JPH07155977A - Laser beam machining head - Google Patents

Abstract

PURPOSE:To provide a laser beam machining head which can prevent the pollution and damage to the optical system, and improve the quality of the welding by providing a gas blowout nozzle so as to be orthogonal to the optical axis of the laser beam immediately blow the optical system. CONSTITUTION:A seal box 9 which is provided with a beam transmitting hole 8, covers the point to be machined by the laser beam of a work 4, and keeps the inside in the non-oxidizing atmosphere, an optical system to concentrate the laser beam to the point to be machined by the laser beam and a nozzle 6 to blow out the gas in an orthogonal or approximately orthogonal manner to the optical axis of the laser beam are provided. In addition, another nozzle 13 which is annularly arranged around the laser beam transmitting hole 8 and blows out the gas toward the part to be machined by the laser beam is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing head, and more particularly to a laser processing head capable of preventing the optical system of the laser processing head from being contaminated by spatters, fumes and the like generated during laser processing.

[0002]

2. Description of the Related Art An outline of a conventional laser processing head will be described with reference to FIG. As shown in the figure, a condenser lens 53 that condenses the laser beam light 52 from the laser light source is provided inside the nozzle 51. The condensing lens 53 condenses the laser beam light 52 on the workpiece 54, and the heat source of high energy density obtained at that time performs processing such as melting and cutting.

During the laser processing, the surface of the workpiece 54 is usually covered with a shield box 55 in order to prevent the processed portion from being oxidized, so that a non-oxidizing atmosphere is created. For example,
A shield gas 55a such as an inert gas is introduced into the shield box 55.

During laser processing, fumes, spatters, etc. are generated and adhere to the optical system such as the condenser lens 53 to contaminate the optical system. In order to prevent this contamination, the condenser lens 5
A gas inlet 56 is provided in the vicinity of 3 to introduce gas to protect the lens and the like. Since the gas introduced from the gas introduction port 56 is blown out from the tip of the nozzle 51, a large amount cannot be flowed in order to keep the laser processing normal.

Therefore, this gas flow can prevent the intrusion of fumes, which are extremely fine particles such as metal oxides, but spatter 57 of fine molten metal and having a large upward momentum. Intrusion cannot be prevented.

[0006] FIG. 4 shows a conventional example in which the problem that the generated spatter enters the optical system can be avoided. As shown in the figure, a gas ejection nozzle 58 is provided in the vicinity of the tip of the nozzle 51 instead of the gas introduction port 56 of FIG.

The spatter generated by laser processing is
The traveling direction can be changed by the gas flow ejected from the gas ejection nozzle 58. Therefore, spatter can be prevented from entering the nozzle 51, and contamination of the optical system due to spatter can be prevented.

However, the gas jetted from the gas jet nozzle 58 disturbs the air flow in the shield box 55. Therefore, oxidation of the welded portion 59 during processing of the welded portion 59 is likely to occur due to the inclusion of air.

Further, as shown in FIG. 3, the gas blown out from the tip of the laser processing head 51 serves to stabilize the processing by discharging metal vapor or the like generated in the processing section from the optical path in addition to protecting the optical system. Is also playing. However, in the laser processing head of FIG. 4, exhaust of metal vapor or the like is not sufficient, and the penetration depth in welding is reduced.

An invention relating to a laser processing head for solving the above problems is disclosed in Japanese Patent Laid-Open No. 5-185266. FIG. 5 shows a laser processing head of the above invention.
The structures of the nozzle 51, the condenser lens 53, and the shield box 55 are the same as those of the conventional example shown in FIG.

Inside the nozzle 51, a gas blowing nozzle 61 for blowing gas in a direction substantially orthogonal to the optical axis of the laser beam 12 is provided directly above the shield box 55. The gas blown out from the gas blowing nozzle 61 forms a gas flow G.

The spatter 57 jumping upward from the laser processing position has its traveling direction changed by the gas flow G and is discharged to the outside of the nozzle through the discharge hole 62. In this way, contamination of the optical system due to sputtering can be prevented.

Further, in the shield box 55, the metal vapor-excluded gas 65 is obliquely directed downward at the tip of the nozzle 51.
A gas blowing nozzle 66 having a nozzle hole 65 for blowing out a is provided. The metal vapor generated during the laser processing is excluded from the range of the optical path by the gas ejected from the nozzle 66. Therefore, stable laser processing can be performed.

[0014]

In the conventional example shown in FIG. 5, the nozzle 51 and the shield box 55 are connected while maintaining hermeticity. Therefore, when the gas is flown from the gas blowing nozzle 61 at a high speed, the atmospheric gas in the shield box is drawn from the laser beam transmitting hole, and the laser plume and the like are drawn into the optical path.

Even when the gas blowing nozzle 66 is arranged, it is impossible to prevent the atmospheric gas from being drawn into the shield box unless a large amount of gas flows from the nozzle 66. Further, in order not to disturb the air flow in the shield box, it is necessary to adjust the ejection amount from the gas ejection nozzle 61 and the ejection amount from the gas ejection nozzle 66, but this adjustment is difficult.

Further, in order to prevent the hem of the shield box 55 from being worn, the shield box 55 and the workpiece 5 are
It is preferable to provide a gap with the No. But,
When the gap is provided, the atmosphere flows in through the gap as the gas in the shield box 55 is discharged by the gas flow G. Therefore, the laser processed portion is easily oxidized.

An object of the present invention is to provide a laser processing head capable of preventing contamination and damage of an optical system and improving welding quality.

[0018]

In the following, description will be given with reference numerals in the drawings for the sake of easy understanding, not in a limiting sense.

The laser processing head of the present invention comprises a shield box (9) for covering the laser processing point of the workpiece (4) and making the inside a non-oxidizing atmosphere, and the laser beam transmission of the shield box. Another nozzle for ejecting gas toward the laser processing part (which is provided around the hole (8) and has an annular gas ejection hole (17, 17a) centering on the optical axis of the laser beam ( 13) and an optical system for converging a laser beam at the laser processing point, which is provided at a predetermined distance so as to have an open space between the shield box and the shield box, and is provided immediately below the optical system. Was
A nozzle (6) for blowing gas so as to be orthogonal or substantially orthogonal to the optical axis of the laser beam.

The gas ejection holes may be arranged so that the direction of the ejected gas flow is toward the laser processing point, or the ejected gas flow is substantially on the optical axis at a predetermined distance from the laser processing point. You may arrange so that it may hit at the point of.

In the shield box, it is preferable to provide a gas introducing means (18) having a large number of holes (19) arranged so as to surround the laser processing point. The optical axis may be arranged obliquely with respect to the processed surface.

[0022]

By providing a nozzle that blows out gas so as to be orthogonal or substantially orthogonal to the optical axis of the laser beam just below the optical system, spatter scattered from the laser processing point can be excluded from the optical path. Therefore, it is possible to prevent the contamination and damage of the optical system due to the sputtering.

The shield box is separated from the gas blowing nozzle via the open space, and the gas is blown to the laser processing point from the nozzle provided around the laser beam transmitting hole, so that the inside of the shield box is well separated from the outside. The metal vapor, laser plume, etc. generated by laser processing can be excluded from the optical path. For this reason,
The loss due to absorption of the laser beam can be reduced. In addition, by making the gas blowing hole in an annular shape,
The direction dependence of laser processing quality can be reduced.

Further, by introducing the shield gas from the hole arranged so as to surround the laser processing point in the shield box, the inside of the shield box can be made almost non-oxidizing atmosphere even if the shield box is lifted from the processing surface. You can Therefore, the oxidation of the laser processing point can be suppressed with good stability.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser processing head according to an embodiment of the present invention will be described with reference to FIG. The condenser lens 1 and the protective glass 2 are arranged inside the lens barrel 15. The laser beam 3 that has passed through the condenser lens 1 is condensed, and the protective glass 2
And the workpiece 4 is irradiated with the light.

An air knife nozzle 6 is provided immediately below the protective glass 2 at the tip of the lens barrel 15. The air knife nozzle 6 ejects gas perpendicularly or substantially perpendicularly to the optical axis to form a flat air knife gas flow 7.

The vicinity of the laser-processed portion of the workpiece 4 is covered with a shield box 9 filled with a shield gas 14 to prevent oxidation. Shield box 9
In the portion through which the laser beam 3 passes, a laser beam transmitting hole 8 having a conical inner surface for transmitting the conical laser beam and a nozzle hole 17 for ejecting a control gas to the laser processing portion are provided. A control nozzle 13 is provided.

The control nozzle 13 includes, for example, four columns 16
Is connected to the lens barrel 15 and is fixed so that the optical axis of the laser beam 3 and the central axis of the laser beam transmitting hole 8 coincide with each other. The nozzle hole 17 provided in the control nozzle 13 has an annular shape centered on the optical axis, and the gas ejected from the nozzle hole 17 forms a conical side-face control gas flow 12.
The nozzle 13 is adjusted so that the conical apex of the control gas flow 12 is located substantially at the laser processing portion.

On the inner surface of the shield box 9, an annular gas passage 18 provided with a large number of ejection holes 19 for ejecting the shield gas 14 is arranged so as to surround the optical axis. The shield gas 14 is supplied to the gas passage 18 from the outside through the gas introduction pipe 20, and the shield gas 14 is introduced into the shield box 9.

In the laser processing head shown in FIG.
The spatter 5 scattered from the workpiece 4 during laser processing is
It is discharged out of the laser optical path by the air knife gas flow 7. Therefore, it is possible to prevent the protection glass 2 from being contaminated by sputtering.

Since the air knife gas flow 7 is formed at a predetermined position separated from the shield box 9 by an open space,
The gas in the shield box 9 is not drawn. Further, since a part of the air knife gas flow 7 is also blown to the protective glass 2, there is also an effect of cooling the protective glass 2.

The metal vapor and the laser plume 11 generated on the surface of the workpiece 4 irradiated with the laser beam 3 are excluded from the optical path by the control gas flow 12. This allows
The amount of the laser beam 3 absorbed and scattered by the metal vapor and the laser plume 11 can be reduced.

The shield gas 14 is supplied from a large number of ejection holes 19 provided in the shield box 9 so as to surround the optical axis.
By introducing the above, the inside of the shield box 9 can be filled almost uniformly in a short time. further,
2-3 without contact between the shield box 9 and the workpiece 4
Even if a constant gap of about mm is provided, the shield effect can be sufficiently maintained. By providing a gap,
It is possible to prevent abrasion of the bottom of the shield box 9.

Using the laser processing head of FIG. 1, a YAG laser having an output of 2 kW as a laser light source, dry air as an air knife gas, argon as a control gas and a shield gas are used, and an aluminum alloy A50 having a plate thickness of 2 mm is used.
52 materials (JIS standard H4000) 0.75 m / min
When the through welding was performed at a speed of, good welding without oxidation was possible.

The case where the control gas is directly ejected from the nozzle hole 17 of the control nozzle 13 toward the laser processing portion has been described above, but the nozzle hole may be provided on the inner surface of the laser beam transmitting hole 8.

FIG. 2 shows a laser processing head in which a nozzle hole is provided on the inner surface of a laser beam transmitting hole. The annular nozzle hole 17a surrounds the optical axis and has a laser beam transmitting hole 8a.
It has an opening on the inner surface. The nozzle hole 17a is formed so as to incline the ejected gas flow toward the inside of the shield box 9 at a predetermined angle from the direction perpendicular to the optical axis.

The control gas ejected from the nozzle hole 17a is
They collide in the vicinity of the optical axis and flow toward the laser processing portion of the workpiece 4 along the optical axis. In this way, even if the control gas is ejected from the nozzle hole 17a opened on the inner surface of the laser beam transmission hole 8, the same effect as in the case of FIG. 1 can be obtained.

1 and 2 show the case where the optical axis of the laser beam is tilted by a predetermined angle from the direction normal to the surface of the workpiece 4. This is to prevent reflected light from the surface of the workpiece from entering the lens barrel 15 when the reflectance of the surface of the workpiece with respect to the laser light is high. When the reflectance of the surface of the workpiece is small, the optical axis does not have to be tilted.

Further, the case where the nozzle holes 17 and 17a of the control nozzles 13 and 13a have an annular shape has been described, but it is not always necessary to have an annular shape as long as the metal vapor can be eliminated. For example, a plurality of nozzle holes may be arranged on the circumference.

The present invention has been described above with reference to the embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0041]

As described above, according to the present invention,
When melting a material in a process such as laser welding or overlaying, it is possible to prevent oxidation of the melted portion and improve the melting quality, and also prevent contamination and damage of the optical system.

[Brief description of drawings]

FIG. 1 is a sectional view of a laser processing head according to an embodiment of the present invention.

FIG. 2 is a sectional view of a laser processing head according to a modified example of the embodiment of the present invention.

FIG. 3 is a sectional view of a laser processing head according to a conventional example.

FIG. 4 is a sectional view of a laser processing head according to a conventional example.

FIG. 5 is a sectional view of a laser processing head according to a conventional example.

[Explanation of symbols]

 1 Condensing Lens 2 Protective Glass 3 Laser Beam 4 Workpiece 5 Sputter 6 Air Knife Nozzle 7 Air Knife Gas Flow 8 Laser Beam Transmission Hole 9 Shield Box 11 Laser Plume 12 Controlled Gas Flow 13, 13a Controlled Nozzle 14 Shielded Gas 15 Mirror Cylinder 16 Support 17, 17a Nozzle hole 18 Gas passage 19 Ejection hole 20 Gas introduction pipe 51 Nozzle 52 Laser beam light 53 Condenser lens 54 Workpiece 55 Shield box 55a Shield gas 56 Gas introduction port 57 Sputter 58 Gas ejection nozzle 59 Welding Part 61 Gas blow nozzle 62 Discharge hole 65 Nozzle hole 65a Metal vapor discharge gas 66 Gas blow nozzle

Claims (5)

[Claims] 1. A shield box (9) having a laser beam transmitting hole (8) for covering a laser processing point of a workpiece (4) to make the inside a non-oxidizing atmosphere, said shield. An optical system for converging a laser beam at the laser processing point, which is provided at a predetermined distance so as to have an open space between the box and a light beam of the laser beam provided directly below the optical system. A nozzle (6) for blowing gas so as to be orthogonal or substantially orthogonal to the axis and a gas injection hole (17) arranged in the circumference of the laser beam transmission hole of the shield box and having an optical axis of the laser beam as the center. , 17a), and another nozzle (13) for injecting gas toward the laser processing section. 2. The laser processing head according to claim 1, wherein the gas ejection holes are arranged such that the direction of the ejected gas flow is toward the laser processing point. 3. The laser processing head according to claim 1, wherein the gas ejection holes are arranged such that the ejected gas flow collides with each other at a point on the optical axis that is separated from the laser processing point by a predetermined distance. 4. A large number of holes (19) arranged in the shield box so as to surround the laser processing point.
The laser processing head according to any one of claims 1 to 3, further comprising a gas introduction unit (18) having a. 5. The optical axis of the laser beam is set to be inclined with respect to the direction of the lower surface of the shield box.
The laser processing head according to any one of to 4.