A method for controlling the finishing descaling of a rolling mill

Abstract

The application discloses a rolling mill precise descaling control method, and specifically comprises the following steps: (1) in the rolling model, according to different product steel grades and specification information, the descaling code corresponding to the precise descaling process is set, the descaling code comprises the descaling code of the first precise descaling process and the second precise descaling process, the descaling code for the second precise descaling process is additionally provided with a mark of using the outlet descaling mode, two different marks are respectively set in the rolling model for the two precise descaling processes, and the precise descaling devices of each pass in the two precise descaling processes in the rolling model are divided into two, including the precise descaling device at the inlet and the precise descaling device at the outlet; (2) selecting the corresponding precise descaling process according to different descaling codes; the control method is simple and easy to implement, can effectively descale, reduce the generation of buckled heads, improve the surface quality of products, and meet the descaling process requirements of different steel plate surfaces.

Description

Technical Field

[0001] This invention relates to a fine descaling control method, specifically a fine descaling control method for rolling mills, belonging to the field of rolling mill descaling technology. Background Technology

[0002] Rolling is a metal processing technique in which a metal billet is passed through the gap between a pair of rotating rolls (of various shapes). Due to the compression of the rolls, the cross-section of the material is reduced and the length is increased.

[0003] To remove secondary iron oxide scale generated on the surface of the rolled piece during rolling, inlet and outlet descaling devices are installed before and after the rolling mill, respectively. Traditionally, the inlet descaling device is kept on and off during odd-pass rolling, and the outlet descaling device is kept on and off during even-pass rolling. In this method, the descaling water flows in the opposite direction to the rolling direction. This descaling method, when rolling thick plates, easily causes a temperature drop at the end of the rolled piece, exacerbating the warping phenomenon.

[0004] Therefore, developing a descaling method for rolling mills that can overcome the above-mentioned defects has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a simple and easy-to-implement method for controlling the fine descaling of rolling mills, which effectively descals, reduces the generation of warped heads, improves the surface quality of products, and meets the different descaling process requirements of steel plate surfaces.

[0006] To address the above technical problems, this invention provides a method for controlling the finishing descaling of a rolling mill, specifically comprising the following steps:

[0007] (i) The rolling model sets the descaling code corresponding to the fine descaling process according to the steel grade and specification information of different products. The descaling code includes the descaling code of the first fine descaling process and the second fine descaling process. For the descaling code of the second fine descaling process, an exit descaling method mark is added. Two different marks are set in the rolling model for the two fine descaling processes respectively. The fine descaling device for each pass of the two fine descaling processes in the rolling model is divided into two, including the fine descaling device at the inlet and the fine descaling device at the outlet.

[0008] The first fine descaling process involves the descaling water flowing in the opposite direction to the rolling direction. During odd-pass rolling, the fine descaling device at the mill inlet is fixedly opened and closed. During even-pass rolling, the fine descaling device at the mill outlet is fixedly opened and closed.

[0009] The second precision descaling process is that the direction of descaling water is the same as the rolling direction, the precision descaling device at the outlet of the rolling mill is opened and closed in the odd pass, and the precision descaling device at the inlet of the rolling mill is opened in the even pass, and high-pressure water descaling is performed;

[0010] (ii) selecting the corresponding precision descaling process according to different descaling codes;

[0011] When the first precision descaling process is selected, the control system controls the precision descaling device at the inlet in the odd pass and controls the precision descaling device at the outlet in the even pass according to the current rolling pass number;

[0012] When the second precision descaling process is selected, the control system controls the precision descaling device at the outlet in the odd pass and controls the precision descaling device at the inlet in the even pass according to the current precision rolling stage rolling pass number.

[0013] The further defined technical solution of the application is:

[0014] Further, in the aforementioned rolling mill precision descaling control method, the control system controls the opening and closing of the precision descaling device valve in advance according to the head and tail positions of the steel plate.

[0015] In the first precision descaling process, the descaling device is opened when the head of the steel plate reaches the calculated descaling opening position, and the descaling device is closed when the tail of the steel plate reaches the calculated closing position. The position is calculated according to the rolling piece speed and the valve response time, and the opening and closing positions of the precision descaling water are dynamically calculated (L±L, L=v*t). The set speed of each descaling pass is different. If the difference in the running speed of the steel plate is not considered, the opening and closing of the descaling water will inevitably increase water consumption. The speed of the rolling piece during rolling is divided into three types: biting speed, rolling speed and throwing speed. In order to more accurately calculate the position of the rolling piece, the biting speed of the rolling piece is used as the basis for calculation during the opening of the descaling water, and the rolling speed of the rolling piece is used as the basis for calculation during the closing of the descaling water, so that the calculated position is more accurate;

[0016] In the second precision descaling process, the descaling device is opened after the head of the steel plate bites into the rolling mill (the rolling mill has a rolling force detection). The descaling device is closed when the tail of the steel plate leaves the rolling mill (the rolling mill has no rolling force detection). (This descaling process does not use dynamic position calculation. The reason is that the speed during the process of the steel plate entering or leaving the rolling mill will change, the biting speed→the rolling speed or the rolling speed→the throwing speed, which is easy to calculate inaccurate results. The biting and throwing signals from the first level are more accurate and practical.

[0017] Technical effects, because the response time of the fine descaling device valve is delayed, the control system needs to open and close the valve in advance to ensure the descaling effect, the tracking program, according to the head and tail position of the steel plate, the opening and closing of the valve is controlled in advance, and the operation of removing the iron oxide scale on the surface of the steel plate is performed.

[0018] In the foregoing fine descaling control method of the rolling mill, the second fine descaling process is used in the descaling pass of the finishing rolling stage, and the first fine descaling process is used before the finishing rolling pass and the steel transfer pass.

[0019] The present application has the following beneficial effects:

[0020] The present application develops a fine descaling process control method of a rolling mill, the direction of the fine descaling water of the descaling pass is the same as the rolling direction, which not only has the effect of descaling the surface of the rolled piece, but also reduces the temperature drop of the descaling water at the end of the rolled piece, reduces the buckling head phenomenon in the process of rolling thick plates, and reduces the difficulty of controlling the temperature of thin specifications. In actual production process, the use effect is good.

[0021] The present application mainly applies to single-stand reversible rolling mills, adopts a new fine descaling process control method of a rolling mill, controls the inlet and outlet of the rolling mill to be respectively provided with high-pressure water descaling devices, and in the rolling process, the model automatically determines the descaling mode and the descaling pass according to the descaling code determined by the descaling process (different descaling codes adopt different descaling modes). The conventional mode is odd pass, the fine descaling device at the inlet of the rolling mill is opened, and even pass, the fine descaling device at the outlet of the rolling mill is opened, a new fine descaling mode opposite to the rolling direction is added, that is, odd pass, the fine descaling device at the outlet of the rolling mill is opened. Even pass, the fine descaling device at the inlet of the rolling mill is opened, and high-pressure water descaling is performed. The present application can flexibly select the conventional descaling or the new descaling mode according to the process requirements in the rolling process. When rolling thick plates, the new descaling mode can not only remove the iron oxide scale on the surface of the hot-rolled steel plate and improve the surface quality of the product, but also reduce the generation of buckling head and reduce the rolling difficulty of temperature control of thin specifications. The method of the present application is simple and easy to implement, and can meet the different descaling process requirements of the surface of the steel plate.

[0022] The present application only takes the use of descaling code = 4 as an example. According to the average billet weight of 20 tons per month before implementation, the economic benefit can be improved = 10*20*285*11=627,000 yuan by adopting this descaling mode. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a schematic diagram of the opening of the fine descaling device of the odd pass of the embodiment of the present application;

[0024] Figure 2 It is a schematic diagram of the closing of the fine descaling device of the odd pass of the embodiment of the present application;

[0025] Figure 3 The figure shows the opening of the embodiment of the application;

[0026] Figure 4 The figure shows the closing of the embodiment of the application;

[0027] Figure 5 The table shows the use data statistics of the mill using the descaling code 4. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the application will be clearly and completely described in connection with the drawings of the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application. Embodiment 1

[0029] Taking the 5-meter mill production line of a wide and thick plate mill as an example, the conventional fine descaling mode, i.e., the first fine descaling process, has been used on site from September 2013 to December 2020. Due to the descaling water of the descaling pass, the temperature drop at the end of the rolled piece is aggravated. During the rolling process of the thick plate on site, the rolled piece has a serious buckled head, and the rolling of some thin specifications is difficult, which affects the production on site. In order to ensure the descaling effect of the steel plate surface and reduce the temperature drop at the end of the descaling water and reduce the buckled head of the steel plate, the mill fine descaling process control method of the application is used in batches from February 2021, which specifically includes the following steps:

[0030] (1) Add the descaling code of the fine descaling process of the mill

[0031] The model table can set up 50 kinds of descaling processes at most, and the corresponding descaling codes are 1-50. In the rolling model, the descaling code of the corresponding fine descaling process is set according to the steel grade and specification information of different products. Among them, 4 is the descaling code of the second fine descaling process used in the pass of the finishing rolling stage, and the rest are the descaling codes of the first fine descaling process. Set the descaling mode at the outlet to TRUE;

[0032] (2) Descaling process model setting (the descaling setting of the rolling model and the picture is divided into two settings. The model program corresponds to the logical descaling of the two settings, the logical entrance P**_espy and the logical exit P**_xspy. The picture DeSpy corresponds to the conventional fine descaling setting, and DxSpy corresponds to the new fine descaling setting. The tracking program fm_espy is fixedly corresponding to the entrance, and the tracking program fm_xspy is fixedly corresponding to the fine descaling device at the exit.)

[0033] (1) Model setting before modification

[0034] Before modification, the descaling setting of rolling model has only one flag, and there is only logical entry descaling setting. The model program does not distinguish the physical position of the entry fine descaling device and the exit fine descaling device. The tracking control program in the secondary server controls the entry fine descaling device in odd pass according to the current rolling pass number, and controls the exit fine descaling device in even pass.

[0035] (2) Modified model setting

[0036] After modification, the descaling setting of rolling model is divided into two flags, namely logical entry descaling setting and logical exit descaling setting. The conventional fine descaling mode of rolling mill, namely the first fine descaling process DeSpy, is the logical entry descaling setting flag, and the new fine descaling mode of rolling mill, namely the second fine descaling process DxSpy, is the logical exit descaling setting flag. Through picture operation, the operator can directly know which descaling fine descaling setting mode is adopted by the model.

[0037] Meanwhile, in the rolling model, the fine descaling device of each pass is also divided into two, namely the logical entry fine descaling device P**_espy and the logical exit fine descaling device P**_xspy (** is the corresponding pass number 01-29). In the tracking program, espy and xspy correspond to the physical position, and fm_espy represents the entry fine descaling device, and fm_xspy represents the exit fine descaling device, which does not change with the rolling direction.

[0038] The model program is modified. According to whether the exit descaling flag (logical exit, which changes with the rolling direction) in the descaling code is used, the model program is converted to the descaling setting of the corresponding pass number, for example, P01_espy represents the logical entry setting of the first pass, and P01_xspy represents the logical exit descaling setting of the first pass. In the tracking program, according to the current pass number and the descaling setting logic P**_espy or P**_xspy adopted by the model, it is converted to control the entry fm_espy or the exit fine descaling device fm_xspy (physical position).

[0039] If the descaling code = 4, it means that the pass in the finishing rolling stage adopts the logical exit descaling flag = TRUE. The model automatically sets the pass number P**_xspy in the finishing rolling stage to 1. In order to ensure the descaling effect, the model program still adopts the first fine descaling process setting for the passes in the rough rolling stage and the steel transfer stage, and adopts the second fine descaling process for the passes in the finishing rolling stage.

[0040] If the descaling code is other than 4, if the logical exit descaling flag = FALSE is adopted, it means that all descaling passes adopt the first fine descaling process. The process setting of the descaling code can be modified here.

[0041] For example, if the descaling code = 2, the corresponding setting logic exit descaling flag = FALSE, the model automatically sets all P**_espy of the descaling pass to 1.

[0042] In order to ensure the descaling effect, the second fine descaling process is only used in the descaling pass of the finishing rolling stage, and the first fine descaling process is still used by default before the finishing rolling pass and the steel transfer pass;

[0043] (Three) for the thick plate rolling buckling head serious product, and temperature control thin specification product, the pass of the finishing rolling stage starts to adopt the fine descaling setting mode of the application, that is, the descaling code = 4, and the second fine descaling process is as follows:

[0044] (1) Because of the delay of the response time of the fine descaling device valve, the control system needs to open and close the valve in advance to ensure the descaling effect, and the tracking program in the secondary server controls the opening and closing of the valve in advance according to the head and tail positions of the steel plate to perform the operation of removing the iron oxide scale on the surface of the steel plate.

[0045] (2) When the odd pass is rolled, the descaling mode is required to open and close the outlet fine descaling device:

[0046] ① Determine the selected descaling mode

[0047] If the descaling code = 4, the second fine descaling process is used for control;

[0048] ② The model generates new descaling settings

[0049] The model generates the setting P**_xspy (P** represents the pass number) of the outlet descaling, which is converted to the fm_xspy setting by the tracking program;

[0050] ③ Correct the head position

[0051] When the steel biting signal TN\L_FHG_FMMIS of the odd pass is received, the tracking program corrects the head position of the rolled steel plate, which is the coordinate position of the rolling mill;

[0052] ④ The outlet fine descaling device is opened as shown in Figure 1

[0053] Because of the delay of the response time of the fine descaling valve, the control system needs to open the valve in advance to ensure the descaling effect, and the control signal TN\C_FM_XSPY_ON (signal point in the NV controller) of the descaling device opening is sent by the tracking control program when the head of the rolling piece of the odd pass reaches the position of the rolling mill, that is, the TN\C_FM_XSPY_ON = TRUE instruction is sent to open the outlet fine descaling device, and the opening control of the outlet descaling water of the rolling mill is completed;

[0054] ⑤ Correct the tail position​

[0055] Upon receiving the steel ejection signal TN\L_FHG_FMMIS from the alternate track, the tracking program corrects the tail position of the rolled steel plate to the coordinate position of the rolling mill.

[0056] ⑥ The descaling device at the outlet is closed. Figure 2 As shown

[0057] Because the response time of the fine descaling valve is delayed, the control system needs to close the valve in advance to ensure the descaling effect. The control signal TN\C_FM_XSPY_ON (signal point in the NV controller) for opening the fine descaling device tracks the control program and sends the TN\C_FM_XSPY_ON=FALSE command when the tail of the rolled piece in the alternate track reaches the mill position, thereby closing the fine descaling device at the outlet and completing the shut-off control of the descaling water at the mill outlet.

[0058] (3) During even-pass rolling, the second descaling process requires the descaling device at the inlet to be turned on:

[0059] ① Determine the method of descaling to be used

[0060] If the descaling code is 4, the second fine descaling process is controlled.

[0061] ② The model generates new descaling settings.

[0062] The descaling setting for the model generation logic exit is P**_xspy (P**_ represents the number of traces), and the corresponding setting in the tracing program is converted to fm_espy.

[0063] ③ Correct the tail position

[0064] Upon receiving the bite signal TN\L_FHG_FMMIS from an even pass, the tracking program corrects the tail position of the rolled steel plate to the coordinate position of the mill.

[0065] ④ The descaling device at the entrance is turned on. Figure 3 As shown

[0066] The control signal TN\C_FM_ESPY_ON (signal point in the NV controller) for starting the fine descaling device tracks the time when the head of the rolled piece in even-pass reaches the mill position. When the time is reached, the TN\C_FM_ESPY_ON=TRUE command is sent to start the fine descaling device at the inlet and complete the opening control of the descaling water at the mill inlet.

[0067] ⑤ Correct head position

[0068] Upon receiving the steel ejection signal TN\L_FHG_FMMIS for an even pass, the tracking program corrects the head position of the rolled steel plate to the coordinate position of the mill.

[0069] ⑥The entry descaling device is closed as shown in Figure 4

[0070] The control signal TN\L_FHG_FMMIS (signal point in the NV controller) of the fine descaling device is opened. When the head of the odd pass rolling piece reaches the mill position, the TN\C_FM_ESPY_ON=FALSE instruction is sent to close the entry fine descaling device, and the closing control of the mill entry descaling water is completed.

[0071] The 5-meter mill production line of the wide and heavy plate plant was implemented in batches from February 2021. Here, only the use of descaling code = 4 is taken as an example for illustration. From February 2021 to December 2021, according to the number of blocks using descaling code 4 each month before implementation and the total rolling block number, the usage ratio is as shown in Table 1 and Figure 5

[0072] 2021 mill descaling code 4 usage data

[0073]

[0074] According to the calculation of 10 blocks of head per month, an average billet weight of 20 tons, and an economic benefit of 285 yuan per ton, the use of this descaling method can improve the economic benefit = 10*20*285*11=627,000 yuan.

[0075] In addition to the above embodiments, the present application can also have other implementation manners. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present application.​​

Claims

1. A method for controlling the finishing descaling of a rolling mill, characterized in that, Specifically, the following steps are included: (i) The rolling model sets the descaling code corresponding to the fine descaling process according to the steel grade and specification information of different products. The descaling code includes the descaling code of the first fine descaling process and the second fine descaling process. For the descaling code of the second fine descaling process, an exit descaling method mark is added. Two different marks are set in the rolling model for the two fine descaling processes respectively. The fine descaling device for each pass of the two fine descaling processes in the rolling model is divided into two, including the fine descaling device at the inlet and the fine descaling device at the outlet. The first fine descaling process is such that the direction of the descaling water is opposite to the rolling direction. During odd-pass rolling, the fine descaling device at the mill inlet is fixedly opened and closed. During even-pass rolling, the fine descaling device at the mill outlet is fixedly opened and closed. The second fine descaling process involves the descaling water flowing in the same direction as the rolling direction. During odd-pass rolling, the fine descaling device at the mill exit is opened and closed, while during even-pass rolling, the fine descaling device at the mill inlet is opened for high-pressure water descaling. (ii) Select the corresponding fine descaling process according to different descaling codes; When selecting the first fine descaling process, the control system controls the fine descaling device at the entrance for odd-pass rolling and the fine descaling device at the exit for even-pass rolling. When selecting the second fine descaling process, the control system controls the fine descaling device at the exit during odd-pass rolling and the fine descaling device at the inlet during even-pass rolling, based on the number of passes in the current finishing rolling stage.

2. The mill descaling control method according to claim 1, characterized in that: The control system controls the opening and closing of the fine descaling device valve in advance based on the head and tail positions of the steel plate.

3. The mill descaling control method according to claim 1, characterized in that: The second fine descaling process is used in the descaling passes of the finishing rolling stage, while the first fine descaling process is used before the finishing rolling passes and in the steel transfer passes.

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