Control method for eliminating thin-gauge hot-rolled strip steel coiling folding marks

Abstract

The invention discloses a control method for eliminating thin-gauge hot-rolled strip steel coiling folding marks, which comprises the following steps: controlling the temperature of the head and tail of strip steel when the strip steel passes through a pinch roll according to the target thickness of the strip steel; the target thickness of the strip steel is larger than 2.0 mm and smaller than or equal to 2.5 mm, and the temperature of the position 10-30 m away from the head and the tail of the strip steel is controlled to be reduced by 30-50 DEG C compared with the target coiling temperature; the target thickness of the strip steel is larger than 1.5 mm and smaller than or equal to 2.0 mm, and the temperature of the positions 20-40 m away from the head and the tail of the strip steel is controlled to be reduced by 40-60 DEG C compared with the target coiling temperature; the target thickness of the strip steel is smaller than or equal to 1.5 mm, and the temperature of 30-50 m positions of the head and the tail of the strip steel is controlled to be reduced by 50-80 DEG C compared with the target coiling By means of strip steel head and tail temperature control, side guide opening degree and pressure control, pinch roll gap and pressure control and wrapper roll pressing force and jump-off value control, the defect of thin-specification hot-rolled strip steel coiling folding marks is overcome, and strip breakage accidents caused by folding marks in subsequent procedures are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of hot-rolled strip steel production, and in particular relates to a control method for eliminating coiling and folding marks of thin-gauge hot-rolled strip steel. Background Art

[0002] In the conventional hot rolling production process, the slab is descaled once after leaving the heating furnace to remove the surface iron oxide, and then rolled into an intermediate slab by the rough rolling unit, and then rolled into a strip by the seven-stand finishing rolling unit. After laminar cooling, the strip passes through the laminar roller and the side guide clamping, and finally guided by the upper and lower pinch rollers into a coiler, and then transported to the transport line by the unloading car and into the finished product warehouse. The production of thin-gauge hot-rolled strip is difficult, and the head and tail are prone to deviation. The deviation strip is prone to folding defects after being clamped by the side guide and squeezed by the pinch roller. After the strip has folding marks, it often causes the strip to break during the subsequent process of leveling and cold rolling pickling, which seriously affects production efficiency and causes serious quality accidents. When a steel plant produces thin hot-rolled strip with a thickness of ≤2.5mm, folding marks often appear at the head and tail of the strip during the coiling process, which directly causes the strip to break in the subsequent cold rolling process. In order to reduce the occurrence of subsequent process accidents, the folding marks can only be removed offline, which seriously affects the hot rolling yield and has a serious impact on product quality. Therefore, it is urgent to solve this problem.

[0003] Publication number CN117840234A discloses an online detection method for folding marks of steel strips, comprising the following steps: (1) collecting the current folding mark monitoring parameters of the steel strips; (2) detecting whether the current folding mark monitoring parameters have changed. If there are folding mark monitoring parameters that have changed, it is determined that there are folding marks at the corresponding position. The online detection method for folding marks of steel strips provided by the present invention can reflect the folding situation of the surface of the steel strips online and in real time, and issue an early warning, thereby reducing the secondary hazards caused by the folding. At present, a certain production line has realized the online process early warning and closure of folding marks, and the outflow rate of folding marks has been reduced by more than 30%. However, only early warning and closure of folding marks cannot eliminate folding mark defects.

[0004] A study on the folding marks of thin-gauge hot-rolled strip coiling found that the thinner the target thickness of the strip, the lower the strength, the greater the deviation of the head and tail, the untimely opening of the side guides, the greater the deviation of the roll gap of the coiling and pinch rollers, and the greater the probability of folding marks on the head and tail of the strip. Summary of the invention

[0005] In order to overcome the defects and shortcomings of the prior art, a control method for eliminating folding marks when coiling thin hot-rolled strip steel is provided.

[0006] To achieve the above object, the present invention provides a control method for eliminating the folding mark of thin hot-rolled strip coiling, and controls the temperature of the head and tail of the strip when passing through the pinch roller according to the target thickness of the strip, as follows:

[0007] The target thickness of the strip is greater than 2.0 mm and less than or equal to 2.5 mm. When the strip head and tail exit F7, the temperature at 10 - 30 m from the strip head and tail is controlled to be 30 - 50 °C lower than the target coiling temperature;

[0008] The target thickness of the strip is greater than 1.5 mm and less than or equal to 2.0 mm. When the strip head and tail exit F7, the temperature at 20 - 40 m from the strip head and tail is controlled to be 40 - 60 °C lower than the target coiling temperature;

[0009] The target thickness of the strip is less than or equal to 1.5 mm. When the strip head and tail exit F7, the temperature at 30 - 50 m from the strip head and tail is controlled to be 50 - 80 °C lower than the target coiling temperature.

[0010] Furthermore, according to the deviation amount △x and deviation direction of the strip head and tail when the strip exits F7, the opening of the side guard on the deviation direction side is adjusted to △x + 20 - 30 mm, improving the centering accuracy of the strip.

[0011] Furthermore, according to the deviation direction of the strip head and tail when the strip exits F7, the pressure of the side guard on the deviation direction side is adjusted by +2 - 4 Kn, further improving the centering accuracy of the strip.

[0012] Furthermore, according to the deviation amount △x and deviation direction of the strip head and tail when the strip exits F7, the deviation of the pinch roll gap on the deviation direction side is adjusted by -0.15 - -0.5 mm.

[0013] Furthermore, according to the deviation amount △x and deviation direction of the strip head and tail when the strip exits F7, the pressure of the pinch roll on the deviation direction side is adjusted by +10 - 30 Kn.

[0014] Furthermore, according to the deviation amount △x and deviation direction of the strip head and tail when the strip exits F7, the pressing force of the coiling roll is -1 - -5 Kn, and the opening value of the coiling roll is +0.15 - 0.3 mm.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention controls the strip head and tail temperature, the opening and pressure of the side guard, the gap and pressure of the pinch roll, and the pressing force and opening value of the coiling roll, eliminating the coiling folding mark defect of thin - gauge hot - rolled strips, avoiding the strip breakage accident caused by folding marks in the subsequent process, and this control method does not require equipment modification, being simple and effective. Specific Embodiments

[0016] The following specific embodiments further illustrate the present invention.

[0017] The target thickness of the strip is greater than 2.0 mm and less than or equal to 2.5 mm. When the strip head and tail exit F7, the temperature at 10 - 30 m from the strip head and tail is controlled to be 30 - 50 °C lower than the target coiling temperature;

[0018] The target thickness of the strip is greater than 1.5 mm and less than or equal to 2.0 mm. When the strip head and tail exit F7, the temperature at 20 - 40 m from the strip head and tail is controlled to be 40 - 60 °C lower than the target coiling temperature.

[0019] When the target thickness of the strip is less than or equal to 1.5 mm and the strip head and tail exit F7, the temperature at 30 - 50 m from the strip head and tail is controlled to be 50 - 80 °C lower than the target coiling temperature.

[0020] Example 1

[0021] Produce a strip with a thickness of 2.2 mm, and the target coiling temperature is 650 °C.

[0022] 1) Strip head and tail temperature

[0023]

[0024] 2) Coiling side guard opening and side guard pressure

[0025] According to the measured deviation amount △x and deviation direction of the strip when it exits F7 by the instrument, the opening of the side guard on the deviation direction side is adjusted to △x + 30 mm; if △x is greater than 0 and less than or equal to 20 mm, the side guard pressure on the deviation direction side is +2 Kn, if △x is greater than 20 mm and less than or equal to 40 mm, the side guard pressure on the deviation direction side is +3 Kn, if △x is greater than 40 mm, the side guard pressure on the deviation direction side is +4 Kn.

[0026] 3) Pinch roll gap deviation and pinch roll pressure

[0027] According to the measured deviation amount △x and deviation direction of the strip when it exits F7 by the instrument, the pinch roll gap on the deviation side is -0.5 mm. If △x is greater than 0 and less than or equal to 20 mm, the pinch roll pressure on the deviation direction side is +10 Kn, if △x is greater than 20 mm and less than or equal to 40 mm, the side pinch roll pressure on the deviation direction side is +20 Kn, if △x is greater than 40 mm, the pinch roll pressure on the deviation direction side is +30 Kn.

[0028] 4) Wrapper roll pressing force and opening value

[0029] According to the measured deviation amount △x and deviation direction of the strip when it exits F7 by the instrument, the opening value of the wrapper roll is +0.3 mm. If △x is greater than 0 and less than or equal to 20 mm, the wrapper roll pressing force is -3 Kn, if △x is greater than 20 mm and less than or equal to 40 mm, the wrapper roll pressing force is -4 Kn, if △x is greater than 40 mm, the wrapper roll pressing force is -5 Kn.

[0030] Implementation effect

[0031] The incidence rate of folding marks in the coiling of thin - gauge hot - rolled strip throughout 2024 is 0.

[0032] Example 2

[0033] Produce strip steel with a thickness of 2.2 mm, and the target coiling temperature is 600 °C.

[0034] 1) Strip head and tail temperature

[0035]

[0036] 2) Coiling side guard opening and side guard pressure

[0037] According to the strip deviation Δx and deviation direction measured by the instrument when the strip exits F7, the opening of the side guard on the deviation side is adjusted to Δx + 25 mm; if Δx is greater than 0 and less than or equal to 20 mm, the side guard pressure on the deviation side is +2 Kn, if Δx is greater than 20 mm and less than or equal to 40 mm, the side guard pressure on the deviation side is +3 Kn, if Δx is greater than 40 mm, the side guard pressure on the deviation side is +4 Kn.

[0038] 3) Pinch roll gap deviation and pinch roll pressure

[0039] According to the strip deviation Δx and deviation direction measured by the instrument when the strip exits F7, the pinch roll gap on the deviation side is -0.4 mm. If Δx is greater than 0 and less than or equal to 20 mm, the pinch roll pressure on the deviation side is +10 Kn, if Δx is greater than 20 mm and less than or equal to 40 mm, the side pinch roll pressure on the deviation side is +15 Kn, if Δx is greater than 40 mm, the pinch roll pressure on the deviation side is +20 Kn.

[0040] 4) Wrapper roll pressing force and opening value

[0041] According to the strip deviation Δx and deviation direction measured by the instrument when the strip exits F7, the opening value of the wrapper roll is +0.2 mm. If Δx is greater than 0 and less than or equal to 20 mm, the wrapper roll pressing force is -2 Kn, if Δx is greater than 20 mm and less than or equal to 40 mm, the wrapper roll pressing force is -3 Kn, if Δx is greater than 40 mm, the wrapper roll pressing force is -4 Kn.

[0042] Implementation effect

[0043] The incidence rate of folding mark defects in the coiling of thin-gauge hot-rolled strip steel throughout 2024 is 0.

[0044] Example 3

[0045] Produce strip steel with a thickness of 1.8 mm, and the target coiling temperature is 700 °C.

[0046] 1) Strip head and tail temperature

[0047]

[0048] 2) Coiling side guard opening and side guard pressure

[0049] According to the measured deviation amount △x and deviation direction of the strip steel exiting F7 by the instrument, the opening of the side guard on the deviation direction side is adjusted to △x + 25 mm; if △x is greater than 0 and less than or equal to 20 mm, the pressure of the side guard on the deviation direction side is increased by 1 Kn, if △x is greater than 20 mm and less than or equal to 40 mm, the pressure of the side guard on the deviation direction side is increased by 2 Kn, and if △x is greater than 40 mm, the pressure of the side guard on the deviation direction side is increased by 3 Kn.

[0050] 3) Deviation of pinch roll gap and pinch roll pressure

[0051] According to the measured deviation amount △x and deviation direction of the strip steel exiting F7 by the instrument, the gap of the pinch roll on the deviation side is -0.3 mm. If △x is greater than 0 and less than or equal to 20 mm, the pressure of the pinch roll on the deviation direction side is increased by 10 Kn, if △x is greater than 20 mm and less than or equal to 40 mm, the pressure of the pinch roll on the deviation direction side is increased by 15 Kn, and if △x is greater than 40 mm, the pressure of the pinch roll on the deviation direction side is increased by 20 Kn.

[0052] 4) Pushing force and opening value of coiling roll

[0053] According to the measured deviation amount △x and deviation direction of the strip steel exiting F7 by the instrument, the opening value of the coiling roll is increased by 0.15 mm. If △x is greater than 0 and less than or equal to 20 mm, the pushing force of the coiling roll is decreased by 3 Kn, if △x is greater than 20 mm and less than or equal to 40 mm, the pushing force of the coiling roll is decreased by 4 Kn, and if △x is greater than 40 mm, the pushing force of the coiling roll is decreased by 5 Kn.

[0054] Implementation effect

[0055] The incidence rate of folding mark defects in the coiling of thin-gauge hot-rolled strip steel throughout 2024 was 0.

[0056] Example 4

[0057] Producing strip steel with a thickness of 1.6 mm, the target coiling temperature is 650 °C.

[0058] 1) Temperature at the tail of the strip steel

[0059]

[0060] 2) Opening of the coiling side guard and side guard pressure

[0061] According to the measured deviation amount △x and deviation direction of the strip steel exiting F7 by the instrument, the opening of the side guard on the deviation direction side is adjusted to △x + 20 mm; if △x is greater than 0 and less than or equal to 20 mm, the pressure of the side guard on the deviation direction side is increased by 3 Kn, if △x is greater than 20 mm and less than or equal to 40 mm, the pressure of the side guard on the deviation direction side is increased by 4 Kn, and if △x is greater than 40 mm, the pressure of the side guard on the deviation direction side is increased by 5 Kn.

[0062] 3) Deviation of pinch roll gap and pinch roll pressure

[0063] According to the strip deviation Δx and deviation direction measured by the instrument when the strip exits F7, the roll gap of the pinch roll on the deviation side is -0.3 mm. If Δx is greater than 0 and less than or equal to 20 mm, the pinch roll pressure on the deviation direction is +15 Kn. If Δx is greater than 20 mm and less than or equal to 40 mm, the pinch roll pressure on the deviation direction side is +20 Kn. If Δx is greater than 40 mm, the pinch roll pressure on the deviation direction is +25 Kn.

[0064] 4) Mandrel pinch force and kick-off value

[0065] According to the strip deviation Δx and deviation direction measured by the instrument when the strip exits F7, the kick-off value of the mandrel is +0.3 mm. If Δx is greater than 0 and less than or equal to 20 mm, the mandrel pinch force is -2 Kn. If Δx is greater than 20 mm and less than or equal to 40 mm, the mandrel pinch force is -3 Kn. If Δx is greater than 40 mm, the mandrel pinch force is -4 Kn.

[0066] Implementation effect

[0067] The incidence rate of folding marks in the coiling of thin-gauge hot-rolled strip throughout 2024 was 0.

[0068] Example 5

[0069] Producing strip with a thickness of 1.5 mm, the target coiling temperature is 600 °C.

[0070] 1) Strip temperature at the outlet

[0071]

[0072] 2) Coiling side guard opening and side guard pressure

[0073] According to the strip deviation Δx and deviation direction measured by the instrument when the strip exits F7, the opening of the side guard on the deviation direction is adjusted to Δx + 20 mm; if Δx is greater than 0 and less than or equal to 20 mm, the side guard pressure on the deviation direction is +2 Kn. If Δx is greater than 20 mm and less than or equal to 40 mm, the side guard pressure on the deviation direction is +3 Kn. If Δx is greater than 40 mm, the side guard pressure on the deviation direction is +4 Kn.

[0074] 3) Pinch roll roll gap deviation and pinch roll pressure

[0075] According to the strip deviation Δx and deviation direction measured by the instrument when the strip exits F7, the roll gap of the pinch roll on the deviation side is -0.15 mm. If Δx is greater than 0 and less than or equal to 20 mm, the pinch roll pressure on the deviation direction is +10 Kn. If Δx is greater than 20 mm and less than or equal to 40 mm, the pinch roll pressure on the deviation direction side is +15 Kn. If Δx is greater than 40 mm, the pinch roll pressure on the deviation direction is +20 Kn.

[0076] 4) Mandrel pinch force and kick-off value

[0077] According to the strip deviation amount △x and deviation direction measured by the instrument when the strip exits F7, the recoiler jumps open by +0.2 mm. If △x is greater than 0 and less than or equal to 20 mm, the recoiler pressing force is -1 Kn; if △x is greater than 20 mm and less than or equal to 40 mm, the recoiler pressing force is -2 Kn; if △x is greater than 40 mm, the recoiler pressing force is -3 Kn.

[0078] Implementation effect

[0079] The incidence rate of coiling folding marks defects in thin-gauge hot-rolled strip throughout 2024 is 0.

Claims

1. A control method for eliminating the folding mark of thin hot-rolled strip coiling, characterized in that: According to the target thickness of the strip, the temperature of the head and tail of the strip when passing through the pinch roll is controlled as follows: The target thickness of the strip is greater than 2.0mm and less than or equal to 2.5mm. When the strip ends at F7, the temperature at 10 to 30m from the strip ends is controlled to be 30 to 50℃ lower than the target coiling temperature; The target thickness of the strip is greater than 1.5mm and less than or equal to 2.0mm. When the strip ends at F7, the temperature at 20 to 40m from the strip ends is controlled to be 40 to 60℃ lower than the target coiling temperature; The target thickness of the strip is less than or equal to 1.5mm. When the strip ends are F7, the temperature at 30 to 50m from the strip ends is controlled to be 50 to 80℃ lower than the target coiling temperature.

2. The control method for eliminating the folding marks of thin hot-rolled strip coiling according to claim 1, characterized in that: According to the head and tail deviation amount △x and the deviation direction when the strip steel comes out of F7, the side guide opening degree in the deviation direction is adjusted to △x+20~30mm.

3. The control method for eliminating the folding marks of thin hot-rolled strip coiling according to claim 2, characterized in that: According to the deviation direction of the head and tail of the strip when it leaves F7, the side guide pressure in the deviation direction is adjusted by +2~4Kn.

4. The control method for eliminating the folding marks of thin hot-rolled strip coiling according to claim 2, characterized in that: According to the head and tail deviation amount △x and the deviation direction when the strip comes out of F7, the roller gap deviation of the pinch rollers in the deviation direction is adjusted to -0.15 to -0.5mm.

5. The control method for eliminating the folding marks of thin hot-rolled strip coiling according to claim 2, characterized in that: According to the head and tail deviation amount △x and deviation direction when the strip steel comes out of F7, the pressure of the pinch roller in the deviation direction is adjusted by +10~30Kn.

6. The control method for eliminating the folding marks of thin hot-rolled strip coiling according to claim 2, characterized in that: According to the head and tail deviation amount △x and deviation direction when the strip steel comes out of F7, the pressing force of the auxiliary winding roller is -1 to -5Kn, and the auxiliary winding roller jump value is +0.15 to 0.3mm.

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