JPS60154889A - Laser welding method - Google Patents

Abstract

PURPOSE:To prevent oxidation of a working part in an atmosphere created by combustion of a resin layer by irradiating laser light to the working parts butted or superposed with the works provided with a combustible resin layer on at least one surface thereby welding said parts. CONSTITUTION:Works 11, 12 provided with resin layers 13, 14 are respectively butted at the ends thereof and are fixed by means of jigs. The laser light 17 condensed by a condensing lens 16 is then moved relatively with the works 11, 12 along a working part 15 to irradiate continuously said part 15. Then the vicinity of the part 15 is heated to a high temp. by which the resin layers 13, 14 of the surface irradiated with the laser light 17 and the resin layers 13, 14 on the opposite side of the surface irradiated by the laser light 17 are burned. The part 15 is enclosed by the atmosphere 18 created by the combustion and is isolated from the oxygen in the outdoor air in the same state as when the works are welded in an inert gaseous atmosphere. The resin layers 13, 14 may be provided only to the part 15 or may be further provided to either one surface.

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 10 and a workpiece (2) are butted together as shown in FIG. il+
, (2) are moved to perform welding.

At this time, the laser beam (4) is oscillated from the laser excavator (5), is deflected by the reflector (6), and is deflected by the condenser lens (7).
) and irradiates the processed area (3). The laser beam (4) uses a continuous wave type, and the heat generated when the laser beam (4) irradiates the processed part (3) completely melts the processed part (3), or the workpiece (1) ) and (2), this superimposed part becomes the processing part (3), and the laser beam (41) and the workpieces (1) and (2) move relative to each other to perform bath contact. When performing such laser welding processing, when the workpieces (1) and (2) are thin plates, especially when the thickness is 0.1
~05 mm, when the laser beam (4) is irradiated to the processed part (3), the processed part (3) becomes very high temperature, so this part and its vicinity will come into contact with oxygen in the atmosphere and be oxidized. is common.

For this reason, in the past, a tapered nozzle 187 that also served as a support for the condensing lens (7) and a pipe (9) were provided on the opposite side of the irradiation surface of the laser beam (4), and the nozzle (8) and the pipe [
9) was supplied with an inert gas ui′ft, and the inert gas [1] was blown onto the processed portion (3) to prevent oxidation of the processed portion (3).

However, in the above case, it is necessary to continuously blow out the inert gas αα during the welding process, that is, when the laser beam (4) is irradiating the processed part (3), and a gas supply device is required for this purpose. Therefore, the welding equipment itself becomes large-scale.

Furthermore, the jetting force of inert gas 0 (l) and Rjk from the nozzle (8) and pipe (9) become uneven, and the machining part (3
) is no longer uniformly sprayed, the bath contact condition at the processed portion (3) changes, and sometimes localized areas of poor welding condition may occur. This means that the processing section +
This problem becomes noticeable when the shape of l), (2) itself or the shape of the processed part (3) becomes complicated, even if the ejection force and flow rate of the inert gas un from the nozzle t8+ and pipe (9) are uniform. Also, inert gas [1
1 becomes very difficult to spray.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser welding method that can weld a workpiece while preventing oxidation of the workpiece without spraying an inert gas onto the workpiece.

[Summary of the invention]

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

[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 (t3, α
→ is provided. This is a vinyl chloride-based resin or a thermoplastic resin used as an ordinary insulating material, and is pre-coated on the surface of the workpiece α]), 02. In this way, one resin layer (L3. (1→) of the workpieces 0υ, (to) are butted against each other at their ends, and this part is used as a processing part) and is fixed by a jig not shown.

Therefore, the laser (17) ld focused by the condensing lens (16), the processing part (workpiece 01 along IQ), @
and relative movement 2, 'machining' Lt19 (16 irradiates continuously.

When the laser beam (17) irradiates the processed part αG, the processed part (
) is heated to a high temperature, the processed part (te melts, and the resin in the resin layer (va, a4) burns. At this time, the resin layer provided on the opposite side to the surface irradiated with the laser beam (17) The resin layers Q3 and u4 provided on the opposite side to the surface irradiated with the laser beam (17) also burn due to the high temperature caused by the laser beam (7). It burns due to the high temperature caused by the laser beam (17).For this reason, near the irradiation of the laser beam (17) in the processing area Qυ, the surrounding air (extension) due to the combustion of the resin causes the resin to be combusted, and the oxygen in the outside air is Therefore, the molten processing part αQ is not oxidized and the workpiece aη,@ is combined. In this way, the laser beam (17) and the workpiece (1υ, ( 6)
The laser beam (17) moves along the processing part (11)
Each time the laser beam (17) is irradiated, the combustion of the resin rytr t1 (t14) continuously prevents oxidation of the processed part IJ0, so the welding state in the processed part αυ after irradiation with the laser beam (17) is maintained in an inert gas atmosphere (( The condition will be the same as when welding.

Note that it is preferable to adjust the thickness of the resin layer (13, Q→) according to the relative movement speed of the laser beam (17). For example,
If the thickness of the workpiece tiBS (2) is thin and the power of the laser beam (17) is high, welding is possible even if the relative movement is made high. The thickness may be thin. Furthermore, as the thickness of the workpiece 11) increases, the relative movement speed of the laser beam (17) must be reduced. In this case, it is preferable to make the resin layer +V'3UΦ thick @ Also, the resin layer (t: +, Q4 is the workpiece (1υ, 11
It is not necessary to provide it on the entire surface of the surface, and it may be provided only on the processed portion. Furthermore, it is not necessary to provide it on both surfaces of the workpieces Ql) and 0, and it may be provided on only one of the surfaces. This means that the laser beam (17)
When the laser beam (17) is irradiated with heat, the resin layer α9, (14) is burnt by the heat directly transmitted to the cut-off processed portion OQ before the processed portion OQ is melted, and the processed portion (
This is because it surrounds the (to) with air.

〔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. Therefore, the above-mentioned device for supplying the inert gas is no longer necessary, and the welding apparatus can be made smaller. 1. The disadvantage of poor welding conditions due to uneven spraying of inert gas to the processed area has also been eliminated.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a conventional laser welding method, and FIGS. 2 and 3 are front views showing a simple embodiment of the present invention. Uη,03...Workpiece, (13,Q4)...Resin layer (c)...Processed part, (17)-...Laser light. Agent Patent Attorney Noriyuki Chika I LS Yu 11ts Figure 1 Figure 2 Figure 3

Claims (1)

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