JP2016132002A - Welding method and welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase joining strength of welding, in a welding method for melting butted base metals with a laser beam and joining the molten butted base metals.SOLUTION: The present invention provided a welding method in which respective ends of two metal materials or ends of one metal material having two ends are butted each other, then the ends are molten together with laser beam thereby joined each other. In the welding method, a butting surface 17a of the end 14a and a butting surface 17b of the end 14b are opposed to each other with a welding line 13a interposed between them. Laser beams 23a and 23b are guided to irradiation surfaces 24a and 24b positioned in the vicinity of the butting surfaces 17a and 17b. When the laser beams 23a and 23b scan while they are in parallel with the welding line 13a, strength of the laser beams 23a and 23b is vibrated in a period of the same length, and a phase difference is also provided in vibration between the laser beams 23a and 23b.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a welding method and a welding apparatus. The present invention particularly relates to a method for melting and joining butted base materials and a welding apparatus suitable for the method.

  Patent Document 1 discloses a butt welding method in the case where there is a gap in the butt portion. FIG. 1 is a plan view of a base material to be welded by the same welding method. Here, the base materials 10a and 10b are joined on the weld line 13a. Base materials 10a and 10b are metal plates.

  As shown in FIG. 1, high-intensity laser light is irradiated to the spots 11a and 11b on the base materials 10a and 10b, respectively. Around the spots 11a and 11b, molten pools 12a and 12b are generated. When the weld pools 12a and 12b expand, they approach each other. For this reason, each molten base material 10a, 10b can fill the gap 13b between them. Moreover, since the molten pools 12a and 12b melt together, the base materials 10a and 10b are joined together.

  As shown in FIG. 1, the laser beams applied to the spots 11a and 11b travel along the traveling directions 16a and 16b while being synchronized with each other. For this reason, the gap 13b is continuously filled. Further, the base materials 10a and 10b are continuously joined together. Here, the traveling directions 16a and 16b are parallel to the welding line 13a located at the center of the gap 13b.

JP 2011-092944 A

  The inventors proceeded with research on the method shown in FIG. Hereinafter, description will be given with reference to the drawings. As shown in FIG. 1, the base materials 10a and 10b have butt surfaces 17a and 17b, respectively. The butting surfaces 17a and 17b are opposed to each other with the gap 13b interposed therebetween. The surfaces of the base materials 10a and 10b are covered with their own oxide films. Similarly, the butted surfaces 17a and 17b are covered with oxide films 18a and 18b represented by hatched portions.

  In the method shown in FIG. 1, the intensities of the laser beams applied to the spots 11a and 11b are made equal so that the sizes of the molten pools 12a and 12b are equal. For this reason, the fusion center line 15 between the molten pool 12a and the molten pool 12b is often located on the weld line 13a.

  In the welding method shown in FIG. 1, the butt surfaces 17 a and 17 b are taken into the fusion center line 15. At this time, the molten pools 12a and 12b are joined by melting and then solidifying. If the melting progresses well, the base materials 10a and 10b are well joined. However, the oxide films 18a and 18b may remain facing each other after the laser light applied to the spots 11a and 11b passes. In such a case, the molten pools 12a and 12b are easy to solidify without melting each other.

  Therefore, when welding is performed by the welding method shown in FIG. 1, the strength of joining between the base materials 10a and 10b may be reduced. Moreover, there is a possibility of cracking over the entire welded part from the part where the joint strength is reduced. The cause of such a problem is not limited to the oxide film. For example, contamination on the surface of the base material or an artificial coating may be the cause.

  According to the present invention, welding strength is increased by promoting fusion between molten pools in a welding method in which the butted base materials are melted with a laser and the base materials are joined. Moreover, the welding apparatus suitable for this welding method is provided.

  One embodiment of the present invention is a welding method in which end portions of a metal material are melted with a laser beam and joined. In such a welding method, the first butting surface of the first end and the second butting surface of the second end are opposed to each other. In addition, the first laser beam is irradiated onto a first irradiation surface which is a surface of the first end portion and is a surface different from the first abutting surface. Further, the second laser beam is scanned on the second irradiation surface which is the surface of the second end portion and is different from the second butting surface.

  In this welding method, the first laser light and the second laser light are scanned along a welding line that is a center line between the first butted surface and the second butted surface. Are oscillated at equal intervals, and a phase difference is provided in the vibration so that an intensity difference is generated between the first laser beam and the second laser beam.

  In the welding method of the present invention, the intensity of the laser light on both sides of the weld line vibrates with a phase difference. Therefore, the butt surface can be stretched and broken. For this reason, the joint strength of welding can be raised by accelerating | stimulating the fusion of molten pools.

  It is preferable that scanning is performed so that the center of the first laser light on the first irradiation surface and the center of the second laser light on the second irradiation surface are in line symmetry with respect to the welding line. By the said aspect, the left-right asymmetry at the time of solidification can be reduced.

  The phase difference is preferably a phase difference corresponding to half of the period. By this aspect, a more uniform joining can be realized along the weld line direction. During the scanning, when the intensity of one of the first laser beam and the second laser beam takes a maximum value, the other intensity is preferably greater than zero. Even if a period is lengthened by the said aspect, generation | occurrence | production of the location where a base material does not fuse | melt can be suppressed.

  One embodiment of the present invention is a welding apparatus that scans laser light on a first irradiation surface of a metal material and a second irradiation surface of the metal material or another metal material. The welding apparatus includes a light source that emits original laser light and a polarization beam splitter that is a first optical element positioned on the optical path of the original laser light.

  The welding apparatus further includes a polarizing plate positioned on the optical path of the exit side P-polarized light and the exit side S-polarized light in the polarization beam splitter, or on the optical path of the incident side original laser light in the polarization beam splitter.

  The polarizing plate rotates on a plane parallel to the polarizing plate. In the welding apparatus, one of the first irradiation surface and the second irradiation surface is irradiated with the P-polarized light, and the other is irradiated with the S-polarized light.

  The welding apparatus is suitable for carrying out the welding method. By the said aspect, it can make it easy to homogenize the 1st laser beam and the 2nd laser beam in points other than the phase difference of an intense | strong vibration. Furthermore, by separating the original laser light into P-polarized light and S-polarized light, energy loss when obtaining linearly polarized light suitable for the first laser light and the second laser light can be reduced.

  The welding apparatus preferably includes, as the polarizing plate, one polarizing plate positioned on the optical path of the P-polarized light and the S-polarized light. According to the above aspect, it is possible to achieve a cycle having a desired length while maintaining the phase difference with a single polarizing plate. In addition, by guiding to a single polarizing plate, it is easy to make the period of intense vibration the same between the first laser beam and the second laser beam. Furthermore, it is easy to generate a phase difference substantially corresponding to half the period between the first laser beam and the second laser beam.

  It is preferable that the welding apparatus further includes a second optical element positioned on the optical path between the first optical element and the polarizing plate on the optical path of the P-polarized light or the S-polarized light. The second optical element is preferably a mirror, a prism, or a polarization beam splitter. The P-polarized light and the S-polarized light are made parallel by the aspect according to the second optical element, and it is easy to guide them to a single polarizing plate.

  In the welding method of melting the butted base materials with a laser and joining the base materials, it is possible to increase the welding joint strength by promoting the fusion of the molten pools. Moreover, the welding apparatus suitable for this welding method can be provided.

It is a top view of the base material welded with the welding method which concerns on a subject. It is a top view of the base material welded with the welding method which concerns on embodiment. It is an element diagram of the welding apparatus which concerns on an Example. It is a perspective view of the polarizing plate which the welding apparatus which concerns on an Example has. It is a top view of the polarizing plate which the welding apparatus which concerns on an Example has. It is a top view which shows the intensity | strength change of the laser beam based on an Example. It is an element diagram of the welding apparatus which concerns on the deformation | transformation of an Example. It is a top view of the base material welded with the welding method which concerns on a reference example. It is a perspective view of the base material welded with the welding method which concerns on a reference example.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description is omitted. FIG. 2 is a plan view of the base materials 10a and 10b to be welded by the welding method according to the embodiment.

  As shown in FIG. 2, in the welding method of this embodiment, the base material 10a, 10b is welded by irradiating the beam pair which consists of two laser beams 23a, 23b. Base materials 10a and 10b are both metal materials. The base material 10a has an end portion 14a that is a first end portion. The base material 10b has an end portion 14b which is a second end portion. The end portions 14a and 14b are butted together for welding.

  As shown in FIG. 2, the end portion 14a has a butting surface 17a which is a first butting surface. The end portion 14b has a butting surface 17b that is a second butting surface. These are opposed so that the butted surfaces 17a and 17b sandwich the weld line 13a. The end portions 14a and 14b are joined around the weld line 13a. The weld line 13a is a set of intermediate points between the butt surfaces 17a and 17b. That is, the weld line 13a is the center line of the butt surfaces 17a and 17b.

  As shown in FIG. 2, the end portions 14a and 14b have irradiation surfaces 24a and 24b in the vicinity of the butting surfaces 17a and 17b, respectively. Irradiation surface 24a, 24b is the surface which edge part 14a, 14b has, Comprising: It is a surface different from the abutting surface 17a, 17b. The irradiation surfaces 24a and 24b are first and second irradiation surfaces, respectively. The irradiation surfaces 24a and 24b are part of the base materials 10a and 10b. The irradiation surfaces 24a and 24b are the surfaces of the end portions 14a and 14b, respectively, on the same side of the base materials 10a and 10b that are abutted. FIG. 2 is a plan view of the base materials 10a and 10b, particularly toward the irradiation surfaces 24a and 24b. One of the irradiation surfaces 24a and 24b is located on one and the other of the both sides of the welding line 13a.

  A laser beam 23a, which is a first laser beam, is irradiated onto the irradiation surface 24a. Further, the laser beam 23b, which is the second laser beam, is irradiated onto the irradiation surface 24b. However, it is preferable not to irradiate the laser beams 23a and 23b between the abutting surfaces 17a and 17b. This is to prevent the laser beams 23a and 23b from being irradiated to the portions where the laser beams 23a and 23b are not scheduled to be irradiated due to the laser beams 23a and 23b passing through the gap 13b.

  The gap 13b shown in FIG. 2 is often generated due to tolerances or roughness of the butted surfaces 17a and 17b. The gap 13b tends to increase as the abutting surfaces 17a and 17b become longer. For this reason, the welding method of this embodiment is suitable for welding a base material having a large tolerance, a base material having a lot of roughness, and a base material having a long butt surface.

  As shown in FIG. 2, the laser beams 23a and 23b are scanned while being parallel along the weld line 13a. The laser beams 23a and 23b travel along the traveling directions 16a and 16b. The traveling directions 16a and 16b are parallel to the welding line 13a located at the center of the gap 13b.

  In this specification, the term “scanning” means that the irradiation position of the laser beam moves on the surface of the base material. Further, unless otherwise specified in the present specification, the term “scan” is not limited by the means for performing “scan”. That is, “scanning” can be performed by an operation of moving a laser beam irradiation source, an operation of an optical element for guiding the laser beam, an operation of a base material, other operations, or a combination thereof.

  Spots 19a, 20a, and 21a shown in FIG. 2 represent the irradiation positions of the laser beam 23a. The spots 19a, 20a, and 21a are arranged in time order from the spot 19a. Similarly, the spots 19b, 20b, and 21b represent the irradiation positions of the laser light 23b. The spots 19b, 20b, and 21b are arranged in order of time from the spot 19b.

  Spots 20a and 20b shown in FIG. 2 represent irradiation positions at the same time point. The same applies to each combination of the spots 19a and 19b and the spots 21a and 21b. FIG. 2 particularly shows the time when the laser beams 23a and 23b reach the spots 20a and 20b.

  As shown in FIG. 2, the spots 20a and 20b are arranged along the weld line 13a without being back and forth. In other words, it is preferable to scan the laser beams 23a and 23b so that the respective irradiation centers 26a and 26b of the laser beams 23a and 23b are axisymmetric with respect to the welding line 13a. With such an embodiment, the left-right asymmetry of the joint after solidification can be reduced.

  As shown in FIG. 2, the irradiation center line 34 is a straight line passing through the irradiation centers 26a and 26b. The above aspect can also be expressed as scanning the laser beams 23a and 23b so that the irradiation center line 34 is substantially orthogonal to the welding line 13a. If the welding line 13a is substantially straight, it is preferable to scan the laser beams 23a and 23b at an equal speed.

  As shown in FIG. 2, the end portion 14a is continuously melted along the weld line 13a with the laser beam 23a including the spots 19a, 20a, 21a as the center. Further, the end portion 14b is continuously melted along the weld line 13a around the irradiation position of the laser beam 23b including the spots 19b, 20b, and 21b.

  As shown in FIG. 2, the melted end portions 14a and 14b become molten pools 22a and 22b, respectively. The molten pools 22a and 22b overlap each other and further melt. After the end portions 14a and 14b are melted together, the end portions 14a and 14b are solidified. For this reason, end part 14a, 14b is joined. Joining by melting, melting and solidification is performed continuously along the weld line 13a.

  In this embodiment, the intensity of the laser beams 23a and 23b is vibrated as shown in FIG. The intensity of the laser beam 23a is maximum at the spot 20a and minimum at the spots 19a and 21a. The intensity of the laser beam 23b is minimum at the spot 20b and maximum at the spots 19b and 21b.

  In the present embodiment, the period of vibration of the intensity of the laser beams 23a and 23b shown in FIG. 2 has the same length. Further, a phase difference is provided in the vibration between the laser beams 23a and 23b. Such a phase difference causes an intensity difference between the intensities of the laser beams 23a and 23b.

  The laser beams 23a and 23b shown in FIG. 2 have a phase difference in intensity. For this reason, when the laser beams 23a and 23b are scanned, the welding center line 25 between the molten pool 22a and the molten pool 22b reciprocates around the welding line 13a. The fusion center line 25 is a center line between the molten pools 22a and 22b continuously melted along the weld line 13a.

  The fusion center line 25 will be described in detail with reference to FIG. In the spots 19a and 19b, the intensity of the laser beam 23a is smaller than that of the laser beam 23b. Therefore, the energy of the laser light projected on the irradiation surface 24a is smaller than that of the irradiation surface 24b. For this reason, the molten pool 22a is smaller than the molten pool 22b. Therefore, the fusion center line 25 approaches the end portion 14a with respect to the weld line 13a.

  In the spots 20a and 20b shown in FIG. 2, the intensity of the laser beam 23a is greater than that of the laser beam 23b. Therefore, the energy of the laser light projected on the irradiation surface 24a is larger than that of the irradiation surface 24b. For this reason, the molten pool 22a is larger than the molten pool 22b. Therefore, the fusion center line 25 approaches the end portion 14b side with respect to the weld line 13a.

  The welding center line 25 shown in FIG. 2 advances from the end portion 14a side to the end portion 14b side between the spots 19a and 19b and the spots 20a and 20b, and crosses the welding line 13a. Similarly, the fusion center line 25 advances from the end 14b side to the end 14a side between the spots 20a and 20b and the spots 21a and 21b, and crosses the weld line 13a.

  The fusion center line 25 shown in FIG. 2 is longer than the weld line 13a. Therefore, the butt surfaces 17a and 17b are broken so as to be stretched at any location in or around the fusion center line 25. In a preferred embodiment, the abutting surfaces 17a and 17b are melted into the molten pools 22a and 22b.

  Since the melting points of the oxide films 18a and 18b shown in FIG. 2 are high, it is difficult to melt them with a laser beam. Therefore, it is effective to destroy the oxide films 18a and 18b with stress. By the welding method of this embodiment, the abutting surfaces 17a and 17b are stretched, and at the same time, the oxide films 18a and 18b are destroyed. Therefore, the molten pools 22a and 22b melt well. For this reason, high joint strength can be obtained by using the welding method of this embodiment.

  In the welding method shown in FIG. 2, high bonding strength can be obtained without removing the oxide films 18a and 18b in advance. Further, the welding speed can be increased by superimposing the pulse laser as compared with the method of removing the oxide films 18a and 18b. Further, in the above welding method, not only the oxide film but also dirt such as fats and oils can be broken to promote fusion between the molten pools 22a and 22b.

  It is preferable that the phase difference between the intensities of the laser beams 23a and 23b shown in FIG. 2 substantially corresponds to half the period of vibration. According to the figure, the intensity of the laser beam 23a is a minimum value at the spots 19a and 21a. At this time, the intensity of the laser beam 23b has a maximum value at the spots 19b and 21b. The intensity of the laser beam 23a has a maximum value at the spot 20a. At this time, the intensity of the laser beam 23b has a minimum value at the spot 20b. According to this aspect, a more uniform joining can be realized along the direction of the weld line 13a.

  Further, during the scanning shown in FIG. 2, when the intensity of one of the laser beams 23a and 23b takes a maximum value, the intensity of the other may be greater than zero. According to the figure, the intensity of the laser beam 23a is greater than 0 at the spots 19a and 21a. The intensity of the laser beam 23b is greater than 0 at the spot 20b. When welding is performed while scanning with laser light, the base material may not be melted if the intensity is close to zero for a long time. However, if it is the said aspect, even if it makes the intensity | strength fluctuation | variation period long, generation | occurrence | production of the location where a base material does not fuse | melt can be suppressed.

  In addition, during the scanning shown in FIG. 2, if the period of intensity fluctuation is short, the fluctuation of the size of the molten pool may be small. That is, if the intensity of the laser beams 23a and 23b is changed before either one of the molten pools 22a and 22b becomes sufficiently large, the molten pools 22a and 22b become substantially constant in size. In this case, the fusion center line 25 is linear, and it is difficult to obtain the effect of extending and destroying the butted surfaces 17a and 17b. An example of how to obtain a preferable period length in the embodiments described later will be described.

  In addition, during the scanning shown in FIG. 2, the total intensity of the laser beams 23a and 23b is preferably constant. At this time, the total amount of molten metal in the molten pools 22a and 22b does not vary greatly during scanning. According to this aspect, a more uniform joining can be realized along the direction of the weld line 13a.

  On the other hand, during the scanning shown in FIG. 2, the intensity of the laser beams 23a and 23b may become zero at a predetermined timing. Such a mode includes a mode in which a pulse laser is used as the laser beams 23a and 23b. Since welding according to this embodiment is performed continuously, the intensity of the laser beams 23a and 23b can be reduced to zero as long as the molten pools 22a and 22b overlap each other and further melt. In a predetermined case, the period of fluctuation in intensity needs to be sufficiently short.

  The metal material constituting the base materials 10a and 10b shown in FIG. 2 may be pure aluminum or an aluminum alloy. The metal material may be a steel material provided with a galvanized film such as a galvanized steel sheet. The base materials 10a and 10b may be made of the same metal or different metals. Such a galvanized film is also broken in the same manner as the above oxide film.

  In FIG. 2, the laser beams 23a and 23b are shown to move during scanning. On the other hand, the base materials 10a and 10b can be transported along the welding line 13a to scan the laser beam. In this case, the conveying direction of the base materials 10a and 10b is opposite to the traveling directions 16a and 16b of the laser beams 23a and 23b.

  Each of the base materials 10a and 10b shown in FIG. 2 may be previously joined to other base materials. Further, the base material joined by the method according to the present embodiment may be further joined with other base materials. That is, by joining the base materials one after another by the method according to the present embodiment, three or more base materials can be joined to form a continuous member.

  In the above welding method, two base materials composed of the base materials 10a and 10b were joined. However, as shown in FIG. 7 to be described later, one base material 10c may have two end portions 14c and 14d. The end portions 14c and 14d are abutted and joined in accordance with the welding method. After joining, a cylindrical metal material is formed.

  Laser light 23a and 23b may be generated as shown in FIG. That is, after the laser beam 41, which is a coherent original laser beam, is separated into two laser beams by a beam splitter or the like, the two laser beams may be used as either one of the laser beams 23a and 23b, respectively. This aspect makes it easy to homogenize the laser beams 23a and 23b at points other than the phase difference of the strong vibration. The laser beams 23a and 23b may be obtained from separate light sources.

  In the following examples, a welding apparatus suitable for carrying out the welding method of the above embodiment is shown, and further, a welding method using such an apparatus is shown. Moreover, the superior point of the welding method of this embodiment is demonstrated in detail, referring a reference example.

[1. Welding Device and Optical System] FIG. 3 is an element diagram of the welding device 27 according to the embodiment. The welding device 27 is for guiding laser beams 23a and 23b to the surfaces of the base materials 10a and 10b that are abutted with each other with the welding wire 13a interposed therebetween. The welding device 27 includes a transporter 29 and an optical system 40. The optical system 40 includes a polarizing beam splitter 30, a prism 36, a light source 45, a convex lens 47, and a polarizing plate 50a.

[2. Light Source] A light source 45 shown in FIG. 3 emits a laser beam 41 that is an original laser beam. The laser light 41 is circularly polarized light or elliptically polarized light. The laser beam 41 is preferably a CW (Continuous wave) laser. Since welding is performed over a predetermined time, the CW laser can efficiently obtain the energy required for welding compared to the pulse laser on such a time scale.

  The light source 45 shown in FIG. 3 may emit the laser beam 41 after optically processing the coherent laser beam in advance. The light source 45 may be a composite optical system including a laser light source and an optical element that performs optical processing.

  The laser beam 41 shown in FIG. 3 may be a pulse laser. The pulse laser can prevent the occurrence of voids or spatter. However, a pulse laser having a frequency that is high enough not to substantially affect the vibration of the intensity of the laser beams 23 a and 23 b is suitable for the laser beam 41.

[3. First Optical Element] The polarization beam splitter 30 shown in FIG. 3 is a first optical element located on the optical path of the laser light 41. In this specification, the laser beam 41 is a laser beam on the optical path between the light source 45 and the polarization beam splitter 30.

  The polarization beam splitter 30 shown in FIG. 3 separates the laser light 41 into S-polarized light 42a and P-polarized light 42b. The S-polarized light 42a and the P-polarized light 42b that pass through a predetermined optical element and are emitted from the optical system 40 can be used as the laser beams 23a and 23b described in the above embodiments, respectively. In this specification, the laser beam 41 is a laser beam on the optical path between the light source 45 and the polarization beam splitter 30.

  The polarizing beam splitter 30 shown in FIG. 3 is preferably of a prism junction type. With this aspect, the optical system 40 can be made compact. The polarization beam splitter 30 may be a plate type.

  As shown in FIG. 3, the polarizing beam splitter 30 includes side surfaces 32a, 32b, 32c, and 32d in this order. The side surfaces 32a and 32c are located facing each other. The side surfaces 32b and 32d are located facing each other.

  As shown in FIG. 3, the polarization beam splitter 30 includes prisms 31a and 31b. The prism 31a includes side surfaces 32a and 32d. The prism 31b includes side surfaces 32b and 32c. The prisms 31a and 31b are joined at the inclined surfaces. Such inclined surfaces are collectively expressed as a polarization plane 33. For example, a dielectric polarizing film is formed on the polarizing surface 33.

  As shown in FIG. 3, the laser beam 41 enters the polarization beam splitter 30 from the side surface 32a and travels through the prism 31a. The laser light 41 incident on the polarization beam splitter 30 is preferably circularly polarized light or elliptically polarized light.

  As shown in FIG. 3, the S-polarized light 42 a is generated by reflecting a part of the laser light 41 on the polarization plane 33. The S-polarized light 42a travels in the prism 31a and is emitted from the side surface 32d. The P-polarized light 42 b is generated by transmitting part of the laser light 41 through the polarization plane 33. The P-polarized light 42b travels in the prism 31b and exits from the side surface 32c.

[4. Second Optical Element] The prism 36 shown in FIG. 3 is an optical element located on the exit side of the S-polarized light 42 a in the polarization beam splitter 30. The prism 36 is located on the optical path of the S-polarized light 42a. The prism 36 is installed for the purpose of bending the optical path of the S-polarized light 42a substantially by 90 degrees. The prism 36 is located on the optical path of the S-polarized light 42a and between the polarizing beam splitter 30 and the polarizing plate 50a.

  As shown in FIG. 3, the prism 36 includes side surfaces 37 a and 37 b and an inclined surface 38. The side surface 37a faces the side surface 32d. The S-polarized light 42a enters from the side surface 37a and travels through the prism 36. The S-polarized light 42a is reflected by the inclined surface 38, travels through the prism 36, and exits from the side surface 37b.

  The prism 36 shown in FIG. 3 makes it easy to guide the S-polarized light 42a and the P-polarized light 42b to the single polarizing plate 50a after making them parallel. The prism 36 may be a 45-degree right-angle prism that performs total reflection on the slope 38 according to a critical angle, or may be a 45-degree right-angle reflection prism having a reflection film on the slope 38.

  An optical path 35 shown in FIG. 3 is an optical path of S-polarized light 42 a traveling from the polarization beam splitter 30 to the prism 36. An optical path 35 is an optical path of the S-polarized light 42a until the S-polarized light 42a is reflected by the polarization plane 33 and further reflected by the inclined surface 38. When the side surface 32d and the side surface 37a are in contact with each other, the size of the optical path 35 can be minimized.

  By reducing the size of the optical path 35 shown in FIG. 3, the S-polarized light 42a and the P-polarized light 42b can be brought close to each other. By bringing the S-polarized light 42a and the P-polarized light 42b close to each other, the irradiation centers 26a and 26b of the laser beams 23a and 23b can be easily brought close to the welding line 13a.

  As shown in FIG. 3, it is preferable that the optical path 35 is orthogonal to the weld line 13a when viewed in plan toward the irradiation surfaces 24a and 24b. This aspect facilitates making the irradiation center line 34 substantially orthogonal to the welding line 13a. In this case, the optical path 35 is substantially parallel to the irradiation center line 34.

  The prism 36 shown in FIG. 3 may be replaced by any other prisms, mirrors, polarizing beam splitters, and other optical elements that can realize the above functions. Such a polarizing beam splitter may be equivalent to the polarizing beam splitter 30. Further, the polarizing beam splitter 30 and the prism 36 may be collectively replaced with a rhombus polarizing beam splitter.

[5. Polarizing Plate] The polarizing plate 50 a shown in FIG. 3 is located on the exit side of the S-polarized light 42 a and the P-polarized light 42 b in the polarizing beam splitter 30. The polarizing plate 50a is located on any optical path of the S-polarized light 42a and the P-polarized light 42b. Both the S-polarized light 42a and the P-polarized light 42b are transmitted through the single polarizing plate 50a. The S-polarized light 42a passes through the prism 36 before passing through the polarizing plate 50a.

  As shown in FIG. 3, the polarizing plate 50a is preferably substantially orthogonal to the optical paths of the S-polarized light 42a and the P-polarized light 42b. According to this aspect, it is possible to realize the same period of intensity vibration between the laser beams 23a and 23b by simple control. Similarly, it is possible to realize a phase difference of strong vibration between the laser beams 23a and 23b with simple control.

  FIG. 4 is a perspective view of the polarizing plate 50 a included in the welding device 27. The polarizing plate 50a is orthogonal to the optical paths of the S-polarized light 42a and the P-polarized light 42b. The S polarized light 42a and the P polarized light 42b are linearly polarized light. For example, when viewed in plan with respect to the polarizing plate 50a, the polarization direction 49a of the S-polarized light 42a bent by the prism 36 is orthogonal to the optical path 35 (FIG. 3). On the other hand, the polarization direction 49b of the P-polarized light 42b is parallel to the optical path 35 (FIG. 3). On the same plane, the polarization direction 49a and the polarization direction 49b form a right angle.

  As shown in FIG. 4, the transmittance of the polarizing plate 50a of the S-polarized light 42a and the P-polarized light 42b can be changed by changing the polarization direction of the polarizing plate 50a. At the time shown in the figure, the polarization direction of the polarizing plate 50a is parallel to the polarization direction 49a and orthogonal to the polarization direction 49b.

  The loss of energy when the S-polarized light 42a shown in FIG. 4 passes through the polarizing plate 50a is minimal. On the other hand, the loss of energy when the P-polarized light 42b passes through the polarizing plate 50a is the largest. Therefore, the P-polarized light 42b does not substantially pass through the polarizing plate 50a.

  As shown in FIG. 4, the polarizing plate 50a preferably rotates about an axis 52 orthogonal to the polarizing plate 50a. The polarizing plate 50a can be made small because the axis 52 is between the S-polarized light 42a and the P-polarized light 42b.

  The rotation angle of the rotation of the polarizing plate 50a shown in FIG. 4 may be smaller than 90 degrees, 360 degrees or less, and larger than 360 degrees. The rotation may be continuous rotation in one direction or reciprocation.

  By rotating the polarizing plate 50a shown in FIG. 4 as described above, it is easy to keep the sum of the laser beams 23a and 23b constant while vibrating the intensity of the laser beams 23a and 23b. Further, the phase difference can be substantially equivalent to half of the period.

  As shown in FIGS. 3 and 4, the polarizing plate 50a is a single polarizing plate, so that the period of intensity vibration can be made the same between the laser beams 23a and 23b. Furthermore, a phase difference corresponding to substantially half of the cycle can be generated between the laser beams 23a and 23b. Such an effect can be brought about only by controlling the planar movement of the polarizing plate 50a.

  FIG. 5 is a plan view of the polarizing plate 50 a included in the optical system 40. The polarizing plate 50a may perform continuous rotation 53. During the scanning of the laser beam, it is preferable that the continuous rotation 53 has a constant speed. When the polarizing plate 50a rotates once, the intensity of the laser beams 23a and 23b vibrates in two cycles. According to such an embodiment, the period of vibration of the intensity of the laser beams 23a and 23b can be kept constant. The continuous rotation 53 may be reversed.

  As shown in FIG. 5, the polarizing plate 50 a may perform reciprocal rotation 56. The reciprocating rotation 56 is performed so that the polarization direction of the polarizing plate 50a reciprocates around the reciprocating center 57. The reciprocating center 57 forms an angle of 45 degrees with the polarization direction 49a of the S-polarized light 42a and the polarization direction 49b of the P-polarized light 42b. According to such an embodiment, it is possible to reduce the bias of the total energy amount received from the laser light between the base materials 10a and 10b.

  The maximum reciprocal angle in the reciprocating rotation 56 shown in FIG. 5 is preferably smaller than 90 degrees. According to this aspect, when the intensity of one of the laser beams 23a and 23b during scanning takes a maximum value, the intensity of the other can be made larger than zero.

  The reciprocating rotation 56 shown in FIG. 5 preferably has a constant cycle. According to such an embodiment, the period of vibration of the intensity of the laser beams 23a and 23b can be kept constant. By limiting the maximum reciprocal angle, the maximum and minimum values of the intensity of the S-polarized light 42a and the P-polarized light 42b can be controlled. The reciprocating rotation 56 may or may not have a predetermined stationary time when turning back the rotation direction.

  Returning to FIG. The polarizing plate 50 a may be replaced with a polarizing plate 50 b located between the light source 45 and the polarizing beam splitter 30. The polarizing plate 50 b is located on the incident side in the polarizing beam splitter 30. The polarizing plate 50b is located on the optical path of the laser beam 41. The polarizing plate 50 b is preferably substantially orthogonal to the optical path of the laser beam 41. The polarizing plate 50b can provide the same effect as the single polarizing plate 50a.

  As shown in FIG. 3, the convex lens 47 is positioned on the optical path of the S-polarized light 42 a that has passed through the prism 36. The S-polarized light 42a that has passed through the convex lens 47 is guided to the irradiation surface 24a of the welding line 13a as laser light 23a. The convex lens 47 is positioned on the optical path of the P-polarized light 42 b that has passed through the polarization beam splitter 30. The P-polarized light 42b that has passed through the convex lens 47 is guided to the irradiation surface 24b as laser light 23b.

  The laser beams 23a and 23b guided as shown in FIG. 3 are applied to the spots 20a and 20b on the irradiation surfaces 24a and 24b. Therefore, the distance between the irradiation centers 26 a and 26 b of the laser beams 23 a and 23 b can be made narrower than the optical path 35 by the convex lens 47.

  The convex lens 47 shown in FIG. 3 may be a plurality of lenses positioned on the optical paths of the S-polarized light 42a and the P-polarized light 42b. The convex lens 47 may be replaced with an optical element or two or more optical element groups that can converge the S-polarized light 42a and the P-polarized light 42b so as to approach each other. For example, it may be replaced with a prism or a prism group.

[6. Other Components] The positional relationship between the S-polarized light 42a and the P-polarized light 42b may be switched by inverting the optical system 40 in FIG. That is, the S-polarized light 42a may be the laser light 23b, and the P-polarized light 42b may be the laser light 23a. The laser beams 23a and 23b may be exchanged by crossing each other. Further, the S-polarized light 42a and the P-polarized light 42b may be interchanged with each other.

  A transporter 29 shown in FIG. 3 transports the base materials 10a and 10b in the transport direction 28 along the weld line 13a. The transport direction 28 is opposite to the traveling directions 16a and 16b. The carrier 29 can scan the laser beams 23a and 23b. The optical system 40 may be transported in the same direction as the traveling directions 16a and 16b. The optical system 40 may scan the laser beams 23a and 23b by sweeping the laser beams 23a and 23b.

  As shown in FIG. 3, the laser light 41 can be bent by a mirror 46 and guided to the polarization beam splitter 30. By replacing the mirror 46 with a prism, the change in the polarization state of the laser light 41 can be reduced.

  In FIG. 3, the mirror 46 may be omitted if the light source 45 is installed directly above the polarizing beam splitter 30 toward the polarizing beam splitter 30. On the other hand, the mirror 46 increases the degree of freedom of the installation location of the light source 45 and the polarization beam splitter 30. The angle and direction of the mirror 46 are not limited. A plurality of mirrors 46 may exist on the optical path of the laser beam 41. In addition, another optical element may be arranged in place of the mirror 46 to change the characteristics of the laser light 41. However, it is preferable that the effects of the polarizing beam splitter and the polarizing plate are not impaired.

[7. Operation and Effect] The welding apparatus 27 shown in FIG. 3 can vibrate the intensity of the laser beams 23a and 23b with a phase difference by the operation of the polarizing plate 50a (FIG. 2). For this reason, it is suitable for implementation of the welding method of the said embodiment.

[8. Welding Method] A welding method using the welding device 27 will be described with reference to FIG. First, the ends of the base materials 10a and 10b are brought into contact with each other. At this time, the butted surfaces are opposed to each other with the welding line 13a interposed therebetween. Next, when the laser beam 41 is emitted from the light source 45, the laser beam 41 is guided as follows.

  As shown in FIG. 3, the laser beam 41 is separated into S-polarized light 42a and P-polarized light 42b by a beam splitter. Next, the separated S-polarized light 42a and P-polarized light 42b are transmitted through the polarizing plate 50a. Alternatively, the laser beam 41 is transmitted through the polarizing plate 50b before the laser beam 41 is separated.

  As shown in FIG. 3, the P-polarized light 42b and the S-polarized light 42a are set to one of the laser beams 23a and 23b, respectively. One of the polarizing plates is rotated on a plane parallel to the polarizing plate 50a or the polarizing plate 50b. Thereby, the intensity | strength of laser beam 23a, 23b is vibrated with the period of the same length. Furthermore, a phase difference is provided in the vibration.

  As shown in FIG. 3, the laser beams 23a and 23b are guided to the irradiation surfaces 24a and 24b, respectively. The laser beams 23a and 23b are scanned while being parallel along the weld line 13a. The base materials 10a and 10b are melted by the laser beams 23a and 23b that vibrate with strength, and butt welding is performed.

  This welding method has an excellent effect other than the effects described in the embodiment. As shown in FIG. 3, the laser beam 41 is separated into S-polarized light 42a and P-polarized light 42b. This has the effect of reducing energy loss when obtaining linearly polarized light suitable for the laser beams 23a and 23b. For example, the effect is remarkably high as compared with the case where the laser beam 41 is separated by the non-polarizing beam splitter instead of the polarizing beam splitter 30 and the desired linearly polarized light is obtained by two polarizing plates.

[9. Intensity oscillation period or frequency] As described above, the intensity oscillation period of the laser light affects the formation of the weld pool and the weld centerline. For this reason, it is necessary to appropriately select the period of vibration of the intensity of the laser beam. It is also necessary to make the relationship between the period and the scanning speed of the laser light appropriate. Hereinafter, the relationship between the scanning speed of the laser beam and the period of vibration of the intensity will be described with reference to FIG. 6, and a method for obtaining a suitable period or frequency will be described.

  FIG. 6 is a diagram showing changes in the intensity of laser light. The spots 20a, 20b, 21a, and 21b are spots equivalent to the spots shown in FIG. That is, the intensity of the laser beam is maximum at the spots 20a and 21b. Further, the intensity of the laser beam is minimal at the spots 21a and 20b.

  Spots 60a and 60b shown in FIG. 6 are spots located between the maximum spot and the minimum spot. It is assumed that the intensity of laser light applied to each of the spots 60a and 60b is equal. The spots 59a, 59b, 61a, 61b are the same spots as the spots 60a, 60b.

  As shown in FIG. 6, the intensity of the laser beam vibrates for one period between the spots 59a and 59b and 61a and 61b. Let T be the period length. Further, the speed of the scanned laser beam is assumed to be v. During scanning, v shall be equal on both sides of the weld line 13a. The distance L by which the laser beam is scanned in the time of 1 × T is expressed by the formula: L = vT.

  The length of the molten pool 62a during scanning with the laser beam shown in FIG. D represents the length in the direction parallel to the weld line 13a. In the figure, the length D of the molten pool 62a is represented by spots 59a and 61a.

  In this embodiment, the period T is preferably determined so as to satisfy D = L. However, D vibrates depending on the vibration of the intensity of the laser beam. Therefore, T may be determined such that the time average Dv of D is equal to L.

  Further, T may be determined so as to satisfy Di ≦ L ≦ Dx. Here, Di represents the minimum value of D that vibrates. Dx represents the maximum value of D that vibrates. Alternatively, T may be determined so as to satisfy L = Di or L = Dx. Further, D may be replaced with the length of the molten pool 62b being scanned. Further, D may be replaced with the average length of the molten pools 62a and 62b.

  Hereinafter, the frequency f (= 1 / T) of the vibration of the intensity of the laser beam is obtained using a specific example. In a specific example, Da = 5 mm and v = 3 m / min. At this time, since 1 / T = v / D, f = 600 (times / minute).

  In this embodiment, the speed v can be set to, for example, 1 m / min or more and 30 m / min or less. The speed v can be set to 1 m / min or more and 2 m / min or less. The speed v can be 10 m / min or more or 20 m / min or more.

  The frequency f can be 100 times / min or more and 12000 times / min or less. The frequency f can be 400 times or less. If the speed v is 1 m / min or more and 30 m / min or less, the frequency f can be 200 times / min or more and 6000 times / min or less.

  Alternatively, when the speed v is 20 m / min or more and 30 m / min or less, the frequency f is preferably 4000 times / min or more and 6000 times / min or less. In this manner, the bonding strength can be increased as described above while increasing the bonding speed.

  D can be arbitrarily determined depending on the material of the base material, the time average intensity of the laser beam, the speed v, the distance from the butt surface to the irradiation center, and the like. The appropriate D can be determined empirically.

[10. Modification] FIG. 7 is an element diagram showing a welding apparatus 67 according to a modification. Each component of the welding device 27 shown in FIG. 3 may be appropriately replaced with each component of the welding device 67. The difference between the welding device 67 and the welding device 27 will be described below.

  As shown in FIG. 7, the welding device 67 includes an optical system 70. In the polarization beam splitter 30 and the prism 36, the side surface 32d and the side surface 37a do not face each other. The side surface 37a faces the side surface 32c. On the other hand, the side surface 32d faces a polarizing plate 50d described later. Therefore, P-polarized light enters the prism 36 and S-polarized light does not enter the prism 36.

  As shown in FIG. 7, the P-polarized light 42 c is generated by transmitting part of the laser light 41 through the polarization plane 33. The S-polarized light 42 d is generated by reflecting a part of the laser light 41 on the polarization plane 33. The prism 36 is located on the optical path of the P-polarized light 42c. The P-polarized light 42c enters from the side surface 37a and travels through the prism 36. The P-polarized light 42c is reflected by the inclined surface 38, travels through the prism 36, and exits from the side surface 37b.

  An optical path 75 shown in FIG. 7 is an optical path of the P-polarized light 42 c that travels from the polarization beam splitter 30 to the prism 36. An optical path 75 is an optical path of the P-polarized light 42 c until the P-polarized light 42 c passes through the polarization plane 33 and is reflected by the inclined surface 38. When the side surface 32c and the side surface 37a are in contact with each other, the size of the optical path 75 can be minimized. The positional relationship between the optical path 75 and other components is in accordance with the optical path 35 shown in FIG.

  As shown in FIG. 7, the optical system 70 includes a polarizing plate 50c for P-polarized light and a polarizing plate 50d for S-polarized light instead of the polarizing plate 50a. The polarizing plate 50c is located on the optical path of the P-polarized light 42c and is not located on the optical path of the S-polarized light 42d. The polarizing plate 50d is located on the optical path of the S-polarized light 42d and is not located on the optical path of the P-polarized light 42c. The polarizing plates 50c and 50d are preferably rotated similarly to the polarizing plate 50a. The rotations of the polarizing plates 50c and 50d are preferably synchronized. The rotations of the polarizing plates 50c and 50d may be opposite to each other.

  Instead of the arrangement of the prisms 36 in FIG. 7, the prisms 36 may be positioned on the optical path of the S-polarized light 42a as shown in FIG. In this case, the polarizing plate 50 c may be positioned on the optical path of the optical path 35.

  Further, instead of the polarizing plates 50c and 50d shown in FIG. 7, a polarizing plate 50a shown in FIG. 3 may be used. In this case, the polarizing plate 50a is positioned on any optical path of the P-polarized light 42c and the S-polarized light 42d that pass through the prism 36.

  As shown in FIG. 7, the convex lens 47 is positioned on the optical path of the P-polarized light 42 c that has passed through the prism 36. The convex lens 47 is positioned on the optical path of the S-polarized light 42d that has passed through the polarization beam splitter 30. The P-polarized light 42c and the S-polarized light 42d are referred to as laser beams 23c and 23d, respectively.

  FIG. 7 further shows a modification of the welding method. In such a welding method, the respective end portions of one base material 10c having two end portions 14c and 14d are brought into contact with each other. Next, the laser beams 23c and 23d are guided to the spots 20c and 20d on the irradiation surfaces 24c and 24d. The spots 20c and 20d are equivalent to the spots 20a and 20b shown in FIG. 3, but the polarization direction of the linearly polarized light to be irradiated is reversed.

  As shown in FIG. 7, the end portions 14c and 14d are melted and joined with laser beams 23c and 23d. By this joining, the base material 10c can be formed into a cylindrical structure. The laser beams 23c and 23d are not irradiated to the gap 13b according to the above embodiment. Therefore, it is possible to avoid irradiating the inside of the cylindrical structure with a laser beam having an intensity for melting the base material 10c.

  The benefits of such operational effects are not limited to the manufacture of cylindrical structures. For example, even when another member is joined to a cylindrical or container-like structure, it is possible to avoid irradiation with laser light. For example, it is preferable to use the welding method of this embodiment for sealing a battery casing. This is because, when the battery casing is sealed, irradiating the casing with laser light may damage the internal components of the battery.

  As shown in FIG. 7, the laser beam 73 may be irradiated to the spot 74. Here, the laser beam 73 is not so strong as to melt the base material 10c. This is because the laser beam 73 enters the gap between the end portions 14c and 14d and reaches the space on the back side of the irradiation surfaces 24c and 24d.

  The spot 74 includes the spots 20c and 20d. Therefore, the laser beam 73 further imparts energy to the molten pool generated by the energy of the laser beams 23c and 23d. For this reason, solidification of the molten pool is delayed. On the other hand, when the laser beam 73 is not irradiated, the molten pool may solidify rapidly, resulting in voids or cracks. The laser beam 73 is suitable for solving such a problem.

  A welding device 67 shown in FIG. On the other hand, when the laser beam 73 is not used, the welding device 67 can be a simpler device. In addition, adjustment of the position between the laser beam 73 and the laser beams 23c and 23d and adjustment of the intensity thereof are not necessary.

  As shown in FIG. 7, the butting surfaces of the end portions 14c and 14d may be bent while facing each other. That is, the welding line 13c may be bent so as to draw an arc. At this time, the traveling directions 16c and 16d of the laser beams 23c and 23d continuously change along the weld line 13c.

  In the embodiment described above, the traveling speed v of the scanned laser beam is the same on both sides of the weld line. When the welding line 13c is bent as described above, the average of the traveling speeds of the laser beams 23c and 23d may be treated as v, and the period T or the frequency f of the strong vibration may be determined. Also, the smaller one of the traveling speeds of the laser beams 23c and 23d on both sides may be set as v.

[11. Reference Example] FIG. 8 is a plan view of base materials 10a and 10b to be welded by a welding method according to a reference example. Such a welding method is characterized in that the laser beam spots 81a and 81b alternately proceed (weave) along the weld line 13a.

  The laser beam spots 81a and 81b shown in FIG. 8 travel on the base materials 10a and 10b. Here, the positional relationship between the laser beam spots 81a and 81b in the direction parallel to the weld line 13a changes periodically. The mode of the laser beam spots 81a and 81b can be realized by an optical diffraction element (DOE) 80, for example. In this example, the optical diffraction element 80 swings to change the positions of the laser beam spots 81a and 81b passing therethrough as described above.

  When the laser beam spot 81a shown in FIG. 8 is positioned behind the laser beam spot 81b, the welding center line 85b crosses the weld line 13a from the base material 10b side to the base material 10a side. On the other hand, since the laser beam spot 81a is positioned in front of the laser beam spot 81b, the welding center line 85c crosses the weld line 13a from the base material 10a side to the base material 10b side.

  The fusion center lines 85b and 85c shown in FIG. 8 are extended more than the fusion center line 85a. Accordingly, shear stress is generated on the abutting surfaces 17a and 17b in the molten pools 82a and 82b. Therefore, the oxide films 18a and 18b are stretched and destroyed. Therefore, the molten pools 82a and 82b melt well with each other. For this reason, base materials 10a and 10b are joined well.

  The welding method shown in FIG. 8 has several problems, unlike the welding method according to the above embodiment. FIG. 9 is a perspective view of a base material to be welded by the welding method according to this reference example. Not only the present reference example, the base materials 10a and 10b are not necessarily plates having a uniform thickness as a whole. For example, the upper surfaces of the base materials 10a and 10b may be raised in the vicinity of the butting surfaces 17a and 17b.

  In the upper case, the heights of the base materials 10a and 10b vary with the progress of the laser light irradiation centers 86a and 86b shown in FIG. In this case, the molten pools 82a and 82b shown in FIG. 8 do not have a desired size. For this reason, since the molten pools 82a and 82b do not melt, there is a possibility that the bonding strength is weakened.

  In FIG. 9, a part of the abutting surface 17b is curved. Such curvature is within tolerance or roughness. Due to such bending, the width of the gap 13b is not uniform. In such a case, the irradiation center 86b may deviate from the base material 10b. At this time, the molten pool 12b shown in FIG. 2 is not sufficiently formed. For this reason, since the molten pools 82a and 82b do not melt, there is a possibility that the bonding strength is weakened. In addition, there is a possibility that the laser beam may pass through the back of the base material and be irradiated to an unexpected location.

  All of the above problems are caused by weaving. On the other hand, in the method according to the embodiment shown in FIG. 2, the weld center line 25 is longer than the weld line 13a without weaving. Therefore, the butt surfaces 17a and 17b are broken so as to be stretched at any location in or around the fusion center line 25. Therefore, by destroying the oxide film, the effect of promoting the fusion of the molten pool can be obtained without depending on the weaving.

  The present invention is not limited to the above-described embodiment or examples, and can be appropriately changed without departing from the spirit of the present invention. For example, you may combine the optical operation or optical mechanism which concerns on the said weaving with respect to the welding method or welding apparatus which concerns on embodiment or an Example.

10a, 10b, 10c Base material 11a, 11b Spot 12a, 12b Weld pool 13a, c Weld line 13b Gap 14a, 14b, 14c, 14d End 15 Weld center line 16a, 16b, 16c, 16d Advancing direction 17a, 17b Surface 18a, 18b Oxide film 19a, 19b, 20a, 20b, 20c, 20d, 21a, 21b Spot 22a, 22b Weld pool 23a, 23b, 23c, 23d Laser beam 24a, 24b, 24c, 24d Irradiation surface 25 Fusion center line 26a, 26b Irradiation center 27 Welding device 28 Transport direction 29 Transporter 30 Polarizing beam splitter 31a, 31b Prism 32a, 32b, 32c, 32d Side surface 33 Polarizing surface 34 Irradiation center line 35 Optical path 36 Prism 37a, 37b, 37c Side surface 38 Slope 40 Optical system 41 Laser Light 42a, 42b, 42c, 42d Polarized light 45 Light source 46 Mirror 47 Convex lens 49a, 49b Polarization direction 50a, 50b, 50c, 50d Polarizing plate 52 Axis 53 Continuous rotation 56 Reciprocal rotation 57 Reciprocal center 59a, 59b, 60a, 60b, 61a , 61b Spot 62a, 62b End of weld pool 64a, 64b 67 Welding device 70 Optical system 73 Laser light 74 Spot 75 Optical path 80 Optical diffraction element 81a, 81b Spot 82a, 82b Weld pool 85a, 85b, 85c Weld centerline 86a, 86b Irradiation center D Length L of molten pool 62a during scanning Distance scanned by laser beam

Claims (7)

It is a welding method in which ends of metal materials are melted and joined with laser light,
The first abutting surface of the first end and the second abutting surface of the second end are opposed to each other,
The first laser light is applied to a first irradiation surface which is a surface of the first end portion and is different from the first abutting surface, and the surface of the second end portion is different from the second abutting surface. The second laser beam is scanned on the second irradiation surface, which is the surface, along a weld line that is a center line between the first butting surface and the second butting surface,
Oscillating the intensities of the first laser light and the second laser light at equal intervals, and providing a phase difference in the vibration so as to produce an intensity difference between the first laser light and the second laser light;
Welding method. Scanning so that the center of the first laser beam on the first irradiation surface and the center of the second laser beam on the second irradiation surface are in line symmetry with respect to the welding line;
The welding method according to claim 1. The phase difference is a phase difference corresponding to half of the period.
The welding method according to claim 1 or 2. During the scanning, when the intensity of one of the first laser light and the second laser light takes a maximum value, the other intensity is greater than 0.
The welding method according to claim 1. A welding apparatus that scans a laser beam on a first irradiation surface of a metal material and a second irradiation surface of the metal material or another metal material,
A light source that emits the original laser beam;
A polarizing beam splitter which is a first optical element located on the optical path of the original laser beam;
A polarizing plate positioned on the optical path of the exit side P-polarized light and the exit side S-polarized light in the polarization beam splitter, or on the optical path of the incident side original laser light in the polarization beam splitter,
The polarizing plate rotates on a plane parallel to the polarizing plate,
Irradiating one of the first irradiation surface and the second irradiation surface with the P-polarized light and irradiating the other with the S-polarized light;
Welding equipment. As the polarizing plate, comprising one polarizing plate located on the optical path of the P-polarized light and the S-polarized light,
The welding apparatus according to claim 5. A second optical element positioned on the optical path between the first optical element and the polarizing plate on the optical path of the P-polarized light or the S-polarized light;
The second optical element is a mirror, a prism, or a polarizing beam splitter;
The welding apparatus according to claim 6.

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