JPH079184A - Laser cutting method and laser cutting torch - Google Patents

Abstract

PURPOSE:To improve cutting speed by injecting an outer assist gas along an inner assist gas and swirling both gasses for injection. CONSTITUTION:When a material to be cut is irradiated with a laser beam 1 and simultaneously oxygen is supplied to the passage 24 of an inner assist gas, a swirling gas flow f1 is formed by a flow straightening member 26. When oxygen is supplied to the passage 22 of an outer assist gas, a swirling gas flow f2 is formed by a flow straightening member 28. The swirling gas flow f1 prevents the lowering of oxygen purity caused by the atmospheric air taken in and also by combustion gasses and slag mixed in. By the ambient protection through the swirling gas flow f2, the directivity of the swirling flow f1 is protected from being interfered by an external air flow. Consequently, a new assist gas with a high purity is always supplied to the cross-section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser cutting method and a laser cutting torch for irradiating a material to be cut with a laser beam and jetting an assist gas.

[0002]

2. Description of the Related Art Laser cutting is performed by irradiating a material to be cut such as a steel plate, a stainless steel plate, a plywood or a plastic plate with a laser beam and jetting an assist gas along the laser beam. In recent years, the output of the laser oscillator has increased, and it has become possible to cut even a thick plate, which has been conventionally regarded as a region for gas cutting or plasma cutting, and the cutting speed is also improving.

The assist gas injected along the laser beam has a function of removing the molten base material generated by the irradiation of the laser beam and preventing the evaporated base material from adhering to the lens. . The assist gas is oxygen gas or nitrogen gas, depending on the material of the material to be cut and the purpose of cutting.
It is selectively used from among inert gases such as argon gas.

In particular, when cutting a ferrous metal such as a steel plate or a stainless steel plate, or a non-ferrous metal such as brass,
By using oxygen gas as the assist gas, it is possible to cut a thicker plate at a higher speed as compared with the case of using another gas. In this case, the oxygen gas activates the metal combustion reaction, and the higher the purity of the oxygen gas, the higher the combustion efficiency.

[0005]

The oxygen gas sprayed from the nozzle of the laser cutting torch entrains air in the atmosphere and its purity is lowered. Further, the combustion gas generated when the material to be cut burns and a molten substance called slag are mixed to lower the purity. The principle of the problem caused by these is shown in Fig. 4.
First, a laser cutting torch 53 for irradiating the material W to be cut with a laser beam 51 and for injecting an oxygen gas 52 as an assist gas along the laser beam 51 is provided in a predetermined direction in the direction of arrow a. Cutting is performed at a speed to form a cut 54 in the material W to be cut.

A tip portion 54 of the cut end 54 on the cutting direction side
Since the leading portion 52a of the oxygen gas 52 facing a is substantially used for cutting, the combustion gas or slag generated at the time of cutting is mixed to reduce the oxygen purity. Meanwhile, oxygen gas
The trailing portion 52b of 52 does not substantially contribute to activation of the combustion reaction without being used for cutting. Further, the purity of the oxygen gas 52 is lowered due to the entrainment of air in the atmosphere and the inclusion of combustion products as it goes in the thickness direction of the material W to be cut, that is, in the direction remote from the laser cutting torch 53.

Further, since the laser beam 51 travels straight and irradiates the material W to be cut, the moving speed of the laser cutting torch 53 (cutting to the material W to be cut) is applied to the oxygen gas 52 jetted from the nozzle 53a for cutting. Delay depending on the speed)
A drag line is generated at the lower end of the cut surface of the cut end portion 54a due to a delay in cutting or the cut surface is roughened. Therefore, the upper limit of the cutting speed is set by the range in which the oxygen gas 52 maintains the purity capable of maintaining the combustion of the material W to be cut and the positional relationship in which the material W is irradiated with the laser beam 51.

That is, as the cutting speed is increased, the delay of the oxygen gas 52 increases, and the oxygen gas 52 of low purity is supplied to the combustion section. When the cutting speed exceeds a certain speed, even if the laser beam 51 is irradiated, the oxygen gas supplied to the combustion portion cannot maintain the combustion of the material W to be cut, and the cutting is stopped. Therefore, the cutting speed is the limit speed at which the combustion of the material W to be cut can be maintained.

In view of the above-mentioned conventional problems, an object of the present invention is to improve the cutting speed by improving the purity of the assist gas injected from the nozzle of the laser cutting torch and facing the cutting surface, and at the same time, to improve the cutting surface. A laser cutting method and a laser cutting torch having improved finish quality are provided.

[0010]

A laser cutting method according to the present invention is a laser cutting method in which a material to be cut is irradiated with a laser beam and an assist gas is injected along the laser beam to cut the material to be cut. In the method, a laser cutting method is characterized in that the assist gas is swirled and jetted.

Further, the laser cutting method according to the present invention is
In a laser cutting method of irradiating a laser beam to a material to be cut and injecting an assist gas along the laser beam to cut the material to be cut, injecting an inner assist gas along the laser beam, In the laser cutting method, an outer assist gas is jetted along the inner assist gas, and the inner assist gas and / or the outer assist gas is swirled and jetted.

Further, the laser cutting torch according to the present invention is a laser cutting method for irradiating a laser beam to a material to be cut and jetting an assist gas along the laser beam to cut the material to be cut. A laser cutting torch comprising: a passage through which the assist gas flows and a rectifying member that is connected to the passage and ejects the assist gas while swirling along the laser beam.

The laser cutting torch according to the present invention is a laser cutting method for irradiating a laser beam on a material to be cut and for injecting an assist gas along the laser beam to cut the material to be cut. A rectifying member that has an inner assist gas passage that allows the inner assist gas to flow and an outer assist gas passage that allows the outer assist gas to flow, and that comprises a rectifying member that injects the inner assist gas and / or the outer assist gas while swirling It is a characteristic laser cutting torch.

The laser cutting torch according to the present invention is the laser cutting torch, wherein the inner assist gas passage and the outer assist gas passage are formed independently of each other.

[0015]

In the laser cutting method according to the present invention, as described above, the assist gas is swirled and jetted along the laser beam, so that the assist gas facing the tip of the cut end on the cutting proceeding direction side of the material to be cut is always kept. The assist gas that can be formed with a new high-purity assist gas and has not contributed to the activation of the combustion reaction by swirling the assist gas of the succeeding portion that does not face the cut end portion to the cut end portion. Can be used to activate the combustion reaction.

Further, since the assist gas to be jetted is swirled along the laser beam, the combustion gas and the slug can be moved away from the cutting surface and the nozzle by the moment of the swirling gas flow. Further, since the inner assist gas is injected along the laser beam and the outer assist gas is injected along the inner assist gas, a curtain of the outer assist gas is formed around the inner assist gas to shield it from the air in the atmosphere. At the same time, it is possible to prevent the combustion gas or slag generated during cutting from being mixed and to maintain the purity of the inner assist gas at a high level. In addition, the outer assist gas flow can restrain the inner assist gas flow to form a gas flow with good directivity.

Further, since one or both of the inner assist gas and the outer assist gas are swirled, as described above, the assist gas with high purity can be constantly faced to the tip of the cut end and the assist gas of the succeeding part can be provided. It can be used effectively.

Further, since the laser cutting torch according to the present invention is provided with the rectifying member connected to the assist gas passage, the assist gas can be swirled and ejected at a desired direction and flow velocity. Further, since a passage for circulating the inner assist gas and a passage for circulating the outer assist gas are provided on the outer periphery of the passage for passing the laser beam, the inner assist gas is ejected along the laser beam and Outer assist gas can be ejected along the inner assist gas.

Further, since the rectifying member is provided by connecting to one or both of the inner assist gas passage and the outer assist gas passage, the inner assist gas and the outer assist gas are selectively or both in desired directions. And can be jetted while swirling at a flow velocity.

Further, since the inner assist gas passage and the outer assist gas passage are formed independently of each other, the type and flow rate of each gas flow can be set individually.

[0021]

EXAMPLE An example of a laser cutting method and a laser cutting torch according to the present invention will be specifically described with reference to the drawings.
1 is a conceptual diagram for explaining the principle of the present invention, FIG. 2 is a sectional explanatory diagram of a first embodiment of the present invention, and FIG. 3 is a sectional explanatory diagram of a second embodiment of the present invention.

The principle of the action and effect when the assist gas is swirled and jetted will be described with reference to FIG. 1. First, the material W to be cut is irradiated with the laser beam 1 and along the laser beam 1. A laser cutting torch 3 that injects oxygen gas 2 as an assist gas while swirling at a predetermined direction and flow rate cuts at a predetermined speed in the direction of arrow a to form a cut 4 in the workpiece W.

A tip portion 4 of the cut end 4 on the cutting proceeding side.
The leading portion 2a of the oxygen gas 2 facing a is used for cutting at a certain moment, and even if combustion gas or slag generated at the time of cutting is mixed and the oxygen purity is lowered, it swirls at the next moment. Since the leading portion 2a of the oxygen gas 2 is moved to the trailing side and the trailing portion 2b is continuously moved to the leading side by the gas flow 2c, the oxygen gas facing the tip portion 4a of the cut 4 is always of a new high purity. It can be formed with oxygen gas.

Therefore, the cutting speed can be improved by activating the combustion reaction with the high-purity oxygen gas, and the drag line formed by the cutting delay at the lower part of the cutting surface of the cut tip 4a is improved. The finish of the cut surface is also improved. Moreover, since the whole oxygen gas 2 ejected from the nozzle 3a can contribute to activation of the combustion reaction, the oxygen gas 2 can be used efficiently.

In FIG. 2, the nozzle member 11 is provided on the outer periphery of the torch body 10 with a predetermined gap from the outer peripheral wall 10a of the body 10.
Is attached to the outer peripheral wall 10a of the main body 10 and the nozzle member 11
Passage 12 through which the assist gas flows between the inner peripheral wall 11a
Are formed. Further, a rectifying member 13 connected to the passage 12 and ejecting the assist gas while swirling is attached. Therefore, the assist gas supplied from the passage 12 forms the swirling gas flow f through the flow regulating member 13 and is jetted while swirling from the hole 11b of the nozzle member 11.

A lens 14 for condensing the laser beam 1 is arranged at a predetermined position inside the main body 10, and a laser beam emitted from a laser oscillator (not shown) is passed through the lens 14 to the center of the main body 10. It is arranged so as to form an image on a material to be cut (not shown) along the axis.

The torch A constructed as described above irradiates a material to be cut (not shown) with a laser beam 1 emitted with a predetermined laser energy, and an assist gas supply device (not shown) for the passage 12. When oxygen gas is supplied as assist gas from the
A swirling gas flow f is formed by the rectifying member 13 through the flow path.

The swirling gas flow f swirls along the laser beam 1, is jetted from the nozzle hole 11b, and is jetted onto a material to be cut (not shown). The swirling gas flow f injected
As described with reference to FIG. 1, it is possible to constantly supply a new high-purity oxygen gas to the tip 4a of the cut end 4 of the material W to be cut, and the entire oxygen gas contributes to activation of the combustion reaction. By doing so, oxygen gas can be used efficiently. In addition, the combustion gas and slag generated by the combustion are moved away from the cutting surface and the nozzle by the swirling flow of themselves, so that the finished quality of the cutting surface can be improved and the lens and torch can be maintained.

Next, the torch B will be described with reference to FIG. 3. Inside the torch main body 20, a first inner cylinder 21 is arranged at a predetermined distance from the inner peripheral wall 20a of the main body 20. Inner wall
An outer assist gas passage 22 is formed by a gap formed by 20a and the outer peripheral wall 21a of the inner cylinder 21. Inside the inner cylinder 21, a second inner cylinder 23 is arranged with a predetermined distance from the inner peripheral wall 21b of the inner cylinder 21, and an outer peripheral wall 23a of the inner cylinder 23.
The inner assist gas passage 24 is formed by a gap formed by the inner peripheral wall 21b of the first inner cylinder 21 and the inner peripheral wall 21b.

An inner nozzle member 25 is attached to the tip of the first inner cylinder 21, and a rectifying member 26 is connected to the inner assist gas passage 24 via the inner nozzle member 25. An outer nozzle member 27 is attached to the tip of the torch body 20, a rectifying member 28 is connected to the outer assist gas passage 22 via the outer nozzle member 27, and the inner peripheral surface 27a of the outer nozzle member 27 and the outer peripheral member 27a are connected to each other. A passage 29 is formed by a gap formed with the outer peripheral surface 25a of the inner nozzle member 25.

A lens 14 for condensing the laser beam 1 is arranged at a predetermined position inside the second inner cylinder 23, and a laser beam emitted from a laser oscillator (not shown) passes through the lens 14. It is arranged along the central axis of the inner cylinder 23 so as to form an image on a material to be cut (not shown).

The torch B configured as described above irradiates the material to be cut (not shown) with the laser beam 1 emitted with a predetermined laser energy, and assists the inner assist gas passage 24 with an assist (not shown). When oxygen gas is supplied as an assist gas from the gas supply device,
The oxygen gas passes through the inner assist gas passage 24, and the swirling gas flow f1 is formed by the rectifying member 26.

The swirling gas flow f1 swirls along the laser beam 1, is jetted from the outer nozzle hole 27b through the inner nozzle hole 25b, and is jetted onto a material to be cut (not shown). Since the swirling gas flow f1 has the same action and effect as the swirling gas flow f described in the above-mentioned torch A, the description thereof is omitted here.

Similarly, the outer assist gas passage 22 is also provided.
On the other hand, when oxygen gas is supplied as an assist gas from an assist gas supply device (not shown), the swirling gas flow f2 is formed by the rectifying member 28 through the outer assist gas passage 22. The swirling gas flow f2 has a passage
Through the outer nozzle hole 27b through 29, and swirls along the outer periphery of the swirling gas flow f1.
On the other hand, while forming a curtain that shields the air in the atmosphere, the curtain is sprayed on the material to be cut (not shown).

Therefore, it is possible to prevent the swirling gas flow f1 from entraining air in the atmosphere to lower the purity of oxygen, and the combustion gas and slag generated when the material to be cut is burned are the swirling gas. It is possible to prevent the oxygen purity from being lowered by being mixed in the stream f1. Further, by protecting the surroundings of the swirling gas flow f2 with respect to the direction of the swirling gas flow f1, it is possible to improve the directivity of the swirling gas flow f1 without being obstructed by the air flow from the outside.

In the above-described embodiment, the outer assist gas passage 22 and the inner assist gas passage 24 are formed independently of each other, and various kinds of gas are supplied to the respective assist gas passages in a desired type and at a desired flow rate. Enables effective laser cutting.

In the present embodiment, the outer nozzle hole 27b is formed on the material thickness direction side of the inner nozzle hole 25b.
These may be configured on the same plane, and are not limited to this embodiment. Furthermore, although oxygen gas is used as the assist gas, it is desirable to selectively use the type of assist gas depending on the application. Further, since various methods of swirling the assist gas can be considered, it is not necessary to limit the method to this embodiment.

[0038]

Since the laser cutting method and the laser cutting torch according to the present invention have the above-mentioned constitutions and functions, the cutting surface can always be formed with a new high-purity assist gas, and the entire assist gas can be formed. Since it can contribute to activation of the combustion reaction, the cutting speed can be improved, the drag line due to the cutting delay can be improved, and the finished quality of the cut surface can be improved.

Further, the momentum of the swirling gas flow can separate the combustion gas and the slag from the cutting surface and the nozzle to improve the finished quality of the cutting surface and maintain the lens and the torch. Further, since the outer assist gas shields the outer circumference of the inner assist gas and the air in the atmosphere and the combustion gas and slag generated at the time of combustion are not mixed into the inner assist gas, the purity of the inner assist gas is high. And maintain directivity.
Therefore, it is possible to improve the cutting speed and improve the finish quality of the cut surface.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating the principle of the present invention.

FIG. 2 is a sectional explanatory view of the first embodiment of the present invention.

FIG. 3 is a sectional explanatory view of a second embodiment of the present invention.

FIG. 4 is a conceptual diagram illustrating a problem.

[Explanation of symbols]

1 ... Laser beam 2 ... Oxygen gas 2a ... Leading part 2b ... Trailing part 2c ... Swirling gas flow 3 ... Laser cutting torch 3a ... Nozzle 4 ... Cut part 4a ... Tip part 10 ... Torch body 10a ... Outer peripheral wall 11 ... Nozzle member 11a. Inner peripheral wall 11b ... Nozzle hole 12 ... Passage 13 ... Straightening member 14 ... Lens 20 ... Torch body 20a ... Inner peripheral wall 21 ... Inner cylinder 21a ... Outer peripheral wall 21b ... Inner peripheral wall 22 ... Outer assist gas passage 23 ... Inner cylinder 23a ... Outer peripheral wall 24 ... Inner assist gas passage 25 ... Inner nozzle member 25a ... Outer peripheral surface 25b ... Inner nozzle hole 26 ... Straightening member 27 ... Outer nozzle member 27a ... Inner peripheral surface 27b ... Outer nozzle hole 28 ... Straightening member 29 ... Passage W ... Cut Material A, B ... Torch f, f1, f2 ... Swirling gas flow

Claims (5)

[Claims] 1. A laser cutting method in which a material to be cut is irradiated with a laser beam and an assist gas is sprayed along the laser beam to cut the material to be cut,
A laser cutting method comprising swirling and ejecting the assist gas. 2. A laser cutting method of irradiating a laser beam to a material to be cut and jetting an assist gas along the laser beam to cut the material to be cut,
Laser cutting characterized in that an inner assist gas is injected along a laser beam, an outer assist gas is injected along the inner assist gas, and the inner assist gas and / or the outer assist gas is swirled and injected. Method. 3. A laser cutting torch for irradiating a material to be cut with a laser beam and injecting an assist gas along the laser beam to cut the material to be cut, and a passage through which the assist gas flows. A laser cutting torch comprising a rectifying member connected to the passage and ejecting the assist gas while swirling along the laser beam. 4. A laser cutting torch for irradiating a material to be cut with a laser beam and injecting an assist gas along the laser beam to cut the material to be cut, an inner assist for circulating an inner assist gas. A laser cutting torch comprising a gas passage and an outer assist gas passage through which the outer assist gas flows, and a rectifying member for ejecting the inner assist gas and / or the outer assist gas while swirling. 5. The laser cutting torch according to claim 4, wherein the inner assist gas passage and the outer assist gas passage are formed independently of each other.