sixth method step 106, the fourth method step 104 is carried out again.

[0072] Although the invention has been illustrated and described in more detail by the preferred exemplary embodiment, the invention is not limited by the examples disclosed, and other variations can be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.

LIST OF REFERENCE SIGNS

[0073] 1 Rolling train

[0074] 2 Rolled stock

[0075] 3 to 7 Rolling stand

[0076] 9, 10 Working roller

[0077] 11 Rolling gap

[0078] 13 Rolling direction

[0079] 15 to 18 Back-up roller

[0080] 19 Heating device

[0081] 21 Roller coolant

[0082] 23 Rolled-stock coolant

[0083] 25, 27 Cooling bars

[0084] 29 Lubricant

[0085] 31, 33 Lubricating bars

[0086] 35 Collecting device

[0087] 37 Measuring unit

[0088] 39 Controller

[0089] 100 Flow diagram

[0090] 101 bis 106 Method step