JP2600323B2 - Laser processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a method for laser processing a metal using an assist gas during laser processing.

[Prior art]

Laser processing is a thermal processing method in which laser light output from a laser oscillator is focused on a processing surface by an optical portion such as a lens, and cutting and welding are performed using high-density energy at this time. In this method, a high-pressure assist gas is injected into a processing portion in order to remove a melt of the workpiece generated by the energy. For example, when laser cutting metals such as aluminum, stainless steel, and titanium, a method using an oxidizing gas containing oxygen as an assist gas is adopted due to the relationship between cutting ability (cutting speed and material thickness). ing. The reason for this is that, by blowing an oxidizing gas onto the cut portion heated by the irradiation of the laser beam, the oxidation reaction is promoted and the cutting ability is improved. However, as a result of using the oxidizing gas, oxidation of the cut portion due to the oxidizing action is unavoidable, and there are problems such as formation of an oxide film on the cut surface and burning around the cut portion. As an example of this, when butt welding materials having an oxide film formed thereon, there is a disadvantage that welding defects due to poor fusion occur due to the effect of the oxide film adhered to the cut surface. Therefore, in order to solve these problems, although the cutting ability is reduced, the degree of oxidation is extremely small, and
Argon, which shows a gloss on the cut surface and provides high quality cutting
Non-oxidizing gases such as helium and nitrogen are employed as assist gases. Here, the difference in the cutting ability due to the difference in the assist gas will be specifically described. For example, when cutting stainless steel with a laser output of 1 Kw, when using an oxidizing gas as the assist gas, the thickness of the material can be cut to about 9 mm, but when using a non-oxidizing gas, 3 mm can be used. The degree is the limit. The cutting speed in this cutting is the same in both cases. By the way, when a 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 the dross is much stronger than when an oxidizing gas is used. Is difficult to remove. For this reason, various measures have been taken to increase the pressure of the assist gas injected to the cutting portion or to adjust the focal position of the laser beam to prevent dross from being generated.

[Problems to be solved by the invention]

As described above, in the conventional laser processing method, when cutting capability is required, processing is performed using an oxidizing gas as an assist gas, and when a glossy and high-quality cut surface is required, Processing is performed using a non-oxidizing gas as an assist gas. Therefore, when an oxidizing gas is used as an assist gas, there is a problem that an oxide film is formed on a cut surface or burning occurs around a cut portion. There was a limit to the thickness of possible materials. The present invention has been made in order to solve the above problems, and is not limited by the thickness of the material, and has a problem that an oxide film is formed on a cut surface or burning occurs around a cut portion. It is an object of the present invention to obtain a laser processing method free from defects.

[Means for Solving the Problems]

The laser processing method according to the present invention is a method of laser processing a metal using an assist gas, in which a plurality of piercing holes are formed in advance in the metal, and the piercing holes are used as start positions to cut a desired figure. In the method, an oxidizing gas is used as an assist gas when forming the piercing holes, and a non-oxidizing gas is used as an assist gas when cutting the desired figure. Further, a laser processing method according to another invention of the present invention,
A method of laser processing a metal using an assist gas, wherein a plurality of piercing holes are formed in advance in the metal, and a plurality of desired graphic processing is performed on the metal. Small and
A pre-cut hole larger than the piercing hole is machined, and each of the desired figures is processed with the pre-cut hole as a start position. When forming the pre-cut hole, an oxidizing gas is used as an assist gas to cut the desired figure. During processing, a non-oxidizing gas is used as an assist gas.

[Action]

According to the present invention, holes are formed in all the piercing portions in advance using an oxidizing gas, and thereafter, the holes are switched to a non-oxidizing gas and the holes in the piercing portions that have already penetrated are started according to a predetermined processing program. Cut each figure as a position. According to another aspect of the present invention, for each desired figure,
A pre-cut hole smaller than the desired figure and larger than the piercing hole is processed by using an assist gas composed of an oxidizing gas. It is processed using an assist gas consisting of

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described. For convenience of description, first, a principle concept thereof will be described. As described above, when a metal material such as aluminum, stainless steel, or titanium is cut by a laser beam, an assist gas is blown to the cut portion in order to blow off a melt generated at the cut portion. The assist gas is generally injected from a nozzle provided at the tip of a processing head that collects laser light and irradiates the processing surface with the laser light. Next, a method of cutting a metal material in the above configuration will be described. First, as a first stage of processing, a cutting process is performed by irradiating a laser beam onto a processing surface of a material using a so-called oxidizing gas such as an oxygen gas or a gas containing oxygen as an assist gas and irradiating a laser beam. . In this cutting, the metal and the oxidizing gas violently react chemically to generate heat near the cut portion, and the cut portion is melted by the heat of the oxidation reaction and the laser beam. Then, cutting is performed by blowing off the melt with an assist gas. Since an oxidizing gas is used as the assist gas on the cut surface after the cutting of the predetermined shape as described above, an oxide film is naturally formed. As described above, the use of the oxidizing gas promotes the oxidation reaction, so that a thick material can be cut and the cutting speed increases. Next, as a second step, the assist gas is switched to a non-oxidizing gas such as helium or nitrogen after the cutting is completed. Then, a non-oxidizing gas is jetted onto the cut surface of the material cut in the first stage processing, and a small amount of laser light is irradiated to perform processing of a predetermined shape. By performing this processing once or, in some cases, several times, the cut surface of the cut material is gradually shaved due to a small amount of laser light to be irradiated, and an oxide film formed on the cut surface is eventually formed. Will also be removed. Since the metal material cut by such a method can obtain a high-quality glossy material without forming an oxide film on the cut surface, for example, poor fusion even when the above materials are butt-welded. Does not occur. Here, a case of cutting a figure as shown in FIG. 1 will be described. As in the above, as the first stage of processing, laser cutting is performed using an oxidizing gas as an assist gas.
At this time, several places of the graphic to be processed (3 in the example of FIG. 1).
Is cut into a predetermined shape while applying a microjoint (1) so that the workpiece (2) after cutting does not fall. Then, after the cutting with the oxidizing gas is completed, the assist gas is switched to a non-oxidizing gas, and the cutting is performed again by jetting a predetermined laser beam while jetting the cutting groove (3) formed as described above. . In this cutting, the oxide film adhering to the cut surface is removed, and the microjoint (1) applied in several places is cut relatively easily because the remaining portion is minute. . By the way, in general laser processing, when cutting a figure, the cutting is started not from the end of the material but from the center. In this case, it is necessary to make an initial hole in the start portion before starting the cutting, and the work of opening the initial hole is usually called piercing. The above is the description of the principle concept of the present invention. Next, an embodiment of the present invention to which this concept is applied will be described. That is, FIG. 2 is a view for explaining an embodiment of the present invention. In FIG. 2, graphics (4) of various shapes to be cut are shown by dotted lines, and FIG. The black dots represent the piercing section (5). As described above, when performing a plurality of piercings, holes are formed in all the piercing portions (5) using an oxidizing gas in advance, and then the piercing is performed by switching to a non-oxidizing gas according to a predetermined processing program. Each figure (4) is cut using the hole of the piercing part (5) as a start position. In this method, since the assist gas needs to be switched only once, it is possible to efficiently cut a large number of figures (4). The initial hole formed at the time of piercing is as small as about 0.2 mm in diameter, and in some cases, the following inconvenience may occur. In other words, the piercing and the cutting of the figure (called the main cutting) are performed in different processes (for example, 2
In the case of using one laser processing machine), it is difficult to position the material after the piercing is completed when setting the material on the main cutting laser processing machine. Further, when piercing and main cutting are performed by a single laser processing machine and by a series of programs, slight thermal deformation occurs in the material in the process of main cutting, so the processing was shifted to the next processing section. Sometimes the starting parts of the processing do not coincide. Therefore, the following can be considered as a method of avoiding these problems. That is, a method is provided in which a hole smaller than the figure to be cut and larger than the initial hole is provided as a preliminary cut hole. The pre-cut hole may have a diameter of about 1 to 2 mm, and is provided at the center of the figure to be cut, like the initial hole. Drilling is performed in the same manner as in the piercing described above. As a result, when the pre-cut hole is processed using a separate laser processing machine and the main cut is performed, or even when the material is thermally deformed during the main cut, the pre-cut hole serving as the starting position of the cut is pierced. Since the size of the initial hole is several times larger than that of the initial hole, the cutting can be continued without any problem. In the processing method described above, cutting can be performed in a short time even with a thick material, and the oxide film on the cut surface is removed, so that it is as if a non-oxidizing gas was used in the entire cutting process. In addition, it is possible to obtain a high quality cutting state that is non-oxidized and glossy.

【The invention's effect】

As described above, according to the present invention, when laser processing a metal using an assist gas, a method of forming a plurality of piercing holes in the metal in advance and performing cutting processing of a desired figure with the piercing holes as starting positions. In the above method, an oxidizing gas is used as an assist gas when forming the piercing hole, and a non-oxidizing gas is used as the assist gas when cutting the desired figure. Therefore, there is an advantage that efficient processing can be performed even when a large number of figures are cut. According to another aspect of the present invention, when laser processing a metal using an assist gas, a method of forming a plurality of piercing holes in the metal in advance and performing a plurality of desired graphic processing on the metal, For each desired figure, a pre-cut hole smaller than the desired figure and larger than the piercing hole is machined, and the desired figure is processed with the pre-cut hole as a start position. Since an oxidizing gas is used, and a non-oxidizing gas is used as an assist gas at the time of cutting the desired figure, even if the metal is thermally deformed during the main cutting, a preliminary cutting hole serving as a starting position of cutting is formed. The problem is that the start part of the processing does not match when moving to the next processing part because it is larger than the initial hole by piercing But there is an advantage that can be eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view for explaining the principle of the present invention, and FIG. 2 is an explanatory view of a laser processing method according to an embodiment of the present invention. In the figure, (1) is a micro joint, (2) is a workpiece, (3) is a cut groove, (4) is a figure, and (5) is a piercing portion. In the drawings, the same reference numerals indicate the same parts.

Claims (2)

(57) [Claims] 1. A method of laser machining a metal using an assist gas, wherein a plurality of piercing holes are formed in advance in the metal, and a desired figure is cut with each of the piercing holes as a start position. A laser processing method, wherein an oxidizing gas is used as an assist gas when forming the piercing hole, and a non-oxidizing gas is used as an assist gas when cutting the desired figure. 2. A method of laser processing a metal using an assist gas, wherein a plurality of piercing holes are previously formed in the metal, and a plurality of desired graphic processings are performed on the metal. A pre-cut hole smaller than the desired figure and larger than the piercing hole is processed, and each desired figure is processed with the pre-cut hole as a start position. When forming the pre-cut hole, an oxidizing gas is used as an assist gas. A laser processing method using a gas, wherein a non-oxidizing gas is used as an assist gas when cutting the desired figure.