WO2022075211A1 - Laser welding method and laser welding device - Google Patents

Abstract

This laser welding method comprises a welding step in which a workpiece is welded by scanning laser light, while the laser light is advanced in an X direction, two-dimensionally and irradiating a surface of the workpiece therewith so as to trace prescribed patterns. The laser light is scanned so that a first drawing pattern, of the prescribed patterns, that is located in front of an origin point in the X direction is a wider pattern in a Y direction than a second drawing pattern that is located behind the origin point. The output of the laser light is controlled so that the output of the laser light during the drawing of the first drawing pattern is lower than the output of the laser light during the drawing of the second drawing pattern.

Description

Laser welding method and laser welding equipment

This disclosure relates to a laser welding method and a laser welding apparatus.

Laser welding has a high power density of laser light shining on the work to be welded, so high-speed and high-quality welding can be performed. In particular, in scanning welding in which welding is performed while scanning the laser beam on the surface of the work at high speed, the laser beam can be moved to the next welding point at high speed during the non-welding period, thus shortening the total welding time. (See, for example, Patent Document 1). Further, as for the method of scanning the laser beam, a method of scanning the laser beam so as to draw a resage pattern on the surface of the work has been conventionally proposed (see, for example, Patent Document 2 and Patent Document 3). Further, scanning welding is applied not only to ordinary steel materials but also to thin plate welding of steel materials surface-treated such as zinc plating (see, for example, Patent Document 4).

Japanese Unexamined Patent Publication No. 2005-095934 Japanese Unexamined Patent Publication No. 60-177983 Japanese Unexamined Patent Publication No. 11-104877 Japanese Patent No. 4915315

By the way, the boiling point of zinc (906 ° C) is significantly lower than the melting point of iron (1535 ° C). For this reason, in lap welding in which two steel plates having a zinc-plated layer formed on their respective surfaces are laminated and welded in a gapless manner, the zinc-plated layer interposed in the laminated surface of the steel plates reaches the evaporation temperature before the iron melts. Will reach. The generated zinc vapor may destabilize the keyhole or the molten pool, form porosity inside the work, or, in the extreme case, blow off the molten pool, resulting in welding defects.

However, in the conventional configurations disclosed in Patent Documents 1 to 3, nothing is disclosed regarding the lap welding of the steel plate on which the zinc-plated layer is formed, and neither is the above-mentioned problem.

On the other hand, in Patent Document 4, there is a method of weaving a laser beam back and forth along the welding direction and lowering the output of the laser beam in the forward step of weaving forward to be lower than that in the reverse step of weaving backward. It has been disclosed. By doing so, it is possible to weld the steel plates to each other after removing the zinc plating layer.

However, in the method disclosed in Patent Document 4, the trajectory of the laser beam overlaps between the forward step and the reverse step. Further, the width of the laser beam in the direction intersecting the welding direction is the same in the forward step and the reverse step. As a result, it is not possible to secure a sufficient area for removing the zinc plating layer with respect to the welded area, and there is a possibility that welding defects may occur.

The present disclosure has been made in view of this point, and an object thereof is to suppress the occurrence of welding defects in lap welding of a plate material on which a coating layer such as a zinc plating layer is formed, and to obtain a weld bead having a good shape. It is an object of the present invention to provide a laser welding method and a laser welding apparatus.

In order to achieve the above object, in the laser welding method according to the present disclosure, the work is welded by scanning the laser light two-dimensionally and irradiating the surface of the work while advancing the laser light in the welding direction. The work has a structure in which the plate-shaped portions are overlapped with each other in two base materials including the plate-shaped portions, and a coating layer is formed at least on the surface of the plate-shaped portions. Yes, the boiling point of the coating layer is lower than the melting point of the base metal, and in the welding step, a predetermined pattern is drawn on the surface of the work, and the predetermined pattern is along the welding direction. The first drawing pattern located in front of the origin of the predetermined pattern scans the laser beam so as to be a pattern wider in the direction intersecting the welding direction than the second drawing pattern located behind the origin. Then, the output of the laser beam is controlled so that the output of the laser beam during drawing of the first drawing pattern is lower than the output of the laser beam during drawing of the second drawing pattern, and the predetermined state is determined. The pattern is characterized in that two annular patterns having an asymmetrical shape are continuous patterns in contact with each other at the origin.

The laser welding apparatus according to the present disclosure includes a laser oscillator that generates a laser beam, a laser head that receives the laser beam and irradiates the work, and a controller that controls the operation of the laser head and the output of the laser beam. The laser head has a laser light scanner that scans the laser light in each of the first direction and the second direction intersecting the first direction, and the work has a plate-shaped portion. In the two base materials including the base material, the plate-shaped portions are overlapped with each other to form a coating layer at least on the surface of the plate-shaped portions, and the boiling point of the coating layer is higher than the melting point of the base material. When low, the controller is located so that the laser beam draws a predetermined pattern on the surface of the work, and is located in front of the origin of the predetermined pattern along the welding direction among the predetermined patterns. The 1 drawing pattern drives and controls the laser light scanner so that the pattern is wider in the direction intersecting the welding direction than the second drawing pattern located behind the origin, and the controller further controls the first drawing pattern. The output of the laser beam is controlled so that the output of the laser beam during drawing of the drawing pattern is lower than the output of the laser beam during drawing of the second drawing pattern, and the predetermined patterns are asymmetrical with each other. It is characterized in that two annular patterns having a large shape are in contact with each other at the origin and are continuous patterns.

According to the present disclosure, the coating layer between the two plate-shaped portions can be removed, and the generation of welding defects due to the steam generated by the evaporation of the coating layer can be suppressed. Further, the shape of the weld bead formed on the work can be improved.

FIG. 1 is a schematic configuration diagram of a laser welding apparatus according to the first embodiment. FIG. 2 is a schematic configuration diagram of a laser light scanner. FIG. 3 is a schematic cross-sectional view of the work. FIG. 4 is a diagram showing a scanning pattern of laser light. FIG. 5 is a diagram showing a scanning locus of a laser beam along a welding direction. FIG. 6 is a diagram showing the relationship between the drawing position of the laser beam and the output. FIG. 7 is a schematic view showing a state change of the work along the welding direction at the time of laser light irradiation. FIG. 8 is a diagram showing the relationship between the drawing position and the output of the laser beam according to the first modification. FIG. 9 is a schematic view showing a state change of the work along the welding direction at the time of laser light irradiation. FIG. 10 is a diagram showing the relationship between the output of the laser beam and the depth of the keyhole. FIG. 11A is a diagram showing a first scanning pattern of the laser beam according to the second modification. FIG. 11B is a diagram showing a second scanning pattern of the laser beam according to the second modification. FIG. 11C is a diagram showing a third scanning pattern of the laser beam according to the second modification. FIG. 12 is a diagram showing a scanning locus of a laser beam along a welding line according to a second embodiment. FIG. 13A is a diagram showing the relationship between the drawing position and the output of the laser beam at the start of welding. FIG. 13B is a diagram showing the relationship between the drawing position and the output of the laser beam at the end of welding. FIG. 14A is a diagram showing a first scanning pattern of the laser beam according to the modified example 3. FIG. 14B is a diagram showing a second scanning pattern of the laser beam according to the third modification. FIG. 14C is a diagram showing a third scanning pattern of the laser beam according to the modified example 3. FIG. 15 is a diagram showing an outline of the scanning locus of the laser beam according to the third embodiment. FIG. 16A is a diagram showing a first spot pattern. FIG. 16B is a diagram showing a second spot pattern. FIG. 16C is a diagram showing a third spot pattern. FIG. 16D is a diagram showing a fourth spot pattern. FIG. 16E is a diagram showing a fifth spot pattern. FIG. 16F is a diagram showing a sixth spot pattern. FIG. 16G is a diagram showing a seventh spot pattern.

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

(Embodiment 1)
[Construction of laser welding equipment and laser light scanner]
FIG. 1 shows a schematic diagram of the configuration of the laser welding apparatus according to the present embodiment, and FIG. 2 shows a schematic configuration diagram of a laser light scanner. FIG. 3 shows a schematic cross-sectional view of the work.

In the following description, the direction parallel to the traveling direction of the laser beam LB from the reflection mirror 33 toward the laser beam scanner 40 is the X direction, and the direction parallel to the optical axis of the laser beam LB emitted from the laser head 30. The Z direction and the directions orthogonal to the X direction and the Z direction may be referred to as the Y direction, respectively. When the surface of the work 200 is a flat surface, the XY plane including the X direction and the Y direction in the plane may be substantially parallel to the surface or may form a constant angle with the surface.

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.

The laser oscillator 10 is a laser light source that is supplied with electric power from a power source (not shown) to generate laser light LB. The laser oscillator 10 may be composed of a single laser light source or a plurality of laser modules. In the latter case, the laser light emitted from each of the plurality of laser modules is combined and emitted as the laser light LB. Further, the laser light source or the laser module used in the laser oscillator 10 is appropriately selected according to the material of the work 200, the shape of the welded portion, and the like.

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

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 inside the optical fiber 20 toward the laser head 30.

The laser head 30 is attached to the end of the optical fiber 20 and irradiates the work 200 with the laser light LB transmitted from the optical fiber 20.

Further, the laser head 30 has a collimation lens 32, a reflection mirror 33, a condenser lens 34, and a laser light scanner 40 as optical components, and these optical components have a predetermined arrangement relationship inside the housing 31. Is kept and housed.

The collimation lens 32 receives the laser beam LB emitted from the optical fiber 20, converts it into parallel light, and causes it to be incident on the reflection mirror 33. Further, the collimation lens 32 is 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 beam LB can be changed, and the laser beam LB can be appropriately irradiated according to the shape of the work 200. That is, the collimation lens 32 also functions as a focal position adjusting mechanism for the laser beam LB in combination with a drive unit (not shown). The condenser lens 34 may be displaced by the drive unit to change the focal position of the laser beam LB.

The reflection mirror 33 reflects the laser light LB transmitted through the collimation lens 32 and makes it incident on the laser light scanner 40. The surface of the reflection mirror 33 is provided so as to form an optical axis of about 45 degrees with the optical axis of the laser beam LB transmitted through the collimation lens 32.

The condenser lens 34 concentrates the laser light LB reflected by the reflection mirror 33 and scanned by the laser light scanner 40 on the surface of the work 200.

As shown in FIG. 2, the laser light scanner 40 is a known galvano scanner having a first galvano mirror 41 and a second galvano mirror 42. The first galvano mirror 41 has a first mirror 41a, a first rotation shaft 41b, and a first drive unit 41c, and the second galvano mirror 42 has a second mirror 42a, a second rotation shaft 42b, and a second drive unit. It has 42c. The laser beam LB transmitted through the condenser lens 34 is reflected by the first mirror 41a and further reflected by the second mirror 42a to irradiate the surface of the work 200.

For example, the first drive unit 41c and the second drive unit 42c are galvano motors, and the first rotation shaft 41b and the second rotation shaft 42b are output shafts of the motor. Although not shown, the first drive unit 41c is rotationally driven by a driver that operates in response to a control signal from the controller 50, so that the first mirror 41a attached to the first rotation shaft 41b becomes the first rotation shaft. It rotates around the axis of 41b. Similarly, the second drive unit 42c is rotationally driven by a driver that operates in response to a control signal from the controller 50, so that the second mirror 42a attached to the second rotary shaft 42b becomes the axis of the second rotary shaft 42b. Rotate around.

The laser beam LB is scanned in the X direction by the first mirror 41a rotating around the axis of the first rotation shaft 41b to a predetermined angle. Further, the second mirror 42a rotates around the axis of the second rotating shaft 42b to a predetermined angle, so that the laser beam LB is scanned in the Y direction. That is, the laser light scanner 40 is configured to scan the laser light LB two-dimensionally in the XY plane and irradiate the work 200.

The controller 50 controls the laser oscillation of the laser oscillator 10. Specifically, laser oscillation control is performed by supplying control signals such as an output current and an on / off time to a power source (not shown) connected to the laser oscillator 10. Further, the controller 50 controls the output of the laser beam LB.

Further, the controller 50 controls the operation of the laser head 30 according to the content of the selected laser welding program. Specifically, the drive control of the laser light scanner 40 provided on the laser head 30 and the drive unit (not shown) of the collimation lens 32 is performed. Further, 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 at another location, and is called by the controller 50 by a command from the controller 50.

The controller 50 has an integrated circuit such as an LSI or a microcomputer (not shown), and the function of the controller 50 described above is realized by executing a laser welding program which is software on the integrated circuit. A controller 50 that controls the operation of the laser head 30 and a controller 50 that controls the output of the laser beam LB may be provided separately.

The manipulator 60 is an articulated robot and is attached to the housing 31 of the laser head 30. Further, the manipulator 60 is connected to the controller 50 so as to be able to send and receive signals, and moves the laser head 30 so as to draw a predetermined trajectory according to the above-mentioned laser welding program. In addition, another controller (not shown) that controls the operation of the manipulator 60 may be provided.

The laser welding device 100 shown in FIG. 1 can perform laser welding on workpieces 200 having various shapes. For example, as shown in FIG. 3, zinc-plated layers 211 and 221 are formed on the surface thereof, and the laser beam LB is placed on the work 200 in which the first plate material 210 and the second plate material 220 made of steel plates are closely adhered to each other without a gap. Is irradiated, and lap welding is performed. By forming the galvanized layers 211 and 221 on the surfaces of the first plate material 210 and the second plate material 220, respectively, it is possible to prevent the steel plate from rusting. Needless to say, the structure and material of the work 200 to be laser welded are not limited to the example shown in FIG.

[Mathematical expression of Lissajous pattern]
FIG. 4 shows a scanning pattern of the laser beam, and the laser beam LB is scanned so as to draw a Lissajous pattern (hereinafter, also referred to as a Lissajous figure) in the XY plane, in this case, on the surface of the work 200.

The Lissajous pattern shown in FIG. 4 vibrates the laser beam LB in the X direction in a sine wave shape of a predetermined frequency, and in the Y direction, the laser light LB has a sine wave shape having a frequency different from the X direction (1/2 of the frequency in the X direction). Obtained by vibrating. Further, as described above, the scanning pattern of the laser beam LB in the X direction and the Y direction is determined based on the rotational motion of the first mirror 41a and the second mirror 42a. When the position coordinates of the resage pattern obtained by driving the first mirror 41a are X and the position coordinates of the resage pattern obtained by driving the second mirror 42a are Y, the position coordinates X and Y are expressed by the following equations, respectively. It is represented by 1) and (2).

X = a1 × sin (nt) ・ ・ ・ (1)
Y = b1 × sin (mt + φ) ・ ・ ・ (2)
X = a2 × sin (nt) ・ ・ ・ (3)
Y = b2 × sin (mt + φ) ・ ・ ・ (4)
here,
a1: Amplitude of scan pattern LS1 in Lissajous pattern in X direction b1: Amplitude of scan pattern LS1 in Lissajous pattern in Y direction a2: Amplitude of scan pattern LS2 in Lissajous pattern in X direction b2: Amplitude of Lissajous pattern Amplitude of the scanning pattern LS2 in the Y direction n: Frequency of the first mirror 41a m: Frequency of the second mirror 42a t: Time φ: Phase difference when driving the first mirror 41a or the second mirror 42a. Is the amount of angular deviation provided during the rotational movement of the first mirror 41a and the second mirror 42a.

The scanning pattern LS1 (hereinafter, also referred to as the first drawing pattern LS1) is a scanning pattern located on the + side in the X direction in the resage pattern shown in FIG. 4, and is also referred to as the scanning pattern LS2 (hereinafter, also referred to as the second drawing pattern LS2). ) Is a scanning pattern located on the − side in the X direction.

The position coordinates X and Y shown in the equations (1) to (4) are represented by a static coordinate system of the resage pattern in a state where the position of the laser head 30 is fixed.

Further, the frequency n and the frequency m correspond to the drive frequencies of the first mirror 41a and the second mirror 42a, respectively.

As is clear from FIG. 4, the resage pattern of the present embodiment has an asymmetrical shape with respect to the center line extending in the Y direction through the origin O.

The first drawing pattern LS1 located in front of the origin O along the X direction is set to a1 = 1, b1 = 1, n = 1, m = 2, φ = 0 in the equations (1) and (2). Correspond to the case. On the other hand, the second drawing pattern LS2 located behind the origin O has a2 = 0.5, b2 = 0.5, n = 1, m = 2, φ = 0 in the equations (3) and (4). Correspond to the case. That is, the first drawing pattern LS1 is larger than the second drawing pattern LS2 in each of the X direction and the Y direction. Therefore, the drawing length of the first drawing pattern LS1 is longer than the drawing length of the second drawing pattern LS2. It should be noted that a1, a2, b1 and b2 are each normalized by 1 based on the size of the first drawing pattern LS1. Further, the phase difference φ of the equations (1) to (4) may be either 0 degree or 180 degrees.

Further, the pattern in which the first drawing pattern LS1 and the second drawing pattern LS2 are combined is an ∞-shaped resage pattern. The size of the actual Lissajous pattern, that is, the amplitudes in the X direction and the Y direction are in the range of about 1 mm to 10 mm, respectively.

Here, as shown in FIG. 4, the drawing distance of the resage pattern in the predetermined time variation Δt in the X direction is ΔX, the drawing distance in the Y direction is ΔY, and the drawing distance of the resage pattern in the time variation Δt is ΔL. Then, ΔX, ΔY, and ΔL are represented by the following equations (5) to (7), respectively.

ΔX = a1 × n × cos (nt) × Δt ・ ・ ・ (5)
ΔY = b1 × m × cos (mt + φ) × Δt ・ ・ ・ (6)
ΔL = Δt × {(ΔX) ² + (ΔY) ² } ^1/2 ... (7)
Therefore, the drawing speed V of the resage pattern is expressed by the following equation (8).

V = ΔL / Δt ・ ・ ・ (8)
The formulas (5) to (8) are formulas related to LS1 created based on the formulas (1) to (2), but similarly, LS2 is based on the formulas (3) to (4). You can create formulas for. Here, the details are omitted.

[Laser welding method]
FIG. 5 shows the scanning locus of the laser beam along the welding direction, and the outer shape of the plurality of resage patterns shown in the figure corresponds to the outer shape of the weld bead. Further, the plurality of resage patterns shown in the figure each indicate a change in the position of the drawing pattern with respect to time when the laser beam LB travels along the welding direction. FIG. 6 shows the relationship between the drawing position of the laser beam and the output, and FIG. 7 schematically shows the state change of the work along the welding direction when the laser beam is irradiated.

The resage pattern shown in FIG. 4 is obtained by scanning the laser beam LB from the origin O in the direction of the arrow AR1 and the arrow AR2 shown in FIG. 4 during one cycle. Specifically, the laser beam LB is scanned so as to pass from the origin O to the drawing position A → B → C → O → D → E → F → O during one cycle.

In the present embodiment, the surface of the work 200 is irradiated with the laser beam LB while the laser head 30 is moved in the + direction in the X direction (hereinafter, may be referred to as the welding direction WD) at a predetermined speed by the manipulator 60. There is. Further, the laser light scanner 40 is used to two-dimensionally scan the laser light LB so as to draw the resage pattern shown in FIG. 4 on the surface of the work 200. Further, in the present embodiment, the case where the work 200 shown in FIG. 3 is laminated and welded will be described as an example.

As shown in FIG. 4, among the resage patterns, the first drawing pattern LS1 drawn in front of the origin O along the welding direction WD is X more than the second drawing pattern LS2 drawn behind the origin O. The scanning amplitude is large in both the direction and the Y direction. Specifically, in the equations (1) and (2), when a1 = 1, b1 = 1, n = 1, and m = 2, the first drawing pattern LS1 shown in FIG. 4 is obtained. Further, in the equations (3) and (4), when a2 = 0.5, b2 = 0.5, n = 1, and m = 2, the second drawing pattern LS2 shown in FIG. 4 is obtained.

As is clear from this, the scanning width LAC of the first drawing pattern LS1 in the Y direction is twice as wide as the scanning width LDF of the second drawing pattern LS2 in the Y direction. Further, as shown in FIG. 5, the scanning width LAC corresponds to the width in the Y direction from which the zinc plating layers 211 and 221 are removed (hereinafter, also referred to as the zinc plating layer removal width LAC), and the scanning width LDF is the work. It corresponds to a welding width of 200 (hereinafter, also referred to as a welding width LDF). The weld width LDF corresponds to the width of the weld bead (not shown) in the Y direction, but the two often do not completely match. This is because the width of the actual weld bead in the Y direction is often slightly wider than the weld width LDF due to the influence of heat conduction during welding.

As described above, the zinc plating layer removal width LAC is set to be wider than the welding width LDF in the Y direction. Therefore, in the scanning locus of the laser beam LB, the galvanized layers 211 and 221 are removed on both sides of the weld width LDF in the Y direction, but the first plate material 210 and the second plate material 220 are not welded. Occurs. In the following description, the width of this region in the Y direction may be referred to as the bead outer peripheral zinc plating layer removal width LNZn.

On the other hand, as shown in FIG. 6, the output P1 of the laser beam LB during drawing of the first drawing pattern LS1 is set to be lower than the output P2 of the laser beam LB during drawing of the second drawing pattern LS2. ..

In the conventional technique, when lap welding is performed on the work 200 shown in FIG. 3 in a gapless manner by using a laser beam LB, as described above, zinc vapor generated before the iron melts may cause welding defects. There is. On the other hand, according to the present embodiment, the zinc-plated layers 211 and 221 intervening at the interface between the first plate material 210 and the second plate material 220 can be removed, and the generation of welding defects due to the generation of zinc vapor can be suppressed. can. This will be described further.

By setting the output of the laser beam LB1 to the output P1 shown in FIG. 6, the optical axis is deeper than the origin O of the resage pattern, for example, at the drawing position B, due to the laser beam LB1 indicated by bb'. LK1 keyhole 301 is formed, and a molten pool 311 is further formed around the keyhole 301. At this time, the depth LK1 of the keyhole 301 does not reach the interface between the first plate material 210 and the second plate material 220, and similarly, the molten pool 311 also reaches the interface between the first plate material 210 and the second plate material 220. Not reached. That is, the first plate material 210 is not completely melted to the bottom by the laser beam LB1.

On the other hand, the temperature of the interface between the first plate material 210 and the second plate material 220 rises due to the heat input from the laser beam LB1 reaching the inside of the keyhole 301 and the heat generated in the molten pool 311 to reach the above-mentioned boiling point of zinc. Upon reaching this point, the zinc-plated layers 211 and 221 intervening at the interface evaporate. As a result, the galvanized layers 211 and 221 are removed from the interface along the X direction from the origin O over the length LZn.

Further, by setting the output of the laser beam LB2 to the output P2 shown in FIG. 6, the laser beam LB2 whose optical axis is indicated by e-e'is behind the origin O of the resage pattern, for example, at the drawing position E. A keyhole 302 having a depth of LK2 is formed, and a molten pool 312 is further formed around the keyhole 302. At this time, the keyhole 302 penetrates the first plate material 210 and reaches the inside of the second plate material 220. Similarly, the molten pool 312 is also formed from the surface of the first plate material 210 to the inside of the second plate material 220. That is, the vicinity of the interface between the first plate material 210 and the second plate material 220 is melted by the laser beam LB2 after the galvanized layers 211 and 221 are evaporated and removed, and the first plate material 210 and the second plate material 220 are formed. The welded welded portion 320 is formed behind the molten pool 312.

Further, as described above, the zinc plating layer removal width LAC is wider than the weld width LDF in the Y direction, and the zinc plating layers 211 and 221 are removed on both sides of the weld width LDF in the Y direction. , A region where the first plate material 210 and the second plate material 220 are not welded is formed.

By doing so, laser welding is performed on the region where the zinc plating layers 211 and 221 are surely removed, so that the instability of the keyhole 302 and the molten pool 312 generated due to the zinc vapor is reduced. can. Similarly, it is possible to suppress the generation of welding defects such as spatters and craters generated by blowing off the porosity and the molten pool 312 formed inside the work 200 due to the zinc steam.

[Effects, etc.]
As described above, in the laser welding method according to the present embodiment, the laser beam LB is two-dimensionally scanned while advancing the laser beam LB in the X direction (first direction) to irradiate the surface of the work 200. This includes a welding step for welding the work 200.

The work 200 has a structure in which the first plate material 210 having the zinc plating layer 211 formed on the surface and the second plate material 220 having the zinc plating layer 221 formed on the surface are overlapped without a gap. Both the first plate material 210 and the second plate material 220 are steel plates.

In the welding step, the laser beam LB is vibrated in a sine wave shape having a first frequency corresponding to the frequency n along the X direction, and has a second frequency corresponding to the frequency m along the Y direction (second direction). Vibrate in a sine wave shape. As a result, the laser beam LB is scanned so as to draw an ∞-shaped resage pattern on the surface of the work 200.

Further, among the resage patterns, the first drawing pattern LS1 located in front of the origin O of the resage pattern along the welding direction WD (+ side direction in the X direction) is located behind the origin O, and the second drawing pattern LS2 is located behind the origin O. The laser beam LB is scanned so as to have a wider pattern in the Y direction than the above.

The output P of the laser beam LB is controlled so that the output P1 of the laser beam LB drawing the first drawing pattern LS1 is lower than the output P2 of the laser beam LB drawing the second drawing pattern LS2.

Further, while drawing the first drawing pattern LS1, the zinc-plated layers 211 and 221 intervening at the interface between the first plate material 210 and the second plate material 220 are removed. While drawing the second drawing pattern LS2, the first plate material 210 and the second plate material 220 from which the galvanized layers 211 and 221 have been removed are welded to each other.

According to this embodiment, the zinc plating layers 211 and 221 intervening at the interface between the first plate material 210 and the second plate material 220 can be removed, and the generation of welding defects due to the generation of zinc vapor can be suppressed. Further, the shape of the weld bead formed on the work 200 can be made good.

In the method disclosed in Patent Document 4, the laser beam is not scanned in the direction intersecting the welding direction, and the trajectory of the laser beam overlaps in the forward step and the reverse step. Further, the width of the laser beam in the direction intersecting the welding direction is the same in the forward step and the reverse step. Therefore, depending on the spot size and output of the laser beam, it is not possible to secure a sufficient width for removing the zinc plating layer with respect to the welding width in the direction intersecting the welding direction, and welding defects caused by zinc vapor during welding of the work. Was likely to occur. In addition, there is a risk that the shape of the weld bead will collapse.

On the other hand, according to the present embodiment, as described above, the laser beam LB is scanned so that the zinc plating layer removal width LAC is wider than the welding width LDF in the Y direction. Therefore, a region where the zinc plating layer is removed can be sufficiently secured for the welded region, and the generation of welding defects due to the generation of zinc vapor can be suppressed. Further, this makes it possible to improve the shape of the weld bead formed on the work 200.

The laser welding apparatus 100 according to the present embodiment includes a laser oscillator 10 that generates a laser beam LB, a laser head 30 that receives the laser beam LB and irradiates the work 200, and an operation of the laser head 30 and a laser beam LB. It includes at least a controller 50 that controls the output P.

The work 200 has a structure in which the first plate material 210 having the zinc plating layer 211 formed on the surface and the second plate material 220 having the zinc plating layer 221 formed on the surface are overlapped without a gap. Both the first plate material 210 and the second plate material 220 are steel plates.

The laser head 30 has a laser light scanner 40 that scans the laser light LB in each of the X direction (first direction) and the Y direction (second direction) intersecting the X direction.

The controller 50 vibrates the laser beam LB in a sinusoidal shape having a first frequency along the X direction and vibrates in a sinusoidal shape having a second frequency along the Y direction. As a result, the controller 50 drives and controls the laser light scanner 40 so that the laser light LB draws an ∞-shaped resage pattern on the surface of the work 200.

Further, in the controller 50, among the resage patterns, the first drawing pattern LS1 located in front of the origin O of the resage pattern along the X direction, which is the welding direction, is Y more than the second drawing pattern LS2 located behind. The laser light scanner 40 is driven and controlled so as to have a wide pattern with respect to the direction.

The controller 50 controls the output P of the laser beam LB so that the output P1 of the laser beam LB drawing the first drawing pattern LS1 is lower than the output P2 of the laser beam LB drawing the second drawing pattern LS2. do.

According to the laser welding apparatus of the present embodiment, the zinc plating layers 211 and 221 intervening at the interface between the first plate material 210 and the second plate material 220 can be removed, and the generation of welding defects due to the generation of zinc vapor is suppressed. be able to. Further, the shape of the weld bead formed on the work 200 can be made good.

The laser welding device 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 with respect to the surface of the work 200.

By providing the manipulator 60 in this way, the welding direction of the laser beam LB can be changed. Further, laser welding can be easily performed on a work 200 having a complicated shape, for example, a three-dimensional shape.

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.

By providing the optical fiber 20 in this way, it becomes possible to perform laser welding on the work 200 installed at a position away from the laser oscillator 10. This increases the degree of freedom in arranging each part of the laser welding apparatus 100.

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

By configuring the laser light scanner 40 in this way, the laser light LB can be easily scanned two-dimensionally. Further, since a known galvano scanner is used as the laser light scanner 40, it is possible to suppress an increase in the cost of the laser welding apparatus 100.

The laser head 30 further includes a collimation lens 32, and the collimation lens 32 is configured to change the focal position of the laser beam LB along the Z direction intersecting each of the X direction and the Y direction. In other words, the collimation lens 32 is configured to change the focal position of the laser beam LB along the Z direction intersecting the surface of the work 200. That is, the collimation lens 32 also functions as a focal position adjusting mechanism for the laser beam LB in combination with a drive unit (not shown).

By doing so, the focal position of the laser beam LB can be easily changed, and the laser beam LB can be appropriately irradiated according to the shape of the work 200.

In the present embodiment, the laser light LB is moved in the + direction in the X direction by moving the laser head 30 in the X direction, but the laser light is moved in the Y direction by moving the laser head 30. The LB may be advanced in the Y direction. That is, the welding direction may be the Y direction. In this case, it is necessary to change the shape of the Lissajous pattern by setting the frequency n to 2 and the frequency m to 1. By doing so, in the controller 50, among the resage patterns, the first drawing pattern LS1 located in front of the origin O of the resage pattern along the Y direction which is the welding direction is located behind the origin O. 2 The laser light scanner 40 can be driven and controlled so that the pattern is wider in the X direction than the drawing pattern LS2. That is, the laser beam LB can be scanned so that the first drawing pattern LS1 has a wider pattern in the X direction than the second drawing pattern LS2. As a result, the width from which the zinc plating layers 211 and 221 are removed can be made sufficiently wider than the welding width, and the generation of welding defects due to zinc vapor can be suppressed.

Further, the drawing direction of the resage pattern is not particularly limited to the above-mentioned direction. For example, the laser beam LB may be scanned in the direction of the arrow AR3 and the arrow AR4 shown in FIG. 4 from the origin O during one cycle to draw a resage pattern. Specifically, the laser beam LB may be scanned so as to pass from the origin O to the drawing position C → B → A → O → F → E → D → O during one cycle.

<Modification 1>
FIG. 8 shows the relationship between the drawing position of the laser beam and the output according to the present modification, and FIG. 9 schematically shows the state change of the work along the welding direction at the time of irradiation with the laser beam. FIG. 10 shows the relationship between the output of the laser beam and the depth of the keyhole. For convenience of explanation, in FIGS. 8 to 10 and the drawings shown thereafter, the same parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted.

This modification differs from the configuration shown in the first embodiment in the following points. That is, the output P of the laser beam LB is controlled to be continuously increased at the transition of the LS2 from the first drawing pattern LS1 to the second drawing pattern. Further, at the time of transition from the second drawing pattern LS2 to the first drawing pattern LS1, the output P of the laser beam LB is controlled to be continuously lowered.

Specifically, as shown by the broken line in FIG. 8, when the drawing position of the laser beam LB moves from the origin O to D, from the time when the laser beam LB passes through the origin O until the period t1 elapses. The output P of the laser beam LB is continuously increased from P1 to P2. The control curve S1 of the output P in this case may be linear or curved. Further, when the drawing position of the laser beam LB moves from the origin O to A, the output P of the laser beam LB is continuously transmitted from P2 to P1 from the time when the laser beam LB passes through the origin O until the period t2 elapses. It is decreasing. The control curve S2 of the output P in this case may be linear or curved.

By doing so, it is possible to suppress the formation of porosity inside the work 200. In addition, the molten pool 312 can be stabilized. This will be described further.

As shown in FIG. 9, when the drawing position of the laser beam LB moves from the position O'' behind the origin O to the position O'in front of the origin O along the X direction, that is, the second drawing in the resage pattern. Consider the transition time from the pattern LS2 to the first drawing pattern LS1. In this case, when the output P of the laser beam LB is stepped down from P2 to P1, the shape of the keyhole 302 having a depth of LK2 suddenly changes to the keyhole 301 having a depth of LK1 (LK1 <LK2). do. As a result, the portion from the bottom of the keyhole 302 to the length LK12 shown in FIG. 9 is rapidly closed due to the surface tension of the molten metal. It does not matter much if the keyholes 302 are closed sequentially from the bottom to the top, but in many cases, the keyholes 302 are closed at one or more locations from the bottom to the length LK12 at almost the same timing. It often ends up. When such a situation occurs, a cavity may remain below or above the closed portion, and porosity may be formed inside the work 200.

On the other hand, according to this modification, as shown in FIG. 8, since the output P of the laser beam LB is continuously reduced from P2 to P1 according to the control curve S2, the keyhole 302 is changed to the keyhole 301. The shape change of the sword becomes gradual, and it is possible to prevent the cavity from remaining on the way. This can prevent the formation of porosity inside the work 200.

Further, consider the case where the drawing position of the laser beam LB moves from the above-mentioned position O'to the position O'", that is, the transition time from the first drawing pattern LS1 to the second drawing pattern LS1 in the resage pattern. In this case, the output P of the laser beam LB increases stepwise from P1 to P2, and the shape of the keyhole 301 having a depth of LK1 suddenly changes to the keyhole 302 having a depth of LK2. As a result, an excessive impact may be applied to the molten pool 312. If the molten pool 312 becomes unstable and undulates, it will be reflected in the shape of the weld bead, and there is a possibility that a weld bead having a good shape cannot be formed.

On the other hand, according to this modification, as shown in FIG. 8, since the output P of the laser beam LB is continuously increased from P1 to P2 according to the control curve S1, the keyhole 301 is changed to the keyhole 302. The shape change becomes gradual, and it is possible to suppress the instability of the molten pool 312. As a result, deterioration of the shape of the weld bead can be suppressed, and a weld bead having a good shape can be obtained.

By controlling the output P as shown in the control curves S1 and S2, it becomes easy to stably reach the target value of the output P. Further, the control of the output P of the laser beam LB is performed by the controller 50.

Further, as shown in FIG. 10, in order to form a keyhole in the work 200, it is necessary to set the output P of the laser beam LB to a predetermined value or more. In the region where the output P is smaller than the predetermined value (heat conduction welding region Rc), the work 200 is softened or melted by the heat input by the laser beam LB, but no keyhole is formed. When the output P is increased from this region, the keyhole welding region Rk is reached via the transition region Rt. In this region, a keyhole is formed in the work 200, and the depth of the keyhole becomes deeper as the output P increases. Both the outputs P1 and P2 described above are included in the keyhole welding region Rk.

<Modification 2>
11A shows the first scanning pattern of the laser beam according to the present modification, FIG. 11B shows the second scanning pattern, and FIG. 11C shows the third scanning pattern of the laser beam.

In actual laser welding, the above-mentioned parameters a1, b1, a2, b2, m shown in the formulas (1) to (4) are appropriately set according to the material of the work 200, the joint shape, the required bead shape width, and the like. Can be changed. Therefore, the scanning pattern of the laser beam LB is not particularly limited to the pattern shown in FIG.

For example, as shown in FIG. 11A, in the drawing pattern LS1, the ratio of the parameters a1 and b1 is 2: 1, and in the drawing pattern LS2, the ratio of the parameters a2 and b2 is 2: 1, and a2 and b2 are set respectively. It may be 1/2 of a1 and b2. Further, as shown in FIG. 11B, the parameters a2 and b2 may be changed from the pattern shown in FIG. 4 so that a2 = 1 and b2 = 0.5 only in the drawing pattern LS2. Further, as shown in FIG. 11C, in the drawing pattern LS1, the ratio of the parameters a1 and b1 may be 2: 1 and in the drawing pattern LS2, the ratio of the parameters a2 and b2 may be 4: 1.

Needless to say, the values of the parameters a1, b1, a2, and b2 shown in the equations (1) to (4) are not particularly limited to the examples shown in FIGS. 4 and 11A to 11C.

As described above, the ratio of the frequency n of the first mirror 41a to the frequency m of the second mirror 42a, in other words, the vibration frequency in the X direction of the laser beam LB, which is the vibration frequency in the first frequency and the vibration frequency in the Y direction. The ratio n: m of the second frequency is 1: 2. This makes it possible to make the first drawing pattern LS1 located in front of the origin O in the Y direction intersecting the welding direction wider than the second drawing pattern LS2 located behind the origin O. On the other hand, when the welding direction is the Y direction, the ratio n: m of the first frequency and the second frequency is 2: 1. This makes it possible to make the first drawing pattern LS1 located in front of the origin O in the X direction intersecting the welding direction wider than the second drawing pattern LS2 located behind the origin O. Further, as long as this frequency ratio is maintained, the drive frequencies of the first mirror 41a and the second mirror 42a may be changed according to the shape of the work 200 or the required bead shape.

(Embodiment 2)
FIG. 12 shows a scanning locus of a laser beam along a welding line according to the present embodiment. FIG. 13A shows the relationship between the drawing position of the laser beam at the start of welding and the output, and FIG. 13B shows the relationship between the drawing position of the laser beam at the end of welding and the output.

As shown in FIGS. 12 and 13A, in the present embodiment, in a predetermined period (first period) after the start of laser welding, the output of the laser beam LB during drawing of the first drawing pattern LS1 is set to P1. It differs from the configuration shown in the first embodiment in that the output of the laser beam LB when drawing the second drawing pattern LS2 is set to zero. In the first period, the distance that the rear end of the resage pattern, that is, the portion corresponding to the drawing position E shown in FIG. 4 moves along the welding direction WD, corresponds to the length L2 shown in FIG. Further, the length L2 corresponds to about twice the length of the second drawing pattern LS2 in the X direction.

Further, as shown in FIGS. 12 and 13B, in the present embodiment, the output of the laser beam LB during drawing of the second drawing pattern LS2 is P2 in a predetermined period (second period) before the end of laser welding. On the other hand, it differs from the configuration shown in the first embodiment in that the output of the laser beam LB when drawing the first drawing pattern LS1 is set to zero. In the second period, the distance that the front end of the resage pattern, that is, the portion corresponding to the drawing position B shown in FIG. 4 moves along the welding direction WD corresponds to the length L1 shown in FIG. Further, the length L1 substantially corresponds to the sum of the length of the first drawing pattern LS1 in the X direction and the length of the second drawing pattern LS2 in the Y direction.

According to the present embodiment, the work 200 is welded by irradiating the region where the zinc plating layers 211 and 221 are surely removed with the laser beam LB at the output P2 to cause welding defects caused by zinc vapor. The occurrence can be reliably suppressed. In addition, the shape of the weld bead can be made good. This will be described further.

When the origin O of the resage pattern is aligned with the welding start point and the welding of the work 200 is started, the first drawing pattern LS1 is drawn in front of the welding start point along the welding direction WD, and the second drawing pattern LS1 is drawn behind the welding start point. The drawing pattern LS2 is drawn. At this time, as shown in FIG. 6, when the output P of the laser beam LB is controlled, the laser beam LB of the output P2 is irradiated behind the welding start point in a state where the zinc plating layers 211 and 221 are not removed. Will be. As described above, when such a situation occurs, zinc vapor is generated in the portion where the zinc plating layer has not been removed, and welding defects are further generated.

In order to avoid such a problem, in the first period after the start of laser welding, the output of the laser beam LB when drawing the second drawing pattern LS2 is set to zero in the present embodiment. By doing so, it is possible to prevent the high-power (= P2) laser beam LB from being irradiated to the region where the zinc-plated layers 211 and 221 have not been removed yet, and welding defects caused by the generation of zinc vapor are generated. It surely suppresses the occurrence.

Further, in order to suppress the occurrence of welding defects, it is necessary that at least the zinc plating layers 211 and 221 are removed from the welding start point to the welding end point. However, for example, if the galvanized layers 211 and 221 are removed more than necessary beyond the welding end point, the corrosion resistance of the first plate material 210 and the second plate material 220, which are steel plates, may decrease.

In order to avoid such a problem, in the second period before the end of laser welding, the output of the laser beam LB when drawing the first drawing pattern LS1 is set to zero in the present embodiment. By doing so, it is possible to shorten the length LZN from which the galvanized layers 211 and 221 are removed while setting the length LW of the welded region to a desired value. As a result, the zinc plating layers 211 and 221 are removed more than necessary, and the deterioration of the corrosion resistance of the first plate material 210 and the second plate material 220, which are steel plates, can be suppressed.

Further, from the viewpoint of suppressing welding defects and suppressing deterioration of corrosion resistance in the first plate material 210 and the second plate material 220, after the welding of the work 200 is completed, the zinc plating layers 211 and 221 along the welding direction WD are formed. Needless to say, it is preferable that the length LZN of the removed portion is the same as or longer than the length LW of the welded portion of the work 200 along the welding direction WD. Therefore, in the figure, the laser output is zero in both the LS2S portion shown by the dotted line in the L2 period and the LS1E portion shown by the dotted line in the L1 period.

<Modification 3>
14A to 14C show the first to third scanning patterns of the laser beam according to this modification. In FIGS. 14A to 14C, the arrows drawn in the scanning pattern indicate the drawing direction of the laser beam LB.

The scanning pattern of the laser beam LB of the present disclosure is not limited to the resage pattern shown in the first embodiment and the second modification. For example, as shown in FIG. 14A, it may be a composite pattern of two circular patterns having asymmetrical shapes and arranged so as to be in contact with each other at the origin O and sandwiching the Y axis. Further, as shown in FIG. 14B, it may be a composite pattern of two elliptical patterns having asymmetrical shapes and arranged so as to be in contact with each other at the origin O and sandwiching the Y axis. In the example shown in FIG. 14B, in each of the two elliptical patterns, the long axis is in the Y direction and the short axis is in the X direction, but the long axis may be in the X direction and the short axis may be in the Y direction. As shown in FIG. 14C, it may be a composite pattern of two rhombus patterns having asymmetrical shapes and arranged so as to be in contact with each other at the origin O and sandwiching the Y axis. When the welding direction WD is parallel to the Y direction, each scanning pattern shown in FIGS. 14A to 14C may be a composite pattern of two annular patterns arranged asymmetrically with respect to the Y axis. Also, the size of each of the two annular patterns can be changed as appropriate.

That is, the scanning pattern of the laser beam LB in the present specification may be a pattern in which two annular patterns are in contact with each other at one point and are continuous, and is not limited to the examples shown in FIGS. 14A to 14C and the modifications thereof. These patterns can be obtained by driving the first mirror 41a and the second mirror 42a according to a predetermined drive pattern, respectively.

By configuring the laser welding method and the laser welding apparatus 100 in this way, it is possible to obtain the same effect as the configurations shown in the first and second embodiments and the first and second modifications.

The "predetermined pattern", which is the scanning pattern of the laser beam LB, is a pattern in which two annular patterns having asymmetrical shapes are at one point, and in this case, they are in contact with each other at the origin O and are continuous. Needless to say, the "predetermined pattern" includes the resage pattern disclosed in the present specification.

(Embodiment 3)
FIG. 15 shows an outline of the scanning locus of the laser beam according to the third embodiment, and FIGS. 16A to 16G show the first to seventh spot patterns, respectively.

In the first embodiment, the so-called line welding, in which the work 200 is laser-welded while advancing the laser beam LB to the + side in the X direction, has been described as an example, but the laser welding method of the present disclosure can also be used for spot welding. Applicable.

For example, consider a case where the laser beam LB is advanced along a circular spot pattern SP indicated by a two-dot chain line, as shown in FIG. The scanning pattern SP1 of the laser beam LB shown in FIG. 15 has a shape similar to the scanning pattern shown in FIG.

Also in this case, in order to remove the zinc-plated layers 211 and 221 of the work 200 at high speed and surely, the scanning pattern SP1 of the laser beam LB has two annular patterns having asymmetrical shapes in contact with each other at the origin O and are continuous. It is preferable to use a pattern, and it is preferable to use an ∞-shaped laserge pattern. For convenience of explanation, the scanning pattern SP1 of the laser beam LB is shown as a Lissajous pattern, but the actual waveform of the scanning pattern SP1 changes according to the traveling speed of the laser beam LB. For example, although not shown, the first drawing pattern LS1 and the second drawing pattern LS2 are separated from each other along the welding direction WD, in this case, in the clockwise direction along the spot pattern SP, and the progress of the laser beam LB The separation distance changes according to the speed. Further, both the first drawing pattern LS1 and the second drawing pattern LS2 have a deformed shape extending along the circumferential direction of the spot pattern SP.

Also in this embodiment, the first drawing pattern LS1 located in front of the origin O of the scanning pattern SP1 along the welding direction WD is wider in the Y direction than the second drawing pattern LS2 located behind the origin O. The laser beam LB is scanned so as to be.

By doing so, the zinc-plated layers 211 and 221 intervening at the interface between the first plate material 210 and the second plate material 220 are removed while drawing the first drawing pattern LS1. While drawing the second drawing pattern LS2, the first plate material 210 and the second plate material 220 from which the galvanized layers 211 and 221 have been removed are spot welded to each other.

In order to make the irradiation width of the laser beam LB the same on the inside and outside of the spot pattern SP in the radial direction with the spot pattern SP sandwiched between them, the scanning pattern SP1 is drawn as the first drawing pattern while passing through the origin O. It is desirable to scan the laser beam LB so that the center line (not shown) divided into the LS1 and the second drawing pattern LS2 is always orthogonal to the tangential direction at the origin O in the spot pattern SP.

Further, when the configurations shown in the first and second embodiments, the first to third embodiments, and the present embodiment are combined, it can be said that the laser welding method of the present disclosure has the following configurations. That is, in the laser welding method of the present disclosure, the welding step of welding the work 200 by scanning the laser beam LB two-dimensionally and irradiating the surface of the work 200 while advancing the laser beam LB in the welding direction WD. Is equipped with.

The work 200 has a structure in which the first plate material 210 having the zinc plating layer 211 formed on the surface and the second plate material 220 having the zinc plating layer 221 formed on the surface are overlapped without a gap. Both the first plate material 210 and the second plate material 220 are steel plates.

In the welding step, the laser beam LB is scanned so as to draw a predetermined pattern on the surface of the work 200. The predetermined pattern is a continuous pattern in which two annular patterns having asymmetrical shapes are in contact with each other at the origin O.

Further, among the predetermined patterns, the first drawing pattern LS1 located in front of the origin O of the predetermined pattern along the welding direction WD has a welding direction WD more than the second drawing pattern LS2 located behind the origin O. The laser beam LB is scanned so as to have a wide pattern in the intersecting direction.

The output P of the laser beam LB is controlled so that the output P1 of the laser beam LB drawing the first drawing pattern LS1 is lower than the output P2 of the laser beam LB drawing the second drawing pattern LS2.

Further, while drawing the first drawing pattern LS1, the zinc-plated layers 211 and 221 intervening at the interface between the first plate material 210 and the second plate material 220 are removed. While drawing the second drawing pattern LS2, the first plate material 210 and the second plate material 220 from which the galvanized layers 211 and 221 have been removed are welded to each other. In this case, the case where the first plate material 210 and the second plate material 220 are spot welded to each other is also included.

By doing so, even if there is no gap between the first plate material 210 and the second plate material 220, the zinc plating layers 211 and 221 intervening at the interface between the first plate material 210 and the second plate material 220 can be removed. At the same time, it is possible to suppress the generation of welding defects due to the generation of zinc vapor. Further, the shape of the weld bead formed on the work 200 can be made good.

The laser welding apparatus 100 of the present disclosure includes a laser oscillator 10 that generates a laser beam LB, a laser head 30 that receives the laser beam LB and irradiates the work 200, an operation of the laser head 30, and an output P of the laser beam LB. At least includes a controller 50 for controlling the above.

The work 200 has a structure in which the first plate material 210 having the zinc plating layer 211 formed on the surface and the second plate material 220 having the zinc plating layer 221 formed on the surface are overlapped without a gap. Both the first plate material 210 and the second plate material 220 are steel plates.

The laser head 30 has a laser light scanner 40 that scans the laser light LB in each of the X direction (first direction) and the Y direction (second direction) intersecting the X direction.

The laser light scanner 40 is driven and controlled so that the laser light LB draws a predetermined pattern on the surface of the work 200.

Further, in the controller 50, among the predetermined patterns, the first drawing pattern LS1 located in front of the origin O of the resage pattern along the welding direction WD is in the welding direction WD with respect to the second drawing pattern LS2 located behind. The laser light scanner 40 is driven and controlled so as to have a wide pattern in the direction intersecting with.

The controller 50 controls the output P of the laser beam LB so that the output P1 of the laser beam LB drawing the first drawing pattern LS1 is lower than the output P2 of the laser beam LB drawing the second drawing pattern LS2. do.

By configuring the laser welding apparatus 100 in this way, even if there is no gap between the first plate material 210 and the second plate material 220, the zinc plating layer interposed at the interface between the first plate material 210 and the second plate material 220 211,221 can be removed, and the generation of welding defects due to the generation of zinc vapor can be suppressed. Further, the shape of the weld bead formed on the work 200 can be made good. In this case, the case where the first plate material 210 and the second plate material 220 are spot welded to each other is also included.

In addition, when spot welding the first plate material 210 and the second plate material 220 to each other, the spot pattern SP does not necessarily have to be a circular pattern shown in FIG. It suffices if the first plate material 210 and the second plate material 220 are spot welded.

From this point of view, the spot pattern SP can take various shapes. For example, as shown in FIG. 16A, the spot pattern SP may be an open circle shape in which a part is open, or as shown in FIG. 16F, the spot pattern SP may be a waveform. Further, as shown in FIG. 16G, the spot pattern SP may be substantially U-shaped. As shown in FIGS. 16A, 16C to 16E, and 16G, when a part of the spot pattern SP is open, air, oil, or the like between the first plate material 210 and the second plate material 220 escapes. Since the mouth is formed, the shape of the weld bead can be improved.

(Other embodiments)
It is also possible to appropriately combine the components shown in the first to third embodiments and the first to third embodiments to form a new embodiment. For example, in drawing each scanning pattern shown in the second embodiment, it is possible to control the output P of the laser beam LB as shown in the first modification.

Further, in the second and third embodiments and the first to third modifications, for example, the laser beam LB passes from the origin O to the drawing position C → B → A → O → F → E → D → O during one cycle. May be scanned. Needless to say, the timing for changing the output P of the laser beam LB is changed according to the change in the order of the drawing positions.

In the example shown in FIG. 1, the condenser lens 34 is arranged in the front stage of the laser light scanner 40, but is in the rear stage of the laser light scanner 40, that is, the light emission port of the laser light scanner 40 and the laser head 30. It may be arranged between.

Further, by vibrating the laser beam LB in a chordal wave shape having a first frequency along the X direction and vibrating in a chordal wave shape having a second frequency along the Y direction, the scanning pattern of the laser beam LB becomes a Lissajous pattern. It may be set to. In this case, it goes without saying that the amplitudes a and b of the first mirror 41a and the second mirror 42a, the frequencies n and m of the first mirror 41a and the second mirror 42a, and the phase φ are appropriately changed.

Further, considering the configurations shown in the third modification and the third embodiment, when the scanning pattern of the laser beam LB is to be an ∞-shaped resage pattern, the laser beam LB is scanned as shown below. To. That is, the laser beam LB is vibrated in a sine and cosine wave shape having a first frequency along the welding direction WD, and also in a sine and cosine wave shape having a second frequency along the direction intersecting the welding direction WD. ..

Further, in the specification of the present application, the case where the work 200 shown in FIG. 3 is laser-welded has been described as an example, but the present invention is not particularly limited to this. For example, even if the work 200 is two base materials each including a plate-shaped portion and the plate-shaped portions are overlapped with each other and a zinc plating layer is formed on the surface of at least the plate-shaped portion. good. The base material in this case may be iron, mild steel, or high-strength steel. All of these melting points are higher than the boiling point of zinc. Further, a zinc alloy plating layer containing zinc and aluminum may be formed on the surfaces of the two base materials. That is, a plating layer containing zinc as a main component may be formed on the surfaces of the two base materials. Here, the "plating layer containing zinc as a main component" means a plating layer containing 60% or more of zinc. Further, a coating layer made of a material other than zinc may be formed on the surfaces of the two base materials, respectively. In this case, the materials of the coating layer and the base material are set so that the boiling points of the materials constituting the coating layer are lower than the melting points of the materials constituting the base material.

When this work 200 is laser welded, the coating layer between the plate-shaped portions is removed while drawing the first drawing pattern LS1. While drawing the second drawing pattern LS2, the two plate-shaped portions from which the covering layer has been removed are welded to each other.

When the work 200 having such a structure is laser welded, by applying the laser welding method and the laser welding apparatus of the present disclosure, welding caused by steam generated by evaporation of the coating layer such as the zinc plating layer 211,221 is performed. Needless to say, the occurrence of defects can be suppressed and the shape of the weld bead can be improved.

Since the laser welding method of the present disclosure can suppress the generation of welding defects due to the vapor generated by evaporation of the coating layer, lap welding of two members having a coating layer such as a zinc plating layer formed on the surface is performed. Useful on.

10 Laser oscillator 20 Optical fiber 30 Laser head 31 Housing 32 Collimation lens 33 Reflective mirror 34 Condensing lens 40 Laser optical scanner 41 1st galvano mirror 41a 1st mirror 41b 1st rotating shaft 41c 1st drive unit 42 2nd galvano mirror 42a 2nd mirror 42b 2nd rotating shaft 42c 2nd drive unit 50 Controller 60 Manipulator 200 Work 210 1st plate material (base material)
211 Galvanized layer (coating layer)
220 Second plate material (base material)
221 Galvanized layer (coating layer)
301, 302 Keyholes 311, 312 Welded pond 320 Welded part

Claims (16)

1. A welding step for welding the work is provided by scanning the laser light two-dimensionally and irradiating the surface of the work while advancing the laser light in the welding direction.
   The work has a structure in which the plate-shaped portions are overlapped with each other in two base materials including the plate-shaped portions, and a coating layer is formed at least on the surface of the plate-shaped portions, and the coating layer is formed. The boiling point of is lower than the melting point of the base metal,
   In the welding step,
   As if drawing a predetermined pattern on the surface of the work
   Moreover, among the predetermined patterns, the first drawing pattern located in front of the origin of the predetermined pattern along the welding direction intersects the welding direction more than the second drawing pattern located behind the origin. The laser beam is scanned so as to have a wide pattern with respect to the direction.
   The output of the laser beam is controlled so that the output of the laser beam during drawing of the first drawing pattern is lower than the output of the laser beam during drawing of the second drawing pattern.
   The predetermined pattern is a laser welding method characterized in that two annular patterns having asymmetrical shapes are in contact with each other at the origin and are continuous patterns.
2. In the laser welding method according to claim 1,
   The predetermined pattern is an ∞-shaped resage pattern extending in the welding direction.
   In the welding step, the laser beam is vibrated in a sinusoidal shape having a first frequency along the welding direction and in a sinusoidal shape having a second frequency along the direction intersecting the welding direction. A laser welding method comprising scanning the laser beam so as to draw the resage pattern on the surface of the work.
3. In the laser welding method according to claim 2,
   A laser welding method characterized in that the ratio of the first frequency to the second frequency is 1: 2.
4. In the laser welding method according to any one of claims 1 to 3,
   At the time of transition from the first drawing pattern to the second drawing pattern, the output of the laser beam is controlled to be continuously increased.
   A laser welding method characterized by controlling the output of the laser beam to be continuously reduced at the time of transition from the second drawing pattern to the first drawing pattern.
5. In the laser welding method according to any one of claims 1 to 4.
   While drawing the first drawing pattern, the covering layer between the plate-shaped portions is removed.
   A laser welding method comprising welding two plate-shaped portions from which the coating layer has been removed while drawing the second drawing pattern.
6. In the laser welding method according to any one of claims 1 to 5,
   In the first period after the start of welding of the work, the output of the laser beam when drawing the second drawing pattern is set to zero at a predetermined drawing length.
   A laser welding method characterized in that, in the second period before the completion of welding of the work, the output of the laser beam when drawing the first drawing pattern is set to zero at a predetermined drawing length.
7. In the laser welding method according to claim 6,
   The predetermined drawing length at which the output of the laser beam is set to zero during the first period is about twice the length for one cycle of the second drawing pattern, while the laser is used during the second period. The predetermined drawing length with the light output set to zero is characterized in that it is approximately the same as the sum of the length of one cycle of the first drawing pattern and the length of one cycle of the second drawing pattern. Laser welding method.
8. In the laser welding method according to any one of claims 1 to 7.
   A laser welding method characterized in that the work is spot-welded by advancing the laser beam in the welding direction.
9. The laser welding method according to any one of claims 1 to 8.
   A laser welding method characterized in that the coating layer is a plating layer containing zinc as a main component.
10. A laser oscillator that generates laser light and
    A laser head that receives the laser beam and irradiates it toward the work,
    At least a controller for controlling the operation of the laser head and the output of the laser beam is provided.
    The laser head has a laser beam scanner that scans the laser beam in each of a first direction and a second direction intersecting the first direction.
    The work has a structure in which the plate-shaped portions are overlapped with each other in two base materials including the plate-shaped portions, and a coating layer is formed at least on the surface of the plate-shaped portions, and the coating layer is formed. When the boiling point of is lower than the melting point of the base metal,
    In the controller, the first drawing pattern located in front of the origin of the predetermined pattern along the welding direction in the predetermined pattern so that the laser beam draws a predetermined pattern on the surface of the work. The laser light scanner is driven and controlled so that the pattern is wider in the direction intersecting the welding direction than the second drawing pattern located behind the origin.
    Further, the controller controls the output of the laser beam so that the output of the laser beam during drawing the first drawing pattern is lower than the output of the laser beam during drawing the second drawing pattern. ,
    The predetermined pattern is a laser welding apparatus characterized in that two annular patterns having asymmetrical shapes are in contact with each other at the origin and are continuous patterns.
11. In the laser welding apparatus according to claim 10,
    The predetermined pattern is an ∞-shaped resage pattern extending in the welding direction.
    The controller vibrates the laser beam in a sinusoidal shape having a first frequency along the welding direction and vibrates in a sinusoidal shape having a second frequency along the direction intersecting the welding direction. A laser welding apparatus characterized in that the laser light scanner is driven and controlled so as to draw the resage pattern on the surface of the work.
12. In the laser welding apparatus according to claim 11,
    A laser welding apparatus characterized in that the ratio of the first frequency to the second frequency is 1: 2.
13. The laser welding apparatus according to any one of claims 10 to 12.
    Further equipped with a manipulator to which the laser head is attached
    The controller controls the operation of the manipulator, and the controller controls the operation of the manipulator.
    The manipulator is a laser welding apparatus characterized by moving the laser head in a predetermined direction with respect to the surface of the work.
14. In the laser welding apparatus according to any one of claims 10 to 13.
    The laser oscillator and the laser head are connected by an optical fiber.
    A laser welding apparatus characterized in that the laser light is transmitted from the laser oscillator to the laser head through the optical fiber.
15. The laser welding apparatus according to any one of claims 10 to 14.
    The laser light scanner is composed of a first galvano mirror that scans the laser light in the first direction and a second galvano mirror that scans the laser light in a second direction that intersects the first direction. Laser welding equipment characterized by being
16. The laser welding apparatus according to any one of claims 10 to 15.
    The laser head further has a focal position adjusting mechanism.
    The laser welding apparatus is characterized in that the focal position adjusting mechanism is configured to change the focal position of the laser beam along a direction intersecting the surface of the work.

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