JP2000202678A - Nozzle for laser beam cutting and laser beam cutting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct high speed cutting or thick plate cutting in high quality by straightening a shield gas in a nozzle for maintaining oxygen purity and realizing gas flow having better efficiency in laser beam cutting with using an unstable type resonator, in particular, laser beam cutting with a high output laser beam. SOLUTION: In laser beam cutting by a high output laser beam with using an assist gas, a pool part 17 for a gas for curtain is arranged in a nozzle for laser beam cutting, a passage from the pool for curtain gas is arranged as having an angle to the direction rotating around a laser beam optical axis, a slit shaped outlet for curtain gas is arranged on a concentric circle more outside than the outlet ejecting a cutting assist gas and a laser beam, gas for curtain flow is straightened in the direction facing outward for the laser beam optical axis, supply of a high purity cutting assist gas is possible as compared to a conventional way, high speed cutting or thick plate cutting is done in high quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser cutting nozzle and a laser cutting apparatus for irradiating a laser beam, jetting an assist gas, and jetting a curtain gas in laser cutting.

[0002]

2. Description of the Related Art In laser cutting of a steel material utilizing an oxidative exothermic reaction using oxygen as an assist gas, the oxygen purity at the cutting point greatly affects the cutting quality. FIG. 9 is a schematic view of a conventional typical laser cutting apparatus. The laser beam 2 output from the laser oscillator 1 is condensed by a condensing lens or a converging mirror 4, and cutting is performed while injecting an assist gas 13 such as a high-purity oxygen gas for cutting coaxially with the laser beam.
At this time, it is necessary to use oxygen gas having a high purity of 99.0% or more.

Conventionally, in laser cutting, in order to maintain the purity of the assist gas even at the time of cutting, the nozzle 6 is arranged so as to surround the laser optical axis and the outer periphery of the nozzle for assist gas injection as shown in FIG.
The gas 14 flows in a curtain shape from the lower surface of the workpiece 8 in a direction substantially perpendicular to the surface of the material 8 to be cut off, thereby preventing the outside air from entering the shield area inside the curtain to prevent the purity of the assist gas from being reduced.

In the prior art, the following method is used. In the laser cutting nozzle disclosed in Japanese Patent Application Laid-Open No. 9-141483, a high-purity gas is supplied by providing an ejection angle to the curtain gas to prevent air from flowing into the system gas region. Next, in the laser processing nozzle disclosed in Japanese Patent Application Laid-Open No. Sho 62-214893, the outer peripheral surface of the processing nozzle is made almost vertical or tapered in a direction opposite to the taper of the passage, thereby preventing entry of air and preventing the purity of the assist gas. Is increasing.

[0005]

In a conventional laser cutting nozzle, a curtain gas is injected substantially perpendicularly to a material to be cut from a surface of the nozzle facing the material to be cut. In this method, the gas injected from the cutting nozzle is jetted at a spread angle, so that the curtain gas enters inside the shield region of the cutting assist gas, disturbs the flow of the cutting assist gas, and cuts. The quality or the cutting speed was reduced, and the good cutting area was narrowed. Alternatively, the curtain gas is mixed into the high-purity assist gas, which lowers the oxygen purity or reduces the oxygen purity in the shield area by entraining the atmosphere outside the curtain, thereby deteriorating the cutting quality or cutting. It reduced the speed and narrowed the area of dross-free cutting.

[0006] Next, in the laser cutting nozzle disclosed in Japanese Patent Application Laid-Open No. 9-141483, the curtain gas faces outward and the flow of the cutting gas is not disturbed by the curtain gas, so that the air outside the curtain is hardly entrained. However, the entrainment amount was small, and the purity of the shielding gas was slightly reduced. Also, in the laser processing nozzle disclosed in Japanese Patent Application Laid-Open No. Sho 62-214893, the flow direction of the curtain gas is jetted perpendicularly to the material to be cut, so that the curtain is positioned within the shield gas region of the assist gas for cutting. There is a problem that the flow of the cutting assist gas is disturbed due to the mixing of the cutting gas.

Accordingly, the present invention provides a laser cutting nozzle and a laser cutting apparatus which can solve the problems of the turbulence of the flow of the cutting gas and the entrainment of the curtain gas and the atmosphere, and can stably secure the oxygen purity at the cutting point. The task is to provide.

[0008]

The object of the present invention is to provide: (1) a ring-shaped curtain gas accumulating portion outside the optical path of the laser beam around the laser optical axis and the flow path of the assist gas inside the nozzle; A cylindrical slit opening at the tip of a nozzle is provided below the curtain gas reservoir outside the optical path of the laser beam and the flow path of the assist gas around the laser optical axis, and the reservoir of the curtain gas. Providing a plurality of flow paths connecting the portion and the cylindrical slit,
A nozzle for laser cutting, wherein a curtain gas flowing in the cylindrical slit is swirled. (2) Inside the nozzle, a ring-shaped curtain gas reservoir is provided outside the optical path of the laser beam around the laser optical axis and the flow path of the assist gas, and a plurality of flow paths are formed from the curtain gas reservoir. A laser cutting nozzle, characterized in that each of the nozzles is arranged on a plane parallel to the laser optical axis at an angle with respect to the laser optical axis, and is opened at the tip of the nozzle in a ring shape. And (3) a laser cutting device for irradiating a groove forming laser in advance to the cutting portion to form a groove in the cutting portion, and then irradiating the groove with a cutting laser to cut the steel plate. A laser cutting device using the laser cutting nozzle according to 2). Can be solved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A laser cutting nozzle according to the present invention allows a curtain gas to flow over the surface of a material to be cut so as to surround an exit of a laser beam and a shielding gas for cutting, thereby reducing disturbance to an assist gas for cutting. Has a mechanism to prevent. As the curtain gas, the same oxygen gas or inert gas as the cutting assist gas is used. The curtain gas is temporarily stored in the curtain gas reservoir to keep the pressure constant. After that, the curtain gas is ejected from the nozzle toward the material to be cut through the cylindrical slit while passing through the inward passage while rotating spirally around the laser optical axis and merging again inside the nozzle.

[0010] The jetted curtain gas is directed to the outside of the jet outlet because it proceeds in the tangential direction of the tubular outlet, and the inside of the gas for the curtain does not enter the gas from the outside and maintains the high-purity assist gas. can do. Further, without providing a cylindrical slit, a curtain containing a swirling flow can be formed outside the nozzle by ejecting the gas from the nozzle tip through a circularly arranged flow path from a reservoir for the curtain gas.

[0011]

[Embodiment 1] FIGS. 1 and 2 show an embodiment of the present invention. In the figure, 1 is a cutting laser oscillator, 2
Is a cutting laser beam, 3 is a condenser lens, 4 is a condenser mirror,
5 is an assist gas supply device, 6 is a cutting nozzle, 7 is a curtain gas supply device, and 8 is a material to be cut.

In this embodiment, the method shown in FIG. 1 is used. In addition to the assist gas supplied to the cutting nozzle 6, a curtain gas supply device 7 was installed to separately provide a curtain gas supply path. Further, a ring-shaped gas reservoir 17 for curtain gas is provided inside the nozzle 6, from which it is jetted downward along a cylindrical slit having a width of 1 mm and a height of 10 mm. At this time, since the curtain gas is supplied to the jet port 16 through the gas passage 19 directed in one direction, the curtain gas turns in the AA 'plane as shown in FIG. FIG. 5 shows a curtain gas injection port 16 on the lowermost surface of the cutting nozzle facing the material to be cut. The outlet of the curtain gas is at the lowermost surface of the nozzle for the material to be cut. This makes it possible to provide an outward component to the ejected curtain gas. As a result, no outside air is trapped in the shield gas region inside the curtain gas, and oxygen purity can be maintained without loss.

The curtain gas is injected from an annular slit having a width of 0.5 mm. The distance between the cutting nozzle and the workpiece is 1mm
A high purity oxygen gas having a purity of 99.9% was used as the curtain gas, and the flow rate was 100 L / min. Cutting laser output 12kW, cutting speed 1.0m / min, focusing mirror 4
Used a parabolic mirror having a focal length FL = 20 ″. A high-purity oxygen gas having a purity of 99.9% was used as an assist gas for cutting.

As a result, the oxygen purity of the assist gas in the processing portion can be maintained at 99.8%,
Dross-free cutting of thick SS400 steel was possible. As a result, the oxidative exothermic reaction between the mild steel material to be cut and oxygen as the assist gas can be used efficiently, cutting can be stably performed dross-free, and the cutting speed can be increased by about 50%. Was.

As shown in FIG. 2, the curtain gas may be shared with the cutting assist gas. That is, the gas supplied from the assist gas supply device 5 passes through the gas reservoir 18 and is ejected from one passage as a cutting assist gas to the vicinity of the laser emission port 15, and from the ejection port 16 via the other passage 19, the curtain is discharged. It gushes as a working gas.

[Embodiment 2] FIG. 3 shows another embodiment of the present invention. As in Example 1, a gas supply path for the curtain was provided in addition to the assist gas for supplying the nozzle to cut the steel sheet as shown in FIG. A gas reservoir 17 for curtain gas is provided inside the nozzle 6, and twelve 3 mm-diameter curtain gas passages 19, which emerge in the direction of the material to be cut, are spirally formed at an angle with respect to the laser optical axis 2. It was located inside the nozzle. The curtain gas passes through a gas passage having a twist angle of 60 degrees, so that an outward component is given to the curtain gas ejected toward the material to be cut. FIG. 6 shows a curtain gas injection port 16 on the lowermost surface of the cutting nozzle 6 facing the material to be cut. Here also, the outlet of the curtain gas is on the lowermost surface of the nozzle facing the material to be cut.

The distance between the cutting nozzle and the material to be cut was 1 mm, high purity oxygen gas of 99.9% was used as the curtain gas, and the flow rate was 100 L / min. The cutting laser used was a 12 kW output, the cutting speed was 1.0 m / min, and the focusing mirror used was a parabolic mirror having a focal length of FL = 20 ″. The cutting assist gas used was 99.9% pure high-purity oxygen gas. As a result, the oxygen purity of the assist gas in the processing portion can be maintained at 99.8%, and the S gas having a thickness of 16 mm can be maintained.
S400 steel was dross-free cut. As a result, the oxidative exothermic reaction between the mild steel material as the material to be cut and oxygen as the assist gas can be efficiently used, the cutting can be stably performed dross-free, and the cutting speed is reduced by about 50%.
Could be raised. In this case, the curtain gas may be shared with the cutting assist gas as shown in FIG.

Example 3 The above cutting nozzle was used as a cutting nozzle for laser cutting in combination with a groove forming laser.
FIG. 10 is a view showing laser irradiation on the groove 12 in the steel plate at this time, FIG. 11 is a schematic perspective view of laser cutting using a groove forming laser, and FIG. 12 is a view showing one embodiment of a composite laser cutting apparatus.

As shown in FIG. 12, the laser cutting apparatus is arranged such that a groove forming laser beam 22
Is provided along a predetermined cutting line on the workpiece 8. For this purpose, a groove forming laser oscillator 9, a reflecting mirror 20 and a condensing mirror 3 are separately provided, and a sputter removing nozzle 10 is also provided toward a position where the groove forming laser light 22 is irradiated. In the figure, 21
Indicates a cutting portion, and 23 indicates a scale removing portion. In this embodiment, the nozzle of FIG. 1 is used. A gas reservoir for curtain gas is provided inside the nozzle, from which the width is 1 mm and the height is 1
It erupted downward along a 0 mm cylindrical slit. The outlet of the curtain gas is at the lowermost surface of the nozzle for the material to be cut.

A pulse laser was used as a groove forming laser, the average power was 250 W, and the repetition frequency was 10 kHz. A lens having a focal length FL = 7.5 ″ was used as a condensing lens. Nitrogen was used as an assist gas for groove processing, and a flow rate was set to 100 L / min. The output was 12 kW, the cutting speed was 1.5 m / min, and the focusing mirror used had a focal length FL = 20 ″. 99.9% high-purity oxygen gas was used as the cutting assist gas. As a result, SS400 with a thickness of 16 mm
Dross-free cutting of thick steel plate was possible.

[0021]

As described above, according to the present invention, a slit-shaped or perforated curtain gas is concentrically arranged on a nozzle so as to surround the outer periphery of a nozzle for irradiating and jetting a laser beam and a cutting assist gas. And the curtain gas passage is angled in the direction in which the curtain gas rotates with respect to the laser optical axis inside the nozzle, so that the curtain gas flows on the material to be cut as shown in FIG. It is emitted in the tangential direction of the concentric circle with the laser beam. As shown in FIG. 7B, the curtain gas does not enter the shield region of the assist gas in the curtain, so that mixing into the assist gas during processing can be prevented and disturbance can be prevented. Further, there is an effect of preventing the invasion of outside air from the outside of the curtain, improving cutting performance such as cutting quality and cutting speed, expanding a dross-free area, and realizing stable cutting.

[Brief description of the drawings]

FIG. 1 is a drawing showing a cross section of a laser cutting nozzle of the present invention and a cutting device.

FIG. 2 is a drawing showing a cross section of a laser cutting nozzle of the present invention and a cutting device.

FIG. 3 is a view showing the structure of a laser cutting device according to the present invention.

FIG. 4 is a view showing a flow of a curtain gas in a nozzle.

FIG. 5 is a view showing the shape of a lower surface injection port (slit type).

FIG. 6 shows the shape of a curtain gas injection port under the nozzle (porous type).
Drawing.

FIG. 7 is a view showing a curtain gas injection direction from a nozzle.

FIG. 8 is a view showing a conventional shielding method using a curtain.

FIG. 9 is a cross-sectional view of a typical prior art laser cutting device.

FIG. 10 is a view showing laser irradiation on a groove in a steel plate.

FIG. 11 is a schematic perspective view of a laser cutting technique using a groove forming laser.

FIG. 12 is a view showing one embodiment of a composite laser cutting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cutting laser oscillator 2 Cutting laser beam 3 Condensing lens 4 Condensing mirror 5 Assist gas supply device 6 Cutting nozzle 7 Curtain gas supply device 8 Material to be cut 9 Groove forming laser oscillator 10 Sputter removal nozzle 11 Scale 12 Groove 13 Cutting assist gas 14 Curtain gas 15 Laser emission port 16 Curtain gas injection port 17 Curtain gas reservoir 18 Assist gas reservoir 19 Curtain gas passage 20 Reflector mirror 21 Cutting unit 22 Groove forming laser beam 23 Scale removal unit

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Katsuhiro Minami 20-1 Shintomi, Futtsu-shi, Chiba F-term in the Technology Development Division of Nippon Steel Corporation (reference) 4E068 AA05 AD00 AE00 CD15 CH02

Claims (3)

[Claims] A laser cutting nozzle used for laser cutting with a high-power laser using an assist gas,
Inside the nozzle, a ring-shaped curtain gas reservoir outside the optical path of the laser light and the assist gas flow path around the laser optical axis, and the laser optical axis below the curtain gas reservoir. Outside the optical path of the laser beam and the flow path of the assist gas, a cylindrical slit opening at the tip of the nozzle is provided, and a plurality of flow paths connecting the reservoir for the curtain gas and the cylindrical slit are formed. A nozzle for laser cutting, wherein a curtain gas flowing in the cylindrical slit is swirled. 2. A laser cutting nozzle used for laser cutting with a high-power laser using an assist gas,
Inside the nozzle, a ring-shaped curtain gas reservoir is provided outside the optical path of the laser light around the laser optical axis and the flow path of the assist gas, and a plurality of flow paths are formed from the curtain gas reservoir through the laser light. A laser cutting nozzle which is arranged at an angle with respect to an axis, is respectively arranged on a plane parallel to a laser optical axis, and has an annular opening at a nozzle tip. 3. A laser cutting apparatus having a laser cutting nozzle according to claim 1 or 2, further comprising a groove forming laser oscillator separately from the laser cutting nozzle, and irradiating the cutting section with a groove forming laser in advance. A laser cutting device for irradiating the groove with a cutting laser from a laser cutting nozzle to cut the steel plate.