JPH042353B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a processing head for laser welding, and in particular to improving the welding performance thereof.

[Conventional technology]

Laser welding, along with electron beam welding, has recently been put into practical use as a high-efficiency, high-quality welding method that uses a high-energy density heat source.

As is well known, laser welding allows deep penetration welding due to the drilling action of the beam, and it is said that penetration welding can be performed in one layer without the need for beveling if the plate thickness is approximately 10 mm. . In welding using this deep penetration mechanism, when the laser output increases and the target plate thickness also increases, the amount of metal vapor called plasma increases in the beam irradiation area during welding, and this absorbs the laser beam or This may cause the penetration to deteriorate significantly. That is, as shown in FIG. 2a, the bead 30 produced by the laser beam has a so-called wine cup shape with a wide upper part. On the other hand, if this plasma is removed by some means, a bead 30 with extremely narrow bead width and deep penetration can be obtained as shown in FIG. 2b.

Conventionally, a so-called side nozzle method has been used as a method for removing plasma.

FIG. 3 is a block diagram showing such a conventional side nozzle type laser welding processing head, in which a side nozzle 2 for ejecting a side gas 4 is provided along with the laser processing head 1.

In this case, the workpiece (hereinafter referred to as the work) 3 moves in the direction of the side nozzle 2, so welding progresses to the left, and the side gas 4 is blown from behind the molten pool (not shown). It becomes like this.

[Problem that the invention seeks to solve]

The conventional processing head for laser welding is configured as described above, and the method of blowing the side gas 4,
That is, depending on the spraying position, spraying angle, etc., the penetration depth etc. change significantly, and it is very difficult to control the penetration depth to an optimum state. That is, welding speed,
Depending on the laser output, the material of the workpiece 3, etc., it is necessary to delicately control the blowing position of the side gas 4 (the blowing height l and the blowing angle θ). There was a problem in that when the distance h between the steel and the steel plate changed, the penetration depth suddenly changed.

This invention was made to solve the above-mentioned problems, and the purpose is to provide a device that allows stable plasma removal without fluctuations in penetration depth depending on the mounting position of the side nozzle. shall be.

[Means for solving problems]

The processing head for laser welding according to the present invention includes a center nozzle that irradiates a laser beam and ejects a plasma removal gas coaxially with the optical axis of the laser beam, and a center nozzle that is provided around the center nozzle and that is attached to a workpiece. It is equipped with a shield nozzle that spouts shielding gas that shields the processing position from the atmosphere.

[Effect]

In the processing head according to the present invention, since the plasma removal gas flows through the center nozzle that emits the laser beam, there is no directionality and the aim position tolerance is increased. Furthermore, since the molten pool is protected by the shield nozzle, deep penetration can be ensured.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional configuration diagram showing the main parts of a processing head for laser welding according to an embodiment of the present invention. A center nozzle 121 ejects plasma removal gas coaxially with the shaft, 121 is a plasma removal gas such as He,
A gas inlet 122 is a nozzle hole of the center nozzle 12 that supplies an inert gas such as Ar to the center nozzle 12. According to experimental results, if the diameter is 3 mm or less, the plasma (not shown) generated directly under the laser beam 5 can be effectively used. I was able to eliminate it. Furthermore, even if the distance h between the machining head 1 and the workpiece 3 changes somewhat, the effect remains the same and the range of application is significantly expanded. A shield nozzle 13 is provided around the center nozzle 12 and blows out a shielding gas that shields the processing position of the workpiece 3 from the atmosphere. For example, the shield nozzle 13 protects the molten metal from the atmosphere and ensures deep penetration. 131 is a shielding gas (e.g. He,
Inert gas such as Ar or in some cases CO ₂
If there is only one shield gas inlet, that is, only one gas inlet, the gas will not be distributed evenly around the center nozzle 12, and the shield It becomes defective. Therefore, in the case of the above embodiment, the filter 132 for shielding gas rectification is
is installed to ensure a homogeneous gas flow. As a result of considering heat resistance and the like, it was found that this filter 132 was effectively made of stainless steel mesh or sintered metal.

With this structure of the processing head 1, it is possible to always obtain a stable deep penetration beat (Fig. 2b) even if the welding conditions or the distance h between the processing head 1 and the workpiece 3 vary slightly. Now I can do it. Furthermore, with conventional side nozzle type machining heads, it was necessary to change the position of the side nozzle each time the welding direction changed, but since the machining head of the present invention has an axially symmetrical structure, there are no restrictions due to direction. No harm will be caused and the scope of application will be expanded.

〔Effect of the invention〕

As described above, according to the present invention, a center nozzle is provided that irradiates a laser beam and spouts plasma removal gas coaxially with the optical axis of the laser beam; The processing head for laser welding is equipped with a shield nozzle that ejects shielding gas to shield it from the atmosphere, making it easy to perform high-quality welding in all directions, increasing target position tolerance, and enabling stable plasma removal. It became.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the main parts of a processing head for laser welding according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a weld pool formed on a workpiece by laser light, and FIG. 1 is a configuration diagram showing a conventional laser welding processing head. DESCRIPTION OF SYMBOLS 1... Processing head, 3... Workpiece, 5... Laser light, 12... Center nozzle, 121... Nozzle hole, 13... Shield nozzle, 132... Filter. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A center nozzle that irradiates a laser beam and spouts plasma removal gas coaxially with the optical axis of the laser beam, and a center nozzle that is provided around the center nozzle and that controls the processing position of the workpiece. A processing head for laser welding equipped with a shield nozzle that spouts shielding gas to shield from the atmosphere. 2. The processing head for laser welding according to claim 1, wherein the shield nozzle is provided with a filter for rectifying the shield gas. 3. The processing head for laser welding according to claim 1 or 2, wherein the diameter of the nozzle hole of the center nozzle is 3 mm or less.