JPS6114093A - Laser welding method - Google Patents

Abstract

PURPOSE:To execute stable laser welding and processing while assuring the formation of penetration beads and allowing the easy expansion of penetration by reflecting the laser light past the keyhole generated in a welding part in the stage of laser welding and heating adequately the rear of the weld zone. CONSTITUTION:The laser light past the keyhole generated in the welding part is reflected by a hollow curved surface 8 provided to the recess 7 of a backing strip and is irradiated on the rear surface in the weld zone of a welding member 3 in the stage of welding said member by the laser light emitted from a welding torch 1. The irradiated part is adequately heated, by which the formation of the penetration beads is assured and the penetration is easily expanded. The welding and processing are thus stabilized. An inert gas may be blown to the recess 7 to prevent the oxidation thereof and in some cases, the inert gas may be blown from the side face of the recess 7. The surface 8 may be made into an interchangeable type.

Description

[Detailed description of the invention] [Technology of invention ° field] The present invention relates to a laser welding method.

[Technical background of the invention and its problems]

Conventionally, it has been common practice to use a copper plate as a backing metal during welding, and laser welding is no exception.However, this is used as an extension of normal welding, and keyhole There was no idea of actively using the leaking laser beam to secure back waves and expand penetration.

In order to perform sound penetration welding in one pass, it is essential to form and secure a back wave, but in conventional laser welding, in order to increase the energy density, it is necessary to increase the laser power and welding speed.
Measures were taken to lower the level. No attention was paid to the laser beam Kti leaking from the kinihole, which rather caused thermal deformation of the jig.

[Purpose of the invention]

An object of the present invention is to provide a laser welding method that contributes to ensuring the formation of back waves and expanding the penetration.

[Summary of the invention]

It is designed so that the laser beam leaking through the keyhole formed in the welded part during laser welding is reflected back to the welded part.

[Embodiments of the invention]

The present invention will be explained below with reference to an embodiment shown in FIG.

In the figure, (1) is a welding torch, and a lens (not shown) for focusing a laser beam (2) is placed inside the welding torch. f3)
, (4) are welding parts to be butt welded, including a copper backing plate (5), holding members (6a), (6b), and K.
The parts except the welded parts that are butted together are restrained. The backing plate (5) has four parts (7) that are opposite to the back side of the welded part, and the bottom of this recess has a predetermined curvature and a concave curved surface (8) K with respect to the back side.
and its surface is formed into a highly reflective surface. Concave curved surface (
8) and the back surface of the welded portion is set at 3 to 5 degrees. Near one side of the backing plate (5), nitrogen gas or other inert gas is injected into the recess (to prevent the concave curved surface (8) from blackening due to force and to prevent oxidation on the back side of the welded part). A spray nozzle (9) is provided, where:
The welding torch (1) and the backing plate (5) are configured to move relative to each other along a welding portion indicated by an arrow (4) by a sliding device (not shown).

In the above configuration, for example, the welding torch (1) is moved along the welding part and the laser beam (2) is irradiated to the butt part of the welding parts (3) and (41) when the welding part is being welded. is formed. In the process of forming this welded part (11), a keyhole is generated, and a part of the laser beam (2) being irradiated leaks through this keyhole to the back side of the welded part.

The leaked laser beam passes through the concave curved surface (8) formed on the highly reflective surface.
) and irradiates the back side of the welded part, heating that part. In addition, during the welding pressurization, inert gas is constantly ejected from the nozzle (9) to prevent the above-mentioned oxidation and blackening.

By the way, in the above embodiment, the concave curved surface (8) which is a part of the backing plate (5) is used as a reflective surface, but this is not limited to this. For example, as shown in FIG. It is also possible to provide a recess (7) K so that it can be replaced.

Regarding the supply of inert gas, as shown in FIG. If only the bottom surface of (7) is made a reflective surface, and the @ surface is also made a reflective surface, the use of incident laser light on the side surface can be increased. Fifth
The figure shows an example in which welding members H and f13 are corner welded, in which a supporting member aa having a curved cutout is disposed on the opposite side of the welding part and welding is performed. In this embodiment, the cutout portion is formed on the reflective surface.
During welding, an inert gas is supplied as in the above embodiment.01' Note that since the temperature of the backing plate (5) and support member (141) increases, it is preferable to add water cooling or other cooling means.

〔Effect of the invention〕

During welding, the laser light leaking from the welded part is irradiated onto the back side of the welded part, so the back side of the welded part is heated appropriately.
Uranami formation is ensured, weld penetration is easy to expand, and stable laser welding can be performed.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram for explaining one embodiment of the present invention, FIG. 2 is a side view of FIG. 1, and FIGS. 3 to 5 are perspective views for explaining other embodiments of the present invention. It is a diagram. (1)...Welding torch, (2)...Laser light, (3
), (41... Welding member, (5)... Backing plate. (6a), (6b)... Holding member, (8)... Concave curved surface, (9)... Nozzle. Agent. Patent Attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 112 Figure 3 Figure 5 Figure 114

Claims (1)

[Claims] A laser welding method characterized in that the laser beam that passes through a keyhole formed in a welded part during laser welding is reflected to the back side of the welded part to perform welding.