A method and system for finishing rolling pre-computing rolling force correction

Abstract

The application provides a kind of finish rolling pre-computing rolling force correction method and system, the method comprises: obtaining the production parameters of current strip steel and previous strip steel, and the average detection temperature of intermediate billet head in the last pass of rough rolling;Determine whether the current strip steel and the previous strip steel are the same steel grade according to the production parameters;If the current strip steel and the previous strip steel are the same steel grade, determine whether the intermediate billet incoming temperature span is out of limit;If the intermediate billet incoming temperature span is out of limit, calculate the rolling force correction coefficient according to the average detection temperature of intermediate billet head in the last pass of rough rolling of current strip steel;Limit the amplitude of rolling force correction coefficient according to the strength level of steel grade, and use the rolling force correction coefficient after amplitude limiting to correct the preset rolling force of finish rolling, to obtain the corrected preset rolling force, and execute the corrected preset rolling force.This application can effectively improve the accuracy of finish rolling preset rolling force, improve the thickness size control accuracy of strip steel head and full length, and improve the stability of strip steel head threading.

Description

Technical Field

[0001] This invention relates to the field of process control technology for hot strip steel rolling in metallurgy, and in particular to a method and system for correcting pre-calculated rolling force in finishing rolling. Background Technology

[0002] In the hot strip rolling process, the accuracy of the pre-set rolling force calculation directly determines the thickness quality and strip threading stability of the strip head. However, due to the use of manual steel firing in some heating furnaces, the exit temperature of different heating furnaces varies significantly, resulting in a large temperature range for intermediate billets of the same steel grade and specification. The different intermediate billet temperatures lead to different threading speeds calculated in the pre-set rolling process and different cooling water usage strategies for the strip. Existing pre-set calculation models for the pre-set rolling force cannot fully adapt to such a large temperature range in the intermediate billets, resulting in a large deviation between the pre-set rolling force and the actual measured rolling force at the strip head. This low accuracy of the pre-set rolling force leads to large thickness deviations at the strip head for the same steel grade and specification, affecting the precise control of the strip head and overall thickness, and ultimately impacting the threading stability of the strip head. Summary of the Invention

[0003] This invention provides a method and system for correcting pre-calculated rolling force in precision rolling, in order to improve the accuracy of strip head and overall thickness control and the stability of strip threading at the head.

[0004] This invention provides a method for correcting pre-calculated rolling force in finishing mills, comprising: acquiring the production parameters of the current strip and the previous strip, and the average detected temperature of the head of the intermediate slab in the last pass of roughing milling; determining whether the current strip and the previous strip are of the same steel grade and specification based on the production parameters; if the current strip and the previous strip are of the same steel grade and specification, determining whether the temperature range of the intermediate slab incoming material exceeds the limit; if the temperature range of the intermediate slab incoming material exceeds the limit, calculating a rolling force correction coefficient based on the average detected temperature of the head of the intermediate slab in the last pass of roughing milling of the current strip; limiting the rolling force correction coefficient according to the steel grade strength level, and using the limited rolling force correction coefficient to correct and calculate the pre-set rolling force in finishing milling, obtaining the corrected pre-set rolling force, and issuing the corrected pre-set rolling force for execution.

[0005] In one embodiment of the present invention, the production parameters include: obtaining the rolling grade, target control thickness, target control width, and target final rolling temperature of the current strip and the previous strip; determining whether the current strip and the previous strip are of the same steel grade and specification based on the production parameters includes: If the steel grade, the target controlled thickness, the target controlled width, and the target final rolling temperature are all in the same control layer, then the current strip steel is determined to be of the same steel grade and specification as the previous strip steel.

[0006] In one embodiment of the present invention, determining whether the temperature range of the intermediate billet exceeds the limit includes: Calculate the temperature deviation between the current strip and the average detected temperature of the head of the intermediate billet in the last roughing pass of the previous strip; If the temperature deviation is greater than or equal to 50°C, or if the temperature deviation is less than or equal to -50°C, then the temperature range of the intermediate billet is determined to be out of limit.

[0007] In one embodiment of the present invention, the rolling force correction coefficient is calculated based on the average detected temperature of the intermediate slab head in the final roughing pass of the current strip, using the following formula:

[0008] In the formula, The rolling force correction factor is... For the corresponding steel grade correction factor, The average measured temperature of the head of the intermediate billet in the final roughing pass of the current strip.

[0009] In one embodiment of the present invention, the limiting processing of the rolling force correction coefficient according to the steel grade strength level includes: Obtain the yield strength of the steel grade to which the current strip belongs. If the yield strength If so, the amplitude limit range is set to [0.95, 1.05]. If the yield strength If so, the amplitude limit range is set to [0.9, 1.1]. If the yield strength Then the amplitude limit range is set to [0.85, 1.15].

[0010] In one embodiment of the present invention, after setting the limiting range, the method further includes: determining whether the calculated rolling force correction coefficient exceeds the corresponding limiting range; and if the calculated rolling force correction coefficient exceeds the corresponding limiting range, forcibly setting the rolling force correction coefficient to the corresponding boundary value.

[0011] In one embodiment of the present invention, the correction calculation of the pre-set rolling force for finishing rolling using the rolling force correction coefficient after the width limiting treatment is performed using the following formula:

[0012] In the formula, The modified preset rolling force, For the original preset rolling force, This is the rolling force correction factor. This is the rack number.

[0013] This invention also provides a finishing mill pre-calculated rolling force correction system, comprising: a parameter acquisition module for acquiring the production parameters of the current strip and the previous strip, and the average detection temperature of the intermediate billet head in the last pass of roughing mill; a specification determination module for determining whether the current strip and the previous strip are of the same steel grade and specification; a temperature difference determination module for determining whether the temperature range of the intermediate billet exceeds the limit when the current strip and the previous strip are of the same steel grade and specification; a coefficient calculation module for calculating a rolling force correction coefficient based on the average detection temperature of the intermediate billet head in the last pass of roughing mill when the temperature range of the intermediate billet exceeds the limit; a limiting module for limiting the rolling force correction coefficient according to the steel grade strength level; and a correction execution module for using the limited rolling force correction coefficient to correct the pre-set rolling force of finishing mill, obtaining the corrected pre-set rolling force, and issuing the corrected pre-set rolling force for execution.

[0014] The beneficial effects of this invention are as follows: This invention proposes a method and system for correcting pre-calculated rolling force in finishing rolling. By acquiring the production parameters of the current strip and the previous strip, as well as the temperature of the intermediate billet head, when it is determined that the steel grade and specifications are the same and the intermediate billet temperature range exceeds the limit, the rolling force correction coefficient is calculated based on the average detected temperature of the intermediate billet head in the last roughing pass of the current strip. This is combined with the steel grade strength level for amplitude limiting processing to correct the pre-set rolling force in finishing rolling. This method uses the rolling force correction coefficient to compensate for the rolling force setting deviation caused by the deformation resistance change due to drastic fluctuations in the intermediate billet temperature. Simultaneously, based on the amplitude limiting protection of steel grade strength, it ensures that the rolling force correction range is within a safe and controllable range. Because it accurately compensates for the rolling force calculation deviation caused by the fluctuation of the intermediate billet temperature without compromising the stability of the original rolling force calculation model, it improves the problem that the existing control model cannot adapt to large-range fluctuations in the intermediate billet temperature, effectively improving the thickness dimension control accuracy of the strip head and the entire length, and enhancing the head threading stability. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0016] In the attached diagram: Figure 1 This is a flowchart illustrating an optional pre-calculated rolling force correction method for finishing mills provided in an embodiment of the present invention. Figure 2This is a structural block diagram of an optional finishing mill pre-calculated rolling force correction system provided in an embodiment of the present invention. Detailed Implementation

[0017] 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. 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. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0018] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. 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.

[0019] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0020] In the actual production process of hot-rolled strip steel, due to the manual firing mode of the heating furnaces, the temperature deviation of the exit furnaces from different heating furnaces is large, resulting in a huge range of incoming slab temperatures for the same steel grade and specification. For example, for the common low-alloy steel Q355B series 11.8mm×1510mm specification, the temperature range measured by the pyrometer in the last pass of the roughing mill is between 920℃ and 1070℃, a temperature range of nearly 150℃. The drastic fluctuation of the incoming slab temperature directly causes nonlinear changes in the deformation resistance of the strip, which in turn affects the threading speed calculated in the finishing mill and the cooling water usage strategy for the finishing strip. The existing finishing mill pre-set calculation model cannot fully adapt to such a large temperature range of the intermediate slab, resulting in a large deviation between the pre-set calculated rolling force and the actual measured rolling force at the head of the strip. Due to the low accuracy of the set rolling force, the thickness deviation at the head of the strip of the same steel grade and specification is large, affecting the accurate control of the thickness at the head and along the entire length of the strip, and affecting the threading stability of the head of the finishing strip.

[0021] The present invention provides a method for correcting pre-calculated rolling force in finishing mills. It introduces a feedforward compensation mechanism based on the judgment of the temperature span of intermediate billets exceeding the limit between the last pass of roughing mills and the entrance of finishing mills, and combines the strength level of steel grades for safety limiting. In this way, without destroying the stability of the original rolling force model, it accurately compensates for the rolling force calculation deviation caused by the temperature fluctuation of the intermediate billet.

[0022] In some exemplary embodiments, please refer to Figure 1 , Figure 1 This is a flowchart illustrating an optional pre-calculated rolling force correction method for finishing mills provided in an embodiment of the present invention. The pre-calculated rolling force correction method for finishing mills mainly includes the following steps: Step S100: Obtain the production parameters of the current strip and the previous strip, as well as the average detection temperature of the head of the intermediate billet in the last pass of the roughing mill. Production parameters typically include strip size information, steel grade information, and process target parameters.

[0023] Step S110: Determine whether the current strip steel and the previous strip steel are of the same steel type and specification based on the production parameters.

[0024] Step S120: If the current strip and the previous strip are of the same steel grade and specification, determine whether the temperature range of the intermediate billet exceeds the limit. The setting rolling force correction will only be triggered when the temperature range of the intermediate billet exceeds the adaptive capability of the conventional model.

[0025] Step S130: If the temperature range of the intermediate billet exceeds the limit, calculate the rolling force correction coefficient based on the average detected temperature of the head of the intermediate billet in the final roughing pass of the current strip. This rolling force correction coefficient k T Used to characterize the degree of deviation of strip deformation resistance from the standard state at the current intermediate billet large span temperature.

[0026] Step S140: The rolling force correction coefficient is limited according to the steel grade and strength level. The pre-set rolling force for finishing mill is then calculated using the limited rolling force correction coefficient to obtain the corrected pre-set rolling force, which is then issued for execution. To prevent the calculated correction coefficient from being too large and causing the pre-set rolling force for finishing mill to exceed the limit under abnormal conditions, safety boundary constraints must be applied to the calculation results. The limited rolling force correction coefficient k... T Preset rolling force F for finishing mill i A corrected calculation is performed to obtain the corrected preset rolling force F. t and the corrected preset rolling force F t Issued and implemented.

[0027] The method described above effectively improves the problem that the existing control model cannot adapt to the large-scale temperature fluctuation of the incoming intermediate billet, reduces the frequent head thickness deviation of the same steel grade and specification when the specification is not changed, and improves the thickness dimension control accuracy of the strip head and the whole length, as well as the head threading stability.

[0028] In some exemplary embodiments, determining whether the current strip and the previous strip are of the same steel grade and specification specifically includes: obtaining the rolling grade, target control thickness, target control width, and target final rolling temperature of the current strip and the previous strip; determining whether the rolling grade, target control thickness, target control width, and target final rolling temperature are all in the same control layer; if the rolling grade, target control thickness, target control width, and target final rolling temperature are all in the same control layer, then the current strip and the previous strip are determined to be of the same steel grade and specification.

[0029] In some exemplary embodiments, the determination of whether the temperature span of the intermediate billet exceeds the limit specifically includes: calculating the temperature deviation between the average detected temperature of the head of the intermediate billet in the last roughing pass of the current strip and the previous strip; if the temperature deviation is greater than or equal to 50°C, or the temperature deviation is less than or equal to -50°C, then it is determined that the temperature span of the intermediate billet exceeds the limit.

[0030] This embodiment first calculates the difference in average detected temperature at the head of the intermediate billet in the last roughing pass between the current strip and the previous strip to obtain the temperature deviation. Only when the temperature deviation is greater than or equal to 50℃ or less than or equal to -50℃ is it determined that the temperature range of the intermediate billet incoming material exceeds the limit.

[0031] In some embodiments, the rolling force correction factor k is calculated based on the average detected temperature of the intermediate slab head in the final roughing pass of the current strip. T The following formula is used for calculation: Equation (1) In equation (1), k T α3 is the rolling force correction factor, α3 is the correction factor for the corresponding steel grade, and t is the average detection temperature of the head of the intermediate billet in the last roughing pass of the current strip.

[0032] In some exemplary instances, the rolling force correction factor is limited according to the steel grade strength level, including: obtaining the yield strength σ of the current strip steel grade. s If the yield strength σ s If the yield strength is less than or equal to 300 MPa, the limit range is set to [0.95, 1.05]; if the yield strength σs is greater than 300 MPa and less than or equal to 500 MPa, the limit range is set to [0.9, 1.1]; if the yield strength σs is greater than 500 MPa, the limit range is set to [0.85, 1.15].

[0033] Specifically, for mild steel with a yield strength of 300 MPa or less, its deformation resistance is relatively low, and its absolute sensitivity to temperature fluctuations is relatively low. Limiting its correction range to ±5% is sufficient to handle typical temperature ranges. For medium-strength steel, this is relaxed to ±10%. However, for high-strength steel with a yield strength greater than 500 MPa, due to its high content of alloying elements, it is prone to work hardening in low-temperature regions, and its deformation resistance is extremely sensitive to temperature drops. Therefore, it is given a maximum correction range of ±15%. This differentiated limitation strategy ensures sufficient correction space for high-strength steel while reducing the risk of over-correction for mild steel, thus ensuring the closed-loop stability of the control system.

[0034] In some embodiments, after setting the limiting range, the method further includes: determining whether the calculated rolling force correction coefficient exceeds the corresponding limiting range; if the calculated rolling force correction coefficient exceeds the corresponding limiting range, then forcibly setting the rolling force correction coefficient to the corresponding boundary value.

[0035] For example, for high-strength steel, when the theoretical k T When the value is 1.20, the system forcibly truncates it and assigns it the upper limit boundary value of 1.15. When the theoretical correction requirement is huge, the system will still provide the maximum compensation force allowed under the current safety framework to prevent drastic fluctuations in the rolling force setting.

[0036] In some exemplary embodiments, the pre-set rolling force Fi of the finishing mill is corrected using the rolling force correction coefficient kT after the limiting treatment, and the following formula is used for calculation: Equation (2) In equation (2), F t For the corrected preset rolling force, F i For the original preset rolling force, k T This is the rolling force correction factor.

[0037] Based on the above embodiments of the present invention, the following solutions are provided: 1) The existing control model cannot adapt to the temperature range of large fluctuations in the temperature of the incoming intermediate billet, resulting in large deviations in the pre-set rolling force calculation; 2) The existing steel grade and specification frequently exhibit large head thickness deviations when the specification is not changed, affecting the head thickness and plate quality control of the same steel grade and specification strip; 3) The large deviation in the pre-set rolling force of the finishing mill leads to unstable head threading, resulting in frequent head breakage, crushing, and steel piling accidents in extremely thin strips.

[0038] Please see Figure 2 , Figure 2This is a structural block diagram of an optional finishing mill pre-calculated rolling force correction system provided in an embodiment of the present invention. The finishing mill pre-calculated rolling force correction system includes: a parameter acquisition module 20, a specification determination module 21, a temperature difference determination module 22, a coefficient calculation module 23, a limiting module 24, and a correction execution module 25.

[0039] The parameter acquisition module 20 is used to acquire the production parameters of the current strip and the previous strip, as well as the average detected temperature t of the intermediate billet head in the last pass of the roughing mill. Parameter acquisition module 20 serves as the system's data entry point, monitoring and capturing upstream and downstream production parameters and key temperature variables in real time.

[0040] The specification determination module 21 is used to determine whether the current strip and the previous strip are of the same steel grade and specification. The specification determination module 21 strictly identifies whether the current working condition belongs to continuous rolling of the same specification.

[0041] The temperature difference determination module 22 is used to determine whether the temperature span of the intermediate billet exceeds the limit when the current strip and the previous strip are of the same steel grade and specification. The temperature difference determination module 22 accurately captures abnormal temperature spans that exceed the threshold.

[0042] The coefficient calculation module 23 is used to calculate the rolling force correction coefficient k based on the average detection temperature t of the head of the intermediate billet in the final roughing pass of the strip when the temperature range of the intermediate billet exceeds the limit. T The coefficient calculation module 23 calls the built-in mathematical model to derive the theoretical rolling force correction coefficient.

[0043] Limiting module 24 is used to adjust the rolling force correction factor k according to the steel grade strength level. T Amplitude limiting is performed. The amplitude limiting module 24 performs boundary checks and truncation on the theoretical coefficients according to the preset yield strength rules for steel grades.

[0044] Correction execution module 25 is used to utilize the rolling force correction coefficient k after the amplitude limiting process. T Preset rolling force F for finishing mill i A corrected calculation is performed to obtain the corrected preset rolling force F. t and the corrected preset rolling force F t Issued and implemented.

[0045] In one embodiment, the specification determination module 21 is specifically used to: obtain the rolling grade, target control thickness, target control width, and target final rolling temperature of the current strip and the previous strip; determine whether the rolling grade, target control thickness, target control width, and target final rolling temperature are all in the same control layer; if the rolling grade, target control thickness, target control width, and target final rolling temperature are all in the same control layer, then the current strip and the previous strip are determined to be of the same steel grade and specification. The specification determination module 21 calls the system's preset specification layer table and checks the four core parameters one by one, giving the module extremely high recognition accuracy and reducing the risk of misjudgment of working conditions.

[0046] 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 correcting pre-calculated rolling force in finishing mills, characterized in that, include: Obtain the production parameters of the current strip and the previous strip, as well as the average detection temperature of the head of the intermediate billet in the last pass of roughing rolling; Based on the production parameters, determine whether the current strip steel and the previous strip steel are of the same steel type and specification; If the current strip steel is of the same steel grade and specification as the previous strip steel, then determine whether the temperature range of the intermediate billet exceeds the limit. If the temperature range of the intermediate billet exceeds the limit, the rolling force correction coefficient is calculated based on the average detected temperature of the head of the intermediate billet in the last roughing pass of the current strip. The rolling force correction coefficient is limited according to the strength level of the steel grade, and the pre-set rolling force of finishing rolling is corrected and calculated using the limited rolling force correction coefficient to obtain the corrected pre-set rolling force, and the corrected pre-set rolling force is issued for execution.

2. The method for correcting pre-calculated rolling force in finishing rolling according to claim 1, characterized in that, The production parameters include: obtaining the rolling grade, target control thickness, target control width, and target final rolling temperature of the current strip and the previous strip; determining whether the current strip and the previous strip are of the same steel grade and specification based on the production parameters includes: If the steel grade, the target controlled thickness, the target controlled width, and the target final rolling temperature are all in the same control layer, then the current strip steel is determined to be of the same steel grade and specification as the previous strip steel.

3. The method for correcting pre-calculated rolling force in finishing rolling according to claim 1, characterized in that, Determining whether the temperature range of the intermediate billet exceeds the limit includes: Calculate the temperature deviation between the current strip and the average detected temperature of the head of the intermediate billet in the last roughing pass of the previous strip; If the temperature deviation is greater than or equal to 50°C, or if the temperature deviation is less than or equal to -50°C, then the temperature range of the intermediate billet is determined to be out of limit.

4. The method for correcting pre-calculated rolling force in finishing rolling according to claim 1, characterized in that, Based on the average detected temperature of the intermediate slab head in the final roughing pass of the current strip, the rolling force correction factor is calculated using the following formula: In the formula, The rolling force correction factor is... For the corresponding steel grade correction factor, The average measured temperature of the head of the intermediate billet in the final roughing pass of the current strip.

5. The method for correcting pre-calculated rolling force in finishing rolling according to claim 1, characterized in that, The limitation processing of the rolling force correction coefficient according to the steel grade strength level includes: Obtain the yield strength of the steel grade to which the current strip belongs. If the yield strength Then the amplitude limit range is set to [0.95, 1.05]. If the yield strength If so, the amplitude limit range is set to [0.9, 1.1]. If the yield strength Then the amplitude limit range is set to [0.85, 1.15].

6. The method for correcting pre-calculated rolling force in finishing rolling according to claim 5, characterized in that, After setting the limiting range, the method further includes: determining whether the calculated rolling force correction coefficient exceeds the corresponding limiting range; and if the calculated rolling force correction coefficient exceeds the corresponding limiting range, forcing the rolling force correction coefficient to a corresponding boundary value.

7. The method for correcting pre-calculated rolling force in finishing rolling according to claim 1, characterized in that, The correction calculation of the pre-set rolling force for finishing mill using the rolling force correction coefficient after the amplitude limiting process is performed using the following formula: In the formula, The modified preset rolling force, For the preset rolling force, The rolling force correction factor is... This is the rack number.

8. A pre-calculated rolling force correction system for finishing mills, characterized in that, include: The parameter acquisition module is used to acquire the production parameters of the current strip and the previous strip, as well as the average detection temperature of the head of the intermediate billet in the last pass of roughing rolling. The specification determination module is used to determine whether the current strip steel and the previous strip steel are of the same steel type and specification. The temperature difference determination module is used to determine whether the temperature span of the intermediate billet exceeds the limit when the current strip steel and the previous strip steel are of the same steel grade and specification. The coefficient calculation module is used to calculate the rolling force correction coefficient based on the average detected temperature of the head of the intermediate billet in the last roughing pass of the current strip when the temperature span of the intermediate billet exceeds the limit. A limiting module is used to limit the rolling force correction coefficient according to the steel grade strength level; The correction execution module is used to perform correction calculations on the pre-set rolling force of finishing mill using the rolling force correction coefficient after the limiting process, to obtain the corrected pre-set rolling force, and then send the corrected pre-set rolling force for execution.

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