Control method for a cold rolling mill

Abstract

The application relates to the field of steel rolling technology and discloses a control method of a cold rolling mill. The method comprises the following steps: collecting rolling force and bending force of each rack in the cold rolling mill at a first set rolling speed, and a position difference of a pressing cylinder between a working side and a driving side of each rack as rolling force setting, bending force setting and leveling setting of the corresponding rack when the cold rolling mill starts; obtaining actual tension between adjacent racks in the cold rolling mill; if the actual tension between the adjacent racks is equal to zero, building tension for the racks between the out-of-tension rack and the last rack; if the actual tension between the adjacent racks is greater than zero, or after building tension for the racks between the out-of-tension rack and the last rack, adjusting the rolling force, the bending force and the position difference of the pressing cylinder of each rack to the given data; and controlling the cold rolling mill to start according to a starting threading speed. The technical scheme can improve the production stability and manufacturing capacity of the cold continuous rolling mill.

Description

Technical Field

[0001] This application relates to the field of steel rolling technology and discloses a control method for a cold rolling mill. Background Technology

[0002] In the production of cold rolling mills, the cold rolling mills often need to be shut down due to problems such as the expiration of the rolls, defects such as roll printing color difference, and equipment failure handling.

[0003] During the restart process of a cold rolling mill after shutdown, the production line may be in a non-steady-state rolling condition where key rolling parameters such as thickness, tension, and rolling force change drastically. This non-steady-state rolling can lead to various production problems, among which strip breakage is highly probable, such as strip breakage due to poor shape deviation or breakage within the stand. Strip breakage during the restart process significantly reduces the yield of the cold rolling mill and disrupts its production rhythm. However, existing technologies cannot solve the problem of strip breakage during mill restart. Summary of the Invention

[0004] This application relates to the field of steel rolling technology and discloses a control method for cold rolling mills. It can solve the problem of strip breakage during restarting of a cold continuous rolling mill after shutdown.

[0005] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0006] According to one aspect of the embodiments of this application, a control method for a cold rolling mill is provided. The method includes: collecting the rolling force and bending roll force of each stand in the cold rolling mill, as well as the position difference of the pressing cylinder between the working side and the drive side of each stand, when the operating speed of the cold rolling mill is a first set rolling speed, as the target rolling force, target bending roll force, and target pressing cylinder position difference of the corresponding stand when the cold rolling mill is started; obtaining the actual tension between adjacent stands in the cold rolling mill; if the actual tension between adjacent stands is equal to zero, then for the first of the adjacent stands... Tensioning is performed on the stands between the first stand and the last stand, where the last stand is the last stand in the cold rolling mill. If the actual tension between adjacent stands is greater than zero, or after tensioning is performed on the stands between the first stand and the last stand in the adjacent stands, the rolling force of each stand is adjusted to its corresponding target rolling force, the rolling force of each stand is adjusted to its corresponding target bending roll force, and the position difference of the pressing cylinder of each stand is adjusted to its corresponding target pressing cylinder position difference. The cold rolling mill is started according to a predetermined starting and threading speed.

[0007] In one embodiment of this application, based on the foregoing scheme, the tensioning process for the frames between the preceding frame and the last frame in the adjacent frames includes: controlling the roll gap of the frames between the preceding frame and the last frame in the adjacent frames to reduce the rolling force of the frames between the preceding frame and the last frame in the adjacent frames to zero; and for any pair of adjacent frames between the preceding frame and the last frame in the adjacent frames, controlling the tension between the adjacent frames to be increased to 1.5 to 2.5 times a predetermined set tension.

[0008] In one embodiment of this application, based on the foregoing scheme, the method further includes: obtaining the actual rolling speed of the cold rolling mill; determining the tension coefficient between each stand according to the actual rolling speed, the tension coefficient being used to determine the target tension between each stand, the tension coefficient being controlled between 1.0 and 1.5; determining the target tension between each stand according to the predetermined set tension between each stand and the tension coefficient; and controlling the actual tension between each stand to increase to the corresponding target tension.

[0009] In one embodiment of this application, based on the foregoing scheme, the method further includes: obtaining the shutdown threading speed of the cold rolling mill when it stops; if the first speed difference between the actual rolling speed and the start-up threading speed is less than a set speed difference threshold, then the tension coefficient is controlled between 1.0 and 1.1; if the second speed difference between the actual rolling speed and the shutdown threading speed is less than the set speed difference threshold, then the tension coefficient is controlled between 1.3 and 1.5.

[0010] In one embodiment of this application, based on the aforementioned scheme, controlling the actual tension between each frame to increase to the corresponding target tension includes: determining the tension change value between each frame based on the actual tension between each frame and the corresponding target tension; determining the roll gap change value of each frame based on the tension change value between each frame and a tension influence coefficient, wherein the tension influence coefficient is used to characterize the correlation between the roll gap change value of the frame and the tension change value between the frames; and adjusting the roll gap of each frame based on the roll gap change value of each frame to increase the actual tension between each frame to the corresponding target tension.

[0011] In one embodiment of this application, based on the aforementioned scheme, determining the roll gap change value of each frame according to the tension change value and tension influence coefficient between each frame includes: determining a tension adjustment coefficient based on the starting and threading speed, wherein the tension adjustment coefficient is used to determine the roll gap change value; calculating the product of the tension change value between each frame and the tension adjustment coefficient, and calculating the ratio of the product to the tension influence coefficient as the roll gap change value of each frame.

[0012] In one embodiment of this application, based on the aforementioned scheme, determining the tension adjustment coefficient according to the starting and threading speed includes: if the starting and threading speed is greater than or equal to a set speed, then the tension adjustment coefficient is controlled between 0.7 and 1.0; if the starting and threading speed is less than the set speed, then the tension adjustment coefficient is controlled between 1.0 and 1.2.

[0013] In one embodiment of this application, based on the aforementioned scheme, the starting speed for threading the conveyor belt is controlled at 20–70 mpm.

[0014] In one embodiment of this application, based on the aforementioned scheme, after the cold rolling mill is shut down, the method further includes: controlling the rolling force of each stand to be reduced to 10% to 20% of its corresponding ultimate rolling force, wherein the ultimate rolling force is the maximum rolling force of the stand.

[0015] In one embodiment of this application, based on the aforementioned scheme, after controlling the cold rolling mill to start according to a predetermined starting and threading speed, the method further includes: obtaining the actual thickness of the strip at each stand exit and the target thickness of the strip at each stand exit; if the thickness deviation value at each stand exit is less than a set thickness deviation threshold, then increasing the operating speed of the cold rolling mill to the first set rolling speed; if the actual thickness of the strip at the last stand exit reaches the target thickness of the strip at the last stand exit, then increasing the operating speed of the cold rolling mill to the second set rolling speed.

[0016] In the technical solution proposed in this application, the rolling force and bending force of each stand in the cold rolling mill, as well as the position difference of the pressing cylinder between the working side and the drive side of each stand, are collected as the rolling force, bending force, and leveling force settings for the corresponding stands when the cold rolling mill is started. Before the cold rolling mill is stopped and restarted, the actual tension between adjacent stands in the cold rolling mill is obtained. If the actual tension between adjacent stands is zero, tensioning is performed on the stands from the untensioned stand to the last stand. If the actual tension between adjacent stands is greater than zero, or after tensioning is performed on the stands from the untensioned stand to the last stand, the rolling force, bending force, and position difference of the pressing cylinder of each stand are adjusted to the data collected before the shutdown. The cold rolling mill is started according to the starting threading speed. The technical solution proposed in this application can avoid drastic changes in key rolling parameters such as rolling force, bending force, and tension before and during the restart of the cold rolling mill, thereby reducing the problem of strip breakage during the restart of the cold rolling mill to a certain extent. It can also improve the yield of the cold rolling mill and enhance the production stability and manufacturing capacity of the cold rolling mill.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0019] Figure 1 A schematic diagram of the cold rolling mill unit in an embodiment of this application is shown;

[0020] Figure 2 A flowchart of the control method for the cold rolling mill in an embodiment of this application is shown;

[0021] Figure 3 The diagram shows the rolling speed variation of the cold rolling mill in the embodiments of this application;

[0022] The annotations in the attached figures are explained as follows:

[0023] 100—Cold rolling mill unit, 101—Rack,

[0024] 102—Upper work roll, 103—Lower work roll

[0025] 104—Tension meter roller. Detailed Implementation

[0026] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0027] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0028] It should be noted that "multiple" in this article refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0029] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such uses of these terms can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described.

[0030] Figure 1 A schematic diagram of a cold rolling mill unit in an embodiment of this application is shown.

[0031] like Figure 1 As shown, the cold rolling mill 100 includes multiple stands 101. Each stand 101 includes at least an upper work roll 102, a lower work roll 103, an upper support roll (not shown in the figure), and a lower support roll (not shown in the figure). At least one tension gauge roll 104 is provided between adjacent stands 101.

[0032] The cold rolling mill 100 may include 2 to 8 stands 101. The first stand of the cold rolling mill 100 may be called the initial stand, and the last stand of the cold rolling mill 100 may be called the final stand. A coiler (not shown in the figure) may also be installed near the final stand. The coiler can be used to coil the finished strip at the exit of the final stand. The tension meter roller 104 can be used to monitor the actual tension between adjacent stands.

[0033] The cold rolling mill 100 may also include a PLC control system (not shown in the figure). The PLC control system can monitor the rolling speed of the cold rolling mill 100, as well as the rolling force and bending force of each stand. It can also control the shutdown and startup of the cold rolling mill 100. The startup of the cold rolling mill 100 can be considered as the cold rolling mill 100 starting up or starting operation, or starting the machine.

[0034] The implementation details of the technical solutions in the embodiments of this application are described in detail below:

[0035] Figure 2 A flowchart of the control method for the cold rolling mill in an embodiment of this application is shown.

[0036] like Figure 2 As shown, the control method for the cold rolling mill includes at least steps 210 to 290.

[0037] The following will be about Figure 2 Steps 210 to 290 are described in detail below:

[0038] In step 210, the rolling force and bending force of each stand in the cold rolling mill, as well as the position difference of the pressing cylinder between the working side and the transmission side of each stand, are collected when the cold rolling mill is running at the first set rolling speed. These are used as the target rolling force, target bending force, and target pressing cylinder position difference of the corresponding stand when the cold rolling mill is started.

[0039] In this application, the rolling force and bending force of each stand in the cold rolling mill, as well as the position difference of the pressing cylinder between the working side and the drive side of each stand, are collected and recorded when the cold rolling mill is running at the first set rolling speed. These are used as the given rolling force and bending force of each stand, as well as the given position difference of the pressing cylinder between the working side and the drive side of each stand, when the cold rolling mill is stopped and restarted.

[0040] The first set rolling speed can be the lowest rolling speed set by the automatic control of the flow rate and thickness per second. The lowest rolling speed set by the automatic control of the flow rate and thickness per second is the lowest speed under the premise of ensuring the dimensional accuracy of the strip. Therefore, when the running speed of the cold rolling mill is the first set rolling speed, the rolling force and bending roll force of each stand in the cold rolling mill, as well as the position difference of the pressing cylinder between the working side and the transmission side of each stand, are used as the given rolling parameters of each stand when the cold rolling mill starts up. This is more in line with the actual environment of the cold rolling mill starting up.

[0041] Automatic thickness control based on mill flow rate is a method that uses the principle that the volume of metal remains unchanged before and after rolling to calculate and control the thickness of the strip exit. The basic principle of automatic thickness control is to continuously measure the actual rolled thickness of the strip using a thickness gauge or other sensors, and adjust the reduction amount, tension or reduction speed by comparing the measured value with the given value based on the deviation signal obtained, using various measuring devices to control the thickness of the strip exit within the allowable deviation range.

[0042] The position difference of the pressing cylinder between the working side and the transmission side can be considered as the deviation value of the piston displacement of the pressing cylinder between the hydraulic cylinder on the working side and the hydraulic cylinder on the transmission side. The position difference of the pressing cylinder can be used to guide the workers to determine the height difference between the working side and the transmission side of each frame.

[0043] If there is strip steel in the stands of the cold rolling mill after the cold rolling mill is shut down, the rolling force of each stand of the cold rolling mill needs to be adjusted. If the strip steel in the stands is squeezed according to the rolling force of each stand when the cold rolling mill is running normally, the strip steel in the stands may be subjected to excessive force and break.

[0044] That is, after the cold rolling mill is shut down, the method further includes: controlling the rolling force of each stand to reduce to 10% to 20% of its corresponding ultimate rolling force, wherein the ultimate rolling force is the maximum rolling force of the stand.

[0045] After the cold rolling mill is shut down, the rolling force of each stand is reduced to 10% to 20% of its corresponding limit rolling force, preferably 12% to 16%.

[0046] After a cold rolling mill is shut down, if there is strip steel remaining in the stands, the strip steel located below the work rolls will be compressed and deformed. This deformed strip steel is called the deformed strip steel. If the deformed strip steel is subjected to excessive rolling force for a prolonged period, it is prone to breakage. Conversely, if the rolling force on the deformed strip steel is too low, it is prone to tension loss between stands. Therefore, tension needs to be established between the stands before restarting the mill. Thus, after a cold rolling mill is shut down, the rolling force on each stand needs to be reduced.

[0047] Continue to refer to Figure 1 In step 230, the actual tension between adjacent stands in the cold rolling mill is obtained.

[0048] In this application, before starting the machine, the actual tension between adjacent stands in the cold rolling mill can be obtained by the tension meter roll in the continuous rolling mill. Based on the actual tension between adjacent stands, it can be determined whether the strip in each stand is in a tensioned state, thereby determining whether it is necessary to perform tensioning treatment on each stand in the cold rolling mill.

[0049] Continue to refer to Figure 1 In step 250, if the actual tension between the adjacent frames is zero, then tensioning is performed on the frames between the previous frame and the last frame in the adjacent frames, where the last frame is the last frame in the cold rolling mill.

[0050] In this application, if the actual tension between at least one pair of adjacent stands in the cold rolling mill is zero, then at least one pair of adjacent stands with zero actual tension can be considered as tension-depleted stands. The tension-depleted stands can be numbered according to their distance from the coiler. The tension-depleted stand farthest from the coiler can be called the initial tension-depleted stand, and the tension-depleted stand closest to the coiler can be called the final tension-depleted stand. Tension can be established between the stands (including the initial tension-depleted stand and the final tension-depleted stand) from the initial tension-depleted stand to the coiler, or tension can be established between the stands (including the initial tension-depleted stand and the final tension-depleted stand) from the finishing mill to the final tension-depleted stand. The initial tension-depleted stand is the first stand in the cold rolling mill.

[0051] In one embodiment, the tensioning process for the stands between the preceding stand and the last stand in the adjacent stands includes: controlling the roll gap of the stands between the preceding stand and the last stand in the adjacent stands to open, so that the rolling force of the stands between the preceding stand and the last stand in the adjacent stands is reduced to zero; and for any pair of adjacent stands between the preceding stand and the last stand in the adjacent stands, controlling the tension between the adjacent stands to be increased to 1.5 to 2.5 times a predetermined set tension.

[0052] In this application, the roll gaps of all stands from the initial de-tensioning stand to the final stand in the de-tensioning stand are opened to reduce the rolling force of all stands from the initial de-tensioning stand to zero, and the tension of any pair of adjacent stands from the initial de-tensioning stand to the final stand is increased to 1.5 to 2.5 times the predetermined set tension.

[0053] After tensioning is applied to the stands between the first and last stands in an adjacent mill, the roll gaps between the first and last stands in an adjacent mill are closed to ensure that the rolling force between the first and last stands in an adjacent mill is greater than zero. The roll gap size of each stand in the cold rolling mill can be adjusted based on the rolling force of each stand collected before the cold rolling mill is shut down.

[0054] Continue to refer to Figure 1 In step 270, if the actual tension between the adjacent stands is greater than zero, or after tensioning is performed on the stands between the previous stand and the last stand in the adjacent stands, the rolling force of each stand is adjusted to its corresponding target rolling force, the rolling force of each stand is adjusted to its corresponding target bending roll force, and the position difference of the pressing cylinder of each stand is adjusted to its corresponding target pressing cylinder position difference.

[0055] In this application, after tensioning is performed on the stands between the preceding and last stands in an adjacent mill, the tension between adjacent stands in the cold rolling mill is greater than zero, and the tension between each adjacent stand can be controlled from 0.5 tons to 20% of the set tension.

[0056] Before restarting, if the actual tension between adjacent stands is greater than zero, the rolling force of each stand is adjusted to the target rolling force collected and recorded before shutdown, and the bending roll force of each stand is adjusted to the target bending roll force collected and recorded before shutdown. At the same time, the position difference of the pressing cylinder between the working side and the drive side of each stand is adjusted to the target position difference of the pressing cylinder collected and recorded before shutdown. This ensures that the rolling parameters of each stand are the same as those of each stand before shutdown, preventing drastic fluctuations in the rolling parameters of each stand before shutdown and after restarting, which could cause strip breakage.

[0057] Continue to refer to Figure 1 In step 290, the cold rolling mill is started according to a predetermined starting and threading speed.

[0058] In this application, after adjusting the rolling parameters of each stand to be the same as those of each stand before shutdown, the cold rolling mill can be started according to the predetermined starting and threading speed. After the cold rolling mill is started, the rolling speed of the cold rolling mill can be determined based on the strip thickness at the exit of each stand.

[0059] In one embodiment, the starting and threading speed is controlled at 20-70 mpm.

[0060] In this application, the starting speed of the cold rolling mill is controlled between 20 and 70 mpm, preferably between 45 and 55 mpm. If the starting speed is faster, the starting deformation rate of the cold rolling mill will be faster and the roll gap adjustment time of each stand will be shorter, which may lead to less stable rolling. If the starting speed is slower, the roll gap lubrication of each stand will be worse and the rolling force of each stand will be greater, which may increase the difficulty of starting the cold rolling mill.

[0061] During the shutdown or startup of the cold rolling mill, the set tension between each stand can be adjusted adaptively to keep the tension between each stand stable and avoid various problems caused by unstable tension during the shutdown or startup of the cold rolling mill.

[0062] In one embodiment, the method further includes: obtaining the actual rolling speed of the cold rolling mill; determining the tension coefficient between each stand based on the actual rolling speed, the tension coefficient being used to determine the target tension between each stand, the tension coefficient being controlled between 1.0 and 1.5; determining the target tension between each stand based on a pre-determined set tension between each stand and the tension coefficient; and controlling the actual tension between each stand to increase to the corresponding target tension.

[0063] In this application, the actual rolling speed of the cold rolling mill is obtained. Based on the actual rolling speed of the cold rolling mill, the tension coefficient between each stand can be determined. By establishing a speed-coupled tension function, the target tension between each stand at different speeds can be determined.

[0064] Specifically, the product of the predetermined set tension and the corresponding tension coefficient between each rack can be calculated, and the calculated product can be used as the target tension between adjacent racks.

[0065] The tension coefficient between each stand in the cold rolling mill can be set individually, meaning that the tension coefficients between each stand can be the same or different.

[0066] In one embodiment, the method further includes: obtaining the shutdown threading speed of the cold rolling mill when it stops; if the first speed difference between the actual rolling speed and the start-up threading speed is less than a set speed difference threshold, then controlling the tension coefficient to 1.0 to 1.1; if the second speed difference between the actual rolling speed and the shutdown threading speed is less than the set speed difference threshold, then controlling the tension coefficient to 1.3 to 1.5.

[0067] In this application, when the cold rolling mill starts up, if the first speed difference between the actual rolling speed of the cold rolling mill and the starting strip threading speed is less than the set speed difference threshold, the tension coefficient is controlled at 1.0 to 1.1 to prevent excessive tension at the moment of starting up, which could cause the strip to break. When the cold rolling mill stops, if the first speed difference between the actual rolling speed of the cold rolling mill and the stopping strip threading speed is less than the set speed difference threshold, the tension coefficient is controlled at 1.3 to 1.5 to reduce the rolling force of each stand when the mill stops by increasing the tension, thereby preventing excessive rolling force from breaking the strip.

[0068] In one embodiment, controlling the actual tension between each frame to increase to the corresponding target tension includes: determining the tension variation value between each frame based on the actual tension between each frame and the corresponding target tension; determining the roll gap variation value of each frame based on the tension variation value between each frame and a tension influence coefficient, wherein the tension influence coefficient is used to characterize the correlation between the roll gap variation value of the frame and the tension variation value between the frames; and adjusting the roll gap of each frame based on the roll gap variation value of each frame to increase the actual tension between each frame to the corresponding target tension.

[0069] In this application, when the cold rolling mill starts up, the difference between the target tension and the actual tension between each stand is calculated as the tension change value between corresponding adjacent stands. By adjusting the roll gap size of the stands, the actual tension between the stands can be changed. The tension influence coefficient of each stand is obtained, and based on the tension change value and the tension influence coefficient between each stand, the roll gap change value of each stand can be determined. Based on the roll gap change value of each stand, the roll gap size of the corresponding stand can be adjusted through the PLC control system, thereby increasing the actual tension between each stand to the corresponding target tension.

[0070] Among them, the tension influence coefficient does not change with the rolling parameters of the stand. For the same tension change value, the larger the tension influence coefficient, the smaller the corresponding roll gap change value, and the smaller the tension influence coefficient, the larger the corresponding roll gap change value.

[0071] In one embodiment, determining the roll gap variation value of each frame based on the tension variation value and tension influence coefficient between each frame includes: determining a tension adjustment coefficient based on the starting and threading speed, wherein the tension adjustment coefficient is used to determine the roll gap variation value; calculating the product of the tension variation value between each frame and the tension adjustment coefficient, and calculating the ratio of the product to the tension influence coefficient as the roll gap variation value of each frame.

[0072] In this application, the tension adjustment coefficient can be determined based on the starting and threading speed. The tension adjustment coefficient can be considered as the tension adjustment gain of adjusting the actual tension between each frame to the corresponding target tension. Depending on the starting and threading speed, the automatic adjustment of the actual tension between each frame responds quickly at the starting and threading speed.

[0073] Calculate the product of the tension variation value and the tension adjustment coefficient between each frame, and then calculate the ratio of the product of the tension variation value and the tension adjustment coefficient between each frame to the tension influence coefficient. Use the calculated ratio as the roll gap variation value of each frame, and adjust the roll gap size of the corresponding frame according to the roll gap variation value of each frame.

[0074] In one embodiment, determining the tension adjustment coefficient based on the starting and threading speed includes: if the starting and threading speed is greater than or equal to a set speed, then controlling the tension adjustment coefficient between 0.7 and 1.0; if the starting and threading speed is less than the set speed, then controlling the tension adjustment coefficient between 1.0 and 1.2.

[0075] In this application, if the starting speed of the conveyor belt is greater than or equal to the set speed, it can be assumed that the tension difference between the actual tension and the corresponding target tension between each frame is small. It is necessary to reduce the magnitude of the unit tension change per unit time to prevent the unit tension change from being too large and making it impossible to accurately adjust the actual tension. Therefore, the tension adjustment coefficient is controlled between 0.7 and 1.0.

[0076] If the starting speed of the rolling mill is less than the set speed, it can be assumed that the tension difference between the actual tension and the corresponding target tension between each stand is large. It is necessary to increase the magnitude of the unit tension change per unit time and quickly adjust the actual tension between each stand so that the actual tension between each stand quickly converges to the corresponding target tension, so that the tension between each stand quickly reaches stability. This can significantly avoid the problem of strip breakage caused by tension instability during the start-up of the cold rolling mill. Therefore, the tension adjustment coefficient should be controlled between 1.0 and 1.2.

[0077] In one embodiment, after controlling the cold rolling mill to start according to a predetermined starting and threading speed, the method further includes: obtaining the actual thickness of the strip at each stand exit and the target thickness of the strip at each stand exit; if the thickness deviation value at each stand exit is less than a set thickness deviation threshold, then increasing the operating speed of the cold rolling mill to the first set rolling speed; if the actual thickness of the strip at the last stand exit reaches the target thickness of the strip at the last stand exit, then increasing the operating speed of the cold rolling mill to the second set rolling speed.

[0078] In this application, after the cold rolling mill is started according to a predetermined starting and threading speed, the minimum rolling speed for automatic flow rate and thickness control and the stable rolling speed for normal rolling of the cold rolling mill are obtained. The minimum rolling speed for automatic flow rate and thickness control can be used as the first set rolling speed, and the stable rolling speed for normal rolling of the cold rolling mill can be used as the second set rolling speed.

[0079] After the cold rolling mill is started, the rolling force of each stand and the actual rolling speed of the cold rolling mill can be adjusted based on the thickness deviation between the actual thickness of the strip at the exit of each stand and the corresponding target thickness.

[0080] Specifically, if the thickness deviation at the exit of each stand is less than the set thickness deviation threshold, and the strip in the deformation zone of the initial stand reaches the exit of the final stand, the operating speed of the cold rolling mill is increased to the minimum rolling speed for automatic thickness control per second, thereby achieving automatic thickness control per second.

[0081] The thickness deviation threshold can be set from 0 to 50 mm, but it is best to set it to 30 mm.

[0082] Meanwhile, after increasing the operating speed of the cold rolling mill to the minimum rolling speed for automatic thickness control, if the actual thickness of the strip at the end stand exit reaches the target thickness of the strip at the end stand exit, the operating speed of the cold rolling mill is increased to the stable rolling speed for normal rolling of the cold rolling mill, and then the cold rolling mill is controlled to perform stable rolling according to the stable rolling speed for normal rolling of the cold rolling mill.

[0083] For example, such as Figure 3 As shown, Figure 3 This diagram shows the rolling speed variation of a cold rolling mill from start-up to shutdown. During the start-up process, the cold rolling mill is controlled to start at a predetermined starting strip-feeding speed v1. After successful start-up, if the thickness deviation at each stand exit is less than the set thickness deviation threshold, and the strip in the deformation zone of the initial stand reaches the exit of the last stand, the actual rolling speed of the cold rolling mill is gradually increased. After the actual rolling speed reaches the minimum rolling speed v2 set by the automatic thickness control per second, the rolling speed is then controlled to continue at a speed of v2 per second. The minimum rolling speed v2 of the automatic flow and thickness control system is used. If the actual thickness of the strip at the exit of the last stand reaches the target thickness of the strip at the exit of the last stand, the actual rolling speed of the cold rolling mill is gradually increased until the actual rolling speed of the cold rolling mill reaches the stable rolling speed v3 of the cold rolling mill. The cold rolling mill is controlled to perform stable rolling according to the stable rolling speed v3. After the cold rolling mill receives a shutdown command, the actual rolling speed of the cold rolling mill is gradually reduced until the actual rolling speed drops to zero.

[0084] To enable those skilled in the art to more easily understand this application, a specific embodiment will be used to illustrate this application below.

[0085] The cold rolling mill consists of four stands, numbered according to the direction of strip movement: stand 1, stand 2, stand 3, and stand 4. The strip thickness at the cold rolling mill inlet is 2.4 mm, the strip thickness at the cold rolling mill outlet is 0.26 mm, and the strip width is 1050 mm.

[0086] The specific steps are as follows:

[0087] Step 1: Collect the minimum rolling speed v for automatic control of flow rate and thickness per second. mfAt 110 MPa, the rolling force and bending force of each stand in the cold rolling mill, as well as the position difference of the pressing cylinder between the working side and the drive side of each stand, are as follows: 1st stand: rolling force S1 = 1130 ton, bending force W1 = 7 ton, pressing cylinder position difference Y1 = 0.02 mm; 2nd stand: rolling force S2 = 1270 ton, bending force W2 = 9 ton, pressing cylinder position difference Y2 = 0.189 mm; 3rd stand: rolling force S3 = 1090 ton, bending force W3 = 8 ton, pressing cylinder position difference Y3 = 0.111 mm; 4th stand: rolling force S4 = 890 ton, bending force W4 = 13 ton, pressing cylinder position difference Y4 = 0.09 mm.

[0088] Step 2: After the cold rolling mill is shut down, the rolling force of each stand is reduced to 10-20% of the mill's ultimate rolling force. The mill's ultimate rolling force is 2000 tons, so the shutdown rolling force is reduced to 200 tons.

[0089] Step 3: Obtain the actual tension between adjacent stands in the cold rolling mill;

[0090] Step 4: If the actual tension between adjacent frames is zero, then tensioning is applied to the frames between the first and last frames in the adjacent frames.

[0091] Step 5: If the actual tension between adjacent stands is greater than zero, before starting the cold rolling mill, control the tension range between each stand to 0.5 ton to 20% of the set tension. The tension between stands 1 and 2 is 4 ton, the tension between stands 2 and 3 is 3.1 ton, the tension between stands 3 and 4 is 2.8 ton, and the tension between stand 4 and the coiler is 1.6 ton, so that the strip in each stand is in a taut state.

[0092] Step 6: Adjust the rolling force of each stand to its corresponding target rolling force, adjust the rolling force of each stand to its corresponding target bending roll force, and adjust the position difference of the pressing cylinder of each stand to its corresponding target pressing cylinder position difference.

[0093] Step 7: Start the cold rolling mill at the predetermined starting speed of 50mpm.

[0094] Step 8: During the start-up process of the cold rolling mill, obtain the actual rolling speed of the cold rolling mill, determine the tension coefficient between each stand based on the actual rolling speed, and determine the target tension between each stand based on the pre-determined set tension and tension coefficient between each stand. The tension coefficients of different cold rolling mill running speeds when the cold rolling mill starts up and stops are shown in Table 1 and Table 2, respectively.

[0095] Step 9: Determine the tension variation value between each frame based on the actual tension between each frame and the corresponding target tension. Determine the roll gap variation value between each frame based on the tension variation value between each frame and the tension influence coefficient. Adjust the roll gap of each frame based on the roll gap variation value between each frame so that the actual tension between each frame is increased to the corresponding target tension.

[0096] Step 10: After starting the rolling mill at the starting threading speed, intervene in the roll gap (i.e., the rolling force) based on the thickness deviation at the exit of each stand. This ensures that the thickness of each stand is close to the target thickness during rolling at the threading speed, with the deviation between (exit thickness and target thickness) for each stand within ±50µm. Once the strip from the deformation zone of stand 1 reaches the exit of the last stand, increase the operating speed of the cold rolling mill to the minimum rolling speed v for automatic thickness control per second. mf =110mpm. After the thickness at the exit of the last stand reaches the target thickness of 0.26mm for the cold-hardened finished product, the running speed of the cold rolling mill is increased to a stable rolling speed, and then the cold rolling mill is controlled to perform stable rolling.

[0097]

[0098] Table 1

[0099]

[0100] Table 2

[0101] The one or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0102] The technical solution proposed in this application can reduce the problem of strip breakage when the cold rolling mill is stopped and restarted to a certain extent, and can improve the yield of the cold rolling mill, while improving the production stability and manufacturing capacity of the cold rolling mill.

[0103] This application also provides a control device for a cold rolling mill, the device comprising: a data acquisition unit, an acquisition unit, a tension setting unit, an adjustment unit, and a control unit.

[0104] The unit comprises the following components: a data acquisition unit, used to acquire the rolling force and bending roll force of each stand in the cold rolling mill, as well as the position difference of the pressing cylinder between the working side and the drive side of each stand, when the cold rolling mill is running at a first set rolling speed; a data acquisition unit, used to acquire the actual tension between adjacent stands in the cold rolling mill; and a tension establishment unit, used to establish tension between the previous stand and the last stand in the adjacent stands if the actual tension between adjacent stands is zero. Tension processing, wherein the last stand is the last stand in the cold rolling mill; adjustment unit, used to adjust the rolling force of each stand to its corresponding target rolling force and the rolling force of each stand to its corresponding target bending roll force and the pressure cylinder position difference of each stand to its corresponding target pressure cylinder position difference if the actual tension between the adjacent stands is greater than zero, or after tensioning processing of the stands from the previous stand to the last stand in the adjacent stands; first control unit, used to control the start-up of the cold rolling mill according to a predetermined start-up and threading speed.

[0105] In some embodiments of this application, based on the foregoing scheme, the tension building unit is configured to: control the roll gap of the frames between the preceding frame and the last frame in the adjacent frames to open, so that the rolling force of the frames between the preceding frame and the last frame in the adjacent frames is reduced to zero; for any pair of adjacent frames between the preceding frame and the last frame in the adjacent frames, control the tension between the adjacent frames to be increased to 1.5 to 2.5 times a predetermined set tension.

[0106] In some embodiments of this application, based on the foregoing scheme, the device further includes a second control unit, which is used to acquire the actual rolling speed of the cold rolling mill; determine the tension coefficient between each stand according to the actual rolling speed, the tension coefficient being used to determine the target tension between each stand, the tension coefficient being controlled between 1.0 and 1.5; determine the target tension between each stand according to the predetermined set tension between each stand and the tension coefficient; and control the actual tension between each stand to increase to the corresponding target tension.

[0107] In some embodiments of this application, based on the foregoing scheme, the second control unit is configured to: obtain the shutdown threading speed when the cold rolling mill is stopped; if the first speed difference between the actual rolling speed and the start-up threading speed is less than a set speed difference threshold, then control the tension coefficient to 1.0 to 1.1; if the second speed difference between the actual rolling speed and the shutdown threading speed is less than the set speed difference threshold, then control the tension coefficient to 1.3 to 1.5.

[0108] In some embodiments of this application, based on the foregoing scheme, the second control unit is further configured to: determine the tension variation value between each frame according to the actual tension between each frame and the corresponding target tension; determine the roll gap variation value of each frame according to the tension variation value between each frame and the tension influence coefficient, wherein the tension influence coefficient is used to characterize the correlation between the roll gap variation value of the frame and the tension variation value between the frames; and adjust the roll gap of each frame according to the roll gap variation value of each frame so that the actual tension between each frame is increased to the corresponding target tension.

[0109] In some embodiments of this application, based on the foregoing scheme, the second control unit is further configured to: determine a tension adjustment coefficient according to the starting and belt threading speed, the tension adjustment coefficient being used to determine the roll gap change value; calculate the product of the tension change value between each frame and the tension adjustment coefficient, and calculate the ratio of the product to the tension influence coefficient as the roll gap change value of each frame.

[0110] In some embodiments of this application, based on the foregoing scheme, the second control unit is further configured to: if the starting speed of the vehicle and the belt threading speed is greater than or equal to the set speed, then control the tension adjustment coefficient to 0.7 to 1.0; if the starting speed of the vehicle and the belt threading speed is less than the set speed, then control the tension adjustment coefficient to 1.0 to 1.2.

[0111] In some embodiments of this application, based on the foregoing scheme, the control unit is configured such that the starting and belt threading speed is controlled between 20 and 70 mpm.

[0112] In some embodiments of this application, based on the foregoing scheme, the device further includes a third control unit, which is used to control the rolling force of each stand to be reduced to 10% to 20% of its corresponding ultimate rolling force, wherein the ultimate rolling force is the maximum rolling force of the stand.

[0113] In some embodiments of this application, based on the aforementioned scheme, the device further includes a lifting unit, which is used to obtain the actual thickness of the strip at each stand exit and the target thickness of the strip at each stand exit; if the thickness deviation value at each stand exit is less than a set thickness deviation threshold, the operating speed of the cold rolling mill is increased to the first set rolling speed; if the actual thickness of the strip at the last stand exit reaches the target thickness of the strip at the last stand exit, the operating speed of the cold rolling mill is increased to the second set rolling speed.

[0114] This application also provides a computer program product including computer instructions stored in a computer-readable storage medium and adapted to be read and executed by a processor to cause a computer device having the processor to perform the control method for the cold rolling mill as described in any of the above embodiments.

[0115] This application also provides a computer-readable medium, which may be included in an electronic device or exist independently without being assembled into an electronic device. The computer-readable storage medium stores at least one piece of program code, which is loaded and executed by a processor to implement the control method for the cold rolling mill described in any of the above embodiments.

[0116] This application also provides an electronic device, which includes one or more processors and one or more memories, wherein at least one piece of program code is stored in the one or more memories, and the at least one piece of program code is loaded and executed by the one or more processors to implement the control method of the cold rolling mill described in any of the above embodiments.

[0117] It should be noted that the computer-readable medium shown in the embodiments of this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination of the two. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fiber, portable compact disc read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such transmitted data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to wireless, wired, etc., or any suitable combination thereof.

[0118] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. Each block in a flowchart or block diagram may represent a module, segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0119] The units described in the embodiments of this application can be implemented in software or hardware, and the described units can also be located in a processor. The names of these units do not necessarily limit the specific unit itself.

[0120] It should be noted that although several modules or units for the device used to perform actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to the embodiments of this application, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0121] Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solutions according to the embodiments of this application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, external hard drive, etc.) or on a network, including several instructions to cause a computing device (such as a personal computer, server, touch terminal, or network device, etc.) to execute the method according to the embodiments of this application.

[0122] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0123] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of this application, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0124] It should be understood that this application is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A control method for a cold rolling mill, characterized in that, The method includes: The rolling force and bending force of each stand in the cold rolling mill, as well as the position difference of the pressing cylinder between the working side and the transmission side of each stand, are collected when the cold rolling mill is running at the first set rolling speed. These are used as the target rolling force, target bending force, and target pressing cylinder position difference of the corresponding stand when the cold rolling mill is started. Obtain the actual tension between adjacent stands in the cold rolling mill; If the actual tension between the adjacent stands is zero, then tensioning is performed on the stands between the previous stand and the last stand in the adjacent stands, where the last stand is the last stand in the cold rolling mill. If the actual tension between the adjacent stands is greater than zero, or after tensioning is performed on the stands between the previous stand and the last stand in the adjacent stands, the rolling force of each stand is adjusted to its corresponding target rolling force, the rolling force of each stand is adjusted to its corresponding target bending roll force, and the position difference of the pressing cylinder of each stand is adjusted to its corresponding target pressing cylinder position difference. The cold rolling mill is started according to the predetermined starting and threading speed. The process of setting up the racks between the previous rack and the last rack in the adjacent racks includes: The roll gap of the stands between the first and last stands in the adjacent stands is opened to reduce the rolling force of the stands between the first and last stands in the adjacent stands to zero. For any pair of adjacent racks between the preceding rack and the last rack, the tension between the adjacent racks is controlled to be increased to 1.5 to 2.5 times a predetermined set tension; The method further includes: Obtain the actual rolling speed of the cold rolling mill; Based on the actual rolling speed, the tension coefficient between each stand is determined. The tension coefficient is used to determine the target tension between each stand, and the tension coefficient is controlled between 1.0 and 1.

5. The target tension between each rack is determined based on the pre-determined set tension and the tension coefficient between each rack; Control the actual tension between each frame to increase to the corresponding target tension; The determination of the tension coefficient between each stand based on the actual rolling speed includes: Obtain the shutdown threading speed of the cold rolling mill when it is shut down; If the first speed difference between the actual rolling speed and the starting threading speed is less than a set speed difference threshold, then the tension coefficient is controlled between 1.0 and 1.

1. If the second speed difference between the actual rolling speed and the stop threading speed is less than the set speed difference threshold, then the tension coefficient is controlled between 1.3 and 1.

5. The control of increasing the actual tension between each frame to the corresponding target tension includes: The tension variation value between each rack is determined based on the actual tension between each rack and the corresponding target tension. Based on the tension variation value and tension influence coefficient between each frame, the roll gap variation value of each frame is determined. The tension influence coefficient is used to characterize the correlation between the roll gap variation value of the frame and the tension variation value between the frames. Adjust the roll gap of each frame according to the roll gap variation value of each frame so that the actual tension between each frame is increased to the corresponding target tension; The determination of the roll gap variation value for each frame based on the tension variation value and tension influence coefficient between each frame includes: Based on the starting and belt threading speed, a tension adjustment coefficient is determined, which is used to determine the roll gap change value. Calculate the product of the tension change value between each frame and the tension adjustment coefficient, and calculate the ratio of the product to the tension influence coefficient as the roll gap change value of each frame; The step of determining the tension adjustment coefficient based on the starting and threading speed includes: If the starting speed of the conveyor belt is greater than or equal to the set speed, the tension adjustment coefficient shall be controlled between 0.7 and 1.

0. If the starting speed of the conveyor belt is less than the set speed, the tension adjustment coefficient is controlled between 1.0 and 1.

2.

2. The method according to claim 1, characterized in that, The starting and threading speed is controlled at 20~70mpm.

3. The method according to claim 1, characterized in that, After the cold rolling mill is shut down, the method further includes: The rolling force of each stand is controlled to be reduced to 10% to 20% of its corresponding ultimate rolling force, where the ultimate rolling force is the maximum rolling force of the stand.

4. The method according to claim 1, characterized in that, After controlling the cold rolling mill to start according to a predetermined starting and threading speed, the method further includes: Obtain the actual thickness of the strip at each rack exit and the target thickness of the strip at each rack exit; If the thickness deviation at the exit of each stand is less than the set thickness deviation threshold, then the operating speed of the cold rolling mill is increased to the first set rolling speed. If the actual thickness of the strip at the exit of the last stand reaches the target thickness of the strip at the exit of the last stand, then the operating speed of the cold rolling mill is increased to the second set rolling speed.

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