JPS58119485A - Nozzle for laser working - Google Patents

Abstract

PURPOSE:To prevent inclusion of air into the work by providing an auxiliary flow passage through which a protecting gas passes near the end of a nozzle head on the side opposite from the work and expelling the air in the nozzle head by the negative pressure developed by the gaseous flow. CONSTITUTION:Laser light 2 is passed into the hole 2A of a nozzle head 6 and an auxiliary gas 7a is admitted through an aixiliary flow passage 7, and is blown to the surface of the work 4. In this stage, the flow of the gas 7 includes air therein and generates discoloration and welding defects in the work 4. Therefore, a gas flow passage 9 for flowing of a protecting gas 10 is mounted adjacently to the head 6, and the gas 10 is run so as to cross the laser light 2. Since the circumference of the gaseous flow is held under negative pressure, the air interposing in the head 6 is drifted toward the same and is discharged together with the gaseous flow to the outside. Thus the air is expelled from the surface of the work 4 and the surface is covered thoroughly with the gas 7b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser processing nozzle, and more particularly to a laser processing nozzle suitable for use in a condensing system using a mirror.

Laser light is coherent, so when it is focused with a mirror or lens, it produces a very small spot and a high energy density. Laser processing, which takes advantage of the characteristics of laser light, is attracting attention as a new processing method because it is capable of welding, cutting, and surface treatment at higher speeds than other processing methods, as well as processing high-melting point materials. . However, because a high energy density can be obtained, new problems arise that are not present in other conventional processing methods. This is a phenomenon in which the temperature of the part of the workpiece that is irradiated with the laser beam becomes extremely high, and part of the workpiece evaporates and scatters.

In the past, lenses were mainly used for condensing light, but mirror condensation is increasingly being used because lenses are damaged by flying debris and laser processing is frequently interrupted. An overview of laser processing using mirror focusing will be explained with reference to FIG. A laser beam 2 extracted from a laser oscillator 1 is focused by a condenser 3 and irradiated onto a workpiece 4 . At this time, a part of the workpiece evaporates and becomes scattered objects 5, which are scattered in all directions, and some of them even reach the mirror surface. When scattered objects adhere to the mirror surface,
Although it will not be damaged like a lens, the mirror surface will be damaged and its light-gathering performance will gradually decrease. As a countermeasure to this problem, a method has conventionally been used in which a protective gas is sprayed near the mirror surface to protect the mirror surface from flying objects, thereby blowing away the flying objects.

By the way, another problem in the case of mirror convergence is air being drawn into the processed surface. - As an example, a case will be explained in which stainless steel plates are welded using a carbon dioxide laser. If welding is performed in an air atmosphere, the welding surface will darken and internal welding defects will occur. For this purpose, an auxiliary gas such as argon gas or helium gas is sprayed onto the welding area, and the welding area is shielded with the auxiliary gas. The part that sprays such auxiliary gas is called a nozzle. Figure 2 shows a nozzle that has been conventionally used in Kagami Toko. A nozzle handle is attached substantially coaxially with the focused laser beam 2, and the nozzle handle is fixed to a support plate 8 to constitute a nozzle. There is a hole 2A on the inside of the nozzle handle through which the laser beam 2 passes, and the auxiliary gas 7a flows in from the auxiliary passage 7 provided at one end of the bag-shaped structure, and the auxiliary gas flows from the hole or groove at the lower end. 7b and is sprayed onto the surface of the workpiece 4,
leaks to the outside. At this time, the air 11 present in the hole 2AK inside the nozzle head through which the laser beam 2 passes is blown toward the hole 2AK by the flow of the auxiliary gas 7b, and the auxiliary gas 7b eventually becomes a flow containing air. For this reason, the weld is more relaxed than when welding in an air atmosphere, but
Discoloration and welding defects were inevitable.

An object of the present invention is to provide a laser processing nozzle that protects the mirror surface and prevents air from being drawn into the auxiliary gas by effectively blowing a protective gas to protect the mirror surface from flying objects. .

The present invention takes advantage of the fact that when gas flows at high speed, the surroundings of the gas flow become negative pressure, and blows the air that was conventionally drawn into the auxiliary gas, thereby preventing air from being drawn into the auxiliary gas. This is what I did.

An embodiment of the present invention will be described with reference to FIG. A gas flow path 9 for flowing a protective gas to protect the mirror surface of the focusing mirror from flying objects is installed adjacent to the nozzle, and when the protective gas 10 is flowed across the laser beam 2, the surrounding area of the gas flow is The pressure becomes negative, and the air 11 present in the nozzle is blown towards it.
Escapes with the protective gas stream. At this time, a part of the auxiliary gas 71) being blown onto the workpiece 4 is blown into the nozzle through the hole at the tip of the nozzle head 6, and flows out together with the air 11 present in the nozzle. As a result, the workpiece 4 in the vicinity of which the laser beam 2 is irradiated
0 surface air is excluded and completely covered with auxiliary gas.

The purpose of the crushing gas used at this time is to blow away the scattered objects from the workpiece 4 through the hole inside the nozzle head 6, and to generate negative pressure around the protective gas. It is sufficient to use an inexpensive gas such as On the other hand, if the gas flow path 9 is installed away from the nozzle upwards (by leaving a gap between the gas flow path 9 and the support plate 80), the air present in this gap will simply be blown into the negative pressure section. The air present in the nozzle is not blown away, so there is no effect.

It is important that the gas flow path 9 is installed adjacent to the nozzle.

FIG. 4 shows another embodiment of the present invention, in which the gas passage 9 through which the maintenance gas flows is brought closer to the nozzle tip, and the protective gas is adjusted to the extent that the diameter of the laser beam is smaller than in FIG. 3. Since the volume of the space from the gas flow path 9 to the workpiece is reduced, the absolute amount of intervening air is reduced and the air can be easily removed. Moreover, as shown in FIG.
A hole for 0a is made and the protective gas 10 flows out diagonally.
By making the hole b, it becomes easier to align the nozzle including the gas flow path 9.

According to the present invention, it is possible to protect the mirror surface from objects flying from the surface of the workpiece, and at the same time, there is an effect that air can be prevented from being drawn into the workpiece.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram explaining the outline of laser processing using mirror focusing, Figure 2 is a side sectional view of a nozzle for conventional laser processing,
3 and 4 are side sectional views of a nozzle according to the present invention.

Claims (1)

[Claims] 1. A nozzle head that has a hole through which the laser beam passes inside and is arranged in correspondence with the workpiece, and an auxiliary passage provided in the nozzle head for spraying auxiliary gas onto the workpiece, which is suitable for the workpiece. A nozzle for laser processing, characterized in that a gas flow path through which a protective gas flows is formed near the end of the nozzle head on the opposite side.