A method for producing extremely thin and wide plates in a vertical annealing furnace

Abstract

This invention discloses a method for producing extremely thin and wide strips in a vertical annealing furnace. Before the wide strip enters the furnace, the strip offset is manually set based on its actual deviation. Considering the risk of thermal warping, the tension in the heating sections 1 and 2 of the annealing furnace, which are prone to deviation, is adjusted in advance. The cooling rate of the wide strip in the annealing furnace is then set to prevent cold warping. Finally, the tension in the flash cooling section is increased, and the distances between the wide strip and the stabilizing rollers, as well as between the wide strip and the bellows, are adjusted to mitigate scratches caused by strip vibration. This invention, through adjusting the process tension parameters for extremely thin and wide strips, setting the cooling rate of the strip in the furnace, and combining these methods with setting the offset parameters before the wide strip enters the furnace, as well as the position parameters of the stabilizing rollers and the bellows, significantly reduces defects such as deviation, warping, and scratches in the extremely thin and wide strips in the furnace, thus improving the stability of wide strip production in a vertical annealing furnace.

Description

Technical Field

[0001] This invention relates to the field of annealing furnace technology, specifically to a method for producing extremely thin and wide plates in a vertical annealing furnace. Background Technology

[0002] With the rapid development of my country's automobile industry and the continuous improvement of residents' living standards, the demand for high-end cars is increasing year by year. In particular, wide-width cold-rolled automotive steel sheets are widely used in the production of large covering parts such as car side panels and roofs. Due to their thinness, width, and soft steel grade, problems such as furnace misalignment, warping, and scratches are prone to occur during the production process. Current technologies mainly involve methods for the industrial production of wide-width steel sheets and their forming equipment, as well as a high-temperature precision alloy wide plate and strip and its production process. For example, Chinese patent application number 201410652073.9 discloses a high-temperature precision alloy wide strip and its production process, mainly involving the formulation and composition of wide strip materials; another example is Chinese patent application number 200510105788.3, ​​which discloses a method for industrial production of wide strips and its forming equipment, mainly involving forming equipment for wide strip processing; and patent application number CN104372164B describes a production method for controlling the cold bending of thin, wide, soft galvanized steel strip, which mainly solves the technical problem of cold bending of thin, wide steel strip by optimizing the cooling temperature and cooling rate after annealing, but does not involve methods for preventing deviation and scratches in thin, wide steel strip. Therefore, none of the existing technologies provide a method for the stable production of extremely thin, wide strips in a vertical continuous annealing furnace. Summary of the Invention

[0003] The purpose of this invention is to provide a method for producing extremely thin and wide plates in a vertical annealing furnace, which reduces the risks of wide plates running off-center, warping, scratches, etc. in the furnace, and improves the production stability of extremely thin and wide plates, thereby solving the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for producing extremely thin and wide plates in a vertical annealing furnace includes the following steps:

[0006] S1: Before the wide strip steel is put into the furnace, manually set the strip steel offset in the HMI operation screen, and adjust the range of ±60mm according to the actual deviation of the strip steel.

[0007] S2: Adjust the tension in advance for the heating sections 1 and 2 of the annealing furnace, which are prone to deviation. Considering the risk of hot bending of the strip, the tension of the heating section is 20-40% higher than the secondary tension, and the tension of the slow cooling section and flash cooling section is 40-60% higher than the secondary tension.

[0008] S3: Set the cooling rate of the wide plate in the annealing furnace: slow cooling zone temperature set to 650℃, flash cooling zone temperature set to 350℃, first stage of over-aging temperature set to 325℃, and second stage of over-aging temperature set to 300℃.

[0009] S4: Increase the tension of the flash cooling section, setting it to be 40-60% higher than the secondary tension. At the same time, adjust the distance between the wide strip and the stabilizing roller, as well as between the wide strip and the bellows, to reduce the scratches caused by strip vibration.

[0010] Furthermore, the thickness of the ultra-thin and wide plate is ≤0.7mm and the width is ≥1900mm. The entire recrystallization annealing process is completed through preheating in an annealing furnace, heating section, slow cooling section, flash cooling section, and over-aging.

[0011] Furthermore, the specific parameter adjustment methods in S1 are as follows: the maximum deviation of wide strip steel entering the furnace is +30mm, and the reference value for manually adjusting the deviation correction is -25mm.

[0012] Furthermore, S1 is used to prevent large deviations of wide strip steel after it enters the furnace.

[0013] Furthermore, the specific adjustment method for parameters in S2 is as follows: For mild steel DC04 with specifications of 0.7*1900mm, the fixed value of the secondary tension system is 7.02KN. After adjustment, the tension of the heating section is 8.554KN, which is 21% higher than the secondary tension. After adjustment, the reference tension of the flash cooling section is 9.97KN, which is 42% higher than the secondary tension.

[0014] Furthermore, in S3, temperature adjustments are made to the slow cooling section, fast cooling section, and over-aging section to ensure uniform temperature at the edges and center of the furnace rollers and prevent wide plates from warping due to cold.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] The present invention provides a method for producing extremely thin and wide plates in a vertical annealing furnace. By adjusting the process tension parameters of the extremely thin and wide plates and setting the cooling rate of the plates in the furnace, and by combining this with setting the offset parameters of the wide strip steel before entering the furnace, and setting the position parameters of the stabilizing roller and the wind box, the method greatly reduces defects such as deviation, warping, and scratches of the extremely thin and wide plates in the furnace. This improves the stability of wide plate production in the vertical annealing furnace, reduces losses such as product downgrading caused by quality defects of the wide strip steel in the furnace, and improves product order fulfillment and customer satisfaction. Attached Figure Description

[0017] Figure 1 This is a flowchart of the wide strip steel production process of the present invention;

[0018] Figure 2 This is a schematic diagram of the flash cooling section structure in the production process of this invention;

[0019] Figure 3 This is a reference diagram showing the offset values ​​for the wide-width plate correction according to the present invention;

[0020] Figure 4 This is a reference tension adjustment diagram for the wide-width plate of the present invention;

[0021] Figure 5 This is a schematic diagram of the wide plate curve of the present invention. Detailed Implementation

[0022] 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.

[0023] In this embodiment of the invention, the thickness of the ultrathin and wide plate is ≤0.7mm, and the width is ≥1900mm. The entire recrystallization annealing process is completed through preheating in an annealing furnace, a heating section, a slow cooling section, a flash cooling section, and over-aging. Figure 1 As shown; among them, ultra-thin and wide steel plates, specifically ultra-low carbon mild steel automotive sheets, are widely used in the manufacture of large covering parts such as automotive side panels and roofs. Due to their thinness, width, and softness, they are prone to problems such as misalignment, warping, and scratches during production. To improve the stable production quality of ultra-thin and wide steel plates in a vertical annealing furnace, this invention provides a method for producing ultra-thin and wide steel plates in a vertical annealing furnace, which includes the following steps:

[0024] S1: Before the wide strip steel is fed into the furnace, the strip steel offset is manually set on the HMI operation screen. The adjustment range is ±60mm according to the actual deviation of the strip steel; for example... Figure 3 As shown, for example, if the maximum deviation of wide strip steel entering the furnace is +30mm, manually adjust the deviation correction reference value to -25mm to prevent large deviation of wide strip steel after entering the furnace.

[0025] S2: Adjust the tension in advance for the heating sections 1 and 2 of the annealing furnace, which are prone to deviation. Considering the risk of thermal warping of the strip, the tension in the heating section should be 20-40% higher than the secondary tension, and the tension in the slow cooling and flash cooling sections should be 40-60% higher than the secondary tension. In this example, using IF mild steel DC04 with specifications of 0.7*1900mm as an example, the fixed value of the secondary tension system is 7.02KN. After adjustment, the reference tension in the heating section is 8.554KN, which is 21% higher than the secondary tension, and the reference tension in the flash cooling section is 9.97KN, which is 42% higher than the secondary tension. Figure 4 As shown;

[0026] S3: By reducing the cooling temperature difference in the cooling sections and adjusting the cooling rate, the warping of wide plates during cold cooling is prevented. Taking IF mild steel DC04 with specifications of 0.7*1900mm as an example, the cooling rate of the wide plate in the annealing furnace is set as shown in Table 1:

[0027]

[0028] The slow cooling section is set to 650℃, the flash cooling section to 350℃, the first aging stage to 325℃, and the second aging stage to 300℃. By adjusting the temperatures of the slow cooling, fast cooling, and aging stages, the temperature of the edges and center of the furnace rolls gradually becomes uniform, reducing the risk of uneven heating of the strip contacting the roll surface and causing warping along the width direction. The flash cooling section temperature is higher than the aging stage temperature primarily to allow the wide strip to undergo a slow cooling process after flash cooling through the first and second aging stages, reducing the temperature difference between the strip and the furnace chamber, thereby preventing cold warping of the strip. Figure 5 As shown;

[0029] S4: Because wide strips are prone to scratches during cooling, especially in the flash cooling section due to the strip width, the present invention requires increasing the tension in the flash cooling section, setting it to be 40-60% higher than the secondary tension. Figure 4 As shown, taking IF mild steel DC04 with specifications of 0.7*1900mm as an example, the fixed value of the secondary tension system is 7.02KN. After adjustment, the reference tension of the flash cooling section is 9.97KN, which is 42% higher than the secondary tension. Simultaneously, the distances between the wide plate and the stabilizing roller, as well as between the wide plate and the bellows, are adjusted. The reference distance between the wide plate and the stabilizing roller is L1 (reference value 0.2-2mm), see details below. Figure 2 In the detailed drawing of the flash cooling section, marked 1, the reference distance L2 between the wide plate and the bellows is ≥100mm. See details below. Figure 2 The flash cooling section is marked with 2 in the detailed drawing, which reduces the scratches caused by strip vibration.

[0030] To further illustrate the embodiments of the present invention, tests were conducted using strip steel of different specifications. The specific test parameters are shown in Table 2.

[0031]

[0032]

[0033] As can be seen from the above, the present invention provides a method for producing extremely thin and wide plates in a vertical annealing furnace. This method addresses the problems of deviation, warping, and scratches that are prone to occur in the furnace during the production of extremely thin and wide plates and ultra-low carbon mild steel. By controlling and adjusting the offset setting of the wide strip steel before entering the furnace through program control, combined with the adjustment and control of tension, temperature, and speed parameters, the method greatly reduces defects such as deviation, warping, and scratches of extremely thin and wide plates in the furnace, and improves the production stability of extremely thin and wide plates.

[0034] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for producing extremely thin and wide plates in a vertical annealing furnace, characterized in that, Includes the following steps: S1: Before the wide strip steel is put into the furnace, manually set the strip steel offset in the HMI operation screen, and adjust the range of ±60mm according to the actual deviation of the strip steel. S2: Adjust the tension in advance for the heating sections 1 and 2 of the annealing furnace, which are prone to deviation. Considering the risk of thermal warping of the strip, the tension of the heating section should be 20-40% higher than the secondary tension, and the tension of the slow cooling section and flash cooling section should be 40-60% higher than the secondary tension. The specific parameter adjustment method is as follows: For mild steel DC04 with specifications of 0.7*1900mm, the fixed value of the secondary tension system is 7.02KN. After adjustment, the tension of the heating section is 8.554KN, which is 21% higher than the secondary tension. After adjustment, the reference tension of the flash cooling section is 9.97KN, which is 42% higher than the secondary tension. S3: Set the cooling rate of the wide plate in the annealing furnace: slow cooling zone temperature set to 650℃, flash cooling zone temperature set to 350℃, first stage of over-aging temperature set to 325℃, and second stage of over-aging temperature set to 300℃. S4: Increase the tension of the flash cooling section, setting it to be 40-60% higher than the secondary tension. At the same time, adjust the distance between the wide strip and the stabilizing roller, as well as between the wide strip and the bellows, to reduce the scratches caused by strip vibration.

2. The method for producing extremely thin and wide plates in a vertical annealing furnace as described in claim 1, characterized in that: The thickness of the ultra-thin and wide plate is ≤0.7mm and the width is ≥1900mm. The entire recrystallization annealing process is completed through preheating in an annealing furnace, heating section, slow cooling section, flash cooling section and over-aging.

3. The method for producing extremely thin and wide plates in a vertical annealing furnace as described in claim 1, characterized in that: The specific parameter adjustment methods in S1 are as follows: the maximum deviation of wide strip steel entering the furnace is +30mm, and the reference value for manual adjustment of the deviation correction is -25mm.

4. The method for producing extremely thin and wide plates in a vertical annealing furnace as described in claim 3, characterized in that: S1 is used to prevent wide strip steel from deviating significantly after entering the furnace.

5. The method for producing extremely thin and wide plates in a vertical annealing furnace as described in claim 1, characterized in that: In S3, temperature adjustments are made to the slow cooling section, fast cooling section, and over-aging section to ensure uniform temperature at the edges and center of the furnace rollers and prevent wide plates from warping due to cold.

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