A method and system for compensating for the gap between impact rolls in a precision rolling mill.

Abstract

This application provides a method and system for compensating for the impact of strip biting during finishing mill rolling. The method includes: obtaining the roll gap setting value of each finishing mill stand; before the first finishing mill stand bites the strip, executing the corresponding finishing mill stand roll gap adjustment strategy according to the strip thickness specification to compensate for the impact of the roll gap after biting, so that the head thickness of the finished strip meets the preset thickness requirement. This application effectively solves the problem of excessive strip head thickness caused by the mill roll gap being bounced open during the instant of strip biting, effectively improving the control accuracy of the head and overall length thickness of the finished strip; it avoids the recurrence of accidents caused by mismatch in the flow rate between stands and steel stacking due to excessive head thickness and rapid pressing down of the F7 roll gap during AGC feedback, thus improving the rolling stability of the production line.

Description

Technical Field

[0001] This invention relates to the field of steel production applications, and in particular to a method and system for compensating for the gap between impact rolls in precision rolling mills. Background Technology

[0002] In the finishing rolling process of hot strip steel, the thickness of the finished strip head is precisely controlled mainly by calculating the roll gap of stands F1-F7 through the actual temperature measured by the high temperature gauge at the entrance of the intermediate slab finishing mill. At the moment when the strip head enters the mill for biting, while the upper and lower work rolls of the mill press down on the strip, the strip exerts a reverse force on the mill (the mill generates a bouncing roll gap). This causes the roll gap of each finishing mill stand to be bounced open at the moment of biting, and the original secondary preset roll gap value cannot be maintained. In severe cases, the roll gap can be bounced open by more than +500um, resulting in a large deviation between the actual roll gap of the strip head and the secondary preset roll gap. This leads to an excessively thick finished strip head, affecting the accuracy of the finished strip head thickness control. At the same time, when the strip head is too thick, the thickness feedback control (AGC) quickly presses down the roll gap of stand F7, causing a mismatch in the flow rate between stands, which affects the stability of finishing rolling. Summary of the Invention

[0003] In view of the problems existing in the prior art, the present invention proposes a method and system for compensating for the impact roll gap when the steel bites in a finishing mill. This method mainly solves the problem that the roll gap is easily opened when the steel bites in the existing finishing mill stand, which can easily lead to excessive thickness at the head of the strip, thereby affecting the product thickness quality and control accuracy.

[0004] To achieve the above and other objectives, the technical solution adopted by the present invention is as follows.

[0005] This application provides a method for compensating for the impact of steel biting during finishing milling, including: obtaining the roll gap setting value of each finishing mill stand; before the first finishing mill stand bites the steel, executing the corresponding finishing mill stand roll gap adjustment strategy according to the strip thickness specification to compensate for the roll gap impact after steel biting, so that the head thickness of the strip after finishing milling meets the preset thickness requirement.

[0006] In one embodiment of this application, the method further includes: restoring the roll gap control value of the finishing mill stand to the roll gap setting value within a preset time interval after the first stand of the finishing mill bites the steel.

[0007] In one embodiment of this application, the step of executing a corresponding finishing mill roll gap adjustment strategy according to the strip thickness specification to compensate for the roll gap impact after the strip bites includes: comparing the strip thickness specification with a preset control thickness threshold to determine the control range in which the corresponding strip thickness specification falls; and calling the corresponding roll gap adjustment strategy according to the control range.

[0008] In one embodiment of this application, the roll gap adjustment strategy includes: when the control range is less than or equal to 6 mm, before the first stand of the finishing mill bites the steel, reducing the roll gap of the first to sixth stands of the finishing mill by 0.2 mm and reducing the roll gap of the seventh stand of the finishing mill by 0.25 mm.

[0009] In one embodiment of this application, the roll gap adjustment strategy includes: when the control range is greater than 6mm and less than or equal to 12mm, before the first stand of the finishing mill bites the steel, reducing the roll gap of the first to fourth stands of the finishing mill by 0.2mm, reducing the roll gap of the fifth stand of the finishing mill by 0.25mm, reducing the roll gap of the sixth stand of the finishing mill by 0.3mm, and reducing the roll gap of the seventh stand of the finishing mill by 0.35mm.

[0010] In one embodiment of this application, the roll gap adjustment strategy includes: when the control range is greater than 12mm and less than or equal to 16mm, before the first stand of the finishing mill bites the steel, reducing the roll gap of the first to fourth stands of the finishing mill by 0.2mm, reducing the roll gap of the fifth stand of the finishing mill by 0.25mm, reducing the roll gap of the sixth stand of the finishing mill by 0.35mm, and reducing the roll gap of the seventh stand of the finishing mill by 0.4mm.

[0011] In one embodiment of this application, the roll gap adjustment strategy includes: when the control range is greater than 16mm, before the first stand of the finishing mill bites the steel, reducing the roll gap of the first to fourth stands of the finishing mill by 0.25mm, reducing the roll gap of the fifth stand of the finishing mill by 0.3mm, reducing the roll gap of the sixth stand of the finishing mill by 0.4mm, and reducing the roll gap of the seventh stand of the finishing mill by 0.45mm.

[0012] In one embodiment of this application, the preset time interval between the execution of different roll gap adjustment strategies and the restoration to the roll gap setting value is different.

[0013] This application also provides a finishing mill bite impact roll gap compensation system, including: a data acquisition module for acquiring the roll gap setting value of each finishing mill stand; and a roll gap compensation module for executing the corresponding finishing mill stand roll gap adjustment strategy according to the strip thickness specification before the first finishing mill stand bites the strip to compensate for the roll gap impact after biting the strip, so that the head thickness of the strip after finishing milling meets the preset thickness requirement.

[0014] As described above, the method and system for compensating for the gap between impact rolls in a precision rolling mill, as proposed in this application, have the following beneficial effects.

[0015] This application performs preset roll gap impact compensation before the strip bites into the first stand of the finishing mill. By pre-adjusting the impact roll gap value of the corresponding stand, the deviation between the actual roll gap and the set roll gap value when the strip head is threaded is reduced, which can effectively reduce the problem of excessive thickness at the strip head, improve product thickness quality and overall thickness control accuracy, and enhance the stability of finishing mill rolling. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a method for compensating for the gap between impact rolls in a precision rolling mill, as described in one embodiment of this application.

[0017] Figure 2 This is a block diagram of a precision rolling mill impact roll gap compensation system in one embodiment of this application. Detailed Implementation

[0018] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0019] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0020] The inventor discovered through research that:

[0021] Existing control technologies lack effective measures to control the problem of the roll gap being snapped open during the bite of steel on the finishing mill stands F1-F7. This results in frequent over-thickness of the strip head, affecting the precision control of product quality and posing a significant risk of quality disputes due to thickness discrepancies. When the strip head is severely over-thick, the AGC feedback control rapidly presses down the roll gap on the F7 stand, affecting the rolling stability of the finishing mill. There have been multiple instances where excessive roll gap pressing during thickness feedback control has led to mismatches in the flow rate between stands, causing steel stacking accidents.

[0022] Based on the problems existing in the prior art, this application proposes a method and system for compensating for the gap between impact rolls in precision rolling mills. The technical solution of this application will be described in detail below with reference to specific embodiments.

[0023] Please see Figure 1 , Figure 1 This is a flowchart illustrating a method for compensating for the impact roll gap in a precision rolling mill, as described in one embodiment of this application. The method provided in this embodiment includes:

[0024] Step S100: Obtain the roll gap setting value for each finishing mill stand.

[0025] In one embodiment, before the intermediate billet is fed into the finishing mill, the control terminal issues a secondary preset roll gap. Each finishing mill stand will pre-adjust according to the secondary preset roll gap before performing finishing milling. The secondary preset roll gap is the roll gap setting value.

[0026] Step S110: Before the first stand of the finishing mill bites the steel, the corresponding finishing mill roll gap adjustment strategy is executed according to the strip thickness specification to compensate for the roll gap impact after biting the steel, so that the head thickness of the strip after finishing milling meets the preset thickness requirement.

[0027] In one embodiment, to avoid excessive deviation between the actual roll gap and the set roll gap value at the moment of strip biting in the finishing mill, it is necessary to optimize the roll gap control logic at the moment of strip biting in the finishing mill, thereby achieving precise control of the strip head thickness. In this embodiment, an impact roll gap compensation control is added before the first stand of the finishing mill bites the strip to achieve the adjustment of the roll gap of the corresponding finishing mill stand.

[0028] In one embodiment, after the roll gap adjustment before the strip bites, and after the corresponding stand bites the strip, the actual roll gap recovery value and roll gap setting value of each stand are reset after a preset time period to ensure the thickness control accuracy and stability of the subsequent strip rolling. This preset time period can be set according to different roll gap adjustment strategies and different strip thickness specifications.

[0029] In one embodiment, the step of executing a corresponding finishing mill roll gap adjustment strategy based on the strip thickness specification to compensate for roll gap impact after strip biting includes: comparing the strip thickness specification with a preset control thickness threshold to determine the control range into which the corresponding strip thickness specification falls; and invoking the corresponding roll gap adjustment strategy based on the control range. Different roll gap adjustment strategies can be pre-associated with corresponding control ranges, with the endpoints of the control ranges used as the corresponding control thickness thresholds. By comparing the currently produced strip thickness specification with the corresponding control thickness threshold, the control range into which the current strip thickness specification falls can be determined, and then the associated roll gap adjustment strategy can be invoked.

[0030] In one embodiment, the roll gap adjustment strategy includes: when the control range is less than or equal to 6mm, before the first stand of the finishing mill bites the steel, reducing the roll gap of the first to sixth stands of the finishing mill by 0.2mm and reducing the roll gap of the seventh stand of the finishing mill by 0.25mm. When the control thickness is <= 6.0mm, after the secondary setting of the finishing mill issues the roll gap setting values ​​for stands F1-F7, based on the secondary roll gap setting, before the F1 stand bites the steel, the roll gap of stands F1-F6 is automatically reduced by -0.2mm, and the roll gap of stand F7 is automatically reduced by -0.25mm.

[0031] 0.1s after the steel bites on the finishing mill stands F1-F7 (i.e., 0.1s after the rising edge of the steel bite signal on the F1-F7 stands arrives), the roll gap automatically returns to the secondary preset roll gap value, that is, the roll gap on the F1-F6 stands automatically rises by +0.2mm, and the roll gap on the F7 stand automatically rises by +0.25mm.

[0032] Taking a 3.39mm thickness specification as an example, the pre-set secondary roll gap is: 2392.38, 1373.14, 818.25, 714.81, 452.84, 442.43, 370.98 [10um]. After compensation for the steel bite impact roll gap, the actual roll gap is: 2372.38, 1353.14, 798.25, 694.81, 432.84, 422.43, 3 45.98 [10um], 0.1s after the steel biting signal of the F1-F7 stands arrives, each stand returns to the secondary preset roll gap as: 2392.38, 1373.14, 818.25, 714.81, 452.84, 442.43, 370.98 [10um], so that when the roll gap is opened at the moment the strip head bites, the roll gap is pressed down in advance to ensure that the thickness control of the strip head is normal.

[0033] In one embodiment, the roll gap adjustment strategy includes: when the control range is greater than 6mm and less than or equal to 12mm, before the first stand of the finishing mill bites the steel, the roll gap of the first to fourth stands of the finishing mill is reduced by 0.2mm, the roll gap of the fifth stand of the finishing mill is reduced by 0.25mm, the roll gap of the sixth stand of the finishing mill is reduced by 0.3mm, and the roll gap of the seventh stand of the finishing mill is reduced by 0.35mm. When 6.0mm < control thickness <= 12.0mm, before the F1 stand bites the steel, the roll gap of the F1-F4 stands is automatically reduced by -0.2mm, the roll gap of the F5 stand is automatically reduced by -0.25mm, the roll gap of the F6 stand is automatically reduced by -0.3mm, and the roll gap of the F7 stand is automatically reduced by -0.35mm.

[0034] 0.15 seconds after the steel bite signal arrives at the F1-F7 stands of the finishing mill, the roll gap automatically returns to the secondary preset roll gap value. That is, the roll gap of the F1-F4 stands automatically increases by +0.2mm, the roll gap of the F5 stand automatically increases by +0.25mm, the roll gap of the F6 stand automatically increases by +0.3mm, and the roll gap of the F7 stand automatically increases by +0.35mm.

[0035] Taking a 9.7mm thickness specification as an example, the pre-set secondary roll gap is: 3305.76, 2395.96, 1810.66, 1531.51, 1180.64, 1052.24, 986.34 [unit: 10um]. After compensation for the steel bite impact roll gap, the actual executed roll gap is: 3285.76, 2375.96, 1790.66, 1511.51, 1155.64, 1022.24, 95 1.34 [Unit: 10um], 0.15s after the steel biting signal arrives at stands F1-F7, each stand returns to the secondary preset roll gap as follows: 3305.76, 2395.96, 1810.66, 1531.51, 1180.64, 1052.24, 986.34 [Unit: 10um], so that when the roll gap is opened at the moment the strip head bites at each stand, the roll gap is pressed down in advance to ensure normal control of the strip head thickness.

[0036] In one embodiment, the roll gap adjustment strategy includes: when the control range is greater than 12mm and less than or equal to 16mm, before the first stand of the finishing mill bites the steel, the roll gap of the first to fourth stands of the finishing mill is reduced by 0.2mm, the roll gap of the fifth stand of the finishing mill is reduced by 0.25mm, the roll gap of the sixth stand of the finishing mill is reduced by 0.35mm, and the roll gap of the seventh stand of the finishing mill is reduced by 0.4mm. When the control thickness is 12.0mm < control thickness <= 16.0mm, before the F1 stand bites the steel, the roll gap of the F1-F4 stands is automatically reduced by -0.2mm, the roll gap of the F5 stand is automatically reduced by -0.25mm, the roll gap of the F6 stand is automatically reduced by -0.35mm, and the roll gap of the F7 stand is automatically reduced by -0.4mm.

[0037] 0.15 seconds after the steel bite signal arrives at the F1-F7 stands of the finishing mill, the roll gap automatically returns to the secondary preset roll gap value. That is, the roll gap of the F1-F4 stands automatically increases by +0.2mm, the roll gap of the F5 stand automatically increases by +0.25mm, the roll gap of the F6 stand automatically increases by +0.35mm, and the roll gap of the F7 stand automatically increases by +0.4mm.

[0038] Taking a 14.0mm thickness specification as an example, the secondary preset roll gap is: 3837.48, 2840.81, 2151.85, 1731.12, 3030.22, 1536.56, 1426.42 [10um]. After compensation for the steel bite impact roll gap, the actual executed roll gap is: 3817.48, 2820.81, 2131.85, 1711.12, 3005.22, 1501.56. 1386.42 [10um], 0.15s after the steel biting signal of the F1-F7 stands arrives, each stand returns to the secondary preset roll gap as: 3837.48, 2840.81, 2151.85, 1731.12, 3030.22, 1536.56, 1426.42 [10um], so that when the roll gap is opened at the moment the strip head bites, the roll gap is pressed down in advance to ensure that the thickness control of the strip head is normal.

[0039] In one embodiment, the roll gap adjustment strategy includes: when the control range is greater than 16mm, before the first stand of the finishing mill bites the steel, reducing the roll gap of the first to fourth stands of the finishing mill by 0.25mm, reducing the roll gap of the fifth stand by 0.3mm, reducing the roll gap of the sixth stand by 0.4mm, and reducing the roll gap of the seventh stand by 0.45mm. When the thickness is less than 16.0mm, before the F1 stand bites the steel, the roll gap of the F1-F4 stands is automatically reduced by -0.25mm, the roll gap of the F5 stand is automatically reduced by -0.3mm, the roll gap of the F6 stand is automatically reduced by -0.4mm, and the roll gap of the F7 stand is automatically reduced by -0.45mm.

[0040] 0.2 seconds after the steel bite signal arrives at the F1-F7 stands of the finishing mill, the roll gap automatically returns to the secondary preset roll gap value. Specifically, the roll gap of the F1-F4 stands automatically increases by +0.25mm, the roll gap of the F5 stand automatically increases by +0.3mm, the roll gap of the F6 stand automatically increases by +0.4mm, and the roll gap of the F7 stand automatically increases by +0.45mm.

[0041] Taking a 20.1mm thickness specification as an example, the secondary preset roll gap is: 4271.53, 3417.32, 2737.46, 2404.18, 3853.10, 2147.89, 2024.95 [10um]. After compensation for the steel bite impact roll gap, the actual executed roll gap is: 4246.53, 3392.32, 2712.46, 2379.18, 3823.10, 2107.89. 1979.95 [10um], 0.2s after the steel biting signal of the F1-F7 stands arrives, each stand returns to the secondary preset roll gap as: 4271.53, 3417.32, 2737.46, 2404.18, 3853.10, 2147.89, 2024.95 [10um], so that when the roll gap is opened at the moment the strip head bites, the roll gap is pressed down in advance to ensure that the thickness control of the strip head is normal.

[0042] Please see Figure 2 , Figure 2 This is a block diagram of a finishing mill bite impact roll gap compensation system according to an embodiment of this application. The system includes: a data acquisition module 20, used to acquire the roll gap setting value of each finishing mill stand; and a roll gap compensation module 21, used to execute the corresponding finishing mill stand roll gap adjustment strategy according to the strip thickness specification before the first finishing mill stand bites the strip to compensate for the roll gap impact after biting, so that the thickness of the strip head after finishing milling meets the preset thickness requirement.

[0043] The specific system execution process has been described in detail in the aforementioned method embodiments, and will not be repeated here.

[0044] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for compensating for the gap between impact rolls in a precision rolling mill, characterized in that, include: Obtain the roll gap setting values ​​for each finishing mill stand; Before the first stand of the finishing mill bites the steel, the corresponding finishing mill roll gap adjustment strategy is implemented according to the strip thickness specification to compensate for the roll gap impact after biting the steel, so that the head thickness of the finished strip meets the preset thickness requirement. Within a preset time interval after the first stand of the finishing mill bites the steel, the roll gap control value of each finishing mill stand is restored to the roll gap setting value; The steps of implementing the corresponding finishing mill roll gap adjustment strategy according to the strip thickness specification to compensate for the roll gap impact after strip biting include: comparing the strip thickness specification with a preset control thickness threshold to determine the control range in which the corresponding strip thickness specification falls; and calling the corresponding roll gap adjustment strategy according to the control range. The roll gap adjustment strategy includes: when the control range is less than or equal to 6mm, before the first stand of the finishing mill bites the steel, the roll gap of the first to sixth stands of the finishing mill is reduced by 0.2mm, and the roll gap of the seventh stand of the finishing mill is reduced by 0.25mm; The roll gap adjustment strategy includes: when the control range is greater than 6mm and less than or equal to 12mm, before the first stand of the finishing mill bites the steel, the roll gap of the first to fourth stands of the finishing mill is reduced by 0.2mm, the roll gap of the fifth stand of the finishing mill is reduced by 0.25mm, the roll gap of the sixth stand of the finishing mill is reduced by 0.3mm, and the roll gap of the seventh stand of the finishing mill is reduced by 0.35mm. The roll gap adjustment strategy includes: when the control range is greater than 12mm and less than or equal to 16mm, before the first stand of the finishing mill bites the steel, the roll gap of the first to fourth stands of the finishing mill is reduced by 0.2mm, the roll gap of the fifth stand of the finishing mill is reduced by 0.25mm, the roll gap of the sixth stand of the finishing mill is reduced by 0.35mm, and the roll gap of the seventh stand of the finishing mill is reduced by 0.4mm; The roll gap adjustment strategy includes: when the control range is greater than 16mm, before the first stand of the finishing mill bites the steel, the roll gap of the first to fourth stands of the finishing mill is reduced by 0.25mm, the roll gap of the fifth stand of the finishing mill is reduced by 0.3mm, the roll gap of the sixth stand of the finishing mill is reduced by 0.4mm, and the roll gap of the seventh stand of the finishing mill is reduced by 0.45mm.

2. The method for compensating for the gap between impact rolls in a precision rolling mill according to claim 1, characterized in that, After different roll gap adjustment strategies are implemented, the preset time interval for restoring to the roll gap setting value is different.

3. A finishing mill impact roll gap compensation system for implementing the finishing mill impact roll gap compensation method according to claim 1 or 2, characterized in that, include: The data acquisition module is used to obtain the roll gap setting values ​​for each finishing mill stand; The roll gap compensation module is used to perform the corresponding roll gap adjustment strategy of the finishing mill stand according to the strip thickness specification before the first stand bites the strip, so as to compensate for the roll gap impact after biting the strip and make the head thickness of the strip after finishing milling meet the preset thickness requirements.

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