JPS625711B2 - - Google Patents

Description

【発明の詳細な説明】[Detailed description of the invention]

本発明は金属缶胴の製造方法及び装置に関し、
さらに詳しくは電気抵抗溶接法により側面重ね合
せ部をマツシユシーム溶接された金属缶胴の製造
方法に関する。 エアロゾール缶、ビール缶、粉末コーヒー缶、
18リツトル缶等の溶接金属缶胴の製造方法とし
て、従来広く行なわれている方法は缶胴成形体の
重ね合せ部を一対の回定位置回転ローラ電極の間
に挿入して移行せしめながら電極間に交流電流を
印加して重ね合せ部をシーム溶接する方法であ
る。この場合ローラ電極の損耗を避けるため回転
ローラ電極と重ね合せ部の間に線電極を介挿して
シーム溶接する方法も広く行なわれている。これ
らの方法に共通する問題点は、缶の内面となるべ
き溶接部の性状が良好でないため保護塗料で補修
しても缶内容物の種類によつては十分な耐食性が
得られないこと、ならびに溶接部の両端部に溶接
線に沿つて突起（一種の熱間圧延効果によると考
えられる）が生じ、この突起が缶端板を２重巻締
するさいシーリングラバーを破つて内容物の漏洩
を招き易いことである。さらにこれらの点を詳細
に説明すれば、従来の技術には次のような欠点が
挙げられる。(1)溶接中に不活性ガスを吹きつける
等の特殊な操作を行なわない限り溶接部が酸化し
て黒色の酸化膜を生成する（特に低炭素鋼板およ
び表面処理鋼板を使用する場合）。この酸化膜は
脆くかつ基金属との密着性が乏しいため、２種巻
締の曲げ加工部において、この酸化膜の上に塗布
された内面保護塗料が剥離して、缶内容物による
基金属の腐食を起こし易い。(2)溶接部に円周方向
に沿つて発生する段差を減少させるため、加圧力
を大きくすると、円周方向に金属（重ね合せ部側
縁部の）の不均一なはみ出しが起こり、このはみ
出し部の下面の隙間を保護塗料によつて外部と完
全に遮断することができないか、できたとしても
多量の保護塗料を必要とする。(3)前述のように溶
接部の両端部に突起を生じ、このため二重巻締部
よりの漏洩を招き易い。 本発明は以上のような従来技術の問題点の解消
を図ろうとするものである。 すなわち本発明の目的は、不活性ガス等を使用
しなくとも、特に缶内面側における溶接部に酸化
膜の生成が殆んど起らない溶接金属缶胴の製造方
法を提供することである。本発明の他の目的は、
特に缶内面側における溶接部の段差が軽微で、か
つ金属の円周方向のはみ出しが実質的にない溶接
金属缶胴の、比較的生産性の高い製造方法を提供
することである。 本発明によれば、金属薄板のブランクから、側
辺に重ね合せ部を有する缶胴成形体を成形し、該
缶胴成形体を第１の軸線方向に送つて、該重ね合
せ部を直径50mm以上の回動電極と、縦長電極の間
に、該重ね合せ部の内面が該縦長電極と接触する
ように挿入して、該縦長電極上に該重ね合せ部を
定置し、該重ね合せ部の該成形体円周方向全巾を
該回動電極と縦長電極の電極面に接触させた状態
で、加圧下に該回動電極を先行の缶胴成形体の場
合の回動方向と逆向きに回動せしめ、同時に該回
動電極と縦長電極間に通電して該重ね合せ部をマ
ツシユシーム溶接して、すくなくとも該缶胴体内
面側にて中周方向の金属のはみ出しが実質的にな
い溶接部を有する金属缶胴を形成した後、該金属
缶胴を第１の軸線方向に送出することを特徴とす
る金属缶胴の製造方法が提供される。 以下本発明について詳細に説明する。 本発明に使用される金属薄板の種類には特に制
限はないが、黒板（無被覆低炭素鋼板）及びブリ
キ、燐酸塩処理鋼板、ニツケルメツキ鋼板等の表
面処理鋼板及びアルミニウム又はアルミニウム合
金板ならびにこれらの塗装板等が好適に使用され
る。表面に絶縁性皮膜を有する場合は、所定の寸
法に裁断されたブランクの重ね合せ部となるべき
両側辺部表面から絶縁性皮膜をミリングカツタ
ー、グラインダー、バイト等の機械的手段又は超
音波印加法等によつて除去することが好ましい。
塗装板の場合には、所謂マージン塗装法によつて
上記両側辺部を未塗装部分とすることが好まし
い。金属薄板の厚さについては特に制限はない
が、通常の缶用薄板材料の厚さ、すなわち約0.12
〜0.6mm、好ましくは約0.15〜0.4mmである。 所定の寸法に裁断された金属薄板ブランクは、
公知の方法すなわちロールフオーム法あるいはイ
ンバーテツドフオーム法等によつて断面が円形、
四角形等の缶胴状に成形され、側辺部に重ね合せ
部を有する缶胴成形体とされる。重ね合せ部の巾
は約0.1〜2.0mmが好ましく、さらに好ましくは約
0.2〜0.8mmが好ましい。約0.1mmより小さいと均一
な重ね合せが困難となり、溶接強度の低下や未溶
接部が生ずるおそれがあり、一方約２mmより大き
い場合は、電力や加圧力が増大し、電極の損耗が
激しくなるからである。 以下図面を参照しながら本発明を説明する。第
１図は本発明を実施する装置の溶接電極部附近の
一部切断正面図であり、第２図は第１図の−
線に沿う一部切断側面図である。 １は缶胴成形体であり、第２図の左方の缶胴成
形機（図示されない）によつて重ね合せ部２が下
方になるようにして成形される。マンドレル３の
左端には缶胴成形機が附設されており、右端にお
いて溶接が行なわれるように構成されており、缶
胴成形体１はマンドレル３上を左方より右方に移
送される。マンドレル３の頂部の長溝には缶胴成
形体送り棒４が挿通しており、送り棒４には一定
間隔をおいて爪５が附設されている。送り棒４が
右方へ移動すると缶胴成形体１はその後端上部が
爪５と係合することによつて搬送される。爪５は
上方より加圧されると下行し、加圧が解かれると
バネによつて元の位置に復するように構成されて
いる。マンドレル３の先端部の底部凹溝に縦長電
極６が内設されている。縦長電極６は少なくとも
電極面７が重ね合せ部２（缶胴成形体の缶高）よ
りも長い細長の銅または銅合金よりなつている。
電極面７は重ね合せ部の形状に対応する平面であ
るか、あるいは巾方向に凸曲面を有している。な
お缶胴成形体１が樽状である場合のように、重ね
合せ部２が直線状でないときは、電極面７は長さ
方向に重ね合せ部２の形状に対応した曲面を有す
る。電極面７の巾は重ね合せ部２の巾より大き
い。電極面７は、通常はマンドレル３の周面の延
長面上に位置する。縦長電極６内には冷却水、ブ
ライン（例えば−30℃の）または液化フレオン等
を貫流するための冷却孔８が貫通しており、缶胴
溶接部表面の冷却が十分に行なわれるようにし
て、該部の酸化防止と電極の損耗防止を図つてい
る。また縦長電極６はフイーダ（図示されない）
によつて溶接電源（例えば商用周波数または高速
製缶の場合は約100〜500Hzの）に接続される。 マンドレル３の電極部の両側には一対の押えウ
イング９が、また上部には支持具１０が配設され
ており、夫々送り棒４の駆動機構と同期したカム
機構（図示されない）によつて横方向および上下
方向に移動可能であつて、溶接に先立ち缶胴成形
体１をマンドレル３に押圧できるように構成され
ている。 縦長電極６の下方には回動電極１１が配設され
ている。本実施例における回動電極は円板状であ
つて、電極面１２は短筒面よりなり、その巾は重
ね合せ部２の巾よりも大きい。回動電極１１は軸
受台１３によつて軸受を介して支承され、またフ
イーダ１４によつて溶接電源に接続される。軸受
台１３の下部には支持棒１５が固着されており、
支持棒１５の下部は摺動板１６の透孔に遊嵌され
ていて、軸受台１３は摺動板１６に対し上下動可
能となつている。軸受台１３の下面と摺動板１６
の上面間に支持棒１５を包囲して押圧スプリング
１７が設けられていて、溶接時この押圧スプリン
グ１７によつて重ね合せ部２に加圧力が加えられ
る。摺動板１６の両側部は支枠１８の両側内面に
水平に設けられたガイド１９のガイド面２０に沿
つて、マンドレル３の長手方向に摺動し、それに
伴なつて回動電極１１は重ね合せ部２上を回動
（回転を含む）する。摺動は回転円板（図示され
ない）に偏心的にその一端が取付けられた連結杆
２１の他端と摺動板１６を結合するピン２２を介
して、該回転円板の回転によつて行なわれる。支
枠１８の両側板の内面上端部には突出部（係合
部）２３が突設されていて、軸受台底板上面１３
ａが突出部２３の下面と係合するとによつて、回
動電極１１が下方に押下げられ、回転電極１１の
頂面と縦長電極６の電極面間の間隙が重ね合せ部
または溶接部の厚さより大きくなることによつ
て、缶胴成形体１の電極部への送入ならびに溶接
の完了した缶胴体の送出が回動電極１１によつて
妨げられないように構成されている。 以上の装置によつて、溶接は次のようにして行
なわれる。 回動電極１１が支枠１８の左端側にあつて、突
出部２３ａと軸受台底板上面１３ａが係合してい
て、回動電極１１の頂面と縦長電極６の電極面７
間の間隔が重ね合せ部の厚さよりも大きい状態に
おいて、缶胴成形体１が送り棒４によつて縦長電
極部の所定位置まで送入されて停止する。同時に
一対の押えウイング９が左右より、また支持具１
０が上部よりマンドレル３の方向に進行して、缶
胴成形体１をマンドレル３上に押圧、固定する。
この固定状態において、第３図に示されるよう
に、重ね合せ部２の巾全体が電極面７および１２
に接触することが重要である。これは重ね合せ部
２の全体をマツシユして溶接部全体の厚さを均等
に減少せしめて、所謂マツシユシーム溶接を行な
うためである。すなわち重ね合せ部２の巾方向に
電極面と接触しない部分が存在する場合は、その
非接触部はマツシユされず、ほとんど板厚分の段
差が残り、この段差を完全に被覆して、缶内容物
に対する防食を果すには、多量の保護塗料を必要
とするからである。 次いで摺動板１６が右へ移行して、軸受台底板
上面１３ａと突出部２３ａの係合が解かれ、回動
電極の電極面１２は縦長電極の電極面７上を回転
した後、重ね合せ部２を押圧スプリング１７によ
つて加圧しながら右へ回動し、その間電流が回転
電極−重ね合せ部−縦長電極間を通過して溶接
（鍛接）が行なわれる。通常は回動速度（すなわ
ち溶接速度）が約20ｍ／min以下の場合は50ない
し60Hzの交流が使用され、溶接速度が大になるに
つれて高い周波数の交流が使用される。ただし本
発明は印加電流の周波数や波形等によつて制約さ
れるものではない。 広義の溶接なる語は融接と鍛接（固相溶接）を
包含するが、本発明の溶接は、実質的に鍛接であ
る。融接の場合は、重ね合せ部の界面において金
属が溶融するため凝固のさい巣を発生して内容物
漏洩の原因となるおそれがあり、また溶融メタル
の界面から外部への飛散所謂スプラツシユが生じ
て、保護塗料により完全な補修を困難にし、さら
に表面まで溶融した場合は溶接部外観、形状を著
るしく損ね、また電極面の激しい損耗を招き易
い。従つて本発明においては溶接電流は、金属薄
板の種類、板厚、表面状態および重ね合せ部の
巾、溶接速度、加圧力、電流波形等の因子に応じ
て適正な鍛接すなわち固相溶接が行なわれるよう
な値が選ばれる。しかし本発明はスプラツシユ等
の悪影響が発生しない範囲内において、重ね合せ
部界面に局部的に溶融を起ることを妨げるもので
はない。 押圧スプリング１７による加圧力すなわち溶接
圧力は約30〜500Kgが好ましく、より好ましくは
約60〜300Kgが望ましい。圧力が約30Kgより小さ
いと、重ね合せ部における板間の接触抵抗が不均
一あるいは過大になり、そのため溶接が不安定に
なり、スプラツシユが発生しやすいという問題を
生ずるからである。また500Kgより大きくなると
電極の損耗が激しくなるからである。なお縦長電
極側における溶接部の段差を軽微にするために
は、圧力は約60Kg以上であることが望ましい。 回動電極の直径は約50mm以上、より好ましくは
約100mm以上であることが望ましい。約50mmより
小さいと、回動電極の電極面と重ね合せ部の接触
長が小さくなるため、交流を使用する場合は、交
流波形の電流が０になる時点附近、つまり発熱量
の小さい箇所附近のみを回動電極が押圧し、次い
で電流がピークとなる時点附近、つまり発熱量の
大きい箇所附近のみを押圧する傾向が著るしくな
るので、溶接部での発熱が溶接線方向に対して不
均一となり、交流波形に対応して不均一な円周方
向のはみ出し部を生じ易くなり、つまり電流がピ
ークとなる時点附近に対応する溶接部に、はみ出
し部を生じ易くなり、また溶接電流を増加させる
と局部的なスプラツシユを生じ、また溶接電流を
減少させると局部的に溶接されない部分が生じて
くるため、溶接可能な電流の範囲が狭くなり、か
つ溶接速度を上げることが困難となるからであ
る。回動電極の直径が大きくなるに従つて、上記
の欠陥は減少し、より均一な溶接部が得られ、溶
接可能な電流の範囲が広くなり、また溶接速度を
上げることが容易になる。 溶接部の厚さは、溶接圧力、温度、速度等によ
つて定まるが、通常はブランクの厚さの1.0〜1.8
倍、好ましくは1.0〜1.6倍である。溶接部の厚さ
が大きくなれば大きな段差を有することになり、
保護塗料の使用量が増えるので一般に好ましくな
い。 第４図は代表的な溶接部の溶接線に垂直な断面
を含む溶接部の斜視図を示したものであつて、第
４−ａ，イ，ロ図は本発明の場合、第４−ｂ図は
一対の回転ロール電極を使用する従来の溶接法に
よる場合のものを示す。第４−ａ図においては、
図の下方が縦長電極側である。第４−ｂ図に明ら
かなように、溶接部２４の両面に回転電極を使用
する場合は、重ね合せ部の側端部のメタルが巾方
向外側に交流波形に対応して不均一にはみ出し
て、はみ出し部２４ａその下部の間隙２４ｂを形
成する。間隙２４ｂには時に空孔が形成されるこ
ともある。また溶接部２４は内外面共に非溶接部
１ａから***している。 第４−ａ，イ図は本発明の方法による溶接部２
ａ縦長電極側面の段差が軽微の場合、第４−ａ，
ロ図は上記段差が殆んどない場合を示す。本図か
ら明らかのように、本発明の場合は縦長電極側に
メタルのはみ出しや間隙は殆んどない。また回動
電極側には段差がみられるが、段差は溶接線方向
にほぼ直線的であつて、第４−ｂ図にみられるよ
うな不均一なはみ出しや間隙が認められない。第
４−ａ，ロ図において缶内面側が平坦であるの
は、縦長電極面と平面で接触するためと思われる
が、缶外面側は回動電極と接触するにも拘らず、
メタルはみ出しが起らない理由については必ずし
も明らかでない。恐らく、缶内面側が平坦になる
ことに伴う溶接時のメタルフローの挙動が、第４
−ｂ図の場合と異なることによるものと推測され
る。また本発明の場合は、回動電極と接触する溶
接部の缶外面側には金属の酸化が起る場合がある
が、缶内面側には金属の酸化現象が殆んどみられ
ない。とくに、回動電極の曲率を大きくすること
により、回動電極と接触する溶接部の缶外面側の
金属の酸化を著るしく減少させうることがわかつ
ており、たとえば回動電極の曲率半径を150mm以
上にすると、缶内外面にわたりほとんど酸化現象
の起らない溶接部を得ることが可能となる。これ
は溶接部と電極面との接触面積が拡大し、冷却が
十分に行なわれて、表面が酸化温度まで上昇する
ことなしに溶接が可能となるものと推察される。 回動電極１１は重ね合せ部２の全長を通過して
溶接を終了した後、縦長電極６の電極面７上を回
動するが、軸受台底板１３ａが突出部２３ｂと係
合する（２点鎖線の回動電極部の位置）ことによ
り、下方に押し下げられて、電極面７と１２との
間には、溶接部２ａが通過できる間隙が生ずる。
すると直ちに送り棒４が右方に移動して溶接の完
了した缶胴成形体を右方へ搬送して、溶接部内面
補修装置等のある次工程へ送る。同時に第２の缶
胴成形体が縦長電極部に送入され回動電極は左方
への戻り工程において重ね合せ部上を回動しなが
ら溶接を行なう。 以上は縦長電極の全長が重ね合せ部よりも長
く、かつ重ね合せ部全体が縦長電極上にある実施
例について説明した。この場合は、作業条件によ
つては、一種の熱間圧延効果により、溶接部の両
端より外方への金属の突起（約１mmの長さ）を生
ずることがある。この突起が実用上有害な影響を
与える場合があることは前述した。回動電極が重
ね合せ部の両端部に接触している間のみ通電を止
めれば、この突起の発生を防止することができる
が、これには複雑な電気制御を必要とするという
難点がある。第５図および第６図はこの突起の発
生を防止するための縦長電極部の構造を示す。第
５図において、縦長電極６は前後端及び背面が薄
い電気絶縁層（例えばコロイダルシリカ塗布層）
２５を介してマンドレル３と接していて、縦長電
極６とマンドレル３は完全に電気的に絶縁されて
いる。またマンドレルの下面３ａは電極面７と同
一面上にある。また縦長電極６の全長は重ね合せ
部２の夫よりも僅かに短かく（例えば約１〜３
mm）、缶胴成形体１は、重ね合せ部２が縦長電極
６上を突出する前後端部分Ｘ及びX′の長さがほ
ぼ等しくなるように送り棒によつて送入される。
このように構成することにより、突出部分Ｘおよ
びX′の電流の通過が妨げられるので、突出部分
Ｘ、X′の温度上昇を、前記の有害な突起の生成
を防止ないし軽減しうる程度まで下げることがで
きる。 第６図は、縦長電極６の両端部とマンドレル３
との間に厚い電気絶縁層（セラミツク等の）２６
を設け、溶接時にこの上に重ね合せ部２の両端部
が位置しうるようにしたものである。この場合縦
長電極６とマンドレル３は必ずしも電気的に絶縁
されなくてもよい。第５図の場合と同様の効果が
得られる。 第７図、第８図は回動電極の他の実施例を示
す。第１図、第２図と同一符号の部分は同一部分
又は同一機能の部分を示す。 回動電極２７は電極面２７ａとなる一辺が重ね
合せ部２より長い円弧よりなる長方形状の側面形
状を有している。電極面２７ａの近傍には冷却孔
２７ｂが貫通している。回動電極２７の胴部に
は、電極面２７ａと平行に、電極面２７ａと同一
曲率半径の案内面２８ａを有する案内孔２８が穿
設されている。案内孔２８を貫通するカムローラ
２９の両端は軸受台１３によつて軸架されてい
る。回動電極２７の両側部にはカムローラ３０の
着設用のローラホルダー３１が固設されており、
カムローラ３０は案内板３２に穿設された案内孔
３３内を移動して、回動電極２７の回動を規制し
ている。カムローラ２９が案内孔２８の両端部に
達した時は、突出部２３が軸受台底板上面１３ａ
と係合して電極面２７ａを引下げ（２点鎖線の回
動電極部の位置）ることによつて、重ね合せ部２
及び溶接部の送入、送出を可能ならしめている。
摺動板１６が右方にガイド１９に沿つて移行する
と突出部２３と軸受台底板上面１３ａの係合が解
かれ、押圧スプリング１７によつてローラカム２
９を介して、回動電極２７は重ね合せ部２を押圧
しながら重ね合せ部２上を回動して、溶接が行な
われる。 前述のように回動電極の直径を大きくすること
が好ましいのであるが、その場合は設備が大型に
なるという欠点があり、また溶接速度を上げよう
とするとロールの慣性が大きくなり、さらに溶接
線に沿つて均一な加圧力を与えることが設備上困
難になるという問題点が生ずる。しかるに本実施
例の回動電極は小さなスペースと慣性で、大きな
曲率半径の電極面を採用することができるという
利点がある。なお本明細書において、回動電極２
７の直径は電極面２７ａの曲率半径の２倍として
定義される。 本発明の方法によれば、重ね合せ部の内面を重
ね合せ部の形状と対応す電極面を有する縦長電極
に接触せしめ、重ね合せ部の外面を直径50mm以上
の回動電極と接触せしめて、マツシユシーム溶接
を行なうので、溶接部の特に内面側は段差と金属
のはみ出しが軽微か、もしくは実質的になく、平
坦であり、かつ表面に脆い酸化膜の生成も殆んど
起らないという効果を奏する。従つて保護塗料に
よる補修も容易であり、かつ２重巻締時の塗膜の
剥離も起り難く、耐食性に勝れている。さらに缶
胴成形体、および缶胴成形体から形成された金属
缶胴を何れも第１の軸線方向に、すなわち上流か
ら下流方向に送り、一方溶接のさいは縦長電極上
に重ね合せ部を定置した状態で、回動電極を先行
の缶胴成形体の場合と逆向きの回転方向に回動し
てマツシユシーム溶接を行なうので、缶胴成形体
と金属缶胴の送り方向を逆にし、かつ溶接のさい
の回動電極の回動方向を各回毎に同じにした場合
にくらべて、遥かに高い生産速度で、すなわち少
なくとも２倍以上の生産速度で溶接金属缶胴を製
造できるとい効果を奏する。また縦長電極に重ね
合せ部の端部が接触しないようにして、該端部に
おける溶接電流の通過を妨げるならば、溶接部端
部における外方への金属の突起生成を妨げること
ができて、二重巻締後の漏洩を防止できる。また
重ね合せ部の外面を回動電極と接触せしめ、回動
電極を回動しながら抵抗溶接を行なうので、外面
に対しても縦長電極を使用して、重ね合せ部全体
を同時に溶接する方法にくらべて、溶接電源の容
量を小さくすることができ、かつより長い重ね合
せ部を溶接することも容易であるという利点を有
する。 以下実施例により本発明の効果を一層明らかに
する。 実施例 １ 板厚が0.24mmの黒板（軟鋼板）の円筒成形体
（内径65.3mm、胴長125.4mm）を作成し、第１図及
び第２図に開示した装置により、その円筒成形体
の重ね合せ部を溶接して溶接缶胴を作成した。 溶接電源としては50サイクルの交流電源を用い
ており、電極は市販の抵抗溶接用電極材料である
クロム銅を用いた。重ね合せ巾0.4mm、回動電極
の直径を300mm、溶接速度を12ｍ／minにした場
合の加圧力と良好な溶接部が得られる溶接電流量
（正弦波電流の実効値）の範囲との関係を表１に
示す。 The present invention relates to a method and apparatus for manufacturing metal can bodies,
More specifically, the present invention relates to a method of manufacturing a metal can body whose overlapping side surfaces are pine seamed by electric resistance welding. Aerosol cans, beer cans, powdered coffee cans,
The conventionally widely used method for manufacturing welded metal can bodies such as 18-liter cans is to insert the overlapped portion of the can body molded body between a pair of rotating roller electrodes at fixed positions, and then move the overlapping portion between the electrodes. This is a method of seam welding the overlapped parts by applying alternating current to the parts. In this case, in order to avoid wear and tear on the roller electrode, a method of seam welding by inserting a wire electrode between the rotating roller electrode and the overlapped portion is also widely used. The problems common to these methods are that the welded part, which is to become the inner surface of the can, is not in good condition, so even if repaired with protective paint, sufficient corrosion resistance may not be obtained depending on the type of can contents; Protrusions (possibly due to a kind of hot rolling effect) are formed along the weld line at both ends of the weld, and these protrusions break the sealing rubber when the can end plates are double-sealed, preventing the contents from leaking. It's easy to invite. To explain these points in more detail, the conventional technology has the following drawbacks. (1) Unless special operations such as blowing inert gas are performed during welding, the weld will oxidize and form a black oxide film (especially when using low-carbon steel sheets and surface-treated steel sheets). Since this oxide film is brittle and has poor adhesion to the base metal, the inner surface protective paint applied on this oxide film peels off during the bending process during type 2 seaming, causing the base metal to be absorbed by the contents of the can. Prone to corrosion. (2) In order to reduce the step difference that occurs in the circumferential direction of the weld, if the pressure is increased, the metal (at the side edges of the overlapping part) will protrude unevenly in the circumferential direction, and this protrusion It is not possible to completely isolate the gap on the lower surface of the part from the outside with protective paint, or even if it is possible, a large amount of protective paint is required. (3) As mentioned above, protrusions are formed at both ends of the welded part, which tends to cause leakage from the double-sealed part. The present invention aims to solve the problems of the prior art as described above. That is, an object of the present invention is to provide a method for manufacturing a welded metal can body in which almost no oxide film is formed particularly at the welded portion on the inner surface of the can without using an inert gas or the like. Another object of the invention is to
It is an object of the present invention to provide a relatively highly productive method for manufacturing a welded metal can body, in which the welded portion has only a slight step, especially on the inner surface of the can, and substantially no protrusion of metal in the circumferential direction. According to the present invention, a molded can body having an overlapping portion on the side is formed from a blank of a thin metal sheet, and the molded can body is fed in the first axial direction, and the overlapping portion is formed with a diameter of 50 mm. Insert the overlapping part between the rotating electrode and the vertically long electrode so that the inner surface of the overlapping part is in contact with the vertically long electrode, and position the overlapping part on the vertically long electrode. With the entire circumferential width of the molded body in contact with the rotary electrode and the electrode surfaces of the vertically elongated electrode, the rotary electrode is rotated under pressure in the opposite direction to the rotation direction of the previous can body molded body. At the same time, current is applied between the rotating electrode and the vertical electrode to perform mash seam welding of the overlapping portion, thereby forming a welded portion at least on the inner surface of the can body in which there is substantially no protrusion of metal in the middle circumferential direction. A method for manufacturing a metal can body is provided, which comprises forming a metal can body having a metal can body and then feeding the metal can body in a first axial direction. The present invention will be explained in detail below. There is no particular restriction on the type of thin metal sheet used in the present invention, but surface-treated steel sheets such as blackboard (uncoated low carbon steel sheet), tinplate, phosphate-treated steel sheet, nickel-plated steel sheet, aluminum or aluminum alloy sheet, and these A painted plate or the like is preferably used. If the surface has an insulating film, the insulating film is milled from the surfaces of both sides of the blanks cut to predetermined dimensions, which are to be overlapped, by mechanical means such as a cutter, grinder, or bit, or by applying ultrasonic waves. It is preferable to remove it by a method or the like.
In the case of a painted board, it is preferable to make the above-mentioned both sides unpainted portions by a so-called margin painting method. There is no particular limit to the thickness of the thin metal sheet, but the thickness of normal thin sheet material for cans, that is, approximately 0.12
~0.6 mm, preferably about 0.15-0.4 mm. A thin metal sheet blank cut to predetermined dimensions is
The cross section is circular by a known method, such as a rolled form method or an inverted form method.
The molded can body is formed into the shape of a can body, such as a rectangular shape, and has overlapping parts on the sides. The width of the overlapping part is preferably about 0.1 to 2.0 mm, more preferably about 0.1 to 2.0 mm.
0.2 to 0.8 mm is preferred. If it is smaller than about 0.1 mm, uniform overlapping will be difficult and there is a risk of a decrease in welding strength or unwelded parts, while if it is larger than about 2 mm, the electric power and pressurizing force will increase, causing severe wear and tear on the electrode. It is from. The present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway front view of the vicinity of the welding electrode of an apparatus for carrying out the present invention, and FIG.
FIG. 3 is a partially cutaway side view taken along a line. Reference numeral 1 designates a can body molded body, which is molded by a can body molding machine (not shown) on the left side of FIG. 2 so that the overlapping portion 2 is directed downward. A can body forming machine is attached to the left end of the mandrel 3, and welding is performed at the right end, and the can body formed body 1 is transferred over the mandrel 3 from the left to the right. A can body molded body feed rod 4 is inserted into the long groove at the top of the mandrel 3, and claws 5 are attached to the feed rod 4 at regular intervals. When the feed rod 4 moves to the right, the upper rear end of the can body molded body 1 engages with the claw 5, thereby being conveyed. The claw 5 is configured to move downward when pressure is applied from above, and return to its original position by a spring when the pressure is released. A vertically elongated electrode 6 is provided inside a bottom groove at the tip of the mandrel 3. The vertically elongated electrode 6 is made of elongated copper or copper alloy and has at least an electrode surface 7 longer than the overlapping portion 2 (the height of the can body formed body).
The electrode surface 7 is a flat surface corresponding to the shape of the overlapping portion, or has a convex curved surface in the width direction. Note that when the overlapping portion 2 is not linear, as in the case where the can body molded body 1 is barrel-shaped, the electrode surface 7 has a curved surface corresponding to the shape of the overlapping portion 2 in the length direction. The width of the electrode surface 7 is larger than the width of the overlapping portion 2. The electrode surface 7 is normally located on an extension of the circumferential surface of the mandrel 3. A cooling hole 8 for passing cooling water, brine (for example, at -30°C), or liquefied freon, etc. passes through the vertically long electrode 6, so that the surface of the welded part of the can body is sufficiently cooled. , to prevent oxidation of this part and prevent wear and tear of the electrodes. In addition, the vertically long electrode 6 is a feeder (not shown).
connected to the welding power source (e.g. commercial frequency or approximately 100-500 Hz for high-speed can making). A pair of presser wings 9 are disposed on both sides of the electrode portion of the mandrel 3, and a support 10 is disposed on the upper part, and the mandrel 3 is horizontally moved by a cam mechanism (not shown) synchronized with the drive mechanism of the feed rod 4. It is configured to be movable in the vertical and vertical directions, and to be able to press the molded can body 1 against the mandrel 3 prior to welding. A rotating electrode 11 is arranged below the vertically elongated electrode 6 . The rotating electrode in this embodiment has a disk shape, the electrode surface 12 is a short cylindrical surface, and its width is larger than the width of the overlapping portion 2. The rotating electrode 11 is supported by a bearing stand 13 via a bearing, and is connected to a welding power source by a feeder 14. A support rod 15 is fixed to the lower part of the bearing stand 13.
The lower part of the support rod 15 is loosely fitted into the through hole of the sliding plate 16, so that the bearing stand 13 can move up and down with respect to the sliding plate 16. The lower surface of the bearing stand 13 and the sliding plate 16
A pressing spring 17 is provided between the upper surfaces surrounding the support rod 15, and pressurizing force is applied to the overlapping portion 2 by the pressing spring 17 during welding. Both sides of the sliding plate 16 slide in the longitudinal direction of the mandrel 3 along the guide surfaces 20 of the guides 19 provided horizontally on both inner surfaces of the support frame 18, and the rotating electrodes 11 are overlapped accordingly. It rotates (including rotation) on the mating part 2. Sliding is performed by rotation of the rotating disk (not shown) via a pin 22 that connects the sliding plate 16 to the other end of a connecting rod 21 whose one end is eccentrically attached to the rotating disk (not shown). It can be done. A protruding portion (engaging portion) 23 is provided on the upper end of the inner surface of both side plates of the support frame 18, and the upper surface 13 of the bearing base bottom plate is provided with a protruding portion (engaging portion) 23.
When a engages with the lower surface of the protruding portion 23, the rotating electrode 11 is pushed down, and the gap between the top surface of the rotating electrode 11 and the electrode surface of the vertically long electrode 6 becomes the overlapped portion or the welded portion. By being larger than the thickness, the rotary electrode 11 is configured so that the feeding of the molded can body 1 into the electrode section and the delivery of the welded can body are not obstructed by the rotating electrode 11. Welding is performed using the above apparatus as follows. The rotating electrode 11 is located on the left end side of the supporting frame 18, and the protrusion 23a and the upper surface 13a of the bearing base bottom plate are engaged, and the top surface of the rotating electrode 11 and the electrode surface 7 of the vertically long electrode 6 are engaged with each other.
In a state in which the interval between the electrode parts is larger than the thickness of the overlapping part, the molded can body 1 is fed by the feed rod 4 to a predetermined position in the vertically elongated electrode part and then stopped. At the same time, a pair of presser wings 9 are pressed from the left and right sides, and the support tool 1
0 advances toward the mandrel 3 from above to press and fix the can body molded body 1 onto the mandrel 3.
In this fixed state, as shown in FIG.
It is important to have contact with This is to perform so-called mash seam welding by mashing the entire overlapped portion 2 to uniformly reduce the thickness of the entire welded portion. In other words, if there is a part in the width direction of the overlapping part 2 that does not contact the electrode surface, that non-contact part is not mashed, and a step almost equal to the thickness of the board remains, and this step is completely covered and the can contents are removed. This is because a large amount of protective paint is required to protect objects from corrosion. Next, the sliding plate 16 moves to the right, the engagement between the upper surface 13a of the bearing base bottom plate and the protruding portion 23a is released, and the electrode surface 12 of the rotating electrode rotates on the electrode surface 7 of the vertically long electrode, and then overlaps. The part 2 is rotated to the right while being pressurized by the pressing spring 17, and during this time a current passes between the rotating electrode, the overlapping part, and the vertically long electrode to perform welding (forge welding). Usually, when the rotational speed (ie, welding speed) is less than about 20 m/min, an alternating current of 50 to 60 Hz is used, and as the welding speed increases, an alternating current of a higher frequency is used. However, the present invention is not limited by the frequency, waveform, etc. of the applied current. Although the term welding in a broad sense includes fusion welding and forge welding (solid phase welding), the welding of the present invention is essentially forge welding. In the case of fusion welding, the metal melts at the interface of the overlapped parts, which may cause solidification cavities and cause leakage of contents, and the molten metal may scatter from the interface to the outside, causing so-called splash. This makes it difficult to completely repair the weld using protective paint, and if it melts to the surface, the appearance and shape of the weld will be significantly damaged, and the electrode surface will likely suffer severe wear and tear. Therefore, in the present invention, the welding current is adjusted to perform appropriate forge welding, that is, solid phase welding, depending on factors such as the type of thin metal plate, the plate thickness, the surface condition, the width of the overlapping part, the welding speed, the pressing force, and the current waveform. A value is chosen such that However, the present invention does not prevent local melting from occurring at the interface of the overlapped portions within a range where no adverse effects such as splash occur. The pressing force by the pressing spring 17, that is, the welding pressure, is preferably about 30 to 500 kg, more preferably about 60 to 300 kg. This is because if the pressure is less than about 30 kg, the contact resistance between the plates in the overlapped portion will be uneven or excessive, resulting in unstable welding and the problem of splashes being likely to occur. Moreover, if the weight exceeds 500 kg, the wear and tear of the electrode will be severe. Note that in order to minimize the level difference in the welded portion on the side of the vertically long electrode, it is desirable that the pressure be approximately 60 kg or more. It is desirable that the rotating electrode has a diameter of about 50 mm or more, more preferably about 100 mm or more. If it is smaller than about 50 mm, the contact length between the electrode surface of the rotating electrode and the overlapping part will be small, so when using AC, only use it near the point where the current of the AC waveform becomes 0, that is, near the point where the amount of heat generation is small. The rotating electrode presses the current, and then there is a marked tendency to press only near the point where the current peaks, that is, near the area where the heat generation is large, so the heat generation in the weld is uneven in the direction of the weld line. Therefore, uneven protrusion in the circumferential direction is likely to occur in response to the AC waveform, and in other words, protrusion is likely to occur in the welding area near the point where the current peaks, which also increases the welding current. This is because local splashes occur, and when the welding current is reduced, some parts are not welded locally, which narrows the weldable current range and makes it difficult to increase the welding speed. . As the diameter of the rotating electrode increases, the above-mentioned defects are reduced, a more uniform weld is obtained, a wider weldable current range is obtained, and it is easier to increase the welding speed. The thickness of the welded part is determined by welding pressure, temperature, speed, etc., but is usually 1.0 to 1.8 of the blank thickness.
times, preferably 1.0 to 1.6 times. As the thickness of the weld increases, there will be a large step.
This is generally undesirable because it increases the amount of protective paint used. Figure 4 shows a perspective view of a typical welded part including a cross section perpendicular to the weld line, and Figures 4-a, A, and B are in the case of the present invention; The figure shows a conventional welding process using a pair of rotating roll electrodes. In Figure 4-a,
The lower part of the figure is the vertically elongated electrode side. As is clear from Figure 4-b, when rotating electrodes are used on both sides of the welding part 24, the metal at the side edges of the overlapping part protrudes unevenly outward in the width direction in response to the AC waveform. , forming a gap 24b below the protruding portion 24a. Holes may sometimes be formed in the gap 24b. Further, both the inner and outer surfaces of the welded portion 24 are raised from the non-welded portion 1a. Figures 4-a and 4-a show welded parts 2 by the method of the present invention.
a If the level difference on the side surface of the vertically long electrode is slight, 4-a,
Figure B shows a case where there is almost no step difference. As is clear from this figure, in the case of the present invention, there is almost no metal protrusion or gap on the vertically long electrode side. Further, although a step is seen on the rotating electrode side, the step is almost linear in the direction of the welding line, and there are no uneven protrusions or gaps as seen in FIG. 4-b. The reason why the inner surface of the can is flat in Figures 4-a and 4-b is thought to be because it makes flat contact with the vertically elongated electrode surface, but even though the outer surface of the can is in contact with the rotating electrode,
The reason why metal extrusion does not occur is not necessarily clear. The behavior of metal flow during welding due to the flattening of the inner surface of the can is probably the fourth cause.
It is presumed that this is due to a difference from the case in Figure -b. Further, in the case of the present invention, metal oxidation may occur on the outer surface of the can at the welded portion that contacts the rotating electrode, but almost no metal oxidation phenomenon is observed on the inner surface of the can. In particular, it is known that increasing the curvature of the rotating electrode can significantly reduce the oxidation of the metal on the outer surface of the can at the welded part that contacts the rotating electrode. When the diameter is 150 mm or more, it is possible to obtain a welded part where almost no oxidation phenomenon occurs on the inside and outside of the can. It is presumed that this is because the contact area between the welding part and the electrode surface is expanded, and sufficient cooling is performed, making it possible to weld without the surface rising to the oxidation temperature. After the rotating electrode 11 passes through the entire length of the overlapped portion 2 and completes welding, it rotates on the electrode surface 7 of the vertically long electrode 6, but the bearing base bottom plate 13a engages with the protruding portion 23b (at two points). As a result of the position of the rotating electrode portion (indicated by the chain line), it is pushed downward, and a gap is created between the electrode surfaces 7 and 12 through which the welded portion 2a can pass.
Immediately, the feed rod 4 moves to the right and conveys the welded can body molded body to the right and sends it to the next process, such as a welded part inner surface repair device. At the same time, the second can body molded body is fed into the vertically elongated electrode section, and the rotating electrode performs welding while rotating on the overlapping section in the return process to the left. The embodiments above have been described in which the entire length of the vertically long electrode is longer than the overlapping portion, and the entire overlapping portion is on the vertically long electrode. In this case, depending on the working conditions, metal protrusions (approximately 1 mm long) may be produced outward from both ends of the weld due to a kind of hot rolling effect. As mentioned above, this protrusion may have a harmful effect in practice. This protrusion can be prevented by stopping the current supply only while the rotating electrode is in contact with both ends of the overlapped portion, but this has the disadvantage of requiring complicated electrical control. FIGS. 5 and 6 show the structure of a vertically elongated electrode portion for preventing the formation of protrusions. In FIG. 5, the longitudinally elongated electrode 6 has a thin electrically insulating layer (for example, a colloidal silica coating layer) on its front and rear ends and back surface.
It is in contact with the mandrel 3 via the electrode 25, and the vertically long electrode 6 and the mandrel 3 are completely electrically insulated. Further, the lower surface 3a of the mandrel is on the same plane as the electrode surface 7. Further, the total length of the vertically long electrode 6 is slightly shorter than that of the overlapping portion 2 (for example, about 1 to 3
mm), the can body molded body 1 is fed by a feed rod so that the lengths of the front and rear end portions X and X' of the overlapping portion 2 protruding above the vertically elongated electrode 6 are approximately equal.
With this configuration, the passage of current through the protrusions X and X' is prevented, so the temperature rise in the protrusions X and X' is reduced to a level that can prevent or reduce the formation of the harmful protrusions. be able to. FIG. 6 shows both ends of the vertically long electrode 6 and the mandrel 3.
A thick electrically insulating layer (such as ceramic) 26 between
is provided so that both ends of the overlapping portion 2 can be positioned on this during welding. In this case, the vertically long electrode 6 and the mandrel 3 do not necessarily have to be electrically insulated. The same effect as in the case of FIG. 5 can be obtained. 7 and 8 show other embodiments of the rotating electrode. Parts with the same reference numerals as in FIGS. 1 and 2 indicate the same parts or parts with the same function. The rotating electrode 27 has a rectangular side surface shape in which one side, which becomes the electrode surface 27a, is an arc longer than the overlapping portion 2. Cooling holes 27b penetrate near the electrode surface 27a. A guide hole 28 having a guide surface 28a having the same radius of curvature as the electrode surface 27a is bored in the body of the rotating electrode 27, parallel to the electrode surface 27a. Both ends of the cam roller 29 passing through the guide hole 28 are supported by a bearing stand 13 . A roller holder 31 for mounting a cam roller 30 is fixed on both sides of the rotating electrode 27.
The cam roller 30 moves within a guide hole 33 formed in a guide plate 32 to restrict rotation of the rotating electrode 27. When the cam roller 29 reaches both ends of the guide hole 28, the protrusion 23 touches the upper surface 13a of the bearing base bottom plate.
By engaging with the electrode surface 27a and lowering the electrode surface 27a (the position of the rotating electrode portion indicated by the two-dot chain line), the overlapping portion 2
It also makes it possible to send in and out the welding part.
When the sliding plate 16 moves to the right along the guide 19, the engagement between the protrusion 23 and the upper surface 13a of the bearing base bottom plate is released, and the roller cam 2 is moved by the pressing spring 17.
9, the rotating electrode 27 rotates on the overlapping portion 2 while pressing the overlapping portion 2, and welding is performed. As mentioned above, it is preferable to increase the diameter of the rotating electrode, but this has the disadvantage of increasing the size of the equipment, and increasing the welding speed increases the inertia of the rolls, which also increases the welding line. A problem arises in that it is difficult to apply a uniform pressing force along the line. However, the rotating electrode of this embodiment has the advantage of being able to use an electrode surface with a large radius of curvature while requiring a small space and inertia. Note that in this specification, the rotating electrode 2
The diameter of 7 is defined as twice the radius of curvature of the electrode surface 27a. According to the method of the present invention, the inner surface of the overlapping portion is brought into contact with a vertically elongated electrode having an electrode surface corresponding to the shape of the overlapping portion, and the outer surface of the overlapping portion is brought into contact with a rotating electrode having a diameter of 50 mm or more, Since pine seam welding is performed, the welded part, especially on the inner surface, has slight or virtually no steps and metal protrusion, and is flat, with almost no formation of a brittle oxide film on the surface. play. Therefore, it is easy to repair with a protective paint, and peeling of the paint film during double seaming is less likely to occur, resulting in excellent corrosion resistance. Furthermore, the can body molded body and the metal can body formed from the can body molded body are both fed in the first axial direction, that is, from upstream to downstream direction, while during welding, the overlapping part is fixed on the vertically long electrode. In this state, the rotating electrode is rotated in the opposite rotation direction to that of the previous molded can body to perform pine seam welding, so the feeding direction of the molded can body and the metal can body is reversed, and the welding The effect is that welded metal can bodies can be manufactured at a much higher production rate, that is, at least twice the production rate, compared to the case where the rotating direction of the small rotating electrode is the same every time. Furthermore, if the end of the overlapping part is prevented from contacting the vertically elongated electrode and the welding current is prevented from passing through the end, it is possible to prevent the metal from forming an outward protrusion at the end of the welding part. Leakage after double seaming can be prevented. In addition, since resistance welding is performed by bringing the outer surface of the overlapping part into contact with a rotating electrode and rotating the rotating electrode, it is possible to weld the entire overlapped part at the same time by using a vertically long electrode on the outer surface as well. Compared to this, it has the advantage that the capacity of the welding power source can be made smaller, and it is easier to weld longer overlapping parts. The effects of the present invention will be further clarified by Examples below. Example 1 A cylindrical molded body (inner diameter 65.3 mm, body length 125.4 mm) of a blackboard (mild steel plate) with a plate thickness of 0.24 mm was created, and the cylindrical molded body was The overlapping parts were welded to create a welded can body. A 50-cycle AC power source was used as the welding power source, and chromium copper, a commercially available electrode material for resistance welding, was used as the electrode. Relationship between the pressure force and the range of welding current amount (effective value of sine wave current) that can obtain a good weld when the overlap width is 0.4 mm, the diameter of the rotating electrode is 300 mm, and the welding speed is 12 m/min. are shown in Table 1.

【表】【table】

【表】 大きいスプラツシユが発生した。
加圧力を130Kg、溶接電流を5000Aとして得ら
れた溶接缶胴の溶接部の溶接線に垂直な断面の顕
微鏡組織を第９図に示した（倍率60、５％ピクリ
ン酸アルコールで腐食）。写真から明らかのよう
に、溶接部の下面（縦長電極側）は平坦に押しつ
ぶされている。また上面（回動電極側）にもメタ
ルの巾方向へのハミ出しや、その下面の間隙の発
生も見られない。また溶接部上面は若干酸化した
が、溶接部下面には酸化による変色は全くみられ
なかつた。 実施例 ２ 板厚が0.24mmのブリキ板（鍍錫量#25）の円筒
成形体（内径74.0mm、胴長134.3mm）を作成し、
実施例１と同じ装置により、その円筒成形体の重
ね合せ部を溶接して十分な溶接強度を有する溶接
缶胴を得た。この場合の重ね合せ部巾は0.4mm、
交流周波数50Hz、溶接電流5210A、回動電極の直
径300mm、加圧力115Kg、溶接速度12ｍ／minであ
つた。 第１０図に溶接部断面の顕微鏡組織（倍率60、
５％ピクリン酸アルコール）を示す。 写真の下面が縦長電極側であつて、軽微な段差
がみられるが、メタルの巾方向はみ出しやその下
面に間隙の生成はみられない。これは上面につい
ても同様である。溶接部の内外面ともに表面酸化
に伴う変色は殆んどなく、溶接線方向に殆んど一
様に押しつぶされており、好ましい溶接部を呈し
ていた。 実施例 ３ 板厚が0.23mmのテインフリースチール（電解ク
ロム酸処理鋼板）の矩形状のブランクを作成し、
重ね合され溶接されるブランクの両端縁部から約
３mm巾に渡り、両面の電解クロム酸処理被覆層を
研削剥離して、鉄面を完全に露出せしめた。この
ブランクから内径74.0mm、胴長84.9mmの円筒成形
体を作成し、第７図、第８図に示す装置によりそ
の円筒成形体の重ね合せ部を溶接して溶接缶胴を
作成した。 溶接電源として50サイクルの交流電源を使用
し、電極は市販の抵抗溶接用電極材のクロム銅を
用いた。そのさい、円筒成形体の重ね合せ巾を
0.3mm、回動電極の曲率半径を250mm、電極加圧力
を200Kg、溶接電流6300A、溶接速度を12ｍ／min
にして溶接を行なつた。 得られた溶接缶胴の溶接部は内外面とも酸化に
よる変色は殆んどなく、その断面は第９図とほと
んど同様であつた。 実施例 ４ 板厚が0.22mmのテインフリースチール（電解ク
ロム酸処理鋼板）を実施例３と同様の手段にて、
溶接部近傍の電解クロム酸処理被覆層を除去し
て、鉄面を完全に露出せしめたものから円筒成形
体（内径65.3mm、胴長104.7mm）を作成し、第１
図および第２図に示す装置により、その円筒成形
体の重ね合せ部を溶接して溶接缶胴を作成した。 溶接電源として、350Hzの交流電源を使用し、
そのさい円筒成形体の重ね合せ幅0.3mm、溶接速
度を60ｍ／minとし、回動電極の直径を120mm、
60mmに変え、さらに電極加圧力および電流量を表
２に示す値とした。 得られた溶接缶胴体の内面側溶接部の金属のは
み出しの状態を調べた結果を表２に示す。[Table] A large splash occurred.
Figure 9 shows the microscopic structure of a cross section perpendicular to the weld line of the welded part of the welded can body obtained with a pressure of 130 kg and a welding current of 5000 A (magnification 60, corrosion with 5% picric acid alcohol). As is clear from the photo, the bottom surface of the weld (vertical electrode side) is flattened. Furthermore, there is no protrusion of the metal in the width direction on the upper surface (rotating electrode side), nor any gaps on the lower surface. Furthermore, although the upper surface of the weld was slightly oxidized, no discoloration due to oxidation was observed on the lower surface of the weld. Example 2 A cylindrical molded body (inner diameter 74.0 mm, body length 134.3 mm) of a tin plate (plating amount #25) with a plate thickness of 0.24 mm was created,
Using the same equipment as in Example 1, the overlapped portions of the cylindrical molded bodies were welded to obtain a welded can body having sufficient welding strength. In this case, the overlap width is 0.4mm.
The AC frequency was 50 Hz, the welding current was 5210 A, the diameter of the rotating electrode was 300 mm, the applied force was 115 kg, and the welding speed was 12 m/min. Figure 10 shows the microscopic structure of the cross section of the weld (magnification 60,
5% picric acid alcohol). The bottom surface of the photo is the vertical electrode side, and there is a slight step, but no protrusion of the metal in the width direction or the formation of gaps on the bottom surface. This also applies to the top surface. There was almost no discoloration due to surface oxidation on both the inner and outer surfaces of the welded part, and the welded part was crushed almost uniformly in the direction of the weld line, indicating a desirable welded part. Example 3 A rectangular blank of stain-free steel (electrolytic chromic acid treated steel plate) with a thickness of 0.23 mm was created,
The electrolytic chromic acid treated coating layer on both sides was removed by grinding over a width of about 3 mm from both ends of the blanks to be stacked and welded, to completely expose the iron surface. A cylindrical molded body having an inner diameter of 74.0 mm and a body length of 84.9 mm was made from this blank, and the overlapped portions of the cylindrical molded bodies were welded using the apparatus shown in FIGS. 7 and 8 to create a welded can body. A 50-cycle AC power source was used as the welding power source, and the electrodes were made of chromium copper, a commercially available electrode material for resistance welding. At that time, the overlapping width of the cylindrical molded bodies
0.3mm, radius of curvature of rotating electrode 250mm, electrode pressure 200Kg, welding current 6300A, welding speed 12m/min
Welding was carried out using The welded portion of the obtained welded can body had almost no discoloration due to oxidation on both the inner and outer surfaces, and its cross section was almost the same as that shown in FIG. 9. Example 4 A stain-free steel plate (electrolytic chromic acid treated steel plate) with a plate thickness of 0.22 mm was prepared in the same manner as in Example 3.
A cylindrical molded body (inner diameter 65.3 mm, body length 104.7 mm) was created by removing the electrolytic chromic acid treatment coating layer near the welded part and completely exposing the iron surface.
Using the apparatus shown in FIG. 2 and FIG. 2, the overlapped portions of the cylindrical molded bodies were welded to create a welded can body. A 350Hz AC power source is used as the welding power source.
At that time, the overlapping width of the cylindrical molded bodies was 0.3 mm, the welding speed was 60 m/min, the diameter of the rotating electrode was 120 mm,
60 mm, and the electrode pressing force and current amount were set to the values shown in Table 2. Table 2 shows the results of examining the state of metal protrusion from the inner welded portion of the obtained welded can body.

【表】 比較例 １ 回動電極の直径を40mmとし、電極加圧力および
電流量を表２に示す値として、その他の条件は実
施例４と同じ条件にて溶接缶胴を作成した。 得られた溶接缶胴体の内面側溶接部には表２に
示すように、加圧力は実施例４の場合よりも小さ
いにもかかわらず、周波数の半サイクルごとに比
較的顕著な金属のはみ出しが見られた。 比較例 ２ 板厚が0.24mmのブリキ板（鍍錫量#25）の円筒
成形体（内径74.0mm、胴長134.3mm）を作成し、
その円筒成形体の重ね合せ幅を0.4mmとして、２
つの回転する円盤状電極間にその成形体の重ね合
せ部を送り込み、12ｍ／minの速度にて通過さ
せ、その通過時において２つの電極間に通電する
ことにより、その重ね合せ部を溶接して溶接缶胴
を得た。そのさい、溶接電源としては50サイクル
の交流電源を用いた。円筒成形体内部に置かれた
円盤状電極の直径は60mmであり、もう一つの成形
体外部に置かれた円盤状電極の直径は80mmであつ
た。また、電極間の加圧力は40Kgであつた。 第１１図に溶接部の顕微鏡組織を示す（倍率
60、５％ピクリン酸アルコール）。写真に示され
るような溶接部内外面に著るしいメタルの巾方向
はみ出しとその下の間隙が存在する部分と、比較
的メタルのはみ出しの少ない部分が溶接線方向に
沿つて、溶接電流波形に対応して不均一に発生し
ていた。また溶接部の両面は共に黒褐色に酸化し
ていた。[Table] Comparative Example 1 A welded can body was prepared under the same conditions as in Example 4 except that the diameter of the rotating electrode was 40 mm, the electrode pressing force and the amount of current were as shown in Table 2, and the other conditions were the same as in Example 4. As shown in Table 2, in the inner welded part of the obtained welded can body, there was relatively significant protrusion of metal at every half cycle of the frequency, although the pressurizing force was smaller than that in Example 4. It was seen. Comparative Example 2 A cylindrical molded body (inner diameter 74.0 mm, body length 134.3 mm) of a tin plate (coating amount #25) with a thickness of 0.24 mm was created,
Assuming that the overlapping width of the cylindrical molded bodies is 0.4 mm, 2
The overlapped part of the molded body is fed between two rotating disk-shaped electrodes, passed at a speed of 12 m/min, and the overlapped part is welded by passing current between the two electrodes. A welded can body was obtained. At that time, a 50-cycle AC power source was used as the welding power source. The diameter of the disc-shaped electrode placed inside the cylindrical molded body was 60 mm, and the diameter of the disc-shaped electrode placed outside the other molded body was 80 mm. Further, the pressing force between the electrodes was 40 kg. Figure 11 shows the microscopic structure of the weld (magnification
60, 5% picric alcohol). The welding current waveform corresponds to the welding current waveform along the weld line direction, as shown in the photo, where there is significant metal protrusion in the width direction and a gap below it on the inner and outer surfaces of the weld, and the area where there is relatively little metal protrusion. It was occurring unevenly. Additionally, both sides of the welded area were oxidized to a blackish brown color.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の実施例である装置の正面図
を、第２図は第１図の−線に沿う側面図を、
第３図は重ね合せ部近傍の拡大断面図を、第４−
ａ図は本発明の方法による代表的溶接部の断面を
含む斜視図を、第４−ｂ図は従来の方法による溶
接部の断面を含む斜視図を、第５図および第６図
は溶接部端部の突起生成を防止するための縦長電
極構造を示す側面断面図を、第７図は本発明の方
法を実施するための装置の一部破断正面図を、第
８図は第７図の−線に沿う側面図を、第９図
および第１０図は本発明の方法により得られた溶
接部の溶接線方向に垂直な断面の顕微鏡組織を、
第１１図は従来の方法により得られた溶接部断面
の顕微鏡組織を示す。 １……缶胴成形体、２……重ね合せ部、３……
マンドレル、６……縦長電極、７……縦長電極の
電極面、１１……回動電極、１２……回動電極の
電極面、１３……軸受台、２３ａ，２３ｂ……係
合部（突出部）、２６……電気絶縁部、２７ａ…
…円弧状電極面。 FIG. 1 is a front view of a device that is an embodiment of the present invention, and FIG. 2 is a side view taken along the - line in FIG. 1.
Figure 3 is an enlarged cross-sectional view of the vicinity of the overlapping part, and Figure 4-
Figure a is a perspective view including a cross section of a typical welded part made by the method of the present invention, Figure 4-b is a perspective view including a cross section of a welded part made by the conventional method, and Figures 5 and 6 are a perspective view including a cross section of a welded part made by the conventional method. FIG. 7 is a side sectional view showing a vertically elongated electrode structure for preventing the formation of protrusions at the ends, FIG. 7 is a partially cutaway front view of an apparatus for carrying out the method of the present invention, and FIG. 9 and 10 are microstructures of a cross section perpendicular to the weld line direction of the weld obtained by the method of the present invention,
FIG. 11 shows a microscopic structure of a cross section of a welded part obtained by a conventional method. 1... Can body molded body, 2... Overlapping portion, 3...
Mandrel, 6... Vertically long electrode, 7... Electrode surface of the vertically long electrode, 11... Rotating electrode, 12... Electrode surface of the rotating electrode, 13... Bearing stand, 23a, 23b... Engaging portion (protrusion) part), 26... electrical insulation part, 27a...
...Arc-shaped electrode surface.

Claims (1)

【特許請求の範囲】 １ 金属薄板のブランクから、側辺に重ね合せ部
を有する缶胴成形体を成形し、該缶胴成形体を第
１の軸線方向に送つて、該重ね合せ部を直径50mm
以上の回動電極と、縦長電極の間に、該重ね合せ
部の内面が該縦長電極と接触するように挿入し
て、該縦長電極上に該重ね合せ部を定置し、該重
ね合せ部の該成形体円周方向全巾を該回動電極と
縦長電極の電極面に接触させた状態で、加圧下に
該回動電極を先行の缶胴成形体の場合の回動方向
と逆向きに回動せしめ、同時に該回動電極と縦長
電極間に通電して該重ね合せ部をマツシユシーム
溶接して、すくなくとも該缶胴体内面側にて円周
方向の金属のはみ出しが実質的にない溶接部を有
する金属缶胴を形成した後、該金属缶胴を第１の
軸線方向に送出することを特徴とする金属缶胴の
製造方法。 ２ 缶胴成形体を縦長電極上に送入するさい、お
よび溶接部を有する金属缶胴を縦長電極から送出
するさいに、該縦長電極と回動電極の間に間〓を
設けて、該缶胴成形体の送入と該金属缶胴の送出
を容易にしたことを特徴とする特許請求の範囲第
１項記載の金属缶胴の製造方法。[Scope of Claims] 1. A molded can body having overlapping portions on the sides is formed from a blank of a thin metal sheet, and the molded can body is fed in the first axial direction to form the overlapping portion in diameter. 50mm
Insert the overlapping part between the rotating electrode and the vertically long electrode so that the inner surface of the overlapping part is in contact with the vertically long electrode, and position the overlapping part on the vertically long electrode. With the entire circumferential width of the molded body in contact with the rotary electrode and the electrode surfaces of the vertically elongated electrode, the rotary electrode is rotated under pressure in the opposite direction to the rotation direction of the previous can body molded body. At the same time, current is applied between the rotating electrode and the vertically elongated electrode to perform mash seam welding of the overlapping portion, thereby creating a welded portion with substantially no protrusion of metal in the circumferential direction at least on the inner surface of the can body. 1. A method for manufacturing a metal can body, comprising: forming a metal can body having a metal can body, and then feeding the metal can body in a first axial direction. 2. When feeding a can body formed body onto a vertically long electrode, and when feeding a metal can body having a welded part from a vertically long electrode, a gap is provided between the vertically long electrode and the rotating electrode, and the can body 2. The method for manufacturing a metal can body according to claim 1, wherein feeding of the formed body and feeding of the metal can body are facilitated.