JP2004130326A

JP2004130326A - Friction stirring and joining device and friction stirring and joining method

Info

Publication number: JP2004130326A
Application number: JP2002295359A
Authority: JP
Inventors: Yoshikuni Kato; 加藤　慶訓; Yasuyuki Fujitani; 藤谷　泰之; Nobumi Hiromoto; 広本　悦己
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 2002-10-08
Filing date: 2002-10-08
Publication date: 2004-04-30
Anticipated expiration: 2022-10-08
Also published as: JP4335513B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction stirring and joining device and a friction stirring and joining method in which a joining surface is copied with high accuracy by controlling the pressure by a hydraulic cylinder even with any distortion of a surface plate, defective setting, or distortion or unevenness of a work joining part. <P>SOLUTION: In the friction stirring and joining device in which a shoulder surface of a rotary tool to be pressed against and brought into contact with any one of at least face and back joining surfaces is movable in the Z-axis direction, and a fluid pressure urging means to control the pressure on the joining surface of the shoulder surface to be substantially constant by the fluid pressure is provided, the fluid pressure urging means is a hydraulic pressure urging path, and a feedback circuit is provided in the path via a relief valve. When the shoulder surface of the rotary tool is fluctuated in the Z-axis direction following the joining surface, the hydraulic pressure received by the rotary tool is controlled to be a predetermined value while releasing the hydraulic pressure by the feedback circuit, or the fluid pressure is the hydraulic pressure, and a hydraulic piston mechanism to urge the hydraulic pressure to the rotary tool applies the hydraulic pressure from both sides of a separating direction from the joining surface and an approaching direction thereto. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、摩擦攪拌接合装置とその接合方法に係り、特に車両、航空機、船舶、建物等の構造体を製造する際のシングルスキンやダブルスキンパネル（二面中空パネル）の接合に用いる摩擦攪拌接合装置とその製造方法に関する。
【０００２】
【従来の技術】
例えば特表平７−５０５０９０号公報（特許文献１）には、摩擦攪拌による固相接合方法として長尺材同士の新規な接合方法が開示されており、かかる接合方法は、加工物より実質的に硬い材質からなる回転ツ−ルを加工物の接合部に挿入し、回転ツ−ルを回転させながら移動することにより、回転ツ−ルと加工物との間に生じる摩擦熱による塑性流動によって加工物を接合する接合方法で、かかる摩擦接合法は、接合部材を固相状態で、回転ツ−ルを回転させながら移動させつつ軟化させた固相部分を一体化しながら接合できるために、熱歪みがなく接合方向に対して実質的に無限に長い長尺材でもその長手方向に連続的に固相接合できる利点がある。さらに、回転ツ−ルと接合部材との摩擦熱による金属の塑性流動を利用した固相接合のため、接合部を溶融させることなく接合できる。また、加熱温度が低いため、接合後の変形が少ない。さらには、接合部は溶融されないため、欠陥が少ないなどの多くの利点がある。
【０００３】
さらに、かかる摩擦接合を利用して、鉄道車両等の大型構造物に用いられる長尺のダブルスキンパネルからなる中空型材を複数平行に配設したものを突き合わせ接合して構成した摩擦撹拌接合による広幅の二面構造体（パネル）を形成する技術が特許第３１５２４２０号公報（特許文献２）に開示されている。
【０００４】
次に摩擦撹拌接合に使用される回転工具について説明する。摩擦撹拌接合は前記特許文献１に開示されているように、ブローブ型とボビンツール型の回転工具が存在し、プローブ型工具２０は図４（Ａ）に示すように、ショルダ部２１とこのショルダ部２１に備えられたプローブ２２とを備えており、このショルダ部２１は円形ショルダ面を有している。そして、複数の型材を突き合わせ、若しくは嵌合された状態の接合線表面より、前記回転工具２０を回転させて、プローブ２２を被加工物の接合線に設けた不図示の孔に侵入させるとともに、複数の型材の接合線上で摺接回転する円形ショルダ面によって被加工物に摩擦熱が付与されるとともに、プローブ２２周囲が塑性流動化し、この状態で回転工具２０を接合線に沿って移動させることにより、接合線周囲が塑性流動化しつつ接合線に沿って２つの素材が圧力を受けながら撹拌混練され、プローブの後方側に移行する。この結果塑性流動した素材は後方側で摩擦熱を失って急速に冷却固化するので両パネル板は素材同士が混じり合って完全に一体化した状態で接合される。
【０００５】
しかしながらかかる接合方法は円形ショルダ面によって被加工物に摩擦熱を均等に付与する必要があり、このため前記ワークを定盤（裏当て）に固定して平面化して接合を行っているが、ワークの歪みやの製作誤差による板厚変動や定盤へのセッティング誤差等によって上記の位置関係に誤差が生じ、これが原因で接合不良が発生したり、あるいは定盤面の局部的な変形はティーチングによっては吸収できず、これによっても上記の位置関係に誤差が生じ接合不良が発生してしまう。また従来の設備では、被接合部材をセットする定盤の平面度は高精度なものが必要となり、大型の被接合部材を接合するための装置は高価なものになる。特に鉄道車両の場合は、ワークスキンが最大２５ｍ程度になり、このような長尺のスキンの接合の場合に定盤のセッテング誤差やワークの歪みが顕著になり、補間作業やテイーチングに非常に手間がかかる。
【０００６】
かかる課題を解決するために、特許第３２６１４３１号（特許文献３）の発明が提供されている。かかる発明は、図５に示すように前記摩擦攪拌接合装置において、回転工具Ｔのショルダを被接合部材（ワーク）Ｐ表面に対して押圧、接触させるように付勢する付勢手段３４と、前記付勢力が略一定になるように制御する付勢力制御手段３６とを設けて成り、さらに前記付勢手段３４はエアシリンダであり、前記付勢力制御手段３６はエアシリンダ３４に供給する圧力を制御する２次圧一定形の減圧弁であることを特徴とし、エアシリンダ３４により回転工具Ｔのショルダを付勢力が略一定になるように前記被接合部材Ｐに対して押圧、接触させることにより、被接合部材Ｐの製作誤差による板厚変動、被接合部材Ｐの定盤４へのセッティング誤差、定盤４面の平面度不良、あるいは定盤４面の局部的な変形が存在しても、被接合部材Ｐと回転工具Ｔとの位置関係は略一定に保たれ、良好な接合を行うことが可能となる。そして更に、エアシリンダ３４を用いた効果としては、押圧力の変動が滑らかであって、油圧シリンダのように急激な変動を生じるものではないので、接合作業には好適である、と油圧シリンダを用いた場合を否定している。
しかしながらエアシリンダはその加圧力を空気という圧縮性流体を用いているために、大きな加圧力が得られず、例えば、ショルダ面の荷重が２００ｋｇｆ以上になるように制御しようとすると、油圧シリンダに比べてエアシリンダのシリンダ容積が大きくなるのみならず、エアシリンダで前記圧力を達成するのはなかなか困難であり、結果として良好な接合が出来ない。
【０００７】
また、特開２０００−３０１３６１号公報（特許文献４）における摩擦攪拌接合において、接合の開始部位から終了部位まで均等な接合品位が得られ、高い加工能率を達成できる発明として、摩擦攪拌接合ツールの先端部をワークＷの接合線に沿って埋入状態で回転しつつ相対的に進行させて、ワーク同士を接合一体化する摩擦攪拌接合方法において、接合ツールの回転数、接合速度、外からの加熱・冷却、接合ツールの加熱・冷却等により、ワークへの入熱量を略一定に制御する技術が開示されている。
【０００８】
さて前記のような片側より摩擦圧力を付勢するブローブ型の回転工具ではなく、図４（Ｂ）に示すように、ボビンツール１０と呼ばれる回転工具も提案されている。
かかる工具は接合する金属板の表裏両面を挟持するように一定間隔を設けた一対のショルダ１０Ａ、１０Ｂが設けられているとともに、該上下一対のショルダ１０Ａ、１０Ｂ間にプローブ１１が設けられているので、接合面の両面において摩擦発熱させることが出来、裏面側の接合不良が生じないのみならず、上下一対のショルダ１０Ａ、１０Ｂ間で互いの反力を受けているために、裏当金や前記した支柱が不要になるが、ブローブ１１により上下一対のショルダ１０Ａ、１０Ｂ間隔が固定されているために、被接合部材の変形や肉厚の変動があると、これを吸収することができず、円滑な摩擦攪拌接合ができない。
【０００９】
更に、ボビンツール１０を用いた際、ショルダ部１０Ａ、１０Ｂの間隔と接合部との間に空隙があると、接合部に圧力がかからないため、空洞的な欠陥が発生してしまう。ショルダ部の間隔と接合部の厚さが同一の場合には、接合部が接合部以外の厚さより薄くなる。このため、接合部の品質に問題が発生することがある。
【００１０】
又裏面押圧部材と表面押圧部材を備え、該押圧部間が可変のボビンツールを用いた摩擦攪拌接合装置は公知であり、例えば特開２０００−３３４８４（特許文献５）において、コイルスプリングを用いて下面押圧部を軸方向に可変にした技術が存在する。
【００１１】
しかしかかる従来技術においても、下面押圧部として機能する攪拌ピンの回転は、ストッパ部とコイルスプリングを介して下面押圧部に伝えられるものであるために、コイルスプリングの押し付け力によってその荷重が規定され、下面押圧部の押し付け力を制御できない。しかもコイルスプリングの押し付け力には上限があり、基本的に上面押圧部として機能する回転筒の押し付け力より大きくすることができない。
【００１２】
【特許文献１】
特表平７−５０５０９０号公報
【特許文献２】
特許第３１５２４２０号公報
【特許文献３】
特許第３２６１４３１号号公報
【特許文献４】
特開２０００−３０１３６１号公報
【特許文献５】
特開２０００−３３４８４号公報
【発明が解決しようとする課題】
【００１３】
本発明はかかる従来技術の課題に鑑み、高品質な接合を高能率に行うことが可能な摩擦撹拌接合装置とその接合方法を提供することを目的とする。
また本発明の他の目的は、油圧シリンダで加圧力制御することで定盤の歪みやセッテング不良、若しくはワーク接合部の歪みや凹凸があっても精度よくこれを倣うことが出来る摩擦撹拌接合装置とその接合方法を提供することを目的とする。
また本発明の他の目的は、片面押圧型のブローブ型回転工具を用いて摩擦攪拌接合を行う場合に、工具経路でのＺ方向（ワーク離接方向、図２参照）の位置を補間せずに、Ｚ座標一定で走査しても油圧シリンダにより精度よくワークを倣うことの出来る摩擦撹拌接合装置とその接合方法を提供することを目的とする。
また本発明の他の目的は回転工具にホビンツールを用いた場合に、精度よくワークを倣う事ができ、表裏両面側での入熱量を調整でき、これにより母材をボビンツールを用いて摩擦攪拌接合する際に該摩擦攪拌接合の柔軟性と円滑化をはかることのできる摩擦撹拌接合装置とその接合方法を提供することを目的とする。更に又本発明は、摩擦攪拌接合により入熱過剰あるいは入熱不足により接合品質が損なわれるために、それに応じて回転数や速度を制御することにより、信頼性の高い摩擦撹拌接合装置を提供することを目的とする。
【００１４】
【課題を解決するための手段】
本第一発明は、回転工具にブローブ型の接合部材の片面側より摩擦入熱を行う装置のみならず、ホビンツールを用いた接合部材の両面側より摩擦入熱を行う装置にも適用されるもので、接合面の少なくとも表裏いずれかの一面に対して押圧、接触される回転工具ショルダ面が、接合面に対し離接する方向（以下Ｚ軸という）に移動可能に構成するとともに、流体圧により上記ショルダ面の接合面への押圧力が略一定になるように制御する流体圧付勢手段を設けてなる摩擦攪拌接合装置において、上記流体圧付勢手段が油圧付勢経路であり、該経路中にリリーフ弁を介してフィードバック回路を設け、回転工具ショルダ面が、接合面に追従してＺ軸方向に変動した際に、前記フィードバック回路により前記回転工具が受圧する油圧を逃がしながら一定圧に制御可能に構成したことを特徴とする。
【００１５】
尚、本発明は、フィードバック回路を設けなくても、請求項２記載の発明のように、上記流体圧が油圧であり、前記回転工具に油圧を付勢する油圧ピストン機構が、接合面に対し離間する方向と、接近する方向の上下両面より油圧力を重圧するように構成してもよい。
【００１６】
かかる発明によれば、回転工具が接合面や定盤の凹凸に対応して上下に変位してもこれに対応して油圧ピストンの上下の圧力バランスをとることにより、請求項１記載の発明と同様な効果を得ることが出来る。
【００１７】
請求項３記載の発明は、裏面押圧部と表面押圧部を備え、該押圧部間が可変のボビンツールを用いた摩擦攪拌接合装置において、
前記裏面押圧部よりの接合面への押圧力と前記表面押圧部よりの接合面への押圧力とを夫々独立して調整可能に構成するとともに、前記押圧力付勢手段が、流体圧であることを特徴とする。
【００１８】
かかる発明によれば、例えば接合されるスキンパネルの自由端側の面板の厚みをその自由端より該パネルのリブを介して自由端内側に位置する中空部の面板厚みより他の自由端の面板厚みを大に設定するとともに、該ダブルスキンパネルの自由端同士を突き合わせ、その突き合わせ面において、表裏両面側にショルダ面より摩擦熱が入熱されるボビンツールにより、裏面側押圧力を表面側押圧力より大に押圧力を調整してしながら摩擦攪拌接合がなされるようにして接合させることにより接合部の突き合わせ部にギャップ（隙間）が生じていても、パネル自由端の裏面側が先に摩擦熱による入熱により軟化し裏面側の余肉部が接合ギャップ空間に進入するため、外部から見える表面側は凹部が発生することなく、平坦を維持できる。この結果、接合後における表面加工処理が基本的に不要であり、特に車両構造体のような長尺のものについては、その作業が大幅に簡単化する。
【００１９】
そしてこの場合表面側凹部の発生を防ぐために、前記裏面押圧部の押圧力を前記表面押圧部の押圧力より大にするとともに、該裏面側押圧力付勢手段が、油圧であるのが好ましいことは前記したとおりである。
一方表面側は、前記表面押圧部の押圧力を前記裏面押圧部の押圧力より小にして倣いを優先するとともに、倣いの場合に空圧であることにより位置変動に対し、なめらかに追従でき、好ましい。
【００２０】
尚、本発明は、油圧や空圧に限定されることなく、水圧や他のガス圧を利用してもよく、従って前記裏面押圧部の押圧力と前記表面押圧部の押圧力とを夫々異なる流体種類による流体圧で構成し、例えば相対的に大なる押圧部の押圧力付勢手段が、油圧であるのが前提であるが、相対的に小なる押圧部の押圧力付勢手段は、油圧若しくは空圧を用いて構成してもよい。
【００２１】
請求項８記載の発明は、前記装置発明を思想として具現化したもので、母材接合部を挟んでその表面側と裏面側より夫々押圧部を介して押圧力を加えてその接合部への摩擦入熱により接合を行う摩擦攪拌接合方法において、前記表面側と裏面側に夫々設けた押圧部が、母材接合部に倣う方向に移動可能に構成するとともに、前記裏面側押圧部の接合面への押圧力と前記表面側押圧部の接合面への押圧力とを夫々独立して流体圧により制御して接合を行うことを特徴とする。
そして前記相対的に大なる一の押圧部の押圧力付勢は、夫々の押圧部を回転させた後に行なわれるのがよい。回転前に２００ｋｇｆを超える押圧力を付勢することにより、モータロックが生じてしまう。
そして本発明の思想を実現するには、相対的に大なる押圧部の押圧力付勢が、塑性流動可能な温度域に達する摩擦入熱であり、相対的に小なる押圧部の押圧力付勢が、接合部に沿う倣いに必要な押圧力である必要がある。
【００２２】
さて、前記したように特許文献４における摩擦攪拌接合には、接合の開始部位から終了部位まで均等な接合品位が得られ、高い加工能率を達成できる発明として、摩擦攪拌接合ツールの先端部をワークＷの接合線に沿って埋入状態で回転しつつ相対的に進行させて、ワーク同士を接合一体化する摩擦攪拌接合方法において、接合ツールの回転数、接合速度、外からの加熱・冷却、接合ツールの加熱・冷却等により、ワークへの入熱量を略一定に制御する技術が開示されている。
しかしながらかかる技術はホビンツールに関するものではなく、その結果裏面押圧部と表面押圧部を間を可変にした場合の課題を何ら示唆していない。
【００２３】
そこで請求項１１記載の発明は、裏面押圧部と表面押圧部を備え、該押圧部間が可変のボビンツールを用いた摩擦攪拌接合装置において、
前記裏面押圧部よりの接合面への押圧力と前記表面押圧部よりの接合面への押圧力とを夫々独立して調整可能に構成するとともに、前記裏面押圧部と表面押圧部からなる回転工具の周囲の温度を検知する手段を設け、該検知温度に基づいて前記裏面押圧部、前記表面押圧部の内の少なくとも１の押圧力付勢力を制御する付勢力制御手段を設けたことを特徴とする。
この場合に裏面押圧部は入熱、表面押圧部は倣いの役割を有しているために、単純な制御を行う場合は前記検知温度に基づいて前記表面押圧部の押圧力付勢力を制御する付勢力制御手段を設ければよい。
更に前記検知温度に基づいて前記裏面押圧部、前記表面押圧部の内の少なくとも１の押圧力付勢力とともに回転速度を制御する押圧部制御手段を設けてもよい。
【００２４】
かかる発明によれば、接合運転開始前には、ホビンツールの周囲の接合位置からはずれたワークＰ表面温度を計測し、基準温度より低い（高い）場合は、裏面押圧部（必要に応じて表面押圧部）の付勢力を大きく（小さく）するか、若しくは回転工具の回転速度を大きく（低く）するか若しくは工具の送り速度を小さく（大きく）するか若しくはこの３つの組み合わせを制御テーブルを用いて制御することにより接合運転の基準温度への移行の際の時間的若しくは温度的バラツキを小さくできる。
【００２５】
運転開始後の運転中には、ホビンツールの後ろ側のワークＰ接合直後の接合部（後述する図６に示すＰ_１）温度を計測し、ワークＰ接合直後の接合部温度が基準接合温度より低い（高い）場合は、裏面押圧部（必要に応じて表面押圧部）の付勢力を大きく（小さく）するか、若しくは回転工具の回転速度を大きく（低く）するか若しくは工具の送り速度を小さく（大きく）するか若しくはこの３つの組み合わせを制御テーブルを用いて制御することにより接合運転中の温度的バラツキを小さくできる。
【００２６】
【発明の実施の形態】
以下、本発明を図に示した実施例を用いて詳細に説明する。但し、この実施例に記載される構成部品の寸法、形状、その相対配置などは特に特定的な記載がない限り、この発明の範囲をそれのみに限定する趣旨ではなく単なる説明例に過ぎない。
【００２７】
図１及び図２はプローブを用いた本発明の第１実施例にかかる摩擦攪拌接合装置の具体的構成を示し、図２においてワーク上面に取り付け固定し、Ｘ軸方向に移動する定盤４と、Ｘ軸と直行するＹ軸方向に延在する水平スライドフレーム３Ａを有する門型枠３と、該門型枠３のスライドフレーム３Ａに沿ってＹ軸方向に移動可能な主軸支持枠５と、該主軸支持枠５に垂直移動機構６を介してＺ軸方向に移動可能に取り付けられた主軸１と主軸の先端に取り付けられたブローブ型回転工具取り付け装置３０よりなる。
【００２８】
図１に戻り、主軸１は主軸枠１Ｂの中心軸線上にベアリング３１によって回転自在に支持されており、前記主軸はモータによって回転駆動されている。
回転工具取り付け装置３０は、主軸１のテーパ穴に嵌着され、一体として回転駆動する回転筒３３と、前記回転筒３３を、その内周部で上下一対のベアリング２２、２３によって回転可能に支持させるとともに、前記主軸枠１Ｂにボルトによって固定されている支持筒枠３５からなる。
この支持筒枠３５には油圧ポンプ３７、油圧通路４５、リリーフ（逃がし）弁３９、減圧弁４１、切替弁４３、からなる油圧一定制御の油圧経路４０が接続され、支持筒枠３５内に設けた油圧通路４７、シール５６されたリングバッファ４９及び回転筒３３の油圧通路５１を介して、回転筒３３中心軸線上に設けた油圧シリンダ５３に開口している。
油圧シリンダ５３にはメタルシール５５により上下に摺動自在に支持された油圧ピストン５７が嵌入されており、該油圧ピストン５７の先端に同軸上にブローブ型回転工具２０が連接されている。
ブローブ型回転工具２０と油圧ピストン５７の間は、段差状に縮径された移動規制部５９が設けられており、該移動規制部５９は回転筒３３下端面よりリング円先端Ｌ字状に垂下されたリング円筒部５４により移動規制されて係止されている。
【００２９】
かかる摩擦攪拌接合装置によれば、垂直移動機構６を介してＺ軸方向に主軸１を移動させて回転工具の２０のショルダ面を定盤４に固定させたワークＰ表面に当接させた状態で、主軸１を回転駆動させた後、油圧ポンプ３７を駆動させてリリーフ弁３９により一定圧に制御された油圧を油圧シリンダ５３に導入することにより、回転筒３３、油圧ピストン５７及びこれに連接する回転工具２０が回転しながら、リング円筒部５４によりゾーン移動規制された状態でワーク表面に摩擦熱の入熱を開始する。
即ち、アルミニウム合金の例えばシングルスキンの接合部に上記回転工具２０のピンを回転させながら挿入すると共に、上記ショルダを上記接合部表面に接触させながら上記回転工具２０を移動させることにより、摩擦熱を利用した接合を行う。このとき回転工具２０は上記油圧シリンダ５３によって、前記油圧付勢力はショルダ面の荷重が２００ｋｇｆ以上になるように略一定の付勢力でもってシングルスキンの接合部表面に押圧制御している。
【００３０】
本発明の有利性を確認するために、前記付勢力に空気圧を用いた場合と、油圧を用いた場合の違いについて説明する。
先ず空気圧の場合に、高圧ガス取締法に該当しない９．９ｋｇ／ｃｍ以下の圧力で、エアシリンダに空気圧を付勢して、工具ショルダ面の荷重が２００ｋｇｆ以上になるように制御するには、エアシリンダ内径をショルダ外径に比較して相当大きくしなければならないが、本発明のように油圧ピストン／シリンダを用いた油圧シリンダでは、油圧を数十〜２００ｋｇ／ｃｍに設定することは容易であり、シリンダ内径を小さくでき、結果的には装置全体を小径化できる。
【００３１】
又、空気圧の場合に回転工具のショルダ面と被接合部材の表面との位置変動に追従してエアシリンダ容積が変動した場合に、エアは圧縮性流体であるために、これに追従してエア圧も変動して工具ショルダ面の荷重が変動するが、本発明は非圧縮性の油圧であり、且つリリーフ弁によるフィードバック回路を設けることにより、回転工具のショルダ面と接合部表面との間のＺ軸方向の位置変動が生じても、言い換えれば油圧シリンダ容積が変動した場合に、リリーフ弁によりフィードバック回路を利用して油圧を油圧ポンプ側に戻すことにより、油圧力を一定に維持できる為に、工具ショルダ面の荷重を一定に維持できる。
更に本発明では、油圧回路にフィードバック回路を設けることにより、油圧を一定に維持しながら前記回転工具は前記移動規制部の範囲内においてワークと回転工具との位置関係を変化させることが出来、言い換えれば、定盤や被接合部材に歪みや高さ変動が生じていてもあるいは、定盤面の局部的な変形が存在しても回転工具が接合部材から受ける反力は一定となるように倣いながら押圧、接触させる事ができ、これにより良好な接合品質が得られる。
【００３２】
特に接合線が上下方向に大きく湾曲しているような継手において、移動規制部の範囲をその最大値以上に設定することにより、回転工具の押圧、付勢力を一定に維持しながら、接合ツールＴは自動的に上記湾曲形状を倣いながら、接合作業を行うことになるのである。
即ち、前記した従来技術においては、油圧シリンダの場合に前記シリンダ容積の変動により急激な圧力変動を生じると記載しているが、本実施例では、リリーフ弁による油圧回路のフィードバックにより圧力の一定化が達成される。しかもエアシリンダの場合は、その押圧力の変動が滑らかであっても、確実に変動が生じ摩擦接合の品質に悪影響を及ぼすのは必至である。そして前記従来技術においては大幅なエア圧の変動が予想されるような場合には、上記減圧弁の前位にさらに別の２次圧一定形減圧弁を介設しておくのが好ましいと記載しているが、減圧弁を複数直列にしても圧力変動をさけるのは不可能である。
【００３３】
図３は、ボビンツール１０を用いた本発明の他の実施例で、表面側ショルダ１０Ａは、ワーク表面を倣うごとく小なる反力（荷重）を付与する第１の油圧ピストン／シリンダ６０に連結されており、一方、裏面側ショルダ１０Ｂは、表面側ショルダ１０ＡにワークＰを挟み裏面側より摩擦力を発生するために大なる反力（荷重）を付与する第２の油圧ピストン／シリンダ６２に連結されており、そしてこれらのボビンツール１０は内部に組み込まれたモータ７２により回転駆動される。
より具体的に説明するに、図中１は加工機主軸で、前記実施例と異なり回転はしない。５１は前記主軸下面に取り付けられた接合機本体で、前記加工主軸１下面に取り付けられた円筒形状の支持外枠６４と、前記支持外枠６４の上部中心軸上にとりつけられた第１の油圧ピストン／シリンダ６０と、前記油圧ピストンに連結された上下動可能な支持軸により吊下された支持内筒６６と、前記支持内筒６６上部に内蔵された第２の油圧ピストン／シリンダ６２と、前記第２の油圧ピストン／シリンダ６２下方の支持筒内部に組み込まれたホビンツール取り付け体７０よりなり、ホビンツール取付体７０周囲にはモータ７２が環装されており、支持内筒６６に対し、ホビンツール取付体７０が回転自在に配設されている。
【００３４】
ホビンツール取付体７０は、第１の油圧ピストン／シリンダ６０の付勢変位を支持内筒６６と一体的に受圧しＺ軸方向に移動変位可能に、フランジ７１を介して回転自在に支持内筒６６内に支持されている表面ショルダ取付体８０と、表面ショルダ１０Ａ内を貫通し、ピン軸１０Ｃを介して先端に裏面ショルダ１０Ｂが取り付けられている裏面ショルダ取付軸７８とからなり、裏面ショルダ取付軸７８と第２の油圧ピストン／シリンダ６２のピストン軸６２Ｂとはベアリング軸受７３を介して連結され、モータ７２による取付軸７８の回転と無関係に支持内筒６６に上下動自在に支持されたピストン軸６２Ｂを介して第２の油圧ピストン／シリンダ６２の付勢力を受圧可能に構成されている。
又裏面側ショルダ取付軸７８と表ショルダ取付体８０の嵌合部分はスプライン８２状に構成し、スプライン８２を介して裏面側ショルダ取付軸７８がピストン軸６２Ｂに摺動自在に連結され、これにより表面側ショルダ取付体８０側のモータ７２と同期して回転可能に構成されている。
【００３５】
又支持内筒６６下側外周と支持外枠６４下側内周との対面位置には、段差状に縮径された移動規制範囲において支持内筒６６が上下移動可能なようにリング状係合凹部８８とリング状係合凸部８９が設けられており、又本実施例の油圧ピストン／シリンダ６０、６２は、前記実施例と異なりピストン６１の上下両側に油圧６３Ａ、６３Ｂが導入されてその圧力バランスにより、ピストン軸６１Ａが上下動するように構成している。これにより倣い及び摩擦押圧力の制御の容易化を図っている。
【００３６】
かかる摩擦攪拌接合装置によれば、ボビンツール１０（裏面ショルダと表面ショルダ）によりワークＰを挟持させた状態で、先ずモータ７２により表面ショルダ取付体８０とこれにスプライン連結している裏面ショルダ取付軸７８とを回転させた後、支持内筒６６を吊下し、ピストン軸６１Ａ及び支持内筒６６を介して表ショルダ１０Ａ側に付勢される第１の油圧ピストン／シリンダ６０では、ワークＰ接合面の表面にかかる表面ショルダ１０Ａ面の荷重が１０ｋｇｆになるように、不図示の油圧ポンプを駆動させる。
又同時に支持内筒６６に内蔵され、ピストン軸６２Ｂ及び裏面ショルダ取付軸７８を介して裏面ショルダ１０Ｂ側に付勢される第２の油圧ピストン／シリンダ６２では、ワークＰ接合面の裏面にかかる裏面側ショルダ１０Ｂの荷重が２００ｋｇｆ以上になるように、不図示の油圧ポンプを駆動させる。
この際、前記ボビンツール１０を回転自在に支持している接合機本体９は、支持内筒６６外周側のリング状係合凹部８８と支持外枠６４内周側のリング状係合凸部８９との間で移動規制された範囲で上下動動に支持している。
【００３７】
このように裏面側ショルダ１０Ｂの荷重が２００ｋｇｆになるように制御し、前記表面側ショルダ１０Ａ面にかかる荷重を裏面側ショルダ１０Ｂにかかる荷重より大幅に小にしている理由は次の通りである。
例えば接合部材がスキンパネルの場合に、接合部の継ぎ手構造が突き合わせになっているために、その接合部にギャップ（隙間）が生じるが、パネル自由端の裏面側（中空部側）の板厚を厚くするとともに、表裏両面側にショルダ面より摩擦熱が入熱されるボビンツール１０を用い、裏面側ショルダ１０Ｂにかかる荷重を大幅に大にして摩擦攪拌接合がなされることで、継ぎ手部でショルダ面との摩擦熱による入熱により裏面側の軟化した部分が接合ギャップ空間に進入するため外部から見える表面側は凹部が発生することなく、平坦を維持でき、しかも接合後における表面加工処理が基本的に不要であり、特に車両構造体のような長尺のものについては、その作業が大幅に簡単化する。
【００３８】
そしてこのような構成を円滑に達成するには、裏面側ショルダ１０Ｂにかかる荷重より大幅にしながら摩擦攪拌接合を行うことにより、表面側より裏面側が前記ギャップに軟化した裏面側が進入することが好ましい。
【００３９】
尚、本発明では、裏面側ショルダ１０Ｂと表面側ショルダ１０Ａをスプライン８２により連結して同期回転させているが、両者を独立して回転制御可能に構成してもよい。
【００４０】
かかる実施例によれば、表面側ショルダ１０Ａにおいては、ワークＰ表面の倣いが主な作用であるために、エアシリンダの利点が有効に生かせる。即ち接合線が上下方向に大きく湾曲しているような継手においてもエアシリンダはその押圧力の変動が滑らかであって、油圧シリンダより倣いの追従性がよい。
一方円滑な摩擦入熱により、大きな押圧力を必要とする裏面ショルダ１０Ｂの場合は油圧ピストン／シリンダを用いることがよいことは前記したとおりである。
【００４１】
図６は、図３の摩擦攪拌接合装置の制御装置を示し、（Ａ）は正面概略図、（Ｂ）は平面概略図で、図中１０Ａのワーク表面側ショルダは、ワークＰ表面を倣うごとく小なる反力（荷重）を付与する第１の油圧ピストン／シリンダ６０（図３参照）に連結されており、一方、１０Ｂの裏面側ショルダ１０Ｂは、ピン軸１０Ｃを介して表面側ショルダ１０ＡにワークＰを挟み裏面側より摩擦力を発生するために大なる反力（荷重）を付与する第２の油圧ピストン／シリンダ６２に連結されており、そしてこれらのボビンツール１０は内部に組み込まれたモータ７２により回転駆動されることは前記したとおりである。
【００４２】
図６に戻り、Ｓは、非接触式の温度計（商品名：パイロメータ）で、ボビンツールの移動に沿って移動し、該ホビンツールの左右両側と図６（Ｂ）に示すその後方の３つの位置の温度値Ｓ_１、Ｓ_２、Ｓ_３を計測する。
そして接合運転開始前には、ホビンツール１０の左右両側の温度値Ｓ_１、Ｓ_２よりワークＰ表面温度を計測し、基準温度より低い（高い）場合は、制御装置ＣＬにより、第２の油圧ピストン／シリンダ６２を介して矢印Ａ、Ｂに示すようにショルダ１０Ｂの付勢力を大きく（小さく）するか、矢印Ｃに示すモータ７２の回転速度を大きく（低く）するか若しくは矢印Ｄに示す工具の送り速度を小さく（大きく）するか若しくはこの３つの組み合わせを制御装置ＣＬ内の制御テーブル（不図示）を用いて制御する。
【００４３】
運転開始後には、ホビンツール１０の後ろ側の温度値Ｓ_３よりワークＰ接合直後の接合部Ｐ_１温度を計測し、ワークＰ接合直後の接合部Ｐ_１温度が基準接合温度より低い（高い）場合は、制御装置ＣＬにより第２の油圧ピストン／シリンダ６２を介して裏面側ショルダ１０Ｂの付勢力を大きく（小さく）するか、モータ７２の回転速度を大きく（低く）するか若しくは工具の送り速度を小さく（大きく）するか若しくはこの３つの組み合わせを制御装置ＣＬ内の制御テーブル（不図示）を用いて制御する。
【００４４】
【発明の効果】
以上記載のごとく本発明によれば、高品質な接合を高能率に行うことが可能な摩擦撹拌接合装置とその接合方法を提供出来る。
また本発明によれば、油圧シリンダで加圧力制御することで定盤の歪みやセッテング不良、若しくはワーク接合部の歪みや凹凸があっても精度よくこれを倣うことが出来る。
また本発明によれば、片面押圧型のブローブ型回転工具を用いて摩擦攪拌接合を行う場合に、工具経路でのＺ方向（ワーク離接方向）の位置を補間せずに、Ｚ座標一定で走査しても油圧シリンダにより精度よくワークを倣うことが出来る。
また本発明は回転工具にホビンツールを用いた場合に、表裏両面側での押圧力を調整でき、これにより母材をボビンツールを用いて摩擦攪拌接合する際に該摩擦攪拌接合の柔軟性と円滑化をはかることができる。
【００４５】
又本発明によれば、摩擦攪拌接合により入熱過剰あるいは入熱不足により接合品質が損なわれるために、それに応じて回転数や速度を制御することにより、信頼性の高い摩擦撹拌接合装置を得ることが出来る。
【図面の簡単な説明】
【図１】本発明の実施例に係る摩擦攪拌接合装置の第１例を示す加工主軸側の詳細構成図である。
【図２】図１の実施例の全体概略図である。
【図３】本発明の実施例に係るボビンツールを用いて表裏両面側の押し付け力を独立して制御可能に構成した摩擦攪拌接合装置の第２例を示す全体概略図である。
【図４】従来技術に係る摩擦撹拌接合のプローブツールとボビンツールの基本構成図である。
【図５】従来技術に係る摩擦撹拌接合装置を示す断面概略図である。
【図６】図３の摩擦攪拌接合装置の制御装置を示し、（Ａ）は正面概略図、（Ｂ）は平面概略図である。
【符号の説明】
１　主軸
１０　ボビンツール
１０Ａ表面側ショルダ
１０Ｂ裏面側ショルダ
２０　ブローブ型回転工具
３０　回転工具取り付け装置
３６　付勢力制御手段
３７　油圧ポンプ
３９　リリーフ（逃がし）弁
４０　油圧経路
４１　減圧弁
４３　切替弁
５１　接合機本体
５３　油圧シリンダ
５７　油圧ピストン
６０　第１の油圧ピストン／シリンダ
６２　第２の油圧ピストン／シリンダ
６６　支持内筒
７０　ホビンツール取付体
７２　モータ
７８　裏面ショルダ取付軸
８０　表面ショルダ取付体
Ｓ　　温度計
ＣＬ　制御装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a friction stir welding apparatus and a joining method thereof, and particularly to friction stir welding used for joining a single-skin or double-skin panel (double-sided hollow panel) when manufacturing a structure such as a vehicle, an aircraft, a ship, or a building. The present invention relates to a joining device and a manufacturing method thereof.
[0002]
[Prior art]
For example, Japanese Patent Application Publication No. 7-505090 (Patent Document 1) discloses a novel joining method of long materials as a solid-state joining method by friction stirring, and such a joining method is substantially more effective than a workpiece. By inserting a rotating tool made of a hard material into the joint of the workpiece and moving it while rotating it, plastic flow due to frictional heat generated between the rotating tool and the workpiece The friction joining method is a joining method for joining workpieces. In the friction joining method, since the joining member can be joined while moving the rotating tool while rotating the rotating tool in a solid state while joining the softened solid portion integrally, There is an advantage that even a long material having no distortion and substantially infinitely long in the joining direction can be solid-phase joined continuously in the longitudinal direction. Furthermore, since solid-state welding is performed using plastic flow of metal due to frictional heat between the rotary tool and the joining member, joining can be performed without melting the joining portion. Further, since the heating temperature is low, deformation after bonding is small. Furthermore, since the joint is not melted, there are many advantages such as fewer defects.
[0003]
Furthermore, using such friction welding, a wide width is formed by friction stir welding in which a plurality of hollow mold members formed of long double skin panels used for large structures such as railway vehicles are arranged and joined in parallel. A technique for forming a two-sided structure (panel) is disclosed in Japanese Patent No. 3152420 (Patent Document 2).
[0004]
Next, a rotary tool used for friction stir welding will be described. As disclosed in Patent Document 1, the friction stir welding includes a probe type rotary tool and a bobbin tool type rotary tool, and a probe type tool 20 includes a shoulder 21 and a shoulder 21 as shown in FIG. And a probe 22 provided in the portion 21. The shoulder portion 21 has a circular shoulder surface. Then, the rotary tool 20 is rotated from the joint line surface in a state where a plurality of mold members are butted or fitted together, and the probe 22 is caused to enter a hole (not shown) provided in the joint line of the workpiece, The frictional heat is applied to the workpiece by the circular shoulder surface that slides and rotates on the joining line of the plurality of mold members, and the area around the probe 22 plastically fluidizes. In this state, the rotary tool 20 is moved along the joining line. As a result, the two materials are stirred and kneaded while receiving pressure along the joint line while the area around the joint line is plastically fluidized, and moved to the rear side of the probe. As a result, the plastically flowed material loses frictional heat on the rear side and rapidly cools and solidifies, so that both panel plates are joined together in a state where the materials are mixed together and are completely integrated.
[0005]
However, in such a joining method, it is necessary to uniformly apply frictional heat to the workpiece by the circular shoulder surface. Therefore, the work is fixed to a surface plate (backing) to be flattened and joined. The positional relationship described above may cause errors in the above positional relationship due to plate thickness fluctuations due to distortion or manufacturing errors, or setting errors to the surface plate, etc., which may cause poor bonding or local deformation of the surface of the surface plate depending on teaching. It cannot be absorbed, and this also causes an error in the above positional relationship, resulting in poor bonding. Further, in the conventional equipment, the platen on which the members to be joined are set needs to have a high degree of flatness, and an apparatus for joining large members to be joined is expensive. In particular, in the case of railway vehicles, the work skin is about 25 m at the maximum, and in the case of joining such a long skin, the setting error of the surface plate and the distortion of the work become remarkable, and it takes much time for interpolation work and teaching. It takes.
[0006]
In order to solve such a problem, the invention of Japanese Patent No. 3261431 (Patent Document 3) is provided. According to the invention, as shown in FIG. 5, in the friction stir welding apparatus, the urging means 34 for urging the shoulder of the rotary tool T to press and contact the surface of the workpiece (work) P, Biasing force control means 36 for controlling the biasing force to be substantially constant; and the biasing means 34 is an air cylinder, and the biasing force control means 36 controls the pressure supplied to the air cylinder 34. The pressure reducing valve is of a constant secondary pressure type, and the air cylinder 34 presses and contacts the shoulder of the rotary tool T against the member P so that the biasing force is substantially constant. Even if there is a thickness variation due to a manufacturing error of the member to be joined P, an error in setting the member to be joined P to the surface plate 4, a poor flatness of the surface of the surface plate 4, or a local deformation of the surface of the surface plate 4, With the member to be joined P Translocation relationship between the tool T is kept substantially constant, it is possible to perform a good bonding. Further, as an effect of using the air cylinder 34, the variation in the pressing force is smooth, and does not cause a sudden variation unlike the hydraulic cylinder. The case where it is used is denied.
However, since the air cylinder uses a compressive fluid called air, a large pressure cannot be obtained.For example, when controlling the load on the shoulder surface to be 200 kgf or more, compared to the hydraulic cylinder, As a result, not only the cylinder capacity of the air cylinder becomes large, but also it is very difficult to achieve the above pressure with the air cylinder, and as a result, good joining cannot be achieved.
[0007]
Further, in friction stir welding in Japanese Patent Application Laid-Open No. 2000-301361 (Patent Document 4), a friction stir welding tool is an invention which can obtain a uniform joining quality from a start portion to an end portion of welding and achieve high processing efficiency. In the friction stir welding method in which the tip portion is relatively advanced while rotating in the embedded state along the joining line of the workpiece W to join and integrate the workpieces, in the friction stir welding method, the rotational speed of the welding tool, the welding speed, and the There is disclosed a technique for controlling the amount of heat input to a work to be substantially constant by heating / cooling, heating / cooling of a joining tool, and the like.
[0008]
As shown in FIG. 4B, a rotary tool called a bobbin tool 10 has been proposed, instead of a probe-type rotary tool for urging frictional pressure from one side as described above.
In such a tool, a pair of shoulders 10A and 10B are provided at regular intervals so as to sandwich both front and back surfaces of a metal plate to be joined, and a probe 11 is provided between the pair of upper and lower shoulders 10A and 10B. Therefore, it is possible to generate frictional heat on both sides of the joining surface, and not only does not cause poor joining on the back side, but also because the pair of upper and lower shoulders 10A and 10B receive mutual reaction force, Although the above-mentioned support is unnecessary, since the distance between the pair of upper and lower shoulders 10A and 10B is fixed by the probe 11, if the deformation or the thickness of the member to be bonded is changed, it cannot be absorbed. And smooth friction stir welding cannot be performed.
[0009]
Furthermore, when the bobbin tool 10 is used, if there is a gap between the gap between the shoulder portions 10A and 10B and the joining portion, no pressure is applied to the joining portion, so that a hollow defect occurs. When the distance between the shoulders and the thickness of the joint are the same, the joint becomes thinner than the thickness other than the joint. For this reason, a problem may occur in the quality of the joint.
[0010]
A friction stir welding apparatus using a bobbin tool that includes a back surface pressing member and a front surface pressing member and has a variable distance between the pressing portions is known. For example, in Japanese Patent Application Laid-Open No. 2000-33484 (Patent Document 5), a coiled spring is used. There is a technique in which the lower surface pressing portion is made variable in the axial direction.
[0011]
However, even in such a conventional technique, the rotation of the stirring pin functioning as the lower surface pressing portion is transmitted to the lower surface pressing portion via the stopper portion and the coil spring, so that the load is defined by the pressing force of the coil spring. However, the pressing force of the lower surface pressing portion cannot be controlled. In addition, there is an upper limit on the pressing force of the coil spring, and the pressing force cannot be made larger than the pressing force of the rotary cylinder that basically functions as the upper surface pressing portion.
[0012]
[Patent Document 1]
Japanese Patent Publication No. 7-5050590
[Patent Document 2]
Japanese Patent No. 3152420
[Patent Document 3]
Japanese Patent No. 3261431
[Patent Document 4]
JP 2000-301361 A
[Patent Document 5]
JP-A-2000-33484
[Problems to be solved by the invention]
[0013]
An object of the present invention is to provide a friction stir welding apparatus and a welding method capable of performing high-quality welding with high efficiency in view of the problems of the related art.
Another object of the present invention is to provide a friction stir welding apparatus that can accurately follow the distortion of a surface plate, a defective setting, or the distortion or unevenness of a work joint by controlling the pressure with a hydraulic cylinder. And a joining method thereof.
Another object of the present invention is to perform a friction stir welding using a single-sided pressing type probe-type rotary tool without interpolating the position in the Z direction (work separation / contact direction, see FIG. 2) on the tool path. Another object of the present invention is to provide a friction stir welding apparatus that can accurately follow a workpiece by a hydraulic cylinder even when scanning is performed with a constant Z coordinate, and a welding method thereof.
Another object of the present invention is that when a hobbin tool is used as a rotary tool, a workpiece can be copied with high accuracy, and the amount of heat input on both front and back sides can be adjusted, thereby frictionally stirring a base material using a bobbin tool. An object of the present invention is to provide a friction stir welding apparatus and a joining method thereof capable of measuring the flexibility and smoothness of the friction stir welding during welding. Furthermore, the present invention provides a highly reliable friction stir welding apparatus by controlling the number of revolutions and speed in accordance with the fact that the welding quality is impaired due to excessive heat input or insufficient heat input due to friction stir welding. The purpose is to:
[0014]
[Means for Solving the Problems]
The first invention is applied not only to a device for performing frictional heat input from one side of a probe-type joining member to a rotary tool, but also to a device for performing frictional heat input from both sides of a joining member using a hobbin tool. The rotary tool shoulder surface pressed and contacted against at least one of the front and back surfaces of the joining surface is configured to be movable in a direction (hereinafter, referred to as Z axis) separating from and coming into contact with the joining surface. In a friction stir welding apparatus provided with fluid pressure urging means for controlling the pressing force of the shoulder surface to the joint surface to be substantially constant, the fluid pressure urging means is a hydraulic urging path, and A feedback circuit is provided through a relief valve to release the hydraulic pressure received by the rotary tool by the feedback circuit when the rotary tool shoulder surface fluctuates in the Z-axis direction following the joint surface. Characterized by being capable of controlling at a constant pressure.
[0015]
In the present invention, even if a feedback circuit is not provided, as in the invention according to claim 2, the fluid pressure is a hydraulic pressure, and a hydraulic piston mechanism for urging the rotary tool with a hydraulic pressure is provided on a joint surface. The hydraulic pressure may be applied to both the upper and lower surfaces in the separating direction and the approaching direction.
[0016]
According to this invention, even if the rotary tool is displaced up and down in accordance with the unevenness of the joining surface and the surface plate, the pressure in the up and down direction of the hydraulic piston is balanced in accordance with the displacement. Similar effects can be obtained.
[0017]
According to a third aspect of the present invention, there is provided a friction stir welding apparatus using a bobbin tool that includes a back surface pressing portion and a front surface pressing portion, and the distance between the pressing portions is variable.
The pressing force on the bonding surface from the back surface pressing portion and the pressing force on the bonding surface from the front surface pressing portion are configured to be independently adjustable, and the pressing force urging means is a fluid pressure. It is characterized by the following.
[0018]
According to this invention, for example, the thickness of the face plate on the free end side of the skin panel to be joined is different from the thickness of the face plate of the hollow portion located on the inner side of the free end from the free end via the rib of the panel. The thickness of the double skin panel is set to be large, and the free ends of the double skin panel are abutted against each other. Even if there is a gap (gap) in the butted portion of the joining portion by performing friction stir welding while adjusting the pressing force to a greater extent, the back side of the free end of the panel is frictional heat first. As a result, the excess portion on the back side enters the bonding gap space, so that the front side seen from the outside can be kept flat without generating a concave portion. As a result, surface processing after joining is basically unnecessary, and the work is particularly simplified for a long object such as a vehicle structure.
[0019]
In this case, in order to prevent the generation of the front surface side concave portion, it is preferable that the pressing force of the back surface pressing portion is larger than the pressing force of the front surface pressing portion, and the back surface pressing force urging means is hydraulic. Is as described above.
On the other hand, the front surface side can prioritize copying by setting the pressing force of the front surface pressing portion smaller than the pressing force of the back surface pressing portion, and can smoothly follow a position change by being pneumatic in the case of copying, preferable.
[0020]
The present invention is not limited to hydraulic pressure and pneumatic pressure, and may use water pressure or another gas pressure. Therefore, the pressing force of the back surface pressing portion and the pressing force of the front surface pressing portion are different from each other. It is configured on the basis of the fluid pressure according to the type of fluid, for example, it is premised that the pressing force urging means of the relatively large pressing part is hydraulic, but the pressing force urging means of the relatively small pressing part is, You may comprise using hydraulic or pneumatic.
[0021]
The invention according to claim 8 is embodied as an idea of the device invention, and applies a pressing force from the front side and the back side via the pressing portion to the joining portion by sandwiching the base material joining portion. In the friction stir welding method of performing welding by frictional heat input, the pressing portions provided on the front surface side and the rear surface side are configured to be movable in a direction following the base metal bonding portion, and the bonding surface of the rear surface side pressing portion is provided. And the pressing force on the bonding surface of the front side pressing portion is independently controlled by fluid pressure to perform the bonding.
Further, it is preferable that the pressing force of the relatively large one pressing portion is performed after each pressing portion is rotated. By applying a pressing force exceeding 200 kgf before rotation, a motor lock occurs.
In order to realize the idea of the present invention, the pressing force of the relatively large pressing portion is a frictional heat input that reaches a temperature range where plastic flow is possible, and the pressing force of the relatively small pressing portion is relatively small. The force needs to be the pressing force required to follow the joint.
[0022]
By the way, as described above, in the friction stir welding in Patent Document 4, as an invention capable of obtaining a uniform joining quality from the start part to the end part of the welding and achieving high processing efficiency, the tip of the friction stir welding tool is used as a work. In the friction stir welding method in which the workpieces are relatively advanced while rotating in an embedded state along the joining line of W to join and integrate the workpieces, the number of rotations of the joining tool, the joining speed, external heating / cooling, There is disclosed a technique for controlling the amount of heat input to a work to be substantially constant by heating / cooling a joining tool or the like.
However, this technique does not relate to a hobbin tool, and as a result, does not suggest any problem when the distance between the back surface pressing portion and the front surface pressing portion is made variable.
[0023]
Therefore, an invention according to claim 11 is a friction stir welding apparatus using a bobbin tool that includes a back surface pressing portion and a front surface pressing portion, and the distance between the pressing portions is variable.
A rotating tool including the back surface pressing portion and the front surface pressing portion, wherein the pressing force on the bonding surface from the back surface pressing portion and the pressing force on the bonding surface from the front surface pressing portion can be independently adjusted. Means for detecting the temperature of the surroundings, and the back surface pressing portion, based on the detected temperature, biasing force control means for controlling at least one pressing force biasing force of the front surface pressing portion is provided. I do.
In this case, since the back surface pressing portion has the role of inputting heat and the front surface pressing portion has the role of copying, when performing simple control, the pressing force of the front surface pressing portion is controlled based on the detected temperature. What is necessary is just to provide an urging force control means.
Further, a pressing unit control means for controlling a rotation speed together with at least one pressing force urging force of the back surface pressing unit and the front surface pressing unit based on the detected temperature may be provided.
[0024]
According to this invention, before the start of the joining operation, the surface temperature of the workpiece P deviated from the joining position around the hobbin tool is measured, and if the temperature is lower (higher) than the reference temperature, the back surface pressing portion (the surface pressing if necessary) Control using a control table to increase (small) the urging force of the part), to increase (lower) the rotational speed of the rotary tool, or to decrease (increase) the feed speed of the tool. By doing so, it is possible to reduce temporal or temperature variations at the time of shifting the joining operation to the reference temperature.
[0025]
During the operation after the start of the operation, a joining portion immediately after joining of the workpiece P behind the hobbin tool (P shown in FIG. ₁ ) When the temperature is measured and the joining temperature immediately after the workpiece P joining is lower (higher) than the reference joining temperature, the urging force of the back surface pressing portion (the front surface pressing portion as necessary) is increased (smaller), or The temperature variation during the joining operation can be reduced by increasing (lowering) the rotation speed of the rotary tool, decreasing (increase) the feed speed of the tool, or controlling the combination of the three using a control table.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail using embodiments shown in the drawings. However, unless otherwise specified, the dimensions, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples.
[0027]
FIGS. 1 and 2 show a specific configuration of a friction stir welding apparatus according to a first embodiment of the present invention using a probe. In FIG. 2, a surface plate 4 attached and fixed to the upper surface of a work and moving in the X-axis direction is shown. A portal frame 3 having a horizontal slide frame 3A extending in the Y-axis direction perpendicular to the X-axis; a main shaft support frame 5 movable in the Y-axis direction along the slide frame 3A of the portal frame 3; It comprises a main spindle 1 mounted on the main spindle support frame 5 via a vertical moving mechanism 6 so as to be movable in the Z-axis direction, and a probe type rotary tool mounting device 30 mounted on the tip of the main spindle.
[0028]
Returning to FIG. 1, the main shaft 1 is rotatably supported by a bearing 31 on the center axis of the main shaft frame 1B, and the main shaft is rotationally driven by a motor.
The rotary tool mounting device 30 is fitted in a tapered hole of the main shaft 1 and rotatably supports the rotary cylinder 33 by a pair of upper and lower bearings 22 and 23 at its inner peripheral portion. And a support cylinder frame 35 fixed to the spindle frame 1B with bolts.
The support cylinder frame 35 is connected to a hydraulic path 40 for constant hydraulic control including a hydraulic pump 37, a hydraulic passage 45, a relief (relief) valve 39, a pressure reducing valve 41, and a switching valve 43, and is provided in the support cylinder frame 35. Through the hydraulic passage 47, the ring buffer 49 in which the seal 56 is sealed, and the hydraulic passage 51 of the rotary cylinder 33, the hydraulic cylinder 53 opens on the hydraulic cylinder 53 provided on the central axis of the rotary cylinder 33.
A hydraulic piston 57 slidably supported up and down by a metal seal 55 is fitted into the hydraulic cylinder 53, and the probe type rotary tool 20 is connected coaxially to the tip of the hydraulic piston 57.
Between the probe-type rotary tool 20 and the hydraulic piston 57, there is provided a movement restricting portion 59 whose diameter is reduced in a step-like manner. The movement is restricted by the ring cylindrical portion 54 and is locked.
[0029]
According to such a friction stir welding apparatus, the main shaft 1 is moved in the Z-axis direction via the vertical movement mechanism 6 so that the shoulder surface of the rotary tool 20 is brought into contact with the surface of the work P fixed to the surface plate 4. After the main shaft 1 is rotationally driven, the hydraulic pump 37 is driven to introduce a hydraulic pressure controlled to a constant pressure by the relief valve 39 to the hydraulic cylinder 53, thereby connecting the rotary cylinder 33, the hydraulic piston 57, and the hydraulic cylinder 53 to the hydraulic cylinder 53. While the rotating rotary tool 20 is rotating, frictional heat input to the work surface is started in a state where the zone movement is restricted by the ring cylindrical portion 54.
That is, frictional heat is generated by rotating the pin of the rotary tool 20 while rotating the pin of the rotary tool 20 in a single-skin joint of an aluminum alloy, and moving the rotary tool 20 while the shoulder is in contact with the surface of the joint. Perform the joining using. At this time, the rotary cylinder 20 is controlled by the hydraulic cylinder 53 to press the hydraulic urging force against the surface of the single-skin joint with a substantially constant urging force so that the load on the shoulder surface becomes 200 kgf or more.
[0030]
In order to confirm the advantages of the present invention, a difference between a case where air pressure is used as the urging force and a case where hydraulic pressure is used will be described.
First, in the case of air pressure, in order to control the load on the tool shoulder surface to be 200 kgf or more by applying air pressure to the air cylinder at a pressure of 9.9 kg / cm or less which does not correspond to the high pressure gas control method, Although the inner diameter of the air cylinder must be considerably larger than the outer diameter of the shoulder, in a hydraulic cylinder using a hydraulic piston / cylinder as in the present invention, it is easy to set the hydraulic pressure to several tens to 200 kg / cm. Yes, the inner diameter of the cylinder can be reduced, and as a result, the diameter of the entire apparatus can be reduced.
[0031]
Also, in the case of air pressure, if the volume of the air cylinder fluctuates following the position fluctuation between the shoulder surface of the rotary tool and the surface of the member to be joined, since the air is a compressible fluid, the air follows. Although the pressure also fluctuates and the load on the tool shoulder surface fluctuates, the present invention is an incompressible hydraulic pressure, and by providing a feedback circuit with a relief valve, the rotation between the shoulder surface of the rotary tool and the joint surface can be reduced. Even if the position in the Z-axis direction fluctuates, in other words, if the hydraulic cylinder volume fluctuates, the hydraulic pressure can be kept constant by returning the hydraulic pressure to the hydraulic pump side using a feedback circuit by a relief valve. In addition, the load on the tool shoulder surface can be kept constant.
Furthermore, in the present invention, by providing a feedback circuit in the hydraulic circuit, the rotary tool can change the positional relationship between the workpiece and the rotary tool within the range of the movement restricting portion while maintaining the oil pressure constant. For example, even if there is distortion or height fluctuation in the surface plate or the member to be joined, or even if there is local deformation of the surface of the surface plate, the rotating tool receives a constant reaction force from the joining member while following It can be pressed and contacted, thereby obtaining good bonding quality.
[0032]
In particular, in a joint in which the joining line is greatly curved in the vertical direction, by setting the range of the movement restricting portion to be equal to or more than the maximum value, the joining tool T Automatically performs the joining operation while following the curved shape.
That is, in the prior art described above, it is described that a sudden pressure change occurs due to a change in the cylinder volume in the case of a hydraulic cylinder, but in the present embodiment, the pressure is stabilized by feedback of a hydraulic circuit by a relief valve. Is achieved. In addition, in the case of an air cylinder, even if the pressing force fluctuates smoothly, it is inevitable that the fluctuation will occur and adversely affect the quality of frictional joining. In the prior art described above, when a large change in air pressure is expected, it is preferable to provide another secondary pressure reducing valve in front of the pressure reducing valve. However, even if a plurality of pressure reducing valves are connected in series, it is impossible to avoid pressure fluctuation.
[0033]
FIG. 3 shows another embodiment of the present invention using the bobbin tool 10, in which the surface side shoulder 10A is connected to a first hydraulic piston / cylinder 60 which applies a small reaction force (load) so as to follow the work surface. On the other hand, the back side shoulder 10B has a second hydraulic piston / cylinder 62 that applies a large reaction force (load) to the front side shoulder 10A to sandwich the work P and generate a frictional force from the back side. The bobbin tools 10 are connected, and are rotatably driven by a motor 72 incorporated therein.
More specifically, in the figure, reference numeral 1 denotes a processing machine main shaft, which does not rotate unlike the above embodiment. Reference numeral 51 denotes a joining machine main body attached to the lower surface of the spindle, a cylindrical supporting outer frame 64 attached to the lower surface of the processing spindle 1, and a first hydraulic pressure mounted on an upper central axis of the supporting outer frame 64. A piston / cylinder 60, a support inner cylinder 66 suspended by a vertically movable support shaft connected to the hydraulic piston, and a second hydraulic piston / cylinder 62 built in the upper part of the support inner cylinder 66; A hobbin tool mounting body 70 is installed inside the support cylinder below the second hydraulic piston / cylinder 62, and a motor 72 is mounted around the hobbin tool mounting body 70. A body 70 is rotatably disposed.
[0034]
The hobbin tool mounting body 70 receives the urging displacement of the first hydraulic piston / cylinder 60 integrally with the supporting inner cylinder 66 and is rotatable via the flange 71 so as to be movable and displaceable in the Z-axis direction. And a back shoulder mounting shaft 78 which penetrates through the inside of the front shoulder 10A and has a back shoulder 10B mounted at the tip via a pin shaft 10C. The piston shaft 78 is connected to the piston shaft 62B of the second hydraulic piston / cylinder 62 via a bearing bearing 73, and is supported by the support inner cylinder 66 so as to be vertically movable independently of the rotation of the mounting shaft 78 by the motor 72. The urging force of the second hydraulic piston / cylinder 62 can be received via 62B.
Further, a fitting portion between the back side shoulder mounting shaft 78 and the front shoulder mounting body 80 is formed in a spline 82 shape, and the back side shoulder mounting shaft 78 is slidably connected to the piston shaft 62B via the spline 82. It is configured to be rotatable in synchronization with the motor 72 on the front side shoulder mounting body 80 side.
[0035]
A ring-shaped engagement is provided at a position facing the lower outer periphery of the support inner cylinder 66 and the lower inner periphery of the support outer frame 64 so that the support inner cylinder 66 can move up and down in a movement restriction range reduced in a step-like shape. A concave portion 88 and a ring-shaped engaging convex portion 89 are provided, and the hydraulic piston / cylinders 60, 62 of this embodiment are different from the previous embodiment in that hydraulic pressures 63A, 63B are introduced on the upper and lower sides of the piston 61, respectively. The configuration is such that the piston shaft 61A moves up and down due to the pressure balance. This facilitates the control of the copying and the friction pressing force.
[0036]
According to such a friction stir welding apparatus, the work 72 is first held by the bobbin tool 10 (the back shoulder and the front shoulder), and then the front shoulder mounting body 80 and the back shoulder mounting shaft spline-connected to the front shoulder mounting body 80 by the motor 72. 78, the support inner cylinder 66 is suspended, and the first hydraulic piston / cylinder 60 urged toward the front shoulder 10A via the piston shaft 61A and the support inner cylinder 66 causes the workpiece P joining. The hydraulic pump (not shown) is driven so that the load on the surface shoulder 10A applied to the surface of the surface becomes 10 kgf.
At the same time, the second hydraulic piston / cylinder 62 built in the support inner cylinder 66 and urged toward the back shoulder 10B via the piston shaft 62B and the back shoulder mounting shaft 78 has a back surface on the back surface of the work P joint surface. The hydraulic pump (not shown) is driven so that the load on the side shoulder 10B becomes 200 kgf or more.
At this time, the joining machine main body 9 rotatably supporting the bobbin tool 10 includes a ring-shaped engaging concave portion 88 on the outer peripheral side of the support inner cylinder 66 and a ring-shaped engaging convex portion 89 on the inner peripheral side of the support outer frame 64. It supports up and down movement within the range where movement is restricted between and.
[0037]
The reason that the load on the back side shoulder 10B is controlled to be 200 kgf and the load on the front side shoulder 10A is made much smaller than the load on the back side shoulder 10B is as follows.
For example, when the joining member is a skin panel, a gap (gap) occurs at the joining portion because the joint structure of the joining portion is abutted, but the thickness of the back surface side (hollow portion side) of the panel free end. The friction stir welding is performed by using the bobbin tool 10 in which frictional heat is input from the shoulder surfaces on both front and rear sides, and the load applied to the rear shoulder 10B is greatly increased to perform friction stir welding. The softened part on the back side enters the joining gap space due to the heat input due to frictional heat with the surface, so that the front side visible from the outside can be maintained flat without forming recesses, and surface processing after joining is fundamental In particular, the operation of a long object such as a vehicle structure is greatly simplified.
[0038]
In order to smoothly achieve such a configuration, it is preferable that the friction stir welding be performed while applying a load greater than the load applied to the backside shoulder 10B so that the backside softened into the gap from the frontside into the gap.
[0039]
In the present invention, the back side shoulder 10B and the front side shoulder 10A are connected by the spline 82 and are rotated synchronously. However, both may be configured to be independently controllable in rotation.
[0040]
According to this embodiment, in the shoulder 10A on the front surface side, since the copying of the surface of the work P is the main operation, the advantages of the air cylinder can be effectively utilized. That is, even in a joint in which the joining line is largely curved in the vertical direction, the air cylinder has a smooth variation in the pressing force, and the air cylinder has better followability than the hydraulic cylinder.
On the other hand, as described above, it is preferable to use a hydraulic piston / cylinder in the case of the back shoulder 10B requiring a large pressing force due to smooth frictional heat input.
[0041]
6A and 6B show a control device of the friction stir welding apparatus of FIG. 3, wherein FIG. 6A is a schematic front view, and FIG. 6B is a schematic plan view. In FIG. It is connected to a first hydraulic piston / cylinder 60 (see FIG. 3) for applying a small reaction force (load), while the back surface shoulder 10B of 10B is connected to the front surface shoulder 10A via a pin shaft 10C. The bobbin tool 10 is connected to a second hydraulic piston / cylinder 62 that applies a large reaction force (load) to generate a frictional force from the back side with the work P interposed therebetween, and these bobbin tools 10 are incorporated therein. The rotation by the motor 72 is as described above.
[0042]
Returning to FIG. 6, S is a non-contact type thermometer (trade name: pyrometer), which moves along with the movement of the bobbin tool. Temperature value S at position ₁ , S ₂ , S ₃ Is measured.
Before the start of the joining operation, the temperature values S on the left and right sides of the hobbin tool 10 are set. ₁ , S ₂ The surface temperature of the workpiece P is measured more, and when the temperature is lower (higher) than the reference temperature, the urging force of the shoulder 10B is increased by the control device CL via the second hydraulic piston / cylinder 62 as shown by arrows A and B. The control in the control device CL is performed to reduce (increase), increase (decrease) the rotation speed of the motor 72 indicated by the arrow C, or decrease (increase) the feed speed of the tool indicated by the arrow D. Control is performed using a table (not shown).
[0043]
After the start of operation, the temperature value S on the rear side of the ₃ Joint P immediately after joining work P ₁ Measure the temperature and check the joint P immediately after the workpiece P is joined. ₁ When the temperature is lower (higher) than the reference joining temperature, the control device CL increases (reduces) the urging force of the back side shoulder 10B via the second hydraulic piston / cylinder 62 or increases the rotation speed of the motor 72. Either (lower) or lower (higher) the feed speed of the tool, or a combination of the three is controlled using a control table (not shown) in the control device CL.
[0044]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a friction stir welding apparatus and a welding method capable of performing high quality welding with high efficiency.
Further, according to the present invention, by controlling the pressing force by the hydraulic cylinder, even if there is a distortion of the surface plate or a defective setting, or a distortion or unevenness of the work joining portion, it can be accurately copied.
Further, according to the present invention, when friction stir welding is performed using a single-sided pressing type probe-type rotary tool, the Z-coordinate is fixed at a constant Z-coordinate without interpolating a position in a Z-direction (work separation / contact direction) on a tool path. Even when scanning, the work can be accurately copied by the hydraulic cylinder.
Further, according to the present invention, when a hobbin tool is used as a rotary tool, the pressing force on both the front and back surfaces can be adjusted, whereby the flexibility and smoothness of the friction stir welding when the base material is friction stir welded using the bobbin tool. Can be measured.
[0045]
Also, according to the present invention, since the welding quality is impaired due to excessive heat input or insufficient heat input due to friction stir welding, a highly reliable friction stir welding device is obtained by controlling the rotation speed and speed accordingly. I can do it.
[Brief description of the drawings]
FIG. 1 is a detailed configuration diagram of a working spindle side showing a first example of a friction stir welding apparatus according to an embodiment of the present invention.
FIG. 2 is an overall schematic diagram of the embodiment of FIG.
FIG. 3 is an overall schematic diagram showing a second example of a friction stir welding apparatus configured to be able to independently control pressing forces on both front and back sides using a bobbin tool according to an embodiment of the present invention.
FIG. 4 is a basic configuration diagram of a friction stir welding probe tool and a bobbin tool according to the related art.
FIG. 5 is a schematic sectional view showing a friction stir welding apparatus according to the related art.
6 shows a control device of the friction stir welding apparatus of FIG. 3, wherein (A) is a schematic front view and (B) is a schematic plan view.
[Explanation of symbols]
1 spindle
10 bobbin tools
10A surface side shoulder
10B back side shoulder
20 Brobe type rotary tool
30 Rotary tool mounting device
36 biasing force control means
37 Hydraulic pump
39 Relief valve
40 Hydraulic path
41 Pressure reducing valve
43 Switching valve
51 welding machine
53 Hydraulic cylinder
57 Hydraulic piston
60 first hydraulic piston / cylinder
62 second hydraulic piston / cylinder
66 Support inner cylinder
70 Hobbin tool mounting body
72 motor
78 Back shoulder mounting shaft
80 Surface shoulder mount
S thermometer
CL controller

Claims

A rotary tool shoulder surface pressed and contacted with at least one of the front and back surfaces of the joining surface is configured to be movable in a direction (hereinafter, referred to as a Z-axis) separating from and coming into contact with the joining surface, and the shoulder surface is formed by fluid pressure. In a friction stir welding apparatus provided with a fluid pressure biasing means for controlling the pressing force on the joining surface of the is substantially constant,
The fluid pressure urging means is a hydraulic urging path, and a feedback circuit is provided in the path via a relief valve. When the rotating tool shoulder surface fluctuates in the Z-axis direction following the joint surface, A friction stir welding apparatus wherein a feedback pressure circuit is configured to control the pressure to be constant while releasing the hydraulic pressure received by the rotary tool.

A rotary tool shoulder surface pressed and contacted with at least one of the front and back surfaces of the joining surface is configured to be movable in a direction (hereinafter, referred to as a Z-axis) separating from and coming into contact with the joining surface, and the shoulder surface is formed by fluid pressure. In a friction stir welding apparatus provided with a fluid pressure biasing means for controlling the pressing force on the joining surface of the is substantially constant,
The fluid pressure is a hydraulic pressure, and a hydraulic piston mechanism for urging the rotary tool to apply a hydraulic pressure is configured to apply a hydraulic pressure to both the upper and lower surfaces in a direction away from the joining surface and an approaching direction. A friction stir welding apparatus.

In a friction stir welding apparatus using a bobbin tool having a back pressing part and a front pressing part, and the pressing part is variable,
The pressing force on the bonding surface from the back surface pressing portion and the pressing force on the bonding surface from the front surface pressing portion are configured to be independently adjustable, and the pressing force urging means is a fluid pressure. A friction stir welding apparatus characterized by the above-mentioned.

The friction stir welding apparatus according to claim 3,
A friction stir welding apparatus, wherein the pressing force of the back surface pressing portion is made larger than the pressing force of the front surface pressing portion, and the back surface pressing force urging means is hydraulic.

The friction stir welding apparatus according to claim 3,
A friction stir welding apparatus, wherein the pressing force of the front surface pressing portion is smaller than the pressing force of the rear surface pressing portion, and the front surface pressing force urging means is pneumatic or hydraulic.

The friction stir welding apparatus according to claim 3,
A friction stir welding apparatus, wherein the pressing force of the back surface pressing portion and the pressing force of the front surface pressing portion are configured by fluid pressures of different fluid types.

7. The friction stirrer according to claim 6, wherein the pressing force urging means of the relatively large pressing portion is hydraulic, and the pressing force urging device of the relatively small pressing portion is pneumatic. Joining equipment.

In a friction stir welding method in which welding is performed by applying frictional heat to the joint by applying a pressing force via a pressing portion from the front side and the back side across the base metal joint,
The pressing portions provided on the front surface side and the back surface side are configured to be movable in a direction following the base material bonding portion, and the pressing force on the bonding surface of the back side pressing portion and the bonding surface of the front side pressing portion are provided. A friction stir welding method, wherein the welding is performed by independently controlling the pressing force of the fluid and the fluid pressure.

The friction stir welding method according to claim 8,
A friction stir welding method, wherein the pressing force of the relatively large pressing portion is performed after rotating each pressing portion.

The friction stir welding method according to claim 8,
The relatively large pressing force of the pressing portion is frictional heat input that reaches a temperature range in which plastic flow is possible, and the relatively small pressing force of the pressing portion is necessary for copying along the joint. A friction stir welding method characterized by a pressing force.

In a friction stir welding apparatus using a bobbin tool having a back pressing part and a front pressing part, and the pressing part is variable,
A rotating tool including the back surface pressing portion and the front surface pressing portion, wherein the pressing force on the bonding surface from the back surface pressing portion and the pressing force on the bonding surface from the front surface pressing portion can be independently adjusted. Means for detecting the temperature of the surroundings, and the back surface pressing portion, based on the detected temperature, biasing force control means for controlling at least one pressing force biasing force of the front surface pressing portion is provided. Friction stir welding equipment.

The friction stir welding apparatus according to claim 3, comprising a back surface pressing portion and a front surface pressing portion, wherein the pressing portion uses a variable bobbin tool.
A friction stir welding apparatus comprising: means for detecting the temperature around the rotary tool; and urging force control means for controlling the urging force of the back surface pressing portion based on the detected temperature.

The friction stir welding apparatus according to claim 3, comprising a back surface pressing portion and a front surface pressing portion, wherein the pressing portion uses a variable bobbin tool.
Provision is made for a means for detecting the temperature around the rotary tool, and based on the detected temperature, the back surface pressing portion, a pressing portion control device for controlling a rotation speed together with at least one pressing force urging force of the front surface pressing portion. A friction stir welding apparatus characterized by being provided.