JP2004079563A

JP2004079563A - Ultrasonic welding horn for electrolytic capacitor and method of manufacturing electrolytic capacitor

Info

Publication number: JP2004079563A
Application number: JP2002233465A
Authority: JP
Inventors: Tatsuro Kubonai; 久保内　達郎; Takeshi Kubota; 久保田　健
Original assignee: Nippon Chemi Con Corp
Current assignee: Nippon Chemi Con Corp
Priority date: 2002-08-09
Filing date: 2002-08-09
Publication date: 2004-03-11
Anticipated expiration: 2022-08-09
Also published as: JP4168694B2

Abstract

<P>PROBLEM TO BE SOLVED: To enable a joint welded by ultrasonic bonding between a terminal rivet and a tab to be improved in weld strength and connection reliability. <P>SOLUTION: The tab 36 led out from a capacitive element 24 is laid on the terminal rivet 34 where the tab 36 is to be welded, and ultrasonic energy is given by an ultrasonic welding horn used for forming an electrolytic capacitor to the weld part 44 of the terminal rivet 34 to the tab 36 as the tab 36 is pressed. The ultrasonic welding horn is equipped with a first pointed projection 12 and second projections 16 and 18 which are lower than the first projection 12 and provided so as to surround the first projection 12, and a method of manufacturing the electrolytic capacitor comprises a process of bonding the terminal rivet 34 to the tab 36 by ultrasonic welding. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、アルミニウム電解コンデンサ等の電解コンデンサのターミナルリベットと引出しリード（タブ）との超音波溶接等に使用される超音波溶接ホーン、この超音波溶接ホーンを用いた電解コンデンサの製造方法に関する。
【０００２】
【従来の技術】
アルミニウム電解コンデンサでは、コンデンサ素子を封入する外装ケースの封口板にターミナルリベットが固定され、このリベットにコンデンサ素子から引き出されたタブをワッシャ等の加締めにより取り付けるとともに、タブをリベットの端部に超音波によって金属接合することにより、ターミナルリベットとタブとの機械的な結合とともに、電気的な接続が行われている。このような機械的な金属間接合を超音波接合によって補完するのは、信頼性の高い接合状態を実現することにある。このようなタブとターミナルリベットとを超音波を用いて接合する技術には例えば、特許第２８１１７３２号「アルミ電解コンデンサの製造方法」がある。
【０００３】
【発明が解決しようとする課題】
ところで、このアルミ電解コンデンサの製造方法では、被溶接部材に超音波エネルギを付与する超音波溶接ホーンが使用され、この超音波溶接ホーンには、複数個の円錐台形状の突起が形成されたものや、複数個の小突起が形成されたものがある。これらホーンの突起の高さがタブの厚みより低く、複数の突起の各頂面で超音波溶接が行われているので、接合されたリベットとタブとの間に境界面が生じるため、両者の接続強度が十分でない。この接続強度を高めるには、溶接処理に必要な超音波エネルギの増大が考えられ、複数枚のタブを重ねて溶接する場合には、タブの厚みや積層数が増すほどに超音波エネルギを増大させ、その超音波の印加時間を長くする必要がある。
【０００４】
しかしながら、増大させた超音波エネルギにタブが耐えられない場合には、タブが変形し、その変形量は超音波エネルギ量によって大きくなり、溶接部分やその近傍に亀裂や破断を生じさせ、場合によってはタブ間にズレを生じさせる。特に、タブ間に幅方向のズレが生じると、溶接面が縮小する結果、溶接不良や接続強度の低下を来たし、接続の信頼性を低下させるおそれがある。
【０００５】
そこで、本発明は、ターミナルリベットとタブとの超音波接合の強度を高め、接続の信頼性の向上を図ることができる電解コンデンサ用超音波溶接ホーン、及び電解コンデンサの製造方法を提供することを目的とする。
【０００６】
【課題を解決するための手段】
係る課題を解決した本発明の電解コンデンサ用超音波溶接ホーン、及び電解コンデンサの製造方法の構成は以下の通りである。
【０００７】
本発明の電解コンデンサ用超音波溶接ホーンにおいて、請求項１に係る電解コンデンサ用超音波溶接ホーンは、溶接すべきターミナルリベット３４上にコンデンサ素子２４から引き出されたタブ３６を重ね、該タブを加圧しながら前記ターミナルリベットと前記タブとの溶接部４４に超音波エネルギを付与する電解コンデンサ用超音波溶接ホーンであって、尖鋭部を持つ第１の突部１２と、この第１の突部を包囲して形成され、前記第１の突部より高さの低い第２の突部１６、１８とを備えたことを特徴とする。
【０００８】
即ち、溶接すべきターミナルリベットの上に重ねられたタブの溶接部に第１の突部を当接すると、該突部が尖鋭部を備えているので、該尖鋭部が加圧によってタブ上に位置決めされ、この部分から超音波溶接が開始される。加圧を持続することで、軟化した溶接部に第１の突部が進入し、この第１の突部の周囲に形成されている凹部に軟化したタブの金属が進入するとともに、第２の突部が溶接部に進行し、主たる溶接部分が第２の突部で包囲されることになる。同時に、主たる溶接部分を包囲して第２の突部での超音波溶接が行われる。
【０００９】
このように、超音波溶接ホーンの中央部にある第１の突部を中心に超音波溶接が行われると、超音波エネルギが溶接部の中央に集中し、その溶接部分が尖鋭化し、タブ側の金属とリベット側の金属との接合面が一体化されるので、ターミナルリベットとタブとの接合強度が高められ、信頼性の高い接合状態が得られる。その結果、溶接時間の低減とともに、溶接に要する超音波エネルギを削減でき、溶接部の尖鋭化は、タブのズレ防止にも寄与する。
【００１０】
また、尖鋭部を持つ第１の突部を中心に超音波エネルギがタブに加わると、溶接部分が尖鋭化し、この部分を中心に積層状のタブが反り返る現象が瞬間的に起こることが予想されるが、第１の突部の周囲にある第２の突部がタブの溶接部の周囲を押圧し、主たる溶接部分を第２の突部によって生じる従たる溶接部分で包囲する結果、反り返り等のタブの変形が抑制され、溶接部分が第１の突部を中心に第２の突部で包囲される範囲に波及し、接合強度の高い溶接とともに、タブのズレが防止される。しかも、第１の突部と第２の突部との間の凹部には、タブ側の溶融金属が進入して立壁状の突部が形成され、溶接範囲外への流出が防止される。さらに、溶接時間及び溶接エネルギの削減により、超音波溶接ホーンを磨耗から防護でき、その耐用時間を延ばすことが可能となる。
【００１１】
本発明の電解コンデンサ用超音波溶接ホーンにおいて、請求項２に係る電解コンデンサ用超音波溶接ホーンは、前記第１の突部が前記タブの厚みより高く設定されたことを特徴とする。即ち、第１の突部をタブの厚みより高く設定することにより、溶接時、タブを超えてリベットに第１の突部を食い込ませることができ、リベットとタブとの溶接強度を向上させることができる。
【００１２】
本発明の電解コンデンサ用超音波溶接ホーンにおいて、請求項３に係る電解コンデンサ用超音波溶接ホーンは、前記第１の突部が尖鋭部を持つ柱状であることを特徴とする。即ち、柱状部を備え、その高さを任意に設定して溶接部分を離間させることができる。
【００１３】
本発明の電解コンデンサ用超音波溶接ホーンにおいて、請求項４に係る電解コンデンサ用超音波溶接ホーンは、前記第２の突部が点状の尖鋭部、連続した線状又は曲線状の尖鋭部を備えたことを特徴とする。即ち、第２の突部の尖鋭部の形態を点状、線状又は曲線状とすることにより、超音波エネルギパターンを所望の形態に制御することができる。点状であれば、超音波エネルギを集中させることができるとともに、その点を中心にしたパターンが得られる。また、線状とすれば、一定の幅を持つエネルギパターンを形成でき、曲線状とすれば、その曲線に沿ったエネルギパターンを形成することができる。このようなパターンを単独又は組み合わせることにより、所望の溶接範囲にすることができる。そして、リベットに溶接されるタブを所定範囲で押圧させることができ、例えば、電解液が付着したタブであっても、リベットからずれることがなく、積層状態にあるタブのズレをも防止できる。
【００１４】
本発明の電解コンデンサ用超音波溶接ホーンにおいて、請求項５に係る電解コンデンサ用超音波溶接ホーンは、前記第２の突部の周縁側に角錐面（傾斜面２０）を備え、その角部に面取り部２２を備えたことを特徴とする。即ち、面取り部により、角部が鈍角化するため、溶接後のタブとの密着を防止でき、取外しが容易になる。
【００１５】
本発明の電解コンデンサ用超音波溶接ホーンにおいて、請求項６に係る電解コンデンサ用超音波溶接ホーンは、前記第２の突部の頂部に平坦面を有することを特徴とする。即ち、第２の突部の頂部の平坦面が主たる溶接部分の周囲を少なからず押圧するため、溶接時のタブの反り返りを防止でき、溶接時間を短縮することができる。
【００１６】
本発明の電解コンデンサの製造方法において、請求項７に係る電解コンデンサの製造方法は、封口板３０に貫通させて固定されたリベット（ターミナルリベット３４）にコンデンサ素子２４から引き出されたタブ３６を重ねて超音波エネルギによって溶接する電解コンデンサの製造方法であって、前記リベット上に重ねられた前記タブと、中央部に尖鋭部を持つ第１の突部１２、この第１の突部を包囲して形成され、該第１の突部より低い第２の突部１６、１８を備えた超音波溶接ホーンとを当接して加圧させる処理と、前記超音波溶接ホーンから前記タブと前記リベットとの溶接部４４に超音波エネルギを付与する処理とを含むことを特徴とする。
【００１７】
即ち、この電解コンデンサの製造方法は、既に述べた電解コンデンサ用超音波溶接ホーンを用いたものであるから、溶接時のタブの変形やズレが抑制され、溶接強度が高く、信頼性の高い接続状態が得られ、電解コンデンサにおいて、振動応力に対する耐力を備えた端子構造を実現できる。この場合、リベットに重ねられたタブに第１の突部を当接して加圧させ、その加圧及び溶接の進行とともに第２の突部がタブ上に当接される結果、第１の突部による超音波溶接ホーンの溶接部分への位置決めと、第２の突部によるタブの押え込みで、タブの位置ずれを防止することができる。
【００１８】
本発明の電解コンデンサの製造方法において、請求項８に係る電解コンデンサの製造方法は、前記リベットと前記タブとを溶接させ、前記第１の突部１２によって第１の凹部４６、前記第１及び第２の突部の間隔内に立壁部４８、前記第２の突部によって前記立壁部を包囲して前記第１の凹部より浅い第２の凹部５０、５２を形成する処理を含むことを特徴とする。即ち、この処理によって、リベット上にタブが確実に溶接される。
【００１９】
本発明の電解コンデンサの製造方法において、請求項９に係る電解コンデンサの製造方法は、溶接時、前記リベットに重ねられた前記タブを前記超音波溶接ホーンで加圧し、前記タブと前記リベットとの前記溶接部を前記超音波溶接ホーンで包囲することを特徴とする。即ち、タブの反り返りやズレを防止でき、タブとリベットとの接続強度を高めることができる。
【００２０】
本発明の電解コンデンサの製造方法において、請求項１０に係る電解コンデンサの製造方法は、溶接時、前記タブに前記超音波溶接ホーンの超音波エネルギを前記タブと同一方向に付与することを特徴とする。即ち、超音波振動がタブと同一方向に付与されるので、タブの幅方向へのズレが防止でき、リベットとタブとの接続範囲を広くすることができる。
【００２１】
【発明の実施の形態】
図１は、本発明の実施の形態に係る電解コンデンサ用超音波溶接ホーンを示している。
【００２２】
この電解コンデンサ用超音波溶接ホーンは、鋼等の金属材料を用いて例えば、十字形に形成されたホーンの先端に単一又は複数のホーン部４が形成されるとともに、図示しない超音波振動源から超音波エネルギが付与される構成である。
【００２３】
各ホーン部４は角柱状の柱状部１０の頂部にローレット加工により形成され、例えば、図２に示すように、尖鋭部を持つ第１の突部として、中央部に突部１２、この突部１２を包囲する凹部として断面Ｖ字状の凹部１４、この凹部１４を包囲して突部１２より高さの低い第２の突部として複数の突部１６、１８を備えている。図３及び図４は図２に示したホーン部の各断面を示しており、図３の（Ａ）は図２のＩＩＩＡ−ＩＩＩＡ線断面、図３の（Ｂ）は図２のＩＩＩＢ−ＩＩＩＢ線断面、図４の（Ａ）は図２の　ＩＶＡ−ＩＶＡ　線断面、図４の（Ｂ）は図２の　ＩＶＢ−ＩＶＢ　線断面である。
【００２４】
突部１２は、底面側を正方形とし、点状の尖鋭部を持つ四角錐形であって、鋭角状の頂角を備え、その角度θ_１は例えば、８０°であり、突部１２を形成する各側面部は二等辺三角形である。この突部１２の高さｈ_１は図３の（Ａ）に示すように、ホーン部４で最も高く、この高さｈ_１は被溶接部材であるタブ（図６）の厚さｔ及び溶接深さに応じて設定される。
【００２５】
凹部１４は、突部１２の底縁を最深部とし、突部１２、１６間、突部１２、１８間及び突部１６、１８間に形成されて井桁状である。
【００２６】
突部１６は、突部１２の底縁長と同一の二辺部を備えた長方形状の底面とし、２つの二等辺三角形と台形とからなる線状の尖鋭部を備えた四角錐であって、凹部１４を挟んで突部１２の各底縁に平行に突部１２を包囲して配置されている。この突部１６において、台形の側面が成す角度、即ち、尖鋭部の角度θ_２は、鋭角であって角度θ_１より鋭く、例えば、６０°に設定されている。また、この突部１６の高さｈ_２は図３の（Ａ）に示すように突部１２より低く、この高さｈ_２は突部１２と同様に、被溶接部材であるタブ（図６）の厚さｔ及び溶接深さに応じて設定される。なお、突部１６を突部１２に向かって又はその反対方向に向かって湾曲させることで、上面視曲線状の尖鋭部からなる突部とし、中央の突部１２を包囲する形態を取ることもできる。
【００２７】
また、突部１８は、突部１６の短い側の底縁長と同一の底縁部を備えた正方形状の底面とし、４つの二等辺三角形からなる点状の尖鋭部を備えた四角錐であって、凹部１４を挟んで突部１２の対角線上の４箇所に配置されている。この突部１８において、尖鋭部が成す角度θ_３は、突部１６と同様に例えば、６０°に設定されている。突部１８の高さｈ_３は図４の（Ａ）に示すように突部１２より低く、この実施の形態では高さｈ_３は突部１６の高さｈ_２と同一であり、突部１２と同様に、被溶接部材であるタブ３６（図６）の厚さｔ及び溶接深さに応じて設定される。この場合、突部１６、１８の高さｈ_２、ｈ_３は異ならせてもよく、また、角度θ_２、θ_３を異ならせてもよい。
【００２８】
この実施の形態では、突部１６、１８を尖鋭部を備えた形状としてが、他の形態としては、突部の頂点を削り、頂部に平面部を形成してもよい。この平面部を有する突部は、その平面部が上面視円形状や、長方形、正方形、三角形等の多角形状とすることができる。また、この突部は、その平面部が長方形を湾曲させて上面視曲面状として突部１２を包囲するように形成してもよい。
【００２９】
そして、このホーン部４は、突部１２を中央にして突部１６、１８が突部１２を包囲して形成され、突部１２、１６、１８の外郭線は、突部１２の底面と相似形の正方形を成し、突部１２の中心が柱状部１０の中心に一致している。ホーン部４は角錐台形であって、周面部が台形状の傾斜面２０を備えているとともに、その角部に例えば、三角形状の面取り部２２が形成されている。この面取り部２２は、円弧面であってもよい。この場合、傾斜面２０と突部１６又は突部１８とは、傾斜面２０側の角度と突部１６、１８側の角度とが相違するため、外面側に角度θ_４の断面Ｖ字状の凹部を形成している。
【００３０】
次に、図５及び図６は、本発明の実施の形態に係る電解コンデンサの製造方法を示している。
【００３１】
電解コンデンサは、コンデンサ素子２４が封入される外装ケース２６を備えており、この外装ケース２６の開口部２８は封口板３０によって封止される。封口板３０は硬質合成樹脂板で形成され、上縁部には封止部材としてＯリング３２が取り付けられている。
【００３２】
封口板３０には、外部端子を構成するターミナルリベット３４が封口板３０へのインサート成形によって貫通、固定されており、封口板３０の内側に突出させたターミナルリベット３４と、コンデンサ素子２４から引き出された引出しリードとして、アルミニウム等の金属材料で形成された帯状の複数枚のタブ３６とは、ターミナルリベット３４をタブ３６の貫通孔３８（図６）に挿入し、且つ、ターミナルリベット３４に嵌合させたワッシャ４０の加締めによって固定されている。この場合、タブ３６の端部側が折り返されてターミナルリベット３４の端部側に重ねられている。
【００３３】
そして、ターミナルリベット３４に重ねられたタブ３６には、図６に示すように、本発明に係る超音波溶接ホーン（図１及び図２）のホーン部４が当接され、図示しない固定手段で位置決め固定された封口板３０のターミナルリベット３４に対向してホーン部４に矢印Ｆで示すように、加圧力とともに図示しない超音波溶接源から超音波エネルギが加えられる。この場合、突部１２の高さｈ_１は被溶接部材であるタブ３６の厚みｔより高く、突部１６、１８の高さｈ_２、ｈ_３は厚みｔより低く設定されている。即ち、これらの大小関係は、ｈ_１＞ｔ＞ｈ_２，ｈ_３である。なお、この大小関係は、ｈ_１＞ｈ_２，ｈ_３＞ｔとしてもよい。このように突部１６、１８の高さｈ_２、ｈ_３をタブ３６の厚みｔに対して高く設定することで、溶接時のタブ３６の反り返りを防止できるとともに、溶接時間を短縮してタブ３６の過度な変形を抑制できるという効果に加えて、突部１６、１８がターミナルリベット３４と当接してタブ３６とターミナルリベット３４とを接続するため、中央の突部１２による溶接部分の電気的な接続状態を強化できるという補完的な効果も得られる。
【００３４】
この超音波溶接において、ターミナルリベット３４に重ねられたタブ３６にホーン部４の突部１２が当接され、その尖鋭部が加圧によってタブ３６上に位置決めされ、この部分から超音波溶接が開始される。加圧を持続すると、超音波エネルギによって軟化したタブ３６を構成する金属中に突部１２がその高さｈ_１だけ進入するが、その際、突部１２及び突部１６、１８に沿って屈曲したタブ３６がターミナルリベット３４に密着するとともに、突部１２とともに一部のタブ３６の金属がターミナルリベット３４内に進入する。このとき、突部１２の周囲の凹部１４には、タブ３６の金属が進入し、溶接部４４中の主たる溶接部分が突部１２によって形成されるとともに、突部１６、１８側にも溶接が進行し、主たる溶接部分を包囲する従たる溶接部分が突部１６、１８側に形成されることにより、タブ３６がターミナルリベット３４に溶着し、溶接部４４が形成される。この実施の形態では、突部１２の高さｈ_１がタブ３６の厚みｔよりも高いため、溶接時、突部１２がターミナルリベット３４の端面より内側に進入し、その結果、ターミナルリベット３４の内部にタブ３６が入り込んでターミナルリベット３４とタブ３６とが溶接されるので、極めて高い接続強度が得られる。
【００３５】
しかも、ホーン部４の中央部にある突部１２を中心に超音波溶接が行われると、超音波エネルギが溶接部４４の中央に集中し、その溶接部分が尖鋭化し、タブ３６側の金属とターミナルリベット３４側の金属との接合面が一体化され、ターミナルリベット３４とタブ３６との接合強度が高められる。その結果、信頼性の高い接合状態が得られる。このような超音波溶接によれば、溶接時間や溶接に要する超音波エネルギを削減でき、溶接部４４の突部１２による尖鋭化は、タブ３６のズレ防止を図ることができる。
【００３６】
また、尖鋭部を持つ突部１２を中心に超音波エネルギがタブ３６に加わると、溶接部分が尖鋭化するが、この部分を中心に積層状のタブ３６が反り返る現象が瞬間的に生じても、突部１２の周囲にある突部１６、１８がタブ３６の溶接部４４の周囲を押圧し、主たる溶接部分を突部１６、１８によって生じる従たる溶接部分で包囲する結果、反り返り等のタブ３６の変形が抑制される。しかも、溶接部分が突部１２を中心に突部１６、１８で包囲される範囲に波及するので、溶接部４４がターミナルリベット３４の端面の全面となる結果、接合強度の高い溶接状態が得られ、タブ３６のズレも防止できる。
【００３７】
そして、このようなホーン部４を用いた超音波溶接では、例えば、図７に示すように、溶接部４４の中央部には突部１２によって角錐状の第１の凹部４６、ホーン部４側の凹部１４によって凹部４６を包囲する立壁部４８、突部１６、１８によって立壁部４８を包囲して凹部４６より浅い角錐状の複数の第２の凹部５０、５２が形成される。ホーン部４の突部１２と突部１６、１８との間の凹部１４が成す空間がタブ３６側の溶融金属溜まりとして機能するとともに、凹部１４の空間で進入した金属の立壁部４８が形成され、同時に、突部１６、１８で凹部５０、５２が形成される。従って、タブ３６の溶接部４４の中央には、容積が大きく、最大の深部を持つ角錐状の凹部４６、この凹部４６より浅く、小さい容積を持つ角錐状の４組の凹部５０、５２とともに、これら凹部４６、５０、５２を仕切る立壁部４８が形成される。立壁部４８の高さは、タブ３６の外面に一致している。この場合、立壁部４８の高さは、タブ３６の平面内に後退させてもよい。
【００３８】
このようなホーン部４を持つ超音波溶接ホーンを用いれば、溶接時間及び溶接エネルギを削減しても強力な溶接が可能となり、溶接時間を短縮できるので、タブ３６に生じる過度な変形を抑制できる上、超音波溶接ホーンを磨耗から防護でき、その耐用時間を延ばすことができる。
【００３９】
【実施例】
この超音波溶接ホーンの実施例１として、例えば、ホーン部４の中央部に頂角の角度（θ_１）＝８０°、高さ（ｈ_１）＝１．４ｍｍの正四角錐からなる突部１２、この突部１２の四隅部に正四角錐からなる突部１６、突部１２の辺部に突部１８を設け、各突部１６、１８の高さ（ｈ_２、ｈ_３）＝０．７ｍｍ、各頂角の角度（θ_２、θ_３）＝６０°とし、面取り部２２の高さ＝１ｍｍに形成した。
【００４０】
被溶接部材であるターミナルリベット３４は直径φ＝４ｍｍとし、タブ３６には厚さ＝０．２ｍｍ、幅＝７ｍｍの化成タブを６枚重ねとした。即ち、タブ３６の総厚み（ｔ）＝１．２ｍｍであることから、ホーン部４の中央部の突部１２の高さ（ｈ_１）はタブ３６の総厚み（ｔ）＝１．２ｍｍより０．２ｍｍだけ高く設定されている。
【００４１】
溶接条件として、加圧力＝４ｋｇ（ゲージ圧）で固定し、超音波振動はタブ３６の長手方向と同方向に設定するとともに、タブ３６に電解液が付着した状態、電解液が付着していない状態を設定した。
【００４２】
また、実施例２として、中央の突部１２を四角錐にするとともに、突部１２を包囲する各突部１６、１８の頂部に平面部を形成した変形ホーンと、従来ホーンとして、例えば、図８に示すように、ホーン部５４に複数の小突起５６が形成されたものを使用した。即ち、タブ３６の貫通孔３８にターミナルリベット３４を貫通させ、ワッシャ４０の加締めによってターミナルリベット３４にタブ３６を固定するとともに、折り返して重ねられたタブ３６にホーン部５４の小突起５６を加圧力Ｆで加圧させながら超音波エネルギを付与して溶接を行った。
【００４３】
このような条件下での溶接結果は表１の通りである。
【００４４】
【表１】

【００４５】
この実験結果から明らかなように、従来ホーンでは、電解液の有無を問わず、タブにズレやタブの一部に破損が発生した。これに対し、実施例１では、電解液の付着の有り、無しに拘わらず、タブズレやタブ破損は生じていない。また、実施例２では、僅かながらタブズレが生じる。しかし、実施例１及び実施例２では、溶接時間が短縮され、溶接に要する超音波エネルギを大幅に低減でき、タブズレが僅かに生じるもののタブ破損がないことから、接続強度を向上させることができ、信頼性の高い溶接が得られている。なお、溶接時に電解液がタブに付着している場合では、第２の突部に尖鋭部を持つ実施例１では、その尖鋭部が電解液を排除してタブを容易に加圧できるので、タブを確実に押さえ込み、タブズレを抑制できるのに対し、第２の突部の頂部に平面部を持つ実施例２では実用上問題にならない程度の僅かなタブズレが生じている。
【００４６】
なお、実施の形態では、中央の突部１２、その四隅部の突部１８を角錐状にしたが、円錐状としてもよく、また、突部１２は、尖鋭部を持つ円柱状又は角柱状等、柱状部を備えてもよい。柱状部の高さを加減することで、所望の溶接深度に設定することができる。
【００４７】
【発明の効果】
以上説明したように、本発明によれば、次の効果が得られる。
（ａ）　第１の突部を中心に溶接を行うことができるので、ターミナルリベットとタブとの溶接強度を向上させることができ、第１の突部の周囲にある複数の第２の突部で溶接部のタブを押圧するとともに溶接するので、溶接時のタブの変形やズレを防止でき、接続の信頼性の向上を図ることができる。
（ｂ）　第１の突部を中心に溶接を行うので、溶接時間を大幅に低減できるとともに、溶接に要する超音波エネルギを小さくでき、溶接によるタブの亀裂、破断等の損傷の発生を防止でき、タブとターミナルリベットとの溶接の信頼性を高めることができる。
（ｃ）　溶接時間や溶接時の超音波エネルギを削減できるため、ホーンの突部の先端部分を磨耗から防護でき、ホーン寿命を延ばすことができるとともに、安定した溶接を長期間に亘って維持することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係る超音波溶接ホーンを示す側面図である。
【図２】超音波溶接ホーンのホーン部を示す平面図である。
【図３】図２に示すホーン部の各断面を示し、（Ａ）は図２のＩＩＩＡ−ＩＩＩＡ線断面図、（Ｂ）は図２のＩＩＩＢ−ＩＩＩＢ線断面図である。
【図４】図２に示すホーン部の各断面を示し、（Ａ）は図２のＩＶＡ　−　ＩＶＡ線断面図、（Ｂ）は図２のＩＶＢ　−ＩＶＢ　線断面図である。
【図５】本発明の実施の形態に係る電解コンデンサの製造方法における製造途上の電解コンデンサの一部を示す図である。
【図６】ターミナルリベットとタブとの溶接を示す図である。
【図７】ターミナルリベットとタブとの溶接部を示す部分平面図である。
【図８】従来の超音波溶接ホーン及び電解コンデンサの製造方法を示す側面図である。
【符号の説明】
１２　第１の突部
１６、１８　第２の突部
２０　傾斜面（角錐面）
２２　面取り部
２４　コンデンサ素子
３０　封口板
３４　ターミナルリベット
３６　タブ
４４　溶接部
４６　第１の凹部
４８　立壁部
５０、５２　第２の凹部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic welding horn used for ultrasonic welding of a terminal rivet of an electrolytic capacitor such as an aluminum electrolytic capacitor and a lead (tab), and a method of manufacturing an electrolytic capacitor using the ultrasonic welding horn.
[0002]
[Prior art]
In aluminum electrolytic capacitors, terminal rivets are fixed to the sealing plate of the outer case that encloses the capacitor element.A tab drawn out of the capacitor element is attached to this rivet by caulking with a washer, and the tab is attached to the end of the rivet. The metal connection by the sound wave provides an electrical connection as well as a mechanical connection between the terminal rivet and the tab. The complementation of such mechanical metal-to-metal bonding by ultrasonic bonding is to realize a highly reliable bonding state. As a technique for joining such a tab and a terminal rivet using ultrasonic waves, for example, there is Japanese Patent No. 2811732 “Method of manufacturing aluminum electrolytic capacitor”.
[0003]
[Problems to be solved by the invention]
By the way, in this method for manufacturing an aluminum electrolytic capacitor, an ultrasonic welding horn for applying ultrasonic energy to a member to be welded is used, and the ultrasonic welding horn has a plurality of truncated conical protrusions formed thereon. Also, there are some in which a plurality of small projections are formed. Since the height of the projections of these horns is lower than the thickness of the tab, and ultrasonic welding is performed on each top surface of the plurality of projections, a boundary surface is created between the joined rivet and the tab, so that both of them are formed. Insufficient connection strength. In order to increase the connection strength, it is conceivable to increase the ultrasonic energy required for the welding process. When multiple tabs are overlapped and welded, the ultrasonic energy increases as the thickness of the tabs and the number of layers increase. It is necessary to make the application time of the ultrasonic wave longer.
[0004]
However, if the tab cannot withstand the increased ultrasonic energy, the tab deforms, and the amount of deformation increases with the amount of ultrasonic energy, causing cracks and breaks at and near the welded portion, and in some cases, Causes a gap between the tabs. In particular, if the tabs are misaligned in the width direction, the welding surface is reduced, resulting in poor welding or a decrease in connection strength, which may reduce the reliability of the connection.
[0005]
Therefore, the present invention provides an ultrasonic welding horn for an electrolytic capacitor capable of increasing the strength of ultrasonic bonding between a terminal rivet and a tab and improving the reliability of connection, and a method of manufacturing an electrolytic capacitor. Aim.
[0006]
[Means for Solving the Problems]
The configuration of the ultrasonic welding horn for an electrolytic capacitor and the method for manufacturing an electrolytic capacitor according to the present invention which has solved the above problems is as follows.
[0007]
In the ultrasonic welding horn for an electrolytic capacitor according to the present invention, the ultrasonic welding horn for an electrolytic capacitor according to claim 1 overlaps a tab 36 drawn from the capacitor element 24 on a terminal rivet 34 to be welded, and adds the tab. An ultrasonic welding horn for an electrolytic capacitor for applying ultrasonic energy to a welded portion 44 between the terminal rivet and the tab while pressing, the first projected portion 12 having a sharp portion, and the first projected portion. It is characterized by comprising

second projections

16 and 18 formed so as to surround and having a lower height than the first projection.
[0008]
That is, when the first projection comes into contact with the welding portion of the tab overlapped on the terminal rivet to be welded, the projection has a sharp portion, and the sharp portion is pressed onto the tab by pressing. The ultrasonic welding is started from this position. By maintaining the pressurization, the first protrusion enters the softened welded portion, the metal of the softened tab enters the recess formed around the first protrusion, and the second protrusion is formed. The protrusion advances to the welded portion, and the main welded portion is surrounded by the second protrusion. At the same time, ultrasonic welding at the second projection is performed surrounding the main welding portion.
[0009]
As described above, when the ultrasonic welding is performed around the first protrusion at the center of the ultrasonic welding horn, the ultrasonic energy is concentrated at the center of the welded portion, the welded portion is sharpened, and the tab side is formed. The joining surface between the metal and the rivet-side metal is integrated, so that the joining strength between the terminal rivet and the tab is increased, and a highly reliable joining state is obtained. As a result, the welding time can be reduced and the ultrasonic energy required for welding can be reduced, and sharpening of the welded portion also contributes to preventing displacement of the tab.
[0010]
Also, when ultrasonic energy is applied to the tab around the first projection having the sharp portion, the welded portion is sharpened, and a phenomenon in which the laminated tab warps around this portion is expected to occur instantaneously. However, the second protrusion around the first protrusion presses the periphery of the tub weld and surrounds the main weld with the secondary weld created by the second protrusion, resulting in warpage, etc. Of the tab is suppressed, the welded portion spreads around the first protrusion to the area surrounded by the second protrusion, and welding with high joining strength is prevented, and the tab is prevented from being displaced. Moreover, in the recess between the first projection and the second projection, the molten metal on the tub side enters to form a vertical wall-shaped projection, thereby preventing the metal from flowing out of the welding range. Further, the reduction of welding time and welding energy allows the ultrasonic welding horn to be protected from abrasion and its service life to be extended.
[0011]
In the ultrasonic welding horn for an electrolytic capacitor according to the present invention, the ultrasonic welding horn for an electrolytic capacitor according to claim 2 is characterized in that the first projection is set higher than the thickness of the tab. That is, by setting the first protrusion to be higher than the thickness of the tab, it is possible to cause the first protrusion to bite into the rivet beyond the tab during welding, thereby improving the welding strength between the rivet and the tab. Can be.
[0012]
In the ultrasonic welding horn for an electrolytic capacitor according to the present invention, the ultrasonic welding horn for an electrolytic capacitor according to claim 3 is characterized in that the first projection has a columnar shape having a sharp portion. That is, a columnar portion is provided, and the height of the columnar portion can be set arbitrarily to separate the welded portions.
[0013]
In the ultrasonic welding horn for an electrolytic capacitor according to the present invention, in the ultrasonic welding horn for an electrolytic capacitor according to claim 4, the second projection has a pointed sharp portion, a continuous linear or curved sharp portion. It is characterized by having. That is, the ultrasonic energy pattern can be controlled to a desired form by setting the shape of the sharp portion of the second projection to a point, a line, or a curve. If it is a point, the ultrasonic energy can be concentrated, and a pattern centered on the point can be obtained. Further, if it is linear, an energy pattern having a certain width can be formed, and if it is curved, an energy pattern along the curve can be formed. By using such patterns alone or in combination, a desired welding range can be obtained. Then, the tab to be welded to the rivet can be pressed within a predetermined range. For example, even if the tab has the electrolytic solution attached thereto, it does not deviate from the rivet, and the displacement of the tab in the stacked state can be prevented.
[0014]
In the ultrasonic welding horn for an electrolytic capacitor according to the present invention, the ultrasonic welding horn for an electrolytic capacitor according to claim 5 is provided with a pyramidal surface (inclined surface 20) on a peripheral side of the second protrusion, and at a corner thereof. It is characterized by having a chamfer 22. That is, the corners are obtuse by the chamfered portions, so that adhesion to the tabs after welding can be prevented, and removal becomes easy.
[0015]
The ultrasonic welding horn for an electrolytic capacitor according to the present invention is characterized in that the ultrasonic welding horn for an electrolytic capacitor according to claim 6 has a flat surface on the top of the second projection. That is, since the flat surface at the top of the second protrusion presses the periphery of the main welded portion, the warpage of the tab at the time of welding can be prevented, and the welding time can be shortened.
[0016]
In the method for manufacturing an electrolytic capacitor according to the present invention, in the method for manufacturing an electrolytic capacitor according to claim 7, a tab 36 drawn out of the capacitor element 24 is overlapped with a rivet (terminal rivet 34) penetrating through the sealing plate 30 and fixed. A method of manufacturing an electrolytic capacitor to be welded by ultrasonic energy, wherein said tab is superimposed on said rivet, a first protrusion 12 having a sharp portion at a central portion, and surrounding said first protrusion. And pressing the ultrasonic welding horn provided with the

second projections

16 and 18 lower than the first projection by pressing the tab and the rivet from the ultrasonic welding horn. And a process of applying ultrasonic energy to the welding portion 44.
[0017]
That is, since the manufacturing method of the electrolytic capacitor uses the ultrasonic welding horn for the electrolytic capacitor described above, the deformation and displacement of the tab during welding are suppressed, and the welding strength is high and the connection is highly reliable. As a result, a terminal structure having resistance to vibration stress can be realized in the electrolytic capacitor. In this case, the first projection is brought into contact with the tab overlapped with the rivet and pressurized, and as the pressing and welding progresses, the second projection comes into contact with the tab, resulting in the first projection. The positioning of the ultrasonic welding horn to the welding portion by the portion and the pressing of the tab by the second projection can prevent the tab from being displaced.
[0018]
In the method for manufacturing an electrolytic capacitor according to the present invention, in the method for manufacturing an electrolytic capacitor according to claim 8, the rivet and the tab are welded, and the first projection 12 forms the first concave portion 46, the first and the second concave portions. The method includes a step of forming the

second recesses

50 and 52 shallower than the first recess by surrounding the upright wall 48 with the second protrusion within the interval between the second protrusions. And That is, this process ensures that the tab is welded onto the rivet.
[0019]
In the method for manufacturing an electrolytic capacitor according to the present invention, the method for manufacturing an electrolytic capacitor according to claim 9 is configured such that, during welding, the tab overlapped with the rivet is pressed by the ultrasonic welding horn, and the tab and the rivet are connected to each other. The welding portion is surrounded by the ultrasonic welding horn. That is, warpage and displacement of the tab can be prevented, and the connection strength between the tab and the rivet can be increased.
[0020]
In the method for manufacturing an electrolytic capacitor according to the present invention, the method for manufacturing an electrolytic capacitor according to claim 10 is characterized in that, during welding, ultrasonic energy of the ultrasonic welding horn is applied to the tab in the same direction as the tab. I do. That is, since the ultrasonic vibration is applied in the same direction as the tab, the tab can be prevented from shifting in the width direction, and the connection range between the rivet and the tab can be widened.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an ultrasonic welding horn for an electrolytic capacitor according to an embodiment of the present invention.
[0022]
This ultrasonic welding horn for an electrolytic capacitor uses a metal material such as steel, for example, a single or plural horn portions 4 are formed at the tip of a horn formed in a cross shape, and an ultrasonic vibration source (not shown) This is a configuration in which ultrasonic energy is applied from
[0023]
Each horn portion 4 is formed by knurling on the top of a prismatic columnar portion 10. For example, as shown in FIG. A concave portion 14 having a V-shaped cross section is provided as a concave portion surrounding the concave portion 12, and a plurality of

protrusions

16, 18 are provided as a second convex portion surrounding the concave portion 14 and having a lower height than the convex portion 12. FIGS. 3 and 4 show cross sections of the horn shown in FIG. 2. FIG. 3 (A) is a cross section taken along line IIIA-IIIA of FIG. 2, and FIG. 3 (B) is a line IIIB-IIIB of FIG. 4A is a cross section taken along the line IVA-IVA in FIG. 2, and FIG. 4B is a cross section taken along the line IVB-IVB in FIG.
[0024]
The protrusion 12 is a quadrangular pyramid having a point-like sharp portion with a square bottom surface side, and has an acute vertex angle, and the angle θ ₁ is, for example, 80 ° to form the protrusion 12. Each of the side portions is an isosceles triangle. As the height h ₁ of the protrusions 12 is shown in FIG. 3 (A), the highest, the height h ₁ is the thickness t and the welding of the tab (FIG. 6) is a member to be welded by the horn portion 4 It is set according to the depth.
[0025]
The concave portion 14 has a bottom edge of the protruding portion 12 and is formed between the protruding

portions

12 and 16, between the protruding

portions

12 and 18, and between the protruding

portions

16 and 18, and has a cross-girder shape.
[0026]
The protruding portion 16 is a rectangular pyramid having a rectangular bottom surface having two sides equal to the bottom edge length of the protruding portion 12 and having a linear sharp portion composed of two isosceles triangles and a trapezoid. The projection 12 is disposed so as to surround the projection 12 in parallel with each bottom edge of the projection 12 with the recess 14 interposed therebetween. In the protrusion 16, the angle formed by the trapezoidal side surface, that is, the angle θ _{2 of the} sharp part is an acute angle and is set to be more acute than the angle θ ₁ , for example, 60 °. The height h ₂ of the protrusions 16 is lower than the projections 12 as shown in FIG. 3 (A), as with the height h ₂ is the projection 12, the tab is welded member (FIG. 6 ) Is set according to the thickness t and the welding depth. The projection 16 may be curved toward the projection 12 or in the opposite direction to form a projection having a sharp portion that is curved in a top view, and may surround the central projection 12. it can.
[0027]
The projection 18 is a square pyramid having a square bottom with the same bottom edge as the bottom edge length of the short side of the projection 16 and a pointed sharp portion composed of four isosceles triangles. In addition, they are arranged at four positions on the diagonal line of the protrusion 12 with the recess 14 interposed therebetween. In this projection 18, the angle theta ₃ the sharp-pointed portion is formed is set in the same manner as projection 16 for example, to 60 °. The height h ₃ of the projections 18 is lower than the projections 12 as shown in FIG. 4 (A), the height h ₃ in this embodiment is the same as the height h ₂ of the protrusions 16, protrusions Similarly to 12, the setting is made according to the thickness t and the welding depth of the tab 36 (FIG. 6) as the member to be welded. In this case, the heights h ₂ and h ₃ of the

protrusions

16 and 18 may be different, and the angles θ ₂ and θ ₃ may be different.
[0028]
In this embodiment, the

protrusions

16 and 18 have a shape having a sharp portion. However, as another form, the apex of the protrusion may be cut off to form a flat portion on the top. The protruding portion having the flat portion may have a flat portion having a circular shape in a top view or a polygonal shape such as a rectangle, a square, or a triangle. Further, the projection may be formed so that the plane portion is formed by curving a rectangle to be a curved surface when viewed from above and surrounds the projection 12.
[0029]
The horn portion 4 is formed such that the

projections

16 and 18 surround the projection 12 with the projection 12 as a center, and the outline of the

projections

12, 16 and 18 is similar to the bottom surface of the projection 12. The center of the protrusion 12 coincides with the center of the columnar portion 10. The horn portion 4 has a truncated pyramid shape, a peripheral surface portion having a trapezoidal inclined surface 20, and a triangular chamfered portion 22, for example, formed at the corner. The chamfered portion 22 may be an arc surface. In this case, since the angle of the inclined surface 20 and the angle of the

protrusions

16 and 18 are different between the inclined surface 20 and the projection 16 or the projection 18, the outer surface side has a V-shaped cross section with an angle θ ₄ . A recess is formed.
[0030]
Next, FIGS. 5 and 6 show a method of manufacturing an electrolytic capacitor according to an embodiment of the present invention.
[0031]
The electrolytic capacitor includes an outer case 26 in which the capacitor element 24 is sealed, and an opening 28 of the outer case 26 is sealed by a sealing plate 30. The sealing plate 30 is formed of a hard synthetic resin plate, and an O-ring 32 is attached to the upper edge as a sealing member.
[0032]
A terminal rivet 34 constituting an external terminal is penetrated and fixed to the sealing plate 30 by insert molding into the sealing plate 30, and is pulled out from the terminal rivet 34 protruding inside the sealing plate 30 and the capacitor element 24. A plurality of strip-shaped tabs 36 made of a metal material such as aluminum or the like are inserted into the through holes 38 (FIG. 6) of the tabs 36 and are fitted to the terminal rivets 34. It is fixed by caulking the washer 40. In this case, the end of the tab 36 is folded and overlapped with the end of the terminal rivet 34.
[0033]
As shown in FIG. 6, the horn portion 4 of the ultrasonic welding horn according to the present invention (FIGS. 1 and 2) abuts on the tab 36 superimposed on the terminal rivet 34, and is fixed by a fixing means (not shown). Ultrasonic energy is applied to the horn 4 from the ultrasonic welding source (not shown) together with the pressing force, as shown by an arrow F, opposite to the terminal rivet 34 of the sealing plate 30 positioned and fixed. In this case, the height _{h 1} of the protrusions 12 is set to be higher than the thickness t of the tab 36 is a member to be welded, the height _h 2, _{h 3} of

projections

16, 18 is lower than the thickness t. That is, these magnitude relations are h ₁ >t> h ₂ , h ₃ . Note that the magnitude relation may be h ₁ > h ₂ , h ₃ > t. By setting the heights h ₂ and h ₃ of the

protrusions

16 and 18 higher than the thickness t of the tab 36 in this manner, the warpage of the tab 36 during welding can be prevented, and the welding time can be reduced by shortening the welding time. In addition to the effect that excessive deformation of the protrusion 36 can be suppressed, since the

protrusions

16 and 18 abut on the terminal rivet 34 to connect the tab 36 and the terminal rivet 34, the electrical connection of the welded portion by the central protrusion 12 is made. The complementary effect that a strong connection state can be strengthened is also obtained.
[0034]
In this ultrasonic welding, the projection 12 of the horn portion 4 abuts on the tab 36 superimposed on the terminal rivet 34, and the sharp portion is positioned on the tab 36 by pressurization, and ultrasonic welding starts from this portion. Is done. With sustained pressure, projections 12 on the metal that constitutes the tabs 36 softened by the ultrasound energy enters only its height h _1, but this time, along with the projection 12 and the projection 16 bent The tab 36 that has been brought into close contact with the terminal rivet 34, and the metal of a part of the tab 36 enters the terminal rivet 34 together with the projection 12. At this time, the metal of the tab 36 enters the concave portion 14 around the protrusion 12, and a main welding portion in the welded portion 44 is formed by the protrusion 12, and welding is also performed on the

protrusions

16 and 18 side. The tab 36 is welded to the terminal rivet 34 by forming a secondary welding portion surrounding the main welding portion on the side of the

projections

16 and 18, so that a welding portion 44 is formed. In this embodiment, since the height h ₁ of the protrusions 12 is greater than the thickness t of the tab 36, welding, projection 12 enters the inside from the end face of the terminal rivet 34, as a result, the terminal rivet 34 Since the tab 36 enters into the inside and the terminal rivet 34 and the tab 36 are welded, extremely high connection strength is obtained.
[0035]
In addition, when ultrasonic welding is performed around the projection 12 at the center of the horn portion 4, the ultrasonic energy is concentrated at the center of the welded portion 44, the welded portion is sharpened, and the metal on the tab 36 side is sharpened. The joining surface with the metal on the terminal rivet 34 side is integrated, and the joining strength between the terminal rivet 34 and the tab 36 is increased. As a result, a highly reliable bonding state can be obtained. According to such ultrasonic welding, welding time and ultrasonic energy required for welding can be reduced, and sharpening of the welded portion 44 by the projection 12 can prevent displacement of the tab 36.
[0036]
Also, when ultrasonic energy is applied to the tab 36 centering on the projection 12 having a sharp portion, the welded portion is sharpened, but even if a phenomenon in which the laminated tab 36 warps around this portion occurs instantaneously. As a result, the

protrusions

16 and 18 around the protrusion 12 press the periphery of the welded portion 44 of the tab 36, and surround the main welded portion with the secondary welded portion generated by the

protrusions

16 and 18. The deformation of 36 is suppressed. In addition, since the welded portion spreads to the area surrounded by the

protrusions

16 and 18 centering on the protrusion 12, the welded portion 44 becomes the entire end face of the terminal rivet 34, so that a welding state with a high bonding strength can be obtained. And the tab 36 can be prevented from being displaced.
[0037]
In the ultrasonic welding using such a horn part 4, for example, as shown in FIG. A plurality of second

concave portions

50 and 52 having a pyramid shape shallower than the concave portion 46 are formed by surrounding the vertical wall portion 48 by the concave portions 14 and surrounding the vertical wall portion 48 by the

protrusions

16 and 18. The space defined by the concave portion 14 between the projection 12 of the horn portion 4 and the

projections

16 and 18 functions as a molten metal pool on the tab 36 side, and an upright metal wall portion 48 entered in the space of the concave portion 14 is formed. At the same time, the

recesses

50 and 52 are formed by the

protrusions

16 and 18. Accordingly, in the center of the welded portion 44 of the tab 36, a pyramid-shaped concave portion 46 having a large volume and a maximum depth, and four sets of pyramid-shaped

concave portions

50 and 52 having a smaller volume than the concave portion 46, An upright wall portion 48 that partitions these

concave portions

46, 50, 52 is formed. The height of the standing wall portion 48 matches the outer surface of the tab 36. In this case, the height of the standing wall portion 48 may be set back within the plane of the tab 36.
[0038]
If an ultrasonic welding horn having such a horn portion 4 is used, strong welding can be performed even if the welding time and welding energy are reduced, and the welding time can be shortened, so that excessive deformation of the tab 36 can be suppressed. In addition, the ultrasonic welding horn can be protected from abrasion and its service life can be extended.
[0039]
【Example】
As a first embodiment of the ultrasonic welding horn, for example, a projection 12 formed of a square pyramid having a vertex angle (θ ₁ ) = 80 ° and a height (h ₁ ) = 1.4 mm at the center of the horn portion 4. the projections 18 provided on the sides of the projections 16, the projections 12 consisting of regular quadrangular pyramid in the four corners of the projection 12, the height of the projections _{_{16,18 (h 2, h 3)}} = 0.7mm The angle (θ ₂ , θ ₃ ) of each apex angle was 60 °, and the height of the chamfered portion 22 was 1 mm.
[0040]
The terminal rivet 34 as a member to be welded had a diameter φ of 4 mm, and the tab 36 was formed by stacking six chemical tabs having a thickness of 0.2 mm and a width of 7 mm. That is, since the total thickness (t) of the tab 36 is 1.2 mm, the height (h ₁ ) of the projection 12 at the center of the horn portion 4 is greater than the total thickness (t) of the tab 36 = 1.2 mm. It is set higher by 0.2 mm.
[0041]
The welding conditions were fixed at a pressing force of 4 kg (gauge pressure), the ultrasonic vibration was set in the same direction as the longitudinal direction of the tab 36, and the electrolyte was attached to the tab 36, and the electrolyte was not attached Set the state.
[0042]
Further, as a second embodiment, as a modified horn in which the central projection 12 is formed into a quadrangular pyramid and a flat portion is formed on the top of each of the

projections

16 and 18 surrounding the projection 12, for example, As shown in FIG. 8, a horn 54 having a plurality of small protrusions 56 formed thereon was used. That is, the terminal rivet 34 is passed through the through hole 38 of the tab 36, the tab 36 is fixed to the terminal rivet 34 by swaging the washer 40, and the small projection 56 of the horn portion 54 is added to the folded tab 36. Welding was performed by applying ultrasonic energy while applying a pressure F.
[0043]
Table 1 shows the welding results under these conditions.
[0044]
[Table 1]

[0045]
As is apparent from the experimental results, in the conventional horn, the tab was displaced and a part of the tab was damaged regardless of the presence or absence of the electrolytic solution. On the other hand, in Example 1, tab displacement and tab breakage did not occur regardless of the presence or absence of the adhesion of the electrolytic solution. In the second embodiment, a slight tab shift occurs. However, in Example 1 and Example 2, the welding time was shortened, the ultrasonic energy required for welding could be significantly reduced, and the tab displacement occurred slightly, but there was no breakage of the tab, so that the connection strength could be improved. Highly reliable welding is obtained. In the case where the electrolytic solution adheres to the tab during welding, in the first embodiment having the sharp portion at the second protrusion, the sharp portion can eliminate the electrolytic solution and easily pressurize the tab. While the tab can be securely pressed down and the tab deviation can be suppressed, in the second embodiment having the flat portion at the top of the second projection, a slight tab deviation that does not cause a practical problem occurs.
[0046]
In the embodiment, the central projection 12 and the projections 18 at the four corners are pyramidal, but may be conical, and the projection 12 may be a column or a prism having a sharp part. And a columnar portion. By adjusting the height of the columnar portion, a desired welding depth can be set.
[0047]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
(A) Since welding can be performed centering on the first protrusion, the welding strength between the terminal rivet and the tab can be improved, and the plurality of second protrusions around the first protrusion are provided. By pressing and welding the tab at the welding portion, deformation and displacement of the tab at the time of welding can be prevented, and the reliability of connection can be improved.
(B) Since the welding is performed mainly on the first protrusion, the welding time can be greatly reduced, the ultrasonic energy required for welding can be reduced, and damage such as cracking or breakage of the tab due to welding can be prevented. In addition, the reliability of welding between the tab and the terminal rivet can be improved.
(C) Since the welding time and ultrasonic energy during welding can be reduced, the tip of the horn projection can be protected from abrasion, the horn life can be extended, and stable welding can be maintained for a long period of time. be able to.
[Brief description of the drawings]
FIG. 1 is a side view showing an ultrasonic welding horn according to an embodiment of the present invention.
FIG. 2 is a plan view showing a horn portion of the ultrasonic welding horn.
3A and 3B show cross sections of the horn shown in FIG. 2, wherein FIG. 3A is a cross sectional view taken along the line IIIA-IIIA of FIG. 2, and FIG. 3B is a cross sectional view taken along the line IIIB-IIIB of FIG.
4A and 4B are cross-sectional views taken along line IVA-IVA of FIG. 2; FIG. 4B is a cross-sectional view taken along line IVB-IVB of FIG. 2;
FIG. 5 is a view showing a part of the electrolytic capacitor in the process of being manufactured in the method for manufacturing an electrolytic capacitor according to the embodiment of the present invention.
FIG. 6 is a diagram showing welding between a terminal rivet and a tab.
FIG. 7 is a partial plan view showing a welded portion between the terminal rivet and the tab.
FIG. 8 is a side view showing a conventional method for manufacturing an ultrasonic welding horn and an electrolytic capacitor.
[Explanation of symbols]
12

First projections

16, 18 Second projections 20 Inclined surface (pyramidal surface)
22 chamfered part 24 capacitor element 30 sealing plate 34 terminal rivet 36 tab 44 welded part 46 first concave part 48

upright wall part

50, 52 second concave part

Claims

An ultrasonic welding horn for an electrolytic capacitor, which superimposes a tab drawn out of a capacitor element on a terminal rivet to be welded and applies ultrasonic energy to a welding portion between the terminal rivet and the tab while pressing the tab. ,
A first protrusion having a sharp portion,
A second projection formed to surround the first projection and having a lower height than the first projection;
An ultrasonic welding horn for an electrolytic capacitor, comprising:

2. The ultrasonic welding horn for an electrolytic capacitor according to claim 1, wherein the first protrusion is set higher than the thickness of the tab.

2. The ultrasonic welding horn for an electrolytic capacitor according to claim 1, wherein said first protrusion has a columnar shape having a sharp portion.

2. The ultrasonic welding horn for an electrolytic capacitor according to claim 1, wherein the second projection has a pointed sharp portion, a continuous linear or curved sharpened portion.

The ultrasonic welding horn for an electrolytic capacitor according to claim 1, wherein a pyramid surface is provided on a peripheral side of the second protrusion, and a chamfered portion is provided at the corner.

2. The ultrasonic welding horn for an electrolytic capacitor according to claim 1, wherein the second projection has a flat surface on the top.

A method for manufacturing an electrolytic capacitor in which tabs drawn from a capacitor element are overlapped on a rivet fixed through a sealing plate and welded by ultrasonic energy,
A first projection having a sharp portion at the center thereof, a tab projected on the rivet, a second projection formed to surround the first projection and being lower than the first projection; A process in which an ultrasonic welding horn having a
A process of applying ultrasonic energy from the ultrasonic welding horn to a welding portion between the tab and the rivet,
A method for manufacturing an electrolytic capacitor, comprising:

The rivet and the tab are welded, and the first protrusion surrounds the first recess, the upright wall within the interval between the first and second protrusions, and the second protrusion surrounds the upright wall. 8. The method according to claim 7, further comprising the step of forming a second concave portion shallower than the first concave portion.

The welding according to claim 7, wherein, during welding, the tab overlapped with the rivet is pressurized by the ultrasonic welding horn, and the welding portion between the tab and the rivet is surrounded by the ultrasonic welding horn. Manufacturing method of electrolytic capacitor.

8. The method according to claim 7, wherein, during welding, ultrasonic energy of the ultrasonic welding horn is applied to the tab in the same direction as the tab.