JP2001330566A - Surface flaw inspection method by ccd camera - Google Patents
Surface flaw inspection method by ccd cameraInfo
- Publication number
- JP2001330566A JP2001330566A JP2000151099A JP2000151099A JP2001330566A JP 2001330566 A JP2001330566 A JP 2001330566A JP 2000151099 A JP2000151099 A JP 2000151099A JP 2000151099 A JP2000151099 A JP 2000151099A JP 2001330566 A JP2001330566 A JP 2001330566A
- Authority
- JP
- Japan
- Prior art keywords
- ccd camera
- electric signal
- thickness
- flaw inspection
- light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
- G01N21/8914—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles characterised by the material examined
- G01N2021/8918—Metal
Landscapes
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ＣＣＤカメラによ
る表面疵検査方法に係り、特に、鋼帯の表面疵を検出す
る際に用いるのに好適な、ＣＣＤカメラによる表面疵検
査方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a surface flaw using a CCD camera, and more particularly to a method for inspecting a surface flaw using a CCD camera, which is suitable for detecting a surface flaw of a steel strip.
【０００２】[0002]
【従来の技術】帯状材の表面に光を照射し、その反射光
をＣＣＤカメラで捕らえて、受光量を電気信号に変換
し、該電気信号の大きさと予め設定した閾値を比較し
て、疵を検出するＣＣＤカメラ方式の表面疵検査装置が
知られている（特開平１１−２４８６４１等）。2. Description of the Related Art Light is radiated on the surface of a band-shaped material, the reflected light is captured by a CCD camera, the amount of received light is converted into an electric signal, and the magnitude of the electric signal is compared with a preset threshold value. There is known a surface flaw inspection device of a CCD camera system for detecting a surface defect (Japanese Patent Application Laid-Open No. H11-248641, etc.).
【０００３】一般に鋼帯は、製品種類や表面性状（光
沢、粗度等）によって、ベースとなる受光量が異なり、
全て同じ条件で検査するために、電気信号の値が一定と
なるようにゲイン調整を行っている。一般的な方法は、
流れ方向の信号値の移動平均を演算し、その結果、一定
の信号レベルになるようにゲイン調整を行っている。[0003] Generally, a steel strip has a different amount of light received as a base depending on a product type and a surface property (gloss, roughness, etc.).
In order to perform inspection under the same conditions, the gain is adjusted so that the value of the electric signal becomes constant. The general method is
The moving average of the signal value in the flow direction is calculated, and as a result, the gain is adjusted so that the signal level becomes constant.
【０００４】このゲイン調整をしないと、信号値が全体
的に高く、又は低くなり過ぎた場合に、全部疵と検出し
てしまい、実際に疵が無いのに特大疵と判定する過検出
となったり、装置の演算部の処理負荷が増大して、疵の
判定処理が間に合わなくなったりする。[0004] If the gain value is not adjusted, if the signal value becomes too high or too low, all of the signals are detected as flaws, resulting in an overdetection of an oversized flaw even though there is no flaw actually. Also, the processing load on the calculation unit of the apparatus increases, and the process of determining the flaw cannot be performed in time.
【０００５】又、製品種類の異なる帯状材の接合部等で
表面性状が長手方向に急激に変化する段付点等の切替り
においては、移動平均を演算するための流れ方向の信号
値のデータが無いため、初期ゲイン値を設定している。
この初期ゲイン値が不適当な値であれば、適切なゲイン
に落ち着くまでに時間がかかり、板厚変化後の鋼帯先頭
部において、過検出や演算処理負荷増大といった問題が
発生する。これを防ぐため、一般的には、製品品種によ
り初期ゲイン値を決めるテーブルを持たせ、初期値は、
過去の該当製品の検査データを参考にしながらユーザが
決定している。[0005] In addition, in switching of stepped points or the like where the surface properties change abruptly in the longitudinal direction at joints of strips of different products, data of signal values in the flow direction for calculating a moving average is used. Because there is no, the initial gain value is set.
If the initial gain value is an inappropriate value, it takes time to settle to an appropriate gain, and problems such as excessive detection and an increase in calculation processing load occur at the leading end of the steel strip after the change in thickness. In order to prevent this, a table that determines the initial gain value according to the product type is generally provided.
The user decides while referring to the past inspection data of the corresponding product.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、同一品
種でも、板厚の違いで光の反射角度が変わり、ＣＣＤカ
メラの受光量に大きな差が生じることが分かった。従っ
て、同一製品であっても、ある板厚で初期ゲイン値が適
正で段付点直後から正常に検査できても、別の板厚で
は、初期ゲイン値が不適切で、段付点直後は過検出等を
起こすことがあった。However, it has been found that even in the same product type, the light reflection angle changes due to the difference in plate thickness, and a large difference occurs in the amount of light received by the CCD camera. Therefore, even with the same product, even if the initial gain value is appropriate at a certain plate thickness and the inspection can be performed normally immediately after the stepping point, the initial gain value is inappropriate at another plate thickness and immediately after the stepping point. In some cases, overdetection or the like may occur.
【０００７】本発明は、前記従来の問題点を解消するべ
くなされたもので、板厚の違いに拘らず、段付点等の板
厚切替直後から適正な検査が行えるようにすることを課
題とする。SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to make it possible to carry out an appropriate inspection immediately after a change of a plate thickness such as a stepped point, regardless of a difference in the plate thickness. And
【０００８】[0008]
【課題を解決するための手段】本発明は、裏面が支持さ
れた帯状材の表面に光を照射し、その反射光をＣＣＤカ
メラで捕らえて、受光量を電気信号に変換し、該電気信
号の大きさと予め設定した閾値を比較して、疵を検出す
るＣＣＤカメラによる表面疵検査方法において、前記閾
値を、帯状材の板厚に応じて補正するようにして、前記
課題を解決したものである。SUMMARY OF THE INVENTION The present invention illuminates the surface of a band-shaped material having a back surface supported, captures the reflected light with a CCD camera, converts the amount of received light into an electric signal, and In the surface flaw inspection method using a CCD camera that detects a flaw by comparing the size of the flaw with a preset threshold value, the threshold value is corrected according to the thickness of the band-shaped material, thereby solving the above problem. is there.
【０００９】又、前記閾値の補正を、製品種類や表面性
状の違いに拘らず、前記電気信号の値が一定となるよう
に行うゲイン調整のための初期ゲイン値を、帯状材の板
厚が変化する段付点で、板厚に応じて補正することによ
り行うようにしたものである。In addition, the threshold value is corrected so that the value of the electric signal is constant irrespective of the product type and the surface texture, and the initial gain value for gain adjustment is determined by the thickness of the band-shaped material. The correction is performed by changing the stepped point according to the thickness of the sheet.
【００１０】図２に示す如く、例えばゴム製の検査ロー
ル１０で裏面が支持された鋼帯１２の表面に投光器１４
により光を照射し、その正反射光を明視野カメラ（ＣＣ
Ｄカメラ）１６、乱反射光を暗視野カメラ（ＣＣＤカメ
ラ）１８で捕らえて、受光量を電気信号に変換し、該電
気信号の大きさと予め設定した閾値を比較して、疵を検
出する場合、通常、製品板厚範囲の中間ぐらいの基準板
厚（例えば４ｍｍ）でカメラ１６、１８の角度調整を行
う。鋼帯１２の表面からカメラ１６、１８までは、１．
５〜２ｍくらい距離があり、カメラの角度は、０．１°
単位の調整が必要である。As shown in FIG. 2, for example, a light projector 14 is provided on the surface of a steel strip 12 whose back surface is supported by an inspection roll 10 made of rubber.
And irradiate the light with the specular reflection light using a bright field camera (CC).
D camera) 16, the diffuse reflection light is captured by a dark field camera (CCD camera) 18, the amount of received light is converted into an electric signal, and the magnitude of the electric signal is compared with a preset threshold to detect a flaw. Normally, the angles of the cameras 16 and 18 are adjusted at a reference plate thickness (for example, 4 mm) about the middle of the product plate thickness range. From the surface of the steel strip 12 to the cameras 16, 18, 1.
There is a distance of about 5 to 2m, and the camera angle is 0.1 °
Unit adjustment is required.
【００１１】このような状態で、検査ロール１０に巻付
いている鋼帯１２の板厚が変わると、図３に示す如く、
反射角度が変化する。角度としては微妙であるが、カメ
ラまでの距離が遠いため、カメラの受光量は大きく変化
し、視野全体の明るさが、明るくなったり、暗くなった
りする。In this state, when the thickness of the steel strip 12 wound around the inspection roll 10 changes, as shown in FIG.
The reflection angle changes. Although the angle is delicate, since the distance to the camera is long, the amount of light received by the camera greatly changes, and the brightness of the entire visual field becomes brighter or darker.
【００１２】本来は、光軸に合わせてカメラを移動させ
るのが望ましいが、カメラ位置を変える必要があり、実
用的ではない。Originally, it is desirable to move the camera in accordance with the optical axis, but it is necessary to change the camera position, which is not practical.
【００１３】本発明は、図３に示したような板厚と反射
角度（受光量低下）の関係が、幾何学的に決まることに
着目してなされたもので、閾値を鋼帯（帯状材）の板厚
に応じて補正することで、適切な閾値を得るようにした
ものである。The present invention focuses on the fact that the relationship between the plate thickness and the reflection angle (decrease in the amount of received light) as shown in FIG. 3 is determined geometrically. ) Is corrected in accordance with the plate thickness to obtain an appropriate threshold.
【００１４】[0014]
【発明の実施の形態】以下図面を参照して、本発明の実
施形態を詳細に説明する。Embodiments of the present invention will be described below in detail with reference to the drawings.
【００１５】本実施形態は、図１に示す如く、裏面が検
査ロール１０で支持された鋼帯１２の表面に光を照射す
るための投光器１４と、鋼帯１２の表面による反射光を
捕らえて、受光量を電気信号に変換するＣＣＤカメラ
（例えば明視野カメラ又は暗視野カメラ）２０と、該Ｃ
ＣＤカメラ２０の出力が、製品種類や表面性状の違いに
拘らず、一定となるようにゲイン調整を行うためのゲイ
ン調整器２２と、該ゲイン調整器２２の初期ゲイン値
を、製品品種に応じて設定するための変換テーブル２４
と、該変換テーブル２４によって選択された初期ゲイン
値に対して、本発明により、例えば板厚に応じた折線関
数を用いて影響係数を設定する影響係数設定器２６と、
前記変換テーブル２４で選択された初期ゲイン値に前記
影響係数設定器２６で選定された影響係数を乗じて、前
記ゲイン調整部２２に入力するための乗算器２８と、前
記ゲイン調整器２２によってゲイン調整された電気信号
をデジタル信号に変換するアナログ／デジタル（Ａ／
Ｄ）変換器３０と、該Ａ／Ｄ変換器３０によりデジタル
信号化された電気信号に対して閾値処理を行う閾値処理
部３２と、該閾値処理部３２の出力により特徴量を採取
する特徴量採取部３４と、該特徴量採取部３４の出力に
基づいて疵の種類を判定する疵種判定部３６とを備えて
いる。In this embodiment, as shown in FIG. 1, a light projector 14 for irradiating light to the front surface of a steel strip 12 whose back surface is supported by an inspection roll 10 and capturing light reflected by the surface of the steel strip 12 A CCD camera (for example, a bright-field camera or a dark-field camera) 20 for converting the amount of received light into an electric signal;
The gain adjuster 22 for performing gain adjustment so that the output of the CD camera 20 is constant irrespective of the product type and the surface texture, and the initial gain value of the gain adjuster 22 according to the product type Conversion table 24 for setting
According to the present invention, for the initial gain value selected by the conversion table 24, an influence coefficient setter 26 for setting an influence coefficient by using, for example, a broken line function corresponding to the sheet thickness;
A multiplier 28 for multiplying the initial gain value selected in the conversion table 24 by the influence coefficient selected by the influence coefficient setting unit 26 and inputting the result to the gain adjustment unit 22; Analog / digital (A / A) that converts the adjusted electric signal into a digital signal
D) a converter 30, a threshold processing unit 32 that performs threshold processing on the electric signal digitized by the A / D converter 30, and a characteristic amount that obtains a characteristic amount based on an output of the threshold processing unit 32 A sampling unit 34 and a flaw type determination unit 36 that determines the type of flaw based on the output of the feature amount collection unit 34 are provided.
【００１６】このようにして、変換テーブル２４で選定
された初期ゲイン値に、影響係数設定器２６で設定され
た影響係数を乗じてゲイン調整器２２に入力することに
より、全ての板厚範囲に対して初期ゲイン値が適正とな
り、段付点等の板厚切替直後から適正な検査が可能とな
る。As described above, the initial gain value selected in the conversion table 24 is multiplied by the influence coefficient set by the influence coefficient setter 26 and input to the gain adjuster 22, whereby the entire thickness range is obtained. On the other hand, the initial gain value becomes appropriate, and an appropriate inspection can be performed immediately after the switching of the plate thickness such as a stepped point.
【００１７】本実施形態においては、影響係数を板厚か
らの折線関数で求めるようにしているので、板厚に応じ
た適切な影響係数を容易に求めることができる。なお、
板厚に応じた影響係数を求める方法はこれに限定され
ず、例えばテーブルで持つことも可能である。In the present embodiment, the influence coefficient is obtained by a broken line function from the sheet thickness, so that an appropriate influence coefficient according to the sheet thickness can be easily obtained. In addition,
The method of obtaining the influence coefficient according to the plate thickness is not limited to this, and for example, it is possible to use a table.
【００１８】又、前記実施形態においては、本発明が、
鋼帯の表面疵検査に適用されていたが、本発明の適用対
象はこれに限定されず、鋼帯以外の帯状材の表面疵検査
にも同様に適用できることは明らかである。Further, in the above embodiment, the present invention
Although the present invention has been applied to the inspection of the surface flaws of the steel strip, the application of the present invention is not limited to this, and it is apparent that the present invention can be similarly applied to the inspection of the surface flaws of strips other than the steel strip.
【００１９】[0019]
【実施例】酸洗ラインの熱延鋼板の表面疵検査に本発明
を適用したところ、鋼板先頭部の未検査による切捨量
が、従来は１０ｍ必要であったのが、本発明により１ｍ
に短縮することができた。EXAMPLE When the present invention was applied to the inspection of the surface flaws of a hot-rolled steel sheet in a pickling line, the amount of cut-off due to the uninspection of the head of the steel sheet was conventionally required to be 10 m.
Could be shortened.
【００２０】[0020]
【発明の効果】本発明によれば、ＣＣＤカメラを移動さ
せることなく、全ての板厚範囲に対して適正な閾値を得
ることができ、段付点等の板厚切替直後から、適正な表
面疵検査を行うことが可能となる。According to the present invention, an appropriate threshold value can be obtained for the entire thickness range without moving the CCD camera. A flaw inspection can be performed.
【図１】本発明に係る表面疵検査装置の実施形態の構成
を示すブロック線図FIG. 1 is a block diagram showing a configuration of an embodiment of a surface flaw inspection apparatus according to the present invention.
【図２】本発明の原理を説明するための、投光器とＣＣ
Ｄカメラの関係の例を示す線図FIG. 2 is a diagram showing a projector and a CC for explaining the principle of the present invention;
Diagram showing an example of the relationship between D cameras
【図３】同じく板厚が変化したときの反射方向の変化状
態の例を示す線図FIG. 3 is a diagram showing an example of a change state of a reflection direction when the plate thickness changes.
１０…検査ロール １２…鋼帯 １４…投光器 １６、１８、２０…ＣＣＤカメラ ２２…ゲイン調整器 ２４…変換テーブル ２６…影響係数設定器 ２８…乗算器 ３２…閾値処理部 ３４…特徴量採取部 ３６…疵種判定部 DESCRIPTION OF SYMBOLS 10 ... Inspection roll 12 ... Steel strip 14 ... Floodlight 16, 18, 20 ... CCD camera 22 ... Gain adjuster 24 ... Conversion table 26 ... Influence coefficient setter 28 ... Multiplier 32 ... Threshold processing part 34 ... Feature quantity sampling part 36 … Scratch type judgment unit
Claims (2)
し、その反射光をＣＣＤカメラで捕らえて、受光量を電
気信号に変換し、該電気信号の大きさと予め設定した閾
値を比較して、疵を検出するＣＣＤカメラによる表面疵
検査方法において、前記閾値を、帯状材の板厚に応じて
補正することを特徴とするＣＣＤカメラによる表面疵検
査方法。1. A light source irradiates a front surface of a band-shaped material having a back surface supported thereon, the reflected light is captured by a CCD camera, the amount of received light is converted into an electric signal, and the magnitude of the electric signal and a predetermined threshold value are determined. A surface flaw inspection method using a CCD camera for detecting flaws, wherein the threshold value is corrected according to the thickness of the strip.
違いに拘らず、前記電気信号の値が一定となるように行
うゲイン調整のための初期ゲイン値を、帯状材の板厚が
変化する段付点で、板厚に応じて補正することにより行
うことを特徴とする請求項１に記載のＣＣＤカメラによ
る表面疵検査方法。2. An initial gain value for gain adjustment for correcting the threshold value so that the value of the electric signal is constant irrespective of a product type or a surface property, and a sheet thickness of the strip material. 2. The surface flaw inspection method using a CCD camera according to claim 1, wherein the method is performed by correcting at a changing step point according to the thickness of the sheet.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000151099A JP2001330566A (en) | 2000-05-23 | 2000-05-23 | Surface flaw inspection method by ccd camera |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000151099A JP2001330566A (en) | 2000-05-23 | 2000-05-23 | Surface flaw inspection method by ccd camera |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2001330566A true JP2001330566A (en) | 2001-11-30 |
Family
ID=18656710
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006297457A (en) * | 2005-04-22 | 2006-11-02 | Jfe Steel Kk | Method for measuring outside diameter of seamless steel tube |
| JP2007057521A (en) * | 2005-07-29 | 2007-03-08 | Dainippon Screen Mfg Co Ltd | Unevenness inspecting apparatus and method therefor |
| JP2017090198A (en) * | 2015-11-09 | 2017-05-25 | 東芝三菱電機産業システム株式会社 | Device for photographing surface flaw on tabular body side face |
| CN108188337A (en) * | 2018-01-05 | 2018-06-22 | 沈成源 | Rivet automatic feed mechanism |
| JP2018149582A (en) * | 2017-03-14 | 2018-09-27 | Ｊｆｅスチール株式会社 | Edge detection method and edge detection apparatus of high strength cold-rolled steel plate |
| JP2019178924A (en) * | 2018-03-30 | 2019-10-17 | 日鉄日新製鋼株式会社 | Surface flaw inspection method and surface flaw inspection device for steel plate |
-
2000
- 2000-05-23 JP JP2000151099A patent/JP2001330566A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006297457A (en) * | 2005-04-22 | 2006-11-02 | Jfe Steel Kk | Method for measuring outside diameter of seamless steel tube |
| JP4725174B2 (en) * | 2005-04-22 | 2011-07-13 | Ｊｆｅスチール株式会社 | Method for measuring the outer diameter of seamless steel pipes |
| JP2007057521A (en) * | 2005-07-29 | 2007-03-08 | Dainippon Screen Mfg Co Ltd | Unevenness inspecting apparatus and method therefor |
| JP2017090198A (en) * | 2015-11-09 | 2017-05-25 | 東芝三菱電機産業システム株式会社 | Device for photographing surface flaw on tabular body side face |
| JP2018149582A (en) * | 2017-03-14 | 2018-09-27 | Ｊｆｅスチール株式会社 | Edge detection method and edge detection apparatus of high strength cold-rolled steel plate |
| CN108188337A (en) * | 2018-01-05 | 2018-06-22 | 沈成源 | Rivet automatic feed mechanism |
| CN108188337B (en) * | 2018-01-05 | 2024-05-24 | 沈成源 | Automatic feeding mechanism for rivet |
| JP2019178924A (en) * | 2018-03-30 | 2019-10-17 | 日鉄日新製鋼株式会社 | Surface flaw inspection method and surface flaw inspection device for steel plate |
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