KR20040006696A - Method for controlling the grinding of surface of rolling mill in hot milling process - Google Patents

Abstract

PURPOSE: A surface grinding control method of rolling mill in hot milling process is provided to remove drawback causing defects in the optimum conditions according to defect type and evaluation marks by detecting the strip defective state in realtime, calculating defect evaluation marks based on the detected data and changing grinding conditions of roll grinding machine. CONSTITUTION: In a surface grinding control method for controlling an online roll grinding machine to remove defects formed on the surface of rolling mill using surface defect data of rolling material detected using surface drawback probe, the surface grinding control method of the rolling mill in the hot milling process comprises first step of finishing operation after completing coiling if defects are not detected by detecting defects using surface detection data inputted from the surface drawback probe; second step of judging whether continuous rolling is possible or not if surface defects are detected; third step of performing coiling operation if the continuous rolling is possible, and awaiting extraction of a workpiece to be rolled if the continuous rolling is not possible; fourth step of exchanging roll after rolling the standby workpiece if the rolling is impossible, and oscillating the workpiece to be rolled at the present position if the rolling is possible by judging whether rolling is possible or not after performing roll grinding operation after awaiting extraction of the workpiece to be rolled; and fifth step of performing rolling of the standby workpiece again if drawback removal is completed after performing online grinding operation.

Description

Method for controlling the grinding of surface of rolling mill in hot milling process}

The present invention detects the defect state of the steel sheet generated by the rolling roll of the rolling mill in real time using the data input from the surface flaw detector, calculates the defect score based on the detected data, Accordingly, the present invention relates to a method for removing the surface of a rolling roll used in a hot rolling process, by changing grinding conditions of a roll grinding apparatus to optimally remove a defect causing a defect according to a defect type and a grade.

In the hot rolling process, the raw material (slab) supplied from the continuous casting machine (1) used in the steelmaking process is reheated and extracted at a temperature suitable for rolling in the hot-rolling furnace apparatus (2), and then rolled and rolled in the hot-rolling mill (3). After the thickness rolling is carried out and the final thickness rolling is performed to the product having the desired thickness in the finishing hot rolling finishing mill 4, the rolled product (strip) is wound in the form of a coil in the winding machine 5. Surface inspection of the strips is performed before and after winding, respectively, to sort out defective products.

Defects and defects on the surface of the strip generated during the hot rolling process as described above are as follows.

First, the rolled material extracted from the hot-rolling furnace apparatus 2 is generally operated at a high temperature of 1100 to 1200 ° C., with a surface defect called scale, a hot-rolled rough mill 3 and a hot-rolled rolling mill for finishing ( 4) Rolling roll marks are generated by (rolled) rolls whose surfaces are damaged due to foreign substances that enter through them, and descaling of the surface of hot-rolled steel sheet due to clogging of various coolant spray nozzles for spraying coolant to the rolling mill. As a result, various scalar surface defects are generated and defective products are generated accordingly. Due to these defects, the strip coil may be sold as a normal product or a low-order off-order product depending on the consumer's use and the occurrence of surface defects.

As described above, the defects on the surface of the strip have a great adverse effect on the quality of the product because once occurring, it occurs continuously throughout the entire process. In order to prevent the occurrence of such product defects, conventional inspection by the surface flaw detector and the neck side has been performed. When product defects are found, inspection is carried out to perform online roll grinding to remove foreign substances from the roll surface or to replace work rolls.

The surface flaw detector 7 is installed between the finishing mill 4 and the winding machine 5, and photographs the surface image of the wound product and provides the surface flaw detector server 8 in real time. The server 8 classifies the defect from the provided surface image and provides it to the local flaw detectors local fish 10 and 11 so that an operator can identify it. Local fish 10 and 11 are separated for finishing rolling and intermediate inspection, respectively. On-line roll grinding operation method is previously filed by the present applicant according to the surface defect detected using the surface flaw detector 7 as described above.

In the roll grinding operation method, if the surface defect is not detected by using the flaw detection result detected when passing through the surface flaw detector 7, rolling is continuously performed. If surface defects are detected, grinding operations using the on-line roll grinding device 13 in the finishing mill 4 are performed for each defect type and grade. Grinding operation is performed in accordance with the control signal transmitted from the upper control unit via the PLC (15).

Examples of grinding operations include defect names with scale and a rating of less than 4 points, continuous rolling, an online roll grinding operation for 4 points, and an online roll grinding operation for 5 points. After rolling, remove the flaw and perform continuous rolling. If the defect name is a roll mark and the rating is less than 3 points, continuous rolling is carried out. If the rating is 3 points, online roll grinding is performed for 1 minute. If the score is 4 points, online roll grinding is performed for 3 minutes, and the rating is 5 If it is a dot, roll rolling is carried out and continuous rolling is performed. The above calculation of the rating is performed by the surface flaw detector server 8.

However, in the conventional roll grinding operation, the online roll grinding operation is performed only according to the kind and rating of the defect, and the management criteria are different depending on the material to be rolled, and the surface roughness and The amount of grinding is different, there was a problem of working without considering these conditions at all. For example, depending on the quality of the material, the material is divided into strict and non-strict materials, which is about 35-40% of the coils where P / O (Pickling Oil) and B / P materials are produced and produced. Non-rigid materials are produced from hot rolled shell and cold rolled materials.

Therefore, if the working conditions are not taken into consideration, not only the removal of the cause of the actual defect by the excessive grinding operation is normally performed, but also the grinding amount of the work roll increases when the grinding operation is set excessively, and the online roll grinding operation There is a problem that the waiting time is greatly increased during the progress of the rolling of the atmospheric material in the supercooled state.

The present invention is to solve the above problems, the object is to detect the defect state of the steel sheet generated by the rolling roll of the rolling mill in real time using the data input from the surface flaw detector, based on the detected data The surface of the rolling roll used in the hot rolling process to calculate the grade, and to remove the defects causing the defects according to the defect type and the grade by changing the grinding conditions of the roll grinding machine according to the strict or non-strict materials. It is to provide a soft delete method.

Another object of the present invention is to provide a method for removing the surface of the rolled roll used in the hot rolling process that can improve the product surface quality and error rate by quickly removing the defect of the roll.

1 is a schematic working state diagram of a general hot rolled steel sheet manufacturing process,

2 is a flow chart showing the method of the present invention applied to a hot rolling production process;

3 is a flow chart showing a process of the online grinding operation of FIG.

Figure 4 is an embodiment of a hot-rolled product surface defect rating reference table according to the present invention,

5 is an example of a data leveling program source detected from a surface flaw detector;

Figure 6 is an embodiment of the grinding amount setting reference data of the roll grinding apparatus according to the present invention,

7 is an example of a program source of the control logic of the roll grinding apparatus according to the present invention.

※ Explanation of symbols about main part of drawing ※

1: Continuous casting machine 2: Heating apparatus

3; Roughing Mill 4: Finishing Mill

5: winding machine 7: surface flaw detector

8: surface flaw detector server 9: local flaw detector local fish

10: Local flaw detector 11: SCC1

12: SCC2 13: Roll Grinding Device

15: PLC

Surface rolling erase method of the rolling roll used in the hot rolling process of the present invention for achieving the above object, by using the surface detection data input from the surface flaw detector to detect a defect, if the defect is not detected, the work after winding completion is finished The first step to do; A second step of determining whether continuous rolling is possible when surface defects are detected; A third step of performing a winding operation if continuous rolling is possible and waiting for extraction of the rolled material if not possible; A fourth step of replacing the roll after the rolling of the atmospheric material and oscillating the rolled material at the current location if the rolling is possible after determining whether rolling is possible after the roll grinding operation after the extraction of the rolled material; And a fifth step of performing an online grinding operation and performing rolling of the atmospheric material when the flaw removal is completed.

Hereinafter, with reference to the accompanying drawings will be described in detail the surface lead erase method of the rolling roll used in the hot rolling process of the present invention.

The control method of the present invention is conventionally used in a hot rolling process using a surface flaw detector (7), an on-line roll grinding device (13), and a control device (8, 9, 10, 11, 12) used for control throughout the device. It is a control method which can remarkably improve the defect occurrence factor by the rolling roll of the finishing mill 4.

Referring to Figure 1 briefly described the operating state of the control device (8, 9, 10, 11, 12) as follows. The server 8 receives and processes the surface flaw detection data by the surface flaw detector 7, and the local fish 9 and 10 display the information according to the surface flaw detection result so that an operator can recognize it. SCC1 (Supervisoric Control Computer 1) controls the operation of the furnace apparatus 2, SCC2 (Supervisoric Control Computer 2) controls the roughing mill (3) and the finishing mill (5). The fishes are all connected to the network via a local intranet. The control by the video information of the surface flaw detector server 8 is configured to automatically control the SCC1 11 and the SCC2 12 automatically.

2 is a flowchart illustrating a control method of the present invention.

The slab extracted from the furnace apparatus 2 is subjected to the width and thickness rolling in the roughing mill 3, and the final thickness rolling in the finishing mill 4 to be supplied to the winding machine 5. Before being supplied to the winder 5, the surface flaw detector 7 passes through the surface flaw detector 7, and information about the surface flaw is input to the fish server 8. When winding is completed in the winder 5, the rolling control logic for one coil is finished.

During the process described above, the data (position and state information of the material) of the process carried out in the furnace apparatus 2, the rough rolling mill 3, and the finishing mill 4, which are unit processes, are continuously SCC1 (11) and SCC2. After being collected via 12, it is input to the server 8. The surface flaw analysis is performed by using the collected information and the surface flaw data detected while passing through the surface flaw detector 7. As a result of the analysis at the server 8, when no defect is detected, the winding by the winder 5 is terminated, and the second rolling is continuously performed.

Defect determination on the surface data of the material input from the surface flaw detector 7 is performed by a rating (1-5 points), and an example of the reference table of ratings is shown in FIG. Referring to the drawings, they are classified into scalability defects and roll mark defects, and each is subdivided into a rating of 1-5. For example, in scalability defects, the rating 1 is set to "it is very insignificant to no touch,""rubbed with rubber sandpaper, and there is no trace", "5% or less per sheet area", and the like. In addition, the scalability 2 of the scalability defect is set to "slight state, no touch, only traces", "rubbed with rubber sandpaper, and traces remain", "10% or less per sheet area", and the like. In the roll mark defect, the rating 3 is set to " feel and scratch area is 10 mm ² or less "," unevenness is 5% or less of sheet thickness " The above-described defect scores are converted into numerical data corresponding to the respective scores of the respective reference tables, and then are input to the server 8 and compared with the data input from the surface flaw detector 7 before the ratings are given.

FIG. 5 is an example of a program source showing an algorithm for converting the data value output from the actual surface flaw detector 7 based on the reference table of FIG. 4 described above. Definitions of the width, height and area of the defect are defined in the introduction to FIG. 5, respectively. For example, the pixel which is the smallest unit number represents 1 pixel = 0.5 mm (width) * 1.1 mm (height).

An example of the data conversion value (converting a defect into a rating) of FIG. 5 will be described below. In item ①, "if (detect.class == 3) {// rollmark id" indicates "roll mark" if the defect name is "3". Also, in item ②, "} else if ((feature.A <= 43) && (feature.w_box> 17) && (feature.w_sbox <= 24)) {defect.grade = 1; (rating1)" If the number of recognized pixels is 43 or less, the width defect is 17 or more, or the width defect is 24 or less, the rating is 1 point. In FIG. 5, the remaining parts of item ② may also be interpreted as described above, and show a case where all of the ratings are 1. See also item ③, "} else if ((feature.A> 43) && (feature.A <= 59) && (feature.h_sbox> 8)) {defect.grade = 2;" Indicates that the number of pixels in which defects are recognized is 43 or more and 59 or less, or when the height direction defects are 8 or more, the score is 2 points.

Also, referring to ⑦, "} else if (defect.class == 15) {// banchu_scale id" means that the defect name is banchu scale. Also, referring to item ⑧, "if ((feature.A <= 66)) {defect.grade = 1;" means that the score is 1 point if the number of pixels where the defect is recognized is 66 or less.

Also, if the defect name is "8", the "rolled_in_scale" defect is indicated, if the defect name is "9", the "sand scale" defect is indicated, and if the defect name is "4", the "SCAB" defect is indicated. These defect names are shown in the program source of FIG. 5, and ruminants, sand, rolled, and caps are all classified as scale.

As described above, the defect state of the pixel is detected to calculate a rating. Through the above process, the rating for the surface defect is calculated.

According to the result of the evaluation of the rating, if a defect (marking point) is detected, it is determined whether the continuous rolling is possible again, and if the defect is capable of continuous rolling, the second rolling is continuously performed. If continuous rolling is not possible, the extraction of the rolled material is switched to the standby state. After switching to the standby state, it is judged whether or not grinding is possible after Online Roll Grinding (ORG). Judgment on the possibility of grinding is classified according to the grade of the defect grade and the stiff or non-rigid material type.

After the on-line roll grinding operation to determine the possibility of grinding, oscillation is performed at the current position with respect to the atmospheric material extracted from the furnace apparatus (2). Material oscillation means moving the material in place without advancing the atmosphere.

In the on-line roll grinding operation process, the slab, which is an atmospheric material, is extracted from the SCC1 (11), which is the control computer of the furnace apparatus 2, and then waited, and the control of the SCC2 (12), which is the control computer of the furnace apparatus 2, is controlled. After finishing, the rough rolling material and the finishing rolling air material are oscillated at the current position by the SCC2 12 which is the control computer of the roughing mill 3 and the finishing mill 4.

While the oscillation of the atmospheric material at the current position is in progress, the online grinding operation is performed. The online grinding operation is an operation of grinding and removing defects formed on the surface of a roll by using the roll grinding device 13. When the online grinding operation is completed and the flaw removal is completed, rolling is performed on the atmospheric material, and the process from the furnace apparatus 2 is performed.

3 is a flowchart showing an operational state for an online grinding operation after oscillation. The extraction atmosphere of the rolled material and the oscillation of the atmospheric material are the same processes as described above. After oscillation operation, it is judged whether it is a roll mark defect or not. If it is determined that the roll mark is defective, it is again determined whether it is strict or non-strict (general). If the material is rigid, the oscillation of the online roll grinding device 13 is performed once with reference to the rating of the data conversion value output from the surface flaw detector 7 (see FIG. 5). If it is a point, oscillation is performed twice, and if a score is 3 points, oscillation is performed three times. However, if the rating is 4 or 5, the oscillation is not allowed because it is a replacement requirement of the rolling roll.

In the case of non-strict materials (general materials), the oscillation is performed once if the rating is 3 points, and the oscillation twice if the rating is 4 points. However, if the score is 1, 2, roll grinding is not performed. If the score is 5, the roll is replaced. In the case where oscillation is performed once with a score of one point, the grinding amounts for the rolling mills F5, F6, and F7 become 3.8 µm, 3.0 µm and 2.7 µm, and the method of determining the grinding amount will be described later. . It is apparent that the number of oscillations or grinding stops according to the above ratings may be changed depending on the hot rolling process to which the method of the present invention is applied.

If the defect name is a scale defect, it is determined whether it is a strict material or a non-strict material like the roll mark defect. If the material is rigid, the oscillation of the online roll grinding device 13 is performed once with reference to the rating of the data conversion value output from the surface flaw detector 7 (see FIG. 5). If it is a point, oscillation is performed twice, and if it is 4 points, oscillation is performed three times. However, if the rating is 5 points, it becomes a replacement requirement of the rolling roll, so oscillation is not made.

In the case of non-strict materials (general materials), one oscillation is performed if the rating is 4 points, and two oscillations if the rating is 5 points. However, if the grade is 1,2,3, roll grinding is not performed. In the case of rigid materials, when oscillation is performed once with a score of one point, the grinding amounts for the rolling mills F5, F6, and F7 are 3.6 µm, 2.8 µm, and 2.5 µm.

In the above working process, the grinding amount of the work roll is determined according to the oscillation number of the on-line roll grinding device 13. In other words, it is determined according to the size of the cause causing the defect, the classification of the material to be rolled (rigid and non-rigid) and the working conditions of the online grinding device. Calculation of the grinding amount of the online grinding device as described above is performed by the following equation (1).

From here

Dr: Grinding amount at 1 oscillation (㎛),

vv0: Grinding capacity (cc / min)-Grinding volume per minute

Pai: circumference rate (3.14)

Dw: Roll diameter

Vosc: Oscillation speed (mm / sec).

By applying Equation 1 above, one working example of the data calculated according to the conditions of the on-line roll grinding apparatus is shown in FIG. 6. As shown, the grinding amount values are divided into low and medium speed according to the speed of the stand and oscillation to be rolled, and divided into high grinding, heavy grinding and low grinding according to the volume of grinding in one minute. . Here, the high grinding capacity is 17cc / min for grinding in 1 minute, the medium grinding capacity is 16cc / min, and the low grinding capacity is 9.5cc / min.

In addition, Vosc shows the distance that the on-line roll grinding device is moved per second, which is different for each stand, and divided into low speed, medium speed, and high speed, and is applied as shown in Table 1 below. Shown in Table 1 below represents the oscillation speed.

division F5 stand F6 stand F7 stand Within 35 45 50 Medium 60 80 90 high speed 120

Oscillation Speed (mm / sec)

The number of oscillations is determined according to the grade values classified by applying the grinding amount and the data conversion value calculated using the above equation.

As described above, an algorithm for selecting the grinding ability according to the strict or non-strict material and the defect grade is described as described above. For example, if the coil being rolled is a rigid material, the defect is a roll mark, and the defect grade is a rating of 1, the grinding performance is set to high grinding performance (17 cc / min) and Vosc is set to low speed (50 mm / sec). have. In addition, if the defect is a scale and the defect grade is a grade 1, it is ignored, and if the bond grade is a grade 2, vvo is a heavy grinding capacity (16 cc / min), and Vosc is a low speed (50 mm / sec).

According to the present invention, the defect state of the steel sheet generated by the rolling roll of the rolling mill is detected in real time using the data input from the surface flaw detector, and the defect score is calculated based on the detected data, By changing the grinding conditions of the roll grinding machine according to the stiffness of material, there is an effect that the defects causing the defects can be optimally removed according to the defect type and the grade.

Claims (3)

In the surface grinding machine method of controlling an on-line roll grinding device to remove defects formed on the surface of a rolling roll by using surface defect data of a rolling material detected using a surface flaw detector, A first step of detecting a defect using surface detection data input from the surface flaw detector and ending the work after the winding is completed if the defect is not detected; A second step of determining whether continuous rolling is possible when surface defects are detected; A third step of performing a winding operation if continuous rolling is possible and waiting for extraction of the rolled material if not possible; A fourth step of replacing the roll after the rolling of the atmospheric material and oscillating the rolled material at the current location if the rolling is possible after determining whether rolling is possible after the roll grinding operation after the extraction of the rolled material; And a fifth step of performing on-line grinding operation and performing flaw removal when the flaw removal is completed, wherein the rolling roll is used in the hot rolling process. The method of claim 1, Determining whether the online roll grinding operation in the fifth step is a roll mark defect or a scalability defect, a step of determining whether a strict material or a non-strict material according to each defect type, and Comprising the step of calculating the oscillation and the surface grinding amount (Dr) of the roll grinding apparatus with reference to the rating for the stiff material. The method of claim 2, Surface grinding amount Dr according to the oscillation, Dr = (vv0 x 10000000) / (60 x Pai x Dw x Vosc), where Dr: Grinding amount at 1 oscillation (㎛), vv0: Grinding capacity (cc / min)-Grinding volume per minute Pai: circumference rate (3.14) Dw: Roll diameter Vosc: calculated by oscillation speed (mm / sec), The grinding ability is divided into high grinding capacity, medium grinding capacity, low grinding capacity, high grinding capacity is 17cc / min, medium grinding capacity is 16cc / min, and low grinding ability is applied to 9.5cc / min Surface rolling erase method of rolling rolls used in hot rolling process.