JP2865543B2 - Laser processing head - Google Patents

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 contamination of an optical system of the laser processing head due to spatter, fume, etc. 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 drawing, a condenser lens 53 for condensing a laser beam 52 from a laser light source is provided inside the nozzle 51. The laser beam 52 is condensed on the workpiece 54 by the condenser lens 53, and a process such as melting and cutting is performed by a heat source having a high energy density obtained at that time.

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

During laser processing, fumes, spatters and the like are generated and adhere to the optical system such as the condenser lens 53 to contaminate the optical system. To prevent this contamination, the condensing 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 inlet 56 is blown out from the tip of the nozzle 51, an excessive amount of gas cannot be flowed in order to maintain normal laser processing.

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

FIG. 4 shows a conventional example which can avoid the problem that generated spatter enters the optical system. 3, a gas ejection nozzle 58 is provided near the tip of the nozzle 51 instead of the gas inlet 56 in FIG.

[0007] Sputter generated by laser processing is
The traveling direction can be changed by the gas flow ejected from the gas ejection nozzle 58. For this reason, it is possible to prevent the spatter from entering the nozzle 51 and prevent contamination of the optical system due to the sputter.

[0008] However, the gas jetted from the gas jet nozzle 58 disturbs the air flow in the shield box 55. Therefore, oxidation during processing of the welded portion 59 is likely to occur due to entrainment in the atmosphere.

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 and the like generated in the processing portion from the optical path in addition to protecting the optical system. Also plays. However, in the laser processing head shown in FIG. 4, exhaust of metal vapor or the like becomes insufficient, and the penetration depth of welding is reduced.

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

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

The sputter 57 that has jumped 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, inside the shield box 55, the metal vapor elimination gas 65
A gas blowing nozzle 66 having a nozzle hole 65 for blowing a is provided. The metal vapor generated during the laser processing is removed out of the optical path by the gas ejected from the nozzle 66. Therefore, laser processing can be performed stably.

[0014]

In the conventional example shown in FIG. 5, a nozzle 51 and a shield box 55 are connected while keeping airtightness. Therefore, when a gas flows at a high speed from the gas blowing nozzle 61, 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 provided, 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. Furthermore, in order not to disturb the airflow in the shield box, it is necessary to adjust the amount of gas ejected from the gas ejection nozzle 61 and the amount of gas ejected 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 work 5
It is preferable to provide a gap between the first and the second. But,
When the gap is provided, the air flows from the gap as the gas in the shield box 55 is discharged by the gas flow G. Therefore, the laser processing 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]

Means for Solving the Problems In the following, description will be made with reference to the reference numerals in the drawings for the sake of simplicity and not for limiting.

A laser processing head according to the present invention covers a laser processing point of a workpiece (4) and has a shield box (9) for making the inside a non-oxidizing atmosphere, and a laser beam transmission of the shield box. Another nozzle (17, 17a) is provided around the hole (8) and has an annular gas ejection hole (17, 17a) centered on the optical axis of the laser beam, and injects gas toward the laser processing portion. 13) and an optical system for condensing 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. 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 hole may be arranged so that the direction of the ejected gas flow is directed to the laser processing point, or the ejected gas flow is substantially on an optical axis at a predetermined distance from the laser processing point. May be arranged so as to collide with each other.

It is preferable that a gas introducing means (18) having a large number of holes (19) arranged so as to surround the laser processing point is provided in the shield box. The optical axis may be arranged obliquely to the processing surface.

[0022]

By providing a nozzle that blows gas just below or substantially perpendicular to the optical axis of the laser beam just below the optical system, spatters scattered from the laser processing point can be excluded from the optical path. For this reason, contamination and damage of the optical system due to sputtering can be prevented.

The shield box is separated from the gas blow-out nozzle via an open space, and the inside of the shield box is well separated from the outside by blowing gas from a nozzle provided around the laser beam transmission hole to a laser processing point. In addition, metal vapor, laser plume, and the like generated by laser processing can be excluded from the optical path. For this reason,
Loss due to laser beam absorption can be reduced. In addition, by making an annular gas blowing hole,
The direction dependency of the laser processing quality can be reduced.

Furthermore, by introducing a shielding gas from a hole arranged in the shield box so as to surround the laser processing point, the inside of the shield box can be made to have a substantially non-oxidizing atmosphere even when the shield box is lifted from the processing surface. Can be. Therefore, 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 disposed inside the lens barrel 15. The laser beam 3 transmitted through the condenser lens 1 is condensed, and
Then, the workpiece 4 is irradiated.

An air knife nozzle 6 is provided directly 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 by a shield box 9 filled with a shield gas 14 to prevent oxidation. Shield box 9
In a portion through which the laser beam 3 passes, a laser beam transmitting hole 8 having a conical inner surface for transmitting a conical laser beam and a nozzle hole 17 for ejecting a control gas to a laser processing portion are provided. A control nozzle 13 is provided.

The control nozzle 13 has, for example, four columns 16
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 the control gas flow 12 having a conical side surface.
The nozzle 13 is adjusted so that the conical apex of the control gas flow 12 is located substantially at the laser processing part.

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 provided so as to surround the optical axis. The shielding gas 14 is supplied to the gas passage 18 from the outside through a gas introduction pipe 20, and the shielding gas 14 is introduced into the shielding box 9.

In the laser processing head shown in FIG.
The spatter 5 scattered from the workpiece 4 during the laser processing,
The air knife gas stream 7 discharges out of the laser beam path. Therefore, contamination of the protective glass 2 due to spatter can be prevented.

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 removed out of 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.

A large number of jet holes 19 provided in the shield box 9 so as to surround the optical axis allow the shield gas 14 to pass through.
, The inside of the shield box 9 can be filled almost uniformly in a short time. further,
Keep the shield box 9 and the workpiece 4 in contact with each other
Even if a certain gap of about mm is provided, a sufficient shielding effect can be maintained. By providing a gap,
Wear of the skirt of the shield box 9 can be prevented.

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

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

FIG. 2 shows a laser processing head having a nozzle hole provided on the inner surface of the laser beam transmitting hole. An annular nozzle hole 17a is formed around the optical axis so as to surround the optical axis.
It is open on the inner surface. The nozzle hole 17 a is formed to be inclined at a predetermined angle from a direction perpendicular to the optical axis so that the jetted gas flow is directed toward the inside of the shield box 9.

The control gas ejected from the nozzle hole 17a is:
They collide near the optical axis and flow toward the laser processing portion of the workpiece 4 along the optical axis. As described above, 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 that of FIG. 1 can be obtained.

FIGS. 1 and 2 show a case where the optical axis of the laser beam is inclined at a predetermined angle from the direction normal to the surface of the workpiece 4. This is to prevent light reflected 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 beam is large. When the reflectance of the workpiece surface is low, the optical axis does not have to be inclined.

Although the case where the nozzle holes 17, 17a of the control nozzles 13, 13a are annular has been described, the annular shape is not necessarily required as long as metal vapor or the like can be eliminated. For example, a plurality of nozzle holes may be arranged on the circumference.

The present invention has been described in connection with the preferred 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 a material is melted in a process such as laser welding or overlaying, it is possible to prevent oxidation of a melted portion, improve the quality of the melt, and prevent contamination and damage of the optical system.

[Brief description of the 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 modification 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]

 DESCRIPTION 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 Control gas flow 13, 13a Control nozzle 14 Shield gas 15 Mirror Cylinder 16 Support 17, 17 a Nozzle hole 18 Gas passage 19 Jet hole 20 Gas inlet tube 51 Nozzle 52 Laser beam light 53 Condensing lens 54 Workpiece 55 Shield box 55 a Shield gas 56 Gas inlet 57 Sputter 58 Gas jet nozzle 59 Welding Part 61 Gas blowout nozzle 62 Discharge hole 65 Nozzle hole 65a Metal vapor discharge gas 66 Gas blowout nozzle

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-56-151191 (JP, A) JP-A-63-127792 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23K 26/00-26/14

Claims (5)

(57) [Claims] 1. A shield box (9) having a laser beam transmitting hole (8), covering a laser processing point of a workpiece (4), and providing a non-oxidizing atmosphere inside the shield box (9); An optical system for focusing a laser beam on the laser processing point, which is provided at a predetermined distance so as to have an open space between the box and the box; and a light beam of the laser beam provided immediately below the optical system. A nozzle (6) for blowing gas so as to be orthogonal or substantially orthogonal to the axis and an annular gas ejection hole (17) arranged around the laser beam transmission hole of the shield box and centered on the optical axis of the laser beam. , 17a) and further nozzles (13) for injecting gas towards the laser working part. 2. The laser processing head according to claim 1, wherein the gas ejection holes are arranged so that the direction of the ejected gas flow is directed to the laser machining point. 3. The laser processing head according to claim 1, wherein the gas ejection holes are arranged such that the ejected gas flows collide at a point on a substantially optical axis which is separated from the laser processing point by a predetermined distance. 4. A plurality of holes (19) arranged in said shield box so as to surround said laser processing point.
The laser processing head according to any one of claims 1 to 3, further comprising a gas introduction means (18) having the following. 5. An optical axis of a laser beam is set to be inclined with respect to a normal line of a lower surface of the shield box.
The laser processing head according to any one of claims 1 to 4.