JP3526964B2 - Laser welding method for high reflectivity materials - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding method for high reflectivity materials. Conventionally, in 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. in use. Laser welding for metal materials is mainly used for carbon steel, stainless steel and the like, which are metal materials having relatively low reflectivity. [0003] In the above laser welding for metal materials, metals having high reflectivity, such as aluminum having a reflectivity of 0.9 or more for carbon dioxide laser light, polished silver, etc. It was difficult to weld with carbon dioxide laser. For example, since aluminum is easily oxidized during welding, it is necessary to use an expensive inert gas such as argon gas or helium gas to shield the weld from the atmosphere. In addition, since aluminum exhibits a reflectivity of 0.9 or more in the solid state as described above, a large amount of energy is required to melt it. Since the gas laser light is absorbed well, it does not require a large amount of energy as at the start of welding. In addition, molten aluminum has a low viscosity and good fluidity, so it tends to flow out of the weld. For the above reasons, in laser welding of aluminum, the difference between the laser energy required at the start of welding and the laser energy required after the start of melting is large, so it is difficult to control the input energy to the welding material. The melting may not be progressed due to shortage, or it may be completely melted and cut by excessive input energy. The present invention has been made in view of the above-mentioned problems, and has a high reflectivity capable of stably welding a high reflectivity material having a reflectivity of 0.9 or more with respect to carbon dioxide laser light. It is to provide a method for laser welding of materials. [0008] To achieve the above object, resolving means for the problems], laser welding method of the high reflectance material of the present invention, Leh
Laser that can irradiate the laser beam onto the welding surface of the welding member
Move the machining head in the X-axis or Y-axis direction with respect to the welding member
In addition to being provided with dynamic positioning, the shield gas is
Acid gas is used and this carbon dioxide gas is mixed with carbon dioxide laser light.
This high temperature plasma gas by interaction, this high temperature
Radiant energy emitted from the plasma gas region
More high temperature and high pressure plasma gas on the welding surface of the welding member
A strong electromagnetic wave from the plasma gas region
A molten pool is formed on the weld surface by radiation of the molten pool,
The laser processing head with respect to the X axis or the Y axis
By relative movement in the direction, the reflectance is 0.9
The gist is to perform the welding of the above high reflectivity materials . According to the laser welding method of the high reflectivity material of the present invention, the welded portion is shielded from the atmosphere by a carbon dioxide gas shielding gas, and at the same time, the carbon dioxide gas is highly enhanced by the interaction with the carbon dioxide laser. The radiant energy radiated from this high temperature plasma gas after being converted into a temperature plasma gas can be used for welding. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a laser welding method of a high reflectivity material using a carbon dioxide laser according to the present invention will be described 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 a laser welding method of a high reflectivity material of the present invention. This 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 portal frame.
Is in the Y-axis direction (left-right direction in FIG. 1) by a known drive mechanism (not shown) controlled by the CNC control device
It is configured to be freely positionable at any position. The Y-axis carriage 11 has the C-axis.
An X-axis carriage 13 that can be positioned at any position in the X-axis direction (direction orthogonal to the paper surface) perpendicular to the Y-axis direction is provided by a known drive mechanism (not shown) controlled by the NC control device, A laser processing head 15 is attached to the X-axis carriage. Accordingly, the laser machining head 15 can be positioned at any position on the XY axes by the CNC control device. Also, a high-pressure shield gas supply source 19 for supplying a carbon dioxide shield gas SG in place of the assist gas AG used for laser cutting in the assist gas injection nozzle 17 “see FIG. 2A” of the laser processing head 15. Is installed near the laser processing apparatus 1 and the assist gas supply port 2 of the laser processing apparatus 1
1 is connected to a shield gas supply pipe 23 from the shield gas supply source 19 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.
5 is an enlarged view of an aluminum welding member 5A, 5B having a high reflectivity close to 1.
Is placed on the table 7 (not shown) with the welding surface WS in contact therewith. The processing head 15 is provided with a condensing optical system 27 such as a convex lens or a concave mirror, and the carbon dioxide laser beam 29 is transmitted to the welding surfaces of the welding members 5A and 5B by the condensing lens 27. It is condensed on the surface of WS.
An inlet 31 for assist gas AG or shield gas SG is provided at a lower position in the vicinity of the condenser lens 27, and carbon dioxide gas shield gas SG is provided from the inlet 31.
Is introduced and carbon dioxide laser light 2 is emitted from the injection nozzle 17.
9 is injected onto the surface of the welding surface WS of the welding members 5A and 5B. Now, the details of the laser welding method of the high reflectivity material by the carbon dioxide gas laser will be described. The laser welding method of a high reflectivity material using a carbon dioxide laser according to the present invention is characterized in that carbon dioxide is used as the shielding gas SG, and the carbon dioxide gas becomes a high-temperature plasma gas by laser light. Is to be used. FIG. 2 (b) shows a further enlarged portion near the focal point of the carbon dioxide laser beam 29 irradiated on the surface of the workpiece 5A. The carbon dioxide gas as the shield gas SG introduced from the shield gas introduction port 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 beam 29. The outer periphery of the conical carbon dioxide laser beam 29 between the spray nozzle 17 and the surface of the welding surface WS of the welding members 5A and 5B is an atmosphere 30 of carbon dioxide. Now, the generation process and the action of the plasma gas will be described. Carbon dioxide gas used as the shield gas SG has a characteristic of absorbing carbon dioxide laser light (wavelength 10.6 μm) very well when the temperature reaches 100 ° C. or higher. When carbon dioxide laser light (wavelength 10.6 μm) is irradiated from the nozzle 17 to the surface of the welding surface WS of the aluminum welding members 5A and 5B, even the aluminum welding members 5A and 5B having high reflectivity are 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 and heated. The temperature is 10
The carbon dioxide gas at 0 ° C. or higher absorbs the carbon dioxide laser beam (wavelength 10.6 μm) very well. Therefore, the carbon dioxide gas is further heated to become a plasma gas, and the high-temperature and high-pressure plasma gas region 33 becomes the welding member 5A. 5B is formed on the welding surface WS. The welding member 5 is irradiated with strong electromagnetic radiation from the high-temperature and high-pressure plasma gas region 33.
The surfaces of the welding surfaces WS of A and 5B are melted to form the molten pool 35. As described above, in the state where the weld 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 expressed as C.
By appropriately controlling with the NC device, continuous or intermittent welding can be performed along an arbitrary curve. Although the example of aluminum has been described in the embodiment, the present invention can be similarly applied to copper having a high reflectance similar to that of aluminum or silver whose surface is polished. Further, the laser processing apparatus 1 shown in FIG.
In the laser processing head 15, the shield gas SG from the injection nozzle 17 is configured to be injected onto the surface of the welding member 5 together with the carbon dioxide laser light 29.
As shown in FIG. 4, a shield gas injection nozzle 43 is provided on the side of the processing head 41 having the condenser lens 27, and this nozzle 4
In the laser processing apparatus configured to inject the shielding gas from 3 onto the surface of the welding member 5, the laser welding method of the high reflectivity material by the carbon dioxide gas laser according to the present invention can be performed. The laser processing apparatus for carrying out the laser welding method of the high reflectivity material by the carbon dioxide gas laser according to the present invention is not limited to the above-mentioned laser processing apparatus, but is a material moving type or an optical axis moving type. Any known laser processing apparatus can be used. As can be understood from the above embodiments, the contract
According to the invention described in claim 1, in welding of a material having a high reflectivity with respect to a carbon dioxide gas laser having a wavelength of 10.6 μm, the carbon dioxide gas laser light having a wavelength of 10.6 μm is absorbed by the carbon dioxide gas, and the welding is performed using the carbon dioxide gas. It can be performed in a stable state by radiation energy from carbon dioxide plasma generated by absorption of gas laser light.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example of a carbon dioxide gas laser processing apparatus used in a laser welding method for a high reflectivity material of 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 diagram of a laser welding method of a high reflectivity material according to the present invention. FIG. 3 shows another example of a carbon dioxide laser processing apparatus that can be used in the laser welding method of the high reflectivity material of the present invention. [Explanation of Symbols] 1 Optical axis moving laser processing apparatus 5A, 5B Welding member 15 Laser processing head 29 Carbon dioxide laser beam 33 Plasma gas region 35 Weld pool SG Shielding gas WS Welding surface

Claims (1)

(57) [Claims] [Claims] [Claim 1] In a carbon dioxide laser welding method using a shielding gas for shielding a welded portion from the atmosphere, a laser
-Laser irradiation capable of condensing and irradiating light on the welding surface of the welded part
Move the work head in the X-axis or Y-axis direction with respect to the welding member
It is provided so that positioning is possible, and carbon dioxide is added to the shielding gas.
This carbon dioxide is used as a phase with the carbon dioxide laser beam.
This high temperature plasma gas by interaction
Depending on the radiation energy radiated from the plasma gas region of
A high temperature and high pressure plasma gas region on the welding surface of the welding member.
A strong electromagnetic wave from the plasma gas region
A molten pool is formed on the weld surface by radiation, and the molten pool
In contrast, the laser processing head is moved in the X-axis or Y-axis direction.
The relative reflectance is 0.9 or more
A method of laser welding a high reflectivity material, comprising welding the above high reflectivity material.