Magnetic particle liquid for magnetic particle testing and magnetic particle testing method

Abstract

To provide magnetic powder liquid for a magnetic powder flaw detection test which is the magnetic powder liquid having the combination of different colors of the magnetic powder and the dispersion liquid for dispersing the magnetic powder and can detect a defective portion by calculating a ratio of a component of a color of the magnetic powder included in a color tone of an indication pattern to a component of a color of the dispersion liquid with image processing, determining as a defective indication pattern the indication pattern in which the ratio of the component of the color of the magnetic powder is increased in comparison to the ratio of the component of each color included in the color tone of the magnetic powder liquid and removing noise due to a liquid reservoir, and a magnetic powder flaw detection testing method.SOLUTION: There is provided magnetic powder liquid for a magnetic powder flaw detection test having the combination of different colors of the magnetic powder and the dispersion liquid for dispersing the magnetic powder (however, excluding the color of water that is not colored).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a magnetic particle liquid for magnetic particle testing and a magnetic particle testing method, and more particularly to a magnetic particle liquid in which the magnetic particles and the dispersion liquid in which the magnetic particles are dispersed have different colors, and relates to a magnetic particle liquid and a magnetic particle testing method that make it easy to distinguish between defects and liquid pools. [Background technology]

[0002] Magnetic particle testing is a flaw detection testing method that applies a magnetic field to the object being inspected, generating magnetic poles in areas with defects such as cracks, attaching colored iron powder (hereinafter referred to as "magnetic powder") to the magnetic poles, and detecting defects by observing the magnetic powder attached to the defective areas.

[0003] However, in actual magnetic particle testing, magnetic particles may remain in areas other than the magnetic pole generating area.

[0004] The area where the magnetic particles remain is called a "liquid puddle." Because the presence of a "liquid puddle" reduces the contrast between the defect indication area and other areas, a back-cleaning method such as immersion in water is used.

[0005] However, this method has the drawback of increasing equipment costs and reducing detection power.

[0006] If defect detection is performed by image processing while the "liquid puddle" remains, the brightness of the background increases, making it difficult to set a threshold for determining whether or not there is a defect.

[0007] Furthermore, because the liquid pools are not uniform across the entire test object, it is necessary to apply a blur filter or the like to the image to determine the brightness change across the entire test image, and then correct the brightness depending on the location or change the threshold depending on the location, which results in poor work efficiency.

[0008] Furthermore, it is difficult to remove locally adhered liquid by the above-mentioned correction, and there is a risk that even areas that are not defective may be detected as defective, resulting in a decrease in defect detection accuracy.

[0009] Furthermore, if the liquid pool contains air bubbles, the air bubbles may be erroneously detected as a defect, further reducing the accuracy of defect detection.

[0010] Therefore, there is a need to develop a magnetic particle liquid that can easily determine whether it is a defect or a liquid pool. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent Publication No. 2000-11528 Summary of the Invention [Problem to be solved by the invention]

[0012] Patent Document 1 describes a method for separating defects from noise components by attaching fluorescent magnetic particles to the surface of a magnetized piece of steel, capturing an image of the fluorescence emitted by the fluorescent magnetic particles attached to the piece of steel, generating a differential image of the captured image, extracting defect candidate areas from the differential image, and identifying defects from the defect candidate areas based on the size and shape of the areas that appear in a binarized image of the captured image.

[0013] However, although the method described in Patent Document 1 can separate defects from noise caused by liquid pools, it has the problem of requiring many steps and being time-consuming.

[0014] The inventors set out to solve the above-mentioned problems as a technical task, and as a result of numerous trial and error prototypes and experiments, they discovered that if the magnetic powder liquid has a combination of different colors, the ratio of the magnetic powder color components and the dispersion liquid color components contained in the hue of the indication pattern can be calculated using image processing to calculate the ratio of the magnetic powder color components to the dispersion liquid color components, and indication patterns in which the ratio of the magnetic powder color components is increased compared to the ratio of each color component of the magnetic powder liquid can be identified as defect indication patterns, thereby removing noise caused by liquid puddles and detecting defects, and thereby achieving the above-mentioned technical task. [Means for solving the problem]

[0015] The present invention is a magnetic particle liquid for magnetic particle testing in which the color of the magnetic particles and the color of the dispersion liquid in which the magnetic particles are dispersed (excluding the color of uncolored water) are different colors.

[0016] The present invention also relates to the magnetic particle liquid for magnetic particle testing, wherein the color combination is a two-color combination of one color and another color that is at an angle of 45° or more and 315° or less from the first color on the color wheel.

[0017] The present invention also relates to the magnetic particle liquid for magnetic particle testing, wherein the color combination is a combination of two colors selected from red, green, and blue.

[0018] The present invention also provides a magnetic particle testing method using the magnetic particle liquid for magnetic particle testing.

[0019] The present invention also provides a magnetic particle testing method for detecting defects by calculating the ratio of the color components of the magnetic particles contained in the hue of the indication pattern to the color components of the dispersion liquid. [Effects of the Invention]

[0020] In this specification, the term "indication pattern" refers to a part that has developed a color and exhibited a pattern, and is used to include not only defect indication patterns but also parts that have developed a color and exhibited a pattern due to liquid pooling or other causes.

[0021] Since the present invention uses a magnetic powder liquid in which the color of the magnetic powder and the color of the dispersion liquid in which the magnetic powder is dispersed are different colors, image processing is used to calculate the ratio of the color components of the magnetic powder contained in the hue of the indication pattern and the ratio of the color components of the dispersion liquid, and indication patterns in which the ratio of the color components of the magnetic powder is higher than the color components of each color contained in the hue of the magnetic powder liquid are identified as defect indication patterns.This is a magnetic powder liquid with high detection accuracy that can remove noise caused by liquid pools and detect defects.

[0022] Furthermore, by using a combination of two colors, the color of the magnetic powder and the color of the dispersion liquid, such as a combination of one color and another color that is at an angle of 45° or more and 315° or less on the color wheel to the first color, or a combination of two colors selected from red, green, and blue, it becomes easier to separate the colors using image processing, making it possible to determine with even greater accuracy whether the pattern is a defect indication pattern or noise caused by a liquid puddle. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a grayscale image of an example and a comparative example. [Figure 2] 10 shows images in which red and green components are extracted in the embodiment. [Figure 3] 10 is an image in which the red component and the green component are extracted, respectively, in a comparative example. [Figure 4] 10 is an image showing defects, pools of liquid, and bubbles. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention provides a magnetic particle liquid in which the magnetic particles and the dispersion liquid in which the magnetic particles are dispersed have different colors.

[0025] In the present invention, "different colors" means that the colors are different at least under the observation conditions when defects are detected in a magnetic particle inspection test.

[0026] Furthermore, the color and hue in the present invention may be a color and hue under visible light, or a color and hue due to fluorescence induced by invisible light such as ultraviolet light.

[0027] Furthermore, the color wheel in the present invention is not particularly limited, and any color wheel may be used.

[0028] It should be noted that the "combination of different colors" in the present invention does not include combinations with the color of uncolored water.

[0029] The magnetic powder liquid is usually managed so that the magnetic particles are uniformly dispersed in the dispersion liquid, and therefore the color of the magnetic particles and the color of the dispersion liquid are uniformly distributed to produce a hue.

[0030] In the magnetic pole generating area, the magnetic particles are attracted to the magnetic pole, whereas the dispersion liquid is not directly affected by the magnetic pole. Therefore, in the magnetic pole generating area caused by the defect, the magnetic particles are concentrated compared to normal magnetic particle liquid, and the color of the magnetic particles becomes darker than the hue of the magnetic particle liquid.

[0031] Therefore, the ratio of the color component of the magnetic particles increases in the defective portion compared to the normal magnetic particle liquid.

[0032] If the color of the magnetic powder and the color of the dispersion liquid are a color combination that can be separated by image processing, it is possible to determine whether the indication pattern obtained by magnetic particle testing is a defect indication pattern formed in the defective area or noise caused by a liquid pool based on the respective ratios of the color components of the magnetic powder and the color components of the dispersion liquid contained in the hue of the indication pattern obtained by magnetic particle testing, and a more appropriate threshold value can be set than in the past.

[0033] It is preferable that the colors of the magnetic powder and the dispersion liquid are easily separable from each other in the color space used.

[0034] An easily separable color is, for example, a combination of colors that are not similar hues on the color wheel.

[0035] A color combination that is not an analogous hue color combination is preferably a color combination in which one color and the other color are separated by an angle of 45° or more and 315° or less on the pigment wheel.

[0036] When using an RGB image, you can select two colors for the magnetic particles and two colors for the dispersion liquid from red, green, and blue.

[0037] This is because it is easy to separate from a color image by image processing.

[0038] For example, magnetic particles that emit green fluorescence when irradiated with ultraviolet light may be dispersed in a dispersion liquid that emits red or blue light when irradiated with ultraviolet light.

[0039] The ratio of magnetic particles to dispersion in the magnetic particle liquid of the present invention is preferably a concentration at which the dispersion emits fluorescence to the same extent as the magnetic particles.

[0040] For example, it can be prepared by dispersing 0.3 g to 1.5 g / L of magnetic powder and 0.28 g / L to 1.0 g / L of red phosphor in 1 L of dispersion liquid.

[0041] The magnetic powder liquid according to the present invention may contain a dispersant.

[0042] The image editing software used in the present invention may be any known image editing software, such as GIMP or Photoshop (registered trademark). [Example]

[0043] The present invention will be explained in more detail with reference to examples and comparative examples, but the present invention is not limited thereto.

[0044] A fluorescent pigment that emits red light under ultraviolet irradiation (SINLOIHI COLOR FZ-6037 Pink / Shinloihi Co., Ltd.) was mixed with 500 mL of water at a ratio of 0.5 g to prepare a dispersion at a concentration of 1 g / L.

[0045] As an example, a magnetic powder liquid was prepared by mixing fluorescent magnetic powder LY-30 (manufactured by Marktec Co., Ltd.) liquid and the prepared dispersion liquid at a ratio of 1:1.

[0046] As comparative examples, fluorescent magnetic powder LY-30 (manufactured by Marktec Co., Ltd.) solution and magnetic powder solution with a concentration of 1 g / L in uncolored water were used.

[0047] The fluorescent magnetic powder LY-30 emits green light under ultraviolet light.

[0048] The specimen used was a test piece having a simulated defect simulating a gear with a slit formed therein.

[0049] The specimen was magnetized by the axial current method, and the test liquid was applied by the continuous method to perform magnetic particle testing.

[0050] After the flaw detection test, the specimen was photographed using a color CMOS (Complementary Metal Oxide Semiconductor) camera sensitive to RGB.

[0051] (Image Processing) Image processing was performed using image editing software according to the following steps (1) to (4). (1) Open the image you obtained (2) Select the target area using the selection tool (3) Use the histogram dialog to obtain the average brightness (8-bit pixel value) of the red component from the area selected in (2). (4) Use the histogram dialog to obtain the average luminance (8-bit pixel value) of the green component from the area selected in (2).

[0052] Figure 1 shows a color image of the test piece taken after the flaw detection test, which was then converted to grayscale.

[0053] Figure 2 shows a color image of the test object after the flaw detection test in this example, with the green and red components extracted.

[0054] Figure 3 shows a color image of the test object after the flaw detection test in the comparative example, with the green and red components extracted.

[0055] Tables 1 and 2 show the 8-bit pixel values ​​of the red and green components of each simulated defect, puddle, and bubble (FIG. 4) in the example and comparative example.

[0056] [Table 1]

[0057] [Table 2]

[0058] In the case of the magnetic powder liquid of the embodiment, defective areas where magnetic poles occur have higher values ​​for the green component than for the red component, while puddles and bubble areas where no magnetic poles occur have almost the same values ​​for the red and green components, proving that it is possible to distinguish between defect indication patterns and noise caused by puddles and to remove the noise. [Industrial Applicability]

[0059] Since the present invention uses a magnetic particle liquid in which the color of the magnetic powder and the color of the dispersion liquid in which the magnetic powder is dispersed are different colors, the color of the magnetic powder in defective areas where magnetic poles are generated is darker than the hue of the magnetic particle liquid, compared to puddles where no magnetic poles are generated.Therefore, by using image processing to calculate the ratio of the color components of the magnetic powder and the color components of the dispersion liquid contained in the hue of the indication pattern, and by distinguishing indication patterns in which the ratio of the color component of the magnetic powder is increased compared to the ratio of each color component of the magnetic particle liquid, as defect indication patterns, it is possible to separate out the noise caused by puddles and detect defective areas, resulting in a magnetic particle liquid and magnetic particle inspection method that allows for highly accurate magnetic particle inspection testing in a simple manner. Therefore, the present invention has high industrial applicability.

Claims

1. A magnetic particle liquid for magnetic particle inspection testing, in which the color of the magnetic particle and the color of the dispersion liquid in which the magnetic particle is dispersed (excluding the color of uncolored water) are different colors, and the color combination is a combination of two colors, one color and another color that is at an angle of 45° or more and 315° or less from the first color on the color wheel.

2. 2. The magnetic particle liquid for magnetic particle testing according to claim 1, wherein the color combination is a combination of two colors selected from the group consisting of red, green, and blue.

3. A magnetic particle testing method using the magnetic particle liquid for magnetic particle testing according to claim 1 or 2.

4. 4. A magnetic particle testing method according to claim 3, wherein defects are detected by calculating the ratio of the color components of the magnetic particles contained in the hue of the indication pattern to the color components of the dispersion liquid.

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