JP3794296B2

JP3794296B2 - Spot welding equipment

Info

Publication number: JP3794296B2
Application number: JP2001224960A
Authority: JP
Inventors: 重行芳賀; 康岩瀬
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2001-07-25
Filing date: 2001-07-25
Publication date: 2006-07-05
Anticipated expiration: 2021-07-25
Also published as: JP2003039175A

Description

【０００１】
【発明の属する技術分野】
本発明は、ワークが一対の電極間にセットされ、その電極間に溶接電流を流すことでワークに抵抗発熱を生じさせて行われるスポット溶接装置に関し、特に、ワークを順次切替えて連続して行われるスポット溶接装置に関する。
【０００２】
【従来の技術】
従来よりのワークを順次切替えて連続して行われるスポット溶接としては、ワーク（被溶接部）に対し一対の電極を圧接させ、その電極間に溶接電流を流すことでワークに抵抗発熱を生じさせてワークをスポット溶接している。そして、ワークが順次切替えられ、この連続したワークを同一の一対の電極を用いて繰り返しスポット溶接が行われるスポット溶接装置が知られている。この連続したワークを同一の一対の電極を用いて繰り返しスポット溶接を行う際、これら電極の温度はワークが準じ切替えられて溶接回数が増えるに従い昇温されていく。この昇温される状態にて連続したワークを同一の溶接条件にてスポット溶接を行うと、溶接状態が不安定となり溶接不良が発生する。詳細には、電極の温度上昇は、電極間における通電抵抗を低下させ通電電流値を増大させる。そして、この通電電流の増大により加熱されるワークの温度が上昇して高温溶融させて溶接部周辺の変形、あるいは溶接部の溶接強度低下等の溶接不良に至るのである。
【０００３】
そこで、連続したワークをスポット溶接する際には、各ワーク毎に溶接条件を変更制御する等の対策が行われている。この対策として、例えば通電時間を短くする、あるいは通電電流を減少させて溶接部の溶融温度を低下させたり、ワークの送り速度を遅くして電極が冷やされる時間を稼ぐ等の対応が行われている。
【０００４】
【発明が解決しようとする課題】
しかし、ワーク毎に溶接条件を変更制御する等の対策は、ワークの溶融される温度を適温となる条件に合わせるのが困難であるとともに制御する装置が高価複雑となる。また、電極の温度を一定温度に保つようにワークの送り速度を遅くして電極が冷やされる時間を設定すると作業効率が低下する。また更に、電極の温度が所定温度領域に保たれなくて高温となると、電極を消耗させる等の問題がある。
【０００５】
本発明の目的は上記の点に鑑み、電極の温度安定を計って電極消耗を押さえ、かつ作業効率を落とすことなく安定的にスポット溶接を行えるスポット溶接装置を提供することにある。
【０００６】
【課題を解決するための手段】
上述した課題を解決するために、本発明の請求項１記載のスポット溶接装置においては、複数の溶接部を有する溶接対象物の各溶接部を順次切替えて連続して溶接が行われるものであって、主電極と副電極とで一対の溶接電極を構成するとともに、一つの溶接対象物の複数の溶接部の数より少ない数となる複数の溶接電極を備え、前記溶接対象物の複数の溶接部を複数の溶接電極にて順次溶接するとき、次ぎの異なる溶接部の溶接に際し、直前の溶接時における溶接電極とは異なる溶接電極にて溶接を行い、且つ前記溶接対象物の複数の溶接部を全て溶接するとき、少なくとも一対の溶接電極は複数回使用されるように、溶接電極が順次切替えられる電極切替え手段を有している。
【０００７】
それにより、一対の電極が連続して各ワークを溶接することがなくなり再度その一対の電極が溶接に供されるまでの時間を長く設定可能となる。このことは、一対の電極の冷やされる時間を稼ぐことができるとともに、ワークの送り速度を遅くすることなく電極の温度安定が可能となる。このように、電極の温度を安定させれば、電極間に通電される溶接電流も安定して溶接状態を安定させることができる。つまり、電極の温度安定を計って電極消耗を押さえ、かつ作業効率を落とすことなく安定的にスポット溶接を行えるスポット溶接装置を提供できる。
【０００８】
本発明の請求項２の記載によるスポット溶接装置では、順次切替えて連続使用される複数組みの一対の電極が一巡した以降の繰返し溶接時（即ち、複数回使用される溶接電極が、同一の溶接対象物における次の異なる溶接部を溶接するために使用されるとき）、当該電極の先端部温度が既定温度領域を維持するように、少なくとも複数の溶接電極の数と前記ワーク（溶接部）の送り速度とのいずれか一方を適合させる（決定する）ことを特徴としている。
【０００９】
このように、切替え使用される一対の電極の組数、あるいはワーク（溶接部）の送り速度の少なくとも一方を適合することで、電極切替え手段を構成させるスポット溶接装置の体格規模と作業効率の双方を両立できる適合が行われ、電極の先端部温度が既定温度領域に維持されるスポット溶接装置を提供できる。
また、本発明の請求項３に記載のスポット溶接装置は、回転方向に複数の溶接部を有する溶接対象物（２）を回転可能に保持するワーク保持部（１１）と、複数の主電極（４）を保持する電極保持部（５）と、電極保持部（５）を搭載して、上下方向に移動可能な移動体ブロック（６）と、移動体ブロック（６）を水平方向に移動可能に保持する第１スライドレール（７）と、複数の副電極（８）を支持する副電極ブロック（９）と、副電極ブロック（９）を搭載して、上下方向に移動可能な支持台（１０）と、支持台（１０）を水平方向に移動可能に保持する第２スライドレール（１２）とを備え、一つの溶接部の溶接が終了すると、次の溶接部の溶接のために溶接対象物（２）がワーク保持部（１１）により回転され、かつ前記移動体ブロック（６）及び副電極ブロック（９）が第１スライドレール（７）及び第２スライドレールに沿って、水平方向に移動することを特徴としている。
更に、本発明の請求項４に記載のスポット溶接装置においては、電極保持部（５）に、主電極（４）の溶接時における温度上昇を抑えるための冷却ブロック（５Ａ）が形成されていることを特徴としている。
更に、本発明の請求項５に記載のスポット溶接装置においては、溶接すべき溶接対象物（２）が位置決めされた後、前記副電極（８）が前記溶接部の外周面に当接されるとともに、前記主電極（４）が２つの副電極（８）の空間に入り込み、前記溶接部の外周面に圧接されて、前記主電極（４）と副電極（８）との間に溶接電流を流すことにより溶接を行うことを特徴としている。
また、本発明の請求項６に記載のスポット溶接装置は、回転方向に設けられた複数の溶接部を有する溶接対象物（２）における各溶接部を順次切替え、連続してスポット溶接を行うスポット溶接装置に関するものである。この溶接装置は、主電極（４）と副電極（８）とで一対の電極を構成する溶接電極を複数組み備えている。更に、主電極（４）を保持する電極保持部（５）と、電極保持部（５）を溶接部に近づく方向に移動可能とさせて搭載される移動体ブロック（６）と、移動体ブロック（６）を各主電極（４）の並ぶ方向へ移動可能に保持する第１スライドレール（７）と、副電極（８）を支持する副電極ブロック（９）と、副電極ブロック（９）を溶接部に近づく方向に移動可能とさせて搭載される支持台（１０）と、支持台（１０）を各副電極（８）の並ぶ方向へ移動可能に保持する第２スライドレール（１２）と、溶接部を回転可能に保持するワーク保持部（１１）を備えている。そして、一つの溶接部の溶接が終了すると、次の溶接部の溶接のために溶接対象物（２）がワーク保持部（１１）により回転され、かつ移動体ブロック（６）及び副電極ブロック（９）を第１スライドレール（７）及び第２スライドレールに沿って、移動させるものである。
【００１０】
【発明の実施の形態】
以下、本発明の一実施形態であるスポット溶接装置を図面を参照して詳細に説明する。なお、以下説明するスポット溶接装置は、ワーク（被溶接部）を一対の電極間にセットし、その電極間に溶接電流を流すことでワークに抵抗発熱を生じさせてスポット溶接が行われる。そして、ワークを順次切替えて連続して行われるスポット溶接装置であって、このスポット溶接装置における電極の先端部の温度安定を計って電極消耗を押さえ、かつ作業効率を落とすことなく安定的にスポット溶接（以降、単に溶接と呼称する。）が行える技術に関する。
【００１１】
図１は、本発明のスポット溶接装置１を示す全体構成図であり、図１（ａ）は、正面図、図１（ｂ）は、側面図である。図２は、図１中のワークとしてのアーマチュア２のコンミテータ部３周辺を示す部分拡大図である。図３は、図２中のＢ部を示す部分拡大図である。なお、前記したアーマチュア２は、図示しないフューエルポンプの一構成部品である。
【００１２】
スポット溶接装置１は、主電極支持構成体、副電極支持構成体、およびワーク支持構成体等から構成される。主電極支持構成体は、棒形状の複数本の主電極４、この複数本の主電極４を保持する電極保持部５、電極保持部５を図１中上下方向に移動可能とさせて搭載される移動体ブロック６、およびこの移動体ブロック６を図１中左右方向に移動可能に保持する第１スライドレール７等を備えている。前記した電極保持部５、移動体ブロック６、および第１スライドレール７は、請求項１に記載の電極切替え手段を構成している。なお、電極保持部５の一部は、主電極４の先端部近傍と接触しながら摺動可能に案内する冷却ブロック５Ａが形成される。この冷却ブロック５Ａは、主電極４の溶接時における温度上昇を抑える冷却効果を持つ。
【００１３】
副電極指示構成体は、上記した複数本の主電極４に対応させた数の副電極８、この複数本の副電極８を支持する副電極ブロック９、副電極ブロック９が図１中上下方向に移動可能とさせて搭載される支持台１０、およびこの支持台を１０図１中左右方向に移動可能に保持する第２スライドレール１２等を備えている。本実施形態では、主電極４および副電極８からなる一対の電極（溶接電極）４、８を４組備える。なお、本実施形態に示す一対の溶接電極４，８を構成する内の副電極８は、副電極ブロック９から延びる２つの電極板からなり（図3（ａ）参照）、２つの電極板の間の空間に主電極４が両者４、８を直接に接触させることなく配設可能とする構成である。
【００１４】
ワーク支持構成体は、アーマチュア２を保持するとともにアーマチュア２を回転させるワーク保持部１１を備え、このワーク保持部１１は、支持台１０とは別の部位置に保持されており図示を省略する。なお、アーマチュア２（溶接対象物）は、ワーク（溶接部）としてのコンミテータ部３を８個（８極）有しており、前述したようにアーマチュア２を回転させることによりワーク（コンミテータ部３）を順次切替える動作を行う。
【００１５】
上記した主電極４および副電極８によってコンミテータ部３が溶接される構成を図３を用いて説明する。コンミテータ部３は、コンミテータ部３より延設される爪部３Ａを有し、アーマチュア２よりの巻線が爪部３Ａに巻回されたのちに爪部３Ａを湾曲させながらコンミテータ部３と溶接させる構成である（詳細は図示省略する）。つまり、溶接すべきコンミテータ部３が位置決めされたのち副電極８がコンミテータ部３へ当接され、主電極４が各々コンミテータ部に圧接されて図３中破線に示す状態に変形しコンミテータ部３へ爪部３Ａの先端側が接触される。そして、この接触状態から主電極４および副電極８間に溶接電流が通電され、コンミテータ部３と爪部３Ａの両者を溶融接合させる溶接が行われる。
【００１６】
次に、図３に述べた一対の電極４、８を用いて、１つのワーク（コンミテータ部３）の溶接が行われたのちにおけるコンミテータ部３を順次切替え、連続して溶接が行われる本発明のスポット溶接装置１について、図４および図５を用いて以下説明する。図４は、図１中のスポット溶接装置１を用いた電極４、８の切替え状態を示す状態図であり、図４（ａ）は、電極４、８の切替え前状態図、図４（ｂ）は、電極４、８の切替え後状態図である。図５は、電極４、８の温度が所定温度領域（後述する）に安定する原理を説明する説明図である。
【００１７】
図４（ａ）に示す状態は、溶接が行われたのちに電極保持部５が図４中上方に移動して主電極４が爪部３Ａから離され、副電極８は副電極ブロック９が図４中上方向に移動してコンミテータ部３から離された状態であり、図５中（イ）点にこの溶接前時の主電極４の先端部温度を示す。なお、本実施形態にて示す一対の電極４、８において、主電極４の先端部と爪部３Ａとの接触面積は、副電極８とコンミテータ部３との接触面積に比して小さく形成させてあり、溶接時における温度は主電極４の先端部の方が副電極８の先端部より高温度となる。このことから、図５中に示す電極先端部温度とはこの主電極４の先端部の温度を示し、以降、説明の便宜上、主電極４先端部の温度についてのみ記す。
【００１８】
図４（ａ）に示す状態からコンミテータ部３の切替えおよび一対の電極４、８の切替えが行われて図４（ｂ）に示す状態となる。つまり、ワーク保持部１１によりアーマチュア２が図４（ｂ）中Ｃ方向に回転され、未溶接のコンミテータ部３へ切替えられる。そして、第１スライドレール７上を移動体ブロック６が図４（ｂ）中Ｄ方向に移動、および第２スライドレール１２上を支持台１０が図４（ｂ）中Ｅ方向に移動し、４組みの一対の電極４、８の内の次（先使用の一対の電極の隣りに位置する）の一対の電極４、８へ切替えられる。この後、電極保持部５および副電極ブロック９が図４（ｂ）中下方向に移動され、図３の説明時に述べたのと同要領にて溶接が行われる。
【００１９】
この切替えられた溶接前時における主電極４先端部の温度を図５中（ロ）点に示す。つまり、前述した図５中（イ）点とほぼ同温度である。図５中（ハ）に示す主電極４先端部の温度特性線は、同一の一対の電極４、８を用いて繰り返し同一の溶接条件にて連続するコンミテータ部３の溶接が行われた場合を示す。つまり、先の溶接後から次の溶接前の時間間隔が充分に取られておらず、この状態にて溶接が繰り返されると溶接前時における主電極４先端部の温度は右肩上がりに上昇していく。
【００２０】
そこで、本発明の前記した電極切替え手段を用いれば、４組の溶接電極４，８が連続して各ワークを溶接することを終了してから、一巡されて再度その４組の溶接電極４，８が溶接に供されるまでの時間（図５中Ｔであり、本実施形態では約８秒）を長く設定可能となり、図５中（ホ）に示す主電極４先端部の温度特性線となる。なお、温度特性線（ハ）、（ホ）ともに、図示の便宜上実際の溶接時における温度特性とは異なる表記である。例えば、溶接電流が通電された際の主電極４先端部の最高温度は、約９００℃である。
【００２１】
図５中（ニ）点は、４組の一対の電極４、８が一巡した時に図５中（イ）点とほぼ同温度に一対の電極４、８が冷やされ、既定温度領域に維持できた状態を示す。なお、この既定温度領域とは、図５中のＬ１、Ｌ２ラインの範囲内温度のことを示し、電極４、８の温度を安定させることにより電極４、８間に通電させる溶接電流を安定させて溶接状態を安定させている。本実施形態では、Ｌ１、Ｌ２の温度を各々３０℃、４０℃としている。
【００２２】
このように構成させたスポット溶接装置１は、切替え使用される一対の電極４、８の組数、およびワークの送り速度の双方を適合させて溶接前の電極４温度を既定温度領域に維持させている。それにより、溶接の作業効率と、電極４の温度安定による電極４の消耗抑制効果のあるスポット溶接装置１となる。
【００２３】
なお、本発明の実施にあたり、既定温度領域を維持するように切替え使用される一対の電極４、８の組数、およびワークの送り速度の双方を適合させたが、切替え使用される一対の電極４、８の組数、あるいはワークの送り速度の少なくとも一方が適合されればよい。それにより、電極切替え手段を構成させるスポット溶接装置の体格規模と溶接の作業効率の双方を両立できる適合が行われ、電極４、８の先端部温度が既定温度領域に維持されるスポット溶接装置を提供できる。
【図面の簡単な説明】
【図１】本発明のスポット溶接装置を示す全体構成図であり、
（ａ）は、正面図、
（ｂ）は、側面図である。
【図２】図１中のワークとしてのアーマチュアのコンミテータ部周辺を示す部分拡大図である。
【図３】図２中のＢ部を示す部分拡大図である。
【図４】図１中のスポット溶接装置を用いた電極の切替え状態を示す状態図であり、
（ａ）は、電極の切替え前状態図、
（ｂ）は、電極の切替え後状態図である。
【図５】電極の温度が所定温度領域に安定する原理を説明する説明図である。
【符号の説明】
１スポット溶接装置
３アーマチュアのコンミテータ部（ワークの一部を構成）
４主電極（一対の電極の一方を構成）
５電極支持部（電極切替え手段の一部を構成）
６移動体ブロック（電極切替え手段の一部を構成）
７第１スライドレール（電極切替え手段の一部を構成）
８副電極（一対の電極の他方を構成）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spot welding apparatus in which a workpiece is set between a pair of electrodes and a resistance current is generated in the workpiece by flowing a welding current between the electrodes. The present invention relates to a spot welding apparatus.
[0002]
[Prior art]
In spot welding, which is performed continuously by sequentially switching workpieces, a pair of electrodes are pressed against the workpiece (the part to be welded), and a welding current is passed between the electrodes to cause resistance heating in the workpiece. The workpiece is spot welded. A spot welding apparatus is known in which workpieces are sequentially switched and spot welding is repeatedly performed on the continuous workpieces using the same pair of electrodes. When spot welding is repeatedly performed on the continuous workpiece using the same pair of electrodes, the temperature of these electrodes is increased as the workpiece is switched in accordance with the number of weldings. When spot welding is performed on the continuous workpieces under the same welding conditions while the temperature is raised, the welding state becomes unstable and welding failure occurs. Specifically, an increase in the temperature of the electrodes decreases the energization resistance between the electrodes and increases the energization current value. And the temperature of the workpiece | work heated by this increase in an energization current rises, it is made to melt at high temperature, and it leads to welding defect, such as a deformation | transformation of a welding part periphery or a welding strength fall of a welding part.
[0003]
Therefore, when spot welding is performed on continuous workpieces, measures are taken such as changing and controlling the welding conditions for each workpiece. As countermeasures, for example, measures such as shortening the energization time, reducing the energization current to lower the melting temperature of the welded part, or slowing the workpiece feed rate to increase the time for the electrode to cool down are performed. Yes.
[0004]
[Problems to be solved by the invention]
However, countermeasures such as changing and controlling the welding conditions for each workpiece make it difficult to adjust the temperature at which the workpiece is melted to the appropriate temperature, and the control device is expensive and complicated. Also, if the time for which the electrode is cooled is set by slowing the workpiece feed rate so as to keep the temperature of the electrode at a constant temperature, the working efficiency is lowered. Furthermore, when the temperature of the electrode is not maintained in a predetermined temperature range and becomes high, there is a problem that the electrode is consumed.
[0005]
An object of the present invention is to provide a spot welding apparatus that measures the temperature stability of an electrode to suppress electrode consumption and can perform spot welding stably without reducing work efficiency.
[0006]
[Means for Solving the Problems]
To solve the problems described above, Oite spot welding apparatus according to claim 1 of the present invention are those welded continuously by sequentially switching each weld of the welding object having a plurality of welds is carried out The main electrode and the sub electrode constitute a pair of welding electrodes, and a plurality of welding electrodes that are smaller than the number of the plurality of welding portions of one welding object are provided, and a plurality of the welding objects are provided. When sequentially welding the welded parts of the welding object with a plurality of welding electrodes, welding is performed with a welding electrode different from the welding electrode at the time of the immediately preceding welding when welding the next different welded part, and a plurality of the welding objects When all the welds are welded, an electrode switching means for sequentially switching the welding electrodes is provided so that at least a pair of welding electrodes are used a plurality of times .
[0007]
Thus, the pair of electrodes do not continuously weld each workpiece, and the time until the pair of electrodes is subjected to welding again can be set longer. This makes it possible to gain time for the pair of electrodes to be cooled and to stabilize the temperature of the electrodes without slowing down the work feed speed. Thus, if the temperature of an electrode is stabilized, the welding current supplied between electrodes can also be stabilized and a welding state can be stabilized. That is, it is possible to provide a spot welding apparatus that measures electrode temperature stability to suppress electrode consumption and that can perform spot welding stably without reducing work efficiency.
[0008]
In the spot welding apparatus according to the second aspect of the present invention, a plurality of pairs of electrodes that are sequentially switched and used continuously are cycled after a round of welding (that is, the welding electrodes that are used a plurality of times are the same welding). When used to weld the next different welds in the object) , at least the number of welding electrodes and the number of the workpieces (welds) so that the tip temperature of the electrodes maintains a predetermined temperature range. It is characterized by adapting (determining) one of the feed speeds.
[0009]
Thus, by adapting at least one of the number of pairs of electrodes used for switching or the feed speed of the workpiece (welding part) , both the physique scale and work efficiency of the spot welding apparatus constituting the electrode switching means Thus, the spot welding apparatus can be provided in which the fitting that can satisfy both requirements is performed and the tip temperature of the electrode is maintained in a predetermined temperature range.
Moreover, the spot welding apparatus according to claim 3 of the present invention includes a workpiece holding portion (11) that rotatably holds a welding object (2) having a plurality of welding portions in a rotation direction, and a plurality of main electrodes ( 4) The electrode holder (5) that holds the electrode, the electrode holder (5), and the movable block (6) that can move in the vertical direction and the movable block (6) can be moved in the horizontal direction. The first slide rail (7) held on the sub-electrode, the sub-electrode block (9) supporting the plurality of sub-electrodes (8), and the support base (9) mounted with the sub-electrode block (9) and movable in the vertical direction 10) and a second slide rail (12) that holds the support base (10) so as to be movable in the horizontal direction. When the welding of one welded portion is completed, the object to be welded is welded for the next welded portion. The object (2) is rotated by the work holding part (11), and the movable body block is Click (6) and the sub electrode block (9) along the first slide rails (7) and the second slide rail, and thus being moved in the horizontal direction.
Furthermore, in the spot welding apparatus according to claim 4 of the present invention, the electrode holding part (5) is formed with a cooling block (5A) for suppressing a temperature rise during welding of the main electrode (4). It is characterized by that.
Furthermore, in the spot welding apparatus according to claim 5 of the present invention, after the welding object (2) to be welded is positioned, the auxiliary electrode (8) is brought into contact with the outer peripheral surface of the welded portion. At the same time, the main electrode (4) enters the space of the two sub-electrodes (8), is pressed against the outer peripheral surface of the welded portion, and a welding current is generated between the main electrode (4) and the sub-electrode (8). It is characterized in that welding is performed by flowing.
Moreover, the spot welding apparatus according to claim 6 of the present invention is a spot for performing spot welding continuously by sequentially switching each welded portion in the welding object (2) having a plurality of welded portions provided in the rotation direction. The present invention relates to a welding apparatus. This welding apparatus includes a plurality of sets of welding electrodes that constitute a pair of electrodes by a main electrode (4) and a sub electrode (8). Furthermore, an electrode holding part (5) for holding the main electrode (4), a moving body block (6) mounted such that the electrode holding part (5) can be moved in a direction approaching the welded part, and a moving body block A first slide rail (7) for holding (6) movably in the direction in which the main electrodes (4) are arranged, a sub-electrode block (9) for supporting the sub-electrode (8), and a sub-electrode block (9) And a second support rail (12) for holding the support base (10) movably in the direction in which the sub-electrodes (8) are arranged. And a work holding part (11) for holding the welded part rotatably. And when welding of one welding part is complete | finished, a welding target object (2) is rotated by the workpiece holding part (11) for welding of the next welding part, and a mobile body block (6) and a sub-electrode block ( 9) is moved along the first slide rail (7) and the second slide rail.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a spot welding apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. In the spot welding apparatus described below, a workpiece (a portion to be welded) is set between a pair of electrodes, and a welding current is passed between the electrodes to cause resistance heat generation in the workpiece and spot welding is performed. And it is a spot welding device that is continuously performed by sequentially switching workpieces, and by measuring the temperature stability of the tip of the electrode in this spot welding device, it suppresses electrode consumption and stably spot without reducing work efficiency The present invention relates to a technique capable of performing welding (hereinafter simply referred to as welding).
[0011]
FIG. 1 is an overall configuration diagram showing a spot welding apparatus 1 according to the present invention, in which FIG. 1 (a) is a front view and FIG. 1 (b) is a side view. FIG. 2 is a partially enlarged view showing the periphery of the commutator portion 3 of the armature 2 as the work in FIG. FIG. 3 is a partially enlarged view showing a portion B in FIG. The armature 2 described above is a component part of a fuel pump (not shown).
[0012]
The spot welding apparatus 1 includes a main electrode support structure, a sub electrode support structure, a work support structure, and the like. The main electrode support structure is mounted with a plurality of rod-shaped main electrodes 4, an electrode holding portion 5 that holds the plurality of main electrodes 4, and the electrode holding portion 5 that can move in the vertical direction in FIG. 1. 1 and a first slide rail 7 for holding the movable body block 6 so as to be movable in the left-right direction in FIG. The electrode holding part 5, the movable body block 6, and the first slide rail 7 described above constitute the electrode switching means according to claim 1. A part of the electrode holding portion 5 is formed with a cooling block 5 </ b> A that is slidably guided while being in contact with the vicinity of the tip of the main electrode 4. The cooling block 5 </ b> A has a cooling effect that suppresses a temperature rise during welding of the main electrode 4.
[0013]
The sub-electrode indicating structure includes a number of sub-electrodes 8 corresponding to the plurality of main electrodes 4, the sub-electrode block 9 supporting the plurality of sub-electrodes 8, and the sub-electrode block 9 in the vertical direction in FIG. support 10 mounted by movable, and the support base and a second slide rail 12 such that movably held in the lateral direction in FIG. 10 1. In the present embodiment, four sets of a pair of electrodes (welding electrodes) 4 and 8 including a main electrode 4 and a sub electrode 8 are provided. In addition, the sub electrode 8 which comprises a pair of welding electrodes 4 and 8 shown to this embodiment consists of two electrode plates extended from the sub electrode block 9 (refer Fig.3 (a)), Between two electrode plates In this configuration, the main electrode 4 can be arranged in the space without directly contacting the both 4 and 8.
[0014]
The workpiece support structure includes a workpiece holder 11 that holds the armature 2 and rotates the armature 2, and the workpiece holder 11 is held at a position different from the support base 10 and is not illustrated. The armature 2 (object to be welded ) has eight (8 poles) commutator portions 3 as workpieces (welded portions) , and the workpiece (commutator portion 3) is rotated by rotating the armature 2 as described above. The operation of sequentially switching is performed.
[0015]
A configuration in which the commutator portion 3 is welded by the main electrode 4 and the sub electrode 8 will be described with reference to FIG. The commutator part 3 has a claw part 3A extending from the commutator part 3, and after the winding from the armature 2 is wound around the claw part 3A, it is welded to the commutator part 3 while curving the claw part 3A. The configuration (details are not shown). That is, after the commutator section 3 to be welded is positioned, the sub-electrode 8 is brought into contact with the commutator section 3, and the main electrodes 4 are respectively brought into pressure contact with the commutator section and deformed into the state shown by the broken lines in FIG. 3 to the commutator section 3. The tip side of the claw portion 3A is brought into contact. Then, a welding current is passed between the main electrode 4 and the sub electrode 8 from this contact state, and welding is performed to melt and join both the commutator portion 3 and the claw portion 3A.
[0016]
Next, using the pair of electrodes 4 and 8 described in FIG. 3, the welding of a single workpiece (commutator portion 3) is performed after the commutator portion 3 is sequentially switched, and welding is continuously performed. The spot welding apparatus 1 will be described below with reference to FIGS. 4 and 5. 4 is a state diagram showing a switching state of the electrodes 4 and 8 using the spot welding apparatus 1 in FIG. 1, and FIG. 4A is a state diagram before the switching of the electrodes 4 and 8, and FIG. ) Is a state diagram after the electrodes 4 and 8 are switched. FIG. 5 is an explanatory diagram for explaining the principle that the temperatures of the electrodes 4 and 8 are stabilized in a predetermined temperature region (described later).
[0017]
In the state shown in FIG. 4A, after the welding is performed, the electrode holding portion 5 moves upward in FIG. 4 so that the main electrode 4 is separated from the claw portion 3A. FIG. 4 shows a state in which it has moved upward and separated from the commutator 3, and the temperature at the tip of the main electrode 4 before welding is shown at point (A) in FIG. 5. In the pair of electrodes 4 and 8 shown in the present embodiment, the contact area between the tip of the main electrode 4 and the claw 3A is made smaller than the contact area between the sub electrode 8 and the commutator 3. The temperature at the time of welding is higher at the tip of the main electrode 4 than at the tip of the sub electrode 8. Therefore, the electrode tip temperature shown in FIG. 5 indicates the temperature of the tip of the main electrode 4, and only the temperature of the tip of the main electrode 4 will be described below for convenience of explanation.
[0018]
From the state shown in FIG. 4A, the commutator 3 is switched and the pair of electrodes 4 and 8 are switched, resulting in the state shown in FIG. 4B. That is, the armature 2 is rotated in the direction C in FIG. 4B by the work holding part 11 and switched to the unwelded commutator part 3. Then, the movable body block 6 moves on the first slide rail 7 in the direction D in FIG. 4B, and the support base 10 moves on the second slide rail 12 in the direction E in FIG. 4B. It is switched to the next pair of electrodes 4 and 8 (located next to the pair of previously used electrodes) out of the pair of electrodes 4 and 8 in the set. Thereafter, the electrode holding portion 5 and the sub electrode block 9 are moved downward in FIG. 4B, and welding is performed in the same manner as described in the description of FIG.
[0019]
The temperature at the front end portion of the main electrode 4 at the time before the switched welding is indicated by a point (b) in FIG. That is, the temperature is substantially the same as the point (A) in FIG. The temperature characteristic line at the tip of the main electrode 4 shown in FIG. 5 (C) shows the case where the continuous commutator 3 is welded repeatedly using the same pair of electrodes 4 and 8 under the same welding conditions. Show. That is, the time interval between the previous welding and the next welding is not sufficiently taken, and if welding is repeated in this state, the temperature of the front end of the main electrode 4 rises to the right. To go.
[0020]
Therefore, by using the above-described electrode switching means of the present invention, the four sets of welding electrodes 4 and 8 are finished to continuously weld each workpiece, and then the four sets of welding electrodes 4 and 4 are made again. 8 can be set to a long time (T in FIG. 5; about 8 seconds in this embodiment) until welding is performed, and the temperature characteristic line at the tip of the main electrode 4 shown in FIG. Become. The temperature characteristic lines (c) and (e) are different from the actual temperature characteristics during welding for convenience of illustration. For example, the maximum temperature of the front end portion of the main electrode 4 when a welding current is applied is about 900 ° C.
[0021]
Point (d) in FIG. 5 can be maintained in a predetermined temperature range by cooling the pair of electrodes 4 and 8 at substantially the same temperature as point (b) in FIG. 5 when the four pairs of electrodes 4 and 8 make a round. Indicates the state. In addition, this predetermined temperature range | region shows the temperature within the range of the L1 and L2 line in FIG. 5, and stabilizes the welding current energized between the electrodes 4 and 8 by stabilizing the temperature of the electrodes 4 and 8. To stabilize the welding state. In the present embodiment, the temperatures of L1 and L2 are 30 ° C. and 40 ° C., respectively.
[0022]
The spot welding apparatus 1 configured as described above maintains both the temperature of the electrode 4 before welding in a predetermined temperature range by adapting both the number of pairs of electrodes 4 and 8 used for switching and the feed rate of the workpiece. ing. As a result, the spot welding apparatus 1 has the effect of suppressing the wear of the electrode 4 due to the welding work efficiency and the temperature stability of the electrode 4.
[0023]
In carrying out the present invention, both the number of pairs of electrodes 4 and 8 used for switching so as to maintain the predetermined temperature range and the feed rate of the workpiece are adapted, but the pair of electrodes used for switching is used. It is sufficient that at least one of the number of groups of 4 and 8 or the feed speed of the workpiece is adapted. As a result, a spot welding apparatus in which both the size of the spot welding apparatus constituting the electrode switching means and the work efficiency of the welding are compatible, and the tip temperature of the electrodes 4 and 8 is maintained in the predetermined temperature range. Can be provided.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing a spot welding apparatus of the present invention,
(A) is a front view,
(B) is a side view.
2 is a partially enlarged view showing the vicinity of a commutator portion of an armature as a work in FIG. 1. FIG.
FIG. 3 is a partially enlarged view showing a portion B in FIG. 2;
4 is a state diagram showing a switching state of electrodes using the spot welding apparatus in FIG. 1,
(A) is a state diagram before switching electrodes,
(B) is a state diagram after switching of electrodes.
FIG. 5 is an explanatory diagram for explaining the principle that the temperature of an electrode is stabilized in a predetermined temperature range.
[Explanation of symbols]
1 Spot welding equipment 3 Armature commutator (part of the work)
4 Main electrode (constitutes one of a pair of electrodes)
5 Electrode support (constitutes part of electrode switching means)
6 Mobile block (part of electrode switching means)
7 First slide rail (part of electrode switching means)
8 Sub-electrode (constitutes the other of the pair of electrodes)

Claims

In a spot welding apparatus in which spot welding is performed successively by sequentially switching each welding part in a welding object having a plurality of welding parts ,
A main electrode and a sub electrode constitute a pair of welding electrodes, and include a plurality of welding electrodes that are less than the number of the plurality of welding portions of the one welding object,
When welding a plurality of welded portions of the welding object sequentially with a plurality of welding electrodes, when welding the next different welded portion, welding is performed with a welding electrode different from the welding electrode at the time of the previous welding, and A spot welding apparatus comprising electrode switching means for sequentially switching welding electrodes so that at least a pair of welding electrodes are used a plurality of times when all of a plurality of welds of a welding object are welded. .

When a welding electrode that is used multiple times is used to weld the next different welds of the same welding object , at least a plurality of the welding electrode tip temperatures maintain a predetermined temperature range . The spot welding apparatus according to claim 1, wherein one of a number of welding electrodes and a feed rate of the welding portion is determined .

A work holding part (11) for rotatably holding a welding object (2) having a plurality of welding parts in the rotation direction;
An electrode holder (5) for holding the plurality of main electrodes (4);
A movable body block (6) mounted with the electrode holding portion (5) and movable in the vertical direction;
A first slide rail (7) for holding the movable body block (6) so as to be movable in the horizontal direction;
A sub-electrode block (9) supporting the plurality of sub-electrodes (8);
A support base (10) mounted with the sub-electrode block (9) and movable in the vertical direction;
A second slide rail (12) that holds the support (10) in a horizontally movable manner,
When the welding of one welded portion is finished, the welding object (2) is rotated by the work holding portion (11) for welding of the next welded portion, and the movable body block (6) and the sub electrode block (9 2. The spot welding device according to claim 1, wherein the spot welding device moves horizontally along the first slide rail (7) and the second slide rail (12).

The spot welding device according to claim 3, wherein the electrode holding part (5) is formed with a cooling block (5A) for suppressing a temperature rise during welding of the main electrode (4).

After the welded portion of the welding object (2) to be welded is positioned, the sub-electrode (8) is brought into contact with the outer peripheral surface of the welded portion, and the main electrode (4) has two sub-electrodes ( The welding is performed by flowing into the space of 8), being pressed against the outer peripheral surface of the welded portion, and passing a welding current between the main electrode (4) and the sub electrode (8). 3. The spot welding apparatus according to 3.

In the spot welding apparatus in which spot welding is performed by successively switching each welding portion in the welding object (2) having a plurality of welding portions provided in the rotation direction,
A plurality of sets of welding electrodes that constitute a pair of electrodes by the main electrode (4) and the sub electrode (8),
An electrode holder (5) for holding the main electrode (4);
A movable body block (6) mounted such that the electrode holder (5) is movable in a direction approaching the welded portion;
A first slide rail (7) for holding the movable body block (6) movably in the direction in which the main electrodes (4) are arranged;
A sub-electrode block (9) supporting the sub-electrode (8);
A support base (10) mounted so that the sub electrode block (9) is movable in a direction approaching the welded portion;
A second slide rail (12) for holding the support base (10) movably in the direction in which the sub-electrodes (8) are arranged;
A work holding part (11) for holding the welded part rotatably,
When the welding of one welded portion is finished, the welding object (2) is rotated by the work holding portion (11) for welding of the next welded portion, and the movable body block (6) and the sub electrode block (9 ) Moves along the first slide rail (7) and the second slide rail.

The number of the plurality of sets of welding electrodes is configured as a number smaller than the number of the plurality of welds of the one welding object,
When welding a plurality of welded portions of the welding object sequentially with a plurality of sets of welding electrodes, when welding the next different welded portion, welding is performed with a welding electrode different from the welding electrode at the previous welding, and The spot welding apparatus according to claim 6, wherein when welding a plurality of welds of the welding object, the welding electrodes are sequentially switched so that at least a pair of welding electrodes are used a plurality of times.

When a welding electrode that is used multiple times is used to weld the next different welds of the same welding object, at least a plurality of the welding electrode tip temperatures maintain a predetermined temperature range. The spot welding apparatus according to claim 7, wherein one of a number of welding electrodes and a feed rate of the welding portion is determined.

The cooling block (5A) for suppressing the temperature rise at the time of welding of the main electrode (4) is formed in the electrode holding part (5). 6 The spot welding apparatus in any one of thru | or 8.

After the welded portion of the welding object (2) to be welded is positioned, the sub-electrode (8) is brought into contact with the outer peripheral surface of the welded portion, and the main electrode (4) has two sub-electrodes ( The welding is performed by flowing into the space of 8), being pressed against the outer peripheral surface of the welded portion, and passing a welding current between the main electrode (4) and the sub electrode (8). The spot welding apparatus according to any one of 6 to 9.