Welding method and welding device

Abstract

To suppress the occurrence of sputtering.SOLUTION: A welding method includes the step of irradiating a workpiece including a member made of tough pitch copper with laser light, thereby melting and welding the workpiece. The laser light is formed of a main beam and an auxiliary beam, at least part of which disposed anteriorly in a sweep direction. The power density of the main beam has an intensity of generating at least a keyhole. The power density of the auxiliary beam has an intensity that is lower than the power density of the main beam and melts the workpiece without generating the keyhole generated by at least the pressure of a metal vapor. The laser light forms a shallow region being a molten pool that is shallower than a molten pool formed in a region irradiated with the main beam in a region irradiated with the auxiliary beam and is filled with the workpiece that has been melted and liquefied. Before the shallow region formed in the region irradiated with the auxiliary beam is solidified, a melting intensity region of the main beam reaches the shallow region, and the depth of the shallow region is deeper than 10 μm.SELECTED DRAWING: Figure 2B

Description

[Technical field]

[0001] The present invention relates to a welding method and a welding apparatus. [Background technology]

[0002] Laser welding is known as one of the methods for welding metal materials such as iron and copper. Laser welding is a welding method in which a laser beam is irradiated onto the welding portion of the workpiece, and the energy of the laser beam melts the welding portion. A pool of molten metal material called a molten pool is formed at the welding portion irradiated with the laser beam, and the metal material in the molten pool then solidifies to complete the welding.

[0003] In addition, when a laser beam is irradiated onto a processing target, the profile of the laser beam may be shaped depending on the purpose. For example, a technique for shaping the profile of a laser beam when the laser beam is used to cut the processing target is known (see, for example, Patent Document 1).

[0004] In the past, because the output of laser light generating devices was low, laser welding was only used for metal materials with low reflectivity (high absorption rate). However, in recent years, the focusing ability of laser light generating devices has tended to improve, and laser welding of metal materials with high reflectivity, such as copper and aluminum, is also beginning to be put into practical use (see, for example, Patent Documents 2 to 4). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2010-508149 [Patent Document 2] Japanese Patent Application Publication No. 7-214369 [Patent Document 3] JP 2004-192948 A [Patent Document 4] International Publication No. 2010 / 131298 Summary of the Invention [Problem to be solved by the invention]

[0006] By the way, it is known that during welding, flying matter called spatter is generated from the molten pool. This spatter is molten metal scattered, and reducing its generation is important in preventing processing defects. The generated spatter adheres to the periphery of the welded area, but if it later peels off and adheres to an electric circuit, etc., it will cause an abnormality in the electric circuit. Therefore, it is difficult to perform welding on components for electric circuits. In addition, since spatter is molten metal scattered, the occurrence of spatter also means that the metal material at the welded area is reduced. In other words, if the occurrence of spatter increases, the metal material at the welded area will be insufficient, which may cause poor strength, etc.

[0007] In addition, even if the output of the laser light generating device is improved, the reflectivity of the metal material does not change, and it is necessary to irradiate a laser light with an intensity sufficient to compensate for the high reflectivity. In particular, when the workpiece begins to melt, it is necessary to irradiate a high-intensity laser light to compensate for the high reflectivity, but once melting begins, the high reflectivity also decreases, and the intensity of the laser light becomes excessive. This excessive laser light energy causes an increase in evaporated metal and unnecessary disturbance of the molten metal, increasing the possibility of welding defects such as spatters and voids.

[0008] The present invention has been made in view of the above, and an object of the present invention is to provide a welding method and welding apparatus that suppress the generation of spatter. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems and achieve the object, a welding method according to one aspect of the present invention includes the steps of placing an object to be processed in an area irradiated with laser light from a laser device, irradiating the laser light from the laser device toward the object to be processed while moving the laser light and the object to be processed relatively, and sweeping the laser light over the object to be processed to melt the irradiated portion of the object to be processed and weld it, wherein the laser light is composed of a main beam and a sub-beam at least a part of which is located forward in the sweep direction, and the power density of the main beam is greater than or equal to the power density of the sub-beam.

[0010] In a welding method according to one aspect of the present invention, the power density of the main beam is at least an intensity capable of generating a keyhole.

[0011] In a welding method according to one aspect of the present invention, the laser beam further has a sub-beam, the sub-beam having a power density lower than that of the main beam, disposed rearward in a sweep direction of the main beam.

[0012] In a welding method according to one aspect of the present invention, the laser beam further includes a sub-beam having a power density lower than that of the main beam in a lateral direction of a sweep direction of the main beam.

[0013] In a welding method according to one aspect of the present invention, the laser beam has sub beams, each of which has a power density lower than that of the main beam, dispersed around the main beam.

[0014] In a welding method according to one aspect of the present invention, the sub beam has a ring shape surrounding the periphery of the main beam or an arc shape that is a part of the ring shape surrounding the periphery of the main beam.

[0015] In a welding method according to one aspect of the present invention, the main beam and the sub beams of the laser light are configured such that a molten pool formed by the main beam and a molten pool formed by the sub beam at least partially overlap with each other.

[0016] In a welding method according to one aspect of the present invention, the wavelength of laser light forming at least the sub beams out of the main beam and the sub beams is a wavelength having a lower reflectance than the reflectance in the infrared region of the workpiece.

[0017] In a welding method according to one aspect of the present invention, a wavelength of the laser light forming the main beam is the same as a wavelength of the laser light forming the sub beams.

[0018] In a welding method according to one aspect of the present invention, the main beam and the sub beams are laser beams emitted from a same oscillator.

[0019] In a welding method according to one aspect of the present invention, the main beam and the sub beams are laser beams emitted from different oscillators.

[0020] In a welding method according to one aspect of the present invention, the main beam and the sub beam are formed by a bee shaper disposed between the oscillator and the workpiece.

[0021] In a welding method according to one aspect of the present invention, the beam shaper is a diffractive optical element.

[0022] In a welding method according to one embodiment of the present invention, the objects to be processed are at least two components to be welded, and the step of arranging the objects to be processed in an area to be irradiated with laser light is a step of arranging the at least two components so that they overlap, contact, or are adjacent to each other.

[0023] In a welding method according to one aspect of the present invention, a beam diameter of the sub beam is substantially equal to or larger than a beam diameter of the main beam.

[0024] A laser welding device according to one aspect of the present invention is comprised of a laser oscillator, and an optical head that receives light emitted from the laser oscillator to generate laser light, and irradiates the generated laser light toward a workpiece to melt and weld the irradiated portion of the workpiece, the optical head is configured so that the laser light and the workpiece are movable relative to each other, and the laser light is swept over the workpiece to melt and weld it, the laser light is comprised of a main beam and a sub-beam at least a portion of which is located forward in the sweep direction, and the power density of the main beam is greater than or equal to the power density of the sub-beam.

[0025] In the laser welding apparatus according to one aspect of the present invention, the power density of the sub beams is at least an intensity sufficient to melt the workpiece.

[0026] In a laser welding apparatus according to one aspect of the present invention, the laser light further includes a sub-beam having a power density lower than that of the main beam, the sub-beam being positioned rearward of the main beam in a sweep direction.

[0027] In a laser welding apparatus according to one aspect of the present invention, the laser light further includes a sub-beam having a power density lower than that of the main beam in a lateral direction of the sweep direction of the main beam.

[0028] In a laser welding apparatus according to one aspect of the present invention, the laser light has sub-beams, each of which has a power density lower than that of the main beam, dispersed around the main beam.

[0029] In the laser welding apparatus according to one aspect of the present invention, the sub beams have a ring shape surrounding the periphery of the main beam or an arc shape that is a part of the ring shape surrounding the periphery of the main beam.

[0030] In one aspect of the laser welding apparatus of the present invention, the main beam and the sub beams of the laser light are configured so that a molten pool formed by the main beam and a molten pool formed by the sub beam at least partially overlap with each other.

[0031] In a laser welding device according to one aspect of the present invention, the wavelength of laser light forming at least the sub beam out of the main beam and the sub beams is a wavelength having a lower reflectance than the reflectance in the infrared region of the workpiece.

[0032] In the laser welding device according to one aspect of the present invention, the wavelength of the laser light forming the main beam is the same as the wavelength of the laser light forming the side beams.

[0033] In the laser welding apparatus according to one aspect of the present invention, the optical head generates the laser light consisting of the main beam and the sub beams from light oscillated from a single laser oscillator.

[0034] In one aspect of the laser welding apparatus of the present invention, the optical head includes a beam shaper arranged between the laser oscillator and the workpiece, and the diffractive optical element forms the main beam and the sub beam from the light emitted from the single laser oscillator.

[0035] In a laser welding apparatus according to one aspect of the present invention, the beam shaper is a diffractive optical element.

[0036] In a laser welding device according to one aspect of the present invention, the laser oscillator is composed of two different laser oscillators, and the main beam and the sub beam are laser beams emitted from the two different oscillators, respectively.

[0037] In a laser welding apparatus according to one aspect of the present invention, the objects to be processed are at least two members to be welded.

[0038] In the laser welding device according to one aspect of the present invention, the beam diameter of the sub beam is substantially equal to or larger than the beam diameter of the main beam.

[0039] In the laser welding apparatus according to one aspect of the present invention, the beam shaper is rotatably provided.

[0040] In a laser welding device according to one aspect of the present invention, the laser oscillators are multiple, and the optical head internally combines the light beams emitted from the multiple oscillators to generate the laser beam.

[0041] A laser welding apparatus according to one aspect of the present invention includes a plurality of the laser oscillators, and further includes a multicore fiber that internally multiplexes light beams emitted from the plurality of laser oscillators and guides the light beams to the optical head.

[0042] In the laser welding device according to one aspect of the present invention, the optical head is configured to be able to sweep the laser light across the fixed workpiece.

[0043] In a laser welding device according to one aspect of the present invention, a position at which the laser light is irradiated from the optical head is fixed, and the workpiece is held so as to be movable relative to the fixed laser light. Effect of the Invention

[0044] The welding method and welding apparatus according to the present invention have the advantage of being able to suppress the generation of spatter. [Brief description of the drawings]

[0045] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a welding device according to a first embodiment. [Figure 2A] FIG. 2A is a diagram showing a comparison of situations in which a laser beam melts an object to be processed. [Figure 2B] FIG. 2B is a diagram showing a comparison of the conditions in which the laser beam melts the processing target. [Figure 3A] FIG. 3A is a diagram showing an example of a cross-sectional shape of laser light. [Figure 3B] FIG. 3B is a diagram showing an example of a cross-sectional shape of laser light. [Figure 3C] FIG. 3C is a diagram showing an example of a cross-sectional shape of laser light. [Figure 3D] FIG. 3D is a diagram showing an example of a cross-sectional shape of a laser beam. [Figure 3E]FIG. 3E is a diagram showing an example of a cross-sectional shape of laser light. [Figure 3F] FIG. 3F is a diagram showing an example of a cross-sectional shape of laser light. [Figure 4] FIG. 4 is a diagram showing a schematic configuration of a welding device according to the second embodiment. [Diagram 5] FIG. 5 is a diagram showing a schematic configuration of a welding device according to a third embodiment. [Figure 6] FIG. 6 is a diagram showing a schematic configuration of a welding device according to a fourth embodiment. [Figure 7] FIG. 7 is a diagram showing a schematic configuration of a welding device according to a fifth embodiment. [Figure 8] FIG. 8 is a diagram showing a schematic configuration of a welding device according to a sixth embodiment. [Figure 9A] FIG. 9A is a diagram showing an example of the configuration of an optical fiber. [Figure 9B] FIG. 9B is a diagram showing an example of the configuration of an optical fiber. [Figure 10] FIG. 10 is a diagram showing the cross-sectional shape of the laser light used in the experiment. [Figure 11] FIG. 11 is a diagram showing an example of a cross-sectional shape of a laser beam. [Figure 12] FIG. 12 is a diagram showing an example of a cross-sectional shape of a laser beam. [Figure 13] FIG. 13 is a graph showing the reflectance of representative metal materials versus wavelength of light. [Figure 14A] FIG. 14A is a diagram showing a comparison of situations in which a laser beam melts an object to be processed. [Figure 14B] FIG. 14B is a diagram showing a comparison of situations in which the laser beam melts the processing target. [Figure 15] FIG. 15 is a diagram illustrating the concept of a diffractive optical element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] Hereinafter, a welding method and a welding device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments described below. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of each element may differ from the reality. There may also be parts in which the dimensional relationships and ratios of each element differ between the drawings.

[0047] (First embodiment) Fig. 1 is a diagram showing a schematic configuration of a welding device according to a first embodiment. As shown in Fig. 1, a welding device 100 according to a first embodiment is an example of a configuration of a device that irradiates a workpiece W with a laser beam L to melt the workpiece W. As shown in Fig. 1, the welding device 100 includes an oscillator 110 that oscillates a laser beam, an optical head 120 that irradiates the workpiece W with the laser beam, and an optical fiber 130 that guides the laser beam oscillated by the oscillator 110 to the optical head 120. The workpiece W is at least two members to be welded.

[0048] The oscillator 110 is configured to oscillate a multimode laser beam with an output of several kW, for example. For example, the oscillator 110 may be configured to include a plurality of semiconductor laser elements therein and oscillate a multimode laser beam with an output of several kW as the total output of the plurality of semiconductor laser elements, or may use various lasers such as a fiber laser, a YAG laser, or a disk laser.

[0049] The optical head 120 is an optical device for concentrating the laser light L guided from the oscillator 110 to a power density strong enough to melt the workpiece W, and irradiating the workpiece W with the laser light. For this purpose, the optical head 120 is equipped with a collimator lens 121 and a condenser lens 122 inside. The collimator lens 121 is an optical system for temporarily collimating the laser light guided by the optical fiber 130, and the condenser lens 122 is an optical system for focusing the collimated laser light on the workpiece W.

[0050] The optical head 120 is provided so that its relative position with respect to the workpiece W can be changed in order to move (sweep) the irradiation position of the laser light L on the workpiece W. Methods for changing the relative position with respect to the workpiece W include moving the optical head 120 itself and moving the workpiece W. That is, the optical head 120 may be configured so that the laser light L can be swept with respect to the fixed workpiece W, or the irradiation position of the laser light L from the optical head 120 may be fixed, and the workpiece W may be held so as to be movable with respect to the fixed laser light L. In the step of arranging the workpiece W in the region irradiated with the laser light L, at least two members to be welded are arranged so as to overlap, contact, or be adjacent to each other.

[0051] The optical head 120 according to the first embodiment includes a diffractive optical element 123 as a beam shaper between the collimator lens 121 and the condenser lens 122. The diffractive optical element here refers to an optical element 1502 in which a plurality of diffraction gratings 1501 with different periods are integrated as shown in the concept of FIG. 15. The laser light passing through this is bent in a direction influenced by each diffraction grating, overlaps, and can be formed into an arbitrary shape. In this embodiment, the diffractive optical element 123 is for shaping the laser light L so that the profile of the power density of the laser light L on the processing object W in the moving direction has a sub-beam with a lower power density than the main beam forward in the moving direction than the main beam with a higher power density. The diffractive optical element 123 can be configured to be rotatable. It can also be configured to be replaceable.

[0052] Here, the power density of the main or side beam includes the peak and is 1 / e 2 The power density in the region with an intensity of 1 / e 2 For non-circular beams, this is defined as the radius of the region with an intensity equal to or greater than 1 / e of the peak intensity, perpendicular to the direction of travel. 2The length of the region where the intensity is equal to or greater than the above is defined as the beam diameter. The beam diameter of the sub beam may be substantially equal to or larger than the beam diameter of the main beam.

[0053] The effect of the profile of the power density of the laser beam L on the workpiece W in the moving direction having a sub beam with a lower power density than the main beam ahead of the main beam with a higher power density in the moving direction is as follows: Figures 2A and 2B are diagrams comparing the conditions in which the laser beam melts the workpiece.

[0054] As shown in FIG. 2A, in conventional laser welding, the laser beam has one beam B, so that a molten pool WP in which the workpiece W is melted is formed as a molten region in the opposite direction of the movement direction (arrow v) from the position where the laser beam is irradiated. On the other hand, as shown in FIG. 2B, in the welding device according to the first embodiment and the welding method using the same, the profile of the power density of the laser beam on the workpiece W in the movement direction has a main beam B1 and a sub-beam B2. The power density of the main beam B1 is, for example, an intensity that can at least generate a keyhole. The keyhole will be described in detail later. And, a sub-beam B2 with a lower power density than the main beam B1 is located forward of the main beam B1 with a high power density in the movement direction (arrow v). Also, the power density of the sub-beam B2 is an intensity that can melt the workpiece W in the presence of the main beam B1 or alone. Therefore, a molten pool WP1 with an area shallower than the depth at which the main beam B1 melts is formed as a molten region forward of the position where the main beam B1 is irradiated. For convenience, this will be called a shallow area R.

[0055] As shown in Fig. 2B, the melting intensity regions of the laser beams of the main beam B1 and the sub beam B2 may overlap, but they do not necessarily have to overlap, as long as the molten pools overlap. It is sufficient that the melting intensity region formed by the main beam B1 reaches the molten pool formed by the sub beam B2 before the molten pool solidifies. As described above, the power density of the main beam B1 and the sub beam B2 is an intensity capable of melting the workpiece W, and the melting intensity region refers to the range of the laser beam of the power density capable of melting the workpiece W around the main beam B1 or the sub beam B2.

[0056] In the welding apparatus and the welding method using the same according to the first embodiment, the shallow area R exists ahead of the position where the main beam B1 is irradiated, so that the molten pool WP1 is stabilized in the vicinity of the irradiation position of the main beam B1. As described above, spatter is molten metal scattered, so stabilizing the molten pool WP1 in the vicinity of the irradiation position of the main beam B1 leads to suppression of spatter generation. In fact, the effect of suppressing spatter generation was confirmed in the experiment described later.

[0057] The welding method according to the first embodiment includes the steps of arranging the workpiece W in an area irradiated with laser light L from an oscillator 110, which is a laser device, moving the laser light L and the workpiece W relatively while irradiating the laser light L from the oscillator 110 toward the workpiece W, and melting the irradiated part of the workpiece W while sweeping the laser light L over the workpiece W, thereby welding the workpiece W. At this time, the laser light L is composed of a main beam B1 and a sub-beam B2, at least a part of which is located forward in the sweep direction, and the power density of the main beam B1 is equal to or greater than the power density of the sub-beam B2. The workpiece W is at least two members to be welded. The step of arranging the workpiece W in an area irradiated with the laser light L is a step of arranging at least two members so that they overlap, contact, or are adjacent to each other.

[0058] The power density of the sub-beam B2 is preferably set so that the shallow region R is deeper than the diameter of the allowable porosity (a void, a pit shape with a hole from the inside to the surface, a blowhole, or other welding defect). This allows impurities attached to the surface of the workpiece W, which is one of the causes of porosity, to flow through the shallow region R into the molten pool WP1 formed by the main beam B1, making it difficult for porosity to occur. The allowable diameter of the porosity is determined, for example, depending on the use of the workpiece W. Generally, a diameter of 200 μm or less is allowable, with 100 μm being preferred, 50 μm or less being more preferred, 30 μm or less being even more preferred, 20 μm or less being even more preferred, and 10 μm or less being even more preferred, and it is most preferred that there be no porosity at all.

[0059] Next, with reference to Figures 3A to 3F, examples of the cross-sectional shape of the laser light will be described, in which the profile of the power density of the laser light on the processing object in the moving direction has a sub-beam with a lower power density than the main beam ahead of the main beam with a higher power density in the moving direction. The examples of the cross-sectional shape of the laser light shown in Figures 3A to 3F are not essential configurations, but a profile of the laser light suitable for carrying out the present invention can be realized by designing the diffractive optical element 123 so that the cross-sectional shape of the laser light exemplified in Figures 3A to 3F is realized on the surface of the processing object W. Note that the cross-sectional shapes of the laser light exemplified in Figures 3A to 3F all move upward on the paper (arrow v in the figure).

[0060] Fig. 3A shows an example in which a sub-beam B2 having a peak P2 and a lower power density than the main beam B1 is provided ahead of the main beam B1 having a peak P1 and a high power density in the moving direction. As shown in Fig. 3A, the region of the power density capable of melting the workpiece around the sub-beam B2 is preferably wider in the direction perpendicular to the moving direction than the region of the power density capable of melting the workpiece around the main beam B1. Therefore, as shown in Fig. 3A, the sub-beam B2 may be extended to a continuous region without being a point shape.

[0061] 3B shows an example in which not only a sub beam B2 having a lower power density than the main beam B1 is provided ahead of the main beam B1 having a high power density in the moving direction, but also a sub beam B2 having a lower power density than the main beam B1 behind the main beam B1 in the moving direction. Welding does not always involve forward movement, but may also involve backward movement. Therefore, as in the example shown in FIG. 3B, if a sub beam B2 having a lower power density than the main beam B1 is provided behind the main beam B1 in the moving direction, the effect of the present invention can be obtained without changing the orientation of the optical head.

[0062] 3C shows an example in which not only a sub-beam B2 with a lower power density than the main beam B1 is provided ahead of the main beam B1 with a high power density in the moving direction, but also a sub-beam B2 with a lower power density than the main beam B1 in the lateral direction of the moving direction of the main beam B1. Welding is not always performed along a straight line. Therefore, as in the example shown in FIG. 3C, if a sub-beam B2 with a lower power density than the main beam B1 is provided in the lateral direction of the moving direction of the main beam B1, the effect of the present invention can be obtained even when welding corners.

[0063] Fig. 3D shows an example in which not only a sub-beam B2 having a lower power density than the main beam B1 is located forward of the main beam B1 having a high power density in the moving direction, but also a sub-beam B2 having a lower power density than the main beam B1 in the rearward and lateral directions of the moving direction of the main beam B1. In other words, the example shown in Fig. 3D has the advantages of both the examples shown in Figs. 3B and 3C.

[0064] FIG. 3E shows an example in which sub-beams B2 having a lower power density than the main beam B1 are distributed around the main beam B1. In the examples shown in FIGS. 3A to 3D, the sub-beams B2 are configured in a line shape, but the sub-beams B2 do not necessarily need to be continuous as long as they are arranged at a certain interval. This is because if the sub-beams B2 are arranged at a certain interval, the shallow water region R is connected, and an effective effect can be obtained. FIG. 3F shows an example in which the sub-beams B2 having a lower power density than the main beam B1 are arranged in a ring shape around the main beam B1. Contrary to FIG. 3E, it is also possible to provide the sub-beams B2 in a continuous circle.

[0065] The distance d between the main beam B1 and the sub beam B2 (for example, as shown in FIG. 3A) is the shortest distance between the outer edge of the beam diameter of the main beam B1 and the outer edge of the beam diameter of the sub beam B2. The distance d should be such that the molten area formed by the main beam B1 can reach the molten pool formed by the sub beam B2 before the molten pool solidifies, but is preferably less than twice the beam diameter of the sub beam B2, more preferably less than 1 time, and even more preferably less than 0.5 times.

[0066] Furthermore, the power densities of the main beam B1 and the sub beam B2 may be equal.

[0067] Second embodiment Fig. 4 is a diagram showing a schematic configuration of a welding device according to a second embodiment. As shown in Fig. 4, the welding device 200 according to the second embodiment is an example of a configuration of a device that irradiates a workpiece W with a laser beam L to melt the workpiece W. The welding device 200 according to the second embodiment realizes a welding method based on the same action principle as the welding device according to the first embodiment. Therefore, only the device configuration of the welding device 200 will be described below.

[0068] As shown in FIG. 4, the welding device 200 includes an oscillator 210 that oscillates a laser beam, an optical head 220 that irradiates the laser beam onto the workpiece W, and an optical fiber 230 that guides the laser beam oscillated by the oscillator 210 to the optical head 220.

[0069] The oscillator 210 is configured to oscillate a multi-mode laser beam with an output of several kW, for example. For example, the oscillator 210 may be configured to include a plurality of semiconductor laser elements therein and oscillate a multi-mode laser beam with an output of several kW as the total output of the plurality of semiconductor laser elements, or may use various lasers such as a fiber laser, a YAG laser, or a disk laser.

[0070] The optical head 220 is an optical device for concentrating the laser light L guided from the oscillator 210 to a power density strong enough to melt the workpiece W, and irradiating the workpiece W with the laser light. For this purpose, the optical head 220 is internally provided with a collimator lens 221 and a condenser lens 222. The collimator lens 221 is an optical system for temporarily collimating the laser light guided by the optical fiber 230, and the condenser lens 222 is an optical system for focusing the collimated laser light on the workpiece W.

[0071] The optical head 220 has a galvano scanner between the condenser lens 222 and the workpiece W. The galvano scanner is a device that can move the irradiation position of the laser light L without moving the optical head 220 by controlling the angles of two mirrors 224a and 224b. In the example shown in Fig. 4, a mirror 226 is provided to guide the laser light L emitted from the condenser lens 222 to the galvano scanner. In addition, the angles of the mirrors 224a and 224b of the galvano scanner are changed by motors 225a and 225b, respectively.

[0072] The optical head 220 according to the second embodiment includes a diffractive optical element 223 between a collimator lens 221 and a condenser lens 222. The diffractive optical element 223 is for shaping the laser light L so that a profile of the power density of the laser light L on the workpiece W in the moving direction has a sub beam having a lower power density than the main beam ahead of the main beam having a high power density in the moving direction, and its function is the same as that of the first embodiment. In other words, the diffractive optical element 223 is designed to realize a profile of the laser light suitable for implementing the present invention, such as the cross-sectional shapes of the laser light exemplified in Figs. 3A to 3F.

[0073] Third embodiment Fig. 5 is a diagram showing a schematic configuration of a welding device according to a third embodiment. As shown in Fig. 5, a welding device 300 according to the third embodiment is an example of a configuration of a device that irradiates a workpiece W with a laser beam L to melt the workpiece W. The welding device 300 according to the third embodiment realizes a welding method by the same action principle as the welding device according to the first embodiment, and the configuration other than the optical head 320 (the oscillator 310 and the optical fiber 330) is the same as that of the second embodiment. Therefore, only the device configuration of the optical head 320 will be described below.

[0074] The optical head 320 is an optical device for concentrating the laser light L guided from the oscillator 310 to a power density strong enough to melt the workpiece W, and irradiating the workpiece W with the laser light. For this purpose, the optical head 320 is internally provided with a collimator lens 321 and a condenser lens 322. The collimator lens 321 is an optical system for temporarily collimating the laser light guided by the optical fiber 330, and the condenser lens 322 is an optical system for focusing the collimated laser light on the workpiece W.

[0075] The optical head 320 has a galvano scanner between the collimator lens 321 and the condenser lens 322. The angles of mirrors 324a and 324b of the galvano scanner are changed by motors 325a and 325b, respectively. In the optical head 320, the galvano scanner is provided at a position different from that in the second embodiment, but similarly, by controlling the angles of the two mirrors 324a and 324b, the irradiation position of the laser light L can be moved without moving the optical head 320.

[0076] The optical head 320 according to the third embodiment includes a diffractive optical element 323 between a collimator lens 321 and a condenser lens 322. The diffractive optical element 323 is for shaping the laser light L so that a profile of the power density of the laser light L on the workpiece W in the moving direction has a sub beam having a lower power density than the main beam ahead of the main beam having a high power density in the moving direction, and its function is the same as that of the first embodiment. In other words, the diffractive optical element 323 is designed to realize a profile of the laser light suitable for implementing the present invention, such as the cross-sectional shape of the laser light exemplified in FIG.

[0077] (Fourth embodiment) Fig. 6 is a diagram showing a schematic configuration of a welding device according to a fourth embodiment. As shown in Fig. 6, a welding device 400 according to the fourth embodiment is an example of a configuration of a device that irradiates a workpiece W with laser beams L1 and L2 to melt the workpiece W. The welding device 400 according to the fourth embodiment realizes a welding method based on the same action principle as the welding device according to the first embodiment. Therefore, only the device configuration of the welding device 400 will be described below.

[0078] As shown in FIG. 6, the welding apparatus 400 includes a plurality of oscillators 411, 412 that oscillate laser light, an optical head 420 that irradiates the laser light onto the workpiece W, and optical fibers 431, 432 that guide the laser light oscillated by the oscillators 411, 412 to the optical head 420.

[0079] The oscillators 411 and 412 are configured to oscillate, for example, a multimode laser beam with an output of several kW. For example, the oscillators 411 and 412 may each include a plurality of semiconductor laser elements therein, and may be configured to oscillate a multimode laser beam with an output of several kW as the total output of the plurality of semiconductor laser elements, or may use various lasers such as a fiber laser, a YAG laser, or a disk laser.

[0080] The optical head 420 is an optical device for concentrating the laser beams L1 and L2 guided from the oscillators 411 and 412 to a power density strong enough to melt the workpiece W, and irradiating the workpiece W with the laser beams. For this purpose, the optical head 420 includes a collimator lens 421a and a condenser lens 422a for the laser beam L1, and a collimator lens 421b and a condenser lens 422b for the laser beam L2. The collimator lenses 421a and 421b are optical systems for temporarily collimating the laser beams guided by the optical fibers 431 and 432, respectively, and the condenser lenses 422a and 422b are optical systems for focusing the collimated laser beams on the workpiece W.

[0081] The optical head 420 according to the fourth embodiment is also configured so that the profile of the power density of the laser beams L1 and L2 on the workpiece W in the moving direction has a sub-beam with a lower power density than the main beam ahead of the main beam with a higher power density in the moving direction. That is, of the laser beams L1 and L2 irradiated to the workpiece W by the optical head 420, the laser beam L1 is used to form the main beam, and the laser beam L2 is used to form the sub-beam. Note that, although the example shown in the figure uses only the laser beams L1 and L2, by appropriately increasing the number of the laser beams, a configuration can be made to realize a profile of the laser beam suitable for implementing the present invention, such as the cross-sectional shape of the laser beam exemplified in FIG. 3.

[0082] Fifth embodiment Fig. 7 is a diagram showing a schematic configuration of a welding device according to a fifth embodiment. As shown in Fig. 7, the welding device 500 according to the fifth embodiment is an example of a configuration of a device that irradiates the workpiece W with laser beams L1 and L2 to melt the workpiece W. The welding device 500 according to the fifth embodiment realizes a welding method based on the same action principle as the welding device according to the first embodiment. Therefore, only the device configuration of the welding device 500 will be described below.

[0083] As shown in FIG. 7, the welding device 500 includes an oscillator 510 that oscillates a laser beam, an optical head 520 that irradiates the laser beam onto an object to be processed W, and optical fibers 531, 533, and 534 that guide the laser beam oscillated by the oscillator 510 to the optical head 520.

[0084] In the fifth embodiment, the oscillator 510 is, for example, a fiber laser, a YAG laser, a disk laser, or the like, and is used to oscillate both of the laser beams L1 and L2 to be irradiated to the processing object W. For that purpose, a branching unit 532 is provided between optical fibers 531, 533, and 534 that guide the laser beam oscillated by the oscillator 510 to the optical head 520, and is configured to branch the laser beam oscillated by the oscillator 510 and then guide it to the optical head 520.

[0085] The optical head 520 is an optical device for collecting the laser beams L1 and L2 branched by the branching unit 532 to a power density strong enough to melt the workpiece W, and irradiating the workpiece W with the collected laser beams. For this purpose, the optical head 520 includes a collimator lens 521a and a condenser lens 522a for the laser beam L1, and a collimator lens 521b and a condenser lens 522b for the laser beam L2. The collimator lenses 521a and 521b are optical systems for temporarily collimating the laser beams guided by the optical fibers 533 and 534, respectively, and the condenser lenses 522a and 522b are optical systems for collecting the collimated laser beams on the workpiece W.

[0086] The optical head 520 according to the fifth embodiment is also configured so that the profile of the power density of the laser beams L1 and L2 on the workpiece W in the moving direction has a sub-beam with a lower power density than the main beam ahead of the main beam with a higher power density in the moving direction. That is, of the laser beams L1 and L2 irradiated to the workpiece W by the optical head 520, the laser beam L1 is used to form the main beam, and the laser beam L2 is used to form the sub-beam. Note that, although the example shown in the figure uses only the laser beams L1 and L2, by appropriately increasing the number of the laser beams, a configuration can be made to realize a profile of the laser beam suitable for implementing the present invention, such as the cross-sectional shape of the laser beam exemplified in FIG. 3.

[0087] Sixth embodiment Fig. 8 is a diagram showing a schematic configuration of a welding device according to a sixth embodiment. As shown in Fig. 8, a welding device 600 according to a sixth embodiment is an example of a configuration of a device that irradiates a workpiece W with a laser beam L to melt the workpiece W. The welding device 600 according to the sixth embodiment realizes a welding method based on the same action principle as the welding device according to the first embodiment. Therefore, only the device configuration of the welding device 600 will be described below.

[0088] As shown in FIG. 8, the welding apparatus 600 includes a plurality of oscillators 611, 612 that oscillate laser light, such as a fiber laser, a YAG laser, a disk laser, etc., an optical head 620 that irradiates the laser light onto the workpiece W, and optical fibers 631, 632, 635 that guide the laser light oscillated by the oscillators 611, 612 to the optical head 620.

[0089] In the sixth embodiment, the laser light oscillated by the oscillators 611 and 612 is coupled before being guided to the optical head 620. For this purpose, a coupling portion 634 is provided between optical fibers 631, 632, and 635 that guide the laser light oscillated by the oscillators 611 and 612 to the optical head 620, and the laser light oscillated by the oscillators 611 and 612 is guided in parallel through the optical fiber 635.

[0090] Here, referring to Figs. 9A and 9B, configuration examples of the optical fiber 631 (and 632) and the optical fiber 635 will be described. As shown in Fig. 9A, the optical fiber 631 (and 632) is a normal optical fiber. That is, the optical fiber 631 (and 632) is an optical fiber in which a clad Cl having a lower refractive index than the core Co is formed around one core Co. On the other hand, as shown in Fig. 9B, the optical fiber 635 is a so-called multi-core optical fiber. That is, the optical fiber 635 has two cores Co1 and Co2, and a clad Cl having a lower refractive index than the cores Co1 and Co2 is formed around the two cores Co1 and Co2. Then, at the coupling portion 634, the core Co of the optical fiber 631 is coupled to the core Co1 of the optical fiber 635, and the core Co of the optical fiber 632 is coupled to the core Co2 of the optical fiber 635.

[0091] Returning to Fig. 8, the optical head 620 is an optical device for concentrating the laser light L combined by the combining portion 634 to a power density strong enough to melt the workpiece W, and irradiating the workpiece W with the laser light. For this purpose, the optical head 620 includes a collimator lens 621 and a condenser lens 622 therein.

[0092] In this embodiment, the optical head 620 does not have a diffractive optical element, nor does it have an independent optical system for multiple laser beams. However, the laser beams oscillated by the oscillators 611, 612 are combined before being guided to the optical head 620, so that the profile of the power density of the laser beam L on the workpiece W in the moving direction is configured to have a sub-beam with a lower power density than the main beam, ahead of the main peak with high power density, in the moving direction.

[0093] In all the embodiments in this specification, the welding form of the main beam may be keyhole welding or heat conduction welding. Keyhole welding here is a welding method that uses a high power density and utilizes a depression or hole (keyhole) that is generated by the pressure of metal vapor that is generated when the workpiece W is melted. On the other hand, heat conduction welding is a welding method that melts the workpiece W by utilizing heat generated by the absorption of laser light on the surface of the base material.

[0094] (Verification experiment 1) Here, the results of verification experiment 1 of the effect of the present invention will be described. The device configuration used in this verification experiment 1 is the configuration of the welding device 100 according to the first embodiment, and a configuration in which the diffractive optical element 123 is removed from the welding device 100 is used as the device configuration of the conventional example. Note that the common experimental conditions are that the output of the oscillator 110 is 3 kW, the relative movement speed between the optical head 120 and the workpiece W is 5 m per minute, and nitrogen gas is used as the shielding gas.

[0095] The diffractive optical element 123 is designed so that the main beam B1 having a peak P1 and the sub-beam B2 having a peak P2 as shown in Fig. 10 are formed, and the sub-beam B2 is designed so that the workpiece W is irradiated with a laser beam having an arc-shaped cross section, which is a part of a ring shape surrounding the main beam B1. The occurrence of sputtering was observed in two moving directions of the laser beam shaped by this diffractive optical element 123, the direction of the arrow A in the figure and the direction of the arrow B in the figure. In the conventional device configuration, the workpiece W is irradiated with a laser beam with the arc portion removed from the cross section of the laser beam shown in Fig. 10.

[0096] In other words, in this verification experiment 1, when moving in the direction of arrow A in the figure, it corresponds to a situation where the sub-beam B2, which has a lower power density than the main beam B1, is located in front of the main beam B1, which has a higher power density, in the direction of movement, while when moving in the direction of arrow B in the figure, it corresponds to a situation where the sub-beam B2, which has a lower power density than the main beam B1, is located behind the main beam B1, which has a higher power density, in the direction of movement, and the conventional configuration corresponds to a situation where only the main beam B1 is irradiated.

[0097] In a situation where only the main beam B1 is irradiated, and in a situation where the sub beam B2, which has a lower power density than the main beam B1, is located behind the main beam B1, which has a higher power density, in the direction of movement, a lot of sputtering occurs, whereas in a situation where the sub beam B2, which has a lower power density than the main beam B1, is located ahead of the main beam B1, which has a higher power density, in the direction of movement, the occurrence of sputtering is significantly reduced, to around 20% or less.

[0098] This verification experiment 1 also showed that a welding device and a welding method using the same, in which the profile of the power density of the laser light L on the workpiece W in the movement direction has a secondary peak with a lower power density than the main peak, which has a high power density, ahead of the main peak in the movement direction, are effective in suppressing the generation of spatter.

[0099] It was also confirmed that the method was effective even under conditions without using nitrogen gas, as shown in Table 1. Table 1 shows four experiments. The material to be processed was SUS304 with a thickness of 10 mm. The DOE is a diffractive optical element. The focal position is the focal position of the main beam and sub beam, and is just focused on the surface. The set output is the power of the laser light output from the oscillator. The speed is the sweep speed. In terms of appearance, experiments No. 3 and 4 produced favorable results. [Table 1]

[0100] 11 and 12 are diagrams showing examples of the cross-sectional shape of laser light, in which a V-shaped sub-beam B2 having a lower power density than the main beam B1 is located ahead of the main beam B1 with a high power density in the moving direction. Fig. 11 shows an example in which the main beam B1 and the sub-beam B2 overlap, and Fig. 12 shows an example in which the main beam B1 and the sub-beam B2 do not overlap.

[0101] (Reflectance of metal materials) Here, the reflectance of metal materials will be explained. The graph shown in FIG. 13 shows the reflectance of representative metal materials with respect to the wavelength of light. In the graph shown in FIG. 13, the horizontal axis represents the wavelength and the vertical axis represents the reflectance, and examples of metal materials are listed as aluminum, copper, gold, nickel, platinum, silver, stainless steel, titanium, and tin. The graph shown in FIG. 13 is a graph of data listed in NASA TECHNICAL NOTE (D-5353).

[0102] As can be seen from the graph in Figure 13, copper and aluminum have higher reflectance than stainless steel. The difference is particularly noticeable in the wavelength range of infrared laser light that is commonly used in laser welding. For example, at around 1070 nm, the reflectance of copper and aluminum is about 95%, meaning that only about 5% of the energy of the irradiated laser light is absorbed by the workpiece. This means that the efficiency of the irradiated energy is about one-sixth compared to stainless steel.

[0103] On the other hand, even if the reflectance of copper or aluminum is high, it does not mean that the reflectance is high for all wavelengths of light. In particular, the change in reflectance of copper is remarkable. As described above, the reflectance of copper is about 95% at around 1070 nm, but at a yellow wavelength (e.g., 600 nm), the reflectance of copper is about 75%, and then drops sharply, and at an ultraviolet wavelength (e.g., 300 nm), the reflectance of copper is about 20%. Therefore, laser welding using blue or green laser light is more energy efficient than using general infrared laser light. Specifically, it is preferable to use laser light with a wavelength between 300 nm and 600 nm.

[0104] The above wavelength range is an example, and if laser welding is performed using a laser beam having a wavelength with a reflectance lower than that of the target material in the infrared region, welding with high energy efficiency can be performed in terms of reflectance. In this case, the infrared region is preferably 1070 nm, which is the wavelength of infrared laser beams used in general laser welding.

[0105] The welding method and welding apparatus according to the embodiment of the present invention described below utilize the above characteristics.

[0106] Seventh embodiment The welding device according to the seventh embodiment can be realized by the welding device 100 according to the first embodiment shown in FIG.

[0107] The laser oscillator 110 is configured to oscillate a multi-mode laser beam with an output of several kW, for example. For example, the laser oscillator 110 may be configured to include a plurality of semiconductor laser elements therein, and to oscillate a multi-mode laser beam with an output of several kW as the total output of the plurality of semiconductor laser elements. In the seventh embodiment, from the above viewpoint, the laser oscillator 110 is preferably configured to oscillate a laser beam with a wavelength between 300 nm and 600 nm. Furthermore, it is more preferable to select a laser oscillator 110 that oscillates a wavelength that reduces the reflectance of the object W to be processed, depending on the object W to be processed.

[0108] The optical head 120 according to the seventh embodiment includes a diffractive optical element 123 as a beam shaper between a collimator lens 121 and a condenser lens 122. The diffractive optical element 123 is for shaping the laser light L so that the profile of the power density of the laser light L on the workpiece W in the sweep direction has a sub-beam located forward of the main beam in the sweep direction. Therefore, the welding device 100 according to the seventh embodiment is configured to separate the laser light emitted from the same laser oscillator 110 by the diffractive optical element 123, and as a result, the wavelengths of the laser light forming both the main beam and the sub-beam are the same. The diffractive optical element 123 can be configured to be rotatable. It can also be configured to be replaceable.

[0109] The effect of the profile of the power density of the laser beam L on the workpiece W in the sweep direction having a main beam and a sub-beam located ahead of the main beam in the sweep direction is as follows: Figures 14A and 14B are diagrams comparing the state in which the laser beam melts the workpiece.

[0110] 14A, in conventional laser welding, the laser beam has one beam B, so that the pre-molten metal W1 ahead of the position irradiated with the laser beam in the sweep direction (arrow v) is melted by the energy of the laser beam, and a molten pool WP of the workpiece W melted is formed in the opposite direction of the sweep direction (arrow v) from the position irradiated with the laser beam. The molten pool WP then resolidifies to become resolidified metal W2, and the workpiece W is welded.

[0111] On the other hand, as shown in FIG. 14B, in the welding apparatus and the welding method using the same according to the eleventh embodiment, the profile of the power density of the laser light on the workpiece W in the sweep direction has a main beam B1 and a sub-beam B2. The sub-beam B2, which has a lower power density than the main beam B1, is located ahead of the main beam B1, which has a higher power density, in the sweep direction (arrow v). The power density of the sub-beam B2 is an intensity that can melt the workpiece W in the presence of the main beam B1 or alone. Therefore, a molten pool shallower than the depth melted by the main beam B1 is formed ahead of the position irradiated by the main beam B1. For convenience, this is called a front molten pool WPf.

[0112] As shown in Fig. 14B, the melting intensity regions of the laser beams of the main beam B1 and the sub beam B2 do not necessarily need to overlap, as long as the weld pools overlap. In other words, it is sufficient that the melting intensity region formed by the main beam B1 reaches the front weld pool WPf before the weld pool formed by the sub beam B2 solidifies. As described above, the power density of the main beam B1 and the sub beam B2 is an intensity capable of melting the workpiece W, and the melting intensity region refers to the range of the laser beam having a power density capable of melting the workpiece W around the main beam B1 or the sub beam B2.

[0113] In the welding apparatus and the welding method using the same according to the eleventh embodiment, the front molten pool WPf exists ahead of the position where the main beam B1 is irradiated, so that the state of the molten pool WP is stabilized in the vicinity of the irradiation position of the main beam B1. As described above, spatter is molten metal scattered, so stabilizing the state of the molten pool WP in the vicinity of the irradiation position of the main beam B1 leads to suppressing the occurrence of spatter.

[0114] Moreover, in the welding apparatus and the welding method using the same according to the seventh embodiment, the wavelength of the laser light forming at least the sub-beam B2 (in this example, both) of the main beam B1 and the sub-beam B2 has a wavelength that has a lower reflectance than the reflectance in the infrared region of the object to be processed, so that a forward molten pool WPf can be efficiently formed even in metal materials such as copper and aluminum that have a high reflectance at infrared wavelengths.

[0115] In the welding apparatus and the welding method using the same according to the seventh embodiment, it is preferable that the power density of the sub beam B2 is lower than the power density of the main beam B1. More specifically, the power density of the sub beam B2 is 1×10 7 W / cm 2 It is preferable that the power density is not too high. The purpose of the sub-beam B2 is to form a front weld pool WPf ahead of the position where the main beam B1 is irradiated, and the function of the front weld pool WPf is to stabilize the state of the weld pool WP in the vicinity of the irradiation position of the main beam B1. The depth of the front weld pool WPf is sufficient to be shallow enough to stabilize the weld pool WP, and as described above, the reflectivity of the workpiece is reduced by making the laser light forming the sub-beam B2 have a wavelength with a reflectivity lower than the reflectivity of the infrared region of the workpiece, so that the power density is not required to be excessively high. If the power density of the sub-beam is excessively high, the sub-beam itself will be a cause of spatter generation. On the other hand, the purpose of the main beam is to sufficiently melt the workpiece W and reliably weld the workpiece W. Considering these points, it is preferable that the power density of the sub-beam B2 is lower than the power density of the main beam B1.

[0116] Examples of the cross-sectional shape of the laser beam in which the profile of the power density of the laser beam on the processing object in the sweep direction has a sub beam located forward of the main beam in the sweep direction are as shown in FIGS.

[0117] The laser beam arranged in the sub-beam B2 has a lower power density than the main beam B1 intended for welding, so even if the sub-beam B2 is arranged in a direction other than the intended forward direction, it does not impede the actual welding work. For example, the intensity of the laser beam forming the main beam B1 is 1 kW, and the intensity of the laser beam forming the sub-beam B2 is 300 W.

[0118] As is clear from the above example, the sub-beam P2 does not necessarily have to have a profile with a single peak. Even if the profile has a peak in a certain area (including a line) or the peak points are arranged at fairly close intervals, this does not have a substantial effect on the molten pool that is formed. Therefore, these will be referred to as the sub-beam P2 without distinction.

[0119] Eighth embodiment The welding device according to the eighth embodiment can be realized by the welding device 200 according to the second embodiment shown in FIG.

[0120] The laser oscillator 210 is configured to oscillate a multi-mode laser beam with an output of several kW, for example. For example, the laser oscillator 210 is configured to include a plurality of semiconductor laser elements therein, and to oscillate a multi-mode laser beam with an output of several kW as the total output of the plurality of semiconductor laser elements. As in the eighth embodiment, the laser oscillator 210 is preferably configured to oscillate a laser beam with a wavelength between 300 nm and 600 nm. Furthermore, it is more preferable to select a laser oscillator 210 that oscillates a wavelength that reduces the reflectance of the object W to be processed, depending on the object W to be processed.

[0121] In the welding apparatus and the welding method using the same according to the eighth embodiment, the wavelength of the laser light forming at least the sub-beams (in this example, both) of the main beam and the sub-beams has a lower reflectance than the reflectance in the infrared region of the object to be processed, so that a forward molten pool can be formed efficiently even in metal materials such as copper and aluminum that have high reflectance in infrared wavelengths.

[0122] Ninth embodiment The welding device according to the ninth embodiment can be realized by the welding device 300 according to the third embodiment shown in FIG.

[0123] The optical head 320 includes a diffractive optical element 323 as a beam shaper between a collimator lens 321 and a condenser lens 322. The diffractive optical element 323 is for shaping the laser light L so that the profile of the power density of the laser light L on the processing object W in the sweep direction has a sub-beam located forward of the main beam in the sweep direction. In other words, the diffractive optical element 323 is designed to realize a profile of the laser light suitable for implementing the present invention, such as the cross-sectional shapes of the laser light exemplified in Figs. 3A to 3F, 11, and 12.

[0124] In the welding apparatus and the welding method using the same according to the ninth embodiment, the wavelength of the laser light forming at least the sub-beams (in this example, both) of the main beam and the sub-beams has a lower reflectance than the reflectance in the infrared region of the object to be processed, so that a forward molten pool can be formed efficiently even in metal materials such as copper and aluminum that have high reflectance at infrared wavelengths.

[0125] Tenth embodiment The welding device according to the tenth embodiment can be realized by the welding device 400 according to the fourth embodiment shown in FIG.

[0126] In the tenth embodiment, the laser oscillator 411 and the laser oscillator 412 are different laser oscillators and may oscillate laser light of the same wavelength, or may be configured to oscillate different laser light. In that case, the laser oscillator 412 is configured so that the wavelength of the laser light L2 forming the sub-beam out of the main beam and the sub-beams is between 300 nm and 600 nm.

[0127] The optical head 420 is configured so that the profile of the power density of the laser beams L1 and L2 on the workpiece W in the sweep direction has a sub-beam located forward of the main beam in the sweep direction. That is, of the laser beams L1 and L2 irradiated by the optical head 420 to the workpiece W, the laser beam L1 may be used to form the main beam, and the laser beam L2 may be used to form the sub-beam. Note that, although the example shown in the figure uses only the laser beams L1 and L2, by appropriately increasing the number of the laser beams, a configuration may be made to realize a profile of the laser beam suitable for implementing the present invention, such as the cross-sectional shapes of the laser beams exemplified in FIGS. 3A to 3F, 11, and 12.

[0128] In the welding apparatus and the welding method using the same according to the tenth embodiment, the wavelength of the laser light forming at least the sub-beam out of the main beam and the sub-beam has a lower reflectance than the reflectance of the workpiece in the infrared region, so that the forward molten pool can be efficiently formed even if the workpiece is a metal material with high reflectance in the infrared region, such as copper or aluminum. On the other hand, the wavelength of the laser light L1 forming the main beam does not necessarily have to be a wavelength with a lower reflectance than the reflectance of the workpiece in the infrared region, so that the laser oscillator 411 can be a high-power laser oscillator with an infrared wavelength, as in the conventional product. That is, in this embodiment, the wavelength of the laser light forming the sub-beam is a wavelength with a lower reflectance than the reflectance of the workpiece at the wavelength of the laser light forming the main beam. Even if the metal material has a high reflectance in the infrared wavelength, the reflectance is low in the molten state, so that the laser oscillator 411 can sufficiently melt the workpiece even if it is a high-power laser oscillator with an infrared wavelength, such as a fiber laser, a YAG laser, or a disk laser.

[0129] Eleventh embodiment The welding apparatus according to the eleventh embodiment can be realized by the welding apparatus 500 according to the fifth embodiment shown in FIG.

[0130] The optical head 520 is configured so that the profile of the power density of the laser beams L1 and L2 on the workpiece W in the sweep direction has a sub-beam located forward of the main beam in the sweep direction. That is, of the laser beams L1 and L2 irradiated by the optical head 520 to the workpiece W, the laser beam L1 may be used to form the main beam, and the laser beam L2 may be used to form the sub-beam. Note that, although the example shown in the figure uses only the laser beams L1 and L2, by appropriately increasing the number of the laser beams, a configuration may be made to realize a profile of the laser beam suitable for implementing the present invention, such as the cross-sectional shapes of the laser beams exemplified in FIGS. 3A to 3F, 11, and 12.

[0131] In the welding apparatus and the welding method using the same according to the eleventh embodiment, the wavelength of the laser light forming at least the sub-beams (in this example, both) of the main beam and the sub-beams has a wavelength that has a lower reflectance than the reflectance in the infrared region of the object to be processed, so that a forward molten pool can be formed efficiently even in metal materials such as copper and aluminum that have a high reflectance at infrared wavelengths.

[0132] Twelfth embodiment The welding apparatus according to the twelfth embodiment can be realized by the welding apparatus 600 according to the sixth embodiment shown in FIG.

[0133] In the twelfth embodiment, the laser oscillator 611 and the laser oscillator 612 are different laser oscillators and may oscillate laser light of the same wavelength, or may be configured to oscillate different laser light. In that case, the laser oscillator 612 is configured so that the wavelength of the laser light forming the sub-beam out of the main beam and the sub-beams is between 300 nm and 600 nm.

[0134] In the twelfth embodiment, the laser light oscillated by the laser oscillators 611 and 612 is coupled before being guided to the optical head 620. For this purpose, a coupling portion 634 is provided between optical fibers 631, 632, and 635 that guide the laser light oscillated by the laser oscillators 611 and 612 to the optical head 620, and the laser light oscillated by the laser oscillators 611 and 612 is guided in parallel through the optical fiber 635.

[0135] The optical head 620 is an optical device for concentrating the laser light L combined by the combining portion 634 to a power density strong enough to melt the workpiece W, and irradiating the workpiece W with the laser light. For this purpose, the optical head 620 includes a collimator lens 621 and a condenser lens 622 therein.

[0136] In this embodiment, the optical head 620 does not have a beam shaper, nor does it have an independent optical system for multiple laser beams. However, the laser beams emitted by the laser oscillators 611, 612 are combined before being guided to the optical head 620, so that the profile of the power density of the laser beam L on the workpiece W in the sweeping direction is configured to have a sub-beam located ahead of the main beam in the sweeping direction.

[0137] In the welding apparatus and the welding method using the same according to the twelfth embodiment, the wavelength of the laser light forming at least the sub-beam out of the main beam and the sub-beam has a lower reflectance than the reflectance of the target in the infrared region, so that the forward molten pool can be efficiently formed even if the target is a metal material with high reflectance in the infrared region, such as copper or aluminum. On the other hand, the wavelength of the laser light L1 forming the main beam does not necessarily have to be a wavelength with a lower reflectance than the reflectance of the target in the infrared region, so that the laser oscillator 611 can use a high-power laser oscillator with an infrared wavelength, as in the conventional product. That is, in this embodiment, the wavelength of the laser light forming the sub-beam is a wavelength with a lower reflectance than the reflectance of the target at the wavelength of the laser light forming the main beam. Even if the metal material has a high reflectance in the infrared wavelength, the reflectance is low in the molten state, so that the laser oscillator 611 can sufficiently melt the target, even if it uses a high-power laser oscillator with an infrared wavelength, such as a fiber laser, a YAG laser, or a disk laser.

[0138] For all the above-mentioned embodiments, the welding form of the main beam can be not only heat conduction type welding but also keyhole type welding.

[0139] (Verification experiment 2) Here, the results of the verification experiment 2 of the effect of the present invention will be described. The device configuration used in this verification experiment 2 is the configuration of the welding device according to the seventh embodiment, and is the same configuration as the welding device 100. The first experimental condition as a comparative example uses a configuration in which the diffractive optical element 123 is removed from the welding device 100, and the second experimental condition corresponding to the present invention includes a diffractive optical element 123 designed to irradiate the workpiece W with laser light with a profile of the irradiation surface shape shown in FIG. 10, but the wavelength of the laser light used is in the blue region. In addition, as common experimental conditions, the sweep speed between the optical head 120 and the workpiece W is 5 m per minute, and nitrogen gas is used as the shielding gas. In addition, tough pitch copper with a thickness of 2 mm is adopted as the workpiece W.

[0140] More specifically, in the first experimental condition, a multimode fiber laser device with an oscillation wavelength of 1070 nm was used as the laser oscillator 110, and this was used with an output of 3 kW. The laser was irradiated as a single spot on the processing target without passing through the diffractive optical element 123, so that the spot diameter at the focal point was 100 μm and the average power density was 3.8×10 7 W / cm 2 Let us assume that.

[0141] In the second experimental condition, a semiconductor laser device with an oscillation wavelength of 450 nm is used as the laser oscillator 110, and is used with an output of 1 kW. The diffractive optical element 123 used is designed so that the workpiece W is irradiated with laser light having an irradiation surface shape as shown in FIG. 10. The power is distributed so that 300 W of the 1 kW output is distributed almost evenly to the semicircular sub-beams. In this case, the average power density of the main beam is 2.2×10 6 W / cm 2 and the average power density of the sub-beam is 8.0×10 4 W / cm 2 It is.

[0142] When a verification experiment was carried out under the above experimental conditions, the following results were obtained.

[0143] Under the first experimental condition, the power density at the focal point exceeded the melting threshold of pure copper, forming a keyhole and enabling welding; however, spatter and welding defects frequently occurred.

[0144] On the other hand, under the second experimental conditions, even though the laser oscillator output was 1kW, copper material has a high absorption rate at a wavelength of 450nm, so welding could be performed to the desired depth, and it was also possible to form a forward molten pool by using a 300W semicircular secondary beam placed forward in the sweep direction. As a result, it was confirmed from high-speed camera observations that spatter and welding defects were significantly reduced to about 20% or less due to the effect of the forward molten pool formed by the secondary beam.

[0145] This verification experiment also showed that a welding device and a welding method using the same, in which the profile of the power density of the laser light L on the workpiece W in the direction of movement has a sub-beam that is located in front of the main beam in the direction of movement, and the wavelength of the laser light forming at least the sub-beam of the main beam and the sub-beam has a wavelength that has a reflectivity lower than the reflectivity in the infrared region of the workpiece, are effective in suppressing the generation of spatter.

[0146] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. The present invention also includes configurations in which the components of the above-mentioned embodiments are appropriately combined. Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-mentioned embodiments, and various modifications are possible. [Explanation of symbols]

[0147] 100,200,300,400,500,600 Welding equipment 110,210,310,411,412,510,611,612 Oscillators 120,220,320,420,520,620 Optical head 121,221,321,421a,421b,521a,521b,621 Collimating Lenses 122,222,322,422a,422b,522a,522b,622 Condenser Lens 123,223,323 Diffractive optical elements 224a, 224b, 226, 324a, 324b Mirror 225a, 225b, 325a, 325b motor 130,230,330,431,432,531,533,534,631,632,635 Optical fiber 532 Branch Unit 634 Joint

Claims

1. A laser beam from a laser device is irradiated onto a workpiece including a member made of copper or aluminum, and the workpiece is melted and welded. The method includes the steps of: the laser light is composed of only one main beam and a sub beam at least a part of which is located forward of the main beam in a sweep direction, the power density of the main beam is an intensity at which at least a keyhole is generated, and the power density of the sub beam is lower than the power density of the main beam and is an intensity at which at least a keyhole generated by a pressure of a metal vapor is melted, the wavelength of the laser light forming the main beam is in the infrared region; the wavelength of the laser light forming the sub-beam is between 300 nm and 600 nm; the laser beam forms a shallow region in an area irradiated with the sub beam, the shallow region being a molten pool filled with the melted and liquefied workpiece, the shallow region being shallower than a molten pool formed in an area irradiated with the main beam, Before the shallow water region formed in the region irradiated with the sub beam is solidified, the melting intensity region of the main beam reaches the shallow water region, The depth of the shallow region is greater than 10 μm. A welding method in which the workpiece is welded using a laser.

2. The welding method according to claim 1 , wherein the laser beam further includes a sub-beam having a power density lower than that of the main beam, the sub-beam being disposed rearward in a sweep direction of the main beam.

3. The welding method according to claim 1 , wherein the laser beam further includes a sub-beam having a power density lower than that of the main beam in a lateral direction of the sweep direction of the main beam.

4. The welding method according to claim 1 , wherein the laser beam further includes sub-beams, each of which has a lower power density than the main beam, and which are distributed around the main beam.

5. The welding method according to claim 1 , wherein the sub beam has a ring shape surrounding the periphery of the main beam or an arc shape that is a part of the ring shape surrounding the periphery of the main beam.

6. 6. The welding method according to claim 1, wherein the main beam and the sub beams of the laser light are configured such that a molten pool formed by the main beam and a molten pool formed by the sub beam at least partially overlap with each other.

7. The method of claim 6 , wherein a distance between the main beam and the sub-beam is less than twice a beam diameter of the sub-beam.

8. The power density in the sub-beam is 1×10 ７ W / cm ２ 2. The welding method according to claim 1, wherein:

9. The welding method according to claim 1 , wherein the main beam and the sub beam are laser beams emitted from different oscillators.

10. 10. The welding method according to claim 9, wherein at least one of the main beam and the sub beam is shaped by a beam shaper disposed between the oscillator and the workpiece.

11. The method of claim 10, wherein the beam shaper is a diffractive optical element.

12. The method of claim 10, wherein the distance between the main beam and the sub-beam is less than one beam diameter of the sub-beam.

13. 2. The welding method according to claim 1, wherein the workpieces are at least two members to be welded, and the step of placing the workpieces in an area to be irradiated with laser light is a step of placing the at least two members so that they overlap, contact, or are adjacent to each other.

14. The welding method according to claim 1 , wherein a beam diameter of the sub beam is substantially equal to or larger than a beam diameter of the main beam.

15. A laser beam from a laser device is irradiated onto a workpiece including a member made of copper or aluminum, and the workpiece is melted and welded. The method includes the steps of: the laser light is composed of only one main beam and a sub-beam at least a part of which is located forward of the main beam in a sweep direction, the main beam has an intensity at least sufficient to generate a keyhole, and the sub-beam has a power density lower than that of the main beam and an intensity at least sufficient to melt the object to be processed without generating a keyhole caused by a pressure of metal vapor, the wavelength of the laser light forming the main beam is in the infrared region; the wavelength of the laser light forming the sub-beam is between 300 nm and 600 nm; the laser beam forms a shallow region in an area irradiated with the sub beam, the shallow region being a molten pool filled with the melted and liquefied workpiece, the shallow region being shallower than a molten pool formed in an area irradiated with the main beam, Before the shallow water region formed in the region irradiated with the sub beam is solidified, the melting intensity region of the main beam reaches the shallow water region, The depth of the shallow region is greater than 10 μm. A welding method in which the workpiece is welded using a laser.

16. The welding method according to claim 1 or 15, wherein the laser light is irradiated toward the object to be processed while a shielding gas is being supplied.

17. A laser oscillator; an optical head that receives light oscillated from a laser oscillator, generates a laser beam, and irradiates a workpiece including a member made of copper or aluminum with the generated laser beam to melt and weld the workpiece at the irradiated portion; It is composed of the optical head is configured so that the laser light and the workpiece are relatively movable, and the laser light is swept over the workpiece to melt and weld the workpiece; the laser light is composed of only one main beam and a sub beam at least a part of which is located forward of the main beam in a sweep direction, the power density of the main beam is an intensity at which at least a keyhole is generated, and the power density of the sub beam is lower than the power density of the main beam and is an intensity at which at least a keyhole generated by a pressure of a metal vapor is melted, the wavelength of the laser light forming the main beam is in the infrared region; the wavelength of the laser light forming the sub-beam is between 300 nm and 600 nm; the laser beam forms a shallow region in an area irradiated with the sub beam, the shallow region being a molten pool filled with the melted and liquefied workpiece, the shallow region being shallower than a molten pool formed in an area irradiated with the main beam, Before the shallow water region formed in the region irradiated with the sub beam is solidified, the melting intensity region of the main beam reaches the shallow water region, The depth of the shallow region is greater than 10 μm. A welding device that uses a laser to weld the workpiece.

18. The welding device according to claim 17 , wherein the laser light further includes a sub-beam having a lower power density than the main beam, the sub-beam being positioned rearward of the main beam in a sweep direction.

19. The welding device according to claim 17 , wherein the laser beam further includes a sub-beam having a power density lower than that of the main beam in a lateral direction of the sweep direction of the main beam.

20. 18. The welding device according to claim 17, wherein the laser light has sub-beams, each of which has a lower power density than the main beam, dispersed around the main beam.

21. 18. The welding apparatus of claim 17, wherein the secondary beams have a ring shape surrounding the periphery of the primary beam or an arc shape that is a portion of a ring shape surrounding the periphery of the primary beam.

22. 22. The welding device according to claim 17, wherein the main beam and the sub beams of the laser light are configured such that a molten pool formed by the main beam and a molten pool formed by the sub beam at least partially overlap with each other.

23. 18. The welding device according to claim 17, wherein the wavelength of the laser light forming at least the sub-beams out of the main beam and the sub-beams is a wavelength having a lower reflectance than a reflectance in the infrared region of the workpiece.

24. The power density in the sub-beam is 1×10 ７ W / cm ２ 24. The welding apparatus of claim 23, wherein:

25. 25. The welding device according to claim 23 or 24, wherein the wavelength of the laser light forming the main beam is the same as the wavelength of the laser light forming the side beams.

26. 18. The welding apparatus according to claim 17, wherein the optical head generates the laser light consisting of the main beam and the sub beams from light oscillated from a single laser oscillator.

27. 27. The welding apparatus of claim 26, wherein the optical head includes a beam shaper disposed between the laser oscillator and the workpiece, the beam shaper forming the main beam and the sub beams from light emitted from the single laser oscillator.

28. 28. The welding apparatus of claim 27, wherein the beam shaper is a diffractive optical element.

29. 29. The welding apparatus according to claim 27 or 28, wherein the distance between the main beam and the sub-beam is less than one beam diameter of the sub-beam.

30. 18. The welding device according to claim 17, wherein the laser oscillator is composed of two different laser oscillators, and the main beam and the sub beam are laser beams emitted from the two different laser oscillators, respectively.

31. 20. The welding apparatus of claim 17, wherein the workpiece is at least two components to be welded.

32. 18. The welding apparatus of claim 17, wherein a beam diameter of the sub-beam is approximately equal to or larger than a beam diameter of the main beam.

33. 29. The welding apparatus of claim 27 or 28, wherein the beam shaper is rotatably mounted.

34. The laser oscillators are multiple, 18. The welding device according to claim 17, wherein the optical head internally combines the light beams emitted from the plurality of laser oscillators to generate the laser beam.

35. The laser oscillators are multiple, 18. The welding device according to claim 17, further comprising a multi-core fiber that internally combines the light beams emitted from the plurality of laser oscillators and guides the combined light beams to the optical head.

36. The welding apparatus of claim 17 , wherein the optical head is configured to be able to sweep the laser light across the workpiece, which is fixed.

37. 18. The welding device according to claim 17, wherein a position at which the laser light is irradiated from the optical head is fixed, and the workpiece is held movable relative to the fixed laser light.

38. A laser oscillator; an optical head that receives light oscillated from a laser oscillator, generates a laser beam, and irradiates a workpiece including a member made of copper or aluminum with the generated laser beam to melt and weld the workpiece at the irradiated portion; It is composed of the laser light is composed of only one main beam and a sub-beam at least a part of which is located forward of the main beam in a sweep direction, the main beam has an intensity at least sufficient to generate a keyhole, and the sub-beam has a power density lower than that of the main beam and an intensity at least sufficient to melt the object to be processed without generating a keyhole caused by a pressure of metal vapor, the wavelength of the laser light forming the main beam is in the infrared region; the wavelength of the laser light forming the sub-beam is between 300 nm and 600 nm; the laser beam forms a shallow region in an area irradiated with the sub beam, the shallow region being a molten pool filled with the melted and liquefied workpiece, the shallow region being shallower than a molten pool formed in an area irradiated with the main beam, Before the shallow water region formed in the region irradiated with the sub beam is solidified, the melting intensity region of the main beam reaches the shallow water region, The depth of the shallow region is greater than 10 μm. A welding device that uses a laser to weld the workpiece.

39. 40. The welding device according to claim 17 or 38, wherein the laser light is irradiated toward the object to be processed while a shielding gas is being supplied.

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