JPH05185266A - Laser beam machining head - Google Patents

Abstract

PURPOSE:To prevent the contamination of an optical system of a laser beam machining head caused by a spatter, fume, etc., generated at the time of laser beam machining. CONSTITUTION:In a laser beam machining head, a laser beam 12 is condensed by a condensing lens 13 in a shielding box 15 which covers the machining point of a material to be machined 14 and machining such as welding, build-up welding is carried out. A gas ejecting nozzle 21 which ejects a gas flow G of spatter eliminating gas is provided in a direction orthogonally or almost orthogonally crossing the light axis of the laser beam 12 directly above the shielding box 15 and an excellent laser beam machining is carried out by eliminating the spatter 17, etc., to prevent the contamination of the condensing lens 13.

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, it is devised so as to prevent contamination of the optical system of the laser processing head due to spatters, fumes and the like generated during laser processing.

[0002]

2. Description of the Related Art An outline of conventional laser processing will be described with reference to FIG. As shown in the figure, a condenser lens 13 for condensing the laser beam light 12 from the laser light source is provided inside the nozzle 11, and the condenser lens 13 causes the laser beam light 12 to reach the workpiece 14. Is focused and laser processing such as melting and cutting is performed by a high energy density heat source obtained at that time.

At the time of this laser processing, a shield box 15 for covering the surface of the workpiece 14 is usually provided in order to prevent the processing portion from being oxidized, and an atmosphere that does not oxidize is formed (for example, a shield for an inert gas or the like). Processing is performed by introducing the gas 15a into the shield box 15).

By the way, during laser processing, fumes, spatters, etc. are generated and adhere to the optical system such as the condenser lens 13 and contaminate the optical system.
A gas inlet 16 is provided in the nozzle 11 near the condenser lens 13 to introduce gas to protect the lens and the like. Since the gas introduced from the gas inlet 16 is blown out from the tip of the nozzle 11, a large amount cannot be flowed in order to keep the laser processing normal.

Therefore, this gas flow can almost prevent the intrusion of fumes, which are fine particles such as metal oxides, but the spatter 17 which is a fine molten metal and has a large upward momentum. , It is in a state where it does not have a protective effect and is left to pollution.

Although it is possible to reduce the occurrence of this spatter 17 by improving the construction surface such as optimization of the laser processing conditions, it is impossible to eliminate it.

In the condensing optical system such as the condensing lens 13 contaminated by the spatter 17, the transmittance of the laser beam light 12 decreases (in the case of a mirror instead of the lens, the reflectivity decreases), and the laser beam The light is heated by the light 12, and the resulting thermal deformation deteriorates the optical characteristics such as the light-collecting performance, and as a result, normal processing cannot be performed. Therefore, the contaminated optical system had to be replaced regularly, but it was often difficult to maintain the reliability of laser processing because the threshold value of contamination that adversely affects the processing was not clear. .. Further, since the laser optical system is expensive, the periodical replacement of the optical system causes a great increase in cost for laser processing.

Therefore, conventionally, the contamination of the spatter is prevented as follows. A method of giving momentum to the generated spatter and changing its traveling direction outside the range of the optical system. Specifically, as shown in FIG. 5, a gas blowing nozzle 18 is provided in the vicinity of the tip of the nozzle 11, and gas is ejected directly above the processed portion of the workpiece 14.

[0009]

However, the conventional methods for preventing spatter contamination have the following problems.

In the method of imparting kinetic force to the spatter and changing the traveling direction thereof to the outside of the range of the optical system, since the laser beam passes through the entrance path of the sputter, the means for imparting kinetic force to the sputter is It should not interrupt the laser beam path.

For example, in the gas blowing method directly above the processing portion as shown in FIG. 5, the gas ejected from the gas blowing nozzles 18 arranged in the shield box 15 disturbs the air flow in the shield box 15 and the atmosphere. Oxidation is likely to occur during the processing of the welded portion 19 due to the inclusion of the metal.

In addition to protecting the optical system, the gas blown from the tip of the processing head also serves to discharge metal vapor generated in the processing section from the optical path to stabilize the processing (for example, welding). Although the penetration depth in the portion 19 is maintained, etc.), when considering the spatter elimination function by the gas flow as described above, the elimination of the metal vapor or the like that is generated is not sufficient, and the penetration depth in welding decreases. ..

[0013]

The structure of the laser processing head according to the present invention for solving the above problems is such that a laser beam light is condensed by an optical system in a shield box covering a laser processing point of a workpiece. A laser processing head for condensing, performing processing such as welding and overlaying, provided with gas flow blowing means for blowing gas in a direction orthogonal or substantially orthogonal to the optical axis of the laser beam light just above the shield box. It is characterized by

[0014]

In the above structure, since the spatter which has jumped upward from the processing point at the time of laser processing can change its traveling direction to the gas flow direction by the gas flow blowing means, it does not reach the converging optical system and the laser is stabilized. Processing can be performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of a laser processing head according to this embodiment. As shown in the figure, a condenser lens 13 as a condenser optical system for condensing the laser beam light 12 is arranged inside the nozzle 11, and the condenser lens 13 causes a laser beam to be applied to a workpiece 14. The beam light 12 is condensed and laser processing such as welding and overlaying is performed. Further, in the laser processing, the shield box 1 for introducing the shield gas 15a in the vicinity of the laser processing portion in order to prevent oxidation of the processing portion.
5 is used for covering. Therefore, the tip of the nozzle 11 is connected to the shield box 15 and maintains hermeticity.

Immediately above the shield box 15 and inside the nozzle 11, there is provided a gas blowing nozzle 21 as a gas blowing means for blowing sputter exhaust gas in a direction orthogonal or substantially orthogonal to the optical axis of the laser beam light 12. , Gas flow G
Is formed. Then, the advancing direction of the spatter 17 jumping upward from the processing point is changed by the gas flow G and is discharged to the outside of the nozzle 11 through the discharge port 22 to prevent scattering to the optical system.

In the above-mentioned structure, the focused laser beam light 12 passes through the nozzle 11 and irradiates the work piece 14, and at the same time, the entire machining head is moved to the work piece 14 at a predetermined speed. The welded portion 19 is formed by moving in the direction.

At this time, the spatter 17 is scattered upward from the welded portion 19 in the nozzle 11. Among them, the spatter 17 that has passed through the transmission hole 23 for the laser beam light 12 at the tip portion and invaded upwards. By the gas flow G of the spatter exhaust gas from the gas blowing nozzle 21 provided directly above the shield box 15, the direction of the gas can be changed to the gas flow G direction, so that the condensing lens 13 or other condensing optical system can be changed. Spatter 17
Can be prevented from adhering.

At this time, in order to normally carry out effective spatter removal, it is preferable to use a gas nozzle for the gas flow G so that a flow velocity of a sonic level can be obtained.

By the way, in the structure in which the gas blowing nozzle 21 is provided on the upper part of the shield box 15 as shown in FIG. 1, since the inside of the shield box 15 becomes a negative pressure, the shield box from the transmission hole 23 for the laser beam 12 is shielded. The sputter exhaust gas does not flow into the inside of the gas generator 21, and inexpensive dry air or the like is used as the gas forming the gas flow G, and a non-oxidizing gas (for example, an inert gas, etc.) is used as the shield gas only in the shield box 21. If nitrogen (carbon dioxide, etc.) is introduced in a separate system, the welding portion 19 can be processed without being oxidized.

However, as shown in FIG. 2, the metal vapor generated in the laser processing part, the laser bloom, etc. are drawn into the optical path, so that the metal vapor 24 absorbs a part of the laser beam light 12 and the welding ability. May decrease.

In such a case, the above problem can be solved by using the laser processing head shown in FIG. 3, which is another embodiment of the present invention. That is, as shown in FIG. 3, in the shield box 15, a gas blowing nozzle 26 having a nozzle hole 25 for injecting the metal vapor excluded gas 25a obliquely downward is provided at the tip of the nozzle 11 as the excluded gas blowing means. The generated metal vapor 24 and the like are excluded out of the range of the optical path of the laser beam light 12 so that the laser processing can be performed more stably.

As an example, the laser processing head shown in FIG. 3 was used to perform penetration welding under the following conditions. As a result, good backside welding without oxidation could be performed. Processing conditions Laser light: CO ₂ laser output: 6.8 kw Speed: 0.5 m / min Work piece: SUS304 material (plate thickness 9 mm) Sputter exclusion gas: Atmospheric shield gas: Nitrogen Metal vapor exclusion gas: Nitrogen

[0024]

As described above with reference to the embodiments, the laser processing head according to the present invention is provided with a gas flow spraying means to remove spatters and the like, so that the spatters and the like adhere to the condensing optical system. Can be prevented. Further, by providing an excluding gas blowing means for excluding metal vapor in the shield box of the laser processing head, it is possible to perform more stable laser processing.

[Brief description of drawings]

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

FIG. 2 is a schematic view of a laser processing head according to an embodiment of the present invention.

FIG. 3 is a schematic view of a laser processing head according to another embodiment of the present invention.

FIG. 4 is a schematic view of a laser processing head according to an example of a conventional technique.

FIG. 5 is a schematic view of a laser processing head according to another example of the prior art.

[Explanation of symbols]

 11 Nozzle 12 Laser Beam Light 13 Condenser Lens 14 Workpiece 15 Shield Box 17 Sputter 19 Welding Part 21 Gas Blowing Nozzle 22 Ejection Port 23 Permeation Hole 24 Metal Vapor 25 Nozzle Hole 26 Gas Blowing Nozzle G Gas Flow

Front Page Continuation (72) Inventor Masahiko Tsumaka 2-1-1, Niihama, Arai-cho, Takasago, Hyogo Pref., Takasago Laboratory, Mitsubishi Heavy Industries, Ltd. (72) 1-1-2-1 Niihama, Arai-cho, Takasago, Hyogo Prefecture Takasago Research Laboratory, Mitsubishi Heavy Industries Ltd. (72) Inventor Yoshiaki Shimogusu 1-1-1, Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries Ltd., Kobe Shipyard

Claims (2)

[Claims] 1. A laser machining head for concentrating a laser beam light by a condensing optical system in a shield box covering a laser machining point of a workpiece to perform machining such as welding and overlaying. A laser processing head characterized in that gas flow blowing means for blowing gas in a direction orthogonal or substantially orthogonal to the optical axis of the laser beam light is provided directly above the shield box. 2. The laser processing head according to claim 1, further comprising an expulsion gas blowing means for excluding metal vapor or the like generated at the time of laser processing outside the range of the laser optical path in the shield box. Processing head.