JPS63311103A - Thickness measurement - Google Patents
Thickness measurementInfo
- Publication number
- JPS63311103A JPS63311103A JP14736387A JP14736387A JPS63311103A JP S63311103 A JPS63311103 A JP S63311103A JP 14736387 A JP14736387 A JP 14736387A JP 14736387 A JP14736387 A JP 14736387A JP S63311103 A JPS63311103 A JP S63311103A
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- thickness
- frequencies
- measured
- inspected
- 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.)
- Pending
Links
- 238000005259 measurement Methods 0.000 title description 15
- 230000035515 penetration Effects 0.000 claims abstract description 10
- 238000000034 method Methods 0.000 claims description 18
- 239000000463 material Substances 0.000 abstract description 13
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000007689 inspection Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000006903 response to temperature Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Landscapes
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は例えばライナ管のライナ厚さ又は鋼管の肉厚等
、被検査材の層厚又は肉厚を測定する方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the layer thickness or wall thickness of a material to be inspected, such as the liner thickness of a liner pipe or the wall thickness of a steel pipe.
ライナ管のライナ厚さを非破壊的に測定する方法の一種
に渦電流法によるものが開発されている（例えば特開昭
５９−６７４０５号公報等）。これは交流を印加したコ
イルのインピーダンス変化を検出することによってライ
ナ厚を測定するものであり、このインピーダンスを変化
させる外乱要因に被検査材の温度変化がある。An eddy current method has been developed as a method for non-destructively measuring the liner thickness of a liner tube (for example, Japanese Patent Laid-Open No. 59-67405). This measures the liner thickness by detecting changes in the impedance of a coil to which alternating current is applied, and a disturbance factor that changes this impedance is a change in temperature of the material to be inspected.
このため従来は一定時間毎、又は計測毎に基準管を用い
て較正をしたり、又被検査材及び装置全体を含む恒温室
を設けること等によって温度変化による誤差を補償して
いる。For this reason, conventionally, errors due to temperature changes have been compensated for by calibrating using a reference tube at regular intervals or every measurement, or by providing a constant temperature room containing the material to be inspected and the entire apparatus.
ところで上述の方法において、基準管を用いる較正は基
準管計測のために計測装置を一時停止させるか、または
被検査材の搬送ライン中に割り込ませる等の必要があり
、検査効率の低下を招く。However, in the above-mentioned method, calibration using a reference tube requires that the measuring device be temporarily stopped or inserted into the conveyance line of the material to be inspected in order to measure the reference tube, resulting in a decrease in inspection efficiency.
また短尺基準管を計測装置中に設けて計測の都度、較正
が行われる基準管較正法では基準管計測自体の再現性に
影響されるため純粋に温度変化に対する正確な較正が行
われない虞れかある。In addition, in the reference tube calibration method, in which a short reference tube is installed in the measuring device and calibration is performed each time a measurement is made, accurate calibration for purely temperature changes may not be possible because it is affected by the reproducibility of the reference tube measurement itself. There is.
そして恒温室を設ける手段は被検査材の温度が恒温室内
の温度になる迄の時間が材質によって異なり、長時間を
要するものは保管スペースを必要とし、それに関わるハ
ンドリング作業が繁雑になるとともに多大のコストがか
かるという問題がある。The method of setting up a constant temperature room is that the time it takes for the temperature of the material to reach the temperature inside the constant temperature room varies depending on the material, and items that require a long time require storage space, making the handling work involved complicated and requiring a large amount of work. There is a problem in that it is costly.
本発明は斯かる事情に鑑みてなされたものであり、渦電
流浸透深さが異なる２周波の計測値が被検査材の温度変
化に対して、相異なる変化量を示すことを利用し、被検
査材の温度を推定し、計測値を補正することにより正確
に被検査材の厚さを測定する厚さ測定方法の提供を目的
とする。The present invention has been made in view of the above circumstances, and utilizes the fact that the measured values of two frequencies with different eddy current penetration depths show different amounts of change in response to temperature changes in the inspected material. The present invention aims to provide a thickness measuring method that accurately measures the thickness of a material to be inspected by estimating the temperature of the material to be inspected and correcting the measured value.
本発明に係る厚さ測定方法は、被検査物の厚さを渦電流
法により計測する方法において、その渦電流浸透深さが
測定すべき厚さに基づいて関連付けてある第１の周波数
と、該第１の周波数と異なる第２の周波数とを用いて夫
々厚さを計測し、各計測値の差より被検査物の温度を推
定し、その結果に基づいて前記第１の周波数の計測値を
補正し、厚さを求めることを特徴とする。A thickness measuring method according to the present invention is a method of measuring the thickness of an object to be inspected by an eddy current method, and includes: a first frequency whose eddy current penetration depth is associated based on the thickness to be measured; The thickness is measured using the first frequency and a second frequency different from each other, the temperature of the object to be inspected is estimated from the difference between the measured values, and the measured value of the first frequency is estimated based on the result. It is characterized by correcting and determining the thickness.
渦電流浸透深さが測定すべき厚さに基づいて関連付けて
ある第１の周波数の計測値とこの周波数と異なる第２の
周波数の計測値との差から被検査物の温度が推定され、
その結果に基づいて第１の周波数の計測値は補正され、
厚さが求められる。The temperature of the object to be inspected is estimated from the difference between a measured value of a first frequency, the eddy current penetration depth of which is associated based on the thickness to be measured, and a measured value of a second frequency different from this frequency;
The measured value of the first frequency is corrected based on the result,
Thickness is required.
以下、本発明をその実施例を示す図面に基づき具体的に
説明する。第１図は本発明の実施状態を示すブロック図
である。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof. FIG. 1 is a block diagram showing an implementation state of the present invention.
発振器１は被検査物であるライナ管８内に挿入されたセ
ンサコイル６に印加する交流電流源であり、この出力は
高周波分周器２及び低周波分周器３へ入力されている。An oscillator 1 is an alternating current source that applies to a sensor coil 6 inserted into a liner tube 8 that is an object to be inspected, and its output is input to a high frequency frequency divider 2 and a low frequency frequency divider 3.
高周波分周器２は計測するライナ管８のライナ層８１の
厚さに基づき関連付けられた周波数Ｆ１が、また低周波
分周器３は前記周波数Ｆ１と異なる周波数Ｆ２が夫々出
力されるように発振器１の出力が位相同期して分周され
る。The high frequency divider 2 outputs a frequency F1 associated with the thickness of the liner layer 81 of the liner tube 8 to be measured, and the low frequency divider 3 outputs a frequency F2 different from the frequency F1. 1 output is frequency-divided in phase synchronization.
前記周波数Ｆ１は渦電流浸透深さがライナ層８Ｉの凡そ
の厚さの２〜３倍になるように設定するのが良好である
ことが実測データより得られており、これは浸透深さδ
が
と比例関係にあることを利用して周波数ｆ、つまりＦ、
を決定することができる。周波数Ｆ２はこのＦ、と異な
る周波数値であり、本実施例においては低周波分周器３
を用いることによってＦｌよりも低周波側に周波数を設
定している。It has been obtained from actual measurement data that it is best to set the frequency F1 so that the eddy current penetration depth is 2 to 3 times the approximate thickness of the liner layer 8I, and this is determined by the penetration depth δ.
Using the fact that is proportional to the frequency f, that is, F,
can be determined. The frequency F2 is a frequency value different from this F, and in this embodiment, the low frequency divider 3
By using , the frequency is set on the lower frequency side than Fl.
高周波分周器２及び低周波分周器３は共にミキサー回路
４に接続されており、これにより各周波数Ｆ１とＦ２と
が重畳されその信号は計測部５へ送られる。計測部５は
前記センサコイル６に接続されており、周波数Ｆ１及び
Ｆ２の重畳信号をセンサコイル６へ与える。計測部５は
周波数Ｆ１及びＦ２の夫々を通過周波数とするバンドパ
スフィルタ、ブリッジ回路及び同期検波回路（共に図示
せず）の組合わせからなり、各周波数Ｆ１及びＦ２にお
けるセンサコイル６のインピーダンスの計測値Ｔ（Ｆ、
）及びＴ（Ｆ２）を求めてこれを出力する。Both the high frequency frequency divider 2 and the low frequency frequency divider 3 are connected to a mixer circuit 4, whereby the respective frequencies F1 and F2 are superimposed and the resulting signal is sent to the measurement section 5. The measuring section 5 is connected to the sensor coil 6, and provides the sensor coil 6 with superimposed signals of frequencies F1 and F2. The measurement unit 5 is composed of a combination of a bandpass filter, a bridge circuit, and a synchronous detection circuit (both not shown) that pass frequencies F1 and F2, respectively, and measures the impedance of the sensor coil 6 at each frequency F1 and F2. The value T(F,
) and T(F2) and output them.
計測部５から出力される計測値”ｒ（ｐ、）及びＴ（Ｆ
２）の出力信号は演算部７へ入力され次に示す演算処理
が行われ、計測値Ｔ（Ｆｌ）が補正され、正確な厚さと
して出力される。The measured values “r(p,) and T(F
The output signal of 2) is input to the calculation section 7, where the following calculation processing is performed, and the measured value T (Fl) is corrected and output as an accurate thickness.
第２図は計測部５によって検出される計測値と被検査物
の温度との関係を示すグラフの一例であり、横軸は温度
（’Ｃ）を、縦軸は計測値（μｍ）を夫々示している。FIG. 2 is an example of a graph showing the relationship between the measured value detected by the measurement unit 5 and the temperature of the object to be inspected, where the horizontal axis represents the temperature ('C) and the vertical axis represents the measured value (μm). It shows.
高周波の計測値Ｔ（Ｆｌ）及び低周波の計測値Ｔ（Ｆ２
）は共に温度ｔ。においで予め断面顕微鏡観察など他の
手段によって測定された基準管のライナ厚さＭｏに較正
されており、温度を変化させることにより各温度に対応
した計測値が求められている。High frequency measurement value T (Fl) and low frequency measurement value T (F2
) are both at temperature t. The liner thickness Mo of the reference tube is calibrated in advance by odor and measured by other means such as cross-sectional microscopic observation, and measured values corresponding to each temperature are obtained by changing the temperature.
このグラフにおいて低周波の計測値Ｔ （Ｆ２）の方が
Ｔ（Ｆｌ）よりも温度に対する計測値の変化量が多いの
は、渦電流浸透深さがＴ（Ｆ、）よりも深く、母材層８
２に深く達しているため、ライナ厚測定の感度が高くな
り母材層８２の抵抗変化の影響を大きく受けるためであ
る。一方、高周波信号Ｔ（Ｆｌ）は低周波信号Ｔ （Ｆ
、）よりも周波数が高いため、温度に対する影響は比較
的小さいものの、高周波単独で計測を行うと誤差が生じ
る。このため、周波数の異なる２周波の計測値から計測
時の被検査物の温度を推定することにより、その温度と
較正時の温度ｔ。との関係から計測値を補正することが
可能である。In this graph, the low-frequency measured value T (F2) has a larger change in measured value with respect to temperature than T (Fl) because the eddy current penetration depth is deeper than T (F,) and the base material layer 8
2, the sensitivity of liner thickness measurement increases and is greatly influenced by resistance changes of the base material layer 82. On the other hand, the high frequency signal T (Fl) is the low frequency signal T (F
, ), so the effect on temperature is relatively small, but an error will occur if the high frequency is used alone for measurement. Therefore, by estimating the temperature of the object to be inspected at the time of measurement from the measured values of two different frequencies, the temperature and the temperature t at the time of calibration can be calculated. It is possible to correct the measured value from the relationship.
第３図はその説明図であり、まず予めライナ厚さＭ。の
基準管を用いて前述の如く設定された２周波数Ｆ１及び
Ｆ２による較正を温度ｔ０において行っておき、複数の
実測データより被検査物の温度と各周波数Ｆ、及びＦ２
の計測値との関係直線Ｔ（Ｆｌ）及びＴ （Ｆ２）を作
成しておく。FIG. 3 is an explanatory diagram of this. First, the liner thickness M is determined in advance. Calibration is performed at the temperature t0 using the two frequencies F1 and F2 set as described above using the reference tube of
The relationship straight lines T (Fl) and T (F2) with the measured values of are created in advance.
そして計測部５によって出力された計測値が図のＭ（Ｆ
２）及びＭ（Ｆｌ）であったとすると次式によって被検
査物の温度ｔを求める。Then, the measurement value outputted by the measurement unit 5 is M (F
2) and M(Fl), the temperature t of the object to be inspected is determined by the following equation.
１＝１ｏ＋α（Ｍ （Ｆ２） −Ｍ （Ｆ、）１ここで
ｔｏは前述した較正時の温度、αは関係直線Ｔ（Ｆｌ）
の傾きとＴ（Ｆ２）の傾きとの差より求まる定数である
。1=1o+α(M (F2) −M (F,)1 where to is the temperature at the time of calibration mentioned above, α is the relational straight line T(Fl)
It is a constant determined from the difference between the slope of T(F2) and the slope of T(F2).
ｔが求まると次式により温度補正量Δｔを求めΔを一β
（ｔＯ−ｔ）
ここで定数βは関係直線Ｔ（Ｆｌ）の傾きである。Once t is determined, calculate the temperature correction amount Δt using the following formula and divide Δ by β.
(tO−t) Here, the constant β is the slope of the relational straight line T(Fl).
Δｔが求まるとこれを用いて計測値Ｍ（Ｆ、）を次式に
よって補正し、ライナ厚Ｔを求める。Once Δt is determined, the measured value M(F,) is corrected using the following equation to determine the liner thickness T.
Ｔ＝Ｍ（Ｆｌ）＋Δｔ
なお、本実施例においてはライナ厚を計測する構成とし
ているが、例えばライニングされていない被検査管の肉
厚を測定することも可能であり、この場合は第１の周波
数を渦電流の浸透深さが凡その肉厚と等しくなるように
設定し、第２の周波数をその第１の周波数よりも高周波
側に設定することにより同様に第１の周波数による計測
値を補正することにより厚さが求まる。T=M(Fl)+Δt Note that in this example, the liner thickness is measured, but for example, it is also possible to measure the wall thickness of an unlined pipe to be inspected; in this case, the first By setting the frequency so that the penetration depth of the eddy current is approximately equal to the wall thickness, and setting the second frequency to a higher frequency side than the first frequency, the measured value at the first frequency can be similarly obtained. The thickness is determined by correction.
この様に本発明では計測対象に合わせて適正な周波数を
選択することで精度良く材料の温度補正を行うことがで
きる。As described above, in the present invention, temperature correction of the material can be performed with high accuracy by selecting an appropriate frequency according to the object to be measured.
加えて本実施例においてミキサー回路は重畳方式のもの
を用いているが、これに代えて第１及び第２の周波数を
交互に切換えて印加する方式としても良い。In addition, in this embodiment, the mixer circuit uses a superimposition type mixer circuit, but instead of this, a type in which the first and second frequencies are alternately switched and applied may be used.
以上の如く、本発明方法においては、第１．第２の２週
波による計測値の差より予め求めておいた較正時の２周
波の温度と計測値との関係に基づいて第１の周波数の計
測値を補正するので温度変化に関係なく、常に正確な厚
みが得られ、基準管による較正を度々行う必要もなく、
恒温室を設ける必要もない。このため検査効率の低下を
招くこともなく、設備コストも高くならない。更に本発
明方法においては例えば製造直後の長尺の被検査物の途
中で温度変化がある場合の計測等には不可欠な技術であ
り非常に有効である等、本発明方法は優れた効果を奏す
る。As mentioned above, in the method of the present invention, the first. The measured value of the first frequency is corrected based on the relationship between the measured value and the temperature of the two frequencies at the time of calibration, which is determined in advance from the difference in the measured value of the second two-week wave. Accurate thickness can be obtained without the need for frequent calibration with reference tubes.
There is no need to set up a constant temperature room. Therefore, there is no reduction in inspection efficiency, and the equipment cost does not increase. Furthermore, the method of the present invention has excellent effects, such as being an indispensable technique and very effective for, for example, measuring when there is a temperature change in the middle of a long object to be inspected immediately after manufacturing. .
第１図は本発明方法の実施状態を示すブロック図、第２
図は温度と厚みの計測値との関係を示すグラフ、第３図
は補正方法の説明図である。
１・・・発振器 ２・・・高周波分周器３・・・低周波
分周器 ５・・・計測部６・・・センサコイル ８・・
・ライナ管特 許 出願人 住友金属工業株式会社代
理人 弁理士 河 野 登 夫λ度
（’Ｃ）
第 ３ 図FIG. 1 is a block diagram showing the implementation state of the method of the present invention, and FIG.
The figure is a graph showing the relationship between temperature and the measured value of thickness, and FIG. 3 is an explanatory diagram of the correction method. 1... Oscillator 2... High frequency divider 3... Low frequency divider 5... Measuring section 6... Sensor coil 8...
・Liner tube patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono Lambda degree ('C) Figure 3
Claims (1)
いて、 その渦電流浸透深さが測定すべき厚さに基 づいて関連付けてある第１の周波数と、該第１の周波数
と異なる第２の周波数とを用いて夫々厚さを計測し、各
計測値の差より被検査物の温度を推定し、その結果に基
づいて前記第１の周波数の計測値を補正し、厚さを求め
ることを特徴とする厚さ測定方法。[Claims] 1. A method for measuring the thickness of an object to be inspected by an eddy current method, comprising: a first frequency whose eddy current penetration depth is associated based on the thickness to be measured; The thickness is measured using the first frequency and a different second frequency, the temperature of the object to be inspected is estimated from the difference between the measured values, and the measured value of the first frequency is corrected based on the result. A thickness measuring method characterized by determining the thickness.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14736387A JPS63311103A (en) | 1987-06-12 | 1987-06-12 | Thickness measurement |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14736387A JPS63311103A (en) | 1987-06-12 | 1987-06-12 | Thickness measurement |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS63311103A true JPS63311103A (en) | 1988-12-19 |
Family
ID=15428512
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14736387A Pending JPS63311103A (en) | 1987-06-12 | 1987-06-12 | Thickness measurement |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63311103A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000037881A3 (en) * | 1998-12-18 | 2000-10-19 | Micro Epsilon Messtechnik | Method for operating an eddy current sensor and eddy current sensor |
| JP2011164110A (en) * | 1999-12-23 | 2011-08-25 | Kla-Tencor Corp | In-situ metalization monitoring using eddy current measurement or optical measurement |
| WO2018031036A1 (en) * | 2016-08-12 | 2018-02-15 | Halliburton Energy Services, Inc. | Remote-field eddy current characterization of pipes |
-
1987
- 1987-06-12 JP JP14736387A patent/JPS63311103A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000037881A3 (en) * | 1998-12-18 | 2000-10-19 | Micro Epsilon Messtechnik | Method for operating an eddy current sensor and eddy current sensor |
| US6479990B2 (en) | 1998-12-18 | 2002-11-12 | Micro-Epsilon Messtechnik Gmbh & Co. Kg | Eddy current sensor for analyzing a test object and method of operating same |
| JP2011164110A (en) * | 1999-12-23 | 2011-08-25 | Kla-Tencor Corp | In-situ metalization monitoring using eddy current measurement or optical measurement |
| WO2018031036A1 (en) * | 2016-08-12 | 2018-02-15 | Halliburton Energy Services, Inc. | Remote-field eddy current characterization of pipes |
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