A method for finishing endless rolling of hot-rolled strip steel

Abstract

The present invention relates to a method for finishing headless rolling of hot-rolled strip steel, and belongs to the technical field of hot-rolled strip steel production process in the metallurgical industry. The technical solution is: when the hot-rolled strip steel is converted from the headless rolling mode to the single-block rolling mode, it is controlled according to the following operations: ① the speed of the finishing coil in the headless rolling mode is increased, so that the tail billet in the headless rolling mode is pulled a certain distance away from the subsequent slab in the single-block rolling mode; ② the thickness of the finished product of the finishing coil in the headless rolling mode is controlled to 2.0 mm. The beneficial effects of the present invention are: it can reduce accidents of tail-end steel pile-up, reduce the accident rate, ensure the coiling preparation time of the finishing coil, improve the cross-sectional quality of the hot-rolled strip steel, improve the convexity of the finished product, eliminate wave defects, and increase the added value of the product.

Description

Technical Field

[0001] The invention relates to a hot-rolled strip steel endless rolling finishing method, belonging to the technical field of hot-rolled strip steel production processes in the metallurgical industry. Background Art

[0002] Hot strip endless rolling is a continuous, uninterrupted process that produces hot-rolled coils directly from molten steel via thin slab casting and rolling equipment. This process combines the continuous casting and rolling processes in tandem, with coil separation performed by a high-speed flying shear before the coiler.

[0003] The finishing mill needs to change rolls in the middle of each casting. Therefore, the endless rolling mode needs to be switched to the single-block mode every time the casting is in the middle or when the casting is stopped. The tail billet before the endless rolling mode is switched to the single-block mode is the tail coil. If the tail coil is not handled properly, the following problems will occur: first, it will cause tail-end steel pile accidents; second, if thicker strip steel is produced, the crown of the tail coil will be reduced and the cross-sectional profile will be uneven; if thinner strip steel is produced, the tail coil will appear wavy after speeding up; third, if the speed is increased too quickly, the coiler will not have sufficient preparation time to coil the next coil, causing a coiling accident. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for finishing headless rolling of hot-rolled strip steel, which can reduce tail-end steel pile-up accidents, improve the cross-sectional quality of the hot-rolled strip steel, and solve the problems existing in the background technology.

[0005] The technical solution of the present invention is:

[0006] A method for finishing endless rolling of a hot-rolled strip, wherein when the hot-rolled strip is converted from an endless rolling mode to a single-block rolling mode, the method is controlled according to the following operations:

[0007] ① Increase the speed of the tail coil in the headless rolling mode to keep a certain distance between the tail billet in the headless rolling mode and the subsequent single-block rolling mode billet;

[0008] ②Control the thickness of the finished coil in the headless rolling mode to 2.0mm.

[0009] The speed increase ratio of the tail coil in the headless rolling mode is 1.2-1.8 times.

[0010] The speed increase multiple of the tail coil in the headless rolling mode refers to the speed increase multiple of the roughing mill, finishing mill and coiler after the tail billet in the headless rolling mode is disconnected from the subsequent slab in the single-block rolling mode.

[0011] The tail coils in the endless rolling mode are the last six coils of steel, and the finished product thickness of the last six coils of steel is controlled at 2.0 mm.

[0012] Adjust the slab lengths corresponding to the last six tail coils in the headless rolling mode so that the coil weight of the first four coils is the maximum weight of the coiler coiling, and the corresponding slab is the maximum slab length; when adjusting the slab lengths corresponding to the last two coils, ensure that the head-to-tail connection point avoids the finishing mill, flying shear and TOP point. The head-to-tail connection point refers to the position where the tail of the previous coil and the head of the next coil are connected in the headless rolling mode. The TOP point is a tracking point in front of the finishing mill. When the head-to-tail connection point reaches this tracking point, the set value is issued to the finishing mill.

[0013] The beneficial effects of the present invention are: it can reduce tail-end steel pile accidents, lower the accident rate, ensure the coiling preparation time of the tail coil, improve the cross-sectional quality of the hot-rolled strip, improve the convexity of the finished product, eliminate wave defects, and increase the added value of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the end of the present invention;

[0015] Figure 2 This is a schematic diagram of the rolling mill speed increase of the present invention;

[0016] In the figure: finishing first roll 1, finishing second roll 2, finishing third roll 3, finishing fourth roll 4, finishing fifth roll 5, finishing sixth roll 6, swing shear 7, tunnel furnace 8, roughing mill 9, TOP point 10, finishing mill 11, high-speed flying shear 12, coiler 13. DETAILED DESCRIPTION

[0017] The present invention will be further described below with reference to the accompanying drawings and through examples.

[0018] Refer to the attached Figure 1-2 A method for finishing endless rolling of hot-rolled strip steel is provided. When the hot-rolled strip steel is converted from endless rolling mode to single-block rolling mode, the control is performed according to the following operations:

[0019] ① Increase the speed of the tail coil in the headless rolling mode to keep a certain distance between the tail billet in the headless rolling mode and the subsequent single-block rolling mode billet;

[0020] ②Control the thickness of the finished coil in the headless rolling mode to 2.0mm.

[0021] The speed increase ratio of the tail coil in the headless rolling mode is 1.2-1.8 times.

[0022] The speed increase multiple of the tail coil in the headless rolling mode refers to the speed increase multiple of the roughing mill, finishing mill and coiler after the tail billet in the headless rolling mode is disconnected from the subsequent slab in the single-block rolling mode.

[0023] The tail coils in the endless rolling mode are the last six coils of steel, and the finished product thickness of the last six coils of steel is controlled at 2.0 mm.

[0024] Adjust the slab lengths corresponding to the last six tail coils in the headless rolling mode so that the coil weight of the first four coils is the maximum weight of the coiler coiling, and the corresponding slab is the maximum slab length; when adjusting the slab lengths corresponding to the last two coils, ensure that the head-to-tail connection point avoids the finishing mill, flying shear and TOP point. The head-to-tail connection point refers to the position where the tail of the previous coil and the head of the next coil are connected in the headless rolling mode. The TOP point is a tracking point in front of the finishing mill. When the head-to-tail connection point reaches this tracking point, the set value is issued to the finishing mill. Example

[0025] Refer to the attached Figure 1 、 2 The endless rolling process includes a continuous casting machine, a swing shear 7, a tunnel furnace 8, a roughing mill 9, a top rolling mill 10, a finishing mill 11, a high-speed flying shear 12, and a coiler 13. This is explained using a casting speed of 5.00 m / min, a width of 1250 mm, and an intermediate billet thickness of 30 mm as an example.

[0026] During the casting process, the finishing rolling roller change and casting stop need to be converted from the full headless mode to the single block mode. This process is achieved by swing shear 7 shearing.

[0027] Refer to the attached Figure 1 The finishing coils in the headless rolling mode are the last six coils of steel, namely the first finishing coil 1, the second finishing coil 2, the third finishing coil 3, the fourth finishing coil 4, the fifth finishing coil 5 and the sixth finishing coil 6. The corresponding slabs are also the last six pieces, that is, there are 6 pieces of steel from the coiler 13 to the swing shear 7, which are counted as the 1st to 6th pieces. Before shearing by the swing shear 7, the length and finished product thickness of these 6 slabs need to be corrected. The finished product thickness of these 6 slabs is controlled to be 2.0mm.

[0028] In order to ensure that the coiler has enough time to unload the coils, the maximum slab length of the 1st to 4th blocks is used, which is corrected to 21.2m, that is, the corresponding coil weight is the maximum weight of the coiler; the length of the 5th and 6th coils is corrected to 16.9m and 18.8m. When the length of the 5th and 6th blocks is modified, it is necessary to ensure that the head-to-tail connection point avoids the finishing mill, the high-speed flying shear and the TOP point. The head-to-tail connection point refers to the position where the tail of the previous coil and the head of the next coil are connected in the headless mode. The TOP point is a tracking point in front of the finishing mill. When the head-to-tail connection point reaches this tracking point, the finishing mill issues the set value.

[0029] After shearing by the swing shear 7, the headless tail billet is separated from the subsequent slabs. The roughing mill, finishing mill and coiler are accelerated synchronously to increase the distance. When the headless tail billet leaves the tunnel furnace, the speed is appropriately reduced to ensure rolling stability until the sixth coil is coiled. The specific speed increase requirements are as follows:

[0030] After the swing shear shearing, the roughing mill, finishing mill and coiler are accelerated at 1.6 times. After the tail of the 6th block leaves the tunnel furnace, the speed increase factor is immediately changed to 1.3. The roughing mill, finishing mill and coiler are accelerated at 1.3 times until the 6th block is coiled. Figure 2 shown.

Claims

1. A method for finishing endless rolling of hot-rolled strip steel, characterized in that: When hot strip rolling is converted from endless rolling mode to single-block rolling mode, the following operations are performed: ① Increase the speed of the tail coil in the headless rolling mode to keep a certain distance between the tail billet in the headless rolling mode and the subsequent single-block rolling mode billet; ② The tail coils in the endless rolling mode are the last six coils of steel, and the finished product thickness of the last six coils of steel is controlled at 2.0 mm; ③ Adjust the slab length corresponding to the last six coils of steel in the headless rolling mode so that the coil weight of the first four coils is the maximum weight of the coiler, and the corresponding slab is the maximum slab length; when adjusting the slab length corresponding to the last two coils, ensure that the head-to-tail connection point avoids the finishing mill, flying shear and TOP point. The head-to-tail connection point refers to the position where the tail of the previous coil and the head of the next coil are connected in the headless rolling mode. The TOP point is a tracking point in front of the finishing mill. When the head-to-tail connection point reaches this tracking point, the set value is sent to the finishing mill.

2. The method for finishing endless rolling of hot-rolled strip according to claim 1, characterized in that: The speed increase multiple of the tail coil in the headless rolling mode is 1.2-1.8 times. The speed increase multiple of the tail coil in the headless rolling mode refers to the speed increase multiple of the roughing mill, finishing mill and coiler after the tail billet in the headless rolling mode is disconnected from the slab in the subsequent single-block rolling mode.

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