JP2012154747A - Crack depth measuring method and crack depth measuring device - Google Patents

Crack depth measuring method and crack depth measuring device Download PDF

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JP2012154747A
JP2012154747A JP2011013375A JP2011013375A JP2012154747A JP 2012154747 A JP2012154747 A JP 2012154747A JP 2011013375 A JP2011013375 A JP 2011013375A JP 2011013375 A JP2011013375 A JP 2011013375A JP 2012154747 A JP2012154747 A JP 2012154747A
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crack
crack depth
ultrasonic probe
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Hajime Takada
一 高田
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JFE Steel Corp
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Abstract

PROBLEM TO BE SOLVED: To provide a crack depth measuring method and device using an ultrasonic TOFD process, enabling the depth of any crack in an examination object to be readily and accurately measured in an extremely simple configuration.SOLUTION: In a crack depth measuring method and device for scanning with an ultrasonic probe 1 the peripheries of a crack 30 in an examination object 2 to measure a crack depth d, the ultrasonic probe 1, which is a focus type ultrasonic probe having a hole 21 at the center, receives a surface reflected wave W1 reflected by the surface of the examination object 2 and a diffracted wave W2 diffracted by the tip of the crack 30 and, on the basis of variations of the interference state of the surface reflected wave W1 and the diffracted wave W2 corresponding to the scanning position, measures the crack depth d.

Description

本発明は、超音波探傷、浸透探傷、磁粉探傷などの非破壊試験によって検出された表面クラックの深さ測定を行うクラック深さ測定方法およびクラック深さ測定装置に関するものである。   The present invention relates to a crack depth measuring method and a crack depth measuring apparatus for measuring the depth of a surface crack detected by a nondestructive test such as ultrasonic flaw detection, penetration flaw detection, and magnetic particle flaw detection.

従来から、被検体のきず端部深さ等を測定する技術としてＴＯＦＤ（Time of Flight Diffraction）法が広く知られている。このＴＯＦＤ法は、図７に示すように、被検体１０２内のきず１２１を中心に、超音波発生素子１３１を装着した超音波発生用探触子１０３と超音波受信素子１４１を装着した超音波受信用探触子１０４を対称に配置し、きず１２１に平行に走査（１次元走査）する方法である。超音波発生素子１３１から放射された超音波は、被検体１０２の表面直下をラテラル波として伝搬し、第１波信号として超音波受信素子１４１に受信される。また、被検体１０２にきず１２１がある場合、きず端部１２１ａから回折波が発生し第２波信号として超音波受信素子１４１に受信される。   Conventionally, the TOFD (Time of Flight Diffraction) method is widely known as a technique for measuring the depth of a flaw edge of a subject. In this TOFD method, as shown in FIG. 7, the ultrasonic wave generation probe 103 having the ultrasonic wave generation element 131 and the ultrasonic wave reception element 141 are mounted around the flaw 121 in the subject 102. In this method, the receiving probes 104 are arranged symmetrically and scanned parallel to the flaw 121 (one-dimensional scanning). The ultrasonic wave radiated from the ultrasonic wave generation element 131 propagates as a lateral wave directly below the surface of the subject 102 and is received by the ultrasonic wave reception element 141 as a first wave signal. When the subject 102 has a flaw 121, a diffracted wave is generated from the flaw end 121a and is received by the ultrasonic wave receiving element 141 as a second wave signal.

そして、きず端部１２１ａからの回折波とラテラル波との伝搬時間差から、きず端部深さＴが算出される。具体的には、図８に示すように、超音波発生素子１３１、超音波受信素子１４１及びきず端部１２１ａがそれぞれ直角三角形の頂点にあるものとして、次式（１）によってきず端部深さＴを算出する。
Ｔ＝（Ｗ２−Ｓ２）１／２ …（１）
ただし、Ｔは、きず端部深さであり、Ｗは、超音波発生素子又は超音波受信素子からきず端部までの距離であり、またＳは、素子間距離、すなわち、超音波発生素子と超音波受信素子との間の距離の１／２である。 Then, the flaw end depth T is calculated from the propagation time difference between the diffracted wave and the lateral wave from the flaw end 121a. Specifically, as shown in FIG. 8, assuming that the ultrasonic wave generating element 131, the ultrasonic wave receiving element 141, and the flaw end 121a are at the vertices of a right triangle, the flaw end depth according to the following equation (1): T is calculated.
T = (W 2 −S 2 ) 1/2 (1)
Where T is the depth of the flaw edge, W is the distance from the ultrasonic wave generating element or ultrasonic wave receiving element to the flaw edge, and S is the distance between elements, that is, the ultrasonic wave generating element and One half of the distance to the ultrasonic receiving element.

ここで、式（１）中のＷは、きず端部１２１ａからの回折波の伝搬時間Ｂｗから算出でき、Ｓは、ラテラル波の伝搬時間Ｌｗから算出できる。ただし、両伝搬時間には、超音波発生用探触子１０３及び超音波受信用探触子１０４のホルダー１３２、１４２内の伝搬時間Ｐｄが含まれているので、きず端部深さＴは、伝搬時間Ｂｗ、Ｌｗから伝搬時間Ｐｄを差し引いて算出する。すなわち、式（１）中の距離Ｗは、次式（２）で表され、距離Ｓは、次式（３）で表される。
Ｗ＝｛（Ｂｗ−Ｐｄ）／２｝×Ｃ …（２）
Ｓ＝｛（Ｌｗ−Ｐｄ）／２｝×Ｃ …（３）
ここで、Ｃは被検体の音速であり、距離Ｓは実測値であるので、式（３）から伝搬時間Ｐｄが算出される。この伝搬時間Ｐｄを式（２）に代入することにより、距離Ｗが算出される。そして、距離Ｓ及び距離Ｗを式（１）に代入することにより、きず端部深さＴが算出される。 Here, W in equation (1) can be calculated from the propagation time Bw of the diffracted wave from the flaw end 121a, and S can be calculated from the propagation time Lw of the lateral wave. However, since both propagation times include the propagation times Pd in the holders 132 and 142 of the ultrasonic wave generation probe 103 and the ultrasonic wave reception probe 104, the flaw edge depth T is: It is calculated by subtracting the propagation time Pd from the propagation times Bw and Lw. That is, the distance W in the formula (1) is expressed by the following formula (2), and the distance S is expressed by the following formula (3).
W = {(Bw−Pd) / 2} × C (2)
S = {(Lw−Pd) / 2} × C (3)
Here, since C is the sound velocity of the subject and the distance S is an actual measurement value, the propagation time Pd is calculated from the equation (3). The distance W is calculated by substituting this propagation time Pd into the equation (2). Then, the flaw end depth T is calculated by substituting the distance S and the distance W into the equation (1).

このように、ＴＯＦＤ法によれば、比較的簡単に、きず端部深さを測定することができる。このため、その適用範囲の拡大、また測定精度・効率の向上等を目的として、様々な改良技術が提案されている（特許文献１〜８参照）。   As described above, according to the TOFD method, the flaw end depth can be measured relatively easily. For this reason, various improvement techniques have been proposed for the purpose of expanding the application range and improving measurement accuracy and efficiency (see Patent Documents 1 to 8).

特開平１１−３１６２１５号公報JP 11-316215 A 特開２００１−５０９３８号公報JP 2001-50938 A 特開２００１−２１５２１８号公報JP 2001-215218 A 特開２００１−２２８１２８号公報JP 2001-228128 A 特開２００１−３０５１２４号公報JP 2001-305124 A 特開２００１−３２４４８４号公報JP 2001-324484 A 特開２００２−５９０４号公報JP 2002-5904 A 特開２００４−５３４６２号公報JP 2004-53462 A

しかしながら、いずれの先行技術も、超音波発信素子と超音波受信素子とが別体となっているため、回折波を効率よく受波するためには両者の正確なアライメントが必要であった。そして、このアライメントには精密な走査装置、あるいは探触子ホルダーなどが必要なため、装置の大型化をまねきやすく、形状が単純ではない物体や狭隘な部位に発生するクラックの深さ測定への適用が難しいという問題があった。   However, in any of the prior arts, since the ultrasonic wave transmitting element and the ultrasonic wave receiving element are separated, accurate alignment of both is necessary to receive the diffracted wave efficiently. And since this alignment requires a precise scanning device or probe holder, it is easy to increase the size of the device, and it is possible to measure the depth of cracks occurring in objects that are not simple in shape and narrow parts. There was a problem that it was difficult to apply.

本発明は上記に鑑みてなされたものであって、簡易な構成で、超音波ＴＯＦＤ法を用いて、被検体のクラック深さを、容易かつ正確に測定することができるクラック深さ測定方法およびクラック深さ測定装置を提供することを目的とする。   The present invention has been made in view of the above, and a crack depth measuring method capable of easily and accurately measuring the crack depth of an object using an ultrasonic TOFD method with a simple configuration, and An object is to provide a crack depth measuring device.

上述した課題を解決し、目的を達成するために、本発明にかかるクラック深さ測定方法は、超音波探触子を用いて被検体のクラック周辺を走査してクラック深さを測定するクラック深さ測定方法であって、前記超音波探触子は、中心に孔を有する焦点型の超音波探触子であり、前記超音波探触子が、前記被検体表面から反射する表面反射波と前記クラックの先端で回折した回折波とを受波し、前記走査位置に対応した前記表面反射波と前記回折波との干渉状態の変化をもとに、前記クラック深さを測定することを特徴とする。   In order to solve the above-described problems and achieve the object, the crack depth measurement method according to the present invention is a crack depth measurement method in which a crack depth is measured by scanning the periphery of a crack of an object using an ultrasonic probe. The ultrasonic probe is a focal-type ultrasonic probe having a hole in the center, and the ultrasonic probe reflects a surface reflected wave reflected from the surface of the subject. Receiving a diffracted wave diffracted at the tip of the crack, and measuring the crack depth based on a change in an interference state between the surface reflected wave and the diffracted wave corresponding to the scanning position. And

また、本発明にかかるクラック深さ測定方法は、上記の発明において、前記超音波探触子が発する超音波の波長毎に、前記干渉状態における隣接する受信ピーク間のピッチとクラック深さとの関係を予め求めておき、前記干渉状態のピッチを求め、該ピッチをもとに前記関係からクラック深さを求めることを特徴とする。   In the crack depth measuring method according to the present invention, in the above invention, the relationship between the pitch between adjacent reception peaks in the interference state and the crack depth for each wavelength of the ultrasonic wave emitted by the ultrasonic probe. Is obtained in advance, the pitch of the interference state is obtained, and the crack depth is obtained from the relationship based on the pitch.

また、本発明にかかるクラック深さ測定装置は、超音波探触子を用いて被検体のクラック周辺を走査してクラック深さを測定するクラック深さ測定装置であって、前記超音波探触子は、中心に孔を有する焦点型の超音波探触子であり、前記被検体表面から反射する表面反射波と前記クラックの先端で回折した回折波とを受波し、前記走査位置に対応した前記表面反射波と前記回折波との干渉状態の変化をもとに、前記クラック深さを測定する測定手段を備えたことを特徴とする。   The crack depth measuring apparatus according to the present invention is a crack depth measuring apparatus that measures the crack depth by scanning the periphery of a crack of an object using an ultrasonic probe, the ultrasonic probe. The child is a focal-type ultrasonic probe having a hole in the center, and receives a surface reflected wave reflected from the subject surface and a diffracted wave diffracted at the tip of the crack, and corresponds to the scanning position. And a measuring means for measuring the crack depth based on a change in the interference state between the surface reflected wave and the diffracted wave.

また、本発明にかかるクラック深さ測定装置は、上記の発明において、前記測定手段は、前記超音波探触子が発する超音波の波長毎に、前記干渉状態における隣接する受信ピーク間のピッチとクラック深さとの関係を予め求めておき、測定時に、前記干渉状態のピッチを求め、該ピッチをもとに前記関係からクラック深さを求めることを特徴とする。   In the crack depth measuring apparatus according to the present invention, in the above invention, the measuring means may include a pitch between adjacent reception peaks in the interference state for each wavelength of the ultrasonic wave emitted by the ultrasonic probe. The relationship with the crack depth is obtained in advance, and the pitch of the interference state is obtained at the time of measurement, and the crack depth is obtained from the relationship based on the pitch.

本発明によれば、中心に孔を有する超音波探触子を１次元走査するという極めて簡易な操作によって、被検体のクラック深さを、容易かつ正確に測定することができるので、様々な非破壊試験現場におけるクラック深さ測定に有効である。   According to the present invention, the crack depth of an object can be measured easily and accurately by an extremely simple operation of one-dimensional scanning of an ultrasonic probe having a hole in the center. It is effective for crack depth measurement at the destructive test site.

図１は、本発明の実施の形態にかかる超音波探傷装置の全体構成を示す模式図である。FIG. 1 is a schematic diagram showing an overall configuration of an ultrasonic flaw detector according to an embodiment of the present invention. 図２は、図１に示した超音波探触子の構成を示す断面図である。FIG. 2 is a cross-sectional view showing the configuration of the ultrasonic probe shown in FIG. 図３は、図２に示した超音波探触子を走査した状態を示す断面図である。FIG. 3 is a cross-sectional view illustrating a state in which the ultrasonic probe illustrated in FIG. 2 is scanned. 図４は、超音波探触子が受波した表面反射波と回折波とが干渉した際の受波超音波振幅の位置依存性を示す図である。FIG. 4 is a diagram showing the position dependency of the received ultrasonic amplitude when the surface reflected wave and the diffracted wave received by the ultrasonic probe interfere with each other. 図５は、クラック深さ測定の原理を説明する説明図である。FIG. 5 is an explanatory diagram for explaining the principle of crack depth measurement. 図６は、本発明によって測定したクラック深さと切断試験により求めたクラック深さとを対比して示した結果を示す図である。FIG. 6 is a diagram showing the results of comparing the crack depth measured by the present invention with the crack depth determined by the cutting test. 図７は、従来のＴＯＦＤ法を説明するための斜視図である。FIG. 7 is a perspective view for explaining the conventional TOFD method. 図８は、従来のＴＯＦＤ法を説明するための説明図である。FIG. 8 is an explanatory diagram for explaining a conventional TOFD method.

以下に、図面を参照して、本発明にかかるクラック深さ測定方法およびクラック深さ測定装置の実施の形態について説明する。なお、この実施の形態によりこの発明が限定されるものではない。   Embodiments of a crack depth measuring method and a crack depth measuring apparatus according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiments.

図１は、本発明の実施の形態にかかる超音波探傷によるクラック深さ測定装置の構成を示す模式図である。図１において、超音波探触子１は、図示しない１次元走査装置に取り付けられている。超音波探触子１は、超音波送受信器１０に接続され、超音波送受信器１０から一定の繰返し周期にて印加される高電圧パルスにより超音波パルスを水中へ送波する。超音波探触子１は、この超音波パルスにより被検体表面からの反射波およびクラック先端からの回折波が重畳された超音波を受波する。超音波送受信器１０は、超音波探触子１によって受波され電気信号に変換された信号を適当な振幅に増幅する。増幅後の超音波信号はゲート回路１１へ送られ、ゲート回路１１は、受波超音波による信号のみを抽出し、ピーク値検出回路１２に送る。ピーク値検出回路１２は、入力された超音波による信号の振幅を検出し、その結果を制御表示装置１３に送る。制御表示装置１３は、１次元走査装置の動きを制御しつつ、超音波探触子１の位置と対応付けて超音波による信号の振幅を収集し、この結果に基づいて、クラック深さを演算し、表示する。   FIG. 1 is a schematic diagram showing the configuration of a crack depth measuring apparatus using ultrasonic flaw detection according to an embodiment of the present invention. In FIG. 1, an ultrasonic probe 1 is attached to a one-dimensional scanning device (not shown). The ultrasonic probe 1 is connected to an ultrasonic transmitter / receiver 10 and transmits ultrasonic pulses into water by high voltage pulses applied from the ultrasonic transmitter / receiver 10 at a constant repetition period. The ultrasonic probe 1 receives the ultrasonic wave on which the reflected wave from the subject surface and the diffracted wave from the crack tip are superimposed by the ultrasonic pulse. The ultrasonic transceiver 10 amplifies the signal received by the ultrasonic probe 1 and converted into an electric signal to an appropriate amplitude. The amplified ultrasonic signal is sent to the gate circuit 11, and the gate circuit 11 extracts only the signal from the received ultrasonic wave and sends it to the peak value detection circuit 12. The peak value detection circuit 12 detects the amplitude of the signal by the inputted ultrasonic wave and sends the result to the control display device 13. The control display device 13 collects the amplitude of the ultrasonic signal in association with the position of the ultrasonic probe 1 while controlling the movement of the one-dimensional scanning device, and calculates the crack depth based on this result. And display.

なお、超音波探触子１には、図示しない給水装置から給水チューブ５を介して水が供給され、超音波探触子１の中央に設けられた給水孔から水が流れ出ることにより、局部水浸法による超音波測定を行うことが可能となる。   The ultrasonic probe 1 is supplied with water from a water supply device (not shown) via a water supply tube 5, and water flows out from a water supply hole provided in the center of the ultrasonic probe 1, thereby causing local water. It is possible to perform ultrasonic measurement by the immersion method.

ここで、上述したクラック深さ測定装置に用いられる超音波探触子の構成について説明する。図２は、超音波探触子１の詳細構成を示す断面図である。また、図３は、図２の状態から超音波探触子１を１次元走査した後の状態を示す断面図である。図２に示すように、この超音波探触子１は、送波器と受波器とを一体化した周知の焦点型超音波探触子の中心に、孔２１および給水孔２２を設けたものである。また、超音波探触子１は、具体的に、中央に孔２１をもったお椀型に成型された超音波振動子２０によって実現される。   Here, the structure of the ultrasonic probe used for the crack depth measuring apparatus mentioned above is demonstrated. FIG. 2 is a cross-sectional view showing a detailed configuration of the ultrasonic probe 1. 3 is a cross-sectional view showing a state after the ultrasonic probe 1 is one-dimensionally scanned from the state of FIG. As shown in FIG. 2, this ultrasonic probe 1 is provided with a hole 21 and a water supply hole 22 at the center of a known focal-type ultrasonic probe in which a transmitter and a receiver are integrated. Is. The ultrasonic probe 1 is specifically realized by an ultrasonic transducer 20 formed in a bowl shape having a hole 21 in the center.

この超音波探触子１を用いたクラック深さ測定は、超音波探触子１と被検体２との間に水を介在させつつ被検体２のクラック３０周辺を走査し、被検体２表面からの表面反射波Ｗ１およびクラック先端において回折した回折波Ｗ２とを受波し、走査にともなう両者（表面反射波Ｗ１と回折波Ｗ２）の干渉状態の変化に基づいて行われる。   The crack depth measurement using the ultrasonic probe 1 is performed by scanning the periphery of the crack 30 of the subject 2 while interposing water between the ultrasonic probe 1 and the subject 2, and the surface of the subject 2. The surface reflected wave W1 from the laser beam and the diffracted wave W2 diffracted at the tip of the crack are received and performed based on the change in the interference state between the two (surface reflected wave W1 and diffracted wave W2) accompanying the scanning.

なお、超音波探触子１には、お椀型（断面が円弧の球面）の超音波振動子２０が設けられるが、入射角が臨界角より小さくなるように、断面円弧の角度は臨界角以下にしている。これは、入射した超音波から漏洩表面波が励起されることにより、受波器が表面反射波Ｗ１および回折波Ｗ２以外の余分な超音波（漏洩表面波がモード変換された縦波）を受けることがないようにするためである。   The ultrasonic probe 1 is provided with a bowl-shaped (spherical spherical section) ultrasonic transducer 20, but the angle of the cross-sectional arc is equal to or less than the critical angle so that the incident angle is smaller than the critical angle. I have to. This is because the leaky surface wave is excited from the incident ultrasonic wave, so that the receiver receives extra ultrasonic waves (longitudinal wave in which the leaky surface wave is mode-converted) other than the surface reflected wave W1 and the diffracted wave W2. This is so that there is no such thing.

このような中心に孔２１を有する焦点型の超音波探触子１を用いることにより、被検体２の表面反射波Ｗ１およびクラック３０先端からの回折波Ｗ２を受波することができる。この構成では、送波器と受波器が一体化されているので、走査に際して特段のアライメントは不要となる。また、この焦点型の超音波探触子１はその中心に孔２１が開いているため、孔２１のない焦点型の超音波探触子に比べ、中心に入射した入射波による直接反射波の受波を防止できるため、表面反射波の大きさを格段に低くすることができる。一方、回折波のレベルは、小さいため、これによって、被検体２の表面からの表面反射波Ｗ１のレベルとクラック３０先端からの回折波Ｗ２のレベルとが近くなるため、受波された超音波から両者の干渉現象を観察することが容易となる。   By using the focal-type ultrasonic probe 1 having the hole 21 at the center, the surface reflected wave W1 of the subject 2 and the diffracted wave W2 from the tip of the crack 30 can be received. In this configuration, since the transmitter and the receiver are integrated, no special alignment is required for scanning. Further, since the focus type ultrasonic probe 1 has a hole 21 at the center thereof, a direct reflected wave due to an incident wave incident on the center is compared with a focus type ultrasonic probe having no hole 21. Since reception can be prevented, the magnitude of the surface reflected wave can be significantly reduced. On the other hand, since the level of the diffracted wave is small, the level of the surface reflected wave W1 from the surface of the subject 2 and the level of the diffracted wave W2 from the tip of the crack 30 become close to each other. Therefore, it becomes easy to observe the interference phenomenon between the two.

ここで、表面反射波Ｗ１と回折波Ｗ２との干渉について説明する。図３に示すように、超音波探触子１をクラック３０周辺で走査すると、クラック３０と超音波探触子１との位置関係によって干渉現象が生じる。これは、図２および図３に示した表面反射波Ｗ１と回折波Ｗ２との位相差が異なるからである。この結果、図４に示すように、クラック３０周辺では、超音波探触子１の位置変化によって、超音波探触子１による表面反射波Ｗ１と回折波Ｗ２とが干渉した受信超音波振幅を検出する。すなわち、クラック３０周辺において走査すると、干渉による強めあい、弱めあいによって、受波超音波振幅が波打ったものとなる。この波うちの周期は、クラック深さに比例するので、波うち周期を計測することによりクラック深さｄを測定することができる。   Here, interference between the surface reflected wave W1 and the diffracted wave W2 will be described. As shown in FIG. 3, when the ultrasonic probe 1 is scanned around the crack 30, an interference phenomenon occurs due to the positional relationship between the crack 30 and the ultrasonic probe 1. This is because the phase difference between the surface reflected wave W1 and the diffracted wave W2 shown in FIGS. 2 and 3 is different. As a result, as shown in FIG. 4, in the vicinity of the crack 30, the received ultrasonic amplitude resulting from interference between the surface reflected wave W <b> 1 and the diffracted wave W <b> 2 by the ultrasonic probe 1 due to a change in the position of the ultrasonic probe 1 is obtained. To detect. That is, when scanning is performed in the vicinity of the crack 30, the received ultrasonic wave amplitude is wavy due to strengthening and weakening due to interference. Since the period of the wave is proportional to the crack depth, the crack depth d can be measured by measuring the period of the wave.

すなわち、クラック深さｄは、次式（４）によって求めることができる。
ｄ＝ｌ1／tanθ1＝ｌ２／tanθ２ …（４）
ただし、図５に示すように、ｌ1、ｌ２は、位相が２πずれた隣り合うピーク振幅値をもつ位置Ｐ１，Ｐ２とクラック３０の位置Ｐとの間の距離である。また、θ１，θ２は、クラック３０の回折位置における位置Ｐ１，Ｐ２への回折角である。 That is, the crack depth d can be obtained by the following equation (4).
d = l 1 / tan θ 1 = l 2 / tan θ 2 (4)
However, as shown in FIG. 5, l 1 and l 2 are distances between positions P 1 and P 2 having adjacent peak amplitude values whose phases are shifted by 2π and the position P of the crack 30. Θ1 and θ2 are diffraction angles to the positions P 1 and P 2 at the diffraction position of the crack 30.

なお、実際には、距離ｌ１，ｌ２間の距離（ピッチ）と、クラック３０の深さｄとは比例関係にあるので、同じ超音波の波長のときの比例関係を予め求めておき、このピッチを測定することによって直ちにクラック３０の深さｄを求めるようにしている。この場合、超音波探触子１が発する超音波の波長ごとに、ピッチとクラック深さとの関係を予め求めておき、この比例関係を制御表示装置１３に予め保持させておき、測定時に、ピッチのみを求め、このピッチから比例関係をもとにクラック深さを求めるようにするとよい。 In practice, since the distance (pitch) between the distances l 1 and l 2 and the depth d of the crack 30 are in a proportional relationship, the proportional relationship at the same ultrasonic wavelength is obtained in advance. By measuring this pitch, the depth d of the crack 30 is immediately obtained. In this case, the relationship between the pitch and the crack depth is obtained in advance for each wavelength of the ultrasonic wave emitted from the ultrasonic probe 1, and this proportional relationship is held in the control display device 13 in advance. It is preferable to obtain the crack depth from this pitch based on the proportional relationship.

（実施例）
超音波プローブ１として、超音波振動子２０の材質をＰ（ＶＤＦ−ＴｒＦＥ）、周波数３０ＭＨｚ、超音波振動子直径６ｍｍ、水中焦点距離１２ｍｍ、中心孔径３ｍｍの仕様のものを用いて、クラック深さの測定を行った。図６は、３個のクラックについて、本発明により測定したクラック深さと切断試験により求めたクラック深さとを対比して示した結果である。切断試験によって求めたクラック深さに対して０．０１〜０．０２ｍｍ程度の誤差があったのみで、それぞれ良好な測定となっている。 (Example)
As the ultrasonic probe 1, the material of the ultrasonic transducer 20 is P (VDF-TrFE), the frequency is 30 MHz, the ultrasonic transducer diameter is 6 mm, the underwater focal length is 12 mm, and the center hole diameter is 3 mm. Was measured. FIG. 6 shows the results of comparing the crack depth measured by the present invention with the crack depth determined by the cutting test for three cracks. Only an error of about 0.01 to 0.02 mm with respect to the crack depth determined by the cutting test is obtained, and each is a good measurement.

なお、本発明の実施形態では、超音波探触子１を１次元走査装置に取り付け走査したが、超音波探触子１の位置を、位置検出手段によって検知しつつ、超音波探触子１を手持ち走査することも可能である。   In the embodiment of the present invention, the ultrasonic probe 1 is attached to and scanned by the one-dimensional scanning device, but the ultrasonic probe 1 is detected while detecting the position of the ultrasonic probe 1 by the position detecting means. It is also possible to perform hand-held scanning.

１ 超音波探触子
２ 被検体
５ 給水チューブ
１０ 超音波送受信器
１１ ゲート回路
１２ ピーク値検出回路
１３ 制御表示装置
２０ 超音波振動子
２１ 孔
２２ 給水孔
３０ クラック
Ｗ１ 表面反射波
Ｗ２ 回折波 DESCRIPTION OF SYMBOLS 1 Ultrasonic probe 2 Subject 5 Water supply tube 10 Ultrasonic transmitter / receiver 11 Gate circuit 12 Peak value detection circuit 13 Control display device 20 Ultrasonic vibrator 21 Hole 22 Water supply hole 30 Crack W1 Surface reflected wave W2 Diffracted wave

Claims (4)

超音波探触子を用いて被検体のクラック周辺を走査してクラック深さを測定するクラック深さ測定方法であって、
前記超音波探触子は、中心に孔を有する焦点型の超音波探触子であり、
前記超音波探触子が、前記被検体表面から反射する表面反射波と前記クラックの先端で回折した回折波とを受波し、
前記走査位置に対応した前記表面反射波と前記回折波との干渉状態の変化をもとに、前記クラック深さを測定することを特徴とするクラック深さ測定方法。 A crack depth measurement method that measures the crack depth by scanning the periphery of a crack of an object using an ultrasonic probe,
The ultrasonic probe is a focal type ultrasonic probe having a hole in the center,
The ultrasonic probe receives a surface reflected wave reflected from the object surface and a diffracted wave diffracted at the tip of the crack,
A crack depth measuring method, wherein the crack depth is measured based on a change in an interference state between the surface reflected wave and the diffracted wave corresponding to the scanning position. 前記超音波探触子が発する超音波の波長毎に、前記干渉状態における隣接する受信ピーク間のピッチとクラック深さとの関係を予め求めておき、
前記干渉状態のピッチを求め、該ピッチをもとに前記関係からクラック深さを求めることを特徴とする請求項１に記載のクラック深さ測定方法。 For each wavelength of ultrasonic waves emitted by the ultrasonic probe, the relationship between the pitch between adjacent reception peaks in the interference state and the crack depth is determined in advance,
The crack depth measuring method according to claim 1, wherein a pitch of the interference state is obtained, and a crack depth is obtained from the relationship based on the pitch. 超音波探触子を用いて被検体のクラック周辺を走査してクラック深さを測定するクラック深さ測定装置であって、
前記超音波探触子は、中心に孔を有する焦点型の超音波探触子であり、前記被検体表面から反射する表面反射波と前記クラックの先端で回折した回折波とを受波し、
前記走査位置に対応した前記表面反射波と前記回折波との干渉状態の変化をもとに、前記クラック深さを測定する測定手段を備えたことを特徴とするクラック深さの測定装置。 A crack depth measuring device that measures the crack depth by scanning the periphery of a crack of an object using an ultrasonic probe,
The ultrasonic probe is a focal type ultrasonic probe having a hole in the center, and receives a surface reflected wave reflected from the subject surface and a diffracted wave diffracted at the tip of the crack,
An apparatus for measuring a crack depth, comprising: measuring means for measuring the crack depth based on a change in an interference state between the surface reflected wave and the diffracted wave corresponding to the scanning position. 前記測定手段は、前記超音波探触子が発する超音波の波長毎に、前記干渉状態における隣接する受信ピーク間のピッチとクラック深さとの関係を予め求めておき、測定時に、前記干渉状態のピッチを求め、該ピッチをもとに前記関係からクラック深さを求めることを特徴とする請求項３に記載のクラック深さの測定装置。   The measurement means obtains in advance a relationship between a pitch between adjacent reception peaks in the interference state and a crack depth for each wavelength of the ultrasonic wave emitted by the ultrasonic probe, and at the time of measurement, the interference state 4. The crack depth measuring apparatus according to claim 3, wherein a pitch is obtained, and a crack depth is obtained from the relationship based on the pitch.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103543208A (en) * 2013-10-24 2014-01-29 大连理工大学 Method for reducing near surface blind region in TOFD (Time of Flight Diffraction) detection based on spectral analysis principle

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103543208A (en) * 2013-10-24 2014-01-29 大连理工大学 Method for reducing near surface blind region in TOFD (Time of Flight Diffraction) detection based on spectral analysis principle
CN103543208B (en) * 2013-10-24 2015-07-08 大连理工大学 Method for reducing near surface blind region in TOFD (Time of Flight Diffraction) detection based on spectral analysis principle

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