JPH0123236B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser welding method mainly for lap welding of metals with relatively high thermal conductivity such as silver and copper.

Even when metals with high thermal conductivity are irradiated with laser light, a large amount of energy diffuses outside the welding area.
It was not possible to weld with sufficient strength. In addition, the energy distribution of the laser beam is high in the center and low in the periphery, which is a so-called Gaussian distribution, which makes overlapping welding of the above-mentioned metals even more difficult.
Conventionally, as shown in FIG. 1, of the overlapping workpieces 1 and 2, the side receiving the spot 5 of the laser beam 4 that has passed through the condenser lens 3 and been defocused, that is, the workpiece 1 In this welding process, a hole 6 smaller than the diameter of the spot 5 is drilled, but as the thickness of the welded member 1 increases, the welding part 7 becomes thicker, as shown in FIG. Cavities 8 frequently occur, and sufficient welding strength cannot be obtained.

This invention was made in view of the above circumstances, and in a laser lap welding method,
The object of the present invention is to provide a laser welding method that causes fewer welding defects and requires a low level of laser output for welding.

EMBODIMENT OF THE INVENTION Hereinafter, this invention will be explained based on drawing which shows an Example.

FIG. 3 shows a first embodiment showing an example of welding electrical component materials. Reference numeral 11 indicates a contact member made of silver or silver alloy, which is a welding member, and 12 indicates this member 1.
The spring material is the other welding member superimposed on 1 and is mainly made of copper or copper alloy. Spring material 1
2 is bored with a hole 13 whose diameter gradually decreases toward the contact member 11. In this embodiment, the hole 13 is concentric with the large diameter portion 14a and the central portion 14.
b, and a small diameter portion 14c. Therefore, inside the hole 13, two horizontal step portions 15a and 15b are formed. A laser oscillator 16 and a condensing lens 18 for condensing laser light 17' output from the oscillator are disposed above the hole 13. The small diameter portion 14c is formed to a size that allows the high energy portion of the laser beam 17 transmitted through the condensing lens 18 to pass through.

With the above configuration, when the out-of-focus laser beam 17 is irradiated toward the hole 13, the edge portions 19a and 19b of each step portion 15a and 15b melt and move toward the small diameter portion 14c, as shown in FIG. It flows out like a landslide.

By the way, in the contact member 11, the laser beam 1
7. The portions to be irradiated are the edge portions 19a, 1
Although it is in a flat state that is difficult to melt compared to 9b,
Since the high energy density portion of the laser beam 17' is irradiated through the small diameter portion 14c, the contact member 11 is melted almost instantly despite its shape and high thermal conductivity. Therefore, the molten material of the edge portions 19a and 19b that melted like a landslide,
The molten material of the contact member 11 is well fused to form a welded portion 20 without voids as shown in FIG. 5, and the point member 11 and the spring material 12 are welded with high strength.

As described above, the present invention makes the irradiated part of the member on the front side of the laser beam irradiation in overlap welding an angular step-like shape that is easy to melt even with relatively low energy, and furthermore, the laser beam irradiation Since the irradiation part of the member on the rear side was configured to receive irradiation with a portion having a high energy distribution of laser light, both members could be successfully welded even with a relatively low level of laser output. In addition, since the welded part has a low level of output, heat dissipation from the component on the rear side is suppressed to a low level, which prevents the occurrence of defects such as voids and deterioration due to excessive heat input, improving the reliability of welding strength. We were able to.

Figures 6 to 8 are the second to fourth figures of this invention.
6 shows an example in which the irradiated part of the member on the front side of the laser beam irradiation is formed in a hole 22 having an inclined step 21;
The figure shows an example in which one step is formed into a hole 24 having a hole 23, and FIG. 8 shows an example in which a groove 25 is formed instead of the hole shape shown in each of the above embodiments. In the second embodiment shown in FIG. 6 above, the stepped portion 21 has a tapered hole shape, but this does not require that the stepped portion be particularly horizontal. It is only necessary to form an edge portion 22a that is easy to bend.
1 is shown slightly straddling it. In addition, in the fourth embodiment shown in FIG. 8, the front member is divided into two parts, each with a step formed at the end and facing each other; In some cases, it may be formed into a long hole. Note that welding is performed by scanning the laser beam and the member to be welded relative to each other. The embodiments shown in FIGS. 6 to 8 described above also provide substantially the same effects as the first embodiment.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and two or more step portions may be formed, and various modifications may be made without departing from the spirit of the invention.

[Brief explanation of drawings]

1 and 2 are sectional views showing a conventional welding method, FIGS. 3 to 5 are sectional views showing a first embodiment of the present invention, and FIGS. 6 and 7 are sectional views showing a conventional welding method. 2. FIG. 8 is a sectional view showing the third embodiment, and FIG. 8 is a perspective view showing the fourth embodiment of the present invention. 11, 12... Welding member, 13... Hole, 15
a, 15b...Step part, 16...Laser oscillator, 1
7'... Laser light, 18... Condensing lens, 25...
…groove.

Claims (1)

[Claims] 1. In a laser welding method in which metals with high thermal conductivity are stacked together and one of the metals is irradiated with a laser beam, the laser beam irradiation part of one of the metals on the front side of the irradiation has at least one or more stepped portions. A laser welding method characterized by forming a stepped hole or groove and welding by irradiating the stepped portion with a laser beam.