JP4248844B2 - Ultrasonic vibrator manufacturing method and ultrasonic flowmeter - Google Patents

Description

【００７２】
ケース天面の平坦度としては３次元表面粗さ計を用いてケース天面を測定し、最大値と最小値の差で求めた。そのときその差が５μｍ以下を合格とした。また、応力腐食割れ試験としては４８時間の試験の後、顕微鏡で目視して割れの全く無いものを合格とした。総合評価としては平坦度と腐食割れの両方の結果を合格したものを○とした。
【００７３】
以上の結果、切削加工されたケースもプレス一体型ケース両方ともケース天面を加圧した状態で熱処理を施すことで、ケース天面も５μｍ以下と平坦度も向上し、さらに応力腐食試験でも割れが生じないことが確認できた。また、治具で加圧する事によって治具の形状にケース天面が馴染むことから平坦度が向上するだけでなく、ケース天面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【００７４】
次に、上記検討と同様な条件でケース天面とフランジ面の両方を同時に加圧した状態で熱処理ができる図２の治具を用いて、ケース天面とフランジ面が平坦になるかどうかと応力腐食割れを調べた。その結果を表２に示す。
【００７５】
【表２】

【００７６】
ケース天面およびフランジ面の平坦度としては３次元表面粗さ計を用いてケース天面を測定し、最大値と最小値の差で求めた。そのとき、その差が５μｍ以下を合格とした。また、応力腐食割れ試験としては４８時間の試験の後、顕微鏡で目視して割れの全く無いものを合格とした。総合評価としては平坦度と腐食割れの両方の結果を合格したものを○とした。
【００７７】
以上の結果、切削加工されたケースもプレス一体型ケースも、両方ともケース天面、フランジ面を加圧した状態で熱処理を施すことで、ケース天面およびフランジ面も５μｍ以下と平坦度も向上し、さらに応力腐食試験でも割れが生じないことが確認できた。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面が馴染むことから平坦度が向上するだけでなく、ケース天面およびフランジ面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【００７８】
次に、上記検討と同様な条件でケース天面とフランジ面、ケース側面を同時に加圧した状態で熱処理ができる図３の治具を用いて、ケース天面とフランジ面が平坦になるかどうか、ケース側面の形状が修正されたかどうかと応力腐食割れを調べた。ケースの形状修正の指標としては真円度を用い真円度の測定には、真円度測定機（タリセンタＣ−１（商品名），テーラーホブソン製）を用いた。その結果を表３に示す。
【００７９】
【表３】

【００８０】
ケース天面およびフランジ面の平坦度としては３次元表面粗さ計を用いてケース天面を測定し、最大値と最小値の差で求めた。そのときその差が５μｍ以下を合格とした。真円度については、５μｍ以下を合格とした。また、応力腐食割れ試験としては４８時間の試験の後、顕微鏡で目視して割れの全く無いものを合格とした。総合評価としては平坦度と腐食割れの両方の結果を合格したものを○とした。
【００８１】
以上の結果、切削加工されたケースもプレス一体型ケース両方ともケース天面、フランジ面、ケース側面を加圧した状態で熱処理を施すことで、ケース天面およびフランジ面も５μｍ以下と平坦度も向上し、真円度についても５μｍ以下が得られた。さらに応力腐食試験でも割れが生じないことが確認できた。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面、ケース側面が馴染むことから平坦度および真円度が向上するだけでなく、ケース天面およびフランジ面、ケース側面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【００８２】
（実施例２）
実施例１の結果から、次はケース天面の加圧面積を変化させて検討を行うために、図８に示すボルト式の加圧治具の上型の面積を一定として、下型の面積を変化させて検討を行った。ケース形状は図１に示すφ１２ｍｍ、高さ５．６ｍｍ、厚さ０．２ｍｍである。このときの切削ケースのケース天面の平均平坦度は１０μｍ、プレス一体成型ケースのケース天面は１１μｍであった。ケース材料としてはＳＵＳ３０４を用いた。切削ケースおよびプレス一体成型ケースを加圧する面積ごとに３個ずつ用意した。加圧力は５００ｋｇｆ／ｃｍ^２一定とした。熱処理の温度プロファイルは図１０の温度プロファイルで昇温速度は３℃／ｍｉｎで２００℃まで加熱し、温度２００℃で１時間保持した後、炉冷した。このときの冷却速度は０．５℃／ｍｉｎであった。その後、常温まで温度が下がったのを確認後、治具からケースを取り出してケース天面の平坦度測定を３次元表面粗さ計で測定し、その後、腐食割れ試験を４８時間行った。腐食割れの判断については、顕微鏡を用いて目視検査を行った。ただし、今回の検討前に予備検討として、切削およびプレスで作製したケースを１０個ずつ用いて応力腐食試験を行ったが、それぞれ１０個ずつすべて割れてしまった。ケース天面の平坦度については３次元表面粗さ計を用いて測定をし、最大値と最小値の差を平坦度として、その差が５μｍ以下を合格とした。また、応力腐食割れ試験を行って、顕微鏡で目視して割れがないものを合格とした。総合評価はケース天面の平坦度が５μｍ以下、応力腐食割れなしの場合○とし、どちらか一方が不合格の場合△、両方不合格の場合×とした。表４及び表５にその結果を示す。表５は表４の続きである。
【００８３】
【表４】

【００８４】
【表５】

【００８５】
以上の結果より、ケース天面の端部を含み、端部から２０％以上の面積で加圧下状態で熱処理を行えば、ケース天面の平坦度を５μｍ以下にでき、さらに応力腐食割れも防止できることが判明した。また、治具で加圧する事によって治具の形状にケース天面が馴染むことから平坦度が向上するだけでなく、ケース天面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【００８６】
次に、上記検討と同様な条件でケース天面とフランジ面の両方を同時に加圧した状態で熱処理ができる治具を用いて、ケース天面とフランジ面が平坦になるかどうかと応力腐食割れを調べた。その結果を表６及び表７に示す。表７は表６の続きである。
【００８７】
【表６】

【００８８】
【表７】

【００８９】
以上の結果より、ケース天面およびフランジ面の曲部を含み、曲部から２０％以上の面積で加圧下状態で熱処理を行えば、ケース天面およびフランジ面の平坦度を５μｍ以下にでき、さらに、応力腐食割れも防止できることが判明した。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面が馴染むことから平坦度が向上するだけでなく、ケース天面およびフランジ面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【００９０】
次に、上記検討と同様な条件でケース天面、フランジ面、ケース側面を同時に加圧した状態で熱処理ができる図３の治具を用いて、ケース天面とフランジ面が平坦になるかどうか、ケース側面の形状が修正されたかどうかと応力腐食割れを調べた。ケースの形状修正の指標としては真円度を用い真円度の測定には、真円度測定機（タリセンタＣ−１，テーラーホブソン製）を用いた。その結果を表８及び表９に示す。表９は表８の続きである。
【００９１】
【表８】

【００９２】
【表９】

【００９３】
以上の結果、切削加工されたケースもプレス一体型ケース両方ともケース天面、フランジ面、ケース側面を加圧した状態で熱処理を施すことで、ケース天面およびフランジ面も５μｍ以下と平坦度も向上し、真円度についても５μｍ以下が得られた。さらに、応力腐食試験でも割れが生じないことが確認できた。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面、ケース側面が馴染むことから平坦度および真円度が向上するだけでなく、ケース天面およびフランジ面、ケース側面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【００９４】
（実施例３）
実施例１の結果を基に、加圧加重範囲の検討を行った。ケース形状は図１に示すφ１２ｍｍ、高さ５．６ｍｍ、厚さ０．２ｍｍである。このときの切削ケースのケース天面の平均平坦度は１０μｍ、プレス一体成型ケースのケース天面は１１μｍであった。ケース材料としてはＳＵＳ３０４を用いた。切削ケースおよびプレス一体成型ケースを加圧する加重ごとにそれぞれ３個ずつ用意した。加圧は図８に示すボルト式の治具に入れてトルクレンチを用いて締め込むトルクによってケース天面に加える加圧力を変化させた。実際の加重については富士写真フイルム株式会社のプレスケール高圧用（ＨＳ）（フィルム上で加圧力を測定できるプレッシャースケールの商品名）を用いて測定を行った。熱処理の温度プロファイルは図１０の温度プロファイルで昇温速度は３℃／ｍｉｎで２００℃まで加熱し、温度２００℃で１時間保持した後、炉冷した。このときの冷却速度は０．５℃／ｍｉｎであった。その後、常温まで温度が下がったのを確認後、治具からケースを取り出してケース天面の平坦度測定を３次元表面粗さ計で測定し、その後、腐食割れ試験を４８時間行った。腐食割れの判断については、顕微鏡を用いて目視検査を行った。ただし、今回の検討前に予備検討として、切削およびプレスで作製したケースを１０個ずつ用いて応力腐食試験を行ったが、それぞれ１０個ずつすべて割れてしまった。ケース天面の平坦度については３次元表面粗さ計を用いて測定をし、最大値と最小値の差を平坦度として、その差が５μｍ以下を合格とした。また、応力腐食割れ試験を行って、顕微鏡で目視して割れがないものを合格とした。総合評価はケース天面の平坦度が５μｍ以下、応力腐食割れなしの場合○とし、どちらか一方が不合格の場合△、両方不合格の場合×とした。表１０にその結果を示す。
【００９５】
【表１０】

【００９６】
以上の結果、応力腐食割れについてはすべての加圧力で割れはは見られなかった。また、ケース天面の平坦度に関しては、切削、プレス加工ともに５００ｋｇｆ／ｃｍ^２以上で５μｍ以下を実現可能であることが判明した。また、治具で加圧する事によって治具の形状にケース天面が馴染むことから平坦度が向上するだけでなく、ケース天面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【００９７】
次に、上記検討と同様な条件でケース天面とフランジ面の両方を同時に加圧した状態で熱処理ができる図２の治具を用いて、ケース天面とフランジ面が平坦になるかどうかと応力腐食割れを調べた。その結果を表１１に示す。
【００９８】
【表１１】

【００９９】
以上の結果、応力腐食割れについてはすべての加圧力で割れは見られなかった。また、ケース天面およびフランジ面の平坦度に関しては、切削、プレス加工ともに５００ｋｇｆ／ｃｍ^２以上で５μｍ以下を実現可能であることが判明した。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面が馴染むことから平坦度が向上するだけでなく、ケース天面およびフランジ面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１００】
次に、上記検討と同様な条件でケース天面、フランジ面、ケース側面を同時に加圧した状態で熱処理ができる図３の治具を用いて、ケース天面とフランジ面が平坦になるかどうか、ケース側面の形状が修正されたかどうかと応力腐食割れを調べた。ケースの形状修正の指標としては真円度を用い真円度の測定には、真円度測定機（タリセンタＣ−１，テーラーホブソン製）を用いた。その結果を表１２に示す。
【０１０１】
【表１２】

【０１０２】
以上の結果、応力腐食割れについてはすべての加圧力で割れは見られなかった。また、ケース天面およびフランジ面の平坦度とケース側面の真円度に関しては、切削、プレス加工ともに５００ｋｇｆ／ｃｍ^２以上で５μｍ以下を実現可能であることが判明した。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面、ケース側面が馴染むことから平坦度および真円度が向上するだけでなく、ケース天面およびフランジ面、ケース側面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１０３】
（実施例４）
実施例１〜３の結果を基に、熱処理温度の検討を行った。ケース形状は図１に示すφ１２ｍｍ、高さ５．６ｍｍ、厚さ０．２ｍｍである。このときの切削ケースのケース天面の平均平坦度は１０μｍ、プレス一体成型ケースのケース天面は１１μｍであった。ケース材料としてはＳＵＳ３０４を用いた。切削ケースおよびプレス一体成型ケースを熱処理温度ごとにそれぞれ３個ずつ用意した。加圧は図８に示すボルト式の治具に入れてトルクレンチを用いて締め込み、ケース天面に対して５００ｋｇｆ／ｃｍ^２の加圧力を加えた。その状態で、熱処理を行った。熱処理の温度プロファイルは図１０の温度プロファイルで昇温速度は３℃／ｍｉｎで、保持温度を１２０〜２２０℃まで１０℃ずつ変化させ、それぞれの温度で１時間保持した後、炉冷した。このときの冷却速度は０．５℃／ｍｉｎであった。その後、常温まで温度が下がったのを確認後、治具からケースを取り出してケース天面の平坦度測定を３次元表面粗さ計で測定し、その後、腐食割れ試験を４８時間行った。腐食割れの判断については、顕微鏡を用いて目視検査を行った。ただし、今回の検討前に予備検討として、切削およびプレスで作製したケースを１０個ずつ用いて応力腐食試験を行ったが、それぞれ１０個ずつすべて割れてしまった。ケース天面の平坦度については３次元表面粗さ計を用いて測定をし、最大値と最小値の差を平坦度として、その差が５μｍ以下を合格とした。また、応力腐食割れ試験を行って、顕微鏡で目視して割れがないものを合格とした。総合評価はケース天面の平坦度が５μｍ以下、応力腐食割れなしの場合○とし、どちらか一方が不合格の場合△、両方不合格の場合×とした。表１３及び表１４にその結果を示す。表１４は表１３の続きである。
【０１０４】
【表１３】

【０１０５】
【表１４】

【０１０６】
以上の結果より、熱処理温度は１５０〜３００℃の範囲でケース天面の平坦度が５μｍ以下にでき、さらに、応力腐食割れを防止することが可能と判明した。また、治具で加圧する事によって治具の形状にケース天面が馴染むことから平坦度が向上するだけでなく、ケース天面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１０７】
次に、上記検討と同様な条件でケース天面とフランジ面の両方を同時に加圧した状態で熱処理ができる図２の治具を用いて、ケース天面とフランジ面が平坦になるかどうかと応力腐食割れを調べた。その結果を表１５及び表１６に示す。表１６は表１５の続きである。
【０１０８】
【表１５】

【０１０９】
【表１６】

【０１１０】
以上の結果より、熱処理温度は１５０〜３００℃の範囲でケース天面およびフランジ面の平坦度が５μｍ以下にでき、さらに応力腐食割れを防止することが可能と判明した。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面が馴染むことから平坦度が向上するだけでなく、ケース天面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１１１】
次に、上記検討と同様な条件でケース天面、フランジ面、ケース側面を同時に加圧した状態で熱処理ができる図３の治具を用いて、ケース天面とフランジ面が平坦になるかどうか、ケース側面の形状が修正されたかどうかと応力腐食割れを調べた。ケースの形状修正の指標としては真円度を用い真円度の測定には、真円度測定機（タリセンタＣ−１，テーラーホブソン製）を用いた。その結果を表１７及び表１８に示す。表１８は表１７の続きである。
【０１１２】
【表１７】

【０１１３】
【表１８】

【０１１４】
以上の結果より、熱処理温度は１５０〜３００℃の範囲でケース天面およびフランジ面の平坦度およびケース側面の真円度を５μｍ以下にでき、さらに、応力腐食割れを防止することが可能と判明した。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面が馴染むことから平坦度が向上するだけでなく、ケース天面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１１５】
（実施例５）
実施例１〜４の結果を基に、熱処理温度での保持時間の検討を行った。ケース形状は図１に示すφ１２ｍｍ、高さ５．６ｍｍ、厚さ０．２ｍｍである。このときの切削ケースのケース天面の平均平坦度は１０μｍ、プレス一体成型ケースのケース天面は１１μｍであった。ケース材料としてはＳＵＳ３０４を用いた。切削ケースおよびプレス一体成型ケースを保持時間ごとにそれぞれ３個ずつ用意した。加圧は図８に示すボルト式の治具に入れてトルクレンチを用いて締め込み、ケース天面に対して５００ｋｇｆ／ｃｍ^２の加圧力を加えた。その状態で、熱処理を行った。熱処理の温度プロファイルは図１０の温度プロファイルで昇温速度は３℃／ｍｉｎで、保持温度を２００℃とし、保持時間を１０分ごとに増やして最大８０分まで変化させた後、炉冷した。このときの冷却速度は０．５℃／ｍｉｎであった。その後、常温まで温度が下がったのを確認後、治具からケースを取り出してケース天面の平坦度測定を３次元表面粗さ計で測定し、その後、腐食割れ試験を４８時間行った。腐食割れの判断については、顕微鏡を用いて目視検査を行った。ただし、今回の検討前に予備検討として、切削およびプレスで作製したケースを１０個ずつ用いて応力腐食試験を行ったが、それぞれ１０個ずつすべて割れてしまった。ケース天面の平坦度については３次元表面粗さ計を用いて測定をし、最大値と最小値の差を平坦度として、その差が５μｍ以下を合格とした。また、応力腐食割れ試験を行って、顕微鏡で目視して割れがないものを合格とした。総合評価はケース天面の平坦度が５μｍ以下、応力腐食割れなしの場合○とし、どちらか一方が不合格の場合△、両方不合格の場合×とした。表１９及び表２０にその結果を示す。表２０は表１９の続きである。
【０１１６】
【表１９】

【０１１７】
【表２０】

【０１１８】
以上の結果から、熱処理温度での保持時間は、５分より大きく、６０分を越えると応力腐食割れが生じ始めることが判明した。従って、熱処理において保持時間は６０分以下で良好な特性が得られる。また、治具で加圧する事によって治具の形状にケース天面が馴染むことから平坦度が向上するだけでなく、ケース天面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１１９】
次に、上記検討と同様な条件でケース天面とフランジ面の両方を同時に加圧した状態で熱処理ができる図２の治具を用いて、ケース天面とフランジ面が平坦になるかどうかと応力腐食割れを調べた。その結果を表２１及び表２２に示す。表２２は表２１の続きである。
【０１２０】
【表２１】

【０１２１】
【表２２】

【０１２２】
以上の結果から、熱処理温度での保持時間は６０分を越えると応力腐食割れが生じ始めることが判明した。従って、熱処理において保持時間は、５分より大きく、６０分以下で良好な特性が得られる。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面が馴染むことから平坦度が向上するだけでなく、ケース天面およびフランジ面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１２３】
次に、上記検討と同様な条件でケース天面、フランジ面、ケース側面を同時に加圧した状態で熱処理ができる図３の治具を用いて、ケース天面、フランジ面、ケース側面が平坦になるかどうかと応力腐食割れを調べた。その結果を表２３及び表２４に示す。
【０１２４】
【表２３】

【０１２５】
【表２４】

【０１２６】
以上の結果から、熱処理温度での保持時間は６０分を越えると応力腐食割れが生じ始めることが判明した。従って、熱処理において保持時間は６０分以下で良好な特性が得られる。また、治具で加圧する事によって治具の形状にケース天面、フランジ面、ケース側面が馴染むことから平坦度や真円度が向上するだけでなく、ケース天面、フランジ面、ケース側面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１２７】
（実施例６）
実施例１〜５の結果を基に、熱処理工程での冷却速度について検討を行った。ケース形状は図１に示すφ１２ｍｍ、高さ５．６ｍｍ、厚さ０．２ｍｍである。このときの切削ケースのケース天面の平均平坦度は１０μｍ、プレス一体成型ケースのケース天面は１１μｍであった。ケース材料としてはＳＵＳ３０４を用いた。切削ケースおよびプレス一体成型ケースを冷却する冷却速度ごとにそれぞれ３個ずつ用意した。加圧は図８に示すボルト式の治具に入れてトルクレンチを用いて締め込み、ケース天面に対して５００ｋｇｆ／ｃｍ^２の加圧力を加えた。その状態で、熱処理を行った。熱処理の温度プロファイルは図１０の温度プロファイルで昇温速度は３℃／ｍｉｎで、保持温度を２００℃とし、保持時間６０分後、冷却する。このときの冷却速度を何種類か変化させ冷却速度がケース天面の平坦化と応力緩和にどの程度寄与するかを調べた。冷却速度としては、▲１▼炉冷・徐冷(平均０．５℃／ｍｉｎ以下）▲２▼空冷（平均１．０℃／ｍｉｎ程度)▲３▼強制冷却（平均５．０℃／ｍｉｎ程度）▲４▼急冷（平均１０℃／ｍｉｎ以上）の４種類を検討した。その後、常温まで温度が下がったのを確認後、治具からケースを取り出してケース天面の平坦度測定を３次元表面粗さ計で測定し、その後、腐食割れ試験を４８時間行った。腐食割れの判断については、顕微鏡を用いて目視検査を行った。ただし、今回の検討前に予備検討として、切削およびプレスで作製したケースを１０個ずつ用いて応力腐食試験を行ったが、それぞれ１０個ずつすべて割れてしまった。ケース天面の平坦度については３次元表面粗さ計を用いて測定をし、最大値と最小値の差を平坦度として、その差が５μｍ以下を合格とした。また、応力腐食割れ試験を行って、顕微鏡で目視して割れがないものを合格とした。総合評価はケース天面の平坦度が５μｍ以下、応力腐食割れなしの場合○とし、どちらか一方が不合格の場合△、両方不合格の場合×とした。表２５にその結果を示す。
【０１２８】
【表２５】

【０１２９】
以上の結果から、冷却速度は、０℃／ｍｉｎより大きく、１．０℃／ｍｉｎ以下であればケースの天面を平坦度５μｍ以下にでき、内部応力も緩和され応力腐食割れも防止可能である。また、治具で加圧する事によって治具の形状にケース天面が馴染むことから平坦度が向上するだけでなく、ケース天面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１３０】
次に、上記検討と同様な条件でケース天面とフランジ面の両方を同時に加圧した状態で熱処理ができる図２の治具を用いて、ケース天面とフランジ面が平坦になるかどうかと応力腐食割れを調べた。その結果を表２６に示す。
【０１３１】
【表２６】

【０１３２】
以上の結果から、冷却速度は、０℃／ｍｉｎより大きく、１．０℃／ｍｉｎ以下であればケースの天面およびフランジ面を平坦度５μｍ以下にでき、内部応力も緩和され応力腐食割れも防止可能である。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面が馴染むことから平坦度が向上するだけでなく、ケース天面およびフランジ面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１３３】
次に、上記検討と同様な条件でケース天面、フランジ面、ケース側面を同時に加圧した状態で熱処理ができる図３の治具を用いて、ケース天面、フランジ面が平坦になるかどうかと、ケース側面の形状がどの程度修正されるかと応力腐食割れを調べた。その結果を表２７に示す。
【０１３４】
【表２７】

【０１３５】
以上の結果から、冷却速度は、０℃／ｍｉｎより大きく、１．０℃／ｍｉｎ以下であればケースの天面およびフランジ面を平坦度５μｍ以下にでき、ケース側面の形状を修正するとともに内部応力も緩和され応力腐食割れも防止可能である。また、治具で加圧する事によって治具の形状にケース天面、フランジ面、ケース側面が馴染むことから平坦度や真円度が向上するだけでなく、ケース天面、フランジ面、ケース側面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１３６】
（実施例７）
実施例１〜６の結果を基に、ケース材料について検討を行った。ケース形状は図１に示すφ１２ｍｍ、高さ５．６ｍｍ、厚さ０．２ｍｍである。このときの切削ケースのケース天面の平均平坦度は１０μｍ、プレス一体成型ケースのケース天面は１１μｍであった。ケース材料としてはＳＵＳ３０４、アルミニウム、アルミニウム合金、銅、真鍮、チタンを検討した。切削ケースおよびプレス一体成型ケースを材料ごとにそれぞれ３個ずつ用意した。加圧は図８に示すボルト式の治具に入れてトルクレンチを用いて締め込み、ケース天面に対して５００ｋｇｆ／ｃｍ^２の加圧力を加えた。その状態で、熱処理を行った。熱処理の温度プロファイルは図１０の温度プロファイルで昇温速度は３℃／ｍｉｎで、保持温度を２００℃とし、保持時間６０分後、０．５℃／ｍｉｎ以下の速度で冷却した。その後、常温まで温度が下がったのを確認後、治具からケースを取り出してケース天面の平坦度測定を３次元表面粗さ計で測定し、その後、腐食割れ試験を４８時間行った。腐食割れの判断については、顕微鏡を用いて目視検査を行った。ただし、今回の検討の予備検討として、切削およびプレスで作製したケースを１０個ずつ用いて応力腐食試験を行ったが、それぞれ１０個ずつすべて割れてしまった。ケース天面の平坦度については３次元表面粗さ計を用いて測定をし、最大値と最小値の差を平坦度として、その差が５μｍ以下を合格とした。また、応力腐食割れ試験を行って、顕微鏡で目視して割れがないものを合格とした。総合評価はケース天面の平坦度が５μｍ以下、応力腐食割れなしの場合○とし、どちらか一方が不合格の場合△、両方不合格の場合×とした。表２８及び表２９にその結果を示す。表２９は表２８の続きである。
【０１３７】
【表２８】

【０１３８】
【表２９】

【０１３９】
以上の結果から、上記金属にも加圧した状態で熱処理を施すことでケース天面の平坦度５μｍ以下、応力腐食割れを防止可能であることがわかった。また、治具で加圧する事によって治具の形状にケース天面が馴染むことから平坦度が向上するだけでなく、ケース天面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１４０】
次に、上記検討と同様な条件でケース天面とフランジ面の両方を同時に加圧した状態で熱処理ができる図２の治具を用いて、ケース天面とフランジ面が平坦になるかどうかと応力腐食割れを調べた。その結果を表３０及び表３１に示す。表３１は表３０の続きである。
【０１４１】
【表３０】

【０１４２】
【表３１】

【０１４３】
以上の結果から、上記金属にも加圧した状態で熱処理を施すことでケース天面およびフランジ面の平坦度５μｍ以下と応力腐食割れを防止可能であることがわかった。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面が馴染むことから平坦度が向上するだけでなく、ケース天面およびフランジ面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１４４】
次に、上記検討と同様な条件でケース天面、フランジ面、ケース側面を同時に加圧した状態で熱処理ができる図３の治具を用いて、ケース天面とフランジ面が平坦になるかどうかと、ケース側面の真円度、応力腐食割れを調べた。その結果を表３２及び表３３に示す。表３３は表３２の続きである。
【０１４５】
【表３２】

【０１４６】
【表３３】

【０１４７】
以上の結果から、上記金属にも加圧した状態で熱処理を施すことでケース天面、フランジ面の平坦度５μｍ以下とケース側面の真円度を高め、応力腐食割れを防止可能であることがわかった。また、治具で加圧する事によって治具の形状にケース天面、フランジ面、ケース側面が馴染むことから平坦度が向上するだけでなく、ケース天面、フランジ面、ケース側面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１４８】
（実施例８）
実施例１〜６の結果を基に、ケース天面の厚みについて検討した。ケース形状は図１に示すφ１２ｍｍ、高さ５．６ｍｍである。このときケース天面の厚さを０．１〜１．５ｍｍまで変化させて検討を行った。切削ケースのケース天面の平均平坦度は１０μｍ、プレス一体成型ケースのケース天面は１１μｍであった。ケース材料としてはＳＵＳ３０４を用いた。切削ケースおよびプレス一体成型ケースをケース天面の厚みごとにそれぞれ３個ずつ用意した。加圧は図８に示すボルト式の治具に入れてトルクレンチを用いて締め込み、ケース天面に対して５００ｋｇｆ／ｃｍ^２の加圧力を加えた。その状態で、熱処理を行った。熱処理の温度プロファイルは図１０の温度プロファイルで昇温速度は３℃／ｍｉｎで、保持温度を２００℃とし、保持時間６０分後、０．５℃／ｍｉｎ以下の速度で冷却した。その後、常温まで温度が下がったのを確認後、治具からケースを取り出してケース天面の平坦度測定を３次元表面粗さ計で測定し、その後、腐食割れ試験を４８時間行った。腐食割れの判断については、顕微鏡を用いて目視検査を行った。ただし、今回の検討の予備検討として、切削およびプレスで作製したケースを１０個ずつ用いて応力腐食試験を行ったが、それぞれ１０個ずつすべて割れてしまった。ケース天面の平坦度については３次元表面粗さ計を用いて測定をし、最大値と最小値の差を平坦度として、その差が５μｍ以下を合格とした。また、応力腐食割れ試験を行って、顕微鏡で目視して割れがないものを合格とした。総合評価はケース天面の平坦度が５μｍ以下、応力腐食割れなしの場合○とし、どちらか一方が不合格の場合△、両方不合格の場合×とした。表３４及び表３５にその結果を示す。表３５は表３４の続きである。
【０１４９】
【表３４】

【０１５０】
【表３５】

【０１５１】
以上の結果、ケース天面の厚みが１．０ｍｍ以下であるならば、ケース天面を加圧した状態で、熱処理施すことで、ケース天面の平坦度５μｍ以下で、応力腐食割れを防ぐことが可能であることがわかった。また、治具で加圧する事によって治具の形状にケース天面が馴染むことから平坦度が向上するだけでなく、ケース天面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１５２】
次に、上記検討と同様な条件でケース天面とフランジ面の両方を同時に加圧した状態で熱処理ができる図２の治具を用いて、ケース天面とフランジ面が平坦になるかどうかと応力腐食割れを調べた。その結果を表３６及び表３７に示す。表３７は表３６の続きである。
【０１５３】
【表３６】

【０１５４】
【表３７】

【０１５５】
以上の結果、ケース天面の厚みが１．０ｍｍ以下であるならば、ケース天面を加圧した状態で、熱処理施すことで、ケース天面およびフランジ面の平坦度５μｍ以下で、応力腐食割れを防ぐことが可能であることがわかった。また、治具で加圧する事によって治具の形状にケース天面およびフランジ面が馴染むことから平坦度が向上するだけでなく、ケース天面およびフランジ面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１５６】
次に、上記検討と同様な条件でケース天面、フランジ面、ケース側面を同時に加圧した状態で熱処理ができる図３の治具を用いて、ケース天面とフランジ面が平坦になるかどうか、ケース側面の真円度と応力腐食割れを調べた。その結果を表３８及び表３９に示す。表３９は表３８の続きである。
【０１５７】
【表３８】

【０１５８】
【表３９】

【０１５９】
以上の結果、ケース天面の厚みが１．０ｍｍ以下であるならば、ケース天面、フランジ面、ケース側面を加圧した状態で、熱処理施すことで、ケース天面、フランジ面の平坦度およびケース側面の真円度を５μｍ以下で、応力腐食割れを防ぐことが可能であることがわかった。また、治具で加圧する事によって治具の形状にケース天面、フランジ面、ケース側面が馴染むことから平坦度が向上するだけでなく、ケース天面フランジ面、ケース側面における形状も均一化されケースの個体ばらつきも小さくなる効果も見られた。
【０１６０】
（実施例９）
実施例１〜８の検討を基に、材質ＳＵＳ３０４、板厚０．２ｍｍを用いてプレス一体成型を用いて作製された有天筒状金属ケースを加圧治具で熱処理を行い、その後、超音波振動子を作製した。加圧および熱処理条件として、加圧は図８に示すボルト式の治具に入れてトルクレンチを用いて締め込み、ケース天面に対して５００ｋｇｆ／ｃｍ^２の加圧力を加えた。その状態で、熱処理を行った。熱処理の温度プロファイルは図１０の温度プロファイルで昇温速度は３℃／ｍｉｎで、保持温度を２００℃とし、保持時間６０分後、０．５℃／ｍｉｎ以下の速度で冷却した。その後、常温まで温度が下がったのを確認後、治具からケースを取り出した。比較のために熱処理を施してない有天筒状金属ケースを用いて同様な超音波振動子を作製し、作製した超音波振動子の個体ばらつきをインピーダンスの周波数特性における相関係数（３５０ＫＨｚ〜７５０ＫＨｚまでの周波数範囲のインピーダンスがどの程度似ているかを表したもの）と感度について比較した。感度については、基準となる超音波振動子を一つ決めて、その基準超音波振動子から発信した信号を受信する受信感度で確認した。その結果を表４０に示す。
【０１６１】
【表４０】

【０１６２】
以上の結果から、加圧した状態で熱処理を施した有天筒状金属ケースを用いて作製された超音波振動子は、インピーダンスの周波数特性における相関係数の値も高く、感度ばらつきも非常に小さく抑えることが可能なため超音波振動子の固体ばらつきを小さくすることができ、高精度な超音波流量計を構築することが可能であることが判明した。
【０１６３】
（実施例１０）
実施例１〜９の検討を基に、材質ＳＵＳ３０４、板厚０．２ｍｍを用いてプレス一体成型を用いて作製された有天筒状金属ケースを圧電体と音響整合層を接着する工程と加圧状態で熱処理を行う工程とを兼ねることができるか調べるために、圧電体および音響整合層を接着するための加圧硬化治具を用いて、ケース天面およびフランジ面を加圧した状態で熱処理を行った。加圧および熱処理条件として、加圧はケース天面およびに対して５００ｋｇｆ／ｃｍ^２の加圧力を加えた。その状態で、熱処理を行った。熱処理の温度プロファイルは図８の温度プロファイルで昇温速度は３℃／ｍｉｎで、保持温度をエポキシ接着剤の硬化温度である１５０℃とし、保持時間３０分後、０．５℃／ｍｉｎ以下の速度で冷却した。その後、常温まで温度が下がったのを確認後、治具からケースを取り出した。治具からケースを取り出してケース天面の平坦度測定を３次元表面粗さ計で測定し、その後、腐食割れ試験を４８時間行った。腐食割れの判断については、顕微鏡を用いて目視検査を行った。ただし、ケース天面の平坦度については３次元表面粗さ計を用いて測定をし、最大値と最小値の差を平坦度として、その差が５μｍ以下を合格とした。また、応力腐食割れ試験を行って、顕微鏡で目視して割れがないものを合格とした。総合評価はケース天面の平坦度が５μｍ以下、応力腐食割れなしの場合○とし、どちらか一方が不合格の場合△、両方不合格の場合×とした。表４１にその結果を示す。
【０１６４】
【表４１】

【０１６５】
以上の結果から判断して、圧電体および整合層をケース天面に接着を行う治具および接着工程を用いても同様な効果が得られることがわかった。従って、接着硬化工程でケース天面およびフランジ面の平坦化と応力腐食割れを防止することが可能であり、工程を兼ねることが可能である。
【０１６６】
（実施例１１）
実施例１〜１０の検討を基に、材質ＳＵＳ３０４、板厚０．２ｍｍを用いてプレス一体成型を用いて作製された有天筒状金属ケースを用いて超音波振動子を作製した。加圧および熱処理条件として、ケース天面およびフランジ面に対して５００ｋｇｆ／ｃｍ^２の加圧力を加えた。熱処理の温度プロファイルは図１０の温度プロファイルで昇温速度は３℃／ｍｉｎで、保持温度をエポキシ接着剤の硬化温度１５０℃とし、保持時間３０分後、０．５℃／ｍｉｎ以下の速度で冷却した。その後、常温まで温度が下がったのを確認後、治具からケースを取り出した。比較のために熱処理を施してない有天筒状金属ケースを用いて同様な超音波振動子を作製し、作製した超音波振動子の個体ばらつきをインピーダンスの周波数特性における相関係数（３５０ＫＨｚ〜７５０ＫＨｚまでの周波数範囲のインピーダンスがどの程度似ているかを表したもの）と感度について比較した。感度については、基準となる超音波振動子を一つ決めて、その基準超音波振動子から発信した信号を受信する受信感度で確認した。その結果を表４２に示す。
【０１６７】
【表４２】

【０１６８】
以上の結果から、加圧した状態で熱処理を施した有天筒状金属ケースを用いて作製された超音波振動子は、インピーダンスの周波数特性における相関係数の値も高く、感度ばらつきも非常に小さく抑えることが可能なため超音波振動子の固体ばらつきを小さくすることができ、高精度な超音波流量計を構築することが可能であることが判明した。
【０１６９】
上記実施形態によれば、切削又はプレスにより一体成型された少なくとも有底筒状金属ケース３３であって、１つの面に配置された圧電体６を少なくとも備える超音波振動子のケース３３において、厚み方向に対して両面から挟み込むように加重した状態で応力腐食割れが抑えられるように低温熱処理を施した天面３３を少なくとも有することにより、切削又はプレスにより一体成型された超音波振動子用ケース３３において、少なくともケース天面３３ａが平坦で応力腐食割れのないケース３３を実現することができて、超音波振動子組立時の歩留まりおよび生産性、長期信頼性の向上を図ることができる。そして、そのような有天筒状金属ケースを利用して圧電体６を天面３３ａに配置することにより、高精度で信頼性の高い超音波振動子および超音波流量計を実現することが可能となる。また、天面３３ａ（又は、天面３３ａ及びフランジ面３３ｆ）を厚み方向に対して天面３３ａ（又は、天面３３ａ及びフランジ面３３ｆ）を両面から加圧治具で挟み込むように加重することにより、加圧治具の挟み込む面の形状に天面３３ａ（又は、天面３３ａ及びフランジ面３３ｆ）が馴染むことから平坦度が向上するだけでなく、天面３３ａ（又は、天面３３ａ及びフランジ面３３ｆ）における形状も均一化されケースの個体ばらつきも小さくなる。さらに、天面３３ａに加えて側面３３ｇを厚み方向に対して天面３３ａに加えて側面３３ｇを両面から加圧治具で挟み込むように加重することにより、加圧治具の挟み込む面の形状に天面３３ａに加えて側面３３ｇが馴染むことから側面３３ｇの形状も均一化されケースの個体ばらつきも小さくなる。
【０１７０】
なお、本発明は上記実施形態に限定されるものではなく、その他種々の態様で実施できる。例えば、上記低温熱処理は、上記ケース３３に被接着物（例えば圧電体６）を加熱状態下で接着剤（例えば接着剤３１）で接着するときの接着剤硬化用の加熱処理であるようにすることもできるが、これ以外の接着工程に適用することもできる。すなわち、上記ケース３３の所定の面の厚み方向に対して所定の面を両面から挟み込むように加重した状態で低温熱処理することで加重面の形状修正及び応力腐食割れを防止する工程を、上記圧電体６及び上記音響整合層４をケース天面３３ａに接着する工程、又は、音響整合層４をケース天面３３ａに接着する工程に置き換えることができる。このようにすれば、特別に低温熱処理工程を設定することなく、上記ケース３３に被接着物（例えば圧電体６及び上記音響整合層４、又は、音響整合層４）を接着剤（例えば接着剤３１及び接着剤３０、又は、接着剤３０）で接着するときの加熱処理工程を上記低温熱処理工程と兼用することができ、より生産性を高めることができる。
【０１７１】
なお、上記様々な実施形態のうちの任意の実施形態や例を適宜組み合わせることにより、それぞれの有する効果を奏するようにすることができる。
【０１７２】
【発明の効果】
本発明によれば、切削又はプレスにより一体成型された少なくとも有底筒状金属ケースであって、１つの面に配置された圧電体とを備える超音波振動子用のケースにおいて、天面などその厚み方向に対して天面などを両面から挟み込むように加重した状態で応力腐食割れが抑えられるように低温熱処理を施すことにより、ケース天面などが平坦で応力腐食割れのないケースを実現することで、超音波振動子組立時の歩留まりおよび生産性、長期信頼性の向上を図ることができる。そして、そのような有天筒状金属ケースを利用することにより、高精度で信頼性の高い超音波振動子および超音波流量計を実現することが可能となる。
【０１７３】
具体的には、本発明の第１態様にかかる有底筒状金属ケースによれば、切削又はプレスにより一体成型された少なくとも有底筒状金属ケースであって、１つの面に配置された圧電体を備える超音波振動子のケースにおいて、厚み方向に対して両面から挟み込むように加重した状態で応力腐食割れが抑えられるように低温熱処理を施した天面を有することにより、ケース天面が平坦で応力腐食割れのないケースを実現することができ、超音波振動子組立時の歩留まりおよび生産性、長期信頼性の向上を図ることができる。そして、そのような有天筒状金属ケースを利用することにより、高精度で信頼性の高い超音波振動子および超音波流量計を実現することが可能となる。また、天面を厚み方向に対して天面を両面から挟み込むように加重することにより、天面を挟み込む加圧治具などの加圧面の形状に天面などが馴染むことから平坦度が向上するだけでなく、天面などにおける形状も均一化されケースの個体ばらつきも小さくなる。
【０１７４】
本発明の第２態様にかかる超音波振動子用ケースの製造方法によれば、切削又はプレスにより一体成型された少なくとも有底筒状金属ケースと、上記ケースの１つの面に配置された圧電体とを備える超音波振動子の上記ケースを製造する、超音波振動子用ケースの製造方法において、上記ケースの天面の厚み方向に対して上記ケースの天面を両面から挟み込むように加重した状態で低温熱処理を施すようにしている。このように構成すれば、ケース天面が平坦で応力腐食割れのないケースを実現することができ、長期信頼性の向上を図ることができる。
【０１７５】
本発明の第３態様にかかる超音波振動子用ケースの製造方法によれば、上記ケースの厚み方向に対して上記ケースの上記天面を両面から挟み込むように加重する加重領域は、上記天面と側面との曲部を含み、上記曲部から上記天面の内向きに少なくとも２割以上の面積の領域とするようにしている。このように構成すれば、ケース天面が平坦で応力腐食割れのないケースをより確実に実現することができ、長期信頼性の向上を図ることができる。
【０１７６】
本発明の第４態様にかかる超音波振動子用ケースの製造方法によれば、上記ケースの天面の厚み方向の両面から上記天面を挟み込むとともに、フランジ面の厚み方向の両面から上記フランジ面を挟み込むように加重した状態で低温熱処理を施すようにしている。このように構成すれば、ケース天面に加えてフランジ面も平坦とすることができて、応力腐食割れのないケースを、より確実に実現することができ、長期信頼性の向上を図ることができる。
【０１７７】
本発明の第５態様にかかる超音波振動子用ケースの製造方法によれば、上記ケースの天面と上記フランジ面とが平行になるように、上記ケースの天面の厚み方向の両面から上記天面を挟み込むとともに、上記フランジ面の厚み方向の両面から上記フランジ面を挟み込むように加重した状態で低温熱処理を施すようにしている。このように構成すれば、上記ケース天面と上記フランジ面との平行度が良くなり、上記フランジ面に端子板を溶接固定するときに応力が発生せず、その応力が側面を伝って上記ケース天面に内部応力を発生させることを防止することができる。
【０１７８】
本発明の第６態様にかかる超音波振動子用ケースの製造方法によれば、上記ケースの上記天面および上記フランジ面を上記天面および上記フランジ面の厚み方向に対して両面から挟み込むように加重する加重領域は、上記ケースの天面と側面との曲部および側面とフランジ面との曲部を含み、それぞれの曲部から上記天面及び上記フランジ面の内向きにそれぞれ少なくとも２割以上の面積とするようにしている。このように構成すれば、加重領域として、天面とフランジ面に加えて、上記ケースの天面と側面との曲部および側面とフランジ面との曲部を含むことができるので、所定の面を修正して平坦化するとき、その所定の面に隣接する曲部を修正することができて、最も効率良く修正動作を行うことができる。さらに、加重領域として、上記フランジ面の内向きにそれぞれ少なくとも２割以上の面積とすることにより、修正動作をより効率良く行うことができる。
【０１７９】
本発明の第７態様にかかる超音波振動子用ケースの製造方法によれば、上記ケースのケース側面を、上記ケース側面の厚み方向に対して、両面から挟み込むように加重した状態で低温熱処理を施すようにしている。このように構成すれば、ケース天面が平坦でかつケース側面の形状修正が可能で応力腐食割れのないケースを実現することができ、長期信頼性の向上を図ることができる。また、側面の形状修正を行うことができる結果、共振周波数のバラツキを低減させることができる。
【０１８０】
本発明の第８態様にかかる超音波振動子用ケースの製造方法によれば、上記ケースの上記加重する面の厚み方向に対して上記加重される面を加圧治具などにより両面から挟み込むように加重する荷重は、５００ｋｇｆ／ｃｍ^２以上であるようにしている。このように構成すれば、上記加重する荷重が５００ｋｇｆ／ｃｍ^２未満では平坦化を必ずしも確実に達成することができないが、上記加重する荷重を５００ｋｇｆ／ｃｍ^２以上とすることにより、平坦化を確実に達成することができる。
【０１８１】
本発明の第９態様にかかる超音波振動子用ケースの製造方法によれば、上記低温熱処理は、上記ケースの温度を上げる工程と、上記ケースをある一定温度で保持する工程と、上記ケースの温度を下げる工程とを備えるようにしている。このように構成すれば、上記各態様の作用効果をより確実にかつ安定して達成することができる。
【０１８２】
本発明の第１０態様にかかる超音波振動子用ケースの製造方法によれば、上記低温熱処理の上記一定温度で保持する工程において、保持温度は１５０〜３００℃であるようにしている。このように構成すれば、保持温度が１５０℃以上であるためケース天面の反り量を平坦にする効果が期待でき、また、保持温度が３００℃以下であるためケース天面の反り量を平坦化する効果も期待でき、応力腐食割れ試験においても割れが生じることがない。また、保持温度が３００℃以下であるため、加圧冶具に関しても特殊鋼などを使用する必要がなく、通常のステンレス（ＳＵＳ３０４など）で対応可能であるとともに、生産性に関しても、タクトタイムも短縮され、低温熱処理するための恒温槽も通常品で可能なため有利である。
【０１８３】
本発明の第１１態様にかかる超音波振動子用ケースの製造方法によれば、上記熱処理温度をある一定温度に保持する工程において、保持時間は、５分より大きく６０分以内であるようにしている。このように構成すれば、６０分以内という少ない時間で効率良く低温熱処理を行うことができるとともに、熱処理時間が長過ぎて応力腐食割れが生じ始めることもない。
【０１８４】
本発明の第１２態様にかかる超音波振動子用ケースの製造方法によれば、上記低温熱処理において、温度を下げる速度は、０℃／ｍｉｎより大きく１．０℃／ｍｉｎ以下であるようにしている。このように構成すれば、急冷もしくは１．０℃／ｍｉｎを超える速度で冷却することがないので、ケースに応力が蓄えられ、反り、変形が生じたり、内部応力が蓄えられることで、応力腐食割れ試験で割れが生じるといったことがない。
【０１８５】
本発明の第１３態様にかかる超音波振動子用ケースの製造方法によれば、上記加工成型された金属ケースを構成する材料は主にステンレス鋼、アルミニウム、アルミニウム合金、銅、真鍮、又は、チタンであるようにしている。このように構成すれば、このような汎用の材料で上記種々の作用効果を確実に達成することができる。
【０１８６】
本発明の第１４態様にかかる超音波振動子用ケースの製造方法によれば、上記ケース材料の厚みは、０ｍｍより大きく１ｍｍ以下であるようにしている。このように構成すれば、ケース天面の厚みが０ｍｍより大きく１ｍｍ以下であるため、低温熱処理で応力腐食割れを防止する効果が低下することがないとともに、超音波振動子の超音波の感度の低下も防止できる。
【０１８７】
本発明の第１５態様にかかる有底筒状金属ケースの製造方法によれば、上記低温熱処理は、上記ケースに被接着物を加熱状態下で接着剤で接着するときの接着剤硬化用の加熱処理であるようにしている。このようにすれば、特別に低温熱処理工程を設定することなく、上記ケースに被接着物を接着剤で接着するときの加熱処理工程を上記低温熱処理工程と兼用することができ、より生産性を高めることができる。
【０１８８】
本発明の第１６態様にかかる超音波振動子用ケースによれば、請求項２〜１５のいずれか１つに記載の超音波振動子用ケースの製造方法により製造されるようにしている。このように構成すれば、天面などその厚み方向に対して天面などを両面から挟み込むように加重した状態で応力腐食割れが抑えられるように低温熱処理を施すことにより、ケース天面などが平坦で応力腐食割れのないケースを超音波振動子用ケースとして使用することができ、超音波振動子組立時の歩留まりおよび生産性、長期信頼性の向上を図ることができるて、高精度で信頼性の高い超音波振動子を提供することが可能となる。
【０１８９】
本発明の第１７態様にかかる超音波振動子の製造方法によれば、切削又はプレスにより一体成型された少なくとも有底筒状金属ケースと、上記ケースの１つの面に配置された圧電体とを備える超音波振動子を製造する、超音波振動子の製造方法において、上記ケースの厚み方向に対して上記ケースの天面を両面から挟み込むように加重した状態で低温熱処理を施すとともに、上記ケースの天面に上記圧電体を固定するようにしている。このようにすれば、第１態様の作用効果を有しかつ流路を流れる流体に対して繋ぎ目のないケースにおいて、第２態様の作用効果と同様に、ケース天面が平坦で応力腐食割れのないケースを超音波振動子用ケースとして使用することができ、超音波流量計組立時の歩留まり及び生産性が良く、高精度で信頼性の高い超音波流量計を実現することが可能となる。
【０１９０】
本発明の第１８〜２９態様にかかる超音波振動子の製造方法によれば、第３〜１４態様の作用効果とそれぞれ同様な作用効果を奏することができる。
【０１９１】
本発明の第３０態様にかかる超音波振動子によれば、上記圧電体が設けられた面の反対側の面に音響整合層が設けられる超音波振動子において、上記ケース天面の厚み方向に対して上記天面を両面から挟み込むように加重した状態で低温熱処理することで上記天面の形状修正および応力腐食割れを防止する工程を、上記圧電体及び上記音響整合層、またはどちらか一方を上記天面に接着する工程に置き換えるようにしている。このようにすれば、特別に低温熱処理工程を設定することなく、上記ケースに被接着物（例えば圧電体及び上記音響整合層、又は、音響整合層）を接着剤（例えば接着剤及び接着剤、又は、接着剤）で接着するときの加熱処理工程を上記低温熱処理工程と兼用することができ、より生産性を高めることができる。
【０１９２】
本発明の第３１態様にかかる超音波振動子によれば、第１７〜３０のいずれか１つの態様に記載の超音波振動子の製造方法により製造されるようにしている。このようにすれば、ケース天面が平坦で応力腐食割れのないケースを実現することができ、超音波振動子組立時の歩留まりおよび生産性、長期信頼性の向上を図ることができる。そして、そのような有天筒状金属ケースを利用することにより、高精度で信頼性の高い超音波振動子および超音波流量計を実現することが可能となる。
【０１９３】
本発明の第３２態様にかかる超音波振動子によれば、上記圧電体が設けられた面の反対側の面に配置された音響整合層をさらに備えるようにしている。このようにすれば、第１態様の作用効果を有しかつ流路を流れる流体に対して繋ぎ目のないケースにおいて、第２態様の作用効果と同様に、ケース天面が平坦で応力腐食割れのないケースを超音波振動子用ケースとして使用することができ、超音波流量計組立時の歩留まり及び生産性が良く、高精度で信頼性の高い超音波流量計を実現することが可能となる。
【０１９４】
本発明の第３３態様にかかる超音波流量計によれば、被測定流体が流れる流量測定部と、上記流量測定部に設けられて超音波を送受信する第３１又は３２の態様に記載の１対の超音波振動子と、上記超音波振動子間の伝搬時間を計測する計測回路と、上記計測回路からの信号に基づいて流量を算出する流量演算手段とを備えるようにしている。このようにすれば、第１態様の作用効果を有しかつ流路を流れる流体に対して繋ぎ目のないケースにおいて、第２態様の作用効果と同様に、ケース天面が平坦で応力腐食割れのないケースを超音波振動子用ケースとして使用することができ、超音波流量計組立時の歩留まり及び生産性が良く、高精度で信頼性の高い超音波流量計を実現することが可能となる。
【図面の簡単な説明】
【図１】 本発明の一実施形態の第１例にかかる有底筒状金属ケースの製造方法において超音波振動子用ケースのケース天面を加圧している様子を示す一部断面図である。
【図２】 本発明の上記実施形態の第２例にかかる有底筒状金属ケースの製造方法において超音波振動子用ケースのケース天面およびフランジ面を加圧している様子を示す一部断面図である。
【図３】 本発明の上記実施形態の第３例にかかる有底筒状金属ケースの製造方法において超音波振動子用ケースのケース天面、フランジ面、ケース側面を加圧している様子を示す一部断面図である。
【図４】 本発明の上記実施形態の第１例にかかる有底筒状金属ケースの製造方法において超音波振動子用ケースの上記ケース天面の加圧領域をハッチング及び太線で示す斜視図である。
【図５】 本発明の上記実施形態の第２例にかかる有底筒状金属ケースの製造方法において超音波振動子用ケースの上記ケース天面およびフランジ面の加圧領域をハッチング及び太線で示す斜視図である。
【図６】 本発明の上記実施形態の第３例にかかる有底筒状金属ケースの製造方法において超音波振動子用ケースの上記ケース天面、フランジ面、ケース側面の加圧領域をハッチング及び太線で示す斜視図である。
【図７】 (ａ），（ｂ）は、それぞれ、円形筒状ケースを示す斜視図、及び、矩形ケースを示す斜視図である。
【図８】 (ａ），（ｂ）は、それぞれ、本発明の上記実施形態の第１例にかかる有底筒状金属ケースの製造方法において使用する加圧治具の構成を示す分解斜視図、及び、加圧治具で加圧した状態を示す斜視図である。
【図９】 恒温槽の構成と加圧治具を投入した状態を示す斜視図である。
【図１０】 熱処理の温度プロファイルを示す図である。
【図１１】 本発明の上記実施形態にかかる有底筒状金属ケースを利用した超音波振動子を示す図である。
【図１２】 本発明の上記実施形態にかかる有底筒状金属ケースを利用した別の超音波振動子を示す図である。
【図１３】 本発明の上記実施形態にかかる有底筒状金属ケースを有する超音波振動子を備える超音波流量計を示す図である。
【図１４】 図１３の超音波流量計の断面を示す図である。
【符号の説明】
４…音響整合層、６…圧電体、７…端子板、８ａ…端子、８ｂ…端子、９…ガラス板、１０…導電ゴム、１１…流量測定部、１２…側壁部、１３…側壁部、１４…シール材、１５…上板部、１６…流路断面、１７…超音波振動子、１８…超音波振動子、１９…振動子取り付け穴、２０…振動子取り付け穴、２１…シール材、２２…シール材、３０，３１…接着剤、３３…有底筒状金属ケース、３３ａ…ケース天面、３３ｂ，３３ｃ…曲部、３３ｆ…フランジ面、３３ｇ…ケース側面、８０…加圧治具、８１…恒温槽、８２…ヒータ、８３…ステンレス板、８４…ファン、９１，９３，９５…上型、９１ａ，９３ａ，９５ａ…第１加圧面、９３ｆ，９５ｆ…第２加圧面、９５ｂ，９５ｃ…角部、９５ｇ…第３加圧面、９２，９４，９６…下型、９２ａ，９４ａ，９６ａ…第１加圧面、９４ｆ，９６ｆ…第２加圧面、９４ｂ，９４ｃ，９６ｂ，９６ｃ…角部、９６ｇ…第３加圧面、９９…加重を加える面積、１００…超音波流量計、１００ａ…入口路、１００ｂ…出口路、１０１…計測回路、１０２…流量演算手段、Ｐ５…温度を上げる工程、Ｐ６…一定温度で保持する工程、Ｐ７…温度を下げる工程。[0001]
BACKGROUND OF THE INVENTION
  The present invention includes a bottomed cylindrical case and an acoustic matching layer provided on at least one surface of the case, and a superconductor provided with a piezoelectric body on a surface opposite to the surface on which the acoustic matching layer is provided. Sonic transducerManufacturing method and superIt relates to a sonic flow meter.
[0002]
[Prior art]
The case for an ultrasonic vibrator is a case for accommodating a piezoelectric vibrator or the like, and is usually replaced with a vacuum or an inert gas and sealed. Since the ultrasonic vibrator is mainly used for measuring the velocity of a fluid such as gas or liquid, the case surface for the ultrasonic vibrator is exposed to the gas and liquid to be measured. For example, when used in a gas meter such as city gas, safety against accidents such as gas leakage and long-term reliability over current electronic components are required because it is used continuously for more than 10 years. In particular, there is a recent movement in the continuous use period from 10 years to 20 years in the industry, and further long-term reliability is demanded. Also, Article 559 (Leakage Test) of Chapter 10 “Gas Meter” of “Specific Meters Inspection Inspection Rules” strictly describes the inspection and provisions regarding leakage and water ingress with respect to gas.
[0003]
In addition, in the gas manufacturer's specifications, for pressure switches, etc., the main material that comes into contact with gas is the gas business law stipulated by the Agency for Natural Resources and Energy, Gas Business Section and Gas Technology Safety Section, “Technical Standards for Gas Works” It shall be a metal material having gas resistance and corrosion resistance conforming to the specification of Article 84 of the Notification that defines the details of "
[0004]
Therefore, the case member in contact with the gas is not allowed to be corroded due to mechanical damage due to processing or impact, or environmental factors such as temperature and acid rain. Accordingly, it is required to have excellent strength, workability, gas resistance, corrosion resistance, stress corrosion cracking resistance, and weldability. For conventional sensors, cases that are integrally molded with resin, sintered cases, cases where joints are processed by welding, etc. are generally used, and are not materials or structures that take into account the above safety aspects or long-term reliability. (For example, refer to Patent Document 1).
[0005]
On the other hand, in the case of a metal machined case that is used in consideration of safety and long-term reliability or a metal case that is integrally formed with a press, the top surface of the case that joins the piezoelectric body and the acoustic matching layer is connected with the accuracy and vibration. Since it is also used as a plate, it is required to process it flat and uniformly from the viewpoint of acoustic performance.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-118550
[0007]
[Problems to be solved by the invention]
The resin case has low moisture resistance and lacks durability, and the sintered case is weak against impact and has poor processing accuracy. In addition, the resin case and the sintered case have a drawback in that it is difficult to guarantee safety and long-term reliability due to low confidentiality. For the cutting case, brass, which is a material with excellent workability, is used because it involves precision machining. However, many materials with excellent workability, such as brass, are inferior in corrosion resistance, and it is necessary to apply plating treatment to the surface after processing in order to improve the corrosion resistance. For this reason, the number of processes is increased and the processing fee is very high. Furthermore, in the cutting case, the case top surface used as a diaphragm from the acoustic surface is processed thinly because it is more sensitive to make the thickness as thin as possible compared to the side of the case. There was a drawback that the top surface was bent or warped due to distortion. Moreover, in the case where there is a joint to the fluid flowing through the flow path, the strength of the welded portion is questionable in terms of long-term reliability. On the other hand, it is difficult to process a very uniform case for a case that has been press-integrated, because it is necessary to make the top of the case flat. The press mold has a short life. Further, since the force applied during processing is stored as internal stress, stress corrosion cracking often occurs in the 42% magnesium chloride corrosion test of stainless steel described in JIS G 05762, making it impossible to use. This is stated in the specifications of the gas manufacturer's pressure switch, and the main material in contact with the gas is the gas business law “Gaseous technology of gas construction” established by the Gas Business Division and the Gas Technology Safety Division of the Agency for Natural Resources and Energy. Because it is defined as “a metal material with gas resistance and corrosion resistance conforming to the standards of Article 84 of the Notification that defines the details of the above standards”, the ultrasonic gas sensor also uses the magnesium chloride test to accelerate the test. Is done.
[0008]
  Accordingly, an object of the present invention is to solve the above-mentioned problems, and by realizing a case where the top surface of the case is flat and free from stress corrosion cracking, the yield, productivity, and long-term reliability at the time of assembling the ultrasonic transducer are realized. Can be improvedManufacturing method of ultrasonic vibrator, andBy using such a cylindrical metal case, it has high performance, high safety, and long-term reliability.,SuperProvide a sonic flow meter.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
[0010]
  According to the first aspect of the present invention, a bottomed cylinder having a top surface and a side surface, a bottomed cylindrical metal case integrally formed by cutting or pressing;
  A piezoelectric body disposed on the top surface of the case;
  An acoustic matching layer disposed on a surface opposite to the surface on which the piezoelectric body is provided;
In the manufacturing method of an ultrasonic vibrator, manufacturing an ultrasonic vibrator used for a gas meter equipped with
  Between the upper mold of the metal having a screw part and the lower mold of the metal having a screw part,The top surface is sandwiched from both sides in the thickness direction of the top surfaceOnlyAnd the side is sandwiched from both sides in the thickness direction of the sideBy screwing one of the upper mold screw part and the lower mold screw part into the other screw part,Including the process of heat treatment in a weighted stateSee
The upper mold integrally covers the outside of the top surface (33a) and the side surface (33g) of the case, and the lower mold is formed of the top surface (33a) and the side surface (33g) of the case. Weigh so as to cover the inside as oneAn ultrasonic transducer manufacturing method is provided.
  According to a second aspect of the present invention, there is provided the method for manufacturing an ultrasonic transducer according to the first aspect, wherein the case has a cylindrical shape.
  According to the third aspect of the present invention, the weighted region for weighting the case so as to sandwich the top surface of the case from both sides with respect to the thickness direction of the case includes a curved portion of the top surface and the side surface, and the curved portion The method for manufacturing an ultrasonic transducer according to the first or second aspect is provided in which the region has an area of at least 20% or more inward of the top surface.
  According to the fourth aspect of the present invention, the bottomed cylindrical metal case has a flange surface at the periphery of the opening of the cylinder,
  In the step of performing the heat treatment, the top surface and the flange surface of the case are further sandwiched from both sides in the thickness direction of the top surface and the flange surface so that the top surface of the case and the flange surface are parallel to each other. There is provided a method for manufacturing an ultrasonic transducer according to any one of the first to third aspects, including a step of performing a heat treatment in a weighted state.
  According to the fifth aspect of the present invention, the weight region for weighting the top surface and the flange surface of the case so as to be sandwiched from both sides with respect to the thickness direction of the top surface and the flange surface is the top surface of the case. And a curved portion of the side surface and a curved surface portion of the flange surface, and each curved portion has an area of at least 20% inward from the top surface and the flange surface. A method for manufacturing an ultrasonic transducer is provided.
  According to the sixth aspect of the present invention, the weight applied so as to sandwich the weighted surface from both sides with respect to the thickness direction of the weighted surface of the case is 500 kgf / cm.²The method for manufacturing an ultrasonic transducer according to any one of the first to fifth aspects is provided.
  According to a seventh aspect of the present invention, the heat treatment comprises
  Increasing the temperature of the case,
  Maintaining the case at a certain temperature;
  A method for manufacturing an ultrasonic transducer according to any one of the first to sixth aspects, comprising a step of lowering the temperature of the case.
  According to the 8th aspect of this invention, in the process hold | maintained at the said fixed temperature of the said heat processing, holding temperature is 150-300 degreeC,
  In the step of holding the heat treatment temperature at a certain temperature, the holding time is greater than 5 minutes and within 60 minutes,
  In the heat treatment, there is provided the method for manufacturing an ultrasonic vibrator according to the seventh aspect, in which the temperature lowering speed is greater than 0 ° C./min and equal to or less than 1.0 ° C./min.
  According to the ninth aspect of the present invention, the material constituting the processed and molded metal case is any one of the first to eighth aspects, wherein the material is stainless steel, aluminum, aluminum alloy, copper, brass, or titanium. The manufacturing method of the ultrasonic vibrator as described in 1. is provided.
  According to a tenth aspect of the present invention, there is provided the method for manufacturing an ultrasonic transducer according to any one of the first to ninth aspects, wherein the thickness of the case material is greater than 0 mm and equal to or less than 1 mm.
  According to the eleventh aspect of the present invention, in the heat treatment step, the piezoelectric body and the acoustic matching layer, or which is weighted so as to sandwich the top surface from both sides with respect to the thickness direction of the case top surface, Provided is a method for manufacturing an ultrasonic transducer according to any one of the first to tenth aspects, in which either one is bonded to the top surface.
  According to the twelfth aspect of the present invention, the flow rate measurement unit through which the fluid to be measured flows,
  A pair of ultrasonic transducers according to any one of the first to eleventh aspects, which are provided in the flow rate measurement unit and transmit and receive ultrasonic waves;
  A measurement circuit for measuring the propagation time between the ultrasonic transducers;
  Provided is an ultrasonic flowmeter comprising flow rate calculation means for calculating a flow rate based on a signal from the measurement circuit.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments according to the present invention will be described below in detail with reference to the drawings.
[0044]
In the bottomed cylindrical metal case 33 manufactured by the manufacturing method of the bottomed cylindrical metal case according to the embodiment of the present invention, a bottom surface for closing the cylindrical opening is integrally formed at one end of the cylindrical body. As shown in FIG. 1, in order to completely remove the processing oil after processing, and then prevent stress corrosion cracking after being manufactured by integral molding process that forms the bottom surface by cutting or pressing, It is manufactured by performing low-temperature heat treatment in a state in which a weight is applied to the case top surface 33a from both sides of the case top surface 33a with respect to the thickness direction of the case top surface 33a. The ultrasonic vibrator and the ultrasonic flowmeter are manufactured by bonding and fixing the piezoelectric body 6 and the like using the bottomed cylindrical metal case 33 manufactured in this manner, thereby manufacturing the ultrasonic vibrator and the ultrasonic flowmeter. High performance, high safety, long-term reliability and high productivity. The case shape is generally cylindrical or rectangular as shown in FIGS. 7A and 7B, for example. In the case of a cylindrical shape, the diameter is φ12 mm, the height is h = 6 mm, the thickness is t = 0.2 mm, and is rectangular. In this case, a size of 8 mm wide × 8 mm wide × 6 mm high and thickness t = 0.2 mm can be exemplified. However, the shape and size of the case 33 are not limited to the above.
[0045]
More specifically, as a first example of the manufacturing method of the bottomed cylindrical metal case 33 according to the embodiment of the present invention, the piezoelectric body 6 is provided on one surface (for example, the top surface 33a) of the case 33. It is a manufacturing method of case 33 used for an ultrasonic vibrator and an ultrasonic flowmeter using the same. First, the flange surface 33f is integrally formed at one end of the cylinder body at the periphery of the cylinder opening, and the flange surface 33f is integrally formed with the case 33 using a deep drawing method by cutting or precision press. Is completely removed. Next, as shown in FIG. 1, a metal lower mold 92 used as a pedestal having a first pressure surface 92a for receiving at least the inner surface of the case top surface 33a, and a first pressure surface 91a for pressing the outer surface of the case top surface 33a. Is substantially uniform so as to sandwich the case top surface 33a from both sides of the case top surface 33a with respect to the thickness direction of the case top surface 33a. A low-temperature heat treatment is applied in a state where a weight is applied to. At this time, the area (weighted region) 99 to which the weight is applied includes the case top surface 33a and the curved portion 33b of the case top surface 33a and the side surface 33g, as shown by hatching in FIG. The area is preferably at least 20% or more in the direction. Here, the shape of the top surface 33a is corrected by applying a weight to the top surface 33a. However, the correction of the shape of the top surface 33a means that the shape of the pressure jig for correcting the shape of the top surface 33a is corrected. It means that the top surface 33a is adapted. Therefore, if the area of the top surface 33a to which the load is applied is reduced, the area that is compatible with the shape of the pressure jig is also reduced. When correcting the top surface 33a, the most effective is that the weight can be reduced by pressing an area of 20% or more including the curved portion 33b as described above. In other words, the weight is most applied in the vicinity of the curved portion 33b. If the area to which the weight is applied is 20% or less, the weight is considerably required and the efficiency is poor. Further, the larger the area to be weighted, the higher the correction can be made. Therefore, it is preferable that the area 99 of the top surface 33a to which the load is applied is at least 20% or more inward from the curved portion 33b. The pressing surfaces 92a and 91a of the lower die 92 and the upper die 91 are desirably as flat as possible, and the flatness needs to be flat and uniform more than the flatness required for the case top surface 33a, that is, 5 μm. It is said. Thereby, the case top surface 33a can be flattened. Using the bottomed cylindrical metal case 33 manufactured in this way, the piezoelectric body 6 is bonded and fixed to a predetermined surface such as the top surface 33a, or the piezoelectric body 6 is bonded and fixed to a predetermined surface such as the top surface 33a. The acoustic matching layer 4 is bonded and fixed to the surface opposite to the top surface 33a to manufacture the ultrasonic vibrator and the ultrasonic flowmeter, thereby improving the performance and safety of the ultrasonic vibrator and the ultrasonic flowmeter. Long-term reliability can be realized.
[0046]
In the manufacturing method of the bottomed cylindrical metal case according to the second example of the embodiment of the present invention, an ultrasonic transducer including the piezoelectric body 6 on one surface (for example, the top surface 33a) of the case 33 and the same It is a manufacturing method of case 33 used for the used ultrasonic flowmeter. First, the flange surface 33f is integrally formed at one end of the cylinder body at the periphery of the cylinder opening, and the flange surface 33f is integrally formed with the case 33 using a deep drawing method by cutting or precision press. Is completely removed. Next, as shown in FIG. 2, a metal lower mold 94 used as a pedestal having a first pressure surface 94a that receives the inner surface of the case top surface 33a and a second pressure surface 94f that receives the inner surface of the flange surface 33f; A pressure jig comprising a metal upper mold 93 having a first pressure surface 93a for pressing the outer surface of the case top surface 33a and a second pressure surface 93f for receiving the outer surface of the flange surface 33f, the case top surface 33a and the flange A low-temperature heat treatment is performed in a state in which a substantially uniform load is applied to the thickness direction of the surface 33f so that the case top surface 33a and the flange surface 33f are sandwiched between the pressure surfaces 93a, 93f, 94a, and 94f, respectively. At this time, as shown by hatching in FIG. 5, an area (weighted region) 99 to which weight is applied is a curved portion 33b of the case top surface 33a and the side surface 33g in addition to the case top surface 33a and the flange surface 33f, and It is preferable that it has an area of at least 20% or more inward from each of the curved portions 33b and 33c, including the curved portion 33c of the flange surface 33f and the side surface 33g. Here, the shapes of the case top surface 33a and the flange surface 33f are corrected by applying a weight to the respective surfaces of the case top surface 33a and the flange surface 33f. Being corrected means that the case top surface 33a and the flange surface 33f are adapted to the shape of the pressure jig whose shape is to be corrected. Therefore, if the area of the surface to which the weight is applied among the surface of the case top surface 33a and the flange surface 33f is reduced, the area adapted to the shape of the pressure jig is also reduced. When correcting each surface, the most effective is that the weight can be reduced by pressing an area of 20% or more including the curved portion as described above. In other words, the weight is most applied in the vicinity of the curved portion, and if the area to which the weight is applied is 20% or less, the weight is considerably required and the efficiency is poor. Further, the larger the area to be weighted, the higher the correction can be made. Therefore, in each surface, the area 99 of the surface to which the load is applied is preferably at least 20% or more inward from the curved portion. Thereby, the case top surface 33a and the flange surface 33f can be flattened. Using the bottomed cylindrical metal case 33 manufactured in this way, the piezoelectric body 6 is bonded and fixed to a predetermined surface such as the top surface 33a, or the piezoelectric body 6 is bonded and fixed to a predetermined surface such as the top surface 33a. The acoustic matching layer 4 is bonded and fixed to the surface opposite to the top surface 33a to manufacture the ultrasonic vibrator and the ultrasonic flowmeter, thereby improving the performance and safety of the ultrasonic vibrator and the ultrasonic flowmeter. Long-term reliability can be realized. The lower die 94 is provided inside the curved portion 33c, which is an inner corner between the corner surface 94b between the flange surface 33f and the side surface 33g, and a corner portion 94b that contacts the inside of the curved portion 33b of the case top surface 33a and the side surface 33g. And a corner portion 94c in contact therewith.
[0047]
In the manufacturing method of the bottomed cylindrical metal case according to the third example of the embodiment of the present invention, an ultrasonic vibrator including the piezoelectric body 6 on one surface (for example, the top surface 33a) of the case 33 and the same It is a manufacturing method of case 33 used for the used ultrasonic flowmeter. First, a flange surface 33f is integrally formed at one end of the cylinder body at the periphery of the cylinder opening, and the flange surface 33f is integrally formed with the case 33 using a deep drawing method by cutting or precision press. Is completely removed. Next, as shown in FIG. 3, it has a first pressure surface 95a that receives the inner surface of the case top surface 33a, a second pressure surface 95f that receives the inner surface of the flange surface 33f, and a third pressure surface 95g that receives the inner surface of the side surface 33g. A metal lower die 95 used as a pedestal, a pressure surface 96a for pressing the outer surface of the case top surface 33a, a second pressure surface 96f for receiving the outer surface of the flange surface 33f, and a third pressure surface 96g for receiving the outer surface of the side surface 33g. A pressure jig provided with a metal upper die 96 having the pressure surfaces 95a, 95f, 95g, 96a, 96f, and 96g with respect to the thickness direction of the case top surface 33a, the flange surface 33f, and the case side surface 33g. Low-temperature heat treatment is performed in a state where a load is applied substantially uniformly so as to sandwich the case top surface 33a, the flange surface 33f, and the case side surface 33g. At this time, as shown by hatching in FIG. 6, the area (weighted area) 99 to which the weight is applied is a curved portion of the case top surface 33a and the side surface 33g in addition to the case top surface 33a, the flange surface 33f, and the case side surface 33g. 33b and a curved portion 33c of the flange surface 33f and the side surface 33g, and the curved portions 33b and 33c preferably have an area of at least 20% or more inward from the case top surface 33a and the flange surface 33f. Here, the shapes of the case top surface 33a and the flange surface 33f are corrected by applying a weight to the respective surfaces of the case top surface 33a and the flange surface 33f. Being corrected means that the case top surface 33a and the flange surface 33f are adapted to the shape of the pressure jig whose shape is to be corrected. Therefore, if the area of the surface to which the weight is applied among the surface of the case top surface 33a and the flange surface 33f is reduced, the area adapted to the shape of the pressure jig is also reduced. When correcting each surface, the most effective is that the weight can be reduced by pressing an area of 20% or more including the curved portion as described above. In other words, the weight is most applied in the vicinity of the curved portion, and if the area to which the weight is applied is 20% or less, the weight is considerably required and the efficiency is poor. Further, the larger the area to be weighted, the higher the correction can be made. Therefore, in each surface, the area 99 of the surface to which the load is applied is preferably at least 20% or more inward from the curved portion. Thereby, the shape correction of the case side surface 33g can be performed simultaneously with flattening the case top surface 33a and the flange surface 33f. Using the bottomed cylindrical metal case 33 manufactured in this way, the piezoelectric body 6 is bonded and fixed to a predetermined surface such as the top surface 33a, or the piezoelectric body 6 is bonded and fixed to a predetermined surface such as the top surface 33a. The acoustic matching layer 4 is bonded and fixed to the surface opposite to the top surface 33a to manufacture the ultrasonic vibrator and the ultrasonic flowmeter, thereby improving the performance and safety of the ultrasonic vibrator and the ultrasonic flowmeter. Long-term reliability can be realized. The upper die 95 is provided on the outer side of the corner portion 95b that is in contact with the outer side of the curved portion 33b that is a corner portion of the case top surface 33a and the inner corner portion between the flange surface 33f and the side surface 33g. And a corner portion 95c that comes into contact. Further, the lower mold 96 is provided inside the curved portion 33c, which is an inner corner between the flange surface 33f and the side surface 33g, and a corner 96b that contacts the inner side of the curved portion 33b that is a corner of the case top surface 33a. And a corner portion 96c in contact therewith. Therefore, when a load is applied so as to sandwich the case top surface 33a, the flange surface 33f, and the case side surface 33g with the pressurizing surfaces 95a, 95f, 95g, 96a, 96f, 96g, the corner portions 95b and 96b form the curved portion 33b. A weight is applied so as to be sandwiched, and a weight is applied so that the curved portion 33c is sandwiched between the corner portions 95c and 96c.
[0048]
In the method for manufacturing a bottomed cylindrical metal case according to each example of the above embodiments of the present invention, the pressurizing force required to flatten the case top surface 33a greatly depends on the thickness of the case top surface 33a. . That is, the thicker the thickness and the higher the rigidity, the more pressure is required. However, when the thickness of the case top surface 33a is greater than 0 mm and equal to or less than 1 mm, the applied pressure required to flatten the case top surface 33a is 500 kgf / cm.²By adding the above, it is possible to flatten the case top surface 33a. Further, the pressing force required for flattening the flange surface 33f greatly depends on the thickness of the flange surface 33f. That is, the thicker the thickness and the higher the rigidity, the more pressure is required. However, when the thickness of the flange surface 33f is greater than 0 mm and equal to or less than 1 mm, the applied pressure required to flatten the flange surface 33f is 500 kgf / cm.²By adding the above, it is possible to flatten the flange surface 33f. Further, the pressure required to correct the shape of the side surface 33g greatly depends on the thickness of the side surface 33g. That is, the thicker the thickness and the higher the rigidity, the more pressure is required. However, when the thickness of the side surface 33g is greater than 0 mm and equal to or less than 1 mm, the applied pressure required to correct the shape of the side surface 33g is 500 kgf / cm.²By adding the above, it is possible to correct the shape of the side surface 33g.
[0049]
In the method for manufacturing a bottomed cylindrical metal case according to each example of the above-described embodiments of the present invention, at least the top surface 33a of the bottomed cylindrical metal case 33 is subjected to low temperature in a state of being weighted so as to be sandwiched from both sides in the thickness direction. In the low temperature heat treatment step for performing heat treatment, the low temperature heat treatment step includes a step P5 for raising the temperature of the bottomed cylindrical metal case 33, a step P6 for holding the bottomed cylindrical metal case 33 at a certain temperature, and the above. And a step P7 for lowering the temperature of the bottomed cylindrical metal case 33. After pressurizing at least the top surface 33a of the bottomed cylindrical metal case 33 so as to be sandwiched from both sides with respect to the thickness direction of the top surface 33a using the pressurizing jig 80 shown in FIGS. 8 (a) and 8 (b). 9, as shown in FIG.
[0050]
Here, as the pressure jig 80, as an example, a pressure jig including the lower mold 92 and the upper mold 91 in FIG. 1 is shown in FIGS. 8A and 8B. The pressurization jig provided with the lower mold 94 and the upper mold 93 in FIG. 2 and the pressurization jig provided with the lower mold 96 and the upper mold 95 in FIG. Therefore, the pressure jig 80 will be described as a representative example. The pressurizing jig 80 is configured such that a male thread portion 92 r on the outer peripheral surface of the lower die 92 is screwed with a female screw portion (not shown) on the inner peripheral surface of the upper die 91. By placing or fitting a cut or pressed case 33 on the upper surface and tightening the upper die 91 to the lower die 92 so as to be screwed with a predetermined torque using a torque wrench, the upper die 91 and the lower die 92 are A predetermined surface of the case 33 is pressurized between the two. Examples of the lower mold and upper mold metal of each pressing jig include stainless steel, aluminum, aluminum alloy, Ti, or Ta. Its thermal conductivity is 10 W / m · K or more, and its rigidity is 2.5 × 10¹¹The above is preferable.
[0051]
On the other hand, the thermostatic chamber 81 includes a heater 82 disposed on the lowermost side, a stainless plate 83 disposed on the heater 82 and carrying a number of the pressure jigs 80, and a fan disposed on the side surface of the thermostatic chamber. 84. The warm air heated by the heater 82 is circulated in the thermostatic chamber 81 by the fan 84. Here, a hot air circulation type thermostatic bath is used, but any system can be used as long as a predetermined low temperature heat treatment can be performed. As shown in FIG. 10, the temperature profile for performing the low-temperature heat treatment includes a process P5 for raising the temperature in the thermostatic chamber 81 and accordingly the temperature of the bottomed cylindrical metal case 33 to a certain temperature, and the temperature in the thermostatic chamber 81 and accordingly A process P6 for holding the bottom cylindrical metal case 33 at a certain temperature and a process P7 for lowering the temperature in the thermostatic chamber 81 and thus the temperature of the bottomed cylindrical metal case 33 are provided.
[0052]
In the low temperature heat treatment of the manufacturing method of the bottomed cylindrical metal case according to each example of the embodiment of the present invention, the speed of raising the temperature in the temperature step P5 for raising the temperature shown in the temperature profile of FIG. It is larger than ° C./min and desirably 5 ° C./min or less. When the speed of raising the temperature is faster than 5 ° C / min, the temperature of the entire case does not rise constantly, resulting in partial heat distribution, distortion and warpage, and the shape is different from the original. There is. In severe cases, cracks may occur.
[0053]
In the low temperature heat treatment of the manufacturing method of the bottomed cylindrical metal case according to each example of the embodiment of the present invention, the heat treatment temperature in the process P6 held at the constant temperature shown in the temperature profile of FIG. 10 is 150 to 300 ° C. It is. When the temperature is lower than 150 ° C., the effect of flattening the warping amount of the case top surface 33a is small. When the temperature exceeds 300 ° C., the effect of flattening the warping amount of the case top surface 33a is also reduced, and cracking occurs in the stress corrosion cracking test. . Moreover, if it is 300 degrees C or less, it is not necessary to use special steel etc. also about the pressurization jig | tool 80, and it can respond with normal stainless steel (SUS304 etc.). Further, regarding the productivity, if it is 300 ° C. or less, which is as low as possible, the tact time is shortened and a constant temperature bath for low-temperature heat treatment is possible with a normal product, which is advantageous. From the above, the heat treatment temperature is desirably in the range of 150 to 300 ° C. The heat treatment temperature may be constant at a certain temperature within the range of 150 to 300 ° C., for example, 170 ° C., or may vary within the range of 150 to 300 ° C.
[0054]
In the step P6 of holding at the constant temperature, the temperature holding time for holding the heat treatment temperature in the range of 150 to 300 ° C. must be 0 minutes, preferably 5 minutes, and more than 60 minutes. The effect of preventing stress corrosion cracking even when the low-temperature heat treatment exceeds 60 minutes is almost the same as that within the heat treatment time of 60 minutes. In some cases, when the heat treatment time exceeds 60 minutes, stress corrosion cracking occurs. This is because it may start (see Example 5 described later). The minimum time is preferably 5 minutes in consideration of reducing the load on the heating device. However, when the residual stress is extremely small, or depending on the material or thickness, the time is less than 5 minutes and exceeds 0 minutes. But it may be okay.
[0055]
In the step P7 for lowering the temperature shown in the temperature profile of FIG. 10, it is necessary to gradually cool the cooling rate for lowering the temperature at a rate higher than 0 ° C./min and not higher than 1.0 ° C./min. This is because the stress is stored in the case 33 when rapidly cooled or cooled at a rate exceeding 1.0 ° C./min, and the reaction is released when it is taken out from the jig 80, and warping, deformation, or internal stress is stored. Cracking occurs in the stress corrosion cracking test. Accordingly, the cooling rate must be greater than 0 ° C./min and must be gradually cooled at 1.0 ° C./min or less.
[0056]
In the low-temperature heat treatment according to each example of the embodiment of the present invention, the heat treatment atmosphere is performed in an inert gas. In this way, by performing low-temperature heat treatment in an inert gas, oxidation can be prevented even in the case of a metal that is easily oxidized, such as copper or brass.
[0057]
According to each example of the above-described embodiment of the present invention, the case top surface 33a is flattened, or the case top surface 33a and the flange surface 33f are flattened, or those flattened surfaces and the shape of the side surface 33g can be modified. The material of the cylindrical metal case 33 is preferably stainless steel, aluminum, aluminum alloy, iron, iron alloy, copper, brass, or titanium. In particular, after these materials have been subjected to cutting processing or press integral molding (for example, integral molding using a deep drawing method using a precision press), the processing oil is completely removed and the case top surface 33a and the like are pressurized. By applying the low temperature heat treatment, it is possible to prevent the case top surface 33a and the like from being flattened, or the flattening and shape modification of the side surface 33g, and stress corrosion cracking.
[0058]
The thickness of the case top surface 33a of the bottomed cylindrical metal case 33 capable of flattening the case top surface 33a of the bottomed cylindrical metal case 33 according to each example of the embodiment of the present invention is greater than 0 mm and 1 mm or less. desirable. When the thickness of the case top surface 33a exceeds 1 mm, the effect of flattening the case top surface 33a is reduced under the above conditions. When the thickness exceeds 1 mm, the case top surface 33a has a high pressure load range and a heat treatment temperature to be flattened. Therefore, if the temperature exceeds 300 ° C., special pressurizing jigs and thermostats are required. From the above viewpoint, the thickness of the case top surface 33a is desirably larger than 0 mm and not larger than 1 mm. The thickness of the flange surface 33f is desirably greater than 0 mm and 1 mm or less. If the thickness of the flange surface 33f exceeds 1 mm, the effect of flattening the flange surface 33f is reduced under the above conditions. On the other hand, when the thickness exceeds 1 mm, the flange surface 33f has a high pressure load range and the heat treatment temperature becomes high in order to flatten the surface. Therefore, if the temperature exceeds 300 ° C., special pressurizing jigs and thermostats are required. From the above viewpoint, the thickness of the flange surface 33f is desirably greater than 0 mm and 1 mm or less. Further, the thickness of the side surface 33g is desirably larger than 0 mm and not larger than 1 mm. When the thickness of the side surface 33g exceeds 1 mm, the effect of flattening the side surface 33g decreases under the above conditions. On the other hand, when the thickness exceeds 1 mm, the side surface 33g has a high pressure load range and the heat treatment temperature is high for flattening. Therefore, if the temperature exceeds 300 ° C., special pressurizing jigs and thermostats are required. From the above viewpoint, the thickness of the side surface 33g is desirably larger than 0 mm and not larger than 1 mm.
[0059]
As a jig for pressurizing the case top surface 33a and the like, any method can be used as long as the method of applying the load is a jig or pressurization system that can uniformly pressurize the pressurizing surface in the pressurizing range. Various jigs and methods may be used. Further, any heat treatment furnace used for the low temperature heat treatment can be used as long as the above temperature profile can be realized, such as a hot air circulation type, a high frequency type, and a direct heating type.
[0060]
As shown in FIG. 11, the ultrasonic transducer formed using the bottomed cylindrical metal case 33 according to each example of the above embodiment of the present invention includes at least a bottomed cylindrical metal case 33 and a case 33. The piezoelectric body 6 is attached to one surface (for example, the top surface) with an adhesive 31 and the terminal plate 7 is resistance-welded to the case 33 so as to contain the piezoelectric body 6. Terminal plate 8 incorporates terminals 8 a and 8 b for applying voltage to piezoelectric body 6, and terminal 8 a is connected to piezoelectric body 6 via conductive rubber 10. Further, the terminal 8a and the terminal plate 7 are fixed and sealed with glass 9.
[0061]
The ultrasonic transducer having the configuration shown in FIG. 11 is used in a medium having a high sound velocity such as in a liquid. In particular, the cylindrical cylindrical metal case 33 used for the ultrasonic vibrator is flat from both the acoustic viewpoint because the top surface also serves as a diaphragm and the construction surface in which the piezoelectric body 6 is bonded to the top surface with the adhesive 31. And uniformity are required. In order to realize flatness and uniformity of the top surface of the celestial cylindrical case, extremely stress is applied during cutting or press integral molding, so if no processing is performed after cutting or press integral molding, the stress is applied. Causes corrosion cracking. Therefore, the internal stress applied during processing can be relieved by controlling the appropriate temperature and time, the time to raise the temperature, the time to lower the temperature, and heating at a low temperature as a low-temperature heat treatment while applying pressure as described above. It is.
[0062]
The adhesive for the adhesive layer 31 includes urethane, cyano, and silicone resin adhesives. The adhesive is temporarily bonded to the piezoelectric body 6 and the case 33 in a viscous state, and when heated to a temperature in the range of 150 to 300 ° C., a chemical reaction occurs to be cured and finally bonded. Therefore, the low-temperature heat treatment is a heat treatment for curing the adhesive when an object to be bonded (for example, the piezoelectric body 6) is bonded to the case 33 with an adhesive (for example, the adhesive 31) in a heated state. You can also. In this way, the heat treatment process when the adherend (for example, the piezoelectric body 6) is bonded to the case 33 with the adhesive (for example, the adhesive 31) without specially setting the low-temperature heat treatment process is performed. It can also be used as a heat treatment step, and productivity can be further increased.
[0063]
As shown in FIG. 12, the ultrasonic transducer according to the modification of the above embodiment of the present invention is provided with at least a bottomed cylindrical metal case 33 and a piezoelectric body 6 on one surface of the case 33. The acoustic matching layer 4 is further provided with an adhesive 30 on the surface opposite to the surface on which the body 6 is provided. The terminal plate 7 is resistance-welded to the case 33 so as to contain the piezoelectric body 6. Terminal plate 8 incorporates terminals 8 a and 8 b for applying voltage to piezoelectric body 6, and terminal 8 a is connected to piezoelectric body 6 via conductive rubber 10. The terminal 8a and the terminal plate 7 are fixed and sealed with a glass plate 9. The ultrasonic transducer having the configuration shown in FIG. 12 is used for measuring the flow rate of city gas, LP gas, hydrogen, etc. in a gas, for example, in the configuration shown in FIGS.
[0064]
FIG. 13 and FIG. 14 are sectional views of an ultrasonic flow meter 100 provided with the ultrasonic transducer 1.
[0065]
A schematic configuration of the ultrasonic flowmeter 100 is shown. A flow rate measurement unit 11 that measures a flow rate of a fluid to be measured that flows in from an inlet passage 100a connected to a supply pipe to which a fluid to be measured such as a gas is supplied; An outlet path 100b that communicates with the unit 11 and guides the fluid to be measured to the outside, and a pair of ultrasonic transducers 17 and 18 that are provided in the flow rate measurement unit 11 and transmit and receive ultrasonic waves (each of which is connected to the ultrasonic transducer 1). And a measurement circuit 101 that measures the propagation time between the ultrasonic transducers 17 and 18, and a flow rate calculation means 102 that calculates a flow rate based on a signal from the measurement circuit 101. Therefore, an ultrasonic wave is transmitted from one ultrasonic transducer 17 to the other ultrasonic transducer 18, and an ultrasonic wave that has passed through a fluid to be measured such as a gas is received by the other ultrasonic transducer 18. Thus, the measurement circuit 101 measures the propagation time between the ultrasonic transducers 17 and 18. Then, conversely, the ultrasonic waves transmitted from the other ultrasonic transducer 17 toward the one ultrasonic transducer 18 and passed through the fluid to be measured such as gas are converted into the one ultrasonic transducer. 18, the measurement circuit 101 measures the propagation time between the ultrasonic transducers 17 and 18. In this way, the ultrasonic propagation time is measured between the pair of ultrasonic transducers 17 and 18 a predetermined number of times, and the flow rate of the fluid under measurement such as gas is calculated by the flow rate calculation means 102 based on the average value. Like to do. Therefore, the ultrasonic transducers 17 and 18 can transmit and receive. Here, the measurement circuit 101 and the flow rate calculation means 102 constitute a flow rate calculation system.
[0066]
As an example, the material constituting the flow rate measurement unit 11 is assumed to be a household gas meter for measuring the flow rate of LP gas or natural gas, and is an aluminum alloy die casting. As shown in FIG. 14, the upper plate portion 15 is screwed to the end surfaces of the side wall portions 12 and 13 via a sealing material 14 made of, for example, a cork material, and the flow rate measuring portion 11 having a rectangular channel cross section 16 is formed. . Further, as shown in FIG. 13, the ultrasonic transducers 17 and 18 are provided obliquely on the side wall portions 12 and 13 so that the transmission / reception surfaces for transmitting and receiving ultrasonic waves face each other. Specifically, the ultrasonic transducers 17 and 18 provided on the side walls 12 and 13 are fixed to the transducer mounting holes 19 and 20 via seal materials 21 and 22 made of, for example, O-rings. This is an example, and the present invention is not limited to this.
[0067]
In order to improve the measurement accuracy, it is necessary to minimize the individual variation of the opposing ultrasonic transducers as much as possible. The major factors that cause individual variation are the acoustic aspect that the flatness and uniformity of the top surface of the cylindrical case also serves as the diaphragm, and both the construction surface side that bonds the piezoelectric body and the matching layer to the top surface. Required by For this reason, a very large stress is applied during cutting or press integral molding, and processing is performed in a state that includes internal stress during processing, resulting in stress corrosion cracking. In particular, an ultrasonic vibrator used in an active gas such as city gas, LP gas, or hydrogen is absolutely not allowed to undergo stress corrosion cracking from the viewpoint of safety such as leakage. Therefore, by controlling the appropriate temperature and time, the time to raise the temperature, and the time to lower the temperature while pressurizing a predetermined part, the flatness of the case top surface etc. is secured and the internal stress applied during processing is reduced. It can be mitigated.
[0068]
Further, the top surface 33a of the case 33 and the flange surface 33f projecting in the radial direction from the end of the side surface 33g of the case 33 are parallel to each other in the thickness direction of the top surface 33a of the case 33. The top surface 33a may be sandwiched and low-temperature heat treatment may be performed in a state where the flange surface 33f is loaded from both sides in the thickness direction of the flange surface 33f. If the parallelism between the top surface 33a of the case 33 and the flange surface 33f is poor, stress is generated when the terminal plate 7 is fixed by welding to the flange surface 33f, and the stress is applied to the side surface 33g. As a result, internal stress is generated on the top surface 33a of the case 33. In order to prevent this, low-temperature heat treatment is performed in a state in which the top surface 33a is sandwiched from both sides in the thickness direction of the top surface 33a of the case 33 and the flange surface 33f is sandwiched from both sides in the thickness direction of the flange surface 33f. By applying, the top surface 33a of the case 33 and the flange surface 33f can be made parallel.
[0069]
【Example】
The effects of the above embodiment of the present invention will be described below with specific examples.
[0070]
Example 1
The case that was integrally formed with the cutting process and the press was washed with a cleaning agent FNS-70 (trade name) manufactured by Kitazawa Yakuhin, and then the top surface of the case was measured with a three-dimensional surface roughness meter. The case shape is φ12 mm, height 6 mm, and thickness 0.2 mm shown in FIG. The average flatness of the case top surface of the cutting case at this time was 10 μm, and the case top surface of the press-integrated case was 11 μm. SUS304 was used as the case material. Ten cutting cases and 10 integrated press-molded cases were placed in a bolt-type pressing jig 80 shown in FIG. 8 and tightened with a torque wrench to a torque of 11 N · m. The weight applied to the top of the case at this time was 11 N · m when measured in advance with a prescale (trade name of a pressure scale capable of measuring pressure on the film) manufactured by Fuji Photo Film Co., Ltd. The temperature profile of the heat treatment was the temperature profile shown in FIG. 10, and the heating rate was 3 ° C./min. The cooling rate at this time was 0.5 ° C./min. Then, after confirming that the temperature was lowered to room temperature, the case was taken out from the jig, the flatness of the case top surface was measured with a three-dimensional surface roughness meter, and then a corrosion cracking test was performed for 48 hours. About the judgment of the corrosion crack, the visual inspection was performed using the microscope. However, as a preliminary examination before this examination, a stress corrosion test was conducted using 10 cases made by cutting or pressing, but 10 pieces each were broken. The results are shown in Table 1.
[0071]
[Table 1]

[0072]
The flatness of the case top surface was determined by measuring the case top surface using a three-dimensional surface roughness meter and calculating the difference between the maximum value and the minimum value. At that time, the difference was determined to be 5 μm or less. In addition, as a stress corrosion cracking test, after 48 hours of testing, a test with no cracks was made acceptable by visual inspection with a microscope. As a comprehensive evaluation, a sample that passed the results of both flatness and corrosion cracking was rated as ○.
[0073]
As a result of the above, both the machined case and the press-integrated case are heat-treated with the case top surface pressed, so that the case top surface also improves flatness to 5 μm or less, and even in the stress corrosion test, it is cracked. It was confirmed that no occurred. Also, pressurizing with a jig not only improves the flatness because the top of the case conforms to the shape of the jig, but also has the effect of making the shape of the top of the case uniform and reducing individual variations in the case. It was.
[0074]
Next, whether or not the case top surface and the flange surface are flattened using the jig shown in FIG. 2 that can be heat-treated in a state where both the case top surface and the flange surface are simultaneously pressurized under the same conditions as described above. Stress corrosion cracking was investigated. The results are shown in Table 2.
[0075]
[Table 2]

[0076]
The flatness of the case top surface and the flange surface was determined by measuring the case top surface using a three-dimensional surface roughness meter and calculating the difference between the maximum value and the minimum value. At that time, the difference was determined to be 5 μm or less. In addition, as a stress corrosion cracking test, after 48 hours of testing, a test with no cracks was made acceptable by visual inspection with a microscope. As a comprehensive evaluation, a sample that passed the results of both flatness and corrosion cracking was rated as ○.
[0077]
As a result of the above, both the machined case and the press-integrated case are heat treated with the case top and flange surfaces pressed, so that the flatness of the case top and flange surfaces is improved to 5 μm or less. In addition, it was confirmed that no cracks occurred in the stress corrosion test. In addition, by applying pressure with the jig, the top and flange surfaces of the case become familiar with the shape of the jig, so the flatness is improved and the shape on the top and flange surfaces of the case is made uniform, resulting in individual variations in cases. There was also a small effect.
[0078]
Next, if the case top surface and the flange surface are flattened using the jig shown in FIG. 3 that can be heat-treated with the case top surface, the flange surface, and the case side surface pressed simultaneously under the same conditions as described above. We investigated whether the shape of the side of the case was modified and stress corrosion cracking. Roundness was used as an index for correcting the shape of the case, and a roundness measuring machine (Taricenter C-1 (trade name), manufactured by Taylor Hobson) was used to measure roundness. The results are shown in Table 3.
[0079]
[Table 3]

[0080]
The flatness of the case top surface and the flange surface was determined by measuring the case top surface using a three-dimensional surface roughness meter and calculating the difference between the maximum value and the minimum value. At that time, the difference was determined to be 5 μm or less. About roundness, 5 micrometers or less were set as the pass. In addition, as a stress corrosion cracking test, after 48 hours of testing, a test with no cracks was made acceptable by visual inspection with a microscope. As a comprehensive evaluation, a sample that passed the results of both flatness and corrosion cracking was rated as ○.
[0081]
As a result, both the machined case and the press-integrated case are heat-treated with the case top surface, the flange surface, and the case side surface pressurized, so that the case top surface and the flange surface have a flatness of 5 μm or less. As a result, the roundness was 5 μm or less. Furthermore, it was confirmed by the stress corrosion test that no cracks occurred. Also, by applying pressure with the jig, the case top surface, flange surface, and case side surface conform to the shape of the jig, so that not only flatness and roundness are improved, but also on the case top surface, flange surface, and case side surface. There was also an effect that the shape was made uniform and the individual variation of the case was reduced.
[0082]
(Example 2)
From the results of Example 1, the area of the lower mold is made constant with the upper mold area of the bolt-type pressure jig shown in FIG. We examined by changing The case shape is φ12 mm, height 5.6 mm, and thickness 0.2 mm shown in FIG. The average flatness of the case top surface of the cutting case at this time was 10 μm, and the case top surface of the press-integrated case was 11 μm. SUS304 was used as the case material. Three cutting cases and three press-molded cases were prepared for each area to be pressed. The applied pressure is 500 kgf / cm²Constant. The temperature profile of the heat treatment was the temperature profile shown in FIG. 10, and the heating rate was 3 ° C./min. The cooling rate at this time was 0.5 ° C./min. Then, after confirming that the temperature was lowered to room temperature, the case was taken out from the jig, the flatness of the case top surface was measured with a three-dimensional surface roughness meter, and then a corrosion cracking test was performed for 48 hours. About the judgment of the corrosion crack, the visual inspection was performed using the microscope. However, as a preliminary examination before this examination, a stress corrosion test was performed using 10 cases made by cutting and pressing, but all 10 cases were broken. The flatness of the case top surface was measured using a three-dimensional surface roughness meter, and the difference between the maximum value and the minimum value was defined as flatness, and the difference was determined to be 5 μm or less. In addition, a stress corrosion cracking test was performed, and a test with no cracks was made acceptable by visual observation with a microscope. The overall evaluation was a case where the flatness of the top surface of the case was 5 μm or less and no stress corrosion cracking, and a case where either one failed, or a case where both failed. Tables 4 and 5 show the results. Table 5 is a continuation of Table 4.
[0083]
[Table 4]

[0084]
[Table 5]

[0085]
From the above results, if the heat treatment is performed under pressure in an area of 20% or more from the edge including the edge of the case top surface, the flatness of the case top surface can be reduced to 5 μm or less, and stress corrosion cracking can be prevented. It turns out that you can. Also, pressurizing with a jig not only improves the flatness because the top of the case conforms to the shape of the jig, but also has the effect of making the shape of the top of the case uniform and reducing individual variations in the case. It was.
[0086]
Next, using a jig that can be heat-treated with both the case top surface and the flange surface pressurized under the same conditions as in the above study, whether the case top surface and the flange surface are flat and stress corrosion cracking. I investigated. The results are shown in Tables 6 and 7. Table 7 is a continuation of Table 6.
[0087]
[Table 6]

[0088]
[Table 7]

[0089]
From the above results, the flatness of the case top surface and the flange surface can be reduced to 5 μm or less if heat treatment is performed under pressure in an area of 20% or more from the curved portion including the curved portion of the case top surface and the flange surface, Furthermore, it has been found that stress corrosion cracking can also be prevented. In addition, by applying pressure with the jig, the top and flange surfaces of the case become familiar with the shape of the jig, so the flatness is improved and the shape on the top and flange surfaces of the case is made uniform, resulting in individual variations in cases. There was also a small effect.
[0090]
Next, if the case top surface and the flange surface are flattened using the jig shown in FIG. 3 that can be heat-treated with the case top surface, the flange surface, and the case side surface simultaneously pressurized under the same conditions as described above. We investigated whether the shape of the side of the case was modified and stress corrosion cracking. Roundness was used as an index for correcting the shape of the case, and a roundness measuring machine (Taricenter C-1, manufactured by Taylor Hobson) was used for measuring roundness. The results are shown in Tables 8 and 9. Table 9 is a continuation of Table 8.
[0091]
[Table 8]

[0092]
[Table 9]

[0093]
As a result, both the machined case and the press-integrated case are heat-treated with the case top surface, the flange surface, and the case side surface pressurized, so that the case top surface and the flange surface have a flatness of 5 μm or less. As a result, the roundness was 5 μm or less. Further, it was confirmed that no cracks were generated even in the stress corrosion test. Also, by applying pressure with the jig, the case top surface, flange surface, and case side surface conform to the shape of the jig, so that not only flatness and roundness are improved, but also on the case top surface, flange surface, and case side surface. There was also an effect that the shape was made uniform and the individual variation of the case was reduced.
[0094]
(Example 3)
Based on the result of Example 1, the pressure weight range was examined. The case shape is φ12 mm, height 5.6 mm, and thickness 0.2 mm shown in FIG. The average flatness of the case top surface of the cutting case at this time was 10 μm, and the case top surface of the press-integrated case was 11 μm. SUS304 was used as the case material. Three each were prepared for each load to pressurize the cutting case and the press-integrated case. The pressurizing was performed by changing the pressure applied to the top of the case by the torque that was put in a bolt-type jig shown in FIG. The actual weight was measured using Fuji Photo Film Co., Ltd. Prescale High Pressure (HS) (trade name of pressure scale capable of measuring pressure on the film). The temperature profile of the heat treatment was the temperature profile shown in FIG. 10, and the heating rate was 3 ° C./min. The cooling rate at this time was 0.5 ° C./min. Then, after confirming that the temperature was lowered to room temperature, the case was taken out from the jig, the flatness of the case top surface was measured with a three-dimensional surface roughness meter, and then a corrosion cracking test was performed for 48 hours. About the judgment of the corrosion crack, the visual inspection was performed using the microscope. However, as a preliminary examination before this examination, a stress corrosion test was performed using 10 cases made by cutting and pressing, but all 10 cases were broken. The flatness of the case top surface was measured using a three-dimensional surface roughness meter, and the difference between the maximum value and the minimum value was defined as flatness, and the difference was determined to be 5 μm or less. In addition, a stress corrosion cracking test was performed, and a test with no cracks was made acceptable by visual observation with a microscope. The overall evaluation was a case where the flatness of the top surface of the case was 5 μm or less and no stress corrosion cracking, and a case where either one failed, or a case where both failed. Table 10 shows the results.
[0095]
[Table 10]

[0096]
As a result, no stress corrosion cracking was observed at all applied pressures. Moreover, regarding the flatness of the case top surface, both cutting and press working are 500 kgf / cm.²From the above, it was found that 5 μm or less can be realized. Also, pressurizing with a jig not only improves the flatness because the top of the case conforms to the shape of the jig, but also has the effect of making the shape of the top of the case uniform and reducing individual variations in the case. It was.
[0097]
Next, whether or not the case top surface and the flange surface are flattened using the jig shown in FIG. 2 that can be heat-treated in a state where both the case top surface and the flange surface are simultaneously pressurized under the same conditions as described above. Stress corrosion cracking was investigated. The results are shown in Table 11.
[0098]
[Table 11]

[0099]
As a result, no stress corrosion cracking was observed at all applied pressures. In addition, regarding the flatness of the case top surface and the flange surface, both cutting and press working are 500 kgf / cm.²From the above, it was found that 5 μm or less can be realized. In addition, by applying pressure with the jig, the top and flange surfaces of the case become familiar with the shape of the jig, so the flatness is improved and the shape on the top and flange surfaces of the case is made uniform, resulting in individual variations in cases. There was also a small effect.
[0100]
Next, if the case top surface and the flange surface are flattened using the jig shown in FIG. 3 that can be heat-treated with the case top surface, the flange surface, and the case side surface simultaneously pressurized under the same conditions as described above. We investigated whether the shape of the side of the case was modified and stress corrosion cracking. Roundness was used as an index for correcting the shape of the case, and a roundness measuring machine (Taricenter C-1, manufactured by Taylor Hobson) was used for measuring roundness. The results are shown in Table 12.
[0101]
[Table 12]

[0102]
As a result, no stress corrosion cracking was observed at all applied pressures. Moreover, regarding the flatness of the case top surface and the flange surface and the roundness of the case side surface, both cutting and press working are 500 kgf / cm.²From the above, it was found that 5 μm or less can be realized. Also, by applying pressure with the jig, the case top surface, flange surface, and case side surface conform to the shape of the jig, so that not only flatness and roundness are improved, but also on the case top surface, flange surface, and case side surface. There was also an effect that the shape was made uniform and the individual variation of the case was reduced.
[0103]
(Example 4)
Based on the results of Examples 1 to 3, the heat treatment temperature was examined. The case shape is φ12 mm, height 5.6 mm, and thickness 0.2 mm shown in FIG. The average flatness of the case top surface of the cutting case at this time was 10 μm, and the case top surface of the press-integrated case was 11 μm. SUS304 was used as the case material. Three cutting cases and three press-molded cases were prepared for each heat treatment temperature. Pressurization is done in a bolt-type jig shown in FIG. 8 and tightened with a torque wrench, and 500 kgf / cm against the top of the case.²The applied pressure was applied. In that state, heat treatment was performed. The temperature profile of the heat treatment was the temperature profile of FIG. 10, the rate of temperature increase was 3 ° C./min, the holding temperature was changed from 120 to 220 ° C. by 10 ° C., held at each temperature for 1 hour, and then cooled in the furnace. The cooling rate at this time was 0.5 ° C./min. Then, after confirming that the temperature was lowered to room temperature, the case was taken out from the jig, the flatness of the case top surface was measured with a three-dimensional surface roughness meter, and then a corrosion cracking test was performed for 48 hours. About the judgment of the corrosion crack, the visual inspection was performed using the microscope. However, as a preliminary examination before this examination, a stress corrosion test was performed using 10 cases made by cutting and pressing, but all 10 cases were broken. The flatness of the case top surface was measured using a three-dimensional surface roughness meter, and the difference between the maximum value and the minimum value was defined as flatness, and the difference was determined to be 5 μm or less. In addition, a stress corrosion cracking test was performed, and a test with no cracks was made acceptable by visual observation with a microscope. The overall evaluation was a case where the flatness of the top surface of the case was 5 μm or less and no stress corrosion cracking, and a case where either one failed, or a case where both failed. Tables 13 and 14 show the results. Table 14 is a continuation of Table 13.
[0104]
[Table 13]

[0105]
[Table 14]

[0106]
From the above results, it has been found that the heat treatment temperature is in the range of 150 to 300 ° C., the flatness of the case top surface can be reduced to 5 μm or less, and stress corrosion cracking can be prevented. Also, pressurizing with a jig not only improves the flatness because the top of the case conforms to the shape of the jig, but also has the effect of making the shape of the top of the case uniform and reducing individual variations in the case. It was.
[0107]
Next, whether or not the case top surface and the flange surface are flattened using the jig shown in FIG. 2 that can be heat-treated in a state where both the case top surface and the flange surface are simultaneously pressurized under the same conditions as described above. Stress corrosion cracking was investigated. The results are shown in Table 15 and Table 16. Table 16 is a continuation of Table 15.
[0108]
[Table 15]

[0109]
[Table 16]

[0110]
From the above results, it has been found that the heat treatment temperature is in the range of 150 to 300 ° C., the flatness of the case top surface and the flange surface can be 5 μm or less, and stress corrosion cracking can be prevented. In addition, by applying pressure with the jig, the case top surface and the flange surface conform to the shape of the jig, so that not only the flatness is improved, but also the shape on the case top surface is made uniform, and the individual variation of the case is reduced. Was also seen.
[0111]
Next, if the case top surface and the flange surface are flattened using the jig shown in FIG. 3 that can be heat-treated with the case top surface, the flange surface, and the case side surface simultaneously pressurized under the same conditions as described above. We investigated whether the shape of the side of the case was modified and stress corrosion cracking. Roundness was used as an index for correcting the shape of the case, and a roundness measuring machine (Taricenter C-1, manufactured by Taylor Hobson) was used for measuring roundness. The results are shown in Table 17 and Table 18. Table 18 is a continuation of Table 17.
[0112]
[Table 17]

[0113]
[Table 18]

[0114]
From the above results, it has been found that the heat treatment temperature is in the range of 150 to 300 ° C., the flatness of the case top surface and flange surface and the roundness of the case side surface can be reduced to 5 μm or less, and further, it is possible to prevent stress corrosion cracking. did. In addition, by applying pressure with the jig, the case top surface and the flange surface conform to the shape of the jig, so that not only the flatness is improved, but also the shape on the case top surface is made uniform, and the individual variation of the case is reduced. Was also seen.
[0115]
(Example 5)
Based on the results of Examples 1 to 4, the holding time at the heat treatment temperature was examined. The case shape is φ12 mm, height 5.6 mm, and thickness 0.2 mm shown in FIG. The average flatness of the case top surface of the cutting case at this time was 10 μm, and the case top surface of the press-integrated case was 11 μm. SUS304 was used as the case material. Three cutting cases and three press-molded cases were prepared for each holding time. Pressurization is done in a bolt-type jig shown in FIG. 8 and tightened with a torque wrench, and 500 kgf / cm against the top of the case.²The applied pressure was applied. In that state, heat treatment was performed. The temperature profile of the heat treatment was the temperature profile of FIG. 10, the rate of temperature increase was 3 ° C./min, the holding temperature was 200 ° C., the holding time was increased every 10 minutes and changed to a maximum of 80 minutes, and then the furnace was cooled. The cooling rate at this time was 0.5 ° C./min. Then, after confirming that the temperature was lowered to room temperature, the case was taken out from the jig, the flatness of the case top surface was measured with a three-dimensional surface roughness meter, and then a corrosion cracking test was performed for 48 hours. About the judgment of the corrosion crack, the visual inspection was performed using the microscope. However, as a preliminary examination before this examination, a stress corrosion test was performed using 10 cases made by cutting and pressing, but all 10 cases were broken. The flatness of the case top surface was measured using a three-dimensional surface roughness meter, and the difference between the maximum value and the minimum value was defined as flatness, and the difference was determined to be 5 μm or less. In addition, a stress corrosion cracking test was performed, and a test with no cracks was made acceptable by visual observation with a microscope. The overall evaluation was a case where the flatness of the top surface of the case was 5 μm or less and no stress corrosion cracking, and a case where either one failed, or a case where both failed. Tables 19 and 20 show the results. Table 20 is a continuation of Table 19.
[0116]
[Table 19]

[0117]
[Table 20]

[0118]
From the above results, it was found that the holding time at the heat treatment temperature was longer than 5 minutes, and stress corrosion cracking began to occur when it exceeded 60 minutes. Therefore, good characteristics can be obtained when the holding time is 60 minutes or less in the heat treatment. Also, pressurizing with a jig not only improves the flatness because the top of the case conforms to the shape of the jig, but also has the effect of making the shape of the top of the case uniform and reducing individual variations in the case. It was.
[0119]
Next, whether or not the case top surface and the flange surface are flattened using the jig shown in FIG. 2 that can be heat-treated in a state where both the case top surface and the flange surface are simultaneously pressurized under the same conditions as described above. Stress corrosion cracking was investigated. The results are shown in Table 21 and Table 22. Table 22 is a continuation of Table 21.
[0120]
[Table 21]

[0121]
[Table 22]

[0122]
From the above results, it has been found that stress corrosion cracking begins to occur when the holding time at the heat treatment temperature exceeds 60 minutes. Therefore, in the heat treatment, the holding time is longer than 5 minutes and good characteristics can be obtained in 60 minutes or less. In addition, by applying pressure with the jig, the top and flange surfaces of the case become familiar with the shape of the jig, so the flatness is improved and the shape on the top and flange surfaces of the case is made uniform, resulting in individual variations in cases. There was also a small effect.
[0123]
Next, the case top surface, the flange surface, and the case side surface are flattened using the jig shown in FIG. 3 that can be heat-treated while the case top surface, the flange surface, and the case side surface are simultaneously pressurized under the same conditions as those described above. It was investigated whether or not and stress corrosion cracking. The results are shown in Table 23 and Table 24.
[0124]
[Table 23]

[0125]
[Table 24]

[0126]
From the above results, it has been found that stress corrosion cracking begins to occur when the holding time at the heat treatment temperature exceeds 60 minutes. Therefore, good characteristics can be obtained when the holding time is 60 minutes or less in the heat treatment. In addition, by applying pressure with the jig, the case top surface, flange surface, and case side surface conform to the shape of the jig, so that not only flatness and roundness are improved, but also on the case top surface, flange surface, and case side surface. There was also an effect that the shape was made uniform and the individual variation of the case was reduced.
[0127]
(Example 6)
Based on the results of Examples 1 to 5, the cooling rate in the heat treatment step was examined. The case shape is φ12 mm, height 5.6 mm, and thickness 0.2 mm shown in FIG. The average flatness of the case top surface of the cutting case at this time was 10 μm, and the case top surface of the press-integrated case was 11 μm. SUS304 was used as the case material. Three each were prepared for each cooling rate for cooling the cutting case and the press-integrated case. Pressurization is done in a bolt-type jig shown in FIG. 8 and tightened with a torque wrench, and 500 kgf / cm against the top of the case.²The applied pressure was applied. In that state, heat treatment was performed. The temperature profile of the heat treatment is the temperature profile of FIG. 10, the rate of temperature increase is 3 ° C./min, the holding temperature is 200 ° C., and cooling is performed after a holding time of 60 minutes. Several kinds of cooling rates at this time were changed to investigate how much the cooling rate contributes to the flattening of the case top surface and stress relaxation. The cooling rate is as follows: (1) Furnace cooling / slow cooling (average 0.5 ° C./min or less) (2) Air cooling (average about 1.0 ° C./min) (3) Forced cooling (average 5.0 ° C./min) Degree) (4) Four types of quenching (average of 10 ° C./min or more) were examined. Then, after confirming that the temperature was lowered to room temperature, the case was taken out from the jig, the flatness of the case top surface was measured with a three-dimensional surface roughness meter, and then a corrosion cracking test was performed for 48 hours. About the judgment of the corrosion crack, the visual inspection was performed using the microscope. However, as a preliminary examination before this examination, a stress corrosion test was performed using 10 cases made by cutting and pressing, but all 10 cases were broken. The flatness of the case top surface was measured using a three-dimensional surface roughness meter, and the difference between the maximum value and the minimum value was defined as flatness, and the difference was determined to be 5 μm or less. In addition, a stress corrosion cracking test was performed, and a test with no cracks was made acceptable by visual observation with a microscope. The overall evaluation was a case where the flatness of the top surface of the case was 5 μm or less and no stress corrosion cracking, and a case where either one failed, or a case where both failed. Table 25 shows the results.
[0128]
[Table 25]

[0129]
From the above results, if the cooling rate is greater than 0 ° C / min and less than 1.0 ° C / min, the top surface of the case can have a flatness of 5 µm or less, the internal stress is relaxed, and stress corrosion cracking can be prevented. is there. Also, pressurizing with a jig not only improves the flatness because the top of the case conforms to the shape of the jig, but also has the effect of making the shape of the top of the case uniform and reducing individual variations in the case. It was.
[0130]
Next, whether or not the case top surface and the flange surface are flattened using the jig shown in FIG. 2 that can be heat-treated in a state where both the case top surface and the flange surface are simultaneously pressurized under the same conditions as described above. Stress corrosion cracking was investigated. The results are shown in Table 26.
[0131]
[Table 26]

[0132]
From the above results, if the cooling rate is greater than 0 ° C./min and less than 1.0 ° C./min, the top and flange surfaces of the case can have a flatness of 5 μm or less, the internal stress is relaxed, and stress corrosion cracking is also prevented. It can be prevented. In addition, by applying pressure with the jig, the top and flange surfaces of the case become familiar with the shape of the jig, so the flatness is improved and the shape on the top and flange surfaces of the case is made uniform, resulting in individual variations in cases. There was also a small effect.
[0133]
Next, whether the case top surface and the flange surface are flattened using the jig shown in FIG. 3 that can be heat-treated with the case top surface, the flange surface, and the case side surface simultaneously pressurized under the same conditions as described above. Then, how much the shape of the side of the case is corrected and the stress corrosion cracking were investigated. The results are shown in Table 27.
[0134]
[Table 27]

[0135]
From the above results, if the cooling rate is greater than 0 ° C./min and less than 1.0 ° C./min, the top and flange surfaces of the case can have a flatness of 5 μm or less, and the shape of the case side surface is corrected and the internal Stress is relaxed and stress corrosion cracking can be prevented. In addition, by applying pressure with the jig, the case top surface, flange surface, and case side surface conform to the shape of the jig, so that not only flatness and roundness are improved, but also on the case top surface, flange surface, and case side surface. There was also an effect that the shape was made uniform and the individual variation of the case was reduced.
[0136]
(Example 7)
The case material was examined based on the results of Examples 1-6. The case shape is φ12 mm, height 5.6 mm, and thickness 0.2 mm shown in FIG. The average flatness of the case top surface of the cutting case at this time was 10 μm, and the case top surface of the press-integrated case was 11 μm. As the case material, SUS304, aluminum, aluminum alloy, copper, brass, and titanium were examined. Three cutting cases and three press-molded cases were prepared for each material. Pressurization is done in a bolt-type jig shown in FIG. 8 and tightened with a torque wrench, and 500 kgf / cm against the top of the case.²The applied pressure was applied. In that state, heat treatment was performed. The temperature profile of the heat treatment was the temperature profile of FIG. 10, the rate of temperature increase was 3 ° C./min, the holding temperature was 200 ° C., and after 60 minutes of holding time, cooling was performed at a rate of 0.5 ° C./min or less. Then, after confirming that the temperature was lowered to room temperature, the case was taken out from the jig, the flatness of the case top surface was measured with a three-dimensional surface roughness meter, and then a corrosion cracking test was performed for 48 hours. About the judgment of the corrosion crack, the visual inspection was performed using the microscope. However, as a preliminary study of this study, a stress corrosion test was performed using 10 cases made by cutting and pressing, but all 10 cases were broken. The flatness of the case top surface was measured using a three-dimensional surface roughness meter, and the difference between the maximum value and the minimum value was defined as flatness, and the difference was determined to be 5 μm or less. In addition, a stress corrosion cracking test was performed, and a test with no cracks was made acceptable by visual observation with a microscope. The overall evaluation was a case where the flatness of the top surface of the case was 5 μm or less and no stress corrosion cracking, and a case where either one failed, or a case where both failed. Tables 28 and 29 show the results. Table 29 is a continuation of Table 28.
[0137]
[Table 28]

[0138]
[Table 29]

[0139]
From the above results, it was found that by applying heat treatment to the above metal under pressure, the flatness of the case top surface is 5 μm or less and stress corrosion cracking can be prevented. Also, pressurizing with a jig not only improves the flatness because the top of the case conforms to the shape of the jig, but also has the effect of making the shape of the top of the case uniform and reducing individual variations in the case. It was.
[0140]
Next, whether or not the case top surface and the flange surface are flattened using the jig shown in FIG. 2 that can be heat-treated in a state where both the case top surface and the flange surface are simultaneously pressurized under the same conditions as described above. Stress corrosion cracking was investigated. The results are shown in Table 30 and Table 31. Table 31 is a continuation of Table 30.
[0141]
[Table 30]

[0142]
[Table 31]

[0143]
From the above results, it was found that stress corrosion cracking can be prevented and the flatness of the case top surface and the flange surface is 5 μm or less by performing heat treatment in a state where the metal is also pressurized. In addition, by applying pressure with the jig, the top and flange surfaces of the case become familiar with the shape of the jig, so the flatness is improved and the shape on the top and flange surfaces of the case is made uniform, resulting in individual variations in cases. There was also a small effect.
[0144]
Next, if the case top surface and the flange surface are flattened using the jig shown in FIG. 3 that can be heat-treated with the case top surface, the flange surface, and the case side surface simultaneously pressurized under the same conditions as described above. The roundness of the case side and stress corrosion cracking were examined. The results are shown in Tables 32 and 33. Table 33 is a continuation of Table 32.
[0145]
[Table 32]

[0146]
[Table 33]

[0147]
From the above results, it is possible to increase the flatness of the case top surface and flange surface by 5 μm or less and the roundness of the case side surface by applying heat treatment to the metal under pressure, and to prevent stress corrosion cracking. all right. In addition, by applying pressure with the jig, the case top surface, flange surface, and case side surface become familiar with the shape of the jig, so that not only flatness is improved, but also the shape on the case top surface, flange surface, and case side surface is made uniform. In addition, there was an effect that the variation of individual cases was reduced.
[0148]
(Example 8)
Based on the results of Examples 1 to 6, the thickness of the case top surface was examined. The case shape is φ12 mm and height 5.6 mm shown in FIG. At this time, the thickness of the case top surface was changed to 0.1 to 1.5 mm for examination. The average flatness of the case top surface of the cutting case was 10 μm, and the case top surface of the press-integrated case was 11 μm. SUS304 was used as the case material. Three cutting cases and three press-molded cases were prepared for each case top thickness. Pressurization is done in a bolt-type jig shown in FIG. 8 and tightened with a torque wrench, and 500 kgf / cm against the top of the case.²The applied pressure was applied. In that state, heat treatment was performed. The temperature profile of the heat treatment was the temperature profile shown in FIG. Then, after confirming that the temperature was lowered to room temperature, the case was taken out from the jig, the flatness of the case top surface was measured with a three-dimensional surface roughness meter, and then a corrosion cracking test was performed for 48 hours. About the judgment of the corrosion crack, the visual inspection was performed using the microscope. However, as a preliminary study of this study, a stress corrosion test was performed using 10 cases made by cutting and pressing, but all 10 cases were broken. The flatness of the case top surface was measured using a three-dimensional surface roughness meter, and the difference between the maximum value and the minimum value was defined as flatness, and the difference was determined to be 5 μm or less. In addition, a stress corrosion cracking test was performed, and a test with no cracks was made acceptable by visual observation with a microscope. The overall evaluation was a case where the flatness of the top surface of the case was 5 μm or less and no stress corrosion cracking, and a case where either one failed, or a case where both failed. Tables 34 and 35 show the results. Table 35 is a continuation of Table 34.
[0149]
[Table 34]

[0150]
[Table 35]

[0151]
As a result, if the thickness of the case top surface is 1.0 mm or less, heat treatment is performed in a state where the case top surface is pressurized to prevent stress corrosion cracking with a flatness of the case top surface of 5 μm or less. Was found to be possible. Also, pressurizing with a jig not only improves the flatness because the top of the case conforms to the shape of the jig, but also has the effect of making the shape of the top of the case uniform and reducing individual variations in the case. It was.
[0152]
Next, whether or not the case top surface and the flange surface are flattened using the jig shown in FIG. 2 that can be heat-treated in a state where both the case top surface and the flange surface are simultaneously pressurized under the same conditions as described above. Stress corrosion cracking was investigated. The results are shown in Table 36 and Table 37. Table 37 is a continuation of Table 36.
[0153]
[Table 36]

[0154]
[Table 37]

[0155]
As a result, if the thickness of the case top surface is 1.0 mm or less, by applying heat treatment in a state where the case top surface is pressurized, the flatness of the case top surface and the flange surface is 5 μm or less, and stress corrosion cracking is performed. It was found that it is possible to prevent. In addition, by applying pressure with the jig, the top and flange surfaces of the case become familiar with the shape of the jig, so the flatness is improved and the shape on the top and flange surfaces of the case is made uniform, resulting in individual variations in cases. There was also a small effect.
[0156]
Next, if the case top surface and the flange surface are flattened using the jig shown in FIG. 3 that can be heat-treated with the case top surface, the flange surface, and the case side surface simultaneously pressurized under the same conditions as described above. The roundness and stress corrosion cracking of the case side were investigated. The results are shown in Table 38 and Table 39. Table 39 is a continuation of Table 38.
[0157]
[Table 38]

[0158]
[Table 39]

[0159]
As a result of the above, if the thickness of the case top surface is 1.0 mm or less, the case top surface, the flange surface, and the case side surface are subjected to heat treatment in a pressurized state, whereby the case top surface, the flatness of the flange surface and It was found that stress corrosion cracking can be prevented when the roundness of the case side is 5 μm or less. In addition, pressurizing with a jig not only improves the flatness because the case top surface, flange surface, and case side surface conform to the shape of the jig, but also the shape on the case top flange surface and case side surface is made uniform. There was also an effect of reducing individual variation of cases.
[0160]
Example 9
Based on the examination of Examples 1 to 8, heat treatment was performed on the dome-shaped cylindrical metal case produced by press integral molding using the material SUS304 and the plate thickness of 0.2 mm, and thereafter A sound wave oscillator was produced. As the pressurization and heat treatment conditions, the pressurization is put in a bolt-type jig shown in FIG. 8 and tightened with a torque wrench, and 500 kgf / cm with respect to the top surface of the case.²The applied pressure was applied. In that state, heat treatment was performed. The temperature profile of the heat treatment was the temperature profile of FIG. 10, the rate of temperature increase was 3 ° C./min, the holding temperature was 200 ° C., and after 60 minutes of holding time, cooling was performed at a rate of 0.5 ° C./min or less. Thereafter, after confirming that the temperature dropped to room temperature, the case was removed from the jig. For comparison, a similar ultrasonic vibrator is manufactured using a cylindrical metal case that has not been heat-treated, and individual variations of the manufactured ultrasonic vibrator are represented by a correlation coefficient (350 KHz to 750 KHz) in impedance frequency characteristics. The sensitivity was compared with how much the impedance in the frequency range up to this was expressed. Regarding the sensitivity, one ultrasonic transducer as a reference was determined, and the sensitivity was confirmed by the reception sensitivity for receiving a signal transmitted from the reference ultrasonic transducer. The results are shown in Table 40.
[0161]
[Table 40]

[0162]
Based on the above results, the ultrasonic transducer fabricated using the cylindrical metal case that has been heat-treated under pressure has a high correlation coefficient in the frequency characteristics of impedance, and the sensitivity variation is very high. It has been found that since it can be kept small, the variation in the solid state of the ultrasonic transducer can be reduced, and it is possible to construct a highly accurate ultrasonic flowmeter.
[0163]
(Example 10)
Based on the examination of Examples 1 to 9, the step of adhering the piezoelectric metal body and the acoustic matching layer to the dome-shaped cylindrical metal case manufactured by press integral molding using the material SUS304 and the plate thickness of 0.2 mm In order to investigate whether it can also serve as a heat treatment process in a pressurized state, a pressure curing jig for bonding the piezoelectric body and the acoustic matching layer is used, and the top surface of the case and the flange surface are pressurized. Heat treatment was performed. As pressure and heat treatment conditions, the pressure is 500 kgf / cm against the top of the case.²The applied pressure was applied. In that state, heat treatment was performed. The temperature profile of the heat treatment is the temperature profile of FIG. 8, the rate of temperature increase is 3 ° C./min, the holding temperature is 150 ° C. which is the curing temperature of the epoxy adhesive, and after 30 minutes holding time, the temperature is 0.5 ° C./min or less. Cooled at speed. Thereafter, after confirming that the temperature dropped to room temperature, the case was removed from the jig. The case was taken out from the jig, and the flatness of the top surface of the case was measured with a three-dimensional surface roughness meter. Thereafter, a corrosion cracking test was performed for 48 hours. About the judgment of the corrosion crack, the visual inspection was performed using the microscope. However, the flatness of the case top surface was measured using a three-dimensional surface roughness meter, and the difference between the maximum value and the minimum value was defined as flatness, and the difference was determined to be 5 μm or less. In addition, a stress corrosion cracking test was performed, and a test with no cracks was made acceptable by visual observation with a microscope. The overall evaluation was a case where the flatness of the top surface of the case was 5 μm or less and no stress corrosion cracking, and a case where either one failed, or a case where both failed. Table 41 shows the results.
[0164]
[Table 41]

[0165]
Judging from the above results, it has been found that the same effect can be obtained even if a jig and an adhesion step for adhering the piezoelectric body and the matching layer to the case top surface are used. Accordingly, it is possible to prevent flattening of the case top surface and the flange surface and stress corrosion cracking in the adhesive curing step, and it can also serve as a step.
[0166]
(Example 11)
Based on the examination of Examples 1 to 10, an ultrasonic vibrator was manufactured using a cylindrical metal case manufactured by press integral molding using a material SUS304 and a plate thickness of 0.2 mm. As a pressure and heat treatment condition, 500 kgf / cm with respect to the case top surface and the flange surface²The applied pressure was applied. The temperature profile of the heat treatment is the temperature profile of FIG. 10, the rate of temperature increase is 3 ° C./min, the holding temperature is set to 150 ° C. of the epoxy adhesive, and after 30 minutes of holding time, the rate is 0.5 ° C./min or less. Cooled down. Thereafter, after confirming that the temperature dropped to room temperature, the case was removed from the jig. For comparison, a similar ultrasonic vibrator is manufactured using a cylindrical metal case that has not been heat-treated, and individual variations of the manufactured ultrasonic vibrator are represented by a correlation coefficient (350 KHz to 750 KHz) in impedance frequency characteristics. The sensitivity was compared with how much the impedance in the frequency range up to this was expressed. Regarding the sensitivity, one ultrasonic transducer as a reference was determined, and the sensitivity was confirmed by the reception sensitivity for receiving a signal transmitted from the reference ultrasonic transducer. The results are shown in Table 42.
[0167]
[Table 42]

[0168]
Based on the above results, the ultrasonic transducer fabricated using the cylindrical metal case that has been heat-treated under pressure has a high correlation coefficient in the frequency characteristics of impedance, and the sensitivity variation is very high. It has been found that since it can be kept small, the variation in the solid state of the ultrasonic transducer can be reduced, and it is possible to construct a highly accurate ultrasonic flowmeter.
[0169]
According to the above-described embodiment, at least the bottomed cylindrical metal case 33 integrally formed by cutting or pressing, and the ultrasonic transducer case 33 including at least the piezoelectric body 6 disposed on one surface has a thickness. The ultrasonic transducer case 33 integrally formed by cutting or pressing by having at least the top surface 33 subjected to low-temperature heat treatment so as to suppress stress corrosion cracking in a state of being weighted so as to be sandwiched from both sides with respect to the direction. In this case, it is possible to realize the case 33 having at least a flat case top surface 33a and no stress corrosion cracking, and it is possible to improve the yield, productivity, and long-term reliability at the time of assembling the ultrasonic transducer. Then, by using such a cylindrical metal case, the piezoelectric body 6 is disposed on the top surface 33a, so that a highly accurate and reliable ultrasonic transducer and ultrasonic flowmeter can be realized. It becomes. In addition, the top surface 33a (or the top surface 33a and the flange surface 33f) is weighted so that the top surface 33a (or the top surface 33a and the flange surface 33f) is sandwiched from both sides with a pressure jig in the thickness direction. As a result, the top surface 33a (or the top surface 33a and the flange surface 33f) conforms to the shape of the surface sandwiched by the pressurizing jig, so that not only the flatness is improved but also the top surface 33a (or the top surface 33a and the flange). The shape of the surface 33f) is also made uniform, and the individual variation of the case is reduced. Furthermore, in addition to the top surface 33a, the side surface 33g is added to the top surface 33a with respect to the thickness direction so that the side surface 33g is sandwiched between the pressure jigs from both sides, thereby forming the shape of the surface to which the pressure jig is sandwiched. Since the side surface 33g is adapted to the top surface 33a, the shape of the side surface 33g is made uniform, and the individual variation of the case is reduced.
[0170]
In addition, this invention is not limited to the said embodiment, It can implement with another various aspect. For example, the low-temperature heat treatment is a heat treatment for curing the adhesive when an object to be bonded (for example, the piezoelectric body 6) is bonded to the case 33 with an adhesive (for example, the adhesive 31) in a heated state. However, it can also be applied to other bonding processes. That is, the step of correcting the shape of the weighted surface and preventing stress corrosion cracking by performing low-temperature heat treatment in a state in which the predetermined surface is sandwiched from both sides with respect to the thickness direction of the predetermined surface of the case 33, The step of adhering the body 6 and the acoustic matching layer 4 to the case top surface 33a or the step of adhering the acoustic matching layer 4 to the case top surface 33a can be replaced. In this way, an adhesive (for example, the adhesive 6 and the acoustic matching layer 4 or the acoustic matching layer 4) is bonded to the case 33 without any special low-temperature heat treatment step. 31 and the adhesive 30 or the adhesive 30) can be combined with the low-temperature heat treatment step, and the productivity can be further increased.
[0171]
In addition, it can be made to show the effect which each has by combining arbitrary embodiment and the example of the said various embodiment suitably.
[0172]
【The invention's effect】
According to the present invention, in a case for an ultrasonic vibrator comprising at least a bottomed cylindrical metal case integrally formed by cutting or pressing, and a piezoelectric body disposed on one surface, the top surface, etc. Realize a case with a flat top surface and no stress corrosion cracking by applying low-temperature heat treatment so that stress corrosion cracking can be suppressed with the top surface sandwiched from both sides in the thickness direction. Thus, it is possible to improve yield, productivity, and long-term reliability when assembling the ultrasonic transducer. Then, by using such a cylindrical metal case, it is possible to realize a highly accurate and reliable ultrasonic vibrator and ultrasonic flowmeter.
[0173]
Specifically, according to the bottomed cylindrical metal case according to the first aspect of the present invention, it is at least a bottomed cylindrical metal case integrally formed by cutting or pressing, and is arranged on one surface. In the case of an ultrasonic vibrator equipped with a body, the case top surface is flat by having a top surface subjected to low-temperature heat treatment so that stress corrosion cracking can be suppressed in a state of being weighted so as to be sandwiched from both sides in the thickness direction. As a result, a case without stress corrosion cracking can be realized, and the yield, productivity, and long-term reliability at the time of assembling the ultrasonic transducer can be improved. Then, by using such a cylindrical metal case, it is possible to realize a highly accurate and reliable ultrasonic vibrator and ultrasonic flowmeter. Also, by applying weight so that the top surface is sandwiched from both sides with respect to the thickness direction, the flatness is improved because the top surface conforms to the shape of the pressure surface such as a pressure jig that sandwiches the top surface. In addition, the shape of the top surface and the like is made uniform, and individual variations of cases are reduced.
[0174]
According to the method for manufacturing an ultrasonic transducer case according to the second aspect of the present invention, at least a bottomed cylindrical metal case integrally formed by cutting or pressing, and a piezoelectric body disposed on one surface of the case In the method for manufacturing an ultrasonic transducer case, the weight of the top surface of the case is weighted so as to be sandwiched from both sides in the thickness direction of the top surface of the case At low temperature heat treatment. If comprised in this way, a case top surface is flat and a case without a stress corrosion cracking can be implement | achieved, and the improvement of long-term reliability can be aimed at.
[0175]
According to the method for manufacturing an ultrasonic transducer case according to the third aspect of the present invention, the weighting area for weighting the case so that the top surface of the case is sandwiched from both sides in the thickness direction of the case is the top surface. And an area having an area of at least 20% or more inward from the curved part to the top surface. If comprised in this way, the case top surface is flat and a case without stress corrosion cracking can be realized more reliably, and improvement in long-term reliability can be achieved.
[0176]
According to the method for manufacturing an ultrasonic transducer case according to the fourth aspect of the present invention, the top surface is sandwiched from both sides in the thickness direction of the top surface of the case, and the flange surface from both sides in the thickness direction of the flange surface. The low-temperature heat treatment is performed in a state of being weighted so as to sandwich. With this configuration, the flange surface can be flattened in addition to the top surface of the case, so that a case without stress corrosion cracking can be realized more reliably, and long-term reliability can be improved. it can.
[0177]
According to the method for manufacturing an ultrasonic transducer case according to the fifth aspect of the present invention, the top surface of the case and the flange surface are parallel to each other from both sides in the thickness direction of the top surface of the case. While sandwiching the top surface, low-temperature heat treatment is performed in a state where the flange surface is sandwiched from both sides in the thickness direction of the flange surface. If comprised in this way, the parallelism of the said case top surface and the said flange surface will become good, and stress will not generate | occur | produce when a terminal board is weld-fixed to the said flange surface, but the said stress will propagate along a side surface and the said case Generation of internal stress on the top surface can be prevented.
[0178]
According to the method for manufacturing an ultrasonic transducer case according to the sixth aspect of the present invention, the top surface and the flange surface of the case are sandwiched from both sides with respect to the thickness direction of the top surface and the flange surface. The weighting area to be weighted includes a curved portion between the top surface and the side surface of the case and a curved portion between the side surface and the flange surface, and at least 20% or more from each curved portion inward of the top surface and the flange surface. The area is set to be. If comprised in this way, in addition to a top | upper surface and a flange surface, in addition to a top | upper surface and a flange surface, the curved part of the said top | upper | facing surface and a side surface and the curved part of a side | surface and a flange surface can be included. When correcting and flattening, the curved portion adjacent to the predetermined surface can be corrected, and the correcting operation can be performed most efficiently. Furthermore, the correction operation can be performed more efficiently by setting the weighted area to an area of at least 20% or more inward of the flange surface.
[0179]
According to the method for manufacturing an ultrasonic transducer case according to the seventh aspect of the present invention, the case side surface of the case is subjected to low-temperature heat treatment in a state of being weighted so as to be sandwiched from both sides with respect to the thickness direction of the case side surface. I try to give it. With this configuration, it is possible to realize a case in which the top surface of the case is flat and the shape of the side surface of the case can be corrected and there is no stress corrosion cracking, and long-term reliability can be improved. Moreover, as a result of correcting the shape of the side surface, variations in the resonance frequency can be reduced.
[0180]
According to the method for manufacturing an ultrasonic transducer case according to the eighth aspect of the present invention, the weighted surface is sandwiched from both sides by a pressure jig or the like with respect to the thickness direction of the weighted surface of the case. The load applied to the load is 500 kgf / cm²That's it. If comprised in this way, the said load to load will be 500 kgf / cm.²If it is less than that, it is not always possible to achieve flattening, but the load to be applied is 500 kgf / cm.²By setting it as the above, planarization can be achieved reliably.
[0181]
According to the method for manufacturing an ultrasonic transducer case according to the ninth aspect of the present invention, the low-temperature heat treatment includes a step of raising the temperature of the case, a step of holding the case at a certain temperature, And a step of lowering the temperature. If comprised in this way, the effect of each said aspect can be achieved more reliably and stably.
[0182]
According to the method for manufacturing an ultrasonic transducer case according to the tenth aspect of the present invention, the holding temperature is set to 150 to 300 ° C. in the step of holding at the constant temperature of the low-temperature heat treatment. If comprised in this way, since the holding temperature is 150 degreeC or more, the effect of flattening the curvature amount of a case top surface can be anticipated, and since the holding temperature is 300 degrees C or less, the curvature amount of a case top surface is flattened. Can be expected, and no cracking occurs in the stress corrosion cracking test. In addition, since the holding temperature is 300 ° C or less, it is not necessary to use special steel for the pressure jig, and it can be handled with ordinary stainless steel (SUS304, etc.), and the tact time is also reduced in terms of productivity. In addition, a thermostatic chamber for low-temperature heat treatment is also advantageous because it can be a normal product.
[0183]
According to the method for manufacturing an ultrasonic transducer case according to the eleventh aspect of the present invention, in the step of holding the heat treatment temperature at a certain constant temperature, the holding time is set to be greater than 5 minutes and within 60 minutes. Yes. If comprised in this way, while being able to perform low-temperature heat processing efficiently in the time as short as less than 60 minutes, heat processing time is not too long and stress corrosion cracking does not begin to arise.
[0184]
According to the method for manufacturing an ultrasonic transducer case according to the twelfth aspect of the present invention, in the low-temperature heat treatment, the rate of decreasing the temperature is greater than 0 ° C./min and less than or equal to 1.0 ° C./min. Yes. If configured in this way, since there is no rapid cooling or cooling at a rate exceeding 1.0 ° C./min, stress is stored in the case, warping or deformation occurs, and internal stress is stored, so stress corrosion There is no such thing as cracking in the cracking test.
[0185]
According to the method for manufacturing an ultrasonic transducer case according to the thirteenth aspect of the present invention, the material constituting the processed metal case is mainly stainless steel, aluminum, an aluminum alloy, copper, brass, or titanium. To be. If comprised in this way, the said various effect can be reliably achieved with such a general purpose material.
[0186]
According to the method for manufacturing an ultrasonic transducer case according to the fourteenth aspect of the present invention, the thickness of the case material is greater than 0 mm and not greater than 1 mm. If comprised in this way, since the thickness of a case top surface is larger than 0 mm and is 1 mm or less, the effect which prevents a stress corrosion cracking by low-temperature heat processing will not fall, and the sensitivity of the ultrasonic wave of an ultrasonic transducer | vibrator Decline can be prevented.
[0187]
According to the manufacturing method of the bottomed cylindrical metal case according to the fifteenth aspect of the present invention, the low-temperature heat treatment is performed for heating the adhesive when the adherend is bonded to the case with an adhesive in a heated state. It is made to be processing. In this way, the heat treatment process for adhering an object to be bonded to the case with an adhesive can also be used as the low temperature heat treatment process, without setting a special low temperature heat treatment process, and more productivity can be achieved. Can be increased.
[0188]
The ultrasonic transducer case according to the sixteenth aspect of the present invention is manufactured by the ultrasonic transducer case manufacturing method according to any one of claims 2 to 15. With this configuration, the top surface of the case is flattened by performing low-temperature heat treatment so that stress corrosion cracking is suppressed in a state where the top surface is sandwiched from both sides in the thickness direction such as the top surface. The case without stress corrosion cracking can be used as a case for ultrasonic transducers, and it is possible to improve the yield, productivity and long-term reliability when assembling ultrasonic transducers. It is possible to provide an ultrasonic transducer with high height.
[0189]
According to the method for manufacturing an ultrasonic transducer according to the seventeenth aspect of the present invention, at least a bottomed cylindrical metal case integrally formed by cutting or pressing, and a piezoelectric body disposed on one surface of the case are provided. In the method for manufacturing an ultrasonic vibrator, the low-temperature heat treatment is performed in a state where the top surface of the case is sandwiched from both sides with respect to the thickness direction of the case. The piezoelectric body is fixed to the top surface. In this case, in the case having the effect of the first aspect and seamless to the fluid flowing through the flow path, the case top surface is flat and the stress corrosion cracking is the same as the effect of the second aspect. Can be used as a case for an ultrasonic transducer, and it is possible to realize an ultrasonic flowmeter with high yield and productivity at the time of assembly of the ultrasonic flowmeter, and with high accuracy and high reliability. .
[0190]
According to the method for manufacturing an ultrasonic transducer according to the eighteenth to twenty-ninth aspects of the present invention, the same function and effect as those of the third to fourteenth aspects can be achieved.
[0191]
According to the ultrasonic transducer in accordance with the thirtieth aspect of the present invention, in the ultrasonic transducer in which the acoustic matching layer is provided on the surface opposite to the surface on which the piezoelectric body is provided, in the thickness direction of the case top surface. On the other hand, a process of preventing the top surface shape modification and stress corrosion cracking by performing low temperature heat treatment in a state where the top surface is sandwiched from both sides, the piezoelectric body and the acoustic matching layer, or either one of them. It replaces with the process of adhere | attaching on the said top | upper surface. In this way, an adhesive (for example, an adhesive and an adhesive, for example, a piezoelectric body and the acoustic matching layer) is attached to the case without setting a special low-temperature heat treatment step. Alternatively, the heat treatment step when bonding with an adhesive) can be combined with the low-temperature heat treatment step, and productivity can be further increased.
[0192]
The ultrasonic transducer according to the thirty-first aspect of the present invention is manufactured by the method for manufacturing an ultrasonic transducer according to any one of the seventeenth to thirtieth aspects. In this way, a case with a flat top surface and no stress corrosion cracking can be realized, and the yield, productivity, and long-term reliability when assembling the ultrasonic transducer can be improved. Then, by using such a cylindrical metal case, it is possible to realize a highly accurate and reliable ultrasonic vibrator and ultrasonic flowmeter.
[0193]
The ultrasonic transducer according to the thirty-second aspect of the present invention is further provided with an acoustic matching layer disposed on a surface opposite to the surface on which the piezoelectric body is provided. In this case, in the case having the effect of the first aspect and seamless to the fluid flowing through the flow path, the case top surface is flat and the stress corrosion cracking is the same as the effect of the second aspect. Can be used as a case for an ultrasonic transducer, and it is possible to realize an ultrasonic flowmeter with high yield and productivity at the time of assembly of the ultrasonic flowmeter, and with high accuracy and high reliability. .
[0194]
According to the ultrasonic flowmeter of the thirty-third aspect of the present invention, the flow measurement unit through which the fluid to be measured flows and the pair of the thirty-first or thirty-second aspects provided in the flow measurement unit for transmitting and receiving ultrasonic waves. An ultrasonic transducer, a measurement circuit for measuring a propagation time between the ultrasonic transducers, and a flow rate calculation means for calculating a flow rate based on a signal from the measurement circuit. In this case, in the case having the effect of the first aspect and seamless to the fluid flowing through the flow path, the case top surface is flat and the stress corrosion cracking is the same as the effect of the second aspect. Can be used as a case for an ultrasonic transducer, and it is possible to realize an ultrasonic flowmeter with high yield and productivity at the time of assembly of the ultrasonic flowmeter, and with high accuracy and high reliability. .
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing a state where a case top surface of a case for an ultrasonic transducer is pressurized in a method for manufacturing a bottomed cylindrical metal case according to a first example of an embodiment of the present invention. .
FIG. 2 is a partial cross-sectional view showing a state in which a case top surface and a flange surface of an ultrasonic transducer case are pressurized in the method for manufacturing a bottomed cylindrical metal case according to the second example of the embodiment of the present invention. FIG.
FIG. 3 shows a state in which a case top surface, a flange surface, and a case side surface of an ultrasonic transducer case are pressurized in the method for manufacturing a bottomed cylindrical metal case according to the third example of the embodiment of the present invention. FIG.
FIG. 4 is a perspective view showing a pressurizing region of the top surface of the case of the ultrasonic transducer case with hatching and a thick line in the manufacturing method of the bottomed cylindrical metal case according to the first example of the embodiment of the present invention. is there.
FIG. 5 shows hatching and bold lines in the pressurization region of the case top surface and the flange surface of the ultrasonic transducer case in the manufacturing method of the bottomed cylindrical metal case according to the second example of the embodiment of the present invention. It is a perspective view.
FIG. 6 shows a method for manufacturing a bottomed cylindrical metal case according to a third example of the embodiment of the present invention, in which the pressure areas on the case top surface, flange surface, and case side surface of the ultrasonic transducer case are hatched and It is a perspective view shown by a thick line.
7A and 7B are a perspective view showing a circular cylindrical case and a perspective view showing a rectangular case, respectively.
FIGS. 8A and 8B are exploded perspective views showing the configuration of a pressing jig used in the method for manufacturing a bottomed cylindrical metal case according to the first example of the embodiment of the present invention, respectively. It is a perspective view which shows the state pressurized with the pressurization jig | tool.
FIG. 9 is a perspective view showing a configuration of a thermostatic chamber and a state where a pressurizing jig is inserted.
FIG. 10 is a view showing a temperature profile of heat treatment.
FIG. 11 is a view showing an ultrasonic transducer using the bottomed cylindrical metal case according to the embodiment of the present invention.
FIG. 12 is a view showing another ultrasonic transducer using the bottomed cylindrical metal case according to the embodiment of the present invention.
FIG. 13 is a diagram showing an ultrasonic flowmeter including an ultrasonic transducer having a bottomed cylindrical metal case according to the embodiment of the present invention.
14 is a view showing a cross section of the ultrasonic flowmeter of FIG. 13;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 4 ... Acoustic matching layer, 6 ... Piezoelectric body, 7 ... Terminal board, 8a ... Terminal, 8b ... Terminal, 9 ... Glass plate, 10 ... Conductive rubber, 11 ... Flow measuring part, 12 ... Side wall part, 13 ... Side wall part, DESCRIPTION OF SYMBOLS 14 ... Seal material, 15 ... Upper board part, 16 ... Channel cross section, 17 ... Ultrasonic vibrator, 18 ... Ultrasonic vibrator, 19 ... Vibrator attachment hole, 20 ... Vibrator attachment hole, 21 ... Seal material, 22 ... Sealing material, 30, 31 ... Adhesive, 33 ... Bottomed cylindrical metal case, 33a ... Case top surface, 33b, 33c ... Curved part, 33f ... Flange surface, 33g ... Case side surface, 80 ... Pressure jig , 81 ... constant temperature bath, 82 ... heater, 83 ... stainless steel plate, 84 ... fan, 91, 93, 95 ... upper mold, 91a, 93a, 95a ... first pressure surface, 93f, 95f ... second pressure surface, 95b, 95c ... Corner, 95g ... Third pressure surface, 92, 94, 96 ... Lower mold, 2a, 94a, 96a ... 1st pressurization surface, 94f, 96f ... 2nd pressurization surface, 94b, 94c, 96b, 96c ... Corner part, 96g ... 3rd pressurization surface, 99 ... Area where load is applied, 100 ... Ultrasonic flow rate 100a ... inlet passage, 100b ... outlet passage, 101 ... measurement circuit, 102 ... flow rate calculating means, P5 ... step of raising temperature, P6 ... step of holding at a constant temperature, P7 ... step of lowering temperature.

Claims (2)

A bottomed cylinder having a top surface (33a) and a side surface (33g), and a bottomed cylindrical metal case (33) integrally formed by cutting or pressing;
A piezoelectric body (6) disposed on the top surface (33a) of the case;
In the method of manufacturing an ultrasonic transducer, an ultrasonic transducer for manufacturing a gas meter including an acoustic matching layer (4) disposed on a surface opposite to the surface on which the piezoelectric body (6) is provided,
And an upper mold of metal with a threaded portion, between the lower mold of metal with a threaded portion, seen write sandwiched the top surface of (33a) from both sides in the thickness direction of the top surface (33a), and said side surfaces the (33 g) seen write sandwiched from both sides in the thickness direction of the side face (33 g), the weighted state by screwing the other threaded portion of one of the threaded portion of the screw portion of the screw portion and the lower die of the upper die in, look at including the step of applying a heat treatment,
The upper mold integrally covers the outside of the top surface (33a) and the side surface (33g) of the case, and the lower mold is formed of the top surface (33a) and the side surface (33g) of the case. A method of manufacturing an ultrasonic transducer, wherein weighting is performed so as to integrally cover an inner side .   The method for manufacturing an ultrasonic transducer according to claim 1, wherein the case has a cylindrical shape.

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