JPH03170841A - Nondestructive hardness measurement method for conductive materials - Google Patents
Nondestructive hardness measurement method for conductive materialsInfo
- Publication number
- JPH03170841A JPH03170841A JP31130989A JP31130989A JPH03170841A JP H03170841 A JPH03170841 A JP H03170841A JP 31130989 A JP31130989 A JP 31130989A JP 31130989 A JP31130989 A JP 31130989A JP H03170841 A JPH03170841 A JP H03170841A
- Authority
- JP
- Japan
- Prior art keywords
- hardness
- conductive material
- measured
- impedance
- conductive materials
- 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
- 239000004020 conductor Substances 0.000 title claims description 43
- 238000000034 method Methods 0.000 title claims description 14
- 238000007542 hardness measurement Methods 0.000 title description 4
- 230000001066 destructive effect Effects 0.000 claims description 4
- 235000019589 hardness Nutrition 0.000 description 66
- 239000000523 sample Substances 0.000 description 12
- 239000000047 product Substances 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 238000012545 processing Methods 0.000 description 7
- 239000007769 metal material Substances 0.000 description 6
- 238000005259 measurement Methods 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 238000011088 calibration curve Methods 0.000 description 3
- 238000007689 inspection Methods 0.000 description 3
- 230000032683 aging Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910003460 diamond Inorganic materials 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000007373 indentation Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 229910001080 W alloy Inorganic materials 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002847 impedance measurement Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000009659 non-destructive testing Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
Landscapes
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Abstract
(57)【要約】本公報は電子出願前の出願データであるた
め要約のデータは記録されません。(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、金属材料等の導電性材料の非破壊硬度測定方
法に関し、特に導電性材料の表面から内部に及ぶ範囲の
硬度を渦電流を利用して間接的に測定するものである。Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for non-destructive hardness measurement of conductive materials such as metal materials. It is used to measure indirectly.
金属製品にあっては、例えば製品の表面と内部とで硬度
差をつけるなどして用いる場合がある。In the case of metal products, for example, hardness may be differentiated between the surface and the inside of the product.
このような硬度差をつける方法として、一般に加工量の
差や熱処理などが利用されるが、いずれの方法によって
も被処理品の硬度分布を正確に制御することは困難であ
る。しかもこれらの処理を施した後に、さらに仕上げ加
工を施すのが普通で、この仕上げ加工により硬度分布の
位置がずれてしまう可能性がある。As a method of creating such a hardness difference, differences in processing amount, heat treatment, etc. are generally used, but it is difficult to accurately control the hardness distribution of the processed product by any of these methods. Moreover, after these treatments, it is common to perform further finishing processing, and this finishing processing may shift the position of the hardness distribution.
したがって、金属製品に対して精密な硬度分布が要求さ
れる場合には、その製品全部に硬さ試験を行って全数検
査することが望ましい。Therefore, when a precise hardness distribution is required for a metal product, it is desirable to conduct a hardness test on all the products and conduct a 100% inspection.
従来の金属材料の硬度測定方法としては、例えばビッカ
ース硬さ試験機による方法が広く行われている。これは
ダイヤモンド圧子を被測定物の面に規定の荷重で押し込
み、その面が塑性変形して生じたくぼみの大きさから一
定の方式にしたがってビッカース硬さ（ＨＶ）を求めて
いる。As a conventional method for measuring the hardness of metal materials, for example, a method using a Vickers hardness tester is widely used. In this method, a diamond indenter is pressed into the surface of the object to be measured with a specified load, and the Vickers hardness (HV) is determined according to a certain method from the size of the depression created by plastic deformation of the surface.
〔発明が解決しようとする諜題）
しかしこのような硬さ試験は、被試験品の測定面に圧子
による圧痕が残るから、表面粗さが全く関係ない大きな
製品の場合であればともかく、円滑な表面形状を要求さ
れる製品の場合は不適当である。このような硬さ試験に
よる圧痕を極力小さくするため、超音波を利用してダイ
ヤモンド圧子の振動数の変化から硬さを推定する方法も
あるが、微小な圧痕は避けられない。[The secret problem that the invention seeks to solve] However, this kind of hardness test leaves impressions by the indenter on the measurement surface of the tested product, so it cannot be performed smoothly, even if it is a large product where surface roughness is not a factor. It is unsuitable for products that require a specific surface shape. In order to minimize indentations caused by such hardness tests, there is a method of estimating hardness from changes in the frequency of a diamond indenter using ultrasonic waves, but small indentations are unavoidable.
更に製品材料内の硬度分布をも検査したい場合は、被試
験材を切断し内部を露出させて測定しなければならず、
非破壊試験は不可能であり抜き取り検査とせざるを得な
い。Furthermore, if you want to inspect the hardness distribution within the product material, you must cut the material under test to expose the inside and measure it.
Non-destructive testing is not possible and sampling inspections must be performed.
そこで本発明は、上記従来の問題点に着目してなされた
ものであり、その目的とするところは、導電性材料の表
面から内部に及ぶ範囲の硬度を完全に非破壊で測定する
導電性材料の非破壊硬度測定方法を提供することにある
。Therefore, the present invention has been made by focusing on the above-mentioned conventional problems, and its purpose is to provide a conductive material that can completely non-destructively measure the hardness of the conductive material in a range from the surface to the inside. The object of the present invention is to provide a non-destructive hardness measurement method.
上記の目的を達或する本発明は、コイルに流した交流電
流により導電性材料表面又は内部に渦電流を生じさせ、
その渦電流により前記導電性材料のインピーダンスを測
定し、そのインピーダンスと導電性材料の表面又は内部
の硬度との比例関係に基づいて前記導電性材料の表面又
は内部の硬度を測定することを特徴とする。The present invention achieves the above object by generating an eddy current on the surface or inside of a conductive material by an alternating current passed through a coil,
The impedance of the conductive material is measured by the eddy current, and the hardness of the surface or inside of the conductive material is measured based on the proportional relationship between the impedance and the hardness of the surface or inside of the conductive material. do.
ここに導電性材料とは、電気伝導性を有する材料をいい
、主として金属材であるが必ずしも金属材のみとは限ら
ない。The electrically conductive material herein refers to a material that has electrical conductivity, and is primarily a metal material, but is not necessarily limited to a metal material.
金属材の加工或いは熱処理で硬さが変化する場合、材料
内部の転移密度の増大や硬度上昇要因となる析出物の出
現などにより、金属材の電気的特性が大きく変化するこ
とが考えられる。本発明者らはこの点に注目して研究を
重ね、硬さ既知の多数の導電性材料に対して渦電流を生
じさせ、この渦電流を利用して導電性材料のインピーダ
ンス威分を測定した結果、そのインピーダンス威分の値
が導電性材料の硬さと比例するという新規な知見を見出
した。When the hardness of a metal material changes due to processing or heat treatment, the electrical characteristics of the metal material may change significantly due to an increase in the dislocation density inside the material or the appearance of precipitates that cause an increase in hardness. The inventors of the present invention have focused on this point and have conducted research, generated eddy currents in a number of conductive materials with known hardness, and measured the impedance strength of conductive materials using this eddy current. As a result, we discovered a new finding that the impedance value is proportional to the hardness of the conductive material.
本発明の導電性材料の非破壊硬度測定方法は、こうして
得られた導電性材料に関するインピーダンス或分の値と
硬さとの関係に基づいて、未知の導電性材料の硬さを非
破壊的に求めるものである。The non-destructive hardness measurement method for conductive materials of the present invention non-destructively determines the hardness of an unknown conductive material based on the relationship between the impedance value and the hardness of the conductive material obtained in this manner. It is something.
導電性材料に渦電流を生じさせ、同時にその導電性材料
のインピーダンス戒分を測定する手段として、コイルブ
ローブを好適に用いることができる。コイルプローブは
内部にコイルを有する端子で、そのコイルに周波数を制
御した交流電流を流して被測定導電性材料に接触させる
と、周波数に応じてその材料の表面または内部に渦電流
が生じる。用いる周波数によって、渦電流が生じる個所
を材料の表面から内部に及ぶ任意の範囲に選定すること
が可能で、周波数が低くなるほど材料内部に及ぶ。すな
わち、例えば周波数がＩＭＨ．程度と高い場合は材料表
面の硬さが測定でき、低くなるほど材料内部の硬さが測
定できる。A coil probe can be suitably used as a means for generating an eddy current in a conductive material and at the same time measuring the impedance distribution of the conductive material. A coil probe is a terminal that has a coil inside, and when an alternating current with a controlled frequency is passed through the coil and brought into contact with a conductive material to be measured, eddy currents are generated on the surface or inside of the material depending on the frequency. Depending on the frequency used, it is possible to select the location where eddy currents are generated within any range from the surface of the material to the inside of the material; the lower the frequency, the deeper the eddy current is generated. That is, for example, if the frequency is IMH. If the degree is high, the hardness of the surface of the material can be measured, and if it is low, the hardness inside the material can be measured.
しかして、インピーダンスはりアクタンス威分と抵抗或
分とにベクトル分解できるから、その抵抗戒分を電圧の
値として測定すれば、この電圧の値がすなわち被測定導
電性材料の所定個所の硬さと比例する。Therefore, impedance can be vector decomposed into actance force and resistance, so if the resistance force is measured as a voltage value, this voltage value is proportional to the hardness of a given part of the conductive material to be measured. do.
以下、本発明の実施例を図とともに説明する。 Embodiments of the present invention will be described below with reference to the drawings.
第１図は被測定導電性材料１に渦電流を生じさせ、同時
にその導電性材料ｌのインピーダンス戒分を測定するた
めの装置の模式図であり、２はコイル２ａを内蔵したコ
イルプロープ、３はそのコイルプロープ２に所定周波数
の電流を流すための交流電源、４はインピーダンスの抵
抗或分を電圧値として測定するインピーダンス抵抗威分
測定器である。FIG. 1 is a schematic diagram of an apparatus for generating an eddy current in a conductive material to be measured 1 and at the same time measuring the impedance ratio of the conductive material 1, in which 2 is a coil probe with a built-in coil 2a, 3 numeral 4 is an AC power source for passing a current of a predetermined frequency through the coil probe 2, and 4 is an impedance resistance measuring device that measures the resistance of impedance as a voltage value.
■＝硬度既知の導電性試料によるインピーダンスの抵抗
戒分（電圧）の測定、すなわち検量線の作成。■=Measurement of impedance resistance (voltage) using a conductive sample with known hardness, that is, creation of a calibration curve.
導電性試料として、タングステン合金（９５ｗｔ％Ｗ
３．５ｗｔ％Ｎｉ ｉ．５ｗｔ％Ｆｅ）の丸棒材を
多数用意し、スウエージング加工と時効処理で種々の硬
さに調整した。硬さＨｖ４５０未満は、第２図に示すよ
うに加工率を変化させてスウエージング加工のみを施す
ことで試料の硬さを調整した。As a conductive sample, tungsten alloy (95wt% W
3.5wt%Ni i. A large number of round bars of 5 wt% Fe) were prepared and adjusted to various hardnesses by swaging and aging treatment. When the hardness was less than Hv450, the hardness of the sample was adjusted by changing the processing rate and performing only swaging processing as shown in FIG.
また、硬さＨＶ４５０〜５５０までは、加工率を２０〜
５０％の範囲内で変化させてスウェージング加工を施し
た後、さらに４００゜Ｃで■時間の時効処理を施すこと
で試料の硬さを調整した。In addition, for hardness HV450-550, the processing rate is 20-550.
After swaging the hardness within a range of 50%, the hardness of the sample was adjusted by aging at 400°C for 1 hour.
次に、この硬さを調整した試料のそれぞれについてビッ
カース硬さ試験機によりビッカース硬さを実測した。Next, the Vickers hardness of each of the samples whose hardness was adjusted was measured using a Vickers hardness tester.
このようにして調整した硬度既知の試料について、第１
図に示す渦電流を利用したインピーダンス測定装置を用
いてインピーダンスの抵抗戒分（電圧）を測定した。す
なわち、コイルプローブ２の先端部を導電性材料ｌの試
料の表面に接触させて、交流電源３により周波数８０Ｋ
Ｈ２の交流電流をコイル２ａに流す。これにより導電性
材料１に硬さに応じた渦電流６が発生する。この渦電流
によるインピーダンスの抵抗戒分をインピーダンス抵抗
或分測定器４で電圧値（Ｖ）として測定した。For the sample with known hardness adjusted in this way, the first
The resistance component (voltage) of impedance was measured using an impedance measurement device using eddy current shown in the figure. That is, the tip of the coil probe 2 is brought into contact with the surface of the sample made of conductive material 1, and the AC power source 3 is used to apply a frequency of 80K.
An alternating current of H2 is passed through the coil 2a. As a result, an eddy current 6 is generated in the conductive material 1 according to its hardness. The resistance component of the impedance due to this eddy current was measured as a voltage value (V) using an impedance resistance measuring device 4.
第１図は、その硬度一電圧の測定結果をグラフにプロッ
トして得られた検量線である．■＝硬度未知の導電性試
料によるインピーダンスの抵抗戊分（電圧）の測定。Figure 1 is a calibration curve obtained by plotting the hardness vs. voltage measurement results on a graph. ■=Measurement of the resistance component (voltage) of impedance using a conductive sample of unknown hardness.
次に、硬度未知の多数の導電性材料１について、上記と
同様にして第１図に示すインピーダンス戒分測定装置に
よりインピーダンスの抵抗戒分（電圧）を測定した。Next, for a large number of conductive materials 1 of unknown hardness, the impedance resistance factor (voltage) was measured using the impedance factor measuring device shown in FIG. 1 in the same manner as described above.
かくして得られた電圧値から第２図に示す検量線を用い
て、各導電性材料毎にビッカース硬さを推定した。The Vickers hardness of each conductive material was estimated from the voltage values thus obtained using the calibration curve shown in FIG.
この渦電流を利用して求めた推定硬度の信頼度をＩＩＩ
Ｌｙ２するため、上記硬度未知の多数の導電性材料１の
それぞれについて、ビッヵース硬さ試験機により実際の
ビッカース硬さを実測した。この実測硬度と上記推定硬
度との対比を第３図に示す。The reliability of the estimated hardness obtained using this eddy current is
In order to measure Ly2, the actual Vickers hardness of each of the large number of conductive materials 1 with unknown hardness was measured using a Vickers hardness tester. FIG. 3 shows a comparison between this measured hardness and the estimated hardness.
第３図から、上記推定硬度は実測硬度にほぼ一致してお
り、本発明の方法によって導電性材料の硬さを非破壊で
かつ容易に測定できることが明白である。From FIG. 3, it is clear that the estimated hardness is almost in agreement with the measured hardness, and that the method of the present invention can easily and non-destructively measure the hardness of a conductive material.
以上説明したように、本発明によれば、コイルに流した
交流電流により導電性材料表面又は内部に渦電流を生じ
させ、その渦電流により前記導電性材料のインピーダン
スを測定し、そのインピーダンスと導電性材料の表面又
は内部の硬度とめ比例関係に基づいて前記導電性材料の
表面又は内部の硬度を測定するものとしたため、導電性
材料の表面から内部に及ぶ範囲の硬度を完全に非破壊で
測定することが可能となり、その結果次のような効果が
得られる。As explained above, according to the present invention, an eddy current is generated on the surface or inside of a conductive material by an alternating current applied to a coil, and the impedance of the conductive material is measured by the eddy current, and the impedance and conductivity are measured. Since the hardness of the surface or inside of the conductive material is measured based on the proportional relationship between the hardness of the surface or inside of the conductive material, the hardness in the range from the surface to the inside of the conductive material can be measured completely non-destructively. As a result, the following effects can be obtained.
■ 導電性材料からなる製品の硬さ或いは硬さの分布を
、全数検査で求めることができる。■ The hardness or hardness distribution of products made of conductive materials can be determined by 100% inspection.
■ 本発明の方法による推定硬度と硬さ測定機による実
測硬度との相関を一旦求めさえすれば、その後は、硬さ
測定機による測定に比べて数十分の一ないし数百分の一
の測定時間で極めて効率よく導電性材料の硬さを求める
ことができる．■ 導電性材料が不均一で、部分的に硬
さが異常に高い個所の存在することが懸念される場合な
どでも、その導電性材料の全体にわたって非破壊で走査
して確認することができる。■ Once the correlation between the estimated hardness by the method of the present invention and the actual hardness measured by a hardness measuring machine is determined, it is possible to calculate the The hardness of conductive materials can be determined extremely efficiently within the measurement time. ■ Even if the conductive material is non-uniform and there is a concern that there are parts with abnormally high hardness, it can be confirmed by non-destructively scanning the entire conductive material.
第１図は本発明の硬度測定方法を実施するための測定装
置の一例を示す模式図、第２図は被測定導電性材料に対
するビッカース硬さ試験機による硬さ実測値と第１図に
示す測定装置で求めた測定電圧値との相関グラフ、第３
図は第２図のグラフを検盟線として求めた本発明の測定
方法による導電性材料の推定硬度とビッカース硬さ試験
機による実測硬度との相関を示すグラフである。
図中、２ａはコイル、３は交流電源、４はインピーダン
ス抵抗成分測定器．Fig. 1 is a schematic diagram showing an example of a measuring device for carrying out the hardness measuring method of the present invention, and Fig. 2 shows the actual hardness values measured by a Vickers hardness tester for the conductive material to be measured, and the values shown in Fig. 1. Correlation graph with the measured voltage value obtained by the measuring device, 3rd
The figure is a graph showing the correlation between the estimated hardness of a conductive material obtained by the measurement method of the present invention using the graph of FIG. 2 as a test line, and the actual hardness measured by a Vickers hardness tester. In the figure, 2a is a coil, 3 is an AC power supply, and 4 is an impedance resistance component measuring device.
Claims (1)
は内部に渦電流を生じさせ、その渦電流により前記導電
性材料のインピーダンスを測定し、そのインピーダンス
と導電性材料の表面又は内部の硬度との比例関係に基づ
いて前記導電性材料の表面又は内部の硬度を測定するこ
とを特徴とする導電性材料の非破壊硬度測定方法。(1) An eddy current is generated on the surface or inside of the conductive material by an alternating current passed through the coil, and the impedance of the conductive material is measured by the eddy current, and the impedance and the hardness of the surface or inside of the conductive material are calculated. A non-destructive hardness measuring method for a conductive material, characterized in that the hardness of the surface or inside of the conductive material is measured based on the proportional relationship.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31130989A JPH03170841A (en) | 1989-11-30 | 1989-11-30 | Nondestructive hardness measurement method for conductive materials |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31130989A JPH03170841A (en) | 1989-11-30 | 1989-11-30 | Nondestructive hardness measurement method for conductive materials |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03170841A true JPH03170841A (en) | 1991-07-24 |
Family
ID=18015585
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31130989A Pending JPH03170841A (en) | 1989-11-30 | 1989-11-30 | Nondestructive hardness measurement method for conductive materials |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03170841A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102013202907A1 (en) * | 2013-02-22 | 2014-08-28 | Mahle International Gmbh | Testing device for testing camshaft of internal combustion engine of motor car, has measuring units arranged adjacent to each other along direction and simultaneously performing hardness and/or surface testing of individual cams of camshaft |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS557630A (en) * | 1978-06-30 | 1980-01-19 | Sumitomo Metal Ind Ltd | Inspection method of depth for peening machined layer at internal surface of tube |
| JPS55141653A (en) * | 1979-04-20 | 1980-11-05 | Mitsubishi Heavy Ind Ltd | Deterioration state deciding method of strong precipitation hardness type iron base alloy |
| JPS59137856A (en) * | 1983-01-28 | 1984-08-08 | Nippon Kokan Kk <Nkk> | Eddy-current type hardness measurement |
| JPS59183359A (en) * | 1983-04-01 | 1984-10-18 | Sumitomo Metal Ind Ltd | Method for testing quality of steel material |
-
1989
- 1989-11-30 JP JP31130989A patent/JPH03170841A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS557630A (en) * | 1978-06-30 | 1980-01-19 | Sumitomo Metal Ind Ltd | Inspection method of depth for peening machined layer at internal surface of tube |
| JPS55141653A (en) * | 1979-04-20 | 1980-11-05 | Mitsubishi Heavy Ind Ltd | Deterioration state deciding method of strong precipitation hardness type iron base alloy |
| JPS59137856A (en) * | 1983-01-28 | 1984-08-08 | Nippon Kokan Kk <Nkk> | Eddy-current type hardness measurement |
| JPS59183359A (en) * | 1983-04-01 | 1984-10-18 | Sumitomo Metal Ind Ltd | Method for testing quality of steel material |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102013202907A1 (en) * | 2013-02-22 | 2014-08-28 | Mahle International Gmbh | Testing device for testing camshaft of internal combustion engine of motor car, has measuring units arranged adjacent to each other along direction and simultaneously performing hardness and/or surface testing of individual cams of camshaft |
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