Production method of double-stand rolling mill for thin steel plate with thickness of 6mm

Abstract

The invention provides a double-stand rolling mill production method for a thin steel plate with the thickness of 6 mm, and belongs to the technical field of steel plate rolling processes. The rolling temperature of rough rolling and finish rolling is increased by adjusting the heating and tapping temperature of the plate blank and the parameters such as the cooling water flow and the rolling pass in the rolling process, and meanwhile a specific straightening technology is used in a matched mode; the problems of camber, edge wave, middle wave, deviation, steel stacking and other defects when a wide and thick plate double-rack rolling mill is adopted to produce steel plates with the thickness specification of 6 mm are effectively solved, and steel clamping accidents are avoided. The produced 6mm thin steel plate is good in plate shape and free of obvious defects such as middle waves, edge waves and camber, the unevenness of the steel plate is smaller than or equal to 3 mm / m, the performance is uniform, and the market requirement of the thin steel plate is met; in addition, the method is low in cost and suitable for batch production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel plate rolling process, in particular to a double-stand rolling mill production method of a 6 mm thick thin gauge steel plate. BACKGROUND

[0002] With the development of economy, steel plate as the main steel material is widely used in various fields such as ships, buildings, pressure vessels, etc. Among them, thin gauge steel plates are mostly produced by hot continuous rolling mills and furnace rolling mills. However, when the width of the steel plate reaches 2000 mm or more, a wide and thick plate rolling mill needs to be used for production. During the production process using a wide and thick plate rolling mill, due to the influence of equipment capacity, billet shape and other factors, problems such as wave shape, camber, and stacked steel often occur. At the same time, due to the wide and thin steel plate, the overall temperature drop is fast and uneven during the rolling process, which further causes large temperature differences between the same steel plates and uneven performance. It is even more difficult to improve the production rhythm while ensuring the yield rate for double-stand production of thin gauge steel plates. Patent CN116809630A discloses a method for producing thin gauge steel plates by a wide and thick plate double-stand rolling mill. The steel plates (thickness 8 mm, width 2000-3200 mm) produced by the method have a flatness of ≤3 mm / m, good plate shape, and uniform performance. However, when the above method is used to produce a steel plate with a thickness of 6 mm, there are still defects such as poor plate shape and serious camber.

[0003] Therefore, it is urgent to develop a rolling process for ultra-thin gauge steel plates to produce ultra-thin gauge steel plates with stable plate shape and uniform performance. SUMMARY

[0004] In view of the above shortcomings of the prior art, the present application provides a double-stand rolling mill production method of a 6 mm thick thin gauge steel plate. The present application uses a double-stand rolling mill finishing process to successfully avoid the occurrence of plate shape defects such as wave shape, camber, and stacked steel in thin gauge steel plates with a thickness of 6 mm and a width of 2000-3000 mm when rolled on a wide and thick plate rolling mill, and the performance is uniform.

[0005] To achieve the above-mentioned purpose, the specific technical solutions of the present application are as follows:

[0006] The present application provides a double-stand rolling mill production method of a 6 mm thick thin gauge steel plate, comprising the following steps:

[0007] Breakdown: multiple steel plates with a thickness of 8-16 mm are arranged, and transition is made from thick to thin, and rolling breakdown is performed to 120±10 mm;

[0008] Heating: the upper surface temperature of the slab is higher than the lower surface temperature when heated, and the discharge temperature is controlled to be 1320-1340 DEG C, and the temperature difference of the discharge section is less than or equal to 20 DEG C;

[0009] Coarse rolling: the opening rolling temperature is controlled to be greater than or equal to 1260 DEG C, the rolling pass is less than or equal to 3 passes, and the finish rolling temperature is controlled to be 1200-1240 DEG C.

[0010] Finish rolling: the opening rolling temperature is controlled to be greater than or equal to 1130 DEG C, the rolling pass is less than or equal to 6 passes, and the finish rolling temperature is controlled to be 800-850 DEG C.

[0011] Straightening: the straightening temperature is controlled to be 450-550 DEG C, and the entry roll gap of the straightening machine is the thickness of the steel plate minus 6-7 mm.

[0012] In view of the problems in the prior art that the overall temperature drop is too fast and uneven during the rolling process of the thin-gauge steel plate, and the temperature difference of the steel plate is large and the performance is uneven, the present application adopts a double-stand rolling process, increases the slab heating discharge temperature to ensure that the slab is opened at a high temperature, reduces the roller body cooling water flow and the rolling pass during the coarse rolling process, and ensures that the steel plate enters the finish rolling stage at a high temperature. In addition, by reducing the roller body cooling water flow and the rolling speed during the finish rolling process, and using a specific straightening process, the production of 6 mm thin-gauge steel plates is finally realized. The 6 mm thin-gauge steel plate produced by the present application has good shape, no obvious middle wave, edge wave, camber and other defects, the unevenness of the steel plate is less than or equal to 3 mm / m, and the performance is uniform.

[0013] Further, the roller body cooling water flow during the coarse rolling process is controlled to be 480-600 m 3 / h, and the roller cooling water is turned off.

[0014] Further, the rolling speed during the coarse rolling process is 2-3 m / s.

[0015] Further, the roller body cooling water flow during the finish rolling process is controlled to be 600-700 m 3 / h, and the roller cooling water is turned off.

[0016] Further, the rolling speed during the finish rolling process is 2.7-6.5 m / s, and the rolling speed of the last three passes is controlled to be 2.7-3.2 m / s.

[0017] Further, the straightening speed during the straightening process is 0.7-1 m / s.

[0018] The present application also provides a 6 mm thin-gauge steel plate produced by the method.

[0019] Further, the thickness 6 mm thin gauge steel plate has a width of 2000-3000 mm, and the unevenness of the steel plate is less than or equal to 3 mm / m.

[0020] Compared with the prior art, the present application has the advantages of:

[0021] The present application adjusts the heating out-furnace temperature of the slab, the cooling water flow rate in the rolling process, the rolling pass and other parameters to improve the rolling temperature, and cooperates with the use of a specific straightening process, effectively solves the problems of camber, edge wave, middle wave, deviation and stacking defects of the 6 mm thick thin gauge steel plate produced by the wide-thick plate double-stand rolling mill, and avoids the occurrence of the steel clamping accident. The 6 mm thin gauge steel plate produced by the present application has good plate shape, no obvious middle wave, edge wave, camber and other defects, the unevenness of the steel plate is less than or equal to 3 mm / m, the performance is uniform, and the market demand of the thin gauge steel plate is met. In addition, the method of the present application has low cost and is suitable for batch production. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0023] The present application provides a double-stand rolling mill production method of a thickness 6 mm thin gauge steel plate, which comprises the following steps:

[0024] Blooming: multiple steel plates with a thickness of 8-16 mm are arranged, and transition is performed from thick to thin, and blooming is performed to 120±10 mm;

[0025] Heating: the upper surface temperature of the slab is higher than the lower surface temperature during heating, and the out-furnace temperature is controlled to be 1320-1340 DEG C, and the temperature difference of the out-furnace section is less than or equal to 20 DEG C;

[0026] The rough rolling is controlled to be greater than or equal to 1260 DEG C, the rolling pass is less than or equal to 3 passes, the rolling speed is 2-3 m / s, the roller body cooling water flow rate is controlled to be 480-600 m 3 / h during the rolling process, the roller bed cooling water is turned off, and the finish rolling temperature is controlled to be 1200-1240 DEG C;

[0027] The finish rolling is controlled to be greater than or equal to 1130 DEG C, the rolling pass is less than or equal to 6 passes, the rolling speed is 2.7-6.5 m / s, the rolling speed of the last three passes is controlled to be 2.7-3.2 m / s, the finish rolling temperature is controlled to be 800-850 DEG C, and the roller body cooling water flow rate is controlled to be 600-700 m 3 / h during the rolling process, and the roller bed cooling water is turned off.

[0028] Straightening: the straightening temperature is controlled to be 450-550 ℃, the straightening speed is 0.7-1 m / s, and the straightening machine inlet roll gap is the thickness of the steel plate minus 6-7 mm.

[0029] Example 1

[0030] The embodiment adopts a double-stand rolling mill to produce a thin gauge steel plate with a thickness of 6 mm and a width of 3000 mm or less, and the production method comprises the following steps:

[0031] (1) blooming: multiple steel plates with a thickness of 8-16 mm are arranged in production, and transition is performed from thick to thin; the plate is rolled to 120 mm; before producing the thin gauge steel plate with a thickness of 6 mm, multiple rolling steel plates with a similar thickness (8-16 mm) are arranged in production to facilitate understanding of the equipment state and making an advance adjustment. When producing the thin gauge steel plate with a thickness of 6 mm, the existing billet with a thickness of 200 mm is rolled to a thickness of 120±10 mm and then cut to a size suitable for charging into the furnace for standby; if the billet is rolled to a thinner thickness (less than 110 mm), the plate shape after the billet is discharged after heating will be unsuitable for production.

[0032] (2) heating: the upper surface temperature of the billet is higher than the lower surface temperature during heating, and the discharge temperature of the billet is controlled to be 1320-1340 ℃, and the temperature difference of the cross section after discharge is ≤20 ℃; after descaling after discharge, the billet is sent to the rough rolling mill. The specific parameters of the heating process are as follows:

[0033]

[0034] (3) rough rolling: the rolling temperature is controlled to be ≥1260 ℃, the rolling pass is ≤3 passes, the rolling speed is 2-3 m / s, the roller body cooling water flow is controlled to be 480-600 m 3 / h during the rolling process, the roller way cooling water is closed, and the finish rolling temperature is controlled to be 1200-1240 ℃. The specific parameters of the rough rolling process are as follows:

[0035]

[0036] (4) finish rolling: the rolling temperature is controlled to be ≥1130 ℃, the rolling pass is ≤6 passes, the rolling speed is 2.7-6.5 m / s, the last three passes are controlled to be 2.7-3.2 m / s, the finish rolling temperature is 800-850 ℃, and the roller body cooling water flow is controlled to be 600-700 m 3 / h during the rolling process, and the roller way cooling water is closed. The specific parameters of the finish rolling process are as follows:

[0037]

[0038] (5) Straightening: straightening is carried out by using a 9-roller straightening machine, the straightening temperature is controlled to be 450-550 ℃, the entry roll gap of the straightening machine is 6-7 mm less than the thickness of the steel plate, and the straightening speed is 0.7-1 m / s. The specific parameters in the straightening process are as follows:

[0039]

[0040] As can be seen from the above, the finished steel plate with a thickness of 6 mm and a width of 2000-2900 mm prepared by the method has a flatness of ≤3 mm / m, good plate shape, no defects such as middle wave, edge wave and camber, and uniform performance.

[0041] Comparative Example 1

[0042] In the comparative example, a double-stand rolling mill is used to produce a thin-gauge steel plate with a thickness of 6 mm and a width of less than 3000 mm, and the production method comprises the following steps:

[0043] (1) The billet with a thickness of 200 mm is not prepared for subsequent heating and rolling.

[0044] (2) Heating: the upper surface temperature of the slab is higher than the lower surface temperature during heating, and the slab discharge temperature is controlled to be 1270-1300 ℃, and the temperature difference of the cross section after discharge is ≤20 ℃. After descaling, it is sent to the rough rolling mill. The specific parameters in the heating process are as follows:

[0045]

[0046] (3) Rough rolling: the opening temperature is controlled to be ≥1220 ℃, and the rolling pass is ≤7 passes. The roller body cooling water flow is controlled to be 650-750 m 3 / h during the rolling process, and the roller way cooling water is closed. The specific parameters in the rough rolling process are as follows:

[0047]

[0048] (4) Finish rolling: the rolling pass is ≤6 passes, the rolling speed is 3-5 m / s, and the rolling speed of the last three passes is controlled to be 3-3.5 m / s. The roller body cooling water flow is controlled to be 650-750 m 3 / h during the rolling process, and the roller way cooling water is closed. The specific parameters in the finish rolling process are as follows:

[0049]

[0050] As can be seen from the above, since the target thickness of 6 mm is thin, the total reduction in the rolling process is too large, and the temperature decreases too fast, it is difficult to ensure the rolling temperature in the later stage to support the deformation amount, resulting in uneven performance of the steel plate.

[0051] Comparative Example 2

[0052] The comparative example uses a double-stand rolling mill to produce thin-gauge steel plates with a thickness of 6 mm and a width of 3000 mm or less. The production method includes the following steps:

[0053] (1) blooming: 20 steel plates with a thickness of 8-16 mm and a similar width are arranged in production, and transition is performed from thick to thin, and the plate is bloomed to 140 mm;

[0054] (2) heating: the upper surface temperature of the plate blank is higher than the lower surface temperature during heating, and the plate blank discharge temperature is controlled to be 1270-1300 °C, and the discharge cross-section temperature difference is ≤20 °C. After descaling after discharge, it is sent to the rough rolling mill. The specific parameters of the heating process are as follows:

[0055]

[0056] (3) rough rolling: the opening rolling temperature is controlled to be ≥1220 °C, and compared with Comparative Example 1, the rolling pass is reduced to ≤3 passes, and the roller body cooling water flow is adjusted to 550-650 m 3 / h during rolling, and the roller cooling water is turned off. The specific parameters of the rough rolling process are as follows:

[0057]

[0058] (4) finishing rolling: the rolling pass is ≤6 passes, the rolling speed is 3-5 m / s, and the rolling speed of the last three passes is controlled to be 3-3.5 m / s, and the roller body cooling water flow is controlled to be 650-750 m 3 / h during rolling, and the roller cooling water is turned off. The specific parameters of the finishing rolling process are as follows:

[0059]

[0060] As can be seen from the above, the steel plates of the first and second groups are rolled, but the plate shape is poor and the thickness fluctuation is large; and the steel plates of the third and fourth groups are still abandoned due to the target thickness being too thin and the width being too large, and the temperature reduction speed being too fast, resulting in serious last-pass rolling camber.

[0061] To sum up, the application adopts the double-stand rolling process, increases the heating and discharging temperature of the slab to ensure the slab to be rolled at a higher temperature, reduces the roller body cooling water flow and rolling passes in the rough rolling process, and ensures the steel plate to enter the finishing rolling stage at a higher temperature. In addition, by reducing the roller body cooling water flow and rolling speed in the finishing rolling process, and cooperating with the specific straightening process, the problems of the steel plate produced by the double-stand plate mill for the 6mm thick thin specification steel plate, such as the camber, edge wave, middle wave, deviation and stacking, are effectively solved, and the steel plate jam accident is avoided. The 6mm thin specification steel plate produced by the application has good plate shape, no obvious middle wave, edge wave and camber defects, the unevenness of the steel plate is less than or equal to 3mm / m, the performance is uniform, and the market demand of the thin specification steel plate is met. In addition, the method of the application is low in cost and suitable for batch production.

[0062] The above detailed description of the embodiments of the application, but the application is not limited to the specific details of the above-described embodiments. Within the scope of the claims and technical concepts of the application, the technical solutions of the application can be modified and changed in many ways, and these simple modifications all belong to the protection scope of the application.

Claims

1. A method of producing a thin gauge steel sheet having a thickness of 6 mm by a twin stand rolling mill, characterized in that, It comprises the following steps: blooming: rolling blooming to 120±10 mm; heating: the upper surface temperature of the slab is higher than the lower surface temperature when heated, and the temperature difference between the cross sections is ≤20 ℃ when leaving the furnace; rough rolling: the rolling pass is ≤3 passes, and the final rolling temperature is controlled to be 1200~1240 ℃; finish rolling: the rolling pass is ≤6 passes, and the final rolling temperature is controlled to be 800~850 ℃; straightening: the straightening temperature is 450~550 ℃, and the entry roll gap of the straightening machine is the thickness of the steel plate minus 6~7 mm.

2. The dual stand mill production method of a thin gauge steel plate of 6 mm thickness according to claim 1, characterized by, The roll body cooling water flow rate in the rough rolling process is 480~600 m 3 / h, and the roll table cooling water is closed.

3. The method of producing a thin gauge steel sheet of 6 mm thickness by a twin stand rolling mill according to claim 2, characterized by, The rolling speed in the rough rolling process is 2~3 m / s.

4. The dual stand mill production method of a thin gauge steel plate of 6 mm thickness according to claim 1, characterized by, The roll body cooling water flow rate in the finish rolling process is 600~700 m 3 / h, and the roll table cooling water is closed.

5. The dual stand mill production method of a thin gauge steel sheet of 6 mm thickness according to claim 4, characterized by, The rolling speed in the finish rolling process is 2.7~6.5 m / s, and the rolling speed of the last three passes is controlled to be 2.7~3.2 m / s.

6. The dual stand mill production method of a thin gauge steel plate of 6 mm thickness according to claim 1, characterized by, The straightening speed in the straightening process is 0.7~1 m / s.

7. The thin gauge steel plate with a thickness of 6 mm produced by the method of any one of claims 1-6.

8. The thickness 6 mm thin-gauge steel sheet according to claim 7, characterized by, The width is 2000~3000 mm, and the unevenness of the steel plate is ≤3 mm / m.

Images