JPS60121093A - Laser welding method - Google Patents

Abstract

PURPOSE:To improve productivity by preheating the part on a weld line by a preheating beam formed of a part of a laser beam for welding then executing welding. CONSTITUTION:A part of a laser beam 11 is taken out as a laser beam 12 for preheating by a semitransparent mirror 13 and is irradiated with a blurred focus F on the weld line of base metals 16 by using a mirror 14 and a lens 15. The beam 12 burns or evaporates stains 17 such as oil on the surface of the metals 16 and preheats the base metals. The beam 11 is focused F by a lens 18 onto the weld line of the base metals 16, by which welding on the weld line cleaned up and preheated by the preheating beam 12 is executed. The smoke, etc. 19 generated by the beam 12 is blown off by using an inert gas 21 from a nozzle 20. The welding is accomplished with less defects by the above-mentioned method. The number of stages is thus reduced and productivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Rede welding method applied to heat exchangers, air fin coolers, automobile sheet metal parts, etc.

The Rede welding method has a p-high energy density different from arc welding methods and the like. Therefore, the heat affected zone and thermal deformation caused by welding are small, and high-speed, high-precision welding is possible. In addition, productivity is high because deep penetration welding can be performed with groove joints.

The conventional Rede welding method is shown in Fig. 1. In this method, after cleaning and preheating the welding part of the base material 1 (workpiece), the base material 1 is irradiated with a laser beam 3 focused by a condenser lens 2 to perform welding. Here is the 4th floor in the diagram! Argon gas for welding shield, 5 is welding metal maple.

However, this welding method has the following drawbacks.

In other words, if the surface of the base metal is contaminated with oil or the like, the weld metal neutralizes the vapor and traps it.

This can cause welding defects such as plowholes. For this reason, conventionally, before welding, it is necessary to clean the base metal surface with an organic solvent or the like to remove oil and other stains.

In addition, if the welded part has a complicated shape, it takes time to clean it, which reduces the high productivity that is a characteristic of laser welding. Furthermore, since cracks are likely to occur when welding medium- and high-carbon steels, the base metal must be preheated. Currently, this process is carried out using electric furnaces, etc., but this not only impairs productivity, but also causes problems in products that require high precision, such as thermal deformation and weld cracking. For this reason, there are cases in which the features of the Rede welding method, which enables high-precision welding, are not fully utilized.

The present invention has been made in view of the above circumstances.

The purpose is to develop a laser welding method that can omit cleaning of the matrix surface, prevent thermal deformation and weld cracking, and improve productivity and quality by performing preheating and welding in one step. It is something that you are trying to gain.

That is, in the present invention, a part of the welding laser beam is branched to form a preheating laser beam, and this preheating laser beam is irradiated onto the weld line before welding to burn and evaporate dirt near the weld line. The method is characterized in that local preheating is performed and then welding is performed using the welding laser beam described above.

The method of the present invention will be explained below with reference to illustrative examples.

In this Rade welding method, as shown in FIG. Irradiate the weld line just before welding with the focus F. This preheating laser beam 1
2 removes dirt 17 such as oil and water on the surface of the base material 16 by burning or evaporating it, and at the same time performs local preheating.

The contact radar beam 1 is focused by a condensing lane 18 and irradiated with a focus F on the welding line of the base material 16, and performs welding on the welding line that has been cleaned and preheated by the preheating radar beam 12.

According to this welding method, since the dirt 17 on the metal surface easily absorbs the laser beam, it can be efficiently burned and evaporated by the preheating Rede beam. Moreover, since the welding point is very small (about 0.1 mt in diameter), the focus of the preheating laser beam 12 can be kept small. Therefore, the energy density increases, and this laser beam 12
The / armpit can be made smaller. Further, although the reflectance of the laser beam is high on a shiny metal surface, the absorption rate is high due to an oil film, etc., and preheating is possible even with a small power. Therefore, the power of the welding laser beam 11 does not decrease significantly, and there is no significant deterioration in welding characteristics such as penetration depth.

Incidentally, smoke and steam 19 such as oil and water generated by the irradiation of the preheating laser beam 12 are blown off using an inert gas such as yen gas through the nozzle 20 to reach the surface of the metal. It is possible to prevent a decrease in the power of the laser beam 7 and increase the effect. In addition, 22 in the figure is weld metal, 2
3 indicates argon gas for welding shield.

However, the laser welding method of the present invention has the following effects.

That is, conventionally, three steps were required: cleaning the metal surface with an organic solvent, preheating, and welding, but with this method, these steps can be performed simultaneously, reducing the number of steps to one, improving productivity. Additionally, since no organic solvent is used, worker safety is improved. Furthermore, since local preheating is performed before welding, there is almost no thermal deformation.

Next, specific examples of the present invention will be described.

When performing welding with a CO laser with an output of 3KW, a semi-transparent mirror 1 that reflects approximately 10% of the laser beam in Fig. 2
3, the preheating radar beam 12 was taken out and irradiated onto the metal surface of the base material 16. Since the bead width produced by laser welding is about 3 mm, the spot size of the preheating laser beam 12 on the metal surface was set to about 5 nm, taking into account a margin of 1 on both sides. The power density of this beam on the metal surface is approximately 400 W/crn'', which is sufficient power density to burn and vaporize oil on the metal surface.

In addition, some of this energy is also absorbed by the base material entertainment,
A local preheating effect was obtained. Preheating radar beam 12
The oil vapor 19 generated by the irradiation was blown away with nitrogen gas, and metals with an oil film were welded without reducing the amount of energy reaching the surface of the metal.
Good welding results were obtained with no blowholes or weld cracks. In addition, as a result of performing laser bath welding without cleaning the surface of this metal using the conventional laser welding method shown in FIG. It was done. From this, it was confirmed that the laser welding method according to the present invention is an efficient (three welds become one process) high quality (no welding defects) laser welding method.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional Lede bath welding method, Fig. 2 is an explanatory diagram of a laser bath welding method showing an embodiment of the present invention, and Fig. 3 is an explanatory diagram showing laser welding results in a comparative example. . 1 No... Laser beam for welding, 12... Radhe beam for preheating, 13... Semi-transmissive mirror, 14... Total reflection mirror, 15... Condensing lens, 16... Base material, 17・・・
- Dirt, 18... Condensing lens, 19... Steam, 20
...Nozzle, 21...Inert gas, 22...Welding entertainment. 23...Argon gas for welding shield, 24...Blow pole. Applicant's agent Patent attorney Takehiko Suzue Figure

Claims (1)

[Claims] A part of the welding laser beam is branched to form a preheating L/-f beam, and this preheating radar beam is irradiated onto the welding line before welding to preheat the welding line. Welding is performed using the preheated trailing zero pin welding laser beam. Rede welding method characterized by construction.