JPH0424157B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a laser welding method for welding workpieces together by irradiating them with laser light.

[Technical background of the invention and its problems]

Nowadays, welding processing using laser light has become widely used as a laser application technology. In this laser welding process, for example, in seam welding, a workpiece 1 and a workpiece 2 are butted together as shown in FIG. Then weld.
At this time, the laser beam 4 is oscillated by the laser oscillator 5, deflected by the reflecting mirror 6, condensed by the condensing lens 7, and irradiated onto the processing section 3. Further, continuous wave laser light 4 is used, and the heat generated when the laser beam 4 is irradiated onto the processed portion 3 melts the processed portion 3 and joins the two workpieces 1 and 2 together. Fig. 1 shows the welding process when the workpieces 1 and 2 are butted together, but when the workpieces 1 and 2 are overlapped, this overlapped part becomes the processing part 3, and the laser beam 4 and the workpiece 1 , 2 are moved relative to each other to perform welding.

When performing such laser welding processing, when the workpieces 1 and 2 are thin plates, especially when the thickness is 0.1 to 0.5 mm, when the laser beam 4 is irradiated to the workpiece 3, the workpiece 3
Because the temperature is so high, this part and its surroundings often come in contact with oxygen in the atmosphere and become oxidized.

For this reason, in the past, a tapered nozzle 8 that also served as a support for the condenser lens 7 and a pipe 9 were provided on the side opposite to the irradiation surface of the laser beam 4, and the nozzle 8 and the pipe 9 were provided.
The inert gas 10 was supplied to the processing section 3 and the inert gas 10 was blown onto the processing section 3 to prevent the processing section 3 from being oxidized.

However, in the above case, during the welding process, that is, when the laser beam 4 is irradiating the process area 3, the inert gas 10 must be continuously ejected, and a gas supply device for this is required. That in itself becomes a big deal. Furthermore, if the jetting force and flow rate of the inert gas 10 from the nozzle 8 and pipe 9 become uneven, and the spraying onto the processed part 3 becomes uneven, the welding condition in the processed part 3 changes, and sometimes locally There may be areas where the welding condition is poor. This problem occurs noticeably when the shapes of the processing parts 1 and 2 themselves or the shape of the processing part 3 become complicated, and even if the ejection force of the inert gas 10 from the nozzle 8 or the pipe 9 is
Even if the flow rate is uniform, it is very difficult to uniformly spray the inert gas 10 onto both sides of the processing section 3.

[Purpose of the invention]

An object of the present invention is to provide a laser welding method that can perform welding while preventing oxidation of a workpiece without spraying inert gas onto the workpiece.

[Summary of the invention]

The present invention is a laser welding method in which a flexible resin layer is provided on the surface of at least one processed part of a workpiece, and welding is performed while burning the resin layer by irradiating laser light. Welding is performed while the workpiece being irradiated with laser light is protected from oxygen in the outside air by the surrounding air created by the combustion of the layer.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to the drawings. FIGS. 2 and 3 are front views showing this embodiment. First, in FIG. 2, resin layers 13 and 14 are provided on both surfaces of workpieces 11 and 12. This is made by coating the surfaces of the workpieces 11 and 12 in advance with a flexible vinyl chloride resin or a resin used as a normal insulating material. In this way, the workpieces 11 and 12 provided with the resin layers 13 and 14 are butted against each other at their ends, and this part is fixed as a workpiece 15 by a jig (not shown). Therefore, condenser lens 1
The laser 17 focused by
The processing section 15 is continuously irradiated by moving relative to the workpieces 11 and 12 along.

When the laser beam 17 irradiates the processed portion 15, the vicinity of the processed portion 15 is heated to a high temperature, the processed portion 15 is melted, and the resin of the resin layers 13 and 14 is burned. At this time, the resin layers 13 and 14 provided on the side opposite to the surface irradiated with the laser beam 17 are also
3 and 14 are also burned due to the high temperature caused by the laser beam 7. Therefore, due to the high temperature caused by the laser beam 17 in the processing section 15, it burns. Therefore, the vicinity of the laser beam 17 irradiation in the processing section 15 is surrounded by the surrounding air 18 due to the combustion of the resin, and is isolated from the oxygen in the outside air. Therefore, the molten processed portion 15 is not oxidized, and the workpieces 11 and 12 are bonded together.

In this way, the laser beam 17 and the workpieces 11 and 12
and moves relative to each other, and the laser beam 17 is transmitted along the processing section 15.
Each time the laser beam 17 is irradiated, the resin layers 13 and 14 are burned to constantly prevent oxidation of the processed area 15, so the welding condition in the processed area 15 after irradiation with the laser beam 17 is the same as when welding in an inert gas. The state will be as follows.

Note that the thickness of the resin layers 13 and 14 is determined by the laser beam 17.
It is preferable to adjust it according to the relative movement speed of.
For example, if the thickness of the workpieces 11 and 12 is thin and the power of the laser beam 17 is high, welding is possible even if the relative movement is made at a high speed, but the thickness of the resin layers 13 and 14 in this case is It can be thin. Moreover, when the thickness of the workpieces 11 and 12 becomes large, the laser beam 1
The relative movement speed of 7 must be small.
In this case, it is preferable that the resin layers 13 and 14 be thick.

Further, the resin layers 13 and 14 do not need to be provided on the entire surface of the workpieces 11 and 12, and may be provided only in the processed portion 15. Furthermore, the workpieces 11 and 12
It is not necessary to provide it on both surfaces, and it may be provided on only one of the surfaces. This is because when the laser beam 17 is irradiated onto the processed portion 15, before the processed portion 15 melts, the resin layers 13, 15 are damaged either directly by the heat of the laser beam 17 or by the heat conducted through the processed portion 15. This is because the gas burns and surrounds the processing section 15 with feces.

〔Effect of the invention〕

As explained above, in the laser welding method of the present invention, it was possible to weld the workpiece while preventing oxidation of the workpiece without spraying inert gas onto the workpiece. This eliminates the need for the above-mentioned device for supplying inert gas, making it possible to downsize the welding device. In addition, the drawback of poor welding conditions caused by uneven spraying of inert gas onto the processed area has also been eliminated.

[Brief explanation of drawings]

FIG. 1 is a front view showing a conventional laser welding method, and FIGS. 2 and 3 are front views showing an embodiment of the present invention. 11, 12...Workpiece, 13, 14...Resin layer, 1
5... Processing section, 17... Laser light.

Claims (1)

[Claims] 1 In a laser welding method in which two workpieces are butted or overlapped, this part is treated as a processing part, and a laser beam is irradiated along the processing part to perform welding, a laser welding method is employed in which a laser beam is welded on the surface of at least one of the processing parts. A laser welding method characterized in that a resin layer is provided, and welding is performed while burning the resin layer by irradiating with laser light.