Method and system for suppressing hot cupping of strip steel during continuous annealing furnace failure shutdown

Abstract

The present application belongs to the technical field of strip steel control in cold rolling continuous annealing furnace, and particularly relates to a control method and system for inhibiting strip steel hot buckling when the continuous annealing furnace is in fault shutdown. The method comprises: early warning cooling before the annealing furnace is shutdown according to the amount of strip steel at the entrance and exit of the annealing furnace; loosening the strip steel at the entrance of the annealing furnace after the annealing furnace is shutdown; keeping high blowing mode cooling in the annealing furnace after the annealing furnace is shutdown and monitoring the temperature in the annealing furnace; starting to pull the strip steel after the temperature in the annealing furnace is decreased to a target value. The system comprises: a warning module, a loosening module, a cooling module and a pulling module. The present application can reduce the heating load of the annealing furnace, avoid the occurrence of hot buckling defects of the strip steel in the annealing furnace when the unit is in emergency speed reduction or shutdown caused by faults, thereby avoiding the occurrence of accidents such as deviation and even breakage of the strip steel in the annealing furnace, ensuring the personal safety of the staff, and ensuring the normal production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of strip steel control in a cold-rolled continuous annealing furnace, and particularly relates to a control method and system for suppressing strip steel hot buckling during a continuous annealing furnace failure shutdown. BACKGROUND

[0002] Continuous annealing is an important link in cold-rolled strip steel production, and has a series of advantages such as short process, high yield, and good product quality, and can produce IF thin soft strip steel, high-surface household appliance steel, automobile plate, and other products. With the continuous improvement of user requirements for product varieties and specifications, annealing products are developing in the thin and wide directions, and the requirement for the through-plate speed is also becoming faster and faster for cost optimization. Under the condition of high-speed through-plate, the heating load of the annealing furnace also increases, and when a failure occurs in the unit, causing an emergency speed reduction or shutdown, the strip steel in the furnace will appear hot buckling defects. The defects are mainly concentrated in low-carbon and micro-carbon thin and wide strip steels, and when the defects occur, the unit continues to run, the defects will be further aggravated, and it is easy to cause the strip steel in the furnace to deviate or even break, and it takes 40-50 hours to recover from the breakage accident, which has a great impact on production.

[0003] After searching, the publication number CN105821198A discloses a control method for preventing thin strip steel buckling during continuous annealing furnace shutdown, and in a continuous annealing furnace with a preheating section, a heating section, a soaking section, a cooling section, an aging section, and a final cooling section, an inlet tension roller and an outlet tension roller are respectively arranged at the inlet and outlet of the furnace. The specific operation steps are as follows: (1) the continuous annealing furnace temperature control is switched from heating mode to cooling mode; (2) the main control PLC sends a "failure shutdown" signal, and at the same time, the strip steel speed in the continuous annealing furnace is reduced to 0 according to a 50 mpm / s shutdown slope; (3) when the strip steel speed is equal to 0, the outlet tension roller of the continuous annealing furnace is closed by brake clutch, and at the same time, the main control PLC automatically switches the strip steel tension control in the furnace from the "tension building" mode to the "tension releasing" mode, and the strip steel releases the tension; (4) the main control PLC detects that the outlet tension roller speed encoder speed is 0, and at the same time, the strip steel is in the "tension releasing" mode, and the inlet tension roller of the continuous annealing furnace starts the delay action function; the delay time is adjustable, and the time setting range is 10s-20s; during the delay time, the inlet tension roller runs at a speed of 5mpm; (5) when the strip steel temperature drops to 440-460℃, the production operator can safely pull out the waste strip steel in the furnace at a speed of 30mpm, and the unit resumes production. The feature is to control the strip steel buckling by controlling the speed shutdown, temperature reduction, and tension release in advance. This patent does not clearly define the specific specifications of the thin strip steel, and the temperature reduction is reduced to 450℃, which takes a long time and wastes a lot of cost.

[0004] In order to solve the above problems, a control method and system for inhibiting hot cupping of strip steel during failure shutdown of a continuous annealing furnace are needed. SUMMARY

[0005] In view of the above problems, the present application provides a control method for inhibiting hot cupping of strip steel during failure shutdown of a continuous annealing furnace, which comprises:

[0006] Before shutdown of the annealing furnace, early warning cooling is performed according to the amount of strip steel at the inlet and outlet of the annealing furnace;

[0007] After shutdown of the annealing furnace, the strip steel at the inlet of the annealing furnace is loosened;

[0008] After shutdown of the annealing furnace, high-blow mode cooling is maintained in the furnace and the temperature in the furnace is monitored;

[0009] After the temperature in the furnace of the annealing furnace drops to a target value, the strip steel is pulled out.

[0010] Preferably, an inlet loop is arranged at the inlet of the annealing furnace, and an outlet loop is arranged at the outlet of the annealing furnace.

[0011] Preferably, the early warning cooling according to the amount of strip steel at the inlet and outlet of the annealing furnace comprises:

[0012] determining whether an early warning cooling condition is met;

[0013] when the early warning cooling condition is met, switching the annealing furnace from heating mode to high-blow mode for cooling;

[0014] after the early warning cooling condition is eliminated, switching the annealing furnace to heating mode.

[0015] Preferably, the early warning cooling condition comprises that the output amount of strip steel of the inlet loop is less than 150 meters or the storage amount of strip steel of the outlet loop is less than 150 meters.

[0016] Preferably, the loosening of the strip steel at the inlet of the annealing furnace comprises:

[0017] setting an electric program of a tension roll at the inlet of the annealing furnace;

[0018] loosening the strip steel at the inlet of the annealing furnace according to the electric program and keeping the strip steel relaxed.

[0019] Preferably, the electric program comprises an electric interval time and a loosening frequency.

[0020] Preferably, the pulling out of the strip steel is started when the temperature in the furnace drops to the target value, which comprises:

[0021] the pulling out of the strip steel is started at a speed of 25-35 m / min until the strip steel in the annealing furnace is completely pulled out.

[0022] The application also provides a control system for inhibiting hot buckling of a strip steel during a failure shutdown of a continuous annealing furnace, the system comprising: a pre-warning module, a strip loosening module, a temperature lowering module, and a strip pulling module.

[0023] The pre-warning module is configured to pre-warn temperature lowering according to the amount of strip steel at the inlet and outlet of the annealing furnace.

[0024] The strip loosening module is configured to loosen the strip steel at the inlet of the annealing furnace after shutdown.

[0025] The temperature lowering module is configured to maintain high blowing mode for temperature lowering in the furnace after shutdown and monitor the temperature in the furnace.

[0026] The strip pulling module is configured to start pulling the strip when the temperature in the furnace of the annealing furnace decreases to a target value.

[0027] Preferably, the pre-warning module is configured to pre-warn temperature lowering according to the amount of strip steel at the inlet and outlet of the annealing furnace, comprising:

[0028] The pre-warning module is configured to determine whether the pre-warning temperature lowering condition is met.

[0029] When the pre-warning temperature lowering condition is met, the annealing furnace is switched from heating mode to high blowing mode for temperature lowering.

[0030] When the pre-warning temperature lowering condition is eliminated, the annealing furnace is switched to heating mode.

[0031] Preferably, the strip loosening module is configured to loosen the strip steel at the inlet of the annealing furnace after shutdown, comprising:

[0032] The strip loosening module is configured to set the electric program of the tension roller at the inlet of the annealing furnace.

[0033] The strip steel at the inlet of the annealing furnace is loosened according to the electric program and the strip steel is kept relaxed.

[0034] The application has the following advantages:

[0035] (1) The application can reduce the heating load of the annealing furnace, avoid the occurrence of hot buckling defects of the strip steel in the furnace when the unit is in emergency speed reduction or shutdown due to failure, avoid the occurrence of accidents such as deviation and even breakage of the strip steel in the furnace, ensure the personal safety of the workers, and ensure the normal production.

[0036] (2) The application is simple to operate, timely, time-saving, and can effectively prevent hot buckling of the strip steel after shutdown, greatly reducing the risk of breakage of the strip steel in the furnace.

[0037] Additional features and advantages of the present application will be set forth in the description that follows, and in part will be apparent from the description, or can be learned by practice of the present application. The objectives and other advantages of the present application will be realized and attained by the structure particularly pointed out in the description and appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and the ordinary skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0039] Figure 1 A flow chart of a control method for suppressing hot cupping of a strip steel during a failure shutdown of a continuous annealing furnace is shown in the embodiments of the present application;

[0040] Figure 2 A control system diagram for suppressing hot cupping of a strip steel during a failure shutdown of a continuous annealing furnace is shown in the embodiments of the present application. DETAILED DESCRIPTION

[0041] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the drawings in the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the ordinary skilled in the art without any creative effort are within the protection scope of the present application.

[0042] As shown in the drawings, Figure 1 The present application proposes a control method for suppressing hot cupping of a strip steel during a failure shutdown of a continuous annealing furnace, which comprises:

[0043] (1) Pre-warn cooling according to the strip steel amount at the inlet and outlet of the annealing furnace before the annealing furnace is shutdown

[0044] The inlet of the annealing furnace is provided with an inlet loop, and the outlet of the annealing furnace is provided with an outlet loop. Generally, the inlet loop is kept full, and the outlet loop is kept empty.

[0045] The pre-warn cooling according to the strip steel amount at the inlet and outlet of the annealing furnace comprises: judging whether the pre-warn cooling condition is met; when the pre-warn cooling condition is met, switching the annealing furnace from the heating mode to the high-blow mode for cooling, which aims to prevent the furnace temperature from rising to cause hot cupping of the strip steel after the annealing furnace is shutdown; and switching the annealing furnace to the heating mode after the pre-warn cooling condition is eliminated.

[0046] The early warning cooling condition includes that the strip output of the entry loop is less than 150 meters or the strip storage of the exit loop is less than 150 meters.

[0047] In the embodiment, the target temperature of the cooling can be much lower than the target temperature of the annealing of the strip, and is generally controlled at a difference of 400 DEG C, so as to reduce the heating load of the annealing furnace; when the condition that the strip output and storage of the loop is less than 150 meters is eliminated, the production line can keep normal operation, and the cooling mode is switched to the heating mode in time, so as to avoid that the product annealing process is not in conformity; when the condition that the strip output and storage of the loop is less than 150 meters is not eliminated, the production line is operated to stop, and the furnace is kept in the high-blow cooling mode.

[0048] (2) Loosening the strip at the entry of the annealing furnace after the annealing furnace stops

[0049] The program of controlling the motor of the tension roller at the entry of the furnace is set, in order to avoid the winding of the motor, the length of the strip loosened by the motor into the furnace is controlled at 5 meters each time, and the option of controlling the motor is set on the man-machine interface in the operation room.

[0050] The program of controlling the motor of the tension roller at the entry of the furnace is set, in order to avoid the winding of the motor, the length of the strip loosened by the motor into the furnace is controlled at 5 meters each time, and the option of controlling the motor is set on the man-machine interface in the operation room.

[0051] The program of the motor includes the interval time of the motor and the number of times of loosening the strip. In the embodiment, the strip can be loosened for multiple times, and the interval time of the motor is greater than 20 seconds each time, until the tension value of the furnace area is reduced to the range of 0-0.6 KN. The change of the tension of the furnace area is monitored, and the motor is started once when the tension value exceeds the range of 0-0.6 KN.

[0052] (3) Keeping the high-blow mode in the furnace after the annealing furnace stops and monitoring the temperature in the furnace

[0053] After the annealing furnace stops, the furnace is kept in the high-blow cooling mode, and when the highest temperature of the furnace reaches the target temperature, the strip can be started to be pulled, and the target temperature is distinguished according to the specification and the carbon equivalent, as shown in Table 1.

[0054] Table 1 Target value of the highest temperature of the furnace

[0055]

[0056] (4) Starting to pull the strip when the temperature in the furnace reaches the target value

[0057] The starting to pull the strip when the temperature in the furnace reaches the target value includes:

[0058] The speed of starting to pull the strip is 25-35 m / min, until the strip in the annealing furnace is all discharged.

[0059] As Figure 2The application also provides a control system for inhibiting strip hot buckling during continuous annealing furnace failure shutdown, which comprises a pre-warning module, a strip loosening module, a temperature lowering module and a strip pulling module.

[0060] The pre-warning module is used for pre-warning temperature lowering according to the amount of strip at the inlet and outlet of the annealing furnace.

[0061] The strip loosening module is used for loosening the strip at the inlet of the annealing furnace after shutdown.

[0062] The temperature lowering module is used for keeping high blowing mode for temperature lowering and monitoring the temperature in the furnace after shutdown.

[0063] The strip pulling module is used for starting to pull the strip when the temperature in the furnace of the annealing furnace decreases to a target value.

[0064] The pre-warning module is used for pre-warning temperature lowering according to the amount of strip at the inlet and outlet of the annealing furnace, which comprises that the pre-warning module is used for judging whether the pre-warning temperature lowering condition is met; when the pre-warning temperature lowering condition is met, the annealing furnace is switched from heating mode to high blowing mode for temperature lowering; and when the pre-warning temperature lowering condition is eliminated, the annealing furnace is switched to heating mode.

[0065] The strip loosening module is used for loosening the strip at the inlet of the annealing furnace after shutdown, which comprises that the strip loosening module is used for setting the electric program of the tension roll at the inlet of the annealing furnace; and the strip at the inlet of the annealing furnace is loosened according to the electric program and kept relaxed.

[0066] Those skilled in the art should understand that although the foregoing detailed description is made with reference to the foregoing embodiments, the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced equivalently; and the modification or replacement does not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A control method for suppressing hot buckling of a strip steel at the time of a failure stop of a continuous annealing furnace, characterized by, The method comprises: The method comprises: The annealing furnace is stopped, and the strip steel at the inlet of the annealing furnace is loosened; The annealing furnace is stopped, and the temperature in the annealing furnace is kept in the high-blow mode and monitored; The strip steel is pulled out when the temperature in the annealing furnace drops to a target value.

2. The control method according to claim 1, wherein the inlet of the annealing furnace is provided with an inlet loop, and the outlet of the annealing furnace is provided with an outlet loop.

3. The control method according to claim 1, wherein the loosening of the strip steel at the inlet of the annealing furnace comprises: The electric program of the tension roller at the inlet of the annealing furnace is set; The strip steel at the inlet of the annealing furnace is loosened according to the electric program and kept relaxed.

4. The control method according to claim 3, wherein the electric program comprises an electric interval time and a loosening frequency.

5. The control method according to claim 1, wherein the pulling out of the strip steel is started when the temperature in the annealing furnace drops to a target value, and the pulling out comprises: The pulling out is started at a speed of 25-35 m / min until the strip steel in the annealing furnace is all discharged. The system comprises a warning module, a loosening module, a temperature lowering module and a pulling-out module; The warning module is used for early warning of temperature lowering according to the amount of strip steel at the inlet and outlet of the annealing furnace, and comprises: The warning module is used for judging whether the early warning of temperature lowering is met, and the annealing furnace is switched from the heating mode to the high-blow mode for temperature lowering when the early warning of temperature lowering is met; the annealing furnace is switched to the heating mode when the early warning of temperature lowering is eliminated; the early warning of temperature lowering comprises that the output amount of strip steel of the inlet loop is less than 150 meters or the storage amount of strip steel of the outlet loop is less than 150 meters; The loosening module is used for loosening the strip steel at the inlet of the annealing furnace after the annealing furnace is stopped; 6. A control system for suppressing hot bowing of a strip steel during a failure stoppage of a continuous annealing furnace, characterized by, The temperature lowering module is used for keeping the temperature in the annealing furnace in the high-blow mode and monitoring the temperature in the annealing furnace after the annealing furnace is stopped; The pulling-out module is used for pulling out the strip steel when the temperature in the annealing furnace drops to a target value.

7. The control system according to claim 6, wherein the loosening module is used for loosening the strip steel at the inlet of the annealing furnace after the annealing furnace is stopped, and comprises: The loosening module is used for setting the electric program of the tension roller at the inlet of the annealing furnace; The strip steel at the inlet of the annealing furnace is loosened according to the electric program and kept relaxed. ​ ​ ​ ​

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