Method for correcting set load of last rack through hot continuous rolling of stainless steel

Abstract

The invention discloses a method for correcting the set load of an end rack in hot continuous rolling, which comprises the following steps of: S1, locking an actual roll gap value before the end rack bites steel, and calculating the actual roll gap adjustment amount of a rolling mill after the steel bites; s2, after AGC is started, the roll gap adjustment amount of a tail rack is calculated in real time; s3, judging whether the speed increase of the tail rack reaches the target rolling speed or not; s4, after speed increasing is completed, delaying for a period of time, and judging whether the current roll gap adjustment amount reaches the upper limit or the lower limit of roll gap adjustment allowed by a control system or not; and S5, if the roll gap adjustment amount reaches the upper limit or the lower limit of roll gap adjustment allowed by the control system, the next set load is corrected. The method is favorable for optimizing the adjustment amount distribution problem of the roll gap between the racks, and has positive significance for improving the rolling stability of the finishing mill.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgical automation control, and particularly relates to a method for correcting the set load of the last finishing stand in hot continuous rolling of stainless steel. Background Art

[0002] In the field of metal rolling, too large an adjustment range of the roll gap of the last finishing stand will cause rolling instability. Especially when the deviation of the set roll gap of the last finishing stand is large, the roll gap will lift or press down significantly to ensure the strip thickness at the outlet, but this will also cause rolling instability.

[0003] Currently, there is no existing technology for correcting the set load of the last finishing stand in hot continuous rolling. However, there are the following several existing technologies for improving the set accuracy of the roll gap: 1. (Patent application with publication number CN112547809B and title: A method for improving the roll gap setting accuracy of a rolling mill), which proposes a method to eliminate the influence of the change in the rolling mill stiffness on the roll gap setting during daily operations by compensating the zero adjustment accuracy of the roll gap of the rolling mill, and ensures the set accuracy of the rolled piece thickness. 2. (Patent application with publication number CN118023303B and title: A roll gap setting method, device and equipment during the production process of thin strip rolling), which proposes a method to obtain relevant data during the metal thin strip rolling process, calculate the set initial roll flattening radius, and then calculate the flattening radii of the upper and lower rolls according to the relevant data. When the relationship between this radius and the initial roll flattening radius meets the preset conditions, calculate the set roll gap of the metal thin strip. 3. (Patent application with publication number CN118162481B and title: A roll gap setting method for the finishing mill group of hot strip continuous rolling), which proposes a method to predict the inlet temperature of the strip when passing through each pass by using the hot strip continuous rolling temperature model, thereby improving the setting accuracy of the rolling force and roll gap of the finishing mill group.

[0004] However, the same roll gap setting accuracy can correspond to different set loads. Especially in cases where the rolling speed changes greatly, the temperature of the strip head and body changes greatly, etc., if the deviation of the set load of the last finishing stand is large, it is very easy to cause changes in the strip shape during the roll gap adjustment process, reducing the rolling stability. In summary, there is currently a lack of a method for correcting the set load of the last finishing stand in hot continuous rolling in the field of metal rolling, which can effectively correct the set load of the next piece through automated means combined with the roll gap adjustment amount during the rolling process, and control the stability of the strip during rolling.

[0005] Therefore, we introduce a method for correcting the set load of the last finishing stand in hot continuous rolling. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for correcting the set load of the last finishing stand in hot continuous rolling of stainless steel to solve the problems raised in the above background art.

[0007] To achieve the above object, the present invention provides the following technical solutions: 1. A method for correcting the set load of the last stand in hot continuous rolling of stainless steel, characterized by comprising the following steps: S1. Lock the actual roll gap value before the last stand bites the steel, for calculating the actual roll gap adjustment amount of the rolling mill after biting the steel; S2. After starting the AGC, calculate the roll gap adjustment amount of the last stand in real time; S3. Judge whether the speed increase of the last stand reaches the target rolling speed; S4. After the speed increase is completed, delay for a period of time, and judge whether the current roll gap adjustment amount reaches the upper limit or the lower limit of the roll gap adjustment allowed by the control system; S5. If the roll gap adjustment amount reaches the upper limit or the lower limit of the roll gap adjustment allowed by the control system, correct the set load of the next slab.

[0008] Preferably, in the step S1, it includes: locking the actual roll gap value before the last stand bites the steel, for calculating the actual roll gap adjustment amount of the rolling mill after biting the steel.

[0009] Preferably, in the step S2, it includes: after starting the AGC, calculate the roll gap adjustment amount of the last stand in real time.

[0010] Preferably, in the step S3, it includes: Judge whether the speed increase of the last stand reaches the target rolling speed, where the actual speed of the last stand is defined as Vact, with the unit of m / s; the maximum rolling speed of the last stand is defined as V max , with the unit of m / s, and the value is set according to the process parameters.

[0011] Preferably, in the step S4, it includes: after the speed increase is completed, delay for a period of time, and judge whether the current roll gap adjustment amount reaches the upper limit or the lower limit of the roll gap adjustment allowed by the control system.

[0012] Preferably, judge whether the current roll gap adjustment amount reaches the upper limit or the lower limit of the roll gap adjustment allowed by the control system; Among them, the upper limit of the roll gap adjustment allowed by the control system is Gap ulim , with the unit of mm, and the value range is 0.5 - 1.5; if the real-time roll gap adjustment amount Gap of the last stand st is greater than the upper limit of the allowed roll gap adjustment Gap ulim , it is considered that the current roll gap adjustment amount reaches the upper limit of the roll gap adjustment allowed by the control system; The lower limit of the roll gap adjustment allowed by the control system is Gap llim , with the unit of mm, and the value range is -1.5 - -0.5; If the real-time roll gap adjustment amount Gap of the last stand st is less than the lower limit of the allowed roll gap adjustment Gap llim , it is considered that the current roll gap adjustment amount reaches the lower limit of the roll gap adjustment allowed by the control system.

[0013] Preferably, in the step S5, it includes: if the roll gap adjustment amount reaches the upper limit or the lower limit of the roll gap adjustment allowed by the control system, then correct the set load of the next slab, and calculate the load value through a formula.

[0014] Compared with the prior art, the beneficial effects of the present invention are: the method for correcting the set load of the last stand in hot continuous rolling, (1). Before the last stand bites the steel, lock the actual roll gap value for calculating the actual roll gap adjustment amount of the rolling mill after biting the steel; after starting the AGC, calculate the roll gap adjustment amount of the last stand in real time; judge whether the speed increase of the last stand reaches the target rolling speed; after the speed increase is completed, delay for a period of time, and judge whether the current roll gap adjustment amount reaches the upper limit or the lower limit of the roll gap adjustment allowed by the control system; if the roll gap adjustment amount reaches the upper limit or the lower limit of the roll gap adjustment allowed by the control system, then correct the set load of the next slab; (2). The control method of the present invention is simple and easy to implement, which is beneficial to optimizing the distribution problem of the roll gap adjustment amount between stands and has a positive significance for improving the rolling stability of the finishing mill. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the execution flowchart of the method for correcting the set load of the last stand in hot continuous rolling provided by the embodiment of the present invention; Figure 2 is the schematic diagram of the rolling speed of the method for correcting the set load of the last stand in hot continuous rolling provided by the present invention; Figure 3 is the schematic diagram of the roll gap adjustment amount of the method for correcting the set load of the last stand in hot continuous rolling provided by the present invention; DETAILED DESCRIPTION OF THE INVENTION The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0016] Please refer to Figures 1 - 3 , the present invention provides a technical solution: a method for correcting the set load of the last stand in hot continuous rolling, locking the actual roll gap value before the last stand bites the steel for calculating the actual roll gap adjustment amount of the rolling mill after biting the steel; after starting the AGC, calculate the roll gap adjustment amount of the last stand in real time; judge whether the speed increase of the last stand reaches the target rolling speed; after the speed increase is completed, delay for a period of time, and judge whether the current roll gap adjustment amount reaches the upper limit or the lower limit of the roll gap adjustment allowed by the control system; if the roll gap adjustment amount reaches the upper limit or the lower limit of the roll gap adjustment allowed by the control system, then correct the set load of the next slab.

[0017] Specifically, the execution process of this method is as follows Figure 1 and includes the following steps: S1. Lock the actual roll gap value before the last stand bites steel, which is used to calculate the actual adjustment amount of the roll gap of the rolling mill after biting steel; Among them, the calculation formula for locking the actual roll gap value before the last stand bites steel is: Among them, Gap lkn represents the actual roll gap value locked before the last stand bites steel, with the unit of mm; Gap act represents the actual roll gap value, with the unit of mm; TA represents the execution cycle of the controller, and the given empirical value ranges from [1, 32]; N represents the number of sampling points before the last stand bites steel, and the given value range is [10, 100].

[0018] S2. After starting the AGC, calculate the adjustment amount of the roll gap of the last stand in real time; Among them, the calculation formula for the adjustment amount of the roll gap of the last stand is: Among them, Gap st represents the real-time adjustment amount of the roll gap of the last stand, with the unit of mm; Gap act represents the actual roll gap value, with the unit of mm; Gap lkn represents the actual roll gap value locked before the last stand bites steel, with the unit of mm.

[0019] S3. Judge whether the speed increase of the last stand reaches the target rolling speed; Among them, judge whether the speed increase of the last stand reaches the target rolling speed. Among them, the actual speed of the last stand is defined as V act , with the unit of m / s; the maximum rolling speed of the last stand is defined as V max , with the unit of m / s, and the value is set by process parameters.

[0020] S4. After the speed increase is completed, delay for a period of time, and judge whether the current roll gap adjustment amount reaches the upper limit or the lower limit of the roll gap adjustment allowed by the control system; Among them, after the speed increase is completed, delay for a period of time T acc , with the unit of ms, and this value is given empirically, and the value range is [200, 2000]. Judge whether the current roll gap adjustment amount reaches the upper limit or the lower limit of the roll gap adjustment allowed by the control system. Among them, the upper limit of the roll gap adjustment allowed by the control system is Gap ulim , with the unit of mm, and this value is given empirically, and the value range is [0.5, 1.5]; if the real-time adjustment amount of the roll gap of the last stand Gap st is greater than the upper limit of the allowable roll gap adjustment Gap ulim , it is considered that the current roll gap adjustment amount reaches the upper limit of the roll gap adjustment allowed by the control system. The lower limit of the roll gap adjustment allowed by the control system is Gapllim , in millimeters, this value is given by experience and the value range is [-1.5, -0.5]; if the real-time adjustment amount of the last stand roll gap Gap st is less than the allowable lower limit of roll gap adjustment Gap llim , it is considered that the current roll gap adjustment amount reaches the allowable lower limit of roll gap adjustment of the control system.

[0021] S5, if the roll gap adjustment amount reaches the allowable upper limit or lower limit of roll gap adjustment of the control system, then correct the set load of the next slab; Among them, the calculation formula for correcting the set load of the next slab is as follows: Among them, Load next represents the set load of the next slab of the last stand, Load this represents the set load of the current slab of the last stand, η represents the correction rate of the set load each time, this value is given by experience, if the roll gap adjustment amount reaches the upper limit, the value range of η is [5%, 10%], if the roll gap adjustment amount reaches the lower limit, the value range of η is [-10%, -5%].

[0022] Next, the implementation process of the method of the present invention will be described in combination with specific application examples.

[0023] In this application example, the operations are carried out according to the following steps: (1) Lock the actual roll gap value before the last stand bites the steel, which is used to calculate the actual adjustment amount of the roll gap of the rolling mill after biting the steel; take the execution period TA of the controller as 16 ms, and the number of sampling points before the last stand bites the steel is 8. The actual roll gap data of the sampling points are shown in Table 1: Table 1 According to the formula for calculating the locked actual roll gap value before the last stand bites the steel: The locked actual roll gap value Gap before the last stand bites the steel is obtained lkn The result is 3.000.

[0024] (2) After starting the AGC, calculate the real-time adjustment amount of the roll gap of the last stand. The formula for calculating the adjustment amount of the roll gap of the last stand is: The adjustment amount of the roll gap of the last stand is obtained as the actual feedback value of the roll gap minus the locked roll gap value before biting the steel, and the locked actual roll gap value before biting the steel is 3.000 mm.

[0025] (3) Judge whether the last stand has accelerated to the target rolling speed. Assume that the target rolling speed is 14.5 m / s, and the actual rolling speed reaches 14.5 m / s, that is, it is considered that the last stand has accelerated to the target rolling speed.

[0026] After the speed-up is completed, after a time delay, it is judged whether the current roll gap adjustment amount reaches the upper or lower limit of the roll gap adjustment allowed by the control system, where the upper limit of the roll gap adjustment allowed by the control system, Gap lim is defined as 1 mm. After the speed-up is completed, a time delay of 200 ms is set. Assuming that the actual roll gap is 4.000 mm, according to the roll gap adjustment amount calculation formula, the real-time roll gap adjustment amount of the last stand, Gap st is 1.000 mm.

[0027] (5) If the roll gap adjustment amount reaches the upper or lower limit of the roll gap adjustment allowed by the control system, then the set load of the next slab is corrected. As can be seen from step (4), the real-time roll gap adjustment amount of the last stand, Gap st reaches the upper limit of the roll gap adjustment allowed by the control system, Gap lim , according to the formula for correcting the set load of the next slab: Defining the set load reduction rate η as 5%, the set load of the next slab can be obtained as 95% of the current set load.

[0028] Through the above application examples, it can be found that the method for correcting the set load of the last stand in the hot strip rolling of the present invention can use the roll gap adjustment range of the strip body as the basis for correcting the load setting in actual production, and has an adaptive learning and correction function for the AGC adjustment range during the rolling process, which is more convenient and flexible. For optimizing the distribution of the roll gap adjustment amount between stands, reducing the phenomenon of large roll gap adjustments, and stabilizing the rolling stability of the finishing mill, it has a positive significance.

[0029] In summary, the control method of this embodiment locks the actual roll gap value before the last stand bites the steel to calculate the actual roll gap adjustment amount of the rolling mill after biting the steel; after starting the AGC, it calculates the roll gap adjustment amount of the last stand in real time; judges whether the speed-up of the last stand reaches the target rolling speed; after the speed-up is completed, after a time delay, it judges whether the current roll gap adjustment amount reaches the upper or lower limit of the roll gap adjustment allowed by the control system; if the roll gap adjustment amount reaches the upper or lower limit of the roll gap adjustment allowed by the control system, then the set load of the next slab is corrected. It is beneficial to optimize the distribution of the roll gap adjustment amount between stands and has a positive significance for improving the rolling stability of the finishing mill.

[0030] In addition, it should be noted that the present invention can be provided as a method, a device, or a computer program product. Therefore, the embodiments of the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the embodiments of the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code.

[0031] Embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, an embedded processor, or other programmable data processing terminal devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing terminal devices generate a device for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks.

[0032] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks. These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device, such that a series of operation steps are executed on the computer or other programmable terminal device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable terminal device provide steps for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks.

[0033] It should also be noted that in this document, the terms "including", "comprising", or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article, or terminal device including the said element.

[0034] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for setting load of the final stand of hot rolling stainless steel correction, characterized in that: The steps include: S1. The actual roll gap value is locked before the last stand bites the steel, which is used to calculate the actual adjustment amount of the mill roll gap after the steel bite; S2. After starting AGC, calculate the adjustment amount of the roller gap of the last stand in real time; S3. Determine whether the final stand speed reaches the target rolling speed; S4. After the speed increase is completed, a delay is made to determine whether the current roll gap adjustment amount reaches the upper or lower limit of the roll gap adjustment allowed by the control system; S5. If the roll gap adjustment amount reaches the upper or lower limit of the roll gap adjustment allowed by the control system, the next set load is corrected.

2. A method for setting load of a hot rolling stainless steel correction final stand according to claim 1, characterized in that: The step S1 includes: locking the actual roll gap value before the last stand bites the steel, which is used to calculate the actual adjustment amount of the roll gap of the rolling mill after biting the steel.

3. The method for setting load of the final stand of hot rolling stainless steel correction according to claim 1, characterized in that: The step S2 includes: starting the AGC and calculating the roller gap adjustment amount of the last stand in real time.

4. The method for setting load of the final stand of hot rolling stainless steel correction according to claim 1, characterized in that: The S3 step includes: Determine whether the speed of the last stand reaches the target rolling speed, where the actual speed of the last stand is defined as Vact, in m / s; the maximum rolling speed of the last stand is defined as V max , the unit is m / s, and the value is set as the process parameter.

5. The method for setting load of the final stand of hot rolling stainless steel correction according to claim 1, characterized in that: The step S4 includes: after the speed increase is completed, a delay is performed to determine whether the current roll gap adjustment amount reaches the upper or lower limit of the roll gap adjustment allowed by the control system.

6. A method for setting load of a hot rolling stainless steel correction final stand according to claim 5, characterized in that: Determining whether the current roll gap adjustment amount reaches the upper or lower limit of the roll gap adjustment allowed by the control system; Among them, the control system allows the roller gap to adjust the upper limit Gap ulim , in mm, the value range is 0.5~1.5; if the real-time adjustment value of the roller gap of the last stand is Gap st Greater than the upper limit of the roller gap adjustment Gap ulim , that is, it is considered that the current roll gap adjustment amount reaches the upper limit of the roll gap adjustment allowed by the control system; The control system allows the roll gap to be adjusted to the lower limit Gap llim , the unit is mm, the value range is -1.5~-0.5; If the end stand roll gap real-time adjustment Gap st Less than the lower limit of the roller gap adjustment Gap llim , that is, it is considered that the current roll gap adjustment amount has reached the lower limit of the roll gap adjustment allowed by the control system.

7. The method for setting load of the final stand of hot rolling stainless steel correction according to claim 1, characterized in that: The step S5 includes: if the roll gap adjustment amount reaches the upper or lower limit of the roll gap adjustment allowed by the control system, then correcting the next set load and calculating the load value through a formula.

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