A method for determining a biting signal of a hot continuous rolling finishing mill

Abstract

The application discloses a hot continuous rolling finishing mill steel biting signal judgment method and belongs to the technical field of automatic steel rolling control engineering. The method comprises the following steps: calculating the average value of the rolling force of the mill in the idle state as the idle rolling force, setting a rolling force threshold value according to the idle rolling force, judging whether the head of the strip steel travels into the set range from the mill or not, and if the head of the strip steel has traveled into the set range, and when the real-time rolling force of the mill continuously exceeds the rolling force threshold value for a certain time, the corresponding mill is judged to bite the steel. In addition, the accidental rolling force fluctuation is eliminated according to the duration that the real-time rolling force exceeds the rolling force threshold value. If the steel biting is not identified in the set range, and the head of the strip steel passes through the mill and exceeds the set range, the steel biting signal is automatically generated. The application provides a steel biting signal judgment method of the hot continuous rolling finishing mill according to the above steps, so that the judgment of the mill steel biting signal is more accurate and reliable.

Description

TECHNICAL FIELD

[0001] The application discloses a method for determining a steel biting signal of a hot continuous rolling finishing mill, and belongs to the technical field of automatic control engineering of steel rolling. BACKGROUND

[0002] In the hot continuous rolling production process, the successful establishment of the steel biting signal of the finishing mill plays a vital role in the integrity and stability of the whole rolling process. The steel biting signal of the finishing mill determines the logic and timing of functions such as loop, bending force and eccentricity compensation. Once an error occurs, it will affect the rolling process, causing equipment damage, steel plate rolling waste, steel stacking and even serious consequences such as safety hazards.

[0003] The traditional control method for determining the steel biting and throwing signals of the rolling mill does not have actual analysis, but directly sets the no-load rolling force of the rack to 0, compares the change rate of the rolling force in the adjacent several periods with the set threshold value, and considers that it is steel biting when the threshold value is greater than the threshold value, and considers that it is not steel biting when the threshold value is less than the threshold value.

[0004] However, for some special cases, such as when producing thick specifications, the rolling force will be seriously small, resulting in failure to reach the set threshold value, or when producing ultra-thin specifications, the rolling force is consistently large due to the pressing of the roll end, and also including accidental mechanical problems of the rolling mill, or local protrusions or depressions of the rolled piece, at this time, the traditional method cannot determine whether the rack is steel biting. When the above conditions occur, it will cause abnormal changes in the rolling force, thereby producing an incorrect steel biting signal to make the rolling mill move abnormally and produce scrap steel.

[0005] Therefore, it is necessary to adopt a method for producing a steel biting signal with higher accuracy. SUMMARY

[0006] In view of the problems of loss and inaccuracy of the steel biting signal in the traditional method, the application provides a method for determining a steel biting signal of a hot continuous rolling finishing mill, which adopts a new judgment method for the change of the rolling force, simultaneously increases the method for obtaining the rolling force of the rack when it is idle, signal false triggering protection and the time range for analyzing the change of the rolling force, and comprehensively judges the change of the rolling force signal.

[0007] The application is implemented by the following technical solutions:

[0008] A method for determining a steel biting signal of a hot continuous rolling finishing mill, the method comprising:

[0009] calculating the average value of the rolling force of the rolling mill when it is idle as the no-load rolling force, and setting a rolling force threshold value according to the no-load rolling force;

[0010] determining whether the strip head travels to a set range from the stand, if the strip head has traveled to the set range from the stand, and if the real-time rolling force of the stand continues to be greater than the rolling force threshold value for a certain time, determining that the corresponding stand bites the strip; wherein the duration that the real-time rolling force is greater than the rolling force threshold value is used to exclude accidental rolling force fluctuation; that is, the occurrence of the biting signal is determined by judging the maintaining condition after the rolling force value suddenly changes;

[0011] if the biting is not identified within the set range, and the strip head passes through the rolling mill beyond the set range, automatically generating the biting signal.

[0012] Further, the method comprises:

[0013] (1) selecting the average value of the rolling force of the finishing mill F(i) stand in an emptying period as the emptying rolling force P 0i of the F(i) stand;

[0014] setting a rolling force value L 0i for the F(i) stand, adding the rolling force value L 0i and the emptying rolling force P 0i , and using the sum of the rolling force value L 0i and the emptying rolling force P 0i as the rolling force threshold value L 1i for judging whether the F(i) stand bites the strip, L 1i =L 0i +P 0i ; wherein i is the stand number;

[0015] (2) when the F(i) stand is in an emptying state after rolling the previous strip, determining whether the head of the next strip travels to a set range from the F(i) stand; when the head of the next strip travels to the set range from the F(i) stand, entering step (3);

[0016] (3) continuously determining whether the real-time rolling force P i of the F(i) stand continues to be greater than the rolling force threshold value L 1i for a certain time;

[0017] if the real-time rolling force P i of the F(i) stand continues to be greater than the rolling force threshold value L 1i for a certain time, determining that the F(i) stand bites the strip, and generating the stand biting signal;

[0018] if the real-time rolling force P i of the F(i) stand does not continue to be greater than the rolling force threshold value L 1i for a certain time, entering step (4);

[0019] (4) Continue to determine whether the travel distance of the head of the next strip exceeds the set range. If it does, immediately generate a bite signal; if it does not, proceed to step (3).

[0020] Furthermore, in step (1):

[0021] When the strip head is about to reach the entrance of the finishing mill, strip travel signal tracking is initiated. When the strip head travels between stands F(i-2) and F(i-1), the average rolling force of stand F(i) under no-load conditions for a certain period of time is taken as the no-load rolling force P of stand F(i). 0i , where i>2;

[0022] When i = 1, 2, the method for calculating the corresponding no-load rolling force values ​​for stands F(1) and F(2) is as follows: Because stand F(1) has no upstream stand, the time T before the strip head reaches the entrance of the finishing mill is... entry Inside, racks F(1) and F(2) operate continuously for a certain period of time T under no-load conditions. count The average rolling force is taken as the no-load rolling force P of stand F(1) and stand F(2). 01 and P 02 , among which, T entry The continuous operating time T of racks F(1) and F(2) under no-load conditions is greater than that of racks F(1) and F(2). count .

[0023] Further, in step (1): the set rolling force value L 0i The range is 50-200 tons; the specific value can be adjusted according to the actual needs on site.

[0024] Furthermore, in step (2):

[0025] Based on the signal tracking of the next strip's movement, the time T between the head position of the next strip and the entrance of the finishing mill is calculated in real time. D When it meets (T) Di -t fr ) <T D <(T Di +t be When the head of the next strip reaches a set distance from the F(i) frame, the following condition is met:

[0026] Among them, t fr t be All are set values; T Di Let F(i) be the time it takes for the strip head to travel from the entrance of the finishing mill to stand F(i).

[0027] Furthermore, in step (3):

[0028] When the real-time rolling force P of the F(i) stand i The first time it exceeds the rolling force threshold L 1i At that time, the timer starts, and continues for the next set time period t. cx Internal real-time rolling force P i Continuously greater than the rolling force threshold L 1i Then, the F(i) frame bite is determined. Where t cx The minimum value is 15ms, but it can be set to 20ms depending on the actual situation.

[0029] Furthermore, in step (4):

[0030] For rack F(i), when T D >(T Di +t be If the head of the next strip has traveled beyond the F(i) frame and exceeded the set range, a bite signal is immediately generated.

[0031] Furthermore, the method also includes:

[0032] If the strip does not generate a bite signal in stand F(i), and the strip travels to stand F(x) downstream of stand F(i), then stand F(x) generates a bite signal. In this case, stand F(i) and all stands between stand F(i) and stand F(x) are given a bite signal, ensuring the normal operation of the rolling mill. This also avoids the situation where the bite signal judgment of a stand fails due to accidental factors.

[0033] Beneficial technical effects of the present invention:

[0034] The present invention provides a method for determining bite signals in a hot strip mill, which overcomes abnormal situations such as abnormal fluctuations in rolling force and false triggering of bite signals when rolling thin strip steel at the negative roll gap of the stand, thereby improving the overall stability of the rolling process.

[0035] This invention provides a method that changes the traditional method of generating bite signals based on the rate of change of rolling force. Instead, it calculates the average rolling force of the mill under no-load conditions during actual production as the no-load rolling force. A threshold is set to determine when bite occurs when the rolling force exceeds this threshold. A time interval is set at the mill stand, specifying that a bite signal can only be generated within this interval. Furthermore, the duration of the rolling force exceeding the threshold is used to further eliminate random rolling force fluctuations, i.e., the maintenance of the rolling force value after a sudden change is judged to ultimately determine the generation of a bite signal. If no bite is detected within the interval, a bite signal is automatically generated when the strip head exceeds the set time range. The method provided by this invention makes the determination of bite signals at the mill stand more accurate and reliable. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart of the hot strip mill bite signal determination method in an embodiment of the present invention;

[0038] Figure 2 This is a flowchart of the frame steel biting signal judgment failure handling method in an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the time range and the structure of the finishing mill set up in the embodiments of the present invention;

[0040] Figure 4 This is a simulation diagram of the F5 no-load rolling force value selected for a certain period of time in an embodiment of the present invention;

[0041] Figure 5 This is a simulation diagram of the average value of the F5 no-load rolling force after a selected period of time in an embodiment of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0043] Conversely, this invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the invention as defined in the claims. Furthermore, to provide a better understanding of the invention, certain specific details are described in detail below. However, those skilled in the art will fully understand the invention even without these detailed descriptions.

[0044] This invention provides a method for determining bite signals in a hot strip mill finishing mill, the method comprising:

[0045] The average rolling force of the mill under no-load conditions is calculated as the no-load rolling force, and the rolling force threshold is set based on the no-load rolling force.

[0046] It is determined whether the strip head has traveled within a set distance from the stand. If it has traveled within the set distance, and the real-time rolling force of the stand has been greater than the rolling force threshold for a certain period of time, then it is determined that the corresponding stand is biting the strip. Random rolling force fluctuations are excluded based on the duration of the real-time rolling force being greater than the rolling force threshold. That is, the generation of the biting signal is determined by judging the maintenance of the rolling force value after a sudden change.

[0047] If no bite is detected within the set range, and the strip head passes through the mill beyond the set range, a bite signal is automatically generated.

[0048] In this embodiment, Figure 1 This is an overall flowchart of the method described in this embodiment of the invention. The method employs a novel method for setting the no-load rolling force of the rolling mill, and simultaneously adds methods for preventing the biting signal from triggering protection and establishing a time-domain range for analyzing rolling force changes, comprehensively judging changes in the rolling force signal. Therefore, under the control technology of this scheme, the phenomenon of scrap steel caused by abnormal biting signals when rolling thin, uneven strips can be eliminated. The method specifically includes:

[0049] (1) Select the average rolling force of the finishing mill stand F(i) during a period of no-load operation as the no-load rolling force P of stand F(i). 0i ;

[0050] A rolling force value L is set for stand F(i). 0i The rolling force value L 0i With the no-load rolling force P 0i Added together, the rolling force value L 0i With the no-load rolling force P 0i The sum of these values ​​serves as the rolling force threshold L for determining whether the F(i) stand is biting the steel. 1i L 1i =L 0i +P 0i Where i is the rack number;

[0051] (2) When the F(i) stand has finished rolling the previous strip and is in an unloaded state, it is determined whether the head of the next strip has traveled to a set range from the F(i) stand; when the head of the next strip has traveled to a set range from the F(i) stand, proceed to step (3).

[0052] (3) Continue to determine the real-time rolling force P of the F(i) stand. i Whether the rolling force exceeds the threshold L for a sustained period of time 1i ;

[0053] If the real-time rolling force P of the F(i) stand i For a period of time, the rolling force is greater than the rolling force threshold L.1i Determine if the F(i) frame is biting, and generate a frame biting signal;

[0054] If the real-time rolling force P of the F(i) stand i No rolling force exceeding the threshold L for an extended period of time 1i Proceed to step (4);

[0055] (4) Continue to determine whether the travel distance of the head of the next strip exceeds the set range. If it does, immediately generate a bite signal; if it does not, proceed to step (3).

[0056] Specifically, in step (1):

[0057] When the strip head is about to reach the entrance of the finishing mill, strip travel signal tracking is initiated. When the strip head travels between stands F(i-2) and F(i-1), the average rolling force of stand F(i) under no-load conditions for a certain period of time (the time range can be set to 250ms-350ms, specifically 300ms) is taken as the no-load rolling force P of stand F(i). 0i , where i>2;

[0058] When i = 1, 2, the method for calculating the corresponding no-load rolling force values ​​for stands F(1) and F(2) is as follows: Because stand F(1) has no upstream stand, the time T before the strip head reaches the entrance of the finishing mill is... entry Inside, racks F(1) and F(2) operate continuously for a certain period of time T under no-load conditions. count The average rolling force (the time range can be set to 250ms-350ms, specifically 300ms) is used as the no-load rolling force P of stand F(1) and stand F(2). 01 and P 02 , among which, T entry The continuous operating time T of racks F(1) and F(2) under no-load conditions is greater than that of racks F(1) and F(2). count .

[0059] In this embodiment, in step (1): the set rolling force value L 0i The range is 50-200 tons. The specific value can be adjusted according to the actual needs on site.

[0060] In step (2) of this embodiment:

[0061] Based on the signal tracking of the next strip's movement, the time T taken for the head of the next strip to travel from the finishing mill entrance to the current position is calculated in real time. D When it meets (T) Di -t fr ) <T D<(T Di +t be When the head of the next strip reaches a set distance from the F(i) frame, the following condition is met:

[0062] Among them, t fr t be All are set values ​​(specifically, t) fr =80ms,t be =50ms); T Di Let F(i) be the time it takes for the strip head to travel from the entrance of the finishing mill to stand F(i). Figure 3 This is a schematic diagram of the time range and the structure of the finishing mill set up in the embodiments of the present invention.

[0063] In step (3) of this embodiment:

[0064] When the real-time rolling force P of the F(i) stand i The first time it exceeds the rolling force threshold L 1i At that time, the timer starts, and continues for the next set time period t. cx Internal real-time rolling force P i Continuously greater than the rolling force threshold L 1i Then, the F(i) frame bite is determined. Where t cx The minimum value is 15ms, but it can be set to 20ms depending on the actual situation.

[0065] In step (4) of this embodiment:

[0066] For rack F(i), when T D >(T Di +t be When ), (specifically, t) be =50ms), then it is determined that the head travel distance of the next strip has passed through the F(i) frame and exceeded the set range, and a bite signal is generated immediately. Step (4) is an emergency measure when a bite signal is not generated normally.

[0067] The method further includes:

[0068] To prevent the bite signal from failing due to accidental factors, if the F(i) stand does not generate a bite signal, and the strip travels to the downstream F(x) stand, then the F(x) stand generates a bite signal; then a bite signal is given to all stands from F(i) (including the F(i) stand) to F(x) stand (excluding the F(x) stand) (i.e., a bite signal is given to the F(i) stand and all stands between the F(i) stand and the F(x) stand), ensuring the normal operation of the rolling mill.

[0069] Taking the F5 stand of the finishing mill as an example, the rolling force value collected when F5 is unloaded in actual production is as follows:Figure 4 As shown; the average value is calculated based on the rolling force value collected during F5 no-load operation, and the average rolling force obtained from the simulation is as follows. Figure 5 As shown.

[0070] Finally, it should be noted that the above description represents a preferred embodiment of the present invention. It should be pointed out that although preferred embodiments have been described, those skilled in the art, once they understand the basic inventive concept of the present invention, can make various improvements and modifications without departing from the principles described herein. These improvements and modifications should also be considered within the scope of protection of the present invention. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

Claims

1. A method for determining bite signals in a hot continuous rolling mill, characterized in that, The method includes: The average rolling force of the mill under no-load conditions is calculated as the no-load rolling force, and the rolling force threshold is set based on the no-load rolling force. It is determined whether the strip head has traveled to a set distance from the stand. If it has traveled to the set range, and the real-time rolling force of the stand has been greater than the rolling force threshold for a certain period of time, it is determined that the corresponding stand is biting the strip. Among them, the duration of the real-time rolling force being greater than the rolling force threshold is used to eliminate random rolling force fluctuations. If no bite is detected within the set range, and the strip head passes through the mill beyond the set range, a bite signal is automatically generated.

2. The method for determining bite signals in a hot continuous rolling mill according to claim 1, characterized in that, The method includes: (1) Select the average rolling force of the finishing mill stand F(i) during a period of no-load operation as the no-load rolling force P of stand F(i). 0i ; A rolling force value L is set for stand F(i). 0i The rolling force value L 0i With the no-load rolling force P 0i Added together, the rolling force value L 0i With the no-load rolling force P 0i The sum of these values ​​serves as the rolling force threshold L for determining whether the F(i) stand is biting the steel. 1i L 1i =L 0i +P 0i Where i is the rack number; (2) When the F(i) stand has finished rolling the previous strip and is in an unloaded state, it is determined whether the head of the next strip has traveled to a set range from the F(i) stand; when the head of the next strip has traveled to a set range from the F(i) stand, proceed to step (3). (3) Continue to determine the real-time rolling force P of the F(i) stand. i Whether the rolling force exceeds the threshold L for a sustained period of time 1i ; If the real-time rolling force P of the F(i) stand i For a period of time, the rolling force is greater than the rolling force threshold L. 1i Determine if the F(i) frame is biting, and generate a frame biting signal; If the real-time rolling force P of the F(i) stand i No rolling force exceeding the threshold L for an extended period of time 1i Proceed to step (4); (4) Continue to determine whether the travel distance of the head of the next strip exceeds the set range. If it does, immediately generate a bite signal; if it does not, proceed to step (3).

3. The method for determining bite signals in a hot continuous rolling mill according to claim 2, characterized in that, In step (1): When the strip head is about to reach the entrance of the finishing mill, strip travel signal tracking is initiated. When the strip head travels between stands F(i-2) and F(i-1), the average rolling force of stand F(i) under no-load conditions for a certain period of time is taken as the no-load rolling force P of stand F(i). 0i , where i>2; When i = 1, 2, the method for calculating the corresponding no-load rolling force values ​​for stands F(1) and F(2) is as follows: during the time T before the strip head reaches the entrance of the finishing mill. entry Inside, racks F(1) and F(2) operate continuously for a certain period of time T under no-load conditions. count The average rolling force is taken as the no-load rolling force P of stand F(1) and stand F(2). 01 and P 02 , among which, T entry The continuous operating time T of racks F(1) and F(2) under no-load conditions is greater than that of racks F(1) and F(2). count .

4. The method for determining bite signals in a hot continuous rolling mill according to claim 2, characterized in that, In step (1): the set rolling force value L 0i The range is 50-200 tons.

5. The method for determining bite signals in a hot continuous rolling mill according to claim 2, characterized in that, In step (2): Based on the signal tracking of the next strip's movement, the time T taken for the head of the next strip to travel from the finishing mill entrance to the current position is calculated in real time. D When it meets (T) Di -t fr ) <T D <(T Di +t be When the head of the next strip reaches a set distance from the F(i) frame, the following condition is met: Among them, t fr t be All are set values; T Di Let F(i) be the time it takes for the strip head to travel from the entrance of the finishing mill to stand F(i).

6. The method for determining bite signals in a hot continuous rolling mill according to claim 2, characterized in that, In step (3): When the real-time rolling force P of the F(i) stand i The first time it exceeds the rolling force threshold L 1i At that time, the timer starts, and continues for the next set time period t. cx Internal real-time rolling force P i Continuously greater than the rolling force threshold L 1i Then, F(i) is determined to be a steel-griped frame.

7. The method for determining bite signals in a hot continuous rolling mill according to claim 5, characterized in that, In step (4): For rack F(i), when T D >(T Di +t be If the head of the next strip has traveled beyond the F(i) frame and exceeded the set range, a bite signal is immediately generated.

8. The method for determining bite signals in a hot continuous rolling mill according to claim 5, characterized in that, The method further includes: If the strip does not generate a bite signal in stand F(i), and the strip travels to stand F(x) downstream of stand F(i), then stand F(x) generates a bite signal; then stand F(i) and all stands between stand F(i) and stand F(x) are given a bite signal to ensure the normal operation of the rolling mill.

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