JPH08318384A - Laser beam welding method for material of high reflection ratio - Google Patents

Abstract

PURPOSE: To provide a laser beam welding method of a material having a high reflection ratio which can stably weld the material having a high reflection ratio against the carbon dioxide gas laser beam. CONSTITUTION: A carbon dioxide gas of a shield gas SG to shield welding parts 5A, 5B from the atmosphere is made to a plasma gas of a high temperature by the interaction with a carbon gas laser beam 29, and in this laser beam welding method of the material having the high reflection ratio, the radiation energy radiated from this high temperature plasma gas territory 33 is used for welding.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to a method for laser welding high reflectance materials.

[0002]

2. Description of the Related Art Conventionally, in the laser welding of easily oxidizable metals, an inert gas such as argon gas or helium gas is used as a gas for shielding the weld from the atmosphere in order to prevent the oxidation reaction of the weld. There is. Laser welding of metal materials is mainly used for carbon steel and stainless steel, which are metal materials having a relatively low reflectance.

[0003]

In the above laser welding of a metal material, a metal having a high reflectance, for example, aluminum having a reflectance of 0.9 or more with respect to carbon dioxide laser light, polished silver or the like is carbon dioxide gas. Laser welding was difficult.

Aluminum, for example, is susceptible to oxidation during welding, so it is necessary to use expensive inert gases such as argon gas or helium gas to shield the weld from the atmosphere.

Further, since aluminum exhibits a reflectance of 0.9 or more in the solid state as described above, a large amount of energy is required to melt it. Since it absorbs gas laser light well, it does not require as much energy as when starting welding. In addition, since molten aluminum has a low viscosity and a good fluidity, it easily flows out of the weld.

For the above-mentioned reason, in the laser welding of aluminum, since the difference between the laser energy required at the start of welding and the laser energy required after the start of melting is large, it is difficult to control the input energy to the welding material, and the input energy is difficult. Is insufficient and melting does not proceed, or excessive input energy causes complete melting and cutting.

The present invention has been made in view of the above problems, and has a high reflectance capable of stably welding a high reflectance material having a reflectance of 0.9 or more for carbon dioxide laser light. It is to provide a laser welding method for materials.

[0008]

In order to achieve the above object, a laser welding method for a high reflectance material according to the present invention is a carbon dioxide laser welding method using a shield gas for shielding a welded portion from the atmosphere. Carbon dioxide is used as the shielding gas, this carbon dioxide is made into a high temperature plasma gas by the interaction with the carbon dioxide laser light, and the radiant energy radiated from this high temperature plasma gas region is used for welding. It is a feature.

[0009]

The laser welding method for a high reflectance material according to the present invention shields the welded portion from the atmosphere by the carbon dioxide shielding gas, and at the same time, the carbon dioxide gas interacts with the carbon dioxide laser to generate a high temperature plasma. The radiant energy emitted from the high temperature plasma gas after being gasified can be used for welding.

[0010]

EXAMPLE An example of a laser welding method for a high reflectance material by a carbon dioxide gas laser according to the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual drawing of a CNC-controlled optical axis moving laser processing apparatus used for carrying out the laser welding method of a high reflectance material of the present invention. The optical axis moving laser processing apparatus 1 includes a portal frame 3, and a table 7 on which a workpiece 5 is placed is provided below the portal frame.

A Y-axis carriage 11 is provided on the beam portion 9 of the gate-shaped frame.
Is in the Y-axis direction (left-right direction in FIG. 1) by a well-known drive mechanism (not shown) controlled by the CNC controller.
It is configured to be freely positionable at any position.

The Y-axis carriage 11 has the C
A well-known drive mechanism (not shown) controlled by an NC controller is provided with an X-axis carriage 13 which can be positioned at an arbitrary position in an X-axis direction (direction orthogonal to the paper surface) orthogonal to the Y-axis direction, A laser processing head 15 is attached to this X-axis carriage.

Therefore, the laser processing head 15 can be positioned at any position on the XY axes by the CNC controller. A high-pressure shield gas supply source 19 for supplying a shield gas SG of carbon dioxide gas instead of the assist gas AG used for laser cutting is shown in the assist gas injection nozzle 17 of the laser processing head 15 (see FIG. 2A). Is installed near the laser processing apparatus 1, and the assist gas supply port 2 of the laser processing apparatus 1
1, a shield gas supply pipe 23 from the shield gas supply source 19 is connected via a regulator 25.
The shield gas is supplied to the laser processing head 15 via a pipe (not shown).

FIG. 2A shows the laser processing head 1 described above.
5 is a magnified view of the portion 5 in which the aluminum welded members 5A and 5B have a high reflectance close to 1.
Is placed on the table 7 (not shown) with the welding surface WS in contact.

The processing head 15 is provided with a converging optical system 27 such as a convex lens or a concave mirror, and the carbon dioxide laser light 29 is used by the condensing lens 27 to weld surfaces of the welding members 5A and 5B. It is focused on the surface of WS.
An inlet 31 for the assist gas AG or the shield gas SG is provided at a lower position in the vicinity of the condenser lens 27, and a carbon dioxide shield gas SG is introduced from the inlet 31.
Is introduced and carbon dioxide laser light 2 is emitted from the injection nozzle 17.
It is sprayed on the surface of the welding surface WS of the welding members 5A and 5B together with 9.

Now, the details of the laser welding method for the high reflectance material by the carbon dioxide laser will be described. The laser welding method for a high reflectance material using a carbon dioxide laser according to the present invention is characterized in that carbon dioxide is used as the shield gas SG, and this carbon dioxide becomes a high temperature plasma gas by the laser light. Is used.

FIG. 2 (b) is a magnified view of the vicinity of the focal point of the carbon dioxide laser beam 29 applied to the surface of the workpiece 5A. The carbon dioxide gas as the shield gas SG introduced from the shield gas inlet 31 is jetted from the jet nozzle 17 to the surface of the welding surface WS of the welding members 5A and 5B together with the carbon dioxide laser light 29. The outer circumference of the conical carbon dioxide laser beam 29 between the injection nozzle 17 and the surface of the welding surface WS of the welding members 5A and 5B is a carbon dioxide atmosphere 30.

Now, the generation process of the plasma gas and its action will be described. Carbon dioxide used as the shield gas SG has a characteristic of absorbing carbon dioxide laser light (wavelength 10.6 μm) very well when the temperature becomes 100 ° C. or higher.

When the surface of the welding surface WS of the aluminum welding members 5A and 5B is irradiated with carbon dioxide laser light (wavelength 10.6 μm) from the nozzle 17, the aluminum welding members 5A and 5B having high reflectance are also welded. Surface WS
The surface temperature of is instantaneously heated to 100 ° C. or higher.

As a result, the carbon dioxide gas as the shield gas SG is heated to 100 ° C. or higher by the weld metal heated by the carbon dioxide laser to raise its temperature. Temperature is 10
The carbon dioxide gas having a temperature of 0 ° C. or higher absorbs the carbon dioxide gas laser light (wavelength 10.6 μm) very well, so that the carbon dioxide gas is further heated to be plasma gasified and the high temperature and high pressure plasma gas region 33 is welded to the welding member 5A 5B is formed on the welding surface WS.

The strong electromagnetic wave radiation from the high temperature and high pressure plasma gas region 33 causes the welding member 5 to move.
The surfaces of the welding surfaces WS of A and 5B are melted to form a molten pool 35.

As described above, when the surface of the welding surface WS of the welding members 5A and 5B is melted and the molten pool 35 is formed, the movement of the laser processing head and the laser output are C
It is possible to perform continuous or intermittent welding along an arbitrary curve by appropriately controlling by the NC device.

Although an example of aluminum has been described in the embodiments, the present invention can be similarly applied to copper, which has a high reflectance similar to aluminum, or silver whose surface is polished.

The laser processing apparatus 1 shown in FIG.
In the laser processing head 15 of FIG. 3, the shield gas SG from the jet nozzle 17 is jetted onto the surface of the welding member 5 together with the carbon dioxide laser light 29.
As shown in FIG. 3, a shield gas injection nozzle 43 is provided on the side of the processing head 41 having the condenser lens 27.
Even in the laser processing apparatus configured to inject the shielding gas from the surface 3 of the welding member 5 from 3, the laser welding method of the high reflectance material by the carbon dioxide laser according to the present invention can be carried out.

The laser processing apparatus for carrying out the laser welding method of the high reflectance material by the carbon dioxide laser according to the present invention is not limited to the above-mentioned laser processing apparatus, but may be a material moving type or an optical axis moving type. The known laser processing device of can be used.

[0026]

As can be understood from the above description of the embodiments, according to the invention described in claim 1 or 2, the material having a high reflectance for the carbon dioxide gas laser having the wavelength of 10.6 μm. In the welding, the carbon dioxide gas laser beam having a wavelength of 10.6 μm is absorbed by the carbon dioxide gas, and the welding can be performed in a stable state by the radiant energy from the carbon dioxide gas plasma generated by the absorption of the carbon dioxide gas laser beam.

[Brief description of drawings]

FIG. 1 is an example of a carbon dioxide gas laser processing apparatus used in a laser welding method for a high reflectance material according to the present invention.

2 is an enlarged view (a) of a laser processing head portion of the laser processing apparatus of FIG. 1 and an explanatory view of a laser welding method for a high reflectance material according to the present invention.

FIG. 3 is an example of another carbon dioxide gas laser processing apparatus that can be used in the laser welding method of the high reflectance material of the present invention.

[Explanation of symbols]

 1 Optical axis moving laser processing device 5A, 5B Welding member 15 Laser processing head 29 Carbon dioxide laser light 33 Plasma gas region 35 Molten pool SG Shield gas WS Welding surface

Claims (1)

[Claims] 1. A carbon dioxide gas laser welding method using a shield gas for shielding a welded portion from the atmosphere, wherein carbon dioxide gas is used as the shield gas, and the carbon dioxide gas is heated to a high temperature by interaction with the carbon dioxide laser light. A laser welding method for high-reflectance materials, which is characterized by using plasma gas and radiant energy radiated from this high-temperature plasma gas region for welding.