KR100775237B1 - Strip surface defect discrimination method in recoiling line (rcl) - Google Patents

Abstract

A method for determining a defect on a surface of a steel plate in a recoiling line is provided to determine a predetermined defect on the surface of the steel plate by using information on the surface defect acquired in a continuous annealing line. A method for determining a defect on a surface of a steel plate in a recoiling line includes the steps of: storing a detection result of a surface defect including the position of the corresponding surface defect in a database(S14); measuring the recoiled length of the steel plate by using a second encoder(S16); comparing the recoiled length of the steel plate with the position of the surface defect(S20); determining whether the position of the surface defect reaches a predetermined position of an inspection unit(S22); reducing the transfer speed of the steel plate in the recoiling line to a set speed; and measuring the length of the steel plate corresponding to the rotational speed of the transferred roll.

Description

Determination of steel plate surface defects in recoiling lines (RCL) {STRIP SURFACE DEFECT DISCRIMINATION METHOD IN RECOILING LINE (RCL)}

1 is a process diagram of a typical continuous annealing line.

2 is a process diagram of a general recoiling line.

3 is a layout view of the surface defect detector in the continuous annealing line (CAL) according to the present invention.

4 is a structural diagram of a recoiling line RCL to which the present invention is applied.

5 is a flow chart showing a method for determining a steel plate surface defect according to an embodiment of the present invention.

 Explanation of symbols on the main parts of the drawings

10: steel plate 11,12,21: payoff reel

13: welding machine 16,23: rolling mill

19,20,27,28: tension reel 24: inspection table

31: surface defect detector (SDD) 32: control unit

33: first encoder 34: database

41: second encoder 42: comparison unit

43: determination unit 44: drive motor control unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining surface defects of a steel sheet, and more particularly, to a surface of a steel sheet in a recoiling line (RCL) by using surface defect information of the steel sheet obtained from a continuous annealing line (CAL). The present invention relates to a method for determining a specific defect on an image.

In general, the steelmaking process includes a continuous annealing line (CAL) for continuously annealing steel sheets (strips) and a recoiling line for inspecting surface defects of the steel sheets by recoiling the steel sheets wound with coils in the CAL. (RCL).

The surface of the cold rolled steel has a high hardness and poor ductility due to the high residual stress inside the steel sheet generated during cold rolling, so it is difficult to process the shape suitable for the purpose. To solve the problem of the steel sheet, continuous annealing line (CAL) Is a process of continuously heat-treating a cold rolled steel sheet to make a steel sheet of a material having excellent workability by repeatedly heating and cooling.

1 is a process diagram of a typical continuous annealing line.

As shown in FIG. 1, in general, the continuous annealing line CAL includes a preheating stage (PHS), a heating stage (HS1, HS2), a crack stage (SS), a slow cooling stage (SCS), a quenching stage (RCS), and an overaging band. (OAS1-OAS3), cooling zone (FCS) and water cooling zone (WCS). The steel sheet (strip) 10 is unrolled from the pay-off reel 11 and 12 of the entrance equipment, and the leading and trailing steel sheets are welded by the welding machine 13, and the surface of the steel sheet is applied to the electrolytic cleaning equipment 14. After removing the foreign matter by electrolysis, the annealing treatment is carried out while passing through the preheating zone to the water cooling zone 15, followed by the tension reel 19 and 20 through the rolling 16, the side trimming 17 and the cutting 18. ) Is wound up.

2 is a process diagram of a general recoiling line. Referring to FIG. 2, as described above, the steel sheet 10 wound by the coil in the continuous annealing line CAL is unwound in the payoff reel 21, welded in the welder 22, and rolled 23, the inspection table 24. It is wound up by the tension reels 27 and 28 via the side trimming 25 and the oiler 26.

In this way, continuous annealing and surface inspection are performed while passing through CAL and RCL. Recently, RCL is being used as an inspection line exclusively for automobile exterior materials as the surface quality standards of automobile exterior materials are becoming more difficult.

In the past, however, the RCL has been troublesome for the inspector to discriminate the defects over the entire length of the steel sheet. In particular, it is difficult to discriminate fatal defects on the surface of the steel sheet moving at high speed. This caused a case where a steel sheet having a fatal defect was incorporated into a product. In addition, there is a problem in that the productivity is reduced when the entire speed inspection at a low line speed.

The present invention has been proposed to solve the above-mentioned conventional problems, and obtains surface defect information of a steel sheet in a continuous annealing line (CAL) and moves at a high speed in a recoiling line (RCL) using the obtained surface defect information. It is an object of the present invention to provide a method for precisely determining a specific defect on the surface of a steel sheet.

Method for determining the surface defect of the steel sheet according to the present invention for achieving the above object, the surface of the steel sheet by recoiling the steel sheet wound in the coil form in the continuous annealing line (CAL) again in the recoiling line (RCL) In the method of determining a defect,

Before winding the steel sheet in the form of a coil in the continuous annealing line CAL, a surface defect present on the surface of the steel sheet is detected using a predetermined surface defect detector SDD, and the continuous annealing line is formed using a first encoder. Measuring a length of the steel sheet moved in the CAL, and storing the detection result of the surface defect including the position of the surface defect among the lengths of the entire steel sheet in a database; A second step of measuring the recoiled length of the steel sheet by using a second encoder while recoiling the steel sheet wound in the coil shape in a recoiling line RCL; A third step of comparing the recoiled length with the surface defect location of the steel sheet stored in the database; A fourth step of determining whether the surface defect position has reached a specific position in front of the inspection table according to the comparison result; And a fifth step of decelerating the feed rate of the steel sheet of the recoiling line RCL to a set speed for the detailed inspection of the inspector when the defect position has reached the specific position. The first encoder and the second encoder are respectively installed on the feed rolls of the continuous annealing line CAL and the recoiling line RCL to detect the number of revolutions of the feed roll, and to determine the length of the steel sheet corresponding to the number of revolutions. Measure

In one embodiment of the present invention, the specific position is preferably any one of 10 to 50m in front of the inspection table.

In addition, in an embodiment of the present disclosure, the fifth step may further include visually and audibly notifying the inspector through an operation of a notification or a lamp when the defect position arrives at the specific position.

In the following, a detailed description of a preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, in the case where it is determined that detailed descriptions of related well-known functions or configurations may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted so as not to obscure the subject matter of the present invention. will be.

3 is a layout view of the surface defect detector in the continuous annealing line (CAL) according to the present invention.

Referring to Figure 3, in the continuous annealing line (CAL) to which the steel sheet surface defect determination method according to the present invention is applied, the steel sheet 10 is released from the payoff reel (11) 12 of the entrance equipment to welder ( 13) wires and trailing steel sheets are welded and removed by electrolysis to remove foreign substances on the surface of the steel sheet in the electrolytic cleaning equipment (14), and then annealing while passing through the preheating zone to the water cooling zone (15), followed by rolling (16), It is wound around the tension reels 19 and 20 via side trimming 17 and cutting 18.

Before the surface defect detector (SDD) 31 is installed at an appropriate position of the rear end of the continuous annealing line CAL to which the present invention is applied, the steel sheet 10 is wound on the tension reel 19, 20. The defect on the surface of the said steel plate 10 is detected. As the surface defect detector (SDD) 31 applied in the present invention, a known detector may be used. For example, an optical method of irradiating light on the surface of the steel sheet and obtaining an image of the surface of the steel sheet irradiated with the light using a camera (for example, a CCD camera) and then analyzing the image to detect surface defects of the steel sheet. After generating a eddy current on the surface of the steel sheet by using a surface defect detector or by applying a magnetic flux to a coil having a certain distance from the surface of the steel sheet, the magnetic flux change caused by a defect on the surface of the steel sheet is detected by the coil. An eddy current type surface defect detector for detecting can be used. The defect signal detected by the surface defect detector 31 is input to the control unit 32, and the control unit 32 processes the received defect signal to provide various types of information (eg, size, Type, location, surface, etc.) are extracted.

In addition, the continuous annealing line (CAL) according to the present invention is provided with a length measuring first encoder 33 for measuring the length of the steel sheet 10 to be moved. The first encoder 33 is attached to the feed roll 35 to detect the rotation speed of the feed roll 35 and measure the length of the steel plate 10 corresponding to the rotation speed.

The control unit 32 uses the defect signal input from the surface defect detector 31 and the length information input from the length encoder 1 to determine whether the defect exists at the length of the entire steel sheet. Further, the size, type, occurrence surface, etc. of the defect are grasped. The location, size, type, etc. of the defect are stored in the database 34 together with the identifier ID of the steel sheet 10.

4 is a structural diagram of a recoiling line RCL to which the present invention is applied.

Referring to FIG. 4, the recoiling line RCL to which the present invention is applied is a line for recoiling the steel sheet 10 wound in a coil form in the continuous annealing line CAL and inspecting a surface state. The coil-shaped steel sheet is unwound from the payoff reel 21 on the inlet side and welded to the welder 22, and the tension reel 27 passes through the rolling 23, the inspection table 24, the side trimming 25, and the oiler 26. It is wound up at (28). The test table 24 may be installed at an appropriate position in the recoiling line RCL.

In the recoiling line RCL to which the present invention is applied, a second encoder 41 for length measurement for measuring the moving length of the steel sheet 10 is installed on an arbitrary feed roll, and measured by the second encoder 41. Comparator 42 for comparing the moving length (recoiled length) of the steel sheet 10 and the defect occurrence position of the steel sheet 10 stored in the database 34, the result of the comparison is the inspection table 24 Determination unit 43 for determining whether to arrive at a specific position (P) in front of the), the feed rate of the steel sheet 10 when the defect occurrence position arrives at a specific position (P) in front of the inspection table 24 A drive motor controller 44 for controlling a drive motor (not shown) is installed to decelerate.

The second encoder 41 is installed on any one of the plurality of transfer rolls installed in the recoiling line RCL to detect the rotational speed of the transfer roll and the length of the steel plate 10 corresponding to the rotational speed. Measure Preferably, the second encoder measures the length of the steel sheet 10 released from the inlet payoff reel 21 of the recoiling line RCL. Here, the steel sheet 10 is wound in the form of a coil from the leading end in the continuous annealing line (CAL), so that the leading end is inside the coil, the rear end is outside the coil. Subsequently, when the steel sheet 10 is recoiled in the recoiling line RCL, it is released from the rear end of the coil. As a result, the second encoder 41 measures the moving length from the rear end of the steel plate 10. Therefore, when a hole of 4 mm size is detected at the surface defect detector (SDD) 31 of the continuous annealing line (CAL) at a point of 650 m from the tip of the steel sheet # 4 having a total length of 3000 m, the recoiling line ( In RCL), since the length is measured from the rear end, the hole exists at a point 2350m (= 3000-650) from the rear end.

The comparison unit 42 compares the moving length of the steel plate 10 measured by the second encoder 41 with the defect occurrence position of the steel plate 10 stored in the database 34, and the determination unit 43. ) Determines whether a defect occurrence position of the steel sheet 10 arrives at a specific position P in front of the inspection table 24. That is, the comparison unit 42 reads the defect information on the specific steel sheet from the database 34 to determine the location of the defect, and the movement length of the steel sheet 10 measured by the second encoder 41 and the occurrence of the defect. The position is compared in real time, and the determination unit 43 determines whether the defect position has arrived at a specific position P in front of the inspection table 24. In the above example, when a hole of 4 mm size is detected at the surface defect detector (SDD) 31 of the continuous annealing line (CAL) at a point of 650 m from the tip of the steel sheet # 4 having a total length of 3000 m, The information of the steel sheet and the defect information is stored in the database 34, and since the hole exists at 2350m from the rear end, the length of the steel sheet is counted in real time while the steel sheet is released from the rear end in the recoiling line RCL. It is determined whether the 2350m point, which is the position of the hole, reaches a specific position (for example, 30m) in front of the inspection table 24. That is, in the above example, it is determined whether the point 2350m from the rear end of the steel sheet reaches the point 30m forward of the inspection table 24. Here, since the specific position 30m is an embodiment, various embodiments will be possible according to the working conditions of the recoiling line (RCL), more preferably 10 to 50m.

When it is determined by the determination unit 43 that the defect occurrence position reaches a specific position P, the driving motor control unit 44 drives the driving motor (not shown) so that the inspection operator can more closely determine the surface defect of the steel sheet. Start the control of the steel plate 10 to reduce the feed rate. Here, when it is determined that the defect occurrence position has reached a specific position P as described above, the operator may be visually and audibly informed through an alarm and / or a lamp.

5 is a flow chart showing a method for determining a steel plate surface defect according to an embodiment of the present invention.

Referring to Figure 5, the method for determining the surface defects of the steel sheet according to an embodiment of the present invention before the steel sheet 10 is wound in a coil form while continuously annealing the steel sheet 10 in a continuous annealing line (CAL) The surface defect of 10) is detected (S12). At this time, the surface defect of the steel sheet may use a known surface defect detector (SDD). Then, the surface defect information detected as described above is stored in the database 34 (S14).

As described above, in the continuous annealing line CAL, after the surface defect of the steel sheet 10 is detected, the steel sheet 10 is wound in the form of a coil by the tension reels 19 and 20 and then the recoiling line RCL. Is recoiled again. That is, it is recoiled while being released from the payoff reel 21 in the recoiling line RCL. At this time, the second encoder 41 measures the length of the recoiled steel sheet 10 in real time (S16), the comparison unit 42 is the surface defect information of the steel sheet 10 stored in the database 34 Read (S18), and compare the defect position of the steel sheet 10 and the length of the currently recoiled steel sheet (S20), the determination unit 43 is the defect position in front of the inspection table 24 according to the comparison result It is determined whether the specific position of (for example, 30m ahead) has arrived (S22).

As a result of the determination, when the defect position has reached a specific position in front of the inspection table 24, a signal for reducing the conveying speed of the steel sheet is generated so that an inspector inspecting the surface of the steel sheet can perform a more precise surface inspection (S24). Subsequently, it is determined whether a signal indicating that the overhaul is completed is generated (S26), and if the overhaul completion signal is not generated, the deceleration is maintained (S28), and if so, a signal for accelerating the feed rate of the steel sheet to perform normal recoiling. To generate (S30).

Subsequently, the steps S16 to S30 are repeatedly performed until the recoiling operation of the steel sheet 10 is completed, and the processor is terminated when the recoiling operation of the steel sheet 10 is completed.

As described above, using the surface defect information of the steel sheet detected in the continuous annealing line (CAL), the steel sheet can be more precisely inspected surface defects generated at a specific position of the steel sheet in the high-speed recoiling line (RCL) It is possible to control the feed rate of the automatic to ensure the reliability of the detection of surface defects for stringent materials, such as automotive exterior materials.

In the drawings and specification described above, optimal embodiments of the present invention have been disclosed. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not intended to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

According to the present invention, a fatal defect (eg, a hole, a cap, etc.) of the steel sheet moving at high speed in the recoiling line RCL can be more easily identified.

In addition, according to the present invention, in order to precisely inspect the surface defects of the steel sheet in the recoiling line (RCL), it is possible to prevent the decrease in productivity by operating at a low speed only in the position where the surface defects exist, without having to operate at a low speed for the entire steel sheet. have.

Claims (3)

In the method of recoiling a steel sheet wound in the form of a coil in a continuous annealing line (CAL) in the recoiling line (RCL) again to determine the surface defects of the steel sheet, Before winding the steel sheet in the form of a coil in the continuous annealing line CAL, a surface defect present on the surface of the steel sheet is detected using a predetermined surface defect detector SDD, and the continuous annealing line is formed using a first encoder. Measuring a length of the steel sheet moved in the CAL, and storing the detection result of the surface defect including the position of the surface defect among the lengths of the entire steel sheet in a database; A second step of measuring the recoiled length of the steel sheet by using a second encoder while recoiling the steel sheet wound in the coil shape in a recoiling line RCL; A third step of comparing the recoiled length with the surface defect location of the steel sheet stored in the database; A fourth step of determining whether the surface defect position has reached a specific position in front of the inspection table according to the comparison result; And A fifth step of decelerating the feed rate of the steel sheet of the recoiling line RCL to a set speed for a detailed inspection by an inspector when the defect position has arrived at the specific position; Including, The first encoder and the second encoder are respectively installed on the feed rolls of the continuous annealing line CAL and the recoiling line RCL to detect the number of revolutions of the feed roll, and to determine the length of the steel sheet corresponding to the number of revolutions. Method for determining the surface defect of the steel sheet in the recoiling line (RCL), characterized in that for measuring. The method of claim 1, The specific position is a steel sheet surface defect determination method in the recoiling line (RCL), characterized in that any one of 10 to 50m in front of the inspection table. The method of claim 1, wherein the fifth step, And recognizing the inspector visually and audibly through the operation of a notification or a lamp when the defect position has arrived at the specific position.

Images