JP3628382B2 - Resistance welding method of aluminum material - Google Patents

Description

【００２７】
実施例１〜４及び比較例１：
実施例１〜４、比較例１において、溶接電流は２４ｋＡ、溶接時間は８サイクル、加圧力は３００ｋｇｆである。
実施例１：
図４に示す突起部１３ａの径ｄを５ｍｍとしたところ、溶接部の引張剪断強度は１３０ｋｇｆとなり、後に述べる比較例１に対し強度倍率は６．５倍（１３０ｋｇｆ／２０ｋｇｆ）と大幅に改善された。
【００２８】
実施例２：
突起部１３ａの径ｄを７ｍｍとしたところ、溶接部の引張剪断強度は２２０ｋｇｆとなり、比較例１に対し１１倍と大幅に改善された。
【００２９】
実施例３：
突起部１３ａの径ｄを１０ｍｍとしたところ、溶接部の引張剪断強度は２５０ｋｇｆとなり、比較例１に対し１２．５倍と大幅に改善された。
【００３０】
実施例４：
突起部１３ａの径ｄを１５ｍｍとしたところ、溶接部の引張剪断強度は２２０ｋｇｆとなり、比較例１に対し１１倍と大幅に改善された。
【００３１】
比較例１：
突起無しの条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は２０ｋｇｆと非常に小さい。
【００３２】
図６は表１の結果を示すグラフであり、横軸は突起径、縦軸は引張剪断強度を表す。突起径無しの条件である比較例１に対し、突起のある実施例１〜４は引張剪断強度が大幅に向上し、突起径１０ｍｍまでは突起径とともに増加している。
実施例３は実施例４に対しても引張剪断強度が大きく、溶接電流の集中度合い及び形成されるナゲットの大きさの点から最適条件であることが分かった。
【００３３】
図７は（ａ），（ｂ）は本発明に係る突起形成の別実施例の説明図であり、溶射による突起形成方法を示す。
（ａ）において、アルミニウム板３の表面の溶接すべき部分を除いてマスキング材７を貼付ける。この状態で溶接部分に溶融したアルミニウムをノズルより噴射し塗布する。表面にアルミニウム被膜８が形成される。
（ｂ）において、アルミニウム板３よりマスキング材７を取除くと、アルミニウム板３の表面にアルミニウム被膜８による突起が形成される。
【００３４】
この他に突起を形成する方法として、高真空中で金属材料を加熱し蒸発させて、溶接材表面に付着・推積させる物理蒸着（ＰＶＤ）や、金属材料をガス化し、このガスを熱、プラズマ、光等を用いて活性化して溶接材の表面上で化学反応を起こさせ、膜を形成する化学蒸着（ＣＶＤ）を用いてもよい。
【００３５】
図８（ａ），（ｂ）は本発明に係る抵抗溶接方法の第２実施例を示す斜視図であり、溶接位置のアルミニウム小片の周囲に難導電材を配置した例である。
（ａ）において、中空断面構造のアルミニウムフレーム１の接合面にアルミニウム小片２，２Ａを載せ、このアルミニウム小片２，２Ａの周囲に難導電材９を載せる。
この後、これらの上にアルミニウム板３を載せる。
【００３６】
その後に、（ｂ）において、一方のアルミニウム小片２を通る直線上に電極４，５が来るようにしてアルミニウム板３とアルミニウムフレーム１とを電極４，５で挟む。
【００３７】
難導電材９は、溶接中にずれないようにアルミニウムフレーム１表面上に粘着剤等を用いて貼付けてもよい。
この難導電材としては、樹脂、金属製の板・シート・テープ材が適当である。
【００３８】
図９（ａ），（ｂ）は図８（ｂ）の９−９線断面図であり、（ａ）において、難導電材９の厚さは、溶接後のアルミニウムフレーム１とアルミニウム板３との間隔を、溶接強度の関係からできるだけ小さくするため、０．１ｍｍ程度とする。アルミニウム小片２の厚さは１ｍｍ程度であり、溶接前は、難導電材９とアルミニウム板３との間に隙間を生じる。
【００３９】
電極４，５で押圧しつつ、通電して１打点目の抵抗溶接を行う。電流は図の矢印のように電極４からアルミニウム板３、アルミニウム小片２、アルミニウムフレーム１を通って電極５に流れる。アルミニウム小片２の断面積は小さいので、この部分に電流は集中する。
【００４０】
（ｂ）において、規定の通電時間を経て、アルミニウム小片２は溶接電流により溶融し、アルミニウムフレーム１とアルミニウム板３の接合面にナゲット６が形成される。
溶接後のアルミニウムフレーム１とアルミニウム板３との間隔は、難導電材９の厚さに保たれる。
次に、他方のアルミニウム小片２Ａを通る直線上に電極４，５が来るように移動させ、アルミニウム板３とアルミニウムフレーム１とを電極４，５で挟み、加圧通電して２打点目の溶接を行う。
【００４１】
電流は矢印のように、一つには電極４からアルミニウム板３、アルミニウム小片２Ａ、アルミニウムフレーム１を経て、電極５に流れる。もう一つは、電極４からアルミニウム板３、１打点目のナゲット、アルミニウムフレーム１を経て、電極５に流れる。１打点目の溶接を行ってもアルミニウムフレーム１とアルミニウム板３との間には難導電材９が介在しているので、ナゲットの周囲からは電流は流れず、２打点目の溶接への影響は少なくなる。この後、２打点目にもナゲット（不図示）が形成される。
【００４２】
図１０（ａ）〜（ｄ）は本発明に係る抵抗溶接方法の第２実施例の変形例を示す断面図であり、難導電材として粘性液状樹脂又は粘性液状樹脂に金属粉末を混練したものを使用した例を示す。尚、この金属自体も難導電材料である。
（ａ）において、アルミニウムフレーム１にアルミニウム小片２を載せ、このアルミニウム小片２の周囲に粘性液状樹脂である難導電材９Ａを盛り、これらの上にアルミニウム板３を載せ、アルミニウム小片２を通る直線上に電極４，５が来るように挟んで加圧通電する。電流は矢印のように流れる。
【００４３】
（ｂ）において、所定の通電時間を経てアルミニウム小片２は溶融し、アルミニウムフレーム１とアルミニウム板３の間にナゲット６が形成される。ナゲット６の周囲には難導電材９Ａの薄膜ができ、溶接に無効な電流が流れるのを防止する。
この難導電材９Ａとしては、エポキシ樹脂が適当である。他に接着剤やシーリング材で、要は電気抵抗の高い材料であり、溶接時の温度に耐えるものであれば良い。
【００４４】
（ｃ）において、難導電材９Ｂは、粘性液状樹脂に金属粉末を混練したものであり、溶接後のナゲット６の周囲には難導電材９Ｂの膜ができる。この膜は金属粉末の粒径（平均２００μｍ程度）によりアルミニウムフレーム１とアルミニウム板３とのクリアランスを一定に保ち絶縁性を高める。
この難導電材９Ｂの金属粉末としては、酸化アルミニウム、チタンが適当である。又、金属に限らず、セラミックスの粉末でも差し支えない。
【００４５】
（ｄ）では、粘性液状樹脂である難導電材９Ａを使用した場合の２打点目の電流の流れを示したものであり、電流は矢印のように、一つには電極４からアルミニウム板３、アルミニウム小片２Ａ、アルミニウムフレーム１を経て、電極５に流れる。もう一つは、電極４からアルミニウム板３、１打点目のナゲット、アルミニウムフレーム１を経て、電極５に流れる。
【００４６】
１打点目の溶接を行ってもアルミニウムフレーム１とアルミニウム板３との間には難導電材９Ａが介在しているので、ナゲットの周囲からは電流は流れず、２打点目の溶接への影響は少なくなる。この後、２打点目にもナゲット（不図示）が形成される。
【００４７】
本発明法の突起と難導電材との組合せによる２点打点時の溶接強度の評価結果を表２に基づいて説明する。尚、この評価に使用したアルミニウムフレーム１は肉厚３ｍｍ、４０ｍｍ角のＪＩＳ−６０６３−Ｔ５（Ａｌ−Ｍｇ−Ｓｉ系アルミニウム合金）押出材、アルミニウム板３は板厚１．２ｍｍのＪＩＳ−５１８２（Ａｌ−Ｍｇ系アルミニウム合金）圧延材、電極４，５は直径が１６ｍｍで、先端の曲率半径がＲ８０ｍｍの無酸素銅電極である。
この試験方法は、表１の試験方法と同一であり、説明を省略する。
尚、どの比較例、実施例ともアルミニウム板１３の突起径はφ１０ｍｍ、突起高さは１ｍｍとした。
【００４８】
【表２】

【００４９】
実施例５〜８及び比較例２，３：
実施例５〜８、比較例２，３において、溶接電流は２４ｋＡ、溶接時間は８サイクル、加圧力は３００ｋｇｆである。
実施例５：
難導電材として０．１ｍｍ厚の塩化ビニールシートを粘着材を使用して貼付け、この状態で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は３７０ｋｇｆとなった。後で述べる比較例３に対して強度倍率は１．４倍であり、充分な強度を有する。
【００５０】
実施例６：
難導電材として粘度１０００００ｃｐのエポキシ樹脂を使用した条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は３６０ｋｇｆとなった。比較例３に対して強度倍率は１．３倍であり、充分な強度を有する。
【００５１】
実施例７：
難導電材として粘度５００００ｃｐのエポキシ樹脂に平均粒径２００μｍ、Ｖｆ１０％の酸化アルミニウムを混練して使用した条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は４００ｋｇｆとなった。比較例３に対して強度倍率は１．５倍であり、充分な強度を有する。
【００５２】
実施例８：
難導電材として粘度５００００ｃｐのエポキシ樹脂に平均粒径２００μｍ、Ｖｆ１０％のチタンを混練して使用した条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は３５０ｋｇｆとなった。比較例３に対して強度倍率は１．３倍であり、充分な強度を有する。
【００５３】
比較例２：
突起無し、難導電材無しの条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は３０ｋｇｆと非常に小さい。
【００５４】
比較例３：
突起有り、難導電材無しの条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は２７０ｋｇｆとなった。
【００５５】
図１１は表２の結果を示すグラフであり、横軸は評価方法（比較例１，２、実施例５〜８）、縦軸は引張剪断強度を表す。
難導電材無しの条件である比較例３に対し、難導電材有りの条件である実施例５〜８はどれも引張剪断強度が大幅に向上している。
【００５６】
次に、本発明法の突起有りについて、粘性液状樹脂の粘度による２点打点時の溶接強度の評価結果を表３に基づいて説明する。尚、この評価に使用したアルミニウムフレーム１は肉厚３ｍｍ、４０ｍｍ角のＪＩＳ−６０６３−Ｔ５（Ａｌ−Ｍｇ−Ｓｉ系アルミニウム合金）押出材、アルミニウム板３は板厚１．２ｍｍのＪＩＳ−５１８２（Ａｌ−Ｍｇ系アルミニウム合金）圧延材、電極４，５は直径が１６ｍｍで、先端の曲率半径がＲ８０ｍｍの無酸素銅電極である。
【００５７】
この試験方法は、表１の試験方法と同一であり、説明を省略する。
尚、どの実施例ともアルミニウム板１３の突起径はφ１０ｍｍ、突起高さは１ｍｍとし、粘性液状樹脂はエポキシ樹脂とした。
【００５８】
【表３】

【００５９】
実施例９〜１４：
実施例９〜１４において、溶接電流は２４ｋＡ、溶接時間は８サイクル、加圧力は３００ｋｇｆである。
実施例９：
粘性液状樹脂の粘度を１００ｃｐとした条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は２７０ｋｇｆとなった。表２で説明を行った比較例３に対して溶接強度は同一となった。
【００６０】
実施例１０：
粘性液状樹脂の粘度を５００ｃｐとした条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は２８０ｋｇｆとなった。比較例３に対して溶接強度は同等となった。
【００６１】
実施例１１：
粘性液状樹脂の粘度を１０００ｃｐとした条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は２８０ｋｇｆとなった。比較例３に対して溶接強度は同等となった。
【００６２】
実施例１２：
粘性液状樹脂の粘度を５０００ｃｐとした条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は３５０ｋｇｆとなった。比較例３に対して強度倍率は１．３倍となり、充分な強度を有する。
【００６３】
実施例１３：
粘性液状樹脂の粘度を１００００ｃｐとした条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は３８０ｋｇｆとなった。比較例３に対して強度倍率は１．４倍となり、充分な強度を有する。
【００６４】
実施例１４：
粘性液状樹脂の粘度を１０００００ｃｐとした条件で抵抗溶接したところ、溶接後の引張剪断試験において、溶接部の引張剪断強度は４００ｋｇｆとなった。比較例３に対して強度倍率は１．５倍となり、充分な強度を有する。
【００６５】
図１２は表３の結果を示すグラフであり、横軸は粘性液状樹脂の樹脂粘度（対数目盛）、縦軸は引張剪断強度を表す。
樹脂粘度が大きくなるにつれて、引張剪断強度は増加する。
引張剪断強度の増加傾向をみると、粘度１０００ｃｐの実施例１１に対し、粘度５０００ｃｐの実施例１２の変化が大きく、強度そのものも４００ｋｇｆ近くと大きいため、難導電材としての粘性液状樹脂の粘度は５０００ｃｐ以上が望ましい。
【００６６】
図１３は本発明に係る抵抗溶接方法の変形例を示す図であり、中空断面構造押出材のアルミニウムフレーム同士の接合方法である。
この方法は、まず、中空断面構造の第１のアルミニウムフレーム２１の接合部を、複数の突起を有し、アルミニウムフレーム２１の幅よりも大きな幅を有するアルミニウム板２３，２３で挟み込む。この時、アルミニウムフレーム２１とアルミニウム板２３，２３との間には難導電材（不図示）を挿入しておく。
次に、アルミニウム板２３，２３の溶接部を２つの電極（不図示）で挟み、複数個所を加圧通電して溶接する。
【００６７】
次に２つのアルミニウム板２３，２３の突接部２３ａ，２３ａの間に第２のアルミニウムフレーム２２を挿入し、第１のアルミニウムフレーム２１に当接させる。この時、アルミニウムフレーム２２とアルミニウム板２３，２３との間には難導電材を挿入しておく。
この後、第２のアルミニウムフレーム２２、２つのアルミニウム板２３，２３を２つの電極で挟み、複数個所を加圧通電して溶接する。
【００６８】
【発明の効果】
請求項１の抵抗溶接方法は、中空断面構造のアルミニウムフレームに、電流集中部材を載せ、この電流集中部材を囲うように難導電材をアルミニウムフレームに載せ、これら電流集中部材並びに難導電材の上にアルミニウム板を載せ、これらアルミニウムフレームとアルミニウム板とを電極で押圧維持しつつ、通電するので、電流集中部材とアルミニウムフレームとの間並びに電流集中部材とアルミニウム板との間に電流が集中し、溶接部強度を増すことが可能となる。即ち、必要溶接強度を得るのに低電流で済む。また、２打点目以降を溶接する時も難導電材の作用で溶接に無効な電流が流れず、溶接に寄与する電流が低下しにくく、溶接部強度を大きくできる。即ち、２打点目以降の必要溶接強度を得るのに低電流で済む。
【００６９】
請求項２の抵抗溶接方法は、電流集中部材は、アルミニウムの小片なので、溶接個所の位置決めが容易となり、溶接するための準備工数が多くかからない。
【００７０】
請求項３の抵抗溶接方法は、電流集中部材は、前記アルミニウム板又はアルミニウムフレームに形成した突起なので、容易に形成でき、溶接するための準備工数が多くかからない。
【００７１】
請求項４の抵抗溶接方法は、難導電材は、樹脂なので、樹脂を板状又はフィルム状としてアルミニウム板とアルミニウムフレームとの間に挿入でき、クリアランスを確保して、難導電材の効果を高め、効率の良い溶接が可能となる。
【００７２】
請求項５の抵抗溶接方法は、難導電材は、液状樹脂に金属の粉末又はセラミックスの粉末を混練したものなので、金属の粉末又はセラミックスの粉末がアルミニウム板とアルミニウムフレームとの間に挟まれて，クリアランスを保つことができ、難導電材の効果を高め、効率の良い溶接が可能となる。
【図面の簡単な説明】
【図１】本発明に係る抵抗溶接方法の第１実施例を示す斜視図
【図２】図１（ｂ）の２−２線断面図
【図３】本発明に係る抵抗溶接方法の第２実施例を示す斜視図（要部）
【図４】図３の４−４線断面図
【図５】本発明に係る抵抗溶接後の溶着部の断面図
【図６】表１の結果を示すグラフ
【図７】本発明に係る突起形成の別実施例の説明図
【図８】本発明に係る抵抗溶接方法の第２実施例を示す斜視図
【図９】図８（ｂ）の９−９線断面図
【図１０】本発明に係る抵抗溶接方法の第２実施例の変形例を示す断面図
【図１１】表２の結果を示すグラフ
【図１２】表３の結果を示すグラフ
【図１３】本発明に係る抵抗溶接方法の変形例を示す図
【図１４】アルミニウム構造体の接合施工図
【図１５】アルミニウムフレームにアルミニウム板を抵抗溶接する改良された従来例図
【符号の説明】
１…アルミニウムフレーム、２，２Ａ…アルミニウム小片（電流集中部材）、３，１３…アルミニウム板、９，９Ａ，９Ｂ…難導電材、１３ａ…突起（電流集中部材）。[0001]
[Industrial application fields]
The present invention relates to a resistance welding technique for aluminum materials.
[0002]
[Prior art]
An aluminum material is used in order to reduce the weight of the structure, and a technique for joining a stringer and a column of a vehicle body via a knot member is disclosed in JP-A-60-135375. A construction method similar to this technology is described in detail in the following figure.
[0003]
FIGS. 14 (a) and 14 (b) are diagrams for joining aluminum structures. When joining the square pipes 101, 102, and 103, for example, a T-shaped joint 104 is prepared, and the square pipe is connected to the joint 104. FIG. The end parts 101 to 103 are inserted and joined by TIG, MIG or laser welding to produce the structure shown in (b). The square pipes 101 to 103 are hollow aluminum frames having a closed cross-sectional structure, and are manufactured by an extrusion method. The joint 104 is an aluminum casting because of its complicated shape.
[0004]
15 (a) and 15 (b) are diagrams showing an improved conventional example in which an aluminum plate is resistance-welded to an aluminum frame. As shown in FIG. 15 (a), a flange 121 is integrally formed on the aluminum frame 120 in advance. An aluminum plate 122 is placed on the flange 121 and resistance welding is performed with the electrodes 113 and 114.
(B) is sectional drawing after welding, 123 is a nugget (welded metal).
[0005]
[Problems to be solved by the invention]
In the joining method of the aluminum structure shown in FIG. 14, if the welding method is TIG or MIG, the thermal strain becomes large, the strain removing heat treatment becomes indispensable, the construction cost increases, and the construction period becomes long. In the laser welding method, there is no problem with thermal distortion, but since high machining accuracy is required, work efficiency is low and it is difficult to reduce the work cost. Further, since the knot member is used, the number of parts increases and the cost increases.
[0006]
In the technique of resistance welding of an aluminum plate to the aluminum frame of FIG. 15, the cost for welding can be kept low, but the flange must be formed in advance, and the material cost and manufacturing cost of the aluminum frame are expensive. Moreover, since the flange becomes a strength member, it is difficult to bend the aluminum frame in the flange direction, and there is a problem that secondary processing of the aluminum frame becomes difficult.
[0007]
Further, in (b), since the joining surface of the flange 121 and the aluminum plate 122 is also in contact with the other part of the pressed part by the electrode, the welding current flows to the part that is not welded, and the current of the part to be welded There was a problem that would decrease. Here, in order to obtain a desired welding strength, there is a method of increasing the current value between the electrodes, but the cost becomes a problem.
Accordingly, an object of the present invention is to provide a resistance welding method which can be performed without a joint or a flange in joining a hollow cross-section frame and an aluminum plate and can obtain a desired welding strength even at a low current.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a current cross-sectional structure of an aluminum frame having a current-concentrating member mounted thereon, and a non-conductive material placed on the aluminum frame so as to surround the current-concentrating member. In addition, an aluminum plate is placed on the hardly conductive material, and the aluminum frame and the aluminum plate are energized while being pressed by the electrodes.
[0009]
According to a second aspect of the present invention, the current concentration member is a small piece of aluminum.
[0010]
According to a third aspect of the present invention, the current concentration member is a protrusion formed on an aluminum plate or an aluminum frame.
[0011]
According to a fourth aspect of the present invention, the hardly conductive material is a resin.
[0012]
The fifth aspect of the present invention is characterized in that the hardly conductive material is obtained by kneading a metal powder or a ceramic powder in a liquid resin.
[0013]
[Action]
According to the first aspect, the current concentrates between the current concentrating member and the aluminum frame and between the current concentrating member and the aluminum plate, so that the strength of the welded portion is increased . Also, since the intervening Nanshirube material, current is difficult to flow between the aluminum frame and the aluminum plate, it is possible to reduce the loss of current.
[0014]
According to the second aspect of the present invention , the current concentration member is an aluminum piece, and the current is concentrated on the aluminum piece.
[0015]
According to a third aspect of the present invention , the current concentration member is a protrusion formed on an aluminum plate or an aluminum frame, and the current is concentrated on the protrusion.
[0016]
According to a fourth aspect of the present invention , the hardly conductive material is a resin, and the resin is formed into a plate shape or a film shape and inserted between the aluminum plate and the aluminum frame.
[0017]
According to the fifth aspect of the present invention , the hardly conductive material is a liquid resin in which metal powder or ceramic powder is kneaded, and this is sandwiched between an aluminum plate and an aluminum frame to maintain clearance.
[0018]
【Example】
Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIGS. 1A and 1B are perspective views showing a first embodiment of a resistance welding method according to the present invention. In FIG. 1A, an aluminum piece 2 is placed on the joining surface of an aluminum frame 1 having a hollow cross-sectional structure. The aluminum plate 3 is placed on the aluminum piece 2. Next, in (b), the aluminum plate 3 and the aluminum frame 1 are sandwiched between the electrodes 4 and 5 so that the electrodes 4 and 5 come on a straight line passing through the aluminum piece 2.
[0019]
FIGS. 2A and 2B are cross-sectional views taken along line 2-2 of FIG. 1B. In FIG. 2A, resistance welding is performed by energization while pressing with the electrodes 4 and 5. The current flows from the electrode 4 to the electrode 5 through the aluminum plate 3, the aluminum piece 2, and the aluminum frame 1 as indicated by the arrows in the figure. Since the cross-sectional area of the aluminum piece 2 is small, the current is concentrated in this portion.
[0020]
In (b), after a predetermined energization time, the aluminum piece 2 is melted by Joule heat, and a nugget 6 is formed on the joint surface between the aluminum frame 1 and the aluminum plate 2.
[0021]
FIG. 3 is a perspective view (essential part) showing a second embodiment of the resistance welding method according to the present invention. The aluminum plate 13 is provided with a projection 13a (see FIG. 4) on the surface to be joined to the aluminum frame 1 to provide resistance. Weld.
[0022]
4 is a cross-sectional view taken along line 4-4 of FIG. 3. Since the aluminum frame 1 and the aluminum plate 13 are in contact with each other with a small area of the protrusion 13a of the aluminum plate 13, the welding current is concentrated on this portion, which is good. Resistance welding can be performed.
Here, d is the protrusion diameter, and h is the protrusion height.
Since the projection can be formed at a plurality of locations simultaneously by pressing, it can be easily formed.
[0023]
Since the electrode 4 has a sufficiently large outer diameter with respect to the protrusion diameter, the aluminum plate 13 can continue to be pressurized even after the protrusion is melted and good welding can be performed.
FIG. 5 is a cross-sectional view of the welded portion after resistance welding according to the present invention. The protrusion 13a of the aluminum plate 13 melts after a specified energization time, and as a result, the nugget 6 is formed.
[0024]
The evaluation result of the welding strength according to the projection diameter of the method of the present invention will be described based on Table 1. The aluminum frame 1 used in this evaluation is a JIS-6063-T5 (Al-Mg-Si-based aluminum alloy) extruded material having a thickness of 3 mm and a 40 mm square, and the aluminum plate 3 is JIS-5182 (a thickness of 1.2 mm). (Al—Mg-based aluminum alloy) Rolled material, electrodes 4 and 5 are oxygen-free copper electrodes having a diameter of 6 mm and a radius of curvature of the tip of R80 mm.
[0025]
As shown in FIG. 5, this test method is a method in which the welded aluminum frame 1 and the aluminum plate 13 are pulled as indicated by arrows, and the load when the welded portion breaks due to shear is measured.
In addition, the protrusion height h of the aluminum plate 13 was 1 mm in all the examples.
[0026]
[Table 1]

[0027]
Examples 1 to 4 and Comparative Example 1:
In Examples 1 to 4 and Comparative Example 1, the welding current is 24 kA, the welding time is 8 cycles, and the applied pressure is 300 kgf.
Example 1:
When the diameter d of the protrusion 13a shown in FIG. 4 is 5 mm, the tensile shear strength of the welded portion is 130 kgf, and the strength magnification is significantly improved to 6.5 times (130 kgf / 20 kgf) as compared with Comparative Example 1 described later. It was.
[0028]
Example 2:
When the diameter d of the protruding portion 13a was 7 mm, the tensile shear strength of the welded portion was 220 kgf, which was a significant improvement of 11 times that of Comparative Example 1.
[0029]
Example 3:
When the diameter d of the protruding portion 13a was 10 mm, the tensile shear strength of the welded portion was 250 kgf, which was significantly improved by 12.5 times compared to Comparative Example 1.
[0030]
Example 4:
When the diameter d of the protruding portion 13a was 15 mm, the tensile shear strength of the welded portion was 220 kgf, which was a significant improvement of 11 times that of Comparative Example 1.
[0031]
Comparative Example 1:
When resistance welding was performed under conditions without protrusions, in the tensile shear test after welding, the tensile shear strength of the welded portion was as extremely low as 20 kgf.
[0032]
FIG. 6 is a graph showing the results of Table 1. The horizontal axis represents the protrusion diameter, and the vertical axis represents the tensile shear strength. Compared to Comparative Example 1 where there is no protrusion diameter, Examples 1 to 4 with protrusions have greatly improved tensile shear strength, and the protrusion diameter increases up to 10 mm with the protrusion diameter.
Example 3 has a larger tensile shear strength than Example 4 and was found to be the optimum condition in terms of the degree of concentration of the welding current and the size of the nugget formed.
[0033]
FIGS. 7A and 7B are explanatory views of another embodiment of the protrusion formation according to the present invention, and show a protrusion formation method by thermal spraying.
In (a), the masking material 7 is affixed except for the portion to be welded on the surface of the aluminum plate 3. In this state, molten aluminum is sprayed from the nozzle and applied to the welded portion. An aluminum coating 8 is formed on the surface.
In (b), when the masking material 7 is removed from the aluminum plate 3, protrusions made of the aluminum coating 8 are formed on the surface of the aluminum plate 3.
[0034]
Other methods for forming protrusions include physical vapor deposition (PVD) in which a metal material is heated and evaporated in a high vacuum to adhere to and accumulate on the surface of the welded material, and the metal material is gasified. Chemical vapor deposition (CVD) may be used in which a film is formed by causing a chemical reaction on the surface of the welding material by activation using plasma, light, or the like.
[0035]
FIGS. 8A and 8B are perspective views showing a second embodiment of the resistance welding method according to the present invention, which is an example in which a hardly conductive material is arranged around an aluminum piece at a welding position.
In (a), the aluminum pieces 2 and 2A are placed on the joint surface of the aluminum frame 1 having a hollow cross-sectional structure, and the poorly conductive material 9 is placed around the aluminum pieces 2 and 2A.
Thereafter, the aluminum plate 3 is placed thereon.
[0036]
Thereafter, in (b), the aluminum plate 3 and the aluminum frame 1 are sandwiched between the electrodes 4 and 5 so that the electrodes 4 and 5 come on a straight line passing through one aluminum piece 2.
[0037]
The hardly conductive material 9 may be attached to the surface of the aluminum frame 1 using an adhesive or the like so that it does not slip during welding.
As the hardly conductive material, a resin, a metal plate / sheet / tape material is suitable.
[0038]
9 (a) and 9 (b) are cross-sectional views taken along line 9-9 of FIG. 8 (b). In FIG. 9 (a), the thickness of the difficult-to-conductive material 9 is as follows. Is set to about 0.1 mm in order to make the interval as small as possible in view of the welding strength. The thickness of the aluminum piece 2 is about 1 mm, and a gap is formed between the hardly conductive material 9 and the aluminum plate 3 before welding.
[0039]
While being pressed by the electrodes 4 and 5, energization is performed and resistance welding at the first spot is performed. The current flows from the electrode 4 to the electrode 5 through the aluminum plate 3, the aluminum piece 2, and the aluminum frame 1 as indicated by the arrows in the figure. Since the cross-sectional area of the aluminum piece 2 is small, the current is concentrated in this portion.
[0040]
In (b), after a prescribed energization time, the aluminum piece 2 is melted by a welding current, and a nugget 6 is formed on the joint surface between the aluminum frame 1 and the aluminum plate 3.
The distance between the aluminum frame 1 and the aluminum plate 3 after welding is kept at the thickness of the hardly conductive material 9.
Next, the electrodes 4 and 5 are moved so as to come on a straight line passing through the other aluminum piece 2A, the aluminum plate 3 and the aluminum frame 1 are sandwiched between the electrodes 4 and 5, and a second energization welding is performed by applying pressure. I do.
[0041]
As indicated by the arrows, the current flows from the electrode 4 to the electrode 5 through the aluminum plate 3, the aluminum piece 2A, and the aluminum frame 1, for example. The other flows from the electrode 4 to the electrode 5 through the aluminum plate 3, the first nugget nugget, and the aluminum frame 1. Even if the first spot welding is performed, the non-conductive material 9 is interposed between the aluminum frame 1 and the aluminum plate 3, so that no current flows from the periphery of the nugget, which affects the second spot welding. Will be less. Thereafter, a nugget (not shown) is also formed at the second hit point.
[0042]
FIGS. 10A to 10D are cross-sectional views showing a modification of the second embodiment of the resistance welding method according to the present invention, in which a metal powder is kneaded into a viscous liquid resin or a viscous liquid resin as a hardly conductive material. An example using is shown. This metal itself is also a difficult conductive material.
In (a), an aluminum piece 2 is placed on an aluminum frame 1, a hardly conductive material 9 A, which is a viscous liquid resin, is placed around the aluminum piece 2, an aluminum plate 3 is placed thereon, and a straight line passing through the aluminum piece 2 Pressurization energization is performed with the electrodes 4 and 5 placed on top. Current flows as shown by the arrows.
[0043]
In (b), the aluminum piece 2 is melted after a predetermined energization time, and a nugget 6 is formed between the aluminum frame 1 and the aluminum plate 3. Around the nugget 6 can thin Nanshirube material 9A, prevented from flowing invalid current for welding.
An epoxy resin is suitable as the hardly conductive material 9A. Other than that, an adhesive or a sealing material, which is a material having a high electrical resistance and can withstand the temperature during welding, may be used.
[0044]
In (c), the hardly conductive material 9B is obtained by kneading metal powder into a viscous liquid resin, and a film of the hardly conductive material 9B is formed around the nugget 6 after welding. This film increases the insulation by keeping the clearance between the aluminum frame 1 and the aluminum plate 3 constant by the particle size of the metal powder (average of about 200 μm).
As the metal powder of the hardly conductive material 9B, aluminum oxide and titanium are suitable. Moreover, it is not limited to metal, and ceramic powder may be used.
[0045]
(D) shows the current flow at the second point of hitting when the hardly conductive material 9A, which is a viscous liquid resin, is used. The current flows from the electrode 4 to the aluminum plate 3 as indicated by arrows. Then, it flows to the electrode 5 through the aluminum piece 2A and the aluminum frame 1. The other flows from the electrode 4 to the electrode 5 through the aluminum plate 3, the first nugget nugget, and the aluminum frame 1.
[0046]
Even if the first spot welding is performed, the hardly conductive material 9A is interposed between the aluminum frame 1 and the aluminum plate 3, so that no current flows from the periphery of the nugget, which affects the second spot welding. Will be less. Thereafter, a nugget (not shown) is also formed at the second hit point.
[0047]
Based on Table 2, the evaluation results of the welding strength at the time of two-point hitting by the combination of the projection of the present invention and the hardly conductive material will be described. The aluminum frame 1 used in this evaluation is a JIS-6063-T5 (Al-Mg-Si-based aluminum alloy) extruded material having a thickness of 3 mm and a 40 mm square, and the aluminum plate 3 is JIS-5182 (a thickness of 1.2 mm). Al-Mg-based aluminum alloy) Rolled material, electrodes 4 and 5 are oxygen-free copper electrodes having a diameter of 16 mm and a radius of curvature of the tip of R80 mm.
This test method is the same as the test method in Table 1, and a description thereof will be omitted.
In all comparative examples and examples, the projection diameter of the aluminum plate 13 was 10 mm, and the projection height was 1 mm.
[0048]
[Table 2]

[0049]
Examples 5 to 8 and Comparative Examples 2 and 3:
In Examples 5 to 8 and Comparative Examples 2 and 3, the welding current is 24 kA, the welding time is 8 cycles, and the applied pressure is 300 kgf.
Example 5:
When a 0.1-mm-thick vinyl chloride sheet was affixed using an adhesive material as a hardly conductive material and resistance welding was performed in this state, the tensile shear strength of the welded portion was 370 kgf in the tensile shear test after welding. Compared to Comparative Example 3 described later, the strength magnification is 1.4 times, which is sufficient.
[0050]
Example 6:
When resistance welding was performed under the condition of using an epoxy resin having a viscosity of 100,000 cp as the poorly conductive material, the tensile shear strength of the welded portion was 360 kgf in the tensile shear test after welding. Compared with Comparative Example 3, the strength magnification is 1.3 times, which is sufficient.
[0051]
Example 7:
When resistance welding was carried out under the condition that kneaded aluminum oxide having an average particle diameter of 200 μm and Vf of 10% was used as an electrically conductive material in an epoxy resin having a viscosity of 50000 cp, the tensile shear strength of the welded portion was 400 kgf in the tensile shear test after welding. became. Compared with Comparative Example 3, the strength magnification is 1.5 times, which is sufficient.
[0052]
Example 8:
When resistance welding was performed under the condition that kneaded titanium having an average particle diameter of 200 μm and Vf of 10% was used as an electrically conductive material with an epoxy resin having a viscosity of 50000 cp, the tensile shear strength of the welded part was 350 kgf in the tensile shear test after welding. It was. Compared with Comparative Example 3, the strength magnification is 1.3 times, which is sufficient.
[0053]
Comparative Example 2:
When resistance welding was performed under the conditions of no protrusions and no difficult conductive material, in the tensile shear test after welding, the tensile shear strength of the welded portion was as extremely low as 30 kgf.
[0054]
Comparative Example 3:
When resistance welding was performed with protrusions and no difficult conductive material, the tensile shear strength of the weld was 270 kgf in the tensile shear test after welding.
[0055]
FIG. 11 is a graph showing the results of Table 2. The horizontal axis represents the evaluation method (Comparative Examples 1 and 2 and Examples 5 to 8), and the vertical axis represents the tensile shear strength.
Compared to Comparative Example 3 where there is no difficult conductive material, Examples 5 to 8 which are conditions where there is a difficult conductive material have significantly improved tensile shear strength.
[0056]
Next, with respect to the presence of protrusions according to the present invention, the evaluation results of the welding strength at the time of two-point hitting based on the viscosity of the viscous liquid resin will be described based on Table 3. The aluminum frame 1 used in this evaluation is a JIS-6063-T5 (Al-Mg-Si-based aluminum alloy) extruded material having a thickness of 3 mm and a 40 mm square, and the aluminum plate 3 is JIS-5182 (a thickness of 1.2 mm). Al-Mg-based aluminum alloy) Rolled material, electrodes 4 and 5 are oxygen-free copper electrodes having a diameter of 16 mm and a radius of curvature of the tip of R80 mm.
[0057]
This test method is the same as the test method in Table 1, and a description thereof will be omitted.
In any of the examples, the projection diameter of the aluminum plate 13 was φ10 mm, the projection height was 1 mm, and the viscous liquid resin was an epoxy resin.
[0058]
[Table 3]

[0059]
Examples 9-14:
In Examples 9 to 14, the welding current is 24 kA, the welding time is 8 cycles, and the applied pressure is 300 kgf.
Example 9:
When resistance welding was performed under the condition that the viscosity of the viscous liquid resin was 100 cp, the tensile shear strength of the welded portion was 270 kgf in the tensile shear test after welding. The welding strength was the same as that of Comparative Example 3 described in Table 2.
[0060]
Example 10:
When resistance welding was performed under the condition that the viscosity of the viscous liquid resin was 500 cp, the tensile shear strength of the welded portion was 280 kgf in the tensile shear test after welding. The welding strength was equivalent to that of Comparative Example 3.
[0061]
Example 11:
When resistance welding was performed under the condition that the viscosity of the viscous liquid resin was 1000 cp, the tensile shear strength of the welded portion was 280 kgf in the tensile shear test after welding. The welding strength was equivalent to that of Comparative Example 3.
[0062]
Example 12:
When resistance welding was performed under the condition that the viscosity of the viscous liquid resin was 5000 cp, the tensile shear strength of the welded part was 350 kgf in the tensile shear test after welding. The strength magnification is 1.3 times that of Comparative Example 3, and the strength is sufficient.
[0063]
Example 13:
When resistance welding was performed under the condition where the viscosity of the viscous liquid resin was 10,000 cp, the tensile shear strength of the welded portion was 380 kgf in the tensile shear test after welding. The strength magnification is 1.4 times that of Comparative Example 3, which is sufficient.
[0064]
Example 14:
When resistance welding was performed under the condition that the viscosity of the viscous liquid resin was 100000 cp, the tensile shear strength of the welded portion was 400 kgf in the tensile shear test after welding. Compared with Comparative Example 3, the strength magnification is 1.5 times, which is sufficient.
[0065]
FIG. 12 is a graph showing the results of Table 3. The horizontal axis represents the resin viscosity (logarithmic scale) of the viscous liquid resin, and the vertical axis represents the tensile shear strength.
As the resin viscosity increases, the tensile shear strength increases.
Looking at the increasing tendency of the tensile shear strength, the change in Example 12 with a viscosity of 5000 cp is larger than that in Example 11 with a viscosity of 1000 cp, and the strength itself is as large as 400 kgf. Therefore, the viscosity of the viscous liquid resin as a hardly conductive material is 5000 cp or more is desirable.
[0066]
FIG. 13 is a view showing a modification of the resistance welding method according to the present invention, which is a method for joining aluminum frames of a hollow cross-section extruded material.
In this method, first, a joint portion of the first aluminum frame 21 having a hollow cross-sectional structure is sandwiched between aluminum plates 23 and 23 having a plurality of protrusions and having a width larger than the width of the aluminum frame 21. At this time, a hardly conductive material (not shown) is inserted between the aluminum frame 21 and the aluminum plates 23 and 23.
Next, the welded portions of the aluminum plates 23 and 23 are sandwiched between two electrodes (not shown), and a plurality of locations are pressurized and energized for welding.
[0067]
Next, the second aluminum frame 22 is inserted between the projecting portions 23 a and 23 a of the two aluminum plates 23 and 23 and brought into contact with the first aluminum frame 21. At this time, a hardly conductive material is inserted between the aluminum frame 22 and the aluminum plates 23 and 23.
Thereafter, the second aluminum frame 22, the two aluminum plates 23, 23 are sandwiched between the two electrodes, and a plurality of locations are pressurized and energized for welding.
[0068]
【The invention's effect】
According to the resistance welding method of claim 1 , a current concentration member is placed on an aluminum frame having a hollow cross-sectional structure, and a hardly conductive material is placed on the aluminum frame so as to surround the current concentration member. Since the aluminum plate is placed on and energized while pressing the aluminum frame and the aluminum plate with the electrodes, the current concentrates between the current concentration member and the aluminum frame and between the current concentration member and the aluminum plate, It is possible to increase the weld strength. That is, a low current is sufficient to obtain the required welding strength. In addition, even when the second and subsequent points are welded, an ineffective current does not flow due to the action of the hardly conductive material, and the current contributing to welding is unlikely to decrease, and the strength of the welded portion can be increased. That is, a low current is sufficient to obtain the required welding strength after the second hit point.
[0069]
According to the resistance welding method of claim 2 , since the current concentrating member is a small piece of aluminum, the positioning of the welding portion is facilitated, and the number of preparation steps for welding is not large.
[0070]
In the resistance welding method according to the third aspect , since the current concentrating member is a protrusion formed on the aluminum plate or the aluminum frame, it can be easily formed and does not require a large number of preparation steps for welding.
[0071]
In the resistance welding method of claim 4 , since the hardly conductive material is a resin, the resin can be inserted between the aluminum plate and the aluminum frame in the form of a plate or film, ensuring a clearance and enhancing the effect of the hardly conductive material. Efficient welding is possible.
[0072]
In the resistance welding method of claim 5 , since the hardly conductive material is a liquid resin in which metal powder or ceramic powder is kneaded, the metal powder or ceramic powder is sandwiched between the aluminum plate and the aluminum frame. , The clearance can be maintained, the effect of the hardly conductive material is enhanced, and efficient welding becomes possible.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a first embodiment of a resistance welding method according to the present invention. FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. Perspective view showing an embodiment (main part)
4 is a cross-sectional view taken along line 4-4 of FIG. 3. FIG. 5 is a cross-sectional view of a welded portion after resistance welding according to the present invention. FIG. 6 is a graph showing the results of Table 1. FIG. FIG. 8 is a perspective view showing a second embodiment of the resistance welding method according to the present invention. FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 8 (b). Sectional drawing which shows the modification of 2nd Example of the resistance welding method which concerns on FIG. 11 The graph which shows the result of Table 2 FIG. 12 The graph which shows the result of Table 3 FIG. 13 The resistance welding method which concerns on this invention FIG. 14 is a diagram showing a joint construction of an aluminum structure. FIG. 15 is a diagram showing an improved conventional example in which an aluminum plate is resistance welded to an aluminum frame.
DESCRIPTION OF SYMBOLS 1 ... Aluminum frame, 2, 2A ... Aluminum piece (current concentration member) 3,13 ... Aluminum plate, 9, 9A, 9B ... Difficult-conductive material, 13a ... Protrusion (current concentration member).

Claims (5)

A current-concentrating member is placed on an aluminum frame having a hollow cross-sectional structure, a hardly conductive material is placed on the aluminum frame so as to surround the current-concentrating member, and an aluminum plate is placed on the current-concentrating member and the hardly conductive material. A resistance welding method for an aluminum material, wherein electricity is applied while pressing the aluminum plate and the aluminum plate with electrodes. The current concentration member, a method of resistance welding aluminum material according to claim 1 Symbol placement was characterized by an aluminum pieces. The current concentration member, a method of resistance welding according to claim 1 Symbol placement aluminum material was characterized by a protrusion formed on the aluminum plate or an aluminum frame. The resistance welding method for an aluminum material according to claim 1 , wherein the hardly conductive material is a resin. 2. The resistance welding method for an aluminum material according to claim 1 , wherein the hardly conductive material is obtained by kneading metal powder or ceramic powder in a liquid resin.

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