JP2560787B2 - Ultrasonic flaw detection method - Google Patents
Ultrasonic flaw detection methodInfo
- Publication number
- JP2560787B2 JP2560787B2 JP63159704A JP15970488A JP2560787B2 JP 2560787 B2 JP2560787 B2 JP 2560787B2 JP 63159704 A JP63159704 A JP 63159704A JP 15970488 A JP15970488 A JP 15970488A JP 2560787 B2 JP2560787 B2 JP 2560787B2
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- signal
- flaw detection
- detecting
- probe
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/044—Internal reflections (echoes), e.g. on walls or defects
Landscapes
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Description
【発明の詳細な説明】 ［産業上の利用分野］ この発明は、超音波を用いて被検材内の欠陥を検出す
る超音波探傷方式に係わり、特に欠陥の位置検出におけ
る距離分解能の向上に関するものである。Description: TECHNICAL FIELD The present invention relates to an ultrasonic flaw detection method for detecting defects in a material to be inspected using ultrasonic waves, and particularly to improvement of distance resolution in defect position detection. It is a thing.
［従来の技術］ 従来のこの種の超音波探傷方式は、振動継続時間の短
い超音波パルスを被検材内に照射し、欠陥で反射し戻っ
てくる反射エコーを受信して欠陥の有無や欠陥の位置を
検出するという，いわゆるパルスエコー法を用いたもの
である。[Prior Art] A conventional ultrasonic flaw detection method of this type irradiates an ultrasonic pulse having a short vibration duration into a test material and receives a reflection echo that is reflected by a defect and returns to detect the presence or absence of a defect. The so-called pulse echo method, which is to detect the position of a defect, is used.
例えば第３図は、丹羽 登著「超音波計測」，昭和57
年３月25日発行，発行所昭晃堂,p67から引用した従来の
この種の超音波探傷方式を示す図である。第３図（ａ）
において、１は被検材であり、２は被検材１内の欠陥で
ある。３は電気信号と超音波との変換を行う探触子、４
はパルス送信器、５は受信器、６は指示装置である。第
３図（ｂ）は指示装置６のCRT上に表示されるエコー信
号の様子を示す図であり、記号Ｔを付して示している信
号は送信パルス、記号Ｆを付した信号は欠陥２からの反
射エコー、記号Ｂを付した信号は被検材１の底面からの
反射エコーである。これらの信号は全て受信器５で包絡
線を検出して表示された信号である。For example, Figure 3 shows Noboru Niwa, "Ultrasonic measurement", Showa 57.
It is a figure which shows the conventional ultrasonic flaw detection system of this kind quoted from Shokodo Publishing Co., Ltd., p. Fig. 3 (a)
In the above, 1 is a material to be inspected, and 2 is a defect in the material to be inspected 1. 3 is a probe for converting electric signals into ultrasonic waves, 4
Is a pulse transmitter, 5 is a receiver, and 6 is an indicating device. FIG. 3 (b) is a diagram showing a state of the echo signal displayed on the CRT of the indicating device 6, wherein the signal indicated by the symbol T is the transmission pulse, and the signal indicated by the symbol F is the defect 2 From the bottom surface of the material 1 to be inspected. All of these signals are signals displayed by detecting the envelope with the receiver 5.
従来のこの種の超音波探傷方式では、パルスを送信し
てから欠陥２よりの反射エコーが受信されるまでの時間
を計測することにより、欠陥２の位置を検出していた。
従って、送信パルスの振動継続時間を短くしなければ、
例えば、欠陥２からの反射エコーＦと被検材１の底面か
らの反射エコーＢとが重なり合って分離できない。In the conventional ultrasonic flaw detection method of this type, the position of the defect 2 is detected by measuring the time from the transmission of the pulse to the reception of the reflected echo from the defect 2.
Therefore, unless the oscillation duration of the transmission pulse is shortened,
For example, the reflection echo F from the defect 2 and the reflection echo B from the bottom surface of the test material 1 overlap and cannot be separated.
しかし、送信パルスの振動継続時間を短くしようとし
ても、探触子３が有限な周波数帯域しかもっていないの
で、それには限界がある。一般に、振動継続時間は短く
できても数サイクル以上である。例えば、中心周波数が
2MHzの探触子３を用い、送信パルスの振動継続時間が２
サイクルとすると、振動継続時間は（２サイクル）×
（1/2MHz）＝１μｓとなる。この振動継続時間は、距離
に換算すると、被検材１内における超音波の伝播速度ｖ
が5000m/sのとき、１μｓ×5000m/s＝5mmに対応する。
つまり、欠陥２が被検材１の底面から5mm/2＝2.5mm以上
離れていなければ、両エコーを分離できない。なお、こ
こで２で割っているのは、超音波伝播経路が往復である
ことによる。However, even if an attempt is made to shorten the oscillation continuation time of the transmission pulse, the probe 3 has only a finite frequency band, so there is a limit to that. Generally, the vibration duration is several cycles or more even if it can be shortened. For example, if the center frequency is
Using the 2MHz probe 3, the oscillation pulse duration is 2
If it is a cycle, the vibration duration is (2 cycles) ×
(1/2 MHz) = 1 μs. When this vibration duration is converted into a distance, the propagation velocity v of the ultrasonic wave in the test material 1
Corresponds to 1 μs × 5000 m / s = 5 mm.
That is, both echoes cannot be separated unless the defect 2 is more than 5 mm / 2 = 2.5 mm away from the bottom surface of the test material 1. Note that the reason why it is divided by 2 here is that the ultrasonic wave propagation path is a round trip.
［発明が解決しようとする課題］ すなわち、従来のいわゆるパルスエコー法を用いた超
音波探傷方式では、送信パルスの振動継続時間を短くし
ようとしても限界があるので、距離分解能が悪いという
問題点があった。[Problems to be Solved by the Invention] That is, in the conventional ultrasonic flaw detection method using the so-called pulse echo method, there is a limit even if it is attempted to shorten the oscillation continuation time of the transmission pulse. there were.
この発明は上記のような問題点を解消するためになさ
れたもので、距離分解能の優れた超音波探傷方式を提供
することを目的とする。The present invention has been made to solve the above problems, and an object of the present invention is to provide an ultrasonic flaw detection method having excellent distance resolution.
［課題を解決するための手段］ この発明に係る超音波探傷方式は、連続的な送信信号
を探触子に送出するとともにその周波数の可変走査が可
能な周波数可変送信手段と、探触子で受信された信号を
２乗する演算手段と、２乗して得られた信号の直流成分
を検出する直流成分検出手段と、検出した信号を走査周
波数の関数として記憶する記憶手段と、記憶した信号の
周期を周波数走査範囲の周波数合成処理により検出する
周期検出手段とを備え、検出された周期より被検材内の
欠陥の位置を検出するようにしたものである。[Means for Solving the Problems] The ultrasonic flaw detection method according to the present invention includes a frequency variable transmission means capable of transmitting a continuous transmission signal to the probe and variably scanning its frequency, and a probe. Arithmetic means for squaring the received signal, DC component detecting means for detecting the DC component of the signal obtained by squaring, storage means for storing the detected signal as a function of scanning frequency, and stored signal And a cycle detecting means for detecting the cycle of (3) by frequency synthesis processing in the frequency scanning range, and the position of the defect in the test material is detected from the detected cycle.
［作用］ この発明においては、連続波あるいはほとんど連続波
とみなして良い程度に長い振動継続時間を有するパルス
を送受信し、送信信号の周波数を逐次走査して得られる
受信信号を２乗し、２乗して得られた信号の直流成分を
検出して走査周波数の関数として記憶する。周波数の走
査範囲にわたって取り込まれたこの信号に周波数合成処
理を施すことにより、その周期を検出することができ、
この周期より被検材内の欠陥の位置を検出できるので、
従来のパルスエコー法のような限界がなくなり、距離分
解能が向上する。[Operation] In the present invention, a pulse having a vibration duration that is long enough to be regarded as a continuous wave or an almost continuous wave is transmitted / received, and the received signal obtained by sequentially scanning the frequency of the transmitted signal is squared to obtain 2 The DC component of the signal obtained by multiplication is detected and stored as a function of the scanning frequency. By subjecting this signal captured over the scanning range of frequencies to frequency synthesis processing, the period can be detected,
Since the position of the defect in the test material can be detected from this cycle,
The limitations of the conventional pulse echo method are eliminated, and the range resolution is improved.
［実施例］ 以下、この発明の一実施例を図について説明する。[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.
第１図はこの発明による超音波探傷方式の一実施例を
示す構成図である。図において、１は被検材、２は欠
陥、３は探触込、６は指示装置であり、これらは従来の
ものと同様なものである。７は周波数可変送信器であ
り、連続波あるいは連続波とみなしてさしつかえないほ
どの振動継続時間を有するパルスを探触子３に送信で
き、かつ周波数を走査して可変できるものである。８は
信号処理装置であり、探触子３で受信された信号を２乗
する演算手段8aと、２乗して得られた信号の直流成分を
検出する直流成分検出手段8bと、検出した信号を走査周
波数の関数として記憶する記憶手段8cと、記憶した信号
の周期を周波数走査範囲の周波数合成処理により検出す
る周期検出手段8dとを有するもので、パーソナルコンピ
ュータ等で実現できる。FIG. 1 is a block diagram showing an embodiment of the ultrasonic flaw detection system according to the present invention. In the figure, 1 is a material to be inspected, 2 is a defect, 3 is a probe, 6 is an indicating device, and these are the same as the conventional ones. A variable frequency transmitter 7 is capable of transmitting a continuous wave or a pulse having a vibration continuation time which can be regarded as a continuous wave to the probe 3, and is capable of scanning and changing the frequency. Reference numeral 8 denotes a signal processing device, which is a computing unit 8a for squaring the signal received by the probe 3, a DC component detecting unit 8b for detecting the DC component of the signal obtained by squaring, and the detected signal. Which has a storage means 8c for storing as a function of the scanning frequency and a cycle detection means 8d for detecting the cycle of the stored signal by frequency synthesis processing of the frequency scanning range, and can be realized by a personal computer or the like.
以下、本方式による信号処理を詳細に述べる。 The signal processing according to this method will be described in detail below.
送信信号をcos（ωｔ＋θ）とする。ここで、ωは角
周波数,tは時間，θは固定位相角である。一方、欠陥２
における超音波の反射率をａで，被検材１の底面におけ
る超音波の反射率をＡで表わし、被検材１の厚さをＬと
し，被検材１底面と欠陥２との間の距離をｌとする。ま
た、超音波の伝播速度をｖとし、Ｔ＝L/v,τ＝l/vとお
く。The transmission signal is cos (ωt + θ). Here, ω is the angular frequency, t is the time, and θ is the fixed phase angle. On the other hand, defect 2
Let a be the reflectance of the ultrasonic wave at, and A be the reflectance of the ultrasonic wave at the bottom surface of the test material 1, and let L be the thickness of the test material 1. Let the distance be l. Further, let v be the propagation velocity of ultrasonic waves, and T = L / v and τ = 1 / v.
さて、探触子３から送信された信号は、欠陥２及び被
検材１底面で反射され、それぞれ時間２（Ｔ−τ）,2T
だけ遅れて探触子３で受信される。従って、受信信号を
Ｓ（ｔ）とすると、 Ｓ（ｔ）＝a cos｛ω［ｔ−２（Ｔ−τ）］＋θ｝ ＋Acos｛ω（ｔ−2T）＋θ） と表わされる。このＳ（ｔ）を２乗する。三角関数の積
を和に変換する公式を利用して、２乗した後の信号を整
理すると、 S2（ｔ）＝［A2/2＋a2/2＋Aa cos（２ωτ）］ ＋［A2cos（２ωｔ−４ωＴ＋２θ）/2 ＋a2cos（２ωｔ−４ωＴ＋４ωτ＋２θ）/2 ＋Aa cos（２ωｔ−４ωＴ＋２ωτ＋２θ）］ となる。この式において、［］で括った第１項目は時間
的に変化しない直流成分であり、第２項目は角周波数２
ωで変化する交流成分である。この２乗した信号を、角
周波数２ω成分をカットし，直流成分を通過させる低域
通過フィルタに通すと、［］で括った第１項目の直流成
分が取り出される。これをｒで表わす。つまり、 ｒ＝A2/2＋a2/2＋Aa cos（２ωτ） このｒを送信周波数とともに記憶する。以上の処理を周
波数可変送信器７の送信周波数を逐次走査しながら信号
処理装置８で繰返し行う。すなわち、ｒはωの関数とし
て記憶されることになる。Now, the signal transmitted from the probe 3 is reflected by the defect 2 and the bottom surface of the material 1 to be inspected, and the time 2 (T-τ), 2T, respectively.
It is received by the probe 3 after a delay. Therefore, when the received signal is S (t), it is expressed as S (t) = a cos {ω [t-2 (T−τ)] + θ} + Acos {ω (t−2T) + θ). This S (t) is squared. Using the formula for converting the product of trigonometric functions in sum, and rearranging the signal after squared, S 2 (t) = [ A 2/2 + a 2/2 + Aa cos (2ωτ)] + [A 2 cos ( 2ωt−4ωT + 2θ) / 2 + a 2 cos (2ωt−4ωT + 4ωτ + 2θ) / 2 + Aa cos (2ωt−4ωT + 2ωτ + 2θ)]. In this equation, the first item enclosed in [] is the DC component that does not change with time, and the second item is the angular frequency 2
It is an AC component that changes with ω. When this squared signal is passed through a low-pass filter that cuts the angular frequency 2ω component and passes the DC component, the DC component of the first item enclosed in [] is extracted. This is represented by r. That, r = A 2/2 + a 2/2 + Aa cos (2ωτ) stored with the transmission frequency of the r. The above processing is repeated in the signal processing device 8 while sequentially scanning the transmission frequency of the variable frequency transmitter 7. That is, r will be stored as a function of ω.
次に信号処理装置８で以下の処理を行う。上記により
記憶された信号ｒを縦軸にとり，角周波数ωを横軸にと
って描いてみると、これは、第２図（ａ）に示すよう
に、ωとともに変化しない直流成分［A2/2＋a2/2］と、
ωとともに変化する交流成分Aa cos（２ωτ）との和に
なっている。交流成分の周期は、２ωτ＝２πとおいて
ωを求めることにより、ω＝π／τとなる。従って、ｒ
の周期を求めることによりτを求めることができる。つ
まり、超音波の伝播速度ｖと以上のようにして求めたτ
とから、被検材１底面と欠陥２との間の距離ｌをｌ＝ｖ
τから求められる。Next, the signal processing device 8 performs the following processing. Placed vertically signal r stored by said, looking painted angular frequency omega abscissa, which, as shown in FIG. 2 (a), a DC component which does not vary with ω [A 2/2 + a 2 / 2],
It is the sum of the AC component Aa cos (2ωτ) that changes with ω. The period of the AC component becomes ω = π / τ by determining ω with 2ωτ = 2π. Therefore, r
Τ can be obtained by obtaining the period of. That is, the ultrasonic wave propagation velocity v and τ obtained as described above
From, the distance l between the bottom surface of the material to be inspected 1 and the defect 2 can be calculated as l = v
Calculated from τ.
ｒの周期を検出するには、例えば、次のようなスペク
トル解析を行えばよい。先ず、ｒから直流成分［A2/2＋
a2/2］を引きさる。つまり、次の処理を行う。In order to detect the period of r, for example, the following spectrum analysis may be performed. First, the DC component from the r [A 2/2 +
leave draw a 2/2]. That is, the following processing is performed.
ｒ′＝ｒ−（A2/2＋a2/2） ＝Aa cos（２ωτ） このようにして得られたｒ′をスペクトル解析する。
角周波数の走査範囲を０〜Ωとする。負の周波数は実際
にはあり得ないが、解析の都合上,r′（−ω）＝ｒ′
（ω）として負の周波数範囲におけるｒ′を与える。そ
の後、ｒ′をフーリエ変換する。つまり、次式 の演算をｐを変化させながら行う。これは周波数合成処
理を行っていることに対応する。上式の右辺の定積分を
行うと、 が得られる。これを図示すると、第２図（ｂ）に示すも
のとなる。Ｈ（ｐ）の絶対値|H（ｐ）｜の相対値，つま
り|H（ｐ）|/（AaΩ）を図示している。第２図（ｂ）か
ら、|H（ｐ）｜が最大となるｐの値を読み取ればこれは
２τに等しいから、読み取ったｐの値からτを求めるこ
とができることがわかる。 r '= r- (A 2/ 2 + a 2/2) = Aa cos (2ωτ) was r obtained in this way' spectrum analyzing.
The scanning range of the angular frequency is 0 to Ω. Negative frequency is impossible in reality, but r '(-ω) = r' for the convenience of analysis.
R'in the negative frequency range is given as (ω). Then, r ′ is Fourier transformed. That is, Is performed while changing p. This corresponds to performing frequency synthesis processing. If you perform definite integration on the right side of the above equation, Is obtained. This is shown in FIG. 2 (b). The relative value of absolute value | H (p) | of H (p), that is, | H (p) | / (AaΩ) is illustrated. From FIG. 2 (b), it can be seen that if the value of p at which | H (p) | becomes maximum is read, this is equal to 2τ, so that τ can be obtained from the read value of p.
以上は、説明を簡単にするため、探触子３の送受信感
度の周波数特性が周波数に依らず一定であるとして信号
処理手順を示したが、探触子３の周波数特性を無視でき
ない場合には、送受信総合感度の周波数特性を予め測定
しておき、これを用いて受信信号Ｓ（ｔ）のレベルを補
正すればよい。つまり、探触子３の送受信総合感度の周
波数特性をＴ（ω）とすれば、Ｓ（ｔ）の代わりにＳ
（ｔ）をＴ（ω）で割ったものを用いればよい。For the sake of simplicity, the signal processing procedure has been described above assuming that the frequency characteristic of the transmission / reception sensitivity of the probe 3 is constant regardless of the frequency. However, when the frequency characteristic of the probe 3 cannot be ignored, The frequency characteristic of the total transmission / reception sensitivity may be measured in advance, and the level of the received signal S (t) may be corrected using this. That is, if the frequency characteristic of the total transmission / reception sensitivity of the probe 3 is T (ω), then S (t) is replaced by S (t).
A value obtained by dividing (t) by T (ω) may be used.
さて、この発明に係る超音波探傷方式を従来のパルス
エコー法を用いた探傷方式と比較してみる。第２図
（ａ）を用いて示したように、この発明に係る超音波探
傷方式では、ｒの周期を検出することにより欠陥２の位
置を検出しようとしている。例えば、2MHzまで周波数を
走査した場合を考える。角周波数に直すと、２π×2MHz
＝４π（rad）×106Hzである。第２図（ａ）において、
横軸の角周波数ωが０〜４π（rad）×106Hzの間に、ｒ
の交流成分が１周期入れば周期を読み取れる。１周期は
π／τであるから、π／τ＝４π×106とおくことによ
りτ＝0.25μｓとなる。これは、距離に換算してｌ＝ｖ
×τ＝5000m/s×0.25μｓ＝1.25mmとなる。すなわち、
前記した従来の距離分解能2.5mmの半分である。なお、
いうまでもなく、周波数走査範囲を広くすればする程、
距離分解能や精度が向上すことは明らかである。Now, the ultrasonic flaw detection method according to the present invention will be compared with the conventional flaw detection method using the pulse echo method. As shown in FIG. 2A, the ultrasonic flaw detection system according to the present invention attempts to detect the position of the defect 2 by detecting the cycle of r. For example, consider the case where the frequency is scanned up to 2 MHz. Converted to angular frequency, 2π × 2MHz
= 4π (rad) × 10 6 Hz. In FIG. 2 (a),
While the angular frequency ω on the horizontal axis is 0 to 4π (rad) × 10 6 Hz, r
The cycle can be read if the AC component of 1 cycle enters. Since one period is π / τ, by setting π / τ = 4π × 10 6 , τ = 0.25 μs. This is converted to a distance, l = v
× τ = 5000 m / s × 0.25 μs = 1.25 mm. That is,
This is half of the conventional distance resolution of 2.5 mm described above. In addition,
Needless to say, the wider the frequency scanning range,
It is clear that the range resolution and accuracy are improved.
ところで、以上の説明では、被検材１の底面からの反
射波をいわば参照信号として用いたが、この発明はこれ
に限らず、被検材１のコーナーからの反射波など被検材
１の他の部分からの反射波を参照信号として用いてもよ
い。By the way, in the above description, the reflected wave from the bottom surface of the test material 1 is used as a reference signal, but the present invention is not limited to this, and the reflected wave from the corner of the test material 1 such as the reflected wave. You may use the reflected wave from another part as a reference signal.
［発明の効果］ 以上のように、この発明による超音波探傷方式では、
周波数走査して各周波数における被検材からの受信信号
を信号処理することにより欠陥からのデータを収集し、
収集したデータに周波数合成処理を施すことにより欠陥
の位置を検出するようにしたので、従来に比べ距離分解
能を大幅に向上できる効果がある。[Effects of the Invention] As described above, in the ultrasonic flaw detection method according to the present invention,
Collecting data from defects by frequency scanning and signal processing the received signal from the test material at each frequency,
Since the position of the defect is detected by subjecting the collected data to frequency synthesis processing, there is an effect that the distance resolution can be greatly improved compared to the conventional case.
第１図はこの発明による超音波探傷方式の一実施例を示
す構成図、第２図（ａ），（ｂ）は実施例の動作を説明
するための図、第３図（ａ），（ｂ）は従来の超音波探
傷方式を示す図である。 １は被検材、２は欠陥、３は探触子、６は指示装置、７
は周波数可変送信器、８は信号処理装置、8aは演算手
段、8bは直流成分検出手段、8cは記憶手段、8dは周期検
出手段。 なお、図中、同一符号は同一、又は相当部分を示す。FIG. 1 is a block diagram showing an embodiment of the ultrasonic flaw detection method according to the present invention, FIGS. 2 (a) and 2 (b) are diagrams for explaining the operation of the embodiment, and FIGS. 3 (a) and 3 ( (b) is a figure which shows the conventional ultrasonic flaw detection system. 1 is a material to be inspected, 2 is a defect, 3 is a probe, 6 is a pointing device, 7
Is a variable frequency transmitter, 8 is a signal processing device, 8a is a calculating means, 8b is a direct current component detecting means, 8c is a storing means, and 8d is a cycle detecting means. In the drawings, the same reference numerals indicate the same or corresponding parts.
Claims (1)
し，被検材内からの反射超音波を受信して被検材内の欠
陥を検出する超音波探傷方式において、 連続的な送信信号を探触子に送出するとともにその周波
数の可変走査が可能な周波数可変送信手段と、探触子で
受信された信号を２乗する演算手段と、２乗して得られ
た信号の直流成分を検出する直流成分検出手段と、検出
した信号を走査周波数の関数として記憶する記憶手段
と、記憶した信号の周期を周波数走査範囲の周波数合成
処理により検出する周期検出手段とを備え、検出された
周期より被検材内の欠陥の位置を検出するようにしたこ
とを特徴とする超音波探傷方式。1. An ultrasonic flaw detection method for detecting a defect in a test material by transmitting ultrasonic waves into the test material using a probe and receiving reflected ultrasonic waves from the test material. , A variable frequency transmission means capable of sending a continuous transmission signal to the probe and variably scanning the frequency thereof, an arithmetic means for squaring the signal received by the probe, and a squared value. A direct current component detecting means for detecting a direct current component of the signal, a storage means for storing the detected signal as a function of the scanning frequency, and a cycle detecting means for detecting the cycle of the stored signal by frequency synthesis processing of the frequency scanning range. An ultrasonic flaw detection method, characterized in that the position of a defect in a test material is detected based on the detected cycle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63159704A JP2560787B2 (en) | 1988-06-28 | 1988-06-28 | Ultrasonic flaw detection method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63159704A JP2560787B2 (en) | 1988-06-28 | 1988-06-28 | Ultrasonic flaw detection method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0210153A JPH0210153A (en) | 1990-01-12 |
| JP2560787B2 true JP2560787B2 (en) | 1996-12-04 |
Family
ID=15699483
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63159704A Expired - Fee Related JP2560787B2 (en) | 1988-06-28 | 1988-06-28 | Ultrasonic flaw detection method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2560787B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1045718C (en) * | 1995-11-06 | 1999-10-20 | 西安天诚医药生物工程有限公司 | New medical use for cucoline |
| US7317862B2 (en) | 2004-04-13 | 2008-01-08 | Nec Corporation | Mechanism for releasing lock between optical transceiver and cage, optical transceiver, communication apparatus and method of releasing lock between optical transceiver and cage |
| US9153782B2 (en) * | 2011-01-19 | 2015-10-06 | Joled Inc. | Method for producing organic light-emitting element, organic display panel, organic light-emitting device, method for forming functional layer, ink, substrate, organic light-emitting element, organic display device, and inkjet device |
-
1988
- 1988-06-28 JP JP63159704A patent/JP2560787B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0210153A (en) | 1990-01-12 |
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