A control method for reducing the failure rate of hot strip layer cooling equipment

Abstract

This invention relates to a control method for reducing the failure rate of hot-rolled strip cooling equipment. The steps are as follows: the system tracks the position and speed of the strip and transmits the data to the PLC; after the tail of the strip passes through the corresponding cooling manifold roller conveyor, the solenoid valve of the cooling manifold closes, completing the setting and control of the coiling temperature of the current strip; after the tail of the strip passes through each set of cooling manifold roller conveyors, a virtual strip is generated in that area; the virtual strip is sprayed after the tail of the previous coil passes; after the virtual strip is sprayed, the setting and control of the actual rolled steel coil for the next coil are entered; according to the different coiling temperatures or rolling rhythms of the rolled steel grades, the interval between sprayed strip coils and the spraying time are optimized. This method requires no manual intervention in production, the system operates stably and reliably, solves the problem of high solenoid valve failure rate caused by high-temperature baking, effectively improves the quality of hot-rolled products and reduces the equipment failure rate.

Description

Technical Field

[0001] This patent application belongs to the field of hot-rolled sheet production technology, and more specifically, it relates to a control method for reducing the failure rate of hot-rolled sheet cooling equipment. Background Technology

[0002] The laminar flow cooling manifold in hot-rolled strip sprays and cools the strip after it has passed through the finishing mill, bringing it to the target coiling temperature. The coiling temperature significantly affects the microstructure of the hot-rolled strip and is one of the key process parameters determining its processing and mechanical properties; therefore, precise control of the coiling temperature is crucial. The strip temperature on the laminar flow cooling roller table is between 450-730℃. The number of laminar flow cooling manifolds to be opened is automatically calculated by a secondary mathematical model based on the rolling process requirements of different steel grades, and then sent to a primary PLC (Programmable Logic Controller) for execution. The original design stipulated that after the strip passed through the corresponding manifold at the tail end, the system would automatically close the solenoid valve of the opened manifold, waiting for the next strip to arrive at that area before issuing an opening command. Hot rolling production operates at a rapid pace, with solenoid valves in the laminar flow cooling zone subjected to prolonged high-temperature baking conditions. This results in a high failure rate for these valves, frequently leading to individual manifold solenoid valves failing to open or close. Furthermore, the cooling water system operates continuously (either open or closed) during rolling, causing abnormal strip coiling temperature control and resulting in substandard hot-rolled product performance. The original system design lacked effective protective measures for the solenoid valves and other equipment in the laminar flow cooling zone. The high-temperature environment and frequent equipment operation contribute to a high failure rate and decreased control accuracy, negatively impacting long-term stable operation and severely restricting the capacity utilization of the hot rolling production line and further improvements in product performance. Simultaneously, the frequent solenoid valve failures result in high costs for hot-rolled spare parts. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a control method for reducing the failure rate of hot-rolled layer cooling equipment, so as to solve the problem of high failure rate of solenoid valve caused by high temperature baking in the background art, thereby effectively improving the quality of hot-rolled products and reducing the equipment failure rate.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0005] A control method for reducing the failure rate of hot-rolled layer cooling equipment includes the following steps:

[0006] S1. During the strip rolling process, the automatic control system tracks data such as the position and speed of the strip and transmits the data to the first-level PLC (programmable controller) in real time.

[0007] S2. After the automatic control system tracks the tail of the strip steel through the roller table where the corresponding cooling manifold is located, the solenoid valve of that cooling manifold is closed, and the system completes the setting and coiling temperature control of the strip steel in this area.

[0008] S3. After the tail of the strip passes through the roller table where each set of cooling manifolds is located, the automatic control system generates a virtual strip in that area.

[0009] S4. The automatic control system is set to spray the virtual strip after the tail of the upper strip passes through;

[0010] S5. After the virtual strip is sprayed, the automatic control system enters the setting and control of the actual rolled steel coil.

[0011] S6. Depending on the coiling temperature or rolling rhythm of the rolled steel, the automatic control system optimizes the interval number of rolls and the spraying time of the sprayed strip on the roller table to achieve effective protection of the equipment under different rolling processes and rolling rhythms.

[0012] Furthermore, in S1, the automatic control system includes a material tracking system, which tracks the position of the strip tail in the laminar flow cooling area, that is, it collects the position information of the strip tail in any set of cooling manifold rollers.

[0013] The automatic control system collects the strip throwing time and the real-time rolling speed of the F7 finishing mill, calculates the length of the strip tail away from the F7 finishing mill, and uses this length to determine the position of the strip tail.

[0014] Furthermore, in S2, after "the automatic control system completes the setting of the strip steel and the control of the winding temperature in this area", it continues to set the opening and closing of the solenoid valves in the cooling manifold of the subsequent roller table and control the laminar cooling water until the tail of the strip steel passes through the roller table where the last set (i.e., the 22nd set) of cooling manifolds is located. Then the automatic control completes the control of the strip steel in the laminar flow cooling area.

[0015] Furthermore, the cooling manifolds are laminar flow cooling manifolds, and there are a total of 22 sets.

[0016] Furthermore, in S3, after the strip exits the F7 finishing mill and passes through the roller table of the first group of laminar flow cooling manifolds, a virtual strip is generated in the automatic control system. The virtual strip uses the speed of the actual rolled strip above on the corresponding roller table as a reference, and moves forward on the roller table of the laminar flow cooling manifold based on this reference. That is, the rolling speed of the virtual strip above the rolled strip moves from the roller table of the first group of laminar flow cooling manifolds to the roller table of the 22nd group of laminar flow cooling manifolds.

[0017] Furthermore, in S4, the difference between virtual strip spraying and actual strip spraying lies in the fact that, for actual strip, the number of cooling manifolds to be opened and the opening method are calculated by the automatic control system based on the cooling process and target coiling temperature. During cooling, there are cooling processes such as intermittent cooling and front-end cooling, meaning that some cooling manifolds are opened during production. Virtual strip uses full-open cooling manifolds, meaning that during the entire process of virtual strip running in the (laminar) cooling manifold on the roller table, the solenoid valve of the cooling manifold opens when it reaches the corresponding area, spraying the roller table where the cooling manifold is located.

[0018] Furthermore, in S5, "after the virtual strip is sprayed, the automatic control system enters the setting and control of the actual rolled steel coil" means that the solenoid valve of the laminar flow cooling manifold opens after the strip passes the tail end, and then automatically closes after 1 second, that is, the (laminar flow) cooling manifold is sprayed for 1 second on the roller table; the automatic control system enters the setting of the lower coil strip, and sets the number of cooling manifold opening groups and the opening method according to the data information such as the final rolling temperature, rolling speed, coiling temperature target value, and cooling method of the lower coil strip.

[0019] Furthermore, in S6, an interval roll adjustment screen is applied to quickly adjust the spray interval roll number and the solenoid valve opening spray time online according to the strip coiling temperature and rolling rhythm during the rolling process.

[0020] Due to the adoption of the above technical solution, the beneficial effects achieved by this invention are:

[0021] This invention generates virtual strips in the corresponding areas after the strip passes through the laminar flow cooling zone's roller conveyors. The system automatically opens the solenoid valves of the laminar flow cooling manifolds for 1 second to spray the roller conveyors, reducing the temperature of the roller conveyors and the environment. This effectively reduces the equipment failure rate caused by high-temperature baking of equipment such as solenoid valves in the laminar flow cooling zone. During production, the roller conveyor spray interval, number of coils, and spray time can be set according to the target coiling temperature value of the rolled steel grade and the rolling rhythm.

[0022] This method can effectively extend the online service life of equipment such as solenoid valves in the laminar flow cooling zone, improve the control accuracy of laminar flow cooling water, effectively enhance the quality of hot-rolled products, and reduce equipment failure rates. The method is flexible in design, easy to operate, and offers high automatic control accuracy, making it convenient for on-site implementation. Attached Figure Description

[0023] Figure 1 This is a flowchart of the process of the present invention. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the embodiments.

[0025] A control method for reducing the failure rate of hot-rolled layer cooling equipment, such as Figure 1It includes the following steps:

[0026] (1) During the rolling process, the automatic control system tracks the data information such as the position of the strip and the speed of the strip, and transmits the data information to the first-level PLC (i.e., programmable controller) in real time.

[0027] (2) After the automatic control system tracks the tail of the strip steel through the roller table where the corresponding cooling manifold is located, the solenoid valve of the cooling manifold is closed, and the automatic control system completes the setting of the strip steel and the control of the coiling temperature in this area.

[0028] (3) After the tail of the strip passes through the roller table where each cooling manifold is located, the automatic control system generates a virtual strip in that area;

[0029] (4) The automatic control system is set to spray the virtual strip after the tail of the upper strip passes through;

[0030] (5) After the virtual strip is sprayed, the automatic control system enters the setting and control of the actual rolled steel coil.

[0031] (6) Depending on the different coiling temperatures or rolling rhythms of the rolled steel, the automatic control system optimizes the setting of the interval number of rolls of sprayed strip on the roller table and the spraying time, so as to achieve effective protection of the equipment under different rolling processes and rolling rhythms.

[0032] In step (1), the automatic control system includes a material tracking system. During the strip rolling process, the material tracking system tracks the position of the strip tail in the laminar cooling zone, that is, it collects the position information of the strip tail on any set of cooling manifolds on the roller table. The system collects the strip ejection time of the F7 finishing mill and the real-time rolling speed of the strip, calculates the length of the strip tail away from the F7 finishing mill, and uses this length to determine the position of the strip tail.

[0033] In step (2), the material tracking system calculates that after the tail of the strip passes through the roller conveyor where a certain group of cooling manifolds is located, the automatic control system sets the solenoid valve of that group of cooling manifolds to automatically close. The automatic control system completes the control of this coil of strip at this position, and continues to set the opening and closing of the solenoid valves in the cooling manifolds of the subsequent roller conveyors and control the laminar cooling water, until the tail of the coil of strip passes through the roller conveyor where the last group, i.e., the 22th group of cooling manifolds, is located. At this point, the automatic control system completes the control of the coil of strip in the laminar flow cooling area. The cooling manifolds are laminar flow cooling manifolds, and there are a total of 22 groups.

[0034] In step (3), after the strip exits the F7 finishing mill and passes the roller table where the first group of laminar cooling manifolds is located, a virtual strip is generated in the automatic control system. The virtual strip uses the speed of the actual rolled strip above the corresponding roller table as a reference, and moves forward on the roller table where the laminar cooling manifolds are located based on this reference. That is, the rolling speed of the virtual strip above the rolled strip moves from the roller table where the first group of laminar cooling manifolds is located to the roller table where the 22nd group of laminar cooling manifolds is located.

[0035] In step (4), after the tail of the strip passes through each set of laminar flow cooling rollers, the system sprays the virtual strip. The difference between the virtual strip spraying and the actual strip spraying is that the actual strip is cooled by the automatic control system calculating the number of cooling manifolds to be opened and the opening method according to the cooling process and the target coiling temperature. The actual strip has cooling processes such as intermittent cooling and front-end cooling, that is, some cooling manifolds are opened during production; the virtual strip is cooled by the cooling manifolds being fully open, that is, the virtual strip runs through the rollers where the laminar flow cooling manifolds are located. When it reaches the corresponding area, the solenoid valve of the cooling manifold opens and sprays the rollers where the cooling manifolds are located.

[0036] In step (5), the solenoid valve of the laminar flow cooling manifold opens after the strip passes the tail end, and then automatically closes after 1 second, i.e., the laminar flow cooling manifold is cooled and sprayed for 1 second on the roller table. The automatic control system enters the setting of the lower coil strip, and sets the number of cooling manifold opening groups and the opening mode according to the final rolling temperature, rolling speed, coiling temperature target value, cooling method and other information of the lower coil strip.

[0037] In step (6), the hot-rolled strip steel rolling processes differ, resulting in significant variations in the target coiling temperature and the ambient temperature of the roller table. Furthermore, strip steel of different thicknesses undergoes different rolling rhythms during production. Based on actual production conditions, the number of interval coils for roller table spray cooling can be set accordingly. An interval coil adjustment screen is established to quickly adjust the spray interval coil number and the solenoid valve opening spray time online during the rolling process, based on the strip steel coiling temperature and rolling rhythm.

[0038] Combination Figure 1After the program starts, it first tracks the tail of the strip. The F7 finishing mill throws the strip and checks if the distance between the tail of the strip and the F7 finishing mill is greater than 13.595. If not, it continues to track the tail of the strip. If it is, it produces virtual strip. The virtual strip reaches the first set of rollers, the first set of cooling manifolds is turned on, and after a 1-second timer, the first set of cooling manifolds is turned off. Then the second set of cooling manifolds is turned on, and after a 1-second timer, the second set of cooling manifolds is turned off. This continues until the virtual strip reaches the 22nd set of rollers, the 22nd set of cooling manifolds is turned on, and after a 1-second timer, the 22nd set of cooling manifolds is turned off. At this time, the F1 finishing mill bites the strip, and the automatic control system sets the parameters for the next coil of strip. If the production is low-temperature coiled strip, the cooling interval coil number is set to ≥2; if the production is high-temperature coiled strip, the cooling interval coil number is set to 1.

[0039] In practical applications, this invention modifies the programmable logic controller (PLC) control program and method to generate a virtual strip after the strip passes through each set of laminar flow cooling rollers at the tail end. The automatic control system controls the solenoid valves of each cooling manifold to open for 1 second to spray the virtual strip. The process includes the following steps:

[0040] 1. The system tracks the tail end of the strip.

[0041] During strip rolling, the material tracking system calculates the strip's position based on data collected from strip speed, thickness at each mill, and HMD (Heat Mover Determination) signals from on-site hot inspection. After the strip is rolled in the finishing mill, the system calculates the distance from the strip's tail to the F7 finishing mill. The system determines the strip's tail is on that roller group when this distance equals the distance between each roller group and the F7 finishing mill. For example, if the distance between the first laminar flow cooling roller group and the F7 finishing mill is 13.595 meters, the system determines the strip's tail is on the first roller group. The material tracking system terminates its tracking of the strip in the laminar flow cooling zone after the strip's tail passes through roller groups 1-22 sequentially.

[0042] 2. Cooling manifold opening and closing settings

[0043] There are over 700 hot-rolled steel grades and diverse cooling processes. The number of open laminar flow cooling manifolds varies significantly depending on the steel grade and the process used in strip production. The automatic control system sets the number of open cooling manifolds based on data such as the strip cooling process and rolling speed, controlling the strip coiling temperature within ±17℃ of the target value. Therefore, during production, some manifolds are set to be open while others are kept closed. After the tail of the strip passes through each set of rollers, the system sets the solenoid valve of that set of cooling manifolds to close, completing the control of that coil of strip on that set of rollers. If the system sets that a set of cooling manifolds is not in use during production, then that manifold remains closed. The system tracks the strip until the 22nd set of rollers detects the tail of the strip passing through, at which point the control of that coil of strip is complete.

[0044] 3. Virtual strip generation and operation

[0045] After the tail of the strip passes through the first group of laminar flow cooling zone rollers, the automatic control system issues a closing command to the first group of open cooling manifold solenoid valves. This means that the cooling manifold closes after the tail of the strip passes through the relevant rollers, and the strip coil is cooled in this area. If the cooling manifold is not used in this coil, the solenoid valve remains closed. At the same time, a virtual strip is generated in the first group of rollers. The system sets the running speed of this virtual strip to be the same as the tail speed of the actual rolled strip in the previous coil. The virtual strip runs from the first group of laminar flow cooling rollers to the 22nd group of rollers at the same speed in the tail of the rolled strip in the previous coil.

[0046] 4. Virtual strip spray cooling

[0047] After the strip passes through each set of laminar flow cooling rollers, a virtual strip is generated on the rollers. The automatic control system sets the solenoid valves to open, spraying the virtual strip. The virtual strip does not generate a coil number and will not interfere with the setting and control of the subsequent coil. There are various laminar flow cooling methods for the strip, and the manifold opening can be either front-stage cooling or rear-stage cooling. In production, the number of cooling manifolds opened varies considerably. For example, in pipeline steel production, front-stage cooling is used, and the first 7 sets of cooling manifolds are generally opened. For thin-gauge products, rear-stage cooling is used, and the target coiling temperature is higher, so the last two sets of cooling manifolds are opened during production. The system uses a full-spray mode for the virtual slab spraying. After the virtual strip is generated, as it travels from the 1st set of rollers to the 22nd set of rollers, the solenoid valves of each set open sequentially when the virtual strip reaches the corresponding roller, spraying and cooling each set of rollers.

[0048] 5. Setting of roller spraying and uncoiled strip steel

[0049] The difference between virtual strip spraying and actual rolled strip is that the automatic control system does not set the opening of the laminar cooling manifold based on the coiling temperature control value. When the virtual slab reaches the 1-22 roller table, the solenoid valve automatically opens for 1 second, during which time the roller table is sprayed with water to cool it down. After the 1-second timeout, the solenoid valve automatically closes. At this time, the automatic control system calculates and sets parameters based on the position of the next coiled strip. When the F1 finishing mill load signal is 1, that is, when the strip enters the F1 finishing mill, the automatic control system calculates the number of laminar cooling manifolds to be opened, the opening method of the manifolds, the opening sequence number, and other set values ​​of the strip coil, and sends them to the primary PLC system. The primary system opens the solenoid valve to spray the strip based on the strip tracking information.

[0050] 6. Setting the number of roller spray intervals

[0051] The target coiling temperature for different grades of hot-rolled strip steel varies from 150-730℃. Lower target coiling temperatures are found for wear-resistant steel, pipeline steel, and thick-gauge ship plates, while higher target temperatures are found for thin-gauge automotive steel. During low-temperature coiling, the roller table ambient temperature is lower than that of high-temperature coiling, thus reducing the frequency of roller table spray cooling during the production of this series of steel grades. To address this, a spray interval coiling parameter setting has been added to the parameter setting interface. This parameter can be quickly set during production based on the type of steel being rolled and the current production pace. For low-temperature coiling or slow-paced rolling, the spray interval coil number can be set to 2 or more coils; for high-temperature coiling, the spray interval coil number can be set to 1 coil. This effectively protects equipment such as solenoid valves while reducing cooling water consumption.

[0052] A control method for reducing the failure rate of equipment in the laminar flow cooling zone of hot rolling mill is proposed. Addressing the issue of high failure rates caused by prolonged high-temperature baking of equipment such as solenoid valves in the laminar flow cooling zone, the method involves activating a 1-second cooling spray function after the strip passes through each roller in the laminar flow cooling zone. This reduces the ambient temperature of the rollers, minimizes the occurrence of solenoid valve malfunctions such as being normally open or normally closed during production, improves equipment control accuracy, and ensures quality control of hot-rolled products while reducing spare parts consumption.

[0053] As can be seen, this invention addresses the problem of solenoid valves in the laminar flow cooling zone being constantly exposed to high temperatures during actual production, causing cooling manifolds to be either normally open or normally closed. The control program is optimized by generating a virtual strip signal in the laminar flow cooling zone after the strip tail rolling is completed. This signal is used to guide the strip from the first set of cooling manifolds to the twenty-second and final set. When the virtual strip reaches the corresponding manifold, the cooling manifold opens for one second to spray the roller table, and then automatically closes, awaiting the system's setting of the number of cooling manifolds to open for the next strip coil. This method ensures that the cooling water is shut off after each strip coil passes through each set of cooling manifolds, completing the system's control of the coil in the corresponding area. Subsequently, the solenoid valve is opened for one second to spray the roller table, reducing the ambient temperature and protecting the solenoid valves and other equipment. This improves the service life and control accuracy of the solenoid valves, enabling precise control of the cooling water and enhancing the quality control capabilities of hot-rolled products. During production, the number of interval coils for strip spraying after the tail of the strip can be flexibly set according to the rolled steel grade and on-site working conditions. This allows control of the laminar flow cooling zone to spray cooling after the tail of each coil, and also allows setting two or more interval coils. This method requires no manual intervention during production, and the automatic control system operates stably and reliably. It solves the problems of high solenoid valve failure rate caused by high-temperature baking in the background technology, effectively improving the quality of hot-rolled products and reducing equipment failure rate.

Claims

1. A control method for reducing the failure rate of a hot strip cold rolling device, characterized by, Includes the following steps: S1. During the strip rolling process, the automatic control system tracks the data information of the strip's position and speed, and transmits the data information to the first-level PLC in real time. S2. After the automatic control system tracks the tail of the strip steel through the roller table where the corresponding cooling manifold is located, the solenoid valve of the cooling manifold is closed, and the automatic control system completes the setting and coiling temperature control of the strip steel in this area. S3. After the tail of the strip passes through the roller table where each set of cooling manifolds is located, the automatic control system generates a virtual strip in that area. S4. The automatic control system is set to spray the virtual strip after the tail of the upper strip passes through; S5. After the virtual strip is sprayed, the automatic control system enters the setting and control of the actual rolled steel coil. S6. Depending on the coiling temperature or rolling rhythm of the rolled steel, the automatic control system optimizes the setting of the interval number of rolls and the spraying time of the roller table sprayed strip to achieve effective protection of the equipment under different rolling processes and rolling rhythms. In S2, after the automatic control system completes the setting of the strip steel and the control of the coiling temperature in this area, it continues to set the opening and closing of the solenoid valves in the cooling manifold of the subsequent roller table and control the laminar cooling water until the tail of the strip steel passes through the roller table where the last set of cooling manifolds is located. Then the automatic control system completes the control of the strip steel in the laminar flow cooling area. In S3, after the strip exits the F7 finishing mill and passes through the roller table where the first group of laminar cooling manifolds is located, a virtual strip is generated in the automatic control system. The virtual strip uses the speed of the actual rolled strip above on the corresponding roller table as a reference and moves forward on the roller table where the laminar cooling manifolds are located based on this reference. In S4, the difference between virtual strip spraying and actual strip spraying is that, for actual strip, the number of cooling manifolds to be opened and the opening method are calculated by the automatic control system based on the cooling process and target coiling temperature. The actual strip involves a cooling process of intermittent cooling and front-end cooling, meaning that some cooling manifolds are opened during production. Virtual strip, on the other hand, uses full opening cooling manifolds. That is, when the virtual strip reaches the corresponding area in the roller table where the cooling manifold is located, the solenoid valve of the cooling manifold opens, spraying the roller table where the cooling manifold is located. In S5, "After the virtual strip is sprayed, the automatic control system enters the setting and control of the actual rolled steel coil" means that the solenoid valve of the laminar flow cooling manifold opens after the strip passes the tail end, and then automatically closes after 1 second, that is, the roller table where the cooling manifold is located is sprayed with cooling for 1 second; the automatic control system enters the setting of the lower coil strip, and sets the number of cooling manifold opening groups and the opening mode according to the data information of the lower coil strip's final rolling temperature, rolling speed, coiling temperature target value, and cooling method.

2. The control method of reducing the failure rate of a hot strip cold rolling apparatus according to claim 1, characterized by, In S1, the automatic control system includes a material tracking system. The material tracking system tracks the position of the strip tail in the laminar flow cooling area, that is, it collects the position information of the strip tail in any set of cooling manifold rollers. The automatic control system collects the strip throwing time and the real-time rolling speed of the F7 finishing mill, calculates the length of the strip tail away from the F7 finishing mill, and uses this length to determine the position of the strip tail.

3. The control method for reducing the failure rate of hot-rolled layer cooling equipment according to claim 2, characterized in that, The cooling manifolds are laminar flow cooling manifolds, and there are a total of 22 groups; the rolling speed of the virtual strip and the coiled strip starts from the roller table where the first group of laminar flow cooling manifolds is located and moves to the roller table where the 22nd group of laminar flow cooling manifolds is located.

4. The control method for reducing the failure rate of hot-rolled layer cooling equipment according to claim 3, characterized in that, In S6, the interval roll number adjustment screen allows for rapid online adjustment of the spray interval roll number and the solenoid valve opening spray time based on the strip coiling temperature and rolling rhythm during the rolling process.

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