Laser welding method and laser welding device

Abstract

This laser welding method comprises at least a welding step for irradiating a surface of a workpiece with a laser beam while advancing the laser beam in an X direction and scanning in a Y direction intersecting the X direction. The welding step includes at least: a first weaving step for weaving the laser beam in the Y direction with a first amplitude (A1); and a second weaving step for weaving the laser beam with a prescribed amplitude smaller than the first amplitude (A1) at both ends of a weaving locus drawn by the laser beam in the first weaving step.

Description

[Technical Field]

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

[0002] Laser welding allows for high-speed, high-quality welding because the power density of the laser beam irradiated onto the workpiece is high. In particular, scanning welding, in which welding is performed while scanning the laser beam over the surface of the workpiece at high speed, can significantly reduce the air transport time required by a robot or other device holding the laser head, enabling welding to be achieved with a shorter takt time.

[0003] On the other hand, because the spot diameter of the laser beam needs to be narrowed, there is a risk that the laser beam will penetrate through the gap when a gap may occur at the welded portion of the workpiece, such as in butt welding. Furthermore, if such penetration occurs, the amount of metal melted by the laser beam may not be sufficient to fill the gap, and there is a risk that a good weld bead will not be formed.

[0004] Therefore, in order to solve these problems, a method has been proposed in the past in which laser welding is performed while weaving a laser beam on the surface of a workpiece at high speed (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3965754 [Patent Document 2] Patent No. 6588498 Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional laser welding methods such as those disclosed in Patent Documents 1 and 2, the entire weaving range is uniformly irradiated with laser light.

[0007] However, when weaving a laser beam in a predetermined direction, the heat diffusion from the molten part of the workpiece to the surrounding area is greater at both ends of the weaving path than in other parts, reducing the effective heat input by the laser beam. Also, in joints such as butt welding of different plate thicknesses or lap welding of the same plate thickness, thermal imbalance occurs at both ends of the weaving path, making it difficult to form a good weld bead.

[0008] The present disclosure has been made in view of the above points, and an object thereof is to provide a laser welding method and a laser welding apparatus that are capable of forming a weld bead with a good shape in laser welding that involves weaving. [Means for solving the problem]

[0009] In order to achieve the above object, a laser welding method according to the present disclosure includes at least a welding step of irradiating a surface of a workpiece with a laser beam while the laser beam advances in a first direction and weaves in a second direction intersecting the first direction, the welding step including at least a first weaving step of weaving the laser beam in the second direction with a first amplitude, and a second weaving step of weaving the laser beam with a predetermined amplitude smaller than the first amplitude at at least one end of a weaving locus drawn by the laser beam in the first weaving step. In the first weaving step, the laser beam is woven so as to draw a linear first weaving locus along the second direction, and in the second weaving step, the laser beam is woven so as to draw a circular second weaving locus. It is characterized by:

[0010] A laser welding device according to the present disclosure includes at least a laser oscillator that generates laser light, a laser head that receives the laser light and irradiates it toward a workpiece, and a controller that controls the operation of the laser head, wherein the laser head has a laser light scanner that scans at least in a second direction intersecting a first direction that is a traveling direction of the laser light, and the controller drives and controls the laser light scanner so as to weave the laser light in the second direction with a first amplitude and further weave the laser light at a predetermined amplitude smaller than the first amplitude at at least one end of a weaving locus of the first amplitude drawn by the laser light, and the controller weaves the laser light to draw a linear first weaving locus and further drives and controls the laser light scanner so as to weave the laser light in either the first direction or the second direction, or to weave in a circular shape at least at one of both end portions of the first weaving locus. The controller weaves the laser beam so as to draw a circular second weaving locus, and further drives and controls the laser beam scanner so as to weave the laser beam in either the first direction or the second direction at a starting point of the second weaving locus, or to weave the laser beam in a circular shape. It is characterized by: [Effects of the Invention]

[0011] According to the laser welding method and laser welding apparatus of the present disclosure, a weld bead with a good shape can be formed in laser welding that involves weaving. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of a laser welding device according to the first embodiment. [Figure 2] FIG. 2 is a schematic diagram of the laser beam scanner. [Figure 3A] FIG. 3A is a schematic diagram of a workpiece. [Figure 3B] FIG. 3B is a schematic diagram of another workpiece. [Figure 4A] FIG. 4A is a diagram showing a weaving locus of laser light. [Figure 4B] FIG. 4B is a diagram showing a change over time in the weaving locus of the laser light. [Figure 5A]FIG. 5A is a diagram showing a weaving locus of laser light according to Comparative Example 1. FIG. [Figure 5B] FIG. 5B is a diagram showing a change over time in the weaving locus of the laser light according to Comparative Example 1. As shown in FIG. [Figure 6A] FIG. 6A is a diagram showing a weaving locus of laser light according to Modification 1. FIG. [Figure 6B] FIG. 6B is a diagram showing a change over time in the weaving locus of the laser light according to the first modification. [Figure 7A] FIG. 7A is a diagram showing a weaving locus of laser light according to Modification 2. FIG. [Figure 7B] FIG. 7B is a diagram showing a change over time in the weaving locus of laser light according to Modification 2. In FIG. [Figure 8A] FIG. 8A is a diagram showing a weaving locus of laser light according to Modification 3. FIG. [Figure 8B] FIG. 8B is a diagram showing a change over time in the weaving locus of laser light according to Modification 3. In FIG. [Figure 9] FIG. 9 is a diagram showing the contribution of each part to the weaving locus of laser light according to the third modification. [Figure 10] FIG. 10 shows an example of a combination of laser beam weaving methods according to the fourth modification. [Figure 11A] FIG. 11A is a diagram showing a weaving locus of laser light according to the second embodiment. [Figure 11B] FIG. 11B is a diagram showing a change over time in the weaving locus of the laser light according to the second embodiment. [Figure 12A] FIG. 12A is a diagram showing a weaving locus of laser light according to Comparative Example 2. FIG. [Figure 12B] FIG. 12B is a diagram showing a change over time in the weaving locus of the laser light according to Comparative Example 2. As shown in FIG. [Figure 13] 10 is a diagram showing a weaving locus of laser light and a change over time in the output of laser light according to the third embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0014] [Configuration of laser welding device and laser beam scanner] Fig. 1 shows a schematic diagram of the configuration of a laser welding device according to this embodiment, Fig. 2 shows a schematic diagram of a laser beam scanner, Fig. 3A shows a schematic diagram of a workpiece, and Fig. 3B shows a schematic diagram of another workpiece.

[0015] In the following description, the direction parallel to the traveling direction of laser beam LB from reflecting mirror 33 toward laser beam scanner 40 will be referred to as the X direction, the direction parallel to the optical axis of laser beam LB emitted from laser head 30 will be referred to as the Z direction, and the direction perpendicular to the X direction and Z direction will be referred to as the Y direction. When the surface of workpiece 200 is flat, the XY plane, which includes the X direction and the Y direction, may be substantially parallel to the surface or may have a certain angle therewith. Furthermore, as will be described later, the X direction corresponds to the longitudinal direction of weld bead 300 (see FIG. 3A ) formed on workpiece 200, and the Y direction corresponds to the width direction of weld bead 300.

[0016] As shown in FIG. 1, the laser welding apparatus 100 includes a laser oscillator 10, an optical fiber 20, a laser head 30, a controller 50, and a manipulator 60.

[0017] The laser oscillator 10 is a laser light source that receives power from a power source (not shown) and generates laser light LB. The laser oscillator 10 may be configured with a single laser light source or multiple laser modules. In the latter case, laser light emitted from the multiple laser modules is combined and emitted as laser light LB. The laser light source or laser module used in the laser oscillator 10 is selected appropriately depending on the material of the workpiece 200, the shape of the welding portion, etc.

[0018] For example, a fiber laser, a disk laser, or a YAG (Yttrium Aluminum Garnet) laser can be used as the laser light source. In this case, the wavelength of the laser light LB is set in the range of 1000 nm to 1100 nm. A semiconductor laser can also be used as the laser light source or laser module. In this case, the wavelength of the laser light LB is set in the range of 800 nm to 1000 nm. A visible light laser can also be used as the laser light source or laser module. In this case, the wavelength of the laser light LB is set in the range of 400 nm to 600 nm.

[0019] The optical fiber 20 is optically coupled to the laser oscillator 10 , and the laser light LB generated by the laser oscillator 10 is incident on the optical fiber 20 and transmitted through the optical fiber 20 toward the laser head 30 .

[0020] The laser head 30 is attached to the end of the optical fiber 20 and irradiates the laser light LB transmitted from the optical fiber 20 toward the workpiece 200 .

[0021] The laser head 30 also has optical components, such as a collimation lens 32, a reflecting mirror 33, a focusing lens 34, and a laser light scanner 40, and these optical components are housed inside the housing 31 while maintaining a predetermined arrangement relationship.

[0022] The collimation lens 32 receives the laser light LB emitted from the optical fiber 20, converts it into parallel light, and directs it to the reflecting mirror 33. The collimation lens 32 is also connected to a drive unit (not shown) and is configured to be displaceable in the Z direction in response to a control signal from the controller 50. By displacing the collimation lens 32 in the Z direction, the focal position of the laser light LB can be changed, allowing the laser light LB to be appropriately irradiated according to the shape of the workpiece 200. In other words, the collimation lens 32, in combination with a drive unit (not shown), also functions as a focal position adjustment mechanism for the laser light LB. The focusing lens 34 may be displaced by a drive unit to change the focal position of the laser light LB.

[0023] The reflecting mirror 33 reflects the laser light LB that has passed through the collimation lens 32 and makes it incident on the laser light scanner 40. The surface of the reflecting mirror 33 is disposed so as to form an angle of approximately 45 degrees with the optical axis of the laser light LB that has passed through the collimation lens 32.

[0024] The condenser lens 34 condenses the laser light LB, which has been reflected by the reflecting mirror 33 and scanned by the laser light scanner 40, onto the surface of the workpiece 200.

[0025] 2, the laser beam scanner 40 is a known galvanometer scanner having a first galvanometer mirror 41 and a second galvanometer mirror 42. The first galvanometer mirror 41 has a first mirror 41a, a first rotation shaft 41b, and a first driver 41c, and the second galvanometer mirror 42 has a second mirror 42a, a second rotation shaft 42b, and a second driver 42c. The laser beam LB transmitted through the condenser lens 34 is reflected by the first mirror 41a and then by the second mirror 42a, and is irradiated onto the workpiece 200.

[0026] For example, the first driver 41c and the second driver 42c are motors, and the first rotary shaft 41b and the second rotary shaft 42b are output shafts of the motors. Although not shown, the first driver 41c is driven to rotate by a driver that operates in response to a control signal from the controller 50, causing the first mirror 41a attached to the first rotary shaft 41b to rotate about the axis of the first rotary shaft 41b. Similarly, the second driver 42c is driven to rotate by a driver that operates in response to a control signal from the controller 50, causing the second mirror 42a attached to the second rotary shaft 42b to rotate about the axis of the second rotary shaft 42b.

[0027] The first mirror 41a rotates around the axis of the first rotation shaft 41b to a predetermined angle, causing the laser light LB to scan in the X direction. The second mirror 42a rotates around the axis of the second rotation shaft 42b to a predetermined angle, causing the laser light LB to scan in the Y direction. In other words, the laser light scanner 40 is configured to scan the laser light LB one-dimensionally or two-dimensionally within the XY plane and irradiate it toward the workpiece 200.

[0028] The controller 50 controls the laser oscillation of the laser oscillator 10. Specifically, the controller 50 controls the laser oscillation by supplying control signals such as output current and on / off time to a power supply (not shown) connected to the laser oscillator 10.

[0029] Furthermore, the controller 50 controls the operation of the laser head 30 in accordance with the contents of the selected laser welding program. Specifically, the controller 50 controls the driving of a driving unit (not shown) of the laser beam scanner 40 and the collimation lens 32 provided in the laser head 30. Furthermore, the controller 50 controls the operation of the manipulator 60. The laser welding program is stored in a storage unit (not shown) provided inside the controller 50 or in a separate location, and is called by the controller 50 in response to a command from the controller 50.

[0030] The controller 50 has an integrated circuit such as an LSI or a microcomputer (not shown), and the above-described functions of the controller 50 are realized by executing a laser welding program, which is software, on this integrated circuit.

[0031] The manipulator 60 is an articulated robot, and is attached to the housing 31 of the laser head 30. The manipulator 60 is connected to the controller 50 so as to be able to exchange signals, and moves the laser head 30 so as to trace a predetermined trajectory in accordance with the laser welding program described above. A separate controller (not shown) for controlling the operation of the manipulator 60 may be provided.

[0032] The laser welding apparatus 100 shown in FIG. 1 can perform laser welding on workpieces 200 of various shapes. For example, as shown in FIG. 3A, a laser beam LB is irradiated onto a joint of the workpiece 200, in which a first plate material 210 and a second plate material 220 are butted together at their end faces, to perform butt welding. As a result, a weld bead 300 extending in the X direction is formed. As shown in FIG. 3B, a laser beam LB is irradiated onto a corner of a joint of the workpiece 200, in which a third plate material 230 and a fourth plate material 240 are overlapped with their end faces shifted, to perform lap fillet welding. However, it goes without saying that the shape of the workpiece 200 to be laser welded is not limited to the examples shown in FIGS. 3A and 3B.

[0033] [Laser welding method] Fig. 4 shows the weaving trajectory of the laser light and its change over time. In Fig. 4 and the subsequent drawings, the movement direction of the laser head 30, in other words, the traveling direction of the laser light LB, is defined as the +X direction, and the opposite direction is defined as the -X direction. In addition, in the Y direction, as shown in Fig. 4, the direction from the line indicating the X direction toward the top of the paper is defined as the +Y direction, and the opposite direction is defined as the -Y direction.

[0034] Fig. 4(a) shows the weaving trajectory of the laser beam LB when the position of the laser head 30 is fixed, and Fig. 4(b) shows the change in the weaving trajectory over time. Fig. 4(b) corresponds to the weaving trajectory of the laser beam LB on the surface of the workpiece 200 when the laser head 30 is moved in the X direction at a constant speed.

[0035] In this specification, "weaving" refers to scanning the laser beam LB along a trajectory or at a speed different from the trajectory of the laser beam LB while moving the laser beam LB in a predetermined traveling direction (welding direction). For example, when the laser beam LB is moved in the +X direction and weaved by linearly reciprocating in the Y direction at a constant speed, the trajectory of the laser beam LB becomes a triangular wave-shaped weaving trajectory (see FIG. 5(b)). Also, when the laser beam LB is moved in the +X direction and weaved in a circular shape in a predetermined direction, the trajectory of the laser beam LB becomes a spiral weaving trajectory (see FIG. 12(b)). In this way, laser welding that draws various types of weaving trajectories can be performed using the laser welding apparatus 100.

[0036] As shown in (a) of Figure 4, the laser beam weaves back and forth along the Y direction to trace a linear first weaving locus (first weaving; first weaving step). That is, the laser beam LB weaves in the width direction of the weld bead 300 (see Figure 3A). The amplitude of the first weaving locus in the Y direction is a first amplitude A1.

[0037] On the other hand, at the end of the first weaving locus in the +Y direction, the laser light LB weaves by going back and forth once to draw a linear third weaving locus along the Y direction (third weaving). At the end of the -Y direction, the laser light LB weaves by going back and forth once to draw a linear fourth weaving locus along the Y direction (fourth weaving). The third weaving and fourth weaving operations are collectively referred to as the second weaving step. Note that in Modifications 1 to 4 described below, the weaving operations further performed at both ends of the first weaving locus are also referred to as the second weaving step.

[0038] The amplitude of the third weaving locus in the Y direction is a third amplitude A3, and the amplitude of the fourth weaving locus in the Y direction is a fourth amplitude A4. Also, as shown in (b) of Figure 4, the number of weaving times of the laser light LB is one at each of the end in the +Y direction and the end in the -Y direction.

[0039] The steps of first weaving (weaving direction: +Y direction) → third weaving → first weaving (weaving direction: -Y direction) → fourth weaving are repeated multiple times in this order. As a result, the weaving trajectory of laser light LB on the time axis becomes a triangular wave with a first amplitude A1, as shown in FIG. 4(b). A triangular wave with a third amplitude A3 is superimposed on the peak of this triangular wave in the +Y direction, and a triangular wave with a fourth amplitude A4 is superimposed on the peak of the -Y direction. In other words, laser light LB weaves in the width direction at the ends of weld bead 300 in the width direction, or so-called edges.

[0040] The third amplitude A3 may be the same as or different from the fourth amplitude A4. For example, the third amplitude A3 may be greater than or smaller than the fourth amplitude A4. In this case, the sum of the third amplitude A3 and the fourth amplitude A4 is preferably less than the first amplitude A1, and more preferably less than half of the first amplitude A1.

[0041] By irradiating the surface of workpiece 200 with laser light LB traveling in the +X direction and weaving in the Y direction as described above, workpiece 200 is laser welded, and for example, weld bead 300 shown in FIG. 3A is formed (welding step).

[0042] [Effects, etc.] As described above, the laser welding method according to this embodiment includes at least a welding step of irradiating the surface of the workpiece 200 with laser light LB while traveling in the X direction (first direction) and weaving in the Y direction (second direction) intersecting the X direction.

[0043] The welding step includes at least a first weaving step in which the laser light LB is weaved in the Y direction with a first amplitude A1, and a second weaving step in which the laser light LB is weaved with a predetermined amplitude smaller than the first amplitude A1 at both ends of the weaving path traced by the laser light LB in the first weaving step.

[0044] In this embodiment, in the first weaving step, the laser light LB is woven so as to draw a linear first weaving locus along the Y direction.

[0045] According to this embodiment, at both ends of the first weaving locus, the laser beam LB is irradiated onto the workpiece 200 by weaving in the same Y direction as the first weaving step. This makes it possible to increase the heat input into the workpiece 200 by the laser beam LB at both ends of the first weaving locus. This will be further explained.

[0046] Fig. 5 shows the weaving trajectory of the laser light according to Comparative Example 1 and its change over time. Note that Fig. 5(a) and Fig. 5(b) correspond to Fig. 4(a) and Fig. 4(b), respectively. That is, Fig. 5(a) shows the weaving trajectory of the laser light LB when the position of the laser head 30 is fixed, and Fig. 5(b) shows the change over time of the weaving trajectory, in other words, the weaving trajectory of the laser light LB on the surface of the workpiece 200 when the laser head 30 is moved in the X direction at a constant speed.

[0047] 6 to 9 and 11 and 12 (a) and (b) shown below correspond to (a) and (b) in FIG. 4, and the same relationship applies thereto.

[0048] The weaving locus of the laser beam LB shown in Fig. 5 corresponds to conventional weaving. That is, the laser beam LB weaves by linearly reciprocating along the Y direction, but no further weaving of the laser beam LB is performed at the end of the linear weaving locus.

[0049] In such a case, as described above, a large amount of heat diffuses from the molten portion of the workpiece 200 to the surrounding area at the end of the linear weaving path. Since the laser beam LB stays for a shorter time at the end of the weaving path than at the center of the weaving, less energy is input to this portion. As a result, the heat input is insufficient at the weld bead 300 corresponding to the end of the linear weaving path, resulting in insufficient penetration of the workpiece 200. This can result in a deterioration in the shape of the weld bead 300.

[0050] On the other hand, according to this embodiment, the heat input to workpiece 200 by laser beam LB can be increased at both ends of the linear first weaving locus compared to the conventional method shown in Fig. 5. As a result, the shape of weld bead 300 can be made smooth and uniform, and weld bead 300 with a good shape can be formed.

[0051] The first weaving step and the second weaving step are performed alternately.

[0052] 3A, when the workpiece 200 is made up of two plate materials 210, 220 with their end faces butted together, laser welding is performed by irradiating the laser beam LB by the above-described method to the butted portion of the two plate materials 210, 220. When the workpiece 200 is made up of two plate materials 230, 240 with their end faces shifted and overlapped, as shown in FIG. 3B, when the workpiece 200 is made up of two plate materials 230, 240 with their end faces shifted and overlapped, laser welding is performed by irradiating the laser beam LB by the above-described method to the corners of the overlapping portions of the two plate materials 230, 240.

[0053] In the workpiece 200 shown in Fig. 3A, when the thickness of the first plate material 210 is different from the thickness of the second plate material 220, a thermal imbalance may occur at both ends of the linear weaving path in the method shown in Fig. 5. Also, in the lap fillet welding shown in Fig. 3B, a similar thermal imbalance occurs at the end on the third plate material 230 side and the end on the fourth plate material 240 side.

[0054] On the other hand, according to this embodiment, for example, in the second weaving step, by making the amplitude of the laser beam LB larger at one end of the first weaving locus than at the other end, the residence time of the laser beam LB at this portion can be extended, thereby eliminating such thermal imbalance. As a result, a well-shaped weld bead 300 can be formed even in butt welding shown in FIG. 3A or lap fillet welding shown in FIG. 3B.

[0055] Furthermore, according to this embodiment, even in cases where a gap may occur at the welded portion of the workpiece 200, such as in the butt welding shown in FIG. 3A, the laser light LB can melt a sufficient amount of metal to fill the gap, thereby forming a weld bead 300 with a good shape.

[0056] Furthermore, according to this embodiment, the shape of weld bead 300 can be improved by changing third amplitude A3 and fourth amplitude A4 depending on the shape, material, etc. of workpiece 200. For example, if workpiece 200 is made of a material that easily diffuses heat, the amount of heat input at both ends of the first weaving locus can be ensured by increasing third amplitude A3 and fourth amplitude A4. Furthermore, if workpiece 200 is made of a material that does not easily diffuse heat, the amount of heat input at both ends of the first weaving locus can be suppressed by decreasing third amplitude A3 and fourth amplitude A4, and the shape of weld bead 300 can be made smooth and uniform.

[0057] The laser welding apparatus 100 of this embodiment includes at least a laser oscillator 10 that generates laser light LB, a laser head 30 that receives the laser light LB and irradiates it toward the workpiece 200, and a controller 50 that controls the operation of the laser head 30.

[0058] The laser head 30 has a laser beam scanner 40 that scans the laser beam LB in both an X direction (first direction) and a Y direction (second direction) that intersects with the X direction. The laser beam scanner 40 scans the laser beam LB at least in the Y direction.

[0059] The controller 50 controls and drives the laser beam scanner 40 so that the laser beam LB weaves in the Y direction at a first amplitude A1. The controller 50 also controls and drives the laser beam scanner 40 so that the laser beam LB weaves at a predetermined amplitude smaller than the first amplitude A1 at both ends of the weaving locus of the first amplitude A1 drawn by the laser beam LB.

[0060] In this embodiment, the controller 50 drives and controls the laser beam scanner 40 so that the laser beam LB traces a linear first weaving locus with a first amplitude A1. Furthermore, the controller 50 drives and controls the laser beam scanner 40 so that the laser beam LB traces a linear third weaving locus with a third amplitude A3 at one end (end in the +Y direction) of the first weaving locus, and so that the laser beam LB traces a linear fourth weaving locus with a fourth amplitude A4 at the other end (end in the -Y direction).

[0061] By configuring laser welding apparatus 100, and particularly controller 50, in this manner, it is possible to increase the heat input to workpiece 200 by laser beam LB at both ends of the first weaving locus. As a result, it is possible to make the shape of weld bead 300 smooth and uniform, and it is possible to form weld bead 300 with a good shape.

[0062] The controller 50 controls the driving of the laser beam scanner 40 so that the weaving of the laser beam LB at the first amplitude A1 and the weaving at a predetermined amplitude are alternately repeated.

[0063] The laser welding apparatus 100 further includes a manipulator 60 to which the laser head 30 is attached, and the controller 50 controls the operation of the manipulator 60. The manipulator 60 moves the laser head 30 in a predetermined direction relative to the surface of the workpiece 200.

[0064] In this way, the welding direction of the laser beam LB can be changed by providing the manipulator 60. Furthermore, laser welding can be easily performed on the workpiece 200 having a complex shape, for example, a three-dimensional shape.

[0065] The laser oscillator 10 and the laser head 30 are connected by an optical fiber 20 , and the laser light LB is transmitted from the laser oscillator 10 to the laser head 30 through the optical fiber 20 .

[0066] By providing the optical fiber 20 in this manner, it becomes possible to perform laser welding on the workpiece 200 that is placed at a position distant from the laser oscillator 10. This increases the degree of freedom in arranging each part of the laser welding apparatus 100.

[0067] The laser light scanner 40 is composed of a first galvanometer mirror 41 that scans the laser light LB in the X direction, and a second galvanometer mirror 42 that scans the laser light LB in the Y direction.

[0068] By configuring the laser beam scanner 40 in this manner, the laser beam LB can be easily scanned one-dimensionally or two-dimensionally. This allows the laser beam LB to be easily weaved. Furthermore, since a known galvanometer scanner is used as the laser beam scanner 40, an increase in the cost of the laser welding apparatus 100 can be suppressed.

[0069] <Variation 1> FIG. 6 shows the weaving locus of the laser light according to this modification and its change over time.

[0070] This modified example differs from the method shown in embodiment 1 in that in the second weaving step, the laser light LB is woven so as to draw a circular weaving locus at both ends of the first weaving locus shown in Figure 4(a).

[0071] At the end of the first weaving locus in the +Y direction, the laser light LB is weaved so as to draw a circular fifth weaving locus (fifth weaving). The weaving direction of the laser light LB, in this case the rotation direction, is clockwise. A fifth amplitude A5, which corresponds to the diameter of the fifth weaving locus, is smaller than the first amplitude A1. At the end of the -Y direction, the laser light LB is weaved so as to draw a circular sixth weaving locus (sixth weaving). The scanning direction (rotation direction) of the laser light LB is counterclockwise. A sixth amplitude A6, which corresponds to the diameter of the sixth weaving locus, is smaller than the first amplitude A1.

[0072] The fifth amplitude A5 may be the same as or different from the sixth amplitude A6. For example, the fifth amplitude A5 may be greater than or smaller than the sixth amplitude A6. In this case, the sum of the fifth amplitude A5 and the sixth amplitude A6 is preferably less than the first amplitude A1, and more preferably less than half of the first amplitude A1.

[0073] The laser welding method of this modification can also achieve the same effects as the method shown in Embodiment 1. That is, the heat input to workpiece 200 by laser beam LB can be increased at both ends of the first weaving locus. As a result, the shape of weld bead 300 can be made smooth and uniform, and weld bead 300 with a good shape can be formed. Furthermore, weld bead 300 with a good shape can also be formed in butt welding shown in FIG. 3A and lap fillet welding shown in FIG. 3B.

[0074] In the second weaving step, the laser light LB is woven in the counterclockwise direction at the end in the +Y direction, and the laser light LB is woven in the clockwise direction at the end in the -Y direction.

[0075] 6(b), this prevents the weaving path of laser beam LB from unnecessarily extending in the Y direction on the surface of workpiece 200. This allows the width of weld bead 300 to be set to a desired value, and also allows weld bead 300 to be formed with a good shape.

[0076] In the laser welding apparatus 100 of this modification, the controller 50 drives and controls the laser beam scanner 40 so that the laser beam weaves linearly in the Y direction at the first amplitude A1. Furthermore, the controller 50 drives and controls the laser beam scanner 40 so that the laser beam weaves circularly at the fifth amplitude A5 or the sixth amplitude A6 at both ends of the first weaving locus.

[0077] This modification can achieve the same effects as those achieved by the configuration shown in embodiment 1. That is, the heat input to workpiece 200 by laser beam LB can be increased at both ends of the first weaving locus. As a result, the shape of weld bead 300 can be made smooth and uniform, and weld bead 300 with a good shape can be formed.

[0078] <Variation 2> FIG. 7 shows the scanning locus of the laser light according to this modification and its change over time.

[0079] In this modified example, in the second weaving step, at the +Y end of the first weaving locus, the laser light LB is woven in a counterclockwise direction to draw a circular seventh weaving locus (seventh weaving), and at the -Y end, the laser light LB is woven in a clockwise direction to draw a circular eighth weaving locus (eighth weaving), which is different from the method and configuration shown in modified example 1.

[0080] The seventh amplitude A7, which corresponds to the diameter of the seventh weaving locus, and the eighth amplitude A8, which corresponds to the diameter of the eighth weaving locus, are each smaller than the first amplitude A1. The seventh amplitude A7 may be the same as or different from the eighth amplitude A8. For example, the seventh amplitude A7 may be larger than the eighth amplitude A8, or conversely, may be smaller than the eighth amplitude A8. In this case, too, the sum of the seventh amplitude A7 and the eighth amplitude A8 is preferably less than the first amplitude A1, and more preferably equal to or less than half of the first amplitude A1.

[0081] This modification can also achieve the same effects as those achieved by the configuration shown in embodiment 1. That is, the heat input to workpiece 200 by laser beam LB can be increased at both ends of the first weaving locus. As a result, the shape of weld bead 300 can be made smooth and uniform, and weld bead 300 with a good shape can be formed.

[0082] The choice between the method shown in Modification 1 and the method shown in this modification is based on the selection of the heat input distribution or bead shape at both ends of the first weaving locus. The selection of the heat input distribution or bead shape is determined appropriately based on the material and shape of workpiece 200, as well as the dimensional constraints required for weld bead 300.

[0083] <Variation 3> FIG. 8 shows the weaving locus of the laser light according to this modification and its change over time, and FIG. 9 shows the contribution of each part to the weaving locus of the laser light.

[0084] This modified example differs from the method and configuration shown in the first embodiment in that in the second weaving step, the laser light LB is weaved by reciprocating in the X direction. Specifically, at the end of the first weaving locus in the +Y direction, the laser light LB is weaved by reciprocating in the X direction with a ninth amplitude A9 (ninth weaving). On the other hand, at the end of the first weaving locus in the -Y direction, the laser light LB is weaved by reciprocating in the X direction with a ninth amplitude A9. 10 Weave back and forth in the X direction (10th weaving).

[0085] The 9th amplitude A9 is the 10th amplitude A 10 For example, the ninth amplitude A9 may be the same as or different from the tenth amplitude A 10 It may be larger than or, conversely, smaller than.

[0086] As shown in FIG. 8(b), in this modification, the weaving locus of the laser light LB on the time axis does not change in the Y direction at the peak of the triangular wave. Instead, the peak is extended on the time axis, and the weaving locus of the laser light LB on the time axis becomes trapezoidal. At the end of the weaving locus of the laser light LB on the time axis in the +Y direction, the laser light LB is irradiated at the ninth weaving time t9. At the end of the weaving locus of the laser light LB on the time axis in the -Y direction, the laser light LB is irradiated at the tenth weaving time t 10 It is irradiated with.

[0087] This modification can also achieve the same effects as the configuration shown in embodiment 1. That is, by irradiating both ends of the first weaving locus with laser beam LB for a longer period of time than shown in embodiment 1, the heat input to workpiece 200 by laser beam LB can be increased. As a result, the shape of weld bead 300 can be made smooth and uniform, and weld bead 300 with a good shape can be formed.

[0088] In particular, according to this modification, more heat can be input only to the two end portions of the first weaving locus, thereby making it possible to form weld bead 300 in a smooth and favorable shape.

[0089] In this modification, the traveling direction (welding direction) of the laser beam LB and the weaving direction of the laser beam LB in the second weaving step are parallel, that is, they are the same X direction.

[0090] Therefore, as shown in FIG. 9, the ninth amplitude A9 and the tenth amplitude A 10 The moving distance of the manipulator 60 corresponding to the weaving period is added to the amplitude of the laser beam LB to determine the actual weaving amplitude of the laser beam LB.

[0091] <Variation 4> FIG. 10 shows an example of a combination of laser beam weaving methods according to this modification.

[0092] The weaving loci of the laser light LB in the second weaving step shown in FIG. 4 and FIGS. 6 to 8 can be appropriately combined to form new modified examples.

[0093] 10 correspond to feasible combinations that are not shown in the first embodiment and modified examples 1 to 3. For example, the fifth weaving may be performed at the end of the first weaving locus in the +Y direction, and the eighth weaving may be performed at the end of the first weaving locus in the -Y direction.

[0094] That is, as shown in FIG. 10, the weaving locus of the laser light LB at the +Y direction end of the first weaving locus may be any one of the third, fifth, seventh, and ninth weaving loci shown in FIG. 4 and FIGS. 6 to 8, and the weaving locus of the laser light LB at the -Y direction end may be any one of the fourth, sixth, eighth, and tenth weaving loci shown in FIG. 4 and FIGS. 6 to 8.

[0095] Furthermore, the weaving direction of the laser light LB in the second weaving step may be different between one end and the other end of the first weaving locus. For example, the laser light LB may be caused to weave in the Y direction at one end and the X direction at the other end. Alternatively, the laser light LB may be caused to weave in the clockwise direction at one end and the counterclockwise direction at the other end. The amplitude of the laser light LB in the second weaving step may be different between one end and the other end of the first weaving locus.

[0096] In this way, the weaving locus of laser light LB in the second weaving step can be selected as appropriate depending on the material and shape of workpiece 200, as well as dimensional constraints required for weld bead 300, and the like.

[0097] That is, the controller 50 of the laser welding apparatus 100 controls the driving of the laser beam scanner 40 so that the laser beam LB traces a linear first weaving locus with a first amplitude A1 in the Y direction.

[0098] Furthermore, the laser beam scanner 40 is driven and controlled so that the laser beam LB is weaved in either the X direction or the Y direction or weaved in a circular shape with a predetermined amplitude at least at one of both end portions of the first weaving locus.

[0099] (Embodiment 2) FIG. 11 shows the weaving locus of the laser light according to this embodiment and its change over time, and FIG. 12 shows the weaving locus of the laser light according to Comparative Example 2 and its change over time.

[0100] 11(a), this embodiment differs from the method and device shown in Embodiment 1 in that, in the first weaving step, the laser light LB is woven so as to draw a circular second weaving locus (second weaving). The rotation direction of the second weaving locus is counterclockwise.

[0101] Furthermore, at the starting point of the second weaving locus, that is, the end portion in the +Y direction of the second weaving locus shown in Fig. 11(a), the laser light LB is further woven so as to draw a circular eleventh weaving locus (eleventh weaving). This eleventh weaving is also called the second weaving step.

[0102] The rotation direction of the 11th weaving locus is also counterclockwise. 11 is smaller than the second amplitude A2, which corresponds to the diameter of the second weaving locus.

[0103] This embodiment can achieve the same effects as those achieved by the configuration shown in Embodiment 1. That is, the heat input by laser beam LB to workpiece 200 can be increased at the start point of the second weaving locus, which is the end in the +Y direction of the spiral weaving locus of laser beam LB in FIG. 11(b). As a result, the shape of weld bead 300 can be made smooth and uniform, and weld bead 300 with a good shape can be formed.

[0104] That is, according to this embodiment, as shown in (b) of Fig. 11, at the end of the spiral weaving locus in the +Y direction, the locus of the laser beam LB becomes a composite locus of two counterclockwise rotation loci. This makes it possible to suppress the occurrence of imbalance in heat input at the end. This will be further explained.

[0105] For example, consider the case where the laser beam LB is weaved so as to trace a circular weaving locus in the counterclockwise direction as shown in (a) of Fig. 12. In this case, as shown in (b) of Fig. 12, the laser beam LB is woven so as to trace a spiral weaving locus on the time axis, in other words, in the +X direction. Furthermore, at the end of the spiral weaving locus in the +Y direction, the locus of the laser beam LB is always counterclockwise.

[0106] 12(b), when laser beam LB is irradiated onto the surface of workpiece 200, the duration of laser beam LB at the end in the +Y direction is shorter than that at the end in the -Y direction, causing an imbalance in heat input between the +Y direction end and the -Y direction end of the bead. When such an imbalance occurs, there is a risk that the shape of weld bead 300 will be distorted, particularly at the end in the +Y direction.

[0107] On the other hand, according to this embodiment, at the end of the spiral weaving locus in the +Y direction, two counterclockwise weavings of laser beam LB are combined, which prevents imbalance in heat input to the end, as described above. This makes it possible to smooth the shape of weld bead 300, and to form weld bead 300 with a good shape.

[0108] It should be noted that the weaving locus of the laser beam LB in the second weaving step in this embodiment is not particularly limited to that shown in Fig. 11. For example, the laser beam LB may be woven so as to trace any one of the third, fifth, seventh and ninth weaving loci shown in the first embodiment and the first to third modifications.

[0109] In the explanation of Figure 11, the rotation directions of the second weaving and the eleventh weaving are described as counterclockwise, but they may both be selected to rotate clockwise as appropriate depending on the material of the workpiece 200, the joint shape, etc.

[0110] That is, the controller 50 of the laser welding apparatus 100 of this embodiment controls the driving of the laser beam scanner 40 so that the laser beam LB traces a circular second weaving locus.

[0111] Furthermore, at the start point of the second weaving locus, the laser beam scanner 40 is driven and controlled so as to weave the laser beam in either the X direction or the Y direction with a predetermined amplitude, or to weave in a circular shape.

[0112] (Embodiment 3) 13 shows the weaving locus and output change over time of the laser light according to embodiment 3. Note that (a) of FIG. 13 is the same as (b) of FIG.

[0113] This embodiment differs from the method and apparatus shown in the first and second embodiments in that the output of the laser light LB is changed between the first weaving step and the second weaving step.

[0114] For example, in the method shown in the first embodiment, as shown in FIG. 13(b), the output of the laser light LB is constant (=P1) in the first weaving step and the second weaving step.

[0115] However, depending on the shape and material of the workpiece 200, the heat input by the laser beam LB may be insufficient or excessive at the welding point. For example, in Fig. 3A, if the plate thickness of the first plate material 210 and the second plate material 220 differs significantly, the heat input may be excessive on the thinner plate side and insufficient on the thicker plate side. In this case, not only may the shape of the weld bead 300 deteriorate, but there is also a risk of welding defects such as melt-through of the plate material or insufficient fusion.

[0116] On the other hand, according to this embodiment, the above-mentioned problem can be improved by changing the output of the laser light LB at each end of the linear first weaving trajectory depending on the shape and material of the workpiece 200.

[0117] For example, as shown in FIG. 13(c), the output of the laser beam LB may be reduced in the second weaving step compared to the first weaving step. For example, if the shape of the workpiece 200 is a butt joint structure of two plate materials of different thicknesses, the output may be reduced at one end of the first weaving path in the Y direction compared to the other end. In the example shown in FIG. 13(c), the output of the laser beam LB is reduced to P2 from P1 at the end of the first weaving path in the +Y direction. Furthermore, the output of the laser beam LB is reduced to P3 from P2 at the end of the -Y direction.

[0118] Also, as shown in Fig. 13(d), in the second scanning step, the output of the laser light LB may be increased more than that in the first scanning step. In the example shown in Fig. 13(d), the output of the laser light LB is increased more than P1 at the end of the first weaving locus in the -Y direction to P2. Furthermore, the output of the laser light LB is increased more than P2 at the end of the +Y direction to P3.

[0119] By doing so, the amount of heat input to the edge of weld bead 300 can be increased, and a weld bead with a good shape can be formed according to the material and shape of workpiece 200.

[0120] In the example shown in FIG. 13(c), the output of the laser light LB may be set to P3 at the end of the first weaving locus in the +Y direction, and the output of the laser light LB may be set to P2 at the end of the first weaving locus in the -Y direction. Also, P2 and P3 may be set to the same value. In the example shown in FIG. 13(d), the output of the laser light LB may be set to P3 at the end of the first weaving locus in the -Y direction, and the output of the laser light LB may be set to P2 at the end of the first weaving locus in the +Y direction. Also, P2 and P3 may be set to the same value.

[0121] Also, the output of the laser light LB may be changed from the first scanning step only at either the end in the +Y direction or the end in the −Y direction of the first weaving locus.

[0122] That is, the controller 50 of the laser welding apparatus 100 of this embodiment controls the operation of the laser oscillator 10, and drives and controls the laser oscillator 10 so as to change the output of the laser light LB at least at one of the two end portions of the first weaving locus.

[0123] Furthermore, the controller 50 may control the driving of the laser oscillator 10 so as to change the output of the laser light LB between one end and the other end of the first weaving locus.

[0124] (Other embodiments) New embodiments can also be created by appropriately combining the components shown in Embodiments 1 to 3 and Modifications 1 to 4. For example, in Modifications 1 to 4, the output of the laser light LB at one end or the other end, or both, of the first weaving locus may be changed from the output in other portions. Also, in Embodiment 2, the output of the laser light LB at the start point of the second weaving locus may be changed from the output in other portions.

[0125] In addition, in the first embodiment and modifications 1 to 4, the weaving locus of the laser light LB on the time axis in the first weaving step is triangular wave-shaped, but it may be sinusoidal. In addition, in the first and third embodiments, the weaving locus of the laser light LB on the time axis in the second weaving step is triangular wave-shaped, but it may be sinusoidal.

[0126] In the first and third embodiments, the number of weaving steps in the second weaving step is described as one, but it may be multiple.

[0127] In the example shown in FIG. 1, the focusing lens 34 is arranged in front of the laser light scanner 40, but it may also be arranged in the rear of the laser light scanner 40, that is, between the laser light scanner 40 and the light emission port of the laser head 30. [Industrial Applicability]

[0128] The laser welding method and laser welding method of the present disclosure are useful in that they can form a well-shaped weld bead. [Explanation of symbols]

[0129] 10 Laser oscillator 20 Optical Fiber 30 laser head 31 Case 32 Collimation Lens 33 Reflective mirror 34 Condenser Lens 40 Laser light scanner 41 First Galvanometer Mirror 41a 1st mirror 41b First rotation axis 41c First drive unit 42 Second Galvanometer Mirror 42a 2nd mirror 42b Second rotation axis 42c Second drive unit 100 Laser welding equipment 200 Work 300 Weld Bead

Claims

1. The method includes at least a welding step of irradiating a surface of a workpiece with a laser beam while advancing the laser beam in a first direction and weaving the laser beam in a second direction intersecting the first direction, The welding step includes: a first weaving step of weaving the laser light in the second direction with a first amplitude; a second weaving step of weaving the laser beam at a predetermined amplitude smaller than the first amplitude at at least one end of a weaving locus drawn by the laser beam in the first weaving step, In the first weaving step, the laser light is woven so as to draw a linear first weaving locus along the second direction; a second weaving step for weaving the laser beam so as to trace a circular second weaving locus;

2. The laser welding method according to claim 1, a second weaving step for changing an output of the laser beam from the first weaving step at least at one of both end portions of the first weaving path;

3. The laser welding method according to claim 2, A laser welding method, characterized in that the output of the laser light is changed at one end and the other end of the first weaving locus.

4. 4. The laser welding method according to claim 1, a laser welding method characterized in that, in the second weaving step, the laser beam is weaved in the second direction at at least one of both ends of a linear first weaving locus drawn by the laser beam or at a starting point of a circular second weaving locus drawn by the laser beam.

5. 5. The laser welding method according to claim 1, a laser welding method characterized in that, in the second weaving step, the laser beam is weaved in the first direction at at least one of both ends of a linear first weaving locus drawn by the laser beam, or at a starting point of a circular second weaving locus drawn by the laser beam.

6. 6. The laser welding method according to claim 1, a laser welding method characterized in that, in the second weaving step, the laser beam is weaved so as to trace a circular weaving locus at at least one of both end portions of a linear first weaving locus traced by the laser beam or at a starting point of a circular second weaving locus traced by the laser beam.

7. The laser welding method according to claim 6, a second weaving step of weaving the laser beam in a clockwise direction at one end of the first weaving locus and weaving the laser beam in a counterclockwise direction at the other end of the first weaving locus.

8. The laser welding method according to any one of claims 4 to 7, a weaving direction of the laser beam in the second weaving step that is different from one end and the other end of the first weaving locus;

9. 9. The laser welding method according to claim 6, a weaving direction of the laser beam in the second weaving step being the same as or different from a weaving direction when the laser beam traces the first weaving locus in the first weaving step.

10. The laser welding method according to any one of claims 1 to 9, A laser welding method, characterized in that the amplitude of the laser beam in the second weaving step is different between one end and the other end of the linear first weaving locus drawn by the laser beam.

11. The laser welding method according to any one of claims 1 to 10, The workpiece is composed of two plate materials whose end faces are butted against each other, A laser welding method, characterized in that the laser beam is irradiated onto the butted portion of the two plate materials.

12. The laser welding method according to any one of claims 1 to 10, The workpiece is composed of two plate materials overlapped with their end faces shifted from each other, A laser welding method characterized in that the laser beam is irradiated onto a corner portion of the overlapping portion of the two plate materials.

13. a laser oscillator that generates laser light; a laser head that receives the laser light and irradiates it toward a workpiece; a controller for controlling the operation of the laser head; the laser head has a laser beam scanner that scans at least in a second direction intersecting a first direction that is a traveling direction of the laser beam, the controller weaves the laser light in the second direction with a first amplitude; Further, driving and controlling the laser beam scanner so that the laser beam weaves at a predetermined amplitude smaller than the first amplitude at at least one end of the weaving locus of the first amplitude drawn by the laser beam, the controller weaves the laser beam so as to draw a linear first weaving locus; Further, the laser beam scanner is driven and controlled so as to weave the laser beam in either the first direction or the second direction, or to weave the laser beam in a circular shape, at least at one of both end portions of the first weaving locus; the controller weaves the laser beam so as to draw a circular second weaving locus; The laser welding device further comprises: a laser beam scanner that drives and controls the laser beam scanner so that the laser beam is weaved in either the first direction or the second direction, or in a circular shape, at a starting point of the second weaving locus.

14. 14. The laser welding apparatus according to claim 13, the controller further controls the operation of the laser oscillator; A laser welding device comprising: a laser oscillator that is driven and controlled so as to change the output of the laser light at least at one of both end portions of the first weaving locus.

15. 15. The laser welding apparatus according to claim 14, The laser welding device is characterized in that the controller drives and controls the laser oscillator so as to change the output of the laser light at one end and the other end of the first weaving locus.

16. 16. The laser welding apparatus according to claim 13, a laser welding device characterized in that the laser beam scanner is composed of a first galvanometer mirror that scans the laser beam in the first direction and a second galvanometer mirror that scans the laser beam in the second direction.

17. 17. The laser welding apparatus according to claim 13, the laser head further includes a focal position adjustment mechanism; The laser welding device is characterized in that the focal position adjustment mechanism is configured to change the focal position of the laser light along directions that intersect with each of the first direction and the second direction.

Images