JP2012035303A - Method for laser welding of metallic plate material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a sound laser welding at low cost by eliminating the need for special jigs or devices to reduce the cost of equipment and also avoiding an increase in the number of processes, in performing laser welding of a gap defined between plate materials, even if there is hardly any gap between the plate materials or the gap is so wide.SOLUTION: A method for laser welding of metallic plate materials, includes: a preparation step of overlapping a first zinc-coated steel plate 11 and a second zinc-coated steel plate 12 and holding the plates; a gap adjustment step of irradiating the first zinc-coated steel plate 11 with a bending laser beam for bending the first zinc-coated steel plate 11 toward the side of the second zinc-coated steel plate 12 so as to generate a gap when there is hardly any gap between the plate materials 11, 12, on the contrary when the gap between the plate materials 11, 12 is so wide, a bent part of the first zinc-coated steel plate 11 is brought into closer to the second zinc-coated steel plate 12 to adjust the gap; and a welding step of welding the plate materials 11, 12 with each other by irradiating with a welding laser beam.

Description

  The present invention relates to a laser welding method in which laser welding is performed in a state where metal plate materials are overlapped.

  2. Description of the Related Art Conventionally, for example, spot welding methods have been widely used when welding steel sheets at automobile manufacturing sites. In the spot welding method, since two steel plates are sandwiched by a pair of rod-shaped electrodes, only intermittent welding can be performed, and there is a restriction that it cannot be applied to a portion where it is not satisfactory in terms of strength or where sealability is desired. It was.

  Therefore, in recent years, laser welding has attracted attention, particularly in the automobile industry. The reason for this is the emergence of remote laser welding equipment that can move the galvanometer mirror and scan the laser light at high speed.

  As a steel plate constituting an automobile, there are various steel plates such as a galvanized steel plate that has been galvanized as a rust-proofing treatment, and a cold-rolled steel plate that is used in a portion that does not require a rust-proofing treatment. Among these steel plates, it is known that the following problems may occur when welding galvanized steel plates and when welding galvanized steel plates and cold-rolled steel plates.

  That is, when the steel plates are overlapped, there may be a portion in which there is no gap between the two. When laser light is irradiated onto this closely contacted portion, the galvanizing is evaporated, and the vapor causes pits and blowholes in the steel sheet, causing poor welding. In addition, when the two steel plates are overlapped, if the gap between them becomes about 0.3 mm or more, the steel plate located on the side irradiated with the laser light will melt away, which is the cause of welding failure. Become.

  A general method for eliminating these welding defects is to set the gap between the two steel plates to about 0.1 mm. However, at an actual manufacturing site, an error occurs in the steel sheet within the range of manufacturing tolerances, and an error may also occur when the steel plate is fixed with a welding jig. Therefore, it is difficult to keep the gap between the two steel plates in the above-mentioned appropriate range, and there is no gap or it is too wide depending on the part.

  In response to this, for example, various attempts have been made as disclosed in Patent Documents 1 to 3.

  The methods disclosed in Patent Documents 1 and 2 are laser welding methods in the case where there is no gap between two steel plates. In the method disclosed in Patent Document 1, first, the stacked steel plates are irradiated with the first laser beam to melt the steel plates located on the irradiation side. Thereby, a convex part is formed on the back side of the steel plate on the laser beam irradiation side. A gap is formed between the two steel plates by forming the convex portion. And both the steel plates are welded by the second laser beam irradiation.

  In the method of Patent Document 2, before superimposing two steel sheets, only one steel sheet is held by a jig, and the steel sheet is deformed by irradiating the steel sheet with laser light. Thereafter, when the two steel plates are overlapped, a gap is formed between the two steel plates due to the deformation of the one steel plate. Then, both steel plates are welded by the second laser beam irradiation.

  The method disclosed in Patent Document 3 is a laser welding method that can cope with both a case where there is no gap between two steel plates and a case where the gap is too wide. The steel plates are overlapped and irradiated with the first laser beam. If there is no gap, the steel plate located on the back side is melted in a range not penetrating, and then the second side is irradiated with the laser beam. Weld through the steel plate. On the other hand, if the gap is too wide, the steel plate located on the irradiation side is melted and dented to narrow the gap between the two steel plates and penetrate the steel plate located on the back side by the second laser light irradiation. And perform welding.

JP 2002-178178 A JP 2005-144504 A JP 2010-23047 A

  However, since the laser welding method of Patent Document 1 does not consider the case where the gap between the two steel plates is too wide, if the gap is too wide, the above-described steel plate located on the laser light irradiation side is burned off. There is a fear. In order to avoid this, a jig for holding the two steel plates so that there is no gap before the formation of the recess is necessary. However, such a jig is expensive and causes an increase in equipment cost.

  The laser welding method of Patent Document 2 also does not consider the case where the gap between the two steel plates is too wide, so there is a possibility that the steel plates will melt. In addition, since one steel plate is deformed and then superposed on the other steel plate, the manufacturing apparatus becomes complicated and the number of processes increases, resulting in high costs. Furthermore, even if the deformed steel sheet is superposed on the other steel sheet, an appropriate gap is not always formed between the two steel sheets.

  In the laser welding method of Patent Document 3, since the steel plate located on the laser beam irradiation side is melted by the first laser beam irradiation, there is a concern that pits and blowholes may be generated. If this occurs, it is difficult to repair it by the second laser beam irradiation, and as a result, there is a concern that poor welding will occur.

  The present invention has been made in view of such a point, and the object of the present invention is to perform laser welding, even when there is no gap between the plate members, even when the gap is too wide. In addition to reducing the cost of equipment by eliminating the need for special jigs and equipment, it is also possible to avoid an increase in the number of processes and perform sound laser welding at low cost.

  In order to achieve the above object, in the present invention, before welding, the gap between the plate materials is adjusted to an appropriate range by bending the plate material positioned on the laser beam irradiation side by irradiating the laser beam, and then the welding process. To do.

  In the first invention, in a state where the first metal plate material and the second metal plate material, at least one of which is plated, are overlapped with each other, the two metal plate materials are obtained by irradiating laser light from the first metal plate material side. In the laser welding method for welding, the first metal plate material is applied to the first metal plate material after the preparation step of superimposing and holding the first metal plate material and the second metal plate material, and after the preparation step. Is irradiated with a bending laser beam to bend toward the second metal plate member side, and there is no gap between the two metal plate members, the second metal plate is bent by deformation of the first metal plate member. Pushing the plate material to create a gap between the two metal plate materials. On the other hand, if the gap between the two metal plate materials is too wide, the bent portion of the first metal plate material is moved closer to the second metal plate material. A gap adjustment process for adjusting the gap between the two metal plates; A welding step of welding the two metal plate materials by irradiating a welding laser beam for welding the first metal plate material and the second metal plate material after the gap adjusting step; To do.

  That is, when there is no gap between the first metal plate and the second metal plate, the first metal plate is directed toward the second metal plate by irradiation of the bending laser beam in the gap adjustment step. At this time, the second metal plate is pushed in a direction away from the first metal plate by the bent portion of the first metal plate. This creates a gap between the first metal plate and the second metal plate. At this time, since the first metal plate material and the second metal plate material are held in a state of being overlapped in the preparation step prior to the gap adjustment step, the gap between the plate materials does not become too wide. Therefore, the gap between the plate materials is adjusted to an appropriate range. When the welding laser beam is irradiated in the welding process, the gap between the plate materials is within an appropriate range, and thus generation of pits and blowholes due to evaporation of plating is suppressed. Since the jig used at this time only needs to hold the first metal plate and the second metal plate in an overlapped state, a general-purpose jig can be used.

  On the other hand, when the gap between the first metal plate and the second metal plate is too wide, the first metal plate is directed toward the second metal plate by irradiation of the bending laser beam in the gap adjustment step. And the gap between the plate materials is narrowed. And the clearance gap between board | plate materials becomes narrow, the clearance gap between board | plate materials becomes an appropriate range, and the 1st metal plate | plate material does not melt down in a welding process.

  As described above, the gap can be adjusted while the first metal plate and the second metal plate are overlapped, and then the welding can be immediately performed. Therefore, a special jig or manufacturing apparatus is not required, so that the equipment cost is not increased, and the number of processes is not increased.

  In addition, in this invention, when both the 1st metal board | plate material and the 2nd metal board | plate material are plated, it can apply to either the case where one side is plated, and the same effect is obtained.

  Also, at the actual welding site, there are many cases where it is not known how much the gap between the first and second metal plate materials is, but also in this case, if there is no gap in the present invention, both are too wide Therefore, it does not become a problem in welding.

  Moreover, it can respond to both the case where it is known beforehand that there is no gap between the first and second metal plate materials and the case where it is known beforehand that the gap is too wide. When the gap is too wide, welding is possible using the method according to the present invention even when both the first and second metal plate members are not plated.

  In addition, an appropriate range of the gap between the first and second metal steel plates (a range where sound welding is possible) is 0.1 mm or more and less than 0.3 mm.

  According to a second invention, in the first invention, in the gap adjusting step, the bending laser light is irradiated to a plurality of locations of the first metal plate material.

  According to this configuration, it is possible to finely adjust the bending amount and the bending range of the first metal plate material.

  The third invention is characterized in that, in the first invention, the irradiation range of the bending laser beam in the gap adjusting step is narrower than the irradiation range of the welding laser beam in the welding step.

  That is, for example, by irradiating the bending laser beam in a spot manner, the first metal plate material is bent not only at the irradiation portion of the bending laser beam but also around the periphery thereof. Thereby, since the clearance gap between board | plate materials is adjusted over the range wider than the irradiation range of the actual bending laser beam, energy consumption can be reduced.

  According to a fourth invention, in any one of the first to third inventions, the strength of the bending laser light is set so as not to melt the first metal plate material in the gap adjustment step. Is.

  According to this configuration, since the first metal plate material does not melt in the gap adjustment step, it is possible to prevent the first metal plate material from being melted.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the irradiation portion of the welding laser beam in the welding step is deviated from the irradiation portion of the bending laser beam in the gap adjustment step. Is.

  For example, depending on the shape of the bent portion of the first metal plate material, the gap between the portion irradiated with the bending laser beam and the second metal plate material may be too narrow. In this case, it is possible to irradiate the laser beam for welding to a portion where an appropriate gap is formed by shifting the irradiation site of the welding laser beam from the irradiation site of the bending laser beam.

  According to the first invention, the first metal plate is bent toward the second metal plate by irradiating the bending laser beam, and when there is no gap between the two metal plates, the second metal is made. Press the plate material to create a gap. On the other hand, if the gap between the two metal plate materials is too wide, adjust the gap by bringing the strong part of the first metal plate material closer to the second metal plate material, and then welding Laser light is irradiated. This eliminates the need for special jigs and manufacturing equipment, reduces equipment costs, and avoids an increase in the number of processes, allowing the gap between the plate materials to be adjusted to an appropriate range, and performing sound laser welding at low cost. be able to.

  According to the second invention, since the bending laser light is irradiated to a plurality of locations of the first metal plate material, the bending amount and the bending range of the first metal plate material can be finely adjusted. Thereby, the clearance gap between board | plate materials can be made appropriate according to the site | part and shape to weld, and a more sound laser welding can be performed.

  According to the third invention, since the irradiation range of the bending laser beam is narrower than the irradiation range of the welding laser beam, sound laser welding can be performed while reducing the energy consumption.

  According to the fourth invention, the laser beam for bending is irradiated so that the first metal plate material does not melt in the gap adjusting step, so that the first metal plate material can be surely prevented from being melted, Sound laser welding can be performed.

  According to the fifth aspect of the invention, since the irradiation site of the welding laser beam is shifted from the irradiation site of the bending laser beam, the welding laser beam can be irradiated to a portion where an appropriate gap is formed. Thereby, sound laser welding can be performed.

It is a schematic block diagram of the laser welding apparatus used for the laser welding method of this invention. It is a perspective view showing the state where two galvanized steel plates were fixed to a jig at intervals in the thickness direction. FIG. 3 is a view corresponding to FIG. 2 in a state where a bending laser beam is irradiated. FIG. 3 is a view corresponding to FIG. 2 in a state where a laser beam for welding is irradiated. It is a perspective view which shows the state which contact | adhered two galvanized steel plates and was fixed to the jig | tool. FIG. 6 is a view corresponding to FIG. 5 in a state in which the bending laser light is irradiated. FIG. 6 is a view corresponding to FIG. 5 showing a modification of the jig. FIG. 6 is a view corresponding to FIG. 3 according to Modification 1 of the method of irradiating the bending laser beam. FIG. 6 is a view corresponding to FIG. 3 according to a second modification of the method of irradiating the bending laser beam. FIG. 6 is a view corresponding to FIG. 3 according to Modification 3 of the method of irradiating the bending laser beam. FIG. 9 is a view corresponding to FIG. 3 according to Modification 4 of the method of irradiating the bending laser beam. FIG. 6 is a view corresponding to FIG. 4 according to Modification 4 of the method for irradiating the welding laser beam.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

  FIG. 1 shows a laser welding apparatus 1 used in a laser welding method according to an embodiment of the present invention. The laser welding apparatus 1 includes a laser oscillator 2, a machining head 3, and a control device 4 that controls the laser oscillator 2 and the machining head 3.

  The laser oscillator 2 is configured to output laser light based on the instruction signal output from the control device 4. Laser light output from the laser oscillator 2 is transmitted to the machining head 3 through a transmission fiber (not shown).

  The processing head 3 incorporates a carbano mirror, a condenser lens (both not shown), etc., adjusts the focus based on the instruction signal output from the control device 4, and sets the laser beam at a set speed. It is configured to scan in the specified direction.

The metal plate materials laser-welded using the laser welding apparatus 1 are the first and second galvanized steel plates 11 and 12 formed in a substantially rectangular shape. The thickness of the first galvanized steel sheet 11 is 1.0 mm, and the basis weight of zinc is 55 g / m ² . The second galvanized steel sheet 12 is the same as the first galvanized steel sheet 11.

  The shapes and thicknesses of the first and second galvanized steel sheets 11 and 12 and the basis weight of zinc are merely examples, and do not limit the application range of the present invention.

  When the first and second galvanized steel plates 11 and 12 are laser-welded, they are fixed to a jig 20 shown in FIG. The jig 20 includes a metal block 21 and fasteners 23, 23,. The block 21 has a recess 21a that opens upward. The galvanized steel plates 11 and 12 are arranged and fixed so that the welded portions correspond to the recesses 21a.

  Each fastener 23 is specifically a bolt and passes through the corners of the first and second galvanized steel plates 11 and 12 and is screwed into the block 21. Accordingly, the first and second galvanized steel plates 11 and 12 are fixed to the block 21.

  Note that the jig 20 is simply configured as described above for convenience of description of the present embodiment, and it is sufficient that the galvanized steel plates 11 and 12 can be fixed so as not to move at an actual welding site. A general-purpose jig can be used.

  Next, the welding procedure of the 1st and 2nd galvanized steel plates 11 and 12 is demonstrated.

  First, a preparation process is performed. This is a process of fixing the first and second galvanized steel sheets 11 and 12 so as not to move at an actual welding site. In the present embodiment, the jig 20 is used. That is, as shown in FIG. 2, after the first and second galvanized steel plates 11 and 12 are arranged on the upper surface of the block 21 so that the first galvanized steel plate 11 is on top, The four corners of 12 are fastened to the block 21 with fasteners 23, 23,.

  In FIG. 2, an initial gap S of about 0.5 mm is formed between the first galvanized steel sheet 11 and the second galvanized steel sheet 12 with a tape (not shown) interposed therebetween. This creates a case where 12 gaps are too wide. In FIG. 2, the initial gap S between the first and second galvanized steel sheets 11 and 12 is drawn wider than the actual gap.

  Thus, assuming the case where laser welding is performed in a state where the initial gap S between the first and second galvanized steel sheets 11 and 12 is about 0.5 mm, the first galvanized steel sheet 11 located on the laser light irradiation side. Melts down to the upper surface of the second galvanized steel sheet 12, and there is a concern that poor welding occurs.

  On the other hand, in this embodiment, the gap adjustment process which adjusts the gap of the welding part of the 1st and 2nd galvanized steel plates 11 and 12 is performed before welding. In the gap adjusting step, as shown in FIG. 3, for bending the first galvanized steel sheet 11 toward the lower side (second galvanized steel sheet 12 side) on the upper surface of the first galvanized steel sheet 11. Irradiate laser beam L1. The irradiation range is indicated by a virtual line A in FIG.

  The bending laser beam L1 is set so that the energy density in the first galvanized steel sheet 11 is smaller than the welding laser beam L2 (shown in FIG. 4) described later. Specifically, the energy density of the bending laser beam L1 is such that the first galvanized steel sheet 11 does not melt.

  As a method for adjusting the energy density in the first galvanized steel sheet 11, there are a method for adjusting the output of the laser beam, a method for adjusting the focus (focal position), a method for adjusting the scanning speed, and the like. The output of the laser beam is the same in the gap adjustment process and the welding process, and the energy density is adjusted by changing the focus and scanning speed.

  That is, in the gap adjustment process, the scanning speed is increased compared to the welding process described later, and in the welding process, the focal position is set to the upper surface of the first galvanized steel sheet 11 (just focus), while the gap adjustment process. Then, the focal position is set at a position away from the upper surface of the first galvanized steel sheet 11. Thereby, the laser beam L1 is irradiated in a wider range in the gap adjustment process than in the welding process.

  Further, the irradiation range of the bending laser beam L1 and the irradiation range of the welding laser beam L2 may be the same. In this case, the energy density can be set as described above by making the scanning speed of the bending laser light L1 faster than the scanning speed of the welding laser light L2 or adjusting the laser output. Further, the irradiation range of the bending laser beam L1 may be narrower than the irradiation range of the welding laser beam L2.

  In addition, you may make it change the output of a laser beam by a clearance gap adjustment process and a welding process. In the gap adjustment process and the welding process, the output of the laser beam and the scanning speed are changed depending on the type of the plate material, the welding conditions, and the like.

  In the first galvanized steel sheet 11 irradiated with the bending laser beam L1, the irradiated portion of the laser beam L1 and the periphery thereof are thermally expanded. At this time, since both ends of the first galvanized steel sheet 11 in the width direction (direction orthogonal to the laser beam scanning direction on the upper surface of the first galvanized steel sheet 11) are restrained by the jig 20, the first galvanized steel sheet 11 11 is subjected to thermal stress and is bent downward (side approaching the second galvanized steel sheet 11) so that the portion irradiated with the bending laser beam L1 is located at the lowest position (see FIG. 3). Show).

  Here, according to an experiment in which the inventors changed the energy density of the bending laser beam L1 in the first galvanized steel sheet 11 in various ways, the bending direction of the first galvanized steel sheet 11 differs depending on the energy density. was gotten. When the energy density of the first galvanized steel sheet 11 is such that the first galvanized steel sheet 11 is not melted at all, and when only the upper surface side of the first galvanized steel sheet 11 is melted, the first galvanized steel sheet 11 11 bends downward.

  In other words, in this step, the first galvanized steel sheet 11 is irradiated with the bending laser beam L1 so that the energy density is bent downward. At this time, the upper surface portion of the first galvanized steel sheet 11 may be somewhat melted. The melting range is preferably about 1/10 to 1/20 of the thickness dimension from the upper surface to the lower surface of the first galvanized steel sheet 11, for example.

  For example, if the first galvanized steel sheet 11 is melted to the center in the thickness direction or to a part closer to the lower surface than the center, the first galvanized steel sheet 11 is bent upward, and the second As a result, the gap between the galvanized steel sheet 12 and the galvanized steel sheet 12 was increased.

  When the first galvanized steel sheet 11 is bent downward as described above, the gap between the second galvanized steel sheet 12 becomes narrower than the initial gap S.

  In addition, the suitable range of the clearance gap between the 1st and 2nd galvanized steel plates 11 and 12 is 0.1 mm or more and less than 0.3 mm.

  Then, a welding process is performed. In the welding process, as shown in FIG. 4, the upper surface of the first galvanized steel sheet 11 is irradiated with a laser beam L2 for welding. The irradiation site of the welding laser beam L2 is separated from the irradiation site A of the bending laser beam L1 in the width direction of the first galvanized steel sheet 11. The distance between the irradiation site A of the bending laser beam L1 and the irradiation site of the welding laser beam L2 is, for example, about several mm.

  The reason why the irradiation site A of the bending laser beam L1 and the irradiation site of the welding laser beam L2 are separated as described above is as follows.

  When the first galvanized steel sheet 11 is bent downward by irradiating the bending laser beam L1, the irradiation site A of the bending laser beam L1 is positioned at the lowest position, and the irradiation site of the bending laser beam L1 is the first. 2 may come into contact with the galvanized steel sheet 12. In this case, there is no gap between the irradiation site A of the bending laser beam L1 of the first galvanized steel sheet 11 and the second galvanized steel sheet 12, so that the welding laser beam L2 is temporarily converted to the bending laser beam L1. When the irradiation site A is irradiated, pits and blowholes may be generated in the steel plates 11 and 12 by the vapor generated when the galvanizing is evaporated.

  On the other hand, in the first galvanized steel sheet 11, a part apart from the irradiation part A of the bending laser beam L <b> 1 is surely formed with the second galvanized steel sheet 12. Moreover, the gap is narrower than the initial gap S. Accordingly, welding failure is less likely to occur by separating the irradiation site A of the bending laser beam L1 and the irradiation site of the welding laser beam L2. FIG. 4 shows a bead after welding by a symbol B.

  Next, a case where there is no gap between the first and second galvanized steel sheets 11 and 12 will be described.

  As shown in FIG. 5, in the preparation step, the tape is fixed to the jig 20 without sandwiching the tape between the first and second galvanized steel plates 11 and 12. Thereby, there will be no gap between the first and second galvanized steel sheets 11 and 12.

  And a clearance gap adjustment process is performed. In the gap adjustment step, the first galvanized steel sheet 11 is irradiated with the bending laser beam L1 so that the energy density is the same as that when the gap is wide. Then, the first galvanized steel sheet 11 in which the thermal stress is generated is bent downward, and the bent portion of the first galvanized steel sheet 1 pushes the second galvanized steel sheet 12 downward. As a result, the second galvanized steel sheet 12 bends downward, and a gap is formed between the first galvanized steel sheet 11 and the second galvanized steel sheet 12. At this time, since the first and second galvanized steel plates 11 and 12 are restrained by the jig 20, the gap between the first galvanized steel plate 11 and the second galvanized steel plate 12 does not become too wide. .

  Moreover, since the 2nd galvanized steel plate 12 is only pushed and deform | transformed by the 1st galvanized steel plate 11, the shape of the bending part of the 1st galvanized steel plate 11 and the shape of the bent part of the 2nd galvanized steel plate 12 Unlike this, a gap is always formed between the two.

  In the subsequent welding process, the upper surface of the first galvanized steel sheet 11 is irradiated with the laser beam L2 for welding as in the case where the gap is wide. The irradiation site of the welding laser beam L2 is separated from the irradiation site A of the bending laser beam L1.

  That is, in the present embodiment, the first galvanized steel sheet 11 is bent downward both in the case where the gap between the first and second galvanized steel sheets 11 and 12 is too wide and in the case where there is no gap. An appropriate gap can be formed, and at this time, a special jig and a manufacturing apparatus are unnecessary.

  Table 1 shows the results of visual inspection and X-ray fluoroscopic inspection of the welded portions of the first and second galvanized steel sheets 11 and 12 laser-welded as described above and the galvanized steel sheets laser-welded by the conventional method. Shown in

  The initial gap in Table 1 is a gap indicated by a symbol S in FIG. 2, where 0 mm is a state where there is no gap and 0.5 mm is a state where the gap is too wide. The appearance inspection is a result of observing the surface using the naked eye or a magnifying glass. The X-ray fluoroscopic inspection is a result of inspecting an internal welding state by irradiating X-rays.

  As is clear from this result, according to the laser welding method of the present invention, good laser welding results were obtained both when there was no initial gap and when the initial gap was too wide.

  As described above, according to this embodiment, the first galvanized steel sheet 11 is placed on the lower side both when the gap between the first and second galvanized steel sheets 11 and 12 is too wide and when there is no gap. And an appropriate gap can be formed between the first and second galvanized steel sheets 11 and 12.

  This eliminates the need for special jigs and manufacturing equipment, reduces equipment costs, and avoids an increase in the number of processes while adjusting the gaps between the plate materials to an appropriate range. It can be carried out.

  Moreover, since the irradiation site | part of the welding laser beam L2 is shifted from the irradiation site | part A of the bending laser beam L1, regardless of the shape of the bending part of the 1st galvanized steel plate 11, it is in the part in which the appropriate clearance gap was formed. The laser beam L2 for welding can be irradiated.

  In the case where the initial gap S between the first and second galvanized steel sheets 11 and 12 is too wide, after the gap adjusting step, between the irradiation part A of the bending laser beam L1 and the second galvanized steel sheet 12. In some cases, an appropriate gap may be formed. In this case, the laser beam L2 for welding may be applied to the irradiation site A of the bending laser L1.

  In addition, as a structure of the jig | tool 20, you may make it fix the 1st and 2nd galvanized steel plates 11 and 12 using the rod-shaped fastener 24 like the modification shown in FIG. The fastener 24 of this modification extends in the scanning direction of the laser beam so that a wide range of both edges in the width direction of the first and second galvanized steel plates 11 and 12 can be fixed to the jig 20. It has become.

  Moreover, you may make it irradiate the laser beam L1 for bending to several places with respect to one welding part like the modifications 1-3 shown in FIGS.

  In Modification 1 of FIG. 8, the bending laser light L <b> 1 is irradiated to two locations separated in the width direction of the first galvanized steel sheet 11. Thereby, the shape of the bent portion of the first galvanized steel sheet 11 can be finely adjusted, and the gap between the first and second galvanized steel sheets 11 and 12 can be adjusted to a more appropriate range. In the case of intermittently irradiating the bending laser beam L1, one irradiation length can be arbitrarily set, and may be the same length. Also, the irradiation interval can be arbitrarily set, and irradiation may be performed at equal intervals or at irregular intervals.

  In Modification 2 of FIG. 9, the bending laser light L1 is irradiated intermittently in the scanning direction. When the bending laser beam L1 is irradiated, heat is transmitted to the surrounding area, so that thermal stress is also generated in the surrounding area, and the bending is performed downward. This makes it possible to secure an appropriate gap between the first and second galvanized steel sheets 11 and 12 without irradiating the bending laser beam L1 over the entire length of the welded portion, so that energy consumption Sound laser welding can be performed while reducing the above.

  Modification 3 of FIG. 10 is a form in which Modifications 1 and 2 are combined, and the bending laser beam L1 is intermittently irradiated in the scanning direction to a portion separated in the width direction of the first galvanized steel sheet 11. .

Further, as in Modification 4 shown in FIGS. 11 and 12, if the part to be laser welded is, for example, C-shaped, the bending laser beam L <b> 1 may be irradiated in correspondence with the C-shaped. Also,
Further, the bending laser beam L1 may be irradiated, for example, in an L shape or in a circle, and the shape is not limited to the above-described shape, and may be various shapes. It's okay.

  Further, the scanning length of the bending laser beam L1 may be longer than that of the welding laser beam L2.

  In the above embodiment, the case where the present invention is applied to the case where both of the two plate materials are the galvanized steel plates 11 and 12 is described. However, the present invention is not limited thereto, and any one of the plate materials is plated. Even if it is not, the present invention can be applied, and similar effects can be obtained.

  Moreover, although not shown in figure, it is also possible to weld the metal plates which are not plated using the method concerning this invention. In this case, when the gap between the plate members is too wide, the gap can be narrowed in the gap adjustment step, so that sound welding can be performed.

  In addition, the method according to the present invention can be used both when it is known in advance that there is no gap between the first and second plated steel sheets 11 and 12 and when it is known in advance that the gap is too wide.

  Further, the bending laser beam L1 may be irradiated to the same site a plurality of times.

  In addition, the present invention can be used in, for example, a welding line at a car body manufacturing site of automobiles, a manufacturing site of various automobile parts, etc., and is also applied to, for example, laser welding of metal plate materials of electrical products. The application range is wide.

  Further, the present invention is not limited to a steel plate made of a metal plate, but can be applied to laser welding of plate materials made of various metal materials. Also, the type of plating is not limited to zinc plating, and can be widely applied when plating is performed with a plating material having a melting point lower than that of a metal plate.

  As described above, the laser welding method according to the present invention is suitable, for example, when welding a galvanized steel sheet constituting a car body of an automobile.

DESCRIPTION OF SYMBOLS 1 Laser welding apparatus 2 Laser oscillator 3 Processing head 4 Control apparatus 11 1st galvanized steel plate (1st metal plate material)
12 Second galvanized steel sheet (second metal plate)
20 Jig 21 Block 21a Recesses 23, 24 Fastener A Bending laser beam irradiation portion L1 Bending laser beam L2 Welding laser beam

Claims (5)

In a laser welding method of welding both metal plate materials by irradiating a laser beam from the first metal plate material side in a state where the first metal plate material and the second metal plate material on which at least one is plated are overlapped ,
A preparatory step of stacking and holding the first metal plate and the second metal plate;
After the preparation step, the first metal plate member is irradiated with a bending laser beam for bending the first metal plate member toward the second metal plate member, and the two metal plate members are exposed to each other. When there is no gap, the second metal plate is pushed by bending deformation of the first metal plate to create a gap between the two metal plates. On the other hand, when the gap between the two metal plates is too wide A gap adjusting step of adjusting a gap between the two metal plate members by bringing the bent portion of the first metal plate member close to the second metal plate member;
A welding step of welding the two metal plate materials by irradiating a welding laser beam for welding the first metal plate material and the second metal plate material after the gap adjusting step; Laser welding method for metal plate. In the laser welding method of the metal plate material according to claim 1,
In the gap adjusting step, a laser welding method for a metal plate material, wherein a plurality of portions of the first metal plate material are irradiated with a bending laser beam. In the laser welding method of the metal plate material according to claim 1 or 2,
A laser welding method for a metal plate material, wherein the irradiation range of the bending laser beam in the gap adjusting step is narrower than the irradiation range of the welding laser beam in the welding step. In the laser welding method of the metal plate material according to any one of claims 1 to 3,
In the gap adjusting step, the intensity of the bending laser beam is set so as not to melt the first metal plate material. In the laser welding method of the metal plate material according to any one of claims 1 to 4,
A laser welding method for a metal plate material, wherein an irradiation site of a welding laser beam in a welding process is shifted from an irradiation site of a bending laser beam in a gap adjustment step.

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