JP4915057B2 - Stainless steel sheet surface inspection method and surface inspection apparatus for stainless steel sheet - Google Patents

Description

  The present invention relates to a stainless steel plate surface inspection method and a stainless steel plate surface inspection device, and more particularly, to a stainless steel plate surface inspection method having a brush pattern with a grinding brush on the surface, and a stainless steel plate that can be suitably used for the method. The present invention relates to a surface inspection apparatus.

Conventionally, as a method for inspecting the surface of a stainless steel plate, for example, techniques described in Patent Documents 1 to 3 are known.
In the technologies described in these patent documents, light for inspection is projected from the light source onto the surface of the stainless steel plate, and the reflected light reflected from the surface of the stainless steel plate is used to so-called the surface of the stainless steel plate. A defect such as a defect is detected.

In particular, in the techniques described in Patent Documents 2 to 3, specular reflection components and irregular reflection components of the reflected light are individually received, and the amount of hege is calculated based on the sum of the components received individually or information obtained by subtraction. Is detected.
JP 60-228943 A Japanese Patent Laid-Open No. 5-188010 JP-A-9-89802

By the way, for example, a stainless steel plate manufactured by annealing is pickled after applying a grinding brush to the steel plate surface for the purpose of removing the scale after annealing. As a result, this type of stainless steel plate has a brush pattern on its surface, and the surface is not smooth, so that the surface formation pattern is a non-uniform steel plate (an example of a brush pattern is shown in FIG. 5). ).
However, the technique described in each of the above patent documents does not assume a steel plate having such a nonuniform surface formation pattern. That is, in the technique described in each of the above patent documents, as the stainless steel plate to which each inspection method is applied, the description is such that “the surface is a mirror surface”, “the surface is a smooth surface”, and “the surface gloss is high”. As such, a steel plate having a smooth surface is assumed. For this reason, when applied to a stainless steel plate having a brush pattern, it is difficult to distinguish between wrinkle defects such as lashes and brush patterns that should be detected, and the brush pattern is overdetected as wrinkle defects. However, this type of stainless steel sheet is still insufficient for application.
Therefore, the present invention has been made paying attention to such problems, and even in a stainless steel plate having a brush pattern, it is possible to suitably distinguish a flaw defect from a brush pattern and detect each of them. It aims at providing the surface inspection method of stainless steel plate, and the surface inspection apparatus for stainless steel plates.

  The present inventors individually receive specular reflection component and irregular reflection component of the reflected light reflected on the surface of the stainless steel plate, and influence of wrinkle defects and brush pattern on the received regular reflection component and irregular reflection component, respectively. As a result of closely observing the correlation with the influence of the effect, the influence on the reflected light due to the presence or absence of wrinkle defects appears strongly in the specular reflection component, as shown in FIG. As shown in FIG. 6A, the influence of the degree on the reflected light is found to appear strongly in the irregular reflection component, and the present invention has been made based on this finding.

That is, in order to solve the above-mentioned problem, the present invention is a method for inspecting the surface of a stainless steel plate having a brush pattern, wherein the direction of the brush pattern and the threading direction are set in the same direction, and the stainless steel Light for inspection is projected on the surface of the steel plate along the plate passing direction, and among the reflected light reflected on the surface of the stainless steel plate, the specular reflection component and the irregular reflection component are along the plate passing direction and the Light is individually received using two CCD cameras at a position opposite to the light projecting position, and the presence or absence of wrinkle defects is detected based on the information on the regular reflection component, and the brush pattern is detected based on the information on the irregular reflection component. It is characterized by discriminating the degree.

Further, the present invention is a surface inspection apparatus for a stainless steel plate for inspecting the surface of a stainless steel plate having a brush pattern, wherein light for inspection is projected along the plate direction on the surface of the stainless steel plate having a brush pattern. Of the reflected light that is projected from the light source and reflected from the surface of the stainless steel plate, the regular reflection component light is received at a position along the plate passing direction and facing the light source. A first CCD camera as a means , and a second CCD camera as a diffuse reflection component light receiving means for receiving diffuse reflection components in the reflected light at a position along the plate passing direction and facing the light source, A defect detection means for detecting the presence or absence of a defect on the basis of information on the regular reflection component received by the regular reflection component light receiving means, and a block based on information on the irregular reflection component received by the irregular reflection component light reception means. It is characterized in that it comprises a brush pattern discriminating means for discriminating the degree of pattern, a.

Here, in the surface inspection apparatus for a stainless steel plate according to the present invention, the specular reflection component information from the specular reflection component light receiving unit and the irregular reflection component information from the irregular reflection component light receiving unit are respectively in the width direction of the stainless steel plate. The gray value obtained by performing gradation processing on the brightness of reflected light, and the wrinkle defect detecting means outputs detection information indicating that there is a wrinkle defect when the gray value of the regular reflection component exceeds a predetermined first threshold value. The brush pattern discriminating means preferably outputs discrimination information indicating that the degree of the brush pattern exceeds the reference value when the gray value of the irregular reflection component exceeds a predetermined second threshold value.
In the surface inspection apparatus for a stainless steel plate of the present invention, it is preferable that the first threshold value is smaller than the second threshold value.

According to the present invention, with respect to wrinkle defects on the surface of the stainless steel plate, the presence or absence of wrinkle defects is detected based on the information of the specular reflection component that strongly affects the surface. On the other hand, for the brush pattern, the degree of the brush pattern is discriminated based on the information of the irregular reflection component that strongly affects the brush pattern. And the regular reflection component and irregular reflection component of the reflected light reflected on the surface of the stainless steel plate have the correlation as described above between the influence of the flaw defect and the influence of the brush pattern. Therefore, according to the present invention, even if the surface of the steel sheet has a brush pattern, the surface is not smooth, and the surface formation pattern is non-uniform, so-called wrinkle defects such as bald defects. And a brush pattern can be distinguished and each can be detected suitably.
The reason why the correlation as described above occurs is considered as follows.
That is, since the light is irregularly reflected by the brush pattern, the diffuse reflection side is easily affected by the brush pattern. On the other hand, on the regular reflection side, the influence of the brush pattern is small, and it is considered that the influence of wrinkle defects such as baldness is easy to detect.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a stainless steel plate which has a brush pattern, the surface inspection method and stainless steel plate surface inspection apparatus for a stainless steel plate which can distinguish between a beard and a brush pattern suitably, and can detect each are provided. can do.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate.
FIG. 1 is an explanatory diagram showing a schematic configuration of an embodiment of a surface inspection apparatus for a stainless steel plate (hereinafter also simply referred to as “surface inspection apparatus”) according to the present invention.
As shown in the figure, this surface inspection apparatus 10 inspects the surface of a stainless steel plate 100 having a brush pattern 90, and includes a light source 1, a regular reflection camera 2, a diffuse reflection camera 3, and a processing apparatus 4. , And is configured.

  The light source 1 is arrange | positioned in the position which can project the light 80 for a test | inspection on the surface of the stainless steel plate 100 which has the brush pattern 90, as shown in the figure (b). That is, the inspection light 80 from the light source 1 can be widely projected to both sides in the width direction W of the steel plate toward the reference line DL to be detected by the stainless steel plate 100 as shown in FIG. is set up. Note that reference numeral 95 in the figure indicates a flaw defect such as a bald flaw.

  As shown in FIG. 2A, the regular reflection camera 2 receives the regular reflection component 60 reflected at the reflection angle θ1 that is substantially the same as the incident angle θ1 among the reflected light reflected from the surface of the stainless steel plate 100. It is a reflection component light receiving means, and is installed above the stainless steel plate 100 at a position where the regular reflection component 60 can be received. The irregular reflection camera 3 is irregular reflection component light receiving means for receiving the irregular reflection component 70 reflected at the reflection angle θ2 different from the incident angle θ1 out of the reflected light reflected on the surface of the stainless steel plate 100. In addition, it is installed at a position where the irregular reflection component 70 can be received. A CCD camera was used for each of the regular reflection camera 2 and the irregular reflection camera 3.

The processing device 4 obtains data of reflected light reflected from the surface of the stainless steel plate 100 as information of the regular reflection component 60 from the regular reflection camera 2 and information of the irregular reflection component 70 from the irregular reflection camera 3. Then, predetermined surface inspection processing is executed based on each acquired data, and the result is output to, for example, a display device (not shown).
Specifically, the processing device 4 temporarily stores a CPU, a storage medium such as a ROM storing a control program of the CPU, data read from the storage medium, and a calculation result necessary in the calculation process of the CPU. And an interface I / F for inputting / outputting data to / from an external device such as the regular reflection camera 2 or the irregular reflection camera 3 described above. The CPU starts a program stored in the storage medium and can execute the surface inspection process shown in the flowchart of FIG. 2 in accordance with the program.

  FIG. 2 is a flowchart for explaining the surface inspection process executed by the processing apparatus 4. Here, in this surface inspection process, the presence / absence of wrinkle defects 95 is detected based on the information of the specular reflection component 60 received by the specular reflection camera 2, and the brush is determined based on the information of the irregular reflection component 70 received by the irregular reflection camera 3. The degree of the pattern 90 is discriminated. The information of the specular reflection component 60 from the specular reflection camera 2 and the information of the irregular reflection component 70 from the irregular reflection camera 3 are set values of predetermined thresholds described later. Except for different points, the same processing is performed in parallel for each acquired data. Therefore, in the following description of the surface inspection processing, processing corresponding to the regular reflection camera 2 will be described, and the irregular reflection camera 3 will be described. The description of the corresponding processing is omitted as appropriate.

  When the surface of the stainless steel plate 100 is inspected by the surface inspection apparatus 10, the program is executed in the processing apparatus 4, and first, the process proceeds to step S1. In step S1, information on the reflected light in the width direction W is read from the regular reflection camera 2 described above, and the process proceeds to step S2. Here, the information of the reflected light is read as a gray value which is brightness / darkness information of the reflected light in the width direction of the stainless steel plate (see (a) in the figure).

In step S2, a predetermined process is performed on the reflected light information read in step S1. In this predetermined processing, the reflected light information read as a gray value is subjected to gradation processing in 255 levels, and an averaging process for correcting the illuminance at both ends in the width direction W is performed ((b) in the figure). Reference) and the process proceeds to step S3.
In step S3, the information on the reflected light that has been subjected to the predetermined processing is compared with a predetermined threshold (see (c) in the figure). At this time, in the processing corresponding to the regular reflection camera 2, if the gray value of the regular reflection component 60 exceeds a predetermined first threshold value, detection information indicating that there is a defect is output, and on the other hand, it corresponds to the irregular reflection camera 3. In the processing, when the gray value of the irregular reflection component 70 exceeds a predetermined second threshold, discrimination information that the degree of the brush pattern exceeds the reference value is output, and the processing is returned.

Here, the setting value of each predetermined threshold value will be described.
FIG. 3 shows experimental results obtained by measuring the gray value of the specular reflection component 60 and the gray value of the irregular reflection component 70 for each of five types of steel plates. In FIG. 3, the specular reflection component 60 is “Bright”. The diffuse reflection component 70 is described as “Dark”, and the maximum value of each gray value is MAX, the minimum value is MIN, and the average value is AVE. The standard deviation is σ. Here, the steel plates 2 to 5 have a brush pattern, and the steel plate 1 does not have a brush pattern.

As can be seen from the figure, in the stainless steel plates (steel plates 2 to 5) having the illustrated brush pattern, the variation in the irregular reflection component 70 is larger than the variation in the regular reflection component 60. This correlation means that the influence of the brush pattern is large in the irregular reflection component 70, whereas the influence of the brush pattern is small in the regular reflection component 60.
That is, due to the brush pattern, the light is irregularly reflected, and the variation of the gray value increases. Therefore, in order to discriminate the brush pattern, the threshold value is increased (sweetened) on the irregular reflection side. On the other hand, on the specular reflection side where the influence of the brush pattern is small, the threshold value can be made small (strict) in order to detect defects with high accuracy.

Therefore, from this knowledge, in the surface inspection apparatus 10, the first threshold value is set to a value smaller than the second threshold value. Thereby, the threshold value in the regular reflection component 60 can be set strictly, and the presence / absence of a flaw defect such as the bald flaw 95 can be detected more suitably. In addition, in FIG. 4, the example of the setting value of each threshold value with respect to five types of various steel plates set based on this knowledge was shown.
Here, the wrinkle defect detecting means corresponds to steps S1 to S3 in the surface inspection process. Similarly, as described above, the brush pattern discriminating means has a threshold value for the wrinkle defect detecting means. It has the same configuration (step S1 to step S3) that is different only in the set value.

Next, the operation and effect of this stainless steel plate surface inspection apparatus will be described.
As described above, the surface inspection apparatus 10 includes the light source 1 that projects the inspection light 80 onto the surface of the stainless steel plate 100 having the brush pattern 90, and the surface of the stainless steel plate 100 that is projected from the light source 1. Of the reflected light, a regular reflection camera 2 that receives the regular reflection component 60, a diffuse reflection camera 3 that receives the irregular reflection component 70 of the reflected light, and the processing device 4 are provided. Then, the processing device 4 has a defect detection means for detecting the presence or absence of the defect 95 based on the gray value of the regular reflection component 60 received by the regular reflection camera 2 and the gray value of the irregular reflection component 70 received by the irregular reflection camera 3. And a brush pattern discriminating means for discriminating the degree of the brush pattern 90 based on the above.

  Therefore, if the surface of the stainless steel plate is inspected using this surface inspection apparatus 10, the inspection light 80 is projected onto the surface of the stainless steel plate 100, and the reflected light reflected by the surface of the stainless steel plate 100 is positive. The reflection component 60 and the irregular reflection component 70 are individually received, the presence or absence of a flaw defect 95 is detected based on the information of the specular reflection component 60 received individually, and the brush is determined based on the information of the irregular reflection component 70 received individually. The degree of the pattern 90 can be discriminated.

  That is, the regular reflection component 60 and the irregular reflection component 70 of the reflected light reflected from the surface of the stainless steel plate 100 have the correlation as described above between the influence of the wrinkle defect 95 and the influence of the brush pattern 90. Therefore, the presence or absence of the wrinkle defect 95 can be detected based on the information of the specular reflection component 60 in which the influence of the flaw defect 95 on the surface of the stainless steel plate 100 appears strongly. On the other hand, with respect to the brush pattern 90, the degree of the brush pattern 90 can be discriminated based on the information of the irregular reflection component 70 in which the influence appears strongly. Therefore, even if the surface of the stainless steel plate 100 has the brush pattern 90, that is, the surface of the stainless steel plate 100 is not smooth and the surface formation pattern is non-uniform, so-called flaw defects such as baldness. 95 and the brush pattern 90 can be distinguished, and each can be detected suitably.

As described above, according to the stainless steel plate surface inspection method and the stainless steel plate surface inspection apparatus according to the present invention, even if the stainless steel plate has a brush pattern, it is possible to appropriately distinguish between a lash and a brush pattern. , Each can be detected.
The stainless steel plate surface inspection method and the stainless steel plate surface inspection apparatus according to the present invention are not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

  For example, in the above-described embodiment, in the surface inspection process in the processing apparatus 4, the presence or absence of a wrinkle defect is detected based only on the information of the specular reflection component, and the degree of the brush pattern is included in the information of the irregular reflection component. However, the present invention is not limited to this, and may be configured to calculate the sum of or subtracted information between the information of the specular reflection component and the information of the irregular reflection component. You may make it judge including a parameter. However, with a simple configuration, the wrinkle defect 95 such as the bald wrinkle is distinguished from the brush pattern 90, and each of them is preferably detected. It is preferable to detect based on only the information and discriminate the degree of the brush pattern based only on the information of the irregular reflection component.

It is explanatory drawing which shows schematic structure of one Embodiment of the surface inspection apparatus for stainless steel plates which concerns on this invention. It is a flowchart explaining the surface inspection process performed with a processing apparatus. It is a figure which shows the experimental result which measured the gray value of the regular reflection component and the irregular reflection component with respect to five types of various steel plates, respectively. It is a figure which shows the example of the setting value of each threshold value with respect to five types of various steel plates. It is an example of the surface formation pattern of a stainless steel plate, The figure has shown the image of the nonuniform surface formation pattern which has a brush pattern on the surface. The example of the image image which received the steel plate surface which has a wrinkle defect in a brush pattern by each of the regular reflection component and the irregular reflection component is shown, The figure (a) is a light reception image by the irregular reflection component, (B) is a light reception image with a regular reflection component.

Explanation of symbols

1 Light source 2 Regular reflection camera (Specular reflection component light receiving means)
3 Diffuse reflection camera (diffuse reflection component light receiving means)
4 treatment apparatus 10 surface inspection apparatus for stainless steel plate 60 specular reflection component 70 irregular reflection component 80 light (for inspection) 90 brush pattern 95 hege haze (wrinkle defect)
100 stainless steel sheet

Claims (4)

A method for inspecting the surface of a stainless steel plate having a brush pattern,
The direction of the brush pattern and the plate passing direction are set in the same direction, the inspection light is projected on the surface of the stainless steel plate along the plate passing direction, and the reflected light is reflected by the surface of the stainless steel plate. Among them, the specular reflection component and the irregular reflection component are individually received using two CCD cameras along the plate passing direction and at a position facing the light projection position, and based on the information of the specular reflection component. A method for inspecting a surface of a stainless steel sheet, wherein the presence or absence of a flaw defect is detected and the degree of a brush pattern is discriminated based on information on the irregular reflection component. A surface inspection apparatus for a stainless steel plate for inspecting the surface of a stainless steel plate having a brush pattern,
A light source that projects light for inspection on the surface of a stainless steel plate having a brush pattern along the direction of the plate, and a regular reflection component of reflected light that is projected from the light source and reflected by the surface of the stainless steel plate A first CCD camera which is a regular reflection component light receiving means for receiving light at a position along the plate passing direction and facing the light source; and the diffused light component of the reflected light along the plate passing direction and the light source. A second CCD camera that is a diffusely reflected component light receiving means that receives light at a position opposite to the light source, a wrinkle defect detecting means that detects the presence or absence of a wrinkle defect based on information on the specular reflection component received by the specular reflection component light receiving means, A surface inspection apparatus for a stainless steel plate, comprising: a brush pattern discriminating unit that discriminates a degree of a brush pattern based on information on the irregular reflection component received by the irregular reflection component light receiving unit. The specular reflection component information from the specular reflection component light-receiving means and the irregular reflection component information from the irregular reflection component light-receiving means are gray values obtained by gradation processing the brightness of the reflected light in the width direction of the stainless steel plate, respectively.
When the gray value of the specular reflection component exceeds a predetermined first threshold, the wrinkle defect detection means outputs detection information indicating that there is a wrinkle defect,
The brush pattern discriminating means outputs discrimination information that the degree of the brush pattern exceeds a reference value when the gray value of the irregular reflection component exceeds a predetermined second threshold value. The surface inspection apparatus for a stainless steel plate according to claim 2.   The surface inspection apparatus for a stainless steel plate according to claim 3, wherein the first threshold value is smaller than the second threshold value.

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