JPS61147158A - Defect detecting device for strip - Google Patents

Abstract

PURPOSE:To detect a fine defect of a strip with high precision by detecting leak magnetic flux by a detection coil which faces a magnetizing device across the strip. CONSTITUTION:The magnetizing device 5 consists of a cavity roll 2 and a cylindrical iron core 3 wound a magnetizing coil 4. Many detection coils 6 are integrated and provided on the reverse surface of a floating mechanism 7 opposite the device 5 across the strip 1. The coil 6 is formed by winding an extremely thin conductor 10 around a small cavity core 11 which is sectioned rectangularly and subminiature, so the coil can be arranged nearby the strip 1. The conductor 10 iswound closely, so a sensing part is integrated without any gap to prevent irregularity in sensitivity due an irregular array. The coil 6 is arranged facing the device 5 almost in parallel to its center axis 12, so variation in leas magnetic flux due to fine inclusions of the strip 1 is detected securely and the detected leak magnetic flux is converted into a voltage signal, which is amplified by a voltage transformer and then processed, thereby deciding on a defect with high precision.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明はストリップの欠陥検出装置に係わシ、詳しくは
オンラインで、ストリップ例えば葡延鋼板１表面処理鋼
板９缶用鋼板等の内部欠陥とくζこ微小な介在物を漏洩
磁気探傷で検出する装置ｔこ関する。DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a strip defect detection device, and more specifically, it is an online method for detecting internal defects in strips, such as rolled steel sheets, 1 surface-treated steel sheet, 9 steel sheets for cans, etc. The present invention relates to a device for detecting minute inclusions using leakage magnetic flaw detection.

（従来の技術） 近年、炭酸飲料缶、ジュース缶、ビール缶などの飲料缶
の製造法において、胴部と底部を一体的に深絞り成形加
工する２ピ一ス缶の占める割合が急速に増加している。(Prior art) In recent years, in the manufacturing methods of beverage cans such as carbonated beverage cans, juice cans, and beer cans, the proportion of two-piece cans, in which the body and bottom are integrally deep-drawn, has rapidly increased. are doing.

この２ピ一ス缶用の鋼板ぽ、介在物がその加工性や、飲
料缶として内容物との反応性に悪い影響を及ぼすので、
該缶用鋼板の製造ラインなどで例えば０．０００５ｍ程
度の微小な介在物でも検出を行なう必要がある。This steel plate for two-piece cans has a negative impact on its processability and reactivity with the contents as a beverage can.
It is necessary to detect even minute inclusions, for example, on the order of 0.0005 m, on the manufacturing line for steel sheets for cans.

従来の鋼板の欠陥検出装置としては超音波探傷装置や磁
粉探傷装置がある。Conventional steel plate defect detection devices include ultrasonic flaw detection devices and magnetic particle flaw detection devices.

例えば、特開昭５ｓ−９ｓｓ６ｏ＋ト示されるような超
音波探傷装置は内部欠陥を検出することが出きるが、そ
の程度は比較的大きな欠陥の検出であって、検出精度の
向上を図るために例えば周波数を上げる等の改良をした
としても、逆Ｅこ超音波の減衰や林状エコーが増大し、
微小な介在物を効率よく検出することは困難である。又
、磁粉探傷装置は微小な介在物の検出に適したものであ
るが、磁粉を使用しなければならず、鋼板が汚れ、また
探傷ｔこ時間がかかるという問題がある。For example, an ultrasonic flaw detector such as that shown in Japanese Patent Application Laid-Open No. 5S-9SS6O+ can detect internal defects, but the degree of detection is relatively large, and in order to improve the detection accuracy, it is possible to detect internal defects. For example, even if improvements are made such as increasing the frequency, attenuation of inverse E ultrasound and forest echoes will increase.
It is difficult to efficiently detect minute inclusions. Further, although magnetic particle flaw detection equipment is suitable for detecting minute inclusions, it requires the use of magnetic particles, which results in the problem of staining the steel plate and the time required for flaw detection.

この他に、例えば特開昭５６−６１６４５に示されてい
るように、漏洩磁気探傷による検出装置がある。In addition to this, there is a detection device using leakage magnetic flaw detection, as shown in Japanese Patent Laid-Open No. 56-61645, for example.

これは励磁用電磁石と複数個の感磁性素子を有する検出
ヘッドを設けて、被検板を間欠的に定量移動させ、検出
ヘッドで漏洩磁束を検出して介在物などの欠陥全検出す
るものである。これは有力な装置であって、０．００１
ｍ″以上の介在物を検出できるとしている。しかしなが
ら、間欠的な探傷であるので、探傷作業が高速に行ない
難いことが懸念される。This is equipped with an excitation electromagnet and a detection head with multiple magnetically sensitive elements, and the test plate is moved intermittently by a fixed amount, and the detection head detects leakage magnetic flux to detect all defects such as inclusions. be. This is a powerful device, with 0.001
It is said that inclusions larger than m'' can be detected.However, since the flaw detection is intermittent, there is a concern that it may be difficult to perform the flaw detection work at high speed.

（発明が解決しようとする問題点〕 またこれまでの装置では現在要求されているような、例
えば０．０００５−程度の微小な介在物を検出すること
が難しかった。(Problems to be Solved by the Invention) Furthermore, with conventional devices, it has been difficult to detect inclusions as small as, for example, about 0.0005, which is currently required.

本発明はかかる実情に鑑みてなされたものであり、ス）
　ＩＪタッグ微小な欠陥を高い検出精度でかつオンライ
ンで検出する装置を目的とするものである。その技術的
骨子は、ストリップを全巾均−ｔこ磁化せしめる磁化装
置と、ストＩＪツブ全はさんで前記磁化装置に対向して
設けられる極細導線を非磁性絶縁物からなる小さい断面
形状とした空芯につめて巻回された検出コイルと、該検
出コイルから漏洩磁束を電圧信号して出力される信号を
昇圧せしめる電圧変成器とを設けたところにある。The present invention has been made in view of such circumstances, and
The purpose of the present invention is to provide a device that can detect small IJ tag defects with high detection accuracy and online. The technical gist is a magnetizing device that uniformly magnetizes the entire width of the strip, and an ultra-fine conducting wire that is provided across the strip IJ and facing the magnetizing device and has a small cross-sectional shape made of a non-magnetic insulator. It is provided with a detection coil wound tightly around an air core, and a voltage transformer that converts leakage magnetic flux from the detection coil into a voltage signal and boosts the output signal.

（問題点を解決するための手段〕 以下に本発明を一実施例に基づいて図面全参照して詳細
に述べる。(Means for Solving the Problems) The present invention will be described in detail below based on one embodiment with full reference to the drawings.

まず、本発明において検出対象とする欠陥例えば介在物
の大きさは、厚み１−２０μ、巾２０〜２００μ、長さ
５００〜１５００μと非常に小さなものを含んでいる。First, the sizes of defects, such as inclusions, to be detected in the present invention include very small ones with a thickness of 1 to 20 microns, a width of 20 to 200 microns, and a length of 500 to 1500 microns.

これらを漏洩磁気探傷で検出するには、ストリップの巾
方向に和尚する水平方向の磁界が均一で強い必要があシ
、さらに微小な欠陥よシの漏洩磁束はもれ出る範囲が小
さくかつ微弱であるが、これを垂直、水平両方向のバイ
アス磁界の影響を受けずに検出することが重要である。In order to detect these with leakage magnetic flaw detection, the horizontal magnetic field that extends across the width of the strip must be uniform and strong, and the leakage magnetic flux from minute defects must be small and weak. However, it is important to detect this without being influenced by bias magnetic fields in both vertical and horizontal directions.

ところで、図面において１は探傷されるストリップ、２
は非磁性材料例えばオーステナイト系ステンレスよフな
る空胴ａ−ル、３は前空胴ロール２の内に設けられた円
筒鉄芯であシ、そのまわシには磁化コイル４が巻回され
ている。この円筒鉄芯３の直径りと磁化コイル４を巻回
した長さＬの比を規定例えば０．２〜０．４とされ、水
平方向の磁界が均一で強いものが得られる。前記空胴ロ
ール２゜磁化コイル４が巻回された円筒鉄芯３によシ磁
化装置旦が構成される。By the way, in the drawing, 1 is the strip to be tested, 2 is
3 is a hollow core made of a non-magnetic material such as austenitic stainless steel, and 3 is a cylindrical iron core provided inside the front hollow roll 2, around which a magnetizing coil 4 is wound. There is. The ratio of the diameter of the cylindrical iron core 3 to the length L of the winding of the magnetizing coil 4 is defined, for example, from 0.2 to 0.4, so that a uniform and strong horizontal magnetic field can be obtained. A magnetizing device is constituted by the cylindrical iron core 3 around which the hollow roll 2° magnetizing coil 4 is wound.

旦は検出コイルであシ、漏洩磁束を検出しその変化よフ
欠陥を検出するものであって、その詳細は後記する。７
は前記検出コイル旦をストリップ１１こ微小間隔をおい
て倣わせるエア浮上機構であり、８は昇降装置である。First, a detection coil is used to detect leakage magnetic flux and detect any changes in the leakage magnetic flux, the details of which will be described later. 7
8 is an air floating mechanism that causes the detection coil to follow the strip 11 at minute intervals, and 8 is a lifting device.

９はストリップ１の押えロールである。9 is a presser roll for the strip 1.

検出コイル旦は微小な欠陥による漏洩磁°束の小さくて
微弱な変化を検出しなければならないので、次の条件金
偏える必要がある。Since the detection coil must detect small and weak changes in leakage magnetic flux due to minute defects, it is necessary to meet the following conditions.

（１）微小な欠陥のつくる磁界分布とはソ同程度の底面
形状をもつ超小型化で、感磁部がス）　ＩＪツブに近接
できること。(1) The magnetic field distribution created by minute defects is ultra-miniaturized with a bottom shape comparable to that of an IJ tube, and the magnetic sensing part can be placed close to the IJ knob.

（２）　　多数例えば数百側程度の集積化に適すること
。(2) Suitable for integration in large numbers, for example, on the order of several hundred.

［３）　　＃Ｉ磁界中で水平方向の諧弱か磁界変化を検
出できること。[3] Ability to detect horizontal gradients or magnetic field changes in #I magnetic field.

（４）ローノイズ特性を有すること。(4) Have low noise characteristics.

本発明者達はかかる条件を備えた検出コイルを開発すべ
く検討した。その結果、第２図に示すように極細導線１
０例えば１〜３０μφを、小さい断面形状とした非磁性
絶縁物からなる空芯１１（こつめて巻いて、微小な磁芯
のない検出コイル旦とし、該検出コイル旦の一辺をスト
リップに近接して、かつその中心軸１２がス）　Ｕツブ
と平行で磁化方向と一致するように配置せしめると、微
小な欠陥によフ発生する漏洩磁束の水平方向の変化が垂
直水平両方向のバイアス磁界に影響されず検出できるこ
とを見出した。The present inventors conducted studies to develop a detection coil that satisfies these conditions. As a result, as shown in FIG.
For example, an air core 11 made of a non-magnetic insulator with a small cross-sectional shape of 1 to 30 μΦ (wound tightly to form a detection coil without a minute magnetic core, and place one side of the detection coil close to the strip. If the center axis 12 is arranged so that it is parallel to the U-tube and coincides with the magnetization direction, horizontal changes in leakage magnetic flux caused by minute defects will affect the bias magnetic field in both the vertical and horizontal directions. We found that it was possible to detect the

そこで検出コイル旦は第２図（ｂ）　ｌこ示すようｌこ
多数個集積され、第１図に示すようにストリップ１を挾
んで磁化装置５に対向して前記浮上機構７の下面に設け
られる。該検出コイル旦は小さい断面形状の空芯１１に
極細導線１０ヲ巻回したもので超小型であるから、スト
リップ１ｆこ近接して配役できる。１だ極細導線１０は
つめて密に巻回されるので感磁部が隙間なく集積化され
、凹凸不整列による感度ムラも防止できる。Therefore, a large number of detection coils are integrated as shown in FIG. 2(b), and are installed on the lower surface of the floating mechanism 7, sandwiching the strip 1 and facing the magnetization device 5, as shown in FIG. . The detection coil 1 is made of an air core 11 having a small cross-sectional shape and wound with 10 ultrafine conductive wires, and is extremely small, so it can be arranged close to the strip 1f. Since the ultra-fine conductive wires 10 are tightly wound, the magnetically sensitive parts are integrated without any gaps, and unevenness in sensitivity due to uneven alignment can be prevented.

該検出コイル旦の断面形状は長方形が好ましく、その大
きさは横０．３〜２ｍ、縦０．１〜１鵡程度である。ま
たその巾は０．１〜１＋ａ＋程度が好ましい。The cross-sectional shape of the detection coil is preferably rectangular, and its size is approximately 0.3 to 2 m in width and 0.1 to 1 m in length. Moreover, the width is preferably about 0.1 to 1+a+.

ところで、検出コイル旦は本質的に漏洩磁束の変化を検
出し、バイアス磁界の影響を受けないということと、ａ
−ノイズである特長をもっている。By the way, the detection coil essentially detects changes in leakage magnetic flux and is not affected by the bias magnetic field.
-It has the characteristic of being a noise.

しかしながら検出コイル旦で検出される微小な欠陥ｔこ
よる漏洩磁束の変化は微弱であシ、これ全欠陥として判
別するには増巾しなければならない。However, the change in leakage magnetic flux caused by a minute defect detected by the detection coil is very weak, and must be increased in order to distinguish it as a total defect.

該検出コイル旦から漏洩磁束が電圧信号として出力され
る信号は非常に微弱であシ、これを直ちに従来の電子式
増巾器で欠陥の判別に必要な倍率例えば１０〜１００万
倍シこ増巾すると、該増巾器自身の電子ノイズのためｆ
こ、Ｓ／Ｎ比が確保できず・欠陥の判別が困難となる。The leakage magnetic flux is output as a voltage signal from the detection coil, which is very weak, and is immediately increased to a magnification of 10 to 1,000,000 times, which is necessary for determining defects, using a conventional electronic amplifier. When the width is increased, f due to the electronic noise of the amplifier itself
In this case, the S/N ratio cannot be secured and it becomes difficult to identify defects.

従って本発明では前記横部 出コイル旦のローインピーダイン特性を利用すべく、第
４図に示すように電圧変成器１３ヲ設けて増巾例えば１
０〜１０００倍に前記検出コイル旦からの電圧信号全増
巾する。これによりローノイズで高倍率の増巾ができ、
装置的ｌこも安価となる。次いで通常の電子式増巾器１
４で増巾し、帯域フィルター１５、波高判別器１６に順
次入力されて欠陥が判別される。Therefore, in the present invention, in order to take advantage of the low impedance characteristics of the lateral output coil, a voltage transformer 13 is provided as shown in FIG.
The voltage signal from the detection coil is fully amplified by 0 to 1000 times. This allows for high magnification with low noise.
The equipment is also inexpensive. Next, a normal electronic amplifier 1
The signal is amplified in step 4, and is sequentially input to a bandpass filter 15 and a pulse height discriminator 16 to determine defects.

次に検出方法について述べる。Next, the detection method will be described.

磁化装置互にて磁化すると、該磁化装置旦によフ磁界が
生じる。その磁界分布を第５図に示すが、磁化装置旦の
中心軸に平行な水平磁界１７と、垂直磁界１８が生じる
。When the magnetizers magnetize each other, a magnetic field is generated between the magnetizers. The magnetic field distribution is shown in FIG. 5, where a horizontal magnetic field 17 parallel to the central axis of the magnetizer and a vertical magnetic field 18 are generated.

ストリップ１のような薄物においては、垂直方向の磁界
強度は反磁界効果ζこよって打消され、水平方向の磁界
のみがストリップ１の磁化に有効１こ作用する。従って
一本の磁化装置旦によって均一な磁化が達成できるので
ある。In a thin object such as the strip 1, the vertical magnetic field strength is canceled by the demagnetizing field effect ζ, and only the horizontal magnetic field has an effective effect on the magnetization of the strip 1. Therefore, uniform magnetization can be achieved with a single magnetizing device.

第６図に示す如く、ストリップ１に微小な欠陥例えば介
在物１９が存在すると、該介在物１９によ磁化じる漏洩
磁束の変化を、検出コイル且は検出する。この検出コイ
ル且は前述の如く極細導線１０が小さい断面形状の非磁
性絶縁物の空芯１１につめて巻かれたものであり、磁化
装置旦ζこ対向してその中心軸とはｙ平行にかつ対向し
て配設されているので、微小な介在物１９によ磁化じる
漏洩磁束の変化を確実に検出できる。該検出された漏洩
磁束は電圧信号に変換され、電圧変成器１３で増巾され
た後に通常の増巾器１４、帯域フィルター１５、波高判
別器１６により信号処理され、欠陥が判別される。As shown in FIG. 6, when a minute defect such as an inclusion 19 exists in the strip 1, the detection coil detects a change in leakage magnetic flux magnetized by the inclusion 19. As mentioned above, this detection coil consists of an ultra-fine conducting wire 10 wrapped around an air core 11 made of non-magnetic insulator with a small cross-section, and facing the magnetizing device ζ, with its central axis parallel to y. In addition, since they are disposed facing each other, changes in leakage magnetic flux caused by magnetization due to minute inclusions 19 can be reliably detected. The detected leakage magnetic flux is converted into a voltage signal, amplified by a voltage transformer 13, and then subjected to signal processing by an ordinary amplifier 14, a bandpass filter 15, and a pulse height discriminator 16 to determine a defect.

（発明の効果〕 本発明は以上詳述したように、ストリップの微小な欠陥
をオンラインで高い検出精度にて検出することができる
。(Effects of the Invention) As described in detail above, the present invention can detect minute defects in a strip online with high detection accuracy.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の一実施例を示す図。第２図は本発明の
一実施例における検出コイルを示す図で、（ａ）はその
１個を示し、（ｂ〕は多数個配設した図である。第３図
は本発明の一実施例における磁化装置を示す図。第４図
は本発明の一実施例シこおける信号処理装置を示す図。 第５図は本発明の詳細な説明するための磁界分布を示す
図。第６図は本発明の詳細な説明するための微小な欠陥
の検出を示す図。 １・・・ストリップ、２−空胴ａ−ル、３・・・円筒鉄
芯、４・・・磁化コイル、二・・・磁化装置、旦・・・
検出コイル、７・・・エア浮上機構、８・・・昇降装置
、９・・・グえロール、１０・・・極細導線、１１・・
・空芯、１２・・・中心軸、１３−・・電圧変成器、１
４・・・増巾器、１５・・・帯域フィルター、１６・・
・波高判別器、１９・・・介在物。FIG. 1 is a diagram showing an embodiment of the present invention. Fig. 2 is a diagram showing a detection coil in an embodiment of the present invention, (a) shows one, and (b) shows a large number of detection coils arranged. Fig. 3 is a diagram showing one embodiment of the present invention. A diagram showing a magnetization device in an example. FIG. 4 is a diagram showing a signal processing device in an embodiment of the present invention. FIG. 5 is a diagram showing a magnetic field distribution for explaining the present invention in detail. FIG. 1 is a diagram showing the detection of minute defects for detailed explanation of the present invention. 1...Strip, 2-Cavity a-ru, 3... Cylindrical iron core, 4... Magnetizing coil, 2- ...Magnetizing device, Dan...
Detection coil, 7... Air floating mechanism, 8... Elevating device, 9... Gouge roll, 10... Ultra-thin conductor wire, 11...
・Air core, 12... Central shaft, 13-... Voltage transformer, 1
4...Amplifier, 15...Band filter, 16...
・Wave height discriminator, 19...Inclusion.

Claims (1)

【特許請求の範囲】[Claims] 円筒鉄芯に磁化コイルを巻回して形成された磁化装置と
、該磁化装置に対向してストリップをはさんで配設され
極細導線を小断面形状の非磁性絶縁物からなる空芯につ
めて巻かれてなる漏洩磁束を検出する検出コイルと、該
検出コイルから漏洩磁束を電圧信号として出力された信
号を増巾する電圧変成器とを設けたことを特徴とするス
トリップの欠陥検出装置。A magnetizing device is formed by winding a magnetizing coil around a cylindrical iron core, and an ultra-fine conductive wire placed across a strip opposite the magnetizing device is packed into an air core made of a non-magnetic insulator with a small cross-section. What is claimed is: 1. A defect detection device for a strip, comprising: a detection coil that detects leakage magnetic flux formed by winding the strip; and a voltage transformer that amplifies a signal outputted from the detection coil by converting the leakage magnetic flux into a voltage signal.