JP2001188047A - Metal belt with marking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-flaw marking apparatus by which a pattern- shaped scab flaw without a remarkable uneven property such as a crack, a scoop or a rolling-up on the surface can be detected without omission and by which its information can be reported to the side of a user by a simple means, to provide a metal belt with a marking and to provide its manufacturing method. SOLUTION: The surface-flaw marking apparatus for the metal belt is provided with a flaw inspection means 40. The flaw inspection means comprises a plurality of light receiving parts 32a to 32c which extract reflected light from the face, to be inspected, of the metal belt 4 under two or more kinds of mutually different optical conditions. The flaw inspection means comprises a signal processing part 30 in which whether the surface flaw of the face to be inspected exists or not is judged on the basis of a combination of reflection components extracted under the mutually different optical conditions. The marking apparatus is provided with a marking means 44 by which a marking operation used to indicate information about the flaw is performed to the surface of the metal belt 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface flaw marking apparatus for optically detecting a surface flaw of a metal strip such as a thin steel plate and marking the position thereof, a metal strip with a marking, and a method of manufacturing the same. .

[0002]

2. Description of the Related Art There is a technique described in Japanese Patent Application Laid-Open No. 58-204353 as a method of detecting a surface of a metal object by applying light from the outside and capturing specularly reflected light and diffusely reflected light with a camera. This technology uses two cameras that place light at an angle of 35 to 75 degrees to the surface of the subject and reflect the reflected light in the specular direction and at an angle within 20 degrees from the incident or specular direction. The light is being received. Then, by comparing the signals of the two cameras and taking, for example, the logical sum of each other, that is, only when both are detected, it is regarded as a flaw, thereby realizing an inspection method which is not affected by noise.

As a method for inspecting a flaw on the surface of an object by receiving backscattered light from the object, Japanese Patent Laid-Open No.
There is a technique described in Japanese Patent No. 28943. The present technology is intended to detect a barbed flaw on the surface of a stainless steel plate by detecting light reflected on the stainless steel plate at a large incident angle and returning to the incident side.

[0004] As a flaw detector by detecting a plurality of backscattered reflected lights, there is a technique described in Japanese Patent Application Laid-Open No. 8-17867. This is to detect scratches on the hot-rolled flat steel. According to the present specification, the flaw slope angle of the flaw is 10 to 40 degrees, and a plurality of cameras are prepared in the backward diffuse reflection direction so as to cover all the specularly reflected light from the flaw slope in this range. I have.

Further, as a surface inspection apparatus using polarized light, the technology described in Japanese Patent Application Laid-Open No. 57-166533 is applied to a measurement object.
45-degree polarized light is incident and received by the proposed polarization camera. The polarization camera splits the reflected light into three using a beam splitter inside the camera, and receives the light through polarization filters having different azimuth angles.
A technique is disclosed in which three signals from a polarization camera are displayed on a monitor by signal processing similar to that of a color TV system, and the polarization state is visualized. This technique utilizes the technique of ellipsometry, and it is desirable that the light source be parallel light, and in the embodiment, laser light is used.

[0006] In Japanese Patent Application Laid-Open No. 9-165552,
A flaw inspection device for a steel sheet surface using ellipsometry is disclosed.

[0007]

The above prior arts are all aimed at detecting flaws having remarkable irregularities or detecting flaws having foreign substances such as oxide films. It was not possible to reliably catch all the flaws and the like having no pattern.

For example, in the technique described in Japanese Patent Application Laid-Open No. 58-204353, two cameras for receiving specularly reflected light and scattered reflected light are provided. Eliminates the effects of noise caused by the camera, and can be applied to flaws with remarkable unevenness, that is, flaws that have cracks, gouges, or curls up on the surface because the flaw signal is captured by both cameras However, in the case of a flaw such as a pattern-shaped barbed flaw having notable unevenness such that only one of the cameras can capture the flaw signal, the flaw cannot be all detected. .

In the technique described in Japanese Patent Application Laid-Open No. 60-228943,
It is intended for raised barbed flaws that have become apparent on stainless steel plates with small surface roughness,
A flaw having no raised part or a flaw-free part cannot be applied to a steel plate having a rough surface that reflects light returning to the incident side. In the technology described in JP-A-8-178867, the scratch is targeted, and since it is based on capturing specularly reflected light on the slope of the scratch, it does not have remarkable unevenness, such as a pattern-shaped barb. In the case of flaws, some of the flaws cannot be caught by the backscattered reflected light, and there is a problem that undetection occurs.

Another problem is that once the camera is installed and the angle of the reflected component to be received is determined, it cannot be easily changed.

The technique described in Japanese Patent Application Laid-Open No. 57-166533 and the technique described in Japanese Patent Application No. 7-286377 use the technique of ellipsometry, and include “thickness and refractive index of thin transparent layer” and "Unevenness in physical property values" can be detected. However, even if the flaw originally has a property value different from that of the base material portion, such as a surface-treated steel sheet, for an object covered with a material having the same property value from above, However, there is a problem that the effectiveness is reduced.

In the ellipsometry, it is necessary to receive reflected light from the same point at a corresponding pixel of each CCD and calculate an ellipsometric parameter for each pixel. for that reason,
In the technique described in Japanese Patent Application Laid-Open No. 57-166533, the reflected light is branched into three by a beam splitter and detected by three CCDs, and thus there is a problem that the light amount is reduced and it is difficult to perform pixel alignment between the CCDs. Was.

In the embodiment of Japanese Patent Application Laid-Open No. Hei 9-165552, three cameras are arranged in the direction in which the steel sheet moves (FIG. 6 in the specification), or the inclination of the three cameras arranged vertically or horizontally is changed. Although the same area is viewed (FIGS. 7 and 8),
In the case of FIG. 6 in the specification, there is a problem that the processing when the speed of the steel sheet changes is complicated. In addition, FIG.
In FIG. 8 of the specification, there is a problem that the optical conditions are not the same because the angles of the respective cameras are different, and it is also difficult to perform pixel alignment.

Further, in the technology described in Japanese Patent Application Laid-Open No. 58-204353 and the technology described in Japanese Patent Application Laid-Open No. 8-17867, since the optical axes of a plurality of cameras are not common but have different emission angles, two images obtained are different. The corresponding pixels have different visual field sizes,
There is a problem that a position shift occurs in the visual field if there is a flutter on the surface to be inspected or a change in distance due to a change in thickness of the object. In particular, in the technique described in Japanese Patent Application Laid-Open No. 58-204353, there is a great problem because it is required that two cameras take a logical sum for the same field of view.

[0015] From the viewpoint of quality assurance, it is an absolute condition that such a surface inspection apparatus does not detect undetected surfaces. The inspection device has not been realized.

Further, the inspection result of the surface flaw is generally determined only to be good or bad as a whole metal strip, and the user cannot know the minor flaw. Even if information on these surface flaws is notified to the user side, it can be said that there is no appropriate method other than the method of describing the information on the mill sheet or the like.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and is intended to remove a pattern-shaped barbed flaw having no remarkable unevenness such as surface cracks, gouges, and curling. It is an object of the present invention to provide a surface flaw marking device, a metal strip with a marking, and a method for manufacturing the same, which can detect without detection and inform the user of the information by simple means.

[0018]

The above object is achieved by the following invention.

According to a first aspect of the present invention, there is provided a light receiving section for extracting reflected light from a surface to be inspected of a metal strip under two or more different optical conditions, and a combination of the reflected components extracted under the different optical conditions. A metal inspection device having a signal processing unit for determining presence / absence of a surface flaw on a surface to be inspected based on a mark, and a marking means for performing marking on a surface of the metal strip to indicate information on the flaw. This is a device for marking the surface flaw of a belt.

In the apparatus according to the present invention, first, the light receiving portion of the flaw inspection means receives the reflected light from the surface of the metal band by two or more types of light receiving portions having different optical conditions such as polarization conditions. Analyze optical properties. Next, the signal processing unit of the flaw inspection means determines a normal part and an abnormal part, that is, a surface flaw, on the surface of the metal strip from the obtained optical properties. The part judged as surface flaw is printed by marking means.
Marking is performed by a predetermined method such as engraving and punching. The position of the marking can be determined by tracking the position of the surface flaw or its vicinity by tracking means or the like.

Next, the form of optical reflection on the steel sheet surface to be inspected by the surface flaw inspection apparatus of the present invention will be described in relation to the microscopic unevenness on the steel sheet surface. Generally, the micro unevenness of the steel sheet surface is temper rolled.
Originally, the points with high undulations were strongly rolled by the rolls to improve the flatness, and the other points were left untouched by the temper rolling rolls, so that the original uneven shape was left.

For example, in the case of an alloyed galvanized steel sheet, the base cold-rolled steel sheet 1 is hot-dip galvanized as shown in FIG. 12A and then passes through an alloying furnace. During this time, the iron element of the base steel sheet diffuses into the zinc of the plating layer, and usually, as shown in FIG.
As shown in FIG. 2C, an alloy crystal 3 having a columnar shape or the like is formed.
When this steel sheet is then temper-rolled as shown in FIG. 12 (b), particularly protruding portions of the columnar crystal 3 are flattened as shown in FIG. 12 (d) (tempered portion 6). (Non-tempered portion 7) remains the original columnar crystal shape.

FIG. 13 shows a model of what kind of optical reflection occurs on such a steel sheet surface. Light 8 incident on the part (tempered part 6) crushed by temper rolling
Is specularly reflected in the steel plate regular reflection direction. On the other hand, light incident on the portion (non-tempered portion 7) which is not crushed by the temper rolling and leaves the original columnar crystal structure is mirror-reflected by each microscopic element on the columnar crystal surface when viewed microscopically. But
The direction of reflection does not always match the direction of regular reflection of the steel sheet.

Therefore, the angle distributions of the reflected light from the tempered portion and the non-tempered portion can be seen macroscopically as shown in FIG.
(B). That is, (a) the tempered portion 6 has a specular reflection 9 having a sharp distribution in the steel plate regular reflection direction, and (b) the non-tempered portion 7 has a spread corresponding to the angular distribution of microplane elements on the columnar crystal surface. It becomes the reflection 10 having.
Hereinafter, the former is called specular reflection, and the latter is called specular diffuse reflection. As shown in FIG. 14C, the angular distribution of the reflection actually observed is obtained by changing the angular distribution of the specular reflection / specular diffuse reflection to the
The sum is obtained according to the area ratio of each non-tempered portion.

Although the above description has been made with reference to an alloyed galvanized steel sheet as an example, the invention can be generally applied to other steel sheets in which a flat portion is formed by temper rolling.

Next, a description will be given of the optical reflection characteristic of a flaw called a pattern-shaped bald flaw, which does not have remarkable unevenness, to be detected by the present invention. For example, as shown in FIG. 15, the barge flaw 11 seen on the galvannealed steel sheet 4 has the barge flaw 11 on the cold-rolled steel sheet 1 before plating, and the plating layer 2 rides thereon. Further, alloying due to diffusion of the underlying iron progresses.

In general, the barge portion differs from the base material in, for example, the plating thickness and the degree of alloying. As a result, for example, when the plating thickness of the barbed portion is large and the base material is convex, the area of the tempered portion becomes larger than that of the non-tempered portion by performing temper rolling. Conversely, when the barb portion is concave compared to the base material, the barb portion does not contact the temper rolling roll, and the non-tempered portion occupies the majority. Further, when the alloy of the barb is shallow, the angular distribution of the minute surface element is strong in the direction of the steel sheet, and the diffusivity is small.

A description will be given of how the pattern-like barbed flaws look due to the difference in the surface properties between the barbed portion and the base material portion. Based on the deformation model of the plating surface in the above-mentioned temper rolling, the difference between the barb portion and the base material portion is classified into the following three types as shown in FIG.

(A): The area ratio of the tempered portion in the barbed portion (solid line) and the angle distribution of the micro-surface element in the non-tempered portion are different from those of the base material portion (broken line). Here, the temper portion is a normal angle ξ =
Corresponding to 0, the figure shows a peak. This peak height (area ratio) is different between the barb portion and the base material portion. Also,
The non-tempered portion corresponds to the other portion (slope), and the distribution of the area ratio between the barbed portion and the base material portion is different in the figure. This slope portion reflects the angle distribution of the micro-surface element in the non-tempered portion.

(B): The area ratio of the tempered portion is different between the barbed portion and the base material portion, but the angle distribution of the minute surface element in the non-tempered portion does not change. In the figure, the peak height is different between the barb portion and the base material portion, but the shapes of the slopes match.

(C): The angular distribution of the micro-surface elements in the non-tempered portion is different between the barbed portion and the base material portion, but the area ratio of the tempered portion does not change. In the figure, the peak height is the same at the barb portion and the base material portion, but the shape of the slope is different.

Such a difference in the temper portion area ratio and the angle distribution of the minute surface element is observed as a difference in the angle distribution of the amount of reflected light as shown in FIG.

When there is a difference in the area ratio of the tempered portion (cases a and b), as shown in FIGS. 16A and 16B, the angular distribution of the reflected light amount is different from that of the barge portion 11a and the base material portion. 12a
become that way. The difference is the direction in which the angular distribution peaks,
That is, it is observed from the regular reflection direction. When the area ratio of the tempered portion of the barbed portion is larger than the base material portion (FIGS. 16a, b, 17a,
(corresponding to b), the barb looks bright from the specular reflection direction, and conversely, if the temper ratio of the barge portion is smaller than the base material portion, the barge is observed dark from the specular reflection direction.

When there is no difference in the temper area ratio (the above ((
In case c)), the scab cannot be seen by observation from the steel plate regular reflection direction. Nevertheless, when there is a difference in the diffusivity of the specular diffuse reflection component, flaws are observed from the diffusion direction deviating from the peak of the angular distribution as shown in FIG. For example, when the diffusivity of the specular diffuse reflection component is small, the barb is generally observed brightly from the diffusion direction relatively close to the specular reflection, and the brightness decreases as the distance from the specular reflection direction increases, and the barge and the barge at a certain angle. The difference between the base material portions disappears, and observation becomes impossible at angles before and after the difference. Further away from the specular reflection, the balding is observed darker.

In order to discriminate and detect such pattern-like barbed flaws from the base material portion, it is necessary to examine at what angle the reflected light from the minute surface element is extracted in FIG. is there. For example, as in the examples of FIGS. 16 (a) and 16 (b), detecting the difference between the barb portion and the base material portion in the regular reflection direction is equivalent to the angular distribution of the micro surface element shown in FIG. Ξ = 0 is extracted, and the difference between the barb portion and the base material portion is detected.

When mathematically expressing that extraction is performed for ξ = 0, each of the functions S (図) shown in FIG. 17 is extracted as a delta function δ (ξ) shown in FIG. This is equivalent to multiplying by a function representing characteristics (hereinafter referred to as a weighting function) and integrating. Further, for example, measuring at a position of 40 degrees, which is 20 degrees from the regular reflection, at the incident angle 60 means detecting reflection by a plane (small plane element) whose normal angle ξ is shifted by 10 degrees. . This is shown in FIG.
This corresponds to the use of the weight function δ (ξ + 10) as shown in FIG. Note that the relationship between the reflection angle and the normal angle ξ of the micro surface element is calculated from FIG.

In this way, it can be understood that the angle at which the reflected light from the minute surface element is extracted corresponds to what weight function is designed. The weight function does not necessarily need to be a delta function, and may have a certain width.

From this point of view, FIG.
Considering a weight function for discriminating and detecting a barbed flaw having an area ratio distribution as shown in (b) and (c) from the base material, the δ function δ (ξ) shown in FIG. This is one example. However, in this case, since the cameras are installed at different light receiving angles, the two optical systems cannot have the same visual field size. Also, once a camera is installed to measure diffuse reflected light, it is not easy to change the weight function because it is necessary to change the installation position of the camera.

For the former problem, measurement on the same optical axis is required. Therefore, it is desirable that both the specular reflection component and the specular diffuse reflection component be detected by measurement from the steel plate regular reflection direction instead of capturing the diffuse reflection light. For the latter, it is desirable that the weighting function can be set with a certain degree of freedom with respect to a change in the installation position of the camera.

For this purpose, in the present invention, a linear light source having a diffusion characteristic is used as a light source instead of a parallel light source such as a laser. Also, the specular reflection component and the specular diffuse reflection component are separated and extracted from the steel plate regular reflection direction by using polarized light.

In order to explain the function and effect of this linear diffused light source, first, as shown in FIG.
4 is arranged parallel to the steel plate 4 and is in a plane perpendicular to the light source,
Consider a reflection characteristic when one point on the steel plate 4 is observed from a direction in which the incident angle coincides with the emission angle (hereinafter, referred to as a steel plate regular reflection direction).

Now, as shown in FIG. 20A, in the case of light emitted from the central portion of the linear light source 14, the light incident on the temper portion is reflected specularly, and is all captured in the steel plate regular reflection direction. Can be On the other hand, the light incident on the non-tempered portion is specularly reflected, and only the light reflected by the minute surface element that happens to be oriented in the same direction as the normal direction of the steel sheet is captured. Since such a small surface element is very small in probability, the specular reflection from the temper portion becomes dominant in the reflected light captured in the steel plate regular reflection direction.

On the other hand, as shown in FIG.
In the case of light emitted from other than the center of the linear light source, the light incident on the temper portion is specularly reflected and reflected in a direction different from the steel plate regular reflection direction, and cannot be captured in the steel plate regular reflection direction. On the other hand, the light that has entered the non-tempered portion is specularly reflected, and the light reflected in the regular reflection direction of the steel plate is captured. Therefore, all the reflected light captured in the steel plate regular reflection direction is specular diffuse reflection light reflected at the non-tempered portion.

When the above two cases are combined, the light radiated from the entire linear light source can be captured by observing from the regular reflection direction of the steel sheet as follows: specular reflection light from the tempered portion and specular diffusion from the non-tempered portion. It is the sum of the reflected light.

Next, how the polarization characteristics change when the surface to be inspected is observed from the specular reflection direction using the linear light source will be described.

In general, when light is reflected on a mirror-like metal surface, polarization characteristics are preserved by reflection of light whose direction of the electric field is parallel to the incident surface (p-polarized light) or light perpendicular to the incident surface (s-polarized light). The light is emitted as p-polarized light or s-polarized light. Also, arbitrary linearly polarized light having both p-polarized light component and s-polarized light component is emitted as elliptically polarized light according to the reflectance ratio of p and s-polarized light and the phase difference.

Hereinafter, a case where light is irradiated from a linear diffusion light source to an alloyed galvanized steel sheet will be considered. FIG. 21 (a)
As shown in the figure, the light emitted from the central part of the linear light source 14 is
It is specularly reflected at the tempered portion of the steel plate 4 and is observed in the steel plate regular reflection direction. In this regard, reflection on the above-mentioned general mirror-like metal surface is established as it is, and p-polarized light is emitted as p-polarized light.

On the other hand, as shown in FIG. 21 (b), light emitted from portions other than the central portion of the linear light source is specularly reflected by a tilted minute surface element of the crystal surface of the non-tempered portion, and is specularly reflected by a steel plate. Some are observed in the direction. At this time, even if p-polarized light parallel to the incident surface of the steel plate is incident, the light is not parallel to the incident surface for the inclined minute plane element that is actually reflected. It becomes linearly polarized light. As a result, the incident light is emitted as elliptically polarized light from the minute surface element. Here, the same applies when s-polarized light is incident instead of p-polarized light.

In addition, regarding linearly polarized light having an arbitrary polarization angle having both p and s polarization components, the polarization angle is tilted with respect to the incident surface for a small plane element tilted for the same reason as described above. Therefore, the shape of the elliptically polarized light emitted in the regular reflection direction of the steel sheet is different from the light that enters from the center of the linear light source and is specularly reflected by the temper portion.

Hereinafter, a case where linearly polarized light having both p and s components is incident will be described more specifically.

First, as shown in FIG. 22, the light 8 from the linear diffused light source 14 is linearly polarized by a polarizing plate 15 having an azimuth angle α, then is incident on a horizontally placed steel plate 4, and its regular reflection is performed. Consider that light is received by the photodetector 16.

As described above, with respect to the light 8 emitted from the point C on the light source, the component reflected specularly by the tempered portion and the minute surface element whose normal line happens to be vertical in the non-tempered portion happened. Is reflected from the point O (and, as a result, the surrounding area 13) on the steel plate,
6 contributes to the light reflected in the direction.

On the other hand, as shown in FIG. 23, for the light 8 from the point A shifted by an angle φ when viewed from the point O, the specular reflection component is reflected in a direction different from that of the photodetector 16. Normal angle ξ (the angle of the normal to the vertical direction is ξ)
Only the specular diffuse reflection component due to the micro-plane element contributes. Here, the relationship between φ and ξ is given by the following equation based on simple geometric considerations. cosξ = ² cos θ · cos ² (φ / 2) / [sin ² φ + 4 · [cos ² θ · cos ⁴ (φ / 2) + sin ² θ · sin ⁴ (φ / 2)]] ^1/2 (1 Where θ is the angle of incidence on the steel plate.

Next, the polarization state of the light reflected as described above will be considered. In FIG. 22, the light 8 emitted from the point C passes through the polarizing plate 15 having the azimuth angle α, and after being specularly reflected at the point O, the polarization state is determined using a Jones matrix generally used in polarization optics. E _c = T · E _in (2) Here, E _in represents a linear polarization vector (column vector) having an azimuth α, and T represents a reflection characteristic matrix of the steel plate. Each component is as follows. ^{_{E in = Ep · t (cosα}} , sinα) T = r s (T mn); T 11 = tanΨ · exp (jΔ), T 22 =
1, T ₁₂ = T ₂₁ = 0

Where ^t () is a column vector and tanΨ is p ·
The amplitude reflectance ratio of s-polarized light, Δ represents a phase difference caused by the reflectance of p · s-polarized light, and r _s represents the s-polarized light reflectance. Note that these matrix expressions are as shown in Equation 1.

(Equation 1)

Similarly, in FIG. 23, the light 8 emitted from the point A is
The polarization state of light reflected in the direction of the photodetector 16 by the small plane element having the normal angle ξ is E _A = R (ξ) if the incident surface is orthogonal to the polarizer 15 and the analyzer 17. ) · T · R (−ξ) · E _in (3) where R is a two-dimensional rotation matrix of the angle ξ, and its component R _mn is as follows. R ₁₁ = R ₂₂ = cosξ, R ₁₂ = -R ₂₁ = -sinξ

The matrix expression of R (ξ) is as shown in Expression 2.

[0058]

(Equation 2)

Equation (2) is a special case where ξ = 0 in equation (3), and both the specular reflection component and the specular diffuse reflection component can be uniformly considered using (expression 3). .

Calculating equation (3) and illustrating the elliptically polarized state of the reflected light from the micro-plane at the normal angle ξ, the result is as shown in FIG. Here, the azimuth angle α of the incident polarized light is 45 degrees, the incident angle θ is 60 degrees, and the reflection characteristics of the steel sheet are Ψ = 28 ° and Δ = 120.
°. From the figure, it can be seen that the ellipse inclines as the value of ξ changes with respect to the ellipse in the case of ξ = 0, ie, specular reflection. Therefore, for example, by inserting an analyzer in front of the photodetector and setting the angle of the analyzer, it is possible to select which normal angle to extract more reflected light from the microscopic surface element.

[0061] To quantify this, when obtaining the polarization state E _D after the insertion of the analyzer of the light detecting angle β to the reflected light of the polarization state represented by the formula (3), E _D = R (β) · a · R ( -β) · E a = R (β) · a · R (-β) · R (ξ) · T · R (-ξ) · E in (4) to become. Here, A = (A _mn ) is a matrix representing an analyzer, A ₁₁ = 1, and other components are 0. Note that the matrix representation of A is as shown in Equation 3.

[0062]

(Equation 3)

Is as follows. From equation (4), the light intensity L of the reflected light from the microscopic surface element having the normal angle ξ detected by the photodetector 16 (FIG. 23)
Calculating the, the area ratio of the micro-area element as S (ξ), L = S (ξ) · | E D | 2 = r s 2 · Ep 2 · S (ξ) · I (ξ, β) I (ξ, β) = tan ² Ψ ・ cos ² (ξ-α) ・ cos ² (ξ-β) +2 ・ tanΨ ・ cosΔ ・ cos (ξ-α) ・ sin (ξ-α) ・ cos (ξ-β ) · Sin (ξ-β) + sin ² (ξ-α) · sin ² (β-ξ) (5). Here, as described above, I (ξ, β) is a weighting function indicating how much the reflected light from the microscopic element having the normal angle ξ can be extracted, and depends on the polarization characteristics of the optical system and the subject. . And the reflectance r _s ^{2 of} the steel plate, the incident light amount Ep ² ,
The product of the area ratio S (ξ) is the detected light intensity.
When considering a target having a uniform material on the surface of the steel sheet, such as a surface-treated steel sheet, the value of r _s ² is considered to be constant. Also, E
p ² may be a constant value if the amount of incident light is uniform regardless of the position of the light source. Therefore, in order to obtain the light intensity detected by the photodetector, it is sufficient to consider the area ratio S (面) of the microplane at the normal angle ξ and the extraction characteristic I (ξ, β).

First, the extraction characteristic I (ξ, β) will be considered. If the contribution from the small-area element of the normal angle xi] ₀ tries to select a Kenhikarikaku beta ₀ as most increases, the candidate is given by solving the following equation beta. [∂I (ξ, β) / ∂ξ] ξ = ξ 0 = 0 (6)

A general mathematical expression of this expression is shown in Expression 4.

[0066]

(Equation 4)

From the above equation (6), when the analysis angle at which ξ = 0, that is, the contribution of the specular reflection component becomes the largest, is obtained, β
Is about -45 degrees. However, also here, as the reflection characteristics of the steel sheet, Ψ = 28 °, Δ = 120 °, and the azimuth α of the polarizer α = 45 °
And FIG. 25 shows the relationship between the angle ξ formed by the normal line of the minute surface element with respect to the vertical direction and the extraction characteristic, that is, the weight function I (ξ, -45) when the analysis angle β is −45 degrees. However, the maximum value is normalized to 1 for easy viewing.

From FIG. 25, ξ = 0, ie, the specular reflection component is the most dominant (easy to extract), and conversely, the normal angle ξ = ± 3
It can be seen that the specular diffuse reflection light from the microscopic element near 5 degrees is least extracted. Conversely, when the analysis angle β that best extracts the reflected light of ξ = ± 35 degrees is obtained from Expressions (5) and (6), approximately β = 45 degrees. FIG. 26 shows the relationship between the normal angle ξ and the extraction characteristic I (ξ, 45) for the analysis angle β = 45 degrees. Here, the reason why the curve of β = 45 degrees is not symmetrical is that, when considering the incident surface (the plane spanned by the incident light and the reflected light with respect to the minute surface element) as a reference, when ξ is positive, the apparent polarization of the incident polarized light is considered. This is because the azimuth angle α becomes smaller (approaches p-polarized light) and the p-polarized light reflectance of the steel sheet is smaller than the s-polarized light reflectance. Also,
The figure also shows β = 90 °, which is a characteristic intermediate between β = −45 ° and 45 °.

As shown in the equation (5), the reflected light intensity L from the microscopic surface element having the normal angle は is calculated based on the extraction characteristic (weight function) I (ξ,
β) and the area ratio S (ξ), the light intensity finally received by the photodetector 16 is S (ξ) ・ I (ξ,
β) is integrated over ξ. For example, when light reflected from a steel plate having a reflection characteristic as shown in FIG. 27 is received through an analyzer having an analysis angle β of −45 degrees, the area ratio S (ξ) shown in FIG. Extraction characteristics I (ξ,
The value obtained by integrating with weighting β) is the amount of received light.

Let us consider a case where there is a pattern-shaped barbed flaw having a characteristic as shown in FIG. 16 on the steel sheet surface. Area ratio in that case
S (ξ) is as shown in FIGS. 17 (a), (b) and (c), respectively.

First, consider the case where there is a difference only in the specular reflection component as shown in FIGS. 16 (b) and 17 (b). The light intensity when such a flaw is received through an analyzer having an analysis angle β = −45 degrees is obtained by integrating FIG. 17 (b) by applying a weight function I (ξ, β) shown in FIG. 25. Therefore, it is possible to detect a difference in the amount of reflected light between the base material portion and the barb portion. As for the analysis angle β = 45 degrees, there is no difference in the specular diffuse reflection component as shown in FIG. 17 (b), and there is a difference only in the vicinity of ξ = 0 ゜. Given that the weight function I ((, β) of β = 45 ゜ is low near ξ = 0 ゜, the product is ξ
Is low in the entire region of, and the difference is canceled by the integration. Therefore, it is not possible to detect a difference between the base material portion and the barb portion.

When only the specular diffuse reflection component is different as shown in FIGS. 16 (c) and 17 (c), conversely, it cannot be detected by passing through a -45 degree analyzer. In this case, it can be detected by passing through a 45-degree analyzer where the weighting function I (ξ, β) shows a high value at a distance from ξ = 0 ゜.

By the way, the normal angle て い る at which the difference in the specular diffuse reflection component between the base material portion and the balding portion disappears is about ξ = ± 20 degrees in FIG. 17 (c). If there is a flaw whose line angle ξ happens to be around ± 30 degrees, it cannot be detected even through a 45-degree analyzer. In that case, another analyzer having an analysis angle (for example, β = 90 °) having another extraction characteristic may be separately prepared, and may be received by the third photodetector.

Generally, the reflection characteristics of the base material and the barb on the surface of the steel sheet are almost any of those shown in FIGS. 10 (a), 10 (b) and 10 (c). (In this example, the detection angle), detection can be performed in most cases. However, in the special case as described above, in order to eliminate the oversight, the analyzer uses three analyzers having different analysis angles, and extracts and receives the reflected light from the micro surface element having the corresponding three normal angles. It is desirable to do so.

When there is a difference between the specular reflection component and the specular diffuse reflection component as shown in FIGS. 16 (a) and 17 (a),
Basically, it is possible to detect the difference between the base material portion and the barb portion only by the reflected light passing through one analyzer.

In the present invention, an incident polarizer is disposed on the entire surface of the linear diffused light source, and the azimuth of the polarized light is set to include both p-polarized light and s-polarized light. Then, a camera that captures an image through a polarizer having a polarization angle that more transmits the specular reflection component of the specular reflection light and a camera that captures an image through a polarizer having a polarization angle that transmits the specular diffuse reflection component more is used.

With such an optical system, measurement is performed on a common optical axis from the specular reflection direction, so that it is possible to cope with both specular reflection and specular diffuse reflection without being affected by fluctuations in the steel sheet distance or speed. Two signals,
A surface flaw inspection device capable of detecting a pattern-shaped bald flaw having no remarkable unevenness without causing undetection is realized. The angle of the specular diffuse reflection component to be detected can be easily changed by setting the analysis angle.

By measuring the intensity or ratio of specular reflection and specular diffuse reflection as described above, it is possible to detect a change in surface texture that affects specular reflection or specular diffuse reflection, in addition to the above-mentioned patterned barbed flaw. . For example, the surface finish of a metal band such as dull finish or hairline finish can be detected in principle if there is a change in the distribution of minute reflecting surfaces, and application to inspection of these surface properties can also be expected. .

It goes without saying that a known method and means may be used in combination with the apparatus of the present invention for the detection and determination of surface flaws. This will be described later in detail.

As described above, the position of the surface to be inspected determined to have a surface flaw is tracked by the tracking means. Tracking can be performed by calculating the time at which the position of the surface flaw reaches the marking means from the transport speed of the metal strip. The marking means is based on a marking instruction from the tracking means,
Marking is performed on the surface of the metal strip.

The marking can be performed by various methods according to the purpose and use. This may be any marking method that is easy to detect in the next step, such as printing with ink or paint, marking with a stamping machine, punching with a punch, modification of surface roughness with a grinder, etc., or metal band. When is a ferromagnetic material, it is performed by a predetermined method such as magnetic marking.

The positions of the markings may coincide with the positions of the surface flaws, but may be coincident only in the longitudinal direction without being coincident in the width direction. For example, when a material is automatically charged into a press line or the like, it may be easier to detect the marking if the position of the marking is rather constant in the width direction.

According to a second aspect of the present invention, light reflected from a surface to be inspected of a metal strip is extracted under two or more different optical conditions, and based on a combination of the reflected components extracted under these different optical conditions. A method for producing a metal strip with a marking, characterized in that the presence or absence of surface flaws is determined and a marking indicating information on the flaw is applied to the surface of the metal strip.

According to the present invention, marking is performed on the surface of the metal band at a portion determined to have a surface flaw by the above-described surface flaw determination method. Since the marking indicating the presence of the surface flaw is given in this way, it becomes possible to remove the surface flaw portion in a subsequent process or in a consumer, and it is possible to prevent the surface flaw from slipping into the product. Further, according to this manufacturing method, after the metal strip is manufactured, operations such as coil division for removing surface flaws can be greatly simplified or omitted, so that production efficiency is improved.

According to a third aspect of the present invention, the light reflected from the surface to be inspected of the metal strip is extracted under two or more different optical conditions, and based on the combination of the reflected components extracted under these different optical conditions. Determining the presence or absence of surface flaws, marking the surface of the metal strip with information about the flaws, winding the metal strip with the marking into a coil, winding the coil A step of detecting the marking by returning, and a step of avoiding or removing a predetermined range of the metal band based on the information indicated by the marking,
And performing a predetermined process on the remaining portion of the metal band that has not been avoided or removed.

According to the present invention, the marking is performed on the surface of the metal band in the same manner as in the second invention, and then the metal band is wound into a coil. The wound coil is transported to a factory or the like to form a thin plate. At the time of molding, the coil is rewound in advance, and the marking is detected visually or by a simple detector or the like. When the marking is detected, a defective portion including a flaw in the metal band is avoided or removed from the information indicated by the detection.

Here, the range of the defective portion is, for example, the portion where the marking is applied in the case where the marking is applied in accordance with the position of the flaw, and the marking includes information such as the type and degree of the flaw. If so, it is determined based on the type and degree of flaws that are defective in the molding process. In addition, avoiding or removing a predetermined range of the metal band means cutting and removing a defective portion of the metal band, or adjusting a feeding amount (feed) of the metal band to a processing step. Is to control the supply of the metal band to the processing step so that the defective portion is not processed, for example, by passing (passing) the defective portion.

According to a fourth aspect of the present invention, a mark indicating information on a flaw is given to a surface of an abnormal portion in which a combination of reflection components from a surface separated under two or more different optical conditions is different from a normal portion. A metal strip with a marking.

As described above, the metal strip of the present invention is marked on the portion determined to be different from the normal portion by the optical analysis of the surface, that is, the position of the surface flaw. Therefore, as described above, it is possible to remove the abnormal portion and prevent the metal band from being mixed in the product in a post-process using the metal band and in a consumer.

The fifth aspect of the present invention relates to a part in which the amount of light of one or both of the specular reflection component from the surface and the specular diffuse reflection component due to a large number of minute specular reflection surfaces becomes abnormal. It is a metal band with a marking, which is provided with a marking indicating information.

In the metal band according to the present invention, when the state of the specular reflection or the specular diffuse reflection from the surface is different from that of the normal part, the marking is applied to the position. Here, the specular diffuse reflection is, as described above, a surface on which a large number of minute specular reflection surfaces whose normals are directed to a specific direction are distributed. As in the case of the above-described invention, when this metal band is used, the treatment of an abnormal portion becomes easy.

According to a sixth aspect of the present invention, a plurality of surface flaw inspection means including a surface flaw inspection means having a light receiving section and a signal processing section, and the inspection results of the metal band surface flaws are comprehensively determined. 2. The apparatus according to claim 1, further comprising marking information creating means for creating marking information on the surface.

According to the present invention, in addition to the surface flaw inspection means having the light receiving section and the signal processing section according to the first invention, the size and shape of flaws and dirt, the reflectance of irradiated light, and the like are detected. By combining ordinary surface inspection means for inspecting surface property abnormalities such as contamination and dirt, the type and degree of surface flaws and other abnormal parts are classified. This makes it possible to make a comprehensive judgment on various surface property abnormalities including abnormalities of specular diffuse reflection, and to mark information on those abnormalities.

The seventh aspect of the present invention relates to a method of inspecting a surface to be inspected based on a combination of reflection components extracted under two or more different optical conditions, the inspection result by a plurality of surface inspection methods including a surface flaw inspection method. A method for producing a metal band with a metal band marking according to the second invention, characterized in that the presence or absence of a surface flaw is determined based on the judgment.

According to the present invention, the reflected light from the inspected surface of the metal strip in the second invention is extracted under two or more different optical conditions, and based on a combination of the extracted reflected components, the reflected light of the inspected surface is extracted. In addition to the surface flaw inspection method to be inspected,
The types and degrees of surface flaws are classified by combining ordinary surface inspection methods. Here, the normal surface flaw inspection method is, for example, a surface inspection method for detecting the size and shape of a flaw, the reflectance of irradiation light, and the like, and inspecting an abnormality of the surface property such as a flaw or dirt. In this way, comprehensive judgment is made on various surface property abnormalities including abnormalities of specular diffuse reflection, and information on those abnormal parts is marked.

According to an eighth aspect of the present invention, for a surface flaw including an abnormal part in which a combination of reflection components from a surface separated under two or more different optical conditions is different from a normal part, marking indicating information on the flaw is provided on the surface. A metal band with a marking according to the fourth invention, wherein the metal band is provided with a marking.

The metal strip according to the present invention can be used in addition to the abnormal portion in the third aspect of the invention, in addition to the normal surface flaw inspection, for example, the surface inspection results based on the size and shape of the flaw or the reflectance of irradiated light, or various surface flaws. Marking is provided on the surface for information on properties. Here, the abnormal portion in the third invention is a portion where the intensity or ratio of the reflected component is different from that of the normal portion when the reflected light is separated under two or more kinds of optical conditions as described above.

The ninth invention relates to a metal band surface including a portion in which the amount of light of one or both of the specular reflection components from the surface and the specular diffuse reflection components by a plurality of minute specular reflection surfaces becomes abnormal. A metal band with marking according to a fifth aspect of the present invention, wherein the information is provided with a marking on the surface indicating information on the surface of the metal band.

The metal strip according to the present invention can be used in addition to the abnormal portion in the fifth invention, in addition to the normal surface flaw inspection, for example, the result of surface inspection based on the size and shape of the flaw or the reflectance of irradiation light, or various surface Marking is provided on the surface for information on properties. Here, the abnormal portion in the fourth invention is a portion where the state of specular reflection or specular diffuse reflection from the surface is different from that of the normal portion as described above, and the reflected light is reflected under two or more polarization conditions. When separated, the intensity or ratio of the reflection component can be determined as a portion different from the normal portion.

According to the above invention, various surface defects including abnormalities of specular diffuse reflection or abnormal portions of surface properties can be
Since the marking indicating the information is provided on the surface of the metal strip, it becomes possible to know the type and degree of the surface flaw in a post-process or in a consumer, and it is possible to cope with various uses and usage purposes.

Also, by marking the surface of the metal band as described above, the metal band can be wound up without cutting and removing the surface flaws and the like, and the number of coils increases by cutting and removing. Can be prevented. As described above, since the number of coils does not increase, in the handling of the coil, an increase in trouble of winding is prevented. Further, in the transport, unwinding and processing of the coil, the number of coils to be processed does not increase, so that the handling effort is reduced.

[0102]

FIG. 1 shows one embodiment of the present invention.
It is a block diagram showing an example. The surface flaw detection device 41 extracts reflected light from the surface to be inspected of the metal strip 4 under two or more different optical conditions, and the signal processing unit 30 uses the signal processing unit 30 to extract the surface of the surface to be inspected based on a combination of these reflection components. The presence or absence of a flaw is determined.

The tracking means 43 calculates the time when the position of the surface flaw reaches the marking means. This is based on the rotation speed measured by the tachometer 46 attached to the transport roll 45, the length of the surface flaw is converted to the plate length by the plate length calculation means 47, the time required to reach the marking means 44 It is obtained by conversion. At that time, the tracking means 43 sends a signal instructing the marking means 44 to perform marking. The marking means 44 performs marking such as printing and punching on the surface of the metal band.

FIG. 2 shows an example of a marked metal band. In this example, the position of the marking 49 is made coincident with the position of the surface flaw 11 in the longitudinal direction, and is fixed from the edge in the width direction. Thus, when used in a press line or the like, it is possible to detect the marking 49 at a fixed position from the edge regardless of the position of the surface flaw 11, and to take measures such as rejection of a part having the surface flaw 11. This makes it possible to prevent defective products from being manufactured.

FIG. 3 and FIG. 4 show an example of the surface flaw detection device 41. As the linear diffusion light source 22, a transparent light guide rod partially coated with a diffuse reflection paint is used, and light from a metal halide light source is incident from both ends thereof. Light diffusely emitted from the light guide rod of the light source 22 is transmitted to the cylindrical lens 25.
After passing through the polarizing plate 26 of 45 ° polarization, the steel plate
The light is converged and incident on a straight line over the entire width of 21. The reflected light 27 is further reflected by the mirror 28 arranged in the steel plate regular reflection direction, and enters the camera units 29a to 29d constituting the light receiving unit.

These camera units 29a to 29d are arranged in the board width direction as shown in FIG. By using the mirror 28 in this way, the device can be made compact. In addition, if the mirror 28 is installed at an appropriate distance from the steel plate 21, an area (outside the field of view of all cameras) is generated on the mirror 28 as shown in FIG. 5, and the mirror may be divided and configured. it can. By dividing the mirror in this way, the production cost can be kept low.

As shown in FIG. 6, the camera units 29a to 29d of the light receiving section are composed of three linear array cameras having analyzers 33a to 33c of -45 °, 45 °, and 90 ° in front of the lens. 32a to 32c, the optical axes of which are kept parallel. The deviation of the visual fields of the three cameras is corrected by the signal processing unit 30. When the optical axes are kept parallel in this way, three cameras 32a
Each pixel of ~ c has the same visual field size and corresponds one-to-one. Further, compared to splitting one reflected light using a beam splitter, loss of light quantity is eliminated, and efficient measurement can be performed.

The light receiving range A of each of the light receiving cameras 32a to 32c in each of the camera units 29a to 29d is, as shown in FIG. 5 described above, the corresponding light receiving camera in the other camera units 29a to 29d adjacent on both sides. They are arranged so as to partially overlap the light receiving range A of 32a to 32c. In other words, the reflected light from any position in the width direction on the steel plate 21 is at least 1 each.
Three types of light receiving cameras 32a in one camera unit 29a to 29d
In this case, a two-dimensional CCD camera can be used in the light receiving unit instead of the linear array camera. In the light emitting section, a fluorescent lamp can be used as the linear diffusion light source 22. Further, a fiber light source in which the output ends of the bundle fiber are aligned in a straight line can be used. This is because the light emitted from each fiber has a sufficient divergence angle corresponding to the N / A of the fiber, and the fiber light source in which the light is aligned substantially becomes a diffusion light source.

Here, the arrangement of a plurality of cameras is illustrated in FIG.
The details will be described with reference to FIG. Each camera unit 29a ~
In 29d, a plurality of units are arranged at regular intervals. One camera unit 29a to 29d operates under different conditions (-45, 45, 90
(Polarized light). Each camera is set up in parallel at regular intervals. Therefore, the respective visual fields are shifted by the same amount as the camera interval.

The order of cameras in each camera unit is the same. For example, the order is 45 degrees, 90 degrees, and -45 degrees from the left. The measurement range (effective area) is, for example,
The range observed under three conditions, only one condition, or
Regions observed only under two conditions (regions at both ends)
Is invalid and not used. The camera interval and the unit interval are determined as dimensions such that the maximum width of the steel sheet falls within the measurement range (effective area).

The three cameras in each unit are not adjusted to have the same field of view. After determining the flaw candidate area in each camera, the correspondence of each camera is determined in units of the flaw candidate area.
As described above, since the field of view of each camera is shifted, three cameras that can fit a certain flaw candidate area into the field of view may not be aligned (the three optical conditions may not be aligned). In that case, use the results of the camera of the next unit to
Prepare for 3 conditions. This concept is applicable not only to the case where three polarized lights are received but also to the case where the whole width of the test object is divided into a plurality of visual fields and observation is performed under arbitrary two or more conditions.

If the plurality of light receiving sections and the signal processing section are collectively referred to as flaw inspection means, the surface flaw marking apparatus shown in FIG. 1 is as shown in FIG. The flaw inspection means 40 includes light receiving sections 32a to 32c (corresponding to the cameras in FIGS. 5 and 6).
And a signal processing unit 30. The signal processing unit 30 detects the above-mentioned diffuse mirror reflection component by signal processing based on the intensity of the reflected light extracted under different optical conditions, and determines whether there is an abnormal part. After that, as in FIG. 1, the tracking means 4
3 and the position of the surface flaw is calculated by the plate length calculating means 47,
The marking means 44 performs marking at the position of the abnormal part.

FIG. 8 is a block diagram showing an example of the signal processing section. Light intensity signals a to c from the light receiving cameras 32a to 32c
Are input to the average value thinning units 34a to 34c, and the average value is calculated. Next, the pulse signal is input as the test object moves by a predetermined distance in the longitudinal direction, and is output as a signal for one line in the width direction. By this thinning process, the resolution in the longitudinal direction is made constant. In addition, the calculation frequency of the average value, the moving distance in the longitudinal direction of the test object is the light receiving cameras 32a to 32c.
If it does not become larger than the field of view, oversight can be eliminated.

Next, the pre-processing units 35a to 35c correct luminance unevenness of the signal. Here, the luminance unevenness includes one caused by the optical system, one caused by the reflectance of the test object, and the like. Further, the pre-processing units 35a to 35c detect the position of the edge of the metal band and perform processing for preventing a sudden signal change in the edge from being erroneously recognized as a flaw.

The preprocessed signals are converted into binary processing units 36a to 36c.
And a flaw candidate point is extracted by comparison with a preset threshold value. The extracted flaw candidate points are input to the feature calculation units 37a to 37c, and signal processing for flaw determination is performed. Here, when the flaw candidate points are continuous, position feature amounts such as a start address and an end address, a peak value thereof, and other density feature amounts are calculated as one flaw candidate region.

These calculated feature amounts are input to the specular flaw judgment unit 38a or the specular diffuse flaw judgment unit 38b according to the optical conditions (analysis angle β) of the original signals a to c.
The output of the feature value calculation unit 37a indicates that the optical condition of the original signal a is -45.
Degree analysis (β = -45 °). Therefore, in this case, the difference is input to the specular flaw determining unit 38a, and as described above, the difference in the amount of reflected light between the base material portion and the barb portion due to the specular reflection component is detected. On the other hand, the output of the feature calculation units 37b and c is such that the optical conditions of the original signals b and c are 45 degrees and 90 degrees analysis (β = 45 ゜ 90 ゜), and there is a difference only in the specular diffuse reflection component. . Therefore, the specular diffusible flaw determination unit 38
The defect is input to b and the flaw determination is performed based on the specular diffuse reflection component.

Finally, the flaw comprehensive judgment section 39 calculates the flaws based on the outputs of the specular flaw judgment section 38a and the specular diffuse flaw judgment section 38b.
For the inspection surface of the metal strip, the final flaw type and its degree are determined. Also, at this time, considering the overlap of the visual field between the cameras 32a to 32d and between the camera units 29a to 29d (FIG. 5), it is possible to appropriately use the flaw determination result based on the signal from the camera of the adjacent camera unit. desirable.

FIG. 9 shows an example in which such a surface flaw inspection means for detecting an abnormality of the specular diffuse reflection component to judge a flaw is combined with a surface flaw inspection means by another method. Here, the surface flaw inspection means 40a is the same as that shown in FIG. 7, extracts the reflected light under different optical conditions at the plurality of light receiving units 32a to 32c, and at the signal processing unit 30, the abnormalities of the specular diffuse reflection component are detected. Is detected to determine the flaw.

As the surface inspection means 40b of another method, a normal surface flaw inspection means, that is, an apparatus of a method of detecting and determining a surface flaw from the size and shape of the flaw, or a method of detecting a surface flaw based on the reflectance of irradiation light or the like is used. An apparatus of a type for detecting dirt and attached matter can be used. The surface inspection means 40b classifies types and degrees of normal surface flaws and abnormalities in surface properties. In the marking information creating means 42, the inspection means 40a,
Based on the inspection result of 40b, comprehensive classification and ranking are performed for various surface flaws and surface property abnormalities including abnormalities of specular diffuse reflection, and information for marking is created.

Thereafter, as in FIG. 1, the tracking means 43
The position of the surface flaw is calculated by the plate length calculating means 47.
The marking means 44 performs marking at the position of the abnormal part based on the marking information. At this time, it is desirable to indicate information on the type and degree of the surface flaw. This may be any form that can be detected, such as the marking pattern, shape, and band width. If barcode or OCR (optical character reading) is used in combination, more detailed information can be marked.

As described above, the marking on the surface of the metal band suppresses an increase in the number of coils, so that the efficiency of work can be improved even in handling such as coil winding, coil transportation, and rewinding. Is improved.
Also, in the processing of the metal band, the metal band is continuously supplied without interruption at the flaws, so that an increase in work efficiency can be expected.

[0122]

EXAMPLE The measurement results of the galvanized steel sheet according to the embodiment of FIG. 3 are shown in FIGS. FIG. 10 shows the aforementioned FIG. 17 (b)
FIG. 11 corresponds to FIG. 17 (c).
As shown in Fig. 0, the area ratio of the tempered portion is larger than that of the base material portion in the barbed portion, but the diffusivity of the non-tempered portion does not change.
(FIG. 17b) and a flaw (FIG. 17c) having a difference in diffusivity although there is no difference in the temper area ratio as shown in FIG. Figure 1
Regarding the type 1 flaw, there is generally an undetectable angle in the diffuse reflection direction, but two types of flaws having different angles were measured. For comparison, in the conventional technology, light was incident at an incident angle of 60 °, and the result was measured without polarization from the specular reflection direction (60 °) and the light receiving angle (-40 °) direction shifted by 20 ° from the incident direction. Are also shown in the figure. The above results are summarized in Table 1.

[0123]

【table 1】

In the prior art, light is received at two light receiving angles and the logical sum is taken for noise removal. However, it is impossible to detect these flaws simultaneously at the two light receiving angles. Furthermore, there are flaws that cannot be detected at either of the light receiving angles.

On the other hand, in the embodiment of the present invention, the reflected light components corresponding to the three different light receiving angles are extracted from the specular reflection direction by using the analyzer. Is possible. Also,
It is also easy to optimally set the analysis angle in accordance with the reflection characteristics of the flaw that needs to be detected.

[0126]

As described above, the present invention provides a method for extracting and capturing each component based on the knowledge that reflection on the surface of a steel sheet is composed of a specular reflection component and a specular diffuse reflection component. Using a diffused light source, a polarized light having both p-polarized light and s-polarized light is incident on the surface to be inspected, and by appropriately setting the analysis angle from the direction of the regular reflection of the steel sheet, a component containing more specular reflection components is And a method of extracting a component containing more specular diffuse reflection components.

This method makes it possible to detect a flaw in which no flaw can be observed from the specular reflection component, and it is possible to detect a pattern-shaped scorch flaw having no noticeable unevenness, which could not be detected conventionally, without undetecting it. became. In addition, since both components are captured by measurement on the same optical axis from the steel plate regular reflection direction,
Measurements that are not affected by changes in steel plate distance or speed are realized. Further, by setting the analysis angle, it is possible to select at which angle the specular diffuse reflection component is extracted.

From the viewpoint of quality assurance, it is an absolute condition that such a surface inspection apparatus has no undetection. According to the present invention, a surface flaw marking apparatus using a surface flaw inspection apparatus without undetection that can be widely applied to a surface-treated steel sheet and the like and the production of a metal band with a marking can be realized. In addition to being able to automate the surface flaw inspection, it is possible to notify the information to a post-process and a user side by simple means, and the industrial use effect is great.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of the device of the present invention.

FIG. 2 is a plan view showing one example of a metal strip of the present invention.

FIG. 3 is a schematic diagram showing an example of a schematic configuration of a surface flaw inspection device of the device of the present invention.

FIG. 4 is a schematic cross-sectional view of the surface flaw inspection device.

FIG. 5 is a diagram showing an arrangement of camera units incorporated in the surface flaw inspection apparatus in a metal band width direction.

FIG. 6 is a diagram showing an arrangement of cameras incorporated in one camera unit.

FIG. 7 is a block diagram showing another example of the device of the present invention.

FIG. 8 is a block diagram illustrating an example of a signal processing unit of the device of the present invention.

FIG. 9 is a block diagram showing still another example of the device of the present invention.

FIG. 10 is a diagram showing an example of a light intensity signal measured by the device of the present invention.

FIG. 11 shows another one of the light intensity signals measured by the apparatus of the present invention.
The figure which shows an example.

FIG. 12 is a diagram showing a method for manufacturing an alloy galvanized steel sheet and a detailed cross section thereof.

FIG. 13 is a schematic cross-sectional view showing a relationship between incident light and reflected light in a tempered portion and a non-tempered portion on the surface of a metal strip after temper rolling.

FIG. 14 is an angle distribution diagram of reflected light in the tempered portion and the non-tempered portion.

FIG. 15 is a cross-sectional view for explaining a generation process of a barbed portion in an alloy galvanized steel sheet.

FIG. 16 is an angle distribution diagram of a specular reflection component and a specular diffuse reflection component in a stub part and a base material part.

FIG. 17 is a diagram showing a relationship between a normal angle of a micro planar element and an area ratio in a barbed portion and a base material portion of a surface to be inspected.

FIG. 18 is a diagram illustrating a relationship between angles of incident light, reflected light, and the like on a microscopic surface element of a surface to be inspected.

FIG. 19 is a diagram illustrating a relationship between a normal line angle of a small surface element and a weight function.

FIG. 20 is a diagram showing a relationship between each incident light from each position of the linear diffused light source and an incident position on a surface to be inspected.

FIG. 21 is a diagram illustrating a polarization state of light reflected from a minute surface element when each incident light of the linear diffusion light source is polarized.

FIG. 22 is a diagram showing reflected light from a minute surface element when incident light from the center of a linear diffused light source is polarized.

FIG. 23 is a diagram showing reflected light from a minute surface element when incident light from a portion other than the center of the linear diffusion light source is polarized.

FIG. 24 is a diagram illustrating a relationship between a normal angle of a microscopic element and an elliptically polarized state of reflected light.

FIG. 25 is a diagram showing a relationship between a normal angle of a small surface element and a weighting function.
(Analysis angle: -45 ゜).

FIG. 26 is a diagram illustrating a relationship between a normal angle of a microscopic element and a weighting function at various analysis angles.

FIG. 27 is a diagram showing a relationship between a normal angle of a small surface element of an inspection surface and an area ratio.

[Explanation of symbols]

 4 Metal strip 6 Tempered part 7 Non-tempered part 8, 24 Incident light 10 Specular diffuse reflection light 11 Abnormal part (heavy part) 12 Base material part 14, 22 Linear diffused light source 15, 26 Polarizer 16, 32a-c Light reception Camera 17, 33a-d Analyzer 21 Steel plate 23 Shading case 24 Incident light 25 Cylindrical lens 26 45 ° polarized polarizing plate 26 27 Reflected light 28 Mirror 29a-d Camera unit 30 Signal processing unit 40a Surface flaw inspection means 40b Surface inspection means 41 Surface flaw detection device 43 Tracking means 44 Marking means 45 Transport roll 46 Tachometer 47 Plate length calculation means 49 Marking

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[Procedure amendment]

[Submission date] November 20, 2000 (200.11.
20)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Metal strip with marking

[Claims]

2. A metal sheet temper-rolled in a metal strip.
And the surface, corresponding to the inside of the specular diffuse reflection component due to the specular reflection component or multiple small specular surface from the metal surface, the abnormal portion fraction amount of either or both of the components becomes abnormal
And shows the information about the abnormal portion on the metal surface
A metal band with a marking, characterized in that the metal band is provided with a marking that has been applied .

3. A dull finish or hair lining for a metal band.
A metal surface down finish is applied, the combination normal part of the reflected component from the metal surface to be separated in two or more different optical conditions corresponding to different abnormal unit content, the abnormality on the metal surface marking with the metal strip, characterized in that a marking <br/> ring subjected to indicate information about the part.

4. In a metal strip, one or both of a metal surface subjected to dull finish or hairline finish and a specular reflection component from the surface or a specular diffuse reflection component by a plurality of minute specular reflection surfaces. light amount corresponds to the abnormal portion to be abnormal, the marking with the metal strip, characterized in <br/> that a marking has been subjected to indicate information about the abnormal portion <br/> on the metal surface .

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a marking with a metal strip having a Ma <br/> Kingu, for example a surface flaw of the metal strip such as steel sheet optically detected subjected at that position .

[0002]

2. Description of the Related Art There is a technique described in Japanese Patent Application Laid-Open No. 58-204353 as a method of detecting a surface of a metal object by applying light from the outside and capturing specularly reflected light and diffusely reflected light with a camera. This technology uses two cameras that place light at an angle of 35 to 75 degrees to the surface of the subject and reflect the reflected light in the specular direction and at an angle within 20 degrees from the incident or specular direction. The light is being received. Then, by comparing the signals of the two cameras and taking, for example, the logical sum of each other, that is, only when both are detected, it is regarded as a flaw, thereby realizing an inspection method which is not affected by noise.

As a method for inspecting a flaw on the surface of an object by receiving backscattered light from the object, Japanese Patent Laid-Open No.
There is a technique described in Japanese Patent No. 28943. The present technology is intended to detect a barbed flaw on the surface of a stainless steel plate by detecting light reflected on the stainless steel plate at a large incident angle and returning to the incident side.

[0004] As a flaw detector by detecting a plurality of backscattered reflected lights, there is a technique described in Japanese Patent Application Laid-Open No. 8-17867. This is to detect scratches on the hot-rolled flat steel. According to the present specification, the flaw slope angle of the flaw is 10 to 40 degrees, and a plurality of cameras are prepared in the backward diffuse reflection direction so as to cover all the specularly reflected light from the flaw slope in this range. I have.

Further, as a surface inspection apparatus using polarized light, the technology described in Japanese Patent Application Laid-Open No. 57-166533 is applied to a measurement object.
45-degree polarized light is incident and received by the proposed polarization camera. The polarization camera splits the reflected light into three using a beam splitter inside the camera, and receives the light through polarization filters having different azimuth angles.
A technique is disclosed in which three signals from a polarization camera are displayed on a monitor by signal processing similar to that of a color TV system, and the polarization state is visualized. This technique utilizes the technique of ellipsometry, and it is desirable that the light source be parallel light, and in the embodiment, laser light is used.

[0006] In Japanese Patent Application Laid-Open No. 9-165552,
A flaw inspection device for a steel sheet surface using ellipsometry is disclosed.

[0007]

The above prior arts are all aimed at detecting flaws having remarkable irregularities or detecting flaws having foreign substances such as oxide films. It was not possible to reliably catch all the flaws and the like having no pattern.

For example, in the technique described in Japanese Patent Application Laid-Open No. 58-204353, two cameras for receiving specularly reflected light and scattered reflected light are provided. Eliminates the effects of noise caused by the camera, and can be applied to flaws with remarkable unevenness, that is, flaws that have cracks, gouges, or curls up on the surface because the flaw signal is captured by both cameras However, in the case of a flaw such as a pattern-shaped barbed flaw having notable unevenness such that only one of the cameras can capture the flaw signal, the flaw cannot be all detected. .

In the technique described in Japanese Patent Application Laid-Open No. 60-228943,
It is intended for raised barbed flaws that have become apparent on stainless steel plates with small surface roughness,
A flaw having no raised part or a flaw-free part cannot be applied to a steel plate having a rough surface that reflects light returning to the incident side. In the technology described in JP-A-8-178867, the scratch is targeted, and since it is based on capturing specularly reflected light on the slope of the scratch, it does not have remarkable unevenness, such as a pattern-shaped barb. In the case of flaws, some of the flaws cannot be caught by the backscattered reflected light, and there is a problem that undetection occurs.

Another problem is that once the camera is installed and the angle of the reflected component to be received is determined, it cannot be easily changed.

The technique described in Japanese Patent Application Laid-Open No. 57-166533 and the technique described in Japanese Patent Application No. 7-286377 use the technique of ellipsometry, and include “thickness and refractive index of thin transparent layer” and "Unevenness in physical property values" can be detected. However, even if the flaw originally has a property value different from that of the base material portion, such as a surface-treated steel sheet, for an object covered with a material having the same property value from above, However, there is a problem that the effectiveness is reduced.

In the ellipsometry, it is necessary to receive reflected light from the same point at a corresponding pixel of each CCD and calculate an ellipsometric parameter for each pixel. for that reason,
In the technique described in Japanese Patent Application Laid-Open No. 57-166533, the reflected light is branched into three by a beam splitter and detected by three CCDs, and thus there is a problem that the light amount is reduced and it is difficult to perform pixel alignment between the CCDs. Was.

In the embodiment of Japanese Patent Application Laid-Open No. Hei 9-165552, three cameras are arranged in the direction in which the steel sheet moves (FIG. 6 in the specification), or the inclination of the three cameras arranged vertically or horizontally is changed. Although the same area is viewed (FIGS. 7 and 8),
In the case of FIG. 6 in the specification, there is a problem that the processing when the speed of the steel sheet changes is complicated. In addition, FIG.
In FIG. 8 of the specification, there is a problem that the optical conditions are not the same because the angles of the respective cameras are different, and it is also difficult to perform pixel alignment.

Further, in the technology described in Japanese Patent Application Laid-Open No. 58-204353 and the technology described in Japanese Patent Application Laid-Open No. 8-17867, since the optical axes of a plurality of cameras are not common but have different emission angles, two images obtained are different. The corresponding pixels have different visual field sizes,
There is a problem that a position shift occurs in the visual field if there is a flutter on the surface to be inspected or a change in distance due to a change in thickness of the object. In particular, in the technique described in Japanese Patent Application Laid-Open No. 58-204353, there is a great problem because it is required that two cameras take a logical sum for the same field of view.

[0015] From the viewpoint of quality assurance, it is an absolute condition that such a surface inspection apparatus does not detect undetected surfaces. The inspection device has not been realized.

Further, the inspection result of the surface flaw is generally determined only to be good or bad as a whole metal strip, and the user cannot know the minor flaw. Even if information on these surface flaws is notified to the user side, it can be said that there is no appropriate method other than the method of describing the information on the mill sheet or the like.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and is intended to remove a pattern-shaped barbed flaw having no remarkable unevenness such as surface cracks, gouges, and curling. It is an object of the present invention to provide a metal strip with a marking that can be detected without being undetected and that information can be notified to a user by simple means.

[0018]

The above object is achieved by the following invention.

The apparatus used in the present invention comprises: a plurality of light receiving sections for extracting reflected light from a surface to be inspected of a metal strip under two or more different optical conditions; Flaw inspection means having a signal processing unit for determining the presence or absence of a surface flaw on the surface to be inspected based on the combination,
A marking means for marking the surface of the metal strip to indicate information on the flaw thereof.

In the apparatus used in the present invention, first, the light receiving section of the flaw inspection means receives the reflected light from the surface of the metal band by two or more kinds of light receiving sections having different optical conditions such as polarization conditions. The optical properties are analyzed from the results. Next, the signal processing unit of the flaw inspection means determines a normal part and an abnormal part, that is, a surface flaw, on the surface of the metal strip from the obtained optical properties. Marking is performed on a portion determined as a surface flaw by a predetermined method such as printing, engraving, and perforation by a marking means. The position of the marking can be determined by tracking the position of the surface flaw or its vicinity by tracking means or the like.

Next, the form of optical reflection on the steel sheet surface to be inspected by the surface flaw inspection apparatus used in the present invention will be described in relation to the microscopic unevenness on the steel sheet surface. Generally, the surface irregularities on the surface of the steel sheet are temper-rolled by temper rolling, so that points with high undulations are rolled strongly by rolls to improve the flatness. The shape remains.

For example, in the case of an alloyed galvanized steel sheet, the base cold-rolled steel sheet 1 is hot-dip galvanized as shown in FIG. 12A and then passes through an alloying furnace. During this time, the iron element of the base steel sheet diffuses into the zinc of the plating layer, and usually, as shown in FIG.
As shown in FIG. 2C, an alloy crystal 3 having a columnar shape or the like is formed.
When this steel sheet is then temper-rolled as shown in FIG. 12 (b), particularly protruding portions of the columnar crystal 3 are flattened as shown in FIG. 12 (d) (tempered portion 6). (Non-tempered portion 7) remains the original columnar crystal shape.

FIG. 13 shows a model of what kind of optical reflection occurs on such a steel sheet surface. Light 8 incident on the part (tempered part 6) crushed by temper rolling
Is specularly reflected in the steel plate regular reflection direction. On the other hand, light incident on the portion (non-tempered portion 7) which is not crushed by the temper rolling and leaves the original columnar crystal structure is mirror-reflected by each microscopic element on the columnar crystal surface when viewed microscopically. But
The direction of reflection does not always match the direction of regular reflection of the steel sheet.

Therefore, the angle distributions of the reflected light from the tempered portion and the non-tempered portion can be seen macroscopically as shown in FIG.
(B). That is, (a) the tempered portion 6 has a specular reflection 9 having a sharp distribution in the steel plate regular reflection direction, and (b) the non-tempered portion 7 has a spread corresponding to the angular distribution of microplane elements on the columnar crystal surface. It becomes the reflection 10 having.
Hereinafter, the former is called specular reflection, and the latter is called specular diffuse reflection. As shown in FIG. 14C, the angular distribution of the reflection actually observed is obtained by changing the angular distribution of the specular reflection / specular diffuse reflection to the
The sum is obtained according to the area ratio of each non-tempered portion.

Although the above description has been made with reference to an alloyed galvanized steel sheet as an example, the invention can be generally applied to other steel sheets in which a flat portion is formed by temper rolling. As described above, in the invention of the temper-rolled metal band, the combination of the temper-rolled metal surface and the reflection component from the metal surface separated under two or more different optical conditions is normal in the metal band. A metal band with a mark, characterized in that the metal surface is provided with a marking corresponding to an abnormal portion different from the portion, and the metal surface is provided with a mark indicating information on the abnormal portion.

Next, a description will be given of the optical reflection characteristic of a flaw called a pattern-shaped bald flaw, which does not have remarkable unevenness, to be detected by the present invention. For example, as shown in FIG. 15, the barge flaw 11 seen on the galvannealed steel sheet 4 has the barge flaw 11 on the cold-rolled steel sheet 1 before plating, and the plating layer 2 rides thereon. Further, alloying due to diffusion of the underlying iron progresses.

In general, the barge portion differs from the base material in, for example, the plating thickness and the degree of alloying. As a result, for example, when the plating thickness of the barbed portion is large and the base material is convex, the area of the tempered portion becomes larger than that of the non-tempered portion by performing temper rolling. Conversely, when the barb portion is concave compared to the base material, the barb portion does not contact the temper rolling roll, and the non-tempered portion occupies the majority. Further, when the alloy of the barb is shallow, the angular distribution of the minute surface element is strong in the direction of the steel sheet, and the diffusivity is small.

A description will be given of how the pattern-like barbed flaws look due to the difference in the surface properties between the barbed portion and the base material portion. Based on the deformation model of the plating surface in the above-mentioned temper rolling, the difference between the barb portion and the base material portion is classified into the following three types as shown in FIG.

(A): The area ratio of the tempered portion in the barbed portion (solid line) and the angle distribution of the micro-surface element in the non-tempered portion are different from those of the base material portion (broken line). Here, the temper portion is a normal angle ξ =
Corresponding to 0, the figure shows a peak. This peak height (area ratio) is different between the barb portion and the base material portion. Also,
The non-tempered portion corresponds to the other portion (slope), and the distribution of the area ratio between the barbed portion and the base material portion is different in the figure. This slope portion reflects the angle distribution of the micro-surface element in the non-tempered portion.

(B): The area ratio of the tempered portion is different between the barbed portion and the base material portion, but the angle distribution of the minute surface element in the non-tempered portion does not change. In the figure, the peak height is different between the barb portion and the base material portion, but the shapes of the slopes match.

(C): The angular distribution of the micro-surface elements in the non-tempered portion is different between the barbed portion and the base material portion, but the area ratio of the tempered portion does not change. In the figure, the peak height is the same at the barb portion and the base material portion, but the shape of the slope is different.

Such a difference in the temper portion area ratio and the angle distribution of the minute surface element is observed as a difference in the angle distribution of the amount of reflected light as shown in FIG.

When there is a difference in the area ratio of the tempered portion (cases a and b), as shown in FIGS. 16A and 16B, the angular distribution of the reflected light amount is different from that of the barge portion 11a and the base material portion. 12a
become that way. The difference is the direction in which the angular distribution peaks,
That is, it is observed from the regular reflection direction. When the area ratio of the tempered portion of the barbed portion is larger than the base material portion (FIGS. 16a, b, 17a,
(corresponding to b), the barb looks bright from the specular reflection direction, and conversely, if the temper ratio of the barge portion is smaller than the base material portion, the barge is observed dark from the specular reflection direction.

When there is no difference in the temper area ratio (the above ((
In case c)), the scab cannot be seen by observation from the steel plate regular reflection direction. Nevertheless, when there is a difference in the diffusivity of the specular diffuse reflection component, flaws are observed from the diffusion direction deviating from the peak of the angular distribution as shown in FIG. For example, when the diffusivity of the specular diffuse reflection component is small, the barb is generally observed brightly from the diffusion direction relatively close to the specular reflection, and the brightness decreases as the distance from the specular reflection direction increases, and the barge and the barge at a certain angle. The difference between the base material portions disappears, and observation becomes impossible at angles before and after the difference. Further away from the specular reflection, the balding is observed darker.

In order to discriminate and detect such pattern-like barbed flaws from the base material portion, it is necessary to examine at what angle the reflected light from the minute surface element is extracted in FIG. is there. For example, as in the examples of FIGS. 16 (a) and 16 (b), detecting the difference between the barb portion and the base material portion in the regular reflection direction is equivalent to the angular distribution of the micro surface element shown in FIG. Ξ = 0 is extracted, and the difference between the barb portion and the base material portion is detected.

When mathematically expressing that extraction is performed for ξ = 0, each of the functions S (図) shown in FIG. 17 is extracted as a delta function δ (ξ) shown in FIG. This is equivalent to multiplying by a function representing characteristics (hereinafter referred to as a weighting function) and integrating. Further, for example, measuring at a position of 40 degrees, which is 20 degrees from the regular reflection, at the incident angle 60 means detecting reflection by a plane (small plane element) whose normal angle ξ is shifted by 10 degrees. . This is shown in FIG.
This corresponds to the use of the weight function δ (ξ + 10) as shown in FIG. Note that the relationship between the reflection angle and the normal angle ξ of the micro surface element is calculated from FIG.

In this way, it can be understood that the angle at which the reflected light from the minute surface element is extracted corresponds to what weight function is designed. The weight function does not necessarily need to be a delta function, and may have a certain width.

From this point of view, FIG.
Considering a weight function for discriminating and detecting a barbed flaw having an area ratio distribution as shown in (b) and (c) from the base material, the δ function δ (ξ) shown in FIG. This is one example. However, in this case, since the cameras are installed at different light receiving angles, the two optical systems cannot have the same visual field size. Also, once a camera is installed to measure diffuse reflected light, it is not easy to change the weight function because it is necessary to change the installation position of the camera.

For the former problem, measurement on the same optical axis is required. Therefore, it is desirable that both the specular reflection component and the specular diffuse reflection component be detected by measurement from the steel plate regular reflection direction instead of capturing the diffuse reflection light. For the latter, it is desirable that the weighting function can be set with a certain degree of freedom with respect to a change in the installation position of the camera.

For this purpose, in the present invention, a linear light source having a diffusion characteristic is used as a light source instead of a parallel light source such as a laser. Also, the specular reflection component and the specular diffuse reflection component are separated and extracted from the steel plate regular reflection direction by using polarized light.

In order to explain the function and effect of this linear diffused light source, first, as shown in FIG.
4 is arranged parallel to the steel plate 4 and is in a plane perpendicular to the light source,
Consider a reflection characteristic when one point on the steel plate 4 is observed from a direction in which the incident angle coincides with the emission angle (hereinafter, referred to as a steel plate regular reflection direction).

Now, as shown in FIG. 20A, in the case of light emitted from the central portion of the linear light source 14, the light incident on the temper portion is reflected specularly, and is all captured in the steel plate regular reflection direction. Can be On the other hand, the light incident on the non-tempered portion is specularly reflected, and only the light reflected by the minute surface element that happens to be oriented in the same direction as the normal direction of the steel sheet is captured. Since such a small surface element is very small in probability, the specular reflection from the temper portion becomes dominant in the reflected light captured in the steel plate regular reflection direction.

On the other hand, as shown in FIG.
In the case of light emitted from other than the center of the linear light source, the light incident on the temper portion is specularly reflected and reflected in a direction different from the steel plate regular reflection direction, and cannot be captured in the steel plate regular reflection direction. On the other hand, the light that has entered the non-tempered portion is specularly reflected, and the light reflected in the regular reflection direction of the steel plate is captured. Therefore, all the reflected light captured in the steel plate regular reflection direction is specular diffuse reflection light reflected at the non-tempered portion.

When the above two cases are combined, the light radiated from the entire linear light source can be captured by observing from the regular reflection direction of the steel sheet as follows: specular reflection light from the tempered portion and specular diffusion from the non-tempered portion. It is the sum of the reflected light.

Next, how the polarization characteristics change when the surface to be inspected is observed from the specular reflection direction using the linear light source will be described.

In general, when light is reflected on a mirror-like metal surface, polarization characteristics are preserved by reflection of light whose direction of the electric field is parallel to the incident surface (p-polarized light) or light perpendicular to the incident surface (s-polarized light). The light is emitted as p-polarized light or s-polarized light. Also, arbitrary linearly polarized light having both p-polarized light component and s-polarized light component is emitted as elliptically polarized light according to the reflectance ratio of p and s-polarized light and the phase difference.

Hereinafter, a case where light is irradiated from a linear diffusion light source to an alloyed galvanized steel sheet will be considered. FIG. 21 (a)
As shown in the figure, the light emitted from the central part of the linear light source 14 is
It is specularly reflected at the tempered portion of the steel plate 4 and is observed in the steel plate regular reflection direction. In this regard, reflection on the above-mentioned general mirror-like metal surface is established as it is, and p-polarized light is emitted as p-polarized light.

On the other hand, as shown in FIG. 21 (b), light emitted from portions other than the central portion of the linear light source is specularly reflected by a tilted minute surface element of the crystal surface of the non-tempered portion, and is specularly reflected by a steel plate. Some are observed in the direction. At this time, even if p-polarized light parallel to the incident surface of the steel plate is incident, the light is not parallel to the incident surface for the inclined minute plane element that is actually reflected. It becomes linearly polarized light. As a result, the incident light is emitted as elliptically polarized light from the minute surface element. Here, the same applies when s-polarized light is incident instead of p-polarized light.

In addition, regarding linearly polarized light having an arbitrary polarization angle having both p and s polarization components, the polarization angle is tilted with respect to the incident surface for a small plane element tilted for the same reason as described above. Therefore, the shape of the elliptically polarized light emitted in the regular reflection direction of the steel sheet is different from the light that enters from the center of the linear light source and is specularly reflected by the temper portion.

Hereinafter, a case where linearly polarized light having both p and s components is incident will be described more specifically.

First, as shown in FIG. 22, the light 8 from the linear diffused light source 14 is linearly polarized by a polarizing plate 15 having an azimuth angle α, then is incident on a horizontally placed steel plate 4, and its regular reflection is performed. Consider that light is received by the photodetector 16.

As described above, with respect to the light 8 emitted from the point C on the light source, the component reflected specularly by the tempered portion and the minute surface element whose normal line happens to be vertical in the non-tempered portion happened. Is reflected from the point O (and, as a result, the surrounding area 13) on the steel plate,
6 contributes to the light reflected in the direction.

On the other hand, as shown in FIG. 23, for the light 8 from the point A shifted by an angle φ when viewed from the point O, the specular reflection component is reflected in a direction different from that of the photodetector 16. Normal angle ξ (the angle of the normal to the vertical direction is ξ)
Only the specular diffuse reflection component due to the micro-plane element contributes. Here, the relationship between φ and ξ is given by the following equation based on simple geometric considerations. cosξ = ² cos θ · cos ² (φ / 2) / [sin ² φ + 4 · [cos ² θ · cos ⁴ (φ / 2) + sin ² θ · sin ⁴ (φ / 2)]] ^1/2 (1 Where θ is the angle of incidence on the steel plate.

Next, the polarization state of the light reflected as described above will be considered. In FIG. 22, the light 8 emitted from the point C passes through the polarizing plate 15 having the azimuth angle α, and after being specularly reflected at the point O, the polarization state is determined using a Jones matrix generally used in polarization optics. E _c = T · E _in (2) Here, E _in represents a linear polarization vector (column vector) having an azimuth α, and T represents a reflection characteristic matrix of the steel plate. Each component is as follows. ^{_{E in = Ep · t (cosα}} , sinα) T = r s (T mn); T 11 = tanΨ · exp (jΔ), T 22 =
1, T ₁₂ = T ₂₁ = 0

Where ^t () is a column vector and tanΨ is p ·
The amplitude reflectance ratio of s-polarized light, Δ represents a phase difference caused by the reflectance of p · s-polarized light, and r _s represents the s-polarized light reflectance. Note that these matrix expressions are as shown in Equation 1.

(Equation 1)

Similarly, in FIG. 23, the light 8 emitted from the point A is
The polarization state of light reflected in the direction of the photodetector 16 by the small plane element having the normal angle ξ is E _A = R (ξ) if the incident surface is orthogonal to the polarizer 15 and the analyzer 17. ) · T · R (−ξ) · E _in (3) where R is a two-dimensional rotation matrix of the angle ξ, and its component R _mn is as follows. R ₁₁ = R ₂₂ = cosξ, R ₁₂ = -R ₂₁ = -sinξ

The matrix expression of R (ξ) is as shown in Expression 2.

[0058]

(Equation 2)

Equation (2) is a special case where ξ = 0 in equation (3), and both the specular reflection component and the specular diffuse reflection component can be uniformly considered using (expression 3). .

Calculating equation (3) and illustrating the elliptically polarized state of the reflected light from the micro-plane at the normal angle ξ, the result is as shown in FIG. Here, the azimuth angle α of the incident polarized light is 45 degrees, the incident angle θ is 60 degrees, and the reflection characteristics of the steel sheet are Ψ = 28 ° and Δ = 120.
°. From the figure, it can be seen that the ellipse inclines as the value of ξ changes with respect to the ellipse in the case of ξ = 0, ie, specular reflection. Therefore, for example, by inserting an analyzer in front of the photodetector and setting the angle of the analyzer, it is possible to select which normal angle to extract more reflected light from the microscopic surface element.

[0061] To quantify this, when obtaining the polarization state E _D after the insertion of the analyzer of the light detecting angle β to the reflected light of the polarization state represented by the formula (3), E _D = R (β) · a · R ( -β) · E a = R (β) · a · R (-β) · R (ξ) · T · R (-ξ) · E in (4) to become. Here, A = (A _mn ) is a matrix representing an analyzer, A ₁₁ = 1, and other components are 0. Note that the matrix representation of A is as shown in Equation 3.

[0062]

(Equation 3)

Is as follows. From equation (4), the light intensity L of the reflected light from the microscopic surface element having the normal angle ξ detected by the photodetector 16 (FIG. 23)
Calculating the, the area ratio of the micro-area element as S (ξ), L = S (ξ) · | E D | 2 = r s 2 · Ep 2 · S (ξ) · I (ξ, β) I (ξ, β) = tan ² Ψ ・ cos ² (ξ-α) ・ cos ² (ξ-β) +2 ・ tanΨ ・ cosΔ ・ cos (ξ-α) ・ sin (ξ-α) ・ cos (ξ-β ) · Sin (ξ-β) + sin ² (ξ-α) · sin ² (β-ξ) (5). Here, as described above, I (ξ, β) is a weighting function indicating how much the reflected light from the microscopic element having the normal angle ξ can be extracted, and depends on the polarization characteristics of the optical system and the subject. . And the reflectance r _s ^{2 of} the steel plate, the incident light amount Ep ² ,
The product of the area ratio S (ξ) is the detected light intensity.
When considering a target having a uniform material on the surface of the steel sheet, such as a surface-treated steel sheet, the value of r _s ² is considered to be constant. Also, E
p ² may be a constant value if the amount of incident light is uniform regardless of the position of the light source. Therefore, in order to obtain the light intensity detected by the photodetector, it is sufficient to consider the area ratio S (面) of the microplane at the normal angle ξ and the extraction characteristic I (ξ, β).

First, the extraction characteristic I (ξ, β) will be considered. If the contribution from the small-area element of the normal angle xi] ₀ tries to select a Kenhikarikaku beta ₀ as most increases, the candidate is given by solving the following equation beta. [∂I (ξ, β) / ∂ξ] ξ = ξ 0 = 0 (6)

A general mathematical expression of this expression is shown in Expression 4.

[0066]

(Equation 4)

From the above equation (6), when the analysis angle at which ξ = 0, that is, the contribution of the specular reflection component becomes the largest, is obtained, β
Is about -45 degrees. However, also here, as the reflection characteristics of the steel sheet, Ψ = 28 °, Δ = 120 °, and the azimuth α of the polarizer α = 45 °
And FIG. 25 shows the relationship between the angle ξ formed by the normal line of the minute surface element with respect to the vertical direction and the extraction characteristic, that is, the weight function I (ξ, -45) when the analysis angle β is −45 degrees. However, the maximum value is normalized to 1 for easy viewing.

From FIG. 25, ξ = 0, ie, the specular reflection component is the most dominant (easy to extract), and conversely, the normal angle ξ = ± 3
It can be seen that the specular diffuse reflection light from the microscopic element near 5 degrees is least extracted. Conversely, when the analysis angle β that best extracts the reflected light of ξ = ± 35 degrees is obtained from Expressions (5) and (6), approximately β = 45 degrees. FIG. 26 shows the relationship between the normal angle ξ and the extraction characteristic I (ξ, 45) for the analysis angle β = 45 degrees. Here, the reason why the curve of β = 45 degrees is not symmetrical is that, when considering the incident surface (the plane spanned by the incident light and the reflected light with respect to the minute surface element) as a reference, when ξ is positive, the apparent polarization of the incident polarized light is considered. This is because the azimuth angle α becomes smaller (approaches p-polarized light) and the p-polarized light reflectance of the steel sheet is smaller than the s-polarized light reflectance. Also,
The figure also shows β = 90 °, which is a characteristic intermediate between β = −45 ° and 45 °.

As shown in the equation (5), the reflected light intensity L from the microscopic surface element having the normal angle は is calculated based on the extraction characteristic (weight function) I (ξ,
β) and the area ratio S (ξ), the light intensity finally received by the photodetector 16 is S (ξ) ・ I (ξ,
β) is integrated over ξ. For example, when light reflected from a steel plate having a reflection characteristic as shown in FIG. 27 is received through an analyzer having an analysis angle β of −45 degrees, the area ratio S (ξ) shown in FIG. Extraction characteristics I (ξ,
The value obtained by integrating with weighting β) is the amount of received light.

Let us consider a case where there is a pattern-shaped barbed flaw having a characteristic as shown in FIG. 16 on the steel sheet surface. Area ratio in that case
S (ξ) is as shown in FIGS. 17 (a), (b) and (c), respectively.

First, consider the case where there is a difference only in the specular reflection component as shown in FIGS. 16 (b) and 17 (b). The light intensity when such a flaw is received through an analyzer having an analysis angle β = −45 degrees is obtained by integrating FIG. 17 (b) by applying a weight function I (ξ, β) shown in FIG. 25. Therefore, it is possible to detect a difference in the amount of reflected light between the base material portion and the barb portion. As for the analysis angle β = 45 degrees, there is no difference in the specular diffuse reflection component as shown in FIG. 17 (b), and there is a difference only in the vicinity of ξ = 0 ゜. Given that the weight function I ((, β) of β = 45 ゜ is low near ξ = 0 ゜, the product is ξ
Is low in the entire region of, and the difference is canceled by the integration. Therefore, it is not possible to detect a difference between the base material portion and the barb portion.

When only the specular diffuse reflection component is different as shown in FIGS. 16 (c) and 17 (c), conversely, it cannot be detected by passing through a -45 degree analyzer. In this case, it can be detected by passing through a 45-degree analyzer where the weighting function I (ξ, β) shows a high value at a distance from ξ = 0 ゜.

By the way, the normal angle て い る at which the difference in the specular diffuse reflection component between the base material portion and the balding portion disappears is about ξ = ± 20 degrees in FIG. 17 (c). If there is a flaw whose line angle ξ happens to be around ± 30 degrees, it cannot be detected even through a 45-degree analyzer. In that case, another analyzer having an analysis angle (for example, β = 90 °) having another extraction characteristic may be separately prepared, and may be received by the third photodetector.

Generally, the reflection characteristics of the base material and the barb on the surface of the steel sheet are almost any of those shown in FIGS. 10 (a), 10 (b) and 10 (c). (In this example, the detection angle), detection can be performed in most cases. However, in the special case as described above, in order to eliminate the oversight, the analyzer uses three analyzers having different analysis angles, and extracts and receives the reflected light from the micro surface element having the corresponding three normal angles. It is desirable to do so.

When there is a difference between the specular reflection component and the specular diffuse reflection component as shown in FIGS. 16 (a) and 17 (a),
Basically, it is possible to detect the difference between the base material portion and the barb portion only by the reflected light passing through one analyzer.

Here , an incident polarizer is arranged on the entire surface of the linear diffused light source, and the azimuth angle of the polarized light is set to include both p-polarized light and s-polarized light. Then, a camera that captures an image through a polarizer having a polarization angle that more transmits the specular reflection component of the specular reflection light and a camera that captures an image through a polarizer having a polarization angle that transmits the specular diffuse reflection component more is used.

With such an optical system, measurement is performed on a common optical axis from the specular reflection direction, so that it is possible to cope with both specular reflection and specular diffuse reflection without being affected by fluctuations in the steel sheet distance or speed. Two signals,
A surface flaw inspection device capable of detecting a pattern-shaped bald flaw having no remarkable unevenness without causing undetection is realized. The angle of the specular diffuse reflection component to be detected can be easily changed by setting the analysis angle.

By measuring the intensity or ratio of specular reflection and specular diffuse reflection as described above, it is possible to detect a change in surface texture that affects specular reflection or specular diffuse reflection, in addition to the above-mentioned patterned barbed flaw. . For example, the surface finish of a metal band such as dull finish or hairline finish can be detected in principle if there is a change in the distribution of minute reflecting surfaces, and application to inspection of these surface properties can also be expected. . According to the invention, dull finish is applied to the metal strip.
Or 2 different from the metal surface with hairline finish
Reflection from the metal surface separated by more than one optical condition
In response to abnormal parts where the combination of components is different from the normal part,
The metal surface is used to provide information about the abnormal part.
Characterized by a marked marking
It becomes a metal band with a ring.

It goes without saying that a known method and means may be used in combination with the apparatus of the present invention for the detection and determination of surface flaws. This will be described later in detail.

As described above, the position of the surface to be inspected determined to have a surface flaw is tracked by the tracking means. Tracking can be performed by calculating the time at which the position of the surface flaw reaches the marking means from the transport speed of the metal strip. The marking means is based on a marking instruction from the tracking means,
Marking is performed on the surface of the metal strip.

The marking can be performed by various methods according to the purpose and use. This may be any marking method that is easy to detect in the next step, such as printing with ink or paint, marking with a stamping machine, punching with a punch, modification of surface roughness with a grinder, etc., or metal band. When is a ferromagnetic material, it is performed by a predetermined method such as magnetic marking.

The positions of the markings may coincide with the positions of the surface flaws, but may be coincident only in the longitudinal direction without being coincident in the width direction. For example, when a material is automatically charged into a press line or the like, it may be easier to detect the marking if the position of the marking is rather constant in the width direction.

The metal strip with marking of the present invention extracts reflected light from the surface to be inspected of the metal strip under two or more different optical conditions, and based on a combination of the reflected components extracted under these different optical conditions. It can be manufactured by a method for manufacturing a metal strip with a mark, characterized in that the presence or absence of a surface flaw on the inspection surface is determined, and a marking indicating information on the flaw is provided on the surface of the metal strip .

According to this method, marking is performed on the surface of the metal strip at a portion determined to have a surface flaw by the above-described surface flaw determination method. Since the marking indicating the presence of the surface flaw is given in this way, it becomes possible to remove the surface flaw portion in a subsequent process or in a consumer, and it is possible to prevent the surface flaw from slipping into the product. Further, according to this manufacturing method, after the metal strip is manufactured, operations such as coil division for removing surface flaws can be greatly simplified or omitted, so that production efficiency is improved.

Further, light reflected from the surface to be inspected of the metal strip is extracted under two or more different optical conditions, and the surface flaw of the surface to be inspected is determined based on a combination of the reflection components extracted under these different optical conditions. A step of determining the presence / absence, a step of marking the surface of the metal strip with information relating to the flaw, a step of winding up the marked metal strip to form a coil, and rewinding the coil to perform marking. Having a step of detecting, a step of avoiding or removing a predetermined range of the metal band based on the information indicated by the marking, and a step of performing predetermined processing on the remaining part of the metal band that has not been avoided or removed. It can also be manufactured by a method of processing a metal strip characterized by the following.

In this method, after marking the metal band surface, the metal band is wound into a coil. The wound coil is transported to a factory or the like to form a thin plate. At the time of molding, the coil is rewound in advance, and the marking is detected visually or by a simple detector or the like.
When the marking is detected, a defective portion including a flaw in the metal band is avoided or removed from the information indicated by the detection.

Here, the range of the defective portion is, for example, the portion where the marking is applied in the case where the marking is applied in accordance with the position of the flaw, and the marking includes information such as the type and degree of the flaw. If so, it is determined based on the type and degree of flaws that are defective in the molding process. In addition, avoiding or removing a predetermined range of the metal band means cutting and removing a defective portion of the metal band, or adjusting a feeding amount (feed) of the metal band to a processing step. Is to control the supply of the metal band to the processing step so that the defective portion is not processed, for example, by passing (passing) the defective portion.

In the metal band of the present invention , markings indicating information on the flaws are given to the surface of an abnormal portion in which a combination of reflection components from the surface separated under two or more different optical conditions is different from a normal portion. A metal strip with a marking.

As described above, the metal strip of the present invention is marked on the portion determined to be different from the normal portion by the optical analysis of the surface, that is, the position of the surface flaw. Therefore, as described above, it is possible to remove the abnormal portion and prevent the metal band from being mixed in the product in a post-process using the metal band and in a consumer.

The metal band according to the present invention relates to the surface of a portion where the amount of light of one or both of the specular reflection component from the surface and the specular diffuse reflection component due to a plurality of minute specular reflection surfaces becomes abnormal. It is a metal band with a marking, which is provided with a marking indicating information.

In the metal band according to the present invention, when the state of the specular reflection or the specular diffuse reflection from the surface is different from that of the normal part, the marking is applied to the position. Here, the specular diffuse reflection is, as described above, a surface on which a large number of minute specular reflection surfaces whose normals are directed to a specific direction are distributed. As in the case of the above-described invention, when this metal band is used, the treatment of an abnormal portion becomes easy.

According to the present invention, a plurality of surface flaw inspection means including a surface flaw inspection means having a light receiving section and a signal processing section, and the inspection results of the metal band surface flaws are comprehensively determined. And a marking information creating means for creating marking information related to the surface of the metal strip.

This apparatus detects the size and shape of flaws and dirt, the reflectance of irradiated light, and the like in addition to the surface flaw inspection means having a light receiving unit and a signal processing unit. By combining ordinary surface inspection means for inspecting property abnormalities, the type and degree of surface flaws and other abnormal parts are classified. This makes it possible to make a comprehensive judgment on various surface property abnormalities including abnormalities of specular diffuse reflection, and to mark information on those abnormalities.

Further, based on the inspection results by a plurality of surface inspection methods including a surface inspection method for inspecting a surface to be inspected based on a combination of reflection components extracted under two or more different optical conditions, surface defects are determined. The method for producing a metal band with a metal band marking according to the second aspect of the invention, which is characterized by determining the presence or absence of the metal band, can be used .

In this method, the reflected light from the inspected surface of the metal strip is extracted under two or more different optical conditions, and a surface defect for inspecting the inspected surface based on a combination of these extracted reflected components. In addition to the above inspection method, the type and degree of surface flaws are classified by combining ordinary surface inspection methods. Here, the normal surface flaw inspection method is, for example, a surface inspection method for detecting the size and shape of a flaw, the reflectance of irradiation light, and the like, and inspecting an abnormality of the surface property such as a flaw or dirt. In this way, comprehensive judgment is made on various surface property abnormalities including abnormalities of specular diffuse reflection, and information on those abnormal parts is marked.

[0096] Further, the surface defects involving abnormal portion different from the combinations normal part of the reflected component from the surface being separated by two or more different optical conditions, with markings indicating the information about the scratches on the surface is subjected The fourth feature is that
It is good also as the metal band with a marking of this invention.

In addition to the above-mentioned abnormal portions, the metal strip of the present invention has a normal surface flaw inspection, for example, a result of a surface inspection based on the size and shape of the flaw or the reflectance of irradiation light or information on various surface properties. Are marked on the surface. Here, the abnormal portion is a portion where the intensity or ratio of the reflected component is different from the normal portion when the reflected light is separated under two or more kinds of optical conditions as described above.

Further , information on the surface of the metal strip including a portion where the light amount of one or both of the specular reflection components from the surface and the specular diffuse reflection components due to a large number of minute specular reflection surfaces becomes abnormal is described. In addition, a marking indicating the information on the surface of the metal band may be provided on the metal band.

The metal strip according to the present invention can be used for normal surface flaw inspection, for example, information on surface inspection results based on the size and shape of flaws, the reflectance of irradiation light, and various surface properties, in addition to the above-mentioned abnormal parts. Are marked on the surface. Here, the abnormal part is a part where the state of specular reflection or specular diffuse reflection from the surface is different from the normal part as described above, and when the reflected light is separated under two or more types of polarization conditions, The intensity or ratio of the component can be determined as a part different from the normal part.

According to the above invention, various surface defects including abnormalities of specular diffuse reflection or abnormal portions of surface properties can be
Since the marking indicating the information is provided on the surface of the metal strip, it becomes possible to know the type and degree of the surface flaw in a post-process or in a consumer, and it is possible to cope with various uses and usage purposes.

Also, by marking the surface of the metal band as described above, the metal band can be wound up without cutting and removing the surface flaws and the like, and the number of coils increases by cutting and removing. Can be prevented. As described above, since the number of coils does not increase, in the handling of the coil, an increase in trouble of winding is prevented. Further, in the transport, unwinding and processing of the coil, the number of coils to be processed does not increase, so that the handling effort is reduced.

[0102]

FIG. 1 is a block diagram showing an example of an apparatus used in an embodiment of the present invention. The surface flaw detection device 41 extracts reflected light from the surface to be inspected of the metal strip 4 under two or more different optical conditions, and the signal processing unit 30
The presence or absence of a surface flaw on the surface to be inspected is determined based on a combination of these reflection components.

The tracking means 43 calculates the time when the position of the surface flaw reaches the marking means. This is based on the rotation speed measured by the tachometer 46 attached to the transport roll 45, the length of the surface flaw is converted to the plate length by the plate length calculation means 47, the time required to reach the marking means 44 It is obtained by conversion. At that time, the tracking means 43 sends a signal instructing the marking means 44 to perform marking. The marking means 44 performs marking such as printing and punching on the surface of the metal band.

FIG. 2 shows an example of a marked metal band. In this example, the position of the marking 49 is made coincident with the position of the surface flaw 11 in the longitudinal direction, and is fixed from the edge in the width direction. Thus, when used in a press line or the like, it is possible to detect the marking 49 at a fixed position from the edge regardless of the position of the surface flaw 11, and to take measures such as rejection of a part having the surface flaw 11. This makes it possible to prevent defective products from being manufactured.

FIG. 3 and FIG. 4 show an example of the surface flaw detection device 41. As the linear diffusion light source 22, a transparent light guide rod partially coated with a diffuse reflection paint is used, and light from a metal halide light source is incident from both ends thereof. Light diffusely emitted from the light guide rod of the light source 22 is transmitted to the cylindrical lens 25.
After passing through the polarizing plate 26 of 45 ° polarization, the steel plate
The light is converged and incident on a straight line over the entire width of 21. The reflected light 27 is further reflected by the mirror 28 arranged in the steel plate regular reflection direction, and enters the camera units 29a to 29d constituting the light receiving unit.

These camera units 29a to 29d are arranged in the board width direction as shown in FIG. By using the mirror 28 in this way, the device can be made compact. In addition, if the mirror 28 is installed at an appropriate distance from the steel plate 21, an area (outside the field of view of all cameras) is generated on the mirror 28 as shown in FIG. 5, and the mirror may be divided and configured. it can. By dividing the mirror in this way, the production cost can be kept low.

As shown in FIG. 6, the camera units 29a to 29d of the light receiving section are composed of three linear array cameras having analyzers 33a to 33c of -45 °, 45 °, and 90 ° in front of the lens. 32a to 32c, the optical axes of which are kept parallel. The deviation of the visual fields of the three cameras is corrected by the signal processing unit 30. When the optical axes are kept parallel in this way, three cameras 32a
Each pixel of ~ c has the same visual field size and corresponds one-to-one. Further, compared to splitting one reflected light using a beam splitter, loss of light quantity is eliminated, and efficient measurement can be performed.

The light receiving range A of each of the light receiving cameras 32a to 32c in each of the camera units 29a to 29d is, as shown in FIG. 5 described above, the corresponding light receiving camera in the other camera units 29a to 29d adjacent on both sides. They are arranged so as to partially overlap the light receiving range A of 32a to 32c. In other words, the reflected light from any position in the width direction on the steel plate 21 is at least 1 each.
Three types of light receiving cameras 32a in one camera unit 29a to 29d
In this case, a two-dimensional CCD camera can be used in the light receiving unit instead of the linear array camera. In the light emitting section, a fluorescent lamp can be used as the linear diffusion light source 22. Further, a fiber light source in which the output ends of the bundle fiber are aligned in a straight line can be used. This is because the light emitted from each fiber has a sufficient divergence angle corresponding to the N / A of the fiber, and the fiber light source in which the light is aligned substantially becomes a diffusion light source.

Here, the arrangement of a plurality of cameras is illustrated in FIG.
The details will be described with reference to FIG. Each camera unit 29a ~
In 29d, a plurality of units are arranged at regular intervals. One camera unit 29a to 29d operates under different conditions (-45, 45, 90
(Polarized light). Each camera is set up in parallel at regular intervals. Therefore, the respective visual fields are shifted by the same amount as the camera interval.

The order of cameras in each camera unit is the same. For example, the order is 45 degrees, 90 degrees, and -45 degrees from the left. The measurement range (effective area) is, for example,
The range observed under three conditions, only one condition, or
Regions observed only under two conditions (regions at both ends)
Is invalid and not used. The camera interval and the unit interval are determined as dimensions such that the maximum width of the steel sheet falls within the measurement range (effective area).

The three cameras in each unit are not adjusted to have the same field of view. After determining the flaw candidate area in each camera, the correspondence of each camera is determined in units of the flaw candidate area.
As described above, since the field of view of each camera is shifted, three cameras that can fit a certain flaw candidate area into the field of view may not be aligned (the three optical conditions may not be aligned). In that case, use the results of the camera of the next unit to
Prepare for 3 conditions. This concept is applicable not only to the case where three polarized lights are received but also to the case where the whole width of the test object is divided into a plurality of visual fields and observation is performed under arbitrary two or more conditions.

If the plurality of light receiving sections and the signal processing section are collectively referred to as flaw inspection means, the surface flaw marking apparatus shown in FIG. 1 is as shown in FIG. The flaw inspection means 40 includes light receiving sections 32a to 32c (corresponding to the cameras in FIGS. 5 and 6).
And a signal processing unit 30. The signal processing unit 30 detects the above-mentioned diffuse mirror reflection component by signal processing based on the intensity of the reflected light extracted under different optical conditions, and determines whether there is an abnormal part. After that, as in FIG. 1, the tracking means 4
3 and the position of the surface flaw is calculated by the plate length calculating means 47,
The marking means 44 performs marking at the position of the abnormal part.

FIG. 8 is a block diagram showing an example of the signal processing section. Light intensity signals a to c from the light receiving cameras 32a to 32c
Are input to the average value thinning units 34a to 34c, and the average value is calculated. Next, the pulse signal is input as the test object moves by a predetermined distance in the longitudinal direction, and is output as a signal for one line in the width direction. By this thinning process, the resolution in the longitudinal direction is made constant. In addition, the calculation frequency of the average value, the moving distance in the longitudinal direction of the test object is the light receiving cameras 32a to 32c.
If it does not become larger than the field of view, oversight can be eliminated.

Next, the pre-processing units 35a to 35c correct luminance unevenness of the signal. Here, the luminance unevenness includes one caused by the optical system, one caused by the reflectance of the test object, and the like. Further, the pre-processing units 35a to 35c detect the position of the edge of the metal band and perform processing for preventing a sudden signal change in the edge from being erroneously recognized as a flaw.

The preprocessed signals are converted into binary processing units 36a to 36c.
And a flaw candidate point is extracted by comparison with a preset threshold value. The extracted flaw candidate points are input to the feature calculation units 37a to 37c, and signal processing for flaw determination is performed. Here, when the flaw candidate points are continuous, position feature amounts such as a start address and an end address, a peak value thereof, and other density feature amounts are calculated as one flaw candidate region.

These calculated feature amounts are input to the specular flaw judgment unit 38a or the specular diffuse flaw judgment unit 38b according to the optical conditions (analysis angle β) of the original signals a to c.
The output of the feature value calculation unit 37a indicates that the optical condition of the original signal a is -45.
Degree analysis (β = -45 °). Therefore, in this case, the difference is input to the specular flaw determining unit 38a, and as described above, the difference in the amount of reflected light between the base material portion and the barb portion due to the specular reflection component is detected. On the other hand, the output of the feature calculation units 37b and c is such that the optical conditions of the original signals b and c are 45 degrees and 90 degrees analysis (β = 45 ゜ 90 ゜), and there is a difference only in the specular diffuse reflection component. . Therefore, the specular diffusible flaw determination unit 38
The defect is input to b and the flaw determination is performed based on the specular diffuse reflection component.

Finally, the flaw comprehensive judgment section 39 calculates the flaws based on the outputs of the specular flaw judgment section 38a and the specular diffuse flaw judgment section 38b.
For the inspection surface of the metal strip, the final flaw type and its degree are determined. Also, at this time, considering the overlap of the visual field between the cameras 32a to 32d and between the camera units 29a to 29d (FIG. 5), it is possible to appropriately use the flaw determination result based on the signal from the camera of the adjacent camera unit. desirable.

FIG. 9 shows an example in which such a surface flaw inspection means for detecting an abnormality of the specular diffuse reflection component to judge a flaw is combined with a surface flaw inspection means by another method. Here, the surface flaw inspection means 40a is the same as that shown in FIG. 7, extracts the reflected light under different optical conditions at the plurality of light receiving units 32a to 32c, and at the signal processing unit 30, the abnormalities of the specular diffuse reflection component are detected. Is detected to determine the flaw.

As the surface inspection means 40b of another method, a normal surface flaw inspection means, that is, an apparatus of a method of detecting and determining a surface flaw from the size and shape of the flaw, or a method of detecting a surface flaw based on the reflectance of irradiation light or the like is used. An apparatus of a type for detecting dirt and attached matter can be used. The surface inspection means 40b classifies types and degrees of normal surface flaws and abnormalities in surface properties. In the marking information creating means 42, the inspection means 40a,
Based on the inspection result of 40b, comprehensive classification and ranking are performed for various surface flaws and surface property abnormalities including abnormalities of specular diffuse reflection, and information for marking is created.

Thereafter, as in FIG. 1, the tracking means 43
The position of the surface flaw is calculated by the plate length calculating means 47.
The marking means 44 performs marking at the position of the abnormal part based on the marking information. At this time, it is desirable to indicate information on the type and degree of the surface flaw. This may be any form that can be detected, such as the marking pattern, shape, and band width. If barcode or OCR (optical character reading) is used in combination, more detailed information can be marked.

As described above, the marking on the surface of the metal band suppresses an increase in the number of coils, so that the efficiency of work can be improved even in handling such as coil winding, coil transportation, and rewinding. Is improved.
Also, in the processing of the metal band, the metal band is continuously supplied without interruption at the flaws, so that an increase in work efficiency can be expected.

[0122]

EXAMPLE The measurement results of the galvanized steel sheet according to the embodiment of FIG. 3 are shown in FIGS. FIG. 10 shows the aforementioned FIG. 17 (b)
FIG. 11 corresponds to FIG. 17 (c).
As shown in Fig. 0, the area ratio of the tempered portion is larger than that of the base material portion in the barbed portion, but the diffusivity of the non-tempered portion does not change.
(FIG. 17b) and a flaw (FIG. 17c) having a difference in diffusivity although there is no difference in the temper area ratio as shown in FIG. Figure 1
Regarding the type 1 flaw, there is generally an undetectable angle in the diffuse reflection direction, but two types of flaws having different angles were measured. For comparison, in the conventional technology, light was incident at an incident angle of 60 °, and the result was measured without polarization from the specular reflection direction (60 °) and the light receiving angle (-40 °) direction shifted by 20 ° from the incident direction. Are also shown in the figure. The above results are summarized in Table 1.

[0123]

【table 1】

In the prior art, light is received at two light receiving angles and the logical sum is taken for noise removal. However, it is impossible to detect these flaws simultaneously at the two light receiving angles. Furthermore, there are flaws that cannot be detected at either of the light receiving angles.

On the other hand, in the embodiment of the present invention, the reflected light components corresponding to the three different light receiving angles are extracted from the specular reflection direction by using the analyzer. Is possible. Also,
It is also easy to optimally set the analysis angle in accordance with the reflection characteristics of the flaw that needs to be detected.

[0126]

As described above, the present invention provides a method for extracting and capturing each component based on the knowledge that reflection on the surface of a steel sheet is composed of a specular reflection component and a specular diffuse reflection component. Using a diffused light source, a polarized light having both p-polarized light and s-polarized light is incident on the surface to be inspected, and by appropriately setting the analysis angle from the direction of the regular reflection of the steel sheet, a component containing more specular reflection components is And a method of extracting a component containing more specular diffuse reflection components.

This method makes it possible to detect a flaw in which no flaw can be observed from the specular reflection component, and it is possible to detect a pattern-shaped scorch flaw having no noticeable unevenness, which could not be detected conventionally, without undetecting it. became. In addition, since both components are captured by measurement on the same optical axis from the steel plate regular reflection direction,
Measurements that are not affected by changes in steel plate distance or speed are realized. Further, by setting the analysis angle, it is possible to select at which angle the specular diffuse reflection component is extracted.

From the viewpoint of quality assurance, it is an absolute condition that such a surface inspection apparatus has no undetection. According to the present invention, a surface flaw marking apparatus using a surface flaw inspection apparatus without undetection that can be widely applied to a surface-treated steel sheet and the like and the production of a metal band with a marking can be realized. In addition to being able to automate the surface flaw inspection, it is possible to notify the information to a post-process and a user side by simple means, and the industrial use effect is great.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of an apparatus used in the present invention.

FIG. 2 is a plan view showing one example of a metal strip of the present invention.

FIG. 3 is a schematic view showing an example of a schematic configuration of a surface flaw inspection device of the device used in the present invention.

FIG. 4 is a schematic cross-sectional view of the surface flaw inspection device.

FIG. 5 is a diagram showing an arrangement of camera units incorporated in the surface flaw inspection apparatus in a metal band width direction.

FIG. 6 is a diagram showing an arrangement of cameras incorporated in one camera unit.

FIG. 7 is a block diagram showing another example of the device used in the present invention.

FIG. 8 is a block diagram illustrating an example of a signal processing unit of the device of the present invention.

FIG. 9 is a block diagram showing still another example of the device used in the present invention.

FIG. 10 shows the relationship between the light intensity signal measured by the apparatus used in the present invention.
FIG.

FIG. 11 is a diagram showing another example of the light intensity signal measured by the device used in the present invention.

FIG. 12 is a diagram showing a method for manufacturing an alloy galvanized steel sheet and a detailed cross section thereof.

FIG. 13 is a schematic cross-sectional view showing a relationship between incident light and reflected light in a tempered portion and a non-tempered portion on the surface of a metal strip after temper rolling.

FIG. 14 is an angle distribution diagram of reflected light in the tempered portion and the non-tempered portion.

FIG. 15 is a cross-sectional view for explaining a generation process of a barbed portion in an alloy galvanized steel sheet.

FIG. 16 is an angle distribution diagram of a specular reflection component and a specular diffuse reflection component in a stub part and a base material part.

FIG. 17 is a diagram showing a relationship between a normal angle of a micro planar element and an area ratio in a barbed portion and a base material portion of a surface to be inspected.

FIG. 18 is a diagram illustrating a relationship between angles of incident light, reflected light, and the like on a microscopic surface element of a surface to be inspected.

FIG. 19 is a diagram illustrating a relationship between a normal line angle of a small surface element and a weight function.

FIG. 20 is a diagram showing a relationship between each incident light from each position of the linear diffused light source and an incident position on a surface to be inspected.

FIG. 21 is a diagram illustrating a polarization state of light reflected from a minute surface element when each incident light of the linear diffusion light source is polarized.

FIG. 22 is a diagram showing reflected light from a minute surface element when incident light from the center of a linear diffused light source is polarized.

FIG. 23 is a diagram showing reflected light from a minute surface element when incident light from a portion other than the center of the linear diffusion light source is polarized.

FIG. 24 is a diagram illustrating a relationship between a normal angle of a microscopic element and an elliptically polarized state of reflected light.

FIG. 25 is a diagram showing a relationship between a normal angle of a small surface element and a weighting function.
(Analysis angle: -45 ゜).

FIG. 26 is a diagram illustrating a relationship between a normal angle of a microscopic element and a weighting function at various analysis angles.

FIG. 27 is a diagram showing a relationship between a normal angle of a small surface element of an inspection surface and an area ratio.

[Description of Signs] 4 Metal strip 6 Tempered part 7 Non-tempered part 8, 24 Incident light 10 Specular diffuse reflection light 11 Abnormal part (severed part) 12 Base material part 14, 22 Linear diffusion light source 15, 26 Polarizer 16 , 32a-c Receiving camera 17, 33a-d Analyzer 21 Steel plate 23 Shading case 24 Incident light 25 Cylindrical lens 26 45 ° polarized polarizing plate 26 27 Reflected light 28 Mirror 29a-d Camera unit 30 Signal processing unit 40a Surface flaw inspection Means 40b Surface inspection means 41 Surface flaw detection device 43 Tracking means 44 Marking means 45 Conveyance roll 46 Tachometer 47 Plate length calculation means 49 Marking

Continuing on the front page (72) Inventor Masakazu Inomata 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Tsutomu Kawamura 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan (72) Inventor Takahiko Oshige 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Hiroyuki Sugiura 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Stock Inside the company (72) Inventor Kazu Tanaka 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Kokan Co., Ltd. (72) Inventor Akira Kazama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (9)

[Claims] A plurality of light receiving units for extracting reflected light from a surface to be inspected of a metal strip under two or more different optical conditions;
A flaw inspection unit having a signal processing unit for determining the presence or absence of a surface flaw on the surface to be inspected based on a combination of the reflection components extracted under these different optical conditions, and marking indicating information on the flaw on the surface of the metal strip. A marking device for marking a surface defect of a metal strip, comprising a marking means. 2. A method for extracting light reflected from a surface to be inspected of a metal strip under two or more different optical conditions, based on a combination of the reflection components extracted under the different optical conditions. A method for producing a metal strip with a mark, comprising determining presence or absence and marking the surface of the metal strip with information indicating the flaw. 3. A method of extracting reflected light from a surface to be inspected of a metal strip under two or more different optical conditions, and detecting surface flaws on the surface to be inspected based on a combination of the reflected components extracted under these different optical conditions. A step of determining the presence / absence, a step of marking the surface of the metal strip with information about the flaw, a step of winding the marked metal strip into a coil, and rewinding the coil to perform the marking. Having a step of detecting and specifying a predetermined range of the metal band based on the information indicated by the marking, and a step of performing predetermined processing on the remaining portion of the metal band that has avoided or removed the specified range. A method for processing a metal strip, comprising: 4. An abnormal part having a combination of reflection components from a surface separated under two or more different optical conditions different from a normal part is marked on the surface to indicate information on a flaw thereof. Metal band with marking. 5. A portion in which the amount of light of one or both of the specular reflection component from the surface and the specular diffuse reflection component due to a large number of minute specular reflection surfaces becomes abnormal.
A metal strip with a marking, characterized in that the surface is provided with a marking indicating information relating thereto. 6. A plurality of surface flaw inspection means including a surface flaw inspection means having a light receiving section and a signal processing section, and comprehensively determine the inspection results of the metal band surface, and provide marking information on the metal band surface. 2. The apparatus according to claim 1, further comprising marking information creating means for creating the marking information. 7. An inspection result by a plurality of surface flaw inspection methods including a surface flaw inspection method for inspecting a surface to be inspected based on a combination of reflection components extracted under two or more different optical conditions. 3. The method for producing a metal band with a metal band marking according to claim 2, wherein the determination is made and marking information on the surface of the metal band is created. 8. Regarding information on a metal band surface including an abnormal part in which a combination of reflection components from a surface separated under two or more different optical conditions is different from a normal part, information on the metal band surface is shown on the surface. 5. The metal strip with marking according to claim 4, wherein the metal strip is marked. 9. The information on the surface of a metal strip including a portion where the light amount of one or both of the specular reflection components from the surface and the specular diffuse reflection components by a plurality of minute specular reflection surfaces becomes abnormal is determined. 6. A metal strip with a marking according to claim 5, wherein a marking indicating information on the surface of the metal strip is provided on the metal strip.