JP2004129145A

JP2004129145A - Manufacturing method for matching material and ultrasonic sensor using it

Info

Publication number: JP2004129145A
Application number: JP2002293854A
Authority: JP
Inventors: Masahiko Ito; 伊藤　雅彦; Akihisa Adachi; 足立　明久; Yukinori Ozaki; 尾崎　行則; Masato Sato; 佐藤　真人
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2002-10-07
Filing date: 2002-10-07
Publication date: 2004-04-22
Anticipated expiration: 2022-10-07
Also published as: JP4082165B2

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the defective molding of a matching material resulting from a hot setting process. <P>SOLUTION: The mold shrinkage factor of the matching material is lowered by hot-setting the mixture of a hollow sphere and a binding material by stages in a low-temperature curing process on the low temperature side and a high-temperature curing process on the high temperature side, holding the glass transition point of the binding material. An ultrasonic sensor using the matching material is provided. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、超音波を利用して気体や液体の流量測定、流速測定する超音波流量計の整合層の製造方法およびそれを用いた超音波センサに関するものである。
【０００２】
【従来の技術】
従来の整合層の製造方法は例えば、図７（ａ）に示すように中空球体２７と樹脂２８の混合物からなる整合層と筒状部材２９からなる負荷ケースが一体成形されている。そして、図７（ｂ）のように圧電体の共振周波数の１／４波長に相当する厚みにカットする。そして以上のように作成した整合層３０を用いて、図７（ｃ）に示すように、整合層３０を圧電振動子３１に載置して、超音波振動子の形成方法が公開されている（特許文献１参照）。
【０００３】
また、ガラスバルーンと樹脂の混合体による整合層の製造方法については、圧電体からの発生する超音波の波長よりも小さい粒径の気泡を樹脂に混入する整合層が示されているものもある（特許文献２参照）。
【０００４】
【特許文献１】
特公平６−１０１８８０号公報（第１図）
【特許文献２】
特開平１１−２１５５９４号公報
【０００５】
【発明が解決しようとする課題】
しかし、この従来の製造方法を用いた整合層は、筒状部材に中空球体と樹脂を混合して熱硬化させて作成するため、樹脂硬化条件によっては、樹脂の収縮が発生し筒状内部壁面と整合層界面間に亀裂が生じたり、整合層にも変色、変形や割れが発生するなどの課題があった。これは、樹脂を加熱することにより、樹脂自体の自己発熱や樹脂成分の急激な化学変化のために、樹脂自体の組成変化が起こるためである。整合層内に亀裂等が入るため、図７（ｂ）のように筒状部材を所定の厚みにカットした整合層群はそれぞれ１枚ごとに、密度が不均一な整合層が作成されてしまう課題があった。
【０００６】
また、超音波の波長よりも小さい粒径の気泡を樹脂に混入することは、非常に困難であり、混入する気泡の大きさを制御することができない。また樹脂中に気泡を混入することで作成された整合層の密度は作成数ごとに異なり、一定の音響インピーダンスを得ることができない。
【０００７】
本発明は、前記従来の課題を解決するもので、成型不良のない安定した整合層を有し、整合層密度のばらつきを低減した整合部材およびその製造方法と超音波センサを提供することを目的とする。
【０００８】
【課題を解決するための手段】
前記の従来の課題を解決するために、本発明の整合層の製造方法は、中空球体と結合材料の混合物を、所定温度より低い温度領域で低温硬化させ、さらに所定温度より高い高温領域で高温硬化させる製造方法で整合部材を作成するので、樹脂の硬化条件に起因する整合層の成型不良を解決することができる。したがって、整合部材中のどの箇所の所定厚みの整合層を取り出しても、本発明整合層の密度は均一となり、密度ばらつきも低減する。
【０００９】
【発明の実施の形態】
請求項１に記載の発明は、中空球体と前記中空球体を包囲する結合材料からなる混合物であって、前記混合物は所定温度より低い度領域で硬化された低温度硬化工程および所定温度より高い温度領域で硬化された高温度硬化工程を実施して整合部材が製造されるので、結合材料の硬化工程に起因する整合部材の成型収縮等による成型不良がなくなり、整合部材のどの部分でも密度均一な整合部材が作成できる。
【００１０】
請求項２に記載の発明は、所定温度が結合材料の熱変形温度であるので、硬化条件として樹脂の特性変曲点を境にして低温硬化と高温硬化を経て樹脂を硬化させるので、整合部材内の割れ、亀裂がなくなり、樹脂の熱膨張、熱収縮に起因する成型不良がなくなり、成型寸法が安定する。
【００１１】
請求項３に記載の発明は、所定温度が結合材料のガラス転移温度であるので、硬化条件として樹脂の温度変化による線膨張係数を境界にして低温硬化と高温硬化を経て樹脂を硬化させるので、樹脂の熱膨張、熱収縮に起因する成型不良がなくなり、成型寸法が安定する。
【００１２】
請求項４に記載の発明は、整合部材は、整合部材作成治具内に中空球体と結合材料の混合物を充填した後、前記整合部材作成治具と共に、連続して低温硬化工程および高温硬化工程を実施する整合部材の製造方法であるので、結合材料硬化の際、結合材料が急激な温度上昇なしに徐々に硬化が進行するので整合部材内部で歪みがなくなり、亀裂や成型不良等の形状異常をなくすことができる。
【００１３】
請求項５に記載の発明は、整合部材は、整合部材作成治具から低温硬化工程および高温硬化工程を実施して取り出した前記整合部材を固定する固定治具を切断装置に設置して前記整合部材を切断する切断工程と同時に、切断時に前記整合部材の残留物が前記整合層表面上に付着しない洗浄工程を実施してなるので、低温硬化工程から高温硬化工程を経た整合部材作成治具内に作成した整合部材を取り出して、所定の厚さに切断研磨しながら切断研磨表面を洗浄するため、研磨時に発生する研磨残留物が表面に付着しない整合層を提供することができる。
【００１４】
請求項６記載の発明は、中空球体と結合材料の混合物を整合部材作成治具内に充填した後、前記整合部材作成治具と共に低温硬化工程を実施し、その後前記整合部材作成治具から前記整合部材を取り出して、前記整合部材を加工した後、前記整合部材に高温硬化工程を実施してなるため、熱形温度に到達する前に整合部材を加工するので、整合部材の加工工程を容易に実施することができ、さらに整合部材を加工後、整合部材を熱変形温度以上の高温硬化工程に通過させるので、結合材料の収縮による整合部材寸法の成型不良を防止することができる。
【００１５】
請求項７記載の発明は、加工と同時に前記整合部材の残留物が前記整合層表面上に付着しない洗浄工程を実施してなるので、所定の厚みの切断加工および洗浄後の整合層に、熱変形温度以上である高温硬化工程を実施するため、整合層表面は切断加工時に発生する残留物が付着することなく結合材料の収縮による整合層寸法の成型不良を防止することができる。
【００１６】
請求項８記載の発明は、中空球体はガラス組成成分からなるので、中空状態を保持したまま結合材料との混合による整合部材を形成することができ、整合層周囲温度が変化による中空球体の中空状態は保持され、整合層密度の安定化を図ることができる。
【００１７】
請求項９記載の発明は、結合材料は熱硬化性樹脂化合物であるので、樹脂化合物が中空球体表面界面とのぬれ性がよく、中空球体表面に密着する。そして、結合材料は低温硬化および高温硬化工程を経て熱硬化されるので、結合材料は自身の自己発熱により整合部材の強度劣化や変色を起こすことはない。
【００１８】
請求項１０記載の発明は、天部と側壁部を有する筒状ケースと前記天部の内壁面に固定された圧電体と前記天部外壁面に接着層を介して設置された請求項１から９の少なくとも１項記載の整合層と前記側壁部の外壁部に設けた支持部とからなるものであり、付着物のない整合層を用いるため整合層表面とケース天部表面との密着性が向上し、圧電体からの振動がケースを介して効率よく整合層に伝播させることができる超音波センサを提供することができ、また、整合層内部に亀裂等欠陥のない密度安定な整合層を得ることができるので、個々のセンサ間の特性ばらつきがない超音波センサを提供することができる。
【００１９】
【実施例】
以下、本説明の実施例について図表を用いて説明する。
【００２０】
（実施例１）
図１は、本発明の第１実施例における整合部材の製造工程の概略図である。
【００２１】
図１において、１は整合層作成治具である。２は、整合層作成治具１に設けられた貫通孔である。整合部材作成治具１の貫通孔２内に中空球体と結合材料の混合体を作成して、本発明整合部材１を作成する。３は中空構造を有するガラス中空体である。ガラス中空体３はそれぞれ１０〜１００μｍの粒径を有し、平均粒径は約６０μｍである。ガラス中空体は他の充填剤と比較して、比重が軽く、耐熱性、耐圧性、耐衝撃性を有し、充填材として使用したときの充填物の寸法安定性、成型性などの物性を改良できる。使用したガラスの組成はホウケイ酸系ガラスである。このガラス中空体は、酸化珪素、硼酸、炭酸カルシウム、炭酸ナトリウム、硫酸ナトリウム等の原料を１０００℃以上の高温で溶融して硫黄分を多含するガラスを形成させた後、ガラスを粉砕後、このガラス微粉末を火炎中に分散、滞留させることにより、硫黄分を発泡剤成分として発泡させて作成している。
【００２２】
また、ガラス中空体と結合材料を密接に結合させるために表面改質材を、ガラス中空体表面に形成しているガラス中空体もあるが、そのガラス中空体を使用しても何ら不都合はない。ガラス中空体３は、比重約０．１６ｇ／ｃｃである。使用する前にガラス中空体３は、ガラスデシケータ内に設置し、そのデシケータごと熱風乾燥循環炉内に設置し、１００℃で１２時間乾燥させた後のサンプルを使用する。ガラス中空体３のガラス表面に付着する水分を完全に除去するためである。ガラス中空体３表面に水分が残留していると後にガラス中空体３と結合材料を硬化反応させるとき、水分が結合材料とガラス中空体３の化学結合による結合を妨害し、ガラス中空体３と結合材料間に微小空隙層を形成してしまい、整合部材の機械強度を低下させることがある。
【００２３】
図１に示すように整合層作成治具１に貫通孔２を設け、貫通孔２内に、乾燥後ガラス中空体３を投入する。このとき図２に示すように、整合層作成治具１を加振装置１１に設置した上で、整合層作成治具１全体を振動させながらガラス中空体３を投入する。加振装置の加振強度は、縦振動のみで、周波数６０Ｈｚ、約５Ｇである。この作業工程の整合層作成治具１を加振させることにより、整合層作成治具１の貫通孔２内に投入されるガラス中空体３間の空隙を埋めるような状態で貫通孔２内に収まっていく。これは、ガラス中空体３の外部壁面が表面改質材の被覆層を形成しているので、ガラス中空体３の流動性が高いために、ガラス中空体３間の壁面が接触しても滞留することなくガラス中空体３が動いて貫通孔２内で最密充填状態になるためである。そのため、ガラス中空体３同志間では、最小の空隙しか存在していない。このようにガラス中空体３を充填した整合層治具１は、貫通孔２上下にフィルター４を設置した後、整合部材作成治具１上に貫通孔２内に結合材料を含浸させる。ここで、結合材料として熱硬化性樹脂化合物であるエポキシ樹脂を用いた。
【００２４】
硬化後の樹脂の形状変化が小さく、長期安定性に優れているためであり、何より、ガラス中空体３表面に対して濡れ性良く馴染むために、がラス中空体３表面とエポキシ樹脂が均一に結合されるためである。使用したエポキシ樹脂は、２液硬化型のエポキシ樹脂である。主剤はビスフェノールＡ型液状エポキシ樹脂であり、硬化剤は、テトラヒドロメチル無水フタル酸である。主剤と硬化剤を最適混合比率で混合してエポキシ樹脂として用いた。特に２液硬化型のエポキシ樹脂にこだわるものではなく、目的が達せられれば１液硬化型のエポキシ樹脂を用いても差し支えない。図１に示すように、エポキシ樹脂７を含浸させるためにエポキシ樹脂７を吸引するための吸引口５を設けた吸引ブロック９を設置する。貫通孔２にガラス中空体３を満たした整合部材作成治具１をエポキシ樹脂７で満たした容器６内に設置する。フィルター４は、貫通孔２の下側に設置するフィルター４は貫通孔２内のガラス中空体３が漏れないためである。貫通孔２の上側に設けるフィルター４は、エポキシ樹脂７を吸引したとき、貫通孔２内のガラス中空体３をエポキシ樹脂７と一緒に吸引しないためである。ここでは、フィルター４にろ紙を用いた。なお、先に述べたフィルター４の目的を達成せいていれば材質にはこだわらない。
【００２５】
そして、吸引ブロック９の吸引口８から真空ポンプ１０により容器６内のエポキシ樹脂７を吸引する。整合部材作成治具１内のガラス中空体３で満たされた貫通孔２にエポキシ樹脂７を含浸させる。真空ポンプによる整合層作成治具１内を低圧雰囲気下にすることにより、ガラス中空体３間に存在した空隙の気泡が抜け去り代わってエポキシ樹脂７がその間を埋めていき、ガラス中空体３間の空隙に一様に含浸される。これにより、貫通孔２内のガラス中空体３同志の密着性が向上し、ガラス中空体３周囲にエポキシ樹脂が塗布される。なお、エポキシ樹脂７を吸引するときには、エポキシ樹脂７が硬化しない温度で、且つエポキシ樹脂７の粘度が低くなる温度で吸引する方が、樹脂の流動性が高くなるので貫通孔２内にエポキシ樹脂を含浸しやすくなる。この場合、エポキシ樹脂７のゲル化温度より低い約６０℃中で吸引した。このようにガラス中空体３が充填された貫通孔２内にエポキシ樹脂７を含浸させた後、吸引用ブロック９を整合部材作成治具１から取り外す。そして、貫通孔２内に存在するガラス中空体３とエポキシ樹脂７の混合体である混合体８を含む整合部材作成治具１ごと恒温炉中に放置して、整合部材作成治具１内の混合体８を加熱硬化させた後、室温に冷却して作成して、本発明整合部材１２を得る。この整合部材１２をそのまま必要厚みに切削加工して、整合部材を得る。図１の整合層作成治具１の貫通孔２は１本しかないが、１本に限らず数本の貫通孔を有することは何の問題もない。
【００２６】
また、整合層作成工程においては、図３に示すようにエポキシ樹脂吸引用ブロック１４とエポキシ樹脂硬化用ブロック１５に分けて整合部材１２を作成しても差し支えない。貫通孔内でガラス中空体とエポキシ樹脂を混合して、エポキシ樹脂硬化用ブロック１５ごと硬化後、貫通孔から整合部材を取りだす。
【００２７】
エポキシ樹脂７のみで作成したエポキシ樹脂の線膨張係数を熱機械分析装置（ＴＭＡ）により、線膨張係数を測定した。測定サンプルには長さ２０ｍｍ、径２５ｍｍ^２の円柱サンプルを使用し、昇温速度は２．５（℃／ｍｉｎ）とした。３０℃〜１３０℃の線膨張係数は約６．６×１０^−５（１／℃）、１５０℃〜１９０℃の線膨張係数は約１．８×１０^−５（１／℃）であった。通常、エポキシ樹脂は、図３に示すように昇温させるとある一定の温度で熱膨張係数が変化する点が存在する（図３のＡ点）。このＡ点がガラス転移点温度（Ｔｇ）である。使用したエポキシ樹脂のガラス転移点温度は約１４０℃であった。このエポキシ樹脂を用いて、整合部材１２を作成する。エポキシ樹脂の加熱硬化条件を変化させて、実施例１のように作成する整合部材の完成後の寸法変化を比較する。整合部材作成治具の貫通孔の穴直径は１０．８ｍｍである。加熱硬化条件を変化させて、整合部材作成後の外径を測定する。同じ加熱硬化条件で５回ずつ整合部材を作成し、外径の平均値を計算して作成後の外径寸法値とし、この値から収縮変化率を求めた。加熱硬化経過後の冷却は、整合部材作成治具１内に整合部材１２を保持したまま恒温漕内で自然冷却させ、整合部材が室温に戻った状態で取り出した。（表１）に加熱硬化条件を変化させて作成した後の整合部材の外径寸法の収縮率を示す。なお（表１）の加熱硬化履歴は、段階的に連続して加熱温度履歴を加えている。
【００２８】
【表１】

【００２９】
（表１）の各加熱硬化条件で、８０℃×２ｈは、エポキシ樹脂をゲル化させるための必要温度および時間として統一した。このゲル化温度以降、エポキシ樹脂のガラス転移点温度を挟んでガラス転移点温度より低温側および高温側で温度を変化させて、エポキシ樹脂を硬化させた場合、（表１）の結果のようにゲル化温度からガラス転移点温度以上の高温領域の硬化温度にまで上げて加熱硬化させた比較例整合部材の外径寸法は約１％から１．６％小さくなって作成されてしまう。それに対して、熱変形温度以下の低温領域温度で一度実施してから、ガラス転移点温度以上の温度で加熱硬化させた本発明整合部材の外径寸法は、整合部材作成治具の貫通孔径の大きさと殆ど変化がなく作成することができた。このことは、比較例整合部材は、ゲル化温度からいきなりガラス転移点温度を超える高温領域で加熱硬化を実施するので、硬化高温本発明整合部材は、エポキシ樹脂の加熱硬化を一旦ガラス転移点温度以下の低温硬化工程を実施した後、ガラス転移点温度以上の高温硬化工程を実施するので、硬化時におけるエポキシ樹脂の構造が安定的に変化するので、整合部材の成型変形量を低減することができる。
【００３０】
（実施例２）
図５は、実施例１のように作成した整合部材を固定する固定治具および切断工程の概略図である。
【００３１】
図５（ａ）に示す１２は整合部材である。整合部材１２は中空球体と熱硬化性樹脂の混合体である。ここで中空球体は中空構造を有する中空ガラスである。中空ガラスは、１０から１００ｕｍの粒径を有し平均粒径は約６０ｕｍである。整合部材１２は実施例１に示すように作成した。この整合部材１２は固定治具１３を用いて固定する。固定治具１３のスライド部１４をスライドすることにより整合部材１２を固定する。この整合部材１２を固定した固定治具１３を切断装置に設置して整合部材１２を切断する。固定治具１３は、整合部材１２を固定する櫛歯状の支持部１５を有する。固定治具１３、スライド部１４と支持部１５の材質は、ステンレス材料を用いた。
【００３２】
図５（ｂ）に整合部材１２を挟む櫛歯状の支持部１５の側面図を示す。支持部１５が整合部材１２の外周形状に沿って固定するために、挟持することにより整合部材１２側面を損傷させることはない。ここでは、整合部材１２の断面に円形状を用いたが、固定治具１３で固定できる形状であればその形状は問わないことはもちろんである。固定治具１３の支持部１５間に切断装置の歯が移動することにより整合部材１２を切断する。この支持部１５の櫛歯の厚みを調整することにより整合部材１２を切断装置で切断してできる整合層の厚みを制御する。また、固定治具１３はこの支持部１５を有することにより整合部材１２を切断装置で切断後も切断した整合層が飛び散らないように固定することができる。これにより切断した整合層を傷つけることなく固定治具内で保持することができる。
【００３３】
図５（ｃ）に切断装置による整合部材の切断工程を示す。固定治具１３に固定された整合部材１２は、切断装置の回転歯１６により所定の厚み、すなわち圧電体の共振周波数の１／４波長に相当する厚みに切断されるとともに整合部材１２の切断表面を研磨する。ここでの切断装置の回転歯１６（ブレード）の少なくとも整合部材１２の切断厚みより大きい最外周面の両面には、ダイヤモンド粒を固着した歯を使用した。この回転歯１６にダイヤモンド粒を固着したのは、この仕様の回転歯１６がシリコンウエハーを切り出すことも可能な高硬度を有しているからである。整合部材１２の硬度よりも低い硬度の回転歯で整合部材１２を切断すると、整合部材１２の断面が傾きを持って切断されてしまうため所定の厚みを有する整合層を取り出すことができない。整合部材１２より高硬度を有する材料であれば、ダイヤモンド粒に限るものではない。また、この回転歯１６の両面にダイヤモンド粒を固着しているため回転歯両面の切断速度が一定であるので、回転歯１６が曲がって整合部材１２を切断することはない。また、整合部材１２を切断時に純水を流水として少なくとも切断表面を覆うように研磨水を回転歯１６に放出する。これにより、切断中の整合部材１２表面を洗浄するために、整合部材の切断表面に付着する切断時の残留物を除去することができる。
【００３４】
これにより、整合部材の接着表面に均一に接着層を形成することができる。なお、本実施例では、切断装置に会社名ディスコのダイシング装置である品番ＤＡＤ３２１を用い、回転歯（ブレード）には切断円周部にはダイヤモンド粒が接着されている回転歯を用いた。　本発明で所定の厚みに制御して作成した整合層表面状態と、従来の研磨により同様の厚みに制御した整合層表面状態をそれぞれ電子顕微鏡写真で比較した。従来方法で作成した整合層表面は、凹型の中空ガラス表面に研磨残留物が付着した状態で出来上がっている。それに対し、本発明で作成した整合層表面の方は、整合部材から発生する切断持の残留物がエポキシ樹脂表面および表面中空ガラス内にも付着せず、きれいに除去されていることが判明した。このことから、本発明で切断した整合層表面は、整合部材の切断時に発生する整合部材の構成材料に起因する残留物が付着することがない。
【００３５】
そのため、この整合層表面に接着剤を塗布あるいは印刷により、超音波振動子の構成材料表面均一に接着することができ整合層の接着強度を向上させることができる。切断および洗浄工程において、使用した本発明の整合部材はエポキシ樹脂をガラス転移点を挟んで、ガラス転移点温度より低温側の低温硬化工程とガラス転移点温度より高温側の高温加熱工程を経て連続加熱硬化して作成している。
【００３６】
また、整合部材は、ガラス転移点温度より低い温度領域で低温硬化工程を実施した後、切断および洗浄工程を実施して所定の厚みに作成した整合部材を作成する。この整合部材をガラス転移点温度より高温領域側である高温硬化工程を実施しても差し支えない。これは、一度低温硬化工程により整合部材の形状を保持されているからであり、この後切断および洗浄工程後、整合部材を高温硬化工程に実施しても形状変形を起こすことはない。
【００３７】
また、切断および洗浄工程を実施した整合部材を高温硬化させるので、洗浄工程時に付着した洗浄水の乾燥と高温硬化工程を一度に実施できるので効率的である。
【００３８】
（実施例３）
図６は、本発明の第３の実施例における超音波センサの断面図である。１７は超音波センサ、１８はケース、１９はケースの天部、１２は天部に固定された本発明の製造方法で作成された整合部材である。
【００３９】
２０はケース１８の天部１９の内壁面に配置された圧電体であり、２１はケース１８を固定するための支持部である。２２は導電体、２３は支持部２１に固定された端子板、２４ａ、２４ｂは端子板２３に固定された端子、２５は端子２４ａと端子２４ｂを絶縁するための絶縁部である。２６は圧電体２０に設けられた溝である。端子２４ａ、２４ｂから導電体２５を介して、圧電体２０に電圧が加わると、圧電体２０は圧電現象により振動する。図６の圧電体は、約５００ＫＨｚで振動し、その振動はケース１８に伝わり、整合部材１２に伝わる。整合部材１２の振動が気体に音波として伝搬する。従来による製造方法で作成した整合層は、密度が不均一でばらつきが大きいため、個々のセンサとしての特性を一定にすることが困難であった。個々の整合層密度が均一であるために、整合層の音速と密度の積で表すことのできる音響インピーダンスが安定し、圧電体からの振動は整合部材を介して均一、安定的に空間中に超音波を発振させることができる。
【００４０】
【発明の効果】
以上のように、請求項１記載の本発明によれば、中空球体と結合材料の混合物の結合材料の硬化工程に起因する整合部材の成型収縮等による成型不良がなくなり、整合部材のどの部分でも密度均一な整合部材が作成できる。
【００４１】
請求項２から３の本発明によれば、硬化条件として結合材料の温度変化による、特性変曲点、ガラス転移点による線膨張係数を境界にして低温硬化と高温硬化を経て樹脂を硬化させるので、樹脂の熱膨張、熱収縮に起因する成型不良がなくなり、成型寸法が安定する。
【００４２】
請求項４から５に記載の本発明は、中空球体と結合材料の混合物を連続して低温硬化工程から高温硬化工程へ加熱硬化した整合部材を切断および洗浄の加工工程を実施するので、結合材料が急激な温度上昇なしに徐々に硬化が進行するので整合部材内部で歪みがなくなり、亀裂や成型不良等の形状変形をなくすことができる。さらに、切断と同時に加工した整合部材表面は、切断残留物が付着していないので超音波センサ作成時のケース天板に接着固定する際、均一で安定的に接着させることができる。
【００４３】
請求項６から７記載の発明は、中空球体と結合材料の混合物に低温硬化工程を実施した後、切断および洗浄工程を経て整合部材を加工後、この整合部材を高温硬化工程させるので、洗浄工程後の整合部材表面に付着した洗浄水の乾燥と、高温硬化工程を一度に同時に実施することができるので効率的である。
【００４４】
請求項８記載の発明は、中空球体はガラス組成成分からなるので、中空状態を維持したまま中空球体外壁表面に表面改質材の被覆層を形成することができる。
【００４５】
請求項９記載の発明は、結合材料は熱硬化性樹脂化合物であるので、中空球体表面とのぬれ性がよくなり表面改質材の加水分解による中空球体表面と化学結合し、中空球体と結合材料の親和性を増すことができる。
【００４６】
請求項１０記載の発明は、天部と側壁部を有する筒状ケースと前記天部の内壁面に固定された圧電体と前記天部外壁面に接着層を介して設置された請求項１から１０の少なくとも１項記載の整合部材からなる整合層を用いるので、密度一定で密度ばらつきの少ない整合層を作成することができるので、ケースを介した圧電体からの振動を整合層が効率よく気体中に音波として伝搬させることができ、個々のセンサ間の特性ばらつきがない超音波センサを提供することができる。
【図面の簡単な説明】
【図１】本発明の実施例１における整合部材の製造工程を示す概略図
【図２】加振装置に設置した整合部材作成治具を示す概略図
【図３】吸引用ブロックと硬化用ブロックを示す構造図
【図４】熱機械分析装置によるエポキシ樹脂の線膨張係数測定結果を示す図
【図５】（ａ）本発明の実施例２における整合部材の固定治具を示す概略図
（ｂ）本発明の実施例２における固定治具の支持部による整合部固定を示す概略図
（Ｃ）本発明の実施例２における整合部材の切断工程を示す概略図
【図６】本発明整合層を用いた超音波センサの断面図
【図７】（ａ）従来の整合層と筒状部材からなる負荷ケースの一体成型を示す断面図
（ｂ）負荷ケースのカット後を示す断面図
（ｃ）従来の整合層と圧電素子を接着した状態を示す断面図
【符号の説明】
１　整合部材作成治具
３　ガラス中空体
９　エポキシ樹脂吸引用ブロック
１１　加振装置
１２　整合部材
１６　超音波センサ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a matching layer of an ultrasonic flowmeter for measuring a flow rate and a flow rate of a gas or a liquid using ultrasonic waves, and an ultrasonic sensor using the same.
[0002]
[Prior art]
In a conventional method of manufacturing a matching layer, for example, as shown in FIG. 7A, a matching layer made of a mixture of a hollow sphere 27 and a resin 28 and a load case made of a cylindrical member 29 are integrally formed. Then, as shown in FIG. 7B, the piezoelectric material is cut to a thickness corresponding to １／ wavelength of the resonance frequency. Then, as shown in FIG. 7C, using the matching layer 30 created as described above, the matching layer 30 is mounted on the piezoelectric vibrator 31, and a method of forming an ultrasonic vibrator is disclosed. (See Patent Document 1).
[0003]
In addition, a method of manufacturing a matching layer using a mixture of a glass balloon and a resin includes a matching layer in which bubbles having a particle size smaller than the wavelength of ultrasonic waves generated from a piezoelectric body are mixed into a resin. (See Patent Document 2).
[0004]
[Patent Document 1]
Japanese Patent Publication No. 6-101880 (Fig. 1)
[Patent Document 2]
JP-A-11-215594 [0005]
[Problems to be solved by the invention]
However, since the matching layer using this conventional manufacturing method is made by mixing a hollow sphere and a resin in a cylindrical member and thermally curing the resin, depending on the resin curing conditions, the resin shrinks and the cylindrical inner wall surface is formed. There is a problem that a crack occurs between the interface and the matching layer, and that the matching layer also undergoes discoloration, deformation and cracking. This is because heating the resin causes a change in the composition of the resin itself due to self-heating of the resin itself and rapid chemical changes in the resin components. Since a crack or the like is formed in the matching layer, a matching layer having a non-uniform density is created for each matching layer group obtained by cutting the cylindrical member to a predetermined thickness as shown in FIG. 7B. There were challenges.
[0006]
Also, it is very difficult to mix bubbles having a particle size smaller than the wavelength of the ultrasonic wave into the resin, and the size of the bubbles to be mixed cannot be controlled. Further, the density of the matching layer formed by mixing bubbles in the resin differs depending on the number of the formed layers, and a constant acoustic impedance cannot be obtained.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a matching member having a stable matching layer free from molding defects and having a reduced variation in matching layer density, a method for manufacturing the same, and an ultrasonic sensor. And
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned conventional problems, a method of manufacturing a matching layer according to the present invention includes a method of curing a mixture of a hollow sphere and a bonding material at a low temperature in a temperature range lower than a predetermined temperature, and further, in a high temperature range higher than a predetermined temperature. Since the matching member is created by the manufacturing method of curing, it is possible to solve the molding failure of the matching layer due to the curing condition of the resin. Therefore, the density of the matching layer of the present invention becomes uniform and the density variation is reduced, regardless of where the matching layer having a predetermined thickness is taken out in the matching member.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The invention according to claim 1 is a mixture comprising a hollow sphere and a bonding material surrounding the hollow sphere, wherein the mixture is cured in a temperature range lower than a predetermined temperature and a temperature higher than a predetermined temperature. Since the matching member is manufactured by performing the high-temperature curing process in which the region is cured, molding defects due to molding shrinkage of the matching member due to the curing process of the bonding material are eliminated, and density uniformity is achieved in any part of the matching member. An alignment member can be created.
[0010]
According to the second aspect of the present invention, since the predetermined temperature is the thermal deformation temperature of the bonding material, the resin is cured through low-temperature curing and high-temperature curing at the boundary of the characteristic inflection point of the resin as a curing condition. The cracks and cracks in the inside are eliminated, and the molding failure due to the thermal expansion and thermal contraction of the resin is eliminated, and the molding dimensions are stabilized.
[0011]
According to the third aspect of the present invention, since the predetermined temperature is the glass transition temperature of the bonding material, the resin is cured through low-temperature curing and high-temperature curing with a boundary between a linear expansion coefficient due to a temperature change of the resin as a curing condition. Molding defects due to thermal expansion and contraction of the resin are eliminated, and the molding dimensions are stabilized.
[0012]
According to a fourth aspect of the present invention, in the alignment member, after filling the mixture of the hollow spheres and the bonding material into the alignment member preparation jig, the alignment member is continuously joined with the alignment member preparation jig in a low-temperature curing step and a high-temperature curing step. Since the bonding material is hardened gradually without a sharp rise in temperature during the curing of the bonding material, distortion is eliminated inside the matching member, and shape abnormalities such as cracks and molding defects are caused. Can be eliminated.
[0013]
According to a fifth aspect of the present invention, in the alignment member, a fixing jig for fixing the alignment member taken out by performing a low-temperature curing step and a high-temperature curing step from the alignment member preparation jig is installed in a cutting device, and the alignment is performed. At the same time as the cutting step of cutting the member, a cleaning step in which the residue of the alignment member does not adhere to the surface of the alignment layer at the time of cutting is performed. Since the matching member prepared in step (1) is taken out and the cut and polished surface is washed while being cut and polished to a predetermined thickness, it is possible to provide a matching layer in which polishing residues generated during polishing do not adhere to the surface.
[0014]
The invention according to claim 6 is that, after filling the mixture of the hollow spheres and the bonding material into the matching member forming jig, a low-temperature curing step is performed together with the matching member forming jig, and thereafter, the matching member forming jig is used. After taking out the alignment member and processing the alignment member, a high-temperature curing step is performed on the alignment member. Therefore, the alignment member is processed before the temperature reaches the hot forming temperature. Further, after the alignment member is processed, the alignment member is passed through a high-temperature hardening step at a temperature equal to or higher than the thermal deformation temperature, so that it is possible to prevent molding defects of the alignment member due to contraction of the bonding material.
[0015]
In the invention according to claim 7, a cleaning step in which the residue of the matching member does not adhere to the surface of the matching layer is performed at the same time as the processing. Since the high-temperature curing step at a temperature equal to or higher than the deformation temperature is performed, a residue generated at the time of cutting does not adhere to the surface of the matching layer, and it is possible to prevent molding defects in the matching layer due to shrinkage of the bonding material.
[0016]
According to the eighth aspect of the present invention, since the hollow sphere is made of a glass composition component, it is possible to form a matching member by mixing with the bonding material while maintaining the hollow state, and the hollow sphere is formed by a change in the surrounding temperature of the matching layer. The state is maintained, and the matching layer density can be stabilized.
[0017]
According to the ninth aspect of the present invention, since the bonding material is a thermosetting resin compound, the resin compound has good wettability with the hollow sphere surface interface and adheres to the hollow sphere surface. Then, since the bonding material is thermally cured through the low-temperature curing and high-temperature curing steps, the bonding material does not cause deterioration in strength or discoloration of the matching member due to self-heating.
[0018]
According to a tenth aspect of the present invention, there is provided a cylindrical case having a top portion and a side wall portion, a piezoelectric body fixed to an inner wall surface of the top portion, and a piezoelectric body mounted on the outer wall surface of the top portion via an adhesive layer. 9. A matching layer comprising at least one of the matching layer according to claim 9 and a support provided on an outer wall portion of the side wall portion. It is possible to provide an ultrasonic sensor that can improve and efficiently transmit vibration from the piezoelectric body to the matching layer through the case. In addition, a density-stable matching layer free from defects such as cracks inside the matching layer can be provided. Therefore, it is possible to provide an ultrasonic sensor having no characteristic variation between individual sensors.
[0019]
【Example】
Hereinafter, embodiments of the present description will be described with reference to the drawings.
[0020]
(Example 1)
FIG. 1 is a schematic view of a manufacturing process of a matching member according to the first embodiment of the present invention.
[0021]
In FIG. 1, reference numeral 1 denotes a matching layer forming jig. Reference numeral 2 denotes a through hole provided in the matching layer forming jig 1. A mixture of a hollow sphere and a bonding material is formed in the through hole 2 of the alignment member forming jig 1 to form the alignment member 1 of the present invention. Reference numeral 3 denotes a hollow glass body having a hollow structure. Each of the glass hollow bodies 3 has a particle size of 10 to 100 μm, and the average particle size is about 60 μm. Compared to other fillers, glass hollow bodies have a lower specific gravity, have heat resistance, pressure resistance, impact resistance, and have properties such as dimensional stability and moldability of the filler when used as a filler. Can be improved. The composition of the glass used was borosilicate glass. This glass hollow body is formed by melting a raw material such as silicon oxide, boric acid, calcium carbonate, sodium carbonate, and sodium sulfate at a high temperature of 1000 ° C. or higher to form a glass containing a large amount of sulfur, and then pulverizing the glass. This glass fine powder is dispersed and retained in a flame to foam sulfur as a foaming agent component.
[0022]
In addition, there is a glass hollow body in which a surface modifier is formed on the surface of the glass hollow body in order to bond the glass hollow body and the bonding material closely, but there is no inconvenience even if the glass hollow body is used. . The glass hollow body 3 has a specific gravity of about 0.16 g / cc. Before use, the glass hollow body 3 is placed in a glass desiccator, and the desiccator is placed in a hot-air drying circulating furnace, and the sample after drying at 100 ° C. for 12 hours is used. This is for completely removing moisture adhering to the glass surface of the glass hollow body 3. If moisture remains on the surface of the glass hollow body 3 and the glass hollow body 3 and the bonding material are cured later, the moisture interferes with the bonding between the bonding material and the glass hollow body 3 by chemical bonding, and the glass hollow body 3 A microvoid layer may be formed between the bonding materials, which may reduce the mechanical strength of the matching member.
[0023]
As shown in FIG. 1, a through hole 2 is provided in a matching layer forming jig 1, and a glass hollow body 3 is put into the through hole 2 after drying. At this time, as shown in FIG. 2, after the matching layer forming jig 1 is set on the vibration device 11, the glass hollow body 3 is loaded while vibrating the entire matching layer forming jig 1. The vibration intensity of the vibration device is only longitudinal vibration, the frequency is 60 Hz, and about 5G. By vibrating the matching layer forming jig 1 in this work process, the matching layer forming jig 1 is vibrated into the through hole 2 in such a state as to fill the gap between the glass hollow bodies 3 put into the through hole 2 of the matching layer forming jig 1. Will fit. This is because, since the outer wall surface of the glass hollow body 3 forms the coating layer of the surface modifying material, the flowability of the glass hollow body 3 is high, so that even if the wall surfaces between the glass hollow bodies 3 come into contact with each other, they stay. This is because the glass hollow body 3 moves without being filled, and becomes in the close-packed state in the through-hole 2. Therefore, only the smallest gap exists between the glass hollow bodies 3. In the matching layer jig 1 filled with the glass hollow body 3 as described above, after the filters 4 are installed above and below the through hole 2, the bonding material is impregnated into the through hole 2 on the matching member forming jig 1. Here, an epoxy resin which is a thermosetting resin compound was used as the bonding material.
[0024]
This is because the shape change of the resin after hardening is small and the long-term stability is excellent. Above all, the surface of the glass hollow body 3 and the epoxy resin are uniformly formed in order to adapt to the surface of the glass hollow body 3 with good wettability. Because they are combined. The epoxy resin used is a two-component curing type epoxy resin. The main agent is a bisphenol A type liquid epoxy resin, and the curing agent is tetrahydromethyl phthalic anhydride. The main agent and the curing agent were mixed at an optimum mixing ratio and used as an epoxy resin. In particular, the present invention is not limited to a two-component curing type epoxy resin, and a one-component curing type epoxy resin may be used as long as the purpose is achieved. As shown in FIG. 1, a suction block 9 provided with a suction port 5 for sucking the epoxy resin 7 to impregnate the epoxy resin 7 is provided. The alignment member forming jig 1 in which the through hole 2 is filled with the glass hollow body 3 is placed in a container 6 filled with epoxy resin 7. The filter 4 is provided below the through-hole 2 so that the glass hollow body 3 in the through-hole 2 does not leak. This is because the filter 4 provided above the through hole 2 does not suck the glass hollow body 3 in the through hole 2 together with the epoxy resin 7 when the epoxy resin 7 is sucked. Here, filter paper was used for the filter 4. The material is not limited as long as the above-described purpose of the filter 4 is achieved.
[0025]
Then, the epoxy resin 7 in the container 6 is sucked from the suction port 8 of the suction block 9 by the vacuum pump 10. Epoxy resin 7 is impregnated into through-hole 2 filled with glass hollow body 3 in alignment member forming jig 1. By setting the inside of the matching layer forming jig 1 by a vacuum pump to a low-pressure atmosphere, air bubbles existing between the glass hollow bodies 3 are removed, and the epoxy resin 7 fills the gaps. Are uniformly impregnated in the voids. Thereby, the adhesion between the glass hollow bodies 3 in the through holes 2 is improved, and the epoxy resin is applied around the glass hollow bodies 3. When the epoxy resin 7 is sucked, it is better to suck the epoxy resin 7 at a temperature at which the epoxy resin 7 does not harden and at a temperature at which the viscosity of the epoxy resin 7 becomes low. Is easy to impregnate. In this case, suction was performed at about 60 ° C. lower than the gelling temperature of the epoxy resin 7. After impregnating the through-hole 2 filled with the glass hollow body 3 with the epoxy resin 7 in this way, the suction block 9 is removed from the alignment member forming jig 1. Then, the matching member making jig 1 including the mixture 8 which is a mixture of the glass hollow body 3 and the epoxy resin 7 existing in the through hole 2 is left in a constant temperature oven, and the inside of the matching member making jig 1 is left. After the mixture 8 is cured by heating, the mixture 8 is cooled to room temperature to produce the matching member 12 of the present invention. The alignment member 12 is cut to a required thickness as it is to obtain an alignment member. Although there is only one through-hole 2 of the matching layer forming jig 1 in FIG. 1, it is not limited to one but has several through-holes.
[0026]
In the matching layer forming step, as shown in FIG. 3, the matching member 12 may be formed separately for the epoxy resin suction block 14 and the epoxy resin curing block 15. The hollow glass body and the epoxy resin are mixed in the through-hole, and after the epoxy resin curing block 15 is cured, the matching member is removed from the through-hole.
[0027]
The coefficient of linear expansion of the epoxy resin prepared using only the epoxy resin 7 was measured by a thermomechanical analyzer (TMA). A cylindrical sample having a length of 20 mm and a diameter of 25 mm ² was used as a measurement sample, and the temperature was raised at a rate of 2.5 (° C./min). The linear expansion coefficient at 30 ° C. to 130 ° C. was about 6.6 × 10 ⁻⁵ (1 / ° C.), and the linear expansion coefficient at 150 ° C. to 190 ° C. was about 1.8 × 10 ⁻⁵ (1 / ° C.). . Usually, there is a point where the thermal expansion coefficient of the epoxy resin changes at a certain temperature when the temperature is increased as shown in FIG. 3 (point A in FIG. 3). This point A is the glass transition point temperature (Tg). The glass transition temperature of the epoxy resin used was about 140 ° C. Using the epoxy resin, the matching member 12 is formed. By changing the heating and curing conditions of the epoxy resin, the dimensional change after completion of the matching member prepared as in Example 1 is compared. The hole diameter of the through hole of the alignment member forming jig is 10.8 mm. The outer diameter after preparing the matching member is measured by changing the heating and curing conditions. An alignment member was prepared five times under the same heat-curing conditions, and the average value of the outer diameter was calculated and used as the outer diameter dimension value after the preparation, and the shrinkage change rate was determined from this value. After the heating and hardening, the cooling was performed by naturally cooling in a constant temperature bath while holding the alignment member 12 in the alignment member preparation jig 1 and taking out the alignment member after returning to room temperature. Table 1 shows the shrinkage ratio of the outer diameter of the matching member after the heating and curing conditions were changed. In the heating and curing history in Table 1, the heating temperature history is continuously added stepwise.
[0028]
[Table 1]

[0029]
Under each heat curing condition of (Table 1), 80 ° C. × 2 h was unified as a necessary temperature and time for gelling the epoxy resin. After the gelling temperature, when the epoxy resin is cured by changing the temperature on the lower side and the higher side from the glass transition point with the glass transition point of the epoxy resin in between, as shown in Table 1, The outer diameter of the comparative example matching member heated and cured by increasing the temperature from the gelation temperature to the curing temperature in the high temperature region equal to or higher than the glass transition temperature is reduced by about 1% to 1.6%. On the other hand, the outer diameter of the matching member of the present invention, which was once performed at a low-temperature region temperature equal to or lower than the heat deformation temperature and then heat-hardened at a temperature equal to or higher than the glass transition temperature, is equal to the through hole diameter of the matching member forming jig. It could be made with little change in size and size. This means that the matching member of the comparative example performs heat curing in a high temperature region immediately exceeding the glass transition point temperature from the gelation temperature. After the following low-temperature curing step, the high-temperature curing step above the glass transition temperature is performed, so that the structure of the epoxy resin at the time of curing changes stably, so that the amount of molding deformation of the matching member can be reduced. it can.
[0030]
(Example 2)
FIG. 5 is a schematic diagram of a fixing jig for fixing the alignment member created as in the first embodiment and a cutting process.
[0031]
Reference numeral 12 shown in FIG. 5A is an alignment member. The matching member 12 is a mixture of a hollow sphere and a thermosetting resin. Here, the hollow sphere is a hollow glass having a hollow structure. Hollow glass has a particle size of 10 to 100 um with an average particle size of about 60 um. The alignment member 12 was made as shown in Example 1. The alignment member 12 is fixed using a fixing jig 13. The alignment member 12 is fixed by sliding the slide portion 14 of the fixing jig 13. A fixing jig 13 to which the alignment member 12 is fixed is set in a cutting device, and the alignment member 12 is cut. The fixing jig 13 has a comb-shaped support portion 15 for fixing the alignment member 12. Stainless steel material was used as the material of the fixing jig 13, the slide portion 14, and the support portion 15.
[0032]
FIG. 5B shows a side view of the comb-shaped support portion 15 sandwiching the alignment member 12. Since the support portion 15 is fixed along the outer peripheral shape of the alignment member 12, the side surface of the alignment member 12 is not damaged by being sandwiched. Here, a circular shape is used for the cross section of the alignment member 12, but it goes without saying that the shape is not limited as long as the shape can be fixed by the fixing jig 13. The alignment member 12 is cut by moving the teeth of the cutting device between the support portions 15 of the fixing jig 13. By adjusting the thickness of the comb teeth of the support portion 15, the thickness of the matching layer formed by cutting the matching member 12 with a cutting device is controlled. Further, since the fixing jig 13 has the support portion 15, even after the alignment member 12 is cut by the cutting device, the cut alignment layer can be fixed so as not to be scattered. Thereby, the cut alignment layer can be held in the fixing jig without being damaged.
[0033]
FIG. 5C shows a process of cutting the alignment member by the cutting device. The matching member 12 fixed to the fixing jig 13 is cut by the rotating teeth 16 of the cutting device to a predetermined thickness, that is, a thickness corresponding to １／ wavelength of the resonance frequency of the piezoelectric body, and a cut surface of the matching member 12. Polish. At this time, teeth having diamond grains fixed thereto were used on both surfaces of the outermost peripheral surface of the rotating teeth 16 (blades) of the cutting device, which are at least larger than the cutting thickness of the alignment member 12. The reason why the diamond grains are fixed to the rotating teeth 16 is that the rotating teeth 16 of this specification have a high hardness that can cut a silicon wafer. If the alignment member 12 is cut with a rotating tooth having a hardness lower than that of the alignment member 12, the alignment layer having a predetermined thickness cannot be taken out because the cross section of the alignment member 12 is cut with an inclination. The material is not limited to diamond grains as long as the material has higher hardness than the matching member 12. Further, since the diamond grains are fixed to both surfaces of the rotating teeth 16, the cutting speed on both surfaces of the rotating teeth is constant, so that the rotating teeth 16 do not bend and cut the alignment member 12. Further, when cutting the alignment member 12, the polishing water is discharged to the rotary teeth 16 so as to cover at least the cut surface using pure water as flowing water. Thereby, in order to clean the surface of the alignment member 12 during cutting, it is possible to remove residues at the time of cutting that adhere to the cut surface of the alignment member.
[0034]
Thereby, the adhesive layer can be formed uniformly on the adhesive surface of the matching member. In this embodiment, the cutting device used was DAD321, a dicing device of the company name Disco, and the rotating teeth (blades) used were rotating teeth having diamond grains adhered to the cutting circumference. An electron microscope photograph was used to compare the surface state of the matching layer formed to a predetermined thickness in the present invention with the surface state of the matching layer controlled to the same thickness by conventional polishing. The surface of the matching layer formed by the conventional method is completed in a state where polishing residues are attached to the surface of the hollow hollow glass. On the other hand, it has been found that, on the surface of the matching layer prepared according to the present invention, the cutting residue generated from the matching member does not adhere to the surface of the epoxy resin and the inside of the surface hollow glass, and is clearly removed. For this reason, the residue caused by the constituent material of the matching member generated when the matching member is cut does not adhere to the surface of the matching layer cut in the present invention.
[0035]
Therefore, by applying or printing the adhesive on the surface of the matching layer, the constituent materials of the ultrasonic vibrator can be uniformly bonded to each other, so that the bonding strength of the matching layer can be improved. In the cutting and cleaning steps, the matching member of the present invention used is a continuous epoxy resin sandwiched between the glass transition point, through a low-temperature curing step below the glass transition point temperature and a high-temperature heating step above the glass transition point temperature. It is made by heat curing.
[0036]
In addition, the matching member performs a low-temperature curing process in a temperature region lower than the glass transition point temperature, and then performs a cutting and cleaning process to create a matching member having a predetermined thickness. The matching member may be subjected to a high-temperature curing step in which the temperature is higher than the glass transition temperature. This is because the shape of the alignment member is once held in the low-temperature curing step, and the shape is not deformed even if the alignment member is subjected to the high-temperature curing step after the cutting and cleaning steps.
[0037]
In addition, since the alignment member that has been subjected to the cutting and cleaning steps is cured at a high temperature, the drying of the cleaning water attached during the cleaning step and the high-temperature curing step can be performed at once, which is efficient.
[0038]
(Example 3)
FIG. 6 is a sectional view of an ultrasonic sensor according to the third embodiment of the present invention. Reference numeral 17 denotes an ultrasonic sensor, reference numeral 18 denotes a case, reference numeral 19 denotes a top portion of the case, and reference numeral 12 denotes an alignment member fixed to the top portion and manufactured by the manufacturing method of the present invention.
[0039]
Reference numeral 20 denotes a piezoelectric body arranged on the inner wall surface of the top portion 19 of the case 18, and reference numeral 21 denotes a support for fixing the case 18. 22 is a conductor, 23 is a terminal plate fixed to the support portion 21, 24a and 24b are terminals fixed to the terminal plate 23, and 25 is an insulating portion for insulating the terminals 24a and 24b. 26 is a groove provided in the piezoelectric body 20. When a voltage is applied to the piezoelectric body 20 from the terminals 24a and 24b via the conductor 25, the piezoelectric body 20 vibrates due to a piezoelectric phenomenon. The piezoelectric body shown in FIG. 6 vibrates at about 500 KHz, and the vibration is transmitted to the case 18 and transmitted to the matching member 12. The vibration of the matching member 12 propagates as a sound wave to the gas. Since the matching layer formed by the conventional manufacturing method has a non-uniform density and a large variation, it has been difficult to make the characteristics as individual sensors constant. Since the density of each matching layer is uniform, the acoustic impedance that can be expressed by the product of the sound velocity and the density of the matching layer is stable, and the vibration from the piezoelectric body is uniformly and stably transmitted through the matching member into the space. Ultrasonic waves can be oscillated.
[0040]
【The invention's effect】
As described above, according to the first aspect of the present invention, molding defects due to molding shrinkage of the alignment member due to the curing step of the binder of the mixture of the hollow sphere and the binder are eliminated, and any part of the alignment member can be used. An alignment member having a uniform density can be created.
[0041]
According to the second and third aspects of the present invention, the resin is cured through low-temperature curing and high-temperature curing with a boundary between a characteristic inflection point and a linear expansion coefficient due to a glass transition point due to a temperature change of the bonding material as a curing condition. In addition, molding defects due to thermal expansion and contraction of the resin are eliminated, and the molding dimensions are stabilized.
[0042]
According to the present invention as set forth in

claims

4 and 5, since the mixture of the hollow spheres and the binder is continuously subjected to the cutting and washing processing steps of the matching member which is heat-cured from the low-temperature curing step to the high-temperature curing step, the bonding material is used. However, since the curing proceeds gradually without a sharp rise in temperature, distortion is eliminated inside the alignment member, and shape deformation such as cracks and molding defects can be eliminated. Furthermore, since the residue of the alignment member processed at the same time as the cutting is free of the cutting residue, it can be uniformly and stably adhered to the case top plate when the ultrasonic sensor is produced.
[0043]
In the invention according to

claims

6 and 7, the low-temperature curing step is performed on the mixture of the hollow spheres and the bonding material, and then the alignment member is processed through the cutting and cleaning steps, and then the alignment member is subjected to the high-temperature curing step. The drying of the washing water adhered to the surface of the alignment member and the high-temperature curing step can be simultaneously performed at the same time, which is efficient.
[0044]
In the invention according to claim 8, since the hollow sphere is made of a glass composition component, a coating layer of a surface modifying material can be formed on the outer wall surface of the hollow sphere while maintaining the hollow state.
[0045]
According to the ninth aspect of the present invention, since the bonding material is a thermosetting resin compound, the wettability with the surface of the hollow sphere is improved, and the bonding material is chemically bonded to the surface of the hollow sphere by hydrolysis of the surface modifier, and is bonded to the hollow sphere. The affinity of the material can be increased.
[0046]
According to a tenth aspect of the present invention, there is provided a cylindrical case having a top portion and a side wall portion, a piezoelectric body fixed to an inner wall surface of the top portion, and a piezoelectric body mounted on the outer wall surface of the top portion via an adhesive layer. Since the matching layer made of the matching member according to at least 10 is used, a matching layer having a constant density and a small density variation can be formed, so that the matching layer efficiently removes vibrations from the piezoelectric body through the case by gas. It is possible to provide an ultrasonic sensor that can be propagated as a sound wave therein and has no characteristic variation between individual sensors.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a manufacturing process of an alignment member in Embodiment 1 of the present invention. FIG. 2 is a schematic view showing an alignment member preparation jig installed in a vibration device. FIG. 3 is a block for suction and a block for hardening. FIG. 4 is a view showing a result of measuring a linear expansion coefficient of an epoxy resin by a thermomechanical analyzer. FIG. 5 (a) is a schematic view showing a fixing jig of a matching member in Example 2 of the present invention (b) FIG. 6 is a schematic diagram showing fixing of a matching part by a support part of a fixing jig according to a second embodiment of the present invention. FIG. 6 (C) is a schematic diagram showing a cutting process of a matching member according to a second embodiment of the present invention. FIG. 7 (a) is a cross-sectional view showing an integrated molding of a conventional load case including a matching layer and a cylindrical member; FIG. 7 (b) is a cross-sectional view showing the load case after cutting; Sectional view showing the state in which the matching layer and the piezoelectric element are bonded to each other.
REFERENCE SIGNS LIST 1 alignment member forming jig 3 glass hollow body 9 epoxy resin suction block 11 vibrating device 12 alignment member 16 ultrasonic sensor

Claims

The alignment member is a mixture of a hollow sphere and a bonding material surrounding the hollow sphere, wherein the mixture is cured in a low temperature curing step in which the temperature is lower than a predetermined temperature and in a temperature region higher than the predetermined temperature. A method for manufacturing an alignment member, which comprises performing a high-temperature curing step.

The method according to claim 1, wherein the predetermined temperature is a heat deformation temperature of the bonding material.

3. The method according to claim 1, wherein the predetermined temperature is a glass transition temperature of the bonding material.

2. The aligning member, after filling the mixture of the hollow spheres and the bonding material into the aligning member forming jig, continuously performs a low-temperature curing step and a high-temperature curing step together with the aligning member forming jig. Manufacturing method of the matching member.

A cutting step of installing a fixing jig for fixing the alignment member taken out by performing the low-temperature curing step and the high-temperature curing step from the alignment member preparation jig in a cutting device, and cutting the alignment member; 5. The method of manufacturing an alignment member according to claim 1, further comprising performing a cleaning step in which a residue of the alignment member does not adhere to the surface of the alignment layer.

After filling the mixture of the hollow spheres and the bonding material into the alignment member preparation jig, the alignment member performs a low-temperature curing step together with the alignment member preparation jig, and then takes out the alignment member from the alignment member preparation jig. The method for manufacturing an alignment member according to claim 1, wherein after processing the alignment member, a high-temperature curing step is performed on the alignment member.

7. The method for manufacturing an alignment member according to claim 6, wherein a cleaning step is performed at the same time as the processing so that residues of the alignment member do not adhere to the surface of the alignment layer.

7. The method according to claim 1, wherein the hollow sphere contains a glass composition.

7. The method for manufacturing a matching member according to claim 1, wherein the bonding material is a thermosetting resin compound.

The alignment according to at least one of claims 1 to 9, wherein a cylindrical case having a top portion and a side wall portion, a piezoelectric body fixed to an inner wall surface of the top portion, and an outer wall surface of the top portion are installed via an adhesive layer. An ultrasonic sensor using a matching layer made of a member.