JP4615087B2

JP4615087B2 - Laminated laser welding structure of plated steel sheets

Info

Publication number: JP4615087B2
Application number: JP2000094942A
Authority: JP
Inventors: 聡上田; 耕二富田; 功介河合; 浩島崎
Original assignee: Fuji Jukogyo KK
Current assignee: Subaru Corp
Priority date: 2000-03-30
Filing date: 2000-03-30
Publication date: 2011-01-19
Anticipated expiration: 2020-03-30
Also published as: JP2001276991A

Description

【０００１】
【発明の属する技術分野】
本発明は、自動車の車体等に使用されるめっき鋼板の重ねレーザ溶接構造に関する。
【０００２】
【従来の技術】
従来から自動車用の表面処理鋼板として亜鉛めっき鋼板が用いられているが、亜鉛めっき鋼板は亜鉛の腐食速度が比較的速いため、長時間の防錆効果を期待するには厚目付のめっきが必要となる。
【０００３】
そこで、亜鉛めっき層の活性を抑制するために、鋼板に溶融亜鉛めっきを施した後、合金化処理を行い、Ｆｅ−Ｚｎ相互拡散を行わせて合金層を形成させた合金化溶融亜鉛めっき鋼板が実用化され、広く用いられている。
【０００４】
合金化溶融亜鉛めっき鋼板は、電気めっき鋼板と比較して経済的に付着量を増加させることができるため、厚目付により耐食性を向上させるという対応が容易な鋼板である。
【０００５】
しかし、このような合金化溶融亜鉛めっき鋼板をはじめとする亜鉛系めっき鋼板を重ねた状態でレーザ溶接した場合、接合面間のめっき層から多量の亜鉛蒸気が発生し、この蒸気ガスが溶融金属内に閉じ込められること等に起因して、ビード内にブローホールやビード表面がへこんだり或いはビードを貫通する欠陥（ピットと呼ばれる欠陥）が多数発生し、ビードの荒れが悪化することが知られている。
【０００６】
そのため、めっき鋼板の接合面間にガス排出路を形成した状態で重ねレーザ溶接を行う技術が種々試みられており、例えば特開平１１−２２６７６５号公報には、めっき鋼板の接合面にブラスト加工を用いて凹凸を形成し、この凹凸によりガス排出路を形成し、このガス出路を通して重ねレーザ溶接の際に発生する成分蒸発ガスを外部へ逃がす技術が開示されている。
【０００７】
【発明が解決しようとする課題】
しかし、接合面間に形成するガス排出路の離間距離は、重ねレーザ溶接の際に厳しく管理する必要がある。
【０００８】
すなわち、接合面間の離間距離が狭すぎると、溶接部分が凝固する前にガスを完全に逃がすことができなくなり、上述したような溶接不良が発生する。又、この離間距離が広すぎた場合には、ガス排出路に溶融金属が流れ込み、レーザ光が照射される側のめっき鋼板が溶断されてしまう等の不都合が生じる。
【０００９】
そのため、重ねレーザ溶接の際には、特別な治具等を用いて、接合面間の離間距離を厳しく管理しなければならず、作業工数が嵩み、生産効率の低下を招く不都合がある。
【００１０】
本発明は、上記事情に鑑み、簡単な構造で、接合面間に形成するガス排出路の離間距離を常に一定に保持した状態でレーザ溶接を行うことが可能で、生産効率の向上を図ることのできるめっき鋼板の重ねレーザ溶接構造を提供することを目的とする。
【００１７】
【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によるめっき鋼板の重ねレーザ溶接構造は、互いに対向するめっき鋼板をレーザ溶接するめっき鋼板の重ねレーザ溶接構造において、一方のめっき鋼板に接合面を曲げ形成し、上記接合面の端縁に他方のめっき鋼板に当接する突出部を形成し、上記接合面を上記他方のめっき鋼板に当接したとき、上記突出部と該接合面の付け根部とで断面三角形状のガス排出路を形成すると共に、上記突出部と上記付け根部との間の、上記ガス排出路に面する2枚のめっき鋼板間の離間距離が設定値となる位置に溶接線を設定することを特徴とする。
【００１８】
このような構成では、一方のめっき鋼板に曲げ形成した接合面を他方のめっき鋼板に当接すると、この接合面の付け根部と端縁に形成された突出部とで、接合面と他方のめっき鋼板との間に断面三角形状のガス排出路が形成され、又、接合面の付け根部と突出部との間の、離間距離が設定値となる位置に溶接線を設定することで、適切な離間距離を維持した状態で重ねレーザ溶接を行うことができる。
【００２１】
【発明の実施の形態】
以下、図面に基づいて本発明の一実施の形態を説明する。図１、図２に第１参考例を示す。ここで、図１は重ねレーザ溶接装置の溶接ヘッド部の拡大図、図２はめっき鋼板の接合面の拡大断面図である。
【００２２】
図中の符号１は溶接ヘッドで、この溶接ヘッド１にローラアーム２が固設され、このローラアーム２に、レーザ照射部の傍らを押圧するプレッシャローラ３が枢支されている。
【００２３】
溶接ヘッド１は、図示しないロボットアーム等に連設されており、このロボットアームの動作により、重ね合せた２枚のめっき鋼板４，５の溶接線Ｌｗ上を移動し、その際、溶接ヘッド１から照射されるレーザ光により、２枚のめっき鋼板４，５を連続線溶接する。
【００２４】
図２に示すように、両めっき鋼板４，５の接合面４ａ，５ａには、離間距離ｇのガス排出路６が形成されている。このガス排出路６は、上側のめっき鋼板４の溶接線Ｌｗ上に、所定間隔を置いて形成した下側のめっき鋼板５の方向へ突出形成したエンボス（突出部）７によって確保されているもので、離間距離ｇは、本参考例では、0.2±0.1mmに設定されている。
【００２５】
このエンボス７は、少なくともめっき鋼板４の溶接線Ｌｗ上の両端に形成されており、溶接長が長い場合は、接合面４ａ，５ａ部分の板厚を考慮して適宜設定する。
【００２６】
このような構成では、プレス加工などにより所定形状に加工された２枚のめっき鋼板４，５の接合面４ａ，５ａを重ね合わせ、溶接ヘッド１を溶接線Ｌｗに沿い、その傍らをプレッシャローラ３にて圧接しながら移動させ、その際、溶接ヘッド１から出射されるレーザ光を、溶接線Ｌｗ上に照射して連続線溶接を行う。
【００２７】
このとき、接合面４ａ，５ａ間の亜鉛等からなるめっき層から発生した成分蒸発ガスは、ガス排出路６から外部に放出される。従って、重ねレーザ溶接により溶接線Ｌｗ上に形成されるビード中に成分蒸発ガスが残留せず、ブローホールやビット等の溶接不良が未然に回避される。
【００２８】
又、ガス排出路６の離間距離ｇの精度を、めっき鋼板４に形成したエンボス７の突出量で確保するようにしたので、離間距離ｇの管理が容易となり、離間距離ｇ（本参考例では、0.2±0.1mm）を維持した状態で溶接を行うことができ、溶接品質を損なうことなく、生産効率の向上を図ることができる。
【００２９】
尚、この場合、図３に示すように、エンボス（突出部）７を、下側のめっき鋼板５の接合面５ａの溶接線Ｌｗ上に、上側のめっき鋼板４の接合面４ａ方向へ突出するように形成しても、上述と同様の作用効果を得ることができる。
【００３０】
又、図４に第２参考例によるめっき鋼板の接合面の拡大断面図を示す。
【００３１】
本参考例では、下側のめっき鋼板５の接合面５ａに、離間距離ｇ（本参考例では、0.2±0.1mm）の段差部８を曲げ形成し、この段差部８によりガス排出路６を確保するようにし、このガス排出路６と上に溶接線Ｌｗを設定するようにしたものである。尚、段差部８は、溶接線Ｌｗと平行に連続形成されている。
【００３２】
そして、同図に示すように、両めっき鋼板４，５の接合面４ａ，５ａを重ね合わせ、その接合部分をプレッシャローラ３で加圧しながら、ガス排出路６上に設定した溶接線Ｌｗに沿って、溶接ヘッド１を移動させながら、レーザ光により連続線溶接を行う。
【００３３】
その際、接合面４ａ，５ａ間のめっき層から発生した成分蒸発ガスは、ガス排出路６から外部に放出されるため、第１参考例と同様、ビード中に成分蒸発ガスが残留せず、ブローホールやビット等の溶接不良の発生を未然に回避することができる。
【００３４】
又、ガス排出路６を段差部８により確保するようにしたので、この段差部８を曲げ形成したときの加工硬化により剛性が高められ、離間距離ｇを一定の状態に保持したまま溶接を行うことができ、より高い溶接品質を得ることができる。尚、段差部８は上側のめっき鋼板４に形成しても、同様の作用効果を得ることができる。
【００３５】
又、図５に本発明の第１実施の形態によるめっき鋼板の接合面の拡大断面図を示す。
【００３６】
本実施の形態では、上側のめっき鋼板４に接合面４ａを曲げ形成し、その端縁に、下側のめっき鋼板５の接合面５ａ側へ突出する突出部９を形成したもので、この突出部９は溶接線Ｌｗに平行して所定離間距離毎に形成されている。
【００３７】
この上側のめっき鋼板４に形成した接合面４ａを、下側のめっき鋼板５に設けた接合面５ａに当接すると、接合面４ａは、その端縁に形成した突出部９と付け根部４ｂとで傾斜された状態となり、この傾斜面により、両接合面４ａ，５ａ間に、断面三角形状のガス排出路６が形成される。
【００３８】
このときの溶接線Ｌｗは、接合面５ａ側の、付け根部４ｂと突出部９とが接触している部位の距離をＸ、突出部９の高さをｈとした場合、ガス排出路６の離間距離ｇが設定値（本実施の形態では、0.2±0.1mm）となる位置に配設する。
【００３９】
そして、プレッシャローラ３に、溶接線Ｌｗを逃げる凹溝３ａを形成し、その両縁を、突出部９と付け根部４ｂとに押し付けて加圧可能な形状とする。
【００４０】
このような構成では、両めっき鋼板４，５の接合面４ａ，５ａを当接すると、接合面４ａは、その端縁に形成した突出部９と付け根部４ｂとで、他方の接合面５ａに対して傾斜された状態となり、接合面４ａ，５ａ間に、断面三角形状のガス排出路６が形成される。
【００４１】
そして、ガス排出路６の離間距離ｇが設定値（本実施の形態では、0.2±0.1mm）となる位置に配設されている溶接線Ｌｗに沿って、溶接ヘッド１（図１参照）を移動させると共に、その前方或いは後方をプレッシャローラ３で加圧しながら連続線溶接を行う。
【００４２】
このとき、接合面４ａ，５ａ間のめっき層から発生した成分蒸発ガスは、主に突出部９側から外部へ放出され、第１参考例と同様の作用効果を得ることができる。
【００４９】
【発明の効果】
以上、説明したように、本発明によれば、２枚のめっき鋼板間の溶接線に近接する部位に、両めっき鋼板の少なくとも一方を離間させてガス排出路を設けたので、重ねレーザ溶接の際に、接合面間のめっき層から発生する成分蒸発ガスはガス排出路を通って外部へ放出されるため、ビード中に成分蒸発ガスが残留せず、常に安定した溶接品質を得ることができる。
【００５０】
この場合、ガス排出路を、２枚のめっき鋼板の一方に突出形成した突出部を他方のめっき鋼板に当接させることで確保し、或いは２枚のめっき鋼板の一方に形成した段差部により確保することで、特別な治具等を用いることなく、簡単な構造で、ガス抜き用離間距離を常に一定に保持した状態で重ねレーザ溶接を行うことが可能となり、生産効率の向上を図ることができる。
【図面の簡単な説明】
【図１】第１参考例による重ねレーザ溶接装置の溶接ヘッド部の拡大図
【図２】同、めっき鋼板の接合面の拡大断面図
【図３】同、他の態様によるめっき鋼板の接合面の拡大断面図
【図４】第２参考例によるめっき鋼板の接合面の拡大断面図
【図５】第１実施の形態によるめっき鋼板の接合面の拡大断面図[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lap laser welding structure of plated steel sheets used for automobile bodies and the like.
[0002]
[Prior art]
Conventionally, galvanized steel sheets have been used as surface-treated steel sheets for automobiles. However, galvanized steel sheets have a relatively high corrosion rate of zinc, so they must be plated with a thick surface in order to expect a long-term rust prevention effect. It becomes.
[0003]
Therefore, in order to suppress the activity of the galvanized layer, the galvanized steel sheet is subjected to galvanizing, then alloyed, and Fe-Zn interdiffusion is performed to form an alloy layer. Has been put into practical use and widely used.
[0004]
An alloyed hot-dip galvanized steel sheet can increase the amount of adhesion economically as compared with an electroplated steel sheet, and is therefore a steel sheet that can be easily coped with by improving the corrosion resistance due to thickness.
[0005]
However, when laser welding is performed with a galvanized steel sheet such as an alloyed hot-dip galvanized steel sheet piled up, a large amount of zinc vapor is generated from the plated layer between the joint surfaces, and this vapor gas is generated by the molten metal. It is known that blow holes and bead surfaces are dented in the bead or a lot of defects (defects called pits) occur in the bead due to being confined in the bead, and the roughness of the bead deteriorates. Yes.
[0006]
For this reason, various techniques for performing laser welding in a state where a gas discharge path is formed between the joining surfaces of the plated steel sheets have been tried. For example, Japanese Patent Application Laid-Open No. 11-226765 discloses blasting on the joining surfaces of the plated steel sheets. There is disclosed a technique in which irregularities are formed by using the irregularities, a gas discharge path is formed by the irregularities, and component vapors generated during laser welding are overlapped through the gas outlet path.
[0007]
[Problems to be solved by the invention]
However, it is necessary to strictly manage the separation distance of the gas discharge path formed between the joining surfaces in the overlap laser welding.
[0008]
That is, if the distance between the joint surfaces is too small, the gas cannot be completely released before the welded portion is solidified, and the above-described poor welding occurs. Moreover, when this separation distance is too wide, the molten metal flows into the gas discharge path, and inconveniences such as melting of the plated steel sheet on the side irradiated with the laser beam occur.
[0009]
For this reason, in the overlap laser welding, a special jig or the like must be used to strictly manage the separation distance between the joining surfaces, which increases the work man-hours and causes a reduction in production efficiency.
[0010]
In view of the above circumstances, the present invention is capable of performing laser welding with a simple structure and keeping the separation distance of the gas discharge passage formed between the joining surfaces constant at all times, thereby improving the production efficiency. An object of the present invention is to provide a lap laser welding structure of plated steel sheets that can be manufactured.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, a lap laser welding structure of plated steel sheets according to the present invention is a lap laser welding structure of plated steel sheets in which plated steel sheets facing each other are laser welded. A protrusion having an abutting contact with the other plated steel sheet is formed at the edge of the surface, and when the joining surface is in contact with the other plated steel sheet, a gas having a triangular cross section is formed between the projecting part and the base of the joining surface. A discharge line is formed, and a welding line is set at a position where a separation distance between the two plated steel sheets facing the gas discharge path becomes a set value between the protruding portion and the base portion. And
[0018]
In such a configuration, when the joint surface formed by bending one plated steel plate is brought into contact with the other plated steel plate, the joint surface and the other plating are formed at the base portion of the joint surface and the protrusion formed at the edge. A gas discharge passage having a triangular cross section is formed between the steel plate and the welding line is set at a position where the separation distance between the base portion of the joint surface and the protruding portion becomes a set value. Overlapping laser welding can be performed while maintaining the separation distance.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 and 2 show a first reference example . Here, FIG. 1 is an enlarged view of the welding head portion of the lap laser welding apparatus, and FIG. 2 is an enlarged cross-sectional view of the joint surface of the plated steel sheet.
[0022]
Reference numeral 1 in the drawing denotes a welding head. A roller arm 2 is fixed to the welding head 1, and a pressure roller 3 that presses the side of the laser irradiation unit is pivotally supported on the roller arm 2.
[0023]
The welding head 1 is connected to a robot arm or the like (not shown), and moves on the welding line Lw between the two plated steel plates 4 and 5 by the operation of the robot arm. The two plated steel plates 4 and 5 are continuously wire-welded by the laser beam irradiated from.
[0024]
As shown in FIG. 2, gas discharge paths 6 having a separation distance g are formed on the joint surfaces 4 a and 5 a of both plated steel plates 4 and 5. The gas discharge path 6 is secured by an emboss (projection) 7 that is formed on the weld line Lw of the upper plated steel plate 4 so as to project toward the lower plated steel plate 5 formed at a predetermined interval. In this reference example , the separation distance g is set to 0.2 ± 0.1 mm.
[0025]
This emboss 7 is formed at least at both ends on the weld line Lw of the plated steel plate 4 and is appropriately set in consideration of the plate thickness of the joint surfaces 4a and 5a when the weld length is long.
[0026]
In such a configuration, the joining surfaces 4a and 5a of the two plated steel plates 4 and 5 processed into a predetermined shape by press working or the like are overlapped, the welding head 1 is along the welding line Lw, and the pressure roller 3 is on the side. In this case, the laser beam emitted from the welding head 1 is irradiated onto the welding line Lw to perform continuous line welding.
[0027]
At this time, the component evaporating gas generated from the plating layer made of zinc or the like between the joint surfaces 4a and 5a is discharged to the outside from the gas discharge path 6. Therefore, the component evaporative gas does not remain in the bead formed on the weld line Lw by the overlap laser welding, and welding defects such as blow holes and bits are avoided in advance.
[0028]
In addition, since the accuracy of the separation distance g of the gas discharge path 6 is ensured by the protruding amount of the emboss 7 formed on the plated steel plate 4, the separation distance g can be easily managed, and the separation distance g (in this reference example) , 0.2 ± 0.1 mm) can be maintained, and the production efficiency can be improved without impairing the welding quality.
[0029]
In this case, as shown in FIG. 3, the embossing (protruding portion) 7 protrudes in the direction of the joint surface 4 a of the upper plated steel plate 4 on the weld line Lw of the joint surface 5 a of the lower plated steel plate 5. Even if it forms in this way, the effect similar to the above-mentioned can be acquired.
[0030]
FIG. 4 shows an enlarged cross-sectional view of the joint surface of the plated steel sheet according to the second reference example .
[0031]
In this reference example , a stepped portion 8 having a separation distance g (0.2 ± 0.1 mm in the present reference example ) is bent on the joint surface 5a of the lower plated steel plate 5, and the gas discharge path 6 is formed by this stepped portion 8. The welding line Lw is set on the gas discharge path 6 and above. The step 8 is continuously formed in parallel with the weld line Lw.
[0032]
Then, as shown in the figure, the joining surfaces 4a and 5a of the plated steel plates 4 and 5 are overlapped, and the joining portion is pressed by the pressure roller 3 along the welding line Lw set on the gas discharge path 6. Then, while moving the welding head 1, continuous line welding is performed with a laser beam.
[0033]
At that time, the component evaporating gas generated from the plating layer between the joint surfaces 4a and 5a is released to the outside from the gas discharge path 6, so that the component evaporating gas does not remain in the bead as in the first reference example . Occurrence of poor welding such as blow holes and bits can be avoided in advance.
[0034]
Further, since the gas discharge path 6 is secured by the stepped portion 8, the rigidity is increased by work hardening when the stepped portion 8 is bent, and welding is performed while the separation distance g is kept constant. And higher weld quality can be obtained. Even if the stepped portion 8 is formed on the upper plated steel plate 4, the same effect can be obtained.
[0035]
FIG. 5 shows an enlarged cross-sectional view of the joint surface of the plated steel sheets according to the first embodiment of the present invention.
[0036]
In the present embodiment, the joining surface 4a is bent and formed on the upper plated steel sheet 4, and the projecting portion 9 projecting toward the joining surface 5a side of the lower plated steel sheet 5 is formed on the edge thereof. The portions 9 are formed at predetermined spacing distances in parallel with the weld line Lw.
[0037]
When the bonding surface 4a formed on the upper plated steel plate 4 is brought into contact with the bonding surface 5a provided on the lower plated steel plate 5, the bonding surface 4a is formed with a protruding portion 9 and a root portion 4b formed on the edge thereof. The gas discharge path 6 having a triangular cross section is formed between the joint surfaces 4a and 5a.
[0038]
The welding line Lw at this time is X of the distance of the part where the base portion 4b and the protruding portion 9 are in contact with each other on the joining surface 5a side, and the height of the protruding portion 9 is h. It is disposed at a position where the separation distance g is a set value (in this embodiment, 0.2 ± 0.1 mm).
[0039]
Then, a concave groove 3a that escapes the weld line Lw is formed in the pressure roller 3, and both edges thereof are pressed against the protruding portion 9 and the root portion 4b so as to have a shape that can be pressurized.
[0040]
In such a configuration, when the joining surfaces 4a and 5a of the both plated steel plates 4 and 5 are brought into contact with each other, the joining surface 4a is formed on the other joining surface 5a by the protruding portion 9 and the base portion 4b formed on the edge thereof. The gas discharge path 6 having a triangular cross section is formed between the joint surfaces 4a and 5a.
[0041]
Then, the welding head 1 (see FIG. 1) is moved along the welding line Lw disposed at a position where the separation distance g of the gas discharge path 6 becomes a set value (in this embodiment, 0.2 ± 0.1 mm). While moving, continuous wire welding is performed while pressing the front or rear with the pressure roller 3.
[0042]
At this time, the component evaporating gas generated from the plating layer between the joint surfaces 4a and 5a is released mainly from the protruding portion 9 side to the outside, and the same effect as the first reference example can be obtained.
[0049]
【The invention's effect】
As described above, according to the present invention, since the gas discharge path is provided by separating at least one of the two plated steel plates at a site close to the weld line between the two plated steel plates, the overlap laser welding is performed. At this time, the component evaporative gas generated from the plating layer between the joining surfaces is released to the outside through the gas discharge path, so that the component evaporative gas does not remain in the bead, and a stable welding quality can always be obtained. .
[0050]
In this case, the gas discharge path is secured by bringing the protruding portion formed on one of the two plated steel plates into contact with the other plated steel plate, or secured by the stepped portion formed on one of the two plated steel plates. By doing so, it is possible to perform overlap laser welding with a simple structure and a constant degassing separation distance without using a special jig or the like, thereby improving production efficiency. it can.
[Brief description of the drawings]
FIG. 1 is an enlarged view of a welding head portion of a lap laser welding apparatus according to a first reference example . FIG. 2 is an enlarged cross-sectional view of a joint surface of a plated steel plate. FIG. 3 is a joint surface of a plated steel plate according to another embodiment. Fig. 4 is an enlarged cross-sectional view of the joint surface of the plated steel plate according to the second reference example . Fig. 5 is an enlarged cross-sectional view of the joint surface of the plated steel plate according to the first embodiment.

Claims

In the lap laser welding structure of plated steel plates for laser welding the plated steel plates facing each other,
Bending the joint surface on one plated steel sheet,
Forming a projecting part that contacts the other plated steel plate at the edge of the joint surface,
When the joint surface is brought into contact with the other plated steel sheet, a gas discharge passage having a triangular cross section is formed by the projecting portion and the base portion of the joint surface,
A lap laser for plated steel sheets, characterized in that a welding line is set at a position where a distance between the two plated steel sheets facing the gas discharge path between the projecting part and the base part becomes a set value. Welded structure.