JPS5949114B2 - Laser welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser welding method that reduces the thermal influence on the Ikekata side when a laser beam is irradiated from one side of a workpiece.

For example, when welding electrical parts, etc., a coating is applied to the surface of the workpiece through a cosmetic treatment such as painting or plating, and then a predetermined member is fixed to the back side of the workpiece by welding. There are cases.

In such a case, if the surface of the workpiece is greatly affected during welding, problems such as a reduction in quality of the coating provided on the surface and loss of adhesion to the base material arise. Conventionally, the means used for welding are arc welding,
Examples include gas welding, resistance welding, electron beam welding, and laser beam welding.

Among these methods, those using arc, gas, or resistance welding have a large thermal effect on both the front and back surfaces of the workpiece. On the other hand, when an electron beam or a laser beam is used, the thermal effect on the surface on the opposite side of the beam can be reduced to some extent compared to the former, but in the conventional technology, the coating formed on this surface is deteriorated due to the thermal effect. It cannot be made small enough to not cause quality deterioration such as discoloration. In particular, in the case of electron beams, the work must be carried out in a vacuum chamber, which is also impractical from this point of view. In addition, although laser beams do not have the disadvantages of electron beams, even if welding is performed by simply irradiating the laser beam from the back side of the workpiece, the coating on the back side may be affected by heat as described above. It's not something that can be protected. This invention was made based on the above circumstances, and its purpose is to bring a heat sink into close contact with one surface of a workpiece, irradiate a laser beam from the other surface, and place the workpiece on the heat sink. It is an object of the present invention to provide a laser welding method that can greatly reduce the thermal influence on one side of a workpiece by melting the workpiece at a depth that does not reach the surface to which it is in close contact.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

First, a first workpiece 2 having a coating 1 formed on its surface by painting or plating is placed with the coating 1 in close contact with the heat sink 3. The heat sink 3 is made of a material with high thermal diffusivity, such as copper. Next, a second workpiece 4 is provided in close contact with the back surface of the first workpiece 2. After that, the laser oscillator 5 disposed facing the heat sink 3 is activated, and the laser beam L output from the laser oscillator 5 is focused by the condensing lens 6 to form a second laser beam L.
The workpiece 4 is irradiated. At this time, in order to weld the first and second workpieces 2 and 4, both must be melted, but the depth of the melting should not reach the surface of the first workpiece 2. . In this case, the heat source is the laser beam L
Therefore, it is easy to control the melting depth of the workpiece,
In addition, control can be performed so that the heat received by the first workpiece 2 from the laser beam L is conducted to the heat sink 3 made of a material with a high thermal diffusivity that is in close contact with the coating 1 on the surface of the workpiece 2 to radiate the heat. In this way, even when the first workpiece 2 is irradiated and melted by the laser beam L, the temperature of the coating 1 on the surface thereof does not rise significantly, and the coating 1 does not change color, deteriorate in quality, or peel off. . Also, the laser beam L
By setting the melting depth to a depth that does not reach the surface of the first workpiece 2, the coating 1 on the surface will not be directly irradiated and melted by the laser beam L and will not be altered in quality.
What? However, the present invention is not limited to the above-mentioned embodiment. For example, when the work frequency is high, fins are integrally provided on the lower surface of the heat sink and the fins are forcibly cooled by a fan, thereby reducing the work frequency. Good welding work can be performed in the same way as when the temperature is low.

Furthermore, in the above embodiment, a film is formed on the workpiece to protect the film from heat effects, but the present invention is not limited to protecting the film, for example, on one side of the workpiece. It can also be applied to cases in which electrical parts are provided to protect them from the effects of heat during welding. As described above, the present invention brings the heat sink into close contact with one surface of the workpiece provided with the coating, and irradiates the laser beam from the other surface, so that the workpiece is brought into close contact with the heat sink. The heat that the workpiece receives from the laser beam is dissipated from the heat sink, and one side of the workpiece that is in close contact with the heat sink is hardly affected by the heat. I tried to avoid it. Therefore, according to this method, for example, when welding a workpiece on which a coating has been formed by painting or plating on one side, the coating can be welded without causing discoloration, deterioration, or peeling of the coating due to heat effects. be able to.

[Brief explanation of the drawing]

The drawing is a side view showing a schematic configuration of an embodiment of the present invention. 2, 4... Workpiece, 3... Heating body,
L...Loser Beam.

Claims (1)

[Claims] 1. A heat sink is brought into close contact with one surface of the workpiece provided with the coating, and a laser beam is irradiated from the other surface to place the workpiece at a depth that does not reach the one surface to which the heat sink is in close contact. A laser welding method characterized by melting.