JP2011237276A - Method for retreating flaw detection head and flaw detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for retreating a flaw detection head and a flaw detection apparatus with which a surface flaw can be detected even if shape defect exits in a steel plate which is an object to be detected without breakage of the flaw detection head through contact of the shape defect portions with the surface flaw detection apparatus.SOLUTION: A flaw detection apparatus includes a flaw detection head arranged at a portion where a steel plate is wound around a roll and opposite to the steel plate, a large protrusion sensor for detecting protrusions of a size of 5 mm or more, and a small protrusion sensor for detecting protrusions of a size of less than 5 mm to 1 mm or more, a calculation processing apparatus for performing output of retreating signals based on signals from the large protrusion sensor and the small protrusion sensor and a control device for sending retreat instruction to each actuator which moves the entire flaw detection head or the sensor portions of the flaw detection head based on the retreat signals.

Description

  The present invention relates to a surface defect detection method and apparatus for detecting minute surface irregularities of a magnetic metal, and in particular, a method for retracting a defect inspection head and a defect when a very large convex defect or shape defect occurs on the metal surface. The present invention relates to a flaw detection apparatus.

  As a technique for detecting a minute uneven surface defect of a magnetic metal, there is a technique disclosed in Patent Document 1 so far.

  This technology installs a leakage flux testing device after a temper rolling mill in a continuous annealing line with a small lift-off (distance between the steel plate and the device, for example, 1 mm), and magnetic flux from the magnetizer in the leakage flux testing device (head) to the steel plate. The magnetic flux change disturbed by the minute uneven surface defects present on the steel sheet is detected.

JP 2007-256274 A

  However, in the technique disclosed in Patent Document 1 described above, a leakage magnetic flux flaw detector is installed with a small lift-off for a steel plate that moves at high speed, so that the steel plate to be flawed is squeezed or referred to as “hege”. When a very large convex defect occurs, or when the shape of the steel plate deteriorates and shape defects such as ear waves and middle elongation occur, the convex portion generated on these steel plates comes into contact with the leakage magnetic flux flaw detector. There was a problem of breaking.

  The present invention has been made in view of such circumstances, and even if a steel plate to be flawed has a shape defect, the defective shape portion and the surface defect flaw detector come into contact with each other to damage the flaw detection head. It is an object of the present invention to provide a defect inspection head retracting method and a defect inspection apparatus capable of detecting surface defects without any defects.

  The first invention of the present invention is a method for retracting a defect inspection head that avoids contact between the convex portion on the surface of the steel sheet and the defect inspection head. The defect inspection head is opposed to the steel sheet at a place where the steel sheet is wound around a roll. And installing a convex detection sensor for detecting a convex portion on the surface of the steel sheet upstream of the installation location of the defect inspection head and at a location where the steel sheet is wound around the roll, and the convex detection sensor is a predetermined value. The defect flaw detection head retracting method is characterized in that the defect flaw detection head is retracted when the above convex portions are detected.

  Further, the second invention of the present invention is the method of retracting a defect inspection head according to the first invention, wherein the defect inspection head is a leakage magnetic flux inspection head, and the protrusion detection sensor is a protrusion of 5 mm or more. A defect flaw detection head retracting method comprising: a large convex sensor for detecting a protrusion and a small convex sensor for detecting a convex part of less than 5 mm and 1 mm or more.

  According to a third aspect of the present invention, in the method for retracting a defect inspection head according to the second aspect, the large convex portion sensor is installed on the exit side of the continuous annealing line to detect a convex portion of 5 mm or more. In the case where the entire defect inspection head is retracted, the small convex sensor is installed on the exit side of the temper rolling mill downstream of the annealing furnace, and a convex part of less than 5 mm and 1 mm or more is detected In this method, the defect inspection head is retracted only by retracting only the sensor portion of the defect inspection head.

  Further, a fourth invention of the present invention is the linear array camera for photographing the slit reflected light from the steel plate, in the method for retracting the defect inspection head of the second or third invention, A method for retracting a defect inspection head characterized in that it is determined that a convex portion is present when a slit light beam deviates from the field of view of the linear array camera.

  The fifth invention of the present invention is a defect inspection device having a retraction mechanism that avoids contact between the convex portion of the steel sheet surface and the defect inspection head, and is opposed to the steel sheet at a place where the steel sheet is wound around the roll. A defect inspection head to be installed, a large convex sensor for detecting a convex part of 5 mm or more, a small convex sensor for detecting a convex part of less than 5 mm and 1 mm, and the large convex sensor and the small convex sensor. An arithmetic processing unit that outputs a retraction signal based on the signal and a control unit that sends a retraction command to each actuator that moves the entire defect inspection head or the sensor unit in the defect inspection head based on the retraction signal. This is a defect inspection device.

  Furthermore, a sixth invention of the present invention is the defect inspection apparatus according to the fifth invention, wherein the defect inspection head is installed on the exit side of the temper rolling mill downstream of the annealing furnace in the continuous annealing line. When the large convexity sensor is installed on the exit side of the annealing furnace and a convexity of 5 mm or more is detected, the entire defect inspection head is retracted and the small convexity sensor is moved out of the temper rolling mill. The defect inspection device is characterized in that, when a convex portion of less than 5 mm and 1 mm or more is detected on the side and upstream from the installation location of the defect inspection head, only the sensor portion of the defect inspection head is retracted. is there.

  According to the present invention, since the convex portion on the surface of the steel sheet is detected and the defect inspection head is retracted, even if there is a defect in the shape of the steel sheet to be inspected, it is in contact with the surface defect inspection device to detect the defect. Surface defects can be detected without damaging the head.

It is a figure explaining the mode of convex part detection using a linear array camera. It is a figure which shows typically the structure of a magnetic flux leakage test head. It is a figure which shows the apparatus structure which concerns on a present Example. It is a figure which shows the flow of the evacuation signal to a magnetic flux leakage test head. It is a figure which shows an example of the process sequence from a convex-part measurement to a leakage magnetic flux test head retraction | saving.

First, the inventors examined in detail the state of occurrence of the aforementioned shape defects, and found that the shape defects could be classified into the following three types.
A: Ear wave, medium stretch
B: Drawing generated in annealing furnace and temper rolling mill
C: Hege originally attached to the cold-rolled steel sheet put in the continuous annealing line.Furthermore, with regard to the ear wave and the middle elongation of A, the shape of the generated ear wave and the middle elongation at the place where the roll is wound around the steel sheet pp (peak to peak) was found to be corrected within 200 μm.

  The unevenness within the corrected p-p of 200 μm is an unevenness of a level that causes no problem in terms of leakage magnetic flux measurement and also from the viewpoint of contact with a leakage magnetic flux inspection head installed at a lift-off of, for example, 1 mm. For this reason, the surface defect is detected by the leakage magnetic flux flaw detector at the place where the roll is wound around the steel plate.

  In addition, with regard to the aforementioned B and C iris / heavy convex portions, the convex portions are detected on the upstream side of the leakage magnetic flux flaw detection head and at the same mechanical location as the flaw detection head is installed. In order to avoid contact when a convex portion is detected by providing a convex portion detection sensor, it has been considered to retract the leakage magnetic flux flaw detection head. Here, the mechanically the same situation means, for example, that the roll is wound around the same diameter, has the same tension, has the same degree of vibration, and the roll has the same eccentricity. It refers to the situation that says.

  As a method for detecting a convex portion, there are a wire type and a laser transmission type as a method for detecting a convex portion of 5 mm or more. However, either method is insufficient in detecting a convex portion of about 1 mm. Although there is a light cutting method using a two-dimensional area camera as a method with high detection capability that satisfies this condition, it takes time to process the two-dimensional data, and the response speed is required to retract the leakage flux testing head. There is a problem of lack.

  Therefore, the present invention adopts a method using a one-dimensional linear array camera that can shorten the processing time. FIG. 1 is a diagram for explaining how convex portions are detected using a linear array camera. In the figure, 1 is a linear array camera, 2 is a laser slit light source, 3 is a monitor, 4 is a steel plate, and 5 is a convex portion. FIG. 1 (a) is a case where the steel plate has no convex portion. ) Schematically shows a state of detection when the steel plate has a convex portion.

The specific convex part detection procedure is as follows.
(1) The slit light from the laser slit light source 2 is irradiated obliquely onto the surface of the steel plate 4 being conveyed.
(2) The slit light is observed with the linear array camera 1 from a direction perpendicular to the surface of the steel plate 4.
(3) When the steel plate 4 has no projection as shown in FIG. 1 (a), the monitor 3 has a linear array camera with uniform brightness over the steel plate width direction, which is the visual field range of the linear array camera 1. One field of view is projected. On the other hand, when the steel plate 4 has the convex portion 5 as shown in FIG. 1B, the slit light is shifted by the convex portion 5 of the steel plate 4, and a part of the visual field range of the linear array camera 1 becomes dark. .
(4) Therefore, when a part of the visual field range of the linear array camera 1 becomes dark, it is determined that the convex portion 5 is present on the steel plate 4.

  The convex part detection sensor for detecting the convex part in the above-mentioned convex part detection procedure is arranged on the upstream side of the leakage magnetic flux flaw detection head, detects the convex part of 1 mm or more, and leaks magnetic flux flaw detection to avoid the collision by the convex part. Retract the head.

  However, further problems remain. In other words, if you try to detect the A, B, and C convex parts mentioned above without omission, there is a convex part of B (that is, a drawing generated in an annealing furnace and a temper rolling mill), so after the temper rolling mill A convex portion detection sensor must be provided.

  On the other hand, as described in Patent Document 1, there is a point that it is better to install the leakage magnetic flux flaw detection head immediately after the temper rolling mill in order to accurately detect the minute uneven surface defects.

  That is, in summary, the convex portion detection sensor is provided immediately after the temper rolling mill, and the leakage magnetic flux flaw detection head is installed downstream of the convex portion detection sensor installation location after the temper rolling mill. This means that the interval between the convex portion detection sensor and the leakage magnetic flux flaw detection head cannot be made too large. Actually, when a suitable place satisfying the above conditions was searched for in the line to which the present invention was applied, it was as much as possible to take about 15 m at the longest.

  Furthermore, the interval of 15m is as short as 1.5 seconds to reach the leakage magnetic flux flaw detection head from the convex detection sensor when a steel plate is flowed at a line speed of 600mpm, for example, and the interval can be shorter than 15m. In this case, the collision avoidance condition becomes more severe because it reaches the leakage magnetic flux testing head from the inspection device in a shorter time.

  There is no problem if the leakage magnetic flux flaw detection head is light and can be retracted sufficiently within this time, but in general, the leakage magnetic flux flaw detection head is provided with a magnetizer for magnetizing the steel sheet. This magnetizer may become very heavy, for example, about 60 kg in weight. In this case, it is technically necessary to detect the convex portion within just 1.5 seconds and retreat the heavy magnetizer. In addition, it becomes very difficult in terms of cost.

Therefore, the present inventors reclassified the convex portions classified as B and C for each occurrence location, and investigated the structure of the leakage magnetic flux flaw detection head to obtain the following knowledge.
-The convex part is classified into a large convex part that is 5 mm or more and a small convex part that is less than 5 mm and 1 mm or more.
・ Large protrusions
B1: In-furnace drawing generated in the annealing furnace,
・ Small convex parts
B2: Drawing generated in temper rolling mill,
C: It is the baldness originally attached to the cold-rolled steel sheet put in the continuous annealing line.

  Furthermore, the magnetic flux leakage test head is a heavy object that can be installed at a distance of about 5 mm from the inspection target (for example, a weight of about 60 kg) and the inspection target for leakage magnetic flux inspection. It was also found that the lift-off can be roughly divided into two parts, that is, a lightweight sensor (for example, several hundred grams) that must be maintained at about 1 mm.

  FIG. 2 is a diagram schematically showing the structure of the leakage flux testing head. In the figure, 4 is a steel plate, 6 is a sensor unit, 7 is an electromagnetic actuator, 8 is a magnetizer unit, 9 is a hydraulic cylinder, 10 is a roller, 11 is a leakage flux test head, and 27 is a roll C.

  The magnetic flux leakage inspection head 11 is largely composed of a magnetizer unit 8, a sensor unit 6, and a roller 10 for following the movement of the steel plate 4 wound around the roll C27. Further, a hydraulic cylinder 9 is provided as an actuator for moving the magnetizer unit 8, and an electromagnetic actuator 7 is provided as an actuator for moving the sensor unit 6. The entire leakage flux testing head 11, that is, the magnetizer unit 8 and the sensor unit 6 are moved together by the movement of the hydraulic cylinder 9, but only the sensor unit 6 is moved independently by the movement of the electromagnetic actuator 7. It realizes small and fast movement.

  By combining the findings described above, the present invention has been obtained. The present invention can be briefly summarized as follows.

  1. Install a large convex sensor that detects a large convex part (5mm or more) on the exit side of the annealing furnace. If a large convex part is detected, the entire leakage flux testing head is retracted. There is usually a sufficient distance between the exit side of the annealing furnace and the leakage magnetic flux testing head installed immediately after the temper rolling mill, and a sufficient retreat time (about 10 seconds or more) can be taken.

  This large convex part sensor only needs to detect convex parts of 5 mm or more, and it does not matter if the resolution is low, so use a wire contact type sensor or a laser transmission type sensor as used conventionally. Can do.

  2. A small convex sensor (using a one-dimensional linear array camera) is provided on the exit side of the temper rolling mill to detect a convex part of 1 mm or more, and small convex parts of 1 mm or more and less than 5 mm are detected here. Then, only the light sensor part in the leakage magnetic flux inspection head is retracted. Here, detection of a small convex part of 1 mm or more and less than 5 mm can be performed by adjusting the incident angle of the laser slit light source 2 and the angle of the linear array camera 1.

  Up to now, the magnetic flux metal flaw detector has been explained as an example of a magnetic metal micro uneven surface defect detection device, but the projection collision avoidance has been described. However, it is applicable to other types of flaw detectors such as eddy current flaw detectors. It doesn't matter.

  An example in which the present invention is applied to a continuous annealing line will be described below. FIG. 3 is a diagram illustrating an apparatus configuration according to the present embodiment. In the figure, 20 is an annealing furnace, 21 is a looper, 22 is a temper rolling mill, 23 is roll A, 24 is convex sensor A, 25 is roll B, 26 is convex sensor B, 27 is roll C, and 28 is roll C. An arithmetic processing unit, 29 is a control unit, 4 is a steel plate, and 11 is a leakage flux testing head.

  It is a continuous annealing line for continuously treating the steel plate 4 in the order of the annealing furnace 20, the looper 21, and the temper rolling mill 22, and a laser transmission type convex portion of 5 mm or more is provided on the exit roll A23 of the annealing furnace 20. A convex sensor B (small convex sensor) 26 that detects a convex part of 1 mm or more of a linear array camera type is applied to a roll B 25 immediately after the temper rolling mill 22 with a convex sensor A (large convex sensor) 24 to be detected. Is installed.

  The leakage magnetic flux testing head 11 which is also a retreat target is installed on a roll C27 located 15 m downstream from the roll B25. The signals from the convex sensor A24 and the convex sensor B26 are arithmetically processed by the arithmetic processing unit 28, and if a convex part is detected, a retract signal is sent to the control unit 29. Alternatively, the retracting operation of the sensor unit 6 is performed.

  FIG. 4 is a diagram illustrating a flow of a retract signal to the leakage magnetic flux testing head. The reference numerals in the figure are the same as those in FIGS. FIG. 5 is a diagram illustrating an example of a processing procedure from the measurement of the convex portion to the retraction of the leakage magnetic flux flaw detection head.

  When a convex part of 5 mm or more is detected by the convex part sensor A24 in FIG. 3, the leakage magnetic flux flaw detection head 11 body is 100 mm by a servo motor (in FIG. 2, 9 is a hydraulic cylinder, but this embodiment uses a servo motor). When the convex portion sensor B26 of FIG. 3 detects a small convex portion of 1 mm or more and less than 5 mm, the electromagnetic actuator 7 retracts only the sensor portion 6 by 5 mm (retracts in about 1 second) (retracted in about 1 second). (See FIG. 4). After the retreat operation is completed, the control device quickly returns the sensor unit and the leakage magnetic flux flaw detection head main body to the original normal position, and continues detection of minute uneven surface defects.

  The processing procedure from the convex measurement to the leakage magnetic flux flaw detection head retraction is shown in FIG. 5, but the series of flow from Step 01 to Step 04 is also performed when the convex sensor A24 detects a convex part of 5 mm or more. The same applies when a small convex part of 1 mm or more and less than 5 mm is detected in B26. However, if a convex part of 5mm or more is detected, the target of the evacuation operation in Step 04 is a servo motor that moves the leakage flux testing head body, or if a small convex part of 1mm or more and less than 5mm is detected in Step 04 The only difference is whether the object of the retraction operation is an electromagnetic actuator that moves only the sensor unit.

  According to the present embodiment described above, contact between the leakage magnetic flux inspection head installed after the temper rolling of the continuous annealing line and the convex portion generated on the steel plate and damage to the inspection head can be prevented, and micro uneven surface defects can be detected. It was.

DESCRIPTION OF SYMBOLS 1 Linear array camera 2 Laser slit light source 3 Monitor 4 Steel plate 5 Convex part 6 Sensor part 7 Electromagnetic actuator 8 Magnetizer part 9 Hydraulic cylinder 10 Roller 11 Leakage magnetic flux inspection head 20 Annealing furnace 21 Looper 22 Temper rolling machine 23 Roll A
24 Convex sensor A
25 Roll B
26 Convex sensor B
27 Roll C
28 arithmetic processing unit 29 control unit

Claims (6)

A method for retracting a defect inspection head that avoids contact between the convex portion of the steel sheet surface and the defect inspection head,
While installing the defect inspection head facing the steel plate at the place where the steel plate is wound around the roll,
Install a convexity detection sensor that detects the convexity on the surface of the steel sheet upstream of the installation location of the defect inspection head and where the steel sheet is wound around the roll,
A method for retracting a defect inspection head, comprising: retracting the defect inspection head when the protrusion detection sensor detects a protrusion greater than a predetermined value. The method of retracting a defect inspection head according to claim 1,
The defect inspection head is a leakage magnetic flux inspection head,
The method of retracting a defect inspection head, wherein the convex detection sensor includes a large convex sensor that detects a convex part of 5 mm or more and a small convex sensor that detects a convex part of less than 5 mm and 1 mm or more. The method for retracting a defect inspection head according to claim 2,
When the large convexity sensor is installed on the exit side of the annealing furnace of the continuous annealing line and a convexity of 5 mm or more is detected, the entire defect inspection head is retracted,
The small convex sensor is installed on the exit side of the temper rolling mill downstream of the annealing furnace, and when a convex part of less than 5 mm and 1 mm or more is detected, only the sensor part of the defect inspection head is retracted. A method of retracting a defect inspection head characterized by the above. In the method for retracting a defect inspection head according to claim 2 or claim 3,
The small convex sensor is
It is a linear array camera that photographs slit reflected light from a steel plate,
A method for retracting a defect inspection head, characterized in that it is determined that a convex portion exists when a slit light beam deviates from the field of view of the linear array camera. A defect flaw detector with a retracting mechanism that avoids contact between the convex portion of the steel sheet surface and the flaw detection head,
A defect inspection head installed opposite to the steel plate at the place where the steel plate is wound around the roll;
A large convex sensor that detects a convex part of 5 mm or more, and a small convex sensor that detects a convex part of less than 5 mm and 1 mm or more,
An arithmetic processing unit that outputs a retract signal based on signals from the large convex sensor and the small convex sensor;
A control device that sends a retraction command to each actuator that moves the entire defect inspection head or a sensor unit in the defect inspection head based on a retraction signal;
A defect inspection apparatus comprising: In the defect inspection apparatus according to claim 5,
The defect inspection head is installed on the exit side of the temper rolling mill downstream of the annealing furnace in the continuous annealing line,
The large convex sensor is installed on the exit side of the annealing furnace, and when a convex part of 5 mm or more is detected, it is configured to retract the entire defect inspection head,
When the small convex sensor is installed on the exit side of the temper rolling mill and upstream from the installation location of the defect inspection head, and a convex portion of less than 5 mm and 1 mm or more is detected, the sensor portion of the defect inspection head A defect flaw detector characterized by being configured to retreat only.