Bell-type furnace hot coil annealing process control method

Abstract

The invention belongs to the field of annealing, and relates to a bell-type furnace hot coil annealing process. The bell-type furnace hot coil annealing process control method comprises the steps that a steel coil coiled from a rolling line is received, and when the temperature of the steel coil is lower than 350 DEG C, the steel coil is placed in a bell-type furnace to be annealed. And the steel coil is annealed, and the space in the bell-type furnace is purged. The purging temperature is lower than 550 DEG C. The purging temperature T is N times of the sum of the initial temperature T1 of the steel coil and 200 DEG C, and the specific formula is as follows; t = N (T1 + 200). The bell-type furnace hot coil annealing process control method further comprises the step of conducting sealing detection on the bell-type furnace. The sealing detection comprises success of at least one sealing detection in a plurality of sealing detection times of the bell-type furnace in the pressure maintaining time.

Description

Technical Field

[0001] The invention belongs to the field of annealing and relates to a bell-type furnace hot coil annealing process. Background Art

[0002] In today's society, there are more and more types of steel to meet different requirements. Some types of steel cannot meet the process requirements after only strip rolling, and they need to be annealed before they can continue to carry out processes such as cutting and cold deformation. Therefore, it is necessary to reduce the hardness and improve the plasticity. Annealing can homogenize the organizational composition of steel, improve the performance of steel, and make the crystal particles in the steel finer, which is convenient for various subsequent processing. After annealing, the stress of the steel coil disappears, and the steel coil will no longer have cracks and deformation. In the traditional process of steel coil annealing, the temperature of the steel coil taken up by the rolling line needs to be reduced to below 100℃ before it can be hoisted into the bell-type furnace for annealing. Generally, the entire annealing process lasts from more than ten hours to dozens of hours, and the cooling process of the steel coil taken up by the rolling line will also last for a long time before annealing. The long wait will invisibly reduce the annealing efficiency of the bell-type furnace and increase energy consumption. To this end, this patent was invented to achieve the loading of hot steel coils and ensure the smooth heating and soaking process during annealing. At the same time, the annealing quality of the steel coils is guaranteed, and no annealing marks will be produced due to the loading of hot coils, which effectively improves efficiency, reduces energy consumption, and saves energy and is environmentally friendly. Summary of the invention

[0003] In order to overcome the defects in the above-mentioned related technologies, the present invention proposes a bell-type furnace hot coil annealing process.

[0004] Some embodiments of the present invention provide a bell-type furnace hot coil annealing process, and the bell-type furnace hot coil annealing process includes:

[0005] The steel coil received from the rolling line is placed in the bell-type furnace for annealing when the temperature of the steel coil is lower than 350°C.

[0006] The steel coil is annealed, and the furnace space of the bell-type furnace is purged.

[0007] The purge temperature is less than 550°C.

[0008] The purge temperature T is N times the sum of the initial temperature T1 of the steel coil and 200°C. The specific formula is as follows:

[0009] T=N(T1+200).

[0010] The bell-type furnace hot coil annealing process control method further includes performing a close inspection on the bell-type furnace; the close inspection includes at least one close inspection being successful among multiple close inspections of the bell-type furnace within the pressure holding time.

[0011] The calculation method of the number of close inspections is as follows:

[0012] Obtain the atmosphere pressure P in the bell-type furnace, and calculate the number of close inspections during the pressure holding time according to the atmosphere pressure P. The specific formula is as follows:

[0013]

[0014] Among them, P is the atmosphere pressure in the bell furnace, R is the gas constant, n is the molar amount, V is the atmosphere volume in the furnace, T is the upper limit of the purge temperature at this time, and during the bell furnace push process, R·n is 1;

[0015]

[0016] N represents the number of times that the pressure can be tested, t is the pressure holding time in seconds, and θ is the pressure test coefficient, which is 1.

[0017] The beneficial effects of the present invention are:

[0018] (1) The change of the purge temperature before the bell-type furnace annealing heating and soaking process is realized to avoid the annealing mark caused by the program stopping when the upper limit is reached, thus reducing the failure time.

[0019] (2) Solve the problem of annealing marks caused by failure of close inspection during annealing heating and soaking in a bell-type furnace, thereby reducing the impact of the annealing process on the quality of the steel coil.

[0020] (3) The one-click to bottom rate and product qualification rate of the bell-type furnace annealing process are improved, and energy consumption is reduced while hot coil stacking, which plays a role in energy conservation and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0024] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more. Figure 1 As shown, some embodiments of the present invention provide a bell-type furnace hot coil annealing process, and a bell-type furnace hot coil annealing process includes:

[0025] The steel coil received from the rolling line is placed in the bell-type furnace for annealing when the temperature of the steel coil is lower than 350°C.

[0026] The steel coil is annealed, and the furnace space of the bell-type furnace is purged.

[0027] The purge temperature is less than 550°C.

[0028] The purge temperature T is N times the sum of the initial temperature T1 of the steel coil and 200°C. The specific formula is as follows:

[0029] T=N(T1+200).

[0030] The bell-type furnace hot coil annealing process control method further includes performing a close inspection on the bell-type furnace; the close inspection includes at least one close inspection being successful among multiple close inspections of the bell-type furnace within the pressure holding time.

[0031] The calculation method of the number of close inspections is as follows:

[0032] Obtain the atmosphere pressure P in the bell-type furnace, and calculate the number of close inspections during the pressure holding time according to the atmosphere pressure P. The specific formula is as follows:

[0033]

[0034] Among them, P is the atmosphere pressure in the bell furnace, R is the gas constant, n is the molar amount, V is the atmosphere volume in the furnace, T is the upper limit of the purge temperature at this time, and during the bell furnace push process, R·n is 1;

[0035]

[0036] N represents the number of times that the pressure can be tested, t is the pressure holding time in seconds, and θ is the pressure test coefficient, which is 1.

[0037] The bell-type furnace annealing will purge the space inside the furnace, and then execute the subsequent procedures. During the purge, the temperature inside the furnace has a certain upper limit. If the upper limit of the purge temperature is exceeded, the program will alarm and annealing will be suspended. The equation is:

[0038] T 限 =η(T 卷 +200) (1)

[0039] Where, T 限 is the upper limit of the temperature for purging in the furnace, η is the temperature coefficient, which is set to 1.05, T 卷 It is the initial temperature of the steel coil stack.

[0040] In order to ensure that the upper limit of the alarm temperature is increased as much as possible without affecting the quality of the steel coil, a restriction equation is added:

[0041] T=Min{550,T 限} (2)

[0042] Wherein, T represents the final set alarm temperature upper limit. If the maximum purge temperature does not exceed 550°C during the annealing process, no annealing mark will be generated.

[0043] During normal annealing, the temperature of the steel coil is less than 100°C, and the upper limit of the purge temperature will be around 300°C; when hot coil annealing is used, when the steel coil temperature is 300°C, the upper limit of the purge temperature is 525°C, and when the initial temperature of the steel coil is 400°C, the upper limit of the purge temperature will be 630°C. At this time, it will be affected by the restriction equation and the upper limit of the purge temperature will be set at 550°C, ensuring product quality.

[0044] The bell-type furnace hot coil annealing will also affect the steps of the close inspection in the process. During the close inspection, the pressure equation of the atmosphere in the furnace is:

[0045]

[0046] Where P is the atmosphere pressure in the furnace, R is the gas constant, n is the molar amount, V is the atmosphere volume in the furnace, T is the upper limit of the purge temperature at this time, and during the bell-type furnace push process, R·n is 1.

[0047] During the close inspection, the atmosphere in the furnace needs to be kept under pressure for a certain period of time. If the close inspection is successful within the specified number of times, the close inspection is passed. The number equation is:

[0048]

[0049] Where N represents the number of times the pressure can be closely checked, t is the holding time in seconds, and θ is the close inspection coefficient, which is 1.

[0050] The atmosphere volume in the bell-type furnace is usually 30 cubic meters. When the temperature is 300°C, the pressure is 10, and the holding time is 10 minutes, the number of close inspections can be 5 times; when the temperature is 550°C, the number of close inspections can be 10 times. This can effectively avoid annealing interruptions and improve work efficiency without affecting quality.

[0051] Take 350℃ hot coil annealing as an example: According to the given formula, the upper limit of the purge temperature should be 577.5℃. However, in order to ensure the quality of the annealed steel coil and avoid annealing marks and other problems, the program makes a choice between 550℃ and 577.5℃, and finally uses 550℃ as the upper limit of the purge temperature at this time. Then the program calculates the atmosphere pressure in the furnace according to the given formula. N / m 3 , and then the close inspection fault tolerance times are calculated to be 9.167 times, rounded up to 10 times. In this way, the hot coil annealing not only successfully passes the most important stage of the bell-type furnace annealing heating and soaking process, but also ensures that the steel coil will not produce annealing marks due to the interruption of the annealing process.

[0052] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0053] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A bell-type furnace hot coil annealing process, characterized in that: include: receiving the steel coil taken from the rolling line, and placing the steel coil in the bell-type furnace for annealing when the temperature of the steel coil is lower than 350° C.; Annealing the steel coil and purging the furnace space of the bell-type furnace; The purge temperature is less than 550°C.

2. The bell-type furnace hot coil annealing process control method according to claim 1, characterized in that: The purge temperature T is N times the sum of the initial temperature T1 of the steel coil and 200°C. The specific formula is as follows: T=N(T1+200).

3. The bell-type furnace hot coil annealing process control method according to claim 1, characterized in that: The bell-type furnace hot coil annealing process control method further comprises performing a close inspection on the bell-type furnace; The close inspection includes that at least one close inspection of the bell-type furnace is successful among multiple close inspection times within the pressure holding time.

4. The bell-type furnace hot coil annealing process control method according to claim 2, characterized in that: The calculation method of the number of close inspections is as follows: Obtain the atmosphere pressure P in the bell-type furnace, and calculate the number of close inspections during the pressure holding time according to the atmosphere pressure P. The specific formula is as follows: Among them, P is the atmosphere pressure in the bell furnace, R is the gas constant, n is the molar amount, V is the atmosphere volume in the furnace, T is the upper limit of the purge temperature at this time, and during the bell furnace push process, R·n is 1; N represents the number of times that the pressure can be tested, t is the pressure holding time in seconds, and θ is the pressure test coefficient, which is 1.

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