JP4527238B2 - Ultrasonic rail flaw detector - Google Patents

Ultrasonic rail flaw detector Download PDF

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JP4527238B2
JP4527238B2 JP2000119459A JP2000119459A JP4527238B2 JP 4527238 B2 JP4527238 B2 JP 4527238B2 JP 2000119459 A JP2000119459 A JP 2000119459A JP 2000119459 A JP2000119459 A JP 2000119459A JP 4527238 B2 JP4527238 B2 JP 4527238B2
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rail
ultrasonic
receiving
reception
transmission
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JP2001305111A (en
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泉 佐藤
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Tokyo Keiki Inc
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Tokyo Keiki Inc
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/025—Change of phase or condition
    • G01N2291/0258—Structural degradation, e.g. fatigue of composites, ageing of oils
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/042—Wave modes
    • G01N2291/0421—Longitudinal waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/044—Internal reflections (echoes), e.g. on walls or defects

Description

【０００１】
【発明の属する技術分野】
本発明は、超音波を利用して、レールの底部腐食または腹部横裂を検出することができる超音波レール探傷装置に関する。
【０００２】
【従来の技術】
従来、鉄道レール等のレールの内部に存在する傷等の欠陥を超音波を利用して探傷する装置は、鉄道の保線現場で広く使用されている。レールの頂面である踏面からレール内に超音波を入射させて、内部の傷等からの反射エコーを検知することによって傷の存在を知ることができる。従来のレールの超音波探傷においては、図６に示すように、複数の超音波探触子を用いて様々な角度でレール１内に超音波を入射させて、レール１各部に発生する傷からの反射エコーを受信して、探傷している。代表的には、垂直探触子４０による超音波の屈折角が０°の縦波超音波、斜角探触子４２，４２による３５°〜４５°の横波超音波、斜角探触子４４，４４による７０°の横波超音波が利用されている。
【０００３】
図７に示すように、レール底部に発生する横裂１Ａについては、探触子からレール内へ入射した超音波が、コーナーで反射を繰り返して、結果として入射した方向に戻ってくることができるため、斜角探触子４２による３５°〜４５°の横波超音波を利用して感度良く検知することができる。
【０００４】
【発明が解決しようとする課題】
しかしながら、レール底部に発生する底部腐食については、必ずしも従来の探触子で十分な検知ができていない。これは、図８に示すように、レール底部の腐食１Ｂの場合、腐食１Ｂによる面の角度が寝ているために、探触子と異なる方向に反射してしまうこと、反射面が腐食１Ｂによる不規則な面のために散乱反射してしまい、受信信号が弱くなることなどから、十分な受信信号レベルが得られないことが理由として挙げられる。
【０００５】
また、垂直探触子４０による０°の縦波超音波を使用して、Ｂスコープを描く方法で底部腐食１Ｂを検知する方法も考えられるが、底面エコーのレベルが大きく、底部腐食１Ｂからの散乱反射が低いレベルであるため、受信増幅度を上げて画像を描かせ、さらに数ｍｍ程度のレール高さの違いを読み取らなければならず、装置が複雑になるという問題がある。
【０００６】
また、レール溶接部の腹部に発生する溶け込み不足の横裂のような欠陥１Ｃ（図９参照）については、面が平滑なために、入射させた超音波のほとんどの成分がレール底面方向に正反射してしまい、探触子の方向に戻ってくる成分が少ないので、ほとんど検知できないという問題がある。そのため、図９のように、２つの探触子（送信探触子４６と受信探触子４８）を利用して、手動で探触子を走査するタンデム探傷法が提案されて実施されている。しかしながら、この方法ではレールの頭部から底部までの全域を探傷するために、各探触子のレール前後方向の相対位置を移動させて、走査しなければならないので、レール上を走行しながら探傷する用途では、移動速度の制限がある等の問題がある。
【０００７】
また、探触子を走査しないで全域を探傷する方法として、広い開口面の探触子を使用する方法もあるが、探触子が大型化するため、コストが高くなるという問題がある。
【０００８】
本発明はかかる従来のレール探傷の持っている課題に鑑みなされたもので、第１の目的は、底部腐食を感度良く検出することができる超音波レール探傷装置を提供することである。
【０００９】
また、第２の目的は、タンデム探傷法を用いた超音波探傷装置において、送受信用振動子と受信用振動子との間の前後方向相対位置の調整の手間を低減することができる超音波レール探傷装置を提供することである。
【００１０】
また、第３の目的は、底部腐食と腹部横裂の両方を検出することができる超音波レール探傷装置を提供することである。
【００１１】
【課題を解決するための手段】
上記目的を達成するために請求項１記載の発明は、超音波を利用してレールを探傷しレール底部の腐食を検出する超音波レール探傷装置であって、レールの頂面に当接される送受信用振動子を備え、該送受信用振動子から屈折角１０°〜２５°の範囲にある縦波超音波をレール内へ入射し、レール底部の腐食で散乱した超音波の一部を該送受信用振動子で受信することを特徴とする。送受信用振動子からの縦波超音波の屈折角を１０°〜２５°の範囲にすることにより、底面エコーの影響を受けずに、レール底部の腐食で散乱された超音波を比較的良い感度で受信することができ、腐食の存在を知ることができる。
【００１４】
請求項２記載の発明は、前記送受信用振動子に対してレール前後方向に整列されレールに当接される受信用振動子をさらに備え、受信用振動子が前記送受信用振動子から放射され欠陥及びレール底面を反射してきた超音波を受信することを特徴とする。送受信用振動子から屈折角１０°〜２５°の縦波超音波が放射され、レール底部の腐食で散乱され戻ってきた縦波超音波を送受信用振動子で受信することにより、レール底部の腐食を検出することができる。また、レール内に欠陥があった場合に、送受信用振動子から放射された屈折角１０°〜２５°の縦波超音波が、レール内の欠陥で反射し、さらにレール底面で反射したものを受信用振動子で受信する、所謂タンデム探傷法を使用することにより、レール内部の欠陥を検出することができる。こうして、１つの送受信用振動子を共通に用いて、レール底部の腐食と、レール内部の横裂のような欠陥の両方を検出することができる。送受信用振動子から放射される縦波超音波の屈折角を１０°〜２５°の範囲にして、従来の横波超音波を使用した場合の屈折角よりも小さく設定することにより、送受信用振動子を大型化することなく、送受信用振動子から放射される超音波のレールの高さ方向の範囲を広げることができ、従って、送受信用振動子と受信用振動子との前後方向の相対位置の調整の手間を少なくして、レール内の欠陥の検出を行うことができる。
【００１５】
特に、請求項３記載の発明のように、レールの高さをｈとし、送受信用振動子からの縦波超音波の屈折角をθとしたときに、前記送受信用振動子のレールの幅方向と垂直な方向の大きさをｈ×ｓｉｎθとすることにより、送受信用振動子と受信用振動子との前後方向の相対位置を動かすことなく、送受信用振動子から送信される縦波超音波でレールの高さ方向全体のどこかにある欠陥を検出することができる。
【００１６】
また、請求項４記載の発明は、前記送受信用振動子と受信用振動子とは、それぞれ切換スイッチを介して同じ受信部に接続されることを特徴とする。切換スイッチを介して切り換えることで、同じ受信部を用いて、レール底部の腐食検出と、レール内部の欠陥検出とを切り換えることができる。
【００１７】
【発明の実施の形態】
以下、図面を用いて本発明の実施の形態を説明する。図１は、本発明の超音波レール探傷装置の実施形態を表す構成説明図、図２はレール探傷を行うときの状態を表す斜視図である。
【００１８】
この超音波レール探傷装置は、超音波パルスをレール１内に送信し、レール１の主に底部腐食１Ｂから反射されてくる反射エコーを受信する送受信用振動子１２と、送受信用振動子１２から送信された超音波パルスが主に腹部の欠陥１Ｃで反射して、レール底部で反射して戻ってくる反射エコーを受信する受信用振動子１４を有する超音波探触子１０を有している。この送受信用振動子１２と受信用振動子１４とは分割膜１６によって音響的に遮断されている。また、送受信用振動子１２の前面には、振動子１２で発生する超音波パルスを規定の入射角でレール１に入射させるための樹脂製シュー１８が設けられ、受信用振動子１４の前面には、レール１から入射された超音波を受信用振動子１４へと送るシュー１９が設けられる。超音波探触子１０には、送受信用振動子１２から超音波パルスを送出するための電気パルスを発生する送信部２０と、送受信用振動子１２で受信される信号を受信して増幅する受信部２２と、受信用振動子１４で受信される信号を受信して増幅する受信部２４と、が接続されている。また、受信部２２及び受信部２４には、それぞれ検知表示部２６，２８が接続されている。検知表示部２６，２８は、受信部２２，２４で所定閾値よりも大きな受信信号を受信した場合に、受信エコーがあったことを示すために表示するもので、ランプ等によって構成され、ランプの点灯により受信エコーがあったことが表示される。
【００１９】
送受信用振動子１２から発射された超音波パルスはシュー１８を経由してレール１に対して規定の角度を持って入射する。この規定の角度は、スネルの法則に従ってレール１内で１０°〜２５°の範囲内の屈折角θの縦波超音波、好ましくは１５°〜２０°の屈折角θの縦波超音波が発生するように選択される。
【００２０】
図１に示すように、送受信用振動子１２の略前後方向の大きさＬ、即ち、レールの幅方向と垂直な方向の大きさＬは、レールの高さをｈとしたときに、
【００２１】
【数１】
Ｌ＝ｈ×ｓｉｎθ （１）
を満足するように設定されている。また、送受信用振動子１２と受信用振動子１４の間の間隔Ｐは、概ね、
【００２２】
【数２】
Ｐ＝ｈ×ｔａｎθ （２）
を満足するように設定されている。但し、送受信用振動子１２と受信用振動子１４との間隔Ｐは、これに限るものではなく、送受信用振動子１２から発射されレール１の腹部の欠陥で反射して、レール底部で反射して戻ってくる超音波を受信することができるような範囲に受信用振動子１４を配置する。
【００２３】
以上のように構成される超音波レール探傷装置において、送受信用振動子１２から発射された超音波パルスは、屈折角θでレール１内へと入射される。レール１底部に腐食１Ｂや溶け込み不足による欠陥１Ｃがない場合には、超音波パルスはレール１底面で反射して、前方へ反射してしまい送受信用振動子１２に戻ってくることはない。
【００２４】
これに対してレール１に底部腐食１Ｂがある場合には、図３に示すように、超音波は腐食部１Ｂで散乱反射して、一部の超音波が送受信用振動子１２に戻ってくる。この反射エコーは、送受信用振動子１２で電気信号に変換され、受信部２２で増幅され、検知表示部２６で表示が行われる。この表示からレール１に底部腐食１Ｂが存在することを知ることができる。屈折角θが１０°〜２５°、好ましくは１５°〜２０°となっており、比較的小さい角度となっているため、底部腐食１Ｂに対して散乱反射が送受信用振動子１２に戻ってきやすい構成となっている。その一方で、垂直探触子の場合と異なり、屈折角θが０°より大きいため、底面エコーの影響を大幅に低減することができる。
【００２５】
図１０及び図１１は、屈折角θと底部腐食検出性能との関係を求めた実験例である。複数の屈折角を実現するために、アクリル製のシュー１８を製作し、送受信用振動子と組み合わせて、底部腐食の検知性能を評価した。評価は、複数の屈折角について、底部腐食からのエコーレベルと、底部腐食のない健全レールの底面からのエコーレベルを測定し、ＳＮ比を比較することにより行った。実験に用いた部品を、次表に示す。
【００２６】
【表１】

Figure 0004527238
測定方法は、まず図１０（ａ）に示すように、φ５の横穴のエコーレベルにより基準化を行い、図１０（ｂ）の健全レールの底部のエコーレベル測定を行い、図１０（ｃ）の腐食レールのエコーレベル測定を行い、それぞれの屈折角におけるＳＮ比を比較した。その測定結果を次表及び図１１に示す。
【００２７】
【表２】
Figure 0004527238
上記測定結果から分かるように、屈折角１０°〜２５°の角度でＳＮ比が良く、特に１５°では感度も良い。このような屈折角の範囲となるように、送受信用振動子１２の屈折角を設定すると効果的である。
【００２８】
次に、図４に示すように、レール１の溶接部等に発生する可能性の高い溶け込み不足のような垂直な平面の横裂１Ｃがある場合、送受信用振動子１２から送出された超音波パルスは、この横裂１Ｃで反射して、さらにレール１底面で反射し、受信用振動子１４で受信される。この信号は受信部２４で増幅され、検知表示部２８で表示が行われる。この表示からレール１の腹部に横裂が存在することを検知することができる。送受信用振動子１２が（１）式を満足することにより、横裂１Ｃがレール１の高さのどの位置にあったとしても、送受信用振動子１２から放射される超音波は、レール１高さ全体をカバーし、必ず、超音波パルスはその横裂１Ｃで反射される。受信用振動子１４が（２）式を満足することにより、反射された超音波パルスは底面で反射し、確実に受信用振動子１４で受信される。この横裂１Ｃを検出する場合、屈折角θは、必ずしも１０°〜２５°となっている必要がなく、それ以外の角度であっても検出することができるが、あまり屈折角が大きいとＬが大きくなり、超音波探触子１０が大型化する。しかしながら、上記角度範囲の屈折角とすることにより、超音波探触子１０の大型化を回避することができる。
【００２９】
図５は、本発明の第２の実施形態を表す図である。図において、第１実施形態と同一の部材は同一の符号を付して、その詳細説明を省略する。
【００３０】
この実施形態では、第１実施形態の受信部２４及び検知表示部２８を省略し、その代わりに、切換スイッチ３０が受信部２２と、送受信用振動子１２及び受信用振動子１４との間に設けられている点で異なっており、受信部２２が選択的に送受信用振動子１２または受信用振動子１４と接続できるようになっている。
【００３１】
切換スイッチ３０を切り換えることで、同じ受信部２２及び検知表示部２６を用いて、目的に応じて底部腐食１Ｂ検知と、横裂１Ｃ検知とを切り換えることができる。
【００３２】
以上の各実施形態では、１つの送受信用振動子１２で底部腐食１Ｂ検知と横裂１Ｃ検知とを行っているため、振動子の数を低減でき、探傷車両等の床下スペースが少なくてすむようになる。
【００３３】
【発明の効果】
以上説明したように、請求項１記載の発明によれば、送受信用振動子からの縦波超音波の屈折角を１０°〜２５°の範囲にすることにより、底面エコーの影響を受けずに、レール底部の腐食で散乱された超音波を比較的良い感度で受信することができ、腐食の存在を検出することができる。
【００３６】
請求項２記載の発明によれば、１つの送受信用振動子を共通に用いて、レール底部の腐食と、レール内部の横裂のような欠陥の両方を検出することができる。送受信用振動子から放射される縦波超音波の屈折角を１０°〜２５°の範囲にして、従来の横波超音波を使用した場合の屈折角よりも小さく設定することにより、送受信用振動子を大型化することなく、送受信用振動子から放射される超音波のレールの高さ方向の範囲を広げることができ、従って、送受信用振動子と受信用振動子との前後方向の相対位置を動かすことなく、レール内の欠陥の検出を行うことができる。
【００３７】
請求項３記載の発明によれば、送受信用振動子と受信用振動子との前後方向の相対位置を動かすことなく、送受信用振動子から送信される縦波超音波でレールの高さ方向全体のどこかにある欠陥を検出することができる。
【００３８】
請求項４記載の発明によれば、同じ受信部を用いて、レール底部の腐食検出と、レール内部の欠陥検出とを切り換えることができる。
【図面の簡単な説明】
【図１】本発明の超音波レール探傷装置の実施形態を表す構成図である。
【図２】図１の超音波レール探傷装置の斜視図である。
【図３】図１の超音波レール探傷装置のレール底部の腐食検出の原理を表す説明図である。
【図４】図１の超音波レール探傷装置の腹部横裂検出の原理を表す説明図である。
【図５】本発明の超音波レール探傷装置の第２の実施形態を表すブロック図である。
【図６】従来の超音波レール探傷装置を表す構成図である。
【図７】レール底部に発生する横裂に対する超音波の反射を表す説明図である。
【図８】レール底部の腐食に対する超音波の反射を表す説明図である。
【図９】従来のタンデム探傷法による超音波レール探傷装置の構成図である。
【図１０】（ａ）〜（ｃ）は屈折角と底部腐食検出性能との関係を求めるための実験例を表す説明図である。
【図１１】図１０の実験結果を表すグラフである。
【符号の説明】
１ レール
１Ｂ 底部の腐食
１Ｃ 腹部横裂
１２ 送受信用振動子
１４ 受信用振動子
２２ 受信部
３０ 切換スイッチ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic rail flaw detector capable of detecting rail bottom corrosion or abdominal lateral fissure using ultrasonic waves.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an apparatus for detecting defects such as scratches existing inside rails such as railroad rails using ultrasonic waves has been widely used in railway track maintenance sites. The presence of a flaw can be known by making an ultrasonic wave enter the rail from the tread, which is the top surface of the rail, and detecting a reflection echo from an internal flaw or the like. In the conventional ultrasonic flaw detection of a rail, as shown in FIG. 6, ultrasonic waves are incident on the rail 1 at various angles using a plurality of ultrasonic probes, and from the flaws generated in each part of the rail 1 The reflected echo is received and the flaw is detected. Typically, a longitudinal wave ultrasonic wave having an ultrasonic refraction angle of 0 ° by the vertical probe 40, a transverse wave ultrasonic wave of 35 ° to 45 ° by the oblique angle probes 42 and 42, and the oblique angle probe 44. , 44 is used.
[0003]
As shown in FIG. 7, with respect to the transverse crack 1A generated at the bottom of the rail, the ultrasonic wave incident from the probe into the rail can be repeatedly reflected at the corner, and can return to the incident direction as a result. Therefore, it is possible to detect with high sensitivity using the transverse wave ultrasonic waves of 35 ° to 45 ° by the oblique angle probe 42.
[0004]
[Problems to be solved by the invention]
However, the bottom corrosion that occurs at the bottom of the rail cannot always be sufficiently detected by a conventional probe. As shown in FIG. 8, in the case of the corrosion 1B at the bottom of the rail, the angle of the surface due to the corrosion 1B lies down, so that it reflects in a direction different from the probe, and the reflection surface is due to the corrosion 1B. The reason is that a sufficient received signal level cannot be obtained because the received signal becomes weak due to scattering and reflection due to an irregular surface.
[0005]
In addition, a method of detecting bottom corrosion 1B by drawing a B scope using 0 ° longitudinal ultrasonic waves from the vertical probe 40 is also conceivable. However, the level of bottom echo is large and the bottom corrosion 1B is detected. Since the scattered reflection is at a low level, an image is drawn with an increased reception amplification level, and a difference in rail height of about several millimeters must be read, resulting in a complicated apparatus.
[0006]
In addition, for the defect 1C (see FIG. 9) such as a transverse crack with insufficient penetration that occurs in the abdomen of the rail welded portion, since the surface is smooth, most components of the incident ultrasonic waves are normal in the rail bottom direction. Since there are few components that are reflected and return in the direction of the probe, there is a problem that almost no detection is possible. For this reason, as shown in FIG. 9, a tandem flaw detection method in which a probe is manually scanned using two probes (a transmission probe 46 and a reception probe 48) has been proposed and implemented. . However, in this method, in order to detect the entire region from the top to the bottom of the rail, the relative position of each probe in the rail front-rear direction must be moved and scanned. In such applications, there is a problem that there is a restriction on the moving speed.
[0007]
Further, as a method for flaw detection over the entire area without scanning the probe, there is a method using a probe with a wide opening surface, but there is a problem that the cost increases because the probe becomes large.
[0008]
The present invention has been made in view of the problems of the conventional rail flaw detection, and a first object thereof is to provide an ultrasonic rail flaw detection apparatus capable of detecting bottom corrosion with high sensitivity.
[0009]
A second object is, ultrasonic waves can be in the ultrasonic flaw detection apparatus using the tandem flaw detection method, reducing the labor for adjustment of the longitudinal relative position between the receiving oscillator and feeding receiving credit vibrator A rail flaw detector is provided.
[0010]
A third object is to provide an ultrasonic rail flaw detector capable of detecting both bottom corrosion and abdominal lateral fissure.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is an ultrasonic rail flaw detector for detecting corrosion of a rail bottom by detecting a rail using ultrasonic waves, and is brought into contact with the top surface of the rail. A transmission / reception vibrator is provided, and longitudinal wave ultrasonic waves having a refraction angle of 10 ° to 25 ° are incident on the rail from the transmission / reception vibrator, and a part of the ultrasonic waves scattered by corrosion at the bottom of the rail is transmitted / received. It is characterized by receiving with a vibrator. By setting the refraction angle of longitudinal ultrasonic waves from the transmitting / receiving transducer to a range of 10 ° to 25 °, the ultrasonic waves scattered by corrosion at the bottom of the rail are relatively sensitive without being affected by the bottom echo. And can know the presence of corrosion.
[0014]
According to a second aspect of the invention, further comprising a receiving credit vibrator wherein Ru is in contact with the aligned rails in rail longitudinal direction with respect to the transmitting and receiving transducers, the receiving credit oscillator is radiated from the transmitting and receiving transducers defects And receiving ultrasonic waves reflected from the bottom of the rail. Corrosion at the bottom of the rail is caused by receiving longitudinal wave ultrasonic waves radiated from the transmitting / receiving transducer with a refraction angle of 10 ° to 25 ° and scattered back by corrosion at the bottom of the rail with the transmitting / receiving transducer. Can be detected. In addition, when there is a defect in the rail, longitudinal wave ultrasonic waves with a refraction angle of 10 ° to 25 ° radiated from the transmitting / receiving transducer are reflected by the defect in the rail and further reflected by the rail bottom surface. By using a so-called tandem flaw detection method that is received by a receiving vibrator, it is possible to detect a defect inside the rail. In this way, it is possible to detect both corrosion at the bottom of the rail and defects such as lateral cracks inside the rail by using one transmission / reception vibrator in common. By setting the refraction angle of the longitudinal ultrasonic wave radiated from the transmission / reception vibrator to a range of 10 ° to 25 ° and setting it to be smaller than the refraction angle when the conventional transverse wave ultrasonic wave is used, the transmission / reception vibrator Without increasing the size, the range of the height direction of the rail of the ultrasonic wave radiated from the transmitting / receiving transducer can be expanded, and therefore the relative position in the front-rear direction between the transmitting / receiving transducer and the receiving transducer can be increased. It is possible to detect a defect in the rail with less adjustment work.
[0015]
In particular, as in the invention of claim 3 , when the height of the rail is h and the refraction angle of longitudinal ultrasonic waves from the transmission / reception transducer is θ, the width direction of the rail of the transmission / reception transducer By setting the size in the direction perpendicular to h × sin θ, the longitudinal ultrasonic waves transmitted from the transmitting / receiving transducer can be used without moving the relative position of the transmitting / receiving transducer and the receiving transducer in the front-rear direction. A defect somewhere in the entire height direction of the rail can be detected.
[0016]
The invention according to claim 4 is characterized in that the transmitting / receiving transducer and the receiving transducer are each connected to the same receiving section via a changeover switch. By switching via the changeover switch, it is possible to switch between corrosion detection at the rail bottom and defect detection inside the rail using the same receiver.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a structural explanatory view showing an embodiment of an ultrasonic rail flaw detector of the present invention, and FIG. 2 is a perspective view showing a state when rail flaw detection is performed.
[0018]
This ultrasonic rail flaw detector transmits an ultrasonic pulse into the rail 1, and receives a reflected echo reflected mainly from the bottom corrosion 1 B of the rail 1. It has an ultrasonic probe 10 having a receiving transducer 14 that receives a reflected echo that is reflected by an abdominal defect 1C and is reflected by the bottom of the rail and then returned. . The transmission / reception vibrator 12 and the reception vibrator 14 are acoustically cut off by the dividing film 16. Further, a resin shoe 18 is provided on the front surface of the transmitting / receiving transducer 12 so that an ultrasonic pulse generated by the transducer 12 is incident on the rail 1 at a predetermined incident angle. Is provided with a shoe 19 for sending ultrasonic waves incident from the rail 1 to the receiving vibrator 14. The ultrasonic probe 10 includes a transmission unit 20 that generates an electrical pulse for transmitting an ultrasonic pulse from the transmission / reception transducer 12, and reception that receives and amplifies a signal received by the transmission / reception transducer 12. The unit 22 and a receiving unit 24 that receives and amplifies a signal received by the receiving transducer 14 are connected. Detection display units 26 and 28 are connected to the reception unit 22 and the reception unit 24, respectively. The detection display units 26 and 28 are configured to display a reception echo when the reception units 22 and 24 receive a reception signal larger than a predetermined threshold, and are configured by a lamp or the like. Illumination indicates that there was a reception echo.
[0019]
The ultrasonic pulse emitted from the transmitting / receiving transducer 12 is incident on the rail 1 through the shoe 18 with a specified angle. According to Snell's law, this prescribed angle is generated by longitudinal ultrasonic waves with a refraction angle θ in the range of 10 ° to 25 ° within the rail 1, preferably longitudinal ultrasonic waves with a refraction angle θ of 15 ° to 20 °. Selected to do.
[0020]
As shown in FIG. 1, the size L in the substantially front-rear direction of the transducer 12 for transmission / reception, that is, the size L in the direction perpendicular to the width direction of the rail is defined as follows.
[0021]
[Expression 1]
L = h × sin θ (1)
Is set to satisfy. The interval P between the transmitting / receiving transducer 12 and the receiving transducer 14 is approximately
[0022]
[Expression 2]
P = h × tan θ (2)
Is set to satisfy. However, the interval P between the transmitting / receiving transducer 12 and the receiving transducer 14 is not limited to this, and is reflected from the defect in the abdomen of the rail 1 emitted from the transmitting / receiving transducer 12 and reflected from the bottom of the rail. The receiving transducer 14 is arranged in a range in which the ultrasonic waves that are returned can be received.
[0023]
In the ultrasonic rail flaw detector configured as described above, the ultrasonic pulse emitted from the transmission / reception transducer 12 is incident on the rail 1 at the refraction angle θ. If there is no corrosion 1B or defect 1C due to insufficient penetration at the bottom of the rail 1, the ultrasonic pulse is reflected from the bottom of the rail 1 and reflected forward, and does not return to the transmitting / receiving transducer 12.
[0024]
On the other hand, when the rail 1 has the bottom corrosion 1B, as shown in FIG. 3, the ultrasonic waves are scattered and reflected by the corrosion portion 1B, and a part of the ultrasonic waves returns to the transmitting / receiving transducer 12. . The reflected echo is converted into an electric signal by the transmitting / receiving transducer 12, amplified by the receiving unit 22, and displayed on the detection display unit 26. From this display, it can be known that the bottom corrosion 1B exists on the rail 1. Since the refraction angle θ is 10 ° to 25 °, preferably 15 ° to 20 ° and is a relatively small angle, scattered reflection easily returns to the transmitting / receiving transducer 12 with respect to the bottom corrosion 1B. It has a configuration. On the other hand, unlike the case of the vertical probe, since the refraction angle θ is larger than 0 °, the influence of the bottom surface echo can be greatly reduced.
[0025]
10 and 11 are experimental examples in which the relationship between the refraction angle θ and the bottom corrosion detection performance is obtained. In order to realize a plurality of refraction angles, an acrylic shoe 18 was manufactured and combined with a transmission / reception vibrator to evaluate the bottom corrosion detection performance. The evaluation was performed by measuring the echo level from the bottom corrosion and the echo level from the bottom surface of the healthy rail without the bottom corrosion for a plurality of refraction angles, and comparing the SN ratio. The parts used in the experiment are shown in the following table.
[0026]
[Table 1]
Figure 0004527238
First, as shown in FIG. 10 (a), the measurement method is standardized by the echo level of the φ5 horizontal hole, and the echo level measurement of the bottom of the healthy rail in FIG. 10 (b) is performed. The echo level measurement of the corrosion rail was performed, and the SN ratio at each refraction angle was compared. The measurement results are shown in the following table and FIG.
[0027]
[Table 2]
Figure 0004527238
As can be seen from the measurement results, the SN ratio is good at an angle of refraction of 10 ° to 25 °, and the sensitivity is particularly good at 15 °. It is effective to set the refraction angle of the transducer 12 for transmission / reception so that the refraction angle is in such a range.
[0028]
Next, as shown in FIG. 4, when there is a vertical plane transverse crack 1 </ b> C that is likely to occur in the welded portion of the rail 1 or the like, the ultrasonic wave transmitted from the transmitting / receiving transducer 12 is transmitted. The pulse is reflected by the lateral crack 1 </ b> C, further reflected by the bottom surface of the rail 1, and received by the receiving transducer 14. This signal is amplified by the receiving unit 24 and displayed on the detection display unit 28. From this display, it can be detected that a lateral fissure exists in the abdomen of the rail 1. When the transmission / reception transducer 12 satisfies the expression (1), the ultrasonic wave radiated from the transmission / reception transducer 12 is high in the rail 1 regardless of the position of the transverse crack 1C in the height of the rail 1. The ultrasonic pulse is always reflected by the transverse crack 1C. When the receiving transducer 14 satisfies the expression (2), the reflected ultrasonic pulse is reflected by the bottom surface and is reliably received by the receiving transducer 14. When detecting this lateral crack 1C, the refraction angle θ does not necessarily have to be 10 ° to 25 °, and it can be detected even at other angles, but if the refraction angle is too large, L Becomes larger, and the ultrasonic probe 10 becomes larger. However, an increase in the size of the ultrasonic probe 10 can be avoided by setting the refraction angle within the above-mentioned angle range.
[0029]
FIG. 5 is a diagram illustrating a second embodiment of the present invention. In the figure, the same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
[0030]
In this embodiment, the receiving unit 24 and the detection display unit 28 of the first embodiment are omitted, and instead, the changeover switch 30 is interposed between the receiving unit 22, the transmitting / receiving transducer 12 and the receiving transducer 14. The receiving unit 22 can be selectively connected to the transmitting / receiving transducer 12 or the receiving transducer 14.
[0031]
By switching the changeover switch 30, it is possible to switch between the bottom corrosion 1B detection and the lateral crack 1C detection according to the purpose, using the same receiving unit 22 and detection display unit 26.
[0032]
In each of the above embodiments, since the bottom corrosion 1B detection and the lateral crack 1C detection are performed by one transmission / reception vibrator 12, the number of vibrators can be reduced, and the space under the floor of a flaw detection vehicle or the like can be reduced. Become.
[0033]
【The invention's effect】
As described above, according to the first aspect of the present invention, the refraction angle of the longitudinal ultrasonic wave from the transmitting / receiving transducer is set within the range of 10 ° to 25 °, so that it is not affected by the bottom echo. The ultrasonic waves scattered by corrosion at the bottom of the rail can be received with relatively good sensitivity, and the presence of corrosion can be detected.
[0036]
According to the second aspect of the present invention, it is possible to detect both corrosion at the bottom of the rail and a defect such as a lateral crack inside the rail by using one transmission / reception vibrator in common. By setting the refraction angle of the longitudinal ultrasonic wave radiated from the transmission / reception vibrator to a range of 10 ° to 25 ° and setting it to be smaller than the refraction angle when the conventional transverse wave ultrasonic wave is used, the transmission / reception vibrator Without increasing the size, the range of the height direction of the rail of the ultrasonic wave radiated from the transmitting / receiving transducer can be expanded, and accordingly, the relative position in the front-rear direction between the transmitting / receiving transducer and the receiving transducer can be increased. It is possible to detect a defect in the rail without moving it.
[0037]
According to the third aspect of the present invention, the longitudinal height of the rail is entirely transmitted by the longitudinal ultrasonic wave transmitted from the transmitting / receiving transducer without moving the relative position between the transmitting / receiving transducer and the receiving transducer in the front-rear direction. It is possible to detect a defect somewhere.
[0038]
According to the fourth aspect of the present invention, it is possible to switch between corrosion detection at the rail bottom and defect detection inside the rail using the same receiver.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of an ultrasonic rail flaw detector according to the present invention.
FIG. 2 is a perspective view of the ultrasonic rail flaw detector shown in FIG.
3 is an explanatory view showing the principle of corrosion detection at the rail bottom of the ultrasonic rail flaw detector shown in FIG. 1; FIG.
4 is an explanatory diagram showing the principle of abdominal transverse crack detection in the ultrasonic rail flaw detector of FIG. 1. FIG.
FIG. 5 is a block diagram showing a second embodiment of the ultrasonic rail flaw detector according to the present invention.
FIG. 6 is a block diagram showing a conventional ultrasonic rail flaw detector.
FIG. 7 is an explanatory diagram showing reflection of ultrasonic waves with respect to a lateral crack generated at the bottom of the rail.
FIG. 8 is an explanatory diagram showing reflection of ultrasonic waves with respect to corrosion at the bottom of the rail.
FIG. 9 is a configuration diagram of an ultrasonic rail flaw detector by a conventional tandem flaw detection method.
FIGS. 10A to 10C are explanatory diagrams showing an experimental example for obtaining the relationship between the refraction angle and the bottom corrosion detection performance. FIGS.
11 is a graph showing the experimental results of FIG.
[Explanation of symbols]
1 Rail 1B Bottom Corrosion 1C Abdominal Lateral Crack 12 Transmitter / Transmitter 14 Receiver Vibrator 22 Receiver 30 Switch

Claims (4)

超音波を利用してレールを探傷しレール底部の腐食を検出する超音波レール探傷装置であって、レールの頂面に当接される送受信用振動子を備え、該送受信用振動子から屈折角１０°〜２５°の範囲にある縦波超音波をレール内へ入射し、レール底部の腐食部で散乱した超音波の一部を該送受信用振動子で受信することを特徴とする超音波レール探傷装置。  An ultrasonic rail flaw detector that detects a rail bottom by detecting a rail using ultrasonic waves, and includes a transmission / reception vibrator that is in contact with the top surface of the rail, and a refraction angle from the transmission / reception vibrator. An ultrasonic rail characterized in that longitudinal ultrasonic waves in a range of 10 ° to 25 ° are incident on the rail, and a part of the ultrasonic waves scattered by the corroded portion at the bottom of the rail is received by the transmitting / receiving transducer. Flaw detection equipment. 前記送受信用振動子に対してレール前後方向に整列されレールに当接される受信用振動子をさらに備え、受信用振動子は前記送受信用振動子から放射され欠陥及びレール底面を反射してきた超音波を受信することを特徴とする請求項１記載の超音波レール探傷装置。 Further comprising a receiving transducer that is in contact with the aligned rails in rail longitudinal direction with respect to the transmitting and receiving transducers, receiving credit vibrator has been reflected by the defect and the rail bottom surface is emitted from the transmitting and receiving transducers Ultra The ultrasonic rail flaw detector according to claim 1, wherein the ultrasonic rail flaw detector receives a sound wave. レールの高さをｈとし、送受信用振動子からの縦波超音波の屈折角をθとしたときに、前記送受信用振動子のレールの幅方向と垂直な方向の大きさをｈ×ｓｉｎθとすることを特徴とする請求項２記載の超音波レール探傷装置。When the height of the rail is h and the refraction angle of the longitudinal ultrasonic wave from the transmission / reception transducer is θ, the size in the direction perpendicular to the rail width direction of the transmission / reception transducer is h × sinθ. The ultrasonic rail flaw detector according to claim 2 . 前記送受信用振動子と受信用振動子とは、それぞれ切換スイッチを介して同じ受信部に接続されることを特徴とする請求項２または３記載の超音波レール探傷装置。Wherein the transmission and reception oscillator for the receiving oscillator, an ultrasonic rail flaw detection apparatus according to claim 2 or 3, wherein being respectively connected to the same receiver unit via the switch.
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