A method for continuous skin pass production line to produce thin gauge hot-rolled checkered plate skin pass

Abstract

The application discloses a method for continuously and flatly producing thin-specification hot-rolled pattern plates on a production line, and belongs to the field of steel production. The technological process comprises the following steps: uncoiling, welding, tension leveling, unevenness, slitting and coiling. When welding, the welding thickness of the front and rear two coils of materials is required to be less than or equal to 0.2 mm in difference from the base plate thickness. The thickness of the hot-rolled pattern plate raw material is compensated by 0.2 mm by using the internal electrical program of the welding machine as the welding parameter. When tension leveling, the strip shape is straightened by a tension leveler, and no flattener is used. The welding seam passes through the tension leveler in an open mode. Compared with the prior art, the application can realize the continuous production of the thin-specification pattern plates on the flattening production line.

Description

Technical Field

[0001] This invention relates to a steel production method, and in particular to a process method for improving the flattening production of thin-gauge hot-rolled patterned plates on a continuous flattening production line, based on the successful development of patterned plate products with a thickness of less than 1.8 μm in the previous process. Background Technology

[0002] Currently, the majority of hot-rolled patterned steel sheets on the market are >2.0mm thick. To enhance the competitiveness of hot-rolled patterned steel sheets in the market, the previous process successfully developed thin-gauge patterned steel sheets with a thickness ≤2.0mm for low-carbon steel, extending the minimum thickness specification to 0.7mm. When producing thin-gauge patterned steel sheets ≤2.0mm thick, especially the extremely thin specifications of 0.7-1.2mm, significant edge waviness occurs in the later stages of rolling, requiring leveling to meet customer requirements. Currently, when leveling on a single-stand leveling machine, the sheet shape qualification rate for thin-gauge patterned steel sheets is only 85%. To improve the sheet shape qualification rate for thin-gauge patterned steel sheets, sheets ≤1.8mm thick need to be transferred to a continuous leveling production line equipped with a straightening machine to improve production efficiency. However, due to the patterned surface structure of hot-rolled patterned steel sheets, with a pattern bead height ≥0.2mm, there are risks associated with welding on the production line, tracking tailing, and wear of the production line rollers. In addition, due to the influence of the height of hot-rolled patterned steel strip, the existing method of calculating the length of the patterned steel strip is inaccurate. The tailing at the exit of the production line is prone to over-tailing, resulting in abnormalities such as inaccurate coiling and weight discrepancies.

[0003] To meet customers' demands for thinner patterned steel sheets, while also ensuring the sheet shape quality of thin patterned steel sheets with a thickness of ≤1.8mm, there is an urgent need for a process method that can be applied to existing continuous leveling production lines for leveling production. Summary of the Invention

[0004] The technical objective of this invention is to address the shortcomings of the prior art by providing a method for the continuous leveling production line of thin-gauge hot-rolled patterned steel sheets. This invention achieves continuous welding production of thin-gauge patterned steel sheets on a leveling production line by optimizing welding machine parameters and modifying the patterned steel sheet length cutting function.

[0005] The technical solution of this invention to solve its technical problem is:

[0006] A method for producing thin-gauge hot-rolled patterned steel plates using a continuous leveling production line, characterized in that the process flow includes: uncoiling → welding → tension leveling → unevenness → slitting → coiling.

[0007] S1. Open the book;

[0008] S2. Welding: The thickness difference between the two substrates of the two rolls must be ≤0.2mm; the thickness of the hot-rolled patterned plate raw material is compensated by 0.2mm using the internal electrical program of the welding machine as the welding parameter;

[0009] S3. Straightening: Straighten the shape of the strip steel plate using a straightening machine, without using a leveling machine; the weld seam is straightened in open mode using the straightening machine.

[0010] S4. Slitting and winding.

[0011] In the above welding process, when the patterned plate is welded to the plain steel coil without pattern, the difference in yield strength between the two coils is less than 200MPa.

[0012] The welding machine's rolling roller is not used in the above welding process.

[0013] When the thickness of the patterned plate is 0.8-1.8mm, the tension straightening process parameters are set as follows: tension straightening elongation 0.3-0.5%, bending crossover 18-20mm, and straightening crossover 23-26mm.

[0014] The working roller diameter of the bending unit of the above-mentioned tension leveling machine is 100mm.

[0015] Before the above straightening process, cut a crescent-sized weld template for each roll and conduct a weld bending test.

[0016] A method for calculating the length of a patterned plate in a slitting and winding process, characterized in that: the formula for calculating the length of the patterned plate is:

[0017] L1=∣Δn2∣×imp2out×π×d2

[0018] Wherein, Δn2 is the pulse value of the encoder within the cycle; the cycle refers to the CPU scan cycle of 0.02 seconds; imp2out is the length of a pulse, which is equal to πd2×τ2 / 1024; d2 is the diameter of tension roller No. 2 in tension roller group No. 6, and τ2 is the reduction ratio of tension roller No. 2 in tension roller group No. 6; the tension roller group No. 6 is located between the leveling machine and the slitting shear.

[0019] Compared with the prior art, the present invention has the following outstanding advantages:

[0020] 1. Utilize the existing continuous leveling production line of cold rolling operation to produce thin-gauge hot-rolled patterned plates, with a plate shape qualification rate of 100%.

[0021] 2. Reduced surface unevenness of the pattern, which poses risks to welding machines and roller wear on the production line; 3. The new calculation method reduces the incidence of inaccurate slitting and tailing during production line tracking. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the production line structure of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, the present invention utilizes an existing continuous leveling production line for cold rolling operations. The production line includes an uncoiler 1, a flying shear 2, a welding machine 3, an inlet looper, a tension leveler 4, a leveler 5, a slitting shear 7, and a coiler 8.

[0025] The process flow of this invention includes: uncoiling → welding → tension leveling → unevenness adjustment → slitting → winding.

[0026] S1, Open Book

[0027] Uncoiler 1 performs uncoiling operations on raw steel coils; flying shear 2 cuts off defects at the beginning and end of the coils to facilitate welding operations.

[0028] S2, Welding

[0029] The two steel coils are welded together by welding machine 3, enabling the unit to produce continuously.

[0030] Due to the varying surface roughness (≥0.2mm) of hot-rolled patterned steel strips, the risks associated with the roller system and welding machine must be fully considered during production. The uneven surface roughness of the patterned steel strip means the weld center melting point cannot remain on a straight line during welding, posing a risk of weld breakage. Furthermore, the production process can cause wear on the process rollers, potentially shortening their service life.

[0031] 1. Control the thickness of the steel coils before and after welding.

[0032] During the welding process, the thickness information received by the welding machine is the thickness of the substrate. In the welding process of ordinary low carbon steel with a thickness of <3.0mm, the thickness difference between the two steel coils is limited to ≤30% and ≤1.0mm, and the strength difference between the two steel coils before and after welding is ≤200MPa.

[0033] However, due to the influence of the cup height of the patterned plate, the cross-section of the strip steel has different heights. If the welding parameters of the thickness of the patterned plate substrate are directly adopted for welding, defects such as incomplete penetration and local bumps will appear in the weld of the patterned plate. Under the current process, the pass rate of cup protrusion test is less than 30%, and the failure rate of weld bending test is as high as 85%.

[0034] Therefore, the welding thickness requirement for the two rolls of material is set as follows:

[0035] (1) Patterned plates are directly welded together, and the difference in thickness between the two substrates is ≤0.2mm.

[0036] (2) Welding of patterned steel plates to plain steel coils without patterns:

[0037] The basic thickness of the patterned plate shall not be greater than that of the ordinary plate, and the difference in substrate thickness between the two shall be ≤0.2mm, and the difference in yield strength shall be less than ≤200MPa.

[0038] 2. Welding process parameter setting

[0039] The internal electrical program of the welding machine is modified so that after the welding machine receives the basic thickness h of the hot-rolled patterned plate, the internal electrical program of the welding machine compensates the thickness of the hot-rolled patterned plate by 0.2mm, that is, the welding thickness of the patterned plate h1 = h + 0.2mm, and the welding machine program calls the thickness h1 as the welding parameter.

[0040] 3. The welding machine's rolling roller is not in use.

[0041] The function of the welding machine's compaction roller is to compact and thin the welded area of ​​the strip after the welding wheel completes the welding task, while ensuring the quality of the strip. This compaction enhances the toughness of the heat-affected zone at the weld joint and improves the mechanical properties of the weld joint. However, due to the unevenness of the strip surface caused by the patterned plate's bead height, using the welding machine's compaction roller would result in vibrations during welding operation, affecting accuracy and potentially damaging the equipment. Therefore, welding machine compaction rollers are not used.

[0042] S3, Straightening

[0043] The strip steel plate is straightened using a tension leveler. A leveling machine is not used in the production of patterned steel plates.

[0044] The process parameters for the tension leveling machine are set as follows: thickness 0.8-1.8mm, tension leveling elongation 0.3-0.5%, bending crossover 18-20mm, straightening crossover 23-26mm. The plate shape meets the requirements.

[0045] The bending unit of the tension leveler has a 100mm working roll diameter. The reason for this is that the existing tension leveler has a 70mm working roll diameter. At a running speed of ≥200m / min, due to the height of the pattern on the hot-rolled patterned plate, the raised pattern continuously impacts the working roll surface during production, causing the working roll box vibration amplitude to reach as high as 3.5mm, leading to the breakage of the working roll rotary joint. Changing the working roll diameter to 100mm reduces the roller box vibration to no more than 2.0mm at a running speed of ≥200m / min, resulting in stable operation and good product shape.

[0046] In addition, to reduce the risk of weld breakage in the patterned steel strip and the impact of the raised pattern on the roller surface, the inlet looper coverage is controlled at 75%, the maximum strip deviation is ±15mm, the idler roller surface is in good condition, and the exit process speed is limited to ≤200m / min. This achieves the expected cycle time and produces a good product surface.

[0047] To reduce the risk of weld breakage in patterned steel plates, the weld seam of each roll of patterned steel plate is passed through the straightening machine in an open mode.

[0048] In the optimized plan, to ensure weld quality and reduce the risk of weld breakage, a crescent-sized weld template is cut for each roll, and a weld bending test is conducted. Rolls that pass the weld bending test are released for production.

[0049] S4. Slitting and winding

[0050] The strip steel is slit using a slitting shear 6, and then the strip steel is wound up by a coiler 8.

[0051] A tension roller group No. 6 is installed between the leveling machine 5 and the slitting shear 7. Its main function is to establish tension and provide data to achieve accurate length cutting of the patterned plate.

[0052] Due to the influence of the height of hot-rolled patterned steel strip, the existing strip length calculation method will result in inaccurate patterned steel strip length calculation, over-tailing at the production line exit, and abnormalities such as inaccurate coiling and weight discrepancies.

[0053] This invention achieves precise cutting by modifying the method for calculating the length of the patterned plate.

[0054] Calculation of strip length at the exit coiler of ordinary steel coils:

[0055] The linear speed of the winding machine is V3 = π × d3 × |Δn3| / (imp3 × τ3).

[0056] Where d3 is the winding diameter of the winding machine, Δn3 is the encoder cycle difference of the winding machine, imp3 is the number of pulses per revolution of the encoder of the winding machine, and τ3 is the reduction ratio of the winding machine.

[0057] The linear velocity of tension roller No. 2 in tension roller group No. 6 is V2 = π × d2 × |Δn2| / (imp2 × τ2).

[0058] Where d2 is the diameter of tension roller #2 in tension roller group 6, Δn2 is the encoder cycle difference of tension roller #2, imp2 is the number of pulses per revolution of the encoder, and τ2 is the reduction ratio of tension roller #2.

[0059] Since the linear speeds of the same steel coil are equal, V3 = V2, therefore:

[0060] d3=(d2∣Δn2∣×imp3×τ3) / (∣Δn3∣imp2×τ2)

[0061] The area of ​​the strip ring in the coiler is S1 = π[(d3-d0) / 2] 2 =L×h.

[0062] The strip length of the coiler is L = π(d3 - d0). 2 / 4h ①

[0063] Where h is the strip thickness, d0 is the initial drum diameter, and d3 is the strip winding diameter of the coiler.

[0064] As can be seen from the formula, due to the influence of the patterned plate height, the thickness of the strip (h) in formula ① is inaccurate, resulting in a significant deviation in the calculated strip length (L). Inaccurate strip length leads to inaccurate slitting weight and abnormal tailing.

[0065] To ensure accurate cutting of the patterned steel strip, a separate formula for calculating its length is designed within the program. The strip's running length on tension roller 2 of tension roller group 6 is consistent with the strip's winding length on the coiler, and the position of tension roller 2 of tension roller group 6 relative to the coiler drum is fixed. Therefore, the cutting length of the patterned steel strip, L1, can be calculated as the cutting length of the patterned steel strip on tension roller 2 of tension roller group 6.

[0066] L1=∣Δn2∣×imp2out×π×d2 ②

[0067] Where Δn2 is the number of encoder pulses within the cycle; the cycle refers to the CPU scan cycle of 0.02 seconds; imp2out is the length of a pulse, which is equal to πd2×τ2 / 1024; the tension roller detects 1024 pulses per revolution. Since the encoder measures the speed of the reducer, d2 is the diameter of tension roller No. 2, and τ2 is the reduction ratio of tension roller No. 2.

[0068] Using formula ② to calculate the length of the patterned plate, without considering the pattern thickness, can avoid the influence of the patterned plate height.

[0069] When using formula ① to calculate the strip steel, due to inaccurate length, the coil weight error reaches 34%, and the abnormal tailing rate is 10%.

[0070] After changing the L length calculation formula ②, the roll weight error was reduced to 2%, and no abnormal tailing occurred.

[0071] It should be noted that the specific embodiments of the present invention have been described in detail. For those skilled in the art, various obvious changes made to it without departing from the spirit and scope of the present invention are within the protection scope of the present invention.

Claims

1. A method for producing thin-gauge hot-rolled patterned steel plates using a continuous leveling production line, characterized in that: The patterned plate is 0.8-1.8mm thick; the process includes: uncoiling → welding → tension leveling → unevenness adjustment → slitting → winding. S1. Open the book; S2. Welding: The thickness difference between the base plates of the two coils should be ≤0.2mm. The thickness of the hot-rolled patterned plate raw material should be compensated by 0.2mm using the internal electrical program of the welding machine as the welding parameter. The rolling roller of the welding machine should not be used. When welding the patterned plate to the plain steel coil without pattern, the yield strength difference between the two coils should be less than ≤200MPa. S3. Straightening: The strip steel plate is straightened using a straightening machine without using a leveling machine; the weld seam is straightened in open mode; the process parameters are set as follows: straightening elongation 0.3-0.5%, bending crossover 18-20mm, straightening crossover 23-26mm; the working roller diameter of the bending unit of the straightening machine is 100mm. S4. Slitting and Rolling: The patterned plate is slit by calculating the running length L1 of tension roller 2 in tension roller group 6. The calculation formula is as follows: L1=|Δn2|×imp2out Where Δn2 is the encoder pulse value within the period, and the period is 0.02 seconds; imp2out = πd2 × τ2 / 1024, d2 is the diameter of tension roller No. 2, and τ2 is its reduction ratio.

2. The method for producing thin-gauge hot-rolled patterned steel plates using a continuous leveling production line according to claim 1, characterized in that: Before the straightening process, a crescent-sized weld template is cut from each roll, and a weld bending test is performed.

Images