JP2010094701A - Method of laser welding metal plated plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of laser welding a metal plated plate, in which successful welding is surely attained without any melting defect such as blowholes. <P>SOLUTION: A lower plate 11 and an upper plate 12 are superposed on each other. First laser beam 18a is moved along first to third straight paths K1-K3 on a superposed section and zinc present in a superposed surface of the lower plate 11 and the upper plate 12 corresponding to a wide application area 19a of the first laser beam 18a is evaporated and allowed to escape outside. Then, the second laser beam 18b having the energy density higher than that of the first laser beam 18a and having an application area 19b narrower than that of the first laser beam is applied while being moved along the second straight path K2. Welding and bonding are completed by melting steel plate portions of the lower plate 11 and the upper plate 12 corresponding to the narrow application area 19b. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for laser welding an overlapping portion of a plurality of metal plated plates.

  A galvanized steel sheet is a steel sheet material in which the surface of a steel sheet, which is a base metal sheet, is galvanized for rust prevention, and is often used as a structural material for automobile bodies. In the case of forming a vehicle body or the like, a laser welding method is known in which two galvanized steel plates are overlapped and a laser beam is irradiated to the overlapped portion to melt and bond the steel plate materials. (See Patent Documents 1-3)

When the laser welding is performed, it is known that welding defects occur due to the boiling point of zinc (about 900 ° C.) being lower than the melting point of steel plate (iron) (about 1500 ° C.). That is, by irradiating the overlapped portion with a laser beam, the steel sheet is melted, but at this time, zinc on the overlapped surface evaporates. And, zinc vapor tends to escape outside through the molten steel sheet. As a result, a part of the molten steel sheet is blown away, or a part of the zinc vapor remains inside the steel sheet, forming pores called blow holes, deteriorating the welding strength or worsening the appearance.

From such a viewpoint, various countermeasures have been proposed in the laser welding method for galvanized steel sheets. (See Patent Documents 1-3) For example, Patent Document 1 describes a method in which zinc is evaporated and dispersed with a laser beam having a low energy density and then welded with a laser beam having a high energy density. In the method of Patent Document 1, one laser beam is divided into a laser beam having a low energy density and a laser beam having a high energy density by using a half mirror and a reflecting mirror, and these two laser beams are divided into two. The irradiation area is shifted and irradiation is performed simultaneously. (See, for example, FIG. 8 of Patent Document 1)
JP-A-4-231190 JP-A-10-156666 JP 2002-178178 A

  However, the welding method disclosed in Patent Document 1 has the following problems because the laser beam having a low energy density and the laser beam having a high energy density are simultaneously irradiated.

  First, the moving speeds of the two laser beams must be the same, and this is a problem in optimizing the two processes of zinc evaporation and welding. is there. Secondly, if the path to be welded is a curve, the two split laser beam emission positions are different, so that the path is likely to be displaced, and if the path is displaced, welding defects such as deterioration of the welding strength are caused. There is a problem of inviting.

  According to the first aspect of the present invention, a plurality of metal plated plates, which are obtained by plating a surface of a base metal plate with a metal having a boiling point lower than the melting point of the base metal, are overlapped, and a laser beam is applied to the overlap portion. In the laser welding method of a metal plated plate for performing welding by irradiating with a first energy line having a low energy density and a wide irradiation region along the first to third paths adjacent to each other on the overlapping portion. By irradiating while moving the laser beam, the metal plated on the base metal portion in the wide irradiation region is evaporated and degassed, and the first laser beam is passed along the first to third paths. After irradiation, the energy density is higher than that of the first laser beam along the second path sandwiched between the first and third paths, and is narrower than that of the first laser beam. By irradiating while moving the second laser beam having a region, to melt the base metal portion of the narrow irradiation region, characterized thereby welded.

  According to the above configuration, since the second laser beam is irradiated after the first laser beam is irradiated, the moving speeds of the first and second laser beam lines can be controlled independently. As a result, optimization of welding conditions is facilitated. In addition, it is possible to eliminate the shift of the travel path of the first and second laser beams.

  In addition, after the first laser beam is irradiated along the first to third paths, the second laser beam is irradiated along the second path sandwiched between the first and third paths. Therefore, when the second laser beam is irradiated, the metal plated in a wide range including both sides of the second path has already been evaporated and degassed. Thereby, the influence of metal vapor can be eliminated and a better welding can be realized. Here, the first to third paths may be linear paths or circumferential paths.

  According to a fourth aspect of the present invention, a plurality of metal plated plates are formed by plating a metal having a boiling point lower than the melting point of the base metal on the surface of the base metal plate, and the overlap portion is formed. In the laser welding method of a metal plating plate for performing welding by irradiating a laser beam, the first laser beam having a low energy density and a wide irradiation area is moved along the spiral path on the overlapping portion. The metal plated on the base metal portion of the wide irradiation area is evaporated by irradiating the first laser beam along the entire spiral path, and then the both sides in the spiral path. The energy density of the region is higher than that of the first laser beam along the path where the first laser beam is irradiated to the region, and the region is higher than that of the first laser beam. By irradiating while moving the second laser beam having a narrow irradiation area, melting the parent metal portion of the narrow irradiation region, characterized thereby welded.

  According to the present invention, since the second laser beam is irradiated after the first laser beam is irradiated as in the first aspect of the invention, the moving speeds of the first and second laser beam lines can be set independently. Can be controlled, and as a result, optimization of welding conditions is facilitated. In addition, it is possible to eliminate the shift of the travel path of the first and second laser beams. Furthermore, since the first laser beam is irradiated along the spiral path, the laser beam can be continuously irradiated, and productivity can be improved. Further, at the time of irradiation with the second laser beam, the metal plated in a wide range including both sides of the irradiation path has already been evaporated and degassed. Thereby, like the invention which concerns on Claim 1, the influence of a metal vapor | steam can be eliminated and still better welding can be implement | achieved.

  According to the laser welding method of the metal plated plate of the present invention, optimization of welding conditions is facilitated, and there is no formation of melt defects such as blow holes even when the path to be welded is a curve. Good welding can be realized reliably.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described. First, the configuration of the laser processing apparatus will be described with reference to FIG. As shown in the figure, two galvanized steel plates are placed on the laser processing table 10 in a state of being overlapped. Hereinafter, the lower galvanized steel sheet will be referred to as the lower plate 11, and the upper galvanized steel sheet will be referred to as the upper plate 12. It is preferable to hold the lower plate 11 and the upper plate 12 with a jig so that the overlapping portions of both plates are as close as possible.

A laser processing head 13 is disposed above the laser processing table 10 on which the lower plate 11 and the upper plate 12 are placed, and a laser beam generated by a fiber laser oscillator 17 through the optical fiber 14 is placed on the laser processing head 13. Is output. In place of the fiber laser oscillator 17, other types of laser oscillators such as a YAG laser oscillator and a CO ₂ laser oscillator may be used.

  The laser processing head 13 houses a collimation lens 15 and a condenser lens 16. The laser beam from the fiber laser oscillator 17 is first converted into parallel rays by the collimation lens 15, and the parallel rays are condensed at a predetermined focal length by the condenser lens 16. The laser processing head 13 is configured to be movable in the X and Y directions within the surface of the upper plate 12 and in the Z direction perpendicular to the surface of the upper plate 12 by moving means such as a laser processing robot. Yes.

  Therefore, by moving the laser processing head 13 in the Z direction, the width of the irradiation region 19 of the laser beam 18 output from the laser processing head 13 (a circular region when viewed from the direction perpendicular to the upper plate 12) is changed. be able to. The energy density of the laser beam 18 is energy per unit area of the irradiation region 19a. If the oscillation output (power) of the fiber laser oscillator 17 is constant, the energy density of the laser beam 18 is inversely proportional to the area of the irradiation region 19a. It will be.

  The width of the irradiation region 19 can also be changed by replacing the collimation lens 15 or the condenser lens 16 of the laser processing head 13. Further, by moving the laser processing head 13 in the X direction, in the Y direction, or in the X direction and the Y direction at the same time, the irradiation region 19 of the laser beam 18 is moved on the overlapping portion along an arbitrary path. It can be moved at a desired moving speed.

  Hereafter, the laser welding method of the galvanized steel plate using the said laser processing apparatus is demonstrated. First, as shown in the perspective view of FIG. 2A, the energy density is low along the first linear path K1 from the starting point P1 to the ending point P2 on the overlapping portion of the lower plate 11 and the upper plate 12, Irradiation is performed while moving the first laser beam 18a having a wide irradiation region 19a.

  As a result, as shown in FIG. 2B (a cross-sectional view taken along the line AA in FIG. 1A), the zinc present on the overlapping surface of the lower plate 11 and the upper plate 12 corresponding to the wide irradiation region 19a is the first. The first laser beam 18a is heated to evaporate and degas. That is, the zinc vapor generated from the overlapping surface escapes through the gap between the overlapping portions of the lower plate 11 and the upper plate 12. At this time, since the energy density of the first laser beam 18a is low, the steel material does not melt and only zinc evaporates.

  After that, as shown in FIG. 3, the second straight path on the overlapping portion of the lower plate 11 and the upper plate 12 is adjacent to the first straight path K1 and parallel to the first straight path K1. Irradiation is performed while moving the first laser beam 18a having a low energy density and a wide irradiation region 19a along K2. The second straight path K2 is a straight path from the starting point P3 to the end point P4, and the length of the path is substantially the same as the length of the first straight path K1. Similarly, at this time, zinc existing on the overlapping surface of the lower plate 11 and the upper plate 12 corresponding to the wide irradiation region 19a along the second linear path K2 is heated by the first laser beam 18a and evaporated. Degas.

  Thereafter, as shown in FIG. 4, a third straight path on the overlapping portion of the lower plate 11 and the upper plate 12, adjacent to the second straight path K <b> 2 and parallel to the second straight path K <b> 2. Irradiation is performed while moving the first laser beam 18a having a low energy density and a wide irradiation region 19a along K3. The third straight path K3 is a straight path from the starting point P5 to the end point P6, and the length of the path is substantially the same as the lengths of the first and second straight paths K1, K2. Similarly, at this time, zinc existing on the overlapping surface of the lower plate 11 and the upper plate 12 corresponding to the wide irradiation region 19a along the third linear path K3 is heated by the first laser beam 18a and evaporated. Degas.

  In this case, the starting points P1, P3, and P5 of the first to third straight paths K1 to K3 are on the same straight line, and the starting points P1, P3, and P5 are also on the same straight line. Further, the moving direction of the first laser beam 18a may be either the left-right direction.

  After moving the first laser beam 18a along the first to third paths K1 to K3 as described above, as shown in FIG. 5A, the energy density is higher than that of the first laser beam 18a. The second laser beam 18b having a high and narrow irradiation area 19b is preferably along the second straight path K2 sandwiched between the first straight path K1 and the third straight path K3, and preferably the second straight line. Irradiation is performed while moving along the center line of the path K2. At this time, the moving direction of the second laser beam 18b may be either P3 → P4 or P4 → P3.

  In this case, the entire narrow irradiation region 19b of the second laser beam 18b is included in the wide irradiation region 19a. When the wide irradiation area 19a and the narrow irradiation area 19b are overlapped, it is preferable to form a concentric circle sharing the center point A. (Refer to FIG. 6) In this way, as shown in FIG. 5B (cross-sectional view taken along line BB in FIG. 5A), along the second straight path K2, a narrow irradiation region 19b is formed. Corresponding lower plate 11 and upper plate 12 are melted to form a welded joint. At this time, not only the laser irradiation area corresponding to the second linear path K2, but also zinc plated in a wide range including the laser irradiation areas corresponding to the first and third linear paths K1 and K3 on both sides thereof has already been obtained. Since it is evaporated and degassed, it is possible to form a good weld joint without the influence of a wide range of zinc vapor.

  That is, compared with the case where the first laser beam 18a is irradiated along one linear path and the second laser beam 18b is irradiated along the same path, in this embodiment, plating is performed in a wider range. After the zinc is evaporated and degassed, welding can be performed. On the other hand, when the irradiation of the first and third straight paths K1 and K3 is not performed, the evaporation and deaeration of zinc is insufficient, and the blowhole cannot be prevented. Further, when it is desired to remove a wide range of zinc, the number of straight paths may be further increased.

  The interval between the first to third linear paths K1 to K3 can be set freely to some extent, but the interval is preferably as small as possible. This is because if the distance between the first to third straight paths K1 to K3 is too large, the non-irradiation area where the laser irradiation is not performed becomes wide, and the effect of removing zinc is not sufficiently exhibited. 3 to 5 illustrate the case where the wide irradiation areas 19a of the first to third linear paths K1 to K3 are separated from each other, the ends of the wide irradiation areas 19a of the adjacent paths overlie each other. You may wrap. Thereby, it is possible to prevent a non-irradiation region from being generated between the first to third straight paths K1 to K3.

  Unlike the present embodiment, a method of evaporating and deaerating a wide range of zinc by expanding the irradiation area of the first laser beam 18a is conceivable. However, the energy of the laser beam can be increased only by expanding the irradiation area. In order to compensate for the decrease in density, the moving speed of the laser beam must be considerably reduced. If it does so, productivity will fall. Further, the oscillation output of the fiber laser oscillator 17 is also limited, and it is often difficult to widen the irradiation area while maintaining the energy density.

  Further, as described above, the first and second laser beams 18a and 18b are moved back and forth without moving simultaneously, so that their moving speeds can be controlled independently. Thereby, welding conditions can be optimized. At this time, the moving speed of the first laser beam 18a is preferably smaller than the moving speed of the second laser beam 18b. That is, by slowly moving the first laser beam 18a, the evaporation and removal of zinc can be promoted. On the other hand, even if the movement of the second laser beam 18b is faster than that, an appropriate weld joint can be formed, leading to a reduction in laser processing time.

  On the other hand, when two laser beams are moved simultaneously as in the welding method of Patent Document 1, if the laser beam is moved slowly in order to sufficiently remove zinc, the steel plate portion is melted. If the laser beam is moved quickly in order to optimize the formation of the weld joint, there is a disadvantage that the removal of zinc becomes insufficient. That is, since the moving speeds of the two laser beams are the same, there is a restriction on optimization of the welding conditions.

[Second Embodiment]
In the first embodiment, the path of movement of the first laser beam 18a and the second laser beam 18b is a straight path, but is not limited to this and may be any path. In the present embodiment, a circumferential route will be described as a preferable route other than a straight route.
In this embodiment, the laser processing apparatus is used, and other conditions are the same as those in the first embodiment.

  First, as shown in FIG. 7, the first laser beam 18a is started from the starting point P7 along the first circumferential path K4 on the overlapping portion of the lower plate 11 and the upper plate 12, and again the same starting point. Move to return to P7. That is, the wide irradiation region 19a of the first laser beam 18a goes around the first circumferential path K4. As a result, as in the first embodiment, the zinc existing on the overlapping surface of the lower plate 11 and the upper plate 12 corresponding to the wide irradiation region 19a is heated by the first laser beam 18a to be evaporated and degassed. .

  Thereafter, as shown in FIG. 8, along the second circumferential path K5 adjacent to the outside of the first circumferential path K4, the first laser beam 18a is returned from the starting point P8 to the same starting point P8 again. Move. That is, the irradiation region 19a of the first laser beam 18a goes around the second circumferential path K5. Also at this time, zinc existing on the overlapping surface of the lower plate 11 and the upper plate 12 corresponding to the wide irradiation region 19a is heated by the first laser beam 18a, and is evaporated and degassed.

  Thereafter, as shown in FIG. 9, along the third circumferential path K6 adjacent to the outside of the second circumferential path K5, the first laser beam 18a is again returned from the starting point P9 to the same starting point P9. Move. That is, the irradiation region 19a of the first laser beam 18a goes around the third circumferential path K6. Also at this time, zinc existing on the overlapping surface of the lower plate 11 and the upper plate 12 corresponding to the wide irradiation region 19a is heated by the first laser beam 18a, and is evaporated and degassed.

  In this case, the centers of the first to third circumferential paths K4 to K6 are preferably the same, that is, the first to third circumferential paths K4 to K6 are preferably concentric circles. The order of the first to third circumferential paths K4 to K6 for moving the first laser beam 18a is arbitrary.

  Thereafter, as shown in FIG. 10, the second laser beam 18b having a higher energy density than the first laser beam 18a and having a narrow irradiation region 19b is preferably moved along the second circumferential path K5. Irradiation while moving along the center line of the circumferential path K5. That is, the second laser beam 18b moves along the second circumferential path K5 sandwiched between the first and third circumferential paths K4 and K6.

  In this case, the second laser beam 18b starts from the starting point P8 and moves to return to the starting point P8 again. That is, the irradiation region 19b of the second laser beam 18b goes around the second circumferential path K5. The starting point P8 at this time does not need to coincide with the starting point P8 of the first laser beam 18a, and can be arbitrarily selected on the second circumferential path K5.

As a result, the steel plate portions of the lower plate 11 and the upper plate 12 corresponding to the narrow irradiation region 19b are melted along the second circumferential path K5 to form a weld joint. At this time, not only the laser irradiation area corresponding to the second circumferential path K5 but also zinc plated in a wide range including the laser irradiation areas corresponding to the first and third circumferential paths K4 and K6 on both sides thereof. Has already been evaporated and degassed, it is possible to eliminate the influence of zinc vapor and form a good weld joint. The diameters of the first to third circumferential paths K4 to K6 can be freely set to some extent, but it is preferable that the distance between the circumferential paths is as small as possible for the reason described above. Further, when it is desired to remove a wider range of zinc, the number of circumferential paths may be further increased. Thus, according to the present embodiment, the moving path of the laser beam is a circumferential path, and the first path Although it is different from the straight path according to the embodiment, the same effect can be obtained.

  In addition, according to the present embodiment, the first laser beam 18a and the second laser beam 18b are moved back and forth without moving the first laser beam 18a and the second laser beam 18b at the same time. Even in the case of a curved path such as K4 to K6, it is possible to eliminate the shift of the path along which the first laser beam 18a and the second laser beam move. On the other hand, when two laser beams are moved simultaneously as in the welding method disclosed in Patent Document 1, since the emission positions of the two divided laser beams are different, the movement path is likely to be shifted. . When the movement path is displaced, the steel material portion from which zinc has not been sufficiently removed is melted and welded, which causes a problem of causing welding defects such as deterioration of welding strength.

[Third Embodiment]
This embodiment is different from the first and second embodiments in that the path of movement of the first laser beam 18a and the second laser beam 18b is a spiral path. In this embodiment, the laser processing apparatus is used, and other conditions are the same as those in the first embodiment.

  First, as shown in FIG. 11, the first laser beam 18a is moved from the starting point P11 to the end point P12 along the spiral path K7 on the overlapping portion of the lower plate 11 and the upper plate 12. That is, the wide irradiation area 19a of the first laser beam 18a moves on the spiral path K7. At this time, zinc existing on the overlapping surface of the lower plate 11 and the upper plate 12 corresponding to the wide irradiation region 19a is heated by the first laser beam 18a to be evaporated and degassed.

  Thereafter, as shown in FIG. 12, the second laser beam 18b is moved from the start point P13 to the end point P14 along the spiral path K7 on the overlapping portion of the lower plate 11 and the upper plate 12. That is, the irradiation region 19b narrow to the second laser beam 18b moves along the path in which the first laser beam 18a has already been irradiated to the regions on both sides of the spiral path K7. Thereby, along the spiral path K7, the steel plate portions of the lower plate 11 and the upper plate 12 corresponding to the narrow irradiation region 19b are melted along the route from the start point P13 to the end point P14, and a weld joint is formed.

  At this time, not only the laser irradiation area corresponding to the spiral path from the starting point P13 to the end point P14, but also the zinc plated in a wide range including the laser irradiation areas corresponding to the spiral paths on both sides has already evaporated and deaerated. Therefore, the influence of zinc vapor can be eliminated and a good weld joint can be formed. Thus, according to the present embodiment, the moving path of the laser beam is a spiral path, which is different from the linear path according to the first embodiment, but the same effect can be obtained. Further, when it is desired to remove a wide range of zinc, the number of turns of the spiral path may be further increased.

  Further, according to the present embodiment, since the moving path of the first laser beam 18a is spiral, continuous irradiation is possible without stopping the laser beam irradiation halfway. This also has a unique effect of improving productivity.

  In addition, in the said 1st thru | or 3rd embodiment, although laser welding is performed in the state which piled up two galvanized steel plates, this invention is the state in which three or more galvanized steel plates were piled up. It can also be applied to laser welding. In addition, the metal plating plate to be laser welded according to the present invention is not limited to a galvanized steel plate, but a metal having a boiling point lower than the melting point of the steel plate, such as aluminum or tin, is plated on the surface of the steel plate. The metal plating board which becomes may be sufficient. Further, the material of the base metal plate is not limited to iron, and may be, for example, an alloy of iron and other elements.

Hereinafter, specific examples of the present invention will be described. Two galvanized steel sheets (standard: GAC270 t1.2) were prepared. This galvanized steel sheet has a thickness of 1.2 mm, and is galvanized at 40 g / m ² on the front and back surfaces. And the 1st laser beam 18a was irradiated along the 1st thru | or 3rd circumferential path | route K4-K6 to the overlapping part of two galvanized steel plates. The oscillation output of the fiber laser oscillator 17 at this time was 4 kW, the wide irradiation area 19a of the first laser beam 18a was circular, and its diameter was 1.0 mm. The moving speed of the first laser beam 18a was 1 m / min. (See FIGS. 7-9)

  After the irradiation with the first laser beam 18a, the second laser beam 18b was irradiated along the second circumferential path K5. At this time, the oscillation output of the fiber laser oscillator 17 was 4 kW, the narrow irradiation region 19b of the second laser beam 18b was circular, and its diameter was 0.8 mm. The moving speed of the second laser beam 18b was 3.5 m / min, which is faster than the moving speed of the first laser beam 18a. (See Figure 10)

  Since the oscillation output of the fiber laser oscillator 17 is constant at 4 kW, the energy density of the laser beam is inversely proportional to the area of the irradiation region. The energy density of the first laser beam 18a is 64% of the energy density of the second laser beam 18b. By irradiating the first and second laser beams 18a and 18b, the two galvanized steel plates are welded along the second circumferential path K5, and it is confirmed that the weld strength is high and the appearance is good. It was.

It is a figure which shows the structure of the laser processing apparatus in embodiment of this invention. It is the perspective view and sectional drawing explaining the laser welding method of the galvanized steel plate by the 1st Embodiment of this invention. It is a perspective view explaining the laser welding method of the galvanized steel plate by the 1st Embodiment of this invention. It is a perspective view explaining the laser welding method of the galvanized steel plate by the 1st Embodiment of this invention. It is the perspective view and sectional drawing explaining the laser welding method of the galvanized steel plate by the 1st Embodiment of this invention. It is a top view which shows the irradiation area | region by a laser beam. It is a perspective view explaining the laser welding method of the galvanized steel plate by the 2nd Embodiment of this invention. It is a perspective view explaining the laser welding method of the galvanized steel plate by the 2nd Embodiment of this invention. It is a perspective view explaining the laser welding method of the galvanized steel plate by the 2nd Embodiment of this invention. It is a perspective view explaining the laser welding method of the galvanized steel plate by the 2nd Embodiment of this invention. It is a top view explaining the laser welding method of the galvanized steel plate by the 3rd Embodiment of this invention. It is a top view explaining the laser welding method of the galvanized steel plate by the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Laser processing table 11 ... Lower plate 12 ... Upper plate 13 ... Laser processing head 14 ... Optical fiber 15 ... Collimation lens 16 ... Condensing lens 17 ... Fiber laser Oscillator 18 ... Laser beam 18a ... First laser beam 18b ... Second laser beam 19a ... Wide irradiation area 19b ... Narrow irradiation area K1 ... First linear path K2. .. second straight path K3 ... third straight path K4 ... first circumferential path K5 ... second circumferential path K6 ... third circumferential path K7 ... Spiral path

Claims (6)

A metal that is welded by superimposing a plurality of metal plating plates on the surface of the base metal plate with a metal having a boiling point lower than the melting point of the base metal, and irradiating the overlap portion with a laser beam In the laser welding method for plated plates,
By irradiating while moving the first laser beam having a low energy density and a wide irradiation area along the first to third paths adjacent to each other on the overlapping portion, the wide irradiation area Evaporate and degas the metal plated on the base metal part of
After irradiating the first laser beam along the first to third paths, the first laser beam is more advanced than the first laser beam along the second path sandwiched between the first and third paths. By irradiating while moving the second laser beam having a high energy density and a narrower irradiation area than the first laser beam, the base metal part of the narrow irradiation area is melted and welded. A laser welding method for a metal plating plate, characterized by comprising: The laser welding method for a metal plated plate according to claim 1, wherein the first to third paths are linear paths parallel to each other. 2. The method of laser welding a metal-plated plate according to claim 1, wherein the first to third paths are paths along the circumferences of three concentric circles having different diameters. A metal that is welded by superimposing a plurality of metal plating plates on the surface of the base metal plate, with a metal having a boiling point lower than the melting point of the base metal, and irradiating the overlap portion with a laser beam In the laser welding method for plated plates,
By irradiating while moving the first laser beam having a low energy density and a wide irradiation area along the spiral path on the overlapping portion, the base metal part of the wide irradiation area is plated. Evaporated metal,
After irradiating the first laser beam along the entire spiral path, the first laser beam is irradiated along the path in which the first laser beam is irradiated on both sides of the spiral path. By irradiating while moving the second laser beam having an energy density higher than that of the laser beam and having an irradiation region narrower than that of the first laser beam, the base metal portion of the narrow irradiation region is melted. And a laser welding method for a metal-plated plate, characterized by welding and joining. The metal welding plate laser welding method according to any one of claims 1 to 4, wherein a moving speed of the first laser beam is smaller than a moving speed of the second laser beam. 6. The method of laser welding a metal plated plate according to claim 1, wherein the base metal is steel, and the metal plated on the surface of the base metal plate is zinc or aluminum. .

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