JP2006220488A

JP2006220488A - Ultrasonic flaw detecting method and ultrasonic flaw detector

Info

Publication number: JP2006220488A
Application number: JP2005033166A
Authority: JP
Inventors: Hirohisa Yamada; 裕久山田
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2005-02-09
Filing date: 2005-02-09
Publication date: 2006-08-24
Anticipated expiration: 2025-02-09
Also published as: JP4505344B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detecting method efficiently performing the flaw detection of the whole surface of a strip like inspection target, while suppressing steep rise in equipment cost, when a flaw is detected with respect to the whole surface of the strip like inspection target by a transmission method, and also to provide an ultrasonic flaw detector. <P>SOLUTION: In the ultrasonic flaw detecting method for detecting the flaw in the inspection target, by using a flaw detection unit 1 for receiving the ultrasonic wave transmitted through the inspection target, at least two flaw detection units 1 are arranged, and the ultrasonic wave 8a, emitted from one flaw detection unit 1a, is received by the same flaw detection unit 1a, while the ultrasonic wave 8x emitted from one flaw detection unit 1a is also received by the separate adjacent flaw detection unit 1b. Effective flaw detection width 23x is added to effective flaw detection widths 23a and 23b, when the flaw detection units 1a and 1b are respectively used independently, and even if a flaw detection unit arranging interval 25 is wider than the effective flaw detection width 23, flaw detection free of inspection failure is made. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、被検査体を透過する超音波を利用して被検査体内部に存在する欠陥を検出するための超音波探傷方法及び超音波探傷装置に関するものである。 The present invention relates to an ultrasonic flaw detection method and an ultrasonic flaw detection apparatus for detecting a defect existing inside a test object using an ultrasonic wave transmitted through the test object.

超音波を利用して被検査体内部に存在する欠陥を検出するための超音波探傷方法には、反射法、透過法、共振法などがある。 Examples of ultrasonic flaw detection methods for detecting defects existing inside the object to be inspected using ultrasonic waves include a reflection method, a transmission method, and a resonance method.

透過法では、図７（ａ）に示すように、被検査体６の一方の側に配置した送信探触子３から発射した超音波が経路を通って被検査体６を透過し、被検査体６の他方の側に配置した受信探触子４に受信する。図８には、被検査体６の内部に欠陥７が存在する場合において、欠陥７付近において超音波エコー強度がどのように変化するのかを模式的に示している。被検査体６内部の超音波の進路に欠陥７が存在すると、透過する超音波が欠陥７によって減衰するので、図８に示すように欠陥７の位置において超音波エコーの減衰が大きくなる。このように、透過法によると超音波の減衰を利用して被検査体内部に存在する欠陥を検出することができる。ここでは、１組の送信探触子と受信探触子の組み合わせを探傷ユニットと呼ぶ。 In the transmission method, as shown in FIG. 7A, ultrasonic waves emitted from the transmission probe 3 arranged on one side of the inspection object 6 pass through the inspection object 6 through a path, and are inspected. The signal is received by the receiving probe 4 arranged on the other side of the body 6. FIG. 8 schematically shows how the ultrasonic echo intensity changes in the vicinity of the defect 7 when the defect 7 exists inside the inspection object 6. If there is a defect 7 in the path of the ultrasonic wave inside the inspection object 6, the transmitted ultrasonic wave is attenuated by the defect 7, so that the attenuation of the ultrasonic echo is increased at the position of the defect 7 as shown in FIG. As described above, according to the transmission method, it is possible to detect a defect existing inside the inspection object by using the attenuation of the ultrasonic wave. Here, a combination of one set of transmission probe and reception probe is called a flaw detection unit.

また、特許文献１、特許文献２には、図７（ｃ）に示すように、透過法を用いた超音波探傷方法として、被検査体６の一方の側に配置した探触子２から発射した超音波が被検査体６を透過し、被検査体の他方の側に配置した反射板５で反射し、被検査体６を再度透過して探触子２に到達する超音波エコー強度から被検査体中の欠陥検出を行う超音波探傷方法が記載されている。この方法においては、探傷ユニットは超音波送信と受信を兼ねるひとつの探触子から構成される。 Further, in Patent Document 1 and Patent Document 2, as shown in FIG. 7C, as an ultrasonic flaw detection method using a transmission method, a laser beam is emitted from a probe 2 arranged on one side of an inspection object 6. The ultrasonic wave that has passed through the inspection object 6 is reflected from the reflection plate 5 disposed on the other side of the inspection object, is transmitted through the inspection object 6 again, and reaches the probe 2. An ultrasonic flaw detection method for detecting a defect in an inspection object is described. In this method, the flaw detection unit is composed of a single probe that serves as both ultrasonic transmission and reception.

透過法には連続波およびパルス波が使用可能であるが、最近はパルス波が多用されている。透過法では、探触子と被検査体間での超音波の安定な伝達が重要であり、被検査体表面が特に良好な場合を除いて、水浸法が用いられることが多い。 A continuous wave and a pulse wave can be used for the transmission method, but recently, a pulse wave is frequently used. In the transmission method, stable transmission of ultrasonic waves between the probe and the test object is important, and the water immersion method is often used unless the surface of the test object is particularly good.

透過法における１コの探傷ユニットによって欠陥を検出できる領域の広さ（以下「有効探傷幅２３」ともいう。）は、所定の狭い範囲に限定される。従って、有効探傷幅よりも広い幅を有する板状の被検査体について超音波探傷を行う際には、欠陥の検出もれを発生させずに幅方向全体の欠陥検出を行うため、種々の工夫がなされる。 The size of the area in which defects can be detected by one flaw detection unit in the transmission method (hereinafter also referred to as “effective flaw detection width 23”) is limited to a predetermined narrow range. Therefore, when performing an ultrasonic flaw detection on a plate-shaped inspection object having a width wider than the effective flaw detection width, various ingenuity is provided in order to detect a defect in the entire width direction without generating a defect detection defect. Is made.

特許文献２に記載の従来方法では、被検査体の幅方向に複数の探触子を一列に並べる。隣り合った探触子の間隔は、探触子の有効探傷幅よりも広いので、被検査体の長手方向に直線状に走査したのでは、欠陥の検出もれが発生することとなる。特許文献２においては、探触子の走査を正弦波軌跡となるように移動させ、正弦波の波長を欠陥の最小長さよりも短くし、検出もれの発生を防ぐ方法が記載されている。 In the conventional method described in Patent Document 2, a plurality of probes are arranged in a line in the width direction of the object to be inspected. Since the interval between adjacent probes is wider than the effective flaw detection width of the probe, if the scanning is performed linearly in the longitudinal direction of the object to be inspected, defect detection will be lost. Patent Document 2 describes a method of preventing the occurrence of detection leakage by moving the scanning of a probe so as to be a sine wave locus, thereby making the wavelength of the sine wave shorter than the minimum length of the defect.

特許文献３に記載されているように、従来の鋼板の自動超音波探傷においては、多数の探触子を、通板最大幅鋼板の中央部探傷領域の全範囲にわたって千鳥状に２列配置し、１回の通板で全面探傷をする方法が知られている。千鳥状に２列配置する理由は、探触子の外形寸法は有効探傷幅よりも幅が広いため、探触子を一列に配置したのでは探傷領域を連続させることができないからである。また、多数の探触子をその有効探傷幅の２倍のピッチで配置し、数回の通板で全面探傷をする方法が知られている。 As described in Patent Document 3, in conventional ultrasonic inspection of steel plates, a large number of probes are arranged in two rows in a staggered manner over the entire range of the flaw detection region at the center of the maximum width steel plate. There is known a method of performing a full flaw detection with one pass. The reason why the two rows are arranged in a staggered pattern is that the outer dimensions of the probes are wider than the effective flaw detection width, and therefore the flaw detection areas cannot be made continuous if the probes are arranged in one row. Further, a method is known in which a large number of probes are arranged at a pitch twice as large as the effective flaw detection width, and the whole flaw detection is performed with several passes.

特開平１−２５００５６号公報Japanese Patent Laid-Open No. 1-250056 特開昭６０−３３０４８号公報JP-A-60-33048 特開平２−１９４３５５号公報JP-A-2-194355

特許文献２に記載の方法では、探触子の走査速度を速くするほど正弦波運動の周期を短くすることが必要となり、機構部にがたつきを生じやすく、走査速度を十分に速くすることができないという欠点がある。 In the method described in Patent Document 2, it is necessary to shorten the cycle of the sinusoidal motion as the scanning speed of the probe is increased, and the mechanism portion is likely to be rattled and the scanning speed is sufficiently increased. There is a disadvantage that can not be.

また特許文献３に記載の方法のうち、探触子をその有効探傷幅に等しいピッチで千鳥状に２列配置する方法では、多数の探触子を用いることが必要となり、探傷装置の設置費用および維持費用が高額となる。また、探触子をその有効探傷幅の２倍のピッチで配置し、数回の通板で全面探傷をする方法では、１回の通板で全面探傷することができないので、検査能力を十分に上げることができない。 Of the methods described in Patent Document 3, the method in which the probes are arranged in two rows in a staggered manner at a pitch equal to the effective flaw detection width requires the use of a large number of probes, and the flaw detection device installation cost is increased. And maintenance costs are high. In addition, in the method in which the probes are arranged at a pitch twice the effective flaw detection width and the entire flaw detection is performed with several passes, the flaw detection cannot be performed with one pass, so that the inspection capability is sufficient. I ca n’t raise it.

本発明は、帯状の被検査体の全面について透過法で欠陥検出するに際し、設備費の高騰を抑制しつつ、能率良く全面探傷を行うことのできる超音波探傷方法及び超音波探傷装置を提供することを目的とする。 The present invention provides an ultrasonic flaw detection method and an ultrasonic flaw detection apparatus capable of efficiently performing full flaw detection while suppressing an increase in equipment costs when detecting defects on the entire surface of a strip-shaped object by the transmission method. For the purpose.

即ち、本発明の要旨とするところは以下のとおりである。
（１）超音波を送信し被検査体を透過してきた超音波を受信する探傷ユニット１を用いて被検査体中の欠陥検出を行う超音波探傷方法において、２以上の探傷ユニット１を配列し、一の探傷ユニット１ａから発射した超音波を同じ探傷ユニット１ａによって受信するとともに、一の探傷ユニット１ａから発射した超音波を隣接する別の探傷ユニット１ｂによっても受信することを特徴とする超音波探傷方法。
（２）各探傷ユニット１は超音波の送信と受信を行う探触子２であり、被検査体６の一方の側に配置した探触子２から超音波を送信及び受信し、被検査体６の反対側に配置した反射板５で超音波を反射することを特徴とする上記（１）に記載の超音波探傷方法。
（３）各探傷ユニット１は、被検査体６の一方の側に超音波を発射する送信探触子３を配置し、被検査体６の他方の側に超音波を受信する受信探触子４を配置してなることを特徴とする上記（１）に記載の超音波探傷方法。
（４）一の探傷ユニット１から発射した超音波を、同一の探傷ユニット１ａ及び隣接する別の探傷ユニット１ｂによって同時期に受信することを特徴とする上記（１）乃至（３）のいずれかに記載の超音波探傷方法。
（５）超音波を送信し被検査体を透過した後に受信する探傷ユニット１を用いて被検査体中の欠陥検出を行う超音波探傷装置であって、２以上の探傷ユニット１を配列し、一の探傷ユニット１ａから発射した超音波を同じ探傷ユニット１ａによって受信するとともに、一の探傷ユニット１ａから発射した超音波を隣接する別の探傷ユニット１ｂによっても受信することを特徴とする超音波探傷装置。
（６）各探傷ユニット１は超音波の送信と受信を行う探触子２であり、被検査体６の一方の側に探傷ユニット１を配置し、被検査体６の反対側に反射板５を配置し、探触子２から超音波を送信及び受信し、反射板５で超音波を反射することを特徴とする上記（５）に記載の超音波探傷装置。
（７）各探傷ユニット１は、被検査体６の一方の側に配置し超音波を発射する送信探触子３と、被検査体６の他方の側に配置し超音波を受信する受信探触子４とからなることを特徴とする上記（５）に記載の超音波探傷装置。
（８）一の探傷ユニット１ａから発射した超音波を、同一の探傷ユニット１ａ及び隣接する別の探傷ユニット１ｂによって同時期に受信することを特徴とする上記（５）乃至（７）のいずれかに記載の超音波探傷装置。 That is, the gist of the present invention is as follows.
(1) In an ultrasonic flaw detection method for detecting defects in a test object using a flaw detection unit 1 that transmits an ultrasonic wave and receives an ultrasonic wave transmitted through the test object, two or more flaw detection units 1 are arranged. The ultrasonic waves emitted from one flaw detection unit 1a are received by the same flaw detection unit 1a, and the ultrasonic waves emitted from one flaw detection unit 1a are also received by another flaw detection unit 1b. Flaw detection method.
(2) Each flaw detection unit 1 is a probe 2 that transmits and receives ultrasonic waves, and transmits and receives ultrasonic waves from the probe 2 arranged on one side of the object to be inspected 6. The ultrasonic flaw detection method as described in (1) above, wherein the ultrasonic wave is reflected by the reflecting plate 5 arranged on the opposite side of 6.
(3) Each flaw detection unit 1 has a transmission probe 3 that emits ultrasonic waves on one side of the inspection object 6 and a reception probe that receives ultrasonic waves on the other side of the inspection object 6. The ultrasonic flaw detection method according to (1) above, wherein 4 is arranged.
(4) Any of the above (1) to (3), wherein the ultrasonic waves emitted from one flaw detection unit 1 are received simultaneously by the same flaw detection unit 1a and another flaw detection unit 1b adjacent thereto. The ultrasonic flaw detection method as described in 4.
(5) An ultrasonic flaw detector that detects a defect in an inspection object using the flaw detection unit 1 that transmits ultrasonic waves and receives the light after passing through the inspection object, and two or more flaw detection units 1 are arranged, Ultrasonic flaw detection characterized in that an ultrasonic wave emitted from one flaw detection unit 1a is received by the same flaw detection unit 1a and an ultrasonic wave emitted from one flaw detection unit 1a is also received by another flaw detection unit 1b. apparatus.
(6) Each flaw detection unit 1 is a probe 2 that transmits and receives ultrasonic waves. The flaw detection unit 1 is arranged on one side of the inspection object 6, and the reflection plate 5 is opposite to the inspection object 6. The ultrasonic flaw detector according to (5) above, wherein ultrasonic waves are transmitted and received from the probe 2 and reflected by the reflector 5.
(7) Each flaw detection unit 1 is arranged on one side of the inspection object 6 and the transmission probe 3 that emits ultrasonic waves, and the reception probe that is arranged on the other side of the inspection object 6 and receives ultrasonic waves. The ultrasonic flaw detector as set forth in (5) above, characterized in that it comprises a tactile element 4.
(8) Any of the above (5) to (7), wherein ultrasonic waves emitted from one flaw detection unit 1a are received at the same time by the same flaw detection unit 1a and another flaw detection unit 1b adjacent thereto. The ultrasonic flaw detector described in 1.

本発明は、超音波を送信し被検査体を透過した後に受信する探傷ユニットを用いて被検査体中の欠陥検出を行う超音波探傷方法において、２以上の探傷ユニットを配列し、一の探傷ユニットから発射した超音波を同じ探傷ユニットによって受信するとともに、一の探傷ユニットから発射した超音波を隣接する別の探傷ユニットによっても受信することによって、探傷ユニットの数を増やすことなく、１回の走査で検出もれのない全面の探傷を可能とする。 The present invention relates to an ultrasonic flaw detection method for detecting a defect in a test object using a flaw detection unit that transmits an ultrasonic wave and receives it after passing through the test object. The ultrasonic waves emitted from the unit are received by the same flaw detection unit, and the ultrasonic waves emitted from one flaw detection unit are also received by another flaw detection unit adjacent to each other without increasing the number of flaw detection units. It enables flaw detection on the entire surface that is not detected by scanning.

透過法による超音波探傷装置の超音波経路に配置した被検査体内に欠陥が存在する場合、透過する超音波の強度が減衰するために欠陥の存在を検出することができる。超音波の経路は広がりを有しているため、欠陥が超音波経路の中心から外れた位置にあっても超音波の減衰は生じるが、その減衰の程度は、超音波経路中心から外れるほど少なくなる。 When there is a defect in the inspection object arranged in the ultrasonic path of the ultrasonic flaw detector by the transmission method, the presence of the defect can be detected because the intensity of the transmitted ultrasonic wave is attenuated. Since the ultrasonic path is broad, even if the defect is located at a position off the center of the ultrasonic path, the attenuation of the ultrasonic wave occurs, but the degree of attenuation is so small that it is off the center of the ultrasonic path. Become.

透過法による超音波探傷において、欠陥として検出できる減衰強度レベルが、検出閾値２２として定められる。減衰量が少ないレベルに検出閾値を定めると、欠陥ではない場合を検出と誤認する頻度が増え、逆に大きな減衰レベルに検出閾値を定めると、欠陥の検出が困難となるため、最適な検出閾値２２が定められる。 In the ultrasonic flaw detection by the transmission method, an attenuation intensity level that can be detected as a defect is determined as the detection threshold 22. If the detection threshold is set to a level with a small amount of attenuation, the frequency of misidentifying that it is not a defect increases. Conversely, if a detection threshold is set to a large attenuation level, it becomes difficult to detect a defect. 22 is defined.

欠陥の存在位置が超音波経路中心から外れた位置に存在する場合、欠陥による超音波の減衰の程度が少なくなるため、減衰量が検出閾値を超えることができず、欠陥検出ができなくなる。所定の大きさを有する人工欠陥の検出を行ったとき、検出閾値２２を超える減衰が得られる範囲を、ここでは有効探傷幅２３と称する。 When a defect exists at a position deviating from the center of the ultrasonic path, the degree of attenuation of the ultrasonic wave due to the defect is reduced, so that the attenuation amount cannot exceed the detection threshold, and the defect cannot be detected. A range in which attenuation exceeding the detection threshold 22 is obtained when an artificial defect having a predetermined size is detected is referred to herein as an effective flaw detection width 23.

超音波送受信を兼ねる探触子２からなる探傷ユニット１を用い、人工欠陥を検出する際における人工欠陥の位置と超音波透過エコー強度２１との関係を調査した結果を図２に示す。 FIG. 2 shows the result of investigating the relationship between the position of the artificial defect and the ultrasonic transmission echo intensity 21 when detecting the artificial defect using the flaw detection unit 1 including the probe 2 that also serves as an ultrasonic transmission / reception.

図２（ａ）に示すように、探傷ユニット１の探触子２として、周波数２０ＭＨｚ、振動子幅８ｍｍ、焦点距離２００ｍｍのラインフォーカス型探触子を用い、被検査体６を挟んで探触子２の反対側に反射板５を設け、探触子２から送信した超音波は被検査体６を透過して反射板５で反射し、再度被検査体６を透過した後に探触子２に戻って受信される。被検査体６として板厚３．２ｍｍで内部に幅５ｍｍの人工欠陥を有する鋼板を用いた。検出閾値２２は−１０ｄＢである。 As shown in FIG. 2A, a line focus type probe having a frequency of 20 MHz, a transducer width of 8 mm, and a focal length of 200 mm is used as the probe 2 of the flaw detection unit 1, and the probe is sandwiched between the inspected object 6. A reflection plate 5 is provided on the opposite side of the probe 2, and the ultrasonic wave transmitted from the probe 2 is transmitted through the inspection object 6, reflected by the reflection plate 5, and again transmitted through the inspection object 6, and then the probe 2. Received back to. A steel plate having an artificial defect with a plate thickness of 3.2 mm and a width of 5 mm inside was used as the object to be inspected 6. The detection threshold 22 is −10 dB.

人工欠陥の位置（超音波経路中心からの距離）を横軸に、透過エコー強度２１を縦軸にとってグラフ化したのが図２（ｂ）である。欠陥が超音波経路中心に位置しているとき（ｘ＝０）は透過エコー強度の減衰量は−２０ｄＢを超えているが、欠陥位置が超音波経路中心から外れるほど減衰量は減少し、欠陥位置が超音波経路中心から約２．５ｍｍ離れたところ（ｘ＝±２．５ｍｍ）で検出閾値２２を満たさなくなる。即ち、この場合、有効探傷幅２３は２．５ｍｍの２倍で約５ｍｍであるということがわかる。 FIG. 2B is a graph showing the position of the artificial defect (distance from the center of the ultrasonic path) on the horizontal axis and the transmitted echo intensity 21 on the vertical axis. When the defect is located at the center of the ultrasonic path (x = 0), the attenuation amount of the transmitted echo intensity exceeds −20 dB, but the attenuation amount decreases as the defect position deviates from the center of the ultrasonic path. When the position is about 2.5 mm away from the center of the ultrasonic path (x = ± 2.5 mm), the detection threshold 22 is not satisfied. That is, in this case, it can be seen that the effective flaw detection width 23 is about 5 mm, which is twice 2.5 mm.

鋼板等の幅広い被検査体６について、その全面の欠陥有無を探傷しようとする際、被検査体の幅方向全長に探傷ユニット１を並べ、鋼板を長手方向に走行させてその全面を探傷することができる。この際、１回の直線的走行で全面の探傷を終えるためには、被検査体の幅方向には、探傷ユニット１をその有効探傷幅以下の間隔で並べることが必要となる。 When flaw detection is performed on the entire surface of a wide range of inspection objects 6 such as steel plates, the flaw detection units 1 are arranged along the entire length in the width direction of the inspection objects, and the entire surface is detected by running the steel plate in the longitudinal direction. Can do. At this time, in order to complete the flaw detection on the entire surface in one linear run, it is necessary to arrange the flaw detection units 1 at intervals equal to or less than the effective flaw detection width in the width direction of the inspection object.

透過法の探傷ユニット１を狭い間隔で並べようとした場合、探傷ユニット１の外形によって最小間隔が定まる。そして最小の探傷ユニット配置間隔２５は、その探傷ユニット１の有効探傷幅２３よりも大きい。図３（ａ）に示すように、探傷ユニット１を可能な限り狭い間隔で一列に並べて探触を行うと、図３（ｂ）に示すように隣接する探傷ユニットの各有効探傷幅２３は重ならず、欠陥を検出することのできない不感帯２４が生じることになる。そのため、探傷ユニット１を有効探傷幅以下の間隔で並べようとすると、特許文献３に記載のように、探傷ユニットを２列にして千鳥に並べることが必須となる。 When the flaw detection units 1 of the transmission method are arranged at a narrow interval, the minimum interval is determined by the outer shape of the flaw detection unit 1. The minimum flaw detection unit arrangement interval 25 is larger than the effective flaw detection width 23 of the flaw detection unit 1. As shown in FIG. 3 (a), when the flaw detection units 1 are arranged in a line at as narrow intervals as possible, the effective flaw detection widths 23 of adjacent flaw detection units are overlapped as shown in FIG. 3 (b). In other words, a dead zone 24 in which a defect cannot be detected is generated. Therefore, if the flaw detection units 1 are arranged at intervals equal to or smaller than the effective flaw detection width, it is essential to arrange the flaw detection units in two rows as described in Patent Document 3.

このように多数の探傷ユニット１を配列することとすると、例えば有効探傷幅が５ｍｍの探傷ユニットを並べ、最大幅２０００ｍｍの鋼板の探傷を行おうとすると、探傷ユニット１を４００個配列することが必要となり、設備費用及び維持費用は膨大なものとなる。 If a large number of flaw detection units 1 are arranged in this way, for example, if flaw detection units having an effective flaw detection width of 5 mm are arranged and a steel plate having a maximum width of 2000 mm is to be flawed, it is necessary to arrange 400 flaw detection units 1. Thus, the equipment cost and the maintenance cost become enormous.

ところで、探触子２から送信された超音波は、ある程度の広がり角度をもって伝搬する。非集束型の探触子を用いた場合、超音波の広がり角度は１．３度程度となる。探触子２の対向面に反射板５を置き、反射板５で反射した超音波は、送信された超音波の広がりに応じて広い範囲に返ってくる。ところが、送信したのと同じ探触子２で受信するため、受信できる超音波の範囲は探触子２の受信幅に制限され、欠陥を検出できる範囲も上記のとおりの有効探傷幅範囲内に制限されている。 By the way, the ultrasonic wave transmitted from the probe 2 propagates with a certain spread angle. When a non-focusing type probe is used, the spread angle of the ultrasonic wave is about 1.3 degrees. The reflecting plate 5 is placed on the opposite surface of the probe 2, and the ultrasonic waves reflected by the reflecting plate 5 return to a wide range according to the spread of the transmitted ultrasonic waves. However, since it is received by the same probe 2 that has transmitted, the range of ultrasonic waves that can be received is limited by the reception width of the probe 2, and the range in which defects can be detected is also within the effective flaw detection range as described above. Limited.

そこで本発明においては、配列して並べられた２以上の探傷ユニット１を複合的に使用することとした。即ち、図１に示すように、一の探傷ユニット１ａから発射した超音波８ａを同じ探傷ユニット１ａによって受信するとともに、一の探傷ユニット１ａから発射した超音波８ｘを隣接する別の探傷ユニット１ｂによっても受信することとした。一の探触子１ａから発射した超音波は、上記のようにある程度の広がり角度をもって伝搬するので、隣接する別の探触子１ｂに到達する成分が存在する。隣接する別の探触子１ｂに到達した超音波８ｘを検出することとすれば、その超音波経路に欠陥が存在した場合には、透過エコー強度の減衰として欠陥の存在を検出することが可能となるのである。 Therefore, in the present invention, two or more flaw detection units 1 arranged and arranged are used in combination. That is, as shown in FIG. 1, the ultrasonic wave 8a emitted from one flaw detection unit 1a is received by the same flaw detection unit 1a, and the ultrasonic wave 8x emitted from one flaw detection unit 1a is received by another flaw detection unit 1b. Also decided to receive. Since the ultrasonic wave emitted from one probe 1a propagates with a certain spread angle as described above, there is a component that reaches another adjacent probe 1b. If the ultrasonic wave 8x that has reached another adjacent probe 1b is detected, if a defect exists in the ultrasonic path, the presence of the defect can be detected as attenuation of transmitted echo intensity. It becomes.

前記図２の場合と同様に周波数２０ＭＨｚ、振動子幅８ｍｍ、焦点距離２００ｍｍのラインフォーカス型探触子を有する探傷ユニット１を用い、図１（ａ）に示すように、２個の探傷ユニット１を８．１ｍｍの間隔で並べた。第１の探傷ユニット１ａの探触子２ａから送信した超音波８ｘを、探傷ユニットと対向して配置した反射板５で反射し、第２の探傷ユニット１ｂの探触子２ｂによって受信した。探傷ユニット１と反射板５との間に、被検査体６として板厚３．２ｍｍで内部に幅５ｍｍの人工欠陥を有する鋼板を配置し、人工欠陥の位置と超音波透過エコー強度２１ｘとの関係を図１（ｂ）に実線で示した。図１（ｂ）には併せて、第１の探傷ユニット１ａの探触子２ａから送信した超音波８ａを同じ探触子２ａで受信した場合の透過エコー強度２１ａの状況を破線で示し、第２の探傷ユニット１ｂの探触子２ｂから送信した超音波８ｂを同じ探触子２ｂで受信した場合の透過エコー強度２１ｂの状況を一点鎖線で示している。 As in the case of FIG. 2, a flaw detection unit 1 having a line focus type probe having a frequency of 20 MHz, a transducer width of 8 mm, and a focal length of 200 mm is used. As shown in FIG. Were arranged at intervals of 8.1 mm. The ultrasonic wave 8x transmitted from the probe 2a of the first flaw detection unit 1a was reflected by the reflecting plate 5 disposed facing the flaw detection unit and received by the probe 2b of the second flaw detection unit 1b. Between the flaw detection unit 1 and the reflector 5, a steel plate having a thickness of 3.2 mm and an internal defect of 5 mm is disposed as the object to be inspected 6, and the position of the artificial defect and the ultrasonic transmission echo intensity 21x The relationship is shown by a solid line in FIG. FIG. 1 (b) also shows the state of the transmitted echo intensity 21a when the ultrasonic wave 8a transmitted from the probe 2a of the first flaw detection unit 1a is received by the same probe 2a by a broken line. The state of the transmitted echo intensity 21b when the ultrasonic wave 8b transmitted from the probe 2b of the second flaw detection unit 1b is received by the same probe 2b is indicated by a one-dot chain line.

図１から明らかなように、第１の探傷ユニット１ａから超音波を送信して第２の探傷ユニット１ｂで受信した超音波８ｘの透過エコー強度２１ｘについては、第１と第２の探傷ユニットの中間位置について検出閾値２２より大きな減衰が得られ、十分な検出感度を有する有効探傷幅２３ｘが実現していることが明らかである。そしてこの有効探傷幅２３ｘは、第１の探傷ユニット単独を用いた場合の有効探傷幅２３ａと、第２の探傷ユニット単独を用いた場合の有効探傷幅２３ｂとの間を十分にカバーしており、不感帯２４が解消していることがわかる。 As is clear from FIG. 1, the transmitted echo intensity 21x of the ultrasonic wave 8x transmitted from the first flaw detection unit 1a and received by the second flaw detection unit 1b is the same as that of the first and second flaw detection units. It is clear that an attenuation greater than the detection threshold 22 is obtained at the intermediate position, and an effective flaw detection width 23x having sufficient detection sensitivity is realized. The effective flaw detection width 23x sufficiently covers the effective flaw detection width 23a when the first flaw detection unit is used alone and the effective flaw detection width 23b when the second flaw detection unit is used alone. It can be seen that the dead zone 24 has been eliminated.

即ち本発明では、２以上の探傷ユニット１を配列し、１つの探傷ユニット１ａから発射した超音波を同じ探傷ユニット１ａによって受信するとともに、１つの探傷ユニット１ａから発射した超音波を隣接する別の探傷ユニット１ｂによっても受信することにより、探傷ユニット１の有効探傷幅２３よりも広い間隔で探傷ユニットを配置しても、被検査体の幅方向全幅を一度にカバーする探傷範囲を実現することができる。そのため、配置する探傷ユニット１の個数をほぼ半数まで削減することが可能となり、探傷ユニット１を２列の千鳥配列とする必要がなくなる。 That is, in the present invention, two or more flaw detection units 1 are arranged, the ultrasonic waves emitted from one flaw detection unit 1a are received by the same flaw detection unit 1a, and the ultrasonic waves emitted from one flaw detection unit 1a are separated from each other. By receiving also by the flaw detection unit 1b, it is possible to realize a flaw detection range that covers the entire width in the width direction of the object to be inspected at one time even if the flaw detection units are arranged at intervals wider than the effective flaw detection width 23 of the flaw detection unit 1. it can. Therefore, the number of flaw detection units 1 to be arranged can be reduced to almost half, and the flaw detection units 1 do not need to be arranged in two rows in a staggered arrangement.

また、ここまでは探傷ユニット１ａから発射した超音波を同じ探傷ユニット１ａによって受信するとともに、１つの探傷ユニット１ａから発射した超音波を隣接する別の探傷ユニット１ｂによっても受信する場合について説明したが、受信する探傷ユニットが送信探傷ユニットの超音波の広がり内であれば、受信する探傷ユニットは複数であってもかまわない。 In the above description, the case where the ultrasonic wave emitted from the flaw detection unit 1a is received by the same flaw detection unit 1a and the ultrasonic wave emitted from one flaw detection unit 1a is also received by another adjacent flaw detection unit 1b has been described. As long as the received flaw detection unit is within the ultrasonic spread of the transmission flaw detection unit, a plurality of flaw detection units may be received.

本発明で用いる探傷ユニット１としては、上記のように被検査体の一方の側に配置した探触子２から超音波を送信及び受信し、被検査体の反対側に配置した反射板５で超音波を反射する形態のみならず、図４に示すように、被検査体の一方の側に超音波を発射する送信探触子３を配置し、被検査体の他方の側に超音波を受信する受信探触子４を配置した形態のものについても適用することができる。第１の探傷ユニット１ａの送信探触子３ａから超音波８ａを発射し、第１の探傷ユニット１ａの受信探触子４ａによって受信すると共に、第１の探傷ユニット１ａの送信探触子３ａから発射した超音波８ｘを第２の探傷ユニット１ｂの受信探触子４ｂによっても受信する。 As described above, the flaw detection unit 1 used in the present invention is a reflector 5 that transmits and receives ultrasonic waves from the probe 2 disposed on one side of the object to be inspected and is disposed on the opposite side of the object to be inspected. As shown in FIG. 4, the transmission probe 3 that emits ultrasonic waves is disposed on one side of the object to be examined, and the ultrasonic waves are transmitted to the other side of the object to be examined. The present invention can also be applied to a configuration in which the receiving probe 4 for receiving is arranged. The ultrasonic wave 8a is emitted from the transmission probe 3a of the first flaw detection unit 1a, received by the reception probe 4a of the first flaw detection unit 1a, and from the transmission probe 3a of the first flaw detection unit 1a. The emitted ultrasonic wave 8x is also received by the reception probe 4b of the second flaw detection unit 1b.

本発明において、図５（ａ）（ｂ）に示すように、一の探傷ユニット１ａから発射した超音波を同一の探傷ユニット１ａで受信するタイミング（図５（ａ））と、同じ探傷ユニット１ａから発射した超音波を隣接する別の探傷ユニット１ｂで受信するタイミング（図５（ｂ））とを別々のタイミングとすることができる。このような実施の形態を採用することにより、超音波を受信して透過エコーの減衰状況を評価するための信号処理装置１５の台数が１台のみであっても、超音波探触を行うことができる。この場合、第１の探傷ユニット１ａで送信と受信を共に行うタイミング、第１の探傷ユニット１ａで送信し第２の探傷ユニット１ｂで受信するタイミング、第２の探傷ユニット１ｂで送信と受信を共に行うタイミング、第２の探傷ユニット１ｂで送信し第３の探触ニット１ｃで受信するタイミング、と次々に処理を行うこととなる。 In the present invention, as shown in FIGS. 5 (a) and 5 (b), the same flaw detection unit 1a as the timing (FIG. 5 (a)) at which the ultrasonic wave emitted from one flaw detection unit 1a is received by the same flaw detection unit 1a. The timing (FIG. 5 (b)) at which the ultrasonic waves emitted from 1 are received by another adjacent flaw detection unit 1b can be set as separate timings. By adopting such an embodiment, even if there is only one signal processing device 15 for receiving the ultrasonic wave and evaluating the attenuation state of the transmitted echo, the ultrasonic probe is performed. Can do. In this case, the timing at which both transmission and reception are performed by the first flaw detection unit 1a, the timing at which transmission is performed by the first flaw detection unit 1a and the reception by the second flaw detection unit 1b, and transmission and reception are both performed by the second flaw detection unit 1b. Processing is performed one after another, timing to perform, timing to transmit by the second flaw detection unit 1b and reception by the third probe unit 1c.

一方、一の探傷ユニット１ａから発射した超音波を、図５（ｃ）に示すように、同一の探傷ユニット１ａ及び隣接する別の探傷ユニット１ｂによって同時期に受信することとするとより好ましい。この場合には、超音波を受信して透過エコーの減衰状況を評価するための信号処理装置１５の台数を少なくとも２台準備することが必要となるが、幅方向に配列した一連の探傷ユニットを用いた処理を行うにあたって、必要なタイミングの回数を半分に減らすことができる。これにより、被検査体の全幅を検出するのに要する時間を半減することが可能となり、被検査体を長手方向に走行させる走査速度を倍増することができる。 On the other hand, it is more preferable that ultrasonic waves emitted from one flaw detection unit 1a are received at the same time by the same flaw detection unit 1a and another flaw detection unit 1b adjacent thereto as shown in FIG. 5 (c). In this case, it is necessary to prepare at least two signal processing devices 15 for receiving ultrasonic waves and evaluating the attenuation state of transmitted echoes, but a series of flaw detection units arranged in the width direction are required. In performing the processing used, the number of necessary timings can be reduced by half. This makes it possible to halve the time required to detect the full width of the object to be inspected, and to double the scanning speed for running the object to be inspected in the longitudinal direction.

反射板５を用いた透過法によって鋼板の欠陥を検出する超音波探傷装置において、本発明を適用した。探傷ユニット１として図１（ａ）に示すものを用いた。 The present invention was applied to an ultrasonic flaw detector that detects a defect in a steel plate by a transmission method using the reflector 5. The flaw detection unit 1 shown in FIG.

探傷ユニット１の探触子２として、周波数２０ＭＨｚ、振動子幅８ｍｍ、焦点距離２００ｍｍのラインフォーカス型探触子を用い、被検査体５を挟んで探触子２の反対側に反射板５を設け、探触子２から送信した超音波は被検査体６を透過して反射板５で反射し、再度被検査体６を透過した後に探触子２に戻って受信される。探傷ユニット１を８．１ｍｍの等間隔で１６組配列した。探傷ユニットを含めた全体の接続状況の概要を図６に示す。 A line focus type probe having a frequency of 20 MHz, a transducer width of 8 mm, and a focal length of 200 mm is used as the probe 2 of the flaw detection unit 1, and the reflector 5 is placed on the opposite side of the probe 2 with the object 5 to be inspected in between. The ultrasonic waves provided and transmitted from the probe 2 are transmitted through the inspection object 6 and reflected by the reflecting plate 5, and after passing through the inspection object 6 again, are returned to the probe 2 and received. Sixteen sets of flaw detection units 1 were arranged at equal intervals of 8.1 mm. FIG. 6 shows an overview of the overall connection status including the flaw detection unit.

受信した超音波信号から欠陥を検出するための信号処理装置１５は、２台１組として２組配置している。同期制御部１０からは、周期１ｍ秒の間隔で同期信号が発信される。同期制御部１０と各探傷ユニット１の送信部１３との間はマルチプレクサ１１で接続され、一度に２組の探傷ユニットに信号が送られ、超音波が発信される。図６においては、第１の探傷ユニット１ａと第９の探傷ユニット１ｉに接続されている。また、１組２台の信号処理装置（１５ａ、１５ｂ）はマルチプレクサ１２によってそれぞれ探傷ユニット１の受信部１４に接続される。図６においては、第１組の２台の信号処理装置（１５ａ、１５ｂ）はそれぞれ第１、第２の探傷ユニット（１ａ、１ｂ）に接続され、第２組の２台の信号処理装置（１５ｃ、１５ｄ）はそれぞれ第９、第１０の探傷ユニット（１ｉ、１ｊ）に接続されている。各信号処理装置１５はパーソナルコンピュータによって構成されるデータ処理部１６に接続されている。各信号処理装置１５で検出された結果は、データ処理部１６に送られ集計され、鋼板における欠陥の発生部位と検出された欠陥の性質とが記録される。 Two sets of signal processing devices 15 for detecting defects from the received ultrasonic signals are arranged as one set. A synchronization signal is transmitted from the synchronization control unit 10 at intervals of a period of 1 msec. The multiplexer 11 is connected between the synchronization control unit 10 and the transmission unit 13 of each flaw detection unit 1, and signals are sent to two sets of flaw detection units at a time to transmit ultrasonic waves. In FIG. 6, it is connected to the first flaw detection unit 1a and the ninth flaw detection unit 1i. A set of two signal processing devices (15a, 15b) are connected to the receiving unit 14 of the flaw detection unit 1 by a multiplexer 12, respectively. In FIG. 6, the first set of two signal processing devices (15a, 15b) are connected to the first and second flaw detection units (1a, 1b), respectively, and the second set of two signal processing devices ( 15c, 15d) are connected to the ninth and tenth flaw detection units (1i, 1j), respectively. Each signal processing device 15 is connected to a data processing unit 16 constituted by a personal computer. The results detected by each signal processing device 15 are sent to the data processing unit 16 where they are aggregated, and the location of the defect in the steel sheet and the nature of the detected defect are recorded.

同期制御部１０からの同期信号が発せられると、マルチプレクサ１１を通じて第１、第９の探傷ユニット（１ａ、１ｉ）に信号が到達し、両探傷ユニットから同時に超音波パルスが発射される。第１の探傷ユニット１ａから発射された超音波は、被検査体６を通過し、反射板５で反射し、再度被検査体５を通過した後、第１と第２の探傷ユニット（１ａ、１ｂ）で受信され、それぞれマルチプレクサ１２を通じて２台の信号処理装置（１５ａ、１５ｂ）に送られ、透過エコー強度２１の解析から欠陥の有無が検出される。第９の探傷ユニット１ｉからの超音波も同様に処理される。 When a synchronization signal is issued from the synchronization control unit 10, the signals reach the first and ninth flaw detection units (1a, 1i) through the multiplexer 11, and ultrasonic pulses are simultaneously emitted from both flaw detection units. The ultrasonic wave emitted from the first flaw detection unit 1a passes through the inspection object 6, is reflected by the reflecting plate 5, passes through the inspection object 5 again, and then the first and second flaw detection units (1a, 1b) and sent to the two signal processing devices (15a, 15b) through the multiplexer 12, respectively, and the presence or absence of a defect is detected from the analysis of the transmitted echo intensity 21. The ultrasonic waves from the ninth flaw detection unit 1i are similarly processed.

第１と第９の探傷ユニット（１ａ、１ｉ）からの発信が完了すると、送信側マルチプレクサ１１は第２、第１０の探傷ユニット（１ｂ、１ｊ）に接続を組み替え、受信側マルチプレクサ１２は第２、３、第１０、１１の探傷ユニット（１ｂ、１ｃ、１ｊ、１ｋ）に接続を組み替える。このようにして次々と超音波送信を繰り返し、８ｍ秒の時間内に８回の送信を完了すると、鋼板の全幅についての一連の処理が完了することとなる。即ち、全幅の探傷を行うための探傷周期は８ｍ秒である。 When the transmission from the first and ninth flaw detection units (1a, 1i) is completed, the transmission side multiplexer 11 is reconnected to the second and tenth flaw detection units (1b, 1j), and the reception side multiplexer 12 is the second one. The connection is rearranged to the third, tenth, and eleventh flaw detection units (1b, 1c, 1j, and 1k). In this way, ultrasonic transmission is repeated one after another, and when transmission of 8 times is completed within a time of 8 milliseconds, a series of processes for the full width of the steel sheet is completed. That is, the flaw detection cycle for performing full width flaw detection is 8 milliseconds.

探傷を行いつつ、鋼板をその長手方向に走行させる。走行速度は３ｍ／ｓとした。これにより、欠陥の鋼板長手方向における長さが２４ｍｍまでの大きさの欠陥を検出することが可能である。 While performing flaw detection, the steel plate is run in the longitudinal direction. The traveling speed was 3 m / s. Thereby, it is possible to detect a defect having a length of up to 24 mm in the longitudinal direction of the steel plate.

本発明を説明する図であり、（ａ）は２台の探傷ユニットの配置を示す図、（ｂ）は人工欠陥による透過エコーの減衰状況を示す図である。It is a figure explaining this invention, (a) is a figure which shows arrangement | positioning of two flaw detection units, (b) is a figure which shows the attenuation | damping condition of the transmission echo by an artificial defect. １台の探傷ユニットによる透過エコーの状況を示す図であり、（ａ）は探傷ユニットの配置を示す図、（ｂ）は人工欠陥による透過エコーの減衰状況を示す図である。It is a figure which shows the condition of the transmission echo by one flaw detection unit, (a) is a figure which shows arrangement | positioning of a flaw detection unit, (b) is a figure which shows the attenuation | damping condition of the transmission echo by an artificial defect. ２台の探傷ユニットによる透過エコーの状況を示す図であり、（ａ）は各探傷ユニットの配置を示す図、（ｂ）は人工欠陥による透過エコーの減衰状況を示す図である。It is a figure which shows the condition of the transmission echo by two flaw detection units, (a) is a figure which shows arrangement | positioning of each flaw detection unit, (b) is a figure which shows the attenuation | damping condition of the transmission echo by an artificial defect. 本発明の２台の探傷ユニットの配置を示す図である。It is a figure which shows arrangement | positioning of the two flaw detection units of this invention. 本発明の２台の探傷ユニットを用いて透過エコーを検出する状況を示す図である。It is a figure which shows the condition which detects a transmission echo using the two flaw detection units of this invention. 本発明の超音波探傷装置の接続状況を示す図である。It is a figure which shows the connection condition of the ultrasonic flaw detector of this invention. 透過型超音波探傷装置の原理を説明する図である。It is a figure explaining the principle of a transmission type ultrasonic flaw detector. 透過型超音波探傷装置において欠陥によって超音波が減衰する状況を説明する図である。It is a figure explaining the condition where an ultrasonic wave attenuate | damps by a defect in a transmissive | pervious ultrasonic flaw detector.

Explanation of symbols

１探傷ユニット
２送受信探触子
３送信探触子
４受信探触子
５反射板
６被検査体
７欠陥
８超音波
１０同期制御部
１１マルチプレクサ
１２マルチプレクサ
１３送信部
１４受信部
１５信号処理装置
１６データ処理部
２１透過エコー強度
２２検出閾値
２３有効探傷幅
２４不感帯
２５探傷ユニット配置間隔 DESCRIPTION OF SYMBOLS 1 Flaw detection unit 2 Transmission / reception probe 3 Transmission probe 4 Reception probe 5 Reflector 6 Inspected object 7 Defect 8 Ultrasonic 10 Synchronization control part 11 Multiplexer 12 Multiplexer 13 Transmission part 14 Reception part 15 Signal processing apparatus 16 Data Processing unit 21 Transmitted echo intensity 22 Detection threshold 23 Effective flaw detection width 24 Dead band 25 Flaw detection unit arrangement interval

Claims

In an ultrasonic flaw detection method for detecting a defect in a test object using a flaw detection unit that transmits an ultrasonic wave and transmits it after passing through the test object, two or more flaw detection units are arranged and fired from one flaw detection unit. An ultrasonic flaw detection method characterized in that an ultrasonic wave is received by the same flaw detection unit and an ultrasonic wave emitted from one flaw detection unit is also received by another flaw detection unit adjacent thereto.

Each flaw detection unit is a probe that transmits and receives ultrasonic waves, transmits and receives ultrasonic waves from a probe disposed on one side of the object to be inspected, and is disposed on the opposite side of the object to be inspected. The ultrasonic flaw detection method according to claim 1, wherein the ultrasonic wave is reflected by a reflecting plate.

Each of the flaw detection units includes a transmission probe that emits ultrasonic waves on one side of the object to be inspected, and a reception probe that receives ultrasonic waves on the other side of the object to be inspected. The ultrasonic flaw detection method according to claim 1.

The ultrasonic flaw detection method according to any one of claims 1 to 3, wherein ultrasonic waves emitted from one flaw detection unit are received at the same time by the same flaw detection unit and another flaw detection unit adjacent thereto.

An ultrasonic flaw detection apparatus that detects a defect in a test object using a flaw detection unit that transmits ultrasonic waves and receives the light after passing through the test object. Two or more flaw detection units are arranged, and one flaw detection unit is arranged. An ultrasonic flaw detector characterized by receiving the emitted ultrasonic waves by the same flaw detection unit and receiving the ultrasonic waves emitted from one flaw detection unit by another flaw detection unit adjacent thereto.

Each of the flaw detection units is a probe that transmits and receives ultrasonic waves, the flaw detection unit is disposed on one side of the object to be inspected, and a reflector is disposed on the opposite side of the object to be inspected. The ultrasonic flaw detector according to claim 5, wherein the ultrasonic wave is transmitted and received, and the ultrasonic wave is reflected by a reflecting plate.

Each of the flaw detection units includes a transmission probe that is arranged on one side of the object to be inspected and emits ultrasonic waves, and a reception probe that is arranged on the other side of the object to be inspected and receives ultrasonic waves. The ultrasonic flaw detector according to claim 5.

The ultrasonic flaw detector according to any one of claims 5 to 7, wherein ultrasonic waves emitted from one flaw detection unit are received at the same time by the same flaw detection unit and another flaw detection unit adjacent thereto.