A method for eliminating hot rolling camber defects

Abstract

The present invention relates to the technical field of hot-rolling shape control, and particularly to a method for eliminating the camber defect of hot-rolled steel strips. In the present invention, an auxiliary roll, also called a tension roll, is provided in front of and behind each rolling mill. The tension roll is characterized by a small roll diameter, aiming to be close to the main roll; the horizontal distance between the main roll and the tension roll is 1 to 1.5 m; the tension roll on the inlet side of the main roll is used to establish the back tension of the strip steel between the main roll and the tension roll; the tension roll on the outlet side of the main roll is used to establish the front tension of the strip steel between the main roll and the tension roll; the distance between the main roll and the tension roll is much smaller than the distance between the main rolls. The distance lacking tension during the rolling of the strip head and tail by each rolling mill becomes very short compared with the prior art. Therefore, the camber of the strip head and tail can be eliminated to a great extent. After the hot-rolled steel coil reaches the front process of cold rolling, only 1 to 2 m of the strip head needs to be sheared.

Description

Technical Field

[0001] The present invention relates to the technical field of hot rolling shape control, and particularly to a method for eliminating the camber defect in hot rolling. Background Art

[0002] Tension rolling is an important condition for obtaining good strip shape. The reason why good strip shape can be obtained by tension rolling is that the rolled piece can be bitten into the roll flatly under the condition of tension, thus ensuring the consistency of the reduction rate and elongation rate of each point in the transverse direction of the strip. The so-called strip tension is the tension force borne by the strip, which is established by the speed difference of the front and rear driving devices. For example, the speed of the 2# finishing mill is greater than that of the 1# finishing mill, and the speed of the 5# finishing mill is greater than that of the 4# finishing mill. Figure 1 After the strip head enters the coiler, the rolling mill is in a normal tension rolling state.

[0003] As Figure 2 shown, in the existing head rolling process, when the strip head enters each rolling mill, there is a section where the front tension is missing until the strip head is bitten by the next rolling mill or wound by the coiler. Since the 5 - 6m length of the strip head is rolled under the state of missing front tension through each rolling mill, the strip head generates camber, which becomes the strip tail of the steel coil after coiling. After the steel coil reaches the front process of cold rolling, 10 - 12m of the strip tail of the steel coil needs to be cut off to remove the camber defect.

[0004] As Figure 3 shown, in the existing strip head and tail rolling process, when the strip tail leaves each rolling mill, there is a section where the rear tension is missing. Since the strip tail is rolled under the state of missing rear tension through each rolling mill, camber is generated, which becomes the strip head of the steel coil after coiling. After the steel coil reaches the front process of cold rolling, 5 - 10m of the strip head of the steel coil needs to be cut off to remove the camber defect.

[0005] The quality of hot rolled strip shape has a great impact on the production efficiency and product quality of cold rolling. The non-tension rolling of the strip head and tail causes the camber defects at the head and tail of the hot rolled strip. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a method for eliminating the camber defect in hot rolling, so as to eliminate the camber at the head and tail of the hot rolled strip and improve the production efficiency and benefits of the subsequent process - cold rolling.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for eliminating the camber defect in hot rolling. The hot rolling mill is equipped with N finishing mills, where N ≥ 5, and the N finishing mills are arranged in sequence along the running direction of the strip steel, namely the 1# finishing mill, 2# finishing mill, 3# finishing mill, 4# finishing mill, 5# finishing mill... N# finishing mill. Specifically, it includes:

[0009] 1) A rear tension roll R1 is set behind the main roll of the 1# finishing mill, and a front tension roll P1 is set in front of the main roll of the 1# finishing mill; a rear tension roll R2 is set behind the main roll of the 2# finishing mill, and a front tension roll P2 is set in front of the main roll of the 2# finishing mill; a rear tension roll R3 is set behind the main roll of the 3# finishing mill, and a front tension roll P3 is set in front of the main roll of the 3# finishing mill; a rear tension roll R4 is set behind the main roll of the 4# finishing mill, and a front tension roll P4 is set in front of the main roll of the 4# finishing mill; a rear tension roll R5 is set behind the main roll of the 5# finishing mill, and a front tension roll P5 is set in front of the main roll of the 5# finishing mill... a rear tension roll Rn is set behind the main roll of the N# finishing mill, and a front tension roll Pn is set in front of the main roll of the N# finishing mill;

[0010] 2) Head rolling

[0011] ① The initial states of R1 to Rn are in the open state;

[0012] ② Through the 1# finishing mill → rolling with the head in a state of lacking front tension → after the head travels 1 - 1.5 m, it enters P1 → P1 compresses the head with a reduction rate of 5% - 10% → the inlet speed of the strip steel at P1 is greater than the outlet speed at the 1# finishing mill → a strip steel tension is established between the 1# finishing mill and P1 → that is, after the head passes through P1, the subsequent strip steel is rolled under tension;

[0013] ③ The head enters the 2# finishing mill, and a strip steel tension is established between the 1# finishing mill and the 2# finishing mill. The task of P1 is completed → P1 is lowered and opened → the head passes through the 2# finishing mill → rolling with the head in a state of lacking front tension → after the head travels 1 - 1.5 m, it enters P2 → P2 compresses the head with a reduction rate of 5% - 10% → the inlet speed of the strip steel at P2 is greater than the outlet speed at the 2# finishing mill → a strip steel tension is established between the 2# finishing mill and P2 → that is, after the head passes through P2, the subsequent strip steel is rolled under tension;

[0014] ④ The head enters the 3# finishing mill, and a strip steel tension is established between the 2# finishing mill and the 3# finishing mill. The task of P2 is completed → P2 is lowered and opened → the head passes through the 3# finishing mill → rolling with the head in a state of lacking front tension → after the head travels 1 - 1.5 m, it enters P3 → P3 compresses the head with a reduction rate of 5% - 10% → the inlet speed of the strip steel at P3 is greater than the outlet speed at the 3# finishing mill → a strip steel tension is established between the 3# finishing mill and P3 → that is, after the head passes through P3, the subsequent strip steel is rolled under tension;

[0015] ⑤ The leading end enters the 4# finishing mill, strip tension is established between the 3# and 4# finishing mills, P3 task completed → P3 screwdown opened → the leading end passes through the 4# finishing mill → the leading end is rolled under the condition of lack of front tension → the leading end travels 1 - 1.5 m and enters P4 → P4 compresses the leading end at a reduction rate of 5% - 10% → the entry speed of the strip at P4 is greater than the exit speed at the 4# finishing mill → strip tension is established between the 4# finishing mill and P4 → that is, after the leading end passes through P4, the subsequent strip is rolled under tension;

[0016] ⑥ The leading end enters the 5# finishing mill, strip tension is established between the 4# and 5# finishing mills, P4 task completed → P4 screwdown opened → the leading end passes through the 5# finishing mill → the leading end is rolled under the condition of lack of front tension → the leading end travels 1 - 1.5 m and enters P5 → P5 compresses the leading end at a reduction rate of 5% - 10% → the entry speed of the strip at P5 is greater than the exit speed at the 5# finishing mill → strip tension is established between the 5# finishing mill and P5 → that is, after the leading end passes through P5, the subsequent strip is rolled under tension;

[0017] ⑦ Until the leading end enters the N# finishing mill, strip tension is established between the N - 1# and N# finishing mills, Pn - 1 task completed → Pn - 1 screwdown opened → the leading end passes through the N# finishing mill → the leading end is rolled under the condition of lack of front tension → the leading end travels 1 - 1.5 m and enters Pn → Pn compresses the leading end at a reduction rate of 5% - 10% → the entry speed of the strip at Pn is greater than the exit speed at the N# finishing mill → strip tension is established between the N# finishing mill and Pn → that is, after the leading end passes through Pn, the subsequent strip is rolled under tension;

[0018] ⑧ After the leading end enters the coiler and winds 2 turns, strip tension is established between the coiler and the N# rolling mill, Pn task completed, Pn screwdown opened, and the subsequent strip is rolled under tension;

[0019] 3) Tail rolling

[0020] The initial states of R1 - Rn are in the open state. When a strip is approaching the tail during rolling, R1 - Rn are screwed down to compress the strip at a reduction rate of 5% - 10% to prepare for tail rolling;

[0021] ① After the strip tail leaves R1, R1 task completed → R1 screwdown lifted → the strip tail is rolled for a distance of 1 - 1.5 m under the condition of lack of back tension behind the 1# finishing mill;

[0022] ② When the strip tail leaves R2, R2 task completed → R2 screwdown lifted → the strip tail is rolled for a distance of 1 - 1.5 m under the condition of lack of back tension behind the 2# finishing mill;

[0023] ③The strip tail leaves R3, and the task of R3 is completed → The R3 screwdown is lifted → The strip tail is rolled at a distance of 1 - 1.5 m under the condition of lack of back tension behind the 3# finishing mill. Compared with the prior art, the strip tail is rolled without back tension starting from leaving the 2# finishing mill;

[0024] ④The strip tail leaves R4, and the task of R4 is completed → The R4 screwdown is lifted → The strip tail is rolled at a distance of 1 - 1.5 m under the condition of lack of back tension behind the 4# finishing mill;

[0025] ⑤The strip tail leaves R5, and the task of R5 is completed → The R5 screwdown is lifted → The strip tail is rolled at a distance of 1 - 1.5 m under the condition of lack of back tension behind the 5# finishing mill;

[0026] ⑥Until the strip tail leaves Rn, the task of Rn is completed → The Rn screwdown is lifted → The strip tail is rolled at a distance of 1 - 1.5 m under the condition of lack of back tension behind the N# finishing mill.

[0027] Furthermore, the diameter of the tension roll is 400 - 500 mm.

[0028] Furthermore, the roughness of the tension roll is 3 - 4 μm.

[0029] Furthermore, the distance between the main roll of the finishing mill and the tension roll is 1 - 1.5 m.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] In the present invention, an auxiliary roll, also called a tension roll, is provided in front of and behind each rolling mill. The tension roll is characterized by a small roll diameter, and the purpose is to be able to be close to the main roll; the horizontal distance between the main roll and the tension roll is 1 - 1.5 m; the tension roll on the entrance side of the main roll is used to establish the back tension of the strip between the main roll and the tension roll; the tension roll on the exit side of the main roll is used to establish the front tension of the strip between the main roll and the tension roll; the distance between the main roll and the tension roll is much smaller than the distance between the main rolls. The distance lacking tension during the rolling process of the strip head and tail in each rolling mill becomes very short compared with the main rolling mill. Therefore, the camber at the head and tail of the hot-rolled strip can be largely eliminated. After the hot-rolled steel coil reaches the front cold rolling process, only 1 - 2 m of the strip head and tail need to be sheared.

[0032] The shearing length of the head and tail of the hot-rolled strip becomes smaller during cold rolling, decreasing from 10 m in the past to 1.5 m currently. The number of cut heads and tails of the hot-rolled steel coil in the front cold rolling process decreases from 19,000 - 20,000 tons / year to 2,800 - 3,000 tons / year.

[0033] Due to the reduction of the camber at the head and tail of the strip, the number of shearing times at the head and tail of the strip becomes less; the running edge times in the edge trimming process are reduced by 90%, improving the operation efficiency of the unit.

[0034] Due to the reduction of the sickle camber at the head and tail of the strip steel, the size and quantity of the strip steel edge overflow before and after the weld during cold rolling coiling are reduced, and the ratio of hemming generated after stacking annealing is reduced by 90%. Description of the Drawings

[0035] Figure 1 It is a diagram of the normal tension rolling state of the rolling mill after the head of the existing strip steel enters the coiler;

[0036] Figure 2 It is a schematic diagram of the rolling process of the existing strip steel head;

[0037] Figure 3 It is a schematic diagram of the rolling process of the existing strip steel tail;

[0038] Figure 4 It is a schematic diagram of the rolling process of the present invention. Detailed Embodiment

[0039] Next, in combination with the examples of the present invention, the technical solutions of the present invention will be clearly and completely described. Obviously, the described implementation cases are only one of the embodiments of the present invention. Those skilled in the art can draw on the content of this article and appropriately modify the process parameters to achieve. It should be particularly pointed out that all similar substitutions and modifications are obvious to those skilled in the art, and they are all regarded as included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and those related can obviously make changes or appropriate changes and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0040] A method for eliminating the hot-rolled sickle camber defect. The hot-rolling mill is provided with N finishing mills, N≥5, and the N finishing mills are arranged in sequence along the running direction of the strip steel, namely 1# finishing mill, 2# finishing mill, 3# finishing mill, 4# finishing mill, 5# finishing mill... N# finishing mill; specifically including:

[0041] 1. A rear tension roll R1 is arranged behind the main roll of the 1# finishing mill, and a front tension roll P1 is arranged in front of the main roll of the 1# finishing mill; a rear tension roll R2 is arranged behind the main roll of the 2# finishing mill, and a front tension roll P2 is arranged in front of the main roll of the 2# finishing mill; a rear tension roll R3 is arranged behind the main roll of the 3# finishing mill, and a front tension roll P3 is arranged in front of the main roll of the 3# finishing mill; a rear tension roll R4 is arranged behind the main roll of the 4# finishing mill, and a front tension roll P4 is arranged in front of the main roll of the 4# finishing mill; a rear tension roll R5 is arranged behind the main roll of the 5# finishing mill, and a front tension roll P5 is arranged in front of the main roll of the 5# finishing mill... a rear tension roll Rn is arranged behind the main roll of the N# finishing mill, and a front tension roll Pn is arranged in front of the main roll of the N# finishing mill.

[0042] Set the back tension roll R1 of the finishing mill #1. Its function is to press down R1 during the rolling process to establish the back tension of the strip being rolled by the finishing mill #1, and R1 is lifted when the tail of the strip leaves the finishing mill #1. Set the front tension roll P1 of the finishing mill #1. Its function is to establish the front tension of the strip being rolled by the finishing mill #1 after the head of the strip is bitten by P1 during the rolling process, and P1 is lifted after the head of the strip enters the finishing mill #2. Set the back tension roll R2 of the finishing mill #2. Its function is to press down R2 when the tail of the strip is about to leave the finishing mill #1 during the rolling process to establish the back tension of the strip being rolled by the finishing mill #2, and R2 is lifted when the tail of the strip leaves the finishing mill #2. Set the front tension roll P2 of the finishing mill #2. Its function is to establish the front tension of the strip being rolled by the finishing mill #2 after the head of the strip is bitten by P2 during the rolling process, and P2 is lifted after the head of the strip enters the finishing mill #3. Set the back tension roll R3 of the finishing mill #3. Its function is to press down R3 when the tail of the strip is about to leave the finishing mill #2 during the rolling process to establish the back tension of the strip being rolled by the finishing mill #3, and R3 is lifted when the tail of the strip leaves the finishing mill #3. Set the front tension roll P3 of the finishing mill #3. Its function is to establish the front tension of the strip being rolled by the finishing mill #3 after the head of the strip is bitten by P3 during the rolling process, and P3 is lifted after the head of the strip enters the finishing mill #4. Set the back tension roll R4 of the finishing mill #4. Its function is to press down R4 when the tail of the strip is about to leave the finishing mill #3 during the rolling process to establish the back tension of the strip being rolled by the finishing mill #4, and R4 is lifted when the tail of the strip leaves the finishing mill #4. Set the front tension roll P4 of the finishing mill #4. Its function is to establish the front tension of the strip being rolled by the finishing mill #4 after the head of the strip is bitten by P4 during the rolling process, and P4 is lifted after the head of the strip enters the finishing mill #5. Set the back tension roll R5 of the finishing mill #5. Its function is to press down R5 when the tail of the strip is about to leave the finishing mill #4 during the rolling process to establish the back tension of the strip being rolled by the finishing mill #5, and R5 is lifted when the tail of the strip leaves the finishing mill #5. Set the front tension roll P5 of the finishing mill #5. Its function is to establish the front tension of the strip being rolled by the finishing mill #5 after the head of the strip is bitten by P5 during the rolling process, and P5 is lifted after the head of the strip enters the coiler. Set the front tension roll Pn of the finishing mill #N. Its function is to establish the front tension of the strip being rolled by the finishing mill #N after the head of the strip is bitten by Pn during the rolling process, and Pn is lifted after the head of the strip enters the coiler.

[0043] Key points for setting the tension rolls in the present invention:

[0044] The diameter of all tension rolls is 400 - 500 mm. It is smaller than the diameter of the main rolling roll, aiming to be closer to the main rolling roll. The closer the distance between the main rolling roll and the tension roll, the shorter the length of the strip rolling without tension. The surface roughness of all tension rolls is 3 - 4 μm. A larger surface roughness of the roll surface can increase the friction between the roll and the strip, which helps to establish the tension between the main rolling roll and the tension roll. The distance between all main rolling rolls and tension rolls is 1 - 1.5 m. The closer the distance between the main rolling roll and the tension roll, the shorter the length of the strip rolling without tension.

[0045] II. The rolling process of the strip head

[0046] 1. The initial states of R1 - R5 are open.

[0047] 2. Pass through the 1# finishing mill → The strip head is rolled under the state of lacking front tension → After the strip head travels 1 - 1.5 m, it enters P1 → P1 compresses the strip head with a reduction rate of 5% - 10% → The inlet speed of the strip at P1 is greater than the outlet speed of the strip at the 1# finishing mill → The strip tension is established between the 1# finishing mill and P1 → That is, after the strip head passes through P1, the subsequent strip is rolled under the tension state. Compared with the existing technology, the strip tension between the 1# finishing mill and the 2# finishing mill can only be established after the strip head travels to the roll gap of the 2# finishing mill.

[0048] 3. The strip head enters the 2# finishing mill, the strip tension is established between the 1# finishing mill and the 2# finishing mill, and the task of P1 is completed → The reduction of P1 is opened → The strip head passes through the 2# finishing mill → The strip head is rolled under the state of lacking front tension → After the strip head travels 1 - 1.5 m, it enters P2 → P2 compresses the strip head with a reduction rate of 5% - 10% → The inlet speed of the strip at P2 is greater than the outlet speed of the strip at the 2# finishing mill → The strip tension is established between the 2# finishing mill and P2 → That is, after the strip head passes through P2, the subsequent strip is rolled under the tension state. Compared with the existing technology, the strip tension between the 2# finishing mill and the 3# finishing mill can only be established after the strip head travels to the roll gap of the 3# finishing mill.

[0049] 4. The strip head enters the 3# finishing mill, the strip tension is established between the 2# finishing mill and the 3# finishing mill, and the task of P2 is completed → The reduction of P2 is opened → The strip head passes through the 3# finishing mill → The strip head is rolled under the state of lacking front tension → After the strip head travels 1 - 1.5 m, it enters P3 → P3 compresses the strip head with a reduction rate of 5% - 10% → The inlet speed of the strip at P3 is greater than the outlet speed of the strip at the 3# finishing mill → The strip tension is established between the 3# finishing mill and P3 → That is, after the strip head passes through P3, the subsequent strip is rolled under the tension state. Compared with the existing technology, the strip tension between the 3# finishing mill and the 4# finishing mill can only be established after the strip head travels to the roll gap of the 4# finishing mill.

[0050] 5. The strip head enters the 4# finishing mill, the strip tension is established between the 3# finishing mill and the 4# finishing mill, and the task of P3 is completed → The reduction of P3 is opened → The strip head passes through the 4# finishing mill → The strip head is rolled under the state of lacking front tension → After the strip head travels 1 - 1.5 m, it enters P4 → P4 compresses the strip head with a reduction rate of 5% - 10% → The inlet speed of the strip at P4 is greater than the outlet speed of the strip at the 4# finishing mill → The strip tension is established between the 4# finishing mill and P4 → That is, after the strip head passes through P4, the subsequent strip is rolled under the tension state. Compared with the existing technology, the strip tension between the 4# finishing mill and the 5# finishing mill can only be established after the strip head travels to the roll gap of the 5# finishing mill.

[0051] 6. The leading end enters the 5# finishing mill, strip tension is established between the 4# and 5# finishing mills, P4 task completed → P4 screw down opened → the leading end passes through the 5# finishing mill → the leading end is rolled under the state of lacking front tension → the leading end travels 1 - 1.5 m and enters P5 → P5 compresses the leading end with a reduction rate of 5% - 10% → the inlet speed of the strip at P5 is greater than the outlet speed of the strip at the 5# finishing mill → strip tension is established between the 5# finishing mill and P5 → that is, after the leading end passes through P5, the subsequent strip is rolled under tension. Compared with the prior art, the strip tension between the 5# finishing mill and the coiler can only be established after the leading end travels to the coiler.

[0052] 7. The leading end enters the N# finishing mill, strip tension is established between the N - 1# and N# finishing mills, Pn - 1 task completed → Pn - 1 screw down opened → the leading end passes through the N# finishing mill → the leading end is rolled under the state of lacking front tension → the leading end travels 1 - 1.5 m and enters Pn → Pn compresses the leading end with a reduction rate of 5% - 10% → the inlet speed of the strip at Pn is greater than the outlet speed of the strip at the N# finishing mill → strip tension is established between the N# finishing mill and Pn → that is, after the leading end passes through Pn, the subsequent strip is rolled under tension. Compared with the prior art, the strip tension between the N# finishing mill and the coiler can only be established after the leading end travels to the coiler.

[0053] 8. After the leading end enters the coiler and winds 2 turns, strip tension is established between the coiler and the N# rolling mill, Pn task completed, Pn screw down opened, and the subsequent strip is rolled under tension.

[0054] III. Rolling process of the strip tail

[0055] The initial states of R1 - R5 are in the open state. When a strip is approaching the strip tail during rolling, R1 - R5 are screwed down to compress the strip with a reduction rate of 5% - 10% to prepare for the rolling of the strip tail.

[0056] 1. After the strip tail leaves R1, R1 task completed → R1 screw down lifted → the strip tail within a distance of 1 - 1.5 m is rolled under the state of lacking rear tension behind the 1# finishing mill.

[0057] 2. When the strip tail leaves R2, R2 task completed → R2 screw down lifted → the strip tail within a distance of 1 - 1.5 m is rolled under the state of lacking rear tension behind the 2# finishing mill. Compared with the prior art, the strip rolling without rear tension starts from leaving the 1# finishing mill.

[0058] 3. When the strip tail leaves R3, R3 task completed → R3 screw down lifted → the strip tail within a distance of 1 - 1.5 m is rolled under the state of lacking rear tension behind the 3# finishing mill. Compared with the prior art, the strip rolling without rear tension starts from leaving the 2# finishing mill.

[0059] 4. The strip tail leaves R4, and the task of R4 is completed → the R4 screwdown is lifted → the strip tail is rolled with a lack of back tension in the 4# finishing mill for a distance of 1 - 1.5 m. Compared with the prior art, the strip tail is rolled without back tension starting from leaving the 3# finishing mill.

[0060] 5. The strip tail leaves R5, and the task of R5 is completed → the R5 screwdown is lifted → the strip tail is rolled with a lack of back tension in the 5# finishing mill for a distance of 1 - 1.5 m. Compared with the prior art, the strip tail is rolled without back tension starting from leaving the 4# finishing mill.

[0061] 6. The strip tail leaves Rn, and the task of Rn is completed → the Rn screwdown is lifted → the strip tail is rolled with a lack of back tension in the N# finishing mill for a distance of 1 - 1.5 m. Compared with the prior art, the strip tail is rolled without back tension starting from leaving the (N - 1)# finishing mill.

[0062]

Embodiment

[0063] As Figure 4 shown, a method for eliminating the hot-rolled camber defect, the hot-rolling mill unit is provided with 5 finishing mills, and the 5 finishing mills are arranged in sequence along the strip running direction, which are the 1# finishing mill, 2# finishing mill, 3# finishing mill, 4# finishing mill, and 5# finishing mill; specifically including:

[0064] I. A back tension roll R1 is arranged behind the main roll of the 1# finishing mill, and a front tension roll P1 is arranged in front of the main roll of the 1# finishing mill; a back tension roll R2 is arranged behind the main roll of the 2# finishing mill, and a front tension roll P2 is arranged in front of the main roll of the 2# finishing mill; a back tension roll R3 is arranged behind the main roll of the 3# finishing mill, and a front tension roll P3 is arranged in front of the main roll of the 3# finishing mill; a back tension roll R4 is arranged behind the main roll of the 4# finishing mill, and a front tension roll P4 is arranged in front of the main roll of the 4# finishing mill; a back tension roll R5 is arranged behind the main roll of the 5# finishing mill, and a front tension roll is arranged in front of the main roll of the 5# finishing mill.

[0065] Set the back tension roll R1 of the No. 1 finishing mill. Its function is that during the rolling process, R1 is lowered to establish the back tension of the strip being rolled by the No. 1 finishing mill, and R1 is lifted when the tail of the strip leaves the No. 1 finishing mill. Set the front tension roll P1 of the No. 1 finishing mill. Its function is that after the head of the strip is bitten by P1 during the rolling process, the front tension of the strip being rolled by the No. 1 finishing mill is established, and P1 is lifted after the head of the strip enters the No. 2 finishing mill. Set the back tension roll R2 of the No. 2 finishing mill. Its function is that when the tail of the strip is about to leave the No. 1 finishing mill during the rolling process, R2 is lowered to establish the back tension of the strip being rolled by the No. 2 finishing mill, and R2 is lifted when the tail of the strip leaves the No. 2 finishing mill. Set the front tension roll P2 of the No. 2 finishing mill. Its function is that after the head of the strip is bitten by P2 during the rolling process, the front tension of the strip being rolled by the No. 2 finishing mill is established, and P2 is lifted after the head of the strip enters the No. 3 finishing mill. Set the back tension roll R3 of the No. 3 finishing mill. Its function is that when the tail of the strip is about to leave the No. 2 finishing mill during the rolling process, R3 is lowered to establish the back tension of the strip being rolled by the No. 3 finishing mill, and R3 is lifted when the tail of the strip leaves the No. 3 finishing mill. Set the front tension roll P3 of the No. 3 finishing mill. Its function is that after the head of the strip is bitten by P3 during the rolling process, the front tension of the strip being rolled by the No. 3 finishing mill is established, and P3 is lifted after the head of the strip enters the No. 4 finishing mill. Set the back tension roll R4 of the No. 4 finishing mill. Its function is that when the tail of the strip is about to leave the No. 3 finishing mill during the rolling process, R4 is lowered to establish the back tension of the strip being rolled by the No. 4 finishing mill, and R4 is lifted when the tail of the strip leaves the No. 4 finishing mill. Set the front tension roll P4 of the No. 4 finishing mill. Its function is that after the head of the strip is bitten by P4 during the rolling process, the front tension of the strip being rolled by the No. 4 finishing mill is established, and P4 is lifted after the head of the strip enters the No. 5 finishing mill. Set the back tension roll R5 of the No. 5 finishing mill. Its function is that when the tail of the strip is about to leave the No. 4 finishing mill during the rolling process, R5 is lowered to establish the back tension of the strip being rolled by the No. 5 finishing mill, and R5 is lifted when the tail of the strip leaves the No. 5 finishing mill. Set the front tension roll P5 of the No. 5 finishing mill. Its function is that after the head of the strip is bitten by P5 during the rolling process, the front tension of the strip being rolled by the No. 5 finishing mill is established, and P5 is lifted after the head of the strip enters the coiler.

[0066] Key points for setting the tension rolls of the present invention: The diameter of all tension rolls is 400 - 500 mm. It is smaller than the diameter of the main rolling roll, aiming to be closer to the main rolling roll. The closer the distance between the main rolling roll and the tension roll, the shorter the length of the strip rolling without tension. The surface roughness of all tension rolls is 3 - 4 μm. A larger surface roughness of the roll surface increases the friction between the roll and the strip, which helps to establish the tension between the main rolling roll and the tension roll. The distance between all main rolling rolls and tension rolls is 1 - 1.5 m. The closer the distance between the main rolling roll and the tension roll, the shorter the length of the strip rolling without tension.

[0067] II. Rolling process of the head of the strip of the present invention

[0068] 1. The initial state of R1 - R5 is in the open state;

[0069] 2. The leading end passes through the 1st finishing mill → rolling is carried out with the leading end in a state of lacking front tension → after the leading end travels 1 - 1.5 m, it enters P1 → P1 compresses the leading end with a reduction rate of 5% - 10% → the inlet speed of the strip at P1 is greater than the outlet speed of the strip at the 1st finishing mill → strip tension is established between the 1st finishing mill and P1 → that is, after the leading end passes through P1, the subsequent strip is rolled under tension. Compared with the prior art, the strip tension between the 1st finishing mill and the 2nd finishing mill can only be established after the leading end travels to the roll gap of the 2nd finishing mill.

[0070] 3. The leading end enters the 2nd finishing mill, strip tension is established between the 1st finishing mill and the 2nd finishing mill, and the task of P1 is completed → the reduction of P1 is opened → the leading end passes through the 2nd finishing mill → rolling is carried out with the leading end in a state of lacking front tension → the leading end travels 1 - 1.5 m and enters P2 → P2 compresses the leading end with a reduction rate of 5% - 10% → the inlet speed of the strip at P2 is greater than the outlet speed of the strip at the 2nd finishing mill → strip tension is established between the 2nd finishing mill and P2 → that is, after the leading end passes through P2, the subsequent strip is rolled under tension. Compared with the prior art, the strip tension between the 2nd finishing mill and the 3rd finishing mill can only be established after the leading end travels to the roll gap of the 3rd finishing mill.

[0071] 4. The leading end enters the 3rd finishing mill, strip tension is established between the 2nd finishing mill and the 3rd finishing mill, and the task of P2 is completed → the reduction of P2 is opened → the leading end passes through the 3rd finishing mill → rolling is carried out with the leading end in a state of lacking front tension → the leading end travels 1 - 1.5 m and enters P3 → P3 compresses the leading end with a reduction rate of 5% - 10% → the inlet speed of the strip at P3 is greater than the outlet speed of the strip at the 3rd finishing mill → strip tension is established between the 3rd finishing mill and P3 → that is, after the leading end passes through P3, the subsequent strip is rolled under tension. Compared with the prior art, the strip tension between the 3rd finishing mill and the 4th finishing mill can only be established after the leading end travels to the roll gap of the 4th finishing mill.

[0072] 5. The leading end enters the 4th finishing mill, strip tension is established between the 3rd finishing mill and the 4th finishing mill, and the task of P3 is completed → the reduction of P3 is opened → the leading end passes through the 4th finishing mill → rolling is carried out with the leading end in a state of lacking front tension → the leading end travels 1 - 1.5 m and enters P4 → P4 compresses the leading end with a reduction rate of 5% - 10% → the inlet speed of the strip at P4 is greater than the outlet speed of the strip at the 4th finishing mill → strip tension is established between the 4th finishing mill and P4 → that is, after the leading end passes through P4, the subsequent strip is rolled under tension. Compared with the prior art, the strip tension between the 4th finishing mill and the 5th finishing mill can only be established after the leading end travels to the roll gap of the 5th finishing mill.

[0073] 6. The leading end enters the No. 5 finishing mill, strip tension is established between the No. 4 and No. 5 finishing mills, P4 task is completed → P4 screwdown is opened → the leading end passes through the No. 5 finishing mill → the leading end is rolled under the state of lacking front tension → the leading end travels 1 - 1.5 m and enters P5 → P5 compresses the leading end with a reduction rate of 5% - 10% → the inlet speed of the strip at P5 is greater than the outlet speed of the strip at the No. 5 finishing mill → strip tension is established between the No. 5 finishing mill and P5 → that is, after the leading end passes through P5, the subsequent strip is rolled under tension. Compared with the prior art, the strip tension between the No. 5 finishing mill and the coiler can only be established after the leading end travels to the coiler.

[0074] 7. After the leading end enters the coiler and winds 2 turns, strip tension is established between the coiler and the No. 5 rolling mill, P5 task is completed, P5 screwdown is opened, and the subsequent strip is rolled under tension.

[0075] III. The rolling process of the strip tail of the present invention

[0076] The initial states of R1 - R5 are in the open state. When a strip is rolled near the strip tail, R1 - R5 are screwed down to compress the strip with a reduction rate of 5% - 10% to prepare for the rolling of the strip tail;

[0077] 1. After the strip tail leaves R1, R1 task is completed → R1 screwdown is lifted → the strip tail is rolled for a distance of 1 - 1.5 m under the state of lacking rear tension behind the No. 1 finishing mill.

[0078] 2. When the strip tail leaves R2, R2 task is completed → R2 screwdown is lifted → the strip tail is rolled for a distance of 1 - 1.5 m under the state of lacking rear tension behind the No. 2 finishing mill. Compared with the prior art, the strip tail is rolled without rear tension starting from leaving the No. 1 finishing mill.

[0079] 3. When the strip tail leaves R3, R3 task is completed → R3 screwdown is lifted → the strip tail is rolled for a distance of 1 - 1.5 m under the state of lacking rear tension behind the No. 3 finishing mill. Compared with the prior art, the strip tail is rolled without rear tension starting from leaving the No. 2 finishing mill.

[0080] 4. When the strip tail leaves R4, R4 task is completed → R4 screwdown is lifted → the strip tail is rolled for a distance of 1 - 1.5 m under the state of lacking rear tension behind the No. 4 finishing mill. Compared with the prior art, the strip tail is rolled without rear tension starting from leaving the No. 3 finishing mill.

[0081] 5. When the strip tail leaves R5, R5 task is completed → R5 screwdown is lifted → the strip tail is rolled for a distance of 1 - 1.5 m under the state of lacking rear tension behind the No. 5 finishing mill. Compared with the prior art, the strip tail is rolled without rear tension starting from leaving the No. 4 finishing mill.

[0082] In the present invention, small-diameter rollers R1-R5 with very close distances are added at the inlets of each finishing mill; small-diameter rollers P1-P5 with very close distances are added at the outlets of each finishing mill. In the prior art, each rolling mill only has a large-diameter main rolling mill; each rolling mill in the present invention includes a large-diameter main rolling mill and a pair of small-diameter auxiliary rolling mills.

[0083] The small-diameter auxiliary rollers P1-P5 are very close to their respective main rolling mills. After the reduction is applied to establish tension during head rolling, the rolling distance in the state of lacking front tension before the head is reduced, thus greatly reducing the length of the sickle bend at the tail of the steel coil. The small-diameter auxiliary rollers R1-R5 are very close to their respective main rolling mills. After the reduction is applied to establish tension during tail rolling, the rolling distance in the state of lacking back tension after the tail is reduced, thus greatly reducing the length of the sickle bend at the head of the steel coil. Under the conditions of the prior art, the rolling distances of the head and tail of the strip steel in the non-tension state are relatively long, so the lengths of the sickle bends generated at the head and tail of the strip steel are relatively large. Under the conditions of the present invention, the rolling distances of the head and tail of the strip steel in the non-tension state are relatively short, so the lengths of the sickle bends generated at the head and tail of the strip steel are relatively small.

[0084] After adopting the method of the present invention, the lengths of the sickle bends at the head and tail of the hot-rolled strip steel are reduced from 10 - 12 m to 1 - 2 m. The lengths of the head and tail of the hot-rolled strip steel during cold rolling and shearing become smaller, from 10 m in the past to 1.5 m at present. The quantities of the head and tail cutting of the hot-rolled steel coil in the front process of cold rolling are reduced from 19,000 - 20,000 tons / year to 2,800 - 3,000 tons / year. Due to the reduction of the sickle bends at the head and tail of the strip steel, the number of shearing times at the head and tail of the strip steel becomes smaller; the running-edge times in the edge-trimming process are reduced by 90%, improving the operation efficiency of the unit. Due to the reduction of the sickle bends at the head and tail of the strip steel, the sizes and quantities of the strip steel edge overflow before and after the weld during cold rolling coiling are reduced, and the ratio of the occurrence of hemming after stacking annealing is reduced by 90%.

[0085] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.

Claims

1. A method for eliminating the camber defect in hot rolling. The hot rolling mill unit is equipped with N finishing mills, where N ≥ 5, and the N finishing mills are arranged in sequence along the running direction of the strip steel, namely the 1# finishing mill, 2# finishing mill, 3# finishing mill, 4# finishing mill, 5# finishing mill... N# finishing mill; it is characterized in that, Specifically including: 1) A rear tension roll R1 is arranged behind the main rolling roll of the 1# finishing mill, and a front tension roll P1 is arranged in front of the main rolling roll of the 1# finishing mill; a rear tension roll R2 is arranged behind the main rolling roll of the 2# finishing mill, and a front tension roll P2 is arranged in front of the main rolling roll of the 2# finishing mill; a rear tension roll R3 is arranged behind the main rolling roll of the 3# finishing mill, and a front tension roll P3 is arranged in front of the main rolling roll of the 3# finishing mill; a rear tension roll R4 is arranged behind the main rolling roll of the 4# finishing mill, and a front tension roll P4 is arranged in front of the main rolling roll of the 4# finishing mill; a rear tension roll R5 is arranged behind the main rolling roll of the 5# finishing mill, and a front tension roll P5 is arranged in front of the main rolling roll of the 5# finishing mill... A rear tension roll Rn is arranged behind the main rolling roll of the N# finishing mill, and a front tension roll Pn is arranged in front of the main rolling roll of the N# finishing mill; 2) Head rolling ① The initial states of R1 to Rn are in the open state; ② The head passes through the 1# finishing mill → The head is rolled under the state of lacking front tension → After the head travels 1 - 1.5 m, it enters P1 → P1 compresses the head with a reduction rate of 5% - 10% → The inlet speed of the strip at P1 is greater than the outlet speed of the strip at the 1# finishing mill → The strip tension is established between the 1# finishing mill and P1 → That is, after the head passes through P1, the subsequent strip is rolled under the tension state; ③ The head enters the 2# finishing mill, and the strip tension is established between the 1# finishing mill and the 2# finishing mill. The task of P1 is completed → P1 is lowered and opened → The head passes through the 2# finishing mill → The head is rolled under the state of lacking front tension → After the head travels 1 - 1.5 m, it enters P2 → P2 compresses the head with a reduction rate of 5% - 10% → The inlet speed of the strip at P2 is greater than the outlet speed of the strip at the 2# finishing mill → The strip tension is established between the 2# finishing mill and P2 → That is, after the head passes through P2, the subsequent strip is rolled under the tension state; ④ The head enters the 3# finishing mill, and the strip tension is established between the 2# finishing mill and the 3# finishing mill. The task of P2 is completed → P2 is lowered and opened → The head passes through the 3# finishing mill → The head is rolled under the state of lacking front tension → After the head travels 1 - 1.5 m, it enters P3 → P3 compresses the head with a reduction rate of 5% - 10% → The inlet speed of the strip at P3 is greater than the outlet speed of the strip at the 3# finishing mill → The strip tension is established between the 3# finishing mill and P3 → That is, after the head passes through P3, the subsequent strip is rolled under the tension state; ⑤ The head enters the 4# finishing mill, and the strip tension is established between the 3# finishing mill and the 4# finishing mill. The task of P3 is completed → P3 is lowered and opened → The head passes through the 4# finishing mill → The head is rolled under the state of lacking front tension → After the head travels 1 - 1.5 m, it enters P4 → P4 compresses the head with a reduction rate of 5% - 10% → The inlet speed of the strip at P4 is greater than the outlet speed of the strip at the 4# finishing mill → The strip tension is established between the 4# finishing mill and P4 → That is, after the head passes through P4, the subsequent strip is rolled under the tension state; ⑥The leading end enters the 5# finishing mill, strip tension is established between the 4# and 5# finishing mills, P4 task completed → P4 screwdown opened → leading end passes through the 5# finishing mill → rolling with the leading end in a state of lacking front tension → the leading end travels 1 - 1.5 m and enters P5 → P5 compresses the leading end with a reduction rate of 5% - 10% → the entry speed of the strip at P5 is greater than the exit speed at the 5# finishing mill → strip tension is established between the 5# finishing mill and P5 → that is, after the leading end passes through P5, the subsequent strip is rolled under tension; ⑦Until the leading end enters the N# finishing mill, strip tension is established between the N - 1# and N# finishing mills, Pn - 1 task completed → Pn - 1 screwdown opened → leading end passes through the N# finishing mill → rolling with the leading end in a state of lacking front tension → the leading end travels 1 - 1.5 m and enters Pn → Pn compresses the leading end with a reduction rate of 5% - 10% → the entry speed of the strip at Pn is greater than the exit speed at the N# finishing mill → strip tension is established between the N# finishing mill and Pn → that is, after the leading end passes through Pn, the subsequent strip is rolled under tension; ⑧After the leading end enters the coiler and winds 2 turns, strip tension is established between the coiler and the N# rolling mill, Pn task completed, Pn screwdown opened, and the subsequent strip is rolled under tension; 3) Tail rolling The initial states of R1 - Rn are open; when a strip is approaching its tail during rolling, R1 - Rn are screwed down to compress the strip with a reduction rate of 5% - 10% to prepare for tail rolling; ①After the strip tail leaves R1, R1 task completed → R1 screwdown lifted → the strip tail is rolled for 1 - 1.5 m in a state of lacking rear tension behind the 1# finishing mill; ②After the strip tail leaves R2, R2 task completed → R2 screwdown lifted → the strip tail is rolled for 1 - 1.5 m in a state of lacking rear tension behind the 2# finishing mill; ③After the strip tail leaves R3, R3 task completed → R3 screwdown lifted → the strip tail is rolled for 1 - 1.5 m in a state of lacking rear tension behind the 3# finishing mill; ④After the strip tail leaves R4, R4 task completed → R4 screwdown lifted → the strip tail is rolled for 1 - 1.5 m in a state of lacking rear tension behind the 4# finishing mill; ⑤After the strip tail leaves R5, R5 task completed → R5 screwdown lifted → the strip tail is rolled for 1 - 1.5 m in a state of lacking rear tension behind the 5# finishing mill; ⑥Until the strip tail leaves Rn, Rn task completed → Rn screwdown lifted → the strip tail is rolled for 1 - 1.5 m in a state of lacking rear tension behind the N# finishing mill.

2. The method for eliminating the hot rolling camber defect according to claim 1, characterized in that, The diameter of the tension roll is 400 - 500 mm.

3. A method for eliminating the camber defect in hot rolling according to claim 1, characterized in that, The roughness of the tension roll is 3 - 4 μm.

4. A method for eliminating the hot-rolled camber defect according to claim 1, characterized in that The horizontal distance between the main rolling roll of the finishing mill and the tension roll is 1 - 1.5 m.

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