A method for processing and manufacturing cold-rolled strip steel

Abstract

This application relates to a cold-rolled strip processing and manufacturing method, and the method includes the steps of: controlling the finish rolling temperature of the strip according to the head-middle-tail segmented finish rolling model; controlling the coiling temperature of the strip according to the head-middle-tail segmented coiling model; controlling the roll gap output according to the thickness deviation of the strip and the corresponding gain coefficient; and performing zonal shape adjustment on the strip according to the shape deviation of the strip. The cold-rolled strip processing and manufacturing method provided by the embodiments of this application effectively reduces the thickness and shape fluctuations of the cold-rolled strip, improves the shape and thickness control accuracy of the cold-rolled strip. After optimization using the method provided by the present invention, the thickness oscillation problem of the cold-rolled strip is significantly improved, and the incidence rate of thickness oscillation of cold-rolled strips of 590 MPa and above levels is reduced to about 0.1%.

Description

Technical Field

[0001] The present application relates to the field of cold-rolled steel strips, and in particular to a method for processing and manufacturing cold-rolled steel strips. Background Art

[0002] In the process of cold rolling high-strength steel, the alloy composition and organizational morphology of high-strength steel are different from those of ordinary plates, so the rolling force of high-strength steel is larger and the strip is harder. When producing higher-strength steel grades such as microalloy DP780 and DP980, the rolling force at the head and tail is about 1500KN-3000KN greater than the rolling force in the strip, and the average rolling speed of some specifications can only reach 30% of the design speed. In particular, the plate shape and plate thickness problems, the cold hard coil has obvious thickness fluctuations at the head and tail of about 60m, up to ±100μm, and the plate shape fluctuations are ±30IU. The thickness oscillation and plate shape mutation problems seriously affect the overall production rhythm of cold-rolled high-strength steel.

[0003] The galvanizing process can eliminate the plate shape problem to a certain extent, but it is very easy to get scratches in front of the furnace, and thickness fluctuations cannot be eliminated. In order to ensure the quality of the finished product, the head and tail need to be cut off in the subsequent galvanizing and continuous annealing production lines, which greatly reduces the yield rate of the finished strip steel. This problem can easily lead to substandard product quality of high-strength steel and produce waste. Summary of the invention

[0004] In order to solve the above technical problems or at least partially solve the above technical problems, the present application provides a cold-rolled strip processing and manufacturing method.

[0005] In a first aspect, the present application provides a method for processing and manufacturing cold-rolled steel strip, the method comprising the steps of:

[0006] The strip steel is subjected to segmented final rolling temperature control according to the head, middle and tail segmented final rolling model;

[0007] Controlling the coiling temperature of the strip steel in sections according to the head, middle and tail section coiling model;

[0008] Controlling the roll gap output according to the thickness deviation of the strip and the corresponding gain coefficient;

[0009] The strip shape is adjusted in different zones according to the strip shape deviation.

[0010] Preferably, the step of controlling the temperature of the steel strip by segmented final rolling according to the head, middle and tail segmented final rolling model comprises the following steps:

[0011] Dividing the strip into three sections: head, middle and tail;

[0012] Setting a first target finishing temperature of the middle portion;

[0013] Selecting a first interval of the head portion and a second interval of the tail portion;

[0014] Determine the second target finishing temperature of the first interval according to the first target finishing temperature;

[0015] Determine the third target finishing temperature of the second interval according to the first target finishing temperature;

[0016] Perform segmented finishing temperature control on the strip according to the first target finishing temperature, the second target finishing temperature and the third target finishing temperature.

[0017] Preferably, the first interval is an interval within a range of 30 m - 60 m from the end of the head, and the second interval is an interval within a range of less than or equal to 60 m from the end of the tail.

[0018] Preferably, the second target finishing temperature is at least 20 °C lower than the first target finishing temperature, and the third target finishing temperature is at least 20 °C higher than the first target finishing temperature.

[0019] Preferably, the performing segmented coiling temperature control on the strip according to the head-middle-tail segmented coiling model includes the steps of:

[0020] Obtain three intervals of the head, middle and tail into which the strip is divided in the head-middle-tail segmented finishing model;

[0021] Set the first target coiling temperature of the middle part;

[0022] Select the third interval of the head and the fourth interval of the tail;

[0023] Determine the second target coiling temperature of the third interval according to the first target coiling temperature;

[0024] Determine the third target coiling temperature of the fourth interval according to the first target coiling temperature;

[0025] Perform segmented coiling temperature control on the strip according to the first target coiling temperature, the second target coiling temperature and the third target coiling temperature.

[0026] Preferably, the third interval is an interval within a range of 60 m from the end of the head, and the fourth interval is an interval within a range of less than or equal to 60 m from the end of the tail.

[0027] Preferably, the second target coiling temperature is at least 30 °C lower than the first target coiling temperature, and the third target coiling temperature is at least 30 °C higher than the first target coiling temperature.

[0028] Preferably, the expression of the roll gap output is:

[0029] SMF = (SMFF + SMFB) × a;

[0030] Wherein, SMF represents the roll gap output, SMFF represents the feedforward roll gap output, SMFB represents the feedback roll gap output, and a represents the gain coefficient.

[0031] Preferably, the expression of the feedforward roll gap output is:

[0032] SMFF = KPMF × Gain1 × Gain2 × Gain3 × Gain4 × (hREF - (HXE × Ventry / Vexit) × (1 + η)) / hREF;

[0033] Wherein, SMFF represents the feedforward speed adjustment, KPMF represents the proportional coefficient, Gain1, Gain2, Gain3, Gain4 represent the system gains, hREF represents the set thickness at the exit, HXE represents the set thickness at the entrance, Ventry represents the strip entrance speed, Vexit represents the strip exit speed, and η represents the compensation coefficient.

[0034] Preferably, the expression of the feedback roll gap output is:

[0035] SMFB = KIMF × Gain1 × Gain2 × Gain3 × Gain4 × (hREF - (hDREF × Ventry / Vexit) / (1 + η)) / hREF;

[0036] Wherein, SMFB represents the feedback roll gap output, KIMF represents the integral coefficient, Gain1, Gain2, Gain3, Gain4 represent the system gains, hREF represents the set thickness at the exit, hDREF represents the set thickness at the entrance, Ventry represents the strip entrance speed, Vexit represents the strip exit speed, and η represents the compensation coefficient.

[0037] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0038] A cold-rolled strip processing and manufacturing method provided by the embodiments of the present application effectively reduces the thickness and shape fluctuations of cold-rolled strips, improves the control precision of the shape and thickness of cold-rolled strips. After optimization by the method provided by the present invention, the thickness oscillation problem of cold-rolled strips is significantly improved, and the incidence rate of thickness oscillation of cold-rolled strips of 590 MPa and above grades is reduced to about 0.1%. Brief Description of the Drawings

[0039] The drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present invention and used together with the specification to explain the principles of the present invention.

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0041] Figure 1 It is a schematic flow chart of a cold-rolled strip processing and manufacturing method provided by an embodiment of the present application;

[0042] Figure 2 It is a schematic diagram of the definition of head and tail parameters of segmented finish rolling / coiling in a cold-rolled strip processing and manufacturing method provided by an embodiment of the present application;

[0043] Figure 3 It is a schematic diagram of the FG function relationship of variable gain control for different thickness fluctuation ranges in a cold-rolled strip processing and manufacturing method provided by an embodiment of the present application;

[0044] Figure 4 It is a schematic diagram of stepped thickness variable gain control for different thickness fluctuation ranges in a cold-rolled strip processing and manufacturing method provided by an embodiment of the present application;

[0045] Figure 5 It is a multi-dimensional differential control flow chart for shape fluctuations in a cold-rolled strip processing and manufacturing method provided by an embodiment of the present application;

[0046] Figure 6 It is a schematic diagram of the non-linear model of neurons in a cold-rolled strip processing and manufacturing method provided by an embodiment of the present application. Detailed implementation manners

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0048] Figure 1 It is a schematic flow chart of a cold-rolled strip processing and manufacturing method provided by an embodiment of the present application.

[0049] The present application provides a cold-rolled strip processing and manufacturing method, and the method includes the steps:

[0050] S1: Perform segmented finish rolling temperature control on the strip according to the head-middle-tail segmented finish rolling model;

[0051] In the embodiment of the present application, the step of controlling the finish rolling temperature of the strip according to the head-middle-tail segmented finish rolling model includes the steps:

[0052] Divide the strip into three sections: the head, the middle, and the tail;

[0053] Set the first target finish rolling temperature of the middle section;

[0054] Select the first section of the head and the second section of the tail;

[0055] Determine the second target finish rolling temperature of the first section according to the first target finish rolling temperature;

[0056] Determine the third target finish rolling temperature of the second section according to the first target finish rolling temperature;

[0057] Control the finish rolling temperature of the strip in segments according to the first target finish rolling temperature, the second target finish rolling temperature, and the third target finish rolling temperature.

[0058] Such as Figure 2 , specifically, the present application provides a method for controlling the finish rolling temperature of hot-rolled high-strength steel, which controls the finish rolling temperature in segments according to three positions: the head, the middle of the strip, and the tail, including the length of the hot head, the temperature drop of the hot head, the uniformity control of the middle of the strip, and the temperature rise of the hot tail, and realizes the setting of different process parameters according to different steel grades, specifications, and user settings, so as to ensure the consistency of the through-strip performance.

[0059] In the embodiment of the present application, the first section is the section within the range of 30m - 60m from the end of the head, and the second section is the section within the range of less than or equal to 60m from the end of the tail.

[0060] In the embodiment of the present application, the second target finish rolling temperature is at least 20°C lower than the first target finish rolling temperature, and the third target finish rolling temperature is at least 20°C higher than the first target finish rolling temperature.

[0061] S2: Control the coiling temperature of the strip in segments according to the head-middle-tail segmented coiling model;

[0062] In the embodiment of the present application, the step of controlling the coiling temperature of the strip according to the head-middle-tail segmented coiling model includes the steps:

[0063] Obtain the three sections of the head, the middle, and the tail into which the strip is divided in the head-middle-tail segmented finish rolling model;

[0064] Set the first target coiling temperature of the middle section;

[0065] Select the third section of the head and the fourth section of the tail;

[0066] Determine the second target coiling temperature of the third interval according to the first target coiling temperature;

[0067] Determine the third target coiling temperature of the fourth interval according to the first target coiling temperature;

[0068] Perform segmented coiling temperature control on the strip steel according to the first target coiling temperature, the second target coiling temperature, and the third target coiling temperature.

[0069] Such as Figure 2 , specifically, the head-middle-tail segmented coiling model provided in this application is calculated and realized by setting different target coiling temperatures for the entire length of the strip steel, that is, converting the set values of the hot head length and the hot tail length into the number of control samples at the head and tail respectively, combining the given hot head temperature rise and hot tail temperature rise values, and adding the head and tail self-learning parameter compensation values to set the control targets for different samples. The main idea of the head-middle-tail segmented coiling model is to set the target coiling temperatures of the strip steel head and tail within a certain distance range respectively, and reduce the number of header pipes opened during the laminar cooling stage to make the actual coiling temperatures of each section of the strip steel head, middle, and tail show a linear change. In addition to the conventional target coiling temperature, it is also necessary to give the set values of the cooling head parameters (hot head temperature rise, hot head length) and the cooling tail parameters (hot tail temperature rise, hot tail length) for the segmented coiling type.

[0070] Furthermore, during the coiling process of hot-rolled strip steel, the coiling temperature of the entire coil is set to a constant target temperature. After the strip steel is coiled, due to the different heat dissipation during the radial heat exchange process of the steel coil, it will cause fluctuations and differences in the performance of the hot-rolled coil due to the differences in the microstructure properties and grain sizes of the strip steel in the inner and outer circles of the hot-rolled coil and the strip steel in the middle of the coil diameter direction, affecting the qualification rate in the length direction of the strip steel. Therefore, a head-middle-tail segmented coiling control strategy is developed in the post-rolling cooling control system to make up for the mechanical property differences caused by uneven heat dissipation of the strip steel after coiling, so as to further improve the qualification rate of the performance of the entire coil of strip steel.

[0071] In the embodiment of this application, the third interval is the interval within 60 m from the end of the head, and the fourth interval is the interval within less than or equal to 60 m from the end of the tail.

[0072] In the embodiment of this application, the second target coiling temperature is at least 30 °C lower than the first target coiling temperature, and the third target coiling temperature is at least 30 °C higher than the first target coiling temperature.

[0073] S3: Control the roll gap output according to the thickness deviation of the strip steel and the corresponding gain coefficient;

[0074] Such as Figure 3, in the embodiment of the present application, the present application establishes a stepped variable gain automatic thickness control function based on the second flow rate. According to the thickness deviation of the real-time feedback calculated by the second flow rate, the variable gain automatic thickness control roll gap output is carried out through the second flow rate AGC, and the MF-AGC stepped control function is developed to reduce the thickness fluctuation of high-strength steel. By developing the FGC function, the gain corresponding to the percentage of thickness deviation is amplified. For deviations above 15μm, large gain control is implemented, and the second flow rate feedback adjustment rate and roll gap adjustment amount are increased, effectively improving the thickness fluctuation at the head and tail. The input item x is the deviation between the set thickness and the actual thickness, with the unit of 0.1μm, and the output y is the control gain coefficient of MF-AGC, with the unit of %.

[0075] In the embodiment of the present application, the expression of the roll gap output is:

[0076] SMF = (SMFF + SMFB) × a;

[0077] Wherein, SMF represents the roll gap output, SMFF represents the feedforward roll gap output, SMFB represents the feedback roll gap output, and a represents the gain coefficient.

[0078] In the embodiment of the present application, the expression of the feedforward roll gap output is:

[0079] SMFF = KPMF × Gain1 × Gain2 × Gain3 × Gain4 × (hREF - (HXE × Ventry / Vexit) × (1 + η)) / hREF;

[0080] Wherein, SMFF represents the feedforward speed adjustment amount, KPMF represents the proportional coefficient, Gain1, Gain2, Gain3, and Gain4 represent the system gains, hREF represents the set thickness at the outlet, HXE represents the set thickness at the inlet, Ventry represents the strip inlet speed, Vexit represents the strip outlet speed, and η represents the compensation coefficient.

[0081] As Figure 4 , in the embodiment of the present application, the present application establishes a stepped variable gain automatic thickness control function based on the second flow rate to control the roll gap output according to the thickness deviation of the strip and the corresponding gain coefficient. According to the thickness deviation of the real-time feedback calculated by the second flow rate, the variable gain automatic thickness control roll gap output is carried out through the second flow rate AGC to reduce the amplitude of the thickness fluctuation at the outlet of the cold rolling strip mill.

[0082] In the embodiment of the present application, the expression of the feedback roll gap output is:

[0083] SMFB = KIMF × Gain1 × Gain2 × Gain3 × Gain4 × (hREF - (hDREF × Ventry / Vexit) / (1 + η)) / hREF;

[0084] Among them, SMFB represents the output of the feedback roll gap, KIMF represents the integral coefficient, Gain1, Gain2, Gain3, and Gain4 represent the system gains, hREF represents the set thickness at the exit, hDREF represents the set thickness at the entrance, Ventry represents the strip entrance speed, Vexit represents the strip exit speed, and η represents the compensation coefficient.

[0085] S4: Perform zonal shape adjustment on the strip according to the shape deviation of the strip.

[0086] Such as Figure 5 and 6 , in the embodiments of the present application, the present application designs a multi-dimensional differential shape adjustment method that adopts a symmetric mirror image mode for zoning according to the shape fluctuations on the drive side and the operator side in the strip width direction, and uses it as a control strategy and control method to offset the multi-dimensional differential shape and shape mutation caused by the performance problems of high-strength steel.

[0087] Specifically, taking WS as an example, the actual shape is checked and fed back through a shape meter, and the real-time shape deviation between the real-time shape of the WS (operator side) half-channel and the target shape is analyzed. The least squares formula in the function is called to fit it into a quadratic curve, and the fitting function is min2((int)ascint_g.useful_ch, 2). The shape deviation value y of each channel (DS is the mirror image of the WD side) shown in the above figure is fitted using the least squares method, and the fitting equation is Y = b0 + b1X + b2X2, where X is the channel number and Y is the shape fitting deviation. Three coefficients b0, b1 (primary deviation), and b2 (secondary deviation) are obtained by fitting, and b2 = func2deg[2] is the shape secondary deviation.

[0088] Furthermore, the control logic of the multi-dimensional differential bending roll mode is as follows. If the secondary deviation is outside the absolute value of the dead zone, control is input, and the absolute value of the dead zone is 1IU. The expression is:

[0089] fiaws_ref = (-1.0) × func2ws_deg[2] × figain × 0.01 / ficoef / 1000.0(1)

[0090] The output value of the intermediate roll bending roll WS = 1 × secondary deviation × bending roll gain value × 0.01 / bending roll efficiency coefficient / 1000

[0091] Among them, fiwsref represents the output of the ws side bending roll force, func2wsdeg[2] represents the secondary deviation of the ws side (half of the operating side), Figain represents the intermediate roll bending roll gain, and ficoef represents the intermediate roll bending roll efficiency coefficient = -0.2 IU / KN.

[0092] In addition, the multi-dimensional differential tilt mode control logic is as follows. When the multi-dimensional differential mode of the roll shifting is turned on, if the secondary deviation is outside the absolute value of the dead zone, the control is input. The absolute value of the dead zone is 2 IU, and the expression is:

[0093] Imrsaws_ref = (1.0) × OrderDifWs × ImrsGain × 0.01 / ImrsCoef / 1000.0)

[0094] The output value of the roll shifting on the ws side = 1 × secondary deviation × roll shifting gain value × 0.01 / roll shifting efficiency coefficient / 1000

[0095] Among them, Imrsaws_ref represents the output of the roll shifting amount on the ws side, func2wsdeg[2] represents the secondary deviation of the ws side (half of the operating side), ImrsGain represents the roll shifting gain value, ImrsGain = 100, and mrsCoef represents the roll shifting efficiency coefficient = 0.3 IU / mm.

[0096] In this application, a shape control method for quickly adjusting the shape deviation of the strip steel is established by partitioning the shape adjustment of the strip steel according to the shape deviation of the strip steel. Through the adjustment range of the multi-dimensional differential intermediate roll bending roll and roll shifting, the shape adjustment and mirror fitting adjustment are carried out to improve the shape fluctuation of the cold-rolled strip steel.

[0097] A cold-rolled strip steel processing and manufacturing method provided by an embodiment of this application effectively reduces the thickness and shape fluctuation of the cold-rolled strip steel, improves the control accuracy of the shape and thickness of the cold-rolled strip steel. After optimization by the method provided by the present invention, the thickness oscillation problem of the cold-rolled strip steel is significantly improved, and the incidence rate of the thickness oscillation of the cold-rolled strip steel of 590 MPa and above levels is reduced to about 0.1%.

[0098] It should be noted that, in this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0099] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for processing and manufacturing cold-rolled strip steel, characterized in that, the method comprises the steps of: Controlling the finishing rolling temperature of the strip steel according to the head-middle-tail segmented finishing rolling model; Controlling the coiling temperature of the strip steel according to the head-middle-tail segmented coiling model; Controlling the roll gap output according to the thickness deviation of the strip steel and the corresponding gain coefficient; Adjusting the strip shape in zones according to the strip shape deviation of the strip steel; The expression of the roll gap output is: SMF = (SMFF + SMFB) × a; wherein, SMF represents the roll gap output, SMFF represents the feedforward roll gap output, SMFB represents the feedback roll gap output, and a represents the gain coefficient; The expression of the feedforward roll gap output is: SMFF = KPMF × Gain1 × Gain2 × Gain3 × Gain4 × (hREF - (HXE × Ventry / Vexit) × (1 + η)) / hREF; wherein, SMFF represents the feedforward roll gap output, KPMF represents the proportional coefficient, Gain1, Gain2, Gain3, Gain4 represent the system gains, hREF represents the set thickness at the exit, HXE represents the set thickness at the entrance, Ventry represents the strip steel entrance speed, Vexit represents the strip steel exit speed, and η represents the compensation coefficient; The expression of the feedback roll gap output is: SMFB = KIMF × Gain1 × Gain2 × Gain3 × Gain4 × (hREF - (hDREF × Ventry / Vexit) / (1 + η)) / hREF; wherein, SMFB represents the feedback roll gap output, KIMF represents the integral coefficient, Gain1, Gain2, Gain3, Gain4 represent the system gains, hREF represents the set thickness at the exit, hDREF represents the set thickness at the entrance, Ventry represents the strip steel entrance speed, Vexit represents the strip steel exit speed, and η represents the compensation coefficient.

2. The method for processing and manufacturing cold-rolled strip steel according to claim 1, characterized in that, The step of controlling the finishing rolling temperature of the strip steel according to the head-middle-tail segmented finishing rolling model comprises the steps of: Dividing the strip steel into three sections: the head, the middle, and the tail; Setting the first target finishing rolling temperature of the middle section; Selecting the first section of the head and the second section of the tail; Determining the second target finishing rolling temperature of the first section according to the first target finishing rolling temperature; Determining the third target finishing rolling temperature of the second section according to the first target finishing rolling temperature; Controlling the finishing rolling temperature of the strip steel in segments according to the first target finishing rolling temperature, the second target finishing rolling temperature, and the third target finishing rolling temperature.

3. The method for processing and manufacturing cold-rolled strip steel according to claim 2, characterized in that, The first section is the section within the range of 30m - 60m from the end of the head, and the second section is the section within the range of less than or equal to 60m from the end of the tail.

4. The method for processing and manufacturing cold-rolled strip steel according to claim 2, characterized in that, The second target finishing rolling temperature is at least 20 °C lower than the first target finishing rolling temperature, and the third target finishing rolling temperature is at least 20 °C higher than the first target finishing rolling temperature.

5. The cold-rolled strip processing and manufacturing method according to claim 1, characterized in that the segmented coiling temperature control of the strip according to the head-middle-tail segmented coiling model includes the steps of: obtaining three intervals of the head, middle, and tail into which the strip is divided in the head-middle-tail segmented finishing rolling model; setting the first target coiling temperature of the middle part; selecting the third interval of the head and the fourth interval of the tail; determining the second target coiling temperature of the third interval according to the first target coiling temperature; determining the third target coiling temperature of the fourth interval according to the first target coiling temperature; performing segmented coiling temperature control on the strip according to the first target coiling temperature, the second target coiling temperature, and the third target coiling temperature.

6. The cold-rolled strip processing and manufacturing method according to claim 5, characterized in that the third interval is an interval within 60 m from the end of the head, and the fourth interval is an interval within less than or equal to 60 m from the end of the tail.

7. The cold-rolled strip processing and manufacturing method according to claim 5, characterized in that the second target coiling temperature is at least 30 °C lower than the first target coiling temperature, and the third target coiling temperature is at least 30 °C higher than the first target coiling temperature.

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