JPH07223086A - Assist gas nozzle for laser beams welding - Google Patents

Abstract

PURPOSE:To prevent the entrapment of the purge air associated with the injection of the assist gas by providing an assist gas feeding passage and a communicating mechanism of an air curtain crossing the laser beams on a machining head. CONSTITUTION:The laser beams L is reflected by a bend mirror 3 in a machining head 2 through a transmission tube 5, and converged by a converging mirror 4, and a work W is irradiated with the laser beams through a nozzle 1. The assist gas A which is the inert gas is fed to the nozzle 1, and an air curtain C crossing the laser beams L at the flow speed equal to or larger than the flow speed of the assist gas A is formed by the air injection from an injection port 17. This air curtain C prevents the purge air P in the machining head 2 from entering the nozzle tip side. The atmospheric air is introduced from an air introducing port 19 into a tapered part 11 to make the flow in the tapered part 11 smooth, and to exhaust the air from an exhaust port 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding assist gas nozzle used to supply an assist gas coaxially with a laser beam during laser welding.

[0002]

2. Description of the Related Art In assist gas nozzles for laser welding, there are a center gas method and a side gas method as an assist gas supply method. Particularly, in the center gas method, the adjustment is easy because the gas is supplied coaxially with the laser beam. There is.

Further, the assist gas nozzle for laser welding has two functions. The first is to supply an inert gas to the processing point to create an inert atmosphere around the processing point to prevent the oxidation of the weld and blow off the plasma generated at the processing point to efficiently transfer the laser energy to the work piece. It is a function to let.

Another function is protection of an optical system (light collecting system). Fume and spatter are generated during laser welding, and these may enter the processing head and damage the optical system. Therefore, fumes and spatters are prevented from entering the processing head by ejecting gas from the nozzle.

Conventionally, there have been center gas type assist gas nozzles for laser welding as shown in FIGS. 5 and 6.

An assist gas nozzle 100 for laser welding shown in FIG. 5 has a taper shape with the small diameter side as the tip, and is provided with an assist gas intake 101 at a position close to the base end, and the machining head 102 has a tip. Is attached with the face down. The processing head 102 is a bend mirror 103.
A condenser mirror 104 is provided, and the condenser mirror 104 is attached to an end portion of a transmission pipe 105 guided from an oscillator (not shown), and a space between the transmission pipe 105 and the transmission pipe 105 is sealed by a partition window 106.

The laser light L passes from the oscillator through the transmission pipe 105, is reflected by the bend mirror 103 in the processing head 102, is then condensed by the condenser mirror 104, and the nozzle 100
The workpiece W is irradiated through the through. At this time, the transmission pipe 1
Purge air (indicated by arrow P) that is dry air is supplied to the inside of 05, and assist gas (indicated by arrow A) that is an inert gas is supplied from the intake port 101. As a result, the assist gas is supplied from the nozzle 100 toward the processing point Q, and the assist gas is also supplied into the processing head 102, so that the mirrors 103 and 104 are protected by the assist gas.

The assist gas nozzle 100 for laser welding shown in FIG. 6 has a double structure having an assist gas supply passage 108 opened at the nozzle tip side by providing an inner wall 107 concentric with the nozzle 100 inside. It has become. The machining head 102 has no partition window and is in communication with the transmission pipe 105. In this case, the inside from the oscillator to the processing head 102 is protected by purge air (P), and the assist gas (A) is supplied toward the processing point Q.

[0009]

By the way, in the conventional assist gas nozzle for laser welding as described above, when the processing head 102 having the window 106 is used,
The partition window 106 absorbs the heat of the laser light and becomes a convex lens due to the thermal lens effect, and as shown in FIG. 7, the focal length of the condensing system changes over time, which causes a problem that welding conditions change during processing. In the case of the double structure including the assist gas supply passage 108, the negative pressure region M is generated in the nozzle 100 by the ejection of the assist gas from the tip of the nozzle, whereby the welded portion is oxidized because the purge air is involved. However, there has been a problem of solving these problems.

[0010]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to the above-mentioned conventional problems, and it is a processing head in which the focal length of a focusing system does not change with time, that is, it is opened to the oscillator side and purge air is used. An object of the present invention is to provide an assist gas nozzle for laser welding, which can prevent the entrainment of purge air that accompanies the injection of the assist gas in the nozzle attached to the processing head supplied.

[0011]

According to another aspect of the present invention, there is provided an assist gas nozzle for laser welding, which is mounted on a processing head having a converging system including a mirror and which supplies the assist gas coaxially with a laser beam. In the above, the configuration is provided with an assist gas supply path opened to the nozzle tip side and an air curtain flow mechanism that traverses the laser light from the processing head at a flow velocity equal to or higher than the flow velocity of the assist gas. It is used as a means to solve the problem.

The assist gas nozzle for laser welding according to the present invention is mounted on a processing head having a converging system by a mirror as claimed in claim 2, and the nozzle supplying the assist gas coaxially with the laser beam has a small diameter side. The taper portion with the tip as an end is provided with an assist gas supply path that is continuous over the circumferential direction of the nozzle and is open to the tip end side of the nozzle, and the base end portion that is mounted on the machining head has a flow velocity of the assist gas equal to or equal to The laser welding according to claim 2, further comprising: an injection port that forms an air curtain that traverses the laser beam from the processing head at the above flow rate, and an exhaust port that faces the injection port. In the assist gas nozzle, the air introduction port is provided at a position adjacent to the nozzle tip side of the injection port, and the above configuration solves the problem. And a means for.

Further, the assist gas nozzle for laser welding according to the present invention is mounted on a processing head having a converging system by a mirror as claimed in claim 4, and the nozzle supplying the assist gas coaxially with the laser beam has a small diameter side. And a block portion on the base end side that is mounted on the processing head, and the taper portion has an assist gas supply path that is continuous over the circumferential direction of the nozzle and is open to the nozzle tip side, The block is provided with a groove which is open at both ends and communicates with the inside of the machining head and the tapered portion, and one end of the groove traverses the laser beam from the machining head at a flow velocity equal to or higher than the flow velocity of the assist gas. An air outlet that forms an air curtain and an air inlet that opens at a position adjacent to the nozzle tip side of the air outlet are provided, and the other end of the groove is ejected. And the air inlet to the opposing outlet and the configured and has, and a means for solving the problems of the above-described configuration.

[0014]

In the assist gas nozzle for laser welding according to the first aspect of the present invention, while the assist gas is supplied from the nozzle tip toward the processing point, the laser beam has a flow rate equal to or higher than the flow rate of the assist gas. The air curtain that traverses the nozzle prevents the purge air in the processing head from entering the nozzle tip side.

In the assist gas nozzle for laser welding according to the second aspect of the present invention, the assist gas is supplied from the tip of the nozzle toward the processing point through the assist gas supply passage which is continuous in the circumferential direction of the nozzle and is open to the tip side of the nozzle. While supplying, at the base end portion, by ejecting air at a flow velocity equal to or higher than the flow velocity of the assist gas from the injection port to form an air curtain that traverses the laser light, and by discharging this from the exhaust port, The purge air in the processing head is prevented from entering the nozzle tip side, and the entrainment of air in the nozzle due to the injection of the assist gas is prevented.

In the assist gas nozzle for laser welding according to a third aspect of the present invention, in addition to the structure of the first aspect, an air introduction port is provided at a position adjacent to the nozzle tip side of the injection port. By introducing outside air into the nozzle with a flow to smooth the flow inside the nozzle tip and discharging them from the exhaust port, the purge air in the processing head is prevented from entering the nozzle tip side, and the assist gas is injected. More reliably prevent entrainment of air in the nozzle involved.

In the assist gas nozzle for laser welding according to claim 4 of the present invention, the injection port and the introduction port are provided at one end of the groove provided in the block portion on the base end side, and the exhaust port is provided at the other end. As a result, the flow of the air curtain is always uniform.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the assist gas nozzle for laser welding of the present invention will be described below with reference to the drawings.

That is, the assist gas nozzle 1 for laser welding shown in FIG. 1 is mounted on a processing head 2 having a converging system by a mirror and supplies the assist gas coaxially with the laser beam L. The processing head 2 includes a bend mirror 3 and a condenser mirror 4, is attached to an end portion of a transmission pipe 5 guided from an oscillator (not shown), and communicates with the inside of the transmission pipe 5.

As shown in FIG. 2, the nozzle 1 is provided with a taper portion 11 whose tip is on the small diameter side and a block portion 12 on the base end side which is mounted on the machining head 2. Tapered part 12
Is provided with an assist gas intake 13 at its base end and an inner wall 14 concentric with the nozzle 1 inside so that it is continuous in the circumferential direction of the nozzle and is open to the nozzle tip side. It has a double structure having an assist gas supply passage 15.

The block portion 12 is open at both ends and communicates with the machining head 2 and the inside of the taper portion 11.
Have six. At the center of the bottom of the groove 16, the tapered portion 11
An opening (not shown) through which the laser light L passes is provided in a communicating portion with the, and an injection port 17 that constitutes a circulation mechanism of the air curtain is provided in an upper half of the one end of the groove 16. The block 18 is fitted. Thereby, the groove 1
An air introduction port 19 that opens at a position adjacent to the nozzle tip side of the injection port 17 is formed in the lower half of one end of the nozzle 6.

The injection port 17 has a slit shape so as to form an air curtain that traverses the laser beam L, and a connecting portion 17a of an air hose (not shown) is continuously provided. Further, the other end of the groove 16 is opened as an exhaust port 20 which constitutes a circulation mechanism of the air curtain and faces the injection port 17 and the air introduction port 19.

Assist gas nozzle 1 for laser welding described above
In the welding machine equipped with the laser beam L, the laser beam L is reflected from the oscillator through the transmission pipe 5, is reflected by the bend mirror 3 in the processing head 2, is then focused by the focusing mirror 4, and is passed through the nozzle 1 to be processed W. Is irradiated.

At this time, purge air (indicated by arrow P in FIG. 1) which is dry air is supplied into the transmission pipe 5,
The purge air P is also supplied to the processing head 2 to protect the mirrors 3 and 4 from dust and the like. Further, since the inside of the transmission pipe 5 and the inside of the processing head 2 are in communication with each other and there is no partition window (see reference numeral 106 in FIG. 5 which is a conventional example) between them, the focal length of the focusing system changes with time. And the welding conditions during processing are kept constant.

Further, the nozzle 1 is equipped with the purge air P.
In addition to the above, the assist gas (indicated by arrow A in FIG. 1) which is an inert gas is supplied from the intake port 13 and the injection port 1
Air jets from 7 form an air curtain C in the groove 16 that traverses the laser light L at a flow velocity equal to or higher than the flow velocity of the assist gas A.

As a result, the assist gas A is supplied from the nozzle tip toward the processing point Q of the workpiece W through the assist gas supply passage 15, while the purge air P in the processing head 2 is supplied to the nozzle by the air curtain C. As shown in FIG. 3, outside air is introduced into the taper portion 11 from the air introduction port 19 by the flow of the air curtain C to make the flow in the taper portion 11 smoother. And exhaust all of them through the exhaust port 20.

Therefore, around the processing point Q, the assist gas A creates an inert atmosphere to prevent oxidation of the welded portion, and the assist gas A also causes fumes and spatter generated during laser welding to enter the nozzle 1. Of the taper portion 1 which is obtained by the air curtain C.
The flow in 1 more reliably prevents the purge air P from being entrained by the injection of the assist gas A.

Further, since the air curtain C is formed in the groove 16 of the block portion 12, its flow is always uniform, and the function of preventing the purge air P from entering the nozzle tip side is kept stable. Be drunk

Further, even if the spatter generated during welding enters the nozzle 1, the spatter S is discharged from the exhaust port 20 by the flow of the air curtain C as shown in FIG. Since it does not enter, there is no concern that the mirrors 3, 4 will be damaged by the spatter S.

[0030]

As described above, according to the assist gas nozzle for laser welding according to the first and second aspects of the present invention, the machining head, that is, the oscillation, in which the focal length of the focusing system does not change with time. In the nozzle attached to the processing head that is opened to the machine side and supplied with purge air, the air curtain prevents the purge air from entering the nozzle tip side, and the purge air is entrained when the assist gas is jetted from the nozzle tip. Can be prevented, oxidation of the welded portion can be reliably prevented, and welding quality can be improved. Further, the air curtain can prevent spatters and the like from entering the processing head through the nozzle, and can also contribute to protection of the light collecting system in the processing head.

According to the assist gas nozzle for laser welding of the third aspect of the present invention, the outside air is introduced also from the air introduction port by the flow of the air curtain, and the flow from the tip of the nozzle to the exhaust port is made smoother. Further, it is possible to more reliably prevent the entrainment of the purge air due to the injection of the assist gas and the intrusion of the spatter into the processing head.

According to the assist gas nozzle for laser welding of the fourth aspect of the present invention, in addition to the effects obtained from the configurations of the first to third aspects, the air curtain is formed in the groove of the block portion. The flow is always uniform,
With this air curtain, the function of preventing the purge air from entering the nozzle tip side and the function of preventing the spatter and the like from entering the processing head can be maintained in a stable state.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of an assist gas nozzle for laser welding according to the present invention.

2 is a perspective view showing the injection port and the air introduction port side of the assist gas nozzle for laser welding shown in FIG. 1 (a), a perspective view showing the exhaust port side (b), and a cross-sectional view of the injection port portion (c). Is.

FIG. 3 is a cross-sectional view illustrating flows of assist gas, an air curtain, introduced air, and purge air in the assist gas nozzle for laser welding shown in FIG.

FIG. 4 is a cross-sectional view of a laser welding assist gas nozzle for explaining the action when spatter generated during welding enters the nozzle.

FIG. 5 is a cross-sectional view illustrating a conventional assist gas nozzle for laser welding.

FIG. 6 is a cross-sectional view illustrating another example of a conventional assist gas nozzle for laser welding.

FIG. 7 is a graph showing a change with time of a focal length of a focusing system during welding.

[Explanation of symbols]

 1 Nozzle 2 Processing Head 3 Bend Mirror 4 Condensing Mirror 11 Tapered Part 12 Block Part 15 Assist Gas Supply Channel 16 Groove 17 Injection Port (Air Curtain Circulation Mechanism) 19 Air Inlet Port 20 Exhaust Port (Air Curtain Circulation Mechanism) A Assist gas C Air curtain L Laser light

Claims (4)

[Claims] 1. A nozzle, which is mounted on a processing head having a converging system with a mirror and which supplies an assist gas coaxially with a laser beam, has an assist gas supply path opened to the nozzle tip side, and an assist gas flow rate. An assist gas nozzle for laser welding, comprising an air curtain flow mechanism that traverses a laser beam from a processing head at a flow velocity equal to or higher than that. 2. A nozzle, which is mounted on a processing head having a converging system by a mirror and which supplies an assist gas coaxially with a laser beam, has a taper portion whose tip is on the small diameter side and which is continuous in the circumferential direction of the nozzle. In addition to having an open assist gas supply path on the nozzle tip side, an air curtain that crosses the laser beam from the processing head at a flow velocity equal to or higher than the flow velocity of the assist gas is formed at the base end part attached to the processing head. An assist gas nozzle for laser welding, comprising: 3. The assist gas nozzle for laser welding according to claim 2, wherein an air introduction port is provided at a position adjacent to the nozzle tip side of the injection port. 4. A nozzle, which is mounted on a processing head having a mirror focusing system and supplies an assist gas coaxially with a laser beam, has a taper portion whose tip is on the small diameter side, and a base end which is mounted on the processing head. Side block portion, the taper portion is provided with an assist gas supply path that is continuous over the circumferential direction of the nozzle and is open to the nozzle tip side, and the block portion is open on both end sides and includes the machining head and the taper portion. An injection port that forms an air curtain that crosses the laser light from the processing head at a flow velocity equal to or higher than the flow velocity of the assist gas at one end of the groove, and the nozzle tip side of the injection port And an air inlet opening at a position adjacent to the air inlet, and the other end of the groove is an exhaust outlet opposed to the injection inlet and the air inlet. Cyst gas nozzle.