A control method for a structure for cleaning a belt steel surface from traces of rinsing

Abstract

The application discloses a control method of a structure for cleaning a belt steel surface rinsing stain, and relates to the technical field of cold-rolled sheet steel rolling. The control method of the structure for cleaning the belt steel surface rinsing stain is specifically as follows: a speed control model is additionally designed in an existing pickling process section control model. The model can judge the stop state of the pickling process section, and the model can calculate the length and duration of the belt steel staying in the rinsing tank in advance, and judge whether the reverse cleaning mode is adopted when the pickling process section resumes operation. The control method of the structure for cleaning the belt steel surface rinsing stain can remove the surface rust caused by the belt steel staying in the rinsing tank by adopting the reverse cleaning mode when the pickling process section is in the stop state, so that the surface of the belt steel after pickling is not affected by the stop of the pickling process section, the belt steel surface is kept clean at all times, and the quality defects and belt breaking accidents during the rolling of the continuous rolling mill are avoided.

Description

Technical Field

[0001] This invention relates to the field of cold-rolled sheet steel technology, specifically to a method for controlling the structure of cleaning rinsing marks on the surface of steel strip. Background Technology

[0002] In the process of producing cold-rolled thin plates by pickling and cold rolling mill, pickling is required to remove the iron oxide scale on the surface of hot-rolled raw materials in advance. Based on the advantages of hydrochloric acid pickling and shallow tank, the shallow tank hydrochloric acid pickling process is usually adopted. The mechanism of hydrochloric acid pickling of hot-rolled strip steel is that it can dissolve various types of iron oxide scale at the same time and quickly, while greatly reducing the corrosion of the metal matrix. The pickling reaction can proceed from the outer layer to the inside.

[0003] While hydrochloric acid can effectively remove iron oxide scale through chemical principles, meeting the requirements of the rolling process, some acid residue remains on the surface of the strip after pickling. Rinsing is necessary to remove this residual acid and ensure the surface quality of the strip. Existing pickling and rolling mills have rinsing tanks divided into four sections. Hot water is heated by steam injection in the last rinsing tank and then sprayed onto the strip surface. Fresh water is injected from the outlet of the final rinsing tank, circulating between the nozzles and each rinsing tank. This cascade rinsing circulation system features high performance and low water consumption. Water is fed from the last stage and overflows into the previous stage in turn, causing the water to flow in the opposite direction to the strip. Each tank is equipped with spray manifolds at the top and bottom to spray an appropriate amount of water, thus effectively rinsing away any residual substances from the strip surface.

[0004] Taking a 1720 pickling and rolling mill as an example, the basic production process is as follows: Raw material feeding → Uncoiling at the entrance section (uncoiler) → Straightening (straightening machine) → Head and tail shearing (double-layer shear) → Welding (laser welding machine) → Entrance looper → Stretch straightening and descaling (stretch straightener) → Pickling tank (pickling process section) → Rinsing tank → Drying → Intermediate looper → Edge trimming (exit edge trimming shear) → Exit looper → Rolling (rolling mill process section) → Slitting (exit shear) → Coiler → Material transportation

[0005] To ensure the quality of strip steel products and the continuous and stable operation of the production line, the pickling and rolling mill has certain control standards for the operating speed of the pickling process section and the rolling mill process section. To achieve continuous and stable operation of the production line, three loopers are usually configured. The buffering effect of the three loopers on the strip steel is used to coordinate the speed of the entry section, the pickling process section, the exit edge trimming shear, and the rolling mill process section. The purpose is to ensure that the pickling and rolling mill operates continuously and stably within the process speed range (as shown in Figure 1: Schematic diagram of the pickling and rolling mill process).

[0006] Technical parameters of the 1720mm pickling and rolling mill:

[0007] Product thickness specifications: Raw material 1.5~5.5 mm, finished product 0.3~3.0 mm

[0008] Width: Raw material 920~1600 mm, finished product 900~1575 mm

[0009] Effective length of loopers (maximum): Inlet looper 465m, Middle looper 203m, Outlet looper 235m

[0010] Speeds in each section: Maximum unwinding speed at the entrance section: 600 m / s; Threading speed: 60 m / s.

[0011] The pickling process has a maximum speed of 240 m / s and a threading speed of 30 m / s.

[0012] The maximum speed of the export edge trimmer is 330 m / s, and the threading speed is 30 m / s.

[0013] The maximum speed at the mill entrance section is 330 m / s, and the threading speed is 30 m / s.

[0014] The pickling process section uses four 30m jet-type pickling tanks, plus a 2m short recovery tank for overflow recovery. The rinsing tank is a four-section hot water rinsing tank with a total length of 18m (as shown in Figure 2: Schematic diagram of the pickling process section).

[0015] Typically, the three looper functions and speed control of each section of the pickling and rolling mill are as follows:

[0016] The inlet looper, located between the inlet section and the pickling section, is used to store and release strip steel, ensuring continuous operation of the strip steel on the production line. The effective storage capacity of the looper will meet the coil changeover time at the inlet, including completing a series of tasks such as uncoiling, threading, deceleration and tailing, head and tail shearing, welding, and edge trimming to ensure continuous operation of the pickling section.

[0017] The intermediate looper, located between the pickling section and the exit trimming shear, is used to store and release strip steel, ensuring continuous operation of the strip steel on the production line. The effective storage capacity of the looper is sufficient to meet the needs of a series of operations such as trimming and shearing, guaranteeing the continuous operation of the pickling section.

[0018] The exit looper, located between the exit trimming shear and the rolling mill process section, is used to store and release strip steel, enabling continuous operation of the strip steel in the production line. Especially during operations such as trimming shear blade width adjustment, rolling mill roll changes, and strip coil cutting at the rolling mill exit, the strip steel speed will change. The intermediate looper will handle operations such as trimming and edge cutting, exit shear shearing, coiler speed adjustment and winding, and rolling mill roll changes.

[0019] The purpose of coordinating and controlling the speed of each section is to ensure that the pickling process section and the continuous rolling mill operate continuously and stably within a certain speed range, and to avoid the production line being interrupted due to insufficient strip buffer in the looper caused by improper speed control, resulting in the continuous production interruption of the pickling process section and the rolling mill.

[0020] Under normal operating conditions, the pickling section and continuous rolling mill can ensure continuous and stable operation of the pickling and rolling mill units within the process speed range. When abnormal conditions occur (as shown in Figure 3, Table of Abnormal Conditions), for example, if the weld quality fails inspection and requires re-welding, the inlet looper speed will not be able to maintain the highest speed of the pickling section. Operators will manually intervene to reduce the speed of the pickling section and continuous rolling mill to avoid interruption of continuous production due to rapid strip runout and lack of looper capacity caused by abnormal conditions. The minimum speed for the pickling section and rolling mill can be reduced to 30 m / s. Further explanation (as shown in Figure 3, Table of Abnormal Conditions): When other abnormal conditions occur, the technical methods for controlling the speed of the pickling section and rolling mill are the same, and will not be detailed further.

[0021] Problems encountered in actual production: If the recovery time for handling abnormal conditions is too long, exceeding the waiting time required for process recovery (as shown in Figure 4, the expected waiting time schedule), it will cause the pickling process section to be shut down.

[0022] Example 1: If a weld fails quality inspection and needs to be re-welded, the process recovery time for each re-weld is 96 seconds. If the weld quality inspection is passed after re-welding, the pickling section and continuous rolling mill can be kept running stably within the process speed range by coordinating the speed of each section and the looper buffer. If the weld quality inspection still fails after re-welding, re-welding must be performed again until the weld quality is acceptable. In such cases, the process recovery time will be exceeded, causing the pickling section and continuous rolling mill to be shut down.

[0023] Example 2: In on-site production, not only will the abnormal states listed in the table (as shown in Figure 3, Abnormal State Constraint Table) occur, but other types of reasons will also cause longer downtime, such as: rolling mill strip breakage, equipment failure handling, routine maintenance, etc. The downtime handling time will exceed 30 minutes.

[0024] If the pickling process is interrupted, the pickled strip will develop water rust spots (also known as stoppage spots) due to its stay in the rinsing section. Depending on the length of time the strip stays in the rinsing tank, quality defects or production accidents may occur when it is rolled by the continuous rolling mill.

[0025] Problems with existing technologies for controlling shutdowns in the pickling process:

[0026] 1. Although strips with a dwell time of no more than 10 minutes can be continuously rolled on a continuous rolling mill, they will produce blemishes on the surface of the strip, requiring downgrading of the product.

[0027] 2. If the dwell time exceeds 20 minutes, the rolling mill must be stopped and all strip steel of the length at the stop location must be rolled out as is to avoid strip breakage accidents.

[0028] 3. Alternatively, the threading speed of each section can be further reduced to coordinate the speed of each section and the looper buffer amount control, so as to ensure continuous operation of the pickling process section and the continuous rolling mill at low speed, but this will reduce production efficiency.

[0029] Novelty search results:

[0030] The surface quality defects of strip steel caused by the shutdown of the pickling process section have been a technical problem that has always restricted the improvement of product quality and rolling stability of cold rolling mills. Steel companies and scholars have also conducted a lot of research on the pickling process and implemented improvements on pickling process equipment and rolling mill equipment, which have achieved certain results.

[0031] 1. Application No. CN202311559289.6, Main Classification No.: B21B28 / 04, Patent Name: A Strip Steel Surface Cleaning Device Before Rolling, characterized in that the strip steel surface cleaning device before rolling of the present invention first connects a water pipe to an emulsion system to provide emulsion rinsing liquid and rinsing pressure to the water pipe, then fixes the roll and the fixing rod through a fixing frame and provides rotational power to the roll, then fixes the connecting rod to which the water pipe is fixed through the fixing rod, and then sprays the liquefied rinsing liquid from the nozzle onto the surface of the roll through each connector of the emulsion system, and rinses the surface of the roll. Since the roll rotates continuously during operation, it can cooperate with the nozzle to rinse the surface of the roll, and clean the foreign matter on the surface of the roll. Compared with the prior art, it greatly reduces the number of product rejections.

[0032] 2. Authorization Announcement No. CN220862361U, Main Classification No.: B21B45 / 02, Patent Title: A Cold-Rolled Strip Steel Cleaning Device, characterized in that the cold-rolled strip steel cleaning device includes a cleaning tank, with limit electric push rods provided at the upper and lower ends of one side of the inner wall of the cleaning tank, a positioning plate provided on the side of the limit electric push rods away from the cleaning tank, and a squeegee provided on the side of the positioning plate away from the limit electric push rods, the squeegee being in the shape of an inverted triangle, and a second support frame provided at the top of the inner wall of the cleaning tank near the limit electric push rods, with a [missing information - likely a design element] located at the middle of the top of the second support frame. The device includes a drive unit with a connecting rod at its output end and a scraper at the bottom of the connecting rod. In this embodiment, a first high-pressure nozzle, a second high-pressure nozzle, and a cleaning brush are provided. When the workpiece enters the cleaning tank, the inlet pipe of the booster pump is connected to the water tank. The booster pump starts and delivers water to the tee joint, the first outlet pipe, the connecting pipe, and the second outlet pipe. Water is then high-pressure cleaned at both ends of the workpiece via the first and second high-pressure nozzles. A second motor drives the cleaning brush to rotate, which removes stubborn stains from the workpiece surface, effectively removing dirt and improving the cleanliness of the workpiece.

[0033] 3. Authorization Announcement No. CN220364593U, Main Classification No.: C23G3 / 02; C23G1 / 36, Patent Name: A Cold-Rolled Silicon Steel Pickling Line Circulation System, characterized in that the purpose of the utility model is to provide a cold-rolled silicon steel pickling line circulation system that addresses the existing technical situation. This system not only reduces the failure rate of easily clogged equipment such as heat exchangers and greatly improves the reliability of system operation, but also has a short cleaning time and high efficiency. At the same time, it does not cause secondary pollution to the surrounding environment and is more environmentally friendly.

[0034] 4. Authorization Announcement No. CN219664658U, Main Classification No.: B08B9 / 087, Patent Name: Brushing Device for Steel Pickling Line; characterized in that the brushing device for steel pickling line includes: a housing, a slide rail assembly, the slide rail assembly being installed on both sides of the inner top of the housing for limiting and providing a track; a scraper assembly, the scraper assembly being installed inside the housing for pushing away accumulated liquid inside the housing; a rinsing assembly, the rinsing assembly being slidably installed on the slide rail assembly for spraying rinsing liquid into the housing; a brushing assembly, the cleaning mechanism being fixedly installed on the rinsing assembly for brushing the side walls of the housing; a collection assembly, the collection assembly being installed at the bottom of the housing for collecting waste liquid; and an inclined channel assembly, the inclined channel assembly being installed on one side inside the housing to facilitate the flow of liquid inside the housing into the collection assembly.

[0035] 5. Authorization Announcement No. CN219117567U, Main Classification No.: C23G3 / 02, Patent Name: Strip Steel Processing Pickling and Rust Removal Device; characterized in that the brushing device of the strip steel pickling line includes a box and a water tank. The box is equipped with an pickling pool, a cleaning box and a moving component. It also includes an acid-resistant filter plate, a rust removal mechanism, a collection part and a sealing part. The acid-resistant filter plate is set in the pickling pool. The rust removal mechanism is set in two sets and is fixedly installed on the box. The collection part is set in the pickling pool for collecting rust residue after cleaning. The sealing part is fixedly installed on the box for sealing the box. The sealing part includes a sealing plate. The sealing plate is hinged to the box through two hinges. A sealing ring is set between the sealing plate and the box. A pull ring is fixedly connected to the sealing plate. This strip steel pickling and rust removal device facilitates the pickling of strip steel through the combination of a water tank, pickling pool, cleaning box, and moving components. At the same time, it can clean and collect rust residue on the surface of the strip steel through the combination of acid-resistant filter plates, rust removal mechanism, collection section, and sealing section.

[0036] 6. Patent Announcement No. CN217570210U, Main Classification No.: B21B45 / 02, Patent Title: A Cleaning Equipment for Pickling Cold-Rolled Strip Steel, characterized in that the cleaning equipment for pickling cold-rolled strip steel includes a first overflow tank, a heated water tank fixedly connected to the back of the first overflow tank, a second overflow tank fixedly connected to the back of the heated water tank, and a spray tank fixedly connected to the back of the second overflow tank; the bottom end of the inner wall of the first overflow tank and the bottom end of the inner wall of the second overflow tank are both... The device is equipped with a fixed isolation wall, and four supporting stones are fixedly connected to the bottom of the inner wall of the heating water tank. The strip steel is placed on top of the four supporting stones. Cylinders are fixedly installed on the top of both sides of the second overflow tank. The bottom of the two cylinders is rotatably connected to the squeezing upper roller through the first bearing. This utility model is a cleaning device for pickling cold-rolled strip steel. It has the functions of cleaning raw strip steel, heating raw strip steel, weak pickling of raw strip steel, and rinsing of reverse strip steel at the inlet to remove acid.

[0037] The aforementioned related patents improve the surface quality of pickled strip steel by designing a brushing device inside the pickling tank, setting a limit electric push rod in the cleaning box, adding an emulsion spraying device at the mill inlet, and designing an overflow tank connected to a heating water tank. These differ significantly in technical features from the structural device and control method for cleaning rinsing stains on the surface of strip steel designed in this invention, which removes surface rust stains caused by the strip steel remaining in the rinsing tank by adopting a reverse cleaning method. Summary of the Invention

[0038] (a) Technical problems to be solved

[0039] To address the shortcomings of existing technologies, this invention provides a method for controlling the structure of cleaning rinsing marks on the surface of steel strips, thus solving the problems existing in the prior art.

[0040] (II) Technical Solution

[0041] To achieve the above objectives, the present invention provides the following technical solution: a method for controlling the structure of cleaning rinsing stains on the surface of steel strip, the specific operation of which is as follows:

[0042] A speed control model is added to the existing pickling process control model. This model can determine the shutdown status of the pickling process. The model pre-calculates the duration and length of the strip in the rinsing tank, and determines whether to adopt a reverse cleaning method when the pickling process resumes. Furthermore, the strip automatically runs in the reverse direction of the production line, and the designed new structural device cleans and removes the surface rust caused by the strip remaining in the rinsing tank. The specific technical solution of this structural device and control method consists of the following parts:

[0043] 1. Speed ​​Control Model: This model receives downtime information from the pickling process section, determines whether to activate the reverse cleaning function, and designs operating mode judgment rules within the speed control model. Based on the downtime, it executes the corresponding pickling process section operation control program. Specifically, it calculates the effective length of the strip steel remaining in the rinsing tank, further designs the reverse running speeds of tension rollers #3 and #4, and calculates the time required for reverse pickling of the strip steel. The running direction, speed, and time of the tension rollers are all calculated and implemented by the speed control model.

[0044] 2. Cleaning Structure Device: A spray device is designed in the pickling process section. This device is installed and fixed inside the inlet recovery trough, located on the upper and lower surfaces of the strip steel. Both the upper and lower spray devices use the same design. In this method, the spray device, a fiberglass composite pipe structure, is installed in the inlet recovery trough area and fixed to the two sides of the trough with pipe clamps. Nozzles are installed on the spray pipes. Specific dimensions, locations, quantities, and technical requirements are shown in Figure 7: Spray Cleaning Structure Device. The rinsing water used for spraying is introduced into the trough from the rinsing tank inlet pipe and discharged through the overflow outlet of the pickling tank trough. Specifically, a pneumatic solenoid valve is installed in the spray pipe of the structure device to control the opening and closing of the spray water.

[0045] The rule for implementing the reverse cleaning function in this unit is that the downtime of the pickling process section is greater than 8 minutes (the downtime can be designed for each unit according to different equipment and process characteristics); further explanation: the reverse cleaning control method is as follows:

[0046] a. The downtime of the pickling process section is less than 8 minutes.

[0047] The pickling process section follows the original control model. Tension rolls #3 and #4 start up at a threading speed of 30 m / s. The model pre-calculates the effective buffer amount of strip steel in the looper to determine the current optimal speed and implements automatic control operation.

[0048] b. The pickling process section has a downtime of more than 8 minutes.

[0049] The speed control model triggers the reverse cleaning function, and the PLC program control system executes the calculation formula:

[0050] T = L / V = 18 / 20 Implement automatic control for reverse operation;

[0051] T: Reverse running time (minutes) L: Rinse tank length (meters) V: Running speed (meters / minute)

[0052] In the formula, the length of the rinsing tank is the length of the rinsing stain defect at the position where the strip remains.

[0053] Tensioning rollers #3 and #4 run in reverse at speed V, and the spray water from the cleaning structure device is turned on simultaneously during operation. After a running time T, tensioning rollers #3 and #4 stop running in reverse and the spray water is turned off simultaneously. The pickling process section resumes the original control model.

[0054] (III) Beneficial Effects

[0055] This invention provides a method for controlling the structure of cleaning rinsing stains on the surface of steel strip. It has the following beneficial effects:

[0056] The control method for cleaning rust stains on the surface of the strip steel involves adding a speed control model to the existing pickling process control model. If abnormal conditions occur during production line operation, the model automatically transmits a stop signal from the pickling process to the speed control model. This model calculates the strip length and running time in the rinsing tank. Furthermore, the strip steel automatically runs in the reverse direction of the production line, using a newly designed structural device to clean and remove surface rust stains caused by the strip steel remaining in the rinsing tank. This ensures that the surface of the pickled strip steel remains clean regardless of pickling process stoppages, achieving continuous and stable rolling.

[0057] The innovations of this structure, device, and control method include:

[0058] 1) Signal detection input system: The existing pickling process section control model is used to monitor the operating speed of each section of the production line. Once the pickling process section is shut down due to abnormal conditions, the shutdown signal will be transmitted to the speed control model. This signal serves as the judgment condition for whether to trigger the reverse cleaning mode (as shown in Figure 5: Schematic diagram of reverse cleaning control process).

[0059] 2) Reverse cleaning control method: After the speed control model triggers the execution of the reverse cleaning mode, it first calculates the effective length of the strip steel remaining in the rinsing tank, and then designs the reverse running speed of tension roller #3 and tension roller #4 to determine the time required for reverse pickling of the strip steel; the running direction, speed and time of the above tension rollers are all calculated and implemented by the speed control model (as shown in Figure 5: Schematic diagram of reverse cleaning control process).

[0060] Cleaning Structure Design: This structure is installed in the short tank of the pickling process section (as shown in Figure 6: Schematic diagram of the short tank cleaning structure). Its function is to prevent acid from being carried out and corroding the equipment during the reverse operation of the strip steel inside the pickling tank. Further explanation: First, an additional pipeline is added to the inlet of the rinsing tank spray water to introduce it into the short tank of the pickling section; Second, a spray pipe is installed in the short tank of the pickling section to connect to the spray water; Third, the spray water in the short tank can be discharged from the overflow port of the short tank; Fourth, a pneumatic solenoid valve is installed on the spray pipeline to control the opening and closing of the spray water; and a speed control model automatically controls the opening and closing of the pneumatic solenoid valve.

[0061] A structural device and control method for cleaning rinsing stains on the surface of strip steel is proposed. In the event of a shutdown in the pickling process section, the duration and length of the strip steel remaining in the rinsing tank can be pre-calculated using a speed control model to determine whether a reverse cleaning method should be adopted when the pickling process section resumes operation. By using the newly designed structural device, the surface rust spots caused by the strip steel remaining in the rinsing tank are removed, ensuring that the surface of the pickled strip steel is not affected by the shutdown of the pickling process section and that the surface of the strip steel remains clean at all times, thus achieving the goal of continuous and stable rolling.

[0062] Even when the pickling process is shut down, reverse cleaning can be used to remove surface rust caused by the strip remaining in the rinsing tank. This ensures that the surface of the pickled strip is unaffected by the downtime of the pickling process, and that the surface of the strip remains clean at all times, thus preventing quality defects and strip breakage accidents during continuous rolling. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the pickling and rolling mill process of the present invention;

[0064] Figure 2 This is a schematic diagram of the pickling process section of the present invention;

[0065] Figure 3 This is a schematic diagram illustrating the factors limiting the abnormal state of the present invention;

[0066] Figure 4 This is a schematic diagram illustrating the expected waiting timeline for the present invention;

[0067] Figure 5 This is a schematic diagram of the reverse cleaning control process of the present invention;

[0068] Figure 6 This is a schematic diagram of the short-tank cleaning structure device of the present invention;

[0069] Figure 7 This invention relates to a spray cleaning structure device. Detailed Implementation

[0070] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] Please see Figure 1-7 This invention provides a technical solution: a method for controlling the structure of cleaning rinsing stains on the surface of steel strip, the specific operation of which is as follows:

[0072] A speed control model is added to the existing pickling process control model. This model can determine the shutdown status of the pickling process. The model pre-calculates the duration and length of the strip in the rinsing tank, and determines whether to adopt a reverse cleaning method when the pickling process resumes. Furthermore, the strip automatically runs in the reverse direction of the production line, and the designed new structural device cleans and removes the surface rust caused by the strip remaining in the rinsing tank. The specific technical solution of this structural device and control method consists of the following parts:

[0073] 1. Speed ​​Control Model: This model receives downtime information from the pickling process section, determines whether to activate the reverse cleaning function, and designs operating mode judgment rules within the speed control model. Based on the downtime, it executes the corresponding pickling process section operation control program. Specifically, it calculates the effective length of the strip steel remaining in the rinsing tank, further designs the reverse running speeds of tension rollers #3 and #4, and calculates the time required for reverse pickling of the strip steel. The running direction, speed, and time of the tension rollers are all calculated and implemented by the speed control model.

[0074] 2. Cleaning Structure Device: A spray device is designed in the pickling process section. This device is installed and fixed inside the inlet recovery trough, located on the upper and lower surfaces of the strip steel. Both the upper and lower spray devices use the same design. In this method, the spray device, a fiberglass composite pipe structure, is installed in the inlet recovery trough area and fixed to the two sides of the trough with pipe clamps. Nozzles are installed on the spray pipes. Specific dimensions, locations, quantities, and technical requirements are shown in Figure 7: Spray Cleaning Structure Device. The rinsing water used for spraying is introduced into the trough from the rinsing tank inlet pipe and discharged through the overflow outlet of the pickling tank trough. Specifically, a pneumatic solenoid valve is installed in the spray pipe of the structure device to control the opening and closing of the spray water.

[0075] The rule for implementing the reverse cleaning function in this unit is that the downtime of the pickling process section is greater than 8 minutes (the downtime can be designed for each unit according to different equipment and process characteristics); further explanation: the reverse cleaning control method is as follows:

[0076] a. The downtime of the pickling process section is less than 8 minutes.

[0077] The pickling process section follows the original control model. Tension rolls #3 and #4 start up at a threading speed of 30 m / s. The model pre-calculates the effective buffer amount of strip steel in the looper to determine the current optimal speed and implements automatic control operation.

[0078] b. The downtime of the pickling process section is greater than 8 minutes.

[0079] The speed control model triggers the reverse cleaning function, and the PLC program control system executes the calculation formula:

[0080] T = L / V = 18 / 20 Implement automatic control for reverse operation;

[0081] T: Reverse running time (minutes) L: Rinse tank length (meters) V: Running speed (meters / minute)

[0082] In the formula, the length of the rinsing tank is the length of the rinsing stain defect at the position where the strip stays.

[0083] Tensioning rollers #3 and #4 run in reverse at speed V, and the spray water from the cleaning structure device is turned on simultaneously during operation. After a running time T, tensioning rollers #3 and #4 stop running in reverse and the spray water is turned off simultaneously. The pickling process section resumes the original control model.

[0084] Example:

[0085] A novel structural device and control method for cleaning rinsing marks on the surface of strip steel is used. The key feature is that a speed control model is added to the existing pickling process control model. In the event of a shutdown in the pickling process, the cleaning structure can perform reverse cleaning to remove surface rust marks caused by the strip steel remaining in the rinsing tank. This ensures that the surface of the pickled strip steel is not affected by the shutdown of the pickling process and always maintains a clean surface, thus achieving the goal of continuous and stable rolling.

[0086] The specific implementation plan is as follows:

[0087] 1. The speed control model receives shutdown information from the pickling process section, determines whether to trigger the reverse cleaning function, and executes the corresponding pickling process section operation control program based on the shutdown time. Specifically, this includes calculating the effective length of the strip steel remaining in the rinsing tank, further designing the reverse running speed of tension rollers #3 and #4, and calculating the time required for reverse pickling of the strip steel. The running direction, speed, and time of the tension rollers are all calculated and implemented by the speed control model. The reverse cleaning control method is as follows:

[0088] The pickling process downtime is less than 8 minutes.

[0089] The pickling process section follows the original control model. Tension rolls #3 and #4 start up at a threading speed of 30 m / s. The model pre-calculates the effective buffer amount of strip steel in the looper to determine the current optimal speed and implements automatic control operation.

[0090] The downtime of the pickling process section is greater than or equal to 8 minutes.

[0091] The speed control model triggers the reverse cleaning function, and the PLC program control system executes the calculation formula:

[0092] T = L / V = 18 / 20 Implement automatic speed control for reverse operation;

[0093] T: Reverse running time (minutes) L: Rinse tank length (meters) V: Reverse running speed (meters / minute)

[0094] In the formula, the length of the rinsing tank is the length of the rinsing stain defect at the position where the strip remains.

[0095] 2. Tensioning rollers #2 and #3 and #4 run in reverse at speed V. During operation, the spray water of the cleaning structure device is turned on simultaneously. After a running time T, tensioning rollers #3 and #4 stop running in reverse and the spray water is turned off simultaneously. The pickling process section resumes the original control model.

[0096] Example 1: An abnormal condition caused the weld to be re-welded twice, which exceeded the waiting time required for process recovery (as shown in Figure 4, the expected waiting time schedule), resulting in a shutdown of the pickling process section. The shutdown time was (96*2-96) / 60=1.6 minutes.

[0097] 1. The downtime of the pickling process section is 1.6 minutes. If it is less than 8 minutes, the conditions for triggering the reverse cleaning function are not met.

[0098] 2. The pickling process section follows the original control model. The No. 3 tension roll and the No. 4 tension roll start up at a threading speed of 30 m / s. The model pre-calculates the effective buffer amount of the strip steel in the looper to determine the current optimal speed and implements automatic control operation.

[0099] Example 2: An abnormal situation occurred, which was a cutting and blocking accident. The recovery time was 15 minutes, which exceeded the waiting time required for the process to recover (as shown in Figure 4, the expected waiting time schedule), causing the pickling process section to be shut down. The downtime was 15-120 / 60=13 minutes.

[0100] The pickling process section has a downtime of 13 minutes; if the downtime exceeds 8 minutes, the reverse cleaning function will be activated.

[0101] 1. The speed control model PLC program control system calculates the time required for reverse pickling of the strip steel:

[0102] T = L / V = 18 / 20 = 0.9 minutes

[0103] T: Reverse running time (minutes) L: Rinse tank length (meters) V: Reverse running speed (meters / minute)

[0104] Tensioner rollers #3 and #4 need to run in reverse for 0.9 minutes.

[0105] 2. The speed control model operates at a speed of V=20 m / min, with tension rollers #3 and #4 running in reverse, and the spray water of the synchronous cleaning structure device starting simultaneously; after a running time of T=0.9 minutes, tension rollers #3 and #4 stop running in reverse, and the spray water stops simultaneously.

[0106] 3. The pickling process section resumes the original control model. The No. 3 tension roll and the No. 4 tension roll start running at a threading speed of 30mPm. The model pre-calculates the effective buffer amount of strip steel in the looper to determine the current optimal speed and implements automatic control operation.

[0107] Example 3: Planned shutdown for maintenance, recovery time 640 minutes, routine maintenance of the pickling process section requires long-term shutdown;

[0108] 1. The maintenance and production recovery time was 640 minutes. The downtime of the pickling process section was significantly longer than 8 minutes, which triggered the reverse cleaning function.

[0109] 2. The speed control model PLC program control system calculates the time required for reverse pickling of the strip steel:

[0110] T = L / V = 18 / 20 = 0.9 minutes

[0111] T: Reverse running time (minutes) L: Rinse tank length (meters) V: Reverse running speed (meters / minute)

[0112] Tensioner rollers #3 and #4 need to run in reverse for 0.9 minutes.

[0113] 4. The speed control model operates at a speed of V=20 m / min, with tension rollers #3 and #4 running in reverse, and the spray water of the synchronous cleaning structure device starting simultaneously; after a running time of T=0.9 minutes, tension rollers #3 and #4 stop running in reverse, and the spray water stops simultaneously.

[0114] 5. The pickling process section resumes the original control model. The No. 3 tension roll and the No. 4 tension roll start running at a threading speed of 30mPm. The model pre-calculates the effective buffer amount of the strip steel in the looper to determine the current optimal speed and implements automatic control operation.

[0115] The cleaning structure and reverse cleaning control method designed and installed in this unit are designed according to the dimensions of the tank equipment and product structure specifications of the pickling process section of this unit. Any method that conforms to the changes in the cleaning structure, reverse cleaning judgment rules and operating mode is a method of this invention.

[0116] In summary, the control method for cleaning rust stains on the surface of the strip steel incorporates a speed control model on top of the existing pickling process control model. If abnormal conditions occur during production line operation, the pickling process stop signal can be automatically transmitted to the speed control model. This model calculates the strip length and running time in the rinsing tank, and the strip steel automatically runs in the reverse direction of the production line. The newly designed structural device cleans and removes surface rust stains caused by the strip steel remaining in the rinsing tank, ensuring that the surface of the pickled strip steel remains clean regardless of pickling process stoppages, thus achieving continuous and stable rolling.

[0117] The innovations of this structure, device, and control method include:

[0118] 1) Signal detection input system: The existing pickling process section control model is used to monitor the operating speed of each section of the production line. Once the pickling process section is shut down due to abnormal conditions, the shutdown signal will be transmitted to the speed control model. This signal serves as the judgment condition for whether to trigger the reverse cleaning mode (as shown in Figure 5: Schematic diagram of reverse cleaning control process).

[0119] 2) Reverse cleaning control method: After the speed control model triggers the execution of the reverse cleaning mode, it first calculates the effective length of the strip steel remaining in the rinsing tank, and then designs the reverse running speed of tension roller #3 and tension roller #4 to determine the time required for reverse pickling of the strip steel; the running direction, speed and time of the above tension rollers are all calculated and implemented by the speed control model (as shown in Figure 5: Schematic diagram of reverse cleaning control process).

[0120] Cleaning Structure Design: This structure is installed in the short tank of the pickling process section (as shown in Figure 6: Schematic diagram of the short tank cleaning structure). Its function is to prevent acid from being carried out and corroding the equipment during the reverse operation of the strip steel inside the pickling tank. Further explanation: First, an additional pipeline is added to the inlet of the rinsing tank spray water to introduce it into the short tank of the pickling section; Second, a spray pipe is installed in the short tank of the pickling section to connect to the spray water; Third, the spray water in the short tank can be discharged from the overflow port of the short tank; Fourth, a pneumatic solenoid valve is installed on the spray pipeline to control the opening and closing of the spray water; and a speed control model automatically controls the opening and closing of the pneumatic solenoid valve.

[0121] A structural device and control method for cleaning rinsing stains on the surface of strip steel is proposed. In the event of a shutdown in the pickling process section, the duration and length of the strip steel remaining in the rinsing tank can be pre-calculated using a speed control model to determine whether a reverse cleaning method should be adopted when the pickling process section resumes operation. By using the newly designed structural device, the surface rust spots caused by the strip steel remaining in the rinsing tank are removed, ensuring that the surface of the pickled strip steel is not affected by the shutdown of the pickling process section and that the surface of the strip steel remains clean at all times, thus achieving the goal of continuous and stable rolling.

[0122] Even when the pickling process is shut down, reverse cleaning can be used to remove surface rust caused by the strip remaining in the rinsing tank. This ensures that the surface of the pickled strip is unaffected by the downtime of the pickling process, and that the surface of the strip remains clean at all times, thus preventing quality defects and strip breakage accidents during continuous rolling.

[0123] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0124] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the structure of cleaning rinsing stains on the surface of steel strip, characterized in that: The specific steps are as follows: A speed control model is added to the existing pickling process control model. This model can determine the shutdown status of the pickling process. The model pre-calculates the duration and length of the strip in the rinsing tank, and determines whether to adopt a reverse cleaning method when the pickling process resumes. Furthermore, the strip automatically runs in the reverse direction of the production line, and the designed new structural device cleans and removes the surface rust caused by the strip remaining in the rinsing tank. The specific technical solution of this structural device and control method consists of the following parts: (1) Speed ​​control model: used to receive the shutdown information of the pickling process section, determine whether the reverse cleaning function is triggered, and design the operation mode judgment rules in the speed control model. According to the shutdown time, the corresponding pickling process section operation control program is executed respectively. Specifically, it includes calculating the effective length of the strip steel staying in the rinsing tank, further designing the reverse running speed of the No. 3 tension roller and the No. 4 tension roller, and calculating the time required for reverse pickling of the strip steel. The running direction, speed and time of the above tension rollers are all calculated and implemented by the speed control model. (2) Cleaning structure device: A spray device is designed in the pickling process section. The device is installed and fixed inside the inlet recovery short tank, located on the upper and lower surfaces of the strip steel. The spray devices at the upper and lower positions adopt the same design. In the use of this method, the spray device is installed in the inlet recovery short tank area. The device is a fiberglass composite material pipe structure, which is fixed to the tank on both sides by pipe clamps. The spray pipe is equipped with nozzles. The rinsing water used for spraying is introduced into the short tank through the inlet pipe of the rinsing tank and discharged through the overflow port of the short tank of the pickling tank. In the structure device, the spray pipe is equipped with a pneumatic solenoid valve to control the opening and closing of the spray water. The rule for determining whether to implement the reverse cleaning function in this unit is that the downtime of the pickling process section is greater than 8 minutes; further explanation: the reverse cleaning control method is as follows: a. The downtime of the pickling process section is less than 8 minutes. The pickling process section follows the original control model. Tension rollers #3 and #4 start up at a threading speed of 30 m / s. The model pre-calculates the effective buffer amount of strip steel in the looper to determine the current optimal speed and implements automatic control operation. b. The pickling process section has a downtime of more than 8 minutes. The speed control model triggers the reverse cleaning function, and the PLC program control system executes the calculation formula: T = L / V = 18 / 20; T: Reverse running time (minutes) L: Rinse tank length (meters) V: Running speed (meters / minute) In the formula, the length of the rinsing tank is the length of the rinsing stain defect at the position where the strip remains; Tensioning rollers #3 and #4 run in reverse at speed V, and the spray water from the cleaning structure device is turned on simultaneously during operation. After a running time T, tensioning rollers #3 and #4 stop running in reverse and the spray water is turned off simultaneously. The pickling process section resumes the original control model.

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