JP2906482B2 - Steel sheet flaw detection method - Google Patents
Steel sheet flaw detection methodInfo
- Publication number
- JP2906482B2 JP2906482B2 JP27218389A JP27218389A JP2906482B2 JP 2906482 B2 JP2906482 B2 JP 2906482B2 JP 27218389 A JP27218389 A JP 27218389A JP 27218389 A JP27218389 A JP 27218389A JP 2906482 B2 JP2906482 B2 JP 2906482B2
- Authority
- JP
- Japan
- Prior art keywords
- steel sheet
- threshold value
- value
- flaw
- detection signal
- 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
Links
Landscapes
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 この発明は、鋼板の疵検出方法、特に、鋼板の微小疵
を検出することができる、鋼板の疵検出方法に関するも
のである。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting flaws on a steel sheet, and more particularly, to a method for detecting flaws on a steel sheet that can detect minute flaws on the steel sheet.
従来、電解クロメート処理鋼板、亜鉛メッキ鋼板等の
薄鋼板に存在するピンホール等の表面疵やブローホール
等の内部疵を、磁気を利用して検出する装置として、例
えば、第４図に示すものが知られている。Conventionally, as shown in FIG. 4, an apparatus using magnetism to detect surface flaws such as pinholes and internal flaws such as blowholes existing in thin steel sheets such as electrolytic chromate-treated steel sheets and galvanized steel sheets is shown in FIG. It has been known.
図示されるように、この疵検出装置は、鋼板１の移動
に伴って回転する中空ロール２と、中空ロール２内に設
けられた、鋼板１を磁化するための、コイル３を有する
磁化コア４と、磁化コア４間に設けられた、漏洩磁束を
検出するためのセンサー５とからなっている。As shown in the figure, the flaw detection device includes a hollow roll 2 that rotates with the movement of a steel sheet 1 and a magnetized core 4 provided in the hollow roll 2 and having a coil 3 for magnetizing the steel sheet 1. And a sensor 5 provided between the magnetized cores 4 for detecting leakage magnetic flux.
移動する鋼板１は、ロール２を介して磁化コア４によ
って磁化される。このようにして磁化された鋼板１に上
述したような疵が存在すると、疵の部分に漏洩磁束が生
じる。この漏洩磁束は、センサー５によって検出され、
センサー５からの疵信号によって鋼板１に存在する疵が
検出される。The moving steel sheet 1 is magnetized by the magnetizing core 4 via the roll 2. If the flaw as described above is present on the steel sheet 1 magnetized in this way, a leakage magnetic flux is generated at the flaw portion. This leakage magnetic flux is detected by the sensor 5,
A flaw existing in the steel sheet 1 is detected based on a flaw signal from the sensor 5.
この場合、疵信号にはノイズ信号が含まれるので、閾
値を予め設定し、疵の誤検出を防止している。In this case, since the flaw signal includes a noise signal, a threshold value is set in advance to prevent flaw detection of the flaw.
しかしながら、上述した、鋼板の疵検出方法は、次の
ような問題を有している。However, the above-described method for detecting a flaw on a steel sheet has the following problems.
即ち、上述したように疵信号には、疵によるもの以外
にノイズによるものがある。ノイズのレベルは、鋼種や
圧延条件等の違いによってまちまちである。従って、従
来は疵の誤検出を防止するために、ノイズの中で最も高
いレベルのものを閾値として設定していた。このため
に、主要な疵は検出できるものの微小疵は検出できない
虞れがあった。That is, as described above, the flaw signal includes a flaw signal other than a flaw signal. The noise level varies depending on the type of steel, rolling conditions, and the like. Therefore, conventionally, in order to prevent erroneous detection of a flaw, the highest noise level is set as the threshold value. For this reason, there is a possibility that the main flaw can be detected but the minute flaw cannot be detected.
従って、この発明の目的は、主要な疵の検出は勿論、
微小疵の検出も行える、鋼板の疵検出方法を提供するこ
とにある。Therefore, the object of the present invention is to detect major flaws,
An object of the present invention is to provide a method for detecting a flaw on a steel sheet, which can also detect a minute flaw.
この発明は、連続的に移動する鋼板の表面近傍に、疵
検出用センサーを設け、前記センサーからの検出信号と
予め設定された第１閾値とを比較し、前記第１閾値を越
える検出信号によって、前記鋼板の主要な疵を検出し、
前記センサーからの検出信号のうち、前記第１閾値に達
しない検出信号のピーク値を、前記鋼板の移動方向にそ
って所定距離間隔毎に検出し、このようにして検出した
複数個のピーク値のうち、所望のピーク値を前記複数個
のピーク値の代表値に選定し、このような代表値の選定
を、前記鋼板の移動方向にそって複数回繰り返し行い、
次いで、このようにして選定した複数個の代表値の平均
値を演算し、このようにして演算した前記平均値を第２
閾値として設定し、前記第１閾値に達しない検出信号と
前記第２閾値とを比較し、前記第２閾値を越える検出信
号によって、前記鋼板の微小疵を検出することに特徴を
有するものである。The present invention provides a flaw detection sensor near the surface of a continuously moving steel plate, compares a detection signal from the sensor with a preset first threshold value, and detects a detection signal exceeding the first threshold value. , Detecting major flaws in the steel sheet,
Among the detection signals from the sensor, a peak value of a detection signal that does not reach the first threshold value is detected at predetermined intervals along the moving direction of the steel sheet, and a plurality of peak values thus detected are detected. Among them, a desired peak value is selected as a representative value of the plurality of peak values, and the selection of such a representative value is repeated a plurality of times along the moving direction of the steel sheet,
Then, an average value of the plurality of representative values selected in this way is calculated, and the average value thus calculated is calculated as a second value.
The method is characterized in that the detection signal is set as a threshold value, the detection signal not reaching the first threshold value is compared with the second threshold value, and the minute flaw of the steel plate is detected by the detection signal exceeding the second threshold value. .
次に、この発明の、鋼板の疵検出方法の一実施態様
を、図面を参照しながら説明する。Next, an embodiment of the method for detecting flaws on a steel sheet according to the present invention will be described with reference to the drawings.
第１図は、この発明の、鋼板の疵検出方法の一実施態
様を示すブロック図である。FIG. 1 is a block diagram showing one embodiment of a method for detecting a flaw on a steel sheet according to the present invention.
連続的に移動する鋼板１の表面下に、例えば、前述し
た第４図に示すような疵検出装置を設置し、比較回路６
によって、疵検出装置のセンサー５からの検出信号と比
較回路６に予め設定された第１閾値とを比較し、第１閾
値を越える検出信号によって、鋼板１の主要な疵を検出
する。Below the surface of the continuously moving steel plate 1, for example, a flaw detection device as shown in FIG.
Then, the detection signal from the sensor 5 of the flaw detection device is compared with a first threshold value preset in the comparison circuit 6, and a main flaw of the steel sheet 1 is detected based on the detection signal exceeding the first threshold value.
これと同時に、センサー５からの検出信号をピーク値
検出回路７に入力して、センサー５からの検出信号のう
ち、第１閾値に達しない検出信号のピーク値を、第２図
（Ａ）に示すように、鋼板１の移動方向にそって所定距
離間隔毎、例えば、100mm毎にＮ個検出し、このように
して検出した複数個のピーク値P1からPnのうち、所望の
ピーク値Paを前記複数個のピーク値の代表値に選定し、
このような代表値の選定を、鋼板１の移動方向にそって
複数回繰り返し行う。次いで、このようにして選定した
複数個の代表値Pa1からPanの平均値ａを平均値演算回
路８によって演算し、このようにして演算した平均値
ａを第２閾値として比較回路９に設定し、前記第１閾値
に達しない検出信号と前記第２閾値とを比較し、前記第
２閾値を越える検出信号によって、鋼板１の微小疵を検
出する。At the same time, the detection signal from the sensor 5 is input to the peak value detection circuit 7, and among the detection signals from the sensor 5, the peak value of the detection signal that does not reach the first threshold is shown in FIG. as shown, each predetermined distance interval along the moving direction of the steel sheet 1, for example, n pieces detected every 100 mm, of P n thus a plurality of peak values P 1 detected by the desired peak value P a is selected as a representative value of the plurality of peak values,
Selection of such a representative value is repeated a plurality of times along the moving direction of the steel sheet 1. Then, the average value a of the plurality of representative values P a1 to P an selected in this manner is calculated by the average value calculation circuit 8, and the average value thus calculated is calculated.
a is set as a second threshold value in the comparison circuit 9, a detection signal not reaching the first threshold value is compared with the second threshold value, and a small flaw of the steel sheet 1 is detected by a detection signal exceeding the second threshold value. .
なお、安全を見込んで第２閾値をα倍しても良い。 The second threshold may be multiplied by α in anticipation of safety.
このように、第３図に示すように、従来は、第１閾値
を越える主要な疵の検出は行えたが、第１閾値に達しな
い微小疵の検出は行えなかったのに対して、この発明に
よれば、第１閾値と第２閾値との間に存在する微小疵の
検出を行うことができる。As described above, as shown in FIG. 3, conventionally, a major flaw exceeding the first threshold could be detected, but a small flaw that did not reach the first threshold could not be detected. According to the present invention, it is possible to detect a minute flaw existing between the first threshold value and the second threshold value.
以上説明したように、この発明によれば、主要な疵の
検出は勿論、微小疵の検出も行えるといった有用な効果
がもたらされる。As described above, according to the present invention, useful effects such as detection of minute flaws as well as detection of main flaws are provided.
第１図は、この発明の、鋼板の疵検出方法の一実施態様
を示すブロック図、第２図（Ａ）（Ｂ）は、信号の説明
図、第３図は、検出信号と鋼板の長さとの関係を示すグ
ラフ、第４図は、疵検出装置の概略断面図である。図面
において、 １……鋼板、２……中空ロール、３……コイル、４……
磁気コア、５……センサー、６、９……比較回路、７…
…ピーク値検出回路、８……平均値検出回路。FIG. 1 is a block diagram showing one embodiment of a method for detecting flaws on a steel sheet according to the present invention. FIGS. 2 (A) and 2 (B) are explanatory diagrams of signals, and FIG. FIG. 4 is a schematic cross-sectional view of the flaw detection device. In the drawings, 1 ... steel plate, 2 ... hollow roll, 3 ... coil, 4 ...
Magnetic core, 5 ... sensor, 6, 9 ... comparison circuit, 7 ...
... peak value detection circuit, 8 ... average value detection circuit.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 桝谷 守洋 山口県徳山市桜木１丁目４番１号 株式 会社システム計測内 (56)参考文献 特開 昭62−112053（ＪＰ，Ａ) 特開 昭61−126462（ＪＰ，Ａ) 特開 昭61−200459（ＪＰ，Ａ) 特開 平３−37564（ＪＰ，Ａ) 特公 昭59−40263（ＪＰ，Ｂ２) (58)調査した分野(Int.Cl.6，ＤＢ名) G01N 27/72 - 27/90 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Morihiro Masutani 1-4-1 Sakuragi, Tokuyama-shi, Yamaguchi Pref. 61-126462 (JP, A) JP-A-61-200459 (JP, A) JP-A-3-37564 (JP, A) JP-B-59-40263 (JP, B2) (58) Fields investigated (Int. Cl. 6 , DB name) G01N 27/72-27/90
Claims (1)
出用センサーを設け、前記センサーからの検出信号と予
め設定された第１閾値とを比較し、前記第１閾値を越え
る検出信号によって、前記鋼板の主要な疵を検出し、前
記センサーからの検出信号のうち、前記第１閾値に達し
ない検出信号のピーク値を、前記鋼板の移動方向にそっ
て所定距離間隔毎に検出し、このようにして検出した複
数個のピーク値のうち、所望のピーク値を前記複数個の
ピーク値の代表値に選定し、このような代表値の選定
を、前記鋼板の移動方向にそって複数回繰り返し行い、
次いで、このようにして選定した複数個の代表値の平均
値を演算し、このようにして演算した前記平均値を第２
閾値として設定し、前記第１閾値に達しない検出信号と
前記第２閾値とを比較し、前記第２閾値を越える検出信
号によって、前記鋼板の微小疵を検出することを特徴と
する、鋼板の疵検出方法。1. A flaw detection sensor is provided near the surface of a continuously moving steel sheet, and a detection signal from the sensor is compared with a preset first threshold value, and a detection signal exceeding the first threshold value is detected. By detecting the main flaw of the steel sheet, of the detection signals from the sensor, the peak value of the detection signal that does not reach the first threshold value is detected at predetermined distance intervals along the moving direction of the steel sheet. Of the plurality of peak values detected in this manner, a desired peak value is selected as a representative value of the plurality of peak values, and the selection of such a representative value is performed along the moving direction of the steel sheet. Repeat several times,
Then, an average value of the plurality of representative values selected in this way is calculated, and the average value thus calculated is calculated as a second value.
Setting as a threshold value, comparing the detection signal not reaching the first threshold value with the second threshold value, and detecting a minute flaw of the steel sheet by a detection signal exceeding the second threshold value, Flaw detection method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27218389A JP2906482B2 (en) | 1989-10-19 | 1989-10-19 | Steel sheet flaw detection method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27218389A JP2906482B2 (en) | 1989-10-19 | 1989-10-19 | Steel sheet flaw detection method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03134556A JPH03134556A (en) | 1991-06-07 |
| JP2906482B2 true JP2906482B2 (en) | 1999-06-21 |
Family
ID=17510244
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP27218389A Expired - Fee Related JP2906482B2 (en) | 1989-10-19 | 1989-10-19 | Steel sheet flaw detection method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2906482B2 (en) |
-
1989
- 1989-10-19 JP JP27218389A patent/JP2906482B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03134556A (en) | 1991-06-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |