JPH0263693A - Laser beam machining method - Google Patents

Abstract

PURPOSE:To obtain the laser beam machining method which is not restricted by thickness of a material by using oxidizing assist gas in a first stage of working and using non-oxidizing assist gas in a second stage of the working. CONSTITUTION:As a fist stage of working, laser beam cutting is executed by using oxidizing gas containing oxygen as assist gas, and in this case, cutting of a prescribed shape is executed, performing a micro-joint 1 so that a work 2 after cutting does not drop down to several parts of a graphic to be worked. Subsequently, the assist gas is switched to non-oxidizing gas which does not contain oxygen, and while jetting it to a cutting groove 3 which is formed, cutting is executed again by in radiating a prescribed laser light. By this cutting, an oxide film adhering to a cutting plane is eliminated, and also, the micro-joint which is performed to several parts is also cut comparatively easily since its residual part is very small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of processing metal using an assist gas during laser processing.

[Conventional technology]

Laser processing is a thermal processing method in which laser light output from a laser oscillator is focused onto a processing surface using an optical part such as a lens, and cutting, welding, etc. are performed using the high-density energy at this time.

In this method, a high-pressure assist gas is injected into the workpiece in order to remove the molten material of the workpiece generated by the energy.

For example, when laser cutting metals such as TLF, aluminum, stainless steel, and titanium, a method using an oxidizing gas containing oxygen as an assist gas is adopted due to the cutting ability (cutting speed, material thickness). has been done. The reason for this is that by spraying the oxidizing gas onto the cut portion heated by laser light irradiation, the oxidation reaction is promoted and the cutting ability is improved.

However, as a result of using an oxidizing gas, oxidation of the cut portion due to oxidation cannot be avoided, resulting in problems such as formation of an oxide film on the cut surface and generation of burnt spots around the cut portion. As an example of this, when materials on which oxide films have been formed are butt-welded, there is a problem in that welding defects occur due to poor fusion due to the influence of the oxide films adhering to the cut surfaces.

Therefore, in order to solve these problems, we decided to use argon, which reduces the cutting ability but has an extremely low degree of oxidation and produces a glossy cut surface, resulting in commercial quality cuts.
Non-oxidizing gases such as helium and nitrogen are used as assist gases.

Here, the difference in cutting ability due to the difference in assist gas will be specifically described.

For example, when cutting stainless steel with a laser output of 1 kW, when an oxidizing gas is used as the assist gas, it is possible to cut the material up to a thickness of about 91 mm, but when a non-oxidizing gas is used, the thickness of the material can be cut to about 8 mm. The fighting culm level is the limit. Note that the cutting speed in this cutting is the same for both.

By the way, when non-oxidizing gas is used as an assist gas for metal cutting, dross and burrs tend to adhere to the back surface of the cut surface, and moreover, dross is much more likely to adhere to the back surface of the cut surface than when using oxidizing gas. It is strong and has a point that makes it difficult to remove. To this end, measures have been taken to prevent the generation of dross by increasing the pressure of the assist gas injected to the cut portion and adjusting the focal position of the laser beam.

[Problem to be solved by the invention]

As described above, since the conventional laser processing method uses a non-oxidizing gas as the assist gas, there is a limit to the thickness of the material that can be processed.

This invention was made to solve the above-mentioned problems, and aims to provide a laser processing method that is not limited by the thickness of the material.

[Means to solve the problem]

In the laser processing method according to the present invention, an oxidizing assist gas is used in the first stage of processing, and a non-oxidizing 7-st gas is used in the second stage of processing.

[For production]

In this invention, the oxidizing reaction is promoted by the oxidizing assist gas, and processing is performed in a short time, and the non-oxidizing assist gas forms a non-oxidized processed part.

[Example of invention]

Hereinafter, one embodiment of this invention will be described.

As mentioned above, when cutting metal materials such as aluminum, stainless steel, titanium, etc. with a laser beam, an assist gas is blown onto the cut part to blow away the molten material generated at the cut part.

This assist gas is generally injected from a round nozzle installed at the tip of a processing head that focuses laser light and irradiates it onto the 11r+ work surface.

Next, a method of cutting the material of the structure I as described above will be explained. As the first stage of processing, #
A so-called oxidizing gas such as an oxidizing gas or a gas containing oxygen is used as an assist gas and is injected from a nozzle at the h11th time of the material while irradiating the material with laser light to perform the cutting process.

During this cutting, the metal arm and the oxidizing gas undergo a violent chemical reaction, generating heat near the cut portion, and the cut portion is melted by the heat of the oxidation reaction and the laser beam. Cutting is then performed by blowing away this molten material with assist gas. The cut surface cut into a predetermined shape as described above has an oxidation reaction that accelerates the oxidation reaction by using an oxidizing gas, making it possible to cut thick materials and increase the cutting speed. As mentioned above, it is faster.

Next, the assist gas is switched to a non-oxidizing gas such as helium or nitrogen to the trowel which has completed the above-mentioned cutting after the second step. Then, non-oxidizing scum is injected onto the cut surface of the material cut in the first stage of processing, while a small amount of laser light is illuminated in the dark to process the material into a predetermined shape. This 7JII
By performing I once or several times in some cases, the cut surface of the material after cutting is gradually scraped by the irradiated laser beam, and eventually the oxide film formed on the cut surface is also removed. It will be removed. The metal material cut by this method does not form an oxide film on the cut surface, and it is possible to obtain a shiny, high-mass material.
For example, even if the above-mentioned materials are butt-welded, no fusion failure will occur.

Here, when cutting the figure shown in H4,
I will explain. In the same way as above, as the first step of processing, laser cutting is performed using the assist gas lζ1 agglutinating gas, but at this time, cuts are made at several locations (8 locations in the example in Figure 1) of the figure to be machined. Cutting into a predetermined shape is performed while performing a microjoin (1) to prevent the subsequent workpiece (2) from falling. After cutting with the oxidizing gaff is completed,
The assist gas is switched to a non-oxidizing gas, and while being injected into the cutting groove (3) formed by the above-mentioned gas, a predetermined laser beam is irradiated to perform circular cutting. This cutting removes the oxide film adhering to the IJ and the cut surface, and also cuts the microjoins (1) that were made in several places relatively easily as the remaining portions are minute. will be done.

By the way, in general laser processing, when cutting a figure, the cutting is not started from the edge of the material;
Cutting starts from the center. In this case, it is necessary to make an initial hole in the starting part before starting cutting ('/
J' is present, and the work of opening this initial hole is called normal via-singing. Hereinafter, the biting and handling method will be explained with reference to FIG. In the figure, figures (4) of various shapes to be cut are indicated by A and M, and the black dots in the figure represent the via cutting parts (5). In this way, when performing multiple via threading, first use oxidizing gas to make holes in all the via threading parts (5), and then switch to non-oxidizing gas and follow the predetermined cutting program to drill holes that have already been penetrated. The respective shapes (4) are cut using the holes of the via threading parts (5) as starting positions. With this method, the assist gas only needs to be switched once, so even when a large number of figures (4) are to be cut, it is possible to cut them efficiently.

However, the initial hole formed in the via hole is very small, with a diameter of about 0.2 fl, and depending on the case, the following problems may occur.

In other words, when piercing and cutting the shape (referred to as main cutting) are performed in separate processes (for example, when using two laser processing machines), when setting the material after piercing into the laser processing machine for main cutting, Difficult to position. In addition, one laser processing machine can perform the via cutting and main cutting.
In addition, when machining is performed using a series of programs, a slight amount of thermal deformation occurs in the material during the main cutting process, so that the start points of machining do not match when moving to the next machining section. Therefore, the following methods can be considered to avoid these problems. That is, this is a method in which a preliminary cutting hole 7 is provided that is smaller than the figure to be cut and larger than the initial hole.

This pre-cut hole has a diameter of about 1 to 2!0 mm (similar to the initial hole, it is provided in the center of the figure to be cut, and the hole is made in the same manner as the via-cutting described above. As a result, even if the pre-cut hole machining and the main cutting are performed using separate laser processing machines, or even if thermal deformation occurs in the material during the main cutting, the pre-cut hole, which is the starting position of the cutting, can be cut by bead cutting. Since it is several times larger than the initial hole, it is possible to continue cutting without interruption.

In the processing method described above, it is possible to cut even fragile materials in a short time, and the oxide film on the cut surface is removed. This results in a high-quality, non-oxidized, glossy cut like the one used.

〔Effect of the invention〕

As described above, according to the present invention, as the assist gas,
Laser JD machining is performed using oxidizing gas in the first stage of machining and non-oxidizing gas in the second stage of machining1.
This has the effect of providing a laser processing method that is not restricted by the thickness of the material.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a four-metal machining method according to one embodiment of the present invention, and FIG. 2 is an explanatory diagram of a laser machining method according to another embodiment of the present invention. In the figure, (1) is a microjoint, (2) is a workpiece, (3) is a cutting groove, (4) is a figure, and (5) is a bij'.
This is the Tshinge Department. In addition, in the figures, 1 and 1 same numbers indicate the same parts.

Claims (1)

[Claims] In the method of laser processing metal using an assist gas, an oxidizing gas containing oxygen is used as the assist gas in the first stage of laser processing, and a non-oxidizing gas containing no oxygen is used in the second stage of laser processing. A laser processing method characterized in that it is used.