JP2959395B2 - Metal residue detection method in metal tube - Google Patents
Metal residue detection method in metal tubeInfo
- Publication number
- JP2959395B2 JP2959395B2 JP10822194A JP10822194A JP2959395B2 JP 2959395 B2 JP2959395 B2 JP 2959395B2 JP 10822194 A JP10822194 A JP 10822194A JP 10822194 A JP10822194 A JP 10822194A JP 2959395 B2 JP2959395 B2 JP 2959395B2
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- Japan
- Prior art keywords
- steel pipe
- coil
- metal
- detection coil
- magnetic
- 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.)
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- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
- Geophysics And Detection Of Objects (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、例えば鋼管内の金属残
留物検出方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a metal residue in a steel pipe, for example.
【０００２】[0002]
【従来の技術】従来、鋼管内の金属残留物、例えば電縫
管の内面ビード屑は自動除去装置によって除去した後、
管端に蛍光灯群を配置し、もう一方の管端から管内部を
のぞいて目視検査するのが一般的である。2. Description of the Related Art Conventionally, metal residues in a steel pipe, for example, internal bead chips of an electric resistance welded pipe are removed by an automatic removing device.
It is common to arrange a group of fluorescent lamps at the end of the tube and visually inspect the inside of the tube from the other end.
【０００３】しかし、例えば長尺鋼管内の金属残留物の
検査を目視で行う場合、長尺鋼管が自重により撓んで検
査し難く、検出モレの可能性を有する。また、金属残留
物の自動除去装置の不具合により、多量の除去残りを発
生させる可能性を有しているので、その場合には速やか
に不具合を検知する必要がある。However, when a metal residue in a long steel pipe is inspected visually, for example, the long steel pipe bends due to its own weight, making it difficult to perform inspection. In addition, since there is a possibility that a large amount of unremoved residue is generated due to a failure of the automatic metal residue removing device, it is necessary to detect the failure promptly in such a case.
【０００４】上記の問題点を解決する方法として、特開
平４−２１５０４６号公報にて、鋼管の管端から電磁波
を輻射し、鋼管を円形導波管として電磁波を伝播させて
伝播した電磁波をもう一方の管端で受信し、その電磁波
の周波数変調および／または電力減衰を計測して内部残
留物を検出する方法が提案されている。As a method for solving the above problem, Japanese Patent Application Laid-Open No. H4-215046 discloses that an electromagnetic wave is radiated from the end of a steel pipe, and the electromagnetic wave is propagated by using the steel pipe as a circular waveguide to propagate the electromagnetic wave. There has been proposed a method of detecting the internal residue by receiving the signal at one end of the tube and measuring the frequency modulation and / or power attenuation of the electromagnetic wave.
【０００５】[0005]
【発明が解決しようとする課題】ところが、この特開平
４−２１５０４６号公報にて提案されている方法は以下
の問題点を有する。 設備が大きいので、大きな設置スペースが必要とな
り、設置場所が限定される。また、設備費が高価にな
る。 鋼管の両端で電磁波を発信および受信しているので、
鋼管の長さにバラツキがあると検出精度が変動する。従
って、長さにバラツキのある鋼管には使用し難い。 発信器および受信器に付随する装置を鋼管の両端に近
接させる必要があるので、高速で処理できない。However, the method proposed in Japanese Patent Application Laid-Open No. H4-215046 has the following problems. Since the equipment is large, a large installation space is required, and the installation place is limited. In addition, the equipment cost becomes high. Since electromagnetic waves are transmitted and received at both ends of the steel pipe,
If the length of the steel pipe varies, the detection accuracy fluctuates. Therefore, it is difficult to use a steel pipe having a variation in length. Since the devices associated with the transmitter and the receiver need to be close to both ends of the steel pipe, they cannot be processed at high speed.
【０００６】本発明の目的は、上記した問題点を解決
し、コンパクトな装置により金属残留物を高精度にかつ
短時間で検出できる金属管内の金属残留物検出方法を提
供することである。An object of the present invention is to solve the above-mentioned problems and to provide a method for detecting a metal residue in a metal tube which can detect a metal residue with high accuracy and in a short time by a compact device.
【０００７】[0007]
【課題を解決するための手段】上記した目的を達成する
ために、第１の本発明の方法は、金属管の外周に渦電流
検出コイルと、この渦電流検出コイル周辺に磁界を付与
する磁気コイルを臨ませ、金属管は磁気飽和し該金属管
内に存する金属残留物は磁気飽和しない程度に磁化した
状態と成るように前記磁気コイルに予め金属管毎に求め
てある電流を供給し、前記渦電流検出コイルに供給する
電圧の電圧変化を測定して前記金属管内に存する金属残
留物を検出するのである。In order to achieve the above-mentioned object, a first method of the present invention is to provide an eddy current detecting coil on the outer periphery of a metal tube and a magnetic field for applying a magnetic field around the eddy current detecting coil. With the coil facing, the metal tube is magnetically saturated, and a metal residue present in the metal tube is supplied with a current previously determined for each metal tube to the magnetic coil so that the metal residue is magnetized to a degree that does not cause magnetic saturation. A change in the voltage supplied to the eddy current detection coil is measured to detect a metal residue present in the metal tube.
【０００８】第２の本発明の方法は、金属管の外周に渦
電流検出コイルと、この渦電流検出コイル周辺に磁界を
付与する磁気コイルを臨ませ、前記渦電流検出コイル周
辺の金属管は磁気飽和し該金属管内に存する金属残留物
は磁気飽和しない程度に磁化した状態と成るように予め
金属管毎に求めてある所定の間隔を存して前記磁気コイ
ルと前記渦電流検出コイルを設置し、前記渦電流検出コ
イルに供給する電圧の電圧変化を測定して前記金属管内
に存する金属残留物を検出するのである。According to a second method of the present invention, an eddy current detecting coil and a magnetic coil for applying a magnetic field around the eddy current detecting coil face the outer periphery of the metal tube. The magnetic coil and the eddy current detection coil are installed at predetermined intervals previously determined for each metal tube so that the metal residue that is magnetically saturated and remains in the metal tube is magnetized to a degree that does not cause magnetic saturation. Then, a voltage change of a voltage supplied to the eddy current detection coil is measured to detect a metal residue existing in the metal tube.
【０００９】[0009]
【作用】本発明者等は鋭意実験研究を重ねた結果、鋼管
表面の欠陥検出方法として用いられている渦流法が鋼管
内部の金属残留物を検査するのに有効であることを知見
した。渦流法は、磁気飽和装置を用いて鋼管を充分に磁
化した後に、検出コイルに高周波数の交流電圧を供給し
て磁束を発生させ、渦電流を誘起し、この渦電流の反作
用を検出コイルのインピーダンス変化による電圧変化と
して検出する方法である。The present inventors have conducted intensive experimental studies and found that the eddy current method, which is used as a method for detecting defects on the surface of a steel pipe, is effective for inspecting metal residues inside the steel pipe. In the eddy current method, after sufficiently magnetizing a steel pipe using a magnetic saturation device, a high-frequency AC voltage is supplied to the detection coil to generate a magnetic flux, to induce an eddy current, and the reaction of the eddy current to the detection coil. This is a method of detecting as a voltage change due to an impedance change.
【００１０】鋼管等の強磁性体は外部の磁界の強さに比
例して磁化されないで、その材質により独特の磁気特性
を示すのは周知である。そして、磁気飽和コイルに電流
を供給すると、供給された電流値とコイルの巻数によ
り、これらによって決定されるある強さの磁界が鋼管に
発生する。磁化されていない鋼管に対して徐々に磁界を
加えると、初期において鋼管は急激に磁化され、その後
は磁界の強度と共に磁化の勢いは減衰して磁気飽和状態
に達する。ちなみに、磁化してない状態の標準的な低炭
素鋼管の比透磁率μは１０００程度である。図２に鋼管
内に金属残留物が存在しない状態を示し、図３に鋼管内
に金属残留物が存在する状態を示す。It is well known that a ferromagnetic material such as a steel pipe is not magnetized in proportion to the strength of an external magnetic field, but exhibits unique magnetic characteristics depending on its material. When a current is supplied to the magnetic saturation coil, a magnetic field having a certain strength determined by the supplied current value and the number of turns of the coil is generated in the steel pipe. When a magnetic field is gradually applied to a non-magnetized steel pipe, the steel pipe is rapidly magnetized in the initial stage, and thereafter, the momentum of the magnetization is attenuated with the strength of the magnetic field to reach a magnetic saturation state. Incidentally, the relative permeability μ of a standard non-carbon steel pipe in a non-magnetized state is about 1,000. FIG. 2 shows a state where no metal residue is present in the steel pipe, and FIG. 3 shows a state where metal residue is present in the steel pipe.
【００１１】金属残留物を存する鋼管に磁界を加えた場
合においても、鋼管および金属残留物は磁化される。と
ころが、鋼管がある程度磁化された後に鋼管内部に存す
る金属残留物が磁化されるので、鋼管を磁気飽和させる
磁界の強さと金属残留物を磁気飽和させる磁界の強さは
異なる。図４に標準的な低炭素鋼管に加えた磁界の強さ
（鋼管の中心部に発生する磁界の磁束密度で代用）と鋼
管および金属残留物の比透磁率との関係を示す。[0011] Even when a magnetic field is applied to the steel pipe containing the metal residue, the steel pipe and the metal residue are magnetized. However, after the steel pipe is magnetized to some extent, the metal residue existing inside the steel pipe is magnetized, so that the strength of the magnetic field for magnetically saturating the steel pipe and the strength of the magnetic field for magnetically saturating the metal residue are different. FIG. 4 shows the relationship between the strength of the magnetic field (substituted by the magnetic flux density of the magnetic field generated at the center of the steel pipe) applied to the standard low carbon steel pipe and the relative permeability of the steel pipe and metal residues.
【００１２】鋼管が磁気飽和し、金属残留物が磁気飽和
しない程度に磁化された状態では、鋼管および空間の比
透磁率は１であり、金属残留物の比透磁率は１０００か
ら変化して、例えば１００程度になる。従って、鋼管の
みが磁気飽和した状態および鋼管が磁気飽和し、金属残
留物が磁気飽和しない程度に磁化されている状態では、
金属残留物の比透磁率に影響されて検出コイルのインピ
ーダンスが大きく変化し、検出コイルに電圧変化が生じ
る。In a state in which the steel pipe is magnetically saturated and the metal residue is magnetized to such an extent that the metal residue is not magnetically saturated, the relative permeability of the steel pipe and the space is 1, and the relative permeability of the metal residue changes from 1000, For example, it is about 100. Therefore, in a state where only the steel pipe is magnetically saturated and in a state where the steel pipe is magnetically saturated and the metal residue is magnetized to such an extent that the metal residue is not magnetically saturated,
The impedance of the detection coil greatly changes due to the relative magnetic permeability of the metal residue, and a voltage change occurs in the detection coil.
【００１３】ところが、鋼管および金属残留物が共に磁
気飽和した状態では、鋼管および金属残留物の比透磁率
は１に近づき、鋼管内に金属残留物が存在しない状態に
等しくなり、検出コイルのインピーダンスは変化しない
ので、検出コイルに電圧変化が生じない。さらに、鋼管
が磁気飽和していない状態では、鋼管に発生する磁気は
金属残留物まで達しない。この場合、鋼管および金属残
留物の比透磁率は共に、空間の比透磁率と比べて大きな
値であるので、鋼管内に金属残留物が存在していても、
検出コイルのインピーダンスは変化せず、検出コイルに
電圧変化が生じない。However, when both the steel pipe and the metal residue are magnetically saturated, the relative permeability of the steel pipe and the metal residue approaches 1, which is equal to a state where no metal residue exists in the steel pipe, and the impedance of the detection coil is increased. Does not change, no voltage change occurs in the detection coil. Further, when the steel pipe is not magnetically saturated, the magnetism generated in the steel pipe does not reach the metal residue. In this case, since the relative permeability of the steel pipe and the metal residue are both larger values than the relative permeability of the space, even if the metal residue is present in the steel pipe,
The impedance of the detection coil does not change, and no voltage change occurs in the detection coil.
【００１４】以上のことより、鋼管のみを磁気飽和させ
て金属残留物を磁気飽和させない程度の比較的弱い磁界
を発生させた状態であれば、検出コイルのインピーダン
スが大きく変化するので、検出コイルの電圧変化を測定
すると、金属残留物を検出できる。As described above, in a state where a relatively weak magnetic field that does not magnetically saturate only the steel pipe and does not magnetically saturate the metal residue is generated, the impedance of the detection coil greatly changes. By measuring the voltage change, metal residues can be detected.
【００１５】また、鋼管に発生する磁界が弱いと、鋼管
表面に発生した表面疵は検出し難いということは知られ
ている。従って、金属残留物が検出し易く、表面疵は検
出し難い程度に鋼管に発生する磁界の磁束密度を調整す
ることで、表面疵に影響されずに金属残留物のみを検出
できる。It is known that if the magnetic field generated on the steel pipe is weak, it is difficult to detect surface flaws generated on the surface of the steel pipe. Therefore, by adjusting the magnetic flux density of the magnetic field generated in the steel pipe to such an extent that the metal residue is easily detected and the surface flaw is hard to detect, only the metal residue can be detected without being affected by the surface flaw.
【００１６】ところで、鋼管のみを磁気飽和させて金属
残留物を磁気飽和させない程度の比較的弱い磁界の強さ
は被検材の材質、寸法によって異なるので、予め鋼管毎
に最適な磁界の強さを求めておく必要がある。また、磁
気飽和コイルに電流を供給して鋼管に加える磁界は、磁
気飽和コイルの中央部で磁束密度が高く、磁気飽和コイ
ルから離れるのにしたがって磁束密度が低くなる。な
お、この磁束密度の変化は磁気飽和コイルの形状、鋼管
の形状、材質等により異なる。The strength of a relatively weak magnetic field that magnetically saturates only the steel pipe and does not magnetically saturate the metal residue differs depending on the material and dimensions of the test material. Need to be sought. The magnetic field applied to the steel pipe by supplying a current to the magnetic saturation coil has a high magnetic flux density at the center of the magnetic saturation coil, and the magnetic flux density decreases as the distance from the magnetic saturation coil increases. The change in the magnetic flux density differs depending on the shape of the magnetic saturation coil, the shape and the material of the steel pipe, and the like.
【００１７】従って、表面疵検出用として磁気飽和コイ
ルに比較的強い磁界を加えた場合であっても、検出コイ
ル周辺においては鋼管のみを磁気飽和させて金属残留物
を磁気飽和させない程度の比較的弱い磁界を発生した状
態となるように磁気飽和コイルと検出コイルを間隔を存
して設置すれば、金属残留物を検出できる。Therefore, even when a relatively strong magnetic field is applied to the magnetic saturation coil for detecting surface flaws, a relatively small amount of magnetic saturation of only the steel pipe around the detection coil and no magnetic saturation of metal residues is detected around the detection coil. If the magnetic saturation coil and the detection coil are arranged at intervals so as to generate a weak magnetic field, metal residues can be detected.
【００１８】さらに、金属残留物は鋼管の内部にあるの
で、鋼管に充分な磁気を浸透させる必要がある。検出コ
イルに供給する交流電圧の周波数が低い程、検出コイル
の磁気を鋼管に深く浸透させることができるので、比較
的に低い周波数の交流電圧を検出コイルに供給すると、
より有効に金属残留物を検出できる。Furthermore, since the metal residue is inside the steel pipe, it is necessary to allow sufficient magnetism to penetrate the steel pipe. The lower the frequency of the AC voltage supplied to the detection coil, the more deeply the magnetism of the detection coil can penetrate the steel pipe, so if a relatively low frequency AC voltage is supplied to the detection coil,
Metal residues can be detected more effectively.
【００１９】[0019]
【実施例】以下、本発明の一実施例を添付した図面に基
づいて説明する。図１は請求項１に対応する本発明方法
を実施する設備の概要を示す図、図７は請求項２に対応
する本発明方法を実施する設備の概要を示す図である。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing an outline of a facility for implementing the method of the present invention corresponding to claim 1, and FIG. 7 is a diagram showing an outline of a facility for implementing the method of the present invention corresponding to claim 2.
【００２０】〔請求項１に対応する実施例〕１は鋼管４
内に存する金属残留物５を検出する検出部で、鋼管４が
検出部１を通過する際に、金属残留物５を検出する。こ
の検出部１内には磁気飽和コイル２と、通過する鋼管４
と磁気飽和コイル２の間に検出コイル３が配設されてい
る。[Embodiment corresponding to claim 1] 1 is a steel pipe 4
The detection unit detects the metal residue 5 existing in the inside, and detects the metal residue 5 when the steel pipe 4 passes through the detection unit 1. A magnetic saturation coil 2 and a steel pipe 4
The detection coil 3 is provided between the magnetic coil 2 and the magnetic saturation coil 2.
【００２１】磁気飽和コイル２は、直流電源装置６から
電流を供給されて、鋼管４を磁気飽和させ、金属残留物
５を磁気飽和しない程度に磁化する。また、検出コイル
３には交流電圧を供給し、検出器７で電圧変化を検出し
て、金属残留物５の存在を検出する。The magnetic saturation coil 2 is supplied with a current from the DC power supply 6 to magnetically saturate the steel pipe 4 and magnetize the metal residue 5 to such an extent that the metal residue 5 is not magnetically saturated. Further, an AC voltage is supplied to the detection coil 3, and a voltage change is detected by the detector 7 to detect the presence of the metal residue 5.
【００２２】請求項１に対応する本発明は、以上説明し
たような構成をした装置を用いて実施するものであり、
外径３８．１ｍｍ、肉厚４ｍｍの電縫管内に、幅６ｍ
ｍ、長さ５０ｍｍのビード屑、幅３ｍｍ、長さ５０ｍｍ
のビード屑および深さ０．５ｍｍ、長さ２０ｍｍの軸方
向ノッチ疵が存する状態を、巻数７０００巻の磁気飽和
コイルと、内径４３ｍｍ、幅７−２−７ｍｍの自己誘導
自己比較式の検出コイルを有する装置にてビード屑の検
出実験を行い、図５・６に示す結果を得た。The present invention corresponding to claim 1 is embodied using an apparatus having the above-described configuration.
6m width in an electric resistance welded tube of 38.1mm outside diameter and 4mm thickness
m, bead shavings of length 50mm, width 3mm, length 50mm
A bead dust and a 0.5 mm deep, 20 mm long axial notch flaw are detected by a magnetically saturated coil having 7000 turns and a self-induction self-comparison type detection coil having an inner diameter of 43 mm and a width of 7-2-7 mm. An experiment for detecting bead debris was performed by using an apparatus having the above, and the results shown in FIGS. 5 and 6 were obtained.
【００２３】図５は鋼管の中心部に発生する磁界の磁束
密度を変化させた場合において検出コイルへ周波数４ｋ
Ｈｚの電圧を供給して検出したビード屑および軸方向ノ
ッチ疵の検出信号の高さを示し、図６は検出コイルに供
給する交流電圧の周波数を変化させた場合において磁気
飽和コイルに５Ａの電流を供給して検出したビード屑お
よび軸方向ノッチ疵の検出信号の高さを示す。FIG. 5 shows a case where the magnetic flux density of the magnetic field generated at the center of the steel pipe is changed and the frequency of 4 k is applied to the detection coil.
6 shows the height of the detection signal of the bead dust and the axial notch flaw detected by supplying a voltage of 5 Hz. FIG. 6 shows the current of 5 A flowing through the magnetic saturation coil when the frequency of the AC voltage supplied to the detection coil is changed. Shows the height of the detection signal of the bead dust and the axial notch flaw detected by supplying the above.
【００２４】図５より、鋼管の中心部に発生する磁界の
磁束密度が０．３〜０．９Ｔであると、外面疵に影響さ
れずにビード屑を検出できることは明らかである。図６
より、２〜８ｋＨｚの交流電圧を検出コイルに供給する
と、ビード屑を検出し易いことは明らかである。ちなみ
に、磁気飽和コイルに５Ａの電流を供給した時に発生す
る磁界の磁束密度は約１．５Ｔである。It is apparent from FIG. 5 that if the magnetic flux density of the magnetic field generated at the center of the steel pipe is 0.3 to 0.9 T, the bead chips can be detected without being affected by the outer surface flaw. FIG.
It is clear from the above that supplying an AC voltage of 2 to 8 kHz to the detection coil makes it easier to detect bead dust. Incidentally, the magnetic flux density of the magnetic field generated when a current of 5 A is supplied to the magnetic saturation coil is about 1.5T.
【００２５】鋼管毎に、磁気飽和コイルによって鋼管に
発生させる磁界の磁束密度および検出コイルに流す交流
電圧の周波数を実験で求め、予め磁気飽和コイルに供給
する電流および検出コイルに供給する電圧の諸条件を設
定して金属残留物の検出を行えばよい。For each steel pipe, the magnetic flux density of the magnetic field generated in the steel pipe by the magnetic saturation coil and the frequency of the AC voltage applied to the detection coil are determined by experiments, and the current supplied to the magnetic saturation coil and the voltage supplied to the detection coil are determined in advance. Conditions may be set to detect metal residues.
【００２６】〔請求項２に対応する実施例〕図７におい
て、２は鋼管４及び金属残留物５を磁化する磁気飽和コ
イルで、この磁気飽和コイル２と予め設定してある所定
の間隔を存して検出コイル３が配設されている。磁気飽
和コイル２は、直流電源装置６から電流を供給されて、
検出コイル３周辺において鋼管４を磁気飽和させ、金属
残留物５を磁気飽和しない程度に磁化する。そして、検
出コイル３には交流電圧を供給し、検出器７で電圧変化
を検出して、通過する鋼管４内の金属残留物５の存在を
検出する。In FIG. 7, reference numeral 2 denotes a magnetic saturation coil for magnetizing the steel pipe 4 and the metal residue 5, and has a predetermined distance from the magnetic saturation coil 2. In addition, a detection coil 3 is provided. The magnetic saturation coil 2 is supplied with current from the DC power supply 6,
The steel tube 4 is magnetically saturated around the detection coil 3, and the metal residue 5 is magnetized so as not to be magnetically saturated. Then, an AC voltage is supplied to the detection coil 3, a voltage change is detected by the detector 7, and the presence of the metal residue 5 in the passing steel pipe 4 is detected.
【００２７】請求項２に対応する本発明は、以上説明し
たような構成をした装置を用いて実施するものであり、
図８に示すように、上記した装置の磁気飽和コイル２と
通過する鋼管４との間に表面疵検出用検出コイル８を配
設し、検出器９で表面疵検出用検出コイル８の電圧変化
を検出して、表面疵を検出するように構成した装置を用
いて、ビード屑および表面疵の検出実験を行う。なお、
１０は表面疵と金属残留物を弁別する演算器、１１は磁
気飽和コイル１を支持するスリーブである。The present invention corresponding to claim 2 is embodied using an apparatus having the above-described configuration.
As shown in FIG. 8, a surface flaw detection coil 8 is disposed between the magnetic saturation coil 2 and the passing steel pipe 4 of the above-described apparatus, and a detector 9 changes the voltage of the surface flaw detection coil 8. , And an experiment for detecting bead dust and surface flaws is performed using an apparatus configured to detect surface flaws. In addition,
Numeral 10 denotes a calculator for discriminating between surface flaws and metal residues, and numeral 11 denotes a sleeve for supporting the magnetic saturation coil 1.
【００２８】外径３８．１ｍｍ、肉厚４ｍｍの電縫管内
に、断面積４ｍｍ2 、長さ５０ｍｍのビード屑および幅
０．５ｍｍ、深さ２ｍｍ、長さ５０ｍｍの軸方向ノッチ
疵が存する状態を、巻幅４００ｍｍの磁気飽和コイル
と、内径４３ｍｍ、幅７ｍｍの自己誘導相互比較式の金
属残留物検出用検出コイルと、内径４３ｍｍ、幅７−２
−７ｍｍの自己誘導自己比較式の表面疵検出用検出コイ
ルを有する装置にてビード屑および表面疵の検出実験を
行い、図９・１１に示す結果を得た。なお、金属残留物
検出用検出コイルに供給した電圧の周波数は４ｋＨｚで
あり、表面疵検出用検出コイルに供給した電圧の周波数
は８ｋＨｚである。A state in which an electric resistance welded tube having an outer diameter of 38.1 mm and a wall thickness of 4 mm has bead dust having a cross-sectional area of 4 mm 2 and a length of 50 mm and an axial notch flaw having a width of 0.5 mm, a depth of 2 mm and a length of 50 mm. With a magnetic saturation coil having a winding width of 400 mm, a self-induction mutual comparison type detection coil for detecting metal residues having an inner diameter of 43 mm and a width of 7 mm, an inner diameter of 43 mm and a width of 7-2.
An experiment for detecting bead dust and surface flaws was performed using an apparatus having a self-induction self-comparison type surface flaw detection coil of -7 mm, and the results shown in FIGS. 9 and 11 were obtained. The frequency of the voltage supplied to the detection coil for detecting metal residue is 4 kHz, and the frequency of the voltage supplied to the detection coil for detecting surface flaws is 8 kHz.
【００２９】図９は、金属残留物検出用検出コイルと表
面疵検出用検出コイルを共に磁気飽和コイルの中央部に
設置した場合における鋼管に加える磁界の強さと金属残
留物検出用検出コイルおよび表面疵検出用検出コイルで
検出したビード屑および軸方向ノッチ疵の検出能の高さ
を示す。図１１は、鋼管の中心部に発生する磁界の磁束
密度が１．６Ｔとなるように磁界を加えた場合における
磁気飽和コイル中央から金属残留物検出用検出コイル中
央までの間隔と金属残留物検出用検出コイル位置での鋼
管中心部の磁束密度との関係を示す。なお、この図１１
中において、磁気飽和コイル中央から金属残留物検出用
検出コイル中央までの間隔０．１ｍ付近で金属残留物検
出用検出コイル位置での鋼管中心部の磁束密度が低下し
ているのは、磁気飽和コイルを支持するために設けたス
リーブの影響である。FIG. 9 shows the intensity of the magnetic field applied to the steel pipe when the detection coil for detecting the metal residue and the detection coil for detecting the surface flaw are both installed at the center of the magnetic saturation coil, and the detection coil and the surface for detecting the metal residue. Fig. 3 shows the detection ability of bead dust and axial notch flaws detected by a flaw detection coil. FIG. 11 shows the distance from the center of the magnetic saturation coil to the center of the detection coil for detecting metal residue and the detection of metal residue when a magnetic field is applied so that the magnetic flux density of the magnetic field generated at the center of the steel pipe becomes 1.6T. The relationship with the magnetic flux density at the center of the steel pipe at the position of the detection coil is shown. Note that FIG.
In the meantime, the magnetic flux density at the center of the steel pipe at the position of the detection coil for metal residue detection decreases around 0.1 m from the center of the magnetic saturation coil to the center of the detection coil for metal residue detection because of the magnetic saturation This is due to the effect of the sleeve provided to support the coil.
【００３０】図９より、鋼管の中心部に発生する磁界の
磁束密度が０．１〜０．４Ｔであるとビード屑のみを容
易に検出でき、鋼管の中心部に発生する磁界の磁束密度
が０．４Ｔ以上であると表面疵のみを容易に検出できる
ことが明らかである。ちなみに、本被検材は、鋼管の中
心部に発生する磁界の磁束密度が約０．１Ｔとなるよう
に磁界を加えた時に磁気飽和するので、本被検材におい
てビード屑のみを検出する場合には、金属残留物検出用
検出コイル周辺における被検材の中心部に発生する磁界
の磁束密度が磁気飽和する磁束密度の１００〜４００％
の磁界を加えるのが最適である。なお、ビード屑のみを
検出するために鋼管に加える最適な磁界の強さは、被検
材の材質や寸法等によって異なり、例えば図１０に示す
ように、被検材の肉厚によって鋼管に加える磁界の強さ
とビード屑検出能との関係は変化する。FIG. 9 shows that when the magnetic flux density of the magnetic field generated at the center of the steel pipe is 0.1 to 0.4 T, only the bead dust can be easily detected, and the magnetic flux density of the magnetic field generated at the center of the steel pipe is reduced. It is clear that only 0.4T or more can easily detect only surface flaws. By the way, this test material is magnetically saturated when a magnetic field is applied so that the magnetic flux density of the magnetic field generated at the center of the steel pipe becomes about 0.1 T. Therefore, when only bead dust is detected in this test material, The magnetic flux density of the magnetic field generated in the center of the test material around the detection coil for detecting metal residue is 100 to 400% of the magnetic flux density at which the magnetic saturation occurs.
It is optimal to apply a magnetic field of The optimum strength of the magnetic field applied to the steel pipe in order to detect only the bead debris varies depending on the material and dimensions of the test material, and for example, as shown in FIG. The relationship between the strength of the magnetic field and the ability to detect bead debris changes.
【００３１】図１１より、金属残留物検出用検出コイル
と磁気飽和コイルとの距離を約０．３〜０．５ｍに設定
すると、ビード屑を確実に検出できる。ちなみに、鋼管
の中心部に発生する磁界の磁束密度が１．６Ｔとなるよ
うに磁界を加えたのは、従来表面疵検出用として表面疵
検出用検出コイルをその内部に配設した磁気飽和コイル
が鋼管に加える磁界の強さであって、上記の間隔を存し
て金属残留物検出用検出コイルと磁気飽和コイルを設置
するとビード屑の検出と共に表面疵検出用検出コイルに
よって表面疵を確実に検出できる。As shown in FIG. 11, when the distance between the detection coil for detecting metal residue and the magnetic saturation coil is set to about 0.3 to 0.5 m, the bead dust can be reliably detected. Incidentally, the reason why the magnetic field was applied so that the magnetic flux density of the magnetic field generated in the central portion of the steel pipe was 1.6 T is that the conventional magnetic saturation coil in which a detection coil for detecting surface flaws is disposed for detecting surface flaws. Is the strength of the magnetic field applied to the steel pipe, and if the detection coil for metal residue detection and the magnetic saturation coil are installed with the above-mentioned interval, bead chips are detected and the surface flaw is detected by the detection coil for surface flaw detection. Can be detected.
【００３２】鋼管毎に、磁気飽和コイルと金属残留物検
出用検出コイルとの間隔および金属残留物検出用検出コ
イルに供給する交流電圧の周波数を実験で求め、予め金
属残留物検出用検出コイルの位置および金属残留物検出
用検出コイルに供給する電圧の諸条件を設定して金属残
留物の検出を行えばよい。The distance between the magnetic saturation coil and the detection coil for detecting metal residue and the frequency of the AC voltage supplied to the detection coil for detecting metal residue were determined experimentally for each steel pipe, and the frequency of the detection coil for detecting metal residue was determined in advance. It is only necessary to set various conditions of the position and the voltage to be supplied to the detection coil for metal residue detection, and detect the metal residue.
【００３３】表面疵検出用検出コイルを磁気飽和コイル
内部に設置することによって、金属残留物の検出と共に
表面疵の検出が可能で、一体化した検出装置を作成可能
である。また、検査される鋼管毎に複数の金属残留物検
出用検出コイルを所定の間隔を存して設置したり、移動
可能なように装置を構成してもよい。さらに、磁気飽和
コイルを中心として金属残留物検出用検出コイルを対称
に設置すれば検出精度の向上が図れる。By installing the detection coil for detecting surface flaws inside the magnetic saturation coil, it is possible to detect metal flaws as well as surface flaws, and to produce an integrated detection device. Further, a plurality of metal residue detection detection coils may be installed at predetermined intervals for each steel pipe to be inspected, or the apparatus may be configured to be movable. Further, if the detection coil for detecting the metal residue is symmetrically disposed around the magnetic saturation coil, the detection accuracy can be improved.
【００３４】[0034]
【発明の効果】以上説明したように、本発明方法によれ
ば、表面疵と区別して、鋼管内の金属残留物を高速に非
接触で自動検出できる。さらに、本発明方法では鋼管の
長さの影響を受けずに金属残留物を検出できるので、鋼
管の長さにバラツキがあっても検出精度は変化しない。
また、使用する検出装置を小さくできるので、設置場所
が限定されない。特に、表面疵検出用渦流装置と一体化
すれば、より空間の有効利用が図れるとともに、金属残
留物と表面疵の検出および弁別が容易となる。As described above, according to the method of the present invention, a metal residue in a steel pipe can be automatically detected at high speed and without contact, in distinction from surface flaws. Further, in the method of the present invention, since the metal residue can be detected without being affected by the length of the steel pipe, the detection accuracy does not change even if the length of the steel pipe varies.
In addition, since the detection device to be used can be made small, the installation place is not limited. In particular, when integrated with the eddy current device for surface flaw detection, more effective use of space can be achieved, and detection and discrimination of metal residues and surface flaws can be facilitated.
【図１】請求項１に対応する本発明方法を実施する設備
の概要を示す図である。FIG. 1 is a diagram showing an outline of equipment for implementing the method of the present invention corresponding to claim 1;
【図２】測定原理を示す図であり、鋼管内に金属残留物
が存在しない状態を示す。FIG. 2 is a view showing a principle of measurement and shows a state in which no metal residue is present in a steel pipe.
【図３】測定原理を示す図であり、鋼管内に金属残留物
が存在する状態を示す。FIG. 3 is a view showing a principle of measurement and shows a state in which a metal residue is present in a steel pipe.
【図４】標準的な低炭素鋼管に加えた磁界の強さと鋼管
および金属残留物の比透磁率との関係を示す図である。FIG. 4 is a diagram showing the relationship between the strength of a magnetic field applied to a standard low carbon steel pipe and the relative permeability of the steel pipe and metal residues.
【図５】鋼管に発生する磁界の磁束密度を変化させた場
合でのビード屑および軸方向ノッチ疵の検出信号の高さ
を示す図である。FIG. 5 is a diagram showing the height of detection signals of bead chips and axial notch flaws when the magnetic flux density of a magnetic field generated in a steel pipe is changed.
【図６】検出コイルに供給する交流電圧の周波数を変化
させた場合でのビード屑および軸方向ノッチ疵の検出信
号の高さを示す図である。FIG. 6 is a diagram illustrating the heights of detection signals of bead dust and axial notch flaws when the frequency of an AC voltage supplied to a detection coil is changed.
【図７】請求項２に対応する本発明方法を実施する設備
の概要を示す図である。FIG. 7 is a diagram showing an outline of equipment for carrying out the method of the present invention corresponding to claim 2;
【図８】請求項２に対応する本発明方法によるビード屑
および表面疵の検出実験に用いた装置の構成を示す図で
ある。FIG. 8 is a view showing a configuration of an apparatus used in an experiment for detecting bead dust and surface flaws according to the method of the present invention corresponding to claim 2;
【図９】鋼管に加える磁界の強さとビード屑および軸方
向ノッチ疵の検出能を示す図である。FIG. 9 is a diagram showing the strength of a magnetic field applied to a steel pipe and the ability to detect bead dust and axial notch flaws.
【図１０】鋼管の肉厚が変化した場合における鋼管に加
える磁界の強さとビード屑検出能を示す図である。FIG. 10 is a diagram showing the strength of a magnetic field applied to the steel pipe and the bead debris detection ability when the thickness of the steel pipe changes.
【図１１】磁気飽和コイル中央から金属残留物検出用検
出コイル中央までの間隔と金属残留物検出用検出コイル
位置での鋼管中心部の磁束密度との関係を示す図であ
る。FIG. 11 is a diagram showing the relationship between the distance from the center of the magnetic saturation coil to the center of the detection coil for detecting metal residue and the magnetic flux density at the center of the steel pipe at the position of the detection coil for detecting metal residue.
１ 検出部 ２ 磁気飽和コイル ３ 検出コイル ４ 鋼管 ５ 金属残留物 ６ 直流電源装置 ７ 検出器 ８ 表面疵検出コイル ９ 検出器 １０ 演算器 １１ スリーブ DESCRIPTION OF SYMBOLS 1 Detection part 2 Magnetic saturation coil 3 Detection coil 4 Steel pipe 5 Metal residue 6 DC power supply 7 Detector 8 Surface flaw detection coil 9 Detector 10 Computing unit 11 Sleeve
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭60−247158（ＪＰ，Ａ) 特開 昭63−163267（ＪＰ，Ａ) 実開 昭59−4464（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.6，ＤＢ名) G01V 3/10 G01N 27/90 ────────────────────────────────────────────────── (5) References JP-A-60-247158 (JP, A) JP-A-63-163267 (JP, A) JP-A-59-4644 (JP, U) (58) Field (Int.Cl. 6 , DB name) G01V 3/10 G01N 27/90
Claims (2)
の渦電流検出コイル周辺に磁界を付与する磁気コイルを
臨ませ、金属管は磁気飽和し該金属管内に存する金属残
留物は磁気飽和しない程度に磁化した状態と成るように
前記磁気コイルに予め金属管毎に求めてある電流を供給
し、前記渦電流検出コイルに供給する電圧の電圧変化を
測定して前記金属管内に存する金属残留物を検出するこ
とを特徴とする金属管内の金属残留物検出方法。1. An eddy current detection coil and a magnetic coil for applying a magnetic field around the eddy current detection coil face the outer periphery of the metal tube. The metal tube is magnetically saturated, and the metal residue existing in the metal tube is magnetically saturated. A current determined in advance for each metal tube is supplied to the magnetic coil so as to be in a magnetized state so as not to be magnetized, and a voltage change of a voltage supplied to the eddy current detection coil is measured to determine a residual metal remaining in the metal tube. A method for detecting a metal residue in a metal tube, comprising detecting an object.
の渦電流検出コイル周辺に磁界を付与する磁気コイルを
臨ませ、前記渦電流検出コイル周辺の金属管は磁気飽和
し該金属管内に存する金属残留物は磁気飽和しない程度
に磁化した状態と成るように予め金属管毎に求めてある
所定の間隔を存して前記磁気コイルと前記渦電流検出コ
イルを設置し、前記渦電流検出コイルに供給する電圧の
電圧変化を測定して前記金属管内に存する金属残留物を
検出することを特徴とする金属管内の金属残留物検出方
法。2. An eddy current detection coil and a magnetic coil for applying a magnetic field around the eddy current detection coil are provided on the outer periphery of the metal tube. The metal tube around the eddy current detection coil is magnetically saturated and enters the metal tube. The magnetic coil and the eddy current detection coil are installed at a predetermined interval previously determined for each metal tube so that the existing metal residue is magnetized to a degree that does not cause magnetic saturation. Detecting a metal residue in the metal tube by measuring a voltage change of a voltage supplied to the metal tube.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10822194A JP2959395B2 (en) | 1993-06-23 | 1994-05-23 | Metal residue detection method in metal tube |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15167493 | 1993-06-23 | ||
| JP5-151674 | 1993-06-23 | ||
| JP10822194A JP2959395B2 (en) | 1993-06-23 | 1994-05-23 | Metal residue detection method in metal tube |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0772263A JPH0772263A (en) | 1995-03-17 |
| JP2959395B2 true JP2959395B2 (en) | 1999-10-06 |
Family
ID=26448159
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10822194A Expired - Lifetime JP2959395B2 (en) | 1993-06-23 | 1994-05-23 | Metal residue detection method in metal tube |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2959395B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4698174B2 (en) * | 2004-06-29 | 2011-06-08 | 東京電力株式会社 | Steel pipe inner surface deterioration detection method and apparatus |
| WO2019187233A1 (en) | 2018-03-27 | 2019-10-03 | 日本製鉄株式会社 | Method and device for detecting metal residue in electric-resistance-welded steel pipe |
| CN111590179A (en) * | 2020-06-04 | 2020-08-28 | 江苏宝强钢结构有限公司 | Efficient full-automatic steel structure welding technology and method thereof |
-
1994
- 1994-05-23 JP JP10822194A patent/JP2959395B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0772263A (en) | 1995-03-17 |
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