JP2000009414A - Method for measuring thickness of surface layer - Google Patents
Method for measuring thickness of surface layerInfo
- Publication number
- JP2000009414A JP2000009414A JP10196534A JP19653498A JP2000009414A JP 2000009414 A JP2000009414 A JP 2000009414A JP 10196534 A JP10196534 A JP 10196534A JP 19653498 A JP19653498 A JP 19653498A JP 2000009414 A JP2000009414 A JP 2000009414A
- Authority
- JP
- Japan
- Prior art keywords
- surface layer
- measured
- coil
- thickness
- layer portion
- 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.)
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、鉄材料や非鉄金属
材料などの導電性材料の材質試験、特に断面の材質が層
状構造なす丸棒材について、内部と材質が実質的に異な
る表層の有無および厚さを検出する表層厚さ測定方法に
関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material test for a conductive material such as a ferrous material or a non-ferrous metal material, and particularly to the presence or absence of a surface layer whose material is substantially different from that of the inside of a round bar having a laminar cross-sectional material. And a method for measuring a surface layer thickness for detecting a thickness.
【０００２】[0002]
【従来の技術】鉄鋼など多くの材料では、厚み方向の材
質に関する均質さまたは不均質さは材料全体の機能を決
める重要な因子である。たとえば鉄鋼材料で内部に比べ
て炭素量が著しく少ない表面の脱炭層や逆に炭素量を増
やした浸炭層は、材料強度や弾性特性に大きな影響を及
ぼす。非鉄金属材料の場合も表層と内部層の組成変化は
材料強度や電気伝導度などの材質決定の因子である。ま
た内部層と外部層が異なる物質からなる複合材について
各層の厚さが所望の値になるように制御することが品質
管理上重要である。2. Description of the Related Art In many materials such as steel, the homogeneity or inhomogeneity of a material in a thickness direction is an important factor that determines the function of the whole material. For example, a decarburized layer on the surface of a steel material having a significantly lower amount of carbon than that inside or a carburized layer with an increased amount of carbon has a great effect on the strength and elastic properties of the material. In the case of a non-ferrous metal material as well, the change in the composition of the surface layer and the inner layer is a factor in determining the material such as material strength and electrical conductivity. It is important for quality control to control the thickness of each layer of the composite material in which the inner layer and the outer layer are made of different substances so that the thickness of each layer becomes a desired value.
【０００３】材料断面の半径方向に層状構造をなす組成
変化や金属組織を調べる材質試験として、通常は試料を
切断して切断面を観察することが行われる。たとえば鉄
鋼材料の表面直下の脱炭深さや浸炭深さを調べるには、
試料の切断面を研磨して光学的にみて平坦化した後にナ
イタールなど酸でエッチングし、エッチング面を光学顕
微鏡で組織を観察して測定されている。またエックス線
マイクロアナライザーで切断面の表面組成のマッピング
をして、各層の厚さを調べる方法も一般的に用いられて
いる。これら手法は試料を切断してその断面を観察する
破壊的方法である。非破壊的な方法としては、脱炭測定
として被検材に超音波を伝搬させてその反射エコー高さ
を調べる方法（特開昭５７−９７４４３号公報）や電磁
誘導式に渦電流の大きさ等により検出する方法（特開昭
５３−２６１５６号公報）が知られている。As a material test for examining a composition change or a metal structure forming a layered structure in a radial direction of a material cross section, usually, a sample is cut and a cut surface is observed. For example, to determine the depth of decarburization or carburization just below the surface of a steel material,
The cut surface of the sample is polished and optically flattened, then etched with an acid such as nital, and the etched surface is measured by observing the structure with an optical microscope. A method of mapping the surface composition of the cut surface with an X-ray microanalyzer and examining the thickness of each layer is also generally used. These techniques are destructive methods of cutting a sample and observing its cross section. As a non-destructive method, there is a method of transmitting ultrasonic waves to a test material to measure a reflected echo height as a decarburization measurement (Japanese Patent Laid-Open No. 57-97443) or an electromagnetic induction type eddy current magnitude. (Japanese Patent Application Laid-Open No. 53-26156) is known.
【０００４】[0004]
【発明が解決しようとする課題】通常多くの場合に行わ
れている層の厚さを調べる破壊的方法では、測定用試料
を準備するのに被検材の切断や研磨などに手間と時間を
要し特に被検材の数が多いときには膨大な作業量とな
る。したがって、金属材料の大量生産で品質管理を目的
として表面層厚さをモニターしたいときには、試料数を
多くできないという問題があった。また、破壊検査であ
るために製品に損失がでることも問題であった。前記の
超音波による表面層深さ測定の場合、深さが小さいとき
には測定がむずかしい。また、試料と探触子の間に油等
の液体を充填しなければならず手数がかかる。一方材料
の電磁誘導特性から層の厚さを測定する従来の方法で
は、試験材料の物性値を予め測定したり他の標準試料が
必要であったりして、実際に多種・多数の試験材の試験
を行うのがむずかしかった。従って、本発明は導電性材
料の表層厚さを、非破壊的に短時間でかつ標準試料を用
いずに測定することを課題とする。In a destructive method for checking the thickness of a layer, which is usually performed in many cases, it takes time and effort to cut or polish a test material to prepare a sample for measurement. In other words, it requires a huge amount of work especially when the number of test materials is large. Therefore, when monitoring the thickness of the surface layer for the purpose of quality control in mass production of metal materials, there is a problem that the number of samples cannot be increased. In addition, there is a problem that the product is lost due to the destructive inspection. In the case of the surface layer depth measurement by the above-mentioned ultrasonic wave, the measurement is difficult when the depth is small. Further, a liquid such as oil must be filled between the sample and the probe, which is troublesome. On the other hand, in the conventional method of measuring the thickness of the layer from the electromagnetic induction characteristics of the material, the physical property value of the test material is measured in advance or another standard sample is required. It was difficult to do the test. Accordingly, an object of the present invention is to measure the surface layer thickness of a conductive material nondestructively in a short time and without using a standard sample.
【０００５】[0005]
【課題を解決するための手段】上記の課題を解決するた
めに本発明では非破壊的手法である電磁誘導的方法を用
いる。即ち、本発明の表層厚さ測定方法は、（１）表層
部と内層部からなる被測定物である導電性の棒材や線材
を空心コイルの内部に同心になるように固定し、該コイ
ルに正弦波の電流を供給し、該コイルまたは被測定物を
貫通し該コイルに隣接して設けた別のコイルに発生する
電磁誘導電圧の振幅と前記励磁電流を基準とした位相を
測定し、前記励磁電流の正弦波の周波数を変化させて前
記測定を繰り返し、得られた測定値から被測定物の自己
または相互インダクタンスを算出するとともに、該算出
値と別途用意した表層部と内層部からなる２層モデルの
自己または相互インダクタンスのモデル式を用いて回帰
計算を行い、前記理論計算のパラメータである表層部の
厚みを求める。あるいは、（２）表層部と内層部からな
る被測定物である導電性の棒材や線材を空心コイルの内
部に同心になるように固定し、該コイルに正弦波の励磁
電流を供給し、該コイルまたは被測定物を貫通し該コイ
ルに隣接して設けた別のコイルに発生する電磁誘導電圧
の振幅と前記励磁電流を基準とした位相を測定し、前記
励磁電流の正弦波の周波数を表層部の材質で決まる周波
数以上の範囲で変化させて前記測定を繰り返し、得られ
た測定値から被測定物自己または相互インダクタンスを
算出するとともに、該算出値と別途用意した表層部の材
質からなる単層モデルの自己または相互インダクタンス
のモデル式を用いて回帰計算を行い、前記モデル式のパ
ラメータである表層部の透磁率と電気抵抗率を予め求
め、その後、（１）の方法により表層部の厚みを求め
る。In order to solve the above-mentioned problems, the present invention employs a non-destructive electromagnetic induction method. That is, the surface layer thickness measuring method of the present invention comprises the steps of (1) fixing a conductive rod or wire, which is an object to be measured comprising a surface layer portion and an inner layer portion, concentrically inside an air-core coil; To supply a sinusoidal current, and measure the amplitude of the electromagnetic induction voltage generated in another coil provided adjacent to the coil or the object to be measured and the phase based on the exciting current, The measurement is repeated by changing the frequency of the sine wave of the excitation current, and the self or mutual inductance of the device under test is calculated from the obtained measurement value, and the calculated value and the surface layer portion and the inner layer portion separately prepared A regression calculation is performed using the model formula of the self or mutual inductance of the two-layer model, and the thickness of the surface layer, which is a parameter of the theoretical calculation, is obtained. Alternatively, (2) a conductive rod or wire, which is an object to be measured, consisting of a surface layer portion and an inner layer portion, is fixed concentrically inside the air-core coil, and a sine-wave exciting current is supplied to the coil. The amplitude of the electromagnetic induction voltage generated in another coil provided adjacent to the coil or the object to be measured and penetrating the object to be measured and the phase based on the excitation current are measured, and the frequency of the sine wave of the excitation current is measured. The above measurement is repeated by changing the frequency in a range equal to or higher than the frequency determined by the material of the surface portion, and the measured object self or mutual inductance is calculated from the obtained measured value, and the calculated value and the material of the surface portion separately prepared are used. A regression calculation is performed using the model formula of the self or mutual inductance of the single-layer model, and the magnetic permeability and the electric resistivity of the surface layer, which are parameters of the model formula, are obtained in advance. Determine the thickness of the part.
【０００６】[0006]
【発明の実施の形態】本発明の表層厚さ測定方法の好適
な実施形態について、図１、図２に基づき詳細に説明す
る。本実施形態では、励磁用の空心コイル１ａに励磁用
電気回路で一定振幅のある周波数ｆの交流励磁電流を流
して、試料の長手方向に交流磁界６を印加する。このと
き検出用の空心コイル１ｂに発生する誘導電圧を電圧検
出部３で検出する。なお空心コイル１ａ，１ｂは同心に
配置され、また図３のように同一コイルであっても良
い。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a method for measuring a surface layer thickness according to the present invention will be described in detail with reference to FIGS. In the present embodiment, an AC magnetic field 6 is applied in the longitudinal direction of the sample by flowing an AC exciting current having a certain frequency f with a constant amplitude to the exciting air core coil 1a by an exciting electric circuit. At this time, an induced voltage generated in the detection air core coil 1b is detected by the voltage detection unit 3. The air-core coils 1a and 1b are arranged concentrically, and may be the same coil as shown in FIG.
【０００７】ところで交流磁界が導電性の材料に侵入す
る深さすなわち表皮深さδは、平板の場合には透磁率μ
と導電率σを用いて、By the way, the depth at which the AC magnetic field penetrates the conductive material, that is, the skin depth δ is determined by the permeability μ in the case of a flat plate.
And conductivity σ,
【０００８】[0008]
【数１】 (Equation 1)
【０００９】で表される。周波数が高くなれば表皮深さ
は小さくなり、丸棒でも同様である。したがって図２の
ように試料が内部層９と表層８の二層構造に成っている
ときと、表層の無い内部層単層のときとでは誘導電圧や
インダクタンスの周波数特性は異なる。すなわち誘導電
圧やインダクタンスを多数の周波数で測定すると、表層
厚さおよび各層の透磁率や電気電導率によって一意的に
決まっている周波数特性曲線が得られる。そこで、導電
性試料について、同心にソレノイドコイルを配置して誘
導起電圧または相互インダクタンスまたは自己インダク
タンスの周波数変化を測定する。同時に試料を除いた空
心コイルの状態で同様に測定すれば、実効インダクタン
スを計算できる。## EQU1 ## As the frequency increases, the skin depth decreases, and the same applies to a round bar. Therefore, the frequency characteristics of the induced voltage and the inductance are different between the case where the sample has a two-layer structure of the inner layer 9 and the surface layer 8 as shown in FIG. 2 and the case where the sample is a single layer of the inner layer without the surface layer. That is, when the induced voltage and the inductance are measured at many frequencies, a frequency characteristic curve uniquely determined by the surface layer thickness, the magnetic permeability and the electric conductivity of each layer can be obtained. Therefore, for the conductive sample, a solenoid coil is disposed concentrically, and the induced electromotive voltage or the mutual inductance or the frequency change of the self-inductance is measured. At the same time, if the same measurement is performed in the state of the air-core coil excluding the sample, the effective inductance can be calculated.
【００１０】一方、理論的に誘導電圧やインダクタンス
を求めるには、丸棒材の断面構造を表層と内部層とする
二層構造モデルを用いる。ある周波数ｆで励磁電流によ
る誘導電圧の理論解Ｖは、外径を既知として内部層の電
気導電率σi 、透磁率μi と表層の電気導電率σ0 、透
磁率μ0 および表層厚さｈの関数としてＶ（ｆ，σi，
μi ，σ0 ，μ0 ，ｈ）と表される。インダクタンスの
理論解Ｌは誘導電圧を励磁電流と角周波数で除して計算
することができて、やはりこれらの変数の関数である。
またインダクタンスＬから試料を除いた空心コイルのイ
ンダクタンスＬ0 を減じた、いわば実効インダクタンス
の理論解Ｌも同様である。On the other hand, in order to theoretically obtain an induced voltage and an inductance, a two-layer structure model having a cross-sectional structure of a round bar as a surface layer and an inner layer is used. The theoretical solution V of the induced voltage due to the excitation current at a certain frequency f is given assuming that the outer diameter is known, the electric conductivity σ i of the inner layer, the magnetic permeability μ i , the electric conductivity σ 0 of the surface layer, the magnetic permeability μ 0 and the surface thickness V (f, σ i ,
μ i , σ 0 , μ 0 , h). The theoretical solution L of the inductance can be calculated by dividing the induced voltage by the exciting current and the angular frequency, and is also a function of these variables.
The same applies to the theoretical solution L of the effective inductance, which is the inductance L minus the inductance L 0 of the air-core coil excluding the sample.
【００１１】二層構造の試料についてある周波数での誘
導電圧の理論解としては、尾上守夫（“導体に近接した
有限長ソレノイドコイルの解析”、電気学会雑誌、vol.
88-10、162頁（1968））によって導かれた解析解を利用
することができる。この解は特殊関数である変形Bessel
関数を含んでおり複雑である。単位電流に対する誘導電
圧解からインピーダンスが導出でき、さらに角周波数で
除してインダクタンスを得ることができる。また、各社
から市販されているコンピュータソフトウエア等で、電
磁場方程式について数値計算で誘導電圧やインダクタン
スの理論解を得ることも可能である。The theoretical solution of the induced voltage at a certain frequency for a sample having a two-layer structure is described by Morio Onoe (“Analysis of a finite length solenoid coil close to a conductor”, Journal of the Institute of Electrical Engineers of Japan, vol.
88-10, p. 162 (1968)). This solution is a special function, the modified Bessel
Complex with functions. The impedance can be derived from the solution of the induced voltage for the unit current, and the inductance can be obtained by dividing by the angular frequency. It is also possible to obtain a theoretical solution of an induced voltage or an inductance by numerical calculation of an electromagnetic field equation using computer software or the like commercially available from each company.
【００１２】ここで、例えば実効インダクタンスの理論
解Ｌが先に求めた測定値と等しいと考えて表層厚さｈを
求めようとしてもσi ，μi ，σ0 ，μ0 が未知であり
不可能である。従って、本発明では、複数の測定値を用
いて回帰計算により表層厚さを決定する。Here, for example, even if it is assumed that the theoretical solution L of the effective inductance is equal to the measured value obtained above and the surface layer thickness h is to be obtained, σ i , μ i , σ 0 , μ 0 are unknown and unacceptable. It is possible. Therefore, in the present invention, the surface layer thickness is determined by regression calculation using a plurality of measured values.
【００１３】各層の透磁率、電気抵抗率や表層厚さを決
定するために、測定値を用いて以下のような回帰分析を
行う。回帰分析は誘導電圧またはインダクタンスのどち
らについても可能であるが、実効インダクタンスＬ
1 （ｆ，σi ，μi ，σ0 ，μ0，ｈ）を例にして説明
する。In order to determine the magnetic permeability, electric resistivity and surface layer thickness of each layer, the following regression analysis is performed using the measured values. Regression analysis is possible for either the induced voltage or the inductance, but the effective inductance L
1 (f, σ i , μ i , σ 0 , μ 0 , h) will be described as an example.
【００１４】さて、実際に表層厚さなどを求める手続き
を図４のフローチャートを用いて説明する。まず実効イ
ンダクタンスを周波数ｆ1 ，ｆ2 ，・・・，ｆn で測定
する。次に各層の透磁率、電気抵抗率および表層厚さの
仮の値（初期値）を定めて、実効インダクタンスの理論
値を計算する。そして測定値と理論計算値の差を数値化
する評価関数Ｇを求める。評価関数の例としては、Ｌ1m
を測定値、Ｌ1cを理論計算値として、Now, a procedure for actually obtaining the surface layer thickness and the like will be described with reference to the flowchart of FIG. First, the effective inductance is measured at the frequencies f 1 , f 2 ,..., F n . Next, temporary values (initial values) of the magnetic permeability, electric resistivity, and surface layer thickness of each layer are determined, and the theoretical value of the effective inductance is calculated. Then, an evaluation function G for digitizing the difference between the measured value and the theoretical calculation value is obtained. As an example of the evaluation function, L 1m
Is a measured value, and L 1c is a theoretically calculated value,
【００１５】[0015]
【数２】 (Equation 2)
【００１６】が挙げられる。Ｇが予め設定した許容値ε
以下になるまで、透磁率、電気抵抗率、表層深さを修正
しながら繰り返し計算を実行する。すなわち回帰計算を
行う。こうして各層の透磁率、電気抵抗率とともに表層
厚さを推定することができる。[0016] G is a preset tolerance ε
The calculation is repeatedly performed while correcting the magnetic permeability, the electric resistivity, and the surface depth until the value becomes below. That is, regression calculation is performed. Thus, the surface layer thickness can be estimated together with the magnetic permeability and electric resistivity of each layer.
【００１７】ところで、強磁性体の鋼材では１００ｋＨ
ｚ程度以上の高周波数においては、表皮深さが５０μｍ
程度とごく浅い。従って表皮深さが予想される表層厚さ
の数分の一以下になる高周波数の測定値を用いれば、被
測定物を等価的に表層の物質から成るものとみなすこと
ができ、モデル式の未知パラメータ減らして表層の透磁
率と電気抵抗率を上記の手続きで推定することができ
る。それから、より低周波数側の測定値と先に求めた表
層の透磁率と電気抵抗率から内部層の透磁率、電気抵抗
率と表層厚さを推定することができる。表層厚さがおお
よそ予想できるときには、このように二段階の推定手続
きの方が回帰計算の実行時間が短くすることができる。By the way, in the case of a ferromagnetic steel material, 100 kHz is used.
At high frequencies above z, the skin depth is 50 μm
Very shallow with degree. Therefore, by using a high-frequency measurement value where the skin depth is less than a fraction of the expected surface layer thickness, the measured object can be regarded as equivalently composed of the surface layer material. By reducing the unknown parameters, the magnetic permeability and the electrical resistivity of the surface layer can be estimated by the above procedure. Then, the magnetic permeability, the electric resistivity, and the surface thickness of the inner layer can be estimated from the measured value on the lower frequency side and the magnetic permeability and the electric resistivity of the surface layer previously obtained. When the surface layer thickness can be roughly estimated, the two-step estimation procedure can shorten the execution time of the regression calculation.
【００１８】[0018]
【実施例】以下、図３に基づいて、本発明の具体的な実
施例について説明する。スイープジェネレーターを内蔵
した、高速フーリエ変換（ＦＦＴ）方式の周波数特性測
定器を用いる。スイープジェネレーターによる基準信号
をもとに、励磁用電気回路である定振幅励磁器１０でコ
イル１に一定振幅値の交流電流を流す。コイルに発生す
る誘導電圧を電圧検出部である周波数特性測定器１１で
検出する。なお誘導電圧の基準電流値信号を周波数特性
測定器に供給する（１３）。周波数特性測定器は、周波
数を走査して誘導電圧の振幅と位相の周波数特性を自動
測定し、さらにインピーダンスを計算することができ
る。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment of the present invention will be described with reference to FIG. A fast Fourier transform (FFT) type frequency characteristic measuring instrument having a built-in sweep generator is used. An alternating current having a constant amplitude value is passed through the coil 1 by a constant amplitude exciter 10, which is an electric circuit for excitation, based on a reference signal from the sweep generator. An induced voltage generated in the coil is detected by a frequency characteristic measuring device 11 which is a voltage detecting unit. The reference current value signal of the induced voltage is supplied to the frequency characteristic measuring device (13). The frequency characteristic measuring device can automatically measure the frequency characteristics of the amplitude and phase of the induced voltage by scanning the frequency, and further calculate the impedance.
【００１９】断面が実質的に円形である外径３２ｍｍφ
の丸棒鋼を１０００℃で熱処理して、炭素量が内部より
も著しく少ない表層を有する試料を準備した。この試料
について、５Ｈｚから５０ｋＨｚの周波数帯域でインピ
ーダンスを測定した。この測定値から予め測定しておい
た空心コイルの測定値を減じていわゆる実効インダクタ
ンスを得た（図５）。Outer diameter 32 mmφ whose cross section is substantially circular
Was heat-treated at 1000 ° C. to prepare a sample having a surface layer having a significantly lower carbon content than the inside. The impedance of this sample was measured in a frequency band of 5 Hz to 50 kHz. The so-called effective inductance was obtained by subtracting the previously measured value of the air-core coil from this measured value (FIG. 5).
【００２０】１３点の周波数（16.5,29,50,85,150,260,
455,800,1.4k,2.4k,7k,12.5k,22kHz）での実効インダク
タンス測定値に対して、表層と内部層それぞれの透磁率
・導電率および表層厚さを変数としてパーソナルコンピ
ュータ１４で回帰分析を行った。回帰分析には、Visual
Numerics社製IMSL FORTRAN ライブラリを用いた。図
６にこうして得られた脱炭深さと、試料断面を研磨して
エッチングした後に光学顕微鏡で目視測定した値との相
関を示す。一つの試料当たりに要する時間は数分以内で
あった。高速タイプの演算器を用いれば数十秒以内も可
能である。短時間での簡便な測定にもかかわらず、高精
度で測定することができる。Thirteen frequencies (16.5, 29, 50, 85, 150, 260,
The regression analysis was performed on the measured effective inductance at 455,800,1.4k, 2.4k, 7k, 12.5k, 22kHz) with the personal computer 14 using the magnetic permeability / conductivity of the surface layer and the inner layer and the surface layer thickness as variables. went. For regression analysis, Visual
The IMSL FORTRAN library manufactured by Numerics was used. FIG. 6 shows the correlation between the decarburization depth thus obtained and the value visually measured with an optical microscope after polishing and etching the sample section. The time required for one sample was within several minutes. If a high-speed type arithmetic unit is used, it can be performed within several tens of seconds. Despite simple measurement in a short time, measurement can be performed with high accuracy.
【００２１】[0021]
【発明の効果】本発明の表層厚さ測定方法によれば、鉄
材料や非鉄金属材料からなる丸棒材で断面が二層状をな
す材料の表層厚さを非破壊的にしかも短時間で測定する
ことができる。According to the method for measuring the surface layer thickness of the present invention, the surface layer thickness of a round bar made of a ferrous material or a non-ferrous metal material having a two-layer cross section can be measured nondestructively and in a short time. can do.
【図１】本実施形態の表層厚さ測定装置の概略図であ
る。FIG. 1 is a schematic view of a surface layer thickness measuring device according to an embodiment.
【図２】二層構造試料と印加磁界を示す模式図である。FIG. 2 is a schematic diagram showing a sample having a two-layer structure and an applied magnetic field.
【図３】丸棒鋼用脱炭深さ測定装置を示す模式図であ
る。FIG. 3 is a schematic view showing a decarburization depth measuring device for a round steel bar.
【図４】表層厚さ推定するためのフローチャートであ
る。FIG. 4 is a flowchart for estimating a surface layer thickness.
【図５】実効インダクタンス測定値を示す特性図であ
る。FIG. 5 is a characteristic diagram showing measured effective inductance values.
【図６】脱炭深さ測定値を示す特性図である。FIG. 6 is a characteristic diagram showing measured values of decarburization depth.
１ 空心コイル １ａ 励磁コイル １ｂ 検出コイル ２ 励磁用電気回路部 ３ 電圧検出部 ４ デジタル演算器 ５ 試料 ６ 印加磁界 ７ 試料 ８ 表層 ９ 内部層 １０ 定振幅励磁器 １１ 周波数特性測定器 １２ 基準信号 １３ 基準電流値信号 １４ パーソナルコンピュータ DESCRIPTION OF SYMBOLS 1 Air-core coil 1a Excitation coil 1b Detection coil 2 Electric circuit part for excitation 3 Voltage detection part 4 Digital calculator 5 Sample 6 Applied magnetic field 7 Sample 8 Surface layer 9 Inner layer 10 Constant amplitude exciter 11 Frequency characteristic measuring instrument 12 Reference signal 13 Reference Current signal 14 Personal computer
Claims (2)
導電性の棒材や線材を空心コイルの内部に同心になるよ
うに固定し、該コイルに正弦波の電流を供給し、該コイ
ルまたは被測定物を貫通し該コイルに隣接して設けた別
のコイルに発生する電磁誘導電圧の振幅と前記励磁電流
を基準とした位相を測定し、前記励磁電流の正弦波の周
波数を変化させて前記測定を繰り返し、得られた測定値
から被測定物の自己または相互インダクタンスを算出す
るとともに、該算出値と別途用意した表層部と内層部か
らなる２層モデルの自己または相互インダクタンスのモ
デル式を用いて回帰計算を行い、前記理論計算のパラメ
ータである表層部の厚みを求めることを特徴とする表層
厚さ測定方法。An object to be measured comprising a surface layer portion and an inner layer portion, a conductive rod or wire, which is an object to be measured, is fixed concentrically inside an air-core coil, and a sine wave current is supplied to the coil. Measure the amplitude of the electromagnetic induction voltage generated in the coil or another coil provided adjacent to the coil to be measured and the phase with respect to the exciting current, and change the frequency of the sine wave of the exciting current. The above measurement is repeated to calculate the self or mutual inductance of the device under test from the obtained measured values, and the self or mutual inductance model of the two-layer model including the surface layer portion and the inner layer portion separately prepared from the calculated values. A method for measuring a surface layer thickness, wherein regression calculation is performed using an equation to determine a thickness of a surface layer portion, which is a parameter of the theoretical calculation.
導電性の棒材や線材を空心コイルの内部に同心になるよ
うに固定し、該コイルに正弦波の励磁電流を供給し、該
コイルまたは被測定物を貫通し該コイルに隣接して設け
た別のコイルに発生する電磁誘導電圧の振幅と前記励磁
電流を基準とした位相を測定し、前記励磁電流の正弦波
の周波数を表層部の材質で決まる周波数以上の範囲で変
化させて前記測定を繰り返し、得られた測定値から被測
定物自己または相互インダクタンスを算出するととも
に、該算出値と別途用意した表層部の材質からなる単層
モデルの自己または相互インダクタンスのモデル式を用
いて回帰計算を行い、前記モデル式のパラメータである
表層部の透磁率と電気抵抗率を予め求め、その後、請求
項１記載の方法により表層部の厚みを求めることを特徴
とする表層厚さ測定方法。2. A conductive rod or wire, which is an object to be measured, comprising a surface layer portion and an inner layer portion, is fixed concentrically inside an air-core coil, and a sinusoidal exciting current is supplied to the coil. The amplitude of the electromagnetic induction voltage generated in another coil provided adjacent to the coil or the object to be measured and penetrating the object to be measured and the phase based on the excitation current are measured, and the frequency of the sine wave of the excitation current is measured. The above measurement is repeated by changing the frequency in a range equal to or higher than the frequency determined by the material of the surface portion, and the measured object self or mutual inductance is calculated from the obtained measured value, and the calculated value and the material of the surface portion separately prepared are used. A regression calculation is performed using a model formula of the self or mutual inductance of the single-layer model, and the permeability and the electrical resistivity of the surface layer portion, which are parameters of the model formula, are determined in advance. A method for measuring a surface layer thickness, comprising determining a thickness of a surface layer portion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10196534A JP2000009414A (en) | 1998-06-26 | 1998-06-26 | Method for measuring thickness of surface layer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10196534A JP2000009414A (en) | 1998-06-26 | 1998-06-26 | Method for measuring thickness of surface layer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2000009414A true JP2000009414A (en) | 2000-01-14 |
Family
ID=16359348
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10196534A Withdrawn JP2000009414A (en) | 1998-06-26 | 1998-06-26 | Method for measuring thickness of surface layer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2000009414A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003065706A (en) * | 2001-08-22 | 2003-03-05 | Nippon Steel Corp | Device for measuring thickness of conductive material |
| JP2005345157A (en) * | 2004-05-31 | 2005-12-15 | Toshiba Corp | Crack depth inspection method of metallic material |
| JP2007519898A (en) * | 2003-12-31 | 2007-07-19 | アーベーベー・アーベー | Method and device for measuring object thickness and electrical conductivity to be measured |
| WO2008109301A1 (en) * | 2007-03-02 | 2008-09-12 | Qed Technologies International, Inc. | Method and apparatus for measurement of magnetic permeability of a material |
| CN101832751A (en) * | 2010-06-08 | 2010-09-15 | 天津大学 | Device and method for measuring decarburization thickness of steel based on hollow-core sensor |
| CN103983177A (en) * | 2014-03-23 | 2014-08-13 | 国家电网公司 | Heated surface tube inner oxide skin accumulation condition detection method |
| CN104612662A (en) * | 2014-12-31 | 2015-05-13 | 郑州光力科技股份有限公司 | Drilling depth measuring device for drill pipe and measuring method adopting same |
-
1998
- 1998-06-26 JP JP10196534A patent/JP2000009414A/en not_active Withdrawn
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003065706A (en) * | 2001-08-22 | 2003-03-05 | Nippon Steel Corp | Device for measuring thickness of conductive material |
| JP4551035B2 (en) * | 2001-08-22 | 2010-09-22 | 新日本製鐵株式会社 | Conductor thickness measuring device |
| JP2007519898A (en) * | 2003-12-31 | 2007-07-19 | アーベーベー・アーベー | Method and device for measuring object thickness and electrical conductivity to be measured |
| JP2005345157A (en) * | 2004-05-31 | 2005-12-15 | Toshiba Corp | Crack depth inspection method of metallic material |
| WO2008109301A1 (en) * | 2007-03-02 | 2008-09-12 | Qed Technologies International, Inc. | Method and apparatus for measurement of magnetic permeability of a material |
| CN101832751A (en) * | 2010-06-08 | 2010-09-15 | 天津大学 | Device and method for measuring decarburization thickness of steel based on hollow-core sensor |
| CN103983177A (en) * | 2014-03-23 | 2014-08-13 | 国家电网公司 | Heated surface tube inner oxide skin accumulation condition detection method |
| CN104612662A (en) * | 2014-12-31 | 2015-05-13 | 郑州光力科技股份有限公司 | Drilling depth measuring device for drill pipe and measuring method adopting same |
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