JP4193081B2 - Center gas nozzle for laser processing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser processing center gas nozzle for performing laser processing while supplying an assist gas to the surface of a workpiece in laser processing such as welding, cutting, drilling, and surface treatment. This relates to a gas nozzle that can prevent deterioration in processing quality due to air entrainment and the like without causing any disturbance in the flow of assist gas.
[0002]
[Problems to be solved by the invention]
As a center gas nozzle used for laser processing including laser welding, for example, Japanese Patent Laid-Open No. 7-290268 proposes a gas nozzle having a double tube structure in which an assist gas is supplied coaxially from the periphery of a laser beam. ing.
[0003]
The gas nozzle disclosed in the above publication includes an annular assist gas flow path between an inner cylinder and an outer cylinder of the nozzle, and this annular gas flow path opens into a laser passage hole formed in the nozzle inner cylinder. When the gas flow passage area at the gas merging portion where the gas flowing through the portion, that is, the annular flow passage merges with the laser passage hole is A, and the gas flow passage area at the outlet of the assist gas is B, the air above the gas merging portion is The ratio B / A of these gas flow path areas is in the range of 0.7 to 1.0 so as not to be involved in the flow of the assist gas.
[0004]
That is, in the gas nozzle disclosed in the above publication, the area ratio B / A of the gas flow paths is 1 or less, that is, the flow area A at the gas merging portion is equal to the flow area B of the outlet or is larger than the outlet area B. Since it is large, it does not involve the air above the gas junction. However, on the other hand, the assist gas flowing into the gas merging portion from the annular flow path flows not only at the outlet side in the gas merging portion, but also a part thereof on the side opposite to the outlet, so the gas flow field at the gas merging portion is Disturbance, this gas flow turbulence also affects the gas flow field at the nozzle outlet, it is difficult to completely prevent air entrainment between the nozzle exit and the processing point, and such air entrainment occurred In some cases, the processing quality may be deteriorated.
[0005]
In addition, the ratio B / A of the gas flow path area described above varies greatly even if the nozzle dimensions vary in units of 1/100 mm, so that there is a strict requirement for dimensional accuracy. There is a problem that the difference in performance is large, and the solution of such a problem has been a problem in the above-described center gas nozzle for laser processing.
[0006]
OBJECT OF THE INVENTION
The present invention has been made paying attention to the above-mentioned problems in a conventional laser processing center gas nozzle having a double tube structure, and the assist gas flow at the outlet of the nozzle is not disturbed. An object of the present invention is to provide a center gas nozzle gas nozzle for laser processing capable of stably supplying an assist gas and preventing deterioration in processing quality due to air entrainment.
[0007]
[Means for Solving the Problems]
The center gas nozzle for laser processing according to claim 1 of the present invention has a double tube structure for supplying an assist gas coaxially with the laser beam through an annular channel formed between the nozzle outer cylinder and the nozzle inner cylinder. A center gas nozzle for laser processing, wherein the flow area of the annular flow path in the gas merging portion where the assist gas flowing through the annular flow path joins the laser passage hole formed in the nozzle inner cylinder is Sm, and the assist at the nozzle outlet When the gas channel area is Se, the ratio Se / Sm of the two channel areas is 1 or more, the second gas channel is provided, and the laser passage hole for the assist gas flowing through the second gas channel is provided. The discharge port is provided on the upstream side of the gas merging portion, and this configuration in the center gas nozzle for laser processing solves the above-described conventional problems. It is the means of the eye.
[0008]
In the gas nozzle according to claim 2 as an embodiment of the center gas nozzle for laser processing according to the present invention, the annular flow path and the second gas flow path are each independently connected to the gas supply device. As an embodiment, the center gas nozzle for laser processing according to claim 3 is characterized in that the second gas flow path has an annular shape coaxial with the laser beam.
[0009]
[Effects of the Invention]
In the center gas nozzle for laser processing according to claim 1 of the present invention, the assist gas from the annular flow passage formed between the nozzle outer cylinder and the nozzle inner cylinder enters the laser passage hole formed in the nozzle inner cylinder. When the flow area of the annular flow path and the flow path area at the nozzle outlet at the joining position (gas confluence portion) are Sm and Se, respectively, the ratio Se / Sm of both flow areas is 1 or more and the second The assist gas from the second gas channel is supplied into the laser passage hole from the discharge port formed on the upstream side of the gas junction.
[0010]
That is, the ratio Se / Sm of the two flow passage areas is 1 or more, in other words, the flow passage area Se of the assist gas at the nozzle outlet is equal to the flow passage area Sm of the annular flow passage at the gas junction, or the flow passage of the annular flow passage. Since the area is larger than the area Sm, the flow of the assist gas in the gas merging portion is all directed toward the nozzle outlet side, so that the flow of the assist gas supplied to the processing point is not disturbed and is stable. Thus, the air around the processing point is not involved. At this time, a negative pressure is generated in the merging portion because all of the assist gas in the merging portion flows toward the nozzle outlet, and an amount of assist gas corresponding to the amount drawn by the negative pressure is the second amount. Since the gas is supplied from the discharge port into the laser passage hole through the gas flow path, air entrainment does not occur at the gas merging portion, and the processing quality of laser processing is improved.
[0011]
In the gas nozzle according to claim 2 as an embodiment of the center gas nozzle for laser processing according to the present invention, the annular flow path and the second gas flow path are independently connected to the gas supply device. By adjusting the supply amount of the assist gas from the second gas flow path with respect to the supply amount of the assist gas from the passage, the difference in performance based on a subtle dimensional error between individual gas nozzles will be eliminated. Similarly, in the center gas nozzle for laser processing according to claim 3 as an embodiment, the second gas flow path has an annular shape coaxial with the laser beam, so that the assist gas is uniformly supplied from the periphery of the laser beam. As a result, the assist gas flow becomes more stable, and air entrainment is more effectively prevented.
[0012]
【The invention's effect】
The center gas nozzle for laser processing according to claim 1 of the present invention includes the above-described configuration, that is, the annular flow path and the second gas flow path, and a joining portion (into the laser passage hole of the assist gas from the annular flow path ( The ratio Se / Sm of the flow passage area of the annular flow passage in the gas confluence portion and the flow passage area of the assist gas at the nozzle outlet is 1 or more, and the upstream side of the confluence portion from the second gas flow passage Since the assist gas discharge port is provided, the assist gas flow can be made stable, and air entrainment between the gas merging section and the nozzle and the processing point can be prevented. This brings about an extremely excellent effect that the processing quality can be improved.
[0013]
Further, in the gas nozzle according to claim 2 as an embodiment of the center gas nozzle for laser processing according to the present invention, the annular flow path and the second gas flow path are each independently connected to the gas supply device. Therefore, the assist gas flow rate from the annular flow channel and the assist gas flow rate from the second gas flow channel can be separately adjusted, and the second gas is compared with the assist gas amount flowing through the annular flow channel. By adjusting the gas supply amount from the flow path, it is possible to eliminate the difference in performance between the individual gas nozzles based on the dimensional difference. Similarly, in the center gas nozzle for laser processing according to claim 3, the second gas is used as an embodiment. Since the flow path has an annular shape coaxial with the laser beam, the assist gas can be supplied on the average around the laser beam. And Les more stable, leading to the effect that it is possible to prevent the entrainment of air more effectively.
[0014]
【Example】
Hereinafter, embodiments of the present invention will be described more specifically based on the drawings.
[0015]
FIGS. 1A to 1D show the structure of a laser processing center gas nozzle according to an embodiment of the present invention. FIG. 1A is a longitudinal sectional view showing the entire structure, and FIG. b) to FIG. 1 (d) are cross-sectional views taken along cutting lines BB, CC and DD shown in FIG. 1 (a), respectively.
[0016]
The center gas nozzle 1 for laser processing shown in the figure is mainly composed of a nozzle outer cylinder 2 and a nozzle inner cylinder 3, and a laser passage hole 3a through which a laser beam L passes along the axis at the center of the nozzle inner cylinder 3. The annular flow path 4 is formed concentrically with the laser passage hole 3 a provided in the nozzle inner cylinder 3 between the nozzle outer cylinder 2 and the nozzle inner cylinder 3.
[0017]
The annular flow path 4 is connected to an assist gas supply device via a gas hose (not shown) at a gas supply port 4a formed on the upper end side of the gas nozzle 1, and the annular flow path 4 is connected to the laser passage hole 3a. The assist gas is supplied coaxially with the laser beam L from the portion (gas merging portion 4b) that is open to the center.
[0018]
Further, in the embodiment, an annular second gas passage 5 having the same annular shape is similarly formed on the upper side of the annular passage 4 in the drawing (opposite the nozzle outlet 2a), that is, on the upstream side of the assist gas. The assist gas is supplied coaxially with the laser beam L from the discharge port 5b opened in the laser passage hole 3a. The gas supply port 5a to the second gas flow path 5 is connected to the gas supply device via a valve and a gas hose different from the gas supply port 4a to the annular flow path 4, The amount of assist gas flowing through the second gas flow path 5 can be freely adjusted with respect to the assist gas flowing through the path 4.
[0019]
FIG.1 (c) shows the cross section of the said gas nozzle 1 in the gas confluence | merging part 4b where the assist gas which flows through the annular flow path 4 joins the laser passage hole 3a as mentioned above, FIG.1 (d) shows the said gas nozzle. 1 shows a cross section at the nozzle outlet 2a, and in the gas nozzle 1 according to the present invention, the flow area Sm of the annular flow path 4 in the gas merging portion 4b shown in FIG. The ratio Se / Sm of the flow passage area Se at the nozzle outlet 2a shown in d) is 1 or more. In particular, in this embodiment, the flow passage area Se at the nozzle outlet 2a is slightly larger than the flow passage area Sm at the gas junction 4b. It is supposed to be.
[0020]
In the laser processing center gas nozzle 1 having such a structure, the assist gas that has flowed into the laser passage hole 3a through the annular flow path 4 has the flow area Se of the nozzle outlet 2a as a gas merging as described above. Since it is larger than the flow path area Sm in the portion 4b, as shown in FIG. 2, all the gas confluence portion 4b flows downward in the drawing, that is, toward the nozzle outlet 2a, and the flow of the assist gas is stable. Will be. At this time, since the negative pressure is generated when the flow of the assist gas in the gas merging portion 4b is all directed toward the nozzle outlet 2a, the assist gas having a flow rate corresponding to the amount drawn into the nozzle outlet 2a due to the negative pressure is supplied to the second outlet gas. By supplying into the laser passage hole 3a from the discharge port 5b through the gas flow path 5, the air in the laser passage hole 3a is prevented from being caught in the assist gas.
[0021]
Here, in order to completely prevent the entrainment of air, the assist gas supply amount from the second gas flow path 5 is adjusted to be slightly larger than the amount drawn by the negative pressure, as shown in FIG. In addition, it is necessary for the assist gas to flow also above the nozzle 1 (on the side opposite to the outlet). As a result, an upper and lower gas flow is generated at the joining portion of the assist gas from the second gas flow path 5 into the laser passage hole 3a, that is, in the vicinity of the discharge port 5b. Although turbulence occurs, the flow is rectified in the joining portion 4b of the assist gas from the annular flow path 4, so that the assist gas having a stable flow is supplied to the processing point.
[Brief description of the drawings]
FIG. 1A is a longitudinal sectional view showing the structure of a laser processing center gas nozzle according to an embodiment of the present invention.
(B) It is a cross-sectional view in the cutting line BB of Fig.1 (a).
(C) It is a cross-sectional view in the cutting line CC of FIG.
(D) It is a cross-sectional view in the cutting line DD of FIG.
FIG. 2 is an explanatory view showing the flow of assist gas in the center gas nozzle for laser processing according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Center gas nozzle for laser processing 2 Nozzle outer cylinder 2a Nozzle outlet 3 Nozzle inner cylinder 3a Laser passage hole 4 Annular flow path 4b Gas confluence part 5 Second gas flow path 5b Discharge port L Laser beam

Claims (3)

A center gas nozzle for laser processing having a double-pipe structure for supplying an assist gas coaxially with a laser beam through an annular passage formed between a nozzle outer cylinder and a nozzle inner cylinder, and flows through the annular passage. When the flow area of the annular flow path at the gas confluence where the assist gas joins the laser passage hole formed in the nozzle inner cylinder is Sm and the flow area of the assist gas at the nozzle outlet is Se, The ratio Se / Sm is 1 or more, the second gas flow path is provided, and the discharge port of the assist gas flowing through the second gas flow path to the laser passage hole is provided upstream of the gas merging portion. A center gas nozzle for laser processing, characterized by The center gas nozzle for laser processing according to claim 1, wherein the annular flow path and the second gas flow path are independently connected to the gas supply device. The center gas nozzle for laser processing according to claim 1 or 2, wherein the second gas flow path has an annular shape coaxial with the laser beam.

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