A method for improving the thickness control accuracy of hot rolled strip steel

Abstract

An embodiment of the present invention provides a method for improving the thickness control accuracy of hot-rolled strip steel, comprising: pre-dividing the strip steel into three strip steel parts, namely a head section, a middle section and a tail section, and setting preset thickness compensation values ​​for the head section, the middle section and the tail section, respectively; correcting the strip steel thickness data measured by a thickness gauge of a finishing mill according to the strip steel part currently being rolled by the rolling roller using the preset thickness compensation value corresponding to the strip steel part to obtain corrected strip steel thickness data; inputting the corrected strip steel thickness data into an AGC thickness control system to control the roll gap of the rolling roller in real time, so as to control the strip steel thickness at the strip steel part.

Description

Technical Field

[0001] The invention relates to the technical field of steel rolling, and in particular to a method for improving the thickness control accuracy of hot-rolled steel strip. Background Art

[0002] In the production process of hot-rolled strip steel, according to the thickness and width requirements of the user's contract, the steel billet undergoes heating, rolling, cooling, and coiling to become a steel coil with a specific thickness and width. The steel coil is flattened by the user to a fixed length and becomes a steel plate that can be directly processed and used. Most users who pay by weight for the steel coils they purchase hope to flatten more steel plates. Therefore, it is necessary to roll the hot-rolled steel coils as thin as possible while meeting the delivery standards. Under the condition that the coil weight remains unchanged, users can get more steel plates, that is, improve the use yield. In the existing thickness control system, the hot rolling thickness control is mainly completed by the secondary model control and the finishing mill AGC thickness control system. The secondary model calculates the roll gap of the seven finishing mills according to the thickness requirements of the steel coil, combined with the temperature, steel type, cooling water volume of the finishing steel coil, etc., to control the head thickness of the strip. When the head of the strip reaches the thickness gauge at the finishing exit, the measured thickness is fed back to the AGC (automatic thickness control system) system to realize closed-loop thickness control. The AGC system adjusts the roll gap size of the rolling mill according to the deviation between the feedback thickness and the target thickness to achieve the target thickness requirement.

[0003] In the process of implementing the present invention, the applicant discovered that there are at least the following problems in the prior art:

[0004] How to accurately control the thickness of hot-rolled strip and improve the yield rate. Summary of the invention

[0005] The embodiment of the present invention provides a method for improving the thickness control accuracy of hot-rolled steel strip, which solves the problem of how to accurately control the thickness of the hot-rolled steel strip and improve the utilization yield.

[0006] To achieve the above-mentioned purpose, on the one hand, an embodiment of the present invention provides a method for improving the thickness control accuracy of hot-rolled strip steel, comprising:

[0007] The strip steel is pre-divided into three strip steel sections, namely, a head section, a middle section and a tail section, and preset thickness compensation values ​​are respectively set for the head section, the middle section and the tail section;

[0008] According to the strip portion currently being rolled by the roller, the strip thickness data measured by the thickness gauge of the finishing mill is corrected using a preset thickness compensation value corresponding to the strip portion to obtain corrected strip thickness data;

[0009] The corrected strip thickness data is input into the AGC thickness control system to control the roll gap of the rolling mill in real time to control the strip thickness at the strip portion.

[0010] Further, the strip thickness data measured by the thickness gauge of the finishing mill is corrected according to the strip portion currently being rolled by the roller using a preset thickness compensation value corresponding to the strip portion to obtain the corrected strip thickness data, including:

[0011] If the part of the strip currently being rolled is the middle section, the preset negative difference in strip thickness is added as the thickness compensation value to the strip thickness data measured by the finishing mill thickness gauge to obtain the corrected strip thickness data; wherein the negative difference in strip thickness is less than 0.

[0012] Further, the strip thickness data measured by the thickness gauge of the finishing mill is corrected according to the strip portion currently being rolled by the roller using a preset thickness compensation value corresponding to the strip portion to obtain the corrected strip thickness data, including:

[0013] If the portion of the strip currently being rolled is the head section, according to the offset distance of the position currently being rolled on the strip relative to the head end of the strip, a strip thickness compensation value corresponding to the offset distance is selected from a preset strip thickness compensation value table, and the strip thickness compensation value is accumulated to the strip thickness data measured by the finishing mill thickness gauge to obtain the corrected strip thickness data;

[0014] Wherein, the strip thickness compensation value table includes at least one set of offset distances and corresponding strip thickness compensation values.

[0015] Further, the strip thickness data measured by the thickness gauge of the finishing mill is corrected according to the strip portion currently being rolled by the roller using a preset thickness compensation value corresponding to the strip portion to obtain the corrected strip thickness data, including:

[0016] If the portion of the steel strip currently being rolled is the tail section, the thickness compensation value is set to 0, and the steel strip thickness data measured by the finishing mill thickness gauge is used as the corrected steel strip thickness data.

[0017] Further, if the thickness of the steel strip is greater than or equal to a preset steel strip thickness, the head section is a portion of the steel strip of a first preset length starting from the head end;

[0018] If the thickness of the steel strip is less than the preset steel strip thickness, the head section is a portion of the steel strip of a second preset length starting from the head end;

[0019] Wherein, the first preset length is smaller than the second preset length;

[0020] The second preset length is the distance between the head end of the steel strip and the thickness gauge of the finishing mill when the head end of the steel strip enters the coiler to establish tension.

[0021] Furthermore, the tail section is the distance from the tail end of the steel strip to the thickness gauge of the finishing mill when the tail end of the steel strip leaves the first finishing mill.

[0022] Furthermore, the method further comprises: setting an operation interface;

[0023] The operation interface is used to set the thickness compensation value, provide first mode selection and second mode selection functions, and automatic selection and manual selection functions;

[0024] The first mode is used to determine the head section, middle section and tail section of the strip when the thickness of the strip is greater than or equal to the preset strip thickness, and to correct the strip thickness data measured by the thickness gauge of the finishing mill according to the strip section currently being rolled by the roller using the preset thickness compensation value corresponding to the strip section to obtain the corrected strip thickness data;

[0025] The second mode is used to determine the head section, middle section and tail section of the strip when the thickness of the strip is less than the preset strip thickness, and to correct the strip thickness data measured by the thickness gauge of the finishing mill according to the strip section currently being rolled by the roller using the preset thickness compensation value corresponding to the strip section to obtain the corrected strip thickness data;

[0026] When the automatic selection function is selected, the first mode or the second mode is automatically selected according to the relationship between the thickness of the steel strip and the preset thickness of the steel strip;

[0027] When the manual selection function is selected, the first mode or the second mode is manually selected.

[0028] Further, the method comprises:

[0029] The first mode: if the strip thickness is greater than or equal to the preset strip thickness, the thickness virtual compensation function is used at the first preset length of the thickness gauge of the finishing mill at the head end of the strip, and the thickness of the strip after the first preset length is adjusted, and the thickness virtual compensation function is stopped when the tail of the strip reaches the first finishing mill;

[0030] The second mode: if the strip thickness is less than the preset strip thickness, the thickness virtual compensation function is used after the strip head enters the coiler to establish tension, and the strip thickness is adjusted thereafter. When the strip tail reaches the first finishing mill, the thickness virtual compensation function is stopped to wait for the strip head to stabilize in shape after coiling and tensioning before adjusting the roll gap.

[0031] The method further comprises: setting an operation interface;

[0032] The operation interface includes: a thickness compensation value setting function, a first mode selection function and a second mode selection function, and an automatic selection function and a manual selection function;

[0033] The automatic selection function is used to automatically adopt the first mode for the strip steel whose thickness is greater than or equal to the preset strip steel thickness, and automatically adopt the second mode for the strip steel whose thickness is less than the preset strip steel thickness when the automatic selection is selected;

[0034] The manual selection function is used to manually select the first mode or the second mode when the automatic selection is selected;

[0035] The method further comprises: for the head section, according to the offset distance of the position currently being rolled on the strip relative to the head end of the strip, selecting a strip thickness compensation value corresponding to the offset distance from a preset strip thickness compensation value table, and accumulating the strip thickness compensation value to the strip thickness data measured by the finishing mill thickness gauge to obtain the corrected strip thickness data;

[0036] Wherein, the strip thickness compensation value table includes at least one set of offset distances and corresponding strip thickness compensation values.

[0037] Furthermore, the method for improving the thickness control accuracy of hot-rolled strip is specifically as follows: for strips with a thickness greater than or equal to 2.5 mm, a thickness virtual compensation function is used at a thickness gauge of 50 meters at the head end of the strip out of the finishing mill, and the thickness of the strip after 50 meters is adjusted, and the thickness virtual compensation function is stopped when the tail of the strip reaches the finishing rolling F1.

[0038] Furthermore, the method for improving the thickness control accuracy of hot-rolled strip is specifically as follows: for strips with a thickness less than 2.5 mm, the thickness virtual compensation function is used after the strip head end leaves the finishing mill thickness gauge for a length greater than or equal to 100 meters and the strip head end enters the coiler to establish tension, and the thickness of the strip is adjusted thereafter, and the thickness virtual compensation function is stopped when the tail of the strip reaches the finishing rolling F1.

[0039] The above technical solution has the following beneficial effects:

[0040] By adding the strip AGC thickness compensation correction function, taking advantage of the small thickness fluctuation of hot-rolled strip after strip threading and tensioning, the middle thickness is thinned and controlled, effectively improving the use rate of strip, improving user satisfaction, and improving the utilization efficiency of strip, saving steel resources under the premise of meeting the requirements. For example, the head and tail of the slightly thin strip are removed, a total of 150 meters, and the thickness is not precisely controlled. The remaining middle part can be controlled for a distance of about 800 meters, and the controllable length is as high as more than 80%. Especially for extremely thin specifications such as 1.6 mm, 1.8 mm, and 2.0 mm, the effect is more significant. Taking the steel plate with a nominal thickness of 1.6 mm as an example, its actual controlled thickness is 1.48 mm, and the negative tolerance is -0.12 mm. After this function is put into use, the negative tolerance can reach -0.14 mm, and the improvement is: -0.2 / -0.12=16.7%. Further, through the multi-stage thickness compensation adjustment of the strip, the regular thickness fluctuation of the fixed position of the strip is significantly eliminated, and the regular thickness fluctuation is reduced. The strategy of controlling the thickness of the head and tail parts and the middle part of the strip differently is adopted. Since there are more environmental variables in the head and tail parts of the strip, they are controlled according to the original target thickness, while the thickness control of the middle part of the strip is relatively uniform and stable. In this process, the negative difference of the strip thickness is increased, and the thickness of the middle part of the strip is controlled to be thinner, so as to increase the rolling length of the whole strip and ultimately achieve the purpose of improving the utilization yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 This is a flow chart of a method for improving the thickness control accuracy of hot-rolled strip steel according to one embodiment of the present invention;

[0043] Figure 2 It is a thickness fluctuation trend diagram of hot-rolled strip steel in the prior art;

[0044] Figure 3 It is a schematic diagram of the AGC thickness control system under the prior art;

[0045] Figure 4 It is a schematic diagram of an AGC thickness control system of a method for improving the thickness control accuracy of hot-rolled strip steel according to one embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In order to solve the problem of how to improve the yield rate while keeping the coil weight unchanged, the inventors found that the thickness of hot-rolled strip steel fluctuates to a certain extent during production. It is necessary to ensure that the thickness of the entire coil meets the upper and lower limits of the delivery standard, reduce thickness fluctuations, and implement thickness negative deviation rolling delivery, which is the most effective way to improve the yield rate.

[0048] Simple calculation using yield:

[0049] However, because the actual width generally deviates less from the standard width, For example, the standard thickness of a certain product ordered by a user is 4.5mm (mm stands for millimeters). The contract standard stipulates that a deviation of ±0.1mm is allowed. Considering the thickness fluctuation of the entire coil, the actual thickness is delivered as 4.45mm. The user uses

[0050] The inventor further analyzed the existing thickness control system and found that Figure 2 As shown in the figure, the target value curve corresponds to the expected thickness of the strip, and the front and rear ends of the actual thickness curve correspond to the temperature fluctuations at the head and tail of the strip, respectively. Figure 2 It can be seen that the large temperature deviation at the head and tail of the strip, the looper being in a state of tension loss, and the unstable plate shape lead to large fluctuations in the thickness of the head and tail of the strip, while the thickness of the middle part is stable and fluctuates little due to uniform temperature and stable tension. Figure 3 In the existing thickness control system shown, in order to ensure that the thickness of the entire coil meets the contract delivery standard range, the rolling thickness setting is always thicker than the lower limit of the user's contract standard thickness range by a sufficient margin, which cannot achieve a large negative tolerance rolling thickness delivery and cannot achieve the user's maximum usage yield.

[0051] According to the above findings, Figure 4As shown, the inventor proposes that by adjusting the thickness compensation of the finishing AGC, the process thickness can achieve relative negative tolerance rolling under the premise of meeting the target value of the strip thickness control, and further improve the strip yield. A method for compensating thickness control using the finishing AGC thickness control system is specifically designed, which adopts a strategy of differentially controlling the thickness of the head and tail parts and the middle part of the strip. Because there are many environmental variables in the head and tail parts of the strip, they are controlled according to the original target thickness, while the thickness control of the middle part of the strip is relatively uniform and stable. In this process, the negative difference of the strip thickness is increased, and the thickness of the middle part of the strip is controlled to be thinner, so as to increase the rolling length of the whole strip, and finally achieve the purpose of improving the yield. In some embodiments, the secondary model control controls the thickness of the head without intervention, and only the AGC control strategy needs to be optimized. The AGC thickness control system is based on the target thickness issued by the secondary model control, and the mill roll gap is compensated and adjusted according to the thickness deviation detected by the thickness gauge to achieve strip thickness control. The inventor pioneered the compensation and correction of the thickness difference data fed back from the thickness gauge and sent it to the AGC control system, indirectly changing the target thickness and realizing the separate control of the middle thickness of the strip. In a specific implementation, an automated program module for virtual correction compensation of thickness gauge data can be added. After receiving the data corrected by virtual compensation, the AGC thickness control system identifies the thickness deviation from the target value, and then adjusts the mill roll gap to achieve the ideal thickness requirement. Furthermore, the inventors also added this function operation window to the operation interface, and the correction compensation amount can be modified and adjusted at any time according to the actual thinning amount required, ultimately achieving thinning or thickness increase.

[0052] The technical solution of the present invention is described in detail below through specific embodiments.

[0053] In one aspect, an embodiment of the present invention provides a method for improving the thickness control accuracy of hot rolled strip steel, comprising:

[0054] Step S100, pre-dividing the steel strip into three steel strip sections, namely, a head section, a middle section and a tail section, and setting preset thickness compensation values ​​for the head section, the middle section and the tail section respectively;

[0055] Step S101, according to the strip portion currently being rolled by the roller, the strip thickness data measured by the thickness gauge of the finishing mill is corrected using a preset thickness compensation value corresponding to the strip portion to obtain corrected strip thickness data; the strip portion includes a head section, a middle section and a tail section of the strip;

[0056] Step S102, inputting the corrected strip thickness data into the AGC thickness control system to control the roll gap of the rolling mill in real time to control the strip thickness at the strip portion.

[0057] In some embodiments, in batch production, the temperature distribution of different steel strips is uneven and has basically the same regularity. By correcting the strip thickness data measured by the finishing mill thickness gauge according to the relative position of the strip and the finishing mill thickness gauge, different roll gaps can be used for different position ranges of the strip according to the distribution of the heating temperature of the strip on the strip, thereby improving the uniformity of the strip thickness. For example, the head of the strip is affected by environmental factors such as uneven heating temperature, water leakage at the low-speed bite of the rolling mill, and the thickness is thicker or thinner at a fixed position. Thickness compensation can be made in a targeted manner at different positions of the strip. In a specific production process, the strip can be divided into a head section, a middle section, and a tail section according to the specification parameters of the strip, and the strip thickness data measured by the finishing mill thickness gauge is corrected according to the strip position currently being rolled by the roller to obtain the corrected strip thickness data, and the corrected strip thickness data is input into the AGC thickness control system to control the roll gap of the roller in real time to control the strip thickness at the strip portion. In some embodiments, a strategy of differentially controlling the thickness of the head and tail parts and the middle part of the strip is adopted. Since there are more environmental variables at the head and tail parts of the strip (i.e., the head section and the tail section), they are controlled according to the original target thickness, while the thickness control of the middle part of the strip (i.e., the middle section) is relatively uniform and stable. In this process, the negative difference in strip thickness is increased, and the thickness of the middle part of the strip is controlled to be thinner, so as to increase the rolling length of the entire strip, and ultimately achieve the purpose of improving the utilization yield.

[0058] The embodiments of the present invention have the following technical effects: targeted thickness compensation for different positions of the strip can improve the uniformity of the strip thickness, and can more accurately control the thickness of the strip within a specified range; on the basis of the existing finishing mill thickness gauge and AGC system, only the strip thickness data measured by the finishing mill thickness gauge is corrected, thereby affecting the output of the AGC system to achieve the purpose of accurately controlling the strip thickness, thereby achieving the effect of accurately controlling the strip thickness with minimal changes.

[0059] Further, the strip thickness data measured by the thickness gauge of the finishing mill is corrected according to the strip portion currently being rolled by the roller using a preset thickness compensation value corresponding to the strip portion to obtain the corrected strip thickness data, including:

[0060] If the part of the strip currently being rolled is the middle section, the preset negative difference in strip thickness is added as the thickness compensation value to the strip thickness data measured by the finishing mill thickness gauge to obtain the corrected strip thickness data; wherein the negative difference in strip thickness is less than 0.

[0061] In some embodiments, since there are more environmental variables in the head section and / or tail section of the strip, the strip thickness data measured by the finishing mill thickness gauge may be controlled according to the original target thickness, that is, no correction is made to the strip thickness data measured by the finishing mill thickness gauge, or the strip thickness data measured by the finishing mill thickness gauge may be corrected more finely according to the temperature change distribution law of the head section and / or tail section. The thickness control of the middle section of the strip is relatively uniform and stable. In this process, the negative difference in strip thickness is increased, and the thickness of the middle part of the strip is controlled to be thinner, so as to increase the rolling length of the entire strip, and ultimately achieve the purpose of improving the utilization yield.

[0062] Further, the strip thickness data measured by the thickness gauge of the finishing mill is corrected according to the strip portion currently being rolled by the roller using a preset thickness compensation value corresponding to the strip portion to obtain the corrected strip thickness data, including:

[0063] If the portion of the strip currently being rolled is the head section, according to the offset distance of the position currently being rolled on the strip relative to the head end of the strip, a strip thickness compensation value corresponding to the offset distance is selected from a preset strip thickness compensation value table, and the strip thickness compensation value is accumulated to the strip thickness data measured by the finishing mill thickness gauge to obtain the corrected strip thickness data;

[0064] Wherein, the strip thickness compensation value table includes at least one set of offset distances and corresponding strip thickness compensation values.

[0065] In some embodiments, by selecting a strip thickness compensation value corresponding to the offset distance of the position currently being rolled on the strip relative to the head end of the strip from a preset strip thickness compensation value table, and accumulating the strip thickness compensation value to the strip thickness data measured by the thickness gauge of the finishing mill to obtain the corrected strip thickness data, regular thickness fluctuation problems can be eliminated in a targeted manner. For example, the strip head is affected by environmental factors such as uneven heating temperature, water leakage at the low-speed bite of the rolling mill, and the thickness is regularly too thick or too thin at a fixed position. In some embodiments, a strip thickness compensation value table as shown in Table 1 can be pre-set, and a thickness difference correction function is performed every 20 meters starting from the head end of the strip, that is, a corresponding thickness compensation value is determined every 20 meters, so as to achieve multiple thickness corrections for one roll of steel and effectively eliminate regular thickness being too thin or too thick. For example, in a batch production, a strip thickness compensation value table as shown in Table 1 can be established by collecting the corresponding relationship between the thickness deviation of the strip and the offset distance during the trial production; in Table 1, the thickness deviation of the steel coil at the offset distance of 20 meters is -80 microns, so the thickness compensation value at the offset distance of 20 meters is set to 80 microns.

[0066]

[0067] Table 1 Strip steel thickness compensation value table (where um is the unit, representing micrometers)

[0068] Further, the strip thickness data measured by the thickness gauge of the finishing mill is corrected according to the strip portion currently being rolled by the roller using a preset thickness compensation value corresponding to the strip portion to obtain the corrected strip thickness data, including:

[0069] If the portion of the steel strip currently being rolled is the tail section, the thickness compensation value is set to 0, and the steel strip thickness data measured by the finishing mill thickness gauge is used as the corrected steel strip thickness data.

[0070] In some embodiments, since there are many environmental variables in the tail section of the steel strip, the original target thickness control may be used, that is, the strip thickness data measured by the thickness gauge of the finishing mill is not corrected.

[0071] Further, if the thickness of the steel strip is greater than or equal to a preset steel strip thickness, the head section is a portion of the steel strip of a first preset length starting from the head end;

[0072] If the thickness of the steel strip is less than the preset steel strip thickness, the head section is a portion of the steel strip of a second preset length starting from the head end;

[0073] Wherein, the first preset length is smaller than the second preset length;

[0074] The second preset length is the distance between the head end of the steel strip and the thickness gauge of the finishing mill when the head end of the steel strip enters the coiler to establish tension.

[0075] In some embodiments, considering that the head shape of thin-gauge strip is unstable, a large adjustment of the roll gap will cause the shape to change. Therefore, according to the on-site conditions of hot rolling, the range of the head section of the strip can be determined according to the relationship between the thickness of the strip and the preset strip thickness. If the thickness of the strip is greater than or equal to the preset strip thickness (for example, for strips with a thickness of ≥2.5 mm), the head section is a portion of the strip with a first preset length starting from the head end of the strip. Preferably, the first preset length is about 50 meters; if the thickness of the strip is less than the preset strip thickness, the head section is a portion of the strip with a second preset length starting from the head end of the strip; the second preset length is the distance between the head end of the strip and the thickness gauge of the finishing mill when the head of the strip enters the coiler to establish tension. Preferably, the second preset length is 100 meters; for thin-gauge strips (i.e., the thickness of the strip is less than the preset strip thickness), the roll gap adjustment is performed after the shape is stable after coiling and tensioning, which can effectively avoid adverse changes in the shape caused by the roll gap adjustment.

[0076] According to the predetermined head section range, the head section can be controlled according to the original target thickness according to the needs of the hot rolling site, or the strip thickness data measured by the finishing mill thickness gauge can be corrected more finely according to the temperature change distribution law of the head section; further, the strip thickness data can be corrected for the middle section and tail section after the head section according to the needs of the hot rolling site.

[0077] The embodiments of the present invention have the following technical effects: according to the thickness of the strip, the range of the head section is reasonably determined, and the undesirable changes in the plate shape caused by the adjustment of the roll gap are effectively avoided.

[0078] Furthermore, the tail section is the distance from the tail end of the steel strip to the thickness gauge of the finishing mill when the tail end of the steel strip leaves the first finishing mill.

[0079] In some embodiments, the distance from the tail end of the strip to the thickness gauge of the finishing mill when the tail end of the strip leaves the first finishing mill is used as the range of the tail section of the strip. Since the tail of the strip is prone to swing after leaving the finishing mill, the tail is exposed to more environmental variables, and it is necessary to control the tail section according to the original target thickness based on the on-site conditions of the hot rolling, or the strip thickness data measured by the thickness gauge of the finishing mill can be corrected more finely based on the temperature change distribution law of the tail section.

[0080] The embodiments of the present invention have the following technical effects: the tail section of the steel strip is determined by fully considering the different effects of environmental variables on different parts of the steel strip, so that a suitable strip thickness data correction method can be applied to the tail section in a targeted manner, thereby improving the precise thickness control of the entire steel strip.

[0081] The middle section is a portion of the steel strip between the head section and the tail section.

[0082] In some embodiments, the range of the head section of the strip is determined according to the relationship between the strip thickness and the preset strip thickness, and the distance from the tail end of the strip to the thickness gauge of the finishing mill when the tail end of the strip leaves the first finishing mill is taken as the range of the tail section of the strip, thereby indirectly determining the range of the middle section of the strip; if the strip thickness is greater than or equal to the preset strip thickness (for example, for strips with a strip thickness ≥ 2.5 mm), the thickness virtual compensation function is used when the strip head exits the finishing mill thickness gauge for a first preset length (preferably, the first preset length is about 50 meters) (that is, the strip thickness data output by the finishing mill thickness gauge is corrected, and the corrected strip thickness data is input into the AGC thickness control system to control the rollers in real time) The roll gap is used to control the strip thickness), and the strip thickness is adjusted after the first preset length (for example, 50 meters). This function is canceled when the tail of the strip reaches the finishing mill F1 (i.e., the first finishing mill); if the strip thickness is less than the preset strip thickness (for example, for strips with a thickness of <2.5 mm), the thickness virtual compensation function is used after the strip head enters the coiler to establish tension (for example, in some embodiments, the strip head is about 100 meters away from the thickness gauge of the finishing mill), and the strip thickness is adjusted thereafter. This function is canceled when the tail of the strip reaches the finishing mill F1, mainly considering that the plate shape of the thin-gauge head is unstable and a large adjustment of the roll gap will cause the plate shape to change. The roll gap adjustment is performed after the plate shape is stable after the coiling is established.

[0083] The embodiments of the present invention have the following technical effects: the starting position for thickness compensation is determined according to the thickness of the strip, ensuring that thickness compensation is performed within a position range where the strip shape is stable, so as to better improve the strip yield while ensuring that the strip thickness meets the delivery standards.

[0084] Furthermore, the method further comprises: setting an operation interface;

[0085] The operation interface is used to set the thickness compensation value, provide first mode selection and second mode selection functions, and automatic selection and manual selection functions;

[0086] The first mode is used to determine the head section, middle section and tail section of the strip when the thickness of the strip is greater than or equal to the preset strip thickness, and to correct the strip thickness data measured by the thickness gauge of the finishing mill according to the strip section currently being rolled by the roller using the preset thickness compensation value corresponding to the strip section to obtain the corrected strip thickness data;

[0087] The second mode is used to determine the head section, middle section and tail section of the strip when the thickness of the strip is less than the preset strip thickness, and to correct the strip thickness data measured by the thickness gauge of the finishing mill according to the strip section currently being rolled by the roller using the preset thickness compensation value corresponding to the strip section to obtain the corrected strip thickness data;

[0088] When the automatic selection function is selected, the first mode or the second mode is automatically selected according to the relationship between the thickness of the steel strip and the preset thickness of the steel strip;

[0089] When the manual selection function is selected, the first mode or the second mode is manually selected.

[0090] In some embodiments, the operator can set a preset thickness compensation correction value through the operation interface; there are two modes of automatic selection and manual selection in the operation interface. When automatic is selected, the program will automatically adopt the first mode for the thickness of the strip steel ≥ the preset strip steel thickness (for example, 2.5mm specification), and the program will automatically adopt the second mode for the thickness < the preset strip steel thickness. If it is manual, it will be executed according to the actual selection. If none of them is selected, this function will not be used. By providing an operation interface, it is convenient for operators to control the assembly line in time, make timely adjustments to the assembly line according to real-time conditions, and improve the safety and control efficiency of the assembly line.

[0091] Furthermore, the method comprises:

[0092] The first mode: if the strip thickness is greater than or equal to the preset strip thickness, the thickness virtual compensation function is used at the first preset length of the thickness gauge of the finishing mill at the head end of the strip, and the thickness of the strip after the first preset length is adjusted, and the thickness virtual compensation function is stopped when the tail of the strip reaches the first finishing mill;

[0093] The second mode: if the strip thickness is less than the preset strip thickness, the thickness virtual compensation function is used after the strip head enters the coiler to establish tension, and the strip thickness is adjusted thereafter. When the strip tail reaches the first finishing mill, the thickness virtual compensation function is stopped to wait for the strip head to stabilize in shape after coiling and tensioning before adjusting the roll gap.

[0094] Wherein: the thickness virtual compensation function is used to correct the strip thickness data output by the finishing mill thickness gauge using a preset thickness compensation value, and input the corrected strip thickness data to the AGC thickness control system to control the roll gap of the rolling mill in real time to control the strip thickness;

[0095] The method further comprises: setting an operation interface;

[0096] The operation interface includes: a thickness compensation value setting function, a first mode selection function and a second mode selection function, and an automatic selection function and a manual selection function;

[0097] The automatic selection function is used to automatically adopt the first mode for the strip steel whose thickness is greater than or equal to the preset strip steel thickness, and automatically adopt the second mode for the strip steel whose thickness is less than the preset strip steel thickness when the automatic selection is selected;

[0098] The manual selection function is used to manually select the first mode or the second mode when the automatic selection is selected;

[0099] The method further comprises: for the head section, according to the offset distance of the position currently being rolled on the strip relative to the head end of the strip, selecting a strip thickness compensation value corresponding to the offset distance from a preset strip thickness compensation value table, and accumulating the strip thickness compensation value to the strip thickness data measured by the finishing mill thickness gauge to obtain the corrected strip thickness data;

[0100] Wherein, the strip thickness compensation value table includes at least one set of offset distances and corresponding strip thickness compensation values.

[0101] The embodiments of the present invention can be understood based on the aforementioned embodiments, and will not be described in detail here.

[0102] The embodiment of the present invention has the following technical effects: by adding the AGC thickness compensation correction function of the strip, the thickness fluctuation of the hot-rolled strip after the strip is threaded and stretched is small, and the middle thickness is controlled to be thinned, so as to effectively improve the utilization rate of the strip and improve user satisfaction. At the same time, the utilization efficiency of the strip is improved, and steel resources are saved under the premise of meeting the requirements. For example, a total of 150 meters of the slightly thin strip with the head and tail removed is not precisely controlled for thickness, and the controllable distance of the remaining middle part reaches about 800 meters, and the controllable length is as high as more than 80%. In particular, the effect is more significant for extremely thin specifications such as 1.6 mm, 1.8 mm, and 2.0 mm. Taking a steel plate with a nominal thickness of 1.6 mm as an example, the actual controlled thickness is 1.48 mm, and the negative tolerance is -0.12 mm. After this function is put into use, the negative tolerance can reach -0.14 mm, and the improvement is: -0.2 / -0.12=16.7%. Furthermore, through multi-stage thickness compensation adjustment of the strip, the regular thickness fluctuation at a fixed position of the strip is significantly eliminated, thereby reducing the regular thickness fluctuation.

[0103] Furthermore, the method for improving the thickness control accuracy of hot-rolled strip is specifically as follows: for strips with a thickness greater than or equal to 2.5 mm, a thickness virtual compensation function is used at a thickness gauge of 50 meters at the head end of the strip out of the finishing mill, and the thickness of the strip after 50 meters is adjusted, and the thickness virtual compensation function is stopped when the tail of the strip reaches the finishing rolling F1.

[0104] In some embodiments, the length of the head section of the strip is determined according to the thickness of the strip. For strips with a thickness greater than or equal to 2.5 mm, the first 50 meters of the strip usually have obvious jitters during movement, while the part after 50 meters is relatively stable. A strategy is adopted to control the thickness of the head, tail and middle parts of the strip differently. Since there are more environmental variables at the head and tail parts of the strip (i.e., the head section and the tail section), the original target thickness is controlled, while the thickness of the middle part of the strip (i.e., the middle section) is relatively uniform and stable. In this process, the negative difference in strip thickness is increased, and the thickness of the middle part of the strip is controlled to be thinner, so as to increase the rolling length of the entire strip, and ultimately achieve the purpose of improving the utilization yield.

[0105] Furthermore, the method for improving the thickness control accuracy of hot-rolled strip is specifically as follows: for strips with a thickness less than 2.5 mm, the thickness virtual compensation function is used after the strip head end leaves the finishing mill thickness gauge for a length greater than or equal to 100 meters and the strip head end enters the coiler to establish tension, and the thickness of the strip is adjusted thereafter, and the thickness virtual compensation function is stopped when the tail of the strip reaches the finishing rolling F1.

[0106] In some embodiments, the length of the head section of the strip is determined according to the thickness of the strip. For strips with a thickness less than 2.5 mm, the strip is relatively thin and is easily offset or deformed during movement. After the strip enters the coiler and is stretched, the strip can maintain stable movement. A strategy of differentially controlling the thickness of the head and tail parts and the middle part of the strip is adopted. Since there are more environmental variables at the head and tail parts of the strip (i.e., the head section and the tail section), the original target thickness is controlled, while the thickness of the middle part of the strip (i.e., the middle section) is relatively uniform and stable. In this process, the negative difference in strip thickness is increased, and the thickness of the middle part of the strip is controlled to be thinner, so as to increase the rolling length of the entire strip, and ultimately achieve the purpose of improving the utilization yield.

[0107] The above technical solution of the embodiment of the present invention is described in detail below in conjunction with specific application examples. For technical details not introduced during the implementation process, please refer to the relevant description in the previous text.

[0108] An embodiment of the present invention provides a method for compensating thickness control by using a finishing rolling AGC thickness control system. The method adopts a strategy of differentially controlling the thickness of the head and tail parts and the middle part of the strip. Since there are more environmental variables in the head and tail parts of the strip, they are controlled according to the original target thickness, while the thickness control of the middle part of the strip is relatively uniform and stable. In this process, the negative difference in the thickness of the strip is increased, and the thickness of the middle part of the strip is controlled to be thinner, so as to increase the rolling length of the entire strip, and ultimately achieve the purpose of improving the utilization yield.

[0109] Taking into account the large fluctuation of thickness at the head and tail of the strip, and the fact that the thickness of the extremely thin gauge is reduced as the thickness is thinned, the threading of the head and the throwing of the tail of the finishing rolling are greatly affected, which is easy to cause rolling breakage, tail swinging and even rolling failure. Therefore, breaking the conventional thinking, the single-mode thickness control of the conventional whole coil is changed to three-stage two-mode thickness control, and the target thickness is reduced in the middle part of the strip. While avoiding the thickness of the head and tail exceeding the range, the rolling length is extended and the utilization rate is improved.

[0110] The secondary model control does not intervene in the head thickness, and only the AGC control strategy needs to be optimized. The AGC thickness control system is based on the target thickness issued by the secondary level, and compensates and adjusts the mill roll gap according to the thickness deviation detected by the thickness gauge to achieve strip thickness control. Figure 4 As shown, the embodiment of the present invention creatively performs compensation and correction on the thickness difference data fed back from the thickness gauge and then sends it to the AGC control system, thereby indirectly changing the target thickness and realizing the separate control of the middle thickness of the strip.

[0111] The following is a specific example for explanation:

[0112] By adding an automated program module for virtual correction compensation of thickness gauge data, the AGC thickness control system can identify the thickness deviation from the target value after receiving the virtual compensation corrected data, and then adjust the mill roll gap to achieve the ideal thickness requirement. This function operation window is added to the operation interface, and the correction compensation amount can be modified and adjusted at any time according to the actual thinning amount required, ultimately achieving thinning or thickness increase.

[0113] According to the on-site conditions of hot rolling, the embodiment of the present invention designs two control modes. The first mode is for strip steel with a thickness ≥ 2.5 mm. The thickness virtual compensation function is used when the head of the strip is about 50 meters (equivalent to the first preset length) out of the thickness gauge of the finishing mill, and the thickness of the strip is adjusted after 50 meters (equivalent to the first preset length). This function is canceled when the tail of the strip reaches the finishing mill F1 (equivalent to the first finishing mill); the second mode is for strip steel with a thickness < 2.5 mm. The thickness virtual compensation function is used after the head of the strip enters the coiler to establish tension, that is, the head of the strip is about 100 meters (equivalent to the second preset length) out of the thickness gauge of the finishing mill, and the thickness of the strip is adjusted thereafter. This function is canceled when the tail of the strip reaches the finishing mill F1. This mode mainly considers that the plate shape of the thin head is unstable, and a large adjustment of the roll gap will cause the plate shape to change. The roll gap adjustment is performed after the plate shape is stable after the coiling and tension establishment. There are two modes in the operation interface: automatic selection and manual selection. When automatic is selected, the first mode will be automatically adopted for specifications with thickness ≥ 2.5 mm, and the second mode will be automatically adopted for specifications with thickness < 2.5 mm. If manual is selected, it will be executed according to the actual selection. If neither is selected, this function will not be used.

[0114] The embodiment of the present invention further provides a method for eliminating regular thickness fluctuation problems in a targeted manner. For example, if the head of the strip is affected by environmental factors such as uneven heating temperature, water leakage at the low-speed bite of the rolling mill, etc., and the thickness is regularly thicker or thinner at a fixed position, the present invention can be used for extended application to make targeted thickness compensation. The specific implementation is to add multiple thickness difference corrections to the operation interface as shown in Table 1, and perform a thickness difference correction function every 20 meters starting from the head of the strip, so as to achieve multiple thickness corrections for one coil of steel and effectively eliminate regular thin or thick thickness.

[0115] The embodiments of the present invention have the following technical effects:

[0116] Without making any changes to the core control systems such as the secondary model control system and the AGC control system, the purpose of changing the thickness control target is achieved indirectly by only making virtual compensation corrections to the thickness difference data of the thickness gauge and then sending it to the AGC. This is safe and simple to implement.

[0117] The thickness targets of the head and tail parts and the middle part of the hot-rolled strip are controlled separately, and the characteristics of small thickness fluctuation and stable plate shape control in the middle part of the strip are fully utilized to control the thinning of the middle part of the strip, thereby improving the material utilization yield.

[0118] By adding the AGC thickness compensation correction function for the strip, and utilizing the small thickness fluctuation of the hot-rolled strip after strip threading and tensioning, the intermediate thickness is controlled to be thinned, effectively improving the strip yield rate and user satisfaction, while also improving the strip utilization efficiency, saving steel resources while meeting the requirements.

[0119] For the steel coils using the function of the present invention, the generally slightly thinner specifications, excluding the head and tail, a total of 150 meters cannot be controlled, and the controllable distance of the middle part reaches about 800 meters, and the controllable length is as high as more than 80%. Especially for extremely thin specifications such as 1.6mm, 1.8mm, 2.0mm, the effect is more significant. Taking the steel plate with a nominal thickness of 1.6mm as an example, the actual controlled thickness is 1.48mm, and the negative tolerance is -0.12mm. After using this function, the negative tolerance can reach -0.14mm, and the improvement is: -0.2 / -0.12=16.7%.

[0120] Through multi-stage strip thickness compensation adjustment, the regular thickness fluctuation at a fixed position of the strip is significantly eliminated, thereby reducing the regular thickness fluctuation.

[0121] The operation window of AGC thickness compensation function is added to the operation interface, and the thickness compensation amount can be adjusted at any time according to actual needs, which has wide adaptability. At the same time, the first mode and the second mode are developed, which can be used for different thickness specifications to avoid the fluctuation of the head plate shape of thin specifications and maximize the application length for thick specifications, and can be selected automatically and manually.

[0122] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present disclosure. The attached method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0123] In the above detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly stated in each claim. On the contrary, as reflected in the appended claims, the invention is in a state of having less than all the features of the disclosed individual embodiments. Therefore, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0124] The disclosed embodiments are described above to enable any person skilled in the art to implement or use the present invention. Various modifications of these embodiments are obvious to those skilled in the art, and the general principles defined herein may also be applied to other embodiments without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0125] The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it should be recognized by those skilled in the art that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", as explained by "including:" used as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to mean "non-exclusive or".

[0126] Those skilled in the art may also understand that the various illustrative logical blocks, units, and steps listed in the embodiments of the present invention may be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly demonstrate the interchangeability of hardware and software, the various illustrative components, units, and steps described above have generally described their functions. Whether such functions are implemented by hardware or software depends on the specific application and the design requirements of the entire system. Those skilled in the art may use various methods to implement the described functions for each specific application, but such implementation should not be understood as exceeding the scope of protection of the embodiments of the present invention.

[0127] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for improving the thickness control accuracy of hot rolled strip steel, characterized in that: include: The strip steel is pre-divided into three strip steel sections, namely, a head section, a middle section and a tail section, and preset thickness compensation values ​​are respectively set for the head section, the middle section and the tail section; According to the strip portion currently being rolled by the roller, the strip thickness data measured by the thickness gauge of the finishing mill is corrected using a preset thickness compensation value corresponding to the strip portion to obtain corrected strip thickness data; Inputting the corrected strip thickness data into the AGC thickness control system to control the roll gap of the rolls in real time to control the strip thickness at the strip portion; The method of correcting the strip thickness data measured by the thickness gauge of the finishing mill according to the strip portion currently being rolled by the roller using a preset thickness compensation value corresponding to the strip portion to obtain the corrected strip thickness data comprises: If the part of the strip currently being rolled is the middle section, the preset negative difference in strip thickness is added as the thickness compensation value to the strip thickness data measured by the finishing mill thickness gauge to obtain the corrected strip thickness data; wherein the negative difference in strip thickness is less than 0.

2. The method for improving the thickness control accuracy of hot rolled strip according to claim 1, characterized in that: The method of correcting the strip thickness data measured by the thickness gauge of the finishing mill according to the strip portion currently being rolled by the roller using a preset thickness compensation value corresponding to the strip portion to obtain the corrected strip thickness data comprises: If the portion of the strip currently being rolled is the head section, according to the offset distance of the position currently being rolled on the strip relative to the head end of the strip, a strip thickness compensation value corresponding to the offset distance is selected from a preset strip thickness compensation value table, and the strip thickness compensation value is accumulated to the strip thickness data measured by the finishing mill thickness gauge to obtain the corrected strip thickness data; Wherein, the strip thickness compensation value table includes at least one set of offset distances and corresponding strip thickness compensation values.

3. The method for improving the thickness control accuracy of hot rolled strip according to claim 1, characterized in that: The method of correcting the strip thickness data measured by the thickness gauge of the finishing mill according to the strip portion currently being rolled by the roller using a preset thickness compensation value corresponding to the strip portion to obtain the corrected strip thickness data comprises: If the portion of the steel strip currently being rolled is the tail section, the thickness compensation value is set to 0, and the steel strip thickness data measured by the finishing mill thickness gauge is used as the corrected steel strip thickness data.

4. The method for improving the thickness control accuracy of hot rolled strip according to claim 1, characterized in that: If the thickness of the steel strip is greater than or equal to a preset steel strip thickness, the head section is a portion of the steel strip with a first preset length starting from the head end; If the thickness of the steel strip is less than the preset steel strip thickness, the head section is a portion of the steel strip of a second preset length starting from the head end; Wherein, the first preset length is smaller than the second preset length; The second preset length is the distance between the head end of the steel strip and the thickness gauge of the finishing mill when the head end of the steel strip enters the coiler to establish tension.

5. The method for improving the thickness control accuracy of hot rolled strip according to claim 4, characterized in that: The tail section is the distance from the tail end of the steel strip to the thickness gauge of the finishing mill when the tail end of the steel strip leaves the first finishing mill.

6. The method for improving the thickness control accuracy of hot rolled strip according to claim 5, characterized in that: Also includes: Set up the operation interface; The operation interface is used to set the thickness compensation value, provide first mode selection and second mode selection functions, and automatic selection and manual selection functions; The first mode is used to determine the head section, middle section and tail section of the strip when the thickness of the strip is greater than or equal to the preset strip thickness, and to correct the strip thickness data measured by the thickness gauge of the finishing mill according to the strip section currently being rolled by the roller using the preset thickness compensation value corresponding to the strip section to obtain the corrected strip thickness data; The second mode is used to determine the head section, middle section and tail section of the strip when the thickness of the strip is less than the preset strip thickness, and to correct the strip thickness data measured by the thickness gauge of the finishing mill according to the strip section currently being rolled by the roller using the preset thickness compensation value corresponding to the strip section to obtain the corrected strip thickness data; When the automatic selection function is selected, the first mode or the second mode is automatically selected according to the relationship between the thickness of the steel strip and the preset thickness of the steel strip; When the manual selection function is selected, the first mode or the second mode is manually selected.

7. The method for improving the thickness control accuracy of hot rolled strip according to claim 1, characterized in that: include: The first mode: if the strip thickness is greater than or equal to the preset strip thickness, the thickness virtual compensation function is used at the first preset length of the thickness gauge of the finishing mill at the head end of the strip, and the thickness of the strip after the first preset length is adjusted, and the thickness virtual compensation function is stopped when the tail of the strip reaches the first finishing mill; The second mode: if the strip thickness is less than the preset strip thickness, the thickness virtual compensation function is used after the strip head enters the coiler to establish tension, and the strip thickness is adjusted thereafter. When the strip tail reaches the first finishing mill, the thickness virtual compensation function is stopped to wait for the strip head to stabilize in shape after coiling and tensioning before adjusting the roll gap. The method further comprises: setting an operation interface; The operation interface includes: a thickness compensation value setting function, a first mode selection function and a second mode selection function, and an automatic selection function and a manual selection function; The automatic selection function is used to automatically adopt the first mode for the strip steel whose thickness is greater than or equal to the preset strip steel thickness, and automatically adopt the second mode for the strip steel whose thickness is less than the preset strip steel thickness when the automatic selection is selected; The manual selection function is used to manually select the first mode or the second mode when the automatic selection is selected; The method further comprises: for the head section, according to the offset distance of the position currently being rolled on the strip relative to the head end of the strip, selecting a strip thickness compensation value corresponding to the offset distance from a preset strip thickness compensation value table, and accumulating the strip thickness compensation value to the strip thickness data measured by the finishing mill thickness gauge to obtain the corrected strip thickness data; Wherein, the strip thickness compensation value table includes at least one set of offset distances and corresponding strip thickness compensation values.

8. The method for improving the thickness control accuracy of hot rolled strip according to claim 1, characterized in that: The method for improving the thickness control accuracy of hot-rolled strip steel is specifically as follows: for strip steel with a thickness greater than or equal to 2.5 mm, a thickness virtual compensation function is used at a thickness gauge of 50 meters at the head end of the strip steel out of the finishing mill, and the thickness of the strip steel after 50 meters is adjusted, and the thickness virtual compensation function is stopped when the tail end of the strip steel reaches the finishing rolling F1.

9. The method for improving the thickness control accuracy of hot rolled strip according to claim 1, characterized in that: The method for improving the thickness control accuracy of hot-rolled strip steel is specifically as follows: for strip steel with a thickness less than 2.5 mm, a thickness virtual compensation function is used after the strip head end leaves the finishing mill thickness gauge for a length greater than or equal to 100 meters and the strip head end enters the coiler to establish tension, and the thickness of the strip is adjusted thereafter, and the thickness virtual compensation function is stopped when the tail of the strip reaches the finishing rolling F1.

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