JP3618715B2

JP3618715B2 - Cooling device for current-carrying electrode and assembly of current-carrying electrode and cooling device

Info

Publication number: JP3618715B2
Application number: JP2001377627A
Authority: JP
Inventors: 正雄鴇田
Original assignee: 住友石炭鉱業株式会社
Priority date: 2001-12-11
Filing date: 2001-12-11
Publication date: 2005-02-09
Anticipated expiration: 2021-12-11
Also published as: JP2003183708A

Description

【０００１】
【発明の属する技術分野】
本発明は、通電電極用の冷却装置及び通電電極と冷却装置との組立体に関し、更に詳細には、パルス通電加圧焼結及び／又は接合装置の通電電極の先端部に取り付けられて被処理部材から通電電極に伝達される熱を遮る冷却装置の改良及び通電電極と冷却装置との組立体に関する。ここで、「パルス通電加圧焼結及び／又は接合装置」とは、パルス通電加圧焼結装置としてもまたパルス通電接合装置としても使用される装置のみならず、パルス通電加圧焼結装置として単独で使用される装置、並びにパルス通電接合装置として単独で使用される装置も含む意味である。
【０００２】
近年通電焼結にも改良が加えられ、例えば放電プラズマ焼結、放電焼結或いはプラズマ活性化焼結を含む、パルス電流を利用して焼結を行うパルス通電加圧焼結法によれば、本来接合が困難な異なる材質の材料、例えばステンレス鋼と銅、セラミックスと各種金属等の材料を焼結により一体的に接合させることが可能になってきた。また、このパルス通電加圧焼結法の原理を利用した接合方法及び接合装置も開発されつつある。
【０００３】
ところで、パルス通電加圧焼結装置により上記のようなパルス通電加圧焼結を行なうには、通常、グラファイトで出来た焼結型の穴内に焼結すべき粉体入れ、その粉体を間に挟んで挿入されセットされた一対のパンチすなわちプレスコアに一対の通電電極を接触させてそれらのプレスコアを所望の圧力で加圧すると共にそれらのプレスコアに通電電極を介して大きな焼結電流を流して焼結する。このとき、焼結すべき粉体の材質によもるが、粉体、焼結型及びプレスコアは高温、例えば粉体がタングステンカーバイド（ＷＣ）の場合には１８００〜２０００℃、に加熱されることになり、その熱はプレスコアを押圧している通電電極に伝達され、通電電極が熱せられてしまうことになる。かかる通電電極はプレスコアに高い圧力を加える必要性があることから、耐酸化性に優れかつ機械的強度の高い材料、例えばステンレス鋼でつくられ、中に冷却液を流す流路が形成され、また必要な場合には、プレスコア側の先端にその流路と通じる冷却通路が形成された冷却部材を配置し、焼結時又は接合時の熱がプレスコアを介して通電電極に直に伝達されるのを防いでいる。
【０００４】
従来のかかる通電電極用の冷却装置としては、例えば、（１）図１［Ａ］に示されるように、片面（同図において下面）に冷却流体用の冷却通路を画成する溝ｂが形成されかつその溝と連通する一対のポートｃが貫通形成された一方の部材ａを、他方の部材ｄに形成された、その部材ｄを受ける凹部ｅ内に勘合し、両部材を互いに重ね合わせた状態でその合わせ面の周辺部ｆ、ｇで溶接によりそれらを互いに接合して一体化して冷却装置とし、その冷却装置を止めねじのような固定手段で通電電極の先端に固定し、その冷却装置に、必要な場合には、更にステンレス鋼製及び／又はグラファイト製の通電プレートｈを取り付けたもの、或いは、（２）図１［Ｂ］に示されるように、片面に冷却通路を画成する溝ｊが形成された一方の部材ｉと、その溝ｊを通電電極に形成された流路と連通するポートｍが形成された他方の部材ｋとを互いに重ね合わせ、その合わせ面の周辺部ｎで溶接によりそれらを接合して一体化して冷却装置とし、その冷却装置を止めねじのような固定手段で通電電極の先端に固定し、その冷却装置に、必要な場合には、更に、図１［Ａ］と同様に、ステンレス鋼製及び／又はグラファイト製の通電プレートを取り付けもの等がある。更に、（３）図２に示されるように、円板状の部材ｐに外周から複数の直線状の盲穴ｑを形成してその複数の盲穴を部材の内部で接続するようにして外側端を栓で塞いで冷却通路を形成し、部材には更にその冷却通路と通電電極の流路とを連通する一対のポートｒを形成して冷却装置とし、その冷却装置を通電電極の先端に取り付けた構造のものがある。そして、冷却盤と通電電極との取り付け面からの冷却流体の漏れを防止するために、通電電極の先端面で流路の回りに形成された環状溝又は冷却盤の通電電極側の面でポートの回りに形成された環状溝内にＯリングシールを配置していた。
【０００５】
【発明が解決しようとする課題】
上記のような構造の冷却装置の設置により焼結型或いは被接合部材から通電電極に伝えられる熱は和らげられるが、焼結型及びプレスコアは、焼結すべき材料によっても異なるが、シリコンカーバイド（ＳｉＣ）、ボロンカーバイド（Ｂ４Ｃ）などの炭化物系セラミックスなどの焼結温度が高い場合には、２，０００℃を超える温度にもなる。しかも、パルス通電加圧焼結機が単に実験用の装置として長い時間を隔てて使用されている場合はよいが、実用生産装置として連続的に使用されると、冷却盤には周期的に高い温度が繰り返し頻繁に伝達されることになるため、加熱、冷却が周期的に繰り返されることになる。このため、前記（１）及び（２）に記載の冷却装置では溶接部で歪み割れを発生し、冷却流体が漏れる問題が発生する。また、前記（３）に記載の冷却装置では栓の部分でのリール破壊の問題或いは冷却通路の成形工程が繁雑になる問題がある。更に、冷却装置によりプレスコア側から通電電極に伝達される熱はある程度低くされるが、焼結温度が高温で、かつ短時間に焼結が繰り返し行われると、冷却装置も蓄熱し、通電電極も高温に熱せられることになる。このため、通電電極と冷却装置との接合面に設けられるＯリングシールが熱より損傷を受け、或いは熱による弾性変形（塑性変形）によって生じた隙間に挟まれて切断する。また、オン‐オフパルス通電によって誘起された不測の火花放電によりＯリングシールが焼け切れるなどの不具合も希にあり、接合面から冷却流体が漏れる問題が発生する。
【０００６】
本発明が解決しようとする課題は、短時間の繰り返しの加熱、冷却に対しても、歪み割れの発生を防止できる通電電極用の冷却装置並びに通電電極と冷却装置との組立体を提供することである。
本発明が解決しようとする他の課題は、通電電極と冷却装置との間の近接位置にあるＯリングシールを省略可能にしてその破損による冷却流体の流出を防止できる通電電極用の冷却装置並びに通電電極と冷却装置との組立体を提供することである。
本発明が解決しようとする別の課題は、パルス通電加圧焼結の原理を利用した接合方法を利用して、繰り返し熱応力に強い接合構造を有する通電電極用の冷却装置並びに通電電極と冷却装置との組立体を構成し、生産用パルス通電加圧焼結機を提供することである。
【０００７】
【課題を解決するための手段】
本願の一つの発明は、電源からのパルス電流を被処理材に通すパルス通電加圧焼結及び／又は接合装置用の通電電極であって、内部において長手方向に伸長させて形成された冷却流体用の流路が開口する前記通電電極の先端面に取り付けられ、前記被処理材から前記通電電極への熱の伝達を遮る冷却装置において、
前記冷却装置が、前記通電電極の前記先端面に接合された、一つの冷却部材を有し、前記冷却部材の前記端面と接合される面に前記流路と連通する冷却通路が形成され、
前記通電電極と前記冷却部材とは、接合面において互いに当接された状態で所定の圧力の加圧下で所定の電圧、電流の直流パルス電流が通されて仮接合され、
前記仮接合された前記通電電極と前記冷却部材とは熱処理炉により所定の条件下で熱処理されて本接合されるように構成されている。この場合、熱処理は短時間で行われ、接合は固相拡散接合であってもよい。
上記通電電極の冷却装置において、前記通電電極及び冷却部材の接合面が鏡面にされていてもよい。
本願の他の発明は、電源からのパルス電流を被処理材に通すパルス通電加圧焼結及び／又は接合装置用の通電電極であって、内部において長手方向に伸長させて形成された冷却流体用の流路が開口する前記通電電極の先端面に取り付けられ、前記被処理材から前記通電電極への熱の伝達を遮る冷却装置において、
前記冷却装置が、互いに接合された少なくとも二つの冷却部材を有し、前記冷却部材の接合面の少なくとも一つの接合面には冷却通路が形成され、前記冷却部材の一つには前記通電電極の流路と前記冷却通路とを連通するポートが形成され、
前記互いに接合される少なくとも二つの冷却部材並びに前記通電電極と前記通電電極に接合される冷却部材とは、接合面において互いに当接された状態で所定の圧力の加圧下で所定の電圧、電流の直流パルス電流が通されて仮接合され、
前記仮接合された冷却部材同士及び前記通電電極と前記冷却部材とは熱処理炉により所定の条件下で熱処理されて本接合されるように構成されている。この場合、熱処理は短時間で行われ、接合は固相拡散接合であってもよい。
上記通電電極用の冷却装置において、前記冷却部材間の接合面及び前記通電電極と冷却部材との接合面が鏡面にされていてもよい。
また、上記両発明において、前記冷却部材がステンレス鋼又はインコネルでつくられかつ前記通電電極がステンレス鋼でつくられ、前記熱処理が真空雰囲気下で９００℃ないし１２００℃の温度で３０分ないし１２０分間行われて作られていてもよい。
【０００８】
本願の別の発明は、電源からのパルス電流を被処理材に通すパルス通電加圧焼結及び／又は接合装置用の通電電極であって、長手方向に伸長しかつ先端面において開口する冷却流体用の流路が形成された通電電極と、前記通電電極の前記先端面に取り付けられ、前記被処理材から前記通電電極への熱の伝達を遮る冷却装置との組立体において、
前記通電電極が互いに取り外し可能に接続された複数の部分を備え、
前記冷却装置が、前記通電電極の先端部分の先端面に接合された、一つの冷却部材を有し、前記冷却部材の前記先端面と接合される面に前記流路と連通する冷却通路が形成され、
前記通電電極と前記冷却部材とは、接合面において互いに当接された状態で所定の圧力の加圧下で所定の電圧、電流の直流パルス電流が通されて仮接合され、
前記仮接合された前記通電電極と前記冷却部材とは熱処理炉により所定の条件下で熱処理されて本接合されるように構成されている。この場合、熱処理は短時間で行われ、かつ接合は固相拡散接合であってもよい。
上記通電電極と冷却装置との組立体において、前記通電電極及び冷却部材の接合面が鏡面にされていてもよい。
本願の更に別の発明は、電源からのパルス電流を被処理材に通すパルス通電加圧焼結及び／又は接合装置用の通電電極であって、長手方向に伸長しかつ先端面において開口する冷却流体用の流路が形成された通電電極と、前記通電電極の前記先端面に取り付けられ、前記被処理材から前記通電電極への熱の伝達を遮る冷却装置との組立体において、
前記通電電極が互いに取り外し可能に接続された複数の部分を備え、
前記冷却装置が、互いに接合された少なくとも二つの冷却部材を有し、前記冷却部材の接合面の少なくとも一つの接合面には冷却通路が形成され、前記冷却部材の一つには前記通電電極の流路と前記冷却通路とを連通するポートが形成され、
前記互いに接合される少なくとも二つの冷却部材並びに前記通電電極の先端部分と前記先端部分に接合される冷却部材とは、接合面において互いに当接された状態で所定の圧力の加圧下で所定の電圧、電流の直流パルス電流が通されて仮接合され、
前記仮接合された冷却部材同士及び前記通電電極と前記冷却部材とは熱処理炉により所定の条件下で熱処理されて本接合されるように構成されている。この場合、熱処理は短時間で行われ、かつ接合は固相拡散接合であってもよい。
上記通電電極と冷却装置との組立体において、前記冷却部材間の接合面及び前記通電電極と冷却部材との接合面が鏡面にされていてもよい。
上記両発明の通電電極と冷却装置との組立体において、前記冷却部材がステンレス鋼又はインコネルでつくられかつ前記通電電極がステンレス鋼でつくられ、前記熱処理が真空雰囲気下で９００℃ないし１２００℃の温度で６０分ないし１２０分間行われてつくられていてもよい。
【０００９】
【実施例】
以下、図面を参照して本発明の実施形態について説明するが、まず、図３及び図４を参照して、本発明による冷却装置が取り付けられる通電電極を備えたパルス通電加圧焼結装置の基本的構造について説明する。パルス通電加圧焼結装置１は、台２１及びその台の上方に複数（例えば４本であるが２本のみ図示）の支柱２２を介して固定された上支持板２３を有する本体フレーム２と、支柱２２に上下移動可能に支持された可動フレーム３と、可動フレーム３に取り付けられた下通電電極４と、上支持板２３に取り付けられている上通電電極４′と、上、下通電電極の先端近傍でチャンバを画成するハウジング組立体５と、可動フレーム３上下動させる駆動装置６とを備えている。可動フレーム３は、軸受け３１を介して支柱２２に滑動可能に案内支持された円板状（この実施形態で）の可動体３２を有している。ハウジング組立体５は、可動体３２に取り付けられた底板５２、底板５２に溶接等により接続された、環状（この実施例では円環状）の側壁を構成する環状体５３及び環状体の上端に固定されたリング部材５４とを有する下ハウジング部分５１と、軸受けを介して支柱２２に滑動可能に案内支持されたリング状の可動体５５と、可動体５５に取り付けられた上ハウジング部分５６とを備えている。上ハウジング部分５６は、可動体５５に固定されたリング部材５７、上壁を構成する天板５８、下端及び上端においてそれぞれリング部材５７及び天板５６に固定された、環状（この実施例では円環状）の側壁を構成する環状体５９を有している。上、下ハウジング部分５１及び５６は互いに協同して焼結チャンバＣを画成するようになっている。上、下ハウジングは、環状体５３、５９をそれぞれ二重に設けることによって二重壁構造（ウオータージャケット状）にされ、中に冷却水を通す構造になっている。この焼結チャンバは図示しない装置により、例えば真空雰囲気或いは不活性ガス雰囲気等の焼結雰囲気に制御されるようになっている。なお、リング部材５４の上面及びリング部材５７の下面の少なくとも一方にはシールリングが設けられ、それらの面間の気密性を確保するようになっている。また、図示しないが上ハウジングの環状体５９には外部から焼結チャンバ内を見れるように覗き窓を設けてもよい。
なお、上ハウジング部分が取り付けられている可動体は、図示しない流体シリンダ等のアクチュエータにより上下動され、それによって上ハウジング部分が下ハウジング部分に接近したり、そこから離れたりするようになっている。
【００１０】
下通電電極４は、図４に詳細に示されるように、電極本体４１が、可動フレーム３２及び底板５２の中央部に形成された上下方向の貫通穴内に、絶縁ブッシュ４６及び絶縁板４７を介して可動フレーム３２及び底板５２に電気的に絶縁させた状態で通され、そのフランジ部４２が固定ボルト４８で可動フレーム３２に取り付けることによって、可動フレーム３２に固定されている。電極本体及びフランジ部は、この実施形態では、ステンレス鋼等の耐圧性に優れた材料で一体的に形成されている。この電極本体の内部には、少なくとも１対の長手方向に伸長し一端が先端面（図３で上端面）で開口する、水等の冷却流体用の流路４４が形成されている。下通電電極の電極本体４１の先端（図３で上端）には本発明の冷却装置７が取り付けられている。電極本体の内部に形成された流路４４は、例えばフランジ部の外周に開口させた他端を介して図示しない外部の冷却流体供給源に接続されるようになっている。また、下通電電極は導電体４９を介して図示しない電源装置に接続されるようになっている。なお、図３及び図４に示される実施形態では流路は１対で示されているが２対又はそれ以上でもよい。
【００１１】
上通電電極４は、円柱状の電極本体４１′が上支持板３３の中央部に形成された上下方向の貫通穴内に絶縁ブッシュ４６′及び４７′を介して上支持板３３と電気的に絶縁させた状態で通され、フランジ部４２′が固定ボルト等（図示せず）により上支持板３３固定されることによって、上支持板に固定されている。電極本体及びフランジ部は、この実施形態では、ステンレス鋼等の耐圧性に優れた材料で一体的に形成されている。上通電電極の電極本体は、上ハウジング部分５６の天板５８を上下に貫通する穴を通して伸び、下端が焼結チャンバ内に配置されるようになっている。電極本体４１′の先端（図１で下端）には本発明の冷却装置７が取り付けられている。天板５８には絶縁ブッシュ及びシール部材等が取り付けられ、電極本体４１′と天板５８との間の絶縁及び気密性を確保している。上通電電極４′の電極本体内には、長手方向に伸長し先端面（図３で下端面）で開口する、水等の冷却流体用の流路が形成されている。上通電電極の電極本体４１′の先端（図３で下端）には本発明の冷却装置７′が取り付けられている。電極本体の内部に形成された流路は図示しない外部の冷却流体供給源に接続されるようになっている。上通電電極に形成される流路は下通電電極に形成された流路と同じ構成でよい。また、上通電電極は導電体４９′を介して図示しない電源装置に接続されるようになっている。
【００１２】
駆動装置６は、この実施形態では流体圧シリンダ６１で構成され、そのピストンロッド６２の先端（図で上端）には下通電電極に固定するための接続ブロック６３が固定されている。接続ブロック６３とピストンロッド１６２との接続方法は、ピストンロッド先端に形成された雄ねじを接続ブロックに形成された雌ねじに螺合することにより行われる。接続ブロック６３と下通電電極４のと間には、導電体４９と、絶縁板６４とが導電体を下通電電極に接触させた状態で、配置されている。接続ブロック６３は、図４に示されるように、その接続ブロック６３を固定ボルト６６で下通電電極４１のフランジ部４２に取り付けることによって、下通電電極に固定されている。なお、図３において、ｐは焼結型、ｑは下プレスコア、ｒは上プレスコア、ｓは焼結される粉末材料である。
上記のパルス通電加圧焼結装置は本発明の冷却装置付き通電電極が取り付けられ得る装置の一例に過ぎない。したがって、冷却装置或いは通電電極と冷却装置の組立体は他のいかなる形式のパルス通電加圧焼結装置或いはパルス通電接合装置にも取り付けられ得る。
【００１３】
次に通電電極及びそれに組み付けられる冷却装置に付いて説明するが、上、下通電電極及び冷却装置は同じ構造で良いので、下通電電極に関連して説明する。
図５において、冷却装置の第１の実施形態が示されている。この実施形態における冷却装置７は、１個の冷却部材７１のみで構成されている。冷却部材は、例えば、電極本体と同じステンレス鋼（例えば、ＳＵＳ３０４）でつくられた厚肉円板状体又は柱状体で良く、電極本体４１の先端（図で下端）面４３に当接する面７３には環状溝７５が形成されている。この環状溝は冷却通路を画成し、電極本体４１に軸方向に伸長させて形成されかつ先端面４３で開口する一対の流路４４と連通可能になっている。電極本体４１と冷却部材７１とは、先端面４３と面７３とを当接させた状態で、パルス通電加圧焼結法の原理を利用した接合方法で一体的に接合されている。
【００１４】
次に、電極本体と冷却部材とを接合する方法について説明する。
まづ、冷却部材７１の表面７３に冷却通路を画成する図５に示されるような環状溝７５を形成した後、表面を電極本体４１の先端面４３に全面に亘ってぴったりと当接するように表面加工する。この場合、冷却部材７１の表面７３及び電極本体７１の先端面７３を平坦面にするのがよいが、両者が同じ曲面であるなら、平坦面に限らず曲面でもよい。また、両者の表面は粗面でもよいが（表面粗さがＪＩＳ規格で▽印程度）でもよいが、Ｒａ０．３μｍ以下の鏡面にするのが両者の接合強度を高く、かつ接合による変形を小さくでき、しかも接合面からの冷却流体の漏れも防止できる点などパルス通電接合２段処理法により固相拡散接合が良好に実施できるので好ましい。
【００１５】
次に、通電電極４の先端面４３の上に接合部材７１を重ね、図７に示されるように、通電接合装置１００の一対の通電電極間に配置する。通電接合装置１００は、通電接合部１１０と、熱処理部１２０とを備えている。通電接合部１１０は、図３に示される構造と同じものでよいが、図６では接合動作の基本的動作の説明に必要な構成要素を示して説明する。互いに重ね合わされ通電電極４と冷却部材７１を通電接合部１１０の下通電電極１１１と上通電電極１１２との間に挟んだ状態で、加圧装置１１３を動作させて上通電電極１１２を下通電電極１１１側に押圧して通電電極４と接合部材７１を所望の圧力で押圧する。この押圧力は、互いに接合すべき通電電極４及び接合部材７１がステンレス鋼の場合は３０ＭＰａ（メガパスカル）ないし５０ＭＰａ（メガパスカル）の範囲でよい。このように押圧した状態で、下通電電極及び上通電電極に電源装置１１５から所定の電圧、電流の直流パルス電流を流す。すると通電電極４と冷却部材７１とは当接面で互いに接合される。これは、直流パルス電流を流すと、接触抵抗の高い当接界面部分がジュール加熱により高温に熱せられ、また、材料自体の抵抗値により全体がジュール加熱される。更にオン−オフパルス電流の流れの方向に沿って電場が生じ、電界拡散が生じる。この電界拡散効果と前述の熱拡散の機械的圧力が固相拡散接合に寄与し金属結晶構造の配向性をもたらすと考えられる。また、このパルス通電接合（焼結）方法は従来の連続直流通電接合（焼結）法に比べ単位時間当たりの拡散速度、緻密化速度が速いことがいままでの接合（焼結）実験結果で分かっている。原理的に短時間パルス通電での拡散量は、表面層のみで少ない。その結果この状態での隣接するブロック間の接合は接合強度の点で見た場合まだ完全なものではないが、接合界面の金属格子の配列状態はより拡散し易い方向に揃うものと考えられる。そこでこの接合状態を仮接合と呼ぶ。仮接合された通電電極及び冷却部材は、次に熱処理部１２０の熱処理炉内で熱処理が行なわれる。これを２段処理と呼ぶ。熱処理温度及び時間は通電電極及び冷却部材の材質及び大きさによって異なる。この２段熱処理を行うことにより大量の拡散に寄与するエネルギーが投入され仮接合されていてかつ接合界面の金属結晶配向性の揃った前処理状態があるため接合面間の固相拡散接合が急激に促進され拡散量（深さ）が増大した完全なものになって完全一体化された接合体になり、その接合強度は通電電極及び冷却部材を構成しているステンレス鋼の材質の強度に匹敵する値になる。しかも、従来のように通電電極と冷却装置との接合面にＯリングシールを必要としなくなったので、本発明による冷却装置を有する焼結装置を高い頻度で繰り返し使用した場合においても、Ｏリングシールの焼損による冷却流体の漏れを防止できる。なお、熱処理部１２０は公知の構造の真空熱処理炉でよい。上記パルス通電接合による加圧力、パルス電流の電圧及び電流並びに熱処理温度及び時間等は通電電極及び冷却部材の材質及びサイズによって異なる。この熱処理時間は、従来の固相拡散接合に要する時間の約１／８ないし１／５程度ですみ省エネルギー効果、製造コスト面で極めて優位性が高い。また、冷却部材の６１の他の面（非接合面）には、必要に応じ図１に示すグラファイト製の通電プレートと止めネジ等で取り外し可能に取り付けてもよいことはもちろんである。
【００１６】
実施例１
図８に示されるように通電電極４及び冷却部材７１の材質を同じステンレス鋼（ＳＵＳ３０４）とし、直径Ｄを１００ｍｍとし、通電電極の長さＬを２２０ｍｍ及び冷却部材７１の厚さＷを３５ｍｍとした場合、電圧３〜１２Ｖ、電流２０００ないし５０００Ａの直流パルス電流を１０ないし３０分間流して仮接合した。その後仮接合された通電電極及び冷却部材を不活性雰囲気の下で温度１０００ないし１２００℃で６０分ないし１２０分間相互拡散熱処理を行って両者の接合を完了した。これにより通電電極４及び冷却部材の当接面で全面に亘り完全に接合させることができ、この冷却装置付きの通電電極を取り付けたパルス通電加圧焼結装置を下記の条件での繰りの返し使用によっても接合面での亀裂が発生せずまた冷却流体の漏れも発生しなかった。
使用例１
使用周期１５分
焼結温度１２００℃
焼結圧力３０ＭＰａ
使用回数５０回
使用例２
使用周期３０分
焼結温度２０００℃
焼結圧力５０ＭＰａ
使用回数５０回
【００１７】
図５及び図６に示された実施形態では通電電極の先端面に単一の冷却部材を接合した例を示したが、図９に示されるように、上記接合方法で互いに接合した一対の冷却部材７１ａ及び７２ａで一つの冷却装置７ａを構成し、その冷却装置を通電電極の先端に前記実施形態と同様にして接合してもよい。図９において、一方の冷却部材７１ａの一方の面７３ａに冷却通路を画成する溝７５ａを形成し、他方の冷却部材７２ａの面（面７３ａに面する面）７４ａには、溝７５ａと連通可能な一対のポート７６ａを形成し、冷却部材７１ａの面７３ａと冷却部材７２ａの面７４ａとを前記実施形態と同様の方法で接合し、冷却装置７ａを形成する。また、冷却装置７ａの冷却部材７２ａを、一対のポート７５ａを通電電極の一対の流路４４と整合させた状態で、通電電極４の先端面４３に前記実施形態と同様に接合する。この場合、一対の冷却部材と通電電極を重ね、それらを一度に接合してもよい。なお、冷却部材を３個以上にして各冷却部材の接合面に冷却通路を形成したそれらを直列又は並列に接続し、通電電極に形成されている流路と連通可能にしても良い。このようにすることにより冷却効果を更に向上できる。
なお、上記二つの実施形態において、溝は環状の形状で示したが、必ずしも環状である必要はなく、図１０に７ｂで示される冷却部材に形成された溝７５ｂのように波形の形状或いはその他の形状でよい。図１０に示される形状の場合、溝の７５ｂ端部が通電電極の一対の通路と連通するようにする必要がある。
【００１８】
図１１及び図１２において、本発明による通電電極と冷却装置との組立体が示されている。この組立体は、図３に示されるパルス通電加圧焼結装置の上通電電極に適用するのに適している。図３に示される焼結装置では上通電電極４′が下通電電極４に比較して非常に長くなっており、上通電電極とそれに接合されるべき冷却部材とをパルス通電加圧焼結装置の一対の通電電極間にセットすることが非常に困難になる。そこで、下通電電極４に冷却部材を接合する場合と同じになるように、通電電極を長手方向に二つの部分に分け、先端部分の先端面に冷却部材を接合するものである。
すなわち、同図において、通電電極４ｃ′は、上支持板２３に固定される基端部分４ｃ_１′と、先端部分４ｃ_２′とに分割されている。なお、図３の実施形態と同じ構成部材に付いては同じ参照番号を付して説明は省略する。基端部分４ｃ_１′の電極本体４１ｃ_１′は図３の通電電極４と同じ方法により上支持板２３に固定されていて、先端（図１１で下端）にはフランジ部が形成されている。先端部分４ｃ_２′の電極本体４１ｃ_２′の一端（図１１及び図１２において上端）にはフランジ部４２ｃ_２′が形成され、そのフランジ部は複数の止めねじ４８ｃ_２′（図１２では１個のみ図示）によって基端部分４ｃ_１′のフランジ部に取り外し可能に取り付けられている。先端部分４ｃ_２′の先端面４３ｃ_２′には前記実施形態と同様な構造を有する１個の冷却部材７１ｃで構成される冷却装置７ｃが前述の接合方法と同じ方法で取り付けられている。基端部分４ｃ_１′と先端部分４ｃ_２′との取り付け面には流路を囲むＯリングシールが設けられ、取り付け面を通して冷却流体が外部に漏れるのを防止している。
【００１９】
この通電電極と冷却装置との組立体によれば、通電電極自体が軸方向に長くなって、その先端への冷却装置のパルス通電加圧接合法による取り付けが困難な場合でも、容易に接合可能になる。しかも、Ｏリングシールの取り付け位置は冷却装置から離れておりかつ通電電極の先端部分自身が冷却されているため、Ｏリングシールの位置まで伝達される熱が低くなり、Ｏリングシールの熱による破損や、Ｏリング取付け部の弾性、塑性変形による損傷などを防止できる。
なお、分割された通電電極の先端部分に接合される冷却装置は図１１及び図１２に示されるものに限られず、図９図に示される構造のものでもよいことはもちろんである。また、冷却部材の先端面（非接合面）にステンレス鋼製及び／又はグラファイト製の通電プレートを取り付けても良いことはもちろんである。なお、上記実施形態では冷却部材をステンレス鋼でつくった場合について説明したが、該部材をインコネルでつくっても良い。
【００２０】
【効果】
本発明によれば、
（イ）パルス通電加圧焼結装置或いはパルス通電接合装置の短時間の繰り返し使用により通電電極が繰り返し加熱、冷却されても溶接部分がないため熱応力による冷却装置の歪み割れによる水漏れの発生を防止でき、安全に長期間操業できる、
（ロ）固相拡散接合により通電電極とそれに取り付けられる冷却装置との間の近接位置のＯリングシールを省略できるので、Ｏリングシールの破損による漏れを防止できる、
（ハ）高温焼結時に先端の冷却装置部に熱による軟化に伴う弾性変形（或いは塑性変形）で隙間ができ、Ｏリングシール不良を生じる水漏れ問題は、Ｏリングシールが省略されているため発生しない、また、冷却を効率よく行えるため、弾性／塑性変形防止され、生産用の焼結機として安定した性能を発揮できる、
（ニ）従来の固相拡散接合に比べて熱処理時間が約１／８ないし１／５と短く、製造コストが安価でかつ信頼性の高い冷却装置を構成することができる、
等の効果を奏することが可能である。
【図面の簡単な説明】
【図１】従来の通電電極用の冷却装置の例を示す断面図である。
【図２】従来の通電電極用の冷却装置の他の例を示す平面図である。
【図３】本発明の冷却装置を有する通電装置を備えたパルス通電加圧焼結機の一例の側面図である。
【図４】下通電電極と駆動装置との連結状態を示す拡大断面図である。
【図５】本発明による冷却装置の一実施形態が接合された通電電極の一部の断面図である。
【図６】図５に示される冷却装置の冷却部材の平面図であって、溝の形状を示す図である。
【図７】本発明の冷却装置と通電電極との接合を説明する概略図である。
【図８】通電電極と冷却装置の寸法関係を示す側面図である。
【図９】本発明による冷却装置の他の実施形態が接合された通電電極の一部の断面図である。
【図１０】冷却部材に形成される溝の変形例を示す図である。
【図１１】本発明による通電電極と冷却装置の組立体を示す断面図である。
【図１２】図１１の一部の拡大断面図である。
【符号の説明】
１、１ｃパルス通電加圧焼結装置
４、４′、４ｃ′ 通電電極
４４、４４ｃ_２′ 流路
７、７′、７ａ、７ｂ、７ｃ′ 冷却装置
７１、７１ａ、７１ｂ、７１ｃ′ 冷却部材７２ａ冷却部材
７５、７５ａ、７５ｃ′ 溝[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cooling device for an energized electrode and an assembly of the energized electrode and the cooling device, and more particularly, is attached to the tip of the energized electrode of the pulse energized pressure sintering and / or joining device to be processed. The present invention relates to an improvement of a cooling device that blocks heat transmitted from a member to a current-carrying electrode and an assembly of a current-carrying electrode and a cooling device. Here, the “pulse current pressure sintering and / or bonding apparatus” is not only a pulse current pressure sintering apparatus and a pulse current bonding apparatus, but also a pulse current pressure sintering apparatus. As well as a device used alone as a pulse current bonding device.
[0002]
In recent years, improvements have also been made in electric current sintering. For example, according to the pulse electric current pressure sintering method in which sintering is performed using a pulse current, including discharge plasma sintering, discharge sintering or plasma activated sintering, It has become possible to integrally bond materials of different materials, which are inherently difficult to bond, such as stainless steel and copper, ceramics and various metals, by sintering. In addition, a joining method and a joining apparatus using the principle of this pulse current pressure sintering method are being developed.
[0003]
By the way, in order to perform the pulsed electric pressure sintering as described above by the pulsed electric pressure sintering apparatus, the powder to be sintered is usually placed in a sintering type hole made of graphite, and the powder is placed in between. A pair of energized electrodes are brought into contact with a pair of punches or press cores inserted and set between the press cores to pressurize the press cores with a desired pressure, and a large sintering current is applied to the press cores through the energized electrodes. Flow and sinter. At this time, although depending on the material of the powder to be sintered, the powder, the sintering die and the press core are heated to a high temperature, for example, 1800 to 2000 ° C. when the powder is tungsten carbide (WC). Therefore, the heat is transmitted to the energizing electrode pressing the press core, and the energizing electrode is heated. Since it is necessary to apply a high pressure to the press core, the current-carrying electrode is made of a material having excellent oxidation resistance and high mechanical strength, for example, stainless steel, in which a flow path for flowing a coolant is formed, If necessary, a cooling member with a cooling passage communicating with the flow path is arranged at the tip on the press core side, and heat during sintering or joining is directly transferred to the energizing electrode through the press core. Is prevented.
[0004]
As a conventional cooling device for current-carrying electrodes, for example, (1) as shown in FIG. 1A, a groove b defining a cooling passage for cooling fluid is formed on one side (the lower side in the figure). One member a in which a pair of ports c communicating with the groove is formed is fitted into a recess e that is formed in the other member d and receives the member d, and the two members are overlapped with each other. In the state, the peripheral portions f and g of the mating surfaces are joined together by welding to form a cooling device, and the cooling device is fixed to the tip of the energizing electrode by a fixing means such as a set screw. If necessary, a stainless steel and / or graphite energizing plate h is attached, or (2) a cooling passage is defined on one side as shown in FIG. 1B. One member i in which a groove j is formed; The groove j is overlapped with the other member k formed with the port m communicating with the flow path formed in the energizing electrode, and they are joined and integrated by cooling at the peripheral portion n of the mating surface to cool. The cooling device is fixed to the end of the energizing electrode by a fixing means such as a set screw. If necessary, the cooling device is made of stainless steel and / or as in FIG. Alternatively, there are those fitted with a graphite energizing plate. (3) As shown in FIG. 2, a plurality of straight blind holes q are formed in the disk-shaped member p from the outer periphery, and the plurality of blind holes are connected to each other inside the member. The end is closed with a plug to form a cooling passage, and the member is further formed with a pair of ports r communicating the cooling passage and the flow path of the energizing electrode to form a cooling device. There is an attached structure. In order to prevent leakage of the cooling fluid from the mounting surface of the cooling plate and the energizing electrode, an annular groove formed around the flow path at the front end surface of the energizing electrode or a port on the energizing electrode side surface of the cooling plate An O-ring seal was placed in an annular groove formed around the.
[0005]
[Problems to be solved by the invention]
Although the heat transferred from the sintering die or the member to be joined to the current-carrying electrode is moderated by the installation of the cooling device having the above structure, the sintering die and the press core differ depending on the material to be sintered. When the sintering temperature of carbide-based ceramics such as (SiC) and boron carbide (B4C) is high, the temperature exceeds 2,000 ° C. Moreover, it is good if the pulse-current pressure-sintering machine is simply used as an experimental device over a long period of time, but when used continuously as a practical production device, it is periodically high in the cooling panel Since temperature is repeatedly transmitted frequently, heating and cooling are repeated periodically. For this reason, in the cooling device as described in said (1) and (2), the distortion crack generate | occur | produces in a welding part and the problem that a cooling fluid leaks generate | occur | produces. Further, the cooling device described in (3) has a problem of reel destruction at the plug portion or a problem of complicated cooling passage molding process. Furthermore, although the heat transferred from the press core side to the energizing electrode by the cooling device is lowered to some extent, if the sintering temperature is high and the sintering is repeated in a short time, the cooling device also stores heat and the energizing electrode It will be heated to a high temperature. For this reason, the O-ring seal provided on the joint surface between the energizing electrode and the cooling device is damaged by heat or is sandwiched by a gap generated by elastic deformation (plastic deformation) due to heat. In addition, there is a rare problem that the O-ring seal burns out due to an unexpected spark discharge induced by the on-off pulse energization, causing a problem that the cooling fluid leaks from the joint surface.
[0006]
The problem to be solved by the present invention is to provide a cooling device for an energized electrode and an assembly of the energized electrode and the cooling device that can prevent the occurrence of strain cracking even when heating and cooling are repeated for a short time. It is.
Another problem to be solved by the present invention is a cooling device for an energized electrode that can omit an O-ring seal in the proximity position between the energized electrode and the cooling device and prevent outflow of cooling fluid due to the breakage, and It is to provide an assembly of a current-carrying electrode and a cooling device.
Another problem to be solved by the present invention is to provide a cooling device for a current-carrying electrode having a joint structure that is resistant to repeated thermal stress, a cooling method for the current-carrying electrode, and a cooling method. It is to provide an assembly with the apparatus and to provide a pulse current pressure sintering machine for production.
[0007]
[Means for Solving the Problems]
One invention of the present application is a current-carrying electrode for pulse-current-pressure-sintering and / or joining apparatus that passes a pulse current from a power source through a material to be processed, and is a cooling fluid formed by extending in the longitudinal direction inside In the cooling device that is attached to the front end surface of the energizing electrode where a flow path for opening is opened and blocks heat transfer from the material to be processed to the energizing electrode,
The cooling device has one cooling member joined to the tip surface of the energizing electrode, and a cooling passage communicating with the flow path is formed on a surface joined to the end surface of the cooling member,
The energization electrode and the cooling member are temporarily joined by passing a DC pulse current of a predetermined voltage and current under pressure of a predetermined pressure in a state where they are in contact with each other on the bonding surface,
The temporarily joined energized electrode and the cooling member are heat-bonded under a predetermined condition in a heat treatment furnace and are finally joined. In this case, the heat treatment is performed in a short time, and the bonding may be solid phase diffusion bonding.
In the cooling device for the energizing electrode, a joining surface of the energizing electrode and the cooling member may be a mirror surface.
Another invention of the present application is an energization electrode for pulse energization pressure sintering and / or a joining apparatus for passing a pulse current from a power source through a material to be processed, and is a cooling fluid formed by extending in the longitudinal direction inside In the cooling device that is attached to the front end surface of the energizing electrode where a flow path for opening is opened and blocks heat transfer from the material to be processed to the energizing electrode,
The cooling device includes at least two cooling members bonded to each other, a cooling passage is formed in at least one of the bonding surfaces of the cooling member, and one of the energizing electrodes is provided in one of the cooling members. A port that connects the flow path and the cooling passage is formed,
The at least two cooling members to be joined to each other, and the energization electrode and the cooling member to be joined to the energization electrode are in contact with each other at a joining surface and are subjected to a predetermined voltage and current under a predetermined pressure. DC pulse current is passed and temporarily joined,
The temporarily joined cooling members and the energizing electrode and the cooling member are configured to be heat-bonded under a predetermined condition by a heat treatment furnace and to be finally joined. In this case, the heat treatment is performed in a short time, and the bonding may be solid phase diffusion bonding.
In the cooling device for energizing electrodes, the joint surface between the cooling members and the joint surface between the energizing electrode and the cooling member may be mirror surfaces.
In both the above inventions, the cooling member is made of stainless steel or Inconel and the energizing electrode is made of stainless steel, and the heat treatment is performed at a temperature of 900 ° C. to 1200 ° C. for 30 minutes to 120 minutes in a vacuum atmosphere. It may be made.
[0008]
Another invention of the present application is a current-carrying electrode for pulse-current-pressure-sintering and / or joining apparatus that passes a pulse current from a power source through a material to be processed, and is a cooling fluid that extends in the longitudinal direction and opens at the tip surface In an assembly of a current-carrying electrode in which a flow path is formed, and a cooling device that is attached to the distal end surface of the current-carrying electrode and blocks heat transfer from the material to be processed to the current-carrying electrode,
The current-carrying electrode comprises a plurality of parts removably connected to each other,
The cooling device has one cooling member joined to the tip surface of the tip portion of the energization electrode, and a cooling passage communicating with the flow path is formed on a surface joined to the tip surface of the cooling member. And
The energization electrode and the cooling member are temporarily joined by passing a DC pulse current of a predetermined voltage and current under pressure of a predetermined pressure in a state where they are in contact with each other on the bonding surface,
The temporarily joined energized electrode and the cooling member are heat-bonded under a predetermined condition in a heat treatment furnace and are finally joined. In this case, the heat treatment is performed in a short time, and the bonding may be solid phase diffusion bonding.
In the assembly of the energizing electrode and the cooling device, the joining surface of the energizing electrode and the cooling member may be a mirror surface.
Still another invention of the present application is a current-carrying electrode for pulse-current-pressure-sintering and / or joining apparatus that passes a pulse current from a power source through a material to be processed, and is a cooling that extends in the longitudinal direction and opens at the tip surface In an assembly of a current-carrying electrode in which a flow path for fluid is formed, and a cooling device that is attached to the distal end surface of the current-carrying electrode and blocks heat transfer from the material to be processed to the current-carrying electrode,
The current-carrying electrode comprises a plurality of parts removably connected to each other,
The cooling device includes at least two cooling members bonded to each other, a cooling passage is formed in at least one of the bonding surfaces of the cooling member, and one of the energizing electrodes is provided in one of the cooling members. A port that connects the flow path and the cooling passage is formed,
The at least two cooling members to be joined to each other, and the tip portion of the energizing electrode and the cooling member to be joined to the tip portion are in contact with each other on the joint surface under a predetermined pressure under a predetermined pressure. , The DC pulse current of the current is passed and temporarily joined,
The temporarily joined cooling members and the energizing electrode and the cooling member are configured to be heat-bonded under a predetermined condition by a heat treatment furnace and to be finally joined. In this case, the heat treatment is performed in a short time, and the bonding may be solid phase diffusion bonding.
In the assembly of the energizing electrode and the cooling device, the joining surface between the cooling members and the joining surface between the energizing electrode and the cooling member may be mirror surfaces.
In the assembly of the energizing electrode and the cooling device of both the above inventions, the cooling member is made of stainless steel or Inconel and the energizing electrode is made of stainless steel, and the heat treatment is performed at 900 ° C. to 1200 ° C. in a vacuum atmosphere. It may be made at a temperature for 60 to 120 minutes.
[0009]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, referring to FIG. 3 and FIG. 4, a pulse energization pressure sintering apparatus including an energizing electrode to which a cooling apparatus according to the present invention is attached will be described. The basic structure will be described. The pulse energization pressure sintering apparatus 1 includes a main body frame 2 having a base 21 and an upper support plate 23 fixed above the base via a plurality of pillars 22 (for example, four but only two are shown). The movable frame 3 supported on the support column 22 so as to be movable up and down, the lower energizing electrode 4 attached to the movable frame 3, the upper energizing electrode 4 'attached to the upper support plate 23, and the upper and lower energizing electrodes The housing assembly 5 which defines a chamber in the vicinity of the tip of the movable frame 3 and the drive device 6 which moves the movable frame 3 up and down are provided. The movable frame 3 has a disc-like (in this embodiment) movable body 32 that is slidably guided and supported by the support column 22 via a bearing 31. The housing assembly 5 is fixed to the bottom plate 52 attached to the movable body 32, the annular body 53 that is connected to the bottom plate 52 by welding or the like and that forms an annular (annular in this embodiment) side wall, and the upper end of the annular body. A lower housing portion 51 having a ring member 54 formed thereon, a ring-shaped movable body 55 that is slidably guided and supported by the column 22 via bearings, and an upper housing portion 56 attached to the movable body 55. ing. The upper housing portion 56 includes a ring member 57 fixed to the movable body 55, a top plate 58 constituting the upper wall, and a ring (in this embodiment, a circle) fixed to the ring member 57 and the top plate 56 at the lower and upper ends, respectively. An annular body 59 constituting an annular side wall is provided. The upper and lower housing portions 51 and 56 cooperate with each other to define a sintering chamber C. The upper and lower housings have a double wall structure (water jacket shape) by providing the annular bodies 53 and 59 in a double manner, and the cooling water is allowed to pass therethrough. This sintering chamber is controlled to a sintering atmosphere such as a vacuum atmosphere or an inert gas atmosphere by an apparatus (not shown). A seal ring is provided on at least one of the upper surface of the ring member 54 and the lower surface of the ring member 57 so as to ensure airtightness between these surfaces. Although not shown, a viewing window may be provided on the annular body 59 of the upper housing so that the inside of the sintering chamber can be seen from the outside.
The movable body to which the upper housing portion is attached is moved up and down by an actuator (not shown) such as a fluid cylinder, so that the upper housing portion approaches or moves away from the lower housing portion. .
[0010]
As shown in detail in FIG. 4, the lower energizing electrode 4 is configured such that the electrode main body 41 is interposed in the vertical through hole formed in the central portion of the movable frame 32 and the bottom plate 52 via the insulating bush 46 and the insulating plate 47. The flange 42 is fixed to the movable frame 32 by attaching the flange 42 to the movable frame 32 with a fixing bolt 48. In this embodiment, the electrode main body and the flange portion are integrally formed of a material having excellent pressure resistance such as stainless steel. Inside the electrode body, there is formed a flow path 44 for a cooling fluid such as water that extends in at least one pair of longitudinal directions and has one end opened at the tip end surface (the upper end surface in FIG. 3). The cooling device 7 of the present invention is attached to the tip (upper end in FIG. 3) of the electrode body 41 of the lower energization electrode. The flow path 44 formed inside the electrode body is connected to an external cooling fluid supply source (not shown) through the other end opened to the outer periphery of the flange portion, for example. Further, the lower energization electrode is connected to a power supply device (not shown) through a conductor 49. In addition, in embodiment shown by FIG.3 and FIG.4, although the flow path is shown by 1 pair, 2 pairs or more may be sufficient.
[0011]
The upper energizing electrode 4 is electrically insulated from the upper support plate 33 through insulating bushes 46 ′ and 47 ′ in a vertical through hole formed in a central portion of the upper support plate 33 with a cylindrical electrode body 41 ′. The flange portion 42 ′ is fixed to the upper support plate by fixing the upper support plate 33 with a fixing bolt or the like (not shown). In this embodiment, the electrode main body and the flange portion are integrally formed of a material having excellent pressure resistance such as stainless steel. The electrode body of the upper energizing electrode extends through a hole that vertically penetrates the top plate 58 of the upper housing portion 56, and the lower end is disposed in the sintering chamber. The cooling device 7 of the present invention is attached to the tip (lower end in FIG. 1) of the electrode body 41 ′. An insulating bush, a seal member, and the like are attached to the top plate 58 to ensure insulation and airtightness between the electrode body 41 ′ and the top plate 58. A flow path for a cooling fluid such as water is formed in the electrode body of the upper energizing electrode 4 ′ and extends in the longitudinal direction and opens at the front end surface (lower end surface in FIG. 3). The cooling device 7 'of the present invention is attached to the tip (lower end in FIG. 3) of the electrode body 41' of the upper energizing electrode. The flow path formed inside the electrode body is connected to an external cooling fluid supply source (not shown). The flow path formed in the upper energization electrode may have the same configuration as the flow path formed in the lower energization electrode. Further, the upper energizing electrode is connected to a power supply device (not shown) through a conductor 49 '.
[0012]
In this embodiment, the driving device 6 is composed of a fluid pressure cylinder 61, and a connection block 63 for fixing to the lower energizing electrode is fixed to the tip (upper end in the figure) of the piston rod 62. The connection method of the connection block 63 and the piston rod 162 is performed by screwing a male screw formed at the tip of the piston rod with a female screw formed in the connection block. Between the connection block 63 and the lower energizing electrode 4, a conductor 49 and an insulating plate 64 are arranged in a state where the conductor is in contact with the lower energizing electrode. As shown in FIG. 4, the connection block 63 is fixed to the lower energization electrode by attaching the connection block 63 to the flange portion 42 of the lower energization electrode 41 with a fixing bolt 66. In FIG. 3, p is a sintering mold, q is a lower press core, r is an upper press core, and s is a powder material to be sintered.
The above-mentioned pulse energization pressure sintering apparatus is only an example of an apparatus to which the energizing electrode with a cooling device of the present invention can be attached. Therefore, the cooling device or the assembly of the energizing electrode and the cooling device can be attached to any other type of pulse energizing pressure sintering apparatus or pulse energizing joining apparatus.
[0013]
Next, the energizing electrode and the cooling device assembled to the energizing electrode will be described. The upper and lower energizing electrodes and the cooling device may have the same structure.
In FIG. 5, a first embodiment of the cooling device is shown. The cooling device 7 in this embodiment is configured by only one cooling member 71. The cooling member may be, for example, a thick disk or column made of the same stainless steel (for example, SUS304) as the electrode body, and a surface 73 that contacts the tip (lower end in the figure) surface 43 of the electrode body 41. Is formed with an annular groove 75. The annular groove defines a cooling passage, and is formed so as to extend in the axial direction in the electrode body 41 and can communicate with a pair of flow paths 44 opened at the front end surface 43. The electrode body 41 and the cooling member 71 are integrally joined by a joining method using the principle of the pulsed current pressure sintering method in a state where the tip surface 43 and the surface 73 are in contact with each other.
[0014]
Next, a method for joining the electrode body and the cooling member will be described.
First, after forming an annular groove 75 as shown in FIG. 5 that defines a cooling passage on the surface 73 of the cooling member 71, the surface is brought into close contact with the tip surface 43 of the electrode body 41 over the entire surface. Surface treatment. In this case, the surface 73 of the cooling member 71 and the tip surface 73 of the electrode body 71 are preferably flat surfaces. However, if both are the same curved surface, the surface is not limited to a flat surface and may be a curved surface. In addition, the surface of both may be rough (the surface roughness is about ▽ in JIS standard), but a mirror surface with Ra of 0.3 μm or less increases the bonding strength between them and reduces deformation due to bonding. In addition, it is preferable because solid phase diffusion bonding can be satisfactorily performed by the pulse current bonding two-stage treatment method, such as being able to prevent leakage of cooling fluid from the bonding surface.
[0015]
Next, the joining member 71 is overlaid on the front end surface 43 of the energization electrode 4 and is disposed between the pair of energization electrodes of the energization joining apparatus 100 as shown in FIG. The energization joining apparatus 100 includes an energization joining portion 110 and a heat treatment portion 120. The current-carrying joint 110 may have the same structure as that shown in FIG. 3, but FIG. 6 shows and illustrates the components necessary for explaining the basic operation of the joining operation. In a state where the energizing electrode 4 and the cooling member 71 are overlapped with each other and sandwiched between the lower energizing electrode 111 and the upper energizing electrode 112 of the energizing joint 110, the pressurizing device 113 is operated to make the upper energizing electrode 112 the lower energizing electrode. It presses to the 111 side, and presses the electricity supply electrode 4 and the joining member 71 with a desired pressure. This pressing force may be in the range of 30 MPa (megapascal) to 50 MPa (megapascal) when the energizing electrode 4 and the joining member 71 to be joined together are stainless steel. In this pressed state, a DC pulse current of a predetermined voltage and current is supplied from the power supply device 115 to the lower energizing electrode and the upper energizing electrode. Then, the energizing electrode 4 and the cooling member 71 are joined to each other at the contact surface. When a direct current pulse current is passed, the contact interface portion having a high contact resistance is heated to a high temperature by Joule heating, and the whole is Joule heated by the resistance value of the material itself. Furthermore, an electric field is generated along the flow direction of the on-off pulse current, and electric field diffusion occurs. It is considered that this electric field diffusion effect and the above-described mechanical pressure of thermal diffusion contribute to the solid phase diffusion bonding and bring about the orientation of the metal crystal structure. In addition, this pulse energization joining (sintering) method has a faster diffusion rate and densification rate per unit time than the conventional continuous direct current energization joining (sintering) method. I know. In principle, the amount of diffusion by short-time pulse energization is small only in the surface layer. As a result, the bonding between adjacent blocks in this state is not yet complete in terms of bonding strength, but it is considered that the arrangement state of the metal lattice at the bonding interface is aligned in a more easily diffusing direction. Therefore, this bonded state is called temporary bonding. The temporarily joined energized electrode and cooling member are then heat treated in a heat treatment furnace of the heat treatment section 120. This is called a two-stage process. The heat treatment temperature and time vary depending on the material and size of the energizing electrode and the cooling member. By carrying out this two-stage heat treatment, energy that contributes to a large amount of diffusion is input, and there is a pretreatment state in which the temporary bonding is performed and the metal crystal orientation of the bonding interface is uniform, so solid phase diffusion bonding between the bonding surfaces is rapidly performed. The result is a complete integrated body with increased diffusion (depth), and its joint strength is comparable to the strength of the stainless steel material that constitutes the current-carrying electrode and cooling member. The value to be In addition, since the O-ring seal is not required on the joint surface between the energizing electrode and the cooling device as in the prior art, the O-ring seal can be used even when the sintering device having the cooling device according to the present invention is repeatedly used at a high frequency. It is possible to prevent the cooling fluid from leaking due to burning of the steel. The heat treatment unit 120 may be a vacuum heat treatment furnace having a known structure. The applied pressure, the voltage and current of the pulse current, the heat treatment temperature and time, and the like due to the pulse energization bonding vary depending on the material and size of the energization electrode and the cooling member. This heat treatment time is about 1/8 to 1/5 of the time required for conventional solid phase diffusion bonding, and is extremely advantageous in terms of energy saving effect and manufacturing cost. Of course, the other surface (non-joint surface) of the cooling member 61 may be detachably attached with a graphite energizing plate and a set screw shown in FIG. 1 as necessary.
[0016]
Example 1
As shown in FIG. 8, the material of the energizing electrode 4 and the cooling member 71 is the same stainless steel (SUS304), the diameter D is 100 mm, the length L of the energizing electrode is 220 mm, and the thickness W of the cooling member 71 is 35 mm. In this case, temporary bonding was performed by applying a DC pulse current of 3 to 12 V and a current of 2000 to 5000 A for 10 to 30 minutes. Thereafter, the temporarily joined current-carrying electrode and cooling member were subjected to a mutual diffusion heat treatment at a temperature of 1000 to 1200 ° C. for 60 to 120 minutes under an inert atmosphere to complete the joining. As a result, the energizing electrode 4 and the cooling member can be joined completely over the entire contact surface, and the pulse energizing pressure sintering apparatus equipped with the energizing electrode with the cooling device is repeatedly operated under the following conditions. Even after use, no cracks occurred on the joint surface, and no leakage of the cooling fluid occurred.
Example 1
Use cycle 15 minutes
Sintering temperature 1200 ℃
Sintering pressure 30MPa
Use count 50 times
Example 2
Use cycle 30 minutes
Sintering temperature 2000 ℃
Sintering pressure 50MPa
Use count 50 times
[0017]
In the embodiment shown in FIGS. 5 and 6, an example in which a single cooling member is joined to the front end surface of the energizing electrode is shown. However, as shown in FIG. 9, a pair of cooling members joined together by the joining method described above. The members 71a and 72a may constitute one cooling device 7a, and the cooling device may be joined to the tip of the energizing electrode in the same manner as in the above embodiment. In FIG. 9, a groove 75a defining a cooling passage is formed on one surface 73a of one cooling member 71a, and a surface (surface facing the surface 73a) 74a of the other cooling member 72a communicates with the groove 75a. A pair of possible ports 76a is formed, and the surface 73a of the cooling member 71a and the surface 74a of the cooling member 72a are joined in the same manner as in the above embodiment to form the cooling device 7a. Further, the cooling member 72a of the cooling device 7a is joined to the distal end surface 43 of the energizing electrode 4 in the same manner as in the above embodiment in a state where the pair of ports 75a are aligned with the pair of flow paths 44 of the energizing electrode. In this case, a pair of cooling members and energization electrodes may be stacked and joined together at one time. Note that three or more cooling members may be provided and cooling passages formed on the joint surfaces of the respective cooling members may be connected in series or in parallel so as to be able to communicate with the flow path formed in the energizing electrode. By doing so, the cooling effect can be further improved.
In the above-described two embodiments, the groove is shown in an annular shape. However, the groove is not necessarily in an annular shape, and a wave shape such as a groove 75b formed in the cooling member shown in FIG. The shape may be sufficient. In the case of the shape shown in FIG. 10, it is necessary that the end portion 75b of the groove communicates with the pair of passages of the energizing electrode.
[0018]
11 and 12, an assembly of a current-carrying electrode and a cooling device according to the present invention is shown. This assembly is suitable for application to the upper energizing electrode of the pulse energizing pressure sintering apparatus shown in FIG. In the sintering apparatus shown in FIG. 3, the upper energizing electrode 4 'is much longer than the lower energizing electrode 4, and the upper energizing electrode and the cooling member to be joined thereto are connected by a pulse energizing pressure sintering apparatus. It becomes very difficult to set between a pair of current-carrying electrodes. Therefore, the current-carrying electrode is divided into two parts in the longitudinal direction, and the cooling member is joined to the tip surface of the tip part so as to be the same as when the cooling member is joined to the lower current-carrying electrode 4.
That is, in the figure, the energizing electrode 4c ′ is a base end portion 4c fixed to the upper support plate 23. ₁ 'And the tip portion 4c ₂ It is divided into ′. In addition, about the same component as embodiment of FIG. 3, the same reference number is attached | subjected and description is abbreviate | omitted. Base end portion 4c ₁ 'Electrode body 41c ₁ ′ Is fixed to the upper support plate 23 by the same method as the energizing electrode 4 in FIG. 3, and a flange portion is formed at the tip (lower end in FIG. 11). Tip portion 4c ₂ 'Electrode body 41c ₂ ′ At one end (the upper end in FIGS. 11 and 12) is the flange portion 42c. ₂ ′ Is formed, and the flange portion has a plurality of set screws 48c. ₂ ′ (Only one is shown in FIG. 12) ₁ It is removably attached to the flange part of ′. Tip portion 4c ₂ ′ End surface 43c ₂ A cooling device 7c composed of a single cooling member 71c having the same structure as that of the above embodiment is attached to 'by the same method as the joining method described above. Base end portion 4c ₁ 'And tip part 4c ₂ An O-ring seal that surrounds the flow path is provided on the attachment surface with ′ to prevent the cooling fluid from leaking outside through the attachment surface.
[0019]
According to the assembly of the energizing electrode and the cooling device, even when the energizing electrode itself is elongated in the axial direction and it is difficult to attach the cooling device to the tip of the energizing electrode by the pulse energization pressure bonding method, it can be easily joined. Become. In addition, since the mounting position of the O-ring seal is away from the cooling device and the tip of the energizing electrode itself is cooled, the heat transmitted to the O-ring seal is reduced, and the O-ring seal is damaged by the heat. In addition, it is possible to prevent damage due to elasticity and plastic deformation of the O-ring mounting portion.
Note that the cooling device joined to the tip portion of the divided energization electrode is not limited to that shown in FIGS. 11 and 12, and may of course have the structure shown in FIG. Needless to say, a stainless steel and / or graphite energizing plate may be attached to the front end surface (non-joint surface) of the cooling member. In the above embodiment, the case where the cooling member is made of stainless steel has been described. However, the member may be made of Inconel.
[0020]
【effect】
According to the present invention,
(A) Since there is no welded part even if the energized electrode is repeatedly heated and cooled by repeated use of a pulse energized pressure sintering apparatus or pulse energized joining apparatus for a short time, leakage of water due to strain cracking of the cooling apparatus due to thermal stress occurs. Can be safely operated for a long time,
(B) Since the O-ring seal at the close position between the current-carrying electrode and the cooling device attached thereto can be omitted by solid phase diffusion bonding, leakage due to breakage of the O-ring seal can be prevented.
(C) The water leakage problem that causes the O-ring seal failure due to the elastic deformation (or plastic deformation) due to heat softening in the cooling device at the tip during high-temperature sintering is because the O-ring seal is omitted. It does not occur, and because it can cool efficiently, it is prevented from elastic / plastic deformation and can exhibit stable performance as a sintering machine for production.
(D) Compared with conventional solid phase diffusion bonding, the heat treatment time is as short as about 1/8 to 1/5, and the manufacturing cost is low and a highly reliable cooling device can be configured.
It is possible to produce effects such as these.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a conventional cooling device for current-carrying electrodes.
FIG. 2 is a plan view showing another example of a conventional cooling device for current-carrying electrodes.
FIG. 3 is a side view of an example of a pulse energizing pressure sintering machine provided with an energizing device having a cooling device of the present invention.
FIG. 4 is an enlarged cross-sectional view illustrating a connection state between a lower energization electrode and a driving device.
FIG. 5 is a cross-sectional view of a part of a current-carrying electrode to which an embodiment of a cooling device according to the present invention is joined.
6 is a plan view of a cooling member of the cooling device shown in FIG. 5, showing the shape of a groove. FIG.
FIG. 7 is a schematic view for explaining the joining of the cooling device of the present invention and a current-carrying electrode.
FIG. 8 is a side view showing a dimensional relationship between a current-carrying electrode and a cooling device.
FIG. 9 is a cross-sectional view of a part of a current-carrying electrode to which another embodiment of the cooling device according to the present invention is joined.
FIG. 10 is a view showing a modified example of a groove formed in the cooling member.
FIG. 11 is a sectional view showing an assembly of a current-carrying electrode and a cooling device according to the present invention.
12 is an enlarged cross-sectional view of a part of FIG.
[Explanation of symbols]
1, 1c Pulse current pressure sintering machine
4, 4 ', 4c' conducting electrode
44, 44c ₂ ′ Flow path
7, 7 ', 7a, 7b, 7c' Cooling device
71, 71a, 71b, 71c 'Cooling member 72a Cooling member
75, 75a, 75c 'groove

Claims

An energizing electrode for pulse energized pressure sintering and / or joining apparatus for passing a pulse current from a power source to a material to be processed, and a flow path for a cooling fluid formed by extending in the longitudinal direction is opened inside. In the cooling device attached to the front end surface of the energizing electrode and blocking heat transfer from the material to be processed to the energizing electrode,
The cooling device has one cooling member joined to the tip surface of the energizing electrode, and a cooling passage communicating with the flow path is formed on a surface joined to the end surface of the cooling member,
The energization electrode and the cooling member are temporarily joined by passing a DC pulse current of a predetermined voltage and current under pressure of a predetermined pressure in a state where they are in contact with each other on the bonding surface,
The cooling device for energized electrodes, wherein the temporarily bonded energized electrode and the cooling member are heat-bonded under a predetermined condition in a heat treatment furnace and are finally bonded.

The cooling device for energized electrodes according to claim 1, wherein a joining surface of the energized electrode and the cooling member is a mirror surface.

An energizing electrode for pulse energized pressure sintering and / or joining apparatus for passing a pulse current from a power source to a material to be processed, and a flow path for a cooling fluid formed by extending in the longitudinal direction is opened inside. In the cooling device attached to the front end surface of the energizing electrode and blocking heat transfer from the material to be processed to the energizing electrode,
The cooling device includes at least two cooling members bonded to each other, a cooling passage is formed in at least one of the bonding surfaces of the cooling member, and one of the energizing electrodes is provided in one of the cooling members. A port that connects the flow path and the cooling passage is formed,
The at least two cooling members to be joined to each other, and the energization electrode and the cooling member to be joined to the energization electrode are in contact with each other at a joining surface and are subjected to a predetermined voltage and current under a predetermined pressure. DC pulse current is passed and temporarily joined,
The cooling device for energized electrodes in which the temporarily bonded cooling members and the energized electrode and the cooling member are heat-bonded under a predetermined condition in a heat treatment furnace and are finally bonded.

The cooling device for energized electrodes according to claim 3, wherein the joining surface between the cooling members and the joining surface between the energizing electrode and the cooling member are mirror surfaces.

5. The cooling device for energizing electrodes according to claim 1, wherein the cooling member is made of stainless steel or Inconel and the energizing electrode is made of stainless steel, and the heat treatment is performed at 900 ° C. in a vacuum atmosphere. A cooling device for energized electrodes, which is performed at a temperature of 1200 ° C. for 60 minutes to 120 minutes.

An energization electrode for pulse energization pressure sintering and / or joining apparatus for passing a pulse current from a power source through a material to be processed, and a flow path for a cooling fluid that extends in a longitudinal direction and opens at a front end surface is formed. In the assembly of the energized electrode and the cooling device that is attached to the tip surface of the energized electrode and blocks heat transfer from the material to be processed to the energized electrode,
The current-carrying electrode comprises a plurality of parts removably connected to each other,
The cooling device has one cooling member joined to the tip surface of the tip portion of the energization electrode, and a cooling passage communicating with the flow path is formed on a surface joined to the tip surface of the cooling member. And
The energization electrode and the cooling member are temporarily joined by passing a DC pulse current of a predetermined voltage and current under pressure of a predetermined pressure in a state where they are in contact with each other on the bonding surface,
The temporarily-bonded energized electrode and the cooling member are heat-bonded under a predetermined condition in a heat treatment furnace and are finally bonded to each other and the assembly of the energized electrode and the cooling device.

The assembly of the energizing electrode and the cooling device according to claim 6, wherein a joining surface of the energizing electrode and the cooling member is a mirror surface.

An energization electrode for pulse energization pressure sintering and / or joining apparatus for passing a pulse current from a power source through a material to be processed, and a flow path for a cooling fluid that extends in a longitudinal direction and opens at a front end surface is formed. In the assembly of the energized electrode and the cooling device that is attached to the tip surface of the energized electrode and blocks heat transfer from the material to be processed to the energized electrode,
The current-carrying electrode comprises a plurality of parts removably connected to each other,
The cooling device includes at least two cooling members bonded to each other, a cooling passage is formed in at least one of the bonding surfaces of the cooling member, and one of the energizing electrodes is provided in one of the cooling members. A port that connects the flow path and the cooling passage is formed,
The at least two cooling members to be joined to each other, and the tip portion of the energizing electrode and the cooling member to be joined to the tip portion are in contact with each other on the joint surface under a predetermined pressure under a predetermined pressure. , The DC pulse current of the current is passed and temporarily joined,
The assembly of the energized electrode and the cooling device in which the temporarily bonded cooling members and the energized electrode and the cooling member are heat-bonded under a predetermined condition in a heat treatment furnace and are finally bonded.

The assembly of the energizing electrode and cooling device according to claim 8, wherein the joining surface between the cooling members and the joining surface between the energizing electrode and the cooling member are mirror surfaces.

10. The assembly of the energizing electrode and the cooling device according to claim 6, wherein the cooling member is made of stainless steel or Inconel and the energizing electrode is made of stainless steel, and the heat treatment is performed in a vacuum atmosphere. The assembly of the current-carrying electrode and the cooling device performed at a temperature of 900 ° C. to 1200 ° C. for 60 minutes to 120 minutes.