Laser welding method

Abstract

To provide a laser welding method that prevents oxidation of a weld area in wobbling welding.SOLUTION: When a laser welding apparatus 3 which emits a laser beam from an irradiation head 2 attached to a robot arm 31 is used to perform wobbling welding on a metal material 5 by moving the irradiation head 2 while finely moving the laser beam, in such a state that a tubular enclosed space 1 connecting a first opening 111 and a second opening 121 on the same straight line is attached with the first opening 111 in close contact with the irradiation head 2, a laser welding method performs wobbling welding with the laser beam 4 emitted from the first opening 111 through the second opening 121 while supplying shield gas 6 into the enclosed space 1.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a laser welding method using wobbling welding. [Background technology]

[0002] Wobbling welding is a laser welding method that can create a weld bead that is beautiful in appearance and has excellent strength by moving the irradiation position while moving the laser light finely, for example, drawing an ellipse. The laser light is irradiated from an irradiation head equipped with a driving means (for example, an optical system using a galvanometer mirror) that moves the irradiation position finely. The irradiation head is attached to a robot arm, and moves the irradiation position of the laser light in accordance with the robot arm. In this way, the irradiation position can be moved while moving the laser light finely (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-123008 A Summary of the Invention [Problem to be solved by the invention]

[0004] Wobbling welding is used to weld a wide variety of metal materials because it can produce weld beads that are beautiful to look at and have excellent strength. Compared to conventional methods, weld beads produced by wobbling welding have a larger width and depth of penetration, which results in a beautiful appearance and excellent strength. However, when the width and depth of the penetration are large, the amount of heat generated at the welded area increases, which can lead to oxidation of the welded area depending on the material, resulting in a decrease in welding quality. Therefore, we investigated a laser welding method that prevents oxidation of the welded area in wobbling welding. [Means for solving the problem]

[0005] As a result of these studies, we developed a laser welding method in which a laser welding device irradiates laser light from an irradiation head attached to a robot arm, and the irradiation head is moved while the laser light is moved in small movements to wobble weld metal materials. In this method, a cylindrical closed space connecting a first opening and a second opening which are on the same straight line is wobble welded by the laser light emitted from the first opening through the second opening while supplying shielding gas into the inside of the closed space, with the first opening attached in close contact with the irradiation head.

[0006] The cylindrical closed space connecting the first opening and the second opening on the same line is attached by closely contacting the first opening to the irradiation head while surrounding the irradiation port of the irradiation head. The shielding gas supplied to the inside of the closed space is pushed by the rising internal pressure and discharged from the second opening to the periphery of the irradiation position of the laser light. The shielding gas discharged from the second opening temporarily stays around the welding part irradiated with the laser light, and then diffuses to the periphery. The shielding gas of the present invention is nitrogen gas or argon gas that suppresses oxidation of metal materials.

[0007] The outer shape of the closed space is not important, and the position where the shielding gas is supplied is also free. However, it is preferable that the closed space is frustum-shaped narrowing from the first opening to the second opening, and the shielding gas is supplied from a position close to the first opening. The shielding gas accumulates near the large first opening in the internal space, and in addition to the increase in internal pressure, more of it is released from the second opening located relatively lower than the first opening due to its own weight, and it temporarily stays in a wide area surrounding the welding area, and the welding area can be widely isolated from the outside air. In addition, since the first opening that is in close contact with the irradiation head is large in the closed space, it is easy to increase the number of attachment points for the irradiation head. Effect of the Invention

[0008] The laser welding method of the present invention prevents oxidation of the welded area in wobbling welding. This is the effect of discharging and temporarily retaining the shielding gas supplied inside the closed space attached to the irradiation head along the laser light emitted through the second opening at the welding position. The closed space, which is frustum-shaped narrowing from the first opening toward the second opening and to which the shielding gas is supplied from a position close to the first opening, allows more shielding gas to be discharged from the second opening, isolating the welded area from the outside air over a wide area, and better preventing oxidation of the welded area. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view showing an example of a laser welding device used in the present invention. [Diagram 2] FIG. 2 is a front view showing the irradiation head of the present example with the closed space portion attached. [Diagram 3] FIG. 2 is a vertical cross-sectional view of the irradiation head of the present embodiment in a state where wobbling welding is performed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, the laser welding method of the present invention is used when performing wobble welding using a welding device 3 having an irradiation head 2 attached to a robot arm 31. The irradiation head 2 moves the irradiation position while finely moving the laser light in accordance with the robot arm 31, and joins, for example, two metal materials 5, which are plate materials placed on a workbench 32, by wobble welding. A closed space portion 1, which is important for the laser welding method of the present invention, is attached to the irradiation head 2.

[0011] As shown in Figs. 2 and 3, the closed space 1 in this example is a cylinder consisting of an upper mounting outer cylinder 11 and a lower frustum-shaped main body 12. The first opening 111 is a circular upper end opening of the mounting outer cylinder 11. The second opening 121 is a circular lower end opening of the frustum-shaped main body 12. The mounting outer cylinder 11 is a connecting member that stably and firmly attaches the frustum-shaped main body 12 to the irradiation head 2. If the closed space 1 is configured so that the frustum-shaped main body 12 can be directly attached to the irradiation head 2, the mounting outer cylinder 11 may not be necessary.

[0012] The mounting outer cylinder 11 in this example is a metallic cylindrical member extending upward from the upper end opening of the frustum-shaped main body 12, and is provided with an annular support step 112 that protrudes radially outward at the boundary with the frustum-shaped main body 12. The mounting outer cylinder 11 in this example is a member that is integral with the frustum-shaped main body 12, but it may also be a separate member from the frustum-shaped main body 12, and connected and integrated with the frustum-shaped main body 12 by conventionally known connecting means (for example, bolts and nuts).

[0013] The mounting outer cylinder 11 is fitted onto the mounting inner cylinder 22 that protrudes downward from the lower surface of the irradiation head 2 with the irradiation port 21 as the center, and an annular support ring 23 suspended from the lower surface of the irradiation head 2 by a suspension rod 231 is engaged from below with the support step 112, thereby being attached to the irradiation head 2. A seal (not shown) is provided in the gap between the mounting outer cylinder 11 and the mounting inner cylinder 22 to increase the airtightness at the upper end side of the closed space portion 1 and to prevent the shielding gas 6 from leaking out from the first opening 111.

[0014] The frustum-shaped main body 12 in this example is an inverted truncated cone member made of metal that tapers downward and has a second opening 121 at its lower end, and has two first supply ports 122 at point-symmetric positions at a height adjacent to the boundary with the mounting outer cylinder 11, and one second supply port 123 at a height close to the second opening 121. The first supply port 122 and the second supply port 123 are connected to gas supply hoses (not shown) extending from a gas supply means (not shown). The shielding gas 6 is supplied into the closed space 1 from the first supply port 122 and the second supply port 123.

[0015] In the closed space portion 1, the first opening 111 and the second opening 121, which are circular, are aligned on the same line, and the first opening 111 is attached to the irradiation head 2 with the center of the first opening 111 coinciding with the irradiation port 21. The second opening 121 is formed to a size that can accommodate the range in which the laser light 4 is moved for wobbling welding (see the thick solid line and the imaginary line in FIG. 3). As a result, the laser light 4 irradiated from the irradiation port 21 of the irradiation head 2 is radiated to the welding area 51 from the first opening 111 through the second opening 112, even if it is moved for wobbling welding.

[0016] 3, the welding device 3 of this example performs wobble welding on, for example, the side edges of two butted metal materials 5 as the welded portion 51 by using a finely moved laser light 4 while discharging the shielding gas 6 supplied from the first supply port 122 and the second supply port 123 into the closed space portion 1 from the second opening 121. The closed space portion 1 has a first opening 111 at the upper end blocked by the irradiation head 2, and only a second opening 121 at the lower end open. In addition, the closed space portion 1 receives more shielding gas 6 from the two first supply ports 122 in the large diameter portion of the frustum-shaped main body 12 than from the one second supply port 123 in the small diameter portion of the frustum-shaped main body 12.

[0017] The laser beam 4 may be irradiated with a slight inclination depending on the posture of the robot arm 31, but is generally irradiated downward. As a result, the closed space portion 1 generally faces the second opening 121 downward, increasing the internal pressure of the closed space portion 1 and forcing the shielding gas 6 toward the only opened second opening 121 and releasing it at a sufficient flow rate. The laser beam 4 for wobbling welding moves finely within the range of the second opening 121, but the shielding gas 6 released at a sufficient flow rate blocks a wide range including the welding area 51, thereby realizing wobbling welding that prevents oxidation of the welding area 51. [Explanation of symbols]

[0018] 1. Closed space 11 Mounting cylinder 111 First Opening 112 Support step 12 Frustum-shaped body 121 Second Opening 122 1st supply port 123 2nd supply port 2 Irradiation head 21 Irradiation port 22 Mounting inner cylinder 23 Support ring 231 Hanging rod 3. Welding equipment 31 Robot Arm 32 Workbench 4. Laser light 5 Metal materials 51 Welding parts 6. Shielding Gas

Claims

1. When using a laser welding device that irradiates a laser beam from an irradiation head attached to a robot arm to wobble weld metal materials by moving the irradiation head while finely moving the laser beam, A laser welding method in which a cylindrical closed space portion connecting a first opening and a second opening on the same straight line is wobble-welded by laser light emitted from the first opening through the second opening while supplying a shielding gas into the inside of the closed space portion with the first opening attached in close contact with an irradiation head.

2. 2. The laser welding method according to claim 1, wherein the closed space has a frustum shape narrowing from the first opening toward the second opening, and the shielding gas is supplied from a position close to the first opening.

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