JPH06201613A - Automatic flaw detector with fluorescent magnetic powder - Google Patents

Abstract

PURPOSE:To maintain high flaw detecting performance even if a scattering amount of fluorescent magnetic powder, intensity of an ultraviolet ray, etc., are varied by deciding a flaw decision threshold value based on an average value of signal intensity of an image signal. CONSTITUTION:A controller 56 inputs an image signal SV from a TV camera 46, and sets a flaw detecting area of only a surface 18 to be flaw-detected of a material 12 to be inspected. The signal SV is smoothed with respect to a longitudinal direction of the material 12 to remove noise. An average value Iav of a signal intensity I of the signal SV in the area is calculated, and a value of, for example, 2-4 times as large as it is set to a flaw decision threshold value TH based on the value Iav. It is differentiated with respect to a lateral direction of the material 12 to abruptly vary a change in the intensity I to sharpen the image. The intensity I is compared with the value TH, a part of I>TH is extracted as a flaw candidate, part to be considered to be noise is removed therefrom, the flaw candidate after removing is judged as the flaw. The value TH is varied in response to the change in the intensity I of the signal SV is varied to always judge presence/absence of the flaw accurately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent magnetic powder for automatically detecting the presence or absence of a surface scratch and a scratch position by picking up an image of the pattern of the fluorescent magnetic powder adhering to the surface of a material to be inspected and performing image processing. The present invention relates to an improvement of the automatic flaw detector.

[0002]

2. Description of the Related Art As a means for detecting surface scratches on a material to be inspected such as steel, there is a fluorescent magnetic particle flaw detection method. This is because when the fluorescent magnetic powder is attached to the surface of the material to be inspected by showering or misting, and the material to be inspected is magnetized and the material to be inspected is magnetized, the magnetic flux gathers at the scratched portion due to leakage flux due to surface scratches Since the light is strongly emitted at the scratched portion, the presence or absence of the scratch and the position are known from the light emitting state (magnetic powder pattern). Then, the magnetic powder pattern is picked up by an image pickup device,
2. Description of the Related Art There is known an automatic flaw detection device that automatically detects the presence or absence of a flaw and the position of the flaw by comparing the image signal with a predetermined flaw determination threshold value. Further, for a long inspection material such as steel material, the inspection material or the imaging device is moved in the longitudinal direction, and the surface of the inspection material is divided into a plurality of blocks for flaw detection. There is. An example thereof is the automatic flaw detection device described in Japanese Patent Application No. 4-100425 filed by the applicant earlier.

[0003]

By the way, when the amount or concentration of the above-mentioned fluorescent magnetic particles fluctuates or changes with time, the emission intensity of the scratched portion and further the signal strength of the image signal change, so that the detection of the scratches is detected. The accuracy decreases. The same applies when the intensity of ultraviolet rays changes due to deterioration of the lamp. For this reason, in order to maintain a constant flaw detection performance, it was necessary to regularly measure the amount of the fluorescent magnetic powder sprayed, the ultraviolet intensity, etc., and strictly control them.

Further, even if the amount of magnetic powder and the intensity of ultraviolet rays are regularly inspected as described above, it is possible to cope with a sudden change due to clogging of the nozzle for spraying the fluorescent magnetic powder or burnout of ultraviolet rays. Instead, it was left as it was until the next periodic inspection, and there was a possibility of overlooking serious surface scratches. There is also a method to constantly monitor the amount of magnetic powder sprayed, the intensity of ultraviolet rays, etc., but in order to monitor a large number of nozzles that spray fluorescent magnetic powder on a long steel material, for example, a large number of monitoring devices are required As a whole, there is a problem that the cost becomes high and the cost becomes high.

The present invention has been made in view of the above circumstances. A first object of the present invention is to maintain high flaw detection performance even when the amount of fluorescent magnetic powder sprayed or the intensity of ultraviolet rays changes. The second object is to make it possible to easily and quickly detect abnormalities such as the amount of magnetic powder sprayed and the ultraviolet intensity.

[0006]

A first invention is to achieve the above first object, and (a) irradiates the surface of the material to be inspected with the fluorescent magnetic particles with ultraviolet rays. Irradiation means, (b) an image pickup device for picking up an image of the surface and outputting an image signal, and (c) a scratch judgment for judging the presence or absence of a scratch on the surface by comparing the signal intensity of the image signal with a scratch judgment threshold value. A fluorescent magnet powder type automatic flaw detector having means, (d) calculating means for obtaining an average value of the signal intensity of the image signal, and (e)
Threshold value determining means for determining the scratch determination threshold value based on the average value obtained by the calculating means.

[0007]

In the fluorescent magnetic powder type automatic flaw detector as described above, the average value of the signal intensity of the image signal is obtained by the calculation means, and the flaw judgment threshold value is determined based on the average value. The presence or absence of the surface flaw is determined by comparing the flaw determination threshold value determined by the means with the signal intensity of the image signal. Therefore, when the emission intensity of the entire surface of the material to be inspected and further the signal intensity of the entire image signal changes due to a change in the amount of the fluorescent magnetic particles or the ultraviolet intensity, the intensity change of the image signal changes. Accordingly, the scratch determination threshold value also changes, and it becomes possible to always determine the presence or absence of a scratch with high accuracy.

[0008]

A second aspect of the present invention is to achieve the second object, and (a) irradiates the surface of a material to be inspected to which fluorescent magnetic powder is adhered with ultraviolet rays. Irradiation means, (b) an image pickup device for picking up an image of the surface and outputting an image signal, and (c) a scratch judgment for judging the presence or absence of a scratch on the surface by comparing the signal intensity of the image signal with a scratch judgment threshold value. A fluorescent magnet powder type automatic flaw detector having means, (d) calculating means for obtaining an average value of the signal intensity of the image signal, and (e)
An abnormality determining means for determining abnormality of the flaw detection condition based on the average value obtained by the calculating means.

[0009]

In the fluorescent magnetic powder type automatic flaw detector as described above, the average value of the signal intensity of the image signal is obtained by the calculating means, and the amount of the fluorescent magnetic powder applied is calculated based on the average value. Abnormality in flaw detection conditions such as the intensity of ultraviolet rays and ultraviolet rays is judged by the abnormality judging means. That is, when the amount of the fluorescent magnetic powder applied, the ultraviolet intensity, or the like changes, the emission intensity of the entire surface of the material to be inspected, and further, the signal intensity of the entire image signal changes, so that the average value of the signal intensity is, for example, If it is lower than a predetermined reference value, or if it is extremely lower than the average value of the signal intensity at the time of the previous flaw detection, there is an abnormality such that the amount of the fluorescent magnetic particles is less than usual or the ultraviolet intensity is weak. You can judge that there is.

As described above, according to the second aspect of the invention, an abnormality such as the amount of dispersed magnetic particles or the intensity of ultraviolet rays can be easily and quickly detected based on the signal intensity of the image signal. Can be effectively prevented, and reliability is improved. Further, since a large-scale monitoring facility is not required, the flaw detector can be made compact and inexpensive as a whole, and the burden on the operator such as regular inspection can be reduced.

[0011]

A third aspect of the present invention is to achieve the above first and second objects.
Irradiation means for irradiating the surface of the material to be inspected to which the fluorescent magnetic powder is attached with ultraviolet rays, (b) an image pickup device for picking up the surface and outputting an image signal, and (c) scratching the signal intensity of the image signal. In a fluorescent magnetic powder type automatic flaw detection device having a scratch judging means for judging the presence or absence of scratches on the surface in comparison with a judgment threshold value,
(D) calculating means for obtaining an average value of the signal intensity of the image signal, and (e) abnormality determining means for determining an abnormality in flaw detection conditions based on the average value obtained by the calculating means,
(F) threshold value determining means for determining the flaw determination threshold value based on the average value obtained by the calculating means.

[0012]

[Operation and effect of the third invention] That is, the third invention is a combination of the first invention and the second invention.
The flaw judgment threshold is determined based on the average value of the signal intensity of the image signal, and the flaw detection condition is determined to be abnormal, regardless of whether the flaw detection condition such as the amount of the fluorescent magnetic powder sprayed or the UV intensity is abnormal. The flaw detection can be performed with high accuracy, and the abnormality of the flaw detection condition can be detected easily and quickly, and the reliability of the apparatus is significantly improved.

[0013]

A fourth aspect of the present invention is to achieve the first and second objects.
An image pickup device that is moved in the longitudinal direction of a long test material having fluorescent particles adhered to the surface thereof and divides the surface into a plurality of blocks to pick up an image, and (b) integrally with the image pickup device. Irradiating means for irradiating the surface with ultraviolet rays relative to the material to be inspected, and (c) comparing the signal intensity of the image signal output from the image pickup device for each block with a flaw determination threshold value. A fluorescent magnet powder type automatic flaw detector having a flaw judging means for judging the presence or absence of a flaw on the surface, (d)
Calculating means for obtaining the average value of the signal intensity of the image signal for each block, and (e) threshold determining means for determining the scratch determination threshold for each block based on the average value obtained by the calculating means, (F) first abnormality determining means for comparing the average values of the respective blocks obtained by the calculating means with each other to determine an abnormality in the flaw detection condition; and (g) average value of the respective blocks obtained by the calculating means. Is averaged and compared with a preset reference value, and second abnormality determining means for determining abnormality in the flaw detection condition is provided.

[0014]

According to a fourth aspect of the present invention, the material to be inspected and the image pickup device are relatively moved in the longitudinal direction of a long material to be inspected, and the surface of the material to be inspected is divided into a plurality of blocks. The flaw detection threshold value is determined by determining the average value of the signal strength of the image signal for each block, and the presence or absence of a flaw is determined based on the flaw determination threshold value. Therefore, even if the flaw detection conditions are different in one inspected material, for example, if the amount or concentration of the fluorescent magnetic powder is uneven, flaw detection can always be performed with high accuracy.

Further, since the average values of the signal intensities in the respective blocks are compared with each other to judge whether the flaw detection condition is abnormal, for example, when the fluorescent magnetic powder is sprayed by using a large number of nozzles, By such abnormality determination, it is possible to identify a nozzle having an abnormality such as clogging, and it is possible to detect the abnormality of the magnetic particle adhering device or the ultraviolet irradiation means in a very fine manner. Abnormality of flaw detection conditions is judged by averaging the average value of the signal intensity in each block and comparing it with a preset reference value, so it can respond to long-term changes in flaw detection conditions such as deterioration of the ultraviolet lamp. Therefore, it is possible to reliably judge the abnormality of the flaw detection condition and obtain high reliability.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view of a fluorescent magnetic powder type automatic flaw detector (hereinafter, simply referred to as flaw detector) 10 which is an embodiment of the present invention. FIG. 2 is a sectional view thereof and FIG. 3 shows a control system. FIG. In these figures, a material 12 to be inspected, which is a ferro-magnetic steel material, has a rectangular cross section and is elongated, and the ridge lines in the longitudinal direction are positioned vertically and horizontally by a plurality of inspection bases 14. It is supported in a fixed position in a substantially horizontal posture.
Then, the pair of inspection units 16 that are moved in the longitudinal direction of the inspected material 12 detect the scratches present on the outer peripheral surface 18 (the upper two surfaces). The magnetic particle flaw detection method uses scratches (defects) on or near the surface.
The magnetic flux, which is a powder of a ferromagnetic substance, is intensively adsorbed to the scratched portion by the leakage magnetic flux flowing around the magnetic flux and the presence or absence of the scratch or the position is checked from the magnetic powder pattern. , Is exposed to a magnetic field in advance and magnetized,
Fluorescent magnetic particles are adhered to the surface 18 by spraying with a large number of nozzles, dipping, or the like.

Above the inspection object 12, the inspection object 1
A pair of guide rails 24 and 2 parallel to the longitudinal direction of
6 is disposed, and the inspection unit 16 is disposed on a carriage 28 which is supported by the pair of guide rails 24 and 26 and travels so that flaw detection can be performed over the entire length of the inspection target material 12. It has become. The carriage 28 is provided with a servo motor 30 which is rotationally driven in both forward and reverse directions by a drive signal SD1 supplied from the control device 56, and the driving force of the servo motor 30 is driven via a timing belt 32. By being transmitted to the wheels 34 and 36, the carriage 28 is caused to travel on the guide rails 24 and 26 at a predetermined moving speed V. Servo motor 30
Is provided with an encoder 38, and a rotation angle signal SA1 corresponding to the moving speed V of the carriage 28 is supplied to the control device 56. A meshing tooth 40 is formed on the upper surface of one guide rail 24, and a meshing tooth 42 that meshes with the meshing tooth 40 is provided on the outer periphery of the one drive wheel 34 rolling on the guide rail 24. The trolley 28 is
Moves on the guide rail 24 in accordance with the rotation angle of the drive wheel 34.

The dolly 28 has a rectangular box shape, and the pair of inspection units 16 has a reflecting mirror 4 arranged in the dolly 28 in a predetermined positional relationship.
4, a television camera 46, an ultraviolet lamp 48 and the like, respectively. The pair of inspection units 16 are designed to simultaneously detect flaws on two surfaces 18 of the material 12 to be inspected which are directed obliquely upward.
TV camera 46, ultraviolet lamp 48, etc.
They are arranged symmetrically with respect to a vertical plane passing through the two axes. The reflecting mirror 44 is attached to the output shaft of the servo motor 50, and the mirror surface 52 formed in a plane including the axis O of the output shaft is rotatable around the axis O. In the case of 50, the axis O is the material to be inspected 1
It is fixed to the carriage 28 in a posture that is perpendicular to the longitudinal direction of 2, that is, the moving direction of the carriage 28, and is parallel to the surface 18 of the material 12 to be inspected. Further, in the television camera 46, the optical axis of the image pickup lens is parallel to the moving direction of the carriage 28, and the axis O
The light from the surface 18 of the material 12 to be inspected is made incident through the reflecting mirror 44 so that the pattern of the fluorescent magnetic powder on the surface 18 is imaged. The television camera 46 corresponds to an image pickup device, and outputs an image signal SV whose intensity changes according to the amount of incident light to the control device 56.

As shown in FIG. 4, the reflecting mirror 44 has a surface 18 formed by the television camera 46 regardless of the movement of the carriage 28.
In order to keep the image pickup range of (1) constant for a predetermined time, a predetermined predetermined angle range is rotated in synchronization with the moving speed V of the carriage 28. Servo motor 5
0 indicates the control device 5 based on the moving speed V of the carriage 28.
6 is operated according to the drive signal SD2 supplied from the encoder 6, and the rotation angle signal SA2 representing the rotation angle is supplied from the encoder 54 to the controller 56. The rotation of the reflecting mirror 44 is repeated at a predetermined timing determined based on the moving speed V, whereby the surface 1
8 is divided into a plurality of blocks and sequentially captured. Figure 4
The hatched line indicates the image pickup range of the television camera 46, and in FIGS. 4A to 4C, the block n is imaged in a substantially stationary state regardless of the movement of the carriage 28. Figure 4 (d)
Causes the reflecting mirror 44 to return and rotate to the rotation position of (a), whereby the imaging range of the television camera 46 moves to the next block n + 1. In addition, such a television camera 46
Is configured to perform horizontal scanning in the width direction of the material 12 to be inspected, that is, the vertical direction in FIG. 4, and perform vertical scanning in the longitudinal direction.

The ultraviolet lamp 48 corresponds to an irradiating means, and can irradiate ultraviolet light to the entire image pickup range of the television camera 46 which is relatively changed with respect to the carriage 28 with the rotation of the reflecting mirror 44. In addition, it is attached to the carriage 28 with a predetermined irradiation range. The material to be inspected 12
Below the pair of left and right ridgelines 58 and 60 among the four ridgelines extending in the longitudinal direction, a pair of edge irradiation lamps 62 are provided in the moving direction of the carriage 28.
4 is disposed at substantially the same position as that of the ridges 58 and 60.
By irradiating each with visible light, the edges of the ridge lines 58 and 60 in the captured image are made clear. In addition, a pair of light projector 64 and light receiver 66 are arranged on both sides of the material 12 to be inspected. The light projector 64 and the light receiver 66 function as a photoelectric switch, and after the carriage 28 starts moving from the initial position where the light emitted from the light projector 64 toward the light receiver 66 is not blocked, the material to be inspected is inspected. It is detected that the light is blocked by passing through the terminal 68 on the flaw detection start side of 12 and the control device 56 can determine the flaw detection start time of the inspected material 12 based on the detection signal SP. .

The control device 56 includes a CPU, a ROM and a RAM.
And the like according to a program stored in advance in the ROM.
The calculation processing is performed while utilizing the temporary storage function of 1 to output the drive signals SD1 and SD2, thereby moving the carriage 28 and rotating the reflecting mirror 44 in synchronization with the movement of the carriage 28. In addition, a scratch map of the surface 18 is created based on the image signal SV supplied from the television camera 46. Hereinafter, referring to the flowchart of FIG.
The signal processing of the image signal SV will be specifically described.

First, in step S1, it is judged whether or not it is the timing of taking in the image signal SV based on the rotation angle of the reflecting mirror 44, and if YES, the image signal S is obtained in step S2.
Take in V. The timing at which the image signal SV is captured is set to the time during which the surface of the surface 18 is imaged in a substantially stationary state by the rotation of the reflecting mirror 44, and, for example, (a) to FIG.
It is time of (c). In the next step S3, a flaw detection area including only the surface 18 to be flaw-detected is set from the captured image represented by the captured image signal SV. For example, the alternate long and short dash line A in FIG. 6 indicates the inspection unit 16 on the right side of FIG.
The image pickup range of the TV camera 46, that is, the image signal SV
In the range of the captured image represented by, the hatched range B is a flaw detection area, and the range B _{1 in} the longitudinal direction of the material 12 to be inspected in the flaw detection area B is predetermined for the captured image A. Further, in the range B _{2 in the} width direction perpendicular to the longitudinal direction of the inspected material 12, the ridge line 60 is discriminated based on the change in the signal intensity of the image signal SV in the width direction, and the surface 18 preset by the setter or the like is used. It is determined according to the width dimension of. The ridgeline 60 is irradiated with visible light by the edge irradiation lamp 62, and the signal intensity I of the image signal SV changes abruptly at the ridgeline 60, so the ridgeline 60 is discriminated with high accuracy. In the following steps, only the image signal SV within the flaw detection area B is processed.

In step S4, the image signal SV is smoothed in the longitudinal direction of the material 12 to be inspected, that is, the horizontal direction in FIG. 6, and noise is removed. Since the material 12 to be inspected is rolled in the longitudinal direction, surface scratches are usually long in the longitudinal direction, and even if smoothing is performed in the longitudinal direction as described above, the signal caused by the actual scratch is hardly affected. . In step S5, the average value I of the signal intensity I of the image signal SV in the flaw detection area B is calculated.
av is calculated, and in step S6, a value about 2 to 4 times the average value Iav is set as the scratch determination threshold TH based on the average value Iav.

In step S7, a differential process (difference process) is performed in the width direction of the material 12 to be inspected, that is, in the vertical direction of FIG.
Is performed to sharpen the change in the signal intensity I of the image signal SV to sharpen the image. In the next step S8, the signal intensity I is compared with the scratch determination threshold value TH to extract a portion of I> TH as a scratch candidate, and in step S9, what is considered to be noise due to the connection pattern of the scratch candidate is extracted. Remove. In this case, for example, when the scratch candidates are not continuous in the longitudinal direction of the inspected material 12, it is judged as noise and removed. In the next step S10, the scratch candidate after being removed as noise is finally determined. It is judged as a scratch and the position of the scratch is stored.

Through the above steps, the flaw detection process for one block of the surface 18 divided into a plurality of pieces is completed. These steps are performed until the reflecting mirror 44 is returned and rotated from the state of FIG. 4C to the state of FIG. 4D and the acquisition of the image signal SV of the next block is started.
Then, in the next step S11, it is determined whether or not the flaw detection on one surface 18 of the inspection target material 12 is completed based on, for example, the detection signal SP of the photodetector 66,
Step S1 and subsequent steps are repeatedly executed until the flaw detection is completed. As a result, the flaw detection process on the surface 18 is performed for each block in FIG. It should be noted that after the image signals SV of all blocks have been captured, step S is performed for each block.
The flaw detection processing of 3 or less may be executed.

When the flaw detection for one surface 18 is completed and the determination in step S11 is YES, in step S12, the flaw detection areas B of the blocks are connected to each other to create a flaw map showing the flaw position of the entire surface 18. To do.
The flaw detection area B of each block is set in advance so as to overlap each other in the longitudinal direction of the inspection target material 12.

In the next step S13, the average value Iav calculated in the step S5 in the flaw detection processing of each block is compared with each other to judge whether the flaw detection condition is abnormal. Specifically, for example, the average value Iav of each block is averaged to obtain TIav, and the average value Iav is 50 to TIav, for example.
It is determined that there is some abnormality in the flaw detection condition in a block having a predetermined value or less set in the range of about 90%. In this embodiment, since the ultraviolet lamp 48 is attached to the carriage 28, it is considered that the ultraviolet irradiation conditions in each block are substantially the same, and it is considered that the fluorescent magnetic particles have uneven distribution. For example, when the material 12 to be inspected is fixedly positioned and the fluorescent magnetic powder is sprayed by a large number of nozzles that are also fixedly fixed, the nozzles of the block in the portion where the average value Iav is low may be clogged. It is considered that there is an abnormality, and the operator is notified of the abnormality by lighting an abnormality lamp indicating the block. Average value Iav and TI
The abnormality display may be performed when the abnormality of the same block continues for a predetermined number of times as necessary, such as when the difference from av is relatively small.

Further, in the next step S14, it is judged whether the flaw detection condition is abnormal or not by determining whether the average TIav of the average values Iav of the respective blocks is smaller than a predetermined reference value Im or not. Notify the operator of the abnormality. The reference value Im is, for example, a value of about 50 to 90% of the average signal intensity I in the case where the fluorescent magnetic powder is normally attached and the ultraviolet lamp 48 is correctly radiating ultraviolet rays. The UV lamp 48 is set by this
It is possible to judge an abnormality such as a decrease in the ultraviolet intensity with time due to the deterioration of, and a decrease in the concentration of the fluorescent magnetic powder with time. Also in this case, the abnormality display may be performed when the abnormal state continues for a predetermined number of times, if necessary.

Here, the flaw detection device 10 of the present embodiment will be described.
Calculates the average value Iav of the signal intensity I of the image signal SV in step S5, then obtains the scratch determination threshold TH based on the average value Iav in step S6, and in step S8 the scratch determination threshold TH and the signal intensity Iv. Since the scratch judgment is made by comparing with, the light intensity from the inspection target material 12 is changed due to the change of the amount and concentration of the fluorescent magnetic powder, the ultraviolet intensity, and the image signal SV. Even if the signal strength I of changes
By changing the flaw determination threshold value TH according to the change in the intensity of the image signal SV, it becomes possible to always determine the presence or absence of a flaw with high accuracy.

In the present embodiment, the surface 18 of the long test material 12 is divided into a plurality of blocks for flaw detection, and
Average value Iav of the signal intensity I of the image signal SV for each block
To determine the scratch judgment threshold TH, and the scratch judgment threshold TH
Since it is designed to judge the presence of scratches based on
For example, if there is unevenness in the amount or concentration of the fluorescent magnetic powder,
Even if flaw detection conditions are different on one surface 18 of one inspected material 12, flaw detection can always be performed with high accuracy.

On the other hand, in step S13, the average value Iav of the signal intensities I in each block is compared with each other to determine the abnormality of the flaw detection condition, and the abnormality such as the nozzle clogging in each block is detected. At the same time, in step S14, the average TIav of the average value Iav is compared with a predetermined reference value Im to decrease the ultraviolet intensity with time due to the deterioration of the ultraviolet lamp 48 or to reduce the fluorescent magnetic powder with time. Since it is designed to detect abnormalities such as a decrease in density, it is possible to know such abnormalities in flaw detection conditions quickly and reliably, and in combination with the fact that flaws can always be detected with high accuracy regardless of fluctuations in flaw detection conditions. The reliability of the device is greatly improved.
Further, since a large-scale monitoring facility for directly detecting and monitoring such an ultraviolet intensity and a magnetic powder dispersion state is not necessarily required, the flaw detector 10 including the magnetic powder adhering device and the like is compact and inexpensive as a whole. Along with
The burden on workers such as periodic inspections is reduced.

In the present embodiment, of the series of signal processing by the controller 56, the part that executes step S5 corresponds to the computing means, the part that executes step S6 corresponds to the threshold value determining means, and execute step S8. The portion corresponds to the scratch determining means, the portion executing step S13 corresponds to the first abnormality determining means, and the portion executing step S14 corresponds to the second abnormality determining means.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, in the above-described embodiment, the case where flaw detection is performed while moving the inspection unit 16 with respect to the inspection object 12 has been described, but the inspection unit 16 may be fixed and the inspection object 12 may be moved. . It is also possible to position the inspection target material 12 in a fixed position in a dark room, and move the television camera 46 to perform flaw detection while the front surface 18 is irradiated with ultraviolet light by a large number of ultraviolet lamps fixedly positioned.

In the above embodiment, the surface 18 is imaged in a substantially stationary state via the reflecting mirror 44.
When the moving speed of the dolly 28 is slow, the surface 18 can be directly imaged by the TV camera 46 without using the reflecting mirror 44.

Further, in the above-mentioned embodiment, the case where the long test material 12 having a rectangular cross section is automatically flaw-detected has been described, but the cross-sectional shape and size of the test material can be appropriately changed. It is not limited to the case where two surfaces 18 are simultaneously inspected.
It is also possible to detect only one surface or to detect three or more surfaces at the same time, and it is also possible to provide a plurality of inspection units 16 for one surface.

In the above embodiment, the scratch judgment threshold value TH is set on the basis of the average value Iav of the signal intensity I of the image signal SV, and the abnormality judgment is made on the basis of the average value Iav. Only one of them may be performed.

In the above embodiment, the average value Iav is 2-4.
Although a value about twice is used as the scratch determination threshold value TH, this scaling factor can be changed appropriately, and a predetermined value may be added to the average value Iav, or the scratch determination threshold value TH may be set from a predetermined map using the average value Iav as a parameter. The method of setting the scratch determination threshold TH, such as calculation, is appropriately determined.

In the above embodiment, steps S13 and S
Although two types of abnormality determinations are made at 14, it is possible to make only one of the abnormality determinations. The judgment value for making an abnormality judgment, that is, what percentage of the average TIav or less, and how to set the reference value Im are appropriately determined. The abnormality determination method based on the average value Iav is such that the abnormality determination can be performed by comparing the average value Iav of each block with the reference value Im.
It can be appropriately determined according to the method of attaching the fluorescent magnetic powder and the method of irradiating with ultraviolet rays.

In the above embodiment, the case where the flaw detection area B is set based on the one ridge line 60 has been described, but the ridge lines on both sides are detected by irradiating the ridge lines on both upper and lower sides in FIG. 6, for example. It is also possible to set the flaw detection area B based on that.

Although the television camera 46 is used as the image pickup device in the above-described embodiment, another image pickup device that outputs an image signal corresponding to the amount of incident light may be used.

Although not illustrated one by one, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a main part of a fluorescent magnetic powder type flaw detector according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the automatic flaw detection device of FIG. 1 viewed from the longitudinal direction of a material to be inspected.

FIG. 3 is a diagram illustrating a flow of various signals in the automatic flaw detection device of FIG.

FIG. 4 is a diagram illustrating a relationship between a rotation angle of a reflecting mirror and an imaging range of an imaging device in the automatic flaw detection device of FIG.

5 is a flowchart illustrating an operation related to flaw detection processing of the automatic flaw detection device of FIG.

6 is a diagram illustrating a method of setting a flaw detection area in step S3 of FIG.

[Explanation of symbols]

 10: Fluorescent magnetic powder type automatic flaw detector 12: Inspected material 18: Surface 46: TV camera (imaging device) 48: Ultraviolet lamp (irradiation means) 56: Control device SV: Image signal Step S5: Calculation means Step S6: Threshold Determining means Step S8: Damage determining means Step S13: First abnormality determining means Step S14: Second abnormality determining means

Claims (4)

[Claims] 1. An irradiation means for irradiating the surface of a material to be inspected to which fluorescent magnetic powder is adhered with ultraviolet rays, an image pickup device for picking up an image of the surface and outputting an image signal, and a signal intensity of the image signal is judged as a flaw. In a fluorescent magnetic particle type automatic flaw detector having a scratch judging means for judging the presence or absence of a scratch on the surface by comparing with a threshold value, a calculating means for calculating an average value of the signal intensity of the image signal, and the calculating means. And a threshold value determining unit that determines the scratch determination threshold value based on the average value. 2. An irradiation means for irradiating the surface of a material to be inspected to which fluorescent magnetic particles are adhered with ultraviolet rays, an image pickup device for picking up the surface and outputting an image signal, and a signal strength of the image signal is judged to be a flaw. In a fluorescent magnetic particle type automatic flaw detector having a scratch judging means for judging the presence or absence of a scratch on the surface by comparing with a threshold value, a calculating means for calculating an average value of the signal intensity of the image signal, and the calculating means. An automatic flaw detection device of the fluorescent magnetic powder type, comprising: an abnormality determination means for determining an abnormality in flaw detection conditions based on the average value. 3. Irradiation means for irradiating the surface of the material to be inspected to which the fluorescent magnetic powder is attached with ultraviolet rays, an image pickup device for picking up the surface and outputting an image signal, and a signal strength of the image signal is judged as a flaw. In a fluorescent magnetic particle type automatic flaw detector having a scratch judging means for judging the presence or absence of a scratch on the surface by comparing with a threshold value, a calculating means for calculating an average value of the signal intensity of the image signal, and the calculating means. The abnormality determination means for determining abnormality of the flaw detection condition based on the average value, and the threshold determination means for determining the flaw determination threshold value based on the average value obtained by the calculation means. Magnetic particle type automatic flaw detector. 4. An image pickup device which is relatively moved in a longitudinal direction of a long test material having a surface on which fluorescent magnetic powder is adhered, and which divides the surface into a plurality of blocks to pick up an image, and an image pickup device integrated with the image pickup device. And an image pickup device for irradiating the surface with ultraviolet rays by being moved relative to the material to be inspected.
A fluorescent magnet powder automatic flaw detector having a scratch judging means for judging the presence or absence of a scratch on the surface by comparing the signal intensity of an image signal output for each block with a scratch judging threshold, and the image signal for each block Calculating means for obtaining the average value of the signal strength of the, the threshold determining means for determining the scratch judgment threshold value for each block based on the average value obtained by the calculating means, and each of the blocks obtained by the calculating means. First abnormality determination means for comparing the average values with each other to determine abnormality in the flaw detection condition, and flaw detection by averaging the average values of the respective blocks obtained by the computing means and comparing with a preset reference value A fluorescent magnet powder type automatic flaw detector characterized in that it has a second abnormality judging means for judging an abnormal condition.