WO2022202198A1

WO2022202198A1 - Evaluation method and evaluation device for surface roughening of metal surface

Info

Publication number: WO2022202198A1
Application number: PCT/JP2022/009211
Authority: WO
Inventors: 紀昭篠原; 右京樋口; 慎剛中原; 和弘木村
Original assignee: ジャパンマリンユナイテッド株式会社
Priority date: 2021-03-25
Filing date: 2022-03-03
Publication date: 2022-09-29
Also published as: JP7370355B2; CN117098972A; KR20230127343A; JP2022149261A

Abstract

The present invention executes: a step S2 for acquiring image data of a surface of a testing sample which has been subjected to surface roughening; a step S7 for calculating an NDSI value of each pixel of the image data with respect to light of two wavelengths pre-selected on the basis of the image data; and steps S8-S12 for performing evaluation with respect to the surface roughening of the testing sample on the basis of the NDSI values.

Description

Evaluation method and evaluation device for roughening of metal surface

The present disclosure relates to a method for evaluating surface roughening applied to the surface of metal such as steel, and an evaluation apparatus capable of executing this.

For the surface of metals such as steel materials, rough surface treatment such as shot blasting is sometimes performed for the purpose of removing rust and improving the bite of paint. In ships, in particular, it is obligatory to roughen the surface of the steel materials that make up the hull, depending on the target location. For example, a light surface roughening process called sweep blasting is applied to areas where the antirust paint film is in good condition, and a stronger surface roughening process is required for areas where the coating is not sound. An inspector conducts an on-site inspection to determine whether or not the surface of the steel material subjected to such treatment satisfies predetermined requirements such as roughness, degree of rust removal, and degree of cleanliness. However, most of such witnessed inspections are subjectively evaluated by inspectors visually. Therefore, the evaluation depends on the skill and experience of the inspector, and the results are likely to vary.

In order to suppress the variation in evaluation due to such evaluation methods, there are methods such as preparing photographs of metal surfaces with different levels of roughening treatment as a reference and comparing them with the actual object for evaluation. has been adopted. However, the optical conditions at the inspection sites vary, and the metal subject to inspection may show discoloration over time. Have difficulty.

Therefore, various devices and methods for objectively measuring the degree of roughening treatment on a metal surface have been invented and put into practical use (for example, see Patent Documents 1 and 2 below).

JP 2019-158820 A JP 2019-168353 A

However, when the techniques described in Patent Documents 1 and 2 are used, even if the surface roughness can be evaluated, the degree of rust removal and cleanliness cannot be evaluated. cannot be substituted. Various other optical techniques and methods have been developed as techniques for evaluating the roughening of metal surfaces, but they all have weaknesses, such as the extremely narrow range that can be evaluated at once. Therefore, it cannot be said that they are practically sufficient as evaluation techniques for surface roughening treatment.

Therefore, in the present disclosure, in view of such circumstances, an evaluation method and evaluation apparatus for metal surface roughening that can easily and suitably evaluate metal surface roughening will be described.

The present disclosure relates to acquiring image data of a roughened surface of an object to be inspected, and based on said image data, for light of two preselected wavelengths, the NDSI value at each pixel of said image data and a step of evaluating the roughening of an object to be inspected based on the NDSI value.

In the method for evaluating the roughening treatment of the metal surface described above, the wavelength of light used for calculating the NDSI value can be selected based on the following conditions.
Condition 1) The magnitude of reflectance is positively correlated with the magnitude of surface roughness.
Condition 2) In addition to satisfying condition 1, one of the two wavelengths of reflected light should have as little variation in reflectance as possible due to the surface roughness of the object to be inspected, and the other should have as large a variation as possible.

In the method for evaluating the roughening of the metal surface described above, the average value of the NDSI values of the target pixels in the acquired image data is calculated, and the surface roughness is evaluated based on the average value. can.

In the method for evaluating the roughening of the metal surface described above, the NDSI value of each target pixel in the acquired image data can be referred to as a preset threshold to evaluate rusting.

In the method for evaluating surface roughening of a metal surface described above, a range to be evaluated can be selected in the acquired image data, and evaluation of surface roughening can be performed within the selected range.

Further, the present disclosure includes an image creation unit that creates image data based on at least the two wavelengths of light selected in advance, and an analysis unit that performs NDSI analysis based on the image data. The present invention relates to an evaluation apparatus for roughening of a metal surface, which is configured to be capable of executing an evaluation method for surface treatment.

According to the method and apparatus for evaluating the roughening treatment of a metal surface of the present invention, it is possible to obtain an excellent effect of easily and suitably evaluating the roughening treatment of a metal surface.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an example of the configuration of a metal surface roughening evaluation apparatus according to an embodiment of the present disclosure; 4 is a graph showing the relationship between the wavelength of light and the reflectance on the surface of a steel material subjected to surface-roughening treatment. 3 is a graph showing each reflectance at each wavelength in FIG. 2 normalized with respect to the reflectance at a specific wavelength; 5 is a graph showing an example of the relationship between calculated NDSI values and surface roughness; 4 is a flow chart illustrating an example of a procedure of a method for evaluating roughening of a metal surface according to an embodiment of the present disclosure; FIG. 4 is a diagram showing an example of a screen displayed on a display unit in an embodiment of the present disclosure, showing a state in which an image of a measurement target using visible light and a selection range thereof are displayed; FIG. 10 is a diagram showing another example of a screen displayed on the display unit in the embodiment of the present disclosure, showing a state in which an image in which the selection range is color-coded according to the NDSI value is displayed. FIG. 10 is a diagram illustrating another example of a screen displayed on the display unit in the embodiment of the present disclosure, and illustrates a state in which an image in which the selection range is binarized according to the NDSI value is displayed;

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

FIG. 1 shows an example of the configuration of a metal surface roughening evaluation apparatus according to an embodiment of the present disclosure. The evaluation device 1 includes an irradiation unit 2 that irradiates light for inspection, an imaging unit 3 that acquires image data of an object to be inspected, a display unit 4 that displays various visual information, the irradiation unit 2 and the imaging unit 3. , and a display unit 4, and a power supply unit 6 for supplying power to these units.

The irradiation unit 2 is, for example, an LED lighting device, and is designed to irradiate the inspection object with light for inspection. The light emitted by the irradiation unit 2 needs to include at least light of wavelengths corresponding to the two wavelengths of reflected light described later. Here, "light of a wavelength corresponding to reflected light of a certain wavelength (λ nm)" refers to "light of a wavelength that, when the light is incident on an object to be inspected, gives reflected light of a wavelength of λ nm". If the object to be inspected is illuminated by another light source, and the image acquisition and inspection procedures, which will be described later, can be executed without hindrance, the irradiation unit 2 as a component of the evaluation apparatus 1 is not necessarily required. .

The imaging unit 3 includes a light receiving unit 7, an image creating unit 8, and an analyzing unit 9. The light receiving unit 7 receives reflected light from the surface of the inspection object, and the image creation unit 8 creates image data of the surface of the inspection object based on the light received by the light receiving unit 7 . The analysis unit 9 performs analysis, which will be described later, based on the image data created by the image creation unit 8 .

The light receiving unit 7 must be able to detect at least two wavelengths of reflected light, which will be described later. In addition, it is preferable that the light receiving section 7 can detect visible light, and it is particularly preferable that the three primary colors of RGB can be detected. For example, a hyperspectral camera can be used as the imaging unit 3 having such a light receiving unit 7. However, if the imaging unit 3 is a device capable of detecting light including the above two wavelengths, it can be used for the analysis and inspection described later. The device may be sufficient and detectable in a narrower wavelength range of light than a typical hyperspectral camera.

The display unit 4 is a display that displays visual information such as images acquired by the imaging unit 3, images processed by the analysis unit 9, and character information indicating the analysis results of the analysis unit 9.

The operation unit 5 is an input device for a user to input operations to each unit such as the irradiation unit 2, the imaging unit 3, and the display unit 4. For example, buttons provided on the main body of the imaging unit 3, or an imaging unit. It is a touch panel display or the like connected to the main body of the unit 3 . When the operation unit 5 is configured as a touch panel display, the operation unit 5 can also function as the display unit 4 .

The power supply unit 6 is, for example, a battery box that houses a rechargeable battery, and supplies power to the irradiation unit 2, the imaging unit 3, the display unit 4, and the operation unit 5. In addition, when the devices corresponding to the irradiation unit 2, the display unit 4, etc. are each provided with a power supply device such as a rechargeable battery, it is not necessary to supply power from the power supply unit 6 to these devices (for example, the display unit 4 and the display unit 4). When the operation unit 5 is configured as a touch panel type display, the touch panel type display usually comes with a power supply device as standard equipment).

A mechanism of inspection using the evaluation apparatus 1 will be described. For inspection, a technique called NDSI (Normalized Difference Spectral Index) analysis using reflected light of two wavelengths, tilt analysis, or the like is used. The NDSI analysis is a method of detecting light of two specific wavelengths out of the light obtained from the surface of the inspection target and grasping the properties of the surface of the inspection target from the difference in intensity thereof. It is known that the reflectance of light on a metal surface varies depending on the surface roughness, and the degree of change in reflectance due to the surface roughness also varies depending on the wavelength of the reflected light. Therefore, by detecting two specific wavelengths of light from the reflected light from the surface of the inspection object and comparing their reflectances, the surface roughness can be grasped from the magnitude thereof. Specifically, the surface of the object to be inspected is irradiated with light, reflected light with two wavelengths λ1 and λ2 is detected from the reflected light, and the respective reflection intensities are calculated. Then, the difference between the two is used as a relative value and the size is evaluated according to the following formula. In the following formula (1), R _λ1 is the reflectance of light with wavelength λ1, and R _λ2 is the reflectance of light with wavelength λ2.
(R _λ1 −R _λ2 )/(R _λ1 +R _λ2 ) (1)

The principle of such NDSI analysis itself is already widely known, but the inventors of the present application have developed a technique for specifying the optimum reflected light wavelength for analyzing the surface roughness of metals, and have further developed a method for surface roughening. In the evaluation of , we have invented a technique that can also evaluate indices other than surface roughness.

First, we will explain how to identify the wavelength of reflected light that is suitable for surface roughness analysis. FIG. 2 is a graph showing the wavelength of reflected light in a steel material and the reflectance of the reflected light at that wavelength. The five curves shown in the figure represent the measurement results of the reflectance of steel materials having different surface roughnesses. The surface roughness of the steel materials corresponding to each curve shown in the figure is the largest for steel material A, and decreases in order of steel material B, steel material C, steel material D, and steel material E. FIG.

As shown here, even for the same inspection object, the intensity of the reflected light differs for each wavelength. In addition, the rate of change in the intensity of reflected light due to wavelength is not uniform regardless of the surface roughness. intensity varies greatly.

Based on this, the reflected light of two wavelengths (λ1, λ2) to be used for inspection is selected. In selecting the wavelength, the following two conditions are important.
Condition 1) The magnitude of reflectance is positively correlated with the magnitude of surface roughness.
Condition 2) In addition to satisfying condition 1, one of the two wavelengths of reflected light should have as little variation in reflectance as possible due to the surface roughness of the object to be inspected, and the other should have as large a variation as possible.

Condition 1 is a condition to ensure the basic accuracy of the inspection. For example, in the graph shown in FIG. 2, the intensity of reflected light at wavelengths p and q is correlated with surface roughness (i.e., the lower the surface roughness, the lower the reflectance, and the higher the surface roughness, the higher the reflectance). high), but for the reflected light of wavelength r, the magnitude of the reflectance is reversed in some regions of surface roughness (focusing on steel materials D and E, the reflectance of reflected light on steel material E with low surface roughness is is higher than the reflectance in steel D, which has a higher surface roughness). Reflected light with a wavelength that causes such a phenomenon does not meet condition 1 and is not suitable for inspection.

Condition 2 is a condition for improving the accuracy of inspection. In the NDSI analysis using the above formula (1), the larger the difference in reflectance between the two wavelengths, the higher the detection sensitivity, which is suitable for evaluating the surface roughness. Here, "the amplitude is as small as possible" and "the amplitude is as large as possible" means that the reflectance due to the surface roughness is "largest" or "smallest" among the wavelengths that meet Condition 1. don't mean Of course, the wavelength at which the reflectance due to the surface roughness is "most" or "least" may be selected here, but is not necessarily limited to those wavelengths. "Of the two wavelengths of reflected light, one is selected so that the fluctuation range of the reflectance due to the surface roughness of the object to be inspected is as small as possible, and the other is selected as large as possible." It refers to selecting two wavelengths so that the difference in amplitude due to surface roughness is large to the extent that it does not hinder the NDSI analysis of . As a guideline, for example, the light of each wavelength is arranged in descending order of the amplitude of the reflectance due to the surface roughness (the difference between the reflectance at the surface roughness with the highest reflectance and the reflectance at the surface roughness with the lowest reflectance). When they are arranged, it is sufficient to set the wavelength selected from the wavelengths positioned within about the upper third to λ1 and the wavelength selected from the wavelengths positioned within the lower one-third to λ2, respectively. . Alternatively, first, light having a wavelength whose reflectance amplitude is located within about the lower one-third is selected as light having a wavelength λ2, and for light having a wavelength λ1, wavelengths having a reflectance amplitude greater than or equal to λ2 are selected. You may select by the method of selecting from light.

An example of a specific selection procedure is described below. First, in FIG. 2, the reflected light of wavelength q that satisfies condition 1 and has the smallest possible fluctuation of reflectance due to surface roughness is selected as one reflected light (reflected light of wavelength λ2) used for inspection.

Next, the reflectance of light of wavelength λ2 in each inspection object is used as a reference, and the reflectance of light of other wavelengths is normalized. If the graph of FIG. 2 is redrawn based on this normalized reflectance, it will become like FIG. In the graph of FIG. 3, the other wavelength (wavelength λ1) that meets the conditions 1 and 2 is selected. The condition that the magnitude of the surface roughness and the magnitude of the reflectance are positively correlated and that the fluctuation range of the reflectance due to the surface roughness is as large as possible corresponds to, for example, the reflected light of the wavelength p. The light is selected as the other reflected light (reflected light with wavelength λ1) used for inspection.

When the object to be inspected is steel, it is particularly suitable for inspection to select light with a wavelength of about 620 nm or more and 700 nm or less as the light with the wavelength λ1 and light with a wavelength of about 450 nm or more and 520 nm or less as the light with the wavelength λ2. , these wavelengths well meet the above conditions 1 and 2). However, this figure can of course vary depending on the type of metal that constitutes the object to be inspected. When the evaluation method of the present invention is applied to metals other than iron, light of two wavelengths (wavelengths λ1 and λ2) used for inspection may be specified by the same technique as described above. Further, even if the object to be inspected is a steel material, the wavelengths of light suitable for the light of wavelengths λ1 and λ2 may differ from the above numerical values depending on the test method and the like. It should be noted that the numerical values illustrated above are only examples.

When inspecting the surface roughness of an object to be inspected using the evaluation apparatus 1 as shown in FIG. Get image data. That is, the image data is created by the image creating section 8 from the light received by the light receiving section 7 . The image data acquired here is, for example, an image of the surface of the object to be inspected photographed in a range of several cm×several cm to 1 m×1 m. The analysis unit 9 selects an appropriate range of the image data (a part of the obtained image may be selected as an inspection target, or the entire image data may be selected). Calculate the NDSI value using equation (1) above based on the intensity of light at wavelengths λ1 and λ2 for each pixel in the pixel. By calculating the average value of the NDSI values obtained for each pixel, it can be evaluated as a value indicating the surface roughness.

Fig. 4 shows an example of the actual relationship between the NDSI value thus calculated and the surface roughness of the steel material. The horizontal axis is the surface roughness measured using a roughness meter for various steel materials subjected to different degrees of surface roughening, and the vertical axis is the NDSI value calculated by the above method for each steel material. As shown here, both values show a strong correlation (number of samples n=24, correlation coefficient r=0.958), and the NDSI value is useful as an index of surface roughness.

In addition, the same NDSI value can be used to evaluate not only surface roughness but also rust removal. The NDSI value based on the reflected light on the metal surface fluctuates according to the surface roughness as described above, but it is also affected by the degree of rust removal. This has been clarified by the research of the inventor of the present application. For example, in steel materials, when calculating the NDSI value by the above formula (1) based on the light of the wavelength determined by the above method (620 nm ≤ λ1 ≤ 700 nm, 450 nm ≤ λ2 ≤ 520 nm), the area with rust (rusted part) , the NDSI value shows a generally constant value (a specific value varies depending on the measurement environment and the like, but is about 60, for example). Therefore, if the NDSI value is 60 or more, it can be determined that rust exists in that portion. That is, for example, if the image data obtained by the evaluation device 1 includes an area having an NDSI value of 60 or more, it can be determined that the area is a rusted portion. Then, the ratio of pixels whose NDSI value is less than 60 can be grasped as the degree of rust removal.

The inspection procedure using the evaluation device 1 (see FIG. 1) as described above can be represented, for example, by the flowchart shown in FIG.

Prior to the inspection, white board data for correction is acquired in the imaging unit 3, and the light intensity used for calculating the NDSI value is set (step S1). Each value (R _λ1 and R _λ2 ) used for calculating the NDSI value represented by the above formula (1) is a reflectance, that is, a relative value. I use it. That is, in a certain pixel of an image acquired in a later step, the value obtained by dividing the intensity of light of a certain wavelength by the intensity of light of the same wavelength in the white board data acquired in step S1 is the value of that wavelength at that pixel. is the reflectance of light. It should be noted that it is sufficient to perform this step S1 only once for each site unless the optical conditions differ greatly.

The surface of the object to be inspected is irradiated with light from the irradiation unit 2, and image data of the surface of the object to be inspected is acquired (step S2). Here, image data is created for light of at least the two wavelengths, but in addition to this, image data may be created for light of other wavelengths, for example, wavelengths corresponding to RGB.

The brightness of the acquired image data is corrected (step S3), and the light intensity data of each wavelength acquired for each pixel is smoothed using a Gaussian filter or the like (step S4).

The image data is displayed on the display unit 4 (step S5). When the image data of the light of the wavelength corresponding to RGB is created in step S2, in this step S5, as shown in FIG.

The user of the evaluation device 1 selects an area to be subjected to evaluation of the roughening process from the image displayed on the display unit 4 (step S6). An example of the selection range at this time is indicated by a rectangle in FIG. In the case of the example shown here, the portion of the displayed image that captures the appearance of the surface that can be used for inspection is the central region, so this region is selected. The subsequent step of evaluating the surface roughening treatment is performed within the range selected here.

Note that this step S6 is a process that is executed, for example, when there is a portion that should not be used for inspection, such as a foreign substance, in the image acquired in step S2, and may be omitted if not necessary. Further, when selecting the region in step S6, the selection may be automatically performed by the evaluation device 1 without depending on the user's operation. In that case, for example, a certain area to be selected from the image displayed on the display unit 4 may be stored in advance, and the stored area may be set to be selected as an evaluation target for each image. . Alternatively, it may be set so that the entire area of the displayed image is automatically selected as the evaluation target.

For each pixel included in the selected area, the reflectance of light of the above two wavelengths is calculated, and the NDSI value (see formula (1) above) is calculated (step S7).

Subsequently, based on the NDSI value calculated for each pixel, the surface roughness, blasting rate, area of the rusted portion, degree of rust removal, and other evaluations of the surface roughening of the inspection object are performed. make a final assessment of the quality of Steps S8 and S9 are steps for obtaining the surface roughness and the blast rate, and steps S10 and S11 are steps for obtaining the area of the rusted portion and the degree of rust removal.

In step S8, the average value of the NDSI values of each pixel obtained in step S7 is calculated. Based on this average value, the surface roughness and the blast rate are calculated from the relationship between the NDSI value and the surface roughness (see FIG. 4) previously obtained by experiment (step S9). Here, the blast rate is the ratio of the area in which the appropriate anchor pattern is formed on the target surface by surface roughening, and correlates with the surface roughness. The surface roughness can be obtained from FIG. 4 based on the NDSI value, but since the surface roughness and the blast rate are correlated, the blast rate can also be obtained based on the surface roughness obtained from FIG.

In steps S10 and S11, the NDSI value of each target pixel in the acquired image is referred to as a preset threshold to evaluate rusting. First, in step S10, the image data is binarized based on the NDSI value of each pixel obtained in step S7. The threshold value used for binarization is an NDSI value that is suitable for determining a rusted portion and is obtained in advance through experiments. A pixel with an NDSI value equal to or greater than a threshold corresponds to a rusted portion, and the area of the rusted portion and the degree of rust removal can be calculated based on the ratio of pixels with an NDSI value greater than or equal to the threshold (step S11).

In steps S7 to S11, the display unit 4 can appropriately display the image of the object, various numerical values, and the like. For example, after calculating the NDSI value for each pixel in step S7, an image in which each pixel is color-coded according to the magnitude of the NDSI value can be displayed as shown in FIG. Further, the image in which the pixels are color-coded in step S10 can be displayed as an image showing the rusted portion as shown in FIG. The user compares these images with the image shown in FIG. 6, for example, and determines which region of the surface to be inspected shown in the image of FIG. 6 has high (or low) surface roughness and blast rate. Alternatively, it is possible to grasp which region corresponds to the rusted portion. Also, if dirt or the like is attached to the surface of the object to be inspected, its position can be grasped from the image shown in FIG. Also, if an area with an abnormal NDSI value is found in the images shown in FIGS. This can be confirmed by the image shown in FIG.

In addition to the images shown in FIGS. 6 to 8, the display unit 4 displays character information such as various values (for example, the average value of the NDSI values in the selected area and the NDSI values used for detecting rusted portions). Threshold value, surface roughness, blast rate, degree of rust removal calculated based on these values, etc.) can also be displayed as appropriate. Further, when the display unit 4 is a touch panel type display and also functions as the operation unit 5, it is possible to display operation buttons and the like.

The quality of the surface roughening treatment is evaluated from the surface roughness or blast rate obtained in step S9 and the degree of rust removal obtained in step S10 (step S12). The evaluation here is determined in consideration of consistency with various evaluation standards depending on the inspection object, field, site, and the like. In the quality evaluation of sweep blasting of steel materials for ships, for example, if the blast rate is 30% or more and the degree of rust removal is 90% or more, it is considered acceptable (these figures are only examples, and specific The criteria may differ depending on the object or site), and the evaluation is performed based on the blasting rate according to the surface roughness calculated from the NDSI value and the rust removal degree calculated by binarization. It should be noted that the evaluation in step S12 is based on pre-inputted criteria (reference values regarding blast rate, rust removal, etc., set in advance according to the environment in which the device is operated, such as the office and ship owner supervision). This may be performed by the analysis unit 9 of the imaging unit 3, or may be performed by a person based on the results of steps S9 and S11.

The results displayed on the display unit 4 (part or all of the surface roughness, blasting rate, rusted area, degree of rust removal, quality of surface roughening, or other information) are recorded or not shown. It is output as appropriate, such as by printing with a printing machine (step S13), and the inspection ends.

As described above, in the evaluation method and evaluation apparatus of this embodiment, the reflectance of light of two wavelengths previously specified as wavelengths suitable for inspection is used, and the surface roughness and the degree of rust are evaluated by NDSI analysis. . Various techniques for evaluating either surface roughness or rusting have been proposed so far. No analogy. In evaluating the roughening treatment of the metal surface, it is necessary to evaluate both the surface roughness and the degree of rust formation. Visual inspection by an inspector has, of course, satisfied this requirement, but the mechanical evaluation techniques that have been developed to date provide devices or methods for evaluating either surface roughness or rust formation. It was not possible to evaluate both at the same time. According to the present embodiment, it is possible to evaluate both indexes by simple calculation, and to output the evaluation of surface roughening based on them.

In addition, with the evaluation apparatus 1 as described above, it is possible to inspect a range of up to about 1 m x 1 m on the surface of the inspection object at once. This range is equivalent to the range visually evaluated by inspectors. Among conventional devices developed for evaluating the quality of surface roughening, there are devices that can inspect only a very narrow range of the surface to be inspected at one time. If so, a sufficiently wide range can be inspected in a single operation. In addition, evaluation of surface roughness and rust removal can be done with very simple arithmetic processing. It takes only a short time (several seconds at most). Therefore, if the image is acquired, the evaluation of the surface roughening of the inspection object can be confirmed on the spot. As described above, in this embodiment, in addition to the accuracy of evaluation, the evaluation items, the range of evaluation, and the time required for evaluation can fully replace the conventional visual inspection by an inspector.

In addition, since only two specific wavelengths of light are used for evaluation, it is not necessary to use an expensive hyperspectral camera, and the evaluation apparatus 1 as shown in FIG. 1 can be manufactured at low cost. In addition, since the imaging unit 3 and the irradiation unit 2 are operated by a battery-powered power supply unit 6 and do not require a power cable or the like, they can be easily brought into an inspection site such as the inside of a ship's hull structure. , a simple inspection is possible. In addition, since the imaging unit 3 can be configured as a device having the same size as a general camera device, and the display unit 4 and the operation unit 5 can be configured as devices such as a touch panel display, even one person can carry the evaluation device 1 to the site. and can be evaluated with a simple operation.

The evaluation method and evaluation apparatus for the roughening treatment of the metal surface of this embodiment can be used as a technology for performing quantitative evaluation instead of the current visual evaluation, for example, in inspections after blasting work prior to painting in shipbuilding. can do. For example, regarding surface roughening, it can be used as a method of presenting an objective standard when the evaluation of pass or fail differs depending on the person. Alternatively, it can be assumed to be used as a tool for training and education for beginners of painting work. At training and education sites, it is sometimes difficult to prepare inspectors or personnel with equivalent knowledge and experience on a case-by-case basis. It can be used for education.

It should be noted that the configuration of the evaluation device 1 and the procedure of evaluation described above are only examples, and the configuration of the device and the procedure can be changed as appropriate as long as the evaluation can be suitably performed on the same principle. For example, regarding the image creation unit 8 and the analysis unit 9 that constitute the evaluation device 1, the case where an image is created from the light received by the light receiving unit 2 provided in the imaging unit 3 and analyzed has been described above. For example, image data used for inspection may be acquired by the image creating unit 8 from an external device and analyzed by the analysis unit 9 . In this case, it is sufficient for the evaluation device 1 to include at least the image generation section 8 and the analysis section 9 . In addition, for the convenience of explanation, the evaluation process was described above assuming that the evaluation procedure for the surface roughness and the evaluation for the degree of rusting were performed in parallel. good.

As described above, in the evaluation method of the roughening treatment of the metal surface of the present embodiment, the step S2 of acquiring the image data of the surface of the object to be inspected which has undergone the roughening treatment; Step S7 of calculating the NDSI value in each pixel of the image data with respect to the light of the selected two wavelengths, and Steps S8 to S12 of evaluating the rough surface treatment of the inspection object based on the NDSI value. . In this way, an objective evaluation can be performed in place of the conventional visual inspection by an inspector.

In the above embodiment, the wavelength of light used for calculating the NDSI value can be selected based on the following conditions. In this way, accurate and highly accurate evaluation can be performed regarding the roughening treatment of the metal surface.
Condition 1) The magnitude of reflectance is positively correlated with the magnitude of surface roughness.
Condition 2) In addition to satisfying condition 1, one of the two wavelengths of reflected light should have as little variation in reflectance as possible due to the surface roughness of the object to be inspected, and the other should have as large a variation as possible.

In the above embodiment, the average value of the NDSI values of the target pixels in the acquired image data can be calculated, and the surface roughness can be evaluated based on the average value.

In the above embodiment, rusting can be evaluated by referring to the NDSI value of each target pixel in the acquired image data as a preset threshold value.

In the above embodiment, a range to be evaluated can be selected in the acquired image data, and evaluation of surface roughening can be performed within the selected range.

Further, the apparatus 1 for evaluating rough surface treatment of a metal surface of the above embodiment includes an image creating unit 8 for creating image data based on light of at least the two wavelengths selected in advance, and an NDSI analysis based on the image data. and an analysis unit 9 for performing the above-described method for evaluating the roughening of the metal surface. In this way, the above effects can be achieved with a device having a simple configuration.

Therefore, according to the present embodiment, the roughening treatment of the metal surface can be easily and favorably evaluated.

It should be noted that the evaluation method and evaluation apparatus for roughening of a metal surface described in the present disclosure are not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. is of course.

1 evaluation device 2 irradiation unit 3 imaging unit 4 display unit 5 operation unit 6 power supply unit 7 light receiving unit 8 image creation unit 9 analysis unit

Claims

acquiring image data of a roughened surface of the inspection object;
calculating an NDSI value at each pixel of the image data for light of two preselected wavelengths based on the image data;
A method for evaluating roughening of a metal surface, comprising the step of evaluating the roughening of an object to be inspected based on the NDSI value.
2. The method for evaluating roughening of a metal surface according to claim 1, wherein the wavelength of light used for calculating the NDSI value is selected based on the following conditions.
Condition 1) The magnitude of reflectance is positively correlated with the magnitude of surface roughness.
Condition 2) In addition to satisfying condition 1, one of the two wavelengths of reflected light should have as little variation in reflectance as possible due to the surface roughness of the object to be inspected, and the other should have as large a variation as possible.
2. The method of evaluating roughening of a metal surface according to claim 1, wherein an average value of NDSI values of target pixels is calculated in the acquired image data, and the surface roughness is evaluated based on the average value. .
3. The method of evaluating roughening of a metal surface according to claim 2, wherein the average value of the NDSI values of the target pixels in the acquired image data is calculated, and the surface roughness is evaluated based on the average value. .
The rough surface of the metal surface according to any one of claims 1 to 4, wherein the NDSI value of each target pixel in the acquired image data is referred to as a preset threshold value to evaluate rusting. How the treatment is evaluated.
Roughening of a metal surface according to any one of claims 1 to 4, wherein a range to be evaluated is selected in the acquired image data, and evaluation of surface roughening is performed within the selected range. evaluation method.
A method for evaluating roughening of a metal surface according to claim 5, wherein a range to be evaluated is selected in the acquired image data, and the evaluation of surface roughening is performed within the selected range.
an image creation unit that creates image data based on at least the two wavelengths of light selected in advance;
an analysis unit that performs NDSI analysis based on the image data,
3. A metal surface roughening evaluation apparatus configured to be capable of executing the metal surface roughening evaluation method according to claim 1 or 2.