An on-line control method for hot continuous rolling laminar flow cooling coiling temperature

Abstract

The application discloses an online control method for hot continuous rolling laminar cooling coiling temperature, comprising the following steps: obtaining the thickness of a strip steel; using a preset physical model, calculating the maximum compensation coefficient of speed to temperature at double speed based on the thickness of the strip steel; obtaining the actual speed of the strip steel; based on the actual speed of the strip steel, performing interpolation calculation between the compensation coefficient at single speed and the maximum compensation coefficient to obtain the actual temperature compensation coefficient corresponding to the actual speed of the strip steel; and obtaining the open water amount according to the actual temperature compensation coefficient, and performing temperature compensation by using the open water amount to realize online control of the temperature of the strip steel. The online control method for the hot continuous rolling laminar cooling coiling temperature can obtain the laminar cooling physical control model of speed to temperature of the strip steel at different thicknesses during rolling according to the physical characteristics of the strip steel and the actual data on site, and more accurately and timely controls the hot continuous rolling laminar cooling coiling temperature by using speed, thereby improving the performance stability of the strip steel.

Description

Technical Field

[0001] This invention belongs to the technical field of hot continuous rolling control equipment, and in particular relates to an online control method for the laminar flow cooling coiling temperature of hot continuous rolling. Background Technology

[0002] When producing strip steel using a hot continuous rolling mill, the rolled strip needs to be continuously cooled by a laminar flow cooling system to reach the target coiling temperature. Different coiling temperatures result in different strip steel properties, and the overall temperature of the strip must be controlled within a certain range to ensure that the performance fluctuations along its entire length are kept within a reasonable limit. However, during the hot continuous rolling process, the rolling speed in the finishing mill is constantly changing. If the amount of hot water used for laminar flow cooling does not change accordingly with the speed, the strip temperature will fluctuate significantly, thus affecting the stability of the strip's overall performance.

[0003] In the existing system, the laminar flow cooling control model uses mathematical regression to compensate for the temperature of the speed. Specifically, it selects 10 strips of the same steel grade, specification and target coiling temperature that were recently rolled, and then performs regression analysis to obtain the maximum compensation curve of speed and temperature at twice the speed. Then, it uses interpolation to compensate online when the coiling temperature increases or decreases.

[0004] However, analysis of over 30,000 strip steel pieces controlled in production revealed that many compensation schemes were ineffective, and some even resulted in reverse compensation errors. This demonstrates that this regression analysis method cannot accurately and effectively control the online temperature of hot strip laminar flow cooling coiling. The reasons for the failure of temperature compensation when the speed changes are as follows: The existing scheme selects 10 previously rolled strip steel pieces of the same steel grade and specification as the original data for regression. This regression analysis requires consistent external conditions to be meaningful. However, the external conditions for previously rolled strip steel are subject to many uncertainties, such as changes in furnace temperature, the condition of the rolling mill roll cooling water, weather temperature, and cooling water temperature. Therefore, using previous data for regression analysis and compensation control under the current environment leads to deviations, and may even result in many contradictory compensations, significantly reducing the performance stability of strip steel production. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides an online control method for the laminar cooling coiling temperature in hot continuous rolling. Based on the physical properties of the strip and actual field data, a physical control model of laminar cooling temperature based on speed is obtained for the strip at different rolling thicknesses. By controlling the speed, the laminar cooling coiling temperature in hot continuous rolling can be more accurately and in real-time online, thereby improving the performance stability of the produced strip.

[0006] This invention provides an online control method for the laminar flow cooling coiling temperature of hot continuous rolling, comprising:

[0007] Obtain the strip thickness;

[0008] Using a preset physical model, the maximum compensation coefficient of speed for temperature at twice the speed is calculated based on the strip thickness.

[0009] Obtain the actual speed of the strip;

[0010] Based on the actual speed of the strip, interpolation is performed between the compensation coefficient at one speed and the maximum compensation coefficient to obtain the actual temperature compensation coefficient corresponding to the actual speed of the strip.

[0011] Based on the actual temperature compensation coefficient, the boiling water volume is obtained, and temperature compensation is performed using the boiling water volume to achieve online control of the strip temperature.

[0012] Preferably, in the above-described online control method for the laminar flow cooling coiling temperature of hot continuous rolling, the formula used in the preset physical model is:

[0013] MaxCofa = -0.06ln(h) - 0.1,

[0014] Where MaxCofa is the maximum compensation coefficient for temperature at double speed, and h is the thickness of the strip.

[0015] Preferably, in the above-described online control method for the laminar flow cooling coiling temperature of hot strip rolling, the step of interpolating between the compensation coefficient at one speed and the maximum compensation coefficient based on the actual speed of the strip to obtain the actual temperature compensation coefficient corresponding to the actual speed of the strip includes:

[0016] Plotting strip speed on the x-axis and compensation coefficient on the y-axis, we obtain a graph showing the variation of the compensation coefficient relative to strip speed.

[0017] The first point on the change graph is determined based on the one-time speed and its corresponding compensation coefficient;

[0018] The second point on the change graph is determined based on the double speed and the corresponding maximum compensation coefficient.

[0019] Connect the first point and the second point with a straight line;

[0020] Find the ordinate of the point on the straight line that corresponds to the actual speed, and thus determine the actual temperature compensation coefficient corresponding to the actual speed of the strip.

[0021] Preferably, in the above-described online control method for the laminar flow cooling coiling temperature of hot continuous rolling, the step of obtaining the boiling water volume based on the actual temperature compensation coefficient includes:

[0022] A hot water volume calculation curve is created by plotting the temperature compensation coefficient on the x-axis and the number of hot water manifolds on the y-axis.

[0023] The number of hot water manifolds is determined by finding the vertical coordinate of the point corresponding to the actual temperature compensation coefficient on the hot water volume calculation curve.

[0024] Preferably, in the above-described online control method for the laminar flow cooling coiling temperature of hot strip rolling, the step of using the hot water volume for temperature compensation to achieve online control of the strip temperature includes:

[0025] Based on the tracking position of the strip on the rolling line, before the strip reaches the manifold that needs to be opened, the number of manifolds to be opened are opened in sequence to perform temperature compensation and realize online control of the strip temperature.

[0026] Preferably, in the above-described online control method for the laminar flow cooling coiling temperature of hot continuous rolling, an actual temperature compensation coefficient corresponding to the actual speed of the strip is calculated at preset intervals.

[0027] Preferably, in the above-described online control method for the laminar flow cooling coiling temperature of hot strip rolling, the step of calculating the actual temperature compensation coefficient corresponding to the actual speed of the strip at preset time intervals includes:

[0028] The primary automated TDC system sends the actual strip speed to the secondary process computer every 150ms to 200ms. The secondary process computer calculates the actual temperature compensation coefficient corresponding to the actual strip speed every 150ms to 200ms to compensate for the temperature in real time.

[0029] Preferably, the above-described online control method for the laminar flow cooling coiling temperature of hot continuous rolling further includes:

[0030] The hot water volume is superimposed and corrected based on the influence coefficient of the final rolling temperature after the finishing mill and the influence coefficient of different rolling thicknesses. The hot water volume after superimposed correction is used for temperature compensation to achieve online control of strip temperature.

[0031] Preferably, in the above-described online control method for the laminar flow cooling coiling temperature of hot continuous rolling, the step of obtaining the strip thickness is:

[0032] The thickness of the strip is detected in real time using a thickness gauge installed behind the finishing mill.

[0033] Preferably, in the above-described online control method for the laminar flow cooling coiling temperature of hot continuous rolling, the compensation coefficient at one speed is the compensation coefficient obtained in a preset step.

[0034] As described above, the online control method for laminar cooling coiling temperature in hot continuous rolling provided by this invention includes: first, obtaining the strip thickness; then, using a preset physical model, calculating the maximum compensation coefficient of speed on temperature at double speed based on the strip thickness; next, obtaining the actual speed of the strip; and then, interpolating between the compensation coefficient at single speed and the maximum compensation coefficient based on the actual speed of the strip to obtain the actual temperature compensation coefficient corresponding to the actual speed of the strip. Finally, based on the actual temperature compensation coefficient, obtaining the boiling water volume, and using the boiling water volume for temperature compensation, thereby achieving online control of the strip temperature. Therefore, this scheme can obtain a physical control model of laminar cooling temperature on speed for strips at different thicknesses when rolling, based on the physical characteristics of the strip and actual field data. By controlling the speed more accurately and in real-time online, the performance stability of the produced strip is improved. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of an embodiment of an online control method for laminar flow cooling coiling temperature provided by the present invention;

[0037] Figure 2 A schematic diagram illustrating the calculation of the actual temperature compensation coefficient using interpolation.

[0038] Figure 3 This is a schematic diagram showing the relationship between Cofa and the amount of boiling water. Detailed Implementation

[0039] The core of this invention is to provide an online control method for the laminar cooling coiling temperature of hot strip rolling. Based on the physical properties of the strip and actual field data, a physical control model of laminar cooling temperature based on speed is obtained when the strip is rolled to different thicknesses. By controlling the speed, the laminar cooling coiling temperature of hot strip rolling can be controlled more accurately and in real time online, thereby improving the performance stability of the produced strip.

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] An implementation example of the online control method for the laminar flow cooling coiling temperature provided by this invention is as follows: Figure 1 As shown, Figure 1 This is a schematic diagram of an embodiment of an online control method for laminar flow cooling coiling temperature provided by the present invention. The method may include the following steps:

[0042] S1: Obtain the strip thickness;

[0043] Specifically, the thickness of the strip currently being manufactured can be obtained from the manufacturing system and used as the basis for subsequent calculations.

[0044] S2: Using a preset physical model, based on the strip thickness, calculate the maximum compensation coefficient of speed for temperature at double speed.

[0045] It should be noted that this preset physical model can be selected according to actual needs. Generally speaking, mathematical models include physical models and statistical models. Existing technologies use statistical models obtained by regression analysis, which are greatly affected by changes in external conditions and sometimes produce incorrect results. The preset physical model used in this embodiment is based on material properties, thus ensuring the correct control direction.

[0046] S3: Obtain the actual speed of the strip;

[0047] It should be noted that the actual speed of the strip can be obtained using either contact or non-contact methods. When using a contact method, the length measuring roller (encoder roller) installed on the upper and lower surfaces of the strip rotates synchronously with the strip to collect pulse signals. The linear speed is then calculated by combining the roller diameter and the reduction ratio. This method is simple in structure, low in cost, and suitable for low-speed or tension-stable applications. When using a non-contact method, the linear speed of the strip surface can be directly measured using laser Doppler or laser strip method. Its advantages are that it does not require contact, has no mechanical wear, is not affected by slippage, and has a fast response, making it suitable for high-speed (>10m / s) applications.

[0048] S4: Based on the actual speed of the strip, interpolation is performed between the compensation coefficient at one speed and the maximum compensation coefficient to obtain the actual temperature compensation coefficient corresponding to the actual speed of the strip.

[0049] It should be noted that interpolation between these two factors can ensure the correctness of the compensation direction, and determining the actual temperature compensation coefficient based on the actual speed of the strip can ensure more accurate compensation.

[0050] S5: Based on the actual temperature compensation coefficient, the boiling water volume is obtained, and temperature compensation is performed using the boiling water volume to achieve online control of the strip temperature.

[0051] It should be noted that the boiling water volume here refers to the amount of water supplied for laminar flow cooling. By finding the corresponding boiling water volume based on the actual temperature compensation coefficient, we can ensure more accurate temperature compensation.

[0052] As described above, the embodiments of the online control method for laminar cooling coiling temperature in hot continuous rolling provided by the present invention include: first, obtaining the strip thickness; then, using a preset physical model, calculating the maximum compensation coefficient of speed on temperature at double speed based on the strip thickness; then, obtaining the actual speed of the strip; and based on the actual speed of the strip, interpolating between the compensation coefficient at single speed and the maximum compensation coefficient to obtain the actual temperature compensation coefficient corresponding to the actual speed of the strip. Finally, based on the actual temperature compensation coefficient, obtaining the water volume, and using the water volume for temperature compensation, thus achieving online control of the strip temperature. Therefore, this scheme can obtain a physical control model of laminar cooling temperature on speed for strips at different rolling thicknesses based on the physical characteristics of the strip and actual field data. This allows for more precise and real-time online control of the laminar cooling coiling temperature in hot continuous rolling through speed control, thereby improving the performance stability of the produced strip.

[0053] In a specific embodiment of the above-described online control method for the laminar flow cooling coiling temperature of hot continuous rolling, the formula used in the preset physical model can be:

[0054] MaxCofa = -0.06ln(h) - 0.1,

[0055] Where MaxCofa is the maximum compensation coefficient for temperature at double speed, and h is the strip thickness.

[0056] This formula can be used to obtain the maximum compensation coefficient of speed for temperature at twice the speed, which is dimensionless. It can be used to control the curling temperature more effectively and avoid the problem of reverse control.

[0057] In another specific embodiment of the above-mentioned online control method for the laminar flow cooling coiling temperature of hot strip rolling, based on the actual speed of the strip, interpolation is performed between the compensation coefficient at one speed and the maximum compensation coefficient to obtain the actual temperature compensation coefficient corresponding to the actual speed of the strip. Specifically, this may include:

[0058] Plotting strip speed on the x-axis and compensation coefficient on the y-axis, we obtain a graph showing the variation of the compensation coefficient relative to strip speed.

[0059] The first point on the change graph is determined based on the one-time speed and its corresponding compensation coefficient;

[0060] The second point on the change graph is determined based on the double speed and its corresponding maximum compensation coefficient;

[0061] Connect the first point and the second point with a straight line;

[0062] Find the ordinate of the point on the straight line that corresponds to the actual speed, and thus determine the actual temperature compensation coefficient corresponding to the actual speed of the strip.

[0063] Here is a practical example for illustration, see reference. Figure 2 , Figure 2 To illustrate the calculation of the actual temperature compensation coefficient using interpolation, when the rolled strip thickness is 5mm, the formula MaxCofa = -0.06ln(h) - 0.1 is used to calculate MaxCofa = -0.2 for a thickness of 5mm. The baseline value of Cofa at the first speed (8m / s) is 1.2, while at the second speed (16m / s) it is Cofa = 1.2 - 0.2 = 1.0. These two sets of values ​​can be used to obtain... Figure 2 For this line, when the actual strip speed being rolled is 10 m / s, according to Figure 2 Linear interpolation calculation yields Cofa = 1.15.

[0064] In another specific embodiment of the above-described online control method for the laminar flow cooling coiling temperature of hot strip mills, obtaining the boiling water volume based on the actual temperature compensation coefficient can specifically include the following steps:

[0065] A hot water volume calculation curve is created by plotting the temperature compensation coefficient on the x-axis and the number of hot water manifolds on the y-axis.

[0066] Find the vertical coordinate of the point on the hot water volume calculation curve that corresponds to the actual temperature compensation coefficient, and thus determine the number of hot water manifolds.

[0067] Specifically, with Figure 3 For example, Figure 3 This diagram illustrates the relationship between Cofa and the volume of boiling water. The speed-temperature compensation coefficient Cofa corresponds to the volume of boiling water in an inverse relationship. The smaller the Cofa value, the larger the volume of boiling water. When Cofa is 1.15 as mentioned above, we can find the corresponding number of boiling water manifolds in this diagram as 35, which means that 35 manifolds need to be opened for water supply.

[0068] In a preferred embodiment of the above-described online control method for the laminar flow cooling coiling temperature of hot strip rolling, temperature compensation using water volume to achieve online control of strip temperature specifically includes:

[0069] Based on the tracking position of the strip on the rolling line, before the strip reaches the manifold that needs to be opened, the aforementioned number of water manifolds are opened in sequence to perform temperature compensation and realize online control of the strip temperature, thus enabling more precise and rapid control.

[0070] In another preferred embodiment of the online control method for the laminar flow cooling coiling temperature of hot strip rolling, an actual temperature compensation coefficient corresponding to the actual speed of the strip is calculated at preset time intervals. This allows for temperature compensation at shorter time intervals, ensuring better real-time adjustment. Further, calculating the actual temperature compensation coefficient corresponding to the actual speed of the strip at preset time intervals can specifically include: using a primary automated TDC system to send the actual strip speed to a secondary process computer every 150ms to 200ms. The secondary process computer calculates the actual temperature compensation coefficient corresponding to the actual speed of the strip every 150ms to 200ms, performing real-time temperature compensation. This automated TDC system is a multi-processor distributed control system. Therefore, this provides a specific implementation method to ensure faster adjustments and better stabilize the strip performance.

[0071] In another preferred embodiment of the above-described online control method for the laminar flow cooling coiling temperature of hot continuous rolling, the following steps may also be included:

[0072] Based on the influence coefficients of the final rolling temperature after the finishing mill and the influence coefficients of different rolling thicknesses, the hot water volume is superimposed and corrected. The corrected hot water volume is then used for temperature compensation, achieving online control of the strip temperature. For example, if the speed correction is Cofa1, the final rolling temperature correction is Cofa2, and the thickness correction is Cofa3, then the overall correction is Cofa = Cofa1 + Cofa2 + Cofa3, which further optimizes the temperature control results.

[0073] In addition, in the above embodiment of the online control method for the laminar flow cooling coiling temperature of hot continuous rolling, the strip thickness can be obtained by using a thickness gauge installed behind the finishing mill to detect the strip thickness in real time. This is easy to obtain and has a low cost. Of course, other methods can be selected according to actual needs, and there is no limitation here. Moreover, the compensation coefficient at one speed can be the compensation coefficient obtained in the preset steps. That is to say, the compensation coefficient at one speed can be determined in the preset stage, which is convenient and quick to obtain.

[0074] In summary, the online control method for laminar cooling coiling temperature in hot strip rolling provided in this application can obtain a physical control model of laminar cooling temperature based on the physical properties of the strip and actual field data when rolling different thicknesses of the strip. By controlling the speed, the online control of laminar cooling coiling temperature in hot strip rolling can be achieved more accurately and in real time, thereby improving the performance stability of the produced strip.

[0075] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An online control method for the laminar flow cooling coiling temperature of hot continuous rolling, characterized in that, include: Obtain the strip thickness; Using a preset physical model, the maximum compensation coefficient of speed for temperature at twice the speed is calculated based on the strip thickness. The temperature compensation coefficient at double speed is calculated by adding the temperature compensation coefficient at one speed to the maximum compensation coefficient. Obtain the actual speed of the strip; Based on the actual speed of the strip, an interpolation calculation is performed between the speed-temperature compensation coefficient at the first speed and the speed-temperature compensation coefficient at the second speed to obtain the actual temperature compensation coefficient corresponding to the actual speed of the strip. Based on the actual temperature compensation coefficient, the boiling water volume is obtained, and temperature compensation is performed using the boiling water volume to achieve online control of the strip temperature. The formula used in the preset physical model is: MaxCofa = -0.06ln(h) - 0.1, Where MaxCofa is the maximum compensation coefficient for temperature at double speed, and h is the thickness of the strip. The step of interpolating between the speed-temperature compensation coefficient at the first speed and the speed-temperature compensation coefficient at the second speed, based on the actual speed of the strip, to obtain the actual temperature compensation coefficient corresponding to the actual speed of the strip includes: Plotting strip speed on the x-axis and compensation coefficient on the y-axis, we obtain a graph showing the variation of the compensation coefficient relative to strip speed. The first point on the change graph is determined based on the one-time speed and the corresponding speed-temperature compensation coefficient. The second point on the change graph is determined based on the double speed and the corresponding speed-temperature compensation coefficient; Connect the first point and the second point with a straight line; Find the ordinate of the point on the straight line that corresponds to the actual speed, and thus determine the actual temperature compensation coefficient corresponding to the actual speed of the strip. The process of obtaining the boiling water volume based on the actual temperature compensation coefficient includes: A hot water volume calculation curve is created by plotting the temperature compensation coefficient on the x-axis and the number of hot water manifolds on the y-axis. Find the vertical coordinate of the point corresponding to the actual temperature compensation coefficient on the hot water volume calculation curve, and thus determine the number of hot water manifolds. The speed compensation coefficient for temperature at the first speed is the compensation coefficient obtained in a preset step.

2. The online control method for the laminar flow cooling coiling temperature of hot continuous rolling as described in claim 1, characterized in that, The method of using the aforementioned water volume for temperature compensation to achieve online control of strip steel temperature includes: Based on the tracking position of the strip on the rolling line, before the strip reaches the manifold that needs to be opened, the number of manifolds to be opened are opened in sequence to perform temperature compensation and realize online control of the strip temperature.

3. The online control method for the laminar flow cooling coiling temperature of hot continuous rolling as described in claim 1, characterized in that, The actual temperature compensation coefficient corresponding to the actual speed of the strip is calculated at preset intervals.

4. The online control method for the laminar flow cooling coiling temperature of hot continuous rolling as described in claim 3, characterized in that, The calculation of the actual temperature compensation coefficient corresponding to the actual speed of the strip at preset time intervals includes: The primary automated TDC system sends the actual strip speed to the secondary process computer every 150ms to 200ms. The secondary process computer calculates the actual temperature compensation coefficient corresponding to the actual strip speed every 150ms to 200ms to compensate for the temperature in real time.

5. The online control method for the laminar flow cooling coiling temperature of hot continuous rolling according to claim 1, characterized in that, Also includes: The hot water volume is superimposed and corrected based on the influence coefficient of the final rolling temperature after the finishing mill and the influence coefficient of different rolling thicknesses. The hot water volume after superimposed correction is used for temperature compensation to achieve online control of strip temperature.

6. The online control method for the laminar flow cooling coiling temperature of hot continuous rolling as described in claim 1, characterized in that, The method for obtaining the strip thickness is as follows: The thickness of the strip is detected in real time using a thickness gauge installed behind the finishing mill.

Images