Method and system for thickness control of a hot continuous rolling finishing mill train

Abstract

The application provides a thickness control method of a hot continuous rolling finishing mill group, comprising the following steps: S1, setting a pre-embedded roll gap according to secondary model data corresponding to a strip passing thickness specification; S2, when a strip head passes through a rack, performing head impact compensation; S3, when the strip does not pass through an outlet of the hot continuous rolling finishing mill group, calculating a rolling force AGC roll gap compensation value through the rolling force AGC, and performing roll gap compensation on the hot continuous rolling finishing mill group; and S4, when the strip passes through the outlet of the hot continuous rolling finishing mill group, calculating a monitoring AGC roll gap compensation value according to a thickness of the strip detected at the outlet, and performing roll gap compensation on the hot continuous rolling finishing mill group according to the monitoring AGC roll gap compensation value and the rolling force AGC roll gap compensation value. Through closed-loop control of the rolling force AGC and the monitoring AGC functions and in cooperation with the head impact compensation function, the application can achieve high-precision control of the thickness of the material at the outlet of the mill from a very short distance of the strip head.

Description

Technical Field

[0001] This invention relates to the field of electrical automation control technology, specifically to a method and system for thickness control of a hot strip mill finishing unit, and particularly to a high-precision thickness control method and system for a hot strip mill finishing unit. Background Technology

[0002] Currently, hot strip mills can achieve a strip thickness accuracy of 30-50µm. However, the thickness deviation at the head of the strip is typically quite poor, sometimes reaching 150-200µm, and it takes a considerable amount of time to reach a stable range. Therefore, rolled products often require the removal of the portion with the largest thickness deviation at the head before being delivered to downstream customers, resulting in resource waste and increased costs. However, as market demands for hot-rolled product quality increase, the ability to roll products with high-precision thickness will provide companies with a competitive advantage in capturing market share and gaining greater profits. Therefore, developing a technology that can stably control the strip thickness at the mill exit from the head is essential.

[0003] Patent document CN110538881A discloses a hot strip rolling thickness control method based on an improved internal die controller. The method includes: establishing a mathematical model of the hydraulic roll gap control system (HGC) for the mill stand; using particle swarm optimization (PSO) to identify the HGC system model; designing a traditional internal die monitoring AGC controller based on this model; and improving the traditional internal die monitoring AGC controller to make it a two-degree-of-freedom controller; and introducing an iterative learning algorithm into the monitoring AGC system based on the improved internal die controller. This invention patent uses an internal die controller to achieve high-precision adjustment of the monitoring AGC, but it does not consider the entire strip rolling process, especially the control of the strip head thickness, and therefore cannot guarantee the thickness accuracy of the strip head.

[0004] Therefore, it is necessary to develop a high-precision thickness control technology to improve the quality of hot-rolled finished products and meet the high demands of downstream customers. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for thickness control in hot continuous rolling mill finishing units.

[0006] A method for thickness control in a hot strip finishing mill according to the present invention includes:

[0007] Step S1: Set the pre-embedded roll gap according to the secondary model data corresponding to the strip thickness specification;

[0008] Step S2: When the strip head passes through the frame, head impact compensation is performed;

[0009] Step S3: Before the strip passes through the exit of the hot strip finishing mill, calculate the roll gap compensation value of the rolling force AGC through the rolling force AGC, and perform roll gap compensation on the hot strip finishing mill.

[0010] Step S4: When the strip passes through the exit of the hot continuous rolling mill, calculate the monitoring AGC roll gap compensation value based on the strip thickness detected at the exit; perform roll gap compensation on the hot continuous rolling mill based on the monitoring AGC roll gap compensation value and the rolling force AGC roll gap compensation value.

[0011] Preferably, step S2 includes:

[0012] When the strip head passes through the mill stand instantaneously, an impact is generated, which causes a change in the roll gap. The amount of change in the roll gap is set as the initial value for head impact compensation. The initial value is then adjusted based on the head thickness measured at the exit of the finishing mill to perform head impact compensation.

[0013] Preferably, step S3 includes:

[0014] Calculate the AGC roll gap compensation value for rolling force, including:

[0015] Based on the frame characteristics, the material plastic deformation coefficient Qn and the frame elastic coefficient M are set. n ; Set the gain coefficient G of the rolling force AGC according to the actual situation;

[0016] Calculate the outlet thickness latch value:

[0017] h n0 =S n0 +h fn F n0

[0018] Calculate the predicted outlet thickness:

[0019] h n =S n +h fn F n

[0020] Calculate the predicted thickness deviation value Δh at the export port. n :

[0021] Δh n =h n -h n0 =S n -S n0 +h fn F n one h fn F n0

[0022] Calculate the AGC roll gap compensation value ΔS n *:

[0023]

[0024] In the above formula:

[0025] S n0 h is the roll gap latch value. n0 For export thickness latch value; F n0 S is the rolling force latch value. n h is the actual roll gap value. n To predict the thickness at the export point; F n h is the actual rolling force. fn The equation for the rolling mill bounce curve is given.

[0026] Preferably, step S4 includes:

[0027] Calculate the AGC roll gap compensation value, including:

[0028] Based on the actual situation, set the gain coefficient G for monitoring AGC respectively. mon The coefficients K and integral time T of the PI controller S The time constant T between racks 0i The running time T from the i-th rolling mill Fi to the X-ray thickness gauge i ;

[0029] The specific formula is as follows:

[0030]

[0031] In the above formula:

[0032] ΔS n1 * To monitor the AGC roll gap compensation value; Δh x This refers to the thickness deviation measured by the thickness gauge used for export.

[0033] Preferably, the compensation process in step S4 includes:

[0034] ΔS total * =ΔS n * +ΔS n1 *

[0035] ΔS total * This is the roll gap compensation value.

[0036] A thickness control system for a hot strip finishing mill according to the present invention includes:

[0037] Module M1: Set the pre-embedded roll gap based on the secondary model data corresponding to the strip thickness specification;

[0038] Module M2: Performs head impact compensation when the strip head passes through the frame;

[0039] Module M3: When the strip has not passed the exit of the hot strip finishing mill, the rolling force AGC roll gap compensation value is calculated through the rolling force AGC, and the roll gap of the hot strip finishing mill is compensated.

[0040] Module M4: When the strip passes through the exit of the hot continuous rolling mill, calculate the monitoring AGC roll gap compensation value based on the strip thickness detected at the exit; and perform roll gap compensation on the hot continuous rolling mill based on the monitoring AGC roll gap compensation value and the rolling force AGC roll gap compensation value.

[0041] Preferably, module M2 includes:

[0042] When the strip head passes through the mill stand instantaneously, an impact is generated, which causes a change in the roll gap. The amount of change in the roll gap is set as the initial value for head impact compensation. The initial value is then adjusted based on the head thickness measured at the exit of the finishing mill to perform head impact compensation.

[0043] Preferably, the execution process of module M3 is as follows:

[0044] Calculate the AGC roll gap compensation value for rolling force, including:

[0045] Based on the characteristics of the frame, the material plastic deformation coefficient Q of the frame is set. n and frame elasticity coefficient M n ; Set the gain coefficient G of the rolling force AGC according to the actual situation;

[0046] Calculate the outlet thickness latch value:

[0047] h n0 =S n0 +h fn F n0

[0048] Calculate the predicted outlet thickness:

[0049] h n =S n +h fn F n

[0050] Calculate the predicted thickness deviation value Δh at the export port. n :

[0051] Δh n =h n -h n0 =S n -S n0 +h fn F n-h fn F n0

[0052] Calculate the AGC roll gap compensation value ΔS n * :

[0053]

[0054] In the above formula:

[0055] S n0 h is the roll gap latch value. n0 For export thickness latch value; F n0 S is the rolling force latch value. n h is the actual roll gap value. n To predict the thickness at the export point; F n h is the actual rolling force. fn The equation for the rolling mill bounce curve is given.

[0056] Preferably, the execution process of module M4 is as follows:

[0057] Calculate the AGC roll gap compensation value, including:

[0058] Based on the actual situation, set the gain coefficient G for monitoring AGC respectively. mon The coefficients K and integral time T of the PI controller S The time constant T between racks 0i The running time T from the i-th rolling mill Fi to the X-ray thickness gauge i ;

[0059] The specific formula is as follows:

[0060]

[0061] In the above formula:

[0062] ΔS n1 * To monitor the AGC roll gap compensation value; Δh x This refers to the thickness deviation measured by the thickness gauge used for export.

[0063] Preferably, the roll gap compensation process in module M4 is as follows:

[0064] ΔS total * =ΔS n * +ΔS n1 *

[0065] ΔS total * This is the roll gap compensation value.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] 1. This invention achieves high-precision control of the material thickness at the mill exit from a very short distance from the strip head through closed-loop control of rolling force AGC and monitoring AGC functions, combined with head impact compensation function.

[0068] 2. This invention develops and optimizes a high-precision thickness control method, combined with head impact compensation energy supply, which can improve the thickness control accuracy and form a complete thickness control system, thereby enabling the hot rolling production line to improve the yield and produce high-end products.

[0069] 3. This invention achieves high-precision thickness control through head thrust compensation of the finishing mill and closed-loop control of rolling force AGC and monitoring AGC. Attached Figure Description

[0070] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0071] Figure 1 This is a schematic flowchart of the method for thickness control in a hot strip finishing mill according to the present invention;

[0072] Figure 2 This is a flowchart illustrating Embodiment 1 of the present invention. Detailed Implementation

[0073] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0074] This invention addresses the problem of low thickness accuracy in hot strip mills by developing and optimizing a high-precision thickness control technology. This technology enables high-precision thickness control from a short distance from the strip head at the exit point, thereby allowing hot strip mills to improve yield and produce high-end products.

[0075] High-precision thickness control technology solution:

[0076] High-precision thickness control is achieved through the closed-loop control functions of automatic rolling force thickness control (AGC) and automatic monitoring thickness control (AGC) integrated into the finishing mill's automated control system, combined with the head thrust compensation function: Each stand of the finishing mill is set with speed, roll gap, and exit thickness data calculated based on the secondary model corresponding to the strip threading thickness specification. During the steel biting process, the pre-embedded roll gap is used to compensate for the roll gap changes caused by instantaneous impact. Then, the rolling force AGC needs to be activated in time to quickly compensate for the changes in stand tension according to the changes in rolling force. After the strip threading is completed and the thickness gauge at the mill exit detects the strip, the finishing mill's monitoring AGC uses the actual thickness deviation as the setting for closed-loop control. The monitoring AGC controls all stands of the finishing mill to adjust the roll gap simultaneously.

[0077] Step 1: Rolling Force AGC Compensation

[0078] During mill calibration, the rolling force and roll gap position at that time are latched and used as relative reference points for subsequent control. This includes Automatic Gauge Control (AGC).

[0079] The rolling force is controlled using a bounce equation. During parameter latching, the current exit thickness is saved as a standard value. Then, based on changes in the rolling force and subsequent rolling force changes during the rolling process, the change in the exit strip thickness is calculated, and the roll gap is adjusted according to this change in exit thickness. Specifically, the rolling pressure deviation measured by the pressure gauge and the thickness deviation Δh1 caused by different width factors are converted into a roll gap deviation value using the bounce equation. The change in roll gap position ΔS1 is measured based on position feedback, and this deviation is fed back to the automatic thickness control device for adjustment.

[0080] In this invention, the compensation amount of the rolling force AGC system is adjusted by using the gain coefficient G of the rolling force AGC. The system can adjust the corresponding parameters according to different steel grades or layers to achieve the best control effect.

[0081] Since rolling force AGC is an instantaneous response control method with a short delay time, it has a good effect on eliminating thickness deviations caused by uneven temperature.

[0082] The specific formula is as follows:

[0083] Calculate the outlet thickness latch value:

[0084] h n0 =S n0 +h fn F n0

[0085] Calculate the predicted outlet thickness:

[0086] hn =S n +h fn F n

[0087] Calculate the predicted thickness deviation value Δh at the export port. n :

[0088] Δh n =h n -h n0 =S n -S n0 +h fn F n -h fn F n0

[0089] Calculate the AGC roll gap compensation value ΔS n * :

[0090]

[0091] In the above formula:

[0092] s n0 h is the roll gap latch value. n0 For export thickness latch value; F n0 S is the rolling force latch value. n h is the actual roll gap value. n To predict the thickness at the export point; F n h is the actual rolling force. fn Here is the equation for the mill bounce curve; G is the gain coefficient of rolling force AGC; Qn is the material plastic deformation coefficient; M n is the frame elasticity coefficient.

[0093] The rolling mill bounce curve equation specifically reflects the change in roll gap caused by the elastic deformation of the rolling mill after being subjected to force. It reflects the relationship between force and roll gap changes. Specifically, it can be approximated as follows: h fn K represents the elastic deformation caused by the roll gap under stress. r Where is the mill stiffness coefficient and P is the rolling force.

[0094] Step 2: Monitor AGC compensation

[0095] Because indirect thickness measurement methods suffer from low accuracy, a high-precision thickness gauge is installed at the exit side of the last stand of the finishing mill to detect the actual thickness deviation Δh2 of the finished steel plate. This deviation is fed back to the automatic thickness control system of each stand and compared with the given target thickness value. When the two values ​​are equal, the thickness gauge output is zero (the output of the thickness gauge is the thickness deviation value Δh2), i.e., Δh2 = 0. If the measured thickness value is not equal to the given target thickness, resulting in a thickness deviation Δh2, this Δh2 is fed back to the automatic thickness control device for roll gap adjustment. The characteristic of this AGC system is that the detected thickness change and the control quantity do not occur simultaneously (because the thickness gauge is a certain distance from the centerline of the work rolls of the last stand). Therefore, when a thickness fluctuation is detected at the detection point, it cannot be reflected immediately, resulting in a certain lag time.

[0096] In this invention, the gain coefficient G of the AGC monitoring is increased. mon The compensation amount for AGC is adjusted using the coefficient K of the PI controller. The system can adjust the corresponding parameters according to different steel grades or layers to achieve the best control effect.

[0097] The specific formula is as follows:

[0098]

[0099] In the above formula:

[0100] ΔS n1 * To monitor the AGC roll gap compensation value; Δh x T represents the thickness deviation measured by the thickness gauge at the export site. 0i T is the time constant between racks, in seconds (sec); i The time from the i-th rolling mill Fi to the X-ray thickness gauge is in seconds (sec); K is the PI controller coefficient; T S G is the integration time; mon Q is the gain coefficient; n M is the plastic deformation coefficient of the material. n is the frame elasticity coefficient.

[0101] Step 3: Head impact compensation

[0102] When the strip head passes through the mill stand, the sudden change in roll gap caused by instantaneous rolling force variations makes sufficient control impossible in AGC mode alone, inevitably increasing the strip thickness at the next stand entrance. The head impact compensation value is generally predicted as follows: first, an initial value is set based on the roll gap change caused by the instantaneous impact during the mill bite (generally, 60% of the roll gap change is used as the initial impact compensation setting); then, appropriate adjustments are made based on the head thickness deviation measured by the thickness gauge after the finishing mill exits. Based on the prediction, the head impact compensation provides a forced reduction to compensate for the strip head thickness, i.e., the head impact compensation amount IDC. Although this compensation function begins when the strip bites at the previous stand, in the downstream stand, as the strip speed increases, the effective control time for the strip will shorten, and there is a certain delay in control, thus reducing the control effect downstream.

[0103] Step 4: Achieve high-precision thickness control by integrating the closed-loop control functions of the rolling force AGC and monitoring AGC, along with the head punching compensation function.

[0104] Calculate the roll gap compensation value ΔS total * :

[0105] ΔS total * =ΔS n * +ΔS n1 *

[0106] By using the roll gap compensation equation, the roll gap compensation value can be adjusted in real time to regulate the roll gap and improve the rolling effect.

[0107] This invention receives the impact compensation setting value from the secondary mill and feeds back the actual roll gap change to the secondary mill during the rolling mill's steel biting process. Through continuous learning and optimization, an optimal impact compensation setting can be obtained, which effectively solves the problem of large thickness deviation at the head.

[0108] Example 1

[0109] For strip steel with a normal rolling exit thickness of 1.5mm, taking the last stand of the rolling mill as an example, the additional value of the roll gap is ΔS. total * ;

[0110] Step 1: The secondary model sets the material plastic deformation coefficient Q of the frame. n and frame elasticity coefficient M n Automated control system, in which the frame flexibility coefficient M nIt is a nonlinear function of rolling force and rolling stand deformation calculated based on mill stiffness testing. The material plastic deformation coefficient Qn is calculated based on the chemical composition of different materials. In this example, the stand elasticity coefficient M... n =5700KN / mm, material plasticity coefficient Q n =22000KN / mm;

[0111] Step 2: The secondary model sends different head impact compensation amounts along with the set values ​​to the automated control system based on the different hardness grades of the rolled steel. In this example, the head impact compensation amount IDC = -120um.

[0112] Step 3: Set the gain coefficient G of the rolling force AGC in the automated control system to 0.90, and monitor the gain coefficient G of the AGC. mon =0.95, the PI controller coefficient for monitoring AGC is K=0.1, and the integral time is T. S =500ms, time constant T between racks 0i =0.45s, the travel time T from the i-th rolling mill Fi to the X-ray thickness gauge i =0.32s;

[0113] Step 4: After the strip is set at the entrance of the finishing mill, the automation system receives the head impact compensation amount IDC = -120um. At this time, the roll gap addition value is ΔS. total * =IDC=-120um, the mill roll gap is closed by 120um to wait for the strip to enter. When the strip head enters the mill and the actual rolling force measured by the rolling force detection device reaches 70% of the rolling force set by the secondary model, the head impact compensation amount IDC=0um is switched according to the internal logic. At this time, the roll gap additional value is ΔS. total * =IDC=0um. The change of this setting value completes the action of the additional roll gap through the position ramp of the position controller set in the automatic control system. This ensures that the change in roll gap during the opening process exactly offsets the increase in roll gap caused by the roll gap impact during the steel biting process, thus minimizing the impact of mechanical equipment on the thickness of the strip head.

[0114] Step 5: When the rolling force AGC performs parameter latching after impact compensation (500ms after the bite signal is triggered), it saves the roll gap latching value S at this time. n0 and rolling force latching value F n0 Then, based on the mill bounce curve issued by the secondary model, the strip exit thickness latch value is calculated and saved as the standard value for the controller. The calculation is performed using the following formula:

[0115] h n0 =Sn0 +h fn F n0

[0116] Since the mill bounce curve generated by the secondary model will yield different values ​​depending on the rolling force, a simplification has been made here, assuming that h is calculated based on relevant parameters. n0 =1.4mm.

[0117] Then, based on the changes in rolling force and subsequent rolling force during the rolling process, the change in the thickness of the exit strip is calculated, and the exit thickness is predicted using the following formula:

[0118] h n =S n +h fn F n

[0119] Similarly, here we assume that h is calculated based on relevant parameters. n =1.3mm.

[0120] Based on the above, the predicted thickness deviation for export can be calculated as follows:

[0121] Δh n =h n -h n0 =1.3-1.4=-0.1mm

[0122] Therefore, the strip exit thickness deviation can be converted into the actual rolling force AGC roll gap deviation of the mill using a formula. Since there is actually a delay in the reduction system, it should be multiplied by the gain coefficient. The specific calculation is as follows:

[0123]

[0124] This calculated value is then added to the roll gap setting of the rolling mill, i.e., ΔS at this point. total * =0.437mm. This process will be calculated in real time based on the actual changes in rolling force and the actual changes in rolling force during subsequent rolling processes.

[0125] Step 6: After the strip head passes through the thickness gauge, once the thickness gauge stably detects the strip thickness deviation, a 150ms delay is set before initiating the monitoring AGC. The monitoring AGC uses the measurement data from the finishing mill exit X-ray thickness gauge to correct the actual exit thickness via a PI controller, thus obtaining the absolute thickness value. Assume the thickness deviation Δh measured by the exit thickness gauge... x =60um, then the AGC roll gap compensation value at that time can be calculated using the following formula:

[0126]

[0127]

[0128] Step 7: Only through the coordinated actions of the rolling force AGC and the monitoring AGC can the stable thickness of the rolled material at the exit be quickly and accurately controlled. The mill roll gap compensation value can be derived from the above calculations:

[0129] ΔS total * =ΔS n * +ΔS n1 * =0.437 + 0.117 = 0.554 mm

[0130] Therefore, the roll gap compensation value at this moment is 0.554mm.

[0131] It should be noted that the roll gap compensation value is reset to zero when the AGC monitoring ends.

[0132] The present invention also provides a system for controlling the thickness of a hot strip mill finishing unit. The system for controlling the thickness of a hot strip mill finishing unit can be implemented by executing the process steps of the method for controlling the thickness of a hot strip mill finishing unit. That is, those skilled in the art can understand the method for controlling the thickness of a hot strip mill finishing unit as a preferred embodiment of the system for controlling the thickness of a hot strip mill finishing unit.

[0133] A system for thickness control in a hot strip mill finishing unit includes: module M1: setting a pre-embedded roll gap based on secondary model data corresponding to the strip thickness specification; module M2: performing head impact compensation when the strip head passes through the mill stand; module M3: calculating the roll gap compensation value of the rolling force AGC based on the rolling force AGC before the strip passes through the exit of the hot strip mill finishing unit, and performing roll gap compensation on the hot strip mill finishing unit; module M4: calculating the monitoring AGC roll gap compensation value based on the strip thickness detected at the exit of the hot strip mill finishing unit when the strip passes through the exit; and performing roll gap compensation on the hot strip mill finishing unit based on the monitoring AGC roll gap compensation value and the rolling force AGC roll gap compensation value.

[0134] Specifically, module M2 includes: when the strip head passes through the stand instantaneously, an impact is generated, which causes a change in the roll gap. The amount of change in the roll gap is set as the initial value for head impact compensation. Then, the initial value is adjusted according to the head thickness measured at the exit of the finishing mill to perform head impact compensation.

[0135] Specifically, the execution process of module M3 is as follows: Calculate the rolling force AGC roll gap compensation value, including: setting the material plastic deformation coefficient Q of the stand according to the stand characteristics. n and frame elasticity coefficient M nBased on the actual situation, set the gain coefficient G of the rolling force AGC; calculate the exit thickness latch value:

[0136] h n0 =S n0 +h fn F n0

[0137] Calculate the predicted outlet thickness:

[0138] h n =S n +h fn F n

[0139] Calculate the predicted thickness deviation value Δh at the export port. n :

[0140] Δh n =h n -h n0 =S n -S n0 +h fn F n -h fn F n0

[0141] Calculate the AGC roll gap compensation value ΔS n * :

[0142]

[0143] In the above formula: S n0 h is the roll gap latch value. n0 For export thickness latch value; F n0 S is the rolling force latch value. n h is the actual roll gap value. n To predict the thickness at the export point; F n h is the actual rolling force. fn The equation for the rolling mill bounce curve is given.

[0144] Specifically, the execution process of module M4 is as follows: Calculate the AGC roll gap compensation value, including:

[0145] Based on the actual situation, set the gain coefficient G for monitoring AGC respectively. mon The coefficients K and integral time T of the PI controller S The time constant T between racks 0i The running time T from the i-th rolling mill Fi to the X-ray thickness gauge i ;

[0146] The specific formula is as follows:

[0147]

[0148] In the above formula:

[0149] ΔS n1 * To monitor the AGC roll gap compensation value; Δh x This refers to the thickness deviation measured by the thickness gauge used for export.

[0150] Specifically, the roll gap compensation process in module M4 is as follows:

[0151] ΔS total * =ΔS n * +ΔS n1 *

[0152] ΔS total * This is the roll gap compensation value.

[0153] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0154] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for thickness control in a hot continuous rolling mill finishing unit, characterized in that, include: Step S1: Set the pre-embedded roll gap according to the secondary model data corresponding to the strip thickness specification; Step S2: When the strip head passes through the frame, head impact compensation is performed; Step S3: Before the strip passes through the exit of the hot strip finishing mill, calculate the roll gap compensation value of the rolling force AGC through the rolling force AGC, and perform roll gap compensation on the hot strip finishing mill. Step S4: When the strip passes through the exit of the hot continuous rolling mill, calculate the monitoring AGC roll gap compensation value based on the strip thickness detected at the exit. Based on the monitored AGC roll gap compensation value and the rolling force AGC roll gap compensation value, roll gap compensation is performed on the hot continuous rolling finishing mill. Step S3 includes: Calculate the AGC roll gap compensation value for rolling force, including: Based on the characteristics of the frame, set the material plastic deformation coefficient of the frame. and frame elasticity coefficient Set the gain coefficient of rolling force AGC according to the actual situation. ; Calculate the rolling force AGC roll gap compensation value : in, Prediction deviation value; Step S4 includes: Calculate the AGC roll gap compensation value, including: Set the gain coefficient for monitoring AGC according to the actual situation. PI controller coefficients Integral Time Time constant between racks The running time of the i-th rolling mill Fi to the X-ray thickness gauge ; The specific formula is as follows: ) In the above formula: To monitor the AGC roll gap compensation value; This refers to the thickness deviation measured by the thickness gauge used for export.

2. The method for thickness control of a hot strip mill finishing unit according to claim 1, characterized in that, Step S2 includes: When the strip head passes through the mill stand instantaneously, an impact is generated, which causes a change in the roll gap. The amount of change in the roll gap is set as the initial value for head impact compensation. The initial value is then adjusted based on the head thickness measured at the exit of the finishing mill to perform head impact compensation.

3. The method for thickness control in a hot strip mill finishing unit according to claim 1, characterized in that, Step S3 further includes: Calculate the outlet thickness latch value: Calculate the predicted outlet thickness: Calculate the predicted thickness deviation value for export : In the above formula: S n0 This is the roll gap lock value; This is the export thickness latch value; This is the rolling force latch value; This is the actual roll gap value; To predict export thickness; This refers to the actual rolling force. The equation for the rolling mill bounce curve is given.

4. The method for thickness control of a hot strip mill finishing unit according to claim 1, characterized in that, The compensation process in step S4 includes: = + This is the roll gap compensation value.

5. A system for thickness control in a hot continuous rolling mill finishing unit, characterized in that, include: Module M1: Set the pre-embedded roll gap based on the secondary model data corresponding to the strip thickness specification; Module M2: Performs head impact compensation when the strip head passes through the frame; Module M3: When the strip has not passed the exit of the hot strip finishing mill, the rolling force AGC roll gap compensation value is calculated through the rolling force AGC, and the roll gap of the hot strip finishing mill is compensated. Module M4: When the strip passes through the exit of the hot continuous rolling mill, calculate the monitoring AGC roll gap compensation value based on the strip thickness detected at the exit. Based on the monitored AGC roll gap compensation value and the rolling force AGC roll gap compensation value, roll gap compensation is performed on the hot continuous rolling finishing mill. The module M3 includes: Calculate the AGC roll gap compensation value for rolling force, including: Based on the characteristics of the frame, set the material plastic deformation coefficient of the frame. and frame elasticity coefficient Set the gain coefficient of rolling force AGC according to the actual situation. ; Calculate the rolling force AGC roll gap compensation value : in, Prediction deviation value; The module M4 includes: Calculate the AGC roll gap compensation value, including: Set the gain coefficient for monitoring AGC according to the actual situation. PI controller coefficients Integral Time Time constant between racks The running time of the i-th rolling mill Fi to the X-ray thickness gauge ; The specific formula is as follows: ) In the above formula: To monitor the AGC roll gap compensation value; This refers to the thickness deviation measured by the thickness gauge used for export.

6. The thickness control system for a hot strip finishing mill according to claim 5, characterized in that, The module M2 includes: When the strip head passes through the mill stand instantaneously, an impact is generated, which causes a change in the roll gap. The amount of change in the roll gap is set as the initial value for head impact compensation. The initial value is then adjusted based on the head thickness measured at the exit of the finishing mill to perform head impact compensation.

7. The thickness control system for a hot strip finishing mill according to claim 5, characterized in that, The execution process of module M3 also includes: Calculate the outlet thickness latch value: Calculate the predicted outlet thickness: Calculate the predicted thickness deviation value for export : In the above formula: S n0 This is the roll gap lock value; This is the export thickness latch value; This is the rolling force latch value; This is the actual roll gap value; To predict export thickness; This refers to the actual rolling force. The equation for the rolling mill bounce curve is given.

8. The thickness control system for a hot strip finishing mill according to claim 5, characterized in that, The roll gap compensation process in module M4 is as follows: = + This is the roll gap compensation value.

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