JPS61229491A - Processing head for laser welding - Google Patents

Abstract

PURPOSE:To remove stably plasma by providing a center nozzle which irradiates laser light and ejects a plasma-removing gas coaxially with the optical axis of the laser light and providing a shielding nozzle around the center nozzle. CONSTITUTION:The center nozzle 12 irradiates the laser light 5 and ejects the plasma-removing gas in the state coaxial with the optical axis of the laser light 5. A gas inlet 121 supplies an inert gas to the nozzle 12. the shielding nozzle 13 is provided around the nozzle 12 and ejects the shielding gas which shields the processing position of a work 3 against the atm. to protect the molten metal against the atm. and to assure deep penetration. A filter 132 for regulating the flow of the shielding gas is provided to maintain the uniform flow of the gas. The always stable deep penetration bead is obtd. in spite of a minor fluctuation in welding conditions and the distance (h) between a processing head 1 and the work 3 by constructing the head 1 in the above- mentioned manner.

Description

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

[Conventional technology]

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

As is well known, in laser welding, deep penetration welding that relies on the perforating action of the beam is the 5R rudder.

It is said that if the plate thickness is about 10 mm, penetration welding can be performed in one layer without the need for beveling. When welding with a deep penetration mechanism, the laser output becomes larger and the target plate thickness also becomes larger.

During welding, metal vapor called plasma is generated in the beam irradiation area, and this metal vapor absorbs or diverges the laser beam, which can significantly impair penetration. That is.

As shown in FIG. 2(a), the beat (welding ability) produced by the laser beam is wide at the top and has the shape of a so-called wine cup. On the other hand, if this plasma is removed by some means, a beat ω with an extremely narrow beat width and deep penetration can be obtained as shown in FIG. 2('b).

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

FIG. 3 is a configuration diagram showing such a conventional side nozzle type laser welding processing head, in which a side nozzle (2) for ejecting side gas (4) is attached to the laser processing head (1). Equipped.

In this case, the workpiece (hereinafter referred to as the work) (3) is
Since it moves in the direction of the side nozzle (2), the bath contact progresses to the left and 1. Side gas (41 is weld pool (not shown)
It will start blowing from behind.

[Problem that the invention seeks to solve]

A conventional laser welding processing head is configured as described above and uses shielding gas (41 blowing method).

That is, the penetration depth changes significantly depending on the spraying position, spraying angle, etc., and it is extremely difficult to control it to the optimum state. i.e. welding speed.

Depending on the laser output, the material of the workpiece (3), etc., it is necessary to delicately control the blowing position (blowout height t and blowing angle θ) of the side gas (4). ) and the workpiece (31) changes,
There was a problem that the penetration depth changed suddenly.

This invention was made in order to solve the above-mentioned problems.The installation of the side nozzle does not cause fluctuations in the penetration depth depending on the position, and it is possible to stably remove the burr from the burr. The purpose is to obtain.

[Means for solving problems]

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

[Effect]

In the processing head according to the present invention, since the plasma removal gas is caused to flow through the center nozzle that emits the laser beam, there is no directionality, and the positional tolerance for alignment 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.

The first @ 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.

In the figure, all denotes a lens mount, and α denotes a center nozzle that emits a laser beam (5) and spouts plasma removal gas coaxially with the optical axis of the laser beam.

(1211) Plasma removal gas, for example, an inert gas such as He or Ar, is supplied to the gas inlet of the center nozzle (1), (1221) is supplied to the nozzle hole of the center nozzle az.

According to the experimental results, if the diameter is 3n or less, the laser beam (5)
Lyr plasma (not shown) generated directly below could be effectively eliminated. Moreover, the processing head (Rito Work (3)
Even if the distance from 1 changes slightly, the effect remains the same and the range of application is significantly expanded. αJFi center nozzle (
It is a shield nozzle that is provided around I2 and blows out a shielding gas that shields the processing position of the workpiece (3) from the atmosphere.1For example, it protects molten metal from the atmosphere and ensures deep penetration. (131) is a shielding gas (e.g. He,
Inert gas such as Ar.

Depending on the situation, 002 is also possible) with shield nozzle 0.
If there is only one shield gas inlet, that is, only one gas inlet, the gas will not be evenly distributed around the center nozzle α2, resulting in poor shielding. Therefore, in the case of the above example,
A filter (132) for shielding gas rectification is provided to make the gas flow homogeneous. This filter (
132), stainless steel mesh or sintered metal were found to be effective in consideration of heat resistance, etc.

Such a processing head (from K to have the structure of 11,
Even if the welding conditions or the distance between the machining head 0) and the workpiece (3) change somewhat, it is now possible to always obtain a stable deep penetration beat (in Fig. 2).

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 this invention has an axisymmetric structure, there are no restrictions due to direction. There is no problem and the scope of application is expanded.

[Effects of the invention]

As described above, according to the present invention, a center nozzle is provided around the center nozzle that emits a laser beam and also spouts out a plasma removal gas coaxially with the optical axis of the laser beam, and a center nozzle is provided around the center nozzle, and the center nozzle is provided at the processing position of the workpiece. The laser welding process is equipped with a shield nozzle that ejects shielding gas to shield it from the atmosphere, making it easy to perform high-quality bath welding in all directions, increasing target position tolerance, and ensuring stable plasma removal. is possible.

[Brief explanation of the drawing]

FIG. 1 is a 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 sectional view showing a weld pool formed on a workpiece by the laser beam, and FIG.
The figure is a configuration diagram showing a conventional laser welding processing head. +1)... Processing head, (31... Workpiece, (5
)...Laser light. a2... Center nozzle, (121)... Nozzle hole, c+s... Shield nozzle, (132)
···filter.

Claims (3)

[Claims] (1) A center nozzle that emits a laser beam and spouts plasma removal gas coaxially with the optical axis of the laser beam, and is provided around the center nozzle to shield the processing position of the workpiece from the atmosphere. A processing head for laser welding equipped with a shield nozzle that spouts shield gas. (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.