JP2013152158A - Steel sheet defect inspection device, steel sheet defect inspection method, and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel sheet defect inspection device capable of detecting a defect in a thin steel plate during a thin steel plate.SOLUTION: The steel sheet defect inspection device includes: a plurality of first array-type magnetic sensors each disposed being separated away with a predetermined distance from each other at the surface side of a thin steel plate; and a plurality of second array-type magnetic sensors each disposed being separated away with a predetermined distance from each other at the rear face side of the thin steel plate. Relationship among a detection level of the first array-type magnetic sensors, a detection level of the second array-type magnetic sensors, and the defect of the thin steel plate corresponding to identical defect detection target position are previously stored. Defects on the thin steel plate are identified based on the level of leakage flux detected by the first array-type magnetic sensors and the level of leakage flux detected by the second array-type magnetic sensors corresponding to identical defect detection target position.

Description

  The present invention relates to a steel sheet defect inspection apparatus, a steel sheet defect inspection method, and a control program.

  Conventionally, as a device for detecting the surface layer of a thin steel plate (strip) such as a tin plate, which is a material of a food can, and a minute defect existing therein, magnetic flaw detection is performed by detecting leakage magnetic flux generated by the defective portion and determining the presence or absence of the defect. There is an apparatus (for example, refer to Patent Document 1).

  In Patent Document 1, in a magnetic flaw detector that magnetizes a thin steel plate in the traveling direction and detects a leakage magnetic flux generated by a defect portion in the thin steel plate and a surface layer portion by arranging a plurality of leakage magnetic sensors in the width direction of the thin steel plate. This array-type leakage magnetic sensor discloses a technique for preventing a flaw in a thin steel plate or causing a failure of the magnetic flaw detector even if there is contact between the magnetic flaw detector and the thin steel plate. Has been.

  This array-type magnetic flaw detector has a magnetic element that detects a leakage magnetic flux leaked from a minute defect portion in close proximity to a thin steel plate, and has one end face portion in close contact with the magnetic sensing surface of the magnetic element, and the other Provided at the back of the magnetic sensing surface of the magnetic element, and a magnetic fiber concentrator made of magnetic fibers having soft magnetic properties that are provided with the end face portion facing the surface of the thin steel plate and concentrating the leakage magnetic flux on the magnetic sensing surface. And a soft magnetic plate.

JP 2002-195984 A

  However, in the prior art, the type of defect such as a defect generated on the surface and the surface layer, a defect generated inside, and a hole defect and the degree of the defect cannot be identified.

  The object of the present invention was made to solve the above-mentioned problems, and is a steel sheet defect inspection capable of identifying the types and extents of defects occurring on the surface and surface layers, defects occurring inside, and hole defects. The object is to provide an apparatus, a steel sheet defect inspection method, and a control program.

In order to achieve the above object, the steel sheet defect inspection apparatus according to the embodiment magnetizes a thin steel sheet in the traveling direction, and arranges a plurality of leakage magnetic fluxes generated by defective portions of the thin steel sheet in a direction intersecting the traveling direction. This is a steel sheet defect inspection apparatus that detects an array type magnetic sensor having a plurality of magnetic detection elements and determines the type of defect in the thin steel sheet.
The first array type magnetic sensor is disposed at a predetermined distance apart on the front side of the thin steel plate, and the second array type magnetic sensor is disposed at a predetermined distance apart on the back side of the thin steel plate.
On the other hand, the storage means includes a detection level of leakage flux in the first array type magnetic sensor corresponding to the same defect detection target position, a detection level of leakage flux in the second array type magnetic sensor, and a defect state of the thin steel plate. Are stored in advance.
As a result, the defect state discriminating unit refers to the storage unit and detects the leakage magnetic flux detection level in the first array type magnetic sensor corresponding to the same defect detection target position and the leakage flux in the second array type magnetic sensor. The defect state of the thin steel sheet is determined based on the detection level.

Drawing 1 is an outline lineblock diagram of a steel plate defect inspection device of an embodiment. FIG. 2 is a schematic configuration diagram of the magnetic sensor unit. FIG. 3 is an explanatory diagram of setting and installation states of the front surface magnetic sensor unit and the back surface magnetic sensor unit. FIG. 4 is a schematic configuration explanatory diagram of a signal processing circuit for determining the type and the state of a defect. FIG. 5 is an explanatory diagram of an example of the artificial defect sample and the determination database. FIG. 6 is an explanatory diagram of the modeled defect state. FIG. 7 is a diagram for explaining the correspondence between the output of the array type magnetic sensor and the defect state. FIG. 8 is an operation flowchart of the embodiment. FIG. 9 is an explanatory diagram of the determination processing of the embodiment.

Next, embodiments will be described with reference to the drawings.
Drawing 1 is an outline lineblock diagram of a steel plate defect inspection device of an embodiment.
In FIG. 1, a steel plate defect inspection apparatus 10 includes a surface magnetic sensor unit 12 provided on the front surface side of a thin steel plate 11, a back magnetic sensor unit 13 provided on the back surface side of the thin steel plate 11, a surface magnetic sensor unit 12 and a back surface. Defect determination unit 14 for determining the presence / absence of a defect from the signal detected by the magnetic sensor unit 13 and defect state determination for determining the type of defect and the degree of defect (grade, level) based on the output of the defect determination unit 14 Part 15.

  In the above configuration, the front magnetic sensor unit 12 and the back magnetic sensor unit 13 are respectively the thin steel plate 11 on the surface of the nonmagnetic roller 21 provided at a predetermined distance in the transport direction (traveling direction) of the thin steel plate 11. It is installed in a position (place) where there is no vertical movement (or negligible for measurement).

FIG. 2 is a schematic configuration diagram of the magnetic sensor unit.
Here, since the front magnetic sensor unit 12 and the back magnetic sensor unit 13 have the same configuration, the front magnetic sensor unit 12 will be described as an example in FIG.
The thin steel plate 11 is wound around the non-magnetic roller 21 and is transported in the direction of the arrow. In this state, the surface magnetic sensor unit 12 is wound with a magnetizing coil MC for magnetizing the thin steel plate 11. A C-type magnetization yoke 12c and an array-type magnetic sensor 12a and an array-type magnetic sensor 12b provided at the center of both end surfaces of the C-type magnetization yoke 12c are provided.

  Similarly, the back surface magnetic sensor unit 13 includes a C-type magnetizing yoke 13c wound with a magnetizing coil MC for magnetizing the thin steel plate 11 wound around the large-diameter nonmagnetic roll 11a and traveling in the direction of the arrow. An array type magnetic sensor 13a and an array type magnetic sensor 13b are provided at the center of both end portions of the C type magnetization yoke 13c.

  Both end portions of the C-shaped magnetizing yoke 12C are spaced a predetermined distance in the traveling direction of the thin steel plate 11 and a predetermined distance from the surface of the thin steel plate 11 so that the thin steel plate 11 is magnetized at a predetermined magnetic flux density or more. Placed close together.

  When a predetermined direct current is passed through the magnetizing coil, the thin steel plate 11 is magnetized by the magnetizing yoke 12C, and if there are inclusions or surface flaws inside the steel plate 11, a leakage magnetic flux is generated in this portion. The leakage magnetic flux is detected by the front magnetic sensor unit 12 and the rear magnetic sensor unit 13 made of the magnetic detection element MS, and the presence or absence of a defect is determined.

Next, setting and installation of the front surface magnetic sensor unit 12 and the back surface magnetic sensor unit 13 will be described.
FIG. 3 is an explanatory diagram of setting and installation states of the front surface magnetic sensor unit and the back surface magnetic sensor unit.
FIG. 3A is an external perspective view of the surface magnetic sensor unit 12. Each of the array type magnetic sensor 12a and the array type magnetic sensor 12b includes a plurality of the same magnetic detection elements MS and the conveyance direction of the thin steel plate 11. They are formed side by side in the width direction, which is the direction that intersects (orthogonal in FIG. 3).

Here, as shown in FIG. 3B, the array type magnetic sensor 12a is arranged to be separated from the surface of the thin steel plate 11 by a distance ΔL1.
Similarly, the array type magnetic sensor 12b is arranged at a distance ΔL2 (> ΔL1) from the surface of the thin steel plate 11 as shown in FIG. 3B.

  The back surface magnetic sensor unit 13 includes an array type magnetic sensor 13a and an array type magnetic sensor 13b. As shown in FIG. 2B, the array type magnetic sensor 13a is arranged at a distance ΔL1 away from the back surface of the thin steel plate 11, and the array type magnetic sensor 13b is separated from the back surface of the thin steel plate 11 by a distance ΔL2 (> They are spaced apart by ΔL1).

  Further, the front surface magnetic sensor unit 12 and the back surface magnetic sensor unit 13 have a magnetization yoke 12C and a magnetization yoke 13c installed horizontally. Further, the front magnetic sensor unit 12 and the rear magnetic sensor unit 13 are arranged to be separated from each other by a distance L in the length of the thin steel plate 11.

  The array type magnetic sensor 12a to the array type magnetic sensor 13b are arranged in advance so that the detection positions of the respective magnetic detection elements MS are aligned in the width direction.

  The distance ΔL1 and the distance ΔL2 from the surface of the thin steel plate 11 are obtained by conducting a sample test in advance on the surface and internal defects generated in the thin steel plate 11 detected by the magnetic detection element MS, and in the thickness direction. The detection sensitivity is set to be different for defects occurring at different positions.

  That is, the defect of the thin steel plate 11 is different in the spatial distribution of the leaked magnetic flux MF between the size of the defect and the defect generated on the surface and surface layer of the thin steel plate 11 and the inner central portion of the thin steel plate 11. The magnitude is determined by placing the magnetic detection element MS at different distances from the thin steel plate 11.

  Therefore, the setting of the distances ΔL1 and ΔL2 is statistically carefully determined in advance in a sample test by increasing the number of defect samples of the thin steel plate having the same material and thickness as the thin steel plate 11 to be detected. .

  Next, a signal processing circuit for determining the type of defect and the state of the defect from the detection signals from the front surface magnetic sensor unit 12 and the back surface magnetic sensor unit 13 set as described above will be described.

FIG. 4 is a schematic configuration explanatory diagram of a signal processing circuit for determining the type and the state of a defect.
Each of the array-type magnetic sensors 12a, 12b, 13a, and 13b includes n magnetic detection elements MS, and the output of each of the n magnetic detection elements MS is detected by a defect determination unit 14 in advance. It is compared with (determination level), and the presence or absence of a defect is determined.

By the way, as shown in FIG. 2B, the signal detected by the defect determination unit 14 as having a defect is a distance ΔL in the conveying direction of the thin steel plate 11 between the array type magnetic sensor 12a and the array type magnetic sensor 12b. Therefore, the detection timing of the defect detection is shifted between the array type magnetic sensor 12a and the array type magnetic sensor 12b for the same defect.
Similarly, since the detection positions of the array type magnetic sensor 13a and the array type magnetic sensor 13b are shifted by a distance ΔL in the transport direction of the thin steel plate 11, the array type magnetic sensor 13a and the array type magnetic sensor 13a even if the same defect exists. The output timing of defect detection is shifted with the magnetic sensor 13b.
Furthermore, since the detection positions of the front magnetic sensor unit 12 and the rear magnetic sensor unit 13 are shifted by a distance L, the front magnetic sensor unit 12 and the rear magnetic sensor unit 13 have the same defect. The output timing of defect detection will be shifted.

Therefore, in the present embodiment, the conveyance speed (Δd) is detected by the speed detector 17, and the output timing of the defect signal detected by the defect determination unit 14 is corrected at this conveyance speed.
Specifically, the delay circuit units 16a to 16c delay the output of the defect detection signal for a time corresponding to later-described delay times n2a, n2b, and n3a.
As a result, at the detection signal output timing of the array type magnetic sensor 13b, detection signals of all the array type magnetic sensors 12a, 12b, 13a, 13b corresponding to the same inspection position (or the same defect position) are output. In addition, the output timing of the defect signal is corrected.

The number of corrections for each unit distance is as follows in the delay circuit unit 16a.
Delay time in the array type magnetic sensor 12a: n _12a = (L + ΔL) / Δd,
In the delay circuit unit 16b,
Delay time in the array type magnetic sensor 12b: n _12b = (L + ΔL),
In the delay circuit unit 16c,
Delay time in array type magnetic sensor 13a: n _13a = ΔL / Δd
It becomes.

  As for the outputs of the delay circuit unit 16a (16b, 16c) and the array type magnetic sensor 13b, the input timing to the defect state determination unit 15 is corrected, and outputs corresponding to the same defect detection target position are simultaneously supplied to the defect state determination unit 15. Entered. Then, it is stored in the storage unit 15 a of the defect state determination unit 15. And the defect detection signal (defect detection data) memorize | stored in the memory | storage part 15a memorize | stores in the memory | storage part 15a the detection pattern from the magnetic detection element MS installed in the front surface side and the back surface side of the thin steel plate 11 at different distances beforehand. The defect state determination program (control program; algorithm) thus read is read out, and the calculation unit 15b performs an operation based on the defect state determination algorithm to determine the defect state (type and degree).

Subsequently, the construction of a database for determining surface defects will be described.
In the present embodiment, for surface defects, a database for determining surface defect data is constructed in advance in order to determine the degree of defects.
In this embodiment, the defect detection signals output from the array type magnetic sensor 12a and the array type magnetic sensor 13a closer to the front or back surface of the thin steel plate 11 are used to determine the degree of surface defects.

FIG. 5 is an explanatory diagram of an example of the artificial defect sample and the determination database.
In creating the determination database DB, a plurality of artificial steels with different steel types, defect depths (maximum and equal to the thickness of the thin steel plate 11 in the case of a through hole), and defect sizes (diameters) are used. Create a defect sample.
In the case of the example of FIG. 5, for each steel type (A, B,...), Four types of samples of a1 mm, a2 mm, a3 mm, and through-holes are created for the depth of defects.
As for the size (diameter) of the defect, three types of samples of φb1 mm, φb2 mm, and φb3 mm are prepared.
As a result, 12 types of artificial defect samples of 4 (types) × 3 (types) are created, measured by the array type magnetic sensor 12a and the array type magnetic sensor 13a, and output from the array type magnetic sensors 12a and 13a. The output voltage value (V) of the detected defect detection signal is stored in the storage unit 15a as the determination database DB.
Specifically, for example, when the depth of defect = a2 mm and the size (diameter) of defect = φb2 mm for the steel type A, the output voltage value of the defect detection signal = c6V is stored in the determination database. When the depth of the defect = a3 mm and the size (diameter) of the defect = φb2 mm, the output voltage value of the defect detection signal = c7V is stored, and when the depth of the defect = a2 mm and the size of the defect (diameter) = φb3 mm Stores the output voltage value of the defect detection signal = c10V.
In the case of the above specific example, the voltage value cx of the defect detection signal output from the array type magnetic sensor 12a is
c6 ≦ cx <c7
In this case, it is estimated that the defect size is b2 mm and the defect depth is a2 mm or more and less than a3 mm.

Next, determination of the type of defect will be described.
The types of defects that can be discriminated in the present embodiment are determined according to combinations of signal levels of defect detection signals output by the array type magnetic sensors 12a, 12b, 13a, and 13b.
More specifically, the defect detection signal output by the magnetic sensor constituting the array type magnetic sensor 12a corresponding to the same detection position is A, the defect detection signal output by the magnetic sensor constituting the array type magnetic sensor 12b is B, The defect detection signal output from the magnetic sensor that constitutes the array type magnetic sensor 13a is C, the defect detection signal that is output from the magnetic sensor that constitutes the array type magnetic sensor 13a is D, and the output signal level of each defect detection signal AD. Are identified as large (indicated by ◎ in the figure), small (indicated by ◯ in the figure), and no output (indicated by x in the figure), these four defect detection signals A to D are output. The type of defect is determined according to the combination of signal levels.

  Here, a large output signal level of the defect detection signals A to D corresponds to a large amount of leakage magnetic flux detected, and a small output signal level of the defect detection signals A to D represents a small amount of leakage magnetic flux detected. Correspondingly, the output signal level of the defect detection signals A to D = no output indicates that the leakage magnetic flux is not detected (or less than the amount considered not to be detected).

FIG. 6 is an explanatory diagram of the modeled defect state.
FIG. 7 is a diagram for explaining the correspondence between the output of the array type magnetic sensor and the defect state.
Here, the case where it detects based on an identification table using the modeled defect shown in FIG. 6 is demonstrated.
As shown in FIGS. 6 (a1) and 7, when a relatively large surface defect is formed on the surface side of the thin steel plate 11, a defect detection signal output from the magnetic sensor constituting the array type magnetic sensor 12a. The output signal level of A is large (◎), the output signal level of the defect detection signal B output from the magnetic sensor constituting the array type magnetic sensor 12b is high (◎), and the magnetic sensor constituting the array type magnetic sensor 13a. The output signal level of the defect detection signal C output from the above is small (◯), and the output signal level of the defect detection signal D output from the magnetic sensor constituting the array type magnetic sensor 13b is not output (×).

  In addition, as shown in FIGS. 6A2 and 7, when a relatively large surface defect is formed on the back surface side of the thin steel plate 11, the defect output from the magnetic sensor constituting the array type magnetic sensor 12a. The output signal level of the detection signal A is no output (x), the output signal level of the defect detection signal B output from the magnetic sensor constituting the array type magnetic sensor 12b is small (◯), and the array type magnetic sensor 13a is configured. The output signal level of the defect detection signal C output from the magnetic sensor is large (◎), and the output signal level of the defect detection signal D output from the magnetic sensor constituting the array type magnetic sensor 13b is high (◎).

  In addition, as shown in FIGS. 6B1 and 7, when a relatively small surface defect is formed on the surface side of the thin steel plate 11, the defect detection output by the magnetic sensor constituting the array type magnetic sensor 12a is detected. The output signal level of the signal A is large (◎), the output signal level of the defect detection signal B output from the magnetic sensor constituting the array type magnetic sensor 12b is low (◯), and the magnetic force constituting the array type magnetic sensor 13a. The output signal level of the defect detection signal C output from the sensor is no output (x), and the output signal level of the defect detection signal D output from the magnetic sensor constituting the array type magnetic sensor 13b is no output (x).

  Further, as shown in FIGS. 6 (b2) and 7, when a relatively small surface defect is formed on the back side of the thin steel plate 11, the defect output from the magnetic sensor constituting the array type magnetic sensor 12a. The output signal level of the detection signal A is no output (x), the output signal level of the defect detection signal B output from the magnetic sensor constituting the array type magnetic sensor 12b is no output (x), and the array type magnetic sensor 13a is turned on. The output signal level of the defect detection signal C output from the constituent magnetic sensor is high (◎), and the output signal level of the defect detection signal D output from the magnetic sensor forming the array type magnetic sensor 13b is low (◯). .

  6 (c1) and FIG. 7, when a relatively large internal defect is formed in the thin steel plate 11, the defect detection signal A output from the magnetic sensor constituting the array type magnetic sensor 12a The output signal level is high (◎), the output signal level of the defect detection signal B output from the magnetic sensor constituting the array type magnetic sensor 12b is low (◯), and the output of the magnetic sensor constituting the array type magnetic sensor 13a. The output signal level of the detected defect detection signal C is high (）), and the output signal level of the defect detection signal D output from the magnetic sensor constituting the array type magnetic sensor 13b is low (◯).

  Further, as shown in FIGS. 6 (c2) and 7, when a relatively small internal defect is formed on the thin steel plate 11, the defect detection signal A output from the magnetic sensor constituting the array type magnetic sensor 12a. Output signal level is small (◯), the output signal level of the defect detection signal B output from the magnetic sensor constituting the array type magnetic sensor 12b is no output (x), and the magnetic sensor constituting the array type magnetic sensor 13a The output signal level of the defect detection signal C output from the above is small (◯), and the output signal level of the defect detection signal D output from the magnetic sensor constituting the array type magnetic sensor 13b is not output (×).

Further, as shown in FIGS. 6D and 7, when the through hole is formed in the thin steel plate 11, the output signal of the defect detection signal A output from the magnetic sensor constituting the array type magnetic sensor 12a. The level is large (◎), the output signal level of the defect detection signal B output from the magnetic sensor constituting the array type magnetic sensor 12b is high (◎), and the defect output from the magnetic sensor constituting the array type magnetic sensor 13a. The output signal level of the detection signal C is high (◎), and the output signal level of the defect detection signal D output from the magnetic sensor constituting the array type magnetic sensor 13b is high (◎).
Further, as shown in FIG. 7, when any defect is not detected, the output signal level of the defect detection signal A output from the magnetic sensor constituting the array type magnetic sensor 12a becomes no output (x), and the array The output signal level of the defect detection signal B output from the magnetic sensor constituting the magnetic sensor 12b is no output (x), and the output signal level of the defect detection signal C output from the magnetic sensor constituting the array magnetic sensor 13a is No output (x), and the output signal level of the defect detection signal D output from the magnetic sensor constituting the array type magnetic sensor 13b is no output (x).

Next, the operation of the embodiment will be described.
FIG. 8 is an operation flowchart of the embodiment.
FIG. 9 is an explanatory diagram of the determination processing of the embodiment.
First, the steel type information for specifying the steel type to be detected is updated (step S11).
Next, defect detection signals A to D output from the magnetic sensors for detecting each of the array type magnetic sensors 12a, 12b, 13a, and 13b are detected (step S12).

Subsequently, it is determined whether or not any of the output signal levels of the defect detection signals A to D is large (◎) or small (◯), that is, whether or not there is a defect in the thin steel plate 11 (step S13).
In the determination of step S13, when all the defect detection signals A to D are not output (x), that is, when it is determined that there is no defect in the thin steel plate 11 (step S13; No), processing is performed. To step S17.
In the determination of step S13, when any of the output signal levels of the defect detection signals A to D is large (（) or small (◯), that is, when it is detected that the thin steel plate 11 has a defect. (Step S13; Yes), the type of the defect is determined, and it is determined whether or not the type of the detected defect is an internal defect (Step S14).

  Specifically, according to FIG. ##, the output signal level of the defect detection signal A output from the magnetic sensor constituting the array type magnetic sensor 12a → the defect detection signal B output from the magnetic sensor constituting the array type magnetic sensor 12b. Output signal level → output signal level of defect detection signal C output from the magnetic sensor constituting array type magnetic sensor 13a → order of output signal level of defect detection signal D output from magnetic sensor constituting array type magnetic sensor 13b And determine from the combination whether or not it is an internal defect.

If it is determined in step S14 that the detected defect is an internal defect (step S14; Yes), the stricter size of the internal defect cannot be specified, and the process proceeds to step S17.
If it is determined in step S14 that the detected defect is a surface defect (step S; No), the output level of the defect detection signal A output from the magnetic detection element MS constituting the array type magnetic sensor 12a and the array type are detected. Based on the defect detection signal C output from the magnetic detection element MS constituting the magnetic sensor 13a, the detected defect state (feature amount) is detected (step S15).

That is, the depth of the defect and the defect size are specified based on the contents of the defect detection database shown in FIG.
Specifically, when the output level (output voltage) of the defect detection signal A output from the magnetic detection element MS constituting the array type magnetic sensor 12a = c7 (V), a defect is formed on the back side of the thin steel plate 11. The defect depth is specified as a3 mm and the defect size is specified as b2 mm.

Thereby, the defect state determination unit 15 stores the detected depth of the defect and the size of the defect together with the position information where the defect is detected, and outputs the data to the outside (step S16).
Subsequently, the defect determination unit 14 determines whether or not the end of the thin steel plate 11 has been reached and the steel plate is not present, that is, whether or not a plateless state has been reached (step S17).

If it is determined in step S17 that the end of the thin steel plate 11 has not yet been reached (step S17; No), the process proceeds to step S12 again in order to continue the defect detection.
If it is determined in step S17 that the end of the thin steel plate 11 has been reached (step S; Yes), it is determined whether or not the measurement (defect detection processing of the thin steel plate 11) is continued according to an operator instruction or the like (step S17). S).

In the determination of step S18, when the measurement, that is, the defect detection process of the thin steel plate 11 is continued (step S18; Yes), the array type magnetic sensors 12a, 12b, 13a, and 13b are automatically calibrated (step S19). ), Until the next defect detection.
In the determination in step S18, when the measurement, that is, the defect detection rule of the thin steel plate 11 is ended (step S18; No), the process is ended.

As described above, according to the present embodiment, at the time of transport such as when the thin steel plate 11 is manufactured, it is only detected that a defect has been formed on the surface or inside of the thin steel plate 11 while being transported. If a defect is detected, the formation position, the formation surface (the front surface or the back surface of the thin steel plate), and the defect formation state (in this embodiment, the defect depth and the defect diameter) are determined to determine the defect formation state. It is possible to easily acquire information (features) related to and store and output the information.
Therefore, it is possible to automatically perform production management or quality control of the thin steel plate 11.

  The steel sheet defect inspection apparatus of the present embodiment includes a control device such as a CPU, a storage device such as a ROM (Read Only Memory) and a RAM, an external storage device such as an HDD and a CD drive device, and a display device such as a display device. It has an input device such as a keyboard and a mouse, and has a hardware configuration using a normal computer.

  The control program executed by the steel sheet defect inspection apparatus of the present embodiment is an installable or executable file, such as a CD-ROM, a flexible disk (FD), a CD-R, a DVD (Digital Versatile Disk), etc. The program is provided by being recorded on a computer-readable recording medium.

Moreover, you may comprise so that the control program run with the steel plate defect inspection apparatus of this embodiment may be provided by storing on a computer connected to networks, such as the internet, and downloading via a network. In addition, the program executed in the apparatus of the present embodiment may be provided or distributed via a network such as the Internet.
Moreover, you may comprise so that the control program of the steel plate defect inspection apparatus of this embodiment may be previously incorporated in ROM etc. and provided.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 Steel plate defect inspection apparatus 11 Thin steel plate 11a Nonmagnetic roll 12 Surface magnetic sensor unit 12C Magnetizing yoke 12a Array type magnetic sensor 12b Array type magnetic sensor 12c Magnetizing yoke 13 Back surface magnetic sensor unit 13a Array type magnetic sensor 13b Array type magnetic sensor 13c Magnetization Yoke 14 Defect determination unit 15 Defect state determination unit (Defect state determination means)
15a Storage unit (storage means)
15b Arithmetic units 16a to 16c Delay circuit unit 17 Speed detector 21 Nonmagnetic roller A to D Defect detection signal DB Defect determination database (storage means)
MC Magnetization coil MF Magnetic flux MS Magnetic detection element

Claims (6)

The thin steel plate is magnetized in the transport direction, and the leakage magnetic flux generated by the defective portion of the thin steel plate is detected by an array type magnetic sensor having a plurality of magnetic detection elements arranged in a direction intersecting the traveling direction, and the thin steel plate is detected. A steel sheet defect inspection apparatus for determining the type of defects in a steel sheet,
A first array type magnetic sensor disposed at a predetermined distance from the surface side of the thin steel plate;
A second array type magnetic sensor disposed on the back side of the thin steel plate and spaced apart by the predetermined distance;
Memory that stores in advance the correspondence between the detection level of the first array type magnetic sensor and the detection level of the second array type magnetic sensor corresponding to the same defect detection target position, and the defect state of the thin steel plate Means,
Referring to the storage means, based on the detection level of leakage magnetic flux in the first array type magnetic sensor and the detection level of leakage magnetic flux in the second array type magnetic sensor corresponding to the same defect detection target position. Defect state determination means for determining the defect state of the thin steel sheet;
Steel sheet defect inspection device equipped with. The storage means stores a defect depth and a defect size as the defect state.
The steel plate defect inspection apparatus according to claim 1. The defect state determination means determines a state of a surface defect including a through hole,
The steel plate defect inspection apparatus according to claim 1 or 2. The storage means has a correspondence relationship between the detection level of the first array type magnetic sensor and the detection level of the second array type magnetic sensor and at least three detection levels and a defect state of the thin steel sheet. Pre-stored,
The steel plate defect inspection apparatus according to any one of claims 1 to 3. A first array-type magnetic sensor that magnetizes the thin steel sheet in the conveying direction, and that has a leakage magnetic flux generated by a defective portion of the thin steel sheet, spaced apart from the surface of the thin steel sheet by a predetermined distance, and the back surface of the thin steel sheet A steel plate defect inspection method that is executed by a steel sheet defect inspection apparatus that detects a defect type of the thin steel sheet by detecting with a second array type magnetic sensor arranged at a predetermined distance on the side,
A level acquisition process for acquiring a leakage flux detection level in the first array type magnetic sensor and a leakage flux detection level in the second array type magnetic sensor corresponding to the same defect detection target position;
Based on the correspondence relationship between the detection level of the first array type magnetic sensor and the detection level of the second array type magnetic sensor corresponding to the same defect detection target position, and the defect state of the thin steel sheet, A defect state determination process for determining a defect state of a thin steel sheet;
A method for inspecting a defect in a steel sheet, comprising: A first array-type magnetic sensor that magnetizes the thin steel sheet in the conveying direction, and that has a leakage magnetic flux generated by a defective portion of the thin steel sheet, spaced apart from the surface of the thin steel sheet by a predetermined distance, and the back surface of the thin steel sheet A control program for controlling by a computer a steel plate defect inspection apparatus that is detected by the second array type magnetic sensor arranged at a predetermined distance on the side and that determines the type of defect in the thin steel plate ,
The computer,
Level acquisition means for acquiring a leakage flux detection level in the first array type magnetic sensor and a leakage flux detection level in the second array type magnetic sensor corresponding to the same defect detection target position;
Based on the correspondence relationship between the detection level of the first array type magnetic sensor and the detection level of the second array type magnetic sensor corresponding to the same defect detection target position, and the defect state of the thin steel sheet, A defect state determining means for determining a defect state of the thin steel sheet;
Control program to function.

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