JP4334725B2 - Laminated laser welding structure of plated steel sheets - Google Patents

Description

[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, the separation distance between the joint surfaces of the gas discharge path needs to be strictly controlled during the overlap laser welding.
[0008]
That is, if the separation distance between the joining surfaces is too narrow, the component evaporation 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]
Therefore, in the overlap laser welding, it is necessary to strictly manage the separation distance between the joint surfaces, which increases the work man-hours and causes the disadvantage of reducing the production efficiency.
[0010]
In view of the above circumstances, the present invention is capable of carrying out overlap laser welding with a simple structure and constantly maintaining the separation distance of the gas discharge path formed between the joining surfaces, thereby improving the production efficiency. An object of the present invention is to provide a lap laser welding structure of plated steel sheets.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a lap laser welding structure of a first plated steel sheet according to the present invention is a lap laser welding structure of plated steel sheets that laser welds opposed plated steel sheets, and is close to the weld line between the two plated steel sheets. A gas discharge path is provided by sandwiching an adhesive material having elastic force at the position, and the adhesive material is affixed to both sides of the weld line between the two plated steel sheets , and the separation distance of the gas discharge path is the pressure of the pressure roller. It is characterized by being adjusted so as to become a set height.
[0012]
In such a configuration, when two plated steel sheets are overlapped and laser welding is performed , an adhesive having elastic force is sandwiched between the two plated steel sheets to form a gas discharge path, thereby forming a gap between the plated steel sheets. The component evaporative gas generated from the formed plating layer is released to the outside through the gas discharge path.
[0014]
In addition, an adhesive material is attached to both sides of the two plated steel sheets with the weld line interposed therebetween to form a gas discharge path, and the weld line is overlap-welded with laser light while being pressurized by a pressure roller. At this time, the gas discharge path can be set to an appropriate value by adjusting the pressure force of the pressure roller so that the separation distance of the gas discharge path becomes the set height.
[0015]
In the overlap laser welding structure of the second plated steel sheet, in the overlap laser welding of the first plated steel sheet, the adhesive material is wound in a roll shape with a predetermined interval between them, On the other hand, it is pasted in a state of straddling the weld line.
[0016]
In such a configuration, the adhesive material can be automatically mounted between the two plated steel plates when the overlap laser welding is performed by winding the adhesive material in a roll shape with a predetermined interval therebetween. Production efficiency is improved.
[0019]
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 embodiment of the present invention. 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.
[0020]
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.
[0021]
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.
[0022]
As shown in FIG. 2, the pressure roller 3 is pressed against the end of the joint surface 4a of the upper plated steel plate 4, and the pressure roller 3 is sandwiched between the joint surfaces 4a and 5a on the opposite side across the weld line Lw. A flat spacer 7 as an example of an insert is interposed.
[0023]
When the end of the joint surface 4a is pressed by the pressure roller 3, the joint surface 4a is inclined by the spacer 7, and a gas discharge path 6 having a triangular cross section is formed between the joint surfaces 4a and 5a.
[0024]
The insertion position of the spacer 7 and the plate thickness thereof are set in advance so that the separation distance g of the gas discharge path 6 on the welding line Lw becomes an appropriate value (0.1 to 0.4 mm in the present embodiment).
[0025]
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, and the spacer 7 is placed at a predetermined position between the both joining surfaces 4a and 5a. Interpose.
[0026]
Then, when the pressure roller 3 is pressed against the end portion side of the joining surface 4a of the upper plated steel sheet 4, the joining surface 4a is inclined as shown in FIG. 2, and the section between the joining surfaces 4a and 5a has a triangular shape. A gas discharge path 6 is formed.
[0027]
Then, the welding head 1 is moved along the welding line Lw while the pressure roller 3 presses the joint surfaces 4a and 5a, and at that time, the laser beam emitted from the welding head 1 is irradiated onto the welding line Lw. Then, continuous wire welding is performed.
[0028]
At this time, since the separation distance g of the gas discharge path 6 located at the welding line Lw is set in advance to a predetermined value depending on the thickness of the spacer 7 and the mounting position, the separation distance g is maintained in an appropriate dimension. Overlapping laser welding can be performed, and the component evaporating gas generated from the plating layer made of zinc or the like generated between the joining surfaces 4a and 5a is released to the outside from the gas discharge path 6, and the component evaporating gas is generated in the bead. It does not remain, and it is possible to avoid the occurrence of poor welding such as blow holes and bits.
[0029]
As described above, in the present embodiment, the separation distance g on the welding line Lw of the gas discharge path 6 is set in advance by the mounting position and the plate thickness of the spacer 7, so that the management of the separation distance g is facilitated and welding is performed. Production efficiency can be improved without losing quality.
[0030]
The spacer 7 may be interposed between the joint surfaces 4a and 5a continuously or intermittently.
[0031]
3 to 5 show a second embodiment of the present invention. Here, FIG. 3 is a perspective view of the joint portion of the plated steel sheet, FIG. 4 is a cross-sectional view of the joint portion of the plated steel sheet, and FIG. 5 is a perspective view of the roll-shaped adhesive tape.
[0032]
In the present embodiment, the adhesive material 11 is used as an insert, and the adhesive material 11 is used to maintain the separation distance g of the gas discharge path 6 at the time of overlap laser welding.
[0033]
As shown in FIG. 5, adhesive materials 11 arranged in two rows at a predetermined interval are affixed to the release paper 13 of the roll-shaped adhesive tape 12. Each of the adhesive materials 11 has a three-layer structure of a core material and adhesive layers formed on the upper and lower surfaces of the core material, and has a certain degree of elasticity. The bonding surfaces 4a and 5a of the plated steel plates 4 and 5 are provided. When the pressure roller is interposed, the separation distance g of the gas discharge path 6 is set to an appropriate value (0.1 to 0.4 m in the present embodiment) by adjusting the pressure applied by the pressure roller.
[0034]
In the welding process, first, of the two plated steel plates 4 and 5 processed into a predetermined shape, a roll-shaped adhesive is formed on both sides of the lower surface of the plated steel plate 5 across the weld line Lw. The adhesive material 11 attached to the tape 12 is attached while being peeled from the release paper 13.
[0035]
Next, the bonding surface 5a of the upper plated steel plate 5 is overlaid on the bonding surface 5a, and the adhesive material 11 is pressed against the pressure-sensitive adhesive material 11 by a pair of pressure rollers 14 and 14, respectively. The welding head 1 (see FIG. 1) is moved along the welding line Lw in a state set to an appropriate value (in this embodiment, 0.1 to 0.4 m) by adjusting the pressure of the roller, and this welding is performed. Continuous line welding is performed by laser light emitted from the head 1.
[0036]
At this time, the component evaporating gas generated in the plating layer between the joining 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 embodiment. The occurrence of poor welding such as blow holes and bits can be avoided.
[0037]
Further, since the gas discharge path 6 is secured by the adhesive material 11, it is not necessary to perform extra processing for forming the gas discharge path 6 on the plated steel plates 4 and 5, and the press work is facilitated. . Further, since the adhesive material 11 is applied to the joining surface 5a while being peeled off from the roll adhesive tape 12, the process of applying the adhesive material 11 can be automated, and the production efficiency is improved.
[0038]
Further, by giving the adhesive material 11 a certain degree of elasticity, the separation distance g of the gas discharge path 6 can be set to an optimum value by adjusting the pressure applied by the pressure roller 3. It is not necessary to strictly manage the thickness of the adhesive material, and the cost of the adhesive material 11 can be reduced.
[0039]
FIG. 6 shows an enlarged cross-sectional view of the joint surface of the plated steel sheets according to the third embodiment of the present invention.
[0040]
In the present embodiment, when the joining surfaces 4a and 5a of the plated steel plates 4 and 5 are overlapped, a pair of L-shaped brackets 15 as an example of a separating member from the end side between the joining surfaces 4a and 5a, 16, when the overlap laser welding is performed, first, the base side of the joint surfaces 4a and 5a is pressurized by the pressure roller 3, and then the pair of brackets 15 and 16 are lifted away from each other in a direction away from each other. Move through etc.
[0041]
Then, the space between the joint surfaces 4a and 5a is expanded to form the gas discharge path 6, and the joint surfaces 4a and 5a are pressed against the brackets 15 and 16 by their own resilience, so that laser light is irradiated. The separation distance g of the welding line Lw to be fixed is fixed.
[0042]
In this case, the separation width of the brackets 15 and 16 is set in advance to a position where the separation distance g is an appropriate value (0.1 to 0.4 m in the present embodiment).
[0043]
Thereafter, while applying pressure with the pressure roller 3, the laser welding is performed along the welding line Lw. At this time, the component evaporating gas generated in the plating layer between the joining 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 embodiment. The occurrence of poor welding such as blow holes and bits can be avoided.
[0044]
Then, after the overlap laser welding is completed in a predetermined manner, the pair of brackets 15 and 16 are removed from between the joint surfaces 4a and 5a.
[0045]
As described above, in the present embodiment, the gas discharge path 6 is formed by expanding the joint surfaces 4a and 5a by the pair of brackets 15 and 16, so that the brackets 15 and 16 are brackets with their own elastic force. Since it is pressed against 15 and 16, the separation distance g on the welding line Lw can be kept constant.
[0046]
【The invention's effect】
As described above, according to the present invention, when two plated steel sheets are overlapped and laser welding is performed, an insert is sandwiched between the two plated steel sheets to form a gas discharge path, Since the component evaporative gas generated in the plating layer formed on the metal is discharged to the outside through the gas discharge path, the component evaporative gas does not remain in the bead, and stable welding quality can always be obtained.
[0047]
Further, by inserting an insert between the joining surfaces, it becomes possible to perform overlap laser welding in a state in which the gas discharge path is always kept constant, so that the production efficiency can be improved. In addition, since it is not necessary to perform any processing for forming a gas discharge path on the plated steel sheet, the structure can be simplified.
[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 embodiment. FIG. 2 is an enlarged cross-sectional view of a joint surface of a plated steel sheet. FIG. 3 is a joint of a plated steel sheet according to a second embodiment. Fig. 4 is a cross-sectional view of a bonded portion of a plated steel sheet. Fig. 5 is a perspective view of a rolled adhesive tape. Fig. 6 is an enlarged cross-sectional view of a bonded surface of a plated steel plate according to a third embodiment. [Explanation of symbols]
3, 14 Pressure roller 4, 5 Plated steel plate 4a, 5a Joint surface 6 Gas discharge path 7 Spacer (insert)
11 Adhesive (insert)
12 Roll adhesive tapes 15 and 16 Bracket (insert)
g Separation distance Lw Welding line

Claims (2)

In the lap laser welding structure of plated steel plates for laser welding the plated steel plates facing each other,
A gas discharge path is provided by sandwiching an adhesive material having elasticity at a position close to the weld line between the two plated steel sheets,
While the adhesive material is affixed to both sides of the weld line between the two plated steel plates,
A lap laser welding structure for plated steel sheets, wherein the separation distance of the gas discharge path is adjusted to a set height by pressurization of a pressure roller. The pressure-sensitive adhesive material is wound in a roll with a set interval in advance,
The lap laser welding structure for plated steel sheets according to claim 1, wherein the welded steel sheet is attached to one of the two plated steel sheets in a state of straddling the weld line.

Images