JP3496288B2 - Testing method for magnetic particle flaw detection function, verification device for magnetic particle flaw detection function, magnetic particle flaw detection device, and fluorescent jig - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention has a magnetic particle flaw detection function.ofInspectionRegular
Law, Inspection device for magnetic particle inspection function, magnetic particle inspection device and fluorescence treatment
IngredientRegarding

[0002]

2. Description of the Related Art Conventionally, in a fluorescent magnetic powder flaw detection inspection, a flaw in the inspected material is detected by spraying the magnetized inspection material with the fluorescent magnetic powder and visually observing the pattern of the adhered fluorescent magnetic powder. During this flaw inspection, the light intensity of the ultraviolet lamp, the fluorescent brightness of the fluorescent magnetic powder, the surface magnetic field strength of the material to be inspected, etc. are managed, and, for example, by measuring the fluorescent brightness in the fluorescent magnetic powder liquid, Fluorescent brightness is managed. In recent years, flaw detection inspection has been automated with the goal of high detectability and high speed, and flaw detection is performed using an image processing apparatus. In this automatic magnetic particle inspection, a fluorescent magnetic powder solution is sprayed while conveying a magnetized material to be inspected, and the fluorescent substance adhered to the flaw is irradiated with ultraviolet rays to emit light, and an image is captured by a CCD camera to perform image processing. To do.

In this image processing, the video signal captured by the camera is input to the freezer, and the still image obtained here is given to the image processing apparatus to obtain the luminance distribution on the screen. Such still images are continuously generated over time, and image processing is performed on these still images to automatically detect flaws in the material to be inspected.

[0004]

In the magnetic particle inspection as described above, it is not verified whether the functions of the camera and the image processing device are normal, and when the function is abnormal. Has a problem that an error occurs in the flaw detection result, and the reliability of the magnetic particle flaw detection is lowered.

The present invention has been made in view of the above circumstances, and provides a method and apparatus for testing a magnetic particle flaw detection function by imaging a fluorescent jig provided with a phosphor having a predetermined brightness. With the goal.

[0006]

According to a first aspect of the present invention, there is provided a magnetic particle flaw detection function inspection method, wherein an image pickup means captures an image of fluorescence from fluorescent magnetic particles attached to the surface of a material to be inspected, and based on the obtained signal. A method for verifying the function of performing magnetic particle flaw detection of the material to be inspected, the step of imaging fluorescence from a fluorescent jig provided with a phosphor having a predetermined fluorescent brightness used for the magnetic particle flaw detection by the imaging means, A step of setting an area centered on the phosphor from the signal obtained by the image pickup means, and a step of creating a luminance histogram in which the horizontal axis represents gradation and the vertical axis represents frequency in the area. And a step of measuring the average luminance of the area from the luminance histogram, and a step of testing the function with the average luminance.

In the inspection method of the magnetic particle flaw detection function according to the second aspect of the invention, the fluorescence from the fluorescent magnetic powder adhered to the surface of the inspected material is imaged by the imaging means, and the magnetic powder of the inspected material is based on the obtained signal. A method for testing the function of flaw detection,
A process of capturing an image of fluorescence from a fluorescent jig provided with a phosphor having a predetermined fluorescence intensity used for the magnetic particle flaw detection by the image pickup means, and an area centered on the phosphor from the signal obtained by the image pickup means and the process of setting, to the area
Then, a step of creating a luminance histogram in which the horizontal axis is gradation and the vertical axis is frequency, a step of measuring an average luminance of the area from the luminance histogram, a step of measuring a half width of the luminance histogram, And a step of testing the function based on the average brightness and the half width.

A magnetic particle inspection function inspection apparatus according to a third aspect of the invention is a magnetic particle inspection function inspection using a fluorescent jig provided with a phosphor having a predetermined fluorescence intensity used for magnetic particle inspection. An image pickup device for picking up the phosphor, a freezer for generating a still image from a video signal from the image pickup device, and a binarization for converting the still image obtained by the freezer into a binarized image. Means, an X-direction projection means for projecting the binarized image in the X direction, a Y-direction projection means for projecting the binarized image in the Y-direction, and a result of the X-direction projection and the Y-direction projection. Based on the central area setting means for setting a central area centered on the phosphor based on the
Tone, the vertical axis to create a brightness histogram and frequencies, and the average luminance measuring means for measuring the average brightness of the central area on the basis of the bright <br/> histogram, the average luminance or within a predetermined tolerance A gain correction unit that determines whether or not the gain correction unit corrects the gain from the imaging device to the binarization unit or the average brightness is within the allowable range when the average brightness is outside the allowable range. It is characterized in that it is configured to notify that it is outside.

A magnetic particle flaw detection function inspection apparatus according to a fourth aspect of the present invention is a magnetic particle flaw detection function inspection that uses a fluorescent jig provided with a phosphor having a predetermined fluorescence intensity used for magnetic particle inspection. An image pickup device for picking up the phosphor, a freezer for generating a still image from a video signal from the image pickup device, and a binarization for converting the still image obtained by the freezer into a binarized image. Means, an X-direction projection means for projecting the binarized image in the X direction, a Y-direction projection means for projecting the binarized image in the Y-direction, and a result of the X-direction projection and the Y-direction projection. Based on the central area setting means for setting a central area centered on the phosphor based on the
Tone, the vertical axis to create a brightness histogram and frequencies, and the average luminance measuring means for measuring the average brightness of the central area on the basis of the bright <br/> histogram, semi measuring the half width of the luminance histogram A price range measuring unit and a gain correction unit that determines whether or not the average brightness and the half-value width are within a predetermined allowable range, and the gain correction unit, when the average brightness and the half-value width are outside the allowable range, It is characterized in that the gain from the image pickup device to the binarization means is corrected or a notification that the average brightness and the half-value width are out of the allowable range is given. A magnetic particle flaw detector according to a fifth aspect of the invention is characterized by including the magnetic particle flaw detector function inspection apparatus according to the third aspect or the fourth aspect of the invention. A fluorescent jig according to a sixth aspect of the present invention is a fluorescent jig used for testing the function of magnetic particle flaw detection, for identifying a phosphor having a predetermined fluorescent brightness used for the magnetic particle flaw detection and a position of the phosphor. And a fluorescent tape attached around the phosphor in a spaced manner.

[0010]

In the inspection method for the magnetic particle flaw detection function of the present invention and the apparatus used for carrying out the method, the image pickup means for picking up the material to be inspected picks up an image of a fluorescent jig provided with a phosphor of known brightness, and the average of the phosphors is taken. The brightness is measured to verify the function of the magnetic particle flaw detection. Thus, for example, when performing a flaw detection test on a plurality of inspection materials, the fluorescent jig is imaged during the flaw detection period to verify whether or not the function of the magnetic particle flaw detection is normal.

Further, in the inspection method for the magnetic particle flaw detection function of the present invention and the apparatus used for carrying out the method, the brightness distribution of the image is determined by the number of pixels having the brightness higher than the predetermined brightness value of the image corresponding to the phosphor. Then, the function of the magnetic particle flaw detection is verified by this.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a block diagram showing the configuration of the assay device of the present invention, and FIG. 2 is a perspective view showing the structure of a fluorescent jig used for carrying out the method of the present invention. As shown in FIG. 2, reference numeral 1 denotes a fluorescent jig, in which a standard phosphor 7 is attached to one surface of a rectangular parallelepiped square member, and four fluorescent tapes a, b, c are arranged so as to surround the standard phosphor 7. , D are attached. The standard phosphor 7 has a fluorescent brightness similar to that of the fluorescent magnetic powder used for the magnetic particle flaw detection inspection, and has a predetermined area smaller than the area of the fluorescent tape a, b, c, d. The fluorescent tapes a and c have a length of 80 mm and a width of 10 mm, and they are attached with a center-to-center distance of Y _S , and the fluorescent tapes b and d have a length of 80 mm and a width of 10 mm. , They are attached with a center-to-center distance of X _S. The fluorescent tapes a, b, c, and d have a dimensional accuracy of 10/100 mm or less, and are attached at intervals (X _S , Y _S ).
Is determined based on the number of fixed pixels included in the image processing unit described later. This fluorescent jig is for the case where the material to be inspected is a square material, but if the material to be inspected is not a square material, a fluorescent jig having the same shape as that of the material is prepared.

In FIG. 1, reference numeral 2 denotes a roller for conveying the material to be inspected and the fluorescent jig 1, and an ultraviolet lamp 3 is arranged diagonally above the fluorescent jig 1 conveyed on the roller 2. A CCD camera 4 is arranged in the vicinity of the ultraviolet lamp 3, and an image of the fluorescent material of the fluorescent jig 1 is picked up and the brightness signal thereof is detected by a freezer 5.
To enter. The input video signal is generated into a still image by the freezer 5 and given to the image processing unit 6. The binarizing unit 61 of the image processing unit 6 converts the video signal input from the freezer 5 into a binarized image based on a predetermined threshold value. The converted signal is given to the X-direction projection means 62 and the Y-direction projection means 63, and the numerical values obtained by the respective means are given to the central area setting means 64. In the central area setting means 64, the central area 9 centered on the image of the standard phosphor 7 is set based on the given numerical values, and is given to the average luminance measuring means 65 and the half width measuring means 66.

The video signal is input from the freezer 5 to the average luminance measuring means 65 and the half-value width measuring means 66, and the average luminance in the set central area 9 and the half-value width described later are respectively obtained to correct the gain. The data is output to the section 8. The binarizing means 61, the X-direction projection means 62, the Y-direction projection means 63, the central area setting means 64, the average luminance measuring means 65, and the half-value width measuring means 66 are components of the image processing section 6. In addition to this, the image processing unit 6 includes means (not shown) for converting the captured luminance signal into a signal indicating the degree of flaw, and is configured to perform a normal magnetic particle flaw detection inspection.

When the magnetic particle flaw detection function is verified by using the apparatus having the above-described structure, the roller 2 is rotated and the fluorescent jig 1 is conveyed between conveyance of a plurality of square pieces. The fluorescent jig 1 used is one stored in a dark place with low humidity in order to prevent deterioration of the standard phosphor 7. Ultraviolet rays are emitted from the ultraviolet lamp 3 and the standard phosphor 7 and the fluorescent tapes a, b, c and d attached to the fluorescent jig 1 emit light. The light intensity of the ultraviolet lamp 3 is set to 4500 μw / cm ² or more. CCD camera 4
The standard phosphor 7 and the fluorescent tapes a, b, c, d are imaged by. The CCD camera 4 has a shutter speed of 1/250
Second, aperture is set to 4 out of 8 stages. The freezer 5 generates a still image based on the luminance signal from the CCD camera 4, and the image processing unit 6 performs image processing. FIG. 3 is a flowchart showing a procedure for the image processing unit 6 to obtain the average luminance and the half-value width, and the operation of the image processing unit 6 will be described below based on this flowchart.

FIG. 3 is a flow chart showing a procedure for carrying out the image processing section 6 of the present invention. The procedure for detecting the brightness of the standard phosphor will be described with reference to this figure. Binarization means 61
The static image given to the
It is converted into a binarized image (step S11). The binarized image is expanded, reduced, and labeled. Then, in order to remove noise, the area of the light emitting portion is calculated, and a portion smaller than a predetermined area of the standard phosphor 7 is determined to be noise and converted to a dark portion (step S12).

FIG. 4 shows the binarized image on the coordinates.
It is a plan view in which the horizontal direction is the X direction and the vertical direction in the drawing.
Is in the Y direction. In this embodiment, X_SIZEIs in the X direction
512 pixels, Y_SIZE  Has a fixed number of 240 pixels in the Y direction
I'm using one. Image of fluorescent tape a, b, c, d
The parameter that represents the position on the image is x_start, X_end, Y
_start, Y_endThen, the fluorescent tape a is (x₁, Y
_start) To (x₂, Y _start), B is (x_end, Y
₁) To (x_end, Y₂), C is (x₁, Y_{en d})
Et (x₂, Y_end), D is (x_start, Y₁) From
(X_start, Y₂) Located.

Then, in order to set the center position of the range surrounded by the fluorescent tapes a, b, c, d, first, the X-direction projection means 62 projects to measure the luminance in the X-direction (step S13). ). As a result of projection, prof-x for the X coordinate, that is, frequency, x
_Calculate the values of _start and x _end . Next, the Y-direction projection means 63 projects in the Y-direction to measure the brightness (step S14). Similar to the result of the X-direction projection, the values of y _start and y _end are obtained from prof-y, that is, the frequency with respect to the Y coordinate. x _start ,
The values of x _end , y _start and y _{en d} are calculated by the following formulas.

[0019]

[Equation 1]

Next, in order to set the central area 9, the X direction and Y of the range surrounded by the fluorescent tapes a, b, c and d.
The number of pixels H and W in each direction is calculated. H = x _end −x _start +1 W = y _end −y _start +1 Then, the average center (x ₀ , y ₀ ) of the image is calculated by x ₀ = x _start + H / 2 y ₀ = y _start + W / 2 (Step S15), the parameters alpha-x, alpha-y representing the central area 9 are obtained by the following equation (step S16). alpha-x = (x _end −x _start ) / 4 alpha-y = (y _end −y _start ) / 4

The pixel resolution can be calculated from the values of the numbers H and W of pixels. The pixel resolution in the X direction is αX _S /
The pixel resolution in the H and Y directions is calculated by αY _S / W. Note that αX _S and αY _S are fixed values of the image processing unit 6.

In the central area 9 thus set, a brightness histogram of the video signal input from the freezer 5 is created. FIG. 5 is a luminance histogram of a video signal, where the vertical axis represents frequency and the horizontal axis represents gradation. The average luminance measuring means 65 measures the average luminance of the standard phosphor 7 from this histogram (step S17). Next, the half width measuring means 66 obtains the half width F from this histogram (step S18). Here, the half-value width F is the number of pixels having a luminance of ½ or more of the maximum luminance. The histograms of A, B, and C in FIG. 5 all have the average brightness x _a , and even if the average brightness has the same value, the brightness distributions may differ. It is possible to know the difference in the luminance distribution in the case of.

As described above, the average luminance and the half-value width F of the standard phosphor are obtained, and these are input to the gain correction section 8. The gain correction unit 8 determines whether these values are within a predetermined allowable range, and if they are out of the range, outputs a signal for correcting the gain from the CCD camera 4 to the image processing unit. Alternatively, it outputs a signal notifying that the gain is out of the allowable range. As an example of the determination condition, the allowable range for the above-described gain correction is 40 ≦ x _a ≦ 50 for the average brightness x _a and 1400 for the half width F.
≦ F ≦ 1800.

In order to set the central area 9, x
X _start without using only the values of ₁ , x ₂ , y ₁ , y ₂
The values of x _end , y _start and y _end are _calculated as x ₁ , x
_{This is} because the values of ₂ , y ₁ and y ₂ easily cause a value error due to stains and chips of the fluorescent tapes a, b, c and d. Also,
If the area around the standard phosphor 7 of the fluorescent jig 1 can be set, the above formula is not limited.

Further, in the above-mentioned embodiment, the case where one CCD camera 4 for picking up an image of one surface of the fluorescent jig is provided is explained. However, in an actual magnetic particle flaw detector, a plurality of CCD cameras are to be inspected. The material may be imaged from various directions, each surface of the fluorescent jig may be imaged by an imaging device that images each surface of the material to be inspected, and the magnetic particle flaw detection function may be verified for each surface.

Further, in the above-described embodiment, the automatic flaw detection inspection apparatus for flaw detection while the material to be inspected is conveyed is explained, but the present invention is not limited to this, and any magnetic flaw detection apparatus for performing image processing can be applied. .

[0027]

As described above, in the present invention, the inspection of the magnetic particle flaw detection function is carried out in real time by imaging the fluorescent jig provided with the phosphor having the known brightness in the flaw detection inspection of the material to be inspected. Therefore, the present invention has excellent effects such as highly accurate magnetic particle flaw detection inspection.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a verification device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a structure of a fluorescent jig used for carrying out the method of the present invention.

FIG. 3 is a flowchart showing an implementation procedure of an image processing unit of the present embodiment.

FIG. 4 is a plan view showing a binarized image according to the present embodiment on coordinates.

FIG. 5 is a luminance histogram of a video signal of this embodiment.

[Explanation of symbols]

1 Fluorescent jig 2 rollers 3 UV light 4 CCD camera 6 Image processing unit 7 Standard phosphor 9 Central area 61 Binarization means 65 Average brightness measuring means 66 Half-width measurement means a, b, c, d fluorescent tape

Front page continuation (72) Inventor Shuji Matsumoto 4-53-3 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (56) Reference JP-A-2-228542 (JP, A) -145354 (JP, U) Actual development Sho 61-163916 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 27/72-27/90 G01N 21/91

Claims (6)

(57) [Claims] 1. A method for detecting fluorescence from fluorescent magnetic powder adhered to the surface of a material to be inspected by an image pickup means, and testing the function of performing magnetic particle flaw detection of the material to be inspected based on the obtained signal. , A process of capturing an image of fluorescence from a fluorescent jig provided with a phosphor having a predetermined fluorescence intensity used for the magnetic particle flaw detection by the image pickup means, and an area centered on the phosphor from the signal obtained by the image pickup means a process of setting a to the area
Then, the method comprises the steps of creating a luminance histogram having the gradation on the horizontal axis and the frequency on the vertical axis, the step of measuring the average luminance of the area from the luminance histogram, and the step of testing the function by the average luminance. A test method for the magnetic particle flaw detection function, which is characterized in that 2. A method for testing the function of performing magnetic particle flaw detection on a material to be inspected on the basis of the signal obtained by imaging the fluorescence from the fluorescent magnetic powder adhered to the surface of the material to be inspected with an imaging means. , A process of capturing an image of fluorescence from a fluorescent jig provided with a phosphor having a predetermined fluorescence intensity used for the magnetic particle flaw detection by the image pickup means, and an area centered on the phosphor from the signal obtained by the image pickup means a process of setting a to the area
Then, a step of creating a luminance histogram in which the horizontal axis is gradation and the vertical axis is frequency, a step of measuring an average luminance of the area from the luminance histogram, a step of measuring a half width of the luminance histogram, And a step of testing the function based on the average brightness and the half width. 3. A magnetic particle flaw detection function verification device for testing a magnetic particle flaw detection function using a fluorescent jig provided with a phosphor having a predetermined fluorescence brightness used for magnetic particle flaw detection, wherein the fluorescent material is imaged. An image pickup device, a freezer for generating a still image from a video signal from the image pickup device, a binarizing means for converting the still image obtained by the freezer into a binarized image, and the binarized image in the X direction. X to project
Direction projection means, Y direction projection means for projecting the binarized image in the Y direction, center for setting a central area centered on the phosphor based on the results of the X direction projection and the Y direction projection With respect to the area setting means and the central area , a luminance hist where the horizontal axis is gradation and the vertical axis is frequency.
Create a chromatogram, and the average luminance measurement means for measuring the average luminance of the <br/> central area based on the luminance histogram,
A gain correction unit that determines whether or not the average brightness is within a predetermined allowable range, and the gain correction unit adjusts the gain from the imaging device to the binarization unit when the average brightness is outside the allowable range. An inspection device for a magnetic particle flaw detection function, which is configured to perform correction or to notify that the average luminance is out of an allowable range. 4. A magnetic particle flaw detection function verification device for testing a magnetic particle flaw detection function using a fluorescent jig provided with a phosphor having a predetermined fluorescence brightness used for magnetic particle flaw detection, wherein the fluorescent material is imaged. An image pickup device, a freezer for generating a still image from a video signal from the image pickup device, a binarizing means for converting the still image obtained by the freezer into a binarized image, and the binarized image in the X direction. X to project
Direction projection means, Y direction projection means for projecting the binarized image in the Y direction, center for setting a central area centered on the phosphor based on the results of the X direction projection and the Y direction projection With respect to the area setting means and the central area , a luminance hist where the horizontal axis is gradation and the vertical axis is frequency.
Create a chromatogram, and the average luminance measurement means for measuring the average luminance of the <br/> central area based on the luminance histogram,
A full width at half maximum measuring unit for measuring the full width at half maximum of the luminance histogram, and a gain correction unit for determining whether or not the average luminance and the full width at half maximum are within a predetermined allowable range, wherein the gain correction unit is the average luminance and half When the value range is out of the allowable range, the gain from the image pickup device to the binarizing means is corrected, or the notification that the average brightness and the half-value width are out of the allowable range is performed. Inspection device for magnetic particle flaw detection function. 5. The magnetic particle flaw detection function according to claim 3 or 4.
Magnetic particle flaw detector equipped with a verification device. 6. A fluorescent jig used for testing the function of magnetic particle flaw detection.
And has a predetermined fluorescent brightness used for the magnetic particle flaw detection.
And a phosphor for identifying the position of the phosphor
And a fluorescent tape attached around the periphery of the
Characteristic fluorescent jig.