JP2004276087A

JP2004276087A - Resistance welding apparatus

Info

Publication number: JP2004276087A
Application number: JP2003073189A
Authority: JP
Inventors: Masakazu Kiko; 正和喜古; Haruo Hirasawa; 春夫平澤
Original assignee: Origin Electric Co Ltd
Current assignee: Origin Electric Co Ltd
Priority date: 2003-03-18
Filing date: 2003-03-18
Publication date: 2004-10-07
Anticipated expiration: 2023-03-18
Also published as: JP4175562B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resistance welding apparatus in which an inside welding electrode is arranged concentrically with an outside welding electrode, wherein even in the case that the interval between the outside welding electrode and the inside welding electrode is small, electric short-circuit is not developed, and welded trace on the material to be welded is less prone to be formed. <P>SOLUTION: In the resistance welding apparatus in which the inside welding electrode is arranged concentrically with the outside welding electrode, an electric insulating body is formed between the outside welding electrode and the inside welding electrode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、筒状の外側溶接電極内に筒状の内側溶接電極が同芯状に装設されてなる抵抗溶接装置に関するものである。
【０００２】
【従来の技術】
２本の溶接電極を並設して、例えばピン状又はナット状の被溶接物を平板状の被溶接物にインダイレクト方式で溶接するような場合、ピン状又はナット状の被溶接物の周辺部の各溶接点と溶接電極との条件が異なってしまう関係で、平板状の被溶接物に流れる電流量がピン状又はナット状の被溶接物の周囲の各部分においてアンバランスとなるため、ピン状又はナット状の被溶接物の全周囲を平板状の被溶接物に均等に溶接することが難しいという問題点があった。
【０００３】
この問題を解決する従来の抵抗溶接装置として、図４に示すように、２本の溶接電極１、２を同芯状に配置し、筒状の外側溶接電極１内に筒状の内側溶接電極２を装設した抵抗溶接装置が提案されている（例えば、特許文献１）。これによれば、内側溶接電極２は外側溶接電極１内を上下に移動できるようになっており、外側溶接電極１も上下に移動できるようになっている。加圧受部材３の上に平板状の被溶接物Ｗａを載せる一方、内側溶接電極２の中心に形成された装着孔２ａにピン状又はボルト状の被溶接物Ｗｂを装着して準備する。
【０００４】
次いで、不図示の駆動装置を動作させて外側溶接電極１を降下させ、被溶接材Ｗａに当てて加圧受部材３の上に被溶接部材Ｗａを図４のように押さえる。また、不図示の別の駆動装置を動作させて内側溶接電極２を下降させ、被溶接部材Ｗｂを被溶接部材Ｗａに接触させてそれらを所定の圧力で加圧する。この状態で、外側溶接電極１と内側溶接電極２に被溶接部材Ｗａ、Ｗｂを通して電流を流し、被溶接部材Ｗａ、Ｗｂ同士を溶接する。このような抵抗溶接にあっては、溶接電流は外側溶接電極１と内側溶接電極２の間を筒状の外側溶接電極１の全周囲にわたって均等に流れるため、溶接性が向上し、良好な溶接を行うことができる。
【０００５】
【特許文献１】特開２００２−２３９７４８公報（頁、図）
【０００６】
【本発明が解決しようとする課題】
しかしながら、被溶接部材Ｗａが比較的薄いアルミニウム板などからなり、かつ被溶接部材Ｗａに溶接痕が形成されるのを低減ないしは防止するには、筒状の外側溶接電極１と被溶接部材Ｗｂとの間隔をできるだけ短くせねばならない。
【０００７】
そのためには、筒状の外側溶接電極１と内側溶接電極２との間の距離を小さくし、かつ内側溶接電極２の外径を被溶接部材Ｗｂの外径に近づけなければならない。しかし、被溶接部材Ｗｂの外径が小さいとき、外側溶接電極１と内側溶接電極２の外径を小さくして全体的に細く、特に内側溶接電極２を細くすると、機械的剛性が低くなり、加圧力をかけたときに内側溶接電極２が撓むことがある。これによって被溶接部材Ｗｂの位置決めが不安定になったり、外側溶接電極１と内側溶接電極２間の間隔が狭い場合にはそれらが接触し、短絡するという致命的な問題が発生する場合もあった。
【０００８】
また、従来の場合には図４のように被溶接部材Ｗｂの一部分ｗｙを内側溶接電極２の中心に形成された装着孔２ａに装着しているが、装着孔２ａと被溶接部材Ｗｂの一部分ｗｙとの間の隙間の裕度が大きい方が装着は容易であるが、その裕度が大きいと被溶接部材Ｗｂの位置が不安定になる。これによって、本来の溶接位置から僅かにずれて被溶接部材Ｗｂが被溶接部材Ｗａに溶接されてしまい、溶接位置精度が要求される場合には問題になる。
【０００９】
本発明の主たる課題は、外側溶接電極と内側溶接電極との間隔を小さくしても電気的に短絡することが無く、被溶接物に溶接痕が形成され難い抵抗溶接装置を提供することを目的とする。
【００１０】
また、本発明の他の目的は、溶接位置決めを正確に行い得る抵抗溶接装置を提供することである。
【００１１】
【課題を解決するための手段及び作用】
上記問題点を解決するため、本願請求項１記載の発明は、外側溶接電極内に内側溶接電極が同芯状に装設された抵抗溶接装置において、前記外側溶接電極と内側溶接電極との間に電気絶縁体を設けたことを特徴とする抵抗溶接装置を提供するものである。
【００１２】
このように構成した抵抗溶接装置においては、外側溶接電極と内側溶接電極との間隔を小さくしてもその間には電気絶縁部材が介在し、また内側溶接電極に支承された被溶接物と外側溶接電極との間にも電気絶縁部材を介在させることができるので、電気的短絡が発生することはなく、前記被溶接物と外側溶接電極との距離を小さくできるので、溶接電流路を十分に短くでき、被溶接物に溶接痕が形成され難い。
【００１３】
また本願請求項２は、請求項１において、前記電気絶縁体は前記内側溶接電極の外径とほぼ等しい内径、又は前記外側溶接電極の内径にほぼ等しい外径を持つ筒状体であることを特徴とする抵抗溶接装置を提供するものである。
【００１４】
このように構成した抵抗溶接装置においては、溶接電極と電気絶縁部材との間の空隙が十分に小さいので、内側溶接電極が細いもので堅牢性に欠けるものであっても、内側溶接電極が外側溶接電極に接触して短絡事故を起こすことなく正しい溶接位置に溶接することが可能である。
【００１５】
本願請求項３は、請求項１又は請求項２において、前記外側溶接電極と内側溶接電極は前記電気絶縁体に対して前記外側溶接電極の内壁又は前記内側溶接電極の外壁が接触しながら滑動することを特徴とする抵抗溶接装置を提供するものである。
【００１６】
このように構成した抵抗溶接装置においても、筒状の一方の溶接電極が他方の溶接電極にガイドされた形で電気絶縁部材面を滑動するので、内側溶接電極が細いもので堅牢性に欠けるものであっても、内側溶接電極が外側溶接電極に接触して短絡事故を起こすことはなく、また正しい溶接位置に溶接することが可能である。
【００１７】
本願請求項４は、外側溶接電極内に内側溶接電極が同芯状に装設された抵抗溶接装置において、前記内側電極の先端部分には中央側の凹んだ円錐状のテーパー面が形成されており、該テーパー面に、一方の被溶接物の中央側が凸状のテーパー面を支承し、前記内側溶接電極を下降させて前記一方の被溶接物を他方の被溶接物に加圧するときに、前記テーパー面同士の働きで前記一方の被溶接物の位置合わせも行えるようにした抵抗溶接装置を提供するものである。
【００１８】
このように構成した抵抗溶接装置においては、溶接電極構造によって、一方の被溶接物を他方の被溶接物の溶接個所に正確に位置決めすることができる。
【００１９】
【本発明の実施の形態】
次に本発明の実施の形態について説明する。この発明は溶接電極部分に特徴があるので、その部分の構造だけを図示し、他の機械的構造部分や電気回路については、前述の特許文献１で開示した技術などをそのまま利用できるので、ここでは図示せず、説明も省略する。また、図４で示した記号と同一の記号は相当する部材を示すものとする。
【００２０】
図１は、本発明の抵抗溶接装置の溶接前における溶接電極部分の状態を示し、図２は本発明の抵抗溶接装置の溶接時における溶接電極部分の状態を示す図である。図１、図２において、外側溶接電極１は黄銅のような金属材料からなる円筒状のものであり、その内側に円筒状の内側溶接電極２が配置されている。外側溶接電極１と内側溶接電極２は互いに同芯状に配置されており、その間には電気絶縁部材４が備えられている。
【００２１】
電気絶縁部材４は、ベーク材料のような電気絶縁性の合成樹脂材料又はセラミクス材料などからなる円筒状のものであり、その外径は外側溶接電極１の内径とほぼ同じであり、その内径は内側溶接電極２の外径よりも幾分大きくなっている。円筒状の電気絶縁部材４は、接着剤による接着、又は嵌め合いによる嵌合などによって外側溶接電極１の内壁に固定されている。円筒状の電気絶縁部材４の内壁面と内側溶接電極２の外壁面との間には微小な空間があり、内側溶接電極２が図面で上下に動くときには、円筒状の電気絶縁部材４の内壁面と内側溶接電極２の外壁面とはほぼ全面で軽く接触しているのが好ましい。
【００２２】
このように全面で軽く接触していることにより、内側溶接電極２は円筒状の電気絶縁部材４にガイドされて鉛直方向に動くことになり、円筒状の電気絶縁部材４の内壁面と内側溶接電極２の外壁面との間には実質的にガタがなくなる。したがって、電気絶縁部材４は内側溶接電極２が撓んだりしても、内側溶接電極２が外側溶接電極１に接触して電気的短絡を起こすことを防ぐばかりでなく、内側溶接電極２をガイドする働きも行うので、被溶接物Ｗｂがいずれかの方向にずれることがなく、溶接位置を高精度に保つ。
【００２３】
内側溶接電極２は、従来のものと同様に被溶接物Ｗｂの一部分ｗｙを受け入れる装着孔２ａを有すると共に、図３に拡大して示すように、先端面に中央側が低くなる傾斜、つまり凹んだ傾斜で形成された円錐状のテーパー面２ｂを備えるところに特徴がある。テーパー面２ａは内側溶接電極２の先端面全周にわたって形成されている。
【００２４】
被溶接物Ｗｂは、内側溶接電極２のテーパー面２ｂに適合するテーパー面Ｔｐを有する。テーパー面Ｔｐは被溶接物Ｗｂの両側面の全周にわたって形成され、中央側が高く、外側に下がる傾斜を有し、その傾斜角度は補角であるが、テーパー面２ｂの角度と同じ角度である。つまり、テーパー面２ｂは中央側が凸状になっている。したがって、被溶接物Ｗｂが内側溶接電極２に吸着保持されたとき、被溶接物Ｗｂのテーパー面Ｔｐはテーパー面２ｂに当接し、それらテーパー面に加圧力が働くとき、被溶接物Ｗｂと内側溶接電極２の中心軸線が一致する。
【００２５】
次に動作について説明する。先ず、不図示の被溶接部搬送ロボットにより被溶接物Ｗｂが内側溶接電極２のテーパー面２ｂに供給され、被溶接物Ｗｂの一部分ｗｙが装着孔２ａに容易に受け入れられる。このとき、内側溶接電極２は外側溶接電極１よりも下側に突出しており、不図示の真空吸引機構の働きにより装着孔２ａを通して吸引され、被溶接物Ｗｂは内側溶接電極２のテーパー面２ｂに吸着保持される。
【００２６】
その状態で、図示しない加圧駆動機構により外側溶接電極１と電気絶縁部材４とが下降し、被溶接物Ｗｂが外側溶接電極１内にある程度入った状態で内側溶接電極２も一緒に更に下降する。この下降で、先ず外側溶接電極１がノートパソコンなどのボトムケースのような被溶接物Ｗａに当接し、被溶接物Ｗａを押し下げ、加圧受部材３に押し付ける。そのとき、内側溶接電極２も図示しない加圧駆動機構により電気絶縁部材４に接触しながら下降し、被溶接物Ｗｂを被溶接物Ｗａに所定の加圧力で押し付ける（図３）。この加圧時、内側溶接電極２のテーパー面２ｂは、その傾斜によって被溶接物Ｗｂを中央へ寄せる働きを行い、内側溶接電極２と被溶接物Ｗｂとの中心軸線を一致させるので、非常に精度の高い溶接位置を確保できることになる。
【００２７】
そして、外側溶接電極１が被溶接物Ｗａを所定の加圧力で加圧し、また内側溶接電極２が被溶接物Ｗｂを被溶接物Ｗａに所定の加圧力で押し付けている状態で、不図示の電気回路から数千ないし数万アンペアのピーク電流が数十ミリ秒以内の短時間に、被溶接物Ｗａと被溶接物Ｗａとを通して外側溶接電極１と内側溶接電極２間を流れる。
【００２８】
このとき、外側溶接電極１から被溶接物Ｗａを流れる溶接電流はその厚みによる断面積を流れるので、例えばその電流路、つまり外側溶接電極１から被溶接物Ｗｂまでの距離が長く、かつ被溶接物Ｗａの板厚が薄いと、その溶接電流の流れた部分は溶接電流によって非常に高温となって溶接痕ができてしまう。
【００２９】
しかしこの発明では、外側溶接電極１と内側溶接電極２との間に電気絶縁部材４を介在させたので、被溶接物Ｗｂが円筒状の電気絶縁部材４の内壁に接する程度まで、外側溶接電極１から被溶接物Ｗｂまでの距離を小さくできる、つまり極限では被溶接物Ｗａの溶接電流路を電気絶縁部材４の厚み程度にできるので、溶接電流によるその電流路での発熱は小さく、溶接痕はできない。
【００３０】
１回の溶接が終了すると、外側溶接電極１と内側溶接電極２は不図示の駆動機構により上昇し、所定位置で停止する。外側溶接電極１と内側溶接電極２の加圧力から開放されて、スプリングで支えられている被溶接物Ｗａは加圧受部材３から離れ、図示しない水平方向駆動機構により移動され、次の溶接個所が加圧受部材３上に位置することになり、前述のような動作がまた繰り返される。
【００３１】
次に図示しないが、別の実施例を説明する。前記実施例では、円筒状の電気絶縁部材４を外側溶接電極１の内壁に固定したが、この実施例では電気絶縁部材４を内側溶接電極２の外壁に固定する。
【００３２】
図１を利用して説明すると、電気絶縁部材４は、前記実施例と同様にベーク材料のような電気絶縁性の合成樹脂材料又はセラミクス材料などからなる円筒状のものであり、その内径は内側溶接電極２の外径とほぼ同じであり、その外径は外側溶接電極１の内径よりも幾分小さくなっている。円筒状の電気絶縁部材４は、接着剤による接着、又は嵌め合いによる嵌合などによって外側溶接電極２の外壁に固定されている。円筒状の電気絶縁部材４の外壁面と外側溶接電極１の内壁面との間には微小な空間があり、内側溶接電極２が図面で上下に動くときには、円筒状の電気絶縁部材４の内壁面と内側溶接電極２の外壁面とはほぼ全面で軽く接触しながら滑動するのが好ましい。
【００３３】
この実施例では、円筒状の電気絶縁部材４を内側溶接電極２の外壁に固定しているので、電気絶縁部材４は連続する１本のものでなくともよく、複数に分割された短い筒状のものでも同様な効果を得ることができ、作り易さもほとんど変わらない。
【００３４】
なお、筒状の電気絶縁部材と外側溶接電極１との間の滑動をより容易にするために、電気絶縁部材４を接触抵抗の少ないリング状にし、このリング状の電気絶縁部材を内側溶接電極２の外壁に一定間隔で取りつけてもよい。したがって、この発明では、筒状の電気絶縁部材４はリング状の電気絶縁部材をも含むものとする。また、短い筒状の電気絶縁部材とリング状の電気絶縁部材とを組み合わせてももちろんよい。
【００３５】
【発明の効果】
以上説明したように、本発明の請求項１によれば、外側溶接電極と内側溶接電極との間隔を小さくしても電気的に短絡することが無く、被溶接物に溶接痕が形成され難い抵抗溶接装置を提供することができる。
【００３６】
また、本発明の請求項４によれば、溶接電極構造によって、一方の被溶接物を他方の被溶接物の溶接個所に正確に位置決めし得る抵抗溶接装置を提供することができる。
【図面の簡単な説明】
【図１】本発明に係る抵抗溶接装置の溶接電極構造を説明するための図である。
【図２】本発明に係る抵抗溶接装置の内側溶接電極構造と被溶接物との関係を説明するための図である。
【図３】溶接時における本発明に係る抵抗溶接装置の溶接電極構造と被溶接物との関係を説明するための図である。
直動部材の一例を説明するための図である。
【図４】従来の抵抗溶接装置の電極構造を説明するための図である。
【符号の説明】
１…外側溶接電極
２…内側溶接電極
２ｂ…内側溶接電極のテーパー面
３…加圧受部材
４…電気絶縁部材
Ｗａ、Ｗｂ…被溶接物
Ｔｐ…被溶接物Ｗｂのテーパー面[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a resistance welding apparatus in which a cylindrical inner welding electrode is provided concentrically inside a cylindrical outer welding electrode.
[0002]
[Prior art]
When two welding electrodes are juxtaposed and, for example, a pin-shaped or nut-shaped workpiece is welded to a flat workpiece by an indirect method, the periphery of the pin-shaped or nut-shaped workpiece is welded. Because the conditions of each welding point of the part and the welding electrode are different, the amount of current flowing through the flat plate-shaped workpiece becomes unbalanced at each part around the pin-shaped or nut-shaped workpiece, There is a problem that it is difficult to uniformly weld the entire periphery of the pin-shaped or nut-shaped workpiece to the flat workpiece.
[0003]
As a conventional resistance welding apparatus for solving this problem, as shown in FIG. 4, two welding electrodes 1 and 2 are arranged concentrically, and a cylindrical inner welding electrode is provided inside a cylindrical outer welding electrode 1. 2 has been proposed (for example, Patent Document 1). According to this, the inner welding electrode 2 can move up and down inside the outer welding electrode 1, and the outer welding electrode 1 can also move up and down. A flat plate-shaped workpiece Wa is placed on the pressure receiving member 3, and a pin-shaped or bolt-shaped workpiece Wb is mounted in a mounting hole 2a formed in the center of the inner welding electrode 2.
[0004]
Next, the drive device (not shown) is operated to lower the outer welding electrode 1, and presses the member to be welded Wa onto the pressure receiving member 3 as shown in FIG. Further, another driving device (not shown) is operated to lower the inner welding electrode 2, and the member to be welded Wb is brought into contact with the member to be welded Wa to press them with a predetermined pressure. In this state, a current is applied to the outer welding electrode 1 and the inner welding electrode 2 through the members Wa and Wb to weld the members Wa and Wb to each other. In such resistance welding, the welding current flows uniformly between the outer welding electrode 1 and the inner welding electrode 2 over the entire circumference of the cylindrical outer welding electrode 1, so that the weldability is improved and good welding is achieved. It can be performed.
[0005]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-239748 (pages, figures)
[0006]
[Problems to be solved by the present invention]
However, in order to reduce or prevent the welded member Wa from a relatively thin aluminum plate or the like, and to prevent or prevent the formation of welding marks on the welded member Wa, the cylindrical outer welding electrode 1 and the welded member Wb must be connected to each other. Must be as short as possible.
[0007]
For this purpose, the distance between the cylindrical outer welding electrode 1 and the inner welding electrode 2 must be reduced, and the outer diameter of the inner welding electrode 2 must be closer to the outer diameter of the member to be welded Wb. However, when the outer diameter of the member to be welded Wb is small, the outer diameters of the outer welding electrode 1 and the inner welding electrode 2 are made smaller and overall thinner. Particularly, when the inner welding electrode 2 is made thinner, the mechanical rigidity becomes lower. When a pressing force is applied, the inner welding electrode 2 may bend. As a result, the positioning of the member to be welded Wb becomes unstable, or when the distance between the outer welding electrode 1 and the inner welding electrode 2 is small, they come into contact with each other, causing a fatal problem of short-circuiting. Was.
[0008]
In the conventional case, a part wy of the member to be welded Wb is mounted in a mounting hole 2a formed at the center of the inner welding electrode 2 as shown in FIG. The larger the allowance of the gap with the wy is, the easier the mounting is, but if the allowance is large, the position of the member to be welded Wb becomes unstable. As a result, the member to be welded Wb is slightly welded to the member to be welded Wa with a slight deviation from the original welding position, which poses a problem when welding position accuracy is required.
[0009]
A main object of the present invention is to provide a resistance welding apparatus in which even if the distance between an outer welding electrode and an inner welding electrode is reduced, an electrical short circuit does not occur and welding marks are not easily formed on a workpiece. And
[0010]
Another object of the present invention is to provide a resistance welding apparatus capable of accurately performing welding positioning.
[0011]
Means and Action for Solving the Problems
In order to solve the above-mentioned problems, the invention according to claim 1 of the present application is directed to a resistance welding apparatus in which an inner welding electrode is provided concentrically inside an outer welding electrode. And a resistance welding apparatus provided with an electric insulator.
[0012]
In the resistance welding apparatus configured as described above, even if the distance between the outer welding electrode and the inner welding electrode is reduced, an electric insulating member is interposed between the outer welding electrode and the inner welding electrode. Since an electrical insulating member can be interposed between the electrode and the electrode, an electrical short circuit does not occur, and the distance between the workpiece and the outer welding electrode can be reduced. It is difficult to form welding marks on the workpiece.
[0013]
Claim 2 of the present application is that, in claim 1, the electric insulator is a cylindrical body having an inner diameter substantially equal to the outer diameter of the inner welding electrode or an outer diameter substantially equal to the inner diameter of the outer welding electrode. A resistance welding apparatus is provided.
[0014]
In the resistance welding apparatus configured as described above, the gap between the welding electrode and the electrical insulating member is sufficiently small, so that even if the inner welding electrode is thin and lacks robustness, the inner welding electrode is It is possible to perform welding at a correct welding position without causing a short circuit accident due to contact with the welding electrode.
[0015]
According to a third aspect of the present invention, in the first or second aspect, the outer welding electrode and the inner welding electrode slide while the inner wall of the outer welding electrode or the outer wall of the inner welding electrode is in contact with the electric insulator. It is intended to provide a resistance welding apparatus characterized by the above.
[0016]
Even in the resistance welding apparatus configured as described above, one of the cylindrical welding electrodes slides on the surface of the electric insulating member in a form guided by the other welding electrode, so that the inner welding electrode is thin and lacks robustness. Even in this case, the inner welding electrode does not contact the outer welding electrode to cause a short circuit accident, and welding can be performed at a correct welding position.
[0017]
According to a fourth aspect of the present invention, in the resistance welding apparatus in which the inner welding electrode is provided concentrically within the outer welding electrode, a concave conical tapered surface on the center side is formed at a tip portion of the inner electrode. When the tapered surface, the center side of one of the workpieces supports a convex tapered surface, and when the inner welding electrode is lowered to press the one workpiece against the other workpiece, It is an object of the present invention to provide a resistance welding apparatus which can perform the positioning of the one workpiece by the action of the tapered surfaces.
[0018]
In the resistance welding apparatus configured as described above, one of the workpieces can be accurately positioned at a welding position of the other workpiece by the welding electrode structure.
[0019]
[Embodiment of the present invention]
Next, an embodiment of the present invention will be described. Since the present invention has a feature in the welding electrode portion, only the structure of the portion is illustrated, and the other mechanical structural portions and electric circuits can use the technology disclosed in the above-mentioned Patent Document 1 as it is. Then, it is not shown, and the description is omitted. Further, the same symbols as those shown in FIG. 4 indicate corresponding members.
[0020]
FIG. 1 is a view showing a state of a welding electrode portion before welding of the resistance welding apparatus of the present invention, and FIG. 2 is a view showing a state of the welding electrode section at the time of welding of the resistance welding apparatus of the present invention. 1 and 2, the outer welding electrode 1 is a cylindrical member made of a metal material such as brass, and a cylindrical inner welding electrode 2 is disposed inside the outer electrode. The outer welding electrode 1 and the inner welding electrode 2 are arranged concentrically with each other, and an electrical insulating member 4 is provided between them.
[0021]
The electrical insulating member 4 is a cylindrical member made of an electrically insulating synthetic resin material such as a bake material or a ceramics material, and has an outer diameter substantially equal to the inner diameter of the outer welding electrode 1 and an inner diameter of the outer welding electrode 1. It is somewhat larger than the outer diameter of the inner welding electrode 2. The cylindrical electrical insulating member 4 is fixed to the inner wall of the outer welding electrode 1 by bonding with an adhesive or fitting by fitting. There is a small space between the inner wall surface of the cylindrical electrical insulating member 4 and the outer wall surface of the inner welding electrode 2, and when the inner welding electrode 2 moves up and down in the drawing, the inner It is preferable that the wall surface and the outer wall surface of the inner welding electrode 2 are in light contact with each other over almost the entire surface.
[0022]
Due to the light contact on the entire surface, the inner welding electrode 2 is guided by the cylindrical electric insulating member 4 and moves in the vertical direction, so that the inner welding electrode 2 is welded to the inner wall surface of the cylindrical electric insulating member 4. There is substantially no play between the electrode 2 and the outer wall surface. Therefore, the electric insulating member 4 not only prevents the inner welding electrode 2 from contacting the outer welding electrode 1 to cause an electric short circuit even if the inner welding electrode 2 bends, but also guides the inner welding electrode 2. Since the workpiece Wb does not shift in any direction, the welding position is maintained with high accuracy.
[0023]
The inner welding electrode 2 has a mounting hole 2a for receiving a part wy of the workpiece Wb in the same manner as the conventional one, and as shown in an enlarged view in FIG. It is characterized in that it has a conical tapered surface 2b formed by inclination. The tapered surface 2 a is formed over the entire circumference of the distal end surface of the inner welding electrode 2.
[0024]
The workpiece Wb has a tapered surface Tp that matches the tapered surface 2b of the inner welding electrode 2. The tapered surface Tp is formed over the entire periphery of both side surfaces of the workpiece Wb, and has a high center side and a downward slope, and the inclination angle is a supplementary angle, but the same angle as the angle of the tapered surface 2b. . That is, the center side of the tapered surface 2b is convex. Therefore, when the workpiece Wb is attracted and held by the inner welding electrode 2, the tapered surface Tp of the workpiece Wb comes into contact with the tapered surface 2b. The central axes of the welding electrodes 2 coincide.
[0025]
Next, the operation will be described. First, the workpiece Wb to be welded is supplied to the tapered surface 2b of the inner welding electrode 2 by a welding part transport robot (not shown), and a part wy of the workpiece Wb is easily received in the mounting hole 2a. At this time, the inner welding electrode 2 protrudes below the outer welding electrode 1, is sucked through the mounting hole 2a by the action of a vacuum suction mechanism (not shown), and the workpiece Wb is tapered on the tapered surface 2b of the inner welding electrode 2. Is held by suction.
[0026]
In this state, the outer welding electrode 1 and the electric insulating member 4 are lowered by a pressure driving mechanism (not shown), and the inner welding electrode 2 is further lowered together with the workpiece Wb partially entering the outer welding electrode 1. I do. By this lowering, the outer welding electrode 1 first comes into contact with the work Wa such as a bottom case of a notebook computer or the like, and the work Wa is pushed down and pressed against the pressure receiving member 3. At this time, the inner welding electrode 2 also descends while being in contact with the electric insulating member 4 by a pressure driving mechanism (not shown), and presses the workpiece Wb against the workpiece Wa with a predetermined pressure (FIG. 3). At the time of pressurization, the tapered surface 2b of the inner welding electrode 2 acts to bring the work Wb to the center by its inclination, and the center axis of the inner welding electrode 2 and the work Wb are aligned with each other. A highly accurate welding position can be secured.
[0027]
The outer welding electrode 1 presses the workpiece Wa with a predetermined pressing force, and the inner welding electrode 2 presses the workpiece Wb against the workpiece Wa with a predetermined pressing force. A peak current of several thousand to tens of thousands of amperes flows from the electric circuit between the outer welding electrode 1 and the inner welding electrode 2 through the workpiece Wa and the workpiece Wa in a short time within several tens of milliseconds.
[0028]
At this time, since the welding current flowing from the outer welding electrode 1 to the workpiece Wa flows through a cross-sectional area depending on the thickness, for example, the current path, that is, the distance from the outer welding electrode 1 to the workpiece Wb is longer, and the welding current is longer. If the thickness of the object Wa is small, the portion where the welding current flows becomes extremely high due to the welding current, and welding marks are formed.
[0029]
However, in the present invention, since the electric insulating member 4 is interposed between the outer welding electrode 1 and the inner welding electrode 2, the outer welding electrode is kept until the workpiece Wb contacts the inner wall of the cylindrical electric insulating member 4. 1 to the work piece Wb can be reduced, that is, in the limit, the welding current path of the work piece Wa can be reduced to about the thickness of the electrical insulating member 4, so that the heat generated in the current path due to the welding current is small, Can not.
[0030]
When one welding is completed, the outer welding electrode 1 and the inner welding electrode 2 are raised by a drive mechanism (not shown) and stop at a predetermined position. The workpiece Wa released from the pressing force of the outer welding electrode 1 and the inner welding electrode 2 and supported by the spring is separated from the pressure receiving member 3 and is moved by a horizontal driving mechanism (not shown) so that the next welding point is formed. Since it is located on the pressure receiving member 3, the above-described operation is repeated.
[0031]
Next, although not shown, another embodiment will be described. In the above embodiment, the cylindrical electric insulating member 4 is fixed to the inner wall of the outer welding electrode 1, but in this embodiment, the electric insulating member 4 is fixed to the outer wall of the inner welding electrode 2.
[0032]
Explaining with reference to FIG. 1, the electric insulating member 4 is a cylindrical member made of an electric insulating synthetic resin material such as a bake material or a ceramic material as in the above-described embodiment, and has an inner diameter of the inner side. The outer diameter of the welding electrode 2 is substantially the same, and the outer diameter is slightly smaller than the inner diameter of the outer welding electrode 1. The cylindrical electric insulating member 4 is fixed to the outer wall of the outer welding electrode 2 by bonding with an adhesive or fitting by fitting. There is a minute space between the outer wall surface of the cylindrical electrical insulating member 4 and the inner wall surface of the outer welding electrode 1, and when the inner welding electrode 2 moves up and down in the drawing, the inner It is preferable that the wall surface and the outer wall surface of the inner welding electrode 2 slide while lightly contacting over substantially the entire surface.
[0033]
In this embodiment, since the cylindrical electric insulating member 4 is fixed to the outer wall of the inner welding electrode 2, the electric insulating member 4 does not have to be a continuous one, but is divided into a plurality of short cylindrical members. The same effect can be obtained even with the one of the above, and the easiness of making is almost the same.
[0034]
In order to make the sliding between the cylindrical electric insulating member and the outer welding electrode 1 easier, the electric insulating member 4 is formed into a ring shape having a small contact resistance, and the ring-shaped electric insulating member is formed into the inner welding electrode. 2 may be attached to the outer wall at regular intervals. Therefore, in the present invention, the cylindrical electric insulating member 4 includes a ring-shaped electric insulating member. Also, a short tubular electric insulating member and a ring-shaped electric insulating member may be combined.
[0035]
【The invention's effect】
As described above, according to the first aspect of the present invention, even if the distance between the outer welding electrode and the inner welding electrode is reduced, there is no electrical short circuit, and welding marks are hardly formed on the workpiece. A resistance welding device can be provided.
[0036]
Further, according to the fourth aspect of the present invention, it is possible to provide a resistance welding apparatus capable of accurately positioning one workpiece to be welded to the other workpiece by the welding electrode structure.
[Brief description of the drawings]
FIG. 1 is a view for explaining a welding electrode structure of a resistance welding apparatus according to the present invention.
FIG. 2 is a diagram for explaining a relationship between an inner welding electrode structure of a resistance welding apparatus according to the present invention and an object to be welded.
FIG. 3 is a diagram for explaining a relationship between a welding electrode structure of the resistance welding apparatus according to the present invention and a workpiece during welding.
It is a figure for explaining an example of a direct-acting member.
FIG. 4 is a view for explaining an electrode structure of a conventional resistance welding apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Outer welding electrode 2 ... Inner welding electrode 2b ... Taper surface of inner welding electrode 3 ... Pressure receiving member 4 ... Electrical insulating member Wa, Wb ... Welding object Tp ... Tapered surface of welding object Wb

Claims

外側溶接電極内に内側溶接電極が同芯状に装設された抵抗溶接装置において、
前記外側溶接電極と内側溶接電極との間に電気絶縁体を設けたことを特徴とする抵抗溶接装置。In a resistance welding apparatus in which an inner welding electrode is provided concentrically inside an outer welding electrode,
A resistance welding apparatus, wherein an electric insulator is provided between the outer welding electrode and the inner welding electrode.

請求項１において、
前記電気絶縁体は前記内側溶接電極の外径とほぼ等しい内径、又は前記外側溶接電極の内径にほぼ等しい外径を持つ筒状体であることを特徴とする抵抗溶接装置。In claim 1,
The resistance welding apparatus according to claim 1, wherein the electric insulator is a cylindrical body having an inner diameter substantially equal to the outer diameter of the inner welding electrode or an outer diameter substantially equal to the inner diameter of the outer welding electrode.

請求項１又は請求項２において、
前記電気絶縁体に対して前記外側溶接電極の内壁又は前記内側溶接電極の外壁が接触しながら滑動することを特徴とする抵抗溶接装置。In claim 1 or claim 2,
A resistance welding apparatus, wherein the inner wall of the outer welding electrode or the outer wall of the inner welding electrode slides while contacting the electrical insulator.

外側溶接電極内に内側溶接電極が同芯状に装設された抵抗溶接装置において、
前記内側電極の先端部分には中央側の凹んだ円錐状のテーパー面が形成されており、該テーパー面に、一方の被溶接物の中央側が凸状のテーパー面を支承し、前記内側溶接電極を下降させて前記一方の被溶接物を他方の被溶接物に加圧するときに、前記テーパー面同士の働きで前記一方の被溶接物の位置合わせも行えるようにしたことを特徴とする抵抗溶接装置。In a resistance welding apparatus in which an inner welding electrode is provided concentrically inside an outer welding electrode,
A concave conical tapered surface on the center side is formed at a tip portion of the inner electrode, and the central side of one of the workpieces supports a convex tapered surface on the tapered surface. When the one workpiece is pressed against the other workpiece by lowering the tapered surface, the tapered surfaces act together to perform the alignment of the one workpiece. apparatus.