JPH01321086A - Laser beam cutting method - Google Patents

Abstract

PURPOSE:To improve and stabilize laser beam cutting quality by mixing different kind of gas in O gas and changing the rate of O purity according to a cutting shape of a material to be cut to perform laser beam cutting thereon. CONSTITUTION:A gas bomb 9 of N gas, etc., of the different kind is connected to an assisting gas supplying device 8 of a laser beam machine 3 together with an O gas bomb 7. The assisting gas having a large quantity of N gas mixed in the O gas is supplied to a fine cutting 11 part and a sharp edge 10 part of the material 5 to be cut by the gas supplying device 8 and laser beam cutting is performed. By this method, since the O purity is adjusted low at the parts with the complicated cutting shapes, the oxidation reaction is suppressed. Accordingly, melting-down due to thermal saturation at the fine cutting parts 10 and 11 is reduced and the cutting quality is improved and stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a laser cutting method suitable for use when cutting a workpiece such as a sheet metal part using a laser beam.

[Prior Art] FIG. 4 is a schematic configuration diagram showing a general laser processing apparatus used when performing conventional laser cutting processing means. In the figure, 1 indicates a laser oscillator that oscillates a laser beam 2; 3 is a laser processing machine, 4 is a processing head attached to the laser processing machine 3, 5 is a workpiece, 6 is a processing table that supports the workpiece 5, and 7 is an oxygen tank that stores oxygen gas used as an assist gas. A gas cylinder 8 is an assist gas supply device that supplies oxygen gas from the oxygen gas cylinder 7 to the processing head 4.

Next, conventional laser cutting processing means performed using the laser processing apparatus shown in FIG. 4 will be explained. A laser beam 2 oscillated by a laser oscillator 1 is guided to a laser processing machine 3, focused into a small spot diameter by a processing head 4, and irradiated onto a workpiece 5 supported on a processing table 6 to form a laser beam 2 to be processed. The object 5 is cut. At this time, oxygen gas is supplied to the processing head 4 by the assist gas supply device 8 as an assist gas for cutting.

[Problems to be Solved by the Invention] Conventional laser cutting is performed as described above, and when the workpiece 5 to be cut is a fully bent part, oxygen gas is used as the assist gas. In areas where the cutting speed is slow, such as sharp edges and fine cuts, the oxidation reaction caused by the oxygen gas blown onto the processed area tends to be excessive, causing the sharp edges and fine cuts to heat up. As a result, cutting quality was unstable and accuracy was reduced. For this reason, the laser output and output form are restricted depending on the shape of the workpiece 5, and it is necessary to use an expensive laser oscillator equipped with a device capable of generating pulsed output.

For example, FIG. 5 is an explanatory diagram showing an example of laser cutting processing using a conventional laser cutting processing means, and FIG. 6(a),
(b) is a characteristic diagram showing an example of the relationship between the sharp edge angle θ and the melting loss length. As shown in FIG. 5.6, the fine cut portion 11 of the workpiece 5 and the sharp edge portion 10 during acute angle cutting become thermally saturated due to the shape effect, and undergo an oxidation reaction with oxygen gas 7, which is an assist gas. The reaction heat caused a melted part (shaded part) 12 to occur, making it impossible to perform a good cutting process. For this purpose, the workpiece 5
In the sharp edge part 1o and the fine cutting part 11, there were problems such as the need to reset processing conditions such as output and output form so as not to cause melt damage.

This invention was made to solve the above-mentioned problems, and it is possible to stabilize the cutting quality even when cutting sharply-angled parts of sheet metal parts with complex shapes, and shorten the time required to set the processing conditions. The purpose is to obtain a laser cutting processing method.

[Means for Solving the Problems] The laser cutting method according to the present invention mixes other types of gas into oxygen gas, which is an assist gas, to adjust the oxygen purity ratio according to the cutting shape of the workpiece. It is something that changes.

[Function] In the laser cutting method of the present invention, the oxidation reaction is suppressed by adjusting the oxygen purity of the oxygen gas that is the assist gas. This also reduces melting loss due to thermal saturation, even when cutting at sharp angles.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1st
The figure is a schematic configuration diagram showing a laser processing device used to implement a laser cutting method according to an embodiment of the present invention. In the figure, the same parts as those in the device shown in FIG. However, the explanation thereof will be omitted.

In FIG. 1, reference numeral 9 denotes a nitrogen gas cylinder that stores nitrogen gas, and an appropriate amount of nitrogen gas in the nitrogen gas cylinder 9 is taken out by an assist gas supply device 8 and mixed with the oxygen gas from the oxygen gas cylinder 7. It has become.

Next, a laser cutting method performed using such a laser processing apparatus will be described. As in the conventional case, a laser beam 2 oscillated by a laser oscillator 1
is guided to a laser processing machine 3, focused into a small spot diameter by a processing head 4, and irradiated onto a workpiece 5 supported on a processing table 6, thereby cutting the workpiece 5.

At this time, in the method of this embodiment, the assist gas supply bag [
8, an appropriate amount of nitrogen gas is mixed into oxygen gas as an assist gas for cutting according to the cutting shape of the workpiece 5, and the oxygen purity is adjusted before the gas is supplied to the processing head 4.

For example, when cutting a shape as shown in FIG.
, J-, as shown in FIG. 3, the amount of nitrogen gas mixed into the oxygen gas is increased by the assist gas supply device 8 to decrease the oxygen purity ratio, and then the mixed gas is supplied to the assist gas. The gas is supplied to the processing head 4 and the workpiece 5 is
Spray onto the processing area.

In this way, in areas with complicated cutting shapes, the oxidation reaction is suppressed by adjusting the oxygen purity of oxygen gas, which is the assist gas, to a low level. Melting loss due to thermal saturation shown in the cutting section and Figure 5 is reduced, allowing high-quality and highly accurate laser cutting, reducing the time required to set processing conditions, and achieving stable cutting. . There is also the advantage that there are no restrictions on the output form and that an inexpensive laser oscillator that does not require a pulse output generator can be used.

In addition, in the above embodiment, a case was explained in which nitrogen gas was used as the gas mixed into the oxygen gas which is the assist gas, but in addition to this, inert gas such as argon, helium, etc.
An active gas such as hydrogen, air, etc. may be used, and in either case, the same effects as in the above embodiments can be achieved.

[Effects of the Invention] As described above, according to the present invention, other types of gases are mixed into the oxygen gas used as an assist gas depending on the cutting shape during laser cutting processing to adjust the purity of the radical element. Therefore, even when cutting sheet metal parts with complicated shapes, the cutting quality is improved and stabilized, and the time required for setting processing conditions can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a laser processing device used to carry out a laser cutting method according to an embodiment of the present invention, and FIG. 2 is a diagram showing a workpiece for explaining an example of cutting processing by the above device. A plan view, FIG. 3 is a graph showing an example of oxygen purity adjustment corresponding to the cutting shape of the workpiece shown in FIG. 2, and FIG. 4 is a graph showing a typical laser used when performing conventional laser cutting processing A schematic configuration diagram showing a processing device, FIG. 5 is a plan view of a workpiece for explaining an example of cutting processing using the above-mentioned conventional device, and FIG. 6 (,) is for explaining the sharp edge angle and erosion length. FIG. 6(b) is a characteristic diagram showing the relationship between the sharp edge angle and the erosion length. In the figure, 1 - laser oscillator, 2 - laser beam, 3
-Laser processing machine, 5.-Workpiece, 7.-Oxygen gas cylinder, 8-Assist gas supply device, 9-Nitrogen gas cylinder. In addition, in FIG. 1, the same reference numerals indicate the same or corresponding parts. Fig. 1 1----- Lehr ° 溌 I Tatsuki 9-111 Nitrogen π bomb Fig. 2 ++ Fig. 3 (Katana Ω Ei Riseki) Fig. 4 1 ---- Leb 溌 1 ash container No. Figure 5 Figure 6 (G) (b) Erra + Night degree θ (button

Claims (1)

[Claims] In a laser cutting method, in which a laser beam is irradiated to the machined part of the workpiece while oxygen gas is used as an assist gas to cut the machined part, the workpiece is cut using an oxidation reaction. A laser cutting method characterized by changing the oxygen purity ratio by mixing other types of gas into the oxygen gas according to the shape.