JP4622742B2 - Method and apparatus for detecting eddy current in metal strip - Google Patents
Method and apparatus for detecting eddy current in metal strip Download PDFInfo
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本発明は、導体である金属帯表層に存在する欠陥を高精度に検出する、金属帯の渦流探傷方法および装置に関するものである。 The present invention relates to a metal band eddy current flaw detection method and apparatus for detecting a defect existing in a metal band surface layer as a conductor with high accuracy.
導体である金属帯の表層に存在する欠陥を検出する方法として、渦流探傷法が広く使用されている。渦流探傷法は、励磁（１次）コイルにより導電体の表層に渦電流を発生させ、その渦電流によって検出（２次）コイルに発生する誘導電圧を検出することにより欠陥を検出するものである。金属帯の表面に欠陥があった場合には、渦電流の流れに変化が起き、それに伴って誘導電圧が変化するので、欠陥の検出が可能となる。このような渦流センサを、例えば鉄鋼製造プロセスにおける酸洗ラインへ適用し、後工程である冷間圧延ラインへ挿入する前にヘゲ欠陥を検出できれば、あらかじめヘゲ部を除去したり、ヘゲ混入情報を冷間圧延ラインへ伝達し、ヘゲ部について圧延ミルの開放などを行うことで、ヘゲ欠陥による板破断や圧延ロールへのダメージを未然に防ぐことが可能となる。 As a method for detecting defects present on the surface layer of a metal band that is a conductor, an eddy current flaw detection method is widely used. In the eddy current flaw detection method, an eddy current is generated on the surface layer of a conductor by an excitation (primary) coil, and a defect is detected by detecting an induced voltage generated in the detection (secondary) coil by the eddy current. . When there is a defect on the surface of the metal strip, a change occurs in the flow of eddy current, and the induced voltage changes accordingly, so that the defect can be detected. If such a eddy current sensor is applied to, for example, a pickling line in a steel production process, and a hege defect can be detected before being inserted into a cold rolling line, which is a subsequent process, the shaving portion can be removed in advance. By transmitting the mixing information to the cold rolling line and opening the rolling mill for the shaving portion, it becomes possible to prevent the sheet breakage due to the shaving defect and damage to the rolling roll.
渦流探傷法に使用されるセンサとして、例えば、特許文献１に示すような、Ｅ型形状をしたセンサが開示されている。Ｅ型センサを使用した渦流探傷の原理を、図４に示す。図４において、１はセンサ、１ａは１次コイル、１ｂ、１ｃは２次コイル、２は金属帯(鋼帯)、３は欠陥をそれぞれ示す。ここで１次コイル１ａの両端１a１、１a２には交流電源が接続され、これによって鋼帯２には、矢印で示されるような渦電流が発生する。また、２次コイル１ｂ、１ｃは直列に差動接続されており、これら検出コイルに同じ向きでかつ大きさの等しい交流磁界が差交する場合には、お互いに打ち消し合うことで、検出コイル両端１ｂ１、１ｃ１間に誘起される起電力は０となる。 As a sensor used in the eddy current flaw detection method, for example, a sensor having an E shape as disclosed in Patent Document 1 is disclosed. The principle of eddy current flaw detection using an E-type sensor is shown in FIG. In FIG. 4, 1 is a sensor, 1a is a primary coil, 1b and 1c are secondary coils, 2 is a metal strip (steel strip), and 3 is a defect. Here, an AC power source is connected to both ends 1a1 and 1a2 of the primary coil 1a, whereby an eddy current as indicated by an arrow is generated in the steel strip 2. Further, the secondary coils 1b and 1c are differentially connected in series. When AC magnetic fields having the same direction and the same magnitude cross in these detection coils, both ends of the detection coils are canceled by canceling each other. The electromotive force induced between 1b1 and 1c1 is zero.
鋼帯に欠陥がないときは、２次コイル１ｂ、１ｃに発生する誘導電圧は同じであるため、差動接続された二つの２次コイルの誘導電圧の出力は、ほぼゼロになる。図４に示されるように、２次コイル１ｃの近傍にのみ欠陥３が存在する場合には、渦電流変化により二つの２次コイルに発生する誘導電圧に差が発生するので、両コイルの誘導電圧の差分がゼロでなくなり、差動接続された２つの２次コイルの両端には出力を生じる。結果として、図４の下図に示すように、上方に固定されたセンサの下方を欠陥３を有する金属帯２が矢印の方向へ移動したとき、位相検波後の出力は、センサ１の中心軸を中心としたサインカーブ状の波形を描くことで、欠陥の検出が可能となる。なお、ここでは１ａを１次コイル、１ｂ及び１ｃを２次コイルとしたが、逆にしても上記差分効果が得られるので、１ｂ及び１ｃを１次コイル、１ａを２次コイルとしても良い。 When there is no defect in the steel strip, the induced voltages generated in the secondary coils 1b and 1c are the same, and therefore the output of the induced voltage of the two differentially connected secondary coils is almost zero. As shown in FIG. 4, when the defect 3 exists only in the vicinity of the secondary coil 1c, a difference occurs in the induced voltage generated in the two secondary coils due to the eddy current change. The voltage difference is not zero, and an output is generated at both ends of the two differentially connected secondary coils. As a result, as shown in the lower diagram of FIG. 4, when the metal band 2 having the defect 3 moves in the direction of the arrow below the sensor fixed above, the output after phase detection is centered on the sensor 1. A defect can be detected by drawing a waveform having a sine curve shape at the center. Here, 1a is a primary coil, and 1b and 1c are secondary coils. However, since the above difference effect can be obtained even if reversed, 1b and 1c may be primary coils and 1a may be secondary coils.
図６は、鉄鋼製造プロセスにおける酸洗ライン出側のブライドルロール上へ、幅方向へ３４ｍｍピッチで配列された前記Ｅ型渦流センサ群の下方を、幅約２０ｍｍのヘゲが通過した際の、ヘゲ直上付近センサチャンネルの出力信号をフィルタ処理した後の波形である（後にヘゲ信号の、幅方向特性について述べるため、センサ直上の左右２チャンネル（ＣＨ）分の波形についても図示し、ヘゲ直上ＣＨも含め合計５ＣＨ分〈(a)〜(e)〉図示している）。なお、フィルタ処理は、Ｓ／Ｎ向上させるため、ヘゲ信号周波数近傍の信号を取り出す処理である。 FIG. 6 shows a state in which a hege having a width of about 20 mm passes under the E-type eddy current sensor group arranged at a pitch of 34 mm in the width direction onto a bridle roll on the side of the pickling line in the steel manufacturing process. This is a waveform after filtering the output signal of the sensor channel immediately above the hege (in order to describe the width direction characteristic of the hege signal later, the waveforms for the left and right channels (CH) immediately above the sensor are also shown, (5) A total of 5 CH including the CH directly above (<a) to (e)> are shown). The filter process is a process for extracting a signal in the vicinity of the hege signal frequency in order to improve S / N.
図６より、あらかじめ欠陥判定しきい値を正負に設け、これを超えたものについて欠陥判定するようにすることで、ヘゲ欠陥の検出が可能となる。
しかしながら、酸洗ラインを流れる板の溶接部近傍は、上工程である熱間圧延ライン走行時に、ランナウトテーブルロール上をバウンドしながら通板されるため、材質荒れによる板幅方向に広く分布した材料ノイズが存在する。この材料ノイズは、有害ヘゲ欠陥による信号レベルに近接しているため、欠陥判定しきい値との比較のみでは、前記溶接部近傍材料ノイズのヘゲ欠陥への誤検出が発生する。 However, the material near the welded portion of the plate flowing through the pickling line is passed widely while bouncing on the run-out table roll during the hot rolling line, which is the upper process, so that the material is widely distributed in the plate width direction due to material roughness There is noise. Since the material noise is close to the signal level due to the harmful hege defect, erroneous detection of the material noise in the vicinity of the weld to the hege defect occurs only by comparison with the defect determination threshold value.
図７は、図６同様に、幅方向へ３４ｍｍピッチで配列された５６ＣＨのＥ型渦流センサのうち、２０、２５、３０、３５、および４０ＣＨの５ＣＨ分について、そのフィルタ処理後の溶接部近傍材料ノイズ波形を示す。このように、板幅方向に広い範囲で分布している溶接部近傍の材料ノイズ（矢印にて表示）は、ヘゲ欠陥信号レベル（図６）と比較して無視できないレベルにあるため、ヘゲ欠陥として誤判定してしまう。この溶接部近傍の材料ノイズによる過検出を抑制するため、溶接部近傍をマスク処理する方法があるが、ヘゲ欠陥はむしろ溶接部近傍に多く、よって溶接部近傍のマスク区間は極力小さい方が望ましい。 FIG. 7 is similar to FIG. 6, among the 56CH E-type eddy current sensors arranged at a pitch of 34 mm in the width direction, in the vicinity of the welded portion after filtering for 20, 25, 30, 35, and 40CH of 5CH. The material noise waveform is shown. Thus, the material noise (indicated by arrows) near the weld that is distributed over a wide range in the plate width direction is at a level that cannot be ignored compared to the hege defect signal level (FIG. 6). It is erroneously determined as a defect. In order to suppress over-detection due to material noise in the vicinity of the weld, there is a method of masking the vicinity of the weld. However, there are many hege defects near the weld. Therefore, the mask section near the weld should be as small as possible. desirable.
本発明は上記事情に鑑みてなされたもので、溶接部近傍材料ノイズとヘゲ欠陥とを分離することができる金属帯の渦流探傷方法および装置を提供することにある。 The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a metal strip eddy current flaw detection method and apparatus that can separate material noise in the vicinity of a weld and lash defects.
発明者らはこの課題に対して検討を加えた結果、「ヘゲによる板幅信号分布は、図６に示すようにセンサ直下より外れると急激に減衰するのに対して、溶接部近傍材料ノイズによる信号分布は、図７に示すように板幅方向に広がりを持ったものとなる」という知見を得て、本発明に至った。 As a result of investigations on this problem, the inventors have found that “the plate width signal distribution due to the stubs abruptly attenuates when it deviates from just below the sensor as shown in FIG. As a result, the present invention has reached the present invention.
本発明の請求項１に係る発明は、複数個の渦流センサを走行する金属帯の幅方向に配置し、前記センサそれぞれの出力をフィルタ処理し、フィルタ処理後のそれぞれの出力と欠陥判定しきい値との比較により、欠陥判定部位を検出する演算処理工程を有する金属帯の渦流探傷方法において、前記演算処理工程は、（イ）前記フィルタ処理後のそれぞれの出力と、前記欠陥判定しきい値よりも低いレベルに設定された、材料ノイズ判定しきい値との比較を行い、該材料ノイズ判定しきい値を超えた出力のチャンネル数を幅方向にカウントし、そのカウント数があらかじめ設定された材料ノイズ判定チャンネル数以上であれば、材料ノイズと判定し、この材料ノイズ判定部位を前記欠陥判定部位から除き、（ロ）前記フィルタ処理後のそれぞれの出力と、前記欠陥判定しきい値よりも、高いレベルに設定された第２の欠陥判定しきい値との比較を行い、該第２の欠陥判定しきい値を超えた出力が出た場合は、該出力のチャンネルにおける前記（イ）の処理を行わないことを特徴とする金属帯の渦流探傷方法である。 In the invention according to claim 1 of the present invention, a plurality of eddy current sensors are arranged in the width direction of the traveling metal strip, the output of each of the sensors is filtered, and the respective outputs after filtering and the defect determination threshold are determined. In the eddy current flaw detection method for a metal strip having a calculation processing step for detecting a defect determination portion by comparing with a value, the calculation processing step includes (a) each output after the filtering, and the defect determination threshold value. Compared with the material noise judgment threshold value set to a lower level, the number of output channels exceeding the material noise judgment threshold value is counted in the width direction, and the count number is preset. If it is equal to or greater than the number of material noise determination channels, it is determined as material noise, this material noise determination part is excluded from the defect determination part, and (b) each after the filtering process And when the output exceeds the second defect determination threshold value, the second defect determination threshold value set to a level higher than the defect determination threshold value is compared. The method for detecting eddy currents in a metal strip is characterized by not performing the process (a) in the output channel.
また本発明の請求項２に係る発明は、複数個の渦流センサを走行する金属帯の幅方向に配置し、前記センサそれぞれの出力をフィルタ処理し、フィルタ処理後のそれぞれの出力と欠陥判定しきい値との比較により、欠陥判定部位を検出する演算処理工程を有する金属帯の渦流探傷方法において、前記演算処理工程は、（イ）金属帯の一定移動量ピッチ毎に、前記センサそれぞれの出力をＡ／Ｄ変換およびフィルタ処理した後、金属帯の所定長さ分だけ区間データとして収集する区間データサンプリング工程と、（ロ）前記区間データと、あらかじめ設定された欠陥判定しきい値との比較により、欠陥判定部位を検出する欠陥判定部検出工程と、（ハ）前記区間データと、前記欠陥判定しきい値よりも低いレベルに設定された、材料ノイズ判定しきい値との比較を行い、該材料ノイズ判定しきい値を超えたデータのチャンネル数を幅方向にカウントし、そのカウント数があらかじめ設定された材料ノイズ判定チャンネル数以上であれば、材料ノイズと判定し、当該長手位置を起点とした、前記所定長さ内の、所定の前後材料ノイズ判定長さ内の全チャンネル部位を前記欠陥判定部位から除く欠陥判定部リジェクト工程と、（ニ）前記区間データと、前記欠陥判定しきい値よりも、高いレベルに設定された第２の欠陥判定しきい値との比較を行い、該第２の欠陥判定しきい値を超えたデータが出た場合は、当該長手位置における前記欠陥判定部リジェクト工程の処理を行わない判定区間再演算工程と、を有することを特徴とする金属帯の渦流探傷方法である。 In the invention according to claim 2 of the present invention, a plurality of eddy current sensors are arranged in the width direction of the running metal strip, the output of each of the sensors is filtered, and each output after filtering is determined as a defect. In the eddy current flaw detection method for a metal strip having a calculation processing step for detecting a defect determination site by comparison with a threshold value, the calculation processing step includes: (a) an output of each of the sensors for each fixed movement pitch of the metal strip. After the A / D conversion and filtering process, the section data sampling step of collecting as a section data for a predetermined length of the metal band, and (b) comparison between the section data and a preset defect determination threshold value And (c) the material noise determination, which is set to a level lower than the defect determination threshold value. Comparison is made with the threshold value, the number of channels of data exceeding the material noise judgment threshold is counted in the width direction, and if the count is equal to or greater than the preset number of material noise judgment channels, A defect determination unit rejecting step for determining and removing all channel portions within the predetermined length within a predetermined length of the front and rear material noise from the defect determination portion, starting from the longitudinal position, and (d) the section When the data is compared with the second defect determination threshold value set to a level higher than the defect determination threshold value, and data exceeding the second defect determination threshold value is output And a determination section recalculation step in which the processing of the defect determination unit rejection step at the longitudinal position is not performed.
また本発明の請求項３に係る発明は、走行する金属帯の幅方向に配置した複数個の渦流センサと、該センサそれぞれの出力をフィルタ処理し、フィルタ処理後のそれぞれの出力と欠陥判定しきい値との比較により、欠陥判定部位を検出する演算処理部とを有する金属帯の渦流探傷装置において、前記演算処理部は、（イ）前記フィルタ処理後のそれぞれの出力と、前記欠陥判定しきい値よりも低いレベルに設定された、材料ノイズ判定しきい値との比較を行い、該材料ノイズ判定しきい値を超えた出力のチャンネル数を幅方向にカウントし、そのカウント数があらかじめ設定された材料ノイズ判定チャンネル数以上であれば、材料ノイズと判定し、この材料ノイズ判定部位を前記欠陥判定部位から除く欠陥判定部リジェクト手段と、（ロ）前記フィルタ処理後のそれぞれの出力と、前記欠陥判定しきい値よりも、高いレベルに設定された第２の欠陥判定しきい値との比較を行い、該第２の欠陥判定しきい値を超えた出力が出た場合は、該出力のチャンネルにおける前記（イ）の処理を行わない判定区間再演算手段とを備えることを特徴とする金属帯の渦流探傷装置である。 In the invention according to claim 3 of the present invention, a plurality of eddy current sensors arranged in the width direction of the traveling metal strip and the outputs of the sensors are filtered, and the outputs and the defects after the filtering are determined. In the eddy current flaw detection apparatus for a metal strip having a calculation processing unit for detecting a defect determination site by comparison with a threshold value, the calculation processing unit (i) determines each defect and the output after the filtering process. Compare with the material noise judgment threshold value set to a level lower than the threshold, count the number of output channels exceeding the material noise judgment threshold value in the width direction, and set the count number in advance. If the number of material noise determination channels is equal to or greater than the number, the material noise determination portion is determined, and the material noise determination portion is excluded from the defect determination portion. Each output after the filtering process is compared with the second defect determination threshold set to a level higher than the defect determination threshold, and the second defect determination threshold is exceeded. A metal band eddy current flaw detection device comprising: a determination interval recalculation unit that does not perform the process (a) in the output channel when an output is output.
さらに本発明の請求項４に係る発明は、走行する金属帯の幅方向に配置した複数個の渦流センサと、該センサそれぞれの出力をフィルタ処理し、フィルタ処理後のそれぞれの出力と欠陥判定しきい値との比較により、欠陥判定部位を検出する演算処理部とを有する金属帯の渦流探傷装置において、前記演算処理部は、（イ）金属帯の一定移動量ピッチ毎に、前記センサそれぞれの出力をＡ／Ｄ変換およびフィルタ処理した後、金属帯の所定長さ分だけ区間データとして収集する区間データサンプリング手段と、（ロ）前記区間データと、あらかじめ設定された欠陥判定しきい値との比較により、欠陥判定部位を検出する欠陥判定部検出手段と、（ハ）前記区間データと、前記欠陥判定しきい値よりも低いレベルに設定された、材料ノイズ判定しきい値との比較を行い、該材料ノイズ判定しきい値を超えたデータのチャンネル数を幅方向にカウントし、そのカウント数があらかじめ設定された材料ノイズ判定チャンネル数以上であれば、材料ノイズと判定し、当該長手位置を起点とした、前記所定長さ内の、所定の前後材料ノイズ判定長さ内の全チャンネル部位を前記欠陥判定部位から除く欠陥判定部リジェクト手段と、（ニ）前記区間データと、前記欠陥判定しきい値よりも、高いレベルに設定された第２の欠陥判定しきい値との比較を行い、該第２の欠陥判定しきい値を超えたデータが出た場合は、当該長手位置における前記欠陥判定部リジェクト手段の処理を行わない判定区間再演算手段と、を備えることを特徴とする金属帯の渦流探傷装置である。 Furthermore, the invention according to claim 4 of the present invention is to filter a plurality of eddy current sensors arranged in the width direction of the traveling metal strip and the outputs of each of the sensors, and determine a defect with each output after the filtering process. In the eddy current flaw detection apparatus for a metal strip having a calculation processing section for detecting a defect determination site by comparison with a threshold value, the calculation processing section is: (a) for each constant movement amount pitch of the metal band, After the output is A / D converted and filtered, section data sampling means for collecting section data for a predetermined length of the metal band, (b) the section data, and a predetermined defect determination threshold value Defect determination unit detecting means for detecting a defect determination site by comparison, (c) Material noise determination set at a level lower than the section data and the defect determination threshold value Comparison is made with the threshold value, the number of channels of data exceeding the material noise judgment threshold is counted in the width direction, and if the count is equal to or greater than the preset number of material noise judgment channels, A defect determination unit rejecting means for determining and removing all channel portions within the predetermined length within a predetermined length of the front and rear material noise from the defect determination portion, starting from the longitudinal position, and (d) the section When the data is compared with the second defect determination threshold value set to a level higher than the defect determination threshold value, and data exceeding the second defect determination threshold value is output A metal band eddy current flaw detector comprising: a determination section recalculation unit that does not perform the processing of the defect determination unit rejection unit at the longitudinal position.
本発明によれば、まず低いレベルにて設定された材料ノイズ判定しきい値による比較を行うことで、材料ノイズの輪郭抽出を行い、次に、しきい値を超えたチャンネルについて幅方向にカウントした個数に対し、あらかじめ設定された材料ノイズ判定チャンネル個数と比較することで、これを超えた場合には、ヘゲ欠陥でなく、材料ノイズであるという判定を行うとともに、
通常の欠陥判定しきい値よりも高いレベルで設定された第２の欠陥判定しきい値を有し、これを超えたものについては、前記材料ノイズ判定処理を行わないようにしたので、
信号レベルがヘゲ信号に近接していても、材料ノイズのヘゲ欠陥への誤検出を防止するとともに、巨大ヘゲ欠陥の見逃しの防止も可能となる。
According to the present invention, first, the contour of the material noise is extracted by performing comparison with the material noise determination threshold set at a low level, and then the channel exceeding the threshold is counted in the width direction. In comparison with the preset number of material noise determination channels, the number of the determined number is determined not to be a hege defect but to material noise when exceeding this,
Since the second defect determination threshold value set at a level higher than the normal defect determination threshold value is exceeded, the material noise determination process is not performed for those exceeding this,
Even if the signal level is close to the shave signal, it is possible to prevent erroneous detection of material noise to shave defects and to prevent the missed giant shave defect.
また、所定長さ分だけ演算処理部へ全チャンネル分のデータを取り込み、各種演算処理をした上で、材料ノイズ判定しきい値超えチャンネル数をカウントし、所定長さ内で前記材料ノイズ判定チャンネル個数を超えた長手位置に対し、前後材料ノイズ判定長さ内の前後データについて、材料ノイズ判定処理するようにしたので、
幅方向に均一に存在しない材料ノイズであっても、ヘゲ欠陥への誤検出防止が可能である。
In addition, data for all channels is fetched into the arithmetic processing unit for a predetermined length, and after various arithmetic processing, the number of channels exceeding the material noise determination threshold is counted, and the material noise determination channel is within the predetermined length. Since the front and back data within the front and rear material noise judgment length is processed for the longitudinal position exceeding the number, the material noise judgment processing is performed.
Even if the material noise does not exist uniformly in the width direction, it is possible to prevent erroneous detection of a bald defect.
本発明を実施するための最良の形態を、図面を参照しながら以下説明する。図１は、本発明に係る金属帯の渦流探傷装置の概要を説明する図である。図中、１はセンサ、４は渦流信号処理アンプ、５はＡ／Ｄ変換器、６は演算処理部、および７はラインＰＬＧをそれぞれ表す。 The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining the outline of a metal strip eddy current flaw detector according to the present invention. In the figure, 1 is a sensor, 4 is an eddy current signal processing amplifier, 5 is an A / D converter, 6 is an arithmetic processing unit, and 7 is a line PLG.
複数のＥ型渦流センサ１を、測定したい方向（例えば、板幅方向）に所定のピッチにて配列する。各々のセンサは、渦流信号処理アンプ４に接続されており、その渦流信号処理アンプ４からの出力信号は、Ａ／Ｄ変換器５を介して、演算処理部６に入力される。 A plurality of E-type eddy current sensors 1 are arranged at a predetermined pitch in a direction to be measured (for example, a plate width direction). Each sensor is connected to the eddy current signal processing amplifier 4, and an output signal from the eddy current signal processing amplifier 4 is input to the arithmetic processing unit 6 via the A / D converter 5.
演算処理部６へは、金属帯の移動をトラッキングするためのラインＰＬＧ７信号が入力され、所定の移動量ピッチ（例えば５ｍｍ）金属帯が進むごとに全チャンネルの渦流信号処理アンプ４出力信号を取り込む。続いて演算処理部６では、所定の処理長さ、例えば６４０ｍｍだけ金属帯が進んだところで、所定のフィルタ処理をソフト的に演算する。フィルタ処理は、欠陥周波数近傍の信号のみを取り出すことで、S/N向上させるためのものである。 A line PLG7 signal for tracking the movement of the metal band is input to the arithmetic processing unit 6, and the output signal of the eddy current signal processing amplifier 4 of all channels is fetched every time the metal band advances by a predetermined movement amount pitch (for example, 5 mm). . Subsequently, the arithmetic processing unit 6 calculates a predetermined filter process in a software manner when the metal band advances by a predetermined processing length, for example, 640 mm. The filter process is for improving the S / N by extracting only the signal near the defect frequency.
図５は、金属帯として鋼帯を例に、その渦流探傷の様子を模式的に示した図である。前記Ｅ型渦流センサ１を、ロール上を走行する鋼帯２の幅方向に渡って所定のピッチにて複数個、かつ鋼帯２の上方所定の距離をおいて配列している。また、表裏面に前記Ｅ型渦流センサ１を配列すれば、鋼帯のばたつき影響も無く、鋼帯の全幅全長における欠陥の検出が可能となる。 FIG. 5 is a diagram schematically showing the state of eddy current flaw detection using a steel strip as an example of a metal strip. A plurality of the E-type eddy current sensors 1 are arranged at a predetermined pitch over the width direction of the steel strip 2 traveling on the roll, and arranged at a predetermined distance above the steel strip 2. Further, if the E-type eddy current sensors 1 are arranged on the front and back surfaces, it is possible to detect defects in the entire length of the steel strip without the influence of flapping of the steel strip.
図２は、本発明に係る演算処理の一例を説明するフローチャートである。ここでの処理は、図１の演算処理部６で行われるものであり、図２に基づいて、演算処理内容を詳説してゆく。 FIG. 2 is a flowchart for explaining an example of the arithmetic processing according to the present invention. The processing here is performed by the arithmetic processing unit 6 of FIG. 1, and the details of the arithmetic processing will be described based on FIG.
まず、Step01にて、(1)あらかじめ検出したいヘゲ欠陥レベルに合わせて設定する、欠陥判定しきい値Ａ、(2)欠陥判定しきい値よりも小さく、通常の地合レベルより高いレベルで、材料ノイズ輪郭を抽出するために設定する、材料ノイズ判定しきい値Ｂ、(3)欠陥判定しきい値よりも大きいレベルで設定する、第２の欠陥判定しきい値Ｃ、の３つのしきい値(Ａ〜Ｃ)について設定しておく。材料ノイズ判定しきい値Ｂ＜欠陥判定しきい値Ａ＜第２の欠陥判定しきい値Ｃという関係に設定するようにする。また、(4)材料ノイズ判定チャンネル個数Ｄ（例えば、全５６ＣＨの内の１０ＣＨなど）とともに、(5)前後材料ノイズ判定長さＥ（この場合、１００ｍｍ）を設定しておく。 First, in Step 01, (1) Defect judgment threshold A set in advance according to the level of defect to be detected, (2) The defect judgment threshold A is smaller than the normal judgment level and higher than the normal ground level. The material noise determination threshold B is set for extracting the material noise contour, and the second defect determination threshold C is set at a level larger than the defect determination threshold. The threshold values (A to C) are set. The relationship of material noise determination threshold B <defect determination threshold A <second defect determination threshold C is set. Further, (4) the material noise determination length E (100 mm in this case) is set in advance together with (4) the material noise determination channel number D (for example, 10 channels out of all 56 channels).
次に、Step02にて、区間データサンプリングを行う。例えば、５ｍｍ金属帯が進むごとに全チャンネルの出力信号を取り込む作業を、１２８回行えば、６４０ｍｍだけ金属帯が進んだ区間全体のデータサンプリングが行える。 Next, in step 02, section data sampling is performed. For example, if the operation of taking the output signals of all channels every time the 5 mm metal band advances is performed 128 times, data sampling of the entire section where the metal band has advanced by 640 mm can be performed.
Step02の区間データサンプリングが終わった段階で、３つのしきい値(欠陥判定しきいＡ、材料ノイズ判定しきい値Ｂ、および第２の欠陥判定しきい値Ｃ)を用いた２値化処理の工程(Step03〜Step05)に、並列的に進む。 At the stage when the section data sampling of Step02 is completed, binarization processing using three threshold values (defect determination threshold A, material noise determination threshold B, and second defect determination threshold C) is performed. The process proceeds in parallel to the steps (Step 03 to Step 05).
Step03では、先の区間データについて欠陥判定しきい値Ａとの比較を行い、２値化処理を行う。例えば、欠陥判定しきい値Ａより大きいデータ部分を黒くし、小さいデータ部分を白くする処理を行う。ここの処理は、これまでヘゲ欠陥の検出で行われてきたものである。 In Step 03, the previous section data is compared with the defect determination threshold A, and binarization processing is performed. For example, a process is performed in which a data portion larger than the defect determination threshold A is blackened and a small data portion is whitened. The processing here has been performed by detecting a hege defect until now.
Step04では、Step03と同様に２値化処理を行うが、Step03との相異は、比較に用いるしきい値が、Step03で用いた欠陥判定しきい値Ａより小さい材料ノイズ判定しきい値Ｂを用いる点にある。これにより、欠陥判定しきい値よりも低いレベルで設定された材料ノイズしきい値に対する判定マップが得られる。そして、この処理に続くStep06にて、区間内の長手位置毎のしきい値超えCH数をカウントし、Step07の材料ノイズ判定区間演算にて、材料ノイズ判定区間が特定される。すなわち、Step07では、Step01で設定した、材料ノイズ判定チャンネル個数Ｄおよび前後材料ノイズ判定長さＥを用いて、材料ノイズ判定区間を演算する。これにより、信号レベルがヘゲ信号に近接していても、材料ノイズのヘゲ欠陥への誤検出防止が可能となる。また、前後材料ノイズ判定長さＥを設定するのは、材料ノイズはきっちり長手方向同一位置にて幅方向に存在するものでなく、材料ノイズが発生する境目では少数のチャンネルしか反応せず、前記材料ノイズ判定チャンネル個数に達せず、ヘゲ欠陥へ誤判定されたままになることを防止するためである。 In Step 04, binarization processing is performed in the same manner as in Step 03. However, the difference from Step 03 is that the threshold used for comparison is a material noise determination threshold B smaller than the defect determination threshold A used in Step 03. There is in point to use. As a result, a determination map for the material noise threshold set at a level lower than the defect determination threshold is obtained. In Step 06 following this process, the number of CHs exceeding the threshold value for each longitudinal position in the section is counted, and the material noise determination section is specified by the material noise determination section calculation in Step 07. That is, in Step 07, the material noise determination section is calculated using the material noise determination channel number D and the front and rear material noise determination length E set in Step 01. As a result, even if the signal level is close to the beard signal, it is possible to prevent erroneous detection of the material noise on the beard defect. The front and rear material noise judgment length E is set because the material noise does not exist in the width direction exactly at the same position in the longitudinal direction, and only a small number of channels react at the boundary where the material noise occurs. This is to prevent the number of material noise determination channels from being reached and erroneously determined to be a hege defect.
ここまでの処理の様子を、図３の具体例を用いて説明する。図３は、鋼帯より２０ｍｍ上方に、板幅方向に３４ｍｍピッチにて配列した５６ＣＨのＥ型渦流センサからの信号処理の過程の一部を示したものであり、５ｍｍピッチで１２８回データを取り込んだ、６４０ｍｍをその判定区間としているものである。 The process so far will be described with reference to a specific example of FIG. FIG. 3 shows a part of the signal processing process from the 56CH E-type eddy current sensor arranged at a pitch of 34 mm in the plate width direction 20 mm above the steel strip. Data is obtained 128 times at a pitch of 5 mm. The taken-in 640 mm is used as the determination section.
先ず、図３（Ａ）は、Step03で溶接部近傍材料ノイズが、欠陥判定しきい値Ａ超えにより、２値化され（中央部、右側の黒点）て、欠陥として誤判定された状態を示している。 First, FIG. 3A shows a state in which the material noise in the vicinity of the welded portion is binarized (in the middle portion, the black dot on the right side) and mistakenly determined as a defect in Step 03 due to exceeding the defect determination threshold A. ing.
さらに、図３（Ｂ）は、欠陥判定しきい値Ａよりも低いレベルで設定された材料ノイズしきい値Ｂに対する判定マップ(Step04)であり、材料ノイズの輪郭部が抽出される。同図にて、前記材料ノイズしきい値Ｂを超えたチャンネル数を長手位置毎にカウントする(Step06)。そして、設定した材料ノイズ判定チャンネル個数Ｄの１０ＣＨに対し、図中の長手位置ａ〜ｄ(それぞれ１１、１３、１１、および１３ＣＨ)の位置でこれを超えることになり、各長手位置ａ〜ｄに対し、その前後１００ｍｍの区間を材料ノイズ判定区間とする(Step07)。そして、最終的に図３（Ｃ）に示すように、図３（Ａ）で表示された誤判定による欠陥判定部がマップ上より、リジェクト(Step09)される。 Further, FIG. 3B is a determination map (Step 04) for the material noise threshold B set at a level lower than the defect determination threshold A, and a contour portion of the material noise is extracted. In the figure, the number of channels exceeding the material noise threshold B is counted for each longitudinal position (Step 06). Then, with respect to 10 CH of the set material noise determination channel number D, the longitudinal positions a to d (11, 13, 11, and 13 CH, respectively) in the figure are exceeded, and the respective longitudinal positions a to d are exceeded. On the other hand, a section of 100 mm before and after that is set as a material noise determination section (Step 07). Finally, as shown in FIG. 3 (C), the defect determination unit by erroneous determination displayed in FIG. 3 (A) is rejected from the map (Step 09).
なお、図２の処理フローでは、Step05として第２の欠陥判定しきい値Ｃと比較して、これを超えるような極大信号が存在した場合には、当該長手位置については、前記材料ノイズ判定による欠陥判定部のリジェクト処理をしない処理(Step08)を行っている。これは、幅方向に大きいヘゲ欠陥を見逃すことを防止するためのものであり、幅方向に巨大なヘゲ欠陥は、その信号強度が極めて大きく、しきい値比較のみにより材料ノイズとの分離が容易である。 In the processing flow of FIG. 2, when there is a local maximum signal exceeding Step 2 as compared with the second defect determination threshold C, the longitudinal position is determined by the material noise determination. A process (Step 08) that does not perform the reject process of the defect determination unit is performed. This is to prevent missing large hege defects in the width direction. The signal intensity of a huge hege defect in the width direction is extremely high, and it is separated from material noise only by threshold comparison. Is easy.
Step09までで一連の区間データについての演算処理は終了するが、更に他の区間データにより処理を継続する場合は、Step02の区間データサンプリングに戻り処理を継続する(Step10)。なお、Ａ〜Ｅのしきい値等を変更し、異なった判定基準で判定する場合は、改めてStep01の設定を行う。 The calculation process for a series of section data is completed up to Step 09. However, if the process is to be continued with other section data, the process returns to the section data sampling in Step 02 and continues (Step 10). If the threshold values A to E are changed and the determination is made based on different criteria, Step 01 is set again.
以上説明した処理によって、溶接部前後等の材料ノイズによる欠陥への誤判定の防止および幅方向に大きいヘゲ欠陥の見逃し防止が可能となり、信頼性の高い渦流探傷が実現できる。 By the processing described above, it is possible to prevent erroneous determination of defects due to material noise before and after the welded portion and to prevent oversight of large bald defects in the width direction, and to realize highly reliable eddy current flaw detection.
１ センサ
１ａ １次コイル
１ｂ、１ｃ ２次コイル
２ 金属帯(鋼帯)
３ 欠陥
４ 渦流信号処理アンプ
５ Ａ／Ｄ変換器
６ 演算処理部
７ ラインＰＬＧ
1 Sensor 1a Primary coil 1b, 1c Secondary coil 2 Metal strip (steel strip)
3 Defect 4 Eddy Current Signal Processing Amplifier 5 A / D Converter 6 Arithmetic Processing Unit 7 Line PLG
Claims (4)
前記演算処理工程は、
（イ）前記フィルタ処理後のそれぞれの出力と、
前記欠陥判定しきい値よりも低いレベルに設定された、材料ノイズ判定しきい値との比較を行い、該材料ノイズ判定しきい値を超えた出力のチャンネル数を幅方向にカウントし、そのカウント数があらかじめ設定された材料ノイズ判定チャンネル数以上であれば、材料ノイズと判定し、この材料ノイズ判定部位を前記欠陥判定部位から除き、
（ロ）前記フィルタ処理後のそれぞれの出力と、
前記欠陥判定しきい値よりも、高いレベルに設定された第２の欠陥判定しきい値との比較を行い、該第２の欠陥判定しきい値を超えた出力が出た場合は、該出力のチャンネルにおける前記（イ）の処理を行わないことを特徴とする金属帯の渦流探傷方法。 A plurality of eddy current sensors are arranged in the width direction of the running metal band, the output of each sensor is filtered, and the defect judgment site is detected by comparing each filter output with the defect judgment threshold. In an eddy current flaw detection method for a metal strip having an arithmetic processing step to
The arithmetic processing step includes
(A) Each output after the filtering process;
Comparison is made with a material noise judgment threshold value set to a level lower than the defect judgment threshold value, and the number of output channels exceeding the material noise judgment threshold value is counted in the width direction. If the number is equal to or greater than the preset number of material noise determination channels, it is determined as material noise, this material noise determination part is excluded from the defect determination part,
(B) each output after the filtering process;
A comparison is made with a second defect determination threshold value set to a level higher than the defect determination threshold value, and if an output exceeding the second defect determination threshold value is output, the output The metal strip eddy current flaw detection method is characterized in that the process (a) is not performed in any of the channels.
前記演算処理工程は、
（イ）金属帯の一定移動量ピッチ毎に、前記センサそれぞれの出力をＡ／Ｄ変換およびフィルタ処理した後、金属帯の所定長さ分だけ区間データとして収集する区間データサンプリング工程と、
（ロ）前記区間データと、あらかじめ設定された欠陥判定しきい値との比較により、欠陥判定部位を検出する欠陥判定部検出工程と、
（ハ）前記区間データと、前記欠陥判定しきい値よりも低いレベルに設定された、材料ノイズ判定しきい値との比較を行い、該材料ノイズ判定しきい値を超えたデータのチャンネル数を幅方向にカウントし、そのカウント数があらかじめ設定された材料ノイズ判定チャンネル数以上であれば、材料ノイズと判定し、
当該長手位置を起点とした、前記所定長さ内の、所定の前後材料ノイズ判定長さ内の全チャンネル部位を前記欠陥判定部位から除く欠陥判定部リジェクト工程と、
（ニ）前記区間データと、
前記欠陥判定しきい値よりも、高いレベルに設定された第２の欠陥判定しきい値との比較を行い、該第２の欠陥判定しきい値を超えたデータが出た場合は、当該長手位置における前記欠陥判定部リジェクト工程の処理を行わない判定区間再演算工程と、
を有することを特徴とする金属帯の渦流探傷方法。 A plurality of eddy current sensors are arranged in the width direction of the running metal band, the output of each sensor is filtered, and the defect judgment site is detected by comparing each filter output with the defect judgment threshold. In an eddy current flaw detection method for a metal strip having an arithmetic processing step to
The arithmetic processing step includes
(A) A section data sampling step of collecting the output of each of the sensors as a section data for a predetermined length of the metal band after A / D conversion and filtering for each constant movement amount pitch of the metal band;
(B) a defect determination unit detecting step for detecting a defect determination site by comparing the section data with a preset defect determination threshold;
(C) The section data is compared with a material noise judgment threshold value set to a level lower than the defect judgment threshold value, and the number of channels of data exceeding the material noise judgment threshold value is determined. Count in the width direction, and if the count is equal to or greater than the preset number of material noise determination channels, it is determined as material noise,
The defect determination unit rejecting step of removing all channel parts within the predetermined length within the predetermined length, starting from the longitudinal position, from the defect determination part,
(D) the interval data;
A comparison is made with the second defect determination threshold value set to a level higher than the defect determination threshold value, and when data exceeding the second defect determination threshold value is output, A determination interval recalculation step that does not perform the processing of the defect determination unit rejection step at the position;
A metal strip eddy current flaw detection method characterized by comprising:
前記演算処理部は、
（イ）前記フィルタ処理後のそれぞれの出力と、
前記欠陥判定しきい値よりも低いレベルに設定された、材料ノイズ判定しきい値との比較を行い、該材料ノイズ判定しきい値を超えた出力のチャンネル数を幅方向にカウントし、そのカウント数があらかじめ設定された材料ノイズ判定チャンネル数以上であれば、材料ノイズと判定し、この材料ノイズ判定部位を前記欠陥判定部位から除く欠陥判定部リジェクト手段と、
（ロ）前記フィルタ処理後のそれぞれの出力と、
前記欠陥判定しきい値よりも、高いレベルに設定された第２の欠陥判定しきい値との比較を行い、該第２の欠陥判定しきい値を超えた出力が出た場合は、該出力のチャンネルにおける前記（イ）の処理を行わない判定区間再演算手段とを備えることを特徴とする金属帯の渦流探傷装置。 A plurality of eddy current sensors arranged in the width direction of the traveling metal strip, the output of each sensor is filtered, and the defect judgment site is detected by comparing each filter output with the defect judgment threshold. In an eddy current flaw detector for a metal strip having an arithmetic processing unit to
The arithmetic processing unit
(A) Each output after the filtering process;
Comparison is made with a material noise judgment threshold value set to a level lower than the defect judgment threshold value, and the number of output channels exceeding the material noise judgment threshold value is counted in the width direction. If the number is equal to or more than the preset number of material noise determination channels, it is determined as material noise, and a defect determination unit rejecting unit that removes this material noise determination part from the defect determination part,
(B) each output after the filtering process;
A comparison is made with a second defect determination threshold value set to a level higher than the defect determination threshold value, and if an output exceeding the second defect determination threshold value is output, the output A metal strip eddy current flaw detector comprising: a determination interval recalculation unit that does not perform the process of (a) in the channel.
前記演算処理部は、
（イ）金属帯の一定移動量ピッチ毎に、前記センサそれぞれの出力をＡ／Ｄ変換およびフィルタ処理した後、金属帯の所定長さ分だけ区間データとして収集する区間データサンプリング手段と、
（ロ）前記区間データと、あらかじめ設定された欠陥判定しきい値との比較により、欠陥判定部位を検出する欠陥判定部検出手段と、
（ハ）前記区間データと、前記欠陥判定しきい値よりも低いレベルに設定された、材料ノイズ判定しきい値との比較を行い、該材料ノイズ判定しきい値を超えたデータのチャンネル数を幅方向にカウントし、そのカウント数があらかじめ設定された材料ノイズ判定チャンネル数以上であれば、材料ノイズと判定し、
当該長手位置を起点とした、前記所定長さ内の、所定の前後材料ノイズ判定長さ内の全チャンネル部位を前記欠陥判定部位から除く欠陥判定部リジェクト手段と、
（ニ）前記区間データと、
前記欠陥判定しきい値よりも、高いレベルに設定された第２の欠陥判定しきい値との比較を行い、該第２の欠陥判定しきい値を超えたデータが出た場合は、当該長手位置における前記欠陥判定部リジェクト手段の処理を行わない判定区間再演算手段と、
を備えることを特徴とする金属帯の渦流探傷装置。 A plurality of eddy current sensors arranged in the width direction of the traveling metal strip, the output of each sensor is filtered, and the defect judgment site is detected by comparing each filter output with the defect judgment threshold. In an eddy current flaw detector for a metal strip having an arithmetic processing unit to
The arithmetic processing unit
(A) Section data sampling means for collecting, as A / D conversion and filtering, the output of each of the sensors for each constant movement pitch of the metal band, and collecting as a section data for a predetermined length of the metal band;
(B) a defect determination unit detecting means for detecting a defect determination part by comparing the section data with a preset defect determination threshold;
(C) The section data is compared with a material noise judgment threshold value set to a level lower than the defect judgment threshold value, and the number of channels of data exceeding the material noise judgment threshold value is determined. Count in the width direction, and if the count is equal to or greater than the preset number of material noise determination channels, it is determined as material noise,
Defect determination unit rejecting means for excluding from the defect determination part all channel parts within the predetermined length and the predetermined front and rear material noise determination length, starting from the longitudinal position,
(D) the interval data;
A comparison is made with the second defect determination threshold value set to a level higher than the defect determination threshold value, and when data exceeding the second defect determination threshold value is output, A determination interval recalculation unit that does not perform the processing of the defect determination unit rejection unit at the position;
A metal strip eddy current flaw detector characterized by comprising:
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| JP4701210B2 (en) | 2007-06-15 | 2011-06-15 | インターナショナル・ビジネス・マシーンズ・コーポレーション | Storage device for detecting defects in recording medium, defect detection method, and program |
| JP4902448B2 (en) * | 2007-07-10 | 2012-03-21 | 株式会社日立製作所 | Defect identification method and defect identification apparatus |
| JP5625919B2 (en) * | 2011-01-05 | 2014-11-19 | Ｊｆｅスチール株式会社 | Surface defect detector |
| JP5605293B2 (en) * | 2011-04-13 | 2014-10-15 | 新日鐵住金株式会社 | How to determine when to change the measuring roll |
| JP5949342B2 (en) * | 2012-03-16 | 2016-07-06 | Ｊｆｅスチール株式会社 | Role management apparatus and role management method |
| CN103591882B (en) * | 2013-11-07 | 2016-03-30 | 国核电站运行服务技术有限公司 | The flexible positioning and clamping mechanism of eddy current probe |
| KR20210014482A (en) * | 2019-07-30 | 2021-02-09 | 주식회사 엘지화학 | Method for testing resistance welding part of battery using eddy current signal |
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| JP2003236613A (en) * | 2002-02-15 | 2003-08-26 | Jfe Steel Kk | Method for manufacturing band steel for manufacturing cold-rolled or plated band steel and method for manufacturing plated band steel |
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