Method for improving slab shape defect of corrugated edge of hot-rolled thin strip

Abstract

The invention relates to the technical field of hot continuous rolling, and particularly discloses a hot-rolled thin strip corrugated plate shape defect improvement method which comprises the following steps: step 1, tracking a hot-rolled thin strip production process, and determining a corrugated plate shape defect occurrence position; secondly, the abrasion state of the finish rolling working roller is analyzed, and the roller shifting interval of the working roller is adjusted according to the abrasion state; 3, analyzing the deviation condition of the center line of the strip steel finish rolling outlet, and optimizing the deviation direction of the strip steel; and step 4, tracking the bellow condition of the optimized hot-rolled thin-gauge strip steel, and further optimizing the channeling roll interval of the working roll and the deviation of the strip steel. By optimizing the working roll shifting interval and adjusting the deviation direction of the head of the strip steel, the strip steel corrugated-edge plate shape defect caused by the fact that the edge of the strip steel exceeds the roll abrasion step due to deviation in the strip steel threading process is avoided, hot rolling continuity and stability are improved, the planned total block number is increased, the corrugated-edge plate shape defect repair rate and smooth cutting loss are reduced, and the production efficiency is improved. And the comprehensive yield of the hot-rolled thin strip is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hot rolling, and in particular relates to a method for improving the ruffled plate shape defects of a hot-rolled thin strip. Background Art

[0002] Plate shape is an important indicator of the quality of hot-rolled strip products. The thinner the strip thickness, the more difficult it is to control the plate shape defects of the hot-rolled strip, and the more serious the plate shape defects are, which has a greater impact on the hot-rolled yield rate and downstream production stability. Hot-rolled strip shape defects generally refer to flatness defects, that is, during the hot rolling process, the thickness of the strip is reduced by different amounts at different positions in the width direction, causing uneven extension of the strip in the length direction, and the internal stress generated exceeds the yield limit of the strip, eventually forming visible wave-shaped defects.

[0003] Common strip shape defects are middle wave, single-side wave, double-side wave and quarter wave, which can be improved by reducing the bending roll force, adjusting the roll gap inclination of the rolling mill, increasing the bending roll force and optimizing the work roll shape. However, there is no detailed research and specific improvement method for the ruffle shape defect of hot-rolled thin strip.

[0004] The ruffled plate shape defect refers to a local plate shape defect that appears on the edge of the hot-rolled thin strip. Its wave-shaped manifestation is characterized by large wave height, narrow wave width and short wave period.

[0005] Once the ruffled plate shape defect occurs during the rolling process, conventional bending rolls, shifting rolls and roll gap leveling measures cannot improve it. The steel coil must be repaired and cut off in the flattening process, which seriously affects the hot-rolled strip repair rate and comprehensive yield rate. Replacing the finishing rolls in advance can improve the ruffled plate shape defect of hot-rolled strip, but this operation not only affects the continuity and stability of hot rolling, but also greatly increases the workload of roller grinding in the grinding workshop. Therefore, this application proposes a method for improving the ruffled plate shape defect of hot-rolled thin strip. Summary of the invention

[0006] The object of the present invention is to provide a method for improving the ruffled plate shape defect of a hot-rolled thin strip to solve the problems raised by the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for improving the ruffled shape defect of a hot-rolled thin strip, comprising the following steps:

[0008] Step 1: Track the production process of hot-rolled thin strip and determine the location where the ruffled plate shape defect occurs;

[0009] Step 2: Analyze the wear status of the finishing rolling work rolls and adjust the work roll shifting interval according to the wear status;

[0010] Step 3: Analyze the deviation of the center line of the strip finishing exit and optimize the deviation direction of the strip;

[0011] Step 4: Track the optimized ruffled edge of hot-rolled thin strip, and further optimize the working roll shifting range and strip deviation.

[0012] Preferably, the method for determining the location of the defect of the ruffled plate mentioned in step 1 comprises: recording, viewing, analyzing and comparing the cold outlet plate shape diagrams of multiple groups of hot-rolled thin strip layers.

[0013] Preferably, the location where the ruffled plate shape defect mentioned in step one occurs is the operating side of the strip.

[0014] Preferably, the method for analyzing the wear state of the finishing rolling working roll mentioned in the step 2 is: the roll shape of the finishing rolling working roll on the F7 frame is a CVC roll shape, the upper working roll and the lower working roll in the F7 frame are removed from the F7 frame respectively, and then the roll shape curves of the upper working roll and the lower working roll are drawn, and the roll shape curves of the upper working roll of the F7 frame after being removed from the machine and the roll shape curves of the lower working roll of the F7 frame after being removed from the machine are checked.

[0015] Preferably, the operating steps for adjusting the working roll shifting interval mentioned in step 2 are: in the early and middle stages of finishing rolling, the negative shifting value of the working roll at the F7 stand is limited to within -100 mm, so as to limit the degree of aggravation of the ruffles caused by the positive shifting of the working rolls.

[0016] Preferably, the method for analyzing the deviation of the center line of the strip finishing exit mentioned in step three is: recording the data of the center line position of the finishing exit and drawing a deviation curve of the center line of the finishing exit.

[0017] Preferably, the method for optimizing the strip deviation direction mentioned in step three is: reducing the roll gap on the operating side of the working rolls of the F5 frame and the F6 frame, limiting the area on the operating side of the strip, and placing the operating side of the strip on the inner side of the working roll wear step in the F7 frame.

[0018] Preferably, the method for tracking the optimized ruffle condition of the hot-rolled thin-gauge strip mentioned in step 4 is: recording the number of ruffle plate shape defect repairs before and after the improvement and calculating the corresponding ratio, and comparing the ratios.

[0019] Preferably, the method for further optimizing the working roll shifting interval and strip deviation mentioned in step 4 is: limiting the roll shifting interval, adjusting the frame leveling value, restricting the strip head, and preventing the strip head from entering the F7 frame and then deviating from the operating side.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention optimizes the working roll shifting interval, adjusts the deviation direction of the strip head, and avoids the strip edge exceeding the roll wear step and causing the strip ruffled plate shape defect caused by the strip deviation during the strip threading process. It is beneficial to improve the continuity and stability of hot rolling, extend the planned total number of blocks, reduce the rework rate of the ruffled plate shape defect and the flat cutting loss, and improve the comprehensive yield rate of hot-rolled thin strips. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a cloud diagram of the plate shape defects at the cold outlet of the hot-rolled thin strip layer in the present invention.

[0023] Figure 2 This is the ruffled morphology of the hot-rolled thin strip under the surface inspection camera in the present invention.

[0024] Figure 3 The figure shows the wear condition of the working rolls on the finishing rolling F7 stand in the present invention.

[0025] Figure 4 The figure shows the wear condition of the lower working roll of the finishing rolling F7 stand in the present invention.

[0026] Figure 5 It is the center line deviation curve of the finishing rolling outlet in the present invention.

[0027] Figure 6 The invention optimizes the repair rate of front and rear ruffle plate defects.

[0028] Figure 7 The present invention is a flow chart of the method for improving the ruffled edge shape defect of hot-rolled thin strip. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Reference Figure 7 A method for improving the ruffled shape defect of a hot-rolled thin strip comprises the following steps:

[0031] Step 1: Track the production process of hot-rolled thin strips and determine the location where the ruffled plate shape defect occurs. The ruffled edge of the strip is a plate shape defect on the edge of the strip, which may appear on either side of the strip. Determine whether the ruffled edge defect of the hot-rolled thin strip occurs on the operating side or the transmission side of the strip during production, and analyze and compare the frequency of ruffled edge defects on the operating side and the transmission side of the strip. The method for determining the location of the ruffled plate defect mentioned in step 1: record, view, analyze, and compare multiple groups of cold outlet plate shape diagrams of the hot-rolled thin strip layer. After analyzing multiple groups of data, confirm that the location of the ruffled plate shape defect is the operating side of the strip.

[0032] like Figure 1 The figure shows the cold outlet shape of several consecutive hot-rolled thin strip layers at the end of the plan. Figure 1 It can be seen that it is difficult to control the shape of hot-rolled thin strips. After cooling, all five coils have quarter waves on the transmission side. Coil 3 and Coil 4 have ruffles, and the ruffles on Coil 3 are more serious. The ruffle shape defects of both coils are located on the operating side of the strip. From the production situation in the past two months, it can be seen that due to the different rolling conditions of each coil, the ruffle shape defects of the strip generally do not occur continuously, but once the ruffle shape defects occur, they are located on the operating side. The morphology of the ruffle defect captured by the surface inspection camera is as follows Figure 2 As shown, the light and dark alternating area is the ruffled wavy area.

[0033] Step 2: Analyze the wear status of the finishing rolls and adjust the work roll shifting interval according to the wear status. In the production process of hot-rolled thin strips, the finishing rolling load is large, the work rolls are severely worn, and the wear of the work rolls further affects the shape control of the hot-rolled thin strips. Therefore, most ruffle defects appear in the middle and late stages of the finishing plan. Therefore, for the hot-rolled thin strip plan with ruffle shape defects, it is necessary to reverse the wear curve of the work rolls after they are off the machine, determine the wear status of the work rolls, and optimize the work roll shifting interval according to the wear status of the work rolls.

[0034] The method for analyzing the wear state of the finishing rolling work roll is as follows: the roll shape of the finishing rolling work roll on the F7 frame is a CVC roll shape, the upper working roll and the lower working roll in the F7 frame are removed from the F7 frame respectively, and then the roll shape curves of the upper working roll and the lower working roll are drawn, and the roll shape curves of the upper working roll of the F7 frame after being removed from the machine and the roll shape curves of the lower working roll of the F7 frame after being removed from the machine are checked, so as to confirm the wear state of the upper working roll and the lower working roll.

[0035] The operating steps for adjusting the working roll shifting range are as follows: in the early and middle stages of finishing rolling, limit the negative shifting value of the working roll of the F7 frame to within -100mm, limit the degree of aggravation of the ruffles due to positive shifting of the working rolls, and leave enough space for the negative shifting of the working rolls in the later stage of finishing rolling. During the entire production process, the working rolls show a gradual negative shifting pattern to avoid aggravation of the ruffle defects due to positive shifting.

[0036] Check the wear curve of the working roll after the rolling plan with ruffles is removed from the mill. Figure 3 This is the roll shape curve of the working roll on the F7 frame after it leaves the machine. Figure 4 The roll shape curve of the lower working roll of the F7 stand after it is removed from the machine. The roll shape of the finishing work roll on the F7 stand is CVC roll shape. The upper rolls of the two wide and thin strip plans have severe local wear after side rolling, such as Figure 3 There is also local wear on the transmission side of the lower working roll, but the local wear is less than that on the operating side of the upper working roll. Figure 4 When hot rolling produces wide and thin strip steel, there is severe local wear on the operating side of the upper roll. When the working roll is moving forward, the wear step moves toward the strip steel. When the edge of the strip steel exceeds the wear step, it is more likely to cause a ruffled plate shape defect.

[0037] Step 3: Analyze the centerline deviation of the strip at the finishing exit and optimize the strip deviation direction. The ruffled plate shape defect appears in the middle and late stages of a single hot-rolled thin strip rolling plan. For the rolling plan with the ruffled plate shape defect, analyze the centerline deviation of the steel coils with and without ruffled defects at the finishing exit. In particular, for consecutive coils of strip, the ruffled and non-ruffled steel coils appear crosswise. Analyze the centerline deviation of the strip at the finishing exit of the two types of steel coils, study the influence of the centerline deviation at the finishing exit on the ruffled plate shape defect, and optimize the strip deviation direction.

[0038] The method for analyzing the deviation of the center line of the strip finishing exit is: recording the data of the center line position of the finishing exit, and drawing a deviation curve of the center line of the finishing exit, wherein the positive value of the vertical coordinate in the drawn graph represents the operation side of the deviation of the strip finishing exit, and the negative value represents the transmission side of the deviation of the strip finishing exit.

[0039] Figure 5 The center line deviation of the steel coil with ruffled plate defect at the finishing exit is Figure 1 The five consecutive strips in the figure correspond to the operation side of the strip finishing exit deviation, and the negative value indicates the transmission side of the strip finishing exit deviation. Figure 5It can be seen that the center lines of the finishing outlets of coils 1, 2 and 5 are all biased toward the transmission side by more than 20 mm at the head of the strip, and the center lines of the finishing outlets of coils 3 and 4 are less biased toward the transmission side at the head of the strip. In particular, the center line of the finishing outlet of coil 3 is biased toward the operating side at the head of the strip, and the ruffles on the operating side are the most serious. Therefore, when the ruffled plate shape defect appears on the operating side of the strip, the finishing leveling value must be adjusted to prevent the strip from deviating from the operating side. The method for optimizing the strip deviation direction is: adjusting the leveling value of the F5 frame and the F6 frame, reducing the roll gap on the operating side of the working rolls of the F5 frame and the F6 frame, limiting the deviation of the operating side of the strip, and placing the operating side of the strip on the inner side of the working roll wear step in the F7 frame. Limiting the deviation of the strip before entering the F7 frame prevents the operating side of the strip from exceeding the F7 working roll wear step, resulting in serious ruffle defects on the operating side.

[0040] Step 4: Track the optimized hot-rolled thin strip ruffles and further optimize the work roll shifting interval and strip deviation. During hot-rolled thin strip production, optimize the work roll shifting interval and strip deviation direction of the finishing mill, track the adjusted hot-rolled thin strip ruffle shape defects, and further optimize the roll shifting and strip deviation control according to the adjusted hot-rolled thin strip ruffle defects.

[0041] The method for tracking the optimized ruffle situation of hot-rolled thin-gauge strip steel is as follows: recording and comparing the number of ruffle plate shape defect repairs before and after the improvement and calculating the corresponding ratio, and comparing the ratio.

[0042] The method for further optimizing the working roll shifting interval and strip deviation is as follows: limiting the roll shifting interval, adjusting the frame leveling value, adjusting the deviation of the strip head, and preventing the strip head from entering the front deviation operation side of the F7 frame. The ruffled plate shape defect of a certain grade of wide and thin strip steel in finishing rolling is greatly reduced. Figure 6 As shown, batch repair and leveling cutting loss are avoided, and the continuous shape and comprehensive yield rate of hot-rolled thin strip production are improved.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for improving the ruffled shape defect of hot-rolled thin strip, characterized in that: The steps include: Step 1: Track the production process of hot-rolled thin strip and determine the location where the ruffled plate shape defect occurs; Step 2: Analyze the wear status of the finishing rolling work rolls and adjust the work roll shifting interval according to the wear status; Step 3: Analyze the deviation of the center line of the strip finishing exit and optimize the deviation direction of the strip; Step 4: Track the optimized ruffled edge of hot-rolled thin strip, and further optimize the working roll shifting range and strip deviation.

2. A method for improving the ruffled shape defect of hot-rolled thin strip according to claim 1, characterized in that: The method for determining the location of the defect of the ruffled plate mentioned in the step 1 is: recording, viewing, analyzing and comparing multiple groups of cold outlet plate shape diagrams of the hot-rolled thin strip layer.

3. A method for improving the ruffled shape defect of hot-rolled thin strip according to claim 2, characterized in that: The location where the ruffled plate shape defect mentioned in the step 1 occurs is the operating side of the strip.

4. A method for improving the ruffled shape defect of hot-rolled thin strip according to claim 1, characterized in that: The method for analyzing the wear state of the finishing working rolls mentioned in the step 2 is: the roll shape of the finishing working rolls on the F7 frame is a CVC roll shape, the upper working roll and the lower working roll in the F7 frame are removed from the F7 frame respectively, and then the roll shape curves of the upper working roll and the lower working roll are drawn, and the roll shape curves of the upper working roll of the F7 frame after being removed from the machine and the roll shape curves of the lower working roll of the F7 frame after being removed from the machine are checked.

5. A method for improving the ruffled shape defect of hot-rolled thin strip according to claim 4, characterized in that: The operating steps for adjusting the working roll shifting range mentioned in step 2 are: in the early and middle stages of finishing rolling, the negative shifting value of the working roll at the F7 stand is limited to within -100 mm, so as to limit the degree of aggravation of the ruffles caused by the positive shifting of the working rolls.

6. A method for improving the ruffled shape defect of hot-rolled thin strip according to claim 1, characterized in that: The method for analyzing the deviation of the center line of the strip finishing exit mentioned in the step three is: recording the data of the center line position of the finishing exit and drawing a deviation curve of the center line of the finishing exit.

7. A method for improving the ruffled shape defect of hot-rolled thin strip according to claim 6, characterized in that: The method for optimizing the strip deviation direction mentioned in the step three is: reducing the roll gap on the operating side of the working rolls of the F5 frame and the F6 frame, limiting the area on the operating side of the strip, and placing the operating side of the strip on the inner side of the working roll wear step in the F7 frame.

8. A method for improving the ruffled shape defect of hot-rolled thin strip according to claim 1, characterized in that: The method for tracking the optimized ruffle situation of hot-rolled thin-gauge strip steel mentioned in step 4 is: recording the number of ruffle plate shape defect repairs before and after the improvement and calculating the corresponding ratio, and comparing the ratios.

9. A method for improving the ruffled shape defect of hot-rolled thin strip according to claim 8, characterized in that: The method mentioned in step 4 for further optimizing the working roll shifting interval and strip deviation is: limiting the roll shifting interval, adjusting the frame leveling value, restricting the strip head, and preventing the strip head from entering the F7 frame and deviating from the operating side.

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