JP4057749B2

JP4057749B2 - Diffusion bonding method

Info

Publication number: JP4057749B2
Application number: JP22398699A
Authority: JP
Inventors: 朋幸橋本; 真佐藤; 清信溝上; 孝治上田; 政克佐藤
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1999-08-06
Filing date: 1999-08-06
Publication date: 2008-03-05
Anticipated expiration: 2019-08-06
Also published as: JP2001050104A

Description

【０００１】
【発明の属する技術分野】
本発明は、軸方向一方に向かうにつれて小径となる被取付け面を有する被取付け部材に、前記被取付け面に少なくとも外周部を対向させる対向端面を軸方向一端に有するとともに横断面円形の外側面を有する取付け部材を、前記対向端面および前記外側面の連設部を被取付け面に最初に接触させつつ両部材の加熱状態で被取付け部材側に加圧する拡散接合方法に関する。
【０００２】
【従来の技術】
このような方法による拡散接合構造は、たとえば特開平７−１０３０７０号公報、特開平７−１８９６２８号公報および特開平９−１２２９２４号公報等により既に知られており、これらの公報には、被取付け部材としてのシリンダヘッドに、該シリンダヘッドとは異なる材料から成る取付け部材としてのバルブシートが拡散接合される構造とその方法が開示されている。
【０００３】
【発明が解決しようとする課題】
ところが、上記従来の拡散接合方法では、取付け部材のうち被取付け部材に接合される部分の接合前の外面が、直線の組み合わせから成る横断面形状を有しているために、前記直線部分で充分な塑性流動が生じないことにより、充分な接合強度が得られない。これは、取付け部材の被取付け部材側への加圧時に被取付け部材に最初に接触する先端部は鋭角に形成されているので、この部分では充分な塑性流動が生じて拡散接合層は充分に形成されるのであるが、直線状の断面形状を有して前記先端部に連なる部分では、前記先端部と比較して塑性流動物の滑り速度や塑性流動物の量が明らかに低下し、充分な拡散接合層が形成されないからであると思料される。
【０００４】
また取付け部材の被取付け部材への接合深さは、取付け部材の被取付け部材への没入によって生じる塑性流動物の量に対応した抵抗値ならびに排出された前記塑性流動物が被取付け面および対向端面間に噛込むことで生じる抵抗値の和と、加圧力とのバランスで定まるものであるが、前記噛込みによる抵抗値のバラツキは非常に大きく、接合深さを精度よくコントロールするのが困難であった。
【０００５】
本発明は、かかる事情に鑑みてなされたものであり、拡散接合時に取付け部材および被取付け部材間に生じる塑性流動物の滑り速度および塑性流動物の量の増大を図り、充分な接合強度を得ることができるようにするとともに、塑性流動物の噛込みによる抵抗値のバラツキを抑えて接合深さを精度よくコントロールし得るようにした拡散接合方法を提供することを目的とする。
【０００６】
【課題を解決するための手段】
上記目的を達成するために、請求項１記載の発明は、軸方向一方に向かうにつれて小径となる被取付け面を有する被取付け部材に、前記被取付け面に少なくとも外周部を対向させる対向端面を軸方向一端に有するとともに横断面円形の外側面を有する取付け部材を、前記対向端面および前記外側面の連設部を被取付け面に最初に接触させつつ両部材の加熱状態で被取付け部材側に加圧する拡散接合方法において、取付け部材の被取付け部材への接合前に、前記連設部を被取付け部材側に膨らんだ曲面状に形成するとともに、前記対向端面および外側面のうち被取付け部材に接合される部分を前記連設部よりも曲率半径を大きくした曲面状に形成しておく一方、前記被取付け部材の被取付け面に、前記対向端面の外周部に対向する環状の底面と、該底面の外周縁から取付け部材側に立ち上がって該取付け部材の外側面に対向する内側面とで構成される接合凹部を設けておき、前記取付け部材の前記被取付け部材側への加圧時に、前記連設部を前記底面の外周部に接触させる第１のステップと、前記対向端面を前記底面に半径方向外方側から順次接触させる第２のステップと、前記外側面を前記内側面に軸方向内方側から順次接触させて加圧抵抗値を立ち上がらせる第３のステップとを、順次実行することを特徴とする。
【０００７】
このような請求項１記載の発明の構成によれば、取付け部材および被取付け部材間に生じる塑性流動物の滑り速度および塑性流動物の量を増大し、良好な拡散接合により充分な接合強度を得ることができる。すなわち取付け部材のうち被取付け部材に接合される部分の接合前の外面形状が曲面であるものは、平坦面であるものに比べて、ストロークに対する塑性流動物の滑り速度を増大することが可能であり、取付け部材の被取付け部材側への加圧時に被取付け部材に被取付け面に最初に接触する連設部が、曲率半径を比較的小さくした曲面に形成されているので、その連設部の被取付け部材への没入により生じる塑性流動物の量を大とすることができ、また対向端面および外側面のうち被取付け部材に接合される部分が前記連設部よりも曲率半径を大きくした曲面状にそれぞれ形成されているので、塑性流動物の滑り速度を増大して塑性流動物を積極的に排出することができる。そして、前記取付け部材の前記被取付け部材側への加圧時の第１ステップでは、取付け部材の連設部が被取付け部材に没入することで塑性流動物が発生するのに応じて抵抗値が急激に増大するが、第２ステップでは取付け部材の対向端面が接合凹部の底面に半径方向外方側から順次接触することで前記抵抗値が徐々に増大し、さらに第３ステップでは、前記連設部および対向端面に加えて取付け部材の外側面が接合凹部の内側面に没入することで、前記抵抗値が大きく立上がることになるから、取付け部材の被取付け部材側への加圧時に、各ステップ毎に抵抗値の変化特性を異ならせ、目標接合深さ直前の接合終期に、抵抗値を大きく立ち上がらせる設定とすることで、加圧を停止するタイミングを精度よく定めることが可能となり、接合深さのコントロール精度を向上することができる。
【０００８】
また請求項２記載の発明は、上記請求項１記載の発明の構成に加えて、取付け部材の被取付け部材への接合前に、前記対向端面のうち被取付け部材に接合される部分よりも半径方向内方に、被取付け面および対向端面の接合界面から排出される塑性流動物を受け入れる環状の凹部を形成しておくことを特徴とする。
【０００９】
このような請求項２記載の発明の構成によれば、対向端面のうち被取付け部材に接合される部分よりも半径方向内方に環状の凹部が形成されているので、対向端面および被取付け面間から前記半径方向内方側に排出される塑性流動物を前記凹部内に逃がすことができ、排出された前記塑性流動物が被取付け面および対向端面間に噛込むことで生じる加圧抵抗値のバラツキを最少限に抑え、接合深さをより精度よくコントロールすることが可能となる。
【００１０】
【発明の実施の形態】
以下、本発明の実施の形態を、添付の図面に示した本発明の一実施例に基づいて説明する。
【００１１】
図１〜図７は本発明の一実施例を示すものであり、図１は４サイクルエンジンの要部縦断面図、図２はバルブシート素材のシリンダヘッドへの拡散接合直前の状態を示す縦断面図、図３は図２の要部拡大図、図４は拡散接合過程終了時の図３に対応した断面図、図５は拡散接合過程を順次説明するための断面図、図６は塑性流動物の滑り速度を説明するための図、図７は拡散接合過程での抵抗値の変化を示す図である。
【００１２】
先ず図１において、４サイクルエンジンのシリンダブロック１１に設けられたシリンダ孔１２に摺動可能に嵌合されるピストン（図示せず）と、シリンダブロック１１に結合される被取付け部材としてのシリンダヘッド１３との間には、燃焼室１４が形成されており、シリンダヘッド１３には、燃焼室１４に通じ得る吸気ポート１５および排気ポート１６が設けられる。
【００１３】
吸気ポート１５および排気ポート１６の燃焼室１４への開口端で、シリンダヘッド１３にはバルブシート１７，１８が接合されており、それらのバルブシート１７，１８に着座可能なシート部１９ａ，２０ａを備える吸気バルブ１９および排気バルブ２０のステム部１９ｂ，２０Ｂが、シリンダヘッド１３に設けられたガイド筒２１，２２にそれぞれ摺動可能に嵌合される。しかも前記各ステム部１９ｂ，２０ｂはガイド筒２１，２２から上方に突出するものであり、各ステム部１９ｂ，２０ｂの上端およびシリンダヘッド１３間に、吸気バルブ１９および排気バルブ２０を上方、すなわちシート部１９ａ，２０ａをバルブシート１７，１８に着座させて吸気ポート１５および排気ポート１６を閉じる方向に付勢するばね２３，２４が設けられる。また各ステム部１９ｂ，２０ｂの上端には図示しない動弁装置が連結されており、該動弁装置で吸気バルブ１９および排気バルブ２０が開閉駆動される。
【００１４】
ところでバルブシート１７，１８は、一般的には圧入によりシリンダヘッド１３に組付けられるのであるが、近年のエンジンレイアウトでは、吸気バルブ１９および排気バルブ２０が近接して配置されており、従来の圧入式では、より大きなバルブ径としたり、高圧縮比化を図ったりするために燃焼室１４の周囲のレイアウトを変更するにあたっての自由度が殆どない状態である。そこで上記圧入式に代えて、シリンダヘッド１３にバルブシート１７，１８を直接接合すると、バルブシート１７，１８の薄肉化によって前記レイアウトの自由度を大幅に向上させたり、バルブシート１７，１８を介しての熱伝達性が改善されることによる吸気および排気バルブ１９，２０、バルブシート１７，１８および燃焼室１４の温度を低減することが可能であり、エンジン性能の大幅向上を期待することができる。この際、バルブシート１７，１８が、シリンダヘッド１３とは異なる金属であっても拡散接合することで充分な接合強度を得ることが可能である。
【００１５】
図２において、シリンダヘッド１３には、取付け部材としてのバルブシート素材２５が拡散接合され、接合後のバルブシート素材２５に機械加工を施すことでバルブシート１７，１８が形成される。
【００１６】
而してシリンダヘッド１３としては、軽量かつ熱伝達性に優れた金属であるアルミニウム合金鋳物が用いられ、バルブシート素材２５としては、たとえば耐摩耗性に優れた鉄系の焼結合金や、冷却・熱伝導性に優れたＣｕ−Ｂｅ合金等が用いられる。
【００１７】
シリンダヘッド１３における吸気および排気ポート１５，１６の燃焼室１４側開口端には、軸方向に沿って燃焼室１４から離反するにつれて小径となる被取付け面２６が形成される。一方、バルブシート素材２５は、前記被取付け面２５に外周部を対向させる対向端面２７を軸方向一端に有するとともに横断面円形の外側面２８を有してリング状に形成される。
【００１８】
バルブシート素材２５は、該バルブシート素材２５およびシリンダヘッド１３の加熱状態でシリンダヘッド１３の被取付け面２６側に一定の加圧力で加圧されることにより、被取付け面２６に拡散接合される。而して前記加熱状態は、バルブシート素材２５をシリンダヘッド１３の被取付け面２６に接触させつつバルブシート素材２５およびシリンダヘッド１３に短時間に大電流を通電することにより、バルブシート素材２５およびシリンダヘッド１３の接触面がジュール発熱で発熱することにより得られる。
【００１９】
図３において、バルブシート素材２５は、該バルブシート素材２５のシリンダヘッド１３側への加圧時に前記対向端面２７および外側面２８の連設部２９をシリンダヘッド１３に最初に接触させるものであり、対向端面２７の外周側の部分２７ａならびに外側面２８の対向端面２７側の部分２８ａと、前記連設部２９とがシリンダヘッド１３に拡散接合される。
【００２０】
而してバルブシート素材２５のうちシリンダヘッド１３に接合される前に、前記連設部２９は、シリンダヘッド１３側に曲率半径Ｒ１で膨らんだ曲面状に形成され、対向端面２７の外周側の部分２７ａは前記連設部２９よりも大きな曲率半径Ｒ２でシリンダヘッド１３側に膨らんだ曲面状に形成され、外側面２８の対向端面２７側の部分２８ａも前記連設部２９よりも大きな曲率半径Ｒ３でシリンダヘッド１３側に膨らんだ曲面状に形成される。
【００２１】
また前記対向端面２７のうちシリンダヘッド１３に接合される部分２７ａよりも半径方向内方には環状の凹部３２が形成され、この凹部３２には、図４で示すように、被取付け面２６および対向端面２７の接合界面から排出される塑性流動物３３を受け入れることが可能である。
【００２２】
図３に注目して、バルブシート素材２５のシリンダヘッド１３への接合前に、シリンダヘッド１３の被取付け面２６には、バルブシート素材２５における対向端面２７の外周部に対向する環状の底面３４ａと、該底面３４ａの外周縁からバルブシート素材２５側に立ち上がって該バルブシート素材２５の外側面２８に対向する内側面３４ｂとで構成される接合凹部３４が設けられる。
【００２３】
しかも前記底面３４ａおよび前記内側面３４ｂは、バルブシート素材２５の被取付け面２６側への加圧時に、図５（ａ）で示すように、前記連設部２９を前記底面３４ａの外周部に接触させる第１のステップと、図５（ｂ）で示すように、前記対向端面２７を前記底面３４ａに半径方向外方側から順次接触させる第２のステップと、図５（ｃ）で示すように、前記外側面２８を前記内側面３４ｂに軸方向内方側から順次接触させて加圧抵抗値を立ち上がらせる第３のステップとが、順次実行されるように形成される。
【００２４】
次にこの実施例の作用について説明すると、バルブシート素材２５を、該バルブシート素材２５およびシリンダヘッド１３の加熱状態でシリンダヘッド１３側に加圧すると、バルブシート素材２５およびシリンダヘッド１３の接触面で滑り変形が生じ、バルブシート素材２５およびシリンダヘッド１３の表面の酸化皮膜、異物および金属間化合物が、図４で示すように塑性流動物３３として接合界面から排出されることになり、前記接合界面での微細凹凸や原子間空孔が消失し、極めて清浄で雰囲気ガスのない接触面が形成されることになる。しかも加熱状態での清浄面同士の接触により金属内自由電子が活性化され、バルブシート素材２５およびシリンダヘッド１３間での原子の粒内・粒界拡散が生じることで、バルブシート素材２５がシリンダヘッド１３に拡散接合される。
【００２５】
ところで、バルブシート素材２５のうちシリンダヘッド１３に接合される部分の接合前の外面形状が曲面で形成されるものは、平坦面であるものに比べて、加圧ストロークに対する塑性流動物３３の滑り速度を増大することが可能である。すなわち塑性流動物３３が、図６（ａ）で示す曲面を滑るときの滑り距離Ｌ１は、図６（ｂ）で示す平坦面を滑るときの滑り距離Ｌ２に対して、同一の加圧ストロークＳでは大（Ｌ１＞Ｌ２）となるものであり、バルブシート素材２５のうちシリンダヘッド１３に接合される部分の接合前の外面形状が曲面で形成されるものは、平坦面であるものに比べて滑り速度が大となるのである。
【００２６】
しかるにバルブシート素材２５のシリンダヘッド１３側への加圧時に最初にシリンダヘッド１３に接触する連設部２９が、曲率半径Ｒ１を比較的小さくして形成されているので、その先端側の連設部２９のシリンダヘッド１３への没入により生じる塑性流動物３３の量を大とすることができ、また前記連設部２９に連なる部分２７ａ，２８ａも曲面状に形成されているので、塑性流動物３３の滑り速度を増大して塑性流動物３３を積極的に排出することができる。したがってバルブシート素材２５をシリンダヘッド１３に良好に拡散接合して充分な接合強度を得ることが可能となる。
【００２７】
またバルブシート素材２５のシリンダヘッド１３への接合深さは、バルブシート素材２５のシリンダヘッド１３への没入によって生じる塑性流動物３３の量に対応した抵抗値ならびに排出された前記塑性流動物３３が被取付け面２６および対向端面２７間に噛込むことで生じる抵抗値の和と、加圧力とのバランスで定まるものであるが、前記噛込みによる抵抗値のバラツキは非常に大きく、そのバラツキを放置したままでは接合深さを精度よくコントロールするのが困難である。
【００２８】
しかるに対向端面２７のうちシリンダヘッド１３に接合される部分よりも半径方向内方には環状の凹部３２が形成され、この凹部３２には、塑性流動物３３を受け入れることが可能である。したがって対向端面２７および被取付け面２６間から内方側に排出される塑性流動物３３を凹部３２内に逃がすことができ、排出された前記塑性流動物３３が被取付け面２６および対向端面２７間に噛込むことで生じる加圧抵抗値のバラツキを最少限に抑え、接合深さをより精度よくコントロールすることが可能となる。
【００２９】
またバルブシート素材２５のシリンダヘッド１３への接合前に、シリンダヘッド１３の被取付け面２６には、環状の底面３４ａと、該底面３４ａの外周縁からバルブシート素材２５側に立ち上がる内側面３４ｂとで構成される接合凹部３４が設けられており、底面３４ａおよび内側面３４ｂは、バルブシート素材２５の被取付け面２６側への加圧時に、バルブシート素材２５の連設部２９を前記底面３４ａの外周部に接触させる第１のステップと、バルブシート素材２５の対向端面２７を前記底面３４ａに半径方向外方側から順次接触させる第２のステップと、バルブシート素材２５の外側面２８を前記内側面３４ｂに軸方向内方側から順次接触させる第３のステップとが順次実行されるように形成されており、このような接合凹部３４により、加圧を停止するタイミングを精度よく定めて接合深さのコントロール精度をより向上することができる。
【００３０】
図７において、第１ステップではバルブシート素材２５の連設部２９がシリンダヘッド１３に没入することで塑性流動物が発生するのに応じて抵抗値が急激に増大するが、第２ステップではバルブシート素材２５の対向端面２７が接合凹部３４の底面３４ａに半径方向外方側から順次接触することで前記抵抗値が徐々に増大し、さらに第３ステップでは、前記連設部２９および対向端面２７に加えてバルブシート素材２５の外側面２８が接合凹部３４の内側面３４ｂに没入するので、前記抵抗値が大きく立上がることになる。すなわちバルブシート素材２５をシリンダヘッド１３側に一定の加圧力で加圧する際に、各ステップ毎に抵抗値の変化特性を異ならせ、抵抗値が大きく立ち上がる最終の第３ステップでバルブシート素材２５を加圧する一定の加圧力と抵抗値（加圧に対する反力）とを釣合わせることにより、目標接合深さを精度よく得ることが可能となり、接合深さのコントロール精度をより向上することができる。
【００３１】
以上、本発明の実施例を詳述したが、本発明は上記実施例に限定されるものではなく、特許請求の範囲に記載された本発明を逸脱することなく種々の設計変更を行なうことが可能である。
【００３２】
たとえば本発明は、バルブシート素材２５のシリンダヘッド１３への拡散接合構造に限定されるものではなく、取付け部材の被取付け部材への拡散接合構造に広く適用可能である。
【００３３】
【発明の効果】
以上のように請求項１記載の発明によれば、取付け部材および被取付け部材間に生じる塑性流動物の滑り速度および塑性流動物の量を増大し、良好な拡散接合により充分な接合強度を得ることができ、しかも、取付け部材の被取付け部材側への加圧時に目標接合深さ直前の接合終期に、抵抗値を大きく立ち上がらせる設定とすることで、加圧を停止するタイミングを精度よく定めることが可能となり、接合深さのコントロール精度をより向上することができる。
【００３４】
また請求項２記載の発明によれば、排出された塑性流動物が被取付け面および対向端面間に噛込むことで生じる加圧抵抗値のバラツキを最少限に抑え、接合深さをより精度よくコントロールすることが可能となる。
【図面の簡単な説明】
【図１】４サイクルエンジンの要部縦断面図である。
【図２】バルブシート素材のシリンダヘッドへの拡散接合直前の状態を示す縦断面図である。
【図３】図２の要部拡大図である。
【図４】拡散接合過程終了時の図３に対応した断面図である。
【図５】拡散接合過程を順次説明するための断面図である。
【図６】塑性流動物の滑り速度を説明するための図である。
【図７】拡散接合過程での抵抗値の変化を示す図である。
【符号の説明】
１３・・・被取付け部材としてのシリンダヘッド
２５・・・取付け部材としてのバルブシート素材
２６・・・被取付け面
２７・・・対向端面
２７ａ・・・対向端面のうち被取付け部材に接合される部分
２８・・・外側面
２８ａ・・・外側面のうち被取付け部材に接合される部分
２９・・・連設部
３２・・・凹部
３４・・・接合凹部前
３４ａ・・・底面
３４ｂ・・・内側面[0001]
BACKGROUND OF THE INVENTION
The present invention has a mounting member having a mounting surface that decreases in diameter toward one side in the axial direction, and has an opposing end surface at one end in the axial direction facing at least the outer peripheral portion to the mounting surface and an outer surface having a circular cross section. a mounting member having, on diffusion bonding how to pressure the the mating member side in a heated state of the first contacts are allowed while the members of the joint portion of the facing end surface and said outer surface the mounting surface.
[0002]
[Prior art]
Diffusion bonding structures by such a method are already known, for example, from JP-A-7-103070, JP-A-7-189628, JP-A-9-122924, and the like. A structure and method are disclosed in which a valve seat as an attachment member made of a material different from that of the cylinder head is diffusion bonded to the cylinder head as a member.
[0003]
[Problems to be solved by the invention]
However, in the conventional diffusion bonding method , since the outer surface of the attachment member before joining the portion to be attached to the attached member has a cross-sectional shape composed of a combination of straight lines, the straight portion is sufficient. Since sufficient plastic flow does not occur, sufficient joint strength cannot be obtained. This is because the tip portion that first contacts the mounted member when the mounting member is pressed to the mounted member side is formed at an acute angle, so that sufficient plastic flow occurs in this portion, and the diffusion bonding layer is sufficiently formed. Although it is formed, the sliding speed of the plastic fluid and the amount of the plastic fluid are clearly reduced in the portion having a linear cross-sectional shape and continuing to the tip portion, compared with the tip portion. It is thought that this is because a new diffusion bonding layer is not formed.
[0004]
Further, the joining depth of the mounting member to the mounted member is the resistance value corresponding to the amount of the plastic fluid generated by the immersion of the mounting member into the mounted member, and the discharged plastic fluid is the mounted surface and the opposed end surface. It is determined by the balance between the sum of resistance values generated by interposing between them and the applied pressure, but the variation in resistance values due to the engagement is very large, and it is difficult to control the junction depth with high accuracy. there were.
[0005]
The present invention has been made in view of such circumstances, and increases the sliding speed of the plastic fluid generated between the mounting member and the mounted member at the time of diffusion bonding and the amount of the plastic fluid to obtain sufficient bonding strength. Another object of the present invention is to provide a diffusion bonding method capable of controlling the bonding depth with high accuracy by suppressing variation in resistance value due to the biting of the plastic fluid.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a mounting member having a mounting surface that decreases in diameter toward one side in the axial direction is provided with an opposing end surface that has at least an outer peripheral portion facing the mounting surface. a mounting member having an outer surface of circular cross section and having a direction end, pressurizes the connecting portion of the facing end surface and said outer surface the mating member side in a heated state of the two members while the first contact with a mounting surface in diffusion bonding how to pressure, prior to bonding to the mounting member of the mounting member, the rewritable form the connecting portion into a curved shape bulging the mounting member side, the mounting of the facing end surface and an outer surface while previously formed part which is bonded to a member in a curved shape with a larger radius of curvature than the coupling parts, wherein the target mounting surface of the mounting member, and an annular bottom surface that faces the outer peripheral portion of the facing end surface A joint recess that is formed from an outer peripheral edge of the bottom surface to the mounting member side and is formed with an inner surface facing the outer surface of the mounting member is provided, and when the mounting member is pressurized to the mounted member side, A first step of bringing the connecting portion into contact with the outer peripheral portion of the bottom surface, a second step of bringing the opposing end surface into contact with the bottom surface sequentially from the radially outer side, and the outer surface as an axis on the inner surface. The third step of sequentially raising the pressure resistance value by sequentially contacting from the inner side in the direction is characterized in that it is executed .
[0007]
According to such a configuration of the invention described in claim 1, the sliding speed of the plastic fluid generated between the mounting member and the mounted member and the amount of the plastic fluid are increased, and sufficient bonding strength is obtained by good diffusion bonding. Obtainable. That is, in the attachment member, the portion of the attachment portion to be attached to the attached member having a curved outer surface shape can increase the sliding speed of the plastic fluid with respect to the stroke as compared with a flat surface. Yes, the connecting part that first contacts the attached surface to the attached member when the attaching member is pressed to the attached member side is formed in a curved surface with a relatively small radius of curvature. The amount of the plastic fluid generated by the immersion of the mounted member can be increased, and the portion of the opposing end surface and the outer surface joined to the mounted member has a radius of curvature larger than that of the connecting portion. Since each is formed in a curved surface, the plastic fluid can be positively discharged by increasing the sliding speed of the plastic fluid. Then, in the first step when the mounting member is pressed to the mounted member side, the resistance value is increased in accordance with the plastic fluid generated by the continuous portion of the mounting member being immersed in the mounted member. In the second step, the resistance value gradually increases as the opposing end surfaces of the mounting members sequentially contact the bottom surfaces of the joint recesses from the radially outer side in the second step, and in the third step, the resistance is increased. In addition to the part and the opposed end surface, the outer surface of the attachment member is immersed in the inner surface of the joint recess, so that the resistance value rises greatly. By changing the resistance change characteristics for each step and setting the resistance value to rise significantly at the end of the joint immediately before the target joint depth, it is possible to accurately determine the timing to stop pressurization. Depth It is possible to improve the control accuracy.
[0008]
According to a second aspect of the present invention, in addition to the structure of the first aspect of the present invention, before the attachment of the attachment member to the attached member, the radius of the opposite end surface is larger than that of the portion joined to the attached member. An annular recess for receiving the plastic fluid discharged from the joint interface between the mounted surface and the opposed end surface is formed inward in the direction .
[0009]
According to such a configuration of the invention described in claim 2 , since the annular recess is formed radially inward from the portion of the opposing end face that is joined to the attached member, the opposing end face and the attached surface The plastic fluid discharged to the radially inward side from the gap can escape into the recess, and the pressure resistance value generated when the discharged plastic fluid is caught between the mounted surface and the opposed end surface It is possible to control the junction depth more accurately by minimizing the variation in the thickness.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.
[0011]
1 to 7 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a main part of a four-cycle engine, and FIG. 2 is a longitudinal section showing a state immediately before diffusion bonding of a valve seat material to a cylinder head. 3 is an enlarged view of the main part of FIG. 2, FIG. 4 is a cross-sectional view corresponding to FIG. 3 at the end of the diffusion bonding process, FIG. 5 is a cross-sectional view for sequentially explaining the diffusion bonding process, and FIG. FIG. 7 is a diagram for explaining the sliding speed of the fluid, and FIG.
[0012]
First, in FIG. 1, a piston (not shown) slidably fitted in a cylinder hole 12 provided in a cylinder block 11 of a four-cycle engine, and a cylinder head as a mounted member coupled to the cylinder block 11. A combustion chamber 14 is formed between the intake port 15 and the exhaust port 16, which can communicate with the combustion chamber 14.
[0013]
Valve seats 17 and 18 are joined to the cylinder head 13 at the open ends of the intake port 15 and the exhaust port 16 to the combustion chamber 14, and seat portions 19 a and 20 a that can be seated on the valve seats 17 and 18 are provided. Stem portions 19b and 20B of the intake valve 19 and the exhaust valve 20 provided are slidably fitted to guide cylinders 21 and 22 provided on the cylinder head 13, respectively. In addition, each of the stem portions 19b and 20b protrudes upward from the guide cylinders 21 and 22, and the intake valve 19 and the exhaust valve 20 are moved upward, that is, the seat between the upper ends of the stem portions 19b and 20b and the cylinder head 13. Springs 23 and 24 are provided to seat the portions 19a and 20a on the valve seats 17 and 18 and urge the intake ports 15 and the exhaust ports 16 in the closing direction. Further, a valve operating device (not shown) is connected to the upper ends of the stem portions 19b and 20b, and the intake valve 19 and the exhaust valve 20 are opened and closed by the valve operating device.
[0014]
By the way, the valve seats 17 and 18 are generally assembled to the cylinder head 13 by press-fitting. However, in recent engine layouts, the intake valve 19 and the exhaust valve 20 are arranged close to each other, and the conventional press-fitting is performed. In the equation, there is almost no degree of freedom in changing the layout around the combustion chamber 14 in order to achieve a larger valve diameter or to achieve a higher compression ratio. Therefore, when the valve seats 17 and 18 are directly joined to the cylinder head 13 instead of the press-fitting type, the valve seats 17 and 18 are thinned to greatly improve the degree of freedom of the layout, or via the valve seats 17 and 18. It is possible to reduce the temperatures of the intake and exhaust valves 19 and 20, the valve seats 17 and 18 and the combustion chamber 14 by improving the heat transfer performance of all the engines, and a great improvement in engine performance can be expected. . At this time, even if the valve seats 17 and 18 are made of a metal different from the cylinder head 13, sufficient bonding strength can be obtained by diffusion bonding.
[0015]
In FIG. 2, a valve seat material 25 as an attachment member is diffusion bonded to the cylinder head 13, and valve seats 17 and 18 are formed by machining the valve seat material 25 after the bonding.
[0016]
Thus, the cylinder head 13 is made of an aluminum alloy casting which is a lightweight and heat-transferable metal, and the valve seat material 25 is, for example, an iron-based sintered alloy having excellent wear resistance, -Cu-Be alloy etc. excellent in thermal conductivity are used.
[0017]
At the opening end of the intake and exhaust ports 15 and 16 of the cylinder head 13 on the combustion chamber 14 side, a mounting surface 26 having a smaller diameter is formed as the distance from the combustion chamber 14 increases along the axial direction. On the other hand, the valve seat material 25 is formed in a ring shape having an opposing end surface 27 that opposes the mounting surface 25 at one end in the axial direction and an outer surface 28 having a circular cross section.
[0018]
Valve seat material 25 by being pressurized with a constant pressure on the mounting surface 26 of the cylinder head 13 in a heated state of the valve seat material 25 and the cylinder head 13, is diffusion bonded to the mounting surface 26 . Thus, in the heated state, the valve seat material 25 and the cylinder head 13 are energized in a short time while the valve seat material 25 is in contact with the mounting surface 26 of the cylinder head 13, so that the valve seat material 25 and It is obtained when the contact surface of the cylinder head 13 generates heat by Joule heat generation.
[0019]
In FIG. 3, the valve seat material 25 is the one in which the connecting portion 29 of the opposed end surface 27 and the outer surface 28 is first brought into contact with the cylinder head 13 when the valve seat material 25 is pressurized to the cylinder head 13 side. The portion 27 a on the outer peripheral side of the opposed end surface 27 and the portion 28 a on the opposed end surface 27 side of the outer side surface 28 and the connecting portion 29 are diffusion bonded to the cylinder head 13.
[0020]
Thus, before the valve seat material 25 is joined to the cylinder head 13, the connecting portion 29 is formed in a curved shape swelled on the cylinder head 13 side with a radius of curvature R 1, and on the outer peripheral side of the opposing end face 27. The portion 27 a is formed in a curved surface swelled toward the cylinder head 13 with a radius of curvature R 2 larger than that of the continuous portion 29, and the portion 28 a on the opposite end surface 27 side of the outer surface 28 is also larger in radius of curvature than the continuous portion 29. It is formed in a curved shape that swells toward the cylinder head 13 at R3.
[0021]
Also, an annular recess 32 is formed radially inward of the opposed end surface 27 with respect to the portion 27a joined to the cylinder head 13, and the recess 32 has a mounting surface 26 and It is possible to receive the plastic fluid 33 discharged from the joint interface of the opposing end face 27.
[0022]
3, before joining the valve seat material 25 to the cylinder head 13, the mounting surface 26 of the cylinder head 13 has an annular bottom surface 34 a that faces the outer peripheral portion of the opposed end surface 27 of the valve seat material 25. And a joint recess 34 that is formed from an outer peripheral edge of the bottom surface 34 a toward the valve seat material 25 and an inner side surface 34 b that faces the outer surface 28 of the valve seat material 25.
[0023]
Moreover, the bottom surface 34a and the inner side surface 34b are arranged so that the connecting portion 29 is placed on the outer peripheral portion of the bottom surface 34a when the valve seat material 25 is pressurized toward the mounting surface 26 side, as shown in FIG. a first step of Ru in contact, as shown in FIG. 5 (b), a second step of Ru by sequentially contacting the radially outer side of the facing end surface 27 to the bottom surface 34a, in FIG. 5 (c) as shown, the third step of the outer surface 28 rise pressurization resistance by sequentially contacting the axially inner side to the inner side surface 34b is formed so that are executed sequentially.
[0024]
Next, the operation of this embodiment will be described. When the valve seat material 25 is pressurized toward the cylinder head 13 while the valve seat material 25 and the cylinder head 13 are heated, the contact surfaces of the valve seat material 25 and the cylinder head 13 are described. As shown in FIG. 4, slip deformation occurs in the valve seat material 25 and the cylinder head 13, and the oxide film, foreign matter and intermetallic compound are discharged from the joint interface as a plastic fluid 33 as shown in FIG. 4. Fine irregularities and interatomic vacancies at the interface disappear, and a contact surface that is extremely clean and free of atmospheric gas is formed. Moreover, free electrons in the metal are activated by contact between the clean surfaces in the heated state, and the intragranular and grain boundary diffusion of atoms occurs between the valve seat material 25 and the cylinder head 13, so that the valve seat material 25 becomes a cylinder. It is diffusion bonded to the head 13.
[0025]
By the way, in the valve seat material 25, the portion of the portion to be joined to the cylinder head 13 that is formed with a curved outer surface shape is a slip surface of the plastic fluid 33 with respect to the pressurization stroke as compared with a flat surface. It is possible to increase the speed. That is, the sliding distance L1 when the plastic fluid 33 slides on the curved surface shown in FIG. 6A is equal to the sliding distance L2 when sliding on the flat surface shown in FIG. 6B. In the valve seat material 25, the shape of the outer surface of the valve seat material 25 that is joined to the cylinder head 13 before being joined is a curved surface as compared to a flat surface. The sliding speed becomes large.
[0026]
However, since the connecting portion 29 that first comes into contact with the cylinder head 13 when the valve seat material 25 is pressurized to the cylinder head 13 side is formed with a relatively small curvature radius R1, the connecting portion 29 on the tip side thereof is provided. the amount of plastic flow animals 33 caused by immersion of the cylinder head 13 of the part 29 can be large, also the connecting portion 29 to the continuous portion 27a, so 28a are also formed in a curved surface, the plastic flow animals The sliding speed of 33 can be increased and the plastic fluid 33 can be positively discharged. Accordingly, the valve seat material 25 can be diffused and bonded satisfactorily to the cylinder head 13 to obtain a sufficient bonding strength.
[0027]
The joint depth of the valve seat material 25 to the cylinder head 13 is such that the resistance value corresponding to the amount of the plastic fluid 33 generated by the immersion of the valve seat material 25 into the cylinder head 13 and the discharged plastic fluid 33 are Although it is determined by the balance between the sum of the resistance values generated by the engagement between the mounted surface 26 and the opposed end surface 27 and the applied pressure, the variation in the resistance value due to the engagement is very large, and the variation is left as it is. As it is, it is difficult to control the junction depth with high accuracy.
[0028]
However, an annular recess 32 is formed radially inwardly of the opposed end surface 27 with respect to the portion joined to the cylinder head 13, and the plastic fluid 33 can be received in the recess 32. Accordingly, the plastic fluid 33 discharged inward from between the opposed end surface 27 and the mounted surface 26 can be released into the recess 32, and the discharged plastic fluid 33 is disposed between the mounted surface 26 and the opposed end surface 27. Therefore, it is possible to minimize the variation in the pressure resistance value caused by the biting into the gap and to control the junction depth more accurately.
[0029]
Further, before the valve seat material 25 is joined to the cylinder head 13, the mounting surface 26 of the cylinder head 13 includes an annular bottom surface 34a and an inner side surface 34b that rises from the outer peripheral edge of the bottom surface 34a toward the valve seat material 25. joining recess 34 is provided configured in the bottom surface 34a and inner surface 34b is in pressurized to the mounting surface 26 side of the valve seat material 25, said connecting portion 29 of the valve seat material 25 bottom 34a a first step of Ru into contact with the outer peripheral portion of a second step of the facing end surface 27 of the valve seat material 25 Ru by sequentially contacting the radially outward side of the bottom surface 34a, the outer surface 28 of the valve seat material 25 the are formed so that the execution and the third step of Ru by sequentially contacting the axially inner side are sequentially into the inner surface 34b, such a joining recess 34 , It is possible to further improve the control accuracy of the junction depth of the timing of stopping the pressure accurately determined.
[0030]
In FIG. 7, in the first step, the resistance value increases rapidly as the plastic fluid is generated by immersing the connecting portion 29 of the valve seat material 25 in the cylinder head 13. The opposing end surface 27 of the sheet material 25 sequentially contacts the bottom surface 34a of the bonding recess 34 from the radially outer side, so that the resistance value gradually increases. In the third step, the connecting portion 29 and the opposing end surface 27 are further increased. In addition, since the outer side surface 28 of the valve seat material 25 is immersed in the inner side surface 34b of the joint recess 34, the resistance value rises greatly. That is, when pressurizing the valve seat material 25 toward the cylinder head 13 with a constant pressure, the change characteristic of the resistance value is changed for each step, and the valve seat material 25 is changed in the final third step in which the resistance value rises greatly. By balancing the constant pressurizing force and the resistance value (reaction force against pressurization), the target joining depth can be obtained with high accuracy, and the control accuracy of the joining depth can be further improved.
[0031]
Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.
[0032]
For example, the present invention is not limited to the diffusion bonding structure of the valve seat material 25 to the cylinder head 13 but can be widely applied to the diffusion bonding structure of the mounting member to the mounted member.
[0033]
【The invention's effect】
As described above, according to the first aspect of the present invention, the sliding speed of the plastic fluid generated between the mounting member and the mounted member and the amount of the plastic fluid are increased, and sufficient bonding strength is obtained by good diffusion bonding. In addition , it is possible to accurately determine the timing of stopping the pressurization by setting the resistance value to rise greatly at the end of joining immediately before the target joining depth when the attaching member is pressed to the attached member side. This makes it possible to improve the control accuracy of the junction depth.
[0034]
According to the second aspect of the present invention, the variation in the pressurization resistance value that occurs when the discharged plastic fluid is caught between the mounted surface and the opposed end surface is minimized, and the joining depth is more accurately determined. It becomes possible to control.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an essential part of a 4-cycle engine.
FIG. 2 is a longitudinal sectional view showing a state immediately before diffusion bonding of a valve seat material to a cylinder head.
FIG. 3 is an enlarged view of a main part of FIG.
4 is a cross-sectional view corresponding to FIG. 3 at the end of the diffusion bonding process.
FIG. 5 is a cross-sectional view for sequentially explaining diffusion bonding processes.
FIG. 6 is a diagram for explaining a sliding speed of a plastic fluid.
FIG. 7 is a diagram showing a change in resistance value in a diffusion bonding process.
[Explanation of symbols]
13 ... Cylinder head 25 as attached member ... Valve seat material 26 as attaching member ... Installed surface 27 ... Opposing end surface 27a ... Joined to attached member among opposed end surfaces Portion 28 ... Outer surface 28a ... Outer surface portion to be joined to member 29 ... Continuous portion 32 ... Concave portion 34 ... Joining concave portion 34a ... Bottom surface 34b ...・ Inside

Claims

A mounted member (13) having a mounted surface (26) having a smaller diameter toward one side in the axial direction has an opposed end surface (27) at one end in the axial direction at least facing the outer surface of the mounted surface (26). first contacts the outer surface of the circular cross section of the mounting member (25) having (28), the connecting portion (29) of the facing end surface (27) and said outer surface (28) on the mounting surface (26) with in diffusion bonding how to pressure the the mating member (13) side in a heated state of the two members (13, 25) while,
Before bonding to the mating member (13) of the mounting member (25), wherein to form the connecting portion (29) to the mounting member (13) bulging side curved Rutotomoni, the opposing end faces (27) The portions (27a, 28a) to be joined to the member to be attached (13) of the outer surface (28) are formed in a curved surface having a radius of curvature larger than that of the connecting portion (29). On the mounting surface (26) of the mounting member (13), an annular bottom surface (34a) facing the outer peripheral portion of the opposed end surface (27), and from the outer peripheral edge of the bottom surface (34a) to the mounting member (25) side There is provided a joint recess (34) that is constituted by an inner surface (34b) that stands up and faces the outer surface (28) of the mounting member (25),
A first step of bringing the connecting portion (29) into contact with the outer peripheral portion of the bottom surface (34a) when the mounting member (25) is pressed toward the mounted member (13); 27) sequentially contacts the bottom surface (34a) from the radially outer side, and pressurizes the outer surface (28) sequentially contacts the inner surface (34b) from the axially inner side. A diffusion bonding method characterized by sequentially performing a third step of raising the resistance value.

The diffusion bonding method according to claim 1, wherein a portion (27a) to be bonded to the mounted member (13) of the opposing end surface (27) before the mounting member (25) is bonded to the mounted member (13). A diffusion bonding characterized by forming an annular recess (32) for receiving a plastic fluid discharged from the bonding interface between the mounted surface (26) and the opposed end surface (27) inwardly in the radial direction. Method.