JP3627614B2 - Drainage pump - Google Patents

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JP3627614B2
JP3627614B2 JP2000072448A JP2000072448A JP3627614B2 JP 3627614 B2 JP3627614 B2 JP 3627614B2 JP 2000072448 A JP2000072448 A JP 2000072448A JP 2000072448 A JP2000072448 A JP 2000072448A JP 3627614 B2 JP3627614 B2 JP 3627614B2
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sprayed film
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亮二 岡田
雅之 山田
国雄 高田
健二 大谷
宏二 会沢
光明 羽田
俊宏 山田
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Hitachi Ltd
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Description

【０００１】
【発明の属する技術分野】
本発明は排水ポンプに係り、特に軸受部に清浄水を供給することなく運転するポンプに適した耐摩耗性と高い信頼性及び組立て性に優れた軸受装置、その軸受装置を用いた排水ポンプとその軸受部の製造方法に関するものである。
【０００２】
【従来の技術】
近年の急激な都市化に伴い、降雨水量のほとんどが排水溝に流れ込むため排水が追いつかず、道路に溢れだす都市型洪水が増加する傾向にある。これに対処すべく排水ポンプシステムを装備した排水機場が設けられているが、排水機場の増加に伴い運転維持管理費が増大するという問題があり、自動運転による排水ポンプシステムが検討されている。この排水ポンプシステムの課題は高性能化、高信頼性化であり、現在、これらに対応する技術として、ポンプの無給水運転技術、大容量化、及び先行待機運転が検討されている。
【０００３】
無給水運転技術とは、軸受、スリーブ間に清浄水を供給することなく運転するものである。清浄水の供給装置がないため、清浄水供給装置、清浄水供用センサー等の故障による誤動作がなく信頼性が高い。無給水運転技術を可能とするためには、排水に含まれる土砂が進入しても摩耗しない軸受装置が必要である。
【０００４】
従来の無給水ポンプ用軸受装置には、耐摩耗性、耐食性に優れるタングステンカ−バイド（以下、ＷＣと称する）製スリーブ（焼結体）とセラミックス製軸受（焼結体）との組合せが用いられてきた。ＷＣ製スリーブとセラミックス製軸受との組合せ構造に関しては、特開昭６０−８１５１７号公報、特開昭６０−８８２１５号公報に開示されている。
【０００５】
一方、ポンプの大容量化は必然的に軸受の大口径化を必要とする。しかしながら、従来のＷＣスリーブとセラミックス軸受との組合せによる軸受装置のままでは、大口径の焼結体スリーブ、焼結体軸受が必要となる。しかしながら、焼結技術が十分に対応できない、さらに部品重量が大きくなり組立て作業が難しくなるという問題があった。そのため、セラミックスと同等の硬さを有する皮膜を被覆する硬質膜コーティング技術が広く検討されている。尚、硬質膜として溶射膜を利用した例として、ＷＣ溶射膜を被覆したスリーブとセラミックス軸受との組合せを用いた無給水排水ポンプが、「トライボロジスト」、第３６巻、第２号の１４４頁から１４７頁に明示されている。
【０００６】
多くの場合、排水ポンプ軸受部には硬質被膜として溶射膜が利用される。しかし、溶射膜は同組成の焼結体よりも硬度、強度の点で劣るため、溶射膜の硬度、強度を上げる方法が検討されている。例えば、５０％Ｃｒ−５０％Ｎｉからなるプラズマ溶射膜を、溶射した後、約７００℃〜８００℃の温度で約１〜１００時間保持し、溶射膜の接着力と強度を高める技術が特開昭５７−２８７２号公報に開示されている。又、ニッケル−リン（ＮｉＰ）を主成分とし２０〜８０％のＮｉＣｒの溶射膜をＦｅ系材料の上に形成し、６００℃〜１０００℃の温度で熱処理を行い、溶射膜の強度を高める方法が特開昭６０−１４９７６２号公報に開示されている。
【０００７】
先行待機運転とは、排水開始前に排水可能水位より低い水位状態で空転運転をすることであり、排水可能水位に達した時点で全力運転が可能で、急激な排水増加にすばやく対応できる。しかし、先行待機運転を行うには、軸受は短時間ながら摺動部に排水を含まない空転運転を行うため、軸受、スリーブ間の摩擦係数が極めて低く、ドライ摺動によっても損傷しないことが求められる。
【０００８】
長時間の空転運転を行う先行待機運転と、無給水運転を両立する軸受はいまだ開発されておらず、空転運転時に軸受摺動部に外部より給水する方法が検討され、特開昭５５−９０７１８号公報に開示されている。
【０００９】
【発明が解決しようとする課題】
土砂を含む水を排水するためには、軸受の耐摩耗性は不可欠である。無給水軸受の場合は軸受、スリーブを保護する清浄水の供給がないため、スラリーに対する耐摩耗性は特に重要である。土砂水に含まれる土砂粒子のほとんどが長石と石英であり、最高硬さがビッカース硬度（以下、Ｈｖと称する）１０００程度（石英）である。従って、軸受、スリーブに必要とされる硬度はＨｖ１０００以上である。
【００１０】
ＷＣ，ＳｉＣ，窒化珪素（以下、Ｓｉ３Ｎ４と称する）の焼結体であれば、その硬度はＷＣがＨｖ約１４００，ＳｉＣが約２８００、Ｓｉ３Ｎ４が約１６００といずれもＨｖ１０００以上であり、硬度の点では十分で耐摩耗性も優れている。しかし、焼結技術、組立て作業性、製造コストを考慮すると、スリーブ、軸受の全体をＷＣ，ＳｉＣ又はＳｉ３Ｎ４の焼結体で製作するのには大きさに限界がある。そこで、上記のごとく焼結体に替わる硬質被膜を用いることが検討されている。摩耗量を考慮すれば、膜厚は数１００μｍ以上必要であるため、硬質被膜の製法が限られる。排水ポンプ軸受部用の硬質被膜としては、比較的膜厚が得られ、高硬度の得られるＷＣ，Ｃｒ３Ｃ２を主成分とする膜厚１００〜２００μｍ程度の溶射膜が広く用いられている。しかし、溶射法で形成したＷＣ，Ｃｒ３Ｃ２を主成分とする溶射膜は、材質、形成法、条件にもよるが一般に焼結体に比べ硬度が低く、約Ｈｖ６００〜１０００程度である。
【００１１】
従来の各種溶射膜の硬度と土砂水に対する耐摩耗性との関係を図２１で説明する。図２１は、実施例において説明する要素試験によって測定した摩耗率である。各種溶射膜はステンレス鋼（以下、ＳＵＳと称する）板の上に形成した各種溶射膜を回転側試験片に用い、固定側試験片にはα−ＳｉＣを用いた。その他の試験条件は、面圧が２ｋｇ／ｃｍ２、周速が０．５ｍ／ｓ、土砂水に含まれる珪砂濃度が９ｗｔ％である。尚、試験片形状や摺動方式などの詳細は、実施例に示した図１９の試験条件と同様である。
【００１２】
図２１の横軸は溶射膜の断面ビッカース硬度であり、縦軸はＷＣ−１２％Ｃｏ焼結体の摩耗率を基準として規格化した相対摩耗率である。溶射膜１、溶射膜２、溶射膜３は、高速フレーム溶射法及び爆発溶射法で作成した、ＷＣ、若しくはＣｒ３Ｃ２を主成分とする従来の溶射膜である。図２１に示すように、土砂水に対する耐摩耗性は、溶射膜の硬度に強く依存し、前述のごとくビッカース硬度で１０００以上が良好である。図２１の結果からは、現状の溶射膜では十分な硬度と土砂水に対する耐摩耗性が得られないことが分かる。
【００１３】
一般に溶射とは、ＷＣ粒子、Ｃｒ３Ｃ２粒子のような硬質粒子だけを加熱して吹き付けるのではなく、結合材としてＮｉ、Ｃｒ、Ｃｏ等の金属粒子をまぜ同時に加熱して吹き付け、溶解した金属粒子によってＷＣ粒子、Ｃｒ３Ｃ２粒子を連結して被膜を形成するものである。溶射膜の硬度が焼結体よりも低いのは、溶射膜中のＷＣ粒子やＣｒ３Ｃ２粒子の硬度が低いのではなく、ＷＣ粒子、Ｃｒ３Ｃ２粒子をつなぐ結合材に空孔等の欠陥があるため、或いは結合材とＷＣ粒子、Ｃｒ３Ｃ２粒子との結合力が不十分なためである。
【００１４】
ＷＣ粒子、Ｃｒ３Ｃ２粒子間の結合力を増すために、様々な溶射法の改善がなされている。例えば溶射粒子の速度を増した、可燃性ガスの燃焼エネルギを利用した高速フレーム溶射、可燃性ガスの爆発を利用した爆発溶射などが開発されており、従来のプラズマ溶射膜よりも溶射時の粒子速度を高め、より高硬度の溶射膜を形成することができる。しかしながら、これらの各溶射法による溶射膜でも土砂水に対する耐摩耗性は充分ではなく、その硬度が低いためであることが図１８に示した要素試験で明らかとなっている。
【００１５】
前記従来技術、特開昭６０−８１５１７号公報及び特開昭６０−８８２１５号公報に開示のセラミック軸受には、軸受、スリーブが大口径化することによって生じる、焼結技術の困難、信頼性の低下、重量増加による組立て性の低下についての検討が加えられていない。
【００１６】
前記従来技術、ＷＣ溶射膜とセラミックス軸受（焼結体）との組合せを用いた無給水排水ポンプ（「トライボロジスト」、第３６巻、第２号）については、ＷＣ、或いはＣｒ３Ｃ２を主成分とする溶射膜の硬度、耐摩耗性、信頼性についての検討が加えられていない。
【００１７】
前記従来技術、特開昭５７−２８７２号公報及び特開昭６０−１４９７６２号公報に開示の溶射膜の改質方法では、主な母材材料であるＦｅ系材料と熱膨張率の近い材料、或いは加熱によって変質の無い材料に限られ、高硬度が得られるＷＣ、或いはＣｒ３Ｃ２を主成分とする溶射膜においては、加熱温度が高いため熱膨張差が大きくなる。その結果被膜が破断しそのままの利用は難しい。更に、ポンプ等の水中で使用する機器では、主材料はＳＵＳに限定される。従って、前記従来技術に示した加熱による溶射膜の改質を適用した場合、加熱温度が下地のＳＵＳの焼きなまし温度、もしくは粒界腐食に対する鋭敏化温度以上の高温となり、下地の硬度、耐食性が低下し、結果として信頼性が低くなるという問題がある。
【００１８】
即ち、前記従来技術においてはＦｅ系材料と熱膨張率差の大きいＷＣを主成分とする溶射膜の改質についての検討がなされていない。更に、下地材料の硬度、耐食性変化についての考慮がなされていない。
前記従来技術、特開昭５５−９０７１８号公報に開示されている、軸受摺動部に外部より給水する方法では、外部給水装置の誤動作によって排水機場の停止が発生し、緊急時に排水が停止する可能性があり、信頼性に問題があった。
【００１９】
本発明は、前記従来技術に鑑みなされたものであり、排水ポンプシステムに適用可能な、耐摩耗性と組立て性に優れ、信頼性が高い軸受装置、その軸受装置を用いた排水ポンプと軸受装置の製造方法を提供することを目的とする。
【００２０】
【課題を解決するための手段】
本発明の課題である軸受装置の摺動面に被覆した溶射膜の耐摩耗性を向上させるには、ＷＣ又はＣｒ３Ｃ２を主成分とする溶射膜の溶射後に、熱応力によって溶射膜の接着力が低下せず、溶射膜が変質せず、更に下地のＳＵＳの硬度が極端に低下しない、さらに粒界腐食に対する鋭敏化が生じない温度条件で加熱することにより達成される。
【００２１】
本発明の課題は例えば、軸受及びこの軸受と摺動するスリ−ブとを備えた軸受装置に用いる軸受及びスリ−ブのいずれか一方若しくは両方の摺動面に次のような溶射膜を被覆することで解決される。被覆する溶射膜はＷＣを主成分としてＮｉ、Ｃｒ又はＣｏのいずれか１つ若しくは複数を結合材とするもの又はＣｒ３Ｃ２を主成分としてＮｉとＣｒを結合材とする溶射膜を被覆するものであって、溶射膜の表面に形成される２０μｍ以上の大きさの空孔の密度が１５個／ｍｍ２以下のものである。
【００２２】
さらに、被覆された溶射膜は、被覆後３００℃以上５５０℃以下の温度で１時間以上加熱され、被膜硬さがビッカース硬さで１０００以上に改善され、土砂水に対する十分な耐摩耗性を発揮するものである。
【００２３】
又溶射膜を被覆する軸受、スリ−ブの材質はＦｅ系金属であれば良いが、望ましくはステンレス鋼が良い。
【００２４】
又軸受又はスリ−ブのいずれか一方を上記の溶射膜を被覆したものとした場合、他方は摺動面にＳｉＣ若しくはＳｉ３Ｎ４を配したものか、全体がＳｉＣ若しくはＳｉ３Ｎ４からなるものでもよい。又、スリ−ブ若しくは軸受は２個以上に分割しても良い。
【００２５】
軸受部材としては、所定形状に加工したステンレス鋼製軸受部材の摺動部にＷＣを主成分として結合材にＮｉ、Ｃｒ又はＣＯのいずれか１つ若しくは複数を含む溶射膜又はＣｒ３Ｃ２を主成分として結合材にＮｉとＣｒを含む溶射膜を形成した後、３００℃以上５５０℃以下の温度で１時間以上加熱し、その後所定の寸法に仕上加工することにより製造する。
【００２６】
一般に、ＷＣ、Ｃｒ３Ｃ２を主成分とする溶射膜を加熱すると、被膜の硬度を増す役割の歪が消失し硬度が低下すると言われていた。又、Ｆｅ系材料（本発明の実施例ではＳＵＳ４０３）を下地材料としその上に熱膨張率の小さいＷＣ又はＣｒ３Ｃ２を主成分とする溶射膜を被覆した場合、両者の熱膨張率差のため、膜形成後に加熱すると熱応力による被膜接着力の低下、更に加熱によるＷＣ粒子又はＣｒ３Ｃ２粒子の酸化が生じ溶射膜の特性が低下すると考えられてきた。このため、ＷＣ又はＣｒ３Ｃ２を主成分とする溶射膜の、溶射後の加熱は望ましいとは考えられていなかった。しかし、加熱条件を選べば、溶射膜に悪影響を与えることなく硬度を増すことができる。例えば、３００℃以上５５０℃以下の温度で１時間以上加熱しすることで溶射膜硬さが増し、土砂水に対して十分な耐摩耗性を示す。その機構及び検討結果の詳細は、実施例で説明する。
【００２７】
溶射膜に空孔が存在すると、溶射膜自体の強度も減り、且つＷＣ粒子、或いはＣｒ３Ｃ２粒子間の結合力も低下するため、摺動中にＷＣ粒子、或いはＣｒ３Ｃ２粒子が脱落し、耐摩耗性を低下させる原因となる。しかし、空孔を消滅させるために膜形成後に高温で加熱すると、前述のごとく結合材粒子、ＷＣ粒子又はＣｒ３Ｃ２粒子の酸化、溶射膜の接着力の低下、及び下他材料の硬度、耐食性低下が生じ、結果的には信頼性を低下させる原因となる。しかし本発明によれば、ＷＣ又はＣｒ３Ｃ２溶射膜の酸化、熱応力による膜接着力の低下、及び下他材料の硬度、耐食性低下が生じないような低温度でも、温度及び加熱時間を適切に選定すれば溶射膜の空孔が減り、且つ空孔の大きさが小さくなり、溶射膜の硬度が増すことが明らかとなった。
【００２８】
特に、本条件で加熱すると、結合材粒子、ＷＣ粒子又はＣｒ３Ｃ２粒子の最大粒子径を超える２０μｍ以上の大きな空孔が減少することが判明した。２０μｍ以上の大きな空孔はＷＣ粒子又はＣｒ３Ｃ２粒子の脱落を生じさせる直接的な原因となる。従って２０μｍ以上の大きな空孔の減少は、溶射膜の強度を向上させるように作用する。更に２０μｍ以上の大きな空孔が減ると、被膜に延性が付与されて、衝撃に対する抵抗力が増し、被膜の破壊、剥離が減少し、被膜の信頼性が増す。
また、空孔は、溶射膜の腐食発生点となるため、空孔を減らすことによってＷＣ粒子間が緻密になり、粒子間に生じる腐食が抑制され、排水に対する耐食性が増す。
また、本発明の排水ポンプを先行待機運転用として用いても無潤滑状態での運転も可能な軸受装置を用いているため十分な信頼性を有する。
【００２９】
更に、スリーブ又は軸受を分割構造とすることにより、製作が容易となり特に大径のものにおいて効果が大きい。
【００３０】
【発明の実施の形態】
本発明の実施例を図１〜図２０を用いて説明する。
図１は本発明の一実施例の排水ポンプの構造を示す縦断面図である。通常、排水ポンプには、インペラ近くと、上部との２個所に軸受が設けられている。本実施例の軸受装置は、両方の軸受に適用できるものである。図１において、１は主軸、２は主軸に取り付けられているスリーブであり、３は軸受である。本実施例においては主軸１、スリ−ブ２及び軸受３ともにＳＵＳ４０３を用いた。
【００３１】
又、本ポンプにはケーシングの排水吸込み口に、パイプが設置されており、一端はケーシングのリブに支持され、他端は排水機場の床に支持され、大気に開口している。
本ポンプでは排水水位が低い場合、ポンプ内圧と大気間に圧力差が生じ、上記パイプから空気が排水中に吸収される。その結果、流水量が減じ、排水面の渦の発生は加振力を生じ、ポンプ振動の一因となるため防がねばならない。パイプから空気を吸い込むことにより、渦の発生しやすい低水位でも渦の発生が防げるため、安定して排水することが可能である。
【００３２】
更に、水位が十分高くなるとケーシング内外の圧力差は減じ、自然にパイプからの吸気は止まる。排水水位によるケーシング中の圧力変化を利用するため、外部からの制御を必要とせず、信頼性が高い。
又、大気側の開口端にバルブを設けることで、吸気量の制御及びこの機能の取消しも可能である。
【００３３】
本実施例の軸受装置を、図２及び図３により説明する。
図２は図１に示した排水ポンプの上部に設置された軸受装置を示す拡大図、図３は図２の摺動部を更に拡大した断面図である。スリ−ブ及び軸受の製造方法はまず、ＳＵＳ４０３でスリーブ基材８及び軸受基材１０を機械加工により形成した後、焼き入れ、焼き戻し熱処理を行い、ＳＵＳ４０３の硬度を高めておく。焼き戻し温度は約７００℃とし、後の溶射膜の改質時にＳＵＳ４０３が焼き戻し脆性を生じないようにした。熱処理後、軸受３及びスリーブ基材８の摺動部分にＷＣを主成分としＮｉＣｒを結合材とする溶射膜１１及び９を高速フレーム溶射で被覆した。溶射膜形成後、４００℃に２０時間加熱し保持する熱処理を施し、溶射膜の硬度を高めた。熱処理後、スリーブ及び軸受は内径、外径を所定寸法、面粗さに加工した。スリーブ２は回り止め４で主軸１に固定した。
【００３４】
軸受３は軸受用バックメタル６に取付け、軸受用緩衝材５を介し固定部材７で固定した。又、軸受３には摺動部への土砂の浸入を防止する浸入防止部材１２を取り付けた。
本実施例によれば、スリ−ブ基材としてＳＵＳ４０３を用いたため、主軸材料との熱膨張率が一致し熱応力の発生が防げるとともに、靭性が高いため表面に被覆した溶射膜を安定して保持できるスリ−ブとすることができる。
【００３５】
又、ＷＣ溶射膜に熱処理を施し硬度を増加させてあるため耐摩耗性が増し、軸受装置の寿命、信頼性が増す。
尚、本実施例では、スリ−ブ及び軸受に形成する溶射膜の材質としてＷＣを主成分としＮｉＣｒを結合材とする溶射膜について説明したが、ＷＣを主成分としＣｏを結合材とする溶射膜若しくはＣｒ３Ｃ２を主成分としＮｉＣｒを結合材とする溶射膜を用いても同様の効果が得られた。
本実施例の排水ポンプは、軸受装置が無潤滑条件下、即ち無給水状態においても安定した摺動性能を発揮し、給水後の摺動においては更に良好な摺動を行うことができる。
又、本実施例の排水ポンプは軸受装置の摺動部への土砂の浸入を防止する浸入防止部材を配置したが、排水中に混入した土砂が摺動部に浸入しても、摺動部には十分な耐摩耗性を備えているため安定した運転ができる。
更に、無潤滑状態においても良好な摺動性能が得られることから、無潤滑と潤滑状態を繰り返す使用状況、即ち先行待機運転においても信頼性の高い運転ができる。
【００３６】
図４は本発明の他の実施例を示すポンプ用軸受装置の縦断面図である。ＳＵＳ４０３のスリーブ基材８の摺動面にはＷＣを主成分としＣｏを結合材とする溶射膜９を被覆した。又、スリ−ブ２と摺動する軸受１３はＳｉＣとした。スリ−ブ２は、溶射膜形成後４００℃×２０時間の熱処理を施し、溶射膜の硬度を高めた。その他の構造は図１乃至図３で説明した実施例のものと同じである。
本実施例によれば、軸受部の材質が均質で高硬度の焼結セラミックからなるため軸受装置の寿命、信頼性が増す。
尚、本実施例では、スリ−ブに形成する溶射膜の材質としてＷＣを主成分としＮｉＣｒを結合材とする溶射膜について説明したが、ＷＣを主成分としＣｏを結合材とする溶射膜若しくはＣｒ３Ｃ２を主成分としＮｉＣｒを結合材とする溶射膜を用いても同様の効果が得られた。
【００３７】
図５は本発明の他の実施例を示すポンプ用軸受装置の縦断面図である。本実施例は、先行待機運転時に、軸受高さまで排水水位が達していない空転運転の場合に対応できる軸受構造である。なお、本図では全体構造を示すため、スリ−ブ２の詳細断面構造は図示していない。ＳＵＳ４０３材製のスリーブ２の摺動面にはＷＣを主成分としＮｉＣｒ結合材とする溶射膜を被覆し、溶射膜形成後４００℃×２０時間の熱処理を施し、溶射膜の硬度を高めた。又、スリ−ブ２と摺動する軸受１３はＳｉＣとし、バックメタル６に取付け、軸受用緩衝材５を介して、ケーシングから張り出した固定部材７’に固定した。さらに、固定部材７’にバッフルプレート１７を固定した。また、主軸１に回転水槽１８を固定した。回転水槽１８中には水が貯水され、軸受高さまで排水水位が達していない空転運転でも、軸受摺動部には潤滑水が存在する構造である。なお、本構造では、回転水槽１８中に土砂が溜りやすいため運転時に摺動部分に土砂が浸入する場合があるが、熱処理によって硬さを増したスリ−ブ摺動面の溶射膜１１の耐摩耗性は十分であり運転に支障はない。
【００３８】
図６，７は本発明の他の実施例を示すポンプ用軸受装置のスリ−ブ固定状況及び固定部の断面図である。本実施例では円周方向に４分割したスリ−ブを用いた。４分割したスリ−ブ２ａ，２ｂ，２ｃ及び２ｄはＳＵＳ４０３からなり軸受との摺動面にＣｒ３Ｃ２を主成分としＮｉＣｒを結合材とする溶射膜を形成した後、４００℃×２０時間の熱処理を施したものである。このスリ−ブ部品２ａ，２ｂ，２ｃ，２ｄはそれぞれ主軸１に軸方向の２ケ所でボルト１４により固定した。
その他の構造は図１乃至図３で説明した実施例のものと同じである。
【００３９】
軸受部の製造及び組立方法を以下説明する。ＳＵＳ４０３でスリーブ部品２ａ，２ｂ，２ｃ及び２ｄを作成し、上記軸受製造方法と同様の熱処理を施す。熱処理後、そのスリーブの摺動面にＷＣを主成分としＮｉＣｒ若しくはＣｏを結合材とする溶射膜ＷＣを高速フレーム溶射で形成する。溶射膜形成後、スリーブを４００℃に加熱し約２０時間保持する。熱処理後、主軸１に固定し所定の寸法に加工する。尚、主軸１への固定はボルトで十分であるが、接着剤を併用すれば、より信頼性は増す。
本実施例では、スリ−ブを分割構造としたため、溶射膜の形成作業が容易となるとともに分割したスリ−ブのそれぞれの重量が一体型のものに比べ約１／４となり、取扱が容易となる。
図８は本発明の他の実施例を示すポンプ用軸受装置の軸受の、一部断面を含む外観図である。本実施例は軸受の摺動部を分割した摺動部材１９を配列、形成する構造のものである。摺動部材１９は、ＳＵＳ４０３製の基材１０に、ＷＣを主成分としＮｉＣｒ若しくはＣｏを結合材とする溶射膜１１を高速フレーム溶射で形成したものであり、溶射膜形成後４００℃×２０時間の熱処理を施し、溶射膜の硬度を高めた。摺動部材１９は、緩衝材５を介してバックメタル６に取付け、軸受ケーシング２０に配置する。摺動部材１９は、固定治具２１によって軸受ケーシング２０に取り付けられているが、接着剤を併用すれば、より信頼性は増す。
本実施例では、軸受摺動部が分割構造となっているため、溶射膜の形成作業が容易となるとともに、各々の摺動部材１９が緩衝材５を介して固定されているため、片当たりの防止に効果的である。
【００４０】
従来、ＷＣを主成分とする超硬材料で製作されていたスリーブが、本発明では、ＳＵＳを用いることができ、大幅な重量低下ができる。さらに超硬材料と異なり、基材がＳＵＳの場合、ねじ穴加工が可能であるため、取扱が容易となる。特に、大径の場合スリーブの重量が増し、本発明が有効である。スリーブの重量低下に対する本発明の効果を図９にまとめる。図９は、スリーブの外径（以後Ｄと称する）とスリーブの重量（以後Ｗと称する）との相関を示す図である。スリーブ重量Ｗは、スリーブの外径Ｄによって変化するため、Ｗ／Ｄ２として、基準化する。本発明のスリーブではＷ／Ｄ２が大幅に低下し、０．０５以下を示す。
【００４１】
図１０に別の実施例として本発明の軸受装置を水車用軸受として用いた水車の断面図を示す。図１０において、２２は水車用主軸、２３はスリ−ブ回りどめ、２４はＷＣを主成分としＮｉＣｒを結合材として２７重量％加えた溶射膜（以下、ＷＣ−２７％ＮｉＣｒ溶射膜と称する）を被覆した後熱処理を施したＳＵＳ４０３製スリ−ブ、２５は熱処理済みＣｒ３Ｃ２を主成分としＮｉＣｒを結合材として２５％加えた溶射膜（以下、Ｃｒ３Ｃ２−２５％ＮｉＣｒ溶射膜と称する）を被覆した後熱処理を施したＳＵＳ４０３製軸受、２６はライナ−である。スリ−ブ及び軸受への溶射膜の被覆は高速フレーム溶射を用いて行った。熱処理済み溶射膜は、前記要素試験結果に示すように焼結体と同等の耐摩耗性を有する。且つ、大口径化が容易なため、水車に対してはコスト低減、軽量化に効果がある。
【００４２】
上記実施例で用いた軸受の耐摩耗特性を調べるため、熱処理による溶射膜の硬度変化を要素試験で調べた。加熱による溶射膜の硬度変化は、加熱温度２００℃〜６００℃、加熱時間１〜３０時間の範囲で調べた。溶射膜の硬度はマイクロビッカース硬度計で測定し、ビッカース硬度（以下、Ｈｖと称する）で示した。下地の影響を避けるため、硬度は溶射膜の断面で測定し、荷重は３００ｇ一定とした。
【００４３】
図１１は上記測定結果の一部であり、ＷＣ−２７％ＮｉＣｒ溶射膜を４００℃で加熱したときの硬度変化を示す。横軸は加熱時間、横軸は溶射膜の硬度である。溶射膜は高速フレーム溶射で形成し、膜厚は表面研磨後で約１００μｍ、下地はＳＵＳ４０３であり、溶射前に焼き入れ、約７００℃での焼き戻しの熱処理を施してある。尚、硬度の測定値にはバラツキがあるため、１０点の測定を行い、測定値中の最大、最小値をバラツキ範囲として線で示し、平均値を○で示した。
【００４４】
図１１に示すように溶射膜の硬度は時間と共に増加し１０〜３０時間で最高硬度に達し、その後バラツキはあるがほぼ一定となる。平均硬度の最高値はＨｖ１０１４（最大値Ｈｖ１０６５、最小値Ｈｖ８９０）である。同様の条件で測定したＷＣを主成分としＣｏをバインダーとして１２重量％加えた焼結体（以下ＷＣ−１２％Ｃｏ焼結体と称する）の硬度、平均値Ｈｖ１３１７（最大値Ｈｖ１４０４、最小値Ｈｖ１２３５）には達しないが、熱処理前の硬度の平均値Ｈｖ７２７（最大値Ｈｖ８６９、最小値Ｈｖ６０４）に比べ、平均値で約３４％の増加となり著しく改善されている。
【００４５】
図１２は測定結果の一部であり、図１１と同様ＷＣ−２７％ＮｉＣｒ溶射膜を５００℃で加熱したときの硬度変化を示す。尚、試料の形成方法、形状、硬度の測定方法は図１１と全て同様である。溶射膜の硬度は約１．５時間の加熱でほぼ最高硬さに達する。平均硬度の最高値はＨｖ１１１５（最大値Ｈｖ１１３９、最小値Ｈｖ１０８４）である。熱処理前の硬度に比べ平均値で約４７％の増加であり、ほぼＷＣ−１２％Ｃｏ焼結体に等しい。
【００４６】
図１３も測定結果の一部であり、ＷＣを主成分としＣｏを結合材として１２重量％加えた溶射膜（以下ＷＣ−１２％Ｃｏ溶射膜と称する）を４００℃で加熱したときの硬度変化を示す。ＷＣ−１２％Ｃｏ溶射膜も、上記の図１１及び１２の各試料と同様の高速フレーム溶射で形成し、膜厚は表面研磨後で約１００μｍ、下地は熱処理済みのＳＵＳ４０３である。試料の形状、硬度の測定方法も、上記図１１及び１２と同様である。ＷＣ−１２％Ｃｏ溶射膜の場合、硬度は時間と共に増加し１０〜２０時間で最高硬さに達し、２５時間でわずかに低下する。最高硬度は、平均値でＨｖ９４６（最大値Ｈｖ１１４９、最小値Ｈｖ７９２）である。熱処理前の硬度、平均値Ｈｖ５８４（最大値Ｈｖ６５２、最小値Ｈｖ４９０）に比べ、平均値で約６２％の増加である。又、５００℃で加熱した場合も、ほぼ、ＷＣ−２７％ＮｉＣｒ溶射膜の場合と同様の硬度変化を示し、約１時間の加熱により最高硬度に達した。
【００４７】
図１４も測定結果の一部であり、Ｃｒ３Ｃ２−２５％ＮｉＣｒ溶射膜を４００℃で加熱したときの硬度変化を示す。Ｃｒ３Ｃ２−２５％ＮｉＣｒ溶射膜も、上記の図１１、１２及び１３の測定に用いた各試料と同様の高速フレーム溶射で形成し、膜厚は表面研磨後で約１００μｍ、下地は熱処理済みのＳＵＳ４０３である。試料の形状、硬度の測定方法も、上記図１１、１２及び１３と同様である。Ｃｒ３Ｃ２−２５％ＮｉＣｒ溶射膜の場合、硬度は時間と共に徐々に増加する。加熱時間２５時間における平均硬度の最高値はＨｖ９５８（最大値Ｈｖ１０４３、最小値Ｈｖ９０５）である。熱処理前の硬度、平均値Ｈｖ７９１（最大値Ｈｖ８１７、最小値Ｈｖ７４４）に比べ、平均値で約２１％の増加であり、ＷＣ−２７％ＮｉＣｒ溶射膜、ＷＣ−１２％Ｃｏ溶射膜ほど顕著には増加しない。又、５００℃で加熱した場合も、４００℃加熱のように硬度は時間と共に徐々に増加するがその割合はより大きい。
【００４８】
以上、ＷＣ−２７％ＮｉＣｒ溶射膜、ＷＣ−１２％Ｃｏ溶射膜及びＣｒ３Ｃ２−２５％ＮｉＣｒ溶射膜は４００〜５００℃の加熱によって、その硬度が著しく改善され、ほぼＷＣ−１２％Ｃｏの焼結体の硬度に等しい値となる。４００℃〜５００℃の加熱によって、溶射膜中のＷＣ粒子又はＣｒ３Ｃ２粒子と結合材の結合力が増し、ほぼ焼結体に等しくなったと考えられる。
【００４９】
加熱温度２００℃〜６００℃、加熱時間１〜３０時間の範囲で調べた結果を以下にまとめる。加熱温度を３００℃以下とすると溶射膜の硬度は増加するものの、その増加率は極めて小さく工業的には利用が難しい。従って、熱処理温度としては、３００℃以上、望ましくは３５０℃以上が良い。しかし、ポンプに用いるＦｅ系材料は、熱膨張率が約１２〜１７×１０？６／℃であり、ＷＣ若しくはＣｒ３Ｃ２系溶射膜は熱膨張率が約５〜７×１０？６／℃であるため、加熱温度を高くし過ぎると溶射膜と下地との熱膨張率の差のため、熱応力が発生し被膜の接着力を低下させ、極端な場合、被膜の剥離を生じる。更に大気中で熱処理をする場合、溶射膜の酸化が生じ耐摩耗性を低下させる。従って、ＷＣ若しくはＣｒ３Ｃ２系の溶射膜を用いるかぎり、熱処理温度は５５０℃以下、望ましくは５００℃以下が良い。尚、溶射膜の加熱は酸化を防ぐためには不活性ガス中若しくは真空中での加熱が望ましい。
【００５０】
図１５に約２００μｍの厚さに溶射したＷＣ−２７％ＮｉＣｒ溶射膜を４００℃で加熱したのち溶射膜を約１００μｍの厚さまで表面研磨し、さらに加熱を行い、再び鏡面状態まで研磨したときの金属組織写真の模式図を示す。最終的な膜厚は、約９０μｍである。（Ａ）が未処理の溶射膜の写真、（Ｂ）が１０時間加熱した溶射膜の写真、（Ｃ）が２０時間加熱した溶射膜の写真であり、倍率は全て１００倍である。
【００５１】
エッチングをせずに観察しているため、ＷＣ粒子と結合材ＮｉＣｒとの差は観察できず、全て白色の下地として観察される。点在して黒く見える部分が空孔である。（Ａ）、（Ｂ）及び（Ｃ）を比較すると、熱処理時間とともに空孔数が減り、大きさも小さくなっている。試験に用いた試料はＳＵＳ４０３の板（２６ｍｍ×２６ｍｍ）の上に形成した溶射膜から切り分けたものであるため、空孔数の差は、溶射条件によって生じたのではなく、熱処理によって空孔が減少したものである。尚、ＷＣ−１２％Ｃｏ溶射膜又はＣｒ３ｃ２−２５％ＮｉＣｒ溶射膜でも同様の現象が認められた。
【００５２】
図１６にＷＣ−２７％ＮｉＣｒ溶射膜を４００℃で加熱したときの、加熱時間と表面に観察される２０μｍ以上の大きさの空孔の密度の関係を示す。尚、表面の空孔の観察方法は、上記図１５の方法と同様である。一方、ＷＣ−２７％ＮｉＣｒ溶射膜の組織を走査型電子顕微鏡で観察したところ、ＷＣ粒子、及びＮｉＣｒ結合材粒子の平均粒子径は約１０μｍ程度であり、最大でも２０μｍ以下である。従って、空孔も数μｍ以下であればＷＣ粒子の脱落には影響が少ない。しかし、２０μｍ以上になるとＷＣ粒子の脱落を生じ、溶射膜の強度を低下させる直接的原因となる。そこで、今回の空孔の測定では、粒子径２０μｍ以上のもののみを測定した。以後は、空孔と表記する場合、全て２０μｍ以上の空孔のこととする。
【００５３】
図１６に示すように、加熱温度４００℃の場合、１５時間以上加熱すると空孔の数は急激に減少する。この空孔密度の変化は図７に示した硬度の変化と一致する。即ち、加熱による溶射膜の硬度の変化は、溶射膜中の空孔密度に起因するものと考えられる。
【００５４】
図１２と１６に示した加熱時間による硬度変化と空孔密度変化とから、空孔密度と硬度との関係を求め、図１７に示す。空孔密度が３０個／ｍｍ２以下になると硬度が増加し始め、１５個／ｍｍ２以下でポンプ軸受部に望ましい硬度となる。従って、ポンプ軸受部に配する溶射膜としては、表面に存在する２０μｍ以上の大きさの空孔密度が、１５個／ｍｍ２以下、望ましくは１０個／ｍｍ２以下である。尚、ＷＣ−１２％Ｃｏ溶射膜、Ｃｒ３Ｃ２−２５％ＮｉＣｒ溶射膜でも同様の現象が認められた。
【００５５】
熱処理済み溶射膜を用いた軸受及びスリーブの、土砂水に対する耐摩耗性を調べるため以下の要素試験を行った。その方法と結果の一部を図１８、１９を用いて説明する。図１８は試験片の形状と摺動方法を示す。（Ａ）に示す回転側試験片１５と（Ｂ）に示す固定側試験片１６を土砂水を想定した、珪砂を含んだ水中に浸漬し、（Ｃ）に示すように回転側試験片を回転させ所定の面圧を負荷して摺動させる。所定時間の摺動後、両試料の摩耗量を測定した。摩耗量の測定は、回転側試験片１５は試験前後の試験片厚さ、固定側試験片１６では試験前後の表面形状を表面粗さ計で測定して求めた。検討した条件範囲は、面圧が１〜１０ｋｇ／ｃｍ２、周速が約０．５〜５ｍ／ｓ、珪砂濃度が０．１〜１０ｗｔ％である。尚、珪砂自体が摩耗される影響を減らすため３．６ｋｍ摺動ごとに土砂水をかえ、更に両試験片の間に珪砂が噛み込みやすいように土砂水を替えるたび両試験片の間に珪砂をはさみ込み摺動試験を繰り返した。
【００５６】
図１９は、熱処理済み溶射膜の耐摩耗性を上記試験によって調べた結果の一部である。横軸は摺動距離、縦軸は回転側試験片の平均摩耗量である。固定側試験片はα−ＳｉＣ、回転側試験片はＷＣ−２７％ＮｉＣｒ溶射膜であり、膜厚が約１００μｍ、下地は焼入れ、焼戻し熱処理を施したＳＵＳ４０３である。溶射膜の熱処理条件は、図１２の結果を参考にし４００℃×２０時間とした。比較材料として、ＷＣ−１２％Ｃｏ焼結体と未処理のＷＣ−２７％ＮｉＣｒ溶射膜を回転側試験片として同様の条件で試験した。その他の試験条件は面圧が２ｋｇ／ｃｍ２、周速が０．５ｍ／ｓ、珪砂濃度が９ｗｔ％である。
【００５７】
図１９において、−▲−で示す（１）のラインが本発明の軸受部材である熱処理済ＷＣ−２７％ＮｉＣｒ溶射膜の摩耗量変化、−○−で示す（２）のラインが比較材料である従来の軸受部材であるＷＣ−１２％Ｃｏ焼結体の摩耗量変化、−△−で示す（３）のラインが比較材料である未熱処理のＷＣ−２７％ＮｉＣｒ溶射膜の摩耗量変化である。未熱処理のＷＣ−２７％ＮｉＣｒ溶射膜の摩耗率は、ＷＣ−１２％Ｃｏ焼結体に比べて約３倍の値を示すのに対し、熱処理済ＷＣ−２７％ＮｉＣｒ溶射膜はほぼ同等の摩耗率を示す。即ち、４００℃×２０時間の熱処理によって、ＷＣ−２７％ＮｉＣｒ溶射膜の土砂水に対する摩耗量は約１／３に減少した。この摩耗量の低下は、図１２に示した溶射膜の熱処理による硬度の増加に起因すると考えられる。図２１で示した溶射膜の硬度と摩耗率との関係からも、上記熱処理済み溶射膜の耐摩耗性は妥当な値である。又、図１９には示さないが、４００℃×２０時間の熱処理を施したＷＣ−２７％ＮｉＣｒ溶射膜とＳｉ３Ｎ４との組み合わせも良好な耐摩耗性を示す。固定側試験片に用いたＳｉ３Ｎ４はＳｉＣ以上に優れた耐摩耗性を示した。
【００５８】
同様の試験によると、ＷＣ−１２％Ｃｏ溶射膜も同様の熱処理によって向上の効果を示す。しかしＷＣ−１２％Ｃｏ溶射膜の場合、ＷＣ−２７％ＮｉＣｒ溶射膜ほど硬度が増さないために、ＷＣ−１２％Ｃｏ焼結体や熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜の耐摩耗性に及ばない。更に、結合材のＣｏがＮｉＣｒに比べ耐食性に劣るため、腐食による摩耗が生じる可能性がある。本条件の熱処理済ＷＣ−１２％Ｃｏ溶射膜では、表面の空孔密度が減るため、Ｃｏ結合材でも腐食摩耗に対する耐摩耗性が向上する。しかし、それでも海水のような塩分を含む排水に対する耐食性は十分でない。従って、使用環境によってはＷＣ−１２％Ｃｏ溶射膜を用いた軸受は用いることができない。
【００５９】
同様の試験によると、Ｃｒ３Ｃ２−２５％ＮｉＣｒ溶射膜も耐摩耗性が向上する。しかし、ＷＣ−２７％ＮｉＣｒ溶射膜、ＷＣ−１２％Ｃｏ溶射膜ほど顕著な耐摩耗性の向上はない。これは、Ｃｒ３Ｃ２−２５％ＮｉＣｒ溶射膜自体の硬度が本質的にＷＣ−２７％ＮｉＣｒ溶射膜、ＷＣ−１２％Ｃｏ溶射膜ほど高くないために、熱処理を施しても効果が小さいためである。
【００６０】
上記図１９の結果と、固定側と回転側の両試験片に熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜を用いた場合及び回転側試験片に熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜、固定側試験片に熱処理済みＣｒ３Ｃ２−２５％ＮｉＣｒ溶射膜を用いた場合の結果を合わせて、各々の摩耗率を図２０にまとめて示す。
【００６１】
図２０は固定側と回転側両試験片の試験時間６０時間における摩耗率を表示したものである。試験条件は図１９の試験と同様である。尚、縦軸の相対摩耗率とは、ＷＣ−１２％Ｃｏ焼結体とα−ＳｉＣとの組合せである（Ａ）の、回転側、固定側各々の試験片の摩耗率を基準１．０とし、各試料の摩耗率を相対値として示した値である。又、棒グラフにおいて、斜線の入っている側が回転側試験片の摩耗率であり、無い側が固定側試験片の摩耗率である。
【００６２】
組合せ（Ａ）は、ＷＣ−１２％Ｃｏ焼結体とα−ＳｉＣとの組合せであり、図１９の曲線（２）の結果である。（Ｂ）は、図１９の曲線（３）に示した未熱処理のＷＣ−２７％ＮｉＣｒ溶射膜とα−ＳｉＣとの組合せ結果である。（Ｃ）は、図１９の曲線（１）に示した本発明の軸受部材である熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜とα−ＳｉＣとの組合せ結果である。（Ｄ）は、本発明の軸受部材である熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜と熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜との組合せ結果、（Ｅ）は熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜と熱処理済みＣｒ３Ｃ２−２５％ＮｉＣｒ溶射膜との組合せ結果である。尚、溶射膜の熱処理条件は、全て４００℃×２０時間である。
【００６３】
図１９で説明したように、（Ｃ）の組み合わせは、固定側、回転側の両試験片とも、組合せ（Ａ）即ちＷＣ−１２％Ｃｏ焼結体とα−ＳｉＣとの組合せとほぼ同等の耐摩耗性を示す。 固定側と回転側の両試験片に熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜を用いた（Ｄ）の組合わせにおいても、回転側、固定側試験片はＷＣ−１２％Ｃｏ焼結体とほぼ同等の耐摩耗性を示した。
【００６４】
固定側試験片の熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜は、α−ＳｉＣ以上の優れた耐摩耗性を示した。α−ＳｉＣの硬度は平均値Ｈｖ２７０４（最大値Ｈｖ２８７４、最小値Ｈｖ２５９１）であり、熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜よりもはるかに高い。それにもかかわらずＷＣ−２７％ＮｉＣｒ溶射膜がα−ＳｉＣよりも優れた耐摩耗性を示した原因は、両者の延性、すなわち破壊靱性の差によると考えられる。α−ＳｉＣの破壊靱性は約３．９（ＭＮ／ｍ・√ｍ）であり、熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜の約１３（ＭＮ／ｍ・√ｍ）に及ばない。熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜の優れた破壊靱性が、硬度以上に耐摩耗性に影響し、上記の優れた耐摩耗性を示したものと考えられる。尚、上記破壊靱性は、ビッカース圧痕法によって測定したものである。
【００６５】
回転側試験片に熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜、固定側試験片に熱処理済みＣｒ３Ｃ２−２５％ＮｉＣｒ溶射膜を用いた（Ｅ）の組み合わせは、回転側試験片の相対摩耗率は（Ｃ）、（Ｄ）の組み合わせとほぼ同等の結果を示した。
【００６６】
しかし、固定側試験片の熱処理済みＣｒ３Ｃ２−２５％ＮｉＣｒ溶射膜の摩耗率は、α−ＳＣｒ３Ｃ２ｉＣや熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜より高い値を示した。これは、図１４に示したように、熱処理を施してもＣｒ３Ｃ２−２５％ＮｉＣｒ溶射膜の硬度が大幅に増加しないためと考えられる。しかし、排水の温度が高い条件では、Ｃｒ３Ｃ２−２５％ＮｉＣｒ溶射膜はＷＣ−２７％ＮｉＣｒ溶射膜と同等、或いはそれ以上の耐摩耗性を示した。これは、Ｃｒ３Ｃ２−２５％ＮｉＣｒ溶射膜が高温での硬度低下が少ないためと考えられる。従って、使用環境によっては、熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜と熱処理済みＣｒ
３Ｃ２−２５％ＮｉＣｒ溶射膜の組み合わせが良好となる。
【００６７】
以上の結果を以下にまとめる。
熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜をスリーブに用い、ＳｉＣ若しくはＳｉ３Ｎ４軸受と組み合わせた場合、良好な耐摩耗性、摺動特性が得られる。この場合、ＳｉＣやＳｉ３Ｎ４は、圧縮応力を加えると強度が増すため、焼きばめによりバックメタルで支持する構造の軸受側に用いる方が良い。熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜をスリーブ、軸受の両方に用いた場合、全般的に優れた耐摩耗性、摺動特性を示す。この場合、Ｃｏを結合材とするＷＣ溶射膜でも同様に優れた耐摩耗性が得られるが、排水に塩分が含まれる場合、腐食のため使用は難しい。熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜と熱処理済みＣｒ３Ｃ２−２５％ＮｉＣｒ溶射膜をスリーブ及び軸受に用いた場合、熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜同しの組み合わせほど優れた耐摩耗性は得られない。しかし排水温度の高い場合は、より優れた特性を示す。この場合、スリーブ、軸受のどちらにＷＣ−２７％ＮｉＣｒ溶射膜を配しても良く、特性に対して影響はない。
【００６８】
従って、本発明の軸受構造はスリーブ及び軸受の摺動面の耐摩耗性が軸受にＷＣ−１２％Ｃｏ焼結体を用いたものとほぼ同等であり、且つスリーブ及び軸受の部品重量が少ないため組立て性が優れる。又、スリーブ及び軸受の靱性が高いため衝撃による破壊の発生がなく信頼性が高くなる。このため、本発明の軸受構造を用いた回転機械、例えばポンプ等は信頼性が高くなる。
【００６９】
上記各実施例では、溶射膜形成法としては高速フレーム溶射を用いたが、爆発溶射、減圧プラズマ溶射、レーザ溶射、プラズマ溶射であってもよく、その製法に制限されるものではない。尚、熱処理前の硬度は高い方が望ましく、高硬度の溶射膜が形成できる高速フレーム溶射、爆発溶射が望ましい。
【００７０】
又、上記各実施例ではスリ−ブ基材及び軸受基材の材料としてＳＵＳ４０３を用いたが、水中で使用できる材料であればよい。尚、ＷＣ又はＣｒ３Ｃ２を主成分とする溶射膜の熱膨張率を考慮すれば、熱膨張率の大きいＳＵＳ３０４よりもＳＵＳ４０３の方が望ましい。また、加熱処理によるＳＵＳの耐食性低下を考慮すれば、炭素含有率の少ないＳＵＳ３０４Ｌ、もしくはＳＵＳ３１６Ｌが望ましい。
【００７１】
又、上記各実施例では結合材としてＮｉＣｒとＣｏを用い、その含有率は１２ｗｔ％，２５ｗｔ％，２７ｗｔ％としたが、溶射膜として特性を満足するならば、その含有率を制限するものではない。
【００７２】
【発明の効果】
本発明によれば、ＷＣ若しくはＣｒ３Ｃ２を主成分とする溶射膜を所定条件で加熱することにより、ＷＣ粒子、Ｃｒ３Ｃ２粒子と結合材との結合力が増し、その結果溶射膜の空孔が減少して硬度が平均値で約５０〜６０％増加し、土砂水に対する耐摩耗性が熱処理前の約３倍に向上する。この特性はＷＣ−１２％Ｃｏ等のセラミック焼結体とほぼ同等であり、ＷＣ−１２％Ｃｏ焼結体製スリーブ、軸受に替わり、金属表面に溶射膜を被覆したスリーブ、軸受を用いることができる。その結果、ＷＣ、ＳｉＣ、Ｓｉ３Ｎ４の焼結体では製作できなかった大口径の軸受、スリーブが製作できる。
【００７３】
更に、口径にかかわらず、軸受、スリーブの重量が低減するために、組立て性が大幅に良くなる。又、靱性の低いＷＣ、ＳｉＣ、Ｓｉ３Ｎ４の焼結体に替わり、ステンレスを基材として使用できるため、軸受、スリーブの信頼性が増す。従って、この軸受装置を用いるポンプの信頼性が増す。
【図面の簡単な説明】
【図１】本発明の実施例の排水ポンプ構造を示す断面図である。
【図２】本発明の実施例の軸受装置を示す一部断面斜視図である。
【図３】本発明の他の実施例の軸受装置の縦断面図である。
【図４】本発明の他の実施例の軸受装置の縦断面図である。
【図５】本発明の他の実施例の軸受装置の縦断面図である。
【図６】本発明の他の実施例のスリ−ブ構造を示す斜視図である。
【図７】図５のＡ−Ａ断面図である。
【図８】本発明の他の実施例の軸受を示す一部断面斜視図である。
【図９】本発明の他の実施例のスリ−ブの外径Ｄと重量Ｗ／（外径Ｄ）２との相関を示す関係図である。
【図１０】本発明の他の実施例の水車構造を示す断面図である。
【図１１】ＷＣ−２７％ＮｉＣｒ溶射膜の４００℃加熱時の硬度変化を示す図である。
【図１２】ＷＣ−２７％ＮｉＣｒ溶射膜の５００℃加熱時の硬度変化を示す図である。
【図１３】ＷＣ−１２％Ｃｏ溶射膜の４００℃加熱時の硬度変化を示す図である。
【図１４】Ｃｒ３Ｃ２−２５％ＮｉＣｒ溶射膜の４００℃加熱時の硬度変化を示す図である。
【図１５】ＷＣ−２７％ＮｉＣｒ溶射膜の４００℃加熱時の溶射膜の変化状況を示す金属組織写真の模式図である。
【図１６】ＷＣ−２７％ＮｉＣｒ溶射膜の４００℃加熱時の溶射膜表面空孔密度と加熱時間との関係図である。
【図１７】ＷＣ−２７％ＮｉＣｒ溶射膜の４００℃加熱時の溶射膜表面空孔密度と硬度との関係図である。
【図１８】摩耗試験片形状と摺動方法を示す図である。
【図１９】摩耗試験によるＷＣ−１２％Ｃｏ焼結体、未熱処理ＷＣ−２７％ＮｉＣｒ溶射膜と熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜の摺動距離と摩耗量との関係図である。
【図２０】熱処理済みＷＣ−２７％ＮｉＣｒ溶射膜、熱処理済みＣｒ３Ｃ２−２５％ＮｉＣｒ溶射膜を含む各種材料組合せの相対摩耗率比較図である。
【図２１】従来の各溶射膜の硬度と土砂水に対するＷＣ−１２％Ｃｏ焼結体を基準とした相対摩耗率を示す図である。
【符号の説明】
１…主軸、２…スリーブ、３…軸受、４…スリーブの回り止め、５…軸受用緩衝材、６…軸受用バックメタル、７，７’…固定部材、８…スリーブ基材、９，１１…溶射膜、１０…軸受基材、１３…セラミック製軸受、１４…分割スリーブ固定ボルト、１５，１６…摩耗試験片、１７…バッフルプレート、１８…回転水槽、１９…摺動部材、２０…軸受ケーシング、２１…固定治具、２２…水車用主軸、２３…スリーブ回り止め、２６…ライナー。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drainage pump, and in particular, a bearing device excellent in wear resistance, high reliability, and assemblability suitable for a pump that operates without supplying clean water to the bearing portion, and a drainage pump using the bearing device, The present invention relates to a method for manufacturing the bearing portion.
[0002]
[Prior art]
With the rapid urbanization in recent years, most of the rainwater flows into the drainage ditch, so the drainage cannot catch up and urban floods that overflow the road tend to increase. In order to cope with this, a drainage pump station equipped with a drainage pump system is provided, but there is a problem that the operation and maintenance costs increase with the increase of the drainage pump station, and a drainage pump system by automatic operation is being studied. The problems of this drainage pump system are high performance and high reliability. Currently, as technologies corresponding to these, non-water supply operation technology, large capacity and advance standby operation of the pump are being studied.
[0003]
The non-water supply operation technique is an operation without supplying clean water between the bearing and the sleeve. Since there is no clean water supply device, there is no malfunction due to failure of the clean water supply device, clean water service sensor, etc., and the reliability is high. In order to enable non-water supply operation technology, a bearing device that does not wear even when soil contained in drainage enters is necessary.
[0004]
A conventional bearing device for a non-water supply pump uses a combination of a sleeve (sintered body) made of tungsten carbide (hereinafter referred to as WC) and a ceramic bearing (sintered body), which has excellent wear resistance and corrosion resistance. Has been. The combined structure of the WC sleeve and the ceramic bearing is disclosed in Japanese Patent Application Laid-Open Nos. 60-81517 and 60-88215.
[0005]
On the other hand, increasing the capacity of the pump inevitably requires an increase in the diameter of the bearing. However, if the conventional bearing device is a combination of a WC sleeve and a ceramic bearing, a large-diameter sintered body sleeve and sintered body bearing are required. However, there has been a problem that the sintering technique cannot be adequately handled, the weight of the parts is increased, and the assembling work becomes difficult. Therefore, hard film coating techniques for coating a film having the same hardness as ceramics have been widely studied. As an example of using a thermal spray film as a hard film, a non-water supply and drainage pump using a combination of a sleeve coated with a WC thermal spray film and a ceramic bearing is “Tribologist,” Vol. 36, No. 2, page 144. To page 147.
[0006]
In many cases, a sprayed coating is used as a hard coating for the drainage pump bearing. However, since the sprayed film is inferior in hardness and strength to a sintered body having the same composition, methods for increasing the hardness and strength of the sprayed film have been studied. For example, there is disclosed a technique for increasing the adhesion and strength of a sprayed film by spraying a plasma sprayed film made of 50% Cr-50% Ni and then holding it at a temperature of about 700 ° C. to 800 ° C. for about 1 to 100 hours. This is disclosed in Japanese Patent Publication No. 57-2872. Also, a method of increasing the strength of the sprayed film by forming a 20-80% NiCr sprayed film mainly on nickel-phosphorus (NiP) on an Fe-based material and performing a heat treatment at a temperature of 600 ° C-1000 ° C. Is disclosed in JP-A-60-149762.
[0007]
The pre-standby operation is an idling operation at a water level lower than the drainable water level before the start of drainage, and full power operation is possible at the time when the drainable water level is reached, and a rapid increase in drainage can be handled quickly. However, in order to perform the preliminary standby operation, since the bearing performs an idling operation in which the sliding portion does not include drainage in a short time, the friction coefficient between the bearing and the sleeve is extremely low, and it is required that the bearing is not damaged even by dry sliding. It is done.
[0008]
Bearings that satisfy both the standby standby operation for a long idling operation and the non-water supply operation have not been developed yet, and a method for supplying water from the outside to the bearing sliding portion during the idling operation has been studied. It is disclosed in the gazette.
[0009]
[Problems to be solved by the invention]
In order to drain water containing earth and sand, the wear resistance of the bearing is indispensable. In the case of a non-water supply bearing, since there is no supply of clean water for protecting the bearing and the sleeve, the wear resistance against the slurry is particularly important. Most of the earth and sand particles contained in the earth and sand water are feldspar and quartz, and the maximum hardness is about Vickers hardness (hereinafter referred to as Hv) 1000 (quartz). Therefore, the hardness required for the bearing and the sleeve is Hv1000 or more.
[0010]
WC, SiC, silicon nitride (hereinafter referred to as Si 3 N 4 The hardness of WC is about 1400 for Hv, about 2800 for SiC, 3 N 4 Is about 1600 and Hv1000 or more, which is sufficient in terms of hardness and excellent in wear resistance. However, considering the sintering technology, assembly workability, and manufacturing cost, the entire sleeve and bearing are made of WC, SiC or Si. 3 N 4 There is a limit to the size of the sintered body. Therefore, it has been studied to use a hard coating instead of the sintered body as described above. Considering the amount of wear, the film thickness needs to be several hundreds of μm or more, so the method for producing the hard coating is limited. As a hard coating for drainage pump bearings, a relatively thick film can be obtained and WC and Cr can be obtained with high hardness. 3 C 2 Thermally sprayed films having a film thickness of about 100 to 200 μm mainly composed of bismuth are widely used. However, WC, Cr formed by spraying method 3 C 2 Although the thermal spray film which has as a main component depends on a material, a formation method, and conditions, generally hardness is low compared with a sintered compact and is about Hv600-1000.
[0011]
The relationship between the hardness of various conventional sprayed coatings and the abrasion resistance against soil water will be described with reference to FIG. FIG. 21 shows the wear rate measured by the element test described in the examples. As the various sprayed films, various sprayed films formed on a stainless steel (hereinafter referred to as SUS) plate were used for the rotation side test piece, and α-SiC was used for the fixed side test piece. Other test conditions include a surface pressure of 2 kg / cm 2 The peripheral speed is 0.5 m / s, and the concentration of silica sand contained in the earth and sand water is 9 wt%. The details of the test piece shape and the sliding method are the same as the test conditions of FIG. 19 shown in the embodiment.
[0012]
The horizontal axis in FIG. 21 is the cross-section Vickers hardness of the sprayed film, and the vertical axis is the relative wear rate normalized based on the wear rate of the WC-12% Co sintered body. Thermal spray film 1, thermal spray film 2, and thermal spray film 3 are WC or Cr made by high-speed flame spraying method and explosion spraying method. 3 C 2 It is a conventional sprayed film mainly composed of As shown in FIG. 21, the abrasion resistance against earth and sand water strongly depends on the hardness of the sprayed film, and as described above, the Vickers hardness is preferably 1000 or more. From the results shown in FIG. 21, it can be seen that the current sprayed coating does not provide sufficient hardness and wear resistance against soil water.
[0013]
In general, thermal spraying means WC particles, Cr 3 C 2 Rather than just heating and spraying hard particles such as particles, metal particles such as Ni, Cr, and Co are mixed and heated and sprayed simultaneously as a binder, and WC particles and Cr are melted by the dissolved metal particles. 3 C 2 The particles are connected to form a film. The hardness of the sprayed film is lower than that of the sintered body because the WC particles and Cr in the sprayed film 3 C 2 WC particles, Cr, not the particle hardness is low 3 C 2 Due to defects such as voids in the binder that connects the particles, or the binder and WC particles, Cr 3 C 2 This is because the bonding force with the particles is insufficient.
[0014]
WC particles, Cr 3 C 2 Various thermal spraying improvements have been made to increase the bond strength between the particles. For example, high-speed flame spraying using combustion energy of combustible gas with increased spray particle speed, and explosive spraying using explosion of combustible gas have been developed, and particles during spraying are more than conventional plasma sprayed films. It is possible to increase the speed and form a sprayed film with higher hardness. However, it is clear from the elemental test shown in FIG. 18 that the abrasion resistance against the earth and sand water is not sufficient even with the sprayed film by each of these spraying methods, and the hardness is low.
[0015]
The ceramic bearings disclosed in the above prior art, Japanese Patent Application Laid-Open Nos. 60-81517 and 60-88215 have difficulty in sintering technology and reliability due to the large diameter of the bearing and sleeve. No consideration has been given to the decrease in assembly performance due to a decrease or an increase in weight.
[0016]
For the conventional technology, a non-feed water drain pump ("Tribologist", Vol. 36, No. 2) using a combination of a WC sprayed film and a ceramic bearing (sintered body), WC or Cr 3 C 2 No study has been made on the hardness, wear resistance, and reliability of the thermal sprayed film mainly composed of.
[0017]
In the method for reforming a sprayed film disclosed in the above prior art, Japanese Patent Application Laid-Open No. 57-2872 and Japanese Patent Application Laid-Open No. 60-149762, a material having a thermal expansion coefficient close to that of an Fe-based material that is a main base material, Alternatively, it is limited to materials that do not change in quality by heating, and WC or Cr that can obtain high hardness 3 C 2 In the thermal sprayed film containing as a main component, since the heating temperature is high, the thermal expansion difference becomes large. As a result, the coating breaks and it is difficult to use it as it is. Furthermore, in equipment used underwater such as a pump, the main material is limited to SUS. Therefore, when the modification of the sprayed film by heating shown in the above prior art is applied, the heating temperature becomes higher than the annealing temperature of the underlying SUS or the sensitization temperature against intergranular corrosion, and the hardness and corrosion resistance of the underlying layer are lowered. As a result, there is a problem that reliability is lowered.
[0018]
That is, in the prior art, no study has been made on the modification of the sprayed film mainly composed of WC having a large difference in thermal expansion coefficient from the Fe-based material. Further, no consideration is given to changes in hardness and corrosion resistance of the base material.
In the method of supplying water to the bearing sliding portion from the outside, which is disclosed in the above-mentioned prior art, Japanese Patent Laid-Open No. 55-90718, the drainage station stops due to malfunction of the external water supply device, and the drainage stops in an emergency. There was a possibility that there was a problem in reliability.
[0019]
The present invention has been made in view of the above prior art, and is applicable to a drainage pump system. The bearing device is excellent in wear resistance and assembly, and has high reliability, and a drainage pump and a bearing device using the bearing device. It aims at providing the manufacturing method of.
[0020]
[Means for Solving the Problems]
In order to improve the wear resistance of the sprayed coating coated on the sliding surface of the bearing device which is the subject of the present invention, WC or Cr 3 C 2 After thermal spraying of the main component, the adhesive strength of the thermal sprayed film does not decrease due to thermal stress, the thermal sprayed film does not deteriorate, the hardness of the underlying SUS does not extremely decrease, and further sensitization to intergranular corrosion It is achieved by heating at a temperature condition that does not occur.
[0021]
An object of the present invention is, for example, to coat the following sprayed coating on one or both sliding surfaces of a bearing and a sleeve used in a bearing device including a bearing and a sleeve sliding with the bearing. It is solved by doing. The thermal spray coating to be coated has WC as a main component and one or more of Ni, Cr or Co as a binder, or Cr 3 C 2 Is coated with a sprayed film containing Ni and Cr as a main component, and the density of pores having a size of 20 μm or more formed on the surface of the sprayed film is 15 / mm. 2 It is as follows.
[0022]
Furthermore, the coated thermal sprayed film is heated at a temperature of 300 ° C. or higher and 550 ° C. or lower for 1 hour or longer after coating, the coating hardness is improved to 1000 or more in terms of Vickers hardness, and exhibits sufficient abrasion resistance against earth and sand water. To do.
[0023]
The material of the bearing and sleeve for coating the sprayed film may be Fe-based metal, but stainless steel is preferable.
[0024]
When either the bearing or the sleeve is coated with the above-mentioned sprayed film, the other has SiC or Si on the sliding surface. 3 N 4 Or the whole is SiC or Si 3 N 4 It may be composed of Further, the sleeve or the bearing may be divided into two or more.
[0025]
As the bearing member, a sprayed film containing Cr as a main component in a sliding portion of a stainless steel bearing member processed into a predetermined shape and containing one or more of Ni, Cr, and CO as a binder or Cr 3 C 2 After forming a sprayed film containing Ni and Cr as a main component in the binder, heating is performed at a temperature of 300 ° C. or higher and 550 ° C. or lower for 1 hour or longer, and then finished to a predetermined size.
[0026]
Generally, WC, Cr 3 C 2 It has been said that when a sprayed film containing as a main component is heated, the strain for increasing the hardness of the coating disappears and the hardness decreases. In addition, a WC or Cr having a low thermal expansion coefficient on a Fe-based material (SUS403 in the embodiment of the present invention) as a base material. 3 C 2 When coating a thermal sprayed film mainly composed of, due to the difference in thermal expansion coefficient between the two, when heated after film formation, the coating adhesive force decreases due to thermal stress, and further WC particles or Cr by heating 3 C 2 It has been thought that the oxidation of particles occurs and the properties of the sprayed film are degraded. For this reason, WC or Cr 3 C 2 Heating after thermal spraying of a thermal sprayed film containing as a main component has not been considered desirable. However, if the heating conditions are selected, the hardness can be increased without adversely affecting the sprayed film. For example, the thermal spray coating hardness is increased by heating at a temperature of 300 ° C. or more and 550 ° C. or less for 1 hour or more, and exhibits sufficient abrasion resistance against earth and sand water. Details of the mechanism and examination results will be described in the examples.
[0027]
If there are vacancies in the sprayed film, the strength of the sprayed film itself decreases, and WC particles or Cr 3 C 2 Since the bonding force between particles also decreases, WC particles or Cr during sliding 3 C 2 Particles fall off and cause a reduction in wear resistance. However, when heated at a high temperature after film formation to eliminate vacancies, as described above, binder particles, WC particles or Cr 3 C 2 Oxidation of the particles, a decrease in the adhesion of the sprayed film, and a decrease in the hardness and corrosion resistance of the lower material occur, resulting in a decrease in reliability. However, according to the present invention, WC or Cr 3 C 2 Even if the temperature and heating time are appropriately selected, the number of pores in the sprayed film will be reduced, even at low temperatures where oxidation of the sprayed film, reduction in film adhesion due to thermal stress, and lower hardness and corrosion resistance of other materials will not occur. In addition, it became clear that the pore size was reduced and the hardness of the sprayed coating was increased.
[0028]
In particular, when heated under these conditions, binder particles, WC particles or Cr 3 C 2 It has been found that large pores of 20 μm or more exceeding the maximum particle diameter of the particles are reduced. Large pores of 20 μm or more are WC particles or Cr 3 C 2 This is a direct cause of particle dropout. Therefore, the reduction of large pores of 20 μm or more acts to improve the strength of the sprayed film. Further, when the large pores of 20 μm or more are reduced, ductility is imparted to the coating, resistance to impact is increased, coating breakage and peeling are reduced, and coating reliability is increased.
Moreover, since a void | hole becomes a corrosion generation | occurrence | production point of a sprayed film, between WC particles becomes dense by reducing a void | hole, the corrosion which arises between particle | grains is suppressed, and the corrosion resistance with respect to waste_water | drain increases.
In addition, since the bearing device that can be operated in a non-lubricated state is used even if the drainage pump of the present invention is used for the preliminary standby operation, it has sufficient reliability.
[0029]
Further, by making the sleeve or the bearing into a divided structure, the manufacture becomes easy, and the effect is particularly great in a large diameter one.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a longitudinal sectional view showing a structure of a drainage pump according to an embodiment of the present invention. Usually, the drainage pump is provided with bearings at two locations near the impeller and at the top. The bearing device of this embodiment can be applied to both bearings. In FIG. 1, 1 is a main shaft, 2 is a sleeve attached to the main shaft, and 3 is a bearing. In this embodiment, SUS403 is used for the main shaft 1, the sleeve 2 and the bearing 3.
[0031]
The pump is provided with a pipe at the drainage suction port of the casing, one end is supported by the rib of the casing, and the other end is supported by the floor of the drainage station and opens to the atmosphere.
In this pump, when the drainage water level is low, a pressure difference is generated between the pump internal pressure and the atmosphere, and air is absorbed into the drainage from the pipe. As a result, the amount of flowing water is reduced, and the generation of vortices on the drainage surface must be prevented because it generates an excitation force and contributes to pump vibration. By sucking air from the pipe, vortices can be prevented from being generated even at low water levels where vortices are likely to occur, so that stable drainage is possible.
[0032]
Furthermore, when the water level becomes sufficiently high, the pressure difference between the inside and outside of the casing decreases, and intake from the pipe stops naturally. Since the pressure change in the casing due to the drainage water level is used, there is no need for external control and the reliability is high.
Further, by providing a valve at the open end on the atmosphere side, it is possible to control the intake air amount and cancel this function.
[0033]
The bearing device of the present embodiment will be described with reference to FIGS.
FIG. 2 is an enlarged view showing a bearing device installed at the upper part of the drainage pump shown in FIG. 1, and FIG. 3 is a sectional view further enlarging the sliding portion of FIG. In the manufacturing method of the sleeve and the bearing, first, the sleeve base material 8 and the bearing base material 10 are formed by machining in SUS403, and then quenching and tempering heat treatment are performed to increase the hardness of the SUS403. The tempering temperature was set to about 700 ° C. so that SUS403 did not cause temper brittleness when the sprayed film was modified later. After the heat treatment, the sprayed films 11 and 9 having WC as a main component and NiCr as a binder were coated on the sliding portions of the bearing 3 and the sleeve base 8 by high-speed flame spraying. After forming the sprayed film, a heat treatment was performed by heating to 400 ° C. for 20 hours to increase the hardness of the sprayed film. After the heat treatment, the sleeve and the bearing were processed to have an inner diameter and an outer diameter with predetermined dimensions and surface roughness. The sleeve 2 was fixed to the main shaft 1 with a detent 4.
[0034]
The bearing 3 was attached to a bearing back metal 6 and fixed with a fixing member 7 via a bearing cushioning material 5. Further, the bearing 3 is provided with an intrusion prevention member 12 for preventing infiltration of earth and sand into the sliding portion.
According to this example, since SUS403 was used as the sleeve base material, the thermal expansion coefficient coincided with that of the main shaft material, so that the generation of thermal stress was prevented, and since the toughness was high, the sprayed film coated on the surface was stably stabilized. The sleeve can be held.
[0035]
In addition, since the WC sprayed film is heat treated to increase the hardness, the wear resistance is increased and the life and reliability of the bearing device are increased.
In this embodiment, the sprayed film using WC as the main component and NiCr as the binder as the material of the sprayed film formed on the sleeve and the bearing has been described. However, the thermal spraying using WC as the main component and Co as the binder is described. Film or Cr 3 C 2 The same effect was obtained even when a sprayed coating containing NiCr as a main component and NiCr as a binder was used.
The drainage pump of the present embodiment exhibits stable sliding performance even when the bearing device is in a non-lubricated condition, that is, in a non-water supply state, and can perform better sliding in sliding after water supply.
In addition, although the drainage pump of this embodiment is provided with an intrusion prevention member that prevents the intrusion of earth and sand into the sliding part of the bearing device, the sliding part is not affected even if the earth and sand mixed in the drainage enters the sliding part. Since it has sufficient wear resistance, stable operation is possible.
Further, since good sliding performance can be obtained even in a non-lubricated state, a highly reliable operation can be performed even in a use situation where the non-lubricated state and the lubricated state are repeated, that is, in a prior standby operation.
[0036]
FIG. 4 is a longitudinal sectional view of a pump bearing device showing another embodiment of the present invention. The sliding surface of the sleeve base material 8 of SUS403 was coated with a sprayed film 9 containing WC as a main component and Co as a binder. The bearing 13 that slides with the sleeve 2 is made of SiC. The sleeve 2 was subjected to a heat treatment at 400 ° C. for 20 hours after the sprayed film was formed to increase the hardness of the sprayed film. Other structures are the same as those of the embodiment described with reference to FIGS.
According to this embodiment, since the material of the bearing portion is made of a sintered ceramic having a uniform and high hardness, the life and reliability of the bearing device are increased.
In the present embodiment, the sprayed film having WC as the main component and NiCr as the binder has been described as the material of the sprayed film formed on the sleeve, but the sprayed film having WC as the main component and Co as the binder may be used. Cr 3 C 2 The same effect was obtained even when a sprayed coating containing NiCr as a main component and NiCr as a binder was used.
[0037]
FIG. 5 is a longitudinal sectional view of a pump bearing device showing another embodiment of the present invention. The present embodiment is a bearing structure that can cope with the idling operation in which the drainage water level does not reach the bearing height during the preceding standby operation. In addition, in this figure, in order to show the whole structure, the detailed cross-sectional structure of the sleeve 2 is not illustrated. The sliding surface of the sleeve 2 made of SUS403 material was coated with a thermal spray film mainly composed of WC and NiCr binder, and after the thermal spray film was formed, heat treatment was performed at 400 ° C. for 20 hours to increase the hardness of the thermal spray film. The bearing 13 that slides with the sleeve 2 is made of SiC, attached to the back metal 6, and fixed to a fixing member 7 ′ protruding from the casing via the bearing cushioning material 5. Further, the baffle plate 17 was fixed to the fixing member 7 ′. A rotating water tank 18 was fixed to the main shaft 1. Even in the idling operation in which water is stored in the rotating water tank 18 and the drainage water level does not reach the bearing height, lubricating water is present in the bearing sliding portion. In this structure, since the earth and sand easily collect in the rotating water tank 18, the earth and sand may infiltrate into the sliding portion during operation. However, the heat resistance of the sprayed film 11 on the sleeve sliding surface increased in hardness by heat treatment. Wearability is sufficient and there is no hindrance to operation.
[0038]
6 and 7 are a sectional view of a fixing portion and a sleeve fixing state of a pump bearing device according to another embodiment of the present invention. In this embodiment, a sleeve divided into four in the circumferential direction is used. The four divided sleeves 2a, 2b, 2c and 2d are made of SUS403, and the sliding surface with the bearing is Cr. 3 C 2 After forming a thermal spray film containing NiCr as a main component and NiCr as a binder, heat treatment is performed at 400 ° C. for 20 hours. The sleeve parts 2a, 2b, 2c and 2d were fixed to the main shaft 1 with bolts 14 at two axial positions.
Other structures are the same as those of the embodiment described with reference to FIGS.
[0039]
A method for manufacturing and assembling the bearing will be described below. Sleeve parts 2a, 2b, 2c and 2d are prepared by SUS403 and subjected to the same heat treatment as the above bearing manufacturing method. After the heat treatment, a sprayed film WC containing WC as a main component and NiCr or Co as a binder is formed on the sliding surface of the sleeve by high-speed flame spraying. After forming the sprayed film, the sleeve is heated to 400 ° C. and held for about 20 hours. After the heat treatment, it is fixed to the main shaft 1 and processed into a predetermined dimension. Note that a bolt is sufficient for fixing to the main shaft 1, but if an adhesive is used in combination, the reliability is further increased.
In this embodiment, since the sleeve is divided, the sprayed film can be easily formed, and the weight of each of the divided sleeves is about ¼ that of the integrated type. Become.
FIG. 8 is an external view including a partial cross section of a bearing of a pump bearing device according to another embodiment of the present invention. This embodiment has a structure in which sliding members 19 obtained by dividing the sliding portion of the bearing are arranged and formed. The sliding member 19 is formed by forming a sprayed film 11 having WC as a main component and NiCr or Co as a binder on a base material 10 made of SUS403 by high-speed flame spraying. After forming the sprayed film, 400 ° C. × 20 hours. Heat treatment was applied to increase the hardness of the sprayed film. The sliding member 19 is attached to the back metal 6 via the cushioning material 5 and disposed on the bearing casing 20. Although the sliding member 19 is attached to the bearing casing 20 by the fixing jig 21, if the adhesive is used together, the reliability is further increased.
In the present embodiment, since the bearing sliding portion has a divided structure, it is easy to form the sprayed film, and each sliding member 19 is fixed via the cushioning material 5, so It is effective for prevention.
[0040]
In the present invention, SUS can be used for a sleeve that has been conventionally made of a super hard material mainly composed of WC, and the weight can be significantly reduced. Furthermore, unlike a super hard material, when a base material is SUS, since screw hole processing is possible, handling becomes easy. In particular, when the diameter is large, the weight of the sleeve increases, and the present invention is effective. The effect of the present invention on the weight reduction of the sleeve is summarized in FIG. FIG. 9 is a diagram showing the correlation between the outer diameter of the sleeve (hereinafter referred to as D) and the weight of the sleeve (hereinafter referred to as W). Since the sleeve weight W varies depending on the outer diameter D of the sleeve, W / D 2 As standardized. In the sleeve of the present invention, W / D 2 Decreases significantly, showing 0.05 or less.
[0041]
FIG. 10 shows a sectional view of a water turbine using the bearing device of the present invention as a water turbine bearing as another embodiment. In FIG. 10, reference numeral 22 denotes a main shaft for a water turbine, 23 is a rotation of a sleeve, and 24 is a sprayed film (hereinafter referred to as WC-27% NiCr sprayed film) in which WC is the main component and NiCr is added as a binder by 27 wt%. SUS403 sleeve which has been heat treated after coating), 25 is heat treated Cr 3 C 2 As a main component and NiCr as a binder with 25% added as a binder (hereinafter referred to as Cr) 3 C 2 A bearing made of SUS403, which is coated with a 25% NiCr sprayed coating and then heat-treated, is a liner. The sleeve and the bearing were coated with a sprayed film using high-speed flame spraying. The thermally sprayed coating has a wear resistance equivalent to that of the sintered body as shown in the element test results. In addition, since it is easy to increase the diameter, it is effective for reducing the cost and weight of the water turbine.
[0042]
In order to investigate the wear resistance characteristics of the bearings used in the above examples, the hardness change of the sprayed film due to heat treatment was examined by an element test. The change in hardness of the sprayed film by heating was examined in the range of heating temperature 200 ° C. to 600 ° C. and heating time 1 to 30 hours. The hardness of the sprayed film was measured with a micro Vickers hardness meter and indicated as Vickers hardness (hereinafter referred to as Hv). In order to avoid the influence of the substrate, the hardness was measured on the cross section of the sprayed film, and the load was constant at 300 g.
[0043]
FIG. 11 shows a part of the measurement results, and shows a change in hardness when the WC-27% NiCr sprayed film is heated at 400 ° C. The horizontal axis is the heating time, and the horizontal axis is the hardness of the sprayed film. The sprayed film is formed by high-speed flame spraying, the film thickness is about 100 μm after surface polishing, and the base is SUS403, which is quenched before thermal spraying and tempered at about 700 ° C. In addition, since the measured value of hardness has dispersion | variation, 10 points | pieces were measured, the maximum and minimum value in the measured value were shown with the line as the variation range, and the average value was shown by (circle).
[0044]
As shown in FIG. 11, the hardness of the sprayed film increases with time, reaches the maximum hardness in 10 to 30 hours, and then becomes substantially constant with variations. The maximum value of the average hardness is Hv1014 (maximum value Hv1065, minimum value Hv890). Hardness, average value Hv1317 (maximum value Hv1404, minimum value Hv1235) of a sintered body (hereinafter referred to as WC-12% Co sintered body) in which WC was measured as a main component and Co was added as a binder in an amount of 12% by weight. However, the average value of the hardness before the heat treatment Hv 727 (maximum value Hv 869, minimum value Hv 604) is about 34% increase in average value, which is remarkably improved.
[0045]
FIG. 12 shows part of the measurement results, and shows the change in hardness when the WC-27% NiCr sprayed film is heated at 500 ° C. as in FIG. The sample formation method, shape, and hardness measurement method are all the same as in FIG. The hardness of the sprayed film reaches almost the maximum hardness when heated for about 1.5 hours. The maximum value of the average hardness is Hv1115 (maximum value Hv1139, minimum value Hv1084). Compared to the hardness before the heat treatment, the average value is about 47% increase, which is almost equal to the WC-12% Co sintered body.
[0046]
FIG. 13 is also a part of the measurement result, and the hardness change when a sprayed film (hereinafter referred to as WC-12% Co sprayed film) containing 12 wt% of WC as a main component and Co as a binder is heated at 400 ° C. Indicates. The WC-12% Co sprayed film is also formed by high-speed flame spraying similar to the samples of FIGS. 11 and 12, and the film thickness is about 100 μm after surface polishing, and the base is SUS403 that has been heat-treated. The method for measuring the shape and hardness of the sample is also the same as in FIGS. In the case of the WC-12% Co sprayed film, the hardness increases with time, reaches the maximum hardness in 10 to 20 hours, and slightly decreases in 25 hours. The maximum hardness is Hv946 (maximum value Hv1149, minimum value Hv792) in average value. Compared to the hardness before heat treatment, the average value Hv584 (maximum value Hv652, minimum value Hv490), the average value is about 62% increase. When heated at 500 ° C., the hardness change was almost the same as in the case of the WC-27% NiCr sprayed film, and the maximum hardness was reached by heating for about 1 hour.
[0047]
FIG. 14 is also a part of the measurement result, and Cr 3 C 2 The hardness change when a -25% NiCr sprayed film is heated at 400 degreeC is shown. Cr 3 C 2 The −25% NiCr sprayed film is also formed by high-speed flame spraying similar to each sample used in the above-described measurement of FIGS. 11, 12 and 13, the film thickness is about 100 μm after surface polishing, and the base is SUS403 that has been heat-treated. is there. The shape and hardness of the sample are also measured in the same manner as in FIGS. Cr 3 C 2 For a -25% NiCr sprayed coating, the hardness gradually increases with time. The maximum value of the average hardness at the heating time of 25 hours is Hv958 (maximum value Hv1043, minimum value Hv905). Compared to the hardness before heat treatment, average value Hv791 (maximum value Hv817, minimum value Hv744), the average value is about 21% increase, and the WC-27% NiCr sprayed film and WC-12% Co sprayed film are more prominent. Does not increase. Also, when heated at 500 ° C., the hardness gradually increases with time as in 400 ° C. heating, but the ratio is larger.
[0048]
WC-27% NiCr sprayed film, WC-12% Co sprayed film and Cr 3 C 2 The hardness of the −25% NiCr sprayed coating is remarkably improved by heating at 400 to 500 ° C., and becomes almost equal to the hardness of the sintered body of WC-12% Co. By heating at 400 ° C to 500 ° C, WC particles or Cr in the sprayed film 3 C 2 It is considered that the bonding force between the particles and the binder increased, and was almost equal to the sintered body.
[0049]
The results of investigation in the range of heating temperature 200 ° C. to 600 ° C. and heating time 1 to 30 hours are summarized below. When the heating temperature is 300 ° C. or less, the hardness of the sprayed film increases, but the rate of increase is extremely small and it is difficult to use industrially. Accordingly, the heat treatment temperature is 300 ° C. or higher, preferably 350 ° C. or higher. However, the thermal expansion coefficient of the Fe-based material used for the pump is about 12 to 17 × 10? 6 / ° C, WC or Cr 3 C 2 Is the thermal spray coefficient of about 5-7 × 10? 6 Since the heating temperature is too high, thermal stress is generated due to the difference in thermal expansion coefficient between the sprayed film and the base, reducing the adhesive strength of the film, and in extreme cases, the film is peeled off. Further, when heat treatment is performed in the atmosphere, the sprayed film is oxidized and wear resistance is lowered. Therefore, WC or Cr 3 C 2 As long as a thermal sprayed coating is used, the heat treatment temperature is 550 ° C. or lower, preferably 500 ° C. or lower. The sprayed film is preferably heated in an inert gas or vacuum to prevent oxidation.
[0050]
FIG. 15 shows a WC-27% NiCr sprayed film sprayed to a thickness of about 200 μm, heated at 400 ° C., then surface-polished to a thickness of about 100 μm, further heated, and again polished to a mirror surface state. The schematic diagram of a metallographic photograph is shown. The final film thickness is about 90 μm. (A) is a photograph of an untreated sprayed film, (B) is a photograph of a sprayed film heated for 10 hours, (C) is a photograph of a sprayed film heated for 20 hours, and the magnifications are all 100 times.
[0051]
Since the observation is performed without etching, the difference between the WC particles and the binder NiCr cannot be observed, and all are observed as a white base. Portions that are scattered and appear black are holes. When (A), (B), and (C) are compared, the number of pores decreases and the size decreases with the heat treatment time. Since the sample used for the test was cut from a sprayed film formed on a SUS403 plate (26 mm × 26 mm), the difference in the number of holes was not caused by the spraying conditions, but the holes were not formed by heat treatment. It is a decrease. The same phenomenon was observed with the WC-12% Co sprayed film or the Cr3c2-25% NiCr sprayed film.
[0052]
FIG. 16 shows the relationship between the heating time and the density of pores having a size of 20 μm or more observed on the surface when the WC-27% NiCr sprayed film is heated at 400 ° C. The method for observing the surface vacancies is the same as the method shown in FIG. On the other hand, when the structure of the WC-27% NiCr sprayed film was observed with a scanning electron microscope, the average particle diameter of the WC particles and the NiCr binder particles was about 10 μm, and at most 20 μm or less. Therefore, if the vacancies are several μm or less, the WC particles are less affected. However, when the thickness is 20 μm or more, WC particles fall off, which is a direct cause of reducing the strength of the sprayed film. Therefore, in this measurement of vacancies, only those having a particle diameter of 20 μm or more were measured. Hereinafter, when expressed as holes, all holes are 20 μm or more.
[0053]
As shown in FIG. 16, when the heating temperature is 400 ° C., the number of vacancies rapidly decreases when heated for 15 hours or more. This change in pore density is consistent with the change in hardness shown in FIG. That is, it is considered that the change in hardness of the sprayed film due to heating is caused by the hole density in the sprayed film.
[0054]
The relationship between the hole density and the hardness is obtained from the change in hardness due to the heating time and the change in hole density shown in FIGS. 12 and 16, and is shown in FIG. Pore density is 30 / mm 2 Hardness starts to increase below 15 pieces / mm 2 The desired hardness for the pump bearing is as follows. Therefore, as the thermal spray film disposed on the pump bearing portion, the pore density of 20 μm or more existing on the surface is 15 / mm. 2 Below, desirably 10 pieces / mm 2 It is as follows. WC-12% Co sprayed film, Cr 3 C 2 The same phenomenon was observed with a -25% NiCr sprayed film.
[0055]
The following elemental tests were conducted to examine the wear resistance of bearings and sleeves using thermal sprayed coatings against sediment water. A part of the method and the result will be described with reference to FIGS. FIG. 18 shows the shape of the test piece and the sliding method. The rotating side test piece 15 shown in (A) and the fixed side test piece 16 shown in (B) are immersed in water containing silica sand assuming earth and sand water, and the rotating side test piece is rotated as shown in (C). And a predetermined surface pressure is applied and slid. After sliding for a predetermined time, the wear amount of both samples was measured. The amount of wear was determined by measuring the thickness of the rotation-side test piece 15 before and after the test and the surface shape of the fixed-side test piece 16 before and after the test with a surface roughness meter. The examined condition range is a surface pressure of 1 to 10 kg / cm. 2 The peripheral speed is about 0.5 to 5 m / s, and the silica sand concentration is 0.1 to 10 wt%. In addition, in order to reduce the effect of the silica sand itself being worn out, the sand water is changed every 3.6 km, and every time the sand water is changed so that the silica sand is easily caught between the two test pieces, The sliding test was repeated.
[0056]
FIG. 19 is a part of the result of examining the wear resistance of the thermally sprayed coating by the above test. The horizontal axis represents the sliding distance, and the vertical axis represents the average wear amount of the rotating side test piece. The fixed-side test piece is α-SiC, the rotation-side test piece is a WC-27% NiCr sprayed film, the film thickness is about 100 μm, the base is SUS403 subjected to quenching and tempering heat treatment. The heat treatment conditions of the sprayed film were set to 400 ° C. × 20 hours with reference to the result of FIG. As comparative materials, a WC-12% Co sintered body and an untreated WC-27% NiCr sprayed film were tested under the same conditions as a rotating side test piece. Other test conditions are 2kg / cm of surface pressure 2 The peripheral speed is 0.5 m / s, and the silica sand concentration is 9 wt%.
[0057]
In FIG. 19, the line (1) indicated by-▲-is a change in the amount of wear of the heat-treated WC-27% NiCr sprayed film which is the bearing member of the present invention, and the line (2) indicated by -O- is a comparative material. A change in wear amount of a conventional WC-12% Co sintered body, which is a bearing member, and a line (3) indicated by -Δ- is a change in wear amount of a non-heat treated WC-27% NiCr sprayed film as a comparative material. is there. The wear rate of the unheat-treated WC-27% NiCr sprayed film is about three times as high as that of the WC-12% Co sintered body, whereas the heat-treated WC-27% NiCr sprayed film is almost equivalent. Indicates the wear rate. That is, the amount of wear of the WC-27% NiCr sprayed coating on the earth and sand water was reduced to about 1/3 by heat treatment at 400 ° C. for 20 hours. This decrease in the amount of wear is considered to result from an increase in hardness due to the heat treatment of the sprayed film shown in FIG. Also from the relationship between the hardness of the sprayed film and the wear rate shown in FIG. 21, the wear resistance of the heat-treated sprayed film is a reasonable value. Further, although not shown in FIG. 19, a WC-27% NiCr sprayed film subjected to heat treatment at 400 ° C. × 20 hours and Si 3 N 4 The combination with also shows good wear resistance. Si used for the fixed side specimen 3 N 4 Exhibited wear resistance superior to that of SiC.
[0058]
According to the same test, the WC-12% Co sprayed film also shows the improvement effect by the same heat treatment. However, in the case of a WC-12% Co sprayed film, the hardness does not increase as much as that of a WC-27% NiCr sprayed film. Therefore, the wear resistance of the WC-12% Co sintered body and the heat treated WC-27% NiCr sprayed film is improved. It doesn't reach. Furthermore, since the binding material Co is inferior in corrosion resistance to NiCr, wear due to corrosion may occur. In the heat-treated WC-12% Co sprayed film under this condition, since the surface void density is reduced, the wear resistance against corrosion wear is improved even with the Co binder. However, the corrosion resistance against wastewater containing salt like seawater is still insufficient. Therefore, depending on the usage environment, a bearing using a WC-12% Co sprayed film cannot be used.
[0059]
According to a similar test, Cr 3 C 2 A -25% NiCr sprayed coating also improves wear resistance. However, the wear resistance is not significantly improved as compared with the WC-27% NiCr sprayed film and the WC-12% Co sprayed film. This is Cr 3 C 2 This is because the hardness of the −25% NiCr sprayed film itself is essentially not as high as that of the WC-27% NiCr sprayed film and the WC-12% Co sprayed film, and therefore the effect is small even if heat treatment is performed.
[0060]
When the heat-treated WC-27% NiCr sprayed film is used for both the fixed side and the rotating side test pieces, and the heat-treated WC-27% NiCr sprayed film for the rotating side test pieces and the fixed side test pieces. Heat treated Cr 3 C 2 The results of using a -25% NiCr sprayed coating are shown together in FIG.
[0061]
FIG. 20 shows the wear rate at the test time of 60 hours for both the fixed and rotating side test pieces. The test conditions are the same as in the test of FIG. The relative wear rate on the vertical axis is the combination of the WC-12% Co sintered body and α-SiC (A), and the wear rate of each test piece on the rotating side and the fixed side is 1.0. And the wear rate of each sample as a relative value. Also, in the bar graph, the side with the diagonal line is the wear rate of the rotating side test piece, and the side without it is the wear rate of the fixed side test piece.
[0062]
The combination (A) is a combination of a WC-12% Co sintered body and α-SiC, and is the result of the curve (2) in FIG. (B) is a combination result of the unheat-treated WC-27% NiCr sprayed film and α-SiC shown in the curve (3) of FIG. (C) is a combination result of heat-treated WC-27% NiCr sprayed film and α-SiC, which is the bearing member of the present invention shown in curve (1) of FIG. (D) is a combination result of a heat-treated WC-27% NiCr sprayed film and a heat-treated WC-27% NiCr sprayed film as the bearing member of the present invention, and (E) is a heat-treated WC-27% NiCr sprayed film. Heat treated Cr 3 C 2 It is a combination result with a -25% NiCr sprayed film. The thermal treatment conditions for the sprayed film are all 400 ° C. × 20 hours.
[0063]
As shown in FIG. 19, the combination of (C) is almost the same as the combination (A), that is, the combination of a WC-12% Co sintered body and α-SiC in both the stationary and rotating test pieces. Shows wear resistance. Even in the combination of (D) using heat-treated WC-27% NiCr sprayed coatings on both the fixed and rotating specimens, the rotating and stationary specimens are almost the same as the WC-12% Co sintered body. Showed wear resistance.
[0064]
The heat-treated WC-27% NiCr sprayed film of the fixed-side test piece showed excellent wear resistance higher than α-SiC. The hardness of α-SiC is an average value Hv2704 (maximum value Hv2874, minimum value Hv2591), which is much higher than the heat-treated WC-27% NiCr sprayed film. Nevertheless, the reason why the WC-27% NiCr sprayed film showed better wear resistance than α-SiC is considered to be due to the difference in ductility between them, that is, the fracture toughness. The fracture toughness of α-SiC is about 3.9 (MN / m · √m), which is less than about 13 (MN / m · √m) of the thermally treated WC-27% NiCr sprayed film. It is considered that the excellent fracture toughness of the heat-treated WC-27% NiCr sprayed film affected the wear resistance more than the hardness and exhibited the above-mentioned excellent wear resistance. The fracture toughness was measured by the Vickers indentation method.
[0065]
Heat treated WC-27% NiCr sprayed coating on rotating side test piece, heat treated Cr on fixed side test piece 3 C 2 The combination of (E) using a -25% NiCr sprayed film showed the result that the relative wear rate of the rotating side test piece was almost the same as the combination of (C) and (D).
[0066]
However, the heat-treated Cr of the fixed side specimen 3 C 2 The wear rate of the -25% NiCr sprayed coating is α-SCr. 3 C 2 It showed a higher value than iC or heat treated WC-27% NiCr sprayed film. As shown in FIG. 14, even if heat treatment is performed, Cr 3 C 2 This is probably because the hardness of the −25% NiCr sprayed film does not increase significantly. However, under conditions where the temperature of the wastewater is high, Cr 3 C 2 The -25% NiCr sprayed film showed wear resistance equal to or higher than that of the WC-27% NiCr sprayed film. This is Cr 3 C 2 This is probably because the -25% NiCr sprayed coating has a small decrease in hardness at high temperatures. Therefore, depending on the usage environment, heat treated WC-27% NiCr sprayed film and heat treated Cr
3 C 2 The combination of -25% NiCr sprayed film is good.
[0067]
The above results are summarized below.
Heat-treated WC-27% NiCr sprayed film is used for sleeve, SiC or Si 3 N 4 When combined with a bearing, good wear resistance and sliding properties can be obtained. In this case, SiC or Si 3 N 4 Since the strength increases when compressive stress is applied, it is better to use it on the bearing side of the structure supported by the back metal by shrink fitting. When heat-treated WC-27% NiCr sprayed film is used for both sleeves and bearings, it generally exhibits excellent wear resistance and sliding properties. In this case, even with a WC sprayed coating using Co as a binder, excellent wear resistance can be obtained as well. However, when salt is contained in the wastewater, it is difficult to use due to corrosion. Heat treated WC-27% NiCr sprayed film and heat treated Cr 3 C 2 When a -25% NiCr sprayed coating is used for the sleeve and bearing, the wear resistance is not as excellent as the combination of the heat treated WC-27% NiCr sprayed coating. However, when drainage temperature is high, more excellent characteristics are exhibited. In this case, a WC-27% NiCr sprayed film may be disposed on either the sleeve or the bearing, and the characteristics are not affected.
[0068]
Therefore, the bearing structure of the present invention has almost the same wear resistance of the sleeve and the sliding surface of the bearing as that using the WC-12% Co sintered body for the bearing, and the weight of the sleeve and the bearing is small. Easy to assemble. Further, since the toughness of the sleeve and the bearing is high, there is no breakdown due to impact, and the reliability is improved. For this reason, a rotating machine using the bearing structure of the present invention, such as a pump, has high reliability.
[0069]
In each of the above embodiments, high-speed flame spraying is used as the sprayed film forming method. However, explosive spraying, low-pressure plasma spraying, laser spraying, and plasma spraying may be used, and the manufacturing method is not limited thereto. The hardness before the heat treatment is preferably high, and high-speed flame spraying and explosive spraying that can form a high-hardness sprayed film are desirable.
[0070]
In each of the above embodiments, SUS403 is used as the material for the sleeve base material and the bearing base material, but any material that can be used in water may be used. WC or Cr 3 C 2 SUS403 is more desirable than SUS304, which has a large thermal expansion coefficient. In consideration of a decrease in corrosion resistance of SUS due to heat treatment, SUS304L or SUS316L having a low carbon content is desirable.
[0071]
In each of the above embodiments, NiCr and Co are used as the binder, and the contents are 12 wt%, 25 wt%, and 27 wt%. However, if the properties are satisfied as a sprayed film, the contents are not limited. Absent.
[0072]
【The invention's effect】
According to the present invention, WC or Cr 3 C 2 By heating a sprayed film mainly containing WC under predetermined conditions, WC particles, Cr 3 C 2 The bond strength between the particles and the binder increases, resulting in a decrease in the number of pores in the sprayed coating and an increase in hardness of about 50-60% on average, improving wear resistance against earth and sand water by about three times that before heat treatment. To do. This characteristic is almost the same as that of a ceramic sintered body such as WC-12% Co. Instead of a sleeve and a bearing made of a WC-12% Co sintered body, a sleeve having a metal surface coated with a sprayed film and a bearing may be used. it can. As a result, WC, SiC, Si 3 N 4 Large diameter bearings and sleeves that could not be manufactured with this sintered body can be manufactured.
[0073]
Further, since the weight of the bearing and the sleeve is reduced regardless of the diameter, the assemblability is greatly improved. Also, WC, SiC, Si with low toughness 3 N 4 Stainless steel can be used as a base material instead of The Therefore, the reliability of the bearing and sleeve is increased. Therefore, the reliability of the pump using this bearing device is increased.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a drainage pump structure according to an embodiment of the present invention.
FIG. 2 is a partial cross-sectional perspective view showing a bearing device according to an embodiment of the present invention.
FIG. 3 is a longitudinal sectional view of a bearing device according to another embodiment of the present invention.
FIG. 4 is a longitudinal sectional view of a bearing device according to another embodiment of the present invention.
FIG. 5 is a longitudinal sectional view of a bearing device according to another embodiment of the present invention.
FIG. 6 is a perspective view showing a sleeve structure according to another embodiment of the present invention.
7 is a cross-sectional view taken along the line AA in FIG.
FIG. 8 is a partial sectional perspective view showing a bearing according to another embodiment of the present invention.
FIG. 9 shows an outer diameter D and a weight W / (outer diameter D) of a sleeve according to another embodiment of the present invention. 2 FIG.
FIG. 10 is a cross-sectional view showing a water wheel structure according to another embodiment of the present invention.
FIG. 11 is a diagram showing a change in hardness of a WC-27% NiCr sprayed film when heated at 400 ° C.
FIG. 12 is a diagram showing a change in hardness of a WC-27% NiCr sprayed film when heated at 500 ° C.
FIG. 13 is a diagram showing a change in hardness of a WC-12% Co sprayed film when heated at 400 ° C.
FIG. 14 Cr 3 C 2 It is a figure which shows the hardness change at the time of 400 degreeC heating of a -25% NiCr sprayed film.
FIG. 15 is a schematic diagram of a metallographic photograph showing a change state of a WC-27% NiCr sprayed film when heated at 400 ° C. FIG.
FIG. 16 is a graph showing the relationship between the vacancy density of the sprayed film surface and the heating time when the WC-27% NiCr sprayed film is heated at 400 ° C.
FIG. 17 is a graph showing the relationship between the vacancy density and the hardness of the sprayed film surface when the WC-27% NiCr sprayed film is heated at 400 ° C.
FIG. 18 is a diagram showing a shape of a wear test piece and a sliding method.
FIG. 19 is a relationship diagram between the sliding distance and the wear amount of a WC-12% Co sintered body, an unheated WC-27% NiCr sprayed film and a heat-treated WC-27% NiCr sprayed film by an abrasion test.
FIG. 20: Heat treated WC-27% NiCr sprayed film, heat treated Cr 3 C 2 It is a relative abrasion rate comparison figure of various material combination containing a -25% NiCr sprayed film.
FIG. 21 is a diagram showing the hardness of each conventional sprayed coating and the relative wear rate based on a WC-12% Co sintered body with respect to earth and sand water.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Main shaft, 2 ... Sleeve, 3 ... Bearing, 4 ... Sleeve stop, 5 ... Bearing cushioning material, 6 ... Bearing back metal, 7, 7 '... Fixing member, 8 ... Sleeve base material, 9, 11 DESCRIPTION OF SYMBOLS ... Sprayed film, 10 ... Bearing base material, 13 ... Ceramic bearing, 14 ... Split sleeve fixing bolt, 15, 16 ... Wear test piece, 17 ... Baffle plate, 18 ... Rotating water tank, 19 ... Sliding member, 20 ... Bearing Casing, 21 ... fixing jig, 22 ... main shaft for water wheel, 23 ... stop of sleeve, 26 ... liner.

Claims (6)

内部を排水が流動するケ−シングと、前記ケ−シング内で軸受装置により支持されその一部にインペラを配置し回転する主軸とを備えるものであって、前記軸受装置の少なくとも１か所は外部より清浄水を供給することなく運転されるものである排水ポンプにおいて、
前記軸受装置を構成するスリ−ブの摺動部は２個以上に分割され、かつ
前記軸受装置を構成する軸受及びスリ−ブのいずれか一方若しくは両方の摺動面は溶射膜を被覆したものであり、前記溶射膜はその表面に形成される２０μｍ以上の大きさの空孔の密度が１５個／ｍｍ2以下であることを特徴とする排水ポンプ。A casing in which drainage flows; and a main shaft that is supported by a bearing device in the casing and has an impeller disposed on a part thereof and that rotates, wherein at least one of the bearing devices includes: In the drainage pump that is operated without supplying clean water from the outside,
The sliding portion of the sleeve constituting the bearing device is divided into two or more, and one or both sliding surfaces of the bearing and sleeve constituting the bearing device are coated with a sprayed film. The sprayed coating is characterized in that the sprayed film has a density of pores of 20 μm or more formed on the surface thereof of 15 / mm 2 or less. 内部を排水が流動するケ−シングと、前記ケ−シング内で軸受装置により支持されその一部にインペラを配置し回転する主軸とを備えるものであって、前記軸受装置の少なくとも１か所は外部より清浄水を供給することなく運転されるものである排水ポンプにおいて、
前記軸受装置を構成するスリ−ブの摺動部は２個以上に分割され、かつ
前記軸受装置を構成する軸受及びスリ−ブのいずれか一方若しくは両方の摺動面は溶射膜を被覆したものであり、該溶射膜は、被覆した後３００℃以上５５０℃以下の温度で１時間以上加熱され、該溶射膜のビッカース硬さが１０００以上であることを特徴とする排水ポンプ。A casing in which drainage flows; and a main shaft that is supported by a bearing device in the casing and has an impeller disposed on a part thereof and that rotates, wherein at least one of the bearing devices includes: In the drainage pump that is operated without supplying clean water from the outside,
The sliding portion of the sleeve constituting the bearing device is divided into two or more, and one or both sliding surfaces of the bearing and sleeve constituting the bearing device are coated with a sprayed film. The drainage pump, wherein the sprayed film is coated and heated at a temperature of 300 ° C. or more and 550 ° C. or less for 1 hour or more, and the sprayed film has a Vickers hardness of 1000 or more. 内部を排水が流動するケ−シングと、前記ケ−シング内で軸受装置により支持されその一部にインペラを配置し回転する主軸とを備えるものであって、前記軸受装置の少なくとも１か所は外部より清浄水を供給することなく運転されるものである排水ポンプにおいて、
前記軸受装置を構成するスリ−ブの摺動部は２個以上に分割され、かつ
前記軸受装置を構成するスリーブの摺動面は溶射膜を被覆したものであり、前記溶射膜はその表面に形成される２０μｍ以上の大きさの空孔の密度が１５個／ｍｍ2以下であることを特徴とする排水ポンプ。A casing in which drainage flows; and a main shaft that is supported by a bearing device in the casing and has an impeller disposed on a part thereof and that rotates, wherein at least one of the bearing devices includes: In the drainage pump that is operated without supplying clean water from the outside,
The sliding part of the sleeve constituting the bearing device is divided into two or more, and the sliding surface of the sleeve constituting the bearing device is coated with a sprayed film, and the sprayed film is formed on the surface thereof. A drainage pump characterized in that the density of pores having a size of 20 μm or more formed is 15 / mm 2 or less. 内部を排水が流動するケ−シングと、前記ケ−シング内で軸受装置により支持されその一部にインペラを配置し回転する主軸とを備えるものであって、前記軸受装置の少なくとも１か所は外部より清浄水を供給することなく運転されるものである排水ポンプにおいて、
前記軸受装置を構成するスリ−ブの摺動部は２個以上に分割され、かつ
前記軸受装置を構成するスリ−ブの摺動面は溶射膜を被覆したものであり、そのｋｇ単位の重量Ｗと、ｃｍ単位の外径Ｄとの比、Ｗ／Ｄ2が０．０５以下であることを特徴とする排水ポンプ。A casing in which drainage flows; and a main shaft that is supported by a bearing device in the casing and has an impeller disposed on a part thereof and that rotates, wherein at least one of the bearing devices includes: In the drainage pump that is operated without supplying clean water from the outside,
The sliding part of the sleeve constituting the bearing device is divided into two or more, and the sliding surface of the sleeve constituting the bearing device is coated with a sprayed film, and its weight in kg A drainage pump characterized in that the ratio of W to the outer diameter D in cm, W / D 2 is 0.05 or less. 請求項１乃至４記載のいずれかにおいて、前記溶射膜はＷＣが主成分であることを特徴とする排水ポンプ。The drainage pump according to any one of claims 1 to 4, wherein the sprayed film is composed mainly of WC. 請求項１乃至４記載のいずれかにおいて、前記溶射膜はＷＣを主成分として結合材にＮｉ、Ｃｒ又はＣｏのいずれか１つ若しくは複数を含むもの又はＣｒ3Ｃ2を主成分として結合材にＮｉとＣｒを含むもののいずれかであることを特徴とする排水ポンプ。5. The sprayed film according to claim 1, wherein the sprayed coating includes WC as a main component and includes any one or more of Ni, Cr, or Co, or Cr 3 C 2 as a main component. A drainage pump characterized by being one containing Ni and Cr.
JP2000072448A 1992-03-18 2000-03-10 Drainage pump Expired - Fee Related JP3627614B2 (en)

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JP2003343474A (en) * 2002-05-29 2003-12-03 Hitachi Industries Co Ltd Bearing device and vertical shaft pump having this device
JP4322473B2 (en) * 2002-06-13 2009-09-02 株式会社東芝 Water supply pump
JP4156963B2 (en) * 2003-04-07 2008-09-24 本田技研工業株式会社 Bonding method between sprayed layer and steel member
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JP6777529B2 (en) * 2016-12-22 2020-10-28 株式会社荏原製作所 How to manufacture shaft sleeves, pumps, and shaft sleeves
JP7216362B2 (en) * 2018-07-17 2023-02-01 株式会社フジミインコーポレーテッド Three-dimensional modeling method, three-dimensional modeling apparatus and base material used therefor
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