Pickling withdrawal and straightening control method and pickling withdrawal and straightening control system

Abstract

The invention discloses a pickling withdrawal and straightening control method, which is applied to a pickling production line and comprises the following steps: acquiring a target pickling strip steel type, a withdrawal and straightening elongation set value of a pickling withdrawal and straightening machine and a pickling speed; according to the target strip steel type, a target pickling thickness reduction coefficient is determined; according to the target pickling thickness reduction coefficient, the set value of the withdrawal and straightening elongation and the pickling speed, the actual value of the withdrawal and straightening elongation is determined; and controlling the production operation of the pickling withdrawal and straightening machine according to the actual value of the withdrawal and straightening elongation. According to the technical scheme of acid pickling and tension leveling linkage control, the actual tension leveling elongation value is dynamically adjusted in a linkage mode according to the actual operation condition of the acid pickling unit, the defects of over-acid pickling, serious thickness reduction and the like of the strip steel when the acid pickling unit operates at the abnormal speed are overcome, and the surface quality and the size precision of the strip steel after acid pickling are improved.

Description

Technical Field

[0001] The present application relates to the technical field of cold rolling pickling, and in particular to a pickling straightening control method. Background Art

[0002] In the pickling cold rolling production line, the pickling process uses acid to remove the iron oxide scale on the surface of the hot-rolled strip, so as to obtain a cold-rolled product with good surface quality. Due to some factors, such as sudden unit failure, or production rhythm problems such as incoming material connection, the strip will inevitably run at an abnormally low speed in the pickling tank, which will extend the pickling time and produce over-pickling defects. Over-pickling not only affects the pickling quality of the strip, but also causes serious thickness thinning of the strip after pickling, and further affects the reduction and dimensional accuracy of the subsequent cold-rolled hard coil, resulting in a decrease in the surface quality of the product. Therefore, how to control the surface quality and dimensional accuracy of the strip during abnormal low-speed pickling is a problem that needs to be solved urgently. Summary of the invention

[0003] The invention provides a pickling and straightening control method to solve or partially solve the technical problem of poor surface quality and dimensional accuracy of strip steel during abnormal low-speed pickling.

[0004] In order to solve the above technical problems, the present invention provides a pickling and straightening control method, which is applied to a pickling production line, comprising:

[0005] S1: Obtain the target strip steel grade for pickling, the set value of the pickling and straightening elongation of the pickling and straightening machine, and the pickling speed;

[0006] S2: Determine the target pickling thickness reduction coefficient according to the target strip steel grade;

[0007] S3: confirm the actual value of the tensile elongation according to the target pickling thickness reduction coefficient, the set value of the tensile elongation and the pickling speed;

[0008] S4: Control the production operation of the pickling and straightening machine according to the actual value of the straightening elongation.

[0009] Furthermore, according to the target strip steel grade, the target pickling thickness reduction factor is determined, including:

[0010] According to the target strip steel grade, the target pickling thickness reduction coefficient is confirmed from the mapping relationship, and the mapping relationship is the corresponding relationship between the steel grade and the pickling thickness reduction coefficient.

[0011] Furthermore, the method for establishing the mapping relationship includes:

[0012] S21: obtaining the steel type of the strip steel;

[0013] S22: Determine the set area of ​​the steel strip and the set position in the set area, and obtain the target thickness value d after pickling corresponding to the set position 1 ;

[0014] S23: Controlling a set area of ​​the strip to be pickled in an acid tank;

[0015] S24: Obtain the actual thickness value d corresponding to the set position after pickling 2 ;

[0016] S25: Determine the first thickness deviation Δd corresponding to the set position 1 =d 2 -d 1 ;

[0017] S26: According to the set position and the Δd corresponding to the set position 1 , establish the pickling thickness reduction model and confirm the pickling thickness reduction coefficient;

[0018] S27: Pair the steel type of the strip steel and the pickling thickness reduction coefficient to obtain a mapping relationship.

[0019] Further, the set area includes a first endpoint located at the acid tank outlet and a second endpoint located at the acid tank inlet;

[0020] Controlling the set areas of the strip being pickled in the pickling tank includes:

[0021] When the first end point is discharged from the acid tank, the pickling speed of the strip is controlled to be 2-8 m / min;

[0022] When exiting the acid tank at the second end point, the pickling speed of the strip is controlled to be above 20m / min.

[0023] As in the above technical solution, the pickling thickness reduction coefficient ranges from 1.5 to 3.5.

[0024] As in the above technical solution, the pickling thickness reduction model takes the distance L from the set position to the strip head as the independent variable, and the Δd corresponding to the set position 1 The linear fitting model established for the dependent variable is:

[0025] Δd 1 =C 0 +C 1 L

[0026] Among them, the unit of Δd is μm, the unit of L is m, and the unit of C 0 is a constant, C 1 is the pickling thickness reduction coefficient.

[0027] As in the above technical solution, according to the target pickling thickness reduction coefficient, the set value of the straightening elongation and the pickling speed, the actual value of the straightening elongation is confirmed, including:

[0028] S31: Determine whether the pickling speed is less than a first preset value, if so, execute S32, if not, execute S37;

[0029] S32: Confirm the speed influence coefficient K 1 ;

[0030] S33: Confirm that the calculated value of the tensile elongation = the set value of the tensile elongation - C 1 *K 1 , where C 1 is the target pickling thickness reduction factor;

[0031] S34: Determine whether the calculated value of the tensile elongation is less than a second preset value. If so, execute S35; if not, execute S36;

[0032] S35: confirming that the actual value of the tensile elongation is equal to the second preset value;

[0033] S36: confirm that the actual value of the straightening elongation is equal to the calculated value of the straightening elongation;

[0034] S37: Confirm that the actual value of the straightening elongation is equal to the set value of the straightening elongation.

[0035] Furthermore, the first preset value is 20 m / min, and the second preset value is 0.5%.

[0036] Further, confirm the speed influence coefficient K 1 ,include:

[0037] S321: Obtain the target thickness value d of the strip after pickling 3 ;

[0038] S322: Confirm K 1 The initial value K 0 , K 0 ∈[0.3%,0.7%];

[0039] S323: Obtain the actual thickness value d of the strip after pickling 4 ;

[0040] S324: Confirm the second thickness deviation Δd 2 =d 4 -d 3 ;

[0041] S325: Determine Δd 2 Is it within the range of [-50μm, 50μm]? If yes, execute S326; if not, execute S327;

[0042] S326: Confirm K 1 =K 0 ;

[0043] S327: If Δd 2 <-50μm, confirm K 1 =K 0 +0.1% and then return to S323; if Δd 2 >50μm, confirm K 1 =K 0 -0.1% and then returns to S323.

[0044] The present invention also provides a pickling and straightening control system, which is applied to a pickling production line, comprising:

[0045] An acquisition module is used to obtain the target strip steel type for pickling, the set value of the pickling and straightening elongation of the pickling and straightening machine, and the pickling speed;

[0046] The first confirmation module is used to confirm the target pickling thickness reduction coefficient according to the target strip steel grade;

[0047] The second confirmation module is used to confirm the actual value of the tensile elongation according to the target pickling thickness reduction coefficient, the tensile elongation setting value and the pickling speed;

[0048] The control module is used to control the production operation of the pickling and straightening machine according to the actual value of the straightening elongation.

[0049] Through one or more technical solutions of the present invention, the present invention has the following beneficial effects or advantages:

[0050] The present invention provides a pickling and straightening control method, firstly determining a target pickling thickness reduction coefficient according to a target strip steel grade, and then dynamically adjusting the actual value of the straightening elongation according to the actual pickling speed, the set value of the straightening elongation and the target pickling thickness reduction coefficient for production. Through the above-mentioned technical scheme of pickling and straightening linkage control, the actual value of the straightening elongation can be dynamically adjusted according to the actual operation of the pickling unit. Compared with the traditional control method of producing with the straightening elongation being consistent over the entire length, the linkage control of the straightening elongation of the strip according to different pickling speeds can avoid defects such as over-pickling and severe thickness reduction when the pickling unit is running at an abnormal speed, and improve the surface quality and dimensional accuracy of the strip after pickling.

[0051] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0053] Figure 1 The overall process diagram of the pickling and straightening control method according to one embodiment of the present invention is shown;

[0054] Figure 2 A schematic flow chart of a method for establishing an array of "strip steel name - pickling thickness reduction coefficient" according to an embodiment of the present invention is shown;

[0055] Figure 3 A schematic flow chart of a method for confirming an actual value of pickling and straightening elongation according to an embodiment of the present invention is shown;

[0056] Figure 4 A schematic flow chart of a method for confirming a pickling thickness reduction coefficient according to an embodiment of the present invention is shown;

[0057] Figure 5 A schematic diagram of a pickling and straightening control system according to an embodiment of the present invention is shown; DETAILED DESCRIPTION

[0058] In order to enable technicians in the technical field to which the present application belongs to understand the present application more clearly, the technical solution of the present application is described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0059] In the pickling cold rolling mill, the pickling straightening machine located at the pickling entrance plays a role in mechanically breaking scale and improving plate shape during the pickling cold rolling process, and is an indispensable equipment in cold rolling production. The pickling straightening machine applies tension to the strip while bending it with a small diameter roller. When bending and deformation exist at the same time, plastic extension occurs in the center layer of the strip, thereby improving the plate shape; on the other hand, there is a huge difference in the mechanical properties of the steel plate matrix and the iron oxide covering layer. Through repeated bending and straightening of the pickling straightening machine, the surface iron oxide scale has poor plasticity, low breaking strength, and poor bonding with the steel plate matrix, resulting in cracks and peeling. This is the principle of the pickling straightening machine for breaking scale of the pickled strip. After the scale is broken, the iron oxide scale of the strip is more likely to react chemically with the acid and fall off during the subsequent pickling process, which improves the pickling effect. The plate shape control and mechanical breaking of the pickling straightening machine are usually controlled by the straightening elongation. During normal production, the straightening elongation is controlled within a reasonable range to improve the descaling effect and control the plate shape. However, when the unit slows down due to some factors, the time the strip stays in the acid tank increases. At this time, if the pickling straightening elongation is controlled according to the normal operation of the unit, the strip is prone to obvious over-pickling defects, the pickling thickness of the strip is seriously reduced, and the dimensional accuracy of the cold hardened coil deteriorates. Taking into account the differences in the density, chemical composition and bonding strength between the iron oxide scale formed by different types of steel plates in the hot rolling stage and the steel plate matrix, it is necessary to dynamically adjust the straightening elongation of the pickling straightening machine according to the type of strip and the pickling speed, so as to control the problems of over-pickling and poor dimensional accuracy caused by low-speed pickling. In the embodiment of the present invention, the traditional rule of consistent elongation of the straightening machine throughout the entire length is broken, and a new method of pickling and straightening linkage control is proposed, such as Figure 1 As shown, the tensile straightening elongation is controlled in linkage according to the pickling speed and steel type.

[0060] like Figure 1 As shown, in an optional embodiment, the provided pickling and straightening control method is applied to a pickling production line, and the steps are as follows:

[0061] S1: Obtain the target strip steel grade for pickling, the set value of the pickling and straightening elongation of the pickling and straightening machine, and the pickling speed;

[0062] S2: Determine the target pickling thickness reduction coefficient according to the target strip steel grade;

[0063] S3: confirm the actual value of the tensile elongation according to the target pickling thickness reduction coefficient, the set value of the tensile elongation and the pickling speed;

[0064] S4: Control the production operation of the pickling and straightening machine according to the actual value of the straightening elongation.

[0065] Specifically, different types of strip steel have different thickness and composition of iron scale (iron oxide scale) due to differences in composition system and hot rolling controlled rolling and controlled cooling process. The pickling thickness reduction coefficient is an indicator to evaluate the thickness reduction variation coefficient of steel plate in pickling, which is associated with specific steel grades. Different steel grades have different pickling thickness reduction coefficients. On the other hand, the pickling speed is directly related to the total amount of pickling thinning of the strip steel. The lower the pickling speed, the longer the pickling reaction time of the strip steel, and the more likely the strip steel is to be over-pickled and over-thinned. At this time, it is necessary to jointly determine the actual value of the straightening elongation of the pickling straightening machine based on the pickling speed and the pickling thickness reduction coefficient. This is because the straightening elongation controls the crushing effect of the iron oxide scale layer on the surface of the strip steel before pickling. The larger the straightening elongation, the greater the degree of damage to the iron oxide scale, and the better the pickling effect of the iron oxide scale; while the lower the straightening elongation, the lower the scale breaking effect, and the lower the pickling effect of the iron oxide scale. In normal production, different steel grades have determined the corresponding set values ​​of tensile straightening elongation, which can obtain good pickling plate surface and dimensional accuracy. However, if the pickling speed of the unit is abnormal, such as low-speed pickling, the pickling time is prolonged, and the original tensile straightening elongation set value is used for control, it will lead to problems such as over-pickling of the plate surface and excessive thinning of the size. At this time, it is necessary to dynamically control the tensile straightening elongation according to the pickling speed to adapt to the pickling production at low speed.

[0066] This embodiment provides a pickling and straightening control method, which first determines the target pickling thickness reduction coefficient according to the target strip steel grade, and then dynamically adjusts the actual value of the straightening elongation according to the actual pickling speed, the set value of the straightening elongation and the target pickling thickness reduction coefficient for production. Through the above-mentioned technical solution of pickling and straightening linkage control, the actual value of the straightening elongation can be dynamically adjusted according to the actual operation of the pickling unit. Compared with the traditional control method of producing with consistent straightening elongation throughout the entire length, the linkage control of the straightening elongation of the strip according to different pickling speeds can avoid defects such as over-pickling and severe thickness reduction when the pickling unit is running at an abnormal speed, and improve the surface quality and dimensional accuracy of the strip after pickling.

[0067] In actual production, as an optional implementation, according to the target strip steel grade, the target pickling thickness reduction coefficient is confirmed from the mapping relationship, and the mapping relationship is the corresponding relationship between the steel grade and the pickling thickness reduction coefficient.

[0068] As mentioned above, the pickling thickness reduction coefficient is a parameter that characterizes the pickling and thinning ability of a specific type of strip steel. By pre-testing various types of strip steel with low-speed pickling production, the pickling thickness reduction coefficient corresponding to each type of strip steel is determined, and an array representing the mapping relationship of "strip steel grade-pickling thickness reduction coefficient" is obtained, and then the array is stored in a storage medium for subsequent calls. The storage medium can be a manual recording medium or a computer storage medium, such as a test data record book, a computer hard disk, a USB flash drive, or a control system server of a pickling cold rolling mill. In actual production, according to the target strip steel grade actually pickled in the production line, the corresponding target pickling thickness reduction coefficient is confirmed from the "strip steel grade-pickling thickness reduction coefficient" mapping relationship, and then the actual value of the straightening elongation is confirmed to control the pickling production of the strip steel. Next, it is introduced how the "strip steel grade-pickling thickness reduction coefficient" mapping relationship is obtained through the pickling production test.

[0069] As an optional implementation, Figure 2 As shown, the method for establishing the mapping relationship includes:

[0070] S21: obtaining the steel type of the strip steel;

[0071] S22: Determine the set area of ​​the steel strip and the set position in the set area, and obtain the target thickness value d after pickling corresponding to the set position 1 ;

[0072] S23: Controlling a set area of ​​the strip to be pickled in an acid tank;

[0073] S24: Obtain the actual thickness value d corresponding to the set position after pickling 2 ;

[0074] S25: Determine the first thickness deviation Δd corresponding to the set position 1 =d 2 -d 1 ;

[0075] S26: According to the set position and the Δd corresponding to the set position 1 , establish the pickling thickness reduction model and confirm the pickling thickness reduction coefficient;

[0076] S27: Pair the steel type of the strip steel and the pickling thickness reduction coefficient to obtain a mapping relationship.

[0077] In summary, the method for obtaining the pickling thickness reduction coefficient is to control a certain strip to be pickled at a low speed in the pickling tank. During normal production, the normal operating speed of the pickling unit is within the range of 25m / min to the upper limit of the design operating speed of the unit (about 200m / min). When encountering some problems, such as equipment failure of the pickling cold rolling production line, the operating speed of the pickling unit drops to below 20m / min, which is abnormal operation. In order to determine the pickling thickness reduction coefficient, it is necessary to control a certain set area of ​​the strip, that is, the test area is carried out in the pickling tank for low-speed pickling test, and the pickling speed can be controlled at 2-8m / min, preferably 5m / min. In this pickling production line, there are 4 acid tanks, among which the 1# acid tank is close to the pickling entrance, and the 4# pickling tank is close to the pickling outlet. The acid concentration in each acid tank is different, and the pickling time in different acid tanks is different at different positions of the strip, and the pickling thinning speed is different. Therefore, the above-mentioned method of controlling the set area to conduct pickling test in the pickling tank is, in general, to control the set area to undergo low-speed pickling for different lengths of time in each pickling tank, and to obtain the pickling thickness reduction coefficient that characterizes the pickling thinning ability of the strip by measuring the thickness reduction data of the set area after pickling at the thickness gauge at the entrance of the rolling mill and performing modeling analysis.

[0078] As an optional embodiment, the above-mentioned set area includes a first endpoint located at the outlet of the acid tank and a second endpoint located at the inlet of the acid tank; the specific method of controlling the set area of ​​the strip to be pickled in the acid tank may be:

[0079] When the first end point is discharged from the acid tank, the pickling speed of the strip is controlled to be 2-8 m / min;

[0080] When exiting the acid tank at the second end point, the pickling speed of the strip is controlled to be above 20m / min.

[0081] Taking S30Y steel as an example, the strip setting area of ​​the pickling test, that is, the data collection area, can be the area of ​​the strip steady-state low-speed pickling, which includes two endpoints: the starting endpoint at the acid tank outlet and the ending endpoint at the acid tank entrance. In order to conveniently record the position relationship of the strip pickling test section, the distance value from the set position to the strip head is used as the position characterization quantity. For example, in this embodiment, the starting endpoint can be 550m away from the strip head, and the ending terminal can be 700m away from the strip head. The total length of the strip in the acid tank is 150m. When the starting endpoint just exits the acid tank outlet, the pickling speed is reduced to 5m / min, and then when the ending endpoint just exits the acid tank outlet, the pickling speed is restored to the normal pickling speed. It can be seen that the strip steel in the range of 550m to 700m belongs to the above-mentioned steady-state low-speed pickling area. The difference is that the time and area of ​​the low-speed running of the strip steel in the pickling tank at different set positions are different. The closer to the end point, the longer the low-speed running time in the acid tank, and the greater the pickling thinning amount. Therefore, collecting thickness data and position data within the range of 550m to 700m for analysis is reliable and accurate raw data reflecting the pickling thickness thinning coefficient.

[0082] The data to be analyzed for pickling thickness reduction coefficient include strip length data and the corresponding thickness deviation Δd 1 The strip length data is the distance from the above-mentioned set position to the strip head, in m, and the thickness deviation Δd 1 It is based on the actual thickness value d corresponding to the length position of the pickled strip detected by the thickness gauge at the rolling mill entrance 2 , minus the target strip thickness d 1 For example, the strip distance from the strip head is 550m, and the corresponding thickness deviation Δd 1 :-50.7μm; Strip distance from strip head: 560m, corresponding thickness deviation Δd 1 :-56μm. The pickling thickness reduction coefficient can be obtained by establishing a pickling thickness reduction model by taking the length of a set of strip steel at set positions as the independent variable and the thickness deviation as the dependent variable.

[0083] Specifically, the pickling thickness reduction model takes the distance L between the set position and the strip head as the independent variable, and the Δd corresponding to the set position 1 The linear fitting model established for the dependent variable is:

[0084] Δd 1 =C 0 +C 1 L

[0085] Among them, the unit of Δd is μm, the unit of L is m, and the unit of C 0 is a constant, C 1 is the pickling thickness reduction coefficient.

[0086] The above linear fitting model is to fit the linear segment of the strip length position-thickness deviation array, and the pickling thickness thinning model is obtained: Δd 1 =1703-2.844*L, and further confirmed that the S30Y pickling thickness reduction coefficient is 2.844. According to the actual fitting results, the linear fitting model has a high degree of fit, and the R-sq value in the above embodiment is 99.4%. In addition, the model is simple, easy to apply in actual production, and suitable for mass production.

[0087] In yet another embodiment, the method of the above embodiment is the same as that of the above embodiment and is applied to S40 steel, as follows:

[0088] (1) The starting point of the strip test is 300m from the strip head, and the ending point is 450m from the strip head;

[0089] (2) When the starting end point exits the acid tank, the pickling speed is reduced to 2 m / min, and when the ending end point exits the acid tank, the pickling speed is increased to 30 m / min;

[0090] (3) Measure and calculate a set of length positions and corresponding thickness deviation data of the 300m to 450m strip;

[0091] (4) Taking the strip length L from the strip head as the independent variable and the thickness deviation as the dependent variable, the pickling thickness reduction model is established: Δd 1 =1074-3.5*L;

[0092] (5) Determine the pickling thickness reduction coefficient C 1 is 3.5.

[0093] In another embodiment, the method of the above embodiment is the same as that of the above embodiment, and is applied to 50W600 steel, as follows:

[0094] (1) The starting point of the strip test is 400m from the strip head, and the ending point is 550m from the strip head;

[0095] (2) When the starting end point exits the acid tank, the pickling speed is reduced to 8m / min, and when the ending end point exits the acid tank, the pickling speed is increased to 40m / min;

[0096] (3) Measure and calculate a set of length positions and corresponding thickness deviation data of the 400m to 550m strip;

[0097] (4) Taking the strip length L from the strip head as the independent variable and the thickness deviation as the dependent variable, the pickling thickness reduction model is established: Δd 1 =587-1.5*L;

[0098] (5) Determine the pickling thickness reduction coefficient C1 is 1.5.

[0099] In general, the pickling reduction coefficient C was determined by conducting slowdown pickling experiments on multiple steel grades. 1 The value range is 1.5~3.5.

[0100] After multiple low-speed pickling tests, the pickling thickness reduction coefficient C, which characterizes the pickling thinning ability of each steel, was determined. 1 After that, you can use C 1 The straightening elongation is controlled in conjunction with the pickling speed. Figure 3 As shown, the method for confirming the actual value of the tensile elongation according to the pickling thickness reduction coefficient, the set value of the tensile elongation and the pickling speed is as follows:

[0101] S31: Determine whether the pickling speed is less than a first preset value, if so, execute S32, if not, execute S37;

[0102] S32: Confirm the speed influence coefficient K 1 ;

[0103] S33: Confirm that the calculated value of the tensile elongation = the set value of the tensile elongation - C 1 *K 1 , where C 1 is the target pickling thickness reduction factor;

[0104] S34: Determine whether the calculated value of the tensile elongation is less than a second preset value. If so, execute S35; if not, execute S36;

[0105] S35: confirming that the actual value of the tensile elongation is equal to the second preset value;

[0106] S36: confirm that the actual value of the straightening elongation is equal to the calculated value of the straightening elongation;

[0107] S37: Confirm that the actual value of the straightening elongation is equal to the set value of the straightening elongation.

[0108] The above method first determines whether the pickling speed is lower than the first preset value, which is usually the lower limit of normal pickling, which can be 20-25m / min. The normal pickling speed range is 25m / min to the upper limit of the design operating speed of the pickling unit (about 200m / min). The tensile elongation is not adjusted within the normal pickling speed range. When the pickling speed drops below 20, it means that the pickling unit is in an abnormal low-speed pickling stage. At this time, the original tensile elongation setting value will result in over-pickling defects. At this time, the tensile elongation needs to be adjusted to adapt to low-speed pickling.

[0109] When using pickling thickness reduction factor C 1When adjusting the elongation of the straightening, it is also necessary to introduce the speed influence coefficient K 1 , speed influence coefficient K 1 is the pickling thickness reduction coefficient C 1 The correction is made to achieve the purpose of fine-tuning the actual elongation of the straightening machine according to the thickness deviation detected by the thickness gauge at the acid rolling entrance, so that the thinning amount of the strip steel is the normal thinning level without speed reduction. In this embodiment, according to the calculation model: the setting value of the straightening elongation - C 1 *K 1 The calculated value of the straightening elongation is used to control the production of the pickling straightening machine according to the calculated value of the straightening elongation. The principle of the above method is to quantitatively reduce the elongation of the straightening machine according to the type of strip steel, the pickling thickness reduction coefficient corresponding to the type of strip steel and the speed influence coefficient through the straightening elongation calculation model, thereby reducing the descaling effect of the straightening machine on the strip steel before pickling, extending the pickling time required for the strip steel, and avoiding over-pickling and excessive thickness reduction of the strip steel.

[0110] It can be seen that the calculated value of the straightening elongation = the set value of the straightening elongation - C 1 *K 1 , according to C 1 and K 1 The value of the straightening elongation may be very small. The pickling straightening machine not only has the function of breaking scales, but also has the function of correcting the plate shape of the strip before pickling, so as to make the cold rolling process smoother and obtain a cold-rolled hard coil with higher dimensional accuracy. Therefore, the straightening elongation cannot be reduced indefinitely, and should at least be maintained above the second preset value to ensure the plate shape of the strip and enable the strip to be cold rolled smoothly. The second preset value can be 0.5%. At this time, when the calculated straightening elongation value is less than 0.5%, the straightening elongation of the pickling straightening machine is not controlled according to the calculated value, but is uniformly controlled at 0.5%.

[0111] In some possible strip production scenarios, even if the pickling unit operating speed drops below 20m / min, it is not necessary to enable online adjustment of the straightening elongation. As an optional implementation, before the above method of confirming the actual value of the straightening elongation, it is possible to choose whether to enable the thinning coefficient C according to the pickling thickness. 1, the setting value of the straightening elongation and the pickling speed, and the method of confirming the actual value of the straightening elongation. After selecting "Enable", it is further determined whether the pickling speed is less than 20m / min to start the prior adjustment of the straightening elongation. In actual application, an online adjustment operation interface for the elongation of the straightening machine is added to the pickling operation screen. Click "USE" in the operation interface to start the online adjustment of the elongation of the straightening machine; after clicking "NO USE", the online adjustment of the elongation of the straightening machine is not put into operation. In this way, it is possible to flexibly choose whether to enable the linkage control method of the straightening elongation provided in this embodiment to meet different product performance requirements and production process control requirements.

[0112] As mentioned above, the method for confirming the actual value of the straightening elongation is as follows: 1 As a correction parameter for the pickling thickness reduction coefficient, in an optional embodiment, Figure 4 As shown, K 1 Confirmation methods include:

[0113] S321: Obtain the target thickness value d of the strip after pickling 3 ;

[0114] S322: Confirm K 1 The initial value K 0 , K 0 ∈[0.3%,0.7%];

[0115] S323: Obtain the actual thickness value d of the strip after pickling 4 ;

[0116] S324: Confirm the second thickness deviation Δd 2 =d 4 -d 3 ;

[0117] S325: Determine Δd 2 Is it within the range of [-50μm, 50μm]? If yes, execute S326; if not, execute S327;

[0118] S326: Confirm K 1 =K 0 ;

[0119] S327: If Δd 2 <-50μm, confirm K 0 =K 0 +0.1% and then return to S323; if Δd 2 >50μm, confirm K 0 =K 0 -0.1% and then returns to S323.

[0120] Specifically, the speed influence coefficient K1 The determination is based on the thickness deviation Δd between the strip thickness after pickling obtained at the pickling entrance thickness gauge and the target thickness. 2 For dynamic adjustment, firstly, a K is preset based on production experience. 1 The value of K 1 The value range is 0.3% to 0.7%, and the preferred value can be 0.5%. Then track the specific value of the thickness deviation obtained at the pickling entrance thickness gauge. If the thickness deviation is greater than 50μm, it means that the strip has a tendency to be under-pickled. At this time, the straightening elongation should be increased to improve the descaling effect of the straightening machine on the strip before pickling. According to the calculation model: straightening elongation calculation value = straightening elongation setting value - C 1 *K 1 It can be seen that if the elongation of tension leveling is to be increased, K should be reduced. 1 Value. K 1 The change step of the value can be 0.1%, that is, when the thickness deviation is greater than 50μm, K 1 The value is reduced by 0.1%. If the preset value is 0.5%, then the adjusted K 1 The value is 0.4%, and the tensile elongation is recalculated according to the adjusted value. Then the specific value of the thickness deviation after adjusting the tensile elongation obtained at the acid rolling entrance thickness gauge is tracked. If the thickness deviation is still greater than 50μm, K is further reduced in steps of 0.1%. 1 The value is set until the thickness deviation obtained by the thickness gauge at the acid rolling entrance is within the range of -50μm to 50μm, and K is stopped. 1 Adjustment of value.

[0121] Based on the same control idea, if according to the preset K 1 The value is calculated to obtain the tensile elongation to control the pickling of the strip. If the thickness deviation obtained at the pickling entrance thickness gauge is less than -50μm, it means that the strip has a tendency to be over-pickled. At this time, the tensile elongation should be reduced to reduce the scale breaking effect of the tensile straightener on the strip before pickling, so as to ensure that the strip will not have over-pickling defects even under low-speed pickling. Similarly, according to the model: tensile elongation calculation value = tensile elongation setting value - C 1 *K 1 If you want to reduce the elongation of tension straightening, you should increase K 1 Value, K 1 The step length of the value change is also 0.1%, until the thickness deviation obtained by the acid rolling entrance thickness gauge is within the range of -50μm to 50μm, and K is stopped. 1 Adjustment of value.

[0122] Next, we will demonstrate with specific data. In one embodiment, the above-mentioned method for confirming the actual value of the tensile elongation is applied to S30Y steel, as follows:

[0123] (1) Confirm the pickling thickness reduction coefficient C of S30Y 1 is 2.844, and the setting value of tensile elongation is 2.8%;

[0124] (2) After clicking "USE" on the pickling operation screen, the elongation of the tension leveler is adjusted online;

[0125] (3) When the pickling speed is <20mpm, the elongation of the straightening machine is adjusted online to confirm the speed influence coefficient K 1 The value is 0.3%, the calculated value of the elongation of the straightening machine = the set value of the elongation of the straightening machine - C 1 *K 1 =2.8%-2.844*0.3%=1.95%.

[0126] (4) It is determined that the calculated value of the elongation of the straightening machine = 1.95%> 0.5%, so the actual elongation of the straightening machine is = 1.95%.

[0127] (5) The thickness deviation detected by the thickness gauge at the rolling mill entrance is 20 to 27 μm, which is within the range of [-50 μm, 50 μm]. Therefore, the actual value of the tensile elongation is determined to be constant and controlled at 1.95%.

[0128] In another embodiment, the above-mentioned method for confirming the actual value of the tensile elongation is applied to S40 steel, as follows:

[0129] (1) Confirm the pickling thickness reduction coefficient C of S40 1 is 3.5, and the setting value of tensile elongation is 3.1%;

[0130] (2) After clicking "USE" on the pickling operation screen, the elongation of the tension leveler is adjusted online;

[0131] (3) When the pickling speed is <20mpm, the elongation of the straightening machine is adjusted online to confirm the speed influence coefficient K 1 The value is 0.7%, the calculated value of the elongation of the straightening machine = the set value of the elongation of the straightening machine - C 1 *K 1 =3.1%-3.5*0.7%=0.65%.

[0132] (4) It is determined that the calculated value of the elongation of the straightening machine = 0.65%> 0.5%, so the actual elongation of the straightening machine is = 0.65%.

[0133] (5) The thickness deviation detected by the thickness gauge at the mill entrance is 60-70 μm, which is greater than 50 μm. There is a tendency of under-pickling, and the straightening elongation should be increased. Therefore, the speed influence coefficient K1 is reconfirmed to be 0.7%-0.1%=0.6%;

[0134] (6) The new calculated value of the elongation of the straightening machine = 3.1% - 3.5 * 0.6% = 1.0%, 1.0% > 0.5%, so the actual elongation of the straightening machine = 1.0%;

[0135] (7) The thickness deviation detected by the thickness gauge at the rolling mill entrance is 34 to 49 μm, which is within the range of [-50 μm, 50 μm]. Therefore, the actual value of the tensile elongation is determined to be constant and controlled at 1.0%.

[0136] In another embodiment, the above-mentioned method for confirming the actual value of the tensile elongation is applied to 50W600 steel, as follows:

[0137] (1) Confirm the pickling thickness reduction coefficient C of 50W600 1 is 1.5, and the setting value of tensile elongation is 2.3%;

[0138] (2) After clicking "USE" on the pickling operation screen, the elongation of the tension leveler is adjusted online;

[0139] (3) When the pickling speed is <20mpm, the elongation of the straightening machine is adjusted online to confirm the speed influence coefficient K 1 The value is 0.5%, the calculated value of the elongation of the straightening machine = the set value of the elongation of the straightening machine - C 1 *K 1 =2.3%-1.5*0.5%=1.55%;

[0140] (4) It is determined that the calculated value of the elongation of the straightening machine = 1.55%> 0.5%, so the actual elongation of the straightening machine is = 1.55%;

[0141] (5) The thickness deviation detected by the mill entrance thickness gauge is -95~-75μm, <-50μm, the strip tends to be over-pickled. At this time, the straightening elongation should be reduced, so the speed influence coefficient is reconfirmed: K 1 =0.5%+0.1%=0.6%;

[0142] (6) The new calculated value of the elongation of the straightening machine = 2.3% - 1.5 * 0.6% = 1.4%, 1.4% > 0.5%, so the actual elongation of the straightening machine = 1.4%;

[0143] (7) The thickness deviation detected by the thickness gauge at the rolling mill entrance is -40μm to -25μm, which is within the range of [-50μm, 50μm]. Therefore, the actual value of the tensile elongation is determined to be constant and controlled at 1.4%.

[0144] In actual production, the actual value of the tensile elongation can be adjusted dynamically by the control system in real time according to the thickness deviation detected by the thickness gauge at the rolling mill entrance. When the control system determines that the thickness deviation data fed back by the thickness gauge is outside the range of [-50μm, 50μm], the speed influence coefficient K is automatically adjusted according to the actual thickness deviation data. 1 The increase or decrease, calculation and confirmation of the actual value of the elongation of the straightening machine, and the production of the pickling and straightening machine is controlled according to the latest confirmed actual value of the elongation of the straightening machine. There is no need for technical personnel to make manual adjustments, which ensures the timeliness of the pickling and straightening linkage control and controls the length of the over-pickling and severely thinned strip within the minimum range.

[0145] The above implementation method provides an optional method for determining the pickling thickness reduction coefficient, and an optional specific control method for dynamically adjusting the tensile elongation using the pickling thickness reduction coefficient and the pickling speed. Through the pre-conducted low-speed pickling test, an array of "strip steel type-pickling thickness reduction coefficient" containing multiple varieties of strip steel is established; then, in the case of abnormal low-speed operation (<20m / min) of the pickling unit in actual production, the pickling thickness reduction coefficient C is determined according to the strip steel name, pickling speed, and pickling thickness reduction coefficient C. 1 and speed influence coefficient K 1 , according to the setting value of tensile elongation -C 1 *K 1 Quantitatively control the actual value of the straightening elongation, and dynamically adjust the speed influence coefficient K according to the thickness deviation detected by the thickness gauge 1 , and fine-tune the actual value of the straightening elongation. Through the above-mentioned quantitative control method of the straightening elongation, the straightening elongation can be adjusted dynamically in real time according to the thickness deviation data fed back by the thickness gauge in actual production, and the straightening elongation of the strip steel can be reduced to a reasonable range during low-speed pickling, which can not only ensure that the strip steel does not undergo over-pickling and serious thickness thinning, but also well control the strip shape before pickling, ensure the smooth operation of the cold rolling unit and the shape and size accuracy of the cold-rolled hard coil, and improve the surface quality of the cold-rolled hard coil after rolling.

[0146] Based on the principle of the above pickling, tensioning and straightening linkage control method, the present invention also provides a pickling, tensioning and straightening control system. In another embodiment, Figure 5 As shown, the pickling and straightening control system includes:

[0147] S5: an acquisition module, used to obtain the target strip steel grade for pickling, the set value of the pickling and straightening elongation of the pickling and straightening machine, and the pickling speed;

[0148] S6: a first confirmation module, used to confirm the target pickling thickness reduction coefficient according to the target strip steel grade;

[0149] S7: a second confirmation module, used to confirm the actual value of the tensile elongation according to the target pickling thickness reduction coefficient, the tensile elongation setting value and the pickling speed;

[0150] S8: A control module, used to control the production operation of the pickling and straightening machine according to the actual value of the straightening elongation.

[0151] Optionally, the acquisition module can be a human-computer interaction module, by manually inputting the strip name, straightening elongation setting value and pickling speed, or it can use the control system of the pickling cold rolling production line to directly read the above data from the control system.

[0152] Optionally, the first confirmation module and the second confirmation module may use a pickling and cold rolling control system for confirmation;

[0153] Optionally, the control module can use a pickling cold rolling control system to control a pickling straightening machine near the pickling entrance.

[0154] Through one or more embodiments of the present invention, the present invention has the following beneficial effects or advantages:

[0155] The present invention provides a pickling and straightening control method, firstly determining a target pickling thickness reduction coefficient according to a target strip steel grade, and then dynamically adjusting the actual value of the straightening elongation according to the actual pickling speed, the set value of the straightening elongation and the target pickling thickness reduction coefficient for production. Through the above-mentioned technical scheme of pickling and straightening linkage control, the actual value of the straightening elongation can be dynamically adjusted according to the actual operation of the pickling unit. Compared with the traditional control method of producing with the straightening elongation being consistent over the entire length, the linkage control of the straightening elongation of the strip according to different pickling speeds can avoid defects such as over-pickling and severe thickness reduction when the pickling unit is running at an abnormal speed, and improve the surface quality and dimensional accuracy of the strip after pickling.

[0156] Furthermore, the present invention also provides an optional method for determining the pickling thickness reduction coefficient, and an optional specific control method for dynamically adjusting the tensile elongation using the pickling thickness reduction coefficient and the pickling speed. Through the pre-conducted low-speed pickling test, an array of "strip steel type-pickling thickness reduction coefficient" containing multiple varieties of strip steel is established; then, in the case of abnormal low-speed operation (<20m / min) of the pickling unit in actual production, the pickling thickness reduction coefficient C is determined according to the strip steel name, pickling speed, and pickling thickness reduction coefficient C. 1 and speed influence coefficient K 1 , according to the setting value of tensile elongation -C 1 *K 1 Quantitatively control the actual value of the straightening elongation, and dynamically adjust the speed influence coefficient K according to the thickness deviation detected by the thickness gauge 1, and fine-tune the actual value of the straightening elongation. Through the above-mentioned quantitative control method of the straightening elongation, the straightening elongation can be adjusted dynamically in real time according to the thickness deviation data fed back by the thickness gauge in actual production, and the straightening elongation of the strip steel can be reduced to a reasonable range during low-speed pickling, which can not only ensure that the strip steel does not undergo over-pickling and serious thickness thinning, but also well control the strip shape before pickling, ensure the smooth operation of the cold rolling unit and the shape and size accuracy of the cold-rolled hard coil, and improve the surface quality of the cold-rolled hard coil after rolling.

[0157] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0158] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A pickling and straightening control method, It is characterized in that Applied to the pickling production line, the control method includes: S1: Obtain the target strip steel grade for pickling, the set value of the pickling and straightening elongation of the pickling and straightening machine, and the pickling speed; S2: confirming the target pickling thickness reduction coefficient according to the target strip steel grade; S3: confirming the actual value of the tensile elongation according to the target pickling thickness reduction coefficient, the tensile elongation setting value and the pickling speed; S4: Controlling the production operation of the pickling and straightening machine according to the actual value of the straightening elongation.

2. The pickling and straightening method according to claim 1, It is characterized in that Determining the target pickling thickness reduction coefficient according to the target strip steel grade includes: According to the target strip steel grade, the target pickling thickness reduction coefficient is confirmed from a mapping relationship, and the mapping relationship is a corresponding relationship between the steel grade and the pickling thickness reduction coefficient.

3. The pickling and straightening method according to claim 2, It is characterized in that The method for establishing the mapping relationship includes: S21: obtaining the steel type of the strip steel; S22: Determine a set area of ​​the steel strip and a set position in the set area, and obtain a target thickness value d after pickling corresponding to the set position. 1 ; S23: Controlling a set area of ​​the strip to be pickled in an acid tank; S24: Obtaining the actual thickness value d corresponding to the set position after pickling 2 ; S25: Determine the first thickness deviation Δd corresponding to the set position 1 =d 2 -d 1 ; S26: According to the set position and the Δd corresponding to the set position 1 , establish the pickling thickness reduction model and confirm the pickling thickness reduction coefficient; S27: Pair the steel type of the strip steel and the pickling thickness reduction coefficient to obtain the mapping relationship.

4. The pickling and straightening method according to claim 3, It is characterized in that The set area includes a first endpoint located at the acid tank outlet and a second endpoint located at the acid tank inlet; The step of controlling the set area of ​​the strip to be pickled in the acid tank comprises: When the first end point exits the acid tank, the pickling speed of the strip is controlled to be 2-8 m / min; When the second end point exits the acid tank, the pickling speed of the strip is controlled to be above 20 m / min.

5. The pickling and straightening method according to claim 3, It is characterized in that The pickling thickness reduction coefficient has a value range of 1.5 to 3.

5.

6. The pickling and straightening method according to claim 3, It is characterized in that The pickling thickness reduction model takes the distance L between the set position and the strip head as the independent variable, and the Δd corresponding to the set position 1 The linear fitting model established for the dependent variable is: Δd 1 =C 0 +C 1 L Among them, the unit of Δd is μm, the unit of L is m, and the unit of C 0 is a constant, C 1 is the pickling thickness reduction coefficient.

7. The pickling and straightening method according to claim 1, It is characterized in that The step of confirming the actual value of the tensile elongation according to the target pickling thickness reduction coefficient, the tensile elongation setting value and the pickling speed includes: S31: Determine whether the pickling speed is less than a first preset value, if so, execute S32, if not, execute S37; S32: Confirm the speed influence coefficient K 1 ; S33: Confirm that the calculated value of the tensile elongation = the set value of the tensile elongation - C 1 *K 1 , wherein the C 1 is the target pickling thickness reduction factor; S34: Determine whether the calculated value of the tensile elongation is less than a second preset value. If so, execute S35; if not, execute S36; S35: confirming that the actual value of the tensile elongation is equal to the second preset value; S36: confirm that the actual value of the straightening elongation is equal to the calculated value of the straightening elongation; S37: Confirm that the actual value of the straightening elongation is equal to the set value of the straightening elongation.

8. The pickling and straightening method according to claim 7, It is characterized in that The first preset value is 20 m / min, and the second preset value is 0.5%.

9. The pickling and straightening method according to claim 7, It is characterized in that The confirmation speed influence coefficient K 1 ,include: S321: Obtain the target thickness value d of the strip after pickling 3 ; S322: Confirm K 1 The initial value K 0 , K 0 ∈[0.3%,0.7%]; S323: Obtain the actual thickness value d of the strip after pickling 4 ; S324: Confirm the second thickness deviation Δd 2 =d 4 -d 3 ; S325: Determine Δd 2 Is it within the range of [-50μm, 50μm]? If yes, execute S326; if not, execute S327; S326: Confirm K 1 =K 0 ; S327: If Δd 2 <-50μm, confirm K 0 =K 0 +0.1% and then return to S323; if Δd 2 >50μm, confirm K 0 =K 0 -0.1% and then returns to S323.

10. A pickling and straightening control system, It is characterized in that Applied to the pickling production line, the control system includes: An acquisition module is used to obtain the target strip steel type for pickling, the set value of the pickling and straightening elongation of the pickling and straightening machine, and the pickling speed; A first confirmation module is used to confirm a target pickling thickness reduction coefficient according to the target strip steel grade; A second confirmation module is used to confirm the actual value of the tensile elongation according to the target pickling thickness reduction coefficient, the tensile elongation setting value and the pickling speed; A control module is used to control the production operation of the pickling and straightening machine according to the actual value of the straightening elongation.

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