JPH01169348A - Cracking detector - Google Patents
Cracking detectorInfo
- Publication number
- JPH01169348A JPH01169348A JP32872187A JP32872187A JPH01169348A JP H01169348 A JPH01169348 A JP H01169348A JP 32872187 A JP32872187 A JP 32872187A JP 32872187 A JP32872187 A JP 32872187A JP H01169348 A JPH01169348 A JP H01169348A
- Authority
- JP
- Japan
- Prior art keywords
- terminals
- cracking
- potential difference
- crack
- cracks
- 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
- 238000005336 cracking Methods 0.000 title abstract 8
- 238000001514 detection method Methods 0.000 claims abstract description 18
- 239000000523 sample Substances 0.000 abstract description 14
- 238000010586 diagram Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 206010016256 fatigue Diseases 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- SMEGJBVQLJJKKX-HOTMZDKISA-N [(2R,3S,4S,5R,6R)-5-acetyloxy-3,4,6-trihydroxyoxan-2-yl]methyl acetate Chemical compound CC(=O)OC[C@@H]1[C@H]([C@@H]([C@H]([C@@H](O1)O)OC(=O)C)O)O SMEGJBVQLJJKKX-HOTMZDKISA-N 0.000 description 1
- 229940081735 acetylcellulose Drugs 0.000 description 1
- 229920002301 cellulose acetate Polymers 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 239000006249 magnetic particle Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000009659 non-destructive testing Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
Landscapes
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は亀裂検出装置に係り、特に金属部材表面の微小
疲労亀裂発生を検出するのに好適な亀裂検出装置に関す
る。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a crack detection device, and particularly to a crack detection device suitable for detecting the occurrence of minute fatigue cracks on the surface of a metal member.
火力発電プラント、化学装置プラント等において、長期
間使用される金属部材には、プラントの起動・停止に伴
い繰返し応力が作用する場合が多く、疲労損傷によって
亀裂が発生・進展して重大事故に至ることがある。Metal components used for long periods in thermal power plants, chemical equipment plants, etc. are often subjected to repeated stress as the plant starts and stops, causing fatigue damage that can cause cracks to develop and develop, leading to serious accidents. Sometimes.
−IGに、長さ数m以上のマクロ亀裂が生じる以前の疲
労損傷の初期段階において、第8図に示すように部材6
の表面に長さ数lO〜数100μmの微小亀裂9が多数
(数10〜数100個)発生する。- In the initial stage of fatigue damage before macrocracks with a length of several meters or more occur in the IG, as shown in Figure 8, the member 6
A large number (several 10s to several 100s) of microcracks 9 with a length of several 10 to several 100 μm are generated on the surface of the substrate.
この微小亀裂の発生を検知できれば、マクロ亀裂の進展
に至る前の損傷の小さい段階で対策を講じることができ
る。If the occurrence of microcracks can be detected, countermeasures can be taken at a stage where the damage is small, before macrocracks develop.
ところで一般の非破壊検査手法、例えば表面亀裂の検出
に有効な螢光磁粉探傷を用いても、長さ0.5mm程度
より小さな亀裂の検出はほとんど困難である。このため
上述の微小亀裂発生の有無を調査するには、部材表面を
注意深く鏡面状に研摩し、アセチルセルロース膜等のレ
プリカを採取して、50〜200倍程度の顕微鏡観察を
行っていた。By the way, even if a general non-destructive testing method is used, such as fluorescent magnetic particle testing which is effective for detecting surface cracks, it is almost difficult to detect cracks smaller than about 0.5 mm in length. Therefore, in order to investigate the presence or absence of the above-mentioned microcracks, the surface of the member was carefully polished to a mirror finish, a replica of the acetyl cellulose film, etc. was taken, and the replica was observed under a microscope at a magnification of about 50 to 200 times.
従来技術で行っているレプリカによる検査は、1枚のレ
プリカ寸法はたかだか1010X10程度であり、実機
部材の広範囲な個所を調査するには膨大な工数を要する
ことになる。In the conventional inspection using replicas, the dimensions of one replica are approximately 1010×10 at most, and a huge number of man-hours are required to investigate a wide range of parts of an actual machine member.
また、一般に市販されている電気抵抗または磁気変化を
利用した亀裂検出器は、長さ数m以上の1本のマクロ亀
裂を対象としたものであり、長さ数10〜数100μm
の微小亀裂が多数発生する場合には適用できない。In addition, crack detectors that use electrical resistance or magnetic changes that are generally available on the market target a single macro crack with a length of several meters or more;
It cannot be applied when many microcracks occur.
以上のように、従来技術では長さ数10〜数100μm
の微小亀裂を簡単に検出することができなかった。As mentioned above, in the conventional technology, the length is several tens to several hundred μm.
microcracks could not be easily detected.
本発明の目的はこのような微小疲労亀裂発生の有無を簡
単に検知することができる亀裂検出装置を提供すること
にある。An object of the present invention is to provide a crack detection device that can easily detect the presence or absence of such micro fatigue cracks.
〔問題点を解決するための手段〕
本発明は、上記問題点を解決するためになされたもので
、亀裂の有無を検査される部材表面の2つの点において
2つの給電端子を接触させ、上記2つの部材表面接触点
を結ぶ線内の2点において2つの検出端子を部材と接触
させ、定電流装置により上記2つの給電端子に所定電流
を供給し、微小電圧計により上記2つの検出端子間の電
位差を検出して部材表面の亀裂を検出する装置において
、前記部材表面の同一個所で直交する2方向について上
記電位差の測定を実施し、両電位差を比較して亀裂の有
無を判断するようにしたことを特徴とするものである。[Means for Solving the Problems] The present invention has been made to solve the above problems, and the present invention is made by bringing two power supply terminals into contact with each other at two points on the surface of a member to be inspected for cracks, and Two detection terminals are brought into contact with the member at two points within the line connecting the surface contact points of the two members, a constant current device supplies a predetermined current to the two power supply terminals, and a microvoltmeter is used to detect the voltage between the two detection terminals. In a device that detects cracks on the surface of a member by detecting a potential difference, the potential difference is measured in two orthogonal directions at the same location on the surface of the member, and the presence or absence of a crack is determined by comparing both potential differences. It is characterized by the fact that
微小疲労亀裂は通常、すべて同一方向の亀裂として生じ
るので、亀裂が多数発生している場合、亀裂面と平行な
方向での電位差に比べ、亀裂面と直角な方向での電位差
が大きくなる。したがって、両者の値を比較することに
より、亀裂発生の有無を検知することができる。Micro fatigue cracks usually occur as cracks all in the same direction, so if many cracks occur, the potential difference in the direction perpendicular to the crack surface will be larger than the potential difference in the direction parallel to the crack surface. Therefore, by comparing both values, it is possible to detect whether or not a crack has occurred.
なお、本発明の場合、直交する2方向での電位差を測定
、比較するため、部材に作用する応力方向は任意でよい
。In the case of the present invention, the stress acting on the member may be in any direction since the potential difference in two orthogonal directions is measured and compared.
以下、本発明を実施例によりさらに詳細に説明する。 Hereinafter, the present invention will be explained in more detail with reference to Examples.
第1図は、本発明の一実施例である亀裂検出装置の系統
を示す図である。この装置は定電流装置2および微小電
圧計1が切替回路3を介してプローブ4に接続されてい
る。FIG. 1 is a diagram showing a system of a crack detection device that is an embodiment of the present invention. In this device, a constant current device 2 and a microvoltmeter 1 are connected to a probe 4 via a switching circuit 3.
第2図は、プローブ4の基本構造を示すもので、部材6
の表面に接触させた状態を示す。また第3図は、プロー
ブ4を第2図中下側より見た状態を示す。プローブ4に
は、第2図に示す1組4本の端子(給電端子7、検出端
子8)が2組取り付けられている。この2組の端子は、
第3図に示すように各々の軸線が直交するように固定さ
れている。FIG. 2 shows the basic structure of the probe 4, in which the member 6
Shows the state in which it is in contact with the surface. Further, FIG. 3 shows the state of the probe 4 seen from the lower side in FIG. Two sets of four terminals (power supply terminal 7, detection terminal 8) shown in FIG. 2 are attached to the probe 4. These two sets of terminals are
As shown in FIG. 3, they are fixed so that their respective axes are perpendicular to each other.
また給電端子7.7°および検出端子8.8′は各々切
替回路3を介して定電流装置2および微小電圧計1に接
続されている。Further, the power supply terminal 7.7° and the detection terminal 8.8' are connected to the constant current device 2 and the microvoltmeter 1 via the switching circuit 3, respectively.
このような構成においてまず片方の組の給電端子7−7
間に、定電流装置2から交流定電流を通電し、検出端子
8−8間の電位差■を測定する。In such a configuration, first one set of power supply terminals 7-7
During this time, a constant alternating current is applied from the constant current device 2, and the potential difference (2) between the detection terminals 8-8 is measured.
次に他方の組の給電端子7°−7”間に通電し、検出端
子8°−8°間の電位差■1を測定する。Next, electricity is applied between the power supply terminals 7° and 7'' of the other set, and the potential difference (1) between the detection terminals 8° and 8° is measured.
このときの通電条件は、次式で求まる表皮厚さδが微小
亀裂の深さと同程度(数10〜数100μm程度)とな
るように設定する。The energization conditions at this time are set so that the skin thickness δ determined by the following equation is approximately the same as the depth of the microcrack (approximately several 10 to several 100 μm).
1−′A
δ=(−σωμμ。)−−−−−−−−・−・・・−(
1)ここでσは電気伝導度、ωは周波数、μはその部材
の透磁率、μ。は真空の透磁率である。1-′A δ=(−σωμμ.)−−−−−−−−・−・・・−(
1) Here, σ is the electrical conductivity, ω is the frequency, and μ is the magnetic permeability of the member. is the vacuum permeability.
通常部材に微小亀裂が発生している場合、疲労亀裂は、
部材に作用する引張応力方向と直角な方向に発生するた
め、第4図のようにほとんど同一方向の亀裂9の集団と
して現れる。第4図中(ロ)−(口“)線上で、電位差
を測定した場合、電流は第5図に示した断面を横切る方
向、すなわち亀裂面を直角に横切る方向に流れる。前述
のように、表皮厚さδを小さくして亀裂深さと同程度と
しであるため、電流が亀裂を迂回し、その電位差Vlは
亀裂がない場合に比べて太き(増加する。When microcracks occur in normal members, fatigue cracks are
Since the cracks occur in a direction perpendicular to the direction of the tensile stress acting on the member, they appear as a group of cracks 9 oriented in almost the same direction as shown in FIG. When the potential difference is measured on the (b)-(b) line in Fig. 4, the current flows in a direction that crosses the cross section shown in Fig. 5, that is, in a direction that crosses the crack surface at right angles.As mentioned above, Since the skin thickness δ is made small to the same level as the crack depth, the current bypasses the crack, and the potential difference Vl becomes thicker (increases) compared to the case where there is no crack.
この場合、微小亀裂の数が多いはどVlは大きくなる。In this case, the larger the number of microcracks, the larger Vl becomes.
一方(ロ)−(口°)方向と直交する(イ)−(イ“)
線上で電位差を測定した場合、電流は第6図に示した断
面を横切り亀裂面と平行な方向に流れるため、その電位
差v2はvlはど亀裂の影響を受けない。On the other hand, (B) - (口°) direction is perpendicular to (A) - (A")
When the potential difference is measured on the line, the current flows across the cross section shown in FIG. 6 in a direction parallel to the crack surface, so the potential difference v2 is not affected by the crack.
したがって亀裂のない場合は■Iζ■よとなるが、亀裂
のある場合は、V、>V!となる。Therefore, if there is no crack, ■Iζ■, but if there is a crack, V,>V! becomes.
実際に調査する際は、応力方向の判らないことが多いの
で、第2図および第3図で示したプローブ4を任意の方
向で接触させ、2方向の電位差■、vlを測定する。次
にプローブ4を45度回転させて再測定する。いずれの
測定でもVIζ■2であれば亀裂の発生はないと判定し
、v>v ’またはv<v ’であれば微小亀裂発生と
判定して、詳細なレプリカ観察を行う。In actual investigation, since the stress direction is often unknown, the probe 4 shown in FIGS. 2 and 3 is brought into contact in any direction to measure the potential difference (2) and vl in the two directions. Next, the probe 4 is rotated 45 degrees and the measurement is performed again. In either measurement, if VIζ■2, it is determined that no crack has occurred, and if v>v' or v<v', it is determined that a micro-crack has occurred, and detailed replica observation is performed.
ところで実際の部材の場合、微小亀裂が発生していても
その正確な深さは不明なので、表皮厚さδの最適値を予
め決めることはできない。そこで通電電流の周波数を変
えて、δの値を対象としている亀裂深さをカバーできる
ように10〜1000μm程度の間で連続的に変化させ
なから■と■。However, in the case of an actual member, even if microcracks occur, the exact depth thereof is unknown, so the optimal value of the skin thickness δ cannot be determined in advance. Therefore, the frequency of the applied current is changed continuously between about 10 and 1000 μm so that the value of δ can cover the target crack depth.
の比較を行う。Make a comparison.
このように本装置を用いれば、容易に微小亀裂発生を検
知することができる。By using this device in this way, the occurrence of microcracks can be easily detected.
第7図は、本発明の他の実施例におけるプローブの構成
を示す図である。この実施例は、1組4本の端子を4組
、各々の軸線が中央で交叉するように固定したものであ
る。このプローブは第3図に比べて端子構成はやや複雑
になるが、プローブ4を45度回転させなくても切替回
路3の切替により、45度回転した方向でのVおよび■
1を測定することができる。FIG. 7 is a diagram showing the configuration of a probe in another embodiment of the present invention. In this embodiment, four sets of four terminals are fixed so that their axes intersect at the center. Although this probe has a slightly more complicated terminal configuration than that shown in Fig. 3, the switching circuit 3 can switch the probe 4 without rotating it 45 degrees, allowing the V and ■
1 can be measured.
本発明によれば、部材表面の酸化スケールを除去した後
、レプリカ観察のように鏡面状に仕上げるという必要が
なく、プローブを接触させることによって微小亀裂の有
無を検知することができる。According to the present invention, the presence or absence of microcracks can be detected by bringing a probe into contact with the surface of the member without requiring mirror-like finishing after removing oxide scale from the surface of the member, as in replica observation.
また電位差の絶対値でなく、同一個所の直交する方向の
電位差を比較して評価するため、部材の材質、表面荒さ
に影響されることがない。このため、従来に比べて効率
よく微小亀裂を検知でき、プラントの安全管理上、大き
な効果がある。Furthermore, since the evaluation is performed by comparing the potential difference in the orthogonal directions at the same location, rather than the absolute value of the potential difference, it is not affected by the material of the member or the surface roughness. Therefore, microcracks can be detected more efficiently than in the past, which has a significant effect on plant safety management.
第1図は、本発明の一実施例を示す亀裂検出装置の系統
を示す図、第2図は、プローブの構成を示す図、第3図
は、第1図の被検材表面のプローブ接触点を示す説明図
、第4図〜第6図は、被検材表面に生じた微小亀裂の発
生状況を示す説明図、第7図は、本発明の他の実施例の
プローブの構成を示す図、第8図は、微小亀裂の発生例
を示す説明図である。
1:微小電圧計、2:定電流装置、3:切替回路、4ニ
ブローブ、5:リード線、6:部材、7:給電端子、8
:検出端子。
代理人 弁理士 川 北 武 長
1:微小電圧計
2:定電流装置
3:切替回路
4ニブローブ
7:給電端子
8:検出端子
6:部材
第4図
(イ)Fig. 1 is a diagram showing the system of a crack detection device showing an embodiment of the present invention, Fig. 2 is a diagram showing the configuration of the probe, and Fig. 3 is a diagram showing the probe contact on the surface of the specimen material shown in Fig. 1. FIGS. 4 to 6 are explanatory diagrams showing the occurrence of microcracks on the surface of the test material. FIG. 7 is a diagram showing the configuration of a probe according to another embodiment of the present invention. 8 are explanatory views showing examples of occurrence of microcracks. 1: Microvoltmeter, 2: Constant current device, 3: Switching circuit, 4 nib lobe, 5: Lead wire, 6: Component, 7: Power supply terminal, 8
: Detection terminal. Agent Patent Attorney Takeshi Kawakita 1: Microvoltmeter 2: Constant current device 3: Switching circuit 4 Nib lobe 7: Power supply terminal 8: Detection terminal 6: Parts Figure 4 (A)
Claims (1)
2つの給電端子を接触させ、上記2つの部材表面接触点
を結ぶ線内の2点において2つの検出端子を部材と接触
させ、定電流装置により上記2つの給電端子に所定電流
を供給し、微小電圧計により上記2つの検出端子間の電
位差を検出して部材表面の亀裂を検出する装置において
、前記部材表面の同一個所で直交する2方向について上
記電位差の測定を実施し、両電位差を比較して亀裂の有
無を判断するようにしたことを特徴とする亀裂検出装置
。Two power supply terminals are brought into contact with the member at two points on the surface of the member to be inspected for the presence or absence of cracks, two detection terminals are brought into contact with the member at two points within a line connecting the two member surface contact points, and a constant current device is installed. In an apparatus for detecting cracks on the surface of a member by supplying a predetermined current to the two power supply terminals and detecting the potential difference between the two detection terminals using a microvoltmeter, two directions perpendicular to each other at the same location on the surface of the member are provided. A crack detection device characterized in that the above-described potential difference is measured and the presence or absence of a crack is determined by comparing both potential differences.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP32872187A JPH01169348A (en) | 1987-12-25 | 1987-12-25 | Cracking detector |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP32872187A JPH01169348A (en) | 1987-12-25 | 1987-12-25 | Cracking detector |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH01169348A true JPH01169348A (en) | 1989-07-04 |
Family
ID=18213437
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP32872187A Pending JPH01169348A (en) | 1987-12-25 | 1987-12-25 | Cracking detector |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH01169348A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5961225A (en) * | 1992-10-06 | 1999-10-05 | Seiko Epson Corporation | Tape printing device and tape cartridge used therein |
US6113292A (en) * | 1994-12-02 | 2000-09-05 | Seiko Epson Corporation | Printer head release mechanism |
JP2009028977A (en) * | 2007-07-26 | 2009-02-12 | Brother Ind Ltd | Tape printing apparatus |
-
1987
- 1987-12-25 JP JP32872187A patent/JPH01169348A/en active Pending
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5961225A (en) * | 1992-10-06 | 1999-10-05 | Seiko Epson Corporation | Tape printing device and tape cartridge used therein |
US5997194A (en) * | 1992-10-06 | 1999-12-07 | Seiko Epson Corporation | Tape printing device and tape cartridge used therein |
US6012860A (en) * | 1992-10-06 | 2000-01-11 | Seiko Epson Corporation | Tape printing device and tape cartridge used therein |
US6106171A (en) * | 1992-10-06 | 2000-08-22 | Seiko Epson Corporation | Tape printing device and cartridge used therein |
US6149325A (en) * | 1992-10-06 | 2000-11-21 | Seiko Epson Corporation | Tape printing device and tape cartridge used therein |
US6113292A (en) * | 1994-12-02 | 2000-09-05 | Seiko Epson Corporation | Printer head release mechanism |
JP2009028977A (en) * | 2007-07-26 | 2009-02-12 | Brother Ind Ltd | Tape printing apparatus |
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