JPH0243588B2

JPH0243588B2 -

Info

Publication number: JPH0243588B2
Application number: JP59126505A
Authority: JP
Priority date: 1984-06-21
Filing date: 1984-06-21
Publication date: 1990-09-28
Also published as: JPS617079A

Description

[Detailed description of the invention]

（産業上の利用分野）本発明は溶接缶胴の製造方法に関し、さらに詳
しくは表面処理被膜層を有する缶胴成形体の側面
重ね合わせ部を電気抵抗マツシユシーム溶接し
て、溶接缶胴を製造する方法に関する。（従来の技術）溶接缶胴、例えばビール、炭酸飲料、ジユース
類等を収納するための溶接缶胴は通常、金属ブラ
ンクを円筒状に丸めて重ね合わせ部を形成した缶
胴成形体の重ね合わせ部を、対向する１対の電極
ロールを用いて、表面が平滑な線電極を介して電
気抵抗マツシユシーム固相溶接することによつて
製造される。その場合金属ブランクが、表面処理被膜を有し
ない低炭素鋼板（所謂黒板）、もしくは通常の錫
めつき鋼板（ぶりき）等のように、比較的電気抵
抗の小さい表面処理被膜を有する金属板よりなる
場合は、上記方法によつてスプラツシユ（溶融金
属の飛沫）等による欠陥を生ずることなく、比較
的容易に満足な溶接缶胴体を製造することがで
き、錫めつき鋼板よりなる溶接缶胴体の製造は商
業的に成功している。しかしながらテインフリースチール（電解クロ
ム酸処理鋼板）のように、比較的、電気絶縁性の
高い表面処理被膜（この場合は主として水和クロ
ム酸化物層、厚さは通常金属クロム換算で５〜30
mg／m²）を有する金属板よりなる金属ブランクよ
り形成された缶胴成形体の場合は、溶接時にスプ
ラツシユを著しく発生し易く、そのため重ね合わ
せ部における表面処理被膜層（この場合は水和ク
ロム酸化物層と金属クロム層）を予め、ミリング
カツター等で除去しなければ満足な溶接部が得ら
れなかつた。この表面処理被膜層の除去は、溶接
部の耐食性を損なうのみならず、カツターの損耗
による工具費や工程の増加のためのコストアツ
プ、および残留した切粉が内容物（例えばビー
ル）に入ることによるフレーバの劣化等の問題を
生ずる。本発明者等はこの対策について、種々研究した
結果、錫めつき鋼板よりなる缶胴成形体の場合よ
りも遥かに高い溶接力（同一重ね合わせ部幅当り
の）を加えることにより、表面処理被膜層を有す
る重ね合わせ部を備えたテインフリースチール缶
胴成形体を、著しいスプラツシユの発生をみるこ
となくマツシユシーム溶接できることを見出し
た。しかしながらこの場合、溶接時に重ね合わせ部
（通常は幅0.2〜1.5mm）の前端近傍および後端
（最後に溶接される部分）近傍、特に後者が円周
方向外方にずれて、これらの部分の溶接部幅が減
少したり、極端の場合は衝合わせ的な溶接部とな
つて、溶接強度が低下して、フランジ加工を行つ
た場合クラツクを生ずるという問題を発生する。
このずれの現象は、強い溶接力にもとづく大きな
マツシユ量による材料の逃げが円周方向外方に向
うためと推測される。前記の端部近傍以外の部分には、上記のずれが
比較的起り難いが、これは上記のタイプの溶接を
行う溶接機として、特公昭54−26213号公報に開
示されているような、重ね合わせ部を電極ロール
入口近傍まで案内する断面Ｚ形の所謂Ｚバー、電
極ロール近傍において缶胴成形体を包囲するガイ
ドロール群、および互に僅かに斜交するよう配設
された１対の電極ロール等のずれ防止対策のとら
れたものが一般に採用されているからである。こ
の種の溶接機を用いても、前述の場合特に重ね合
わせ部の後端近傍にずれが生ずるのは、後端近傍
が電極ロールを通過するさい（線電極を介して）、
Ｚバーおよびガイドロール群による拘束力が失わ
れるためと推測される。（発明が解決しようとする課題）本発明は以上の従来技術の問題点に鑑みなされ
たものであつて、本発明は表面処理被膜層を有す
る金属ブランクより形成された缶胴成形体の重ね
合わせ部を、一対の電極ロールを用いて線電極を
介して電気抵抗マツシユシーム固相溶接して、溶
接缶胴を製造する方法であつて、たとえ表面処理
被膜層の電気絶縁性が比較的高い場合であつて
も、重ね合わせ部に表面処理被膜層を残したまま
で、全長にわたり満足な溶接部が得られる溶接缶
胴の製造方法を提供することを目的とする。（課題を解決するための手段）上記目的を達成するため本発明は、表面処理被
膜層を有する金属ブランクの対向する第１の端部
と第２の端部を、該表面処理被膜層を残したまま
重ね合わせて形成された缶胴成形体の重ね合わせ
部を、対向する１対の電極ロールを用いて線電極
を介して、電気抵抗マツシユシーム溶接する溶接
缶胴の製造方法において、該線電極の該重ね合わ
せ部に接る面が、平均粗さ２〜4μmに粗面化され
ていることを特徴とする溶接缶胴の製造方法を提
供するものである。（作用）本願発明においては、線電極の重ね合わせ部に
接する面が平均粗さ2μm以上に粗面化されてい
る。そのため線電極の上記面は溶接のさい、加熱
軟化した重ね合わせ部の表面に食い込むので、比
較的高い溶接力で溶接を行つても、重ね合わせ部
の前端近傍および後端近傍を含む全長にわたつ
て、円周方方向外方にずれることが起こり難い。また重ね合わせ部の上記面の平均粗さが4μmを
越えると、表面処理被膜層の電気絶縁性が比較的
高い場合には、比較的高い溶接力で溶接を行なつ
ても、通電が不安定になつてスプラツシユが発生
するなど溶接状態が悪化する。しかし本願発明の
場合、上記平均粗さが4μm以下であるので、のよ
うな欠陥が起こり難い。従つて本願発明は、金属ブランクの表面処理被
膜層の電気絶縁性が比較的高い場合でも、全長に
わたり満足な溶接部をを有する溶接缶胴を製造す
ることができる。（実施例）溶接直前の状態を示す第１図において、１は缶
胴成形体であつて、テインフリースチールの方形
ブランク（図示されない）を丸めて、その対向す
る第１の端部１ａと第２の端部１ｂを、表面処理
被膜層２（地鉄３側が金属クロム層（図示されな
い）、表面側が水和クロム酸化物層（図示されな
い）よりなる）を残したまま重ね合わせて、重ね
合わせ部４を形成することにより作られたもので
ある。重ね合わせ部４の幅は通常約0.2〜1.5mmで
ある。５は内部電極ロール、６は外部電極ロールであ
り、夫々の周溝５ａおよび６ａに、夫々線電極７
および７′が挿通している。線電極７，７′は、短
辺が円弧状の断面長方方形状になつている。この
ような形状の線電極７，７′は、通常銅丸線を、
内部電極ロール５の上流側において、圧延ロール
によつて平圧延することによつて得られる。かつ、線電極７と７′は通常１本の銅線よりな
つている。すなわち、内側線電極７は、図示され
ない経路を通つて折返されて外側線電極７′とな
る。そのため内側線電極７の平坦な内面７ａおよ
び外面７ｂが夫々、外側線電極７′の外面７′ｂお
よび内面７′ａとなる。またマツシユシーム溶接
を行うため、内面７ａ，７′ａの幅は、重ね合わ
せ部４の幅より大きく定められており、かつ溶接
時に重ね合わせ部４の幅全体が内面７ａ，７′ａ
と接触するように、缶胴成形体１は送られる。内側線電極７の重ね合わせ部４と接する平坦な
面７ａ，および外側線電極７′の重ね合わせ部４
と接する平坦な面７′ａ、従つて線電極７，７′の
平坦な両面７ａ，７′ａ，７ｂ，７′ｂは粗面化さ
れている。このような粗面化された線電極は、サ
ンドブラスト又はグリツトブラスト等によつて表
面が粗面化された圧延ロールによつて平圧延する
か、もしくは通常の平滑な表面を有する圧延ロー
ルで平圧延された線電極の平坦な面を、サンドブ
ラストもしくはグリツトブラストすること等によ
つて得られる。従来の線電極の、平坦な面（７ａ，７′ａ，７
ｂ，７′ｂに対応する）の平均粗さR_aは、約0.1〜
0.4μmであるが、本発明に適用される線電極の重
ね合わせ部４と接する平坦な面７ａ，７′ａの平
均粗さR_aは２〜4μmであることが好ましい。（作用）第２図は、以上の内部電極ロール５および外部
電極ロール６により、線電極７，７′を介して、
重ね合わせ部４に比較的高い押圧力（例えば錫め
つき鋼板よりなる缶胴成形体の場合の約1.5倍の）
すなわち溶接力を加え、かつ交流電流を通電し
て、マツシユシーム固相溶接を行つて、溶接部８
を有する溶接缶胴１０を形成した直後の状態を示
す。線電極の内面７ａ，７′ａは、溶接中に加熱軟
化した重ね合わせ部の表面に喰込むので、缶胴成
形体１の前端近傍および後端近傍の重ね合わせ部
４であつても、円周向外方にずれることが防止さ
れる。従つてこれらの部分の溶接部８の幅が減少した
り、あるいは衝合わせ的な溶接部が生ずるおそれ
がない。このように溶接時に重ね合わせ部４が円周方向
外方にずれるのを防止するためには、線電極の重
ね合わせ部４と接する面７ａ，７′ａの平均粗さ
R_aが2μm以上であることが好ましい。一方テイ
ンフリースチールよりなる缶胴成形体の場合は、
平均粗さR_aが約4μmより大きくなると、通電が
不安定になり溶接状態を悪化させるので、平均粗
さR_aは4μm以下であることが好ましい。なお一
度内部電極ロール５、外部電極ロール６を通過し
た線電極７，７′は、廃棄されて再使用されない。本発明は以上の例によつて制約されるものでな
く、例えば特開昭60−227983号に提案されたよう
な、重ね合わせ部の接触面が線電極の電極面に対
して傾斜して、第１の端部と第２の端部が互いに
噛み合うよう、表面処理被膜を除去することな
く、第１の端部と第２の端部が予め加工されてい
る重ね合わせ部を有する、缶胴成形体のマツシユ
シーム溶接による溶接缶胴の製造にも適用しうる
ものである。さらに金属ブランクは、特開昭53−23833号公
報に開示されているような比較的厚い水和クロム
酸化物層を表面に有する鉄錫合金被覆鋼板、ある
いは比較的厚い水和クロム酸化物層を表面に有す
る極薄ニツケル又はニツケル−錫めつき鋼板等よ
りなるものであつてもよい。以下具体例について述べる。具体例厚さ0.22mm、金属クロム量100mg／m²、クロム
酸化物量（金属クロム換算）15mg／m²の両面に塗
膜を形成されたテインフリースチールのブランク
から、重ね合わせ部幅0.4mmの缶胴成形体を形成
し、次の溶接条件で、種々の平均粗さの電極面７
ａ，７′ａを有する線電極を用いて、スードロニ
ツク溶接機で、電気抵抗マツシユシーム溶接して
溶接缶胴を作製した。溶接条件：電流周波数…250Hz、溶接速度…
30m／分、溶接力…50Kgｆ、線電極幅…2.0mm。結果を第１表に示す。なお表面処理被膜層が重
ね合わせ部に残つた状態で溶接を行つた。 (Industrial Application Field) The present invention relates to a method for manufacturing a welded can body, and more particularly, the present invention relates to a method for manufacturing a welded can body, and more specifically, a welded can body is manufactured by electric resistance mating seam welding of the overlapped side portions of can body molded bodies having a surface treatment film layer. Regarding the method. (Prior Art) Welded can bodies, for example, welded can bodies for storing beer, carbonated drinks, juices, etc., are usually made by overlapping can bodies formed by rolling metal blanks into a cylindrical shape to form overlapping parts. The parts are manufactured by electrical resistance pine seam solid state welding through smooth-surfaced wire electrodes using a pair of opposing electrode rolls. In that case, the metal blank is a low carbon steel plate (so-called blackboard) that does not have a surface treatment coating, or a metal plate that has a surface treatment coating with relatively low electrical resistance, such as an ordinary tinned steel plate (tinplate). In such cases, it is possible to relatively easily manufacture a satisfactory welded can body using the above method without causing defects due to splashes (molten metal splashes), etc., and to manufacture a welded can body made of tinned steel plate. Manufacture has been commercially successful. However, like stain-free steel (electrolytic chromic acid treated steel sheet), there are surface treatment coatings with relatively high electrical insulation properties (in this case, it is mainly a hydrated chromium oxide layer, and the thickness is usually 5 to 30 mm in terms of metal chromium).
In the case ^of can body molded bodies formed from metal blanks made of metal plates with A satisfactory weld could not be obtained unless the oxide layer and metallic chromium layer were removed using a milling cutter or the like. Removal of this surface treatment film layer not only impairs the corrosion resistance of the weld, but also increases the cost due to increased tool costs and process steps due to cutter wear, and the risk of residual chips entering the contents (e.g. beer). This causes problems such as deterioration of flavor. As a result of various studies on this countermeasure, the present inventors have found that by applying a much higher welding force (per the same overlap width) than in the case of a can body formed body made of tin-plated steel sheets, the surface treatment coating can be applied. It has been found that a stain-free steel can body formed body having an overlapping portion having layers can be pine seamed welded without significant splashing. However, in this case, during welding, the vicinity of the front end and the rear end (the last part to be welded) of the overlapping part (usually width 0.2 to 1.5 mm), especially the latter, shift outward in the circumferential direction, causing damage to these parts. This results in a problem in that the width of the weld is reduced, or in extreme cases, the weld becomes a butt-like weld, reducing the weld strength and causing cracks when flanging is performed.
The phenomenon of this shift is presumed to be due to the material escaping outward in the circumferential direction due to the large amount of mush caused by the strong welding force. The above-mentioned deviation is relatively unlikely to occur in areas other than the vicinity of the above-mentioned ends. A so-called Z bar with a Z-shaped cross section that guides the mating part to the vicinity of the electrode roll inlet, a group of guide rolls surrounding the can body molded body in the vicinity of the electrode roll, and a pair of electrodes arranged so as to be slightly oblique to each other. This is because rolls and other rolls that take measures to prevent slippage are generally used. Even if this type of welding machine is used, the reason why the deviation occurs especially in the vicinity of the rear end of the overlapping part in the above case is because the vicinity of the rear end passes through the electrode roll (via the wire electrode).
It is presumed that this is because the restraining force of the Z bar and guide roll group is lost. (Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned problems of the prior art. A method for producing a welded can body by solid-phase electrical resistance pine seaming welding of the parts through a wire electrode using a pair of electrode rolls, even if the surface treatment coating layer has relatively high electrical insulation. To provide a method for manufacturing a welded can body, which allows a satisfactory welded part to be obtained over the entire length while leaving a surface treatment coating layer in the overlapping part even if the welded can body is welded. (Means for Solving the Problems) In order to achieve the above object, the present invention provides a metal blank having a surface treatment film layer, with the opposing first and second ends of the metal blank having the surface treatment film layer left behind. In a method for manufacturing a welded can body, in which the overlapping portions of can body molded bodies formed by overlapping each other are electrically resistance mat seam welded via a wire electrode using a pair of opposing electrode rolls, the wire electrode The present invention provides a method for manufacturing a welded can body, characterized in that the surface in contact with the overlapping portion is roughened to an average roughness of 2 to 4 μm. (Function) In the present invention, the surface in contact with the overlapping portion of the wire electrodes is roughened to an average roughness of 2 μm or more. Therefore, during welding, the above-mentioned surface of the wire electrode digs into the heated and softened surface of the overlapping part, so even if welding is performed with a relatively high welding force, the surface of the wire electrode will not cut over the entire length of the overlapping part, including near the front and rear ends. Therefore, displacement outward in the circumferential direction is unlikely to occur. In addition, if the average roughness of the above-mentioned surfaces of the overlapping part exceeds 4 μm, and the electrical insulation of the surface treatment film layer is relatively high, the current flow will become unstable even if welding is performed with a relatively high welding force. The welding condition deteriorates as splashes occur. However, in the case of the present invention, since the average roughness is 4 μm or less, such defects are unlikely to occur. Therefore, the present invention makes it possible to produce a welded can body having a satisfactory weld over the entire length even when the surface treatment coating layer of the metal blank has relatively high electrical insulation. (Example) In FIG. 1 showing the state immediately before welding, 1 is a can body formed body, which is formed by rolling up a rectangular blank of stain-free steel (not shown) and connecting the opposing first end 1a and the The ends 1b of 2 are overlapped with the surface treatment coating layer 2 (consisting of a metal chromium layer (not shown) on the base metal 3 side and a hydrated chromium oxide layer (not shown) on the surface side) remaining. It is made by forming part 4. The width of the overlapping portion 4 is usually about 0.2 to 1.5 mm. 5 is an internal electrode roll, 6 is an external electrode roll, and wire electrodes 7 are provided in the circumferential grooves 5a and 6a, respectively.
and 7' are inserted. The wire electrodes 7, 7' have a rectangular cross section with short sides shaped like arcs. The wire electrodes 7, 7' having such a shape are usually made of round copper wire.
It is obtained by flat rolling with a rolling roll on the upstream side of the internal electrode roll 5. Moreover, the wire electrodes 7 and 7' are usually made of one copper wire. That is, the inner line electrode 7 is folded back through a path not shown to become the outer line electrode 7'. Therefore, the flat inner surface 7a and the flat outer surface 7b of the inner wire electrode 7 become the outer surface 7'b and the inner surface 7'a of the outer wire electrode 7', respectively. In addition, in order to perform pine seam welding, the width of the inner surfaces 7a, 7'a is set larger than the width of the overlapping part 4, and the entire width of the overlapping part 4 during welding is
The molded can body 1 is fed so that it comes into contact with the can body. A flat surface 7a in contact with the overlapping part 4 of the inner line electrode 7 and the overlapping part 4 of the outer line electrode 7'
The flat surfaces 7'a in contact with the line electrodes 7, 7', and hence the flat surfaces 7a, 7'a, 7b, 7'b of the wire electrodes 7, 7' are roughened. Such a roughened wire electrode can be flat-rolled with a rolling roll whose surface has been roughened by sandblasting or grit blasting, or flattened with a regular rolling roll with a smooth surface. This can be obtained by sandblasting or gritblasting the flat surface of a rolled wire electrode. The flat surfaces (7a, 7'a, 7
b, 7'b)) has an average roughness R _a of approximately 0.1 to
The average roughness R _a of the flat surfaces 7a and 7'a in contact with the overlapping portion 4 of the wire electrodes applied to the present invention is preferably 2 to 4 μm. (Function) FIG. 2 shows that the internal electrode roll 5 and the external electrode roll 6 allow the wire electrodes 7 and 7' to
A relatively high pressing force is applied to the overlapping portion 4 (for example, about 1.5 times as much as in the case of a can body formed body made of tin-plated steel plate).
That is, welding force is applied and alternating current is applied to perform pine seam solid phase welding, and the welded portion 8 is welded.
1 shows a state immediately after forming a welded can body 10 having a welded can body 10. Since the inner surfaces 7a and 7'a of the wire electrodes bite into the surface of the overlapping part that is heated and softened during welding, even if the overlapping part 4 is near the front end and the rear end of the can body molded body 1, it will not be circular. Circumferential outward displacement is prevented. Therefore, there is no risk that the width of the welded portion 8 in these portions will be reduced or that an abutted welded portion will occur. In order to prevent the overlapping part 4 from shifting outward in the circumferential direction during welding, the average roughness of the surfaces 7a and 7'a of the wire electrodes in contact with the overlapping part 4 must be
It is preferable that R _a is 2 μm or more. On the other hand, in the case of a can body molded body made of stain-free steel,
If the average roughness R _a is larger than about 4 μm, the current flow becomes unstable and the welding condition deteriorates, so the average roughness R _a is preferably 4 μm or less. Note that the wire electrodes 7, 7' that have once passed through the internal electrode roll 5 and the external electrode roll 6 are discarded and are not reused. The present invention is not limited to the above examples, but, for example, as proposed in Japanese Patent Laid-Open No. 60-227983, the contact surface of the overlapping portion is inclined with respect to the electrode surface of the wire electrode, A can body having an overlapping portion in which the first end and the second end are pre-processed without removing the surface treatment coating so that the first end and the second end engage with each other. It can also be applied to the manufacture of welded can bodies by pine seam welding of molded bodies. Furthermore, the metal blank may be an iron-tin alloy coated steel plate having a relatively thick hydrated chromium oxide layer on its surface, as disclosed in JP-A No. 53-23833, or a steel plate coated with a relatively thick hydrated chromium oxide layer. It may be made of ultra-thin nickel or nickel-tin plated steel plate on the surface. A specific example will be described below. Specific example: From a stain-free steel blank with a thickness of 0.22 mm, a metal chromium content of 100 mg/m ² , a chromium oxide content (metal chromium equivalent) of 15 mg/m ² and a coating film formed on both sides, an overlapping part width of 0.4 mm is obtained. A molded can body is formed, and electrode surfaces 7 with various average roughnesses are welded under the following welding conditions.
A welded can body was fabricated by electric resistance pine seam welding using a Sudronik welding machine using wire electrodes having diameters a and 7'a. Welding conditions: Current frequency...250Hz, welding speed...
30m/min, welding force...50Kgf, wire electrode width...2.0mm. The results are shown in Table 1. Note that welding was performed with the surface treatment film layer remaining in the overlapped portion.

【表】（発明の効果）本発明の溶接缶胴の製造方法は、表面処理被膜
層の電気絶縁性が高い場合であつても、重ね合わ
せ部に表面処理被膜層を残したままで、全長にわ
たり満足な溶接部を有する溶接缶胴を製造できる
という効果を奏する。[Table] (Effects of the Invention) The method for manufacturing a welded can body of the present invention allows the surface treatment film layer to remain in the overlapping portion and extend over the entire length even when the surface treatment film layer has high electrical insulation. The effect is that a welded can body having a satisfactory welded area can be manufactured.

[Brief explanation of the drawing]

第１図、および第２図は夫々、本発明の溶接が
行われる直前、および溶接終了直後の状態の例を
示す、線電極の軸線に垂直な面に沿う縦断面図で
ある。１……缶胴成形体、１ａ……第１の端部、１ｂ
……第２の端部、２……表面処理被膜層、４……
重ね合わせ部、７……線電極、７ａ……内面（重
ね合わせ部と接する面）、７′……線電極、７′ａ
……内面（重ね合わせ部と接する面）、８……溶
接部、１０……溶接缶胴。 FIG. 1 and FIG. 2 are longitudinal cross-sectional views along a plane perpendicular to the axis of the wire electrode, showing examples of the state immediately before welding of the present invention is performed and immediately after welding is completed, respectively. 1... Can body molded body, 1a... First end, 1b
...Second end portion, 2...Surface treatment film layer, 4...
Overlapping part, 7... Line electrode, 7a... Inner surface (surface in contact with the overlapping part), 7'... Line electrode, 7'a
...Inner surface (surface in contact with the overlapping part), 8...Welded part, 10...Welded can body.

Claims

[Claims]

1 The overlapping part of the can body formed body formed by overlapping the opposing first and second ends of a metal blank having a surface treatment film layer with the surface treatment film remaining, is In a method for manufacturing a welded can body in which electric resistance mat seam welding is performed via a wire electrode using a pair of electrode rolls, the surface of the wire electrode in contact with the overlapping portion has an average roughness of 2 to 4 μm.
A method for manufacturing a welded can body, characterized in that the welded can body has a roughened surface.