Strip steel and leveling method thereof

Abstract

The invention discloses strip steel and a flattening method thereof. A strip steel flattening method comprises the steps that a flattening raw material coil is placed on a winding drum of an uncoiler, one end of strip steel is threaded to a coiler through a flattening working roller, and then a vehicle is started for flattening; wherein the flattening raw material coil sequentially comprises outer ring strip steel and inner ring strip steel from the outer ring to the inner ring, the flattening speed of the outer ring strip steel is 20-150 m / min, the flattening speed of the inner ring strip steel is 20-60 m / min, the uncoiling tension of the outer ring strip steel is 20-40 KN, and the uncoiling tension of the inner ring strip steel is 50-120 KN. According to the embodiment of the invention, leveling off tracking and contusion of the strip steel can be prevented while the leveling efficiency is improved, the shape of a raw material roll plate is improved, and the leveling yield is improved.

Description

Technical Field

[0001] The present application relates to thin-gauge hot-rolled high-strength steel, and more particularly to a strip steel and a flattening method thereof. Background Art

[0002] In recent years, with the extensive application of hot-rolled high-strength steel, especially thin-gauge products, in the automotive industry, construction industry, compressor industry and other fields, users have continuously increased their requirements for the plate quality of hot-rolled steel. In order to obtain better plate quality, the hot rolling leveling process is increasingly used in improving plate quality. However, the hot rolling leveling process also brings a large number of surface quality defects, among which deviation and contusion defects are the most widespread and have the most serious impact on the surface quality of the plate and strip. For the production of some thin-gauge high-strength steel, deviation and contusion defects often occur during the leveling process, which not only has a great impact on customer use, but also greatly reduces the yield rate of strip steel. Therefore, it is necessary to analyze the various influencing factors of deviation and contusion defects, and take corresponding measures in production to avoid the occurrence of deviation and contusion defects.

[0003] When flattening thin-gauge high-strength steel, similar steel mills at home and abroad usually adopt two methods: "reducing the flattening speed" and "reducing the unwinding tension". However, reducing the flattening speed will result in low production efficiency; reducing the unwinding tension will make the strip easily run off the track and break when flattening to the inner circle of the steel coil due to large cooling edge waves, resulting in low yield rate. Summary of the invention

[0004] The embodiment of the present application provides a steel strip and a flattening method thereof, which can improve the flattening efficiency while preventing the steel strip from being flattened and bruised, improve the coil shape of the raw material, and increase the flattening yield rate.

[0005] In the first aspect, an embodiment of the present application provides a method for leveling a strip, comprising: placing a leveled raw material roll on the reel of a uncoiler, and passing one end of the strip through a leveling working roller to a coiler, and then starting the machine for leveling; wherein the leveled raw material roll comprises an outer ring strip and an inner ring strip from the outer ring to the inner ring, the leveling speed of the outer ring strip is 20 to 150 m / min, the leveling speed of the inner ring strip is 20 to 60 m / min, the uncoiling tension of the outer ring strip is 20 to 40 KN, and the uncoiling tension of the inner ring strip is 50 to 120 KN.

[0006] In any embodiment of the present application, the outer ring strip steel includes, from the outside to the inside, a first strip steel section located at 0 to 50 meters of the outer ring of the flat raw material roll and a second strip steel section located at 50 meters of the outer ring of the flat raw material roll to 150 meters of the inner ring, and the inner ring strip steel includes, from the outside to the inside, a third strip steel section located at 150 meters of the inner ring of the flat raw material roll to 100 meters of the inner ring, a fourth strip steel section located at 100 meters of the inner ring of the flat raw material roll to 50 meters of the inner ring, and a fifth strip steel section located at 50 meters of the inner ring of the flat raw material roll to 0 meters of the inner ring; wherein, the flattening speed of the first strip steel section is 20 to 60 m / s. min, the leveling speed of the second strip section is 60~150m / min, the leveling speed of the third strip section is 40~60m / min, the leveling speed of the fourth strip section is 20~40m / min, the leveling speed of the fifth strip section is 20~40m / min, the uncoiling tension of the first strip section is 20~40KN, the uncoiling tension of the second strip section is 20~40KN, the uncoiling tension of the third strip section is 50~70KN, the uncoiling tension of the fourth strip section is 70~90KN, and the uncoiling tension of the fifth strip section is 90~120KN.

[0007] In any embodiment of the present application, before starting the machine for leveling, the reel of the uncoiler is also rotated in the direction of the coiling of the coiler, so as to drive the inner ring of the leveled raw material roll to rotate and expand.

[0008] In any embodiment of the present application, after the inner ring of the flat raw material roll is driven to rotate and expand, the process further includes expanding the reel of the uncoiler to expand the inner ring of the raw material roll.

[0009] In any embodiment of the present application, after one end of the steel strip is passed through the leveling work roll and fed to the coiler, a static tension of 20 to 40 KN is applied to the steel strip.

[0010] In any embodiment of the present application, after applying static tension to the steel strip, the method further includes applying pressure and bending roll force to the steel strip.

[0011] In any embodiment of the present application, before starting the machine for leveling, the coiling tension of the uncoiler is 60 to 80 KN, and the uncoiling tension of the coiler is 20 to 40 KN.

[0012] In any embodiment of the present application, a straightening machine is further provided between the uncoiler and the smooth working roll, and a pinch tension device is further provided between the coiler and the smooth working roll.

[0013] In any embodiment of the present application, the yield rate of the flattened steel strip is 99.80% to 99.90%.

[0014] In a second aspect, an embodiment of the present application provides a steel strip obtained by the above-mentioned flattening method.

[0015] The strip steel and the flattening method of the embodiment of the present application perform multi-stage control on the strip steel: a high-speed and low-tension mode is adopted on the outer ring of the flattened raw material coil to improve the damage; a mode of reducing the speed and gradually increasing the unwinding tension is adopted on the inner ring of the flattened raw material coil to improve the plate shape. The flattening speed is guaranteed as a whole, and the flattening yield rate can be increased while the flattening efficiency is improved, thereby maximizing the economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 A schematic diagram of the structure of the flattening process of some embodiments of the present application;

[0018] Figure 2 It is the tension curve diagram of the uncoiler in Example 1;

[0019] Figure 3 It is the speed curve diagram of the uncoiler in Example 1;

[0020] Figure 4 It is the tension curve diagram of the unwinder in Comparative Example 1;

[0021] Figure 5 This is the speed curve of the uncoiler in Comparative Example 1. DETAILED DESCRIPTION

[0022] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the scheme of the present application will be further described below. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0023] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present application may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present application, rather than all of the embodiments.

[0024] Hereinafter, the embodiments of the strip steel and the flattening method thereof of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0025] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] If not otherwise specified, all embodiments and optional embodiments of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0027] Unless otherwise specified, all technical features and optional technical features of the present application may be combined with each other to form a new technical solution, and such a technical solution should be deemed to be included in the disclosure of the present application.

[0028] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0029] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0030] Unless otherwise specified, this application adopts conventional test methods or test methods recommended by the instrument.

[0031] When flattening thin-gauge high-strength steel, similar steel mills at home and abroad usually adopt two methods: "reducing the flattening speed" and "reducing the unwinding tension". However, reducing the flattening speed will result in low production efficiency; reducing the unwinding tension will result in low yield rate.

[0032] This application analyzes the serious deficiencies of the above two control measures for improving the flatness of the strip shape in actual use, combines the characteristics of the existing equipment layout on site, and performs multi-stage control of the strip.

[0033] Leveling method

[0034] A method for leveling strip steel comprises: placing a leveling raw material coil on a reel of an unwinder, passing one end of the strip steel through a leveling working roller to a coiler, and then starting the machine for leveling; wherein the leveling raw material coil comprises an outer ring strip steel and an inner ring strip steel in sequence from the outer ring to the inner ring, the leveling speed of the outer ring strip steel is 20 to 150 m / min, the leveling speed of the inner ring strip steel is 20 to 60 m / min, the unwinding tension of the outer ring strip steel is 20 to 40 KN, and the unwinding tension of the inner ring strip steel is 50 to 120 KN. Optionally, the smoothing speed of the outer ring strip is independently selected from any value among 20m / min, 25m / min, 30m / min, 35m / min, 40m / min, 45m / min, 50m / min, 55m / min, 60m / min, 65m / min, 70m / min, 75m / min, 80m / min, 85m / min, 90m / min, 95m / min, 100m / min, 105m / min, 110m / min, 115m / min, 120m / min, 125m / min, 130m / min, 135m / min, 140m / min, 145m / min, 150m / min or any range value between two of them. Optionally, the leveling speed of the inner ring steel strip is independently selected from any value among 20m / min, 25m / min, 30m / min, 35m / min, 40m / min, 45m / min, 50m / min, 55m / min, 60m / min or any range between two values. Optionally, the unwinding tension of the outer ring steel strip is independently selected from any value among 20KN, 21KN, 22KN, 23KN, 24KN, 25KN, 26KN, 27KN, ​​28KN, 29KN, 30KN, 31KN, 32KN, 33KN, 34KN, 35KN, 36KN, 37KN, 38KN, 39KN, 40KN or any range between two values. Optionally, the uncoiling tension of the inner ring strip is independently selected from any value among 50KN, 55KN, 60KN, 65KN, 70KN, 75KN, 80KN, 85KN, 90KN, 95KN, 100KN, 105KN, 110KN, 115KN, 120KN or any range value between two of them.

[0035] like Figure 1 As shown, the flattened raw material roll 1 is placed on the reel of the uncoiler, one end of the strip passes through the flattening working roller 2, and is threaded onto the coiler 3, and then the machine is started for flattening.

[0036] Outer ring strip steel and inner ring strip steel refer to: after the strip steel is rolled up from the flat raw material coil, it forms a narrow and long thin plate. According to the order of unfolding, the two ends in the unfolding direction are called the head and tail ends. Among them, the strip steel between the head end and a certain point in the middle is called the outer ring strip steel, and the strip steel between the tail end and a certain point in the middle is called the inner ring strip steel.

[0037] The leveling speed refers to the speed at which the strip passes through the leveling work roll. The unwinding tension is provided by the coiler.

[0038] The present application adopts a high-speed and low-tension mode for the outer ring of the flat raw material roll, and adopts a mode of reducing speed and gradually increasing unwinding tension for the inner ring of the flat raw material roll, thereby improving production efficiency and improving the yield rate, thereby achieving good economic benefits.

[0039] In some embodiments, the strip threading needs to be completed in one go (even if it cannot be completed in one go, the number of times the strip threading is performed should be reduced as much as possible), and the number of operations on the strip pressure head and the insertion jaws is less than or equal to two times, which can avoid the strip from sliding between other working rollers and causing contusions.

[0040] In some embodiments, the outer ring steel strip includes, from the outside to the inside, a first steel strip section located at 0 to 50 meters of the outer ring of the flat raw material coil and a second steel strip section located at 50 meters of the outer ring to 150 meters of the inner ring of the flat raw material coil, and the inner ring steel strip includes, from the outside to the inside, a third steel strip section located at 150 meters of the inner ring to 100 meters of the inner ring of the flat raw material coil, a fourth steel strip section located at 100 meters of the inner ring to 50 meters of the inner ring of the flat raw material coil, and a fifth steel strip section located at 50 meters of the inner ring to 0 meters of the inner ring of the flat raw material coil; wherein, the flattening speed of the first steel strip section is 20 to 60 m / mi n, the leveling speed of the second strip section is 60~150m / min, the leveling speed of the third strip section is 40~60m / min, the leveling speed of the fourth strip section is 20~40m / min, the leveling speed of the fifth strip section is 20~40m / min, the uncoiling tension of the first strip section is 20~40KN, the uncoiling tension of the second strip section is 20~40KN, the uncoiling tension of the third strip section is 50~70KN, the uncoiling tension of the fourth strip section is 70~90KN, and the uncoiling tension of the fifth strip section is 90~120KN.

[0041] After the strip steel coiled from the flat raw material coil is unrolled, a narrow and long thin plate is formed. The two ends in the unrolling direction are called the first and last ends according to the order of unrolling. Between the first and last ends, several adjacent strip steel segments can be sequentially divided in the unrolling direction. The speed and coiling force of each strip steel segment passing through the flat work roll are specially set to achieve the optimal overall performance, thereby better improving production efficiency and yield rate.

[0042] In some embodiments, before starting the machine for leveling, the reel of the unwinder is rotated in the direction of the coiling of the coiler to drive the inner ring of the leveled raw material coil to rotate and expand, so as to avoid relative sliding after starting the machine to unwind the coil, thereby preventing the strip surface from being bruised.

[0043] In some embodiments, after the inner ring of the flat raw material coil is driven to rotate and expand, the reel of the unwinder is further expanded to expand the inner ring of the raw material coil, so as to avoid relative sliding after the start of the machine and the unwinding, thereby preventing the strip surface from being bruised.

[0044] In some embodiments, before starting the machine for leveling, it also includes rotating the reel of the uncoiler in the direction of the winding of the coiler, driving the inner ring of the leveled raw material roll to rotate and expand, and during the rotation of the reel of the leveling uncoiler, the reel of the uncoiler is expanded to expand the inner ring of the leveled raw material roll.

[0045] During the expansion of the coil, the inner circle of the flat raw material coil can be gradually expanded and the flat raw material coil can be tightened to avoid relative sliding after the coil is loosened when the machine is started, thereby avoiding bruising on the strip surface.

[0046] Since the inner ring of the flat raw material roll has been expanded during the rotation of the roll of the flat uncoiler, the sliding of the layers of the flat raw material roll and the resulting bruising can be avoided when the roll is expanded. Since the roll is constantly rotating during expansion, it can drive the inner ring of the flat raw material roll to rotate together. Compared with directly expanding the roll without rotating the roll, the pressure between the layers of the inner ring of the flat raw material roll is smaller during the expansion process, and no bruising will occur (direct expansion lacks the tangential traction of the raw material roll, and the pressure of the inner ring will directly act on the outer ring during the expansion process, and sliding will also occur).

[0047] In some embodiments, after one end of the steel strip is passed through the leveling work roll to the coiler, a static tension of 20 to 40 KN is applied to the steel strip. Optionally, the static tension is independently selected from any value of 20 KN, 21 KN, 22 KN, 23 KN, 24 KN, 25 KN, 26 KN, 27 KN, 28 KN, 29 KN, 30 KN, 31 KN, 32 KN, 33 KN, 34 KN, 35 KN, 36 KN, 37 KN, 38 KN, 39 KN, 40 KN or any range between two values. The static tension can be applied by the uncoiler and the coiler.

[0048] In some embodiments, after applying static tension to the steel strip, the method further includes applying pressure and bending roll force to the steel strip.

[0049] At this time, since static tension is applied first, the strip will be tensioned, and when the bending roller force is applied again, the strip will not slide due to pulling, thus avoiding contusion. It should be noted that the use of bending roller force is manually controlled. The current operation method is to gradually press down the deep bending roller after starting the machine or during the starting process. If there is no static tension on the strip, it will be impossible to avoid the looseness and redundancy of the strip in the leveling equipment. After the deep bending roller is pressed down, the strip will slide during the tensioning process, causing contusion. In addition, if static tension is applied after starting the machine, due to the limited control accuracy of the equipment speed, pressure on the strip, etc., there will also be sliding, and contusion is difficult to avoid.

[0050] In some embodiments, before starting the machine for leveling, the coiling tension of the uncoiler is 60-80 KN, and the uncoiling tension of the coiler is 20-40 KN.

[0051] like Figure 1 As shown, in some embodiments, a straightening machine 4 is provided between the uncoiler 1 and the smooth working roll 2, a clamping tension device 5 is provided between the coiler 3 and the smooth working roll 2, and a hydraulic cross-cutting shear 6 is provided between the smooth working roll 2 and the clamping tension device 5.

[0052] In some embodiments, the yield of the flattened steel strip is 99.80% to 99.90%. Optionally, the yield of the flattened steel strip is independently selected from any value among 99.80%, 99.81%, 99.82%, 99.83%, 99.84%, 99.85%, 99.86%, 99.87%, 99.88%, 99.89%, 99.90%, or any range between two values.

[0053] Strip Steel

[0054] A steel strip obtained by the flattening method described above.

[0055] Strip steel is a narrow and long steel plate produced by various steel rolling enterprises to meet the needs of industrialized production of various metal or mechanical products in different industrial sectors. Strip steel is also called steel strip, with a width of less than 1300mm and a length slightly different depending on the size of each roll.

[0056] Example 1

[0057] In the flattening workshop of Liangang hot-rolled plate mill, flattening is carried out according to the following procedures. The specification of the flattened raw material coil is 2.6*1363mm DP980-1 high-strength steel:

[0058] 1. The flat raw material roll is placed in the flat uncoiler by the roll transport trolley, and the reel of the flat uncoiler is rotated in the direction of the coiling of the coiler, driving the inner ring of the flat raw material roll to rotate and expand.

[0059] 2. During the rotation of the reel of the flat uncoiler, the reel expands to tighten the inner ring of the flat raw material roll.

[0060] 3. The flat raw material roll is threaded from the uncoiler to the coiler and rotated 2 times on the coiler.

[0061] 4. Apply a static tension of 25kN to the strip after threading.

[0062] 5. After static tension is applied, press down the leveling working roller.

[0063] 6. The coiling tension of the strip is 70kN and the uncoiling tension is 25kN.

[0064] 7. Start the leveling working roller.

[0065] 8. When leveling the 0-50m section of the outer ring of the leveled raw material roll, the leveling speed is 30m / min and the unwinding tension remains unchanged at 25KN.

[0066] 9. When leveling the section from 50 meters on the outer circle to 150 meters on the inner circle of the leveled raw material roll, the leveling speed is 65m / min and the unwinding tension is 30KN.

[0067] 10. When leveling the section from 150m to 100m of the inner circle of the leveling raw material roll, the leveling unit slows down to 50m / min and the unwinding tension increases to 60KN.

[0068] 11. When leveling the section from 100m to 50m of the inner circle of the leveling raw material roll, the leveling unit slows down to 30m / min and the unwinding tension increases to 80KN.

[0069] 12. When leveling the 50-meter section of the inner circle of the flat raw material roll, the leveling unit slows down to 30m / min and the unwinding tension increases to 100KN until the raw material roll is leveled.

[0070] During the leveling process, the tension curve and speed curve of the uncoiler are as follows: Figure 2 and Figure 3 As shown, the yield rate of the flattened strip steel was tested. The weight of the inlet raw strip steel was 22.86t, the weight of the outlet finished strip steel was 22.82t, and the yield rate was 99.83%.

[0071] Comparative Example 1

[0072] In the flattening workshop of Liangang Hot Rolling Plant, the flattening is carried out according to the following procedures. The specification of the flattened raw material coil is 2.7*1140mm DP980-1 high-strength steel:

[0073] 1. The flat raw material coil is placed in the flat uncoiler by the coil transport trolley, and the reel of the flat uncoiler is rotated in the direction of the coiling of the coiler, driving the inner ring of the raw material coil to rotate and expand.

[0074] 2. During the rotation of the reel of the leveling uncoiler, the reel expands, causing the inner circle of the raw material roll to expand.

[0075] 3. The flat raw material roll is threaded on the uncoiler to the exit coiler and rotated 2 circles on the exit coiler.

[0076] 4. Apply a static tension of 40kN to the strip after threading.

[0077] 5. After static tension is applied, press down the leveling working roller.

[0078] 6. The coiling tension of the strip is 40kN and the uncoiling tension is 40kN.

[0079] 7. Start the leveling working roller.

[0080] 8. During the leveling process, the unwinding tension of the strip is kept constant at 40kN along the entire length.

[0081] 9. The length from the outer coil to the inner coil of the flattened raw material roll is 150m, and the flattening speed is 50m / min.

[0082] 10. When the inner circle is leveled to 150m, due to slight deviation and contusion of the strip, the leveling unit slows down to 30-35m / min, and the unwinding tension remains unchanged at 40kN. The subsequent strip deviates and is severely contused, so the tail of about 120m is cut off (waste roll).

[0083] During the leveling process, the tension curve and speed curve of the uncoiler are as follows: Figure 4 and Figure 5 As shown, the yield rate of the flattened strip steel was tested. The weight of the inlet raw strip steel was 21.41t, the weight of the outlet finished strip steel was 18.595t, and the yield rate was 86.9%.

[0084] It can be seen from Example 1 and Comparative Example 1 that the method for controlling the strip shape provided in the present application can effectively reduce the surface defects of the strip during the uncoiling and flattening process, improve the surface quality of the strip, and improve the yield rate of the strip. At the same time, it can also ensure that the strip has a high production efficiency and effectively reduce production costs.

[0085] The above is only a specific implementation of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in this application, and these modifications or replacements should be included in the protection scope of this application.

Claims

1. A method for flattening a steel strip, characterized in that: include: Place the flat raw material coil on the reel of the uncoiler, and pass one end of the strip through the flat working roller to the coiler, and then start the machine for flattening; Among them, the flattened raw material roll includes outer ring strip steel and inner ring strip steel from outer ring to inner ring, the flattening speed of the outer ring strip steel is 20-150m / min, the flattening speed of the inner ring strip steel is 20-60m / min, the uncoiling tension of the outer ring strip steel is 20-40KN, and the uncoiling tension of the inner ring strip steel is 50-120KN.

2. The leveling method according to claim 1, characterized in that: The outer ring steel strip includes, from the outside to the inside, a first steel strip section located at 0 to 50 meters of the outer ring of the flat raw material roll and a second steel strip section located at 50 meters of the outer ring to 150 meters of the inner ring of the flat raw material roll; the inner ring steel strip includes, from the outside to the inside, a third steel strip section located at 150 meters of the inner ring to 100 meters of the inner ring of the flat raw material roll, a fourth steel strip section located at 100 meters of the inner ring to 50 meters of the inner ring of the flat raw material roll, and a fifth steel strip section located at 50 meters of the inner ring to 0 meters of the inner ring of the flat raw material roll; The leveling speed of the first steel strip segment is 20-60 m / min, the leveling speed of the second steel strip segment is 60-150 m / min, the leveling speed of the third steel strip segment is 40-60 m / min, the leveling speed of the fourth steel strip segment is 20-40 m / min, and the leveling speed of the fifth steel strip segment is 20-40 m / min. The uncoiling tension of the first steel strip segment is 20-40 KN, the uncoiling tension of the second steel strip segment is 20-40 KN, the uncoiling tension of the third steel strip segment is 50-70 KN, the uncoiling tension of the fourth steel strip segment is 70-90 KN, and the uncoiling tension of the fifth steel strip segment is 90-120 KN.

3. The leveling method according to claim 1, characterized in that: Before starting the machine for leveling, the reel of the uncoiler is rotated in the direction of the coiling of the coiler, so as to drive the inner ring of the leveled raw material coil to rotate and expand.

4. The leveling method according to claim 3, characterized in that: After the inner ring of the flat raw material roll is driven to rotate and expand, the method further includes expanding the reel of the uncoiler to expand the inner ring of the raw material roll.

5. The leveling method according to claim 1, characterized in that: After one end of the strip is passed through the leveling work roll to the coiler, a static tension of 20 to 40 kN is applied to the strip.

6. The leveling method according to claim 5, characterized in that: After applying static tension to the strip, it also includes applying pressure and bending roll force to the strip.

7. The leveling method according to claim 1, characterized in that: Before starting the machine for leveling, the coiling tension of the uncoiler is 60-80KN, and the uncoiling tension of the coiler is 20-40KN.

8. The leveling method according to claim 1, characterized in that: A straightening machine is also provided between the uncoiler and the leveling working roll, and a pinching tension device is also provided between the coiler and the leveling working roll.

9. The leveling method according to claim 1, characterized in that: The yield rate of the flattened strip is 99.80% to 99.90%.

10. A steel strip obtained by the flattening method according to any one of claims 1 to 9.

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