Improve the control method of strip head mark of cold-rolled strip coiler

Abstract

This invention discloses a method for controlling strip head marks in cold-rolled strip coilers. This method utilizes a high-elasticity sleeve and eliminates strip head marks by setting tension during the tapered tension, high tension, and low tension coiling stages. Specifically, it includes: Coiling preparation stage: a preset tension T0 is used, and the tapered tension mode is activated when the strip thickness is ≥0.8mm; Tapered tension coiling stage: tension is established when the strip is wound to S1 turns, with tension T1 = 1.5–3.0 times T0, and S1 < 1 turn; High tension coiling stage: when winding to S2 turns, the tension is switched to T2 = 0.1–0.9 times T0, and S2 < 5 turns; Low tension coiling stage: when winding to S3 turns, the tension is switched back to T0, and S3 ≥ 5 turns; Constant tension coiling stage: coiling is completed at T0; where T0 = t × H × B, H is the thickness, B is the width, and t is the unit tension. This method effectively shortens the strip head mark area and reduces its severity through tension gradient adjustment and the use of a high-elasticity sleeve.

Description

Technical Field

[0001] This invention relates to the field of cold-rolled product coiling process control technology, and in particular to a method for improving the control of strip head marks in cold-rolled strip coiling machines. Background Technology

[0002] Lead mark defects are a common problem in the cold rolling coiling process. During the coiling of cold-rolled steel coils, the lead mark of the first coil forms a protrusion on the coiler's sleeve. This protruding area acts as a curvature abrupt change zone. When subsequent strip passes through this area, under the combined action of coiling tension and sleeve winding force, the strip in this protruding area undergoes a certain degree of plastic deformation. This deformation results in a transverse mark running through the width of the strip on each coil, commonly referred to in the industry as a "lead mark." The severity of the lead mark gradually decreases and eventually disappears as the coil diameter increases. Thicker strips exhibit more severe lead marks and longer areas of plastic deformation, negatively impacting subsequent deep processing, spraying, and baking processes. Long-term production experience shows that the lead mark problem is particularly prominent when the strip thickness reaches or exceeds 0.8 mm. Therefore, how to effectively shorten the length of the area where the imprint is generated and reduce the degree of imprint has become a control challenge that urgently needs to be solved in the winding process. Summary of the Invention

[0003] The purpose of this invention is to provide a method for improving the control of strip head marks in cold-rolled strip coilers. This method can solve the problems of long strip head mark generation areas and severe strip head mark severity in existing strips with a thickness of 0.8 mm or more.

[0004] To solve the above problems, the technical solution adopted by this invention is as follows: This method for improving the control of strip head marks in cold-rolled strip coiling machines utilizes a highly elastic sleeve outside the coiling machine mandrel. By setting the tension during the tapered tension coiling stage and adjusting the tensions during the high-tension and low-tension coiling stages, the strip head is embedded in the sleeve to eliminate strip head marks. The specific steps are as follows:

[0005] Step (1), Coiling preparation stage: preset the coiling tension T0 and determine the online strip thickness. When the strip thickness is <0.8mm, the constant tension coiling mode is adopted; when the strip thickness is ≥0.8mm, the tapered tension control mode is used for coiling.

[0006] Step (2), Taper tension winding stage: When the strip steel is wound around the sleeve to the preset number of turns S1, tension is established, and the tension is set to T1, S1 turns < 1 turn;

[0007] Step (3), High-tension winding stage: When the strip is wound around the sleeve to the preset number of turns S2, the winding stage is completed. Adjust the tension setting from T1 to T2, and S2 turns < 5 turns;

[0008] Step (4): When the tension is switched to T2 and the strip is wound around the sleeve to the preset number of turns S3, adjust the tension setting from T2 to T0, and S3 turns ≥ 5 turns;

[0009] Step (5): After the tension reaches the set value of T0, the strip is wound up at a constant tension of T0 until the winding of the strip ends;

[0010] In the above steps, T0 = t × H × B, where H is the strip thickness in mm; B is the strip width in mm; and t is the unit tension of the strip steel series in daN / mm².

[0011] Tension T1 > T0 > T2, where T1 is 1.5 to 3.0 times T0 and T2 is 0.1 to 0.9 times T0.

[0012] In the above-mentioned technical solution for improving the control method of the strip head mark of the cold-rolled strip coiler, a more specific technical solution may be: the coiler maintains a constant strip threading speed v during the process of steps (1) to (4); after entering step (5), the unit speeds up.

[0013] In some possible implementations, the threading speed v is in the range of 30 to 70 m / min.

[0014] In some possible implementations, the sleeve is a rubber sleeve.

[0015] In some possible implementations, the outer surface of the sleeve is provided with a number of spiral grooves.

[0016] In some possible implementations, the inner surface of the sleeve is provided with multiple straight grooves.

[0017] In some possible implementations, both the spiral groove and the straight groove have a circular arc structure.

[0018] By adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0019] 1. This invention utilizes the elastic properties of a high-elasticity sleeve, enabling it to better conform to the strip's head portion, ensuring the strip head is tightly embedded in the sleeve from the initial winding stage, thus reducing the formation of strip head marks. Furthermore, the high-elasticity sleeve effectively absorbs and disperses the impact force of the strip on the sleeve during winding, reducing stress concentration in the strip head area, thereby minimizing strip head marks. During the taper tension winding stage, a relatively high build-up tension T1 (1.5 to 3.0 times T0) is set to ensure the strip head is tightly embedded in the sleeve from the initial winding stage, reducing the area where strip head marks are generated. As the number of strip winding turns increases, the tension is gradually reduced to avoid excessive tension causing strip head marks. Plastic deformation reduces the degree of strip head marks. During the high-tension winding stage, when the strip is wound around the sleeve to the preset number of turns S2, the tension is switched from T1 to T2 to reduce the tension and ensure that the strip is evenly stressed during winding, thus reducing the generation of strip head marks. During the low-tension winding stage, when the strip is wound around the sleeve to the preset number of turns S3, the tension is switched from T2 to T0, and winding is completed at a constant tension of T0. This stable tension setting helps maintain the flatness of the strip and further reduces the generation of strip head marks. This method is simple to operate, suitable for actual production environments, and can significantly improve production efficiency and reduce downtime and scrap rates caused by strip head marks.

[0020] 2. In steps (1) to (4), maintaining a constant threading speed v can ensure that the strip is subjected to uniform stress in the initial stage of coiling, especially in the critical stage of the strip head embedding into the sleeve, and avoid tension instability caused by speed fluctuations. A stable threading speed helps the strip to fit tightly with the high elastic sleeve, reducing stress concentration in the strip head area, thereby effectively reducing the generation of strip head marks. In step (5), when the strip head mark problem has been basically solved and the strip coiling has entered a stable stage, the unit speed can be increased to improve production efficiency, while not having a negative impact on the control of strip head marks.

[0021] 3. Controlling the threading speed within the range of 30 to 70 m / min ensures both the stability of the winding process and the requirements of production efficiency. Within this range, a lower threading speed is suitable for the critical stage of the strip head embedding into the sleeve, ensuring a tight fit between the strip and the sleeve; a higher threading speed is suitable for the subsequent stable winding stage, improving production efficiency.

[0022] 4. The rubber sleeve has excellent elasticity and cushioning performance, which can effectively absorb the impact and vibration generated during the strip winding process, reduce stress concentration in the strip head area, and thus reduce the formation of strip head marks; the softness of the rubber material allows it to better fit the strip head part, ensuring that the strip head is tightly embedded in the sleeve in the early stage of winding, reducing the formation of strip head marks.

[0023] 5. The spiral groove design on the outer surface of the sleeve enables the strip to distribute tension evenly during the winding process, avoiding local stress concentration and thus reducing the generation of strip head marks; the straight groove design on the inner surface of the sleeve enhances the connection stability between the sleeve and the winding machine core shaft, preventing the sleeve from shifting or loosening during the winding process and ensuring the smoothness of the winding process.

[0024] 6. The spiral groove and straight groove have a circular arc structure, which can effectively reduce stress concentration on the strip and sleeve during the winding process and avoid strip damage or sleeve wear caused by sharp edges. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the winding tension and number of winding turns in this method.

[0026] Figure 2 This is a schematic diagram of the winding equipment used in this method.

[0027] Figure 3 This is a schematic diagram of the sleeve structure.

[0028] Figure 4 yes Figure 3 A side view diagram.

[0029] Explanation of reference numerals in the attached diagram: 1. Pressure roller; 2. Guide roller; 3. Strip steel; 4. Winding aid belt; 5. Sleeve; 5-1. Spiral groove; 5-2. Straight groove; 6. Winding machine core shaft. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0031] like Figure 2 As shown, the coiling equipment used in this improved method for controlling the strip head markings on a cold-rolled strip coiler includes a pressure roller 1, a guide roller 2, a coiling aid belt 4, a sleeve 5, a coiler mandrel 6, and a clamping device. The coiler mandrel 6 is located at the center of the coiler and is used to support and drive the coiling of the strip 3. The sleeve 5 is a highly elastic sleeve tightly fitted onto the coiler mandrel 6. In this embodiment, the sleeve 5 is a rubber sleeve, such as... Figure 3 and Figure 4As shown, to enhance the elasticity of the sleeve 5, several spiral grooves 5-1 are distributed on its outer surface. These spiral grooves 5-1 also increase the friction with the strip 3, helping the strip head to better embed into the sleeve 5. Furthermore, multiple straight grooves 5-2 are provided on the inner surface of the sleeve 5 to optimize its elasticity and deformation capacity. Both the spiral grooves 5-1 and the straight grooves 5-2 have a circular arc structure, which reduces stress concentration. The winding aid belt 4 is in close contact with the outer surface of the sleeve 5, and the tension is output through a tension adjustment valve. The pressure roller 1 and the guide roller 2 are located at the input end of the strip 3, used to feed the straight strip 3 into the coiler and apply a certain pressure so that the strip 3 can be tightly wound onto the sleeve 5. During the winding stage, the winding aid belt 4 is in close contact with the strip 3, helping the strip 3 to wind better onto the sleeve 5. As the winding process proceeds, the strip gradually forms a coil on the sleeve. The clamping device is located at the output end of the coiler and is used to maintain the stability of the strip 3 during the coiling process, preventing the strip 3 from shifting or loosening during the coiling process.

[0032] This improved method for controlling strip head marks in cold-rolled strip coilers utilizes a highly elastic sleeve outside the coiler's mandrel. By setting the tension during the tapered tension coiling stage and adjusting the tensions during the high-tension and low-tension coiling stages, the strip head is embedded in the sleeve to eliminate strip head marks. The specific steps are as follows:

[0033] Step (1), Coiling Preparation Stage: Preset the coiling tension T0. This tension is calculated based on the strip thickness H, strip width B, and the unit tension t of the steel grade series. The calculation formula is T0 = t × H × B, where the unit of strip thickness H is mm, the unit of strip width B is mm, and the unit tension t of the steel grade series is daN / mm². Simultaneously, determine the thickness of the strip on the line. When the strip thickness < 0.8 mm, use constant tension coiling mode; when the strip thickness ≥ 0.8 mm, use tapered tension control mode for coiling. See [link to relevant documentation]. Figure 1 During this stage, the pressure rollers and guide rollers involved in the winding assist perform the pressing action, and the straight strip steel needs to be wound into a coil by the clamping device of the coiler; when the clamping device is closed, the winding assist belt is tightly attached to the sleeve, and the winding assist belt achieves tension output through the tension adjustment valve;

[0034] Step (2), Tapered tension winding stage: When the strip steel is wound around the sleeve to the preset number of turns S1, tensioning begins. S1 turns < 1 turn, and the tensioning is set to T1, T1 > T0. T1 is 1.5 to 3.0 times T0. During the rapid tensioning process of S1 turns, the strip head maintains its own inertia and is simultaneously subjected to the combined action of large winding tension, the tension of the winding belt and the torque of the mandrel. The resulting instantaneous change in force embeds the strip head into the soft sleeve.

[0035] Step (3), High-tension winding stage: When the strip is wound around the sleeve to the preset number of turns S2, the winding stage is completed, S2 turns < 5 turns; at this time, adjust the tension setting from T1 to T2, T0 > T2, T2 is 0.1 to 0.9 times T0, at the same time, the pressure roller and the steering roller are opened, the clamping device is also opened, and the winding belt is unloaded;

[0036] Step (4), tension switching and adjustment stage: When the tension is switched to T2 and the strip is wound around the sleeve to the preset number of turns S3, the tension setting is adjusted from T2 back to T0, and S3 turns ≥ 5 turns; by rapidly decreasing the tension value, an artificial relatively loose winding area is created in the area between S2 turns and S3 turns, which is used to quickly alleviate the plastic deformation area of ​​the strip head protrusion, and to basically control the strip head print defect within the "hard core" of T1 high tension and the "soft area" of T2 low tension;

[0037] Step (5), constant tension winding stage: After the tension is adjusted to the T0 set value, the strip is wound at a constant tension of T0 until the winding of the strip ends;

[0038] In the above steps, the winding machine maintains a constant threading speed v during steps (1) to (4), and the threading speed v is in the range of 30 to 70 m / min; after entering step (5), the unit speeds up to the normal production speed at this stage.

[0039] The tension experienced by the strip steel during continuous hot-dip galvanizing is actually the sum of the stresses on its cross-section. To achieve flatness and stable coiling of the strip steel, the tension should be controlled within a reasonable range. Because the cross-section of the produced strip steel changes very frequently, continuous lines establish a matrix-style unit tension baseline table based on practical experience to better maintain the tension regime.

[0040] Examples 1 to 10 take the application of this method to the coiling of CQ series steel grades on a 0.4 to 2.5 × 1880 mm continuous hot-dip galvanizing unit coiling production line as an example. Table 1 is the unit tension table for the continuous unit coiling area of ​​this steel grade.

[0041] Table 1

[0042]

[0043] Example 1

[0044] CQ series strip steel with a thickness of 0.4 mm and a width of 1800 mm is coiled, with a base surface tension of 31.2 daN / mm. 2 Therefore, the winding tension T0 = t × H × B = 31.2 da N / mm 2 ×0.4mm×1800mm=22464N; the strip thickness is <0.8mm, and a constant tension winding mode is adopted, with the winding machine maintaining a constant threading speed of 30m / min. For example... Figure 1 As shown, this embodiment uses thin strip steel with a thickness of <0.8mm, which has a smaller impact from the strip head mark. The winding method shown in the dotted line is adopted, which means that the winding tension is increased starting from turn S2 (within the range of 1 to 5 turns), and the winding starts to stabilize when the tension reaches T0. Figure 1 S4 represents the number of winding turns from tension 0 to tension T1, which is between S1 and S2 turns; S5 represents the number of winding turns from tension T1 to T2, which is between S2 and S3 turns.

[0045] Examples 2 to 4 describe the coiling of CQ series strip steel with a thickness range of [0.80~1.49] mm. The tension settings and variations during the coiling process in these examples are as follows:

[0046]

[0047] Examples 5 to 7 describe the coiling of CQ series strip steel with a thickness range of [1.50~1.99] mm. The tension settings and variations during the coiling process in these examples are as follows:

[0048]

[0049] Examples 8 to 10 describe the coiling of CQ series strip steel with a thickness range of [2.00~2.50] mm. The tension settings and variations during the coiling process in these examples are as follows:

[0050]

[0051] In the above embodiments, the coiling tension T0 is calculated based on the strip thickness, width, and base surface unit tension. S1 represents the number of turns at which tension is initially established. As the thickness of the coil increases, the number of turns at the start of tension establishment (S1) gradually decreases because thicker strips can form a stable coil shape more quickly in the early stages of coiling, allowing tension to be applied earlier. The high tension T1 in stage 1 is a multiple of T0, used to provide sufficient tension in the early stages of coiling to ensure stable coiling of the strip. As the strip thickness increases, the multiple of the high tension T1 relative to the initial tension T0 decreases because thicker strips have stronger structural stability during coiling and do not require excessive tension to maintain the embedded state of the strip head. The low tension T2 in stage 2 is another multiple of T0, used to appropriately reduce tension during coiling to reduce strip deformation and damage. The multiple of the low tension T2 relative to T0 increases with the increase of strip thickness. If thicker strips require more time to alleviate the plastic deformation zone of the strip head protrusion, then T2 will increase relative to T0. S2 represents the number of turns for tension reduction. S2 gradually increases with the increase of strip thickness because thicker strips require more time to adapt to tension changes and remain stable. S3 represents the number of turns for tension to be increased to T0. S3 gradually decreases with the increase of strip thickness because thicker strips have stronger structural stability during winding, allowing the tension to be restored to the initial value T0 earlier. Ultimately, the strip is wound up at a constant tension of T0.

[0052] By uncoiling and oilstone polishing inspections of the CQ series steel grades in Examples 2 to 10, the length of the strip head mark area was controlled within 15 meters for steel coils with a thickness range of [0.80~1.49] mm; within 25 meters for steel coils with a thickness range of [1.50~1.99] mm; and within 30 meters for steel coils with a thickness range of [2.00~2.50] mm. This demonstrates that the adopted coiling method and tension control strategy are effective in improving the coiling quality of the strip and reducing the length of the strip head mark.

[0053] Examples 11 to 19 illustrate the application of this method to the coiling of IF series steel grades on a continuous hot-dip galvanizing line of 0.4 to 2.5 × 1880 mm. Table 2 shows the unit tension baseline for the continuous coiling area of ​​this steel grade.

[0054] Table 2

[0055]

[0056] Examples 11 to 13 describe the winding of IF series strip steel with a coil thickness ranging from [0.80 to 1.49] mm. The tension settings and variations during the winding process in these examples are as follows:

[0057]

[0058] Examples 14 to 16 describe the winding of IF series strip steel with a coil thickness ranging from 1.50 to 1.99 mm. The tension settings and variations during the winding process in these examples are as follows:

[0059]

[0060] Examples 17 to 19 describe the winding of IF series strip steel with a coil thickness ranging from [2.00 to 2.50] mm. The tension settings and variations during the winding process in these examples are as follows:

[0061]

[0062] By uncoiling and oilstone polishing inspections of the IF series steel grades in Examples 2 to 10, the length of the lead mark on steel coils with a thickness of [0.80~1.49] was controlled within 20 meters; the length of the lead mark on steel coils with a thickness of [1.50~1.99] was controlled within 35 meters; and the length of the lead mark on steel coils with a thickness of [2.00~2.50] was controlled within 45 meters. The control and elimination of the lead mark were significantly effective, achieving a relatively optimal control level.

Claims

1. A method for improving the control of strip head marks in a cold-rolled strip coiler, characterized in that: By utilizing a highly elastic sleeve outside the winding machine's core shaft, and by setting the tension during the taper tension winding stage and adjusting the tensions during the high-tension and low-tension winding stages, the tape head is embedded into the sleeve to eliminate tape head marks. The specific steps are as follows: Step (1), Coiling preparation stage: preset the coiling tension T0 and determine the online strip thickness. When the strip thickness is <0.8mm, the constant tension coiling mode is adopted; when the strip thickness is ≥0.8mm, the tapered tension control mode is used for coiling. Step (2), Taper tension winding stage: When the strip steel is wound around the sleeve to the preset number of turns S1, the tension is set to T1, and S1 turns < 1 turn; Step (3), High-tension winding stage: When the strip is wound around the sleeve to the preset number of turns S2, the winding stage is completed. Adjust the tension setting from T1 to T2, and S2 turns < 5 turns; Step (4), low tension winding stage: when the tension is switched to T2 and the strip is wound around the sleeve to the preset number of turns S3, adjust the tension setting from T2 to T0, and S3 turns ≥ 5 turns; Step (5): After the tension reaches the set value T0, the strip is wound up at a constant tension T0 until the winding of the strip ends; In the above steps, T0 = t × H × B, where H is the strip thickness in mm; B is the strip width in mm; and t is the unit tension of the strip steel series in daN / mm². Tension T1 > T0 > T2, where T1 is 1.5 to 3.0 times T0 and T2 is 0.1 to 0.9 times T0.

2. The method for improving the control of strip head marks in a cold-rolled strip coiler according to claim 1, characterized in that: During steps (1) to (4), the winding machine maintains a constant threading speed v; after entering step (5), the unit speeds up.

3. The method for improving the control of strip head marks in a cold-rolled strip coiler according to claim 2, characterized in that: The threading speed v is in the range of 30 to 70 m / min.

4. The method for improving the control of strip head marks in a cold-rolled strip coiler according to any one of claims 1 to 3, characterized in that: The sleeve is a rubber sleeve.

5. The method for improving the control of strip head marks in a cold-rolled strip coiler according to claim 4, characterized in that: The outer surface of the sleeve has several spiral grooves.

6. The method for improving the control of strip head marks in a cold-rolled strip coiler according to claim 5, characterized in that: The inner surface of the sleeve is provided with multiple straight grooves.

7. The method for improving the control of strip head marks in a cold-rolled strip coiler according to claim 6, characterized in that: Both the spiral groove and the straight groove have a circular arc structure.

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