JPH04262889A - Method for laser beam machining hollow tubular body - Google Patents

Abstract

PURPOSE:To prevent the material to be machined from sticking the molten matter or the inner side of the material to be machined from damaging caused with the passing optical laser beam by making needless that any function is added to the positioning device or its peripheral equipment, and making needless the auxiliary working which is generated for filling the liquid in the inside of the tube material. CONSTITUTION:The molten matter recovering nozzle 25 having the molten matter recovering window 29 is inserted in the tube material 3. And the molten recovering window 29 is positioned at the down side of the machine portion 6. The liquid 21 which absorbs the optical laser beam 5 or makes it dispersing and attenuating is supplied from the liquid ejecting tube 26 to the molten matter recovering window 29. And at the same time with this, the laser beam maching is executed while the liquid 21 which is mixed with the recovered molten matter 13 is sucked and discharged from the liquiod recovering tube 27 through the molten matter recovering window 29.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a laser processing method for cutting, drilling, complete penetration welding, etc. by irradiating a laser beam onto a workpiece, and particularly relates to a laser processing method for cutting, drilling, complete penetration welding, etc., by irradiating a laser beam onto a workpiece, and particularly relates to a laser processing method for cutting, drilling, complete penetration welding, etc. The present invention relates to a laser processing method suitable for processing (pipe material).

0002

[Prior Art] When cutting pipe materials using a laser beam, there are problems such as adhesion of molten material generated during processing to the inner surface of the pipe material, which is the workpiece, and the problem of molten material that passes through and is not absorbed into the processing area. There was a problem that the inner surface of the pipe material was damaged by the laser beam.

Three typical conventional techniques for solving the above problems will be explained below.

The first conventional technique will be explained using FIGS. 6 and 7. FIG. 6 shows a laser processing device 1 that cuts a long pipe material into an arbitrary shape using a laser beam, and a pipe material inner surface protection device that aims to prevent melt adhesion to the inner surface of the pipe material and damage caused by passing laser light. 2.

As shown in FIG. 6, the laser processing device 1 includes:
A pipe material 3 that is a workpiece, a positioning device 4 that holds the pipe material 3 and can freely rotate it and position it in the axial direction, and a laser beam irradiation device that irradiates a laser beam 5 (other than the laser beam is not shown) (omitted), and it is possible to cut the pipe material 3 into any shape.

The pipe material inner surface protection device 2 also includes a lid member 8 that closes one opening 7 of the pipe material 3, and a processing area 6 in the pipe material 3 from the other opening 9 side of the pipe material 3. The compressed air is inserted to the far side when cutting.
It is composed of a nozzle 11 for feeding air, and a hose 12 for connecting the nozzle 11 to an air source (not shown) such as a compressor.

FIG. 7 is a sectional view of the vicinity of the processed portion 6 in FIG. 6. The pipe material inner surface protection device 2 can scatter and discharge the molten material 13 generated at the processing area 6 during cutting through the compressed air 10 that is ejected from the nozzle 11 and out of the pipe material 3. inner surface of pipe material 14
Can prevent adhesion to. Furthermore, the passing laser beam 15 that is not absorbed by the processed portion 6 is also blocked by the nozzle 11, and does not reach the inner surface 14 of the pipe material, thereby preventing damage. Furthermore, by connecting the nozzle 11 to an arm such as a robot (not shown), the nozzle 11 can be
It is also possible to use it as a rod member for recovering workpieces after separation. Such technology is disclosed in, for example, Japanese Patent Application Laid-Open No. 1-162.
It is disclosed in Japanese Patent No. 583.

However, when the inner diameter of the pipe material 3 is small, the distance from the processed part 6 to the inner surface 14 of the pipe material is short, and as shown in FIG. There was a problem in that the particles adhered to the inner surface 14 of the pipe material before being scattered and discharged. In addition, the clearance between the inner diameter of the pipe material 3 and the outer diameter of the nozzle 11 is inevitably small, and a portion of the molten material 13 adheres and accumulates on the surface of the nozzle 11 before being discharged outside the pipe material 3, resulting in long-term use. When doing so, a lump of adhered coagulum 16 formed. As a result, as described above, when the nozzle 11 is attached to an arm of a robot or the like and used as a rod member for recovering the workpiece after being cut off, the workpiece after being cut off is the coagulum adhered to the nozzle 11.
There was also the problem that the retrieval operation could not be performed normally due to the retrieval mechanism getting caught in the clump of No. 6.

Furthermore, when the inner diameter of the pipe material 3 is small, the nozzle 11 also has a small diameter and a thin wall thickness.
As shown in FIG. 2, a problem also occurred in that the passing laser beam 15 that was not absorbed by the processed part 6 created a hole 17 even in the nozzle 11 and reached the inner surface 14 of the pipe material, causing damage 18.

A second conventional technique will be explained using FIGS. 10 and 11. FIG. 10 shows the laser processing device 1 and the pipe material inner surface protection device 19. Laser processing device 1
Since the configuration is exactly the same as that of the first prior art, the explanation will be omitted. Pipe material inner surface protection device 1 in this conventional technology
Reference numeral 9 indicates a liquid supply hose 20 connected to one opening 7 of the pipe material 3, and a liquid 21 such as water to the liquid supply hose 20.
and a liquid supply source (not shown) for supplying.

FIG. 11 is a sectional view of the vicinity of the processed portion 6 in FIG. 10. Liquid 21 supplied from liquid supply hose 20
passes through the inside of the pipe material 3 and flows out from the open opening 9. By placing the liquid 21 inside the processing area 6, the molten material 13 during drilling or cutting is cooled and solidified, and is discharged outside the pipe material 3 in a state mixed with the liquid 21, so that the molten material 13 is transferred to the inner surface 14 of the pipe material. Adhesion and coagulation of the substance 13 can be prevented.

When water is used as the liquid 21, the absorption rate of CO2 laser light in water is large due to wavelength characteristics,
O2 laser light hardly passes through water and is absorbed and attenuated. Although YAG laser light has a low absorption rate for water,
Attenuated by scattering effects in water. Therefore, damage 18 to the inner surface 14 of the pipe material can be prevented or reduced. Such prior art is disclosed, for example, in Japanese Patent Application Laid-Open No. 52-8580.
This method is disclosed in Japanese Patent No. 0 and Japanese Patent Application Laid-Open No. 2-52188.

However, even in the second prior art,
When using water as the liquid 21 and processing a pipe material 3 with a small inner diameter with a YAG laser beam, there is a problem that the YAG laser beam is not sufficiently attenuated in water and reaches the inner surface 14 of the pipe material, causing damage. there were. In addition, in order to fill the inside of the pipe material 3 with the liquid 21, a large amount of man-hours were required for incidental work such as draining the liquid 21 from inside the pipe material 3 when replacing the pipe material 3 and drying the workpiece. .

In order to solve the problems of each of the above-mentioned conventional techniques, a third conventional technique that combines the first conventional technique and the second conventional technique will be explained using FIGS. 12 and 13. . FIG. 12 shows the laser processing device 1 and the pipe material inner surface protection device 22. The configuration of the laser processing device 1 is completely the same as that of the first prior art, so the explanation will be omitted. FIG. 13 is a sectional view of the vicinity of the processed portion 6 in FIG. 12.

As shown in FIGS. 12 and 13, the pipe material inner surface protection device 22 according to the third prior art uses compressed air 10 for scattering and discharging the melt 13 in the first prior art configuration. , a liquid 21 such as water is used.

When actually processing the pipe material 3, processing is performed while discharging the liquid 21 from the tip of the liquid discharging nozzle 23. As in the case of the compressed air 10 of the first prior art, the melt 13 generated during processing is cooled and solidified by the liquid 21 flowing outward inside the pipe material 3.
It is discharged outside in a mixed state. As a result, the molten material 13 generated during processing is discharged to the outside of the pipe material 3 without adhering to the inner surface 14 of the pipe material or the surface of the liquid discharge nozzle 23.

Even when water is used as the liquid 21 and YAG laser light is used for processing, the passing laser light 15 that is not absorbed by the processing area 6 reaches the surface of the liquid discharge nozzle 23, but is scattered by the liquid 21. After attenuation, even if the liquid discharge nozzle 23 has a thin wall, it is difficult to form a hole, and if processing is performed by adjusting the output of the laser beam 5, the inner surface 1 of the pipe material
It will not reach 4 and cause any damage.

[0018]

[Problem to be Solved by the Invention] However, in the case of the third prior art described above, it is necessary to add a waterproof function to the positioning device 4 and its peripheral devices, which imposes very severe restrictions on the design and manufacture of the device. There was a problem in that the equipment was expensive. In addition, in order to fill the inside of the pipe material 3 with the liquid 21, the work of closing one opening 7 of the pipe material 3 with the lid member 8, the work of draining the liquid 21 from the inside of the pipe material 3 when replacing the pipe material 3, A large number of man-hours were required for incidental work such as drying the workpiece after processing.

The present invention has been made in view of the problems of the prior art, and it achieves the following without impairing the effects of the prior art.
The purpose of the present invention is to provide a method for laser processing a hollow tubular body, which does not require adding waterproof functionality to the positioning device or its peripheral equipment, and does not require a large amount of additional work required to fill the inside of the pipe material with liquid. do.

[0020]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a laser processing method for a hollow tubular body in which the hollow tubular body is irradiated with a laser beam to perform processing such as cutting. The melt recovery nozzle has a melt recovery window that opens toward the workpiece and can be used to recover the workpiece after separation.
The hollow tubular body is inserted into the hollow tubular body through the opening at one end thereof, and after the melt recovery window is located below the processing area of the hollow tubular body, the melt is recovered by communicating with the melt recovery window. A liquid that absorbs or scatters and attenuates the laser beam is supplied from at least one liquid discharge pipe provided in the nozzle to the melt recovery window, and at the same time, at least one liquid discharge pipe provided in the melt recovery nozzle communicates with the melt recovery window. We decided to carry out laser processing while sucking and discharging the liquid mixed with the melt collected through the melt collection window using the main liquid collection pipe.

[0021]

[Operation] Liquid is supplied from at least one liquid discharge pipe to the melt recovery window of the melt recovery nozzle inserted inside the processing part of the hollow tubular body, and the melt generated during processing is cooled by the liquid. , to solidify and prevent the melt from adhering to the inner surface of the hollow tubular body or the melt collection nozzle. Furthermore, by suctioning and discharging the liquid through at least one liquid recovery pipe, the solidified molten material is reliably discharged from the hollow tubular body while being mixed in the liquid. Furthermore, the passing laser light that was not absorbed by the processing area is also absorbed or attenuated by scattering by the liquid, and furthermore, the scattered and attenuated laser light is blocked and absorbed by the melt recovery nozzle, so that it is not absorbed by the processing area. It is also possible to prevent damage to the inner surface of the tubular hollow body facing the processed area due to the passing laser beam.

[0022]

[Example 1] FIG. 2 shows the configuration of the melt recovery device 24 (corresponding to the pipe material inner surface protection device in the example) of the device used in Example 1 of the laser processing method according to the present invention, and the laser processing device 1. This shows the main parts. The configuration of the laser processing apparatus 1 in FIG. 2 is completely the same as that of the prior art, so the explanation will be omitted. FIG. 2 shows a state in which cutting is being performed while irradiating the laser beam 5 to the processed portion 6 of the pipe material 3.

FIG. 1 shows the melt recovery nozzle 2 in the melt recovery device 24 when cutting is being performed while irradiating the processed portion 6 of the pipe material 3 with the laser beam 5 in FIG.
5 shows a cross-sectional view near the processing point No. 5.

FIG. 3 shows a partial sectional view of the melt recovery nozzle 25.

As shown in FIGS. 1 and 3, the structure of the melt recovery nozzle 25 of this embodiment is such that a liquid (ordinary water) 21 is discharged from the liquid discharge pipe 26 to the outside of the liquid discharge pipe 26.
A liquid recovery tube 27 having an annular cross section for recovering liquid is arranged in a double structure. The end surface of the liquid recovery tube 27 on the side to be inserted into the pipe material 3, which is the workpiece, is connected to the lid member 2.
It is blocked at 8. Also, the lid member 28 of the liquid recovery pipe 27
A melt recovery window 29 is bored upward in the vicinity of the end face on the side closed by. This lid member 28 is made of a so-called rubber plug or the like. Melt collection window 29
is provided in the vicinity between the tip of the liquid discharge tube 26 and the lid member 28.

As shown in FIG. 2, the liquid discharge pipe 26 is connected to a liquid tank (not shown) or a liquid discharge pump (not shown) via a liquid discharge hose 31 connected to the base end 30 of the melt recovery nozzle 25. The liquid recovery pipe 27 is connected to a liquid recovery tank (not shown) and a suction pump (not shown) via a liquid recovery hose 32.

When processing the pipe material 3 with the processing apparatus equipped with the melt recovery device 24 having the above configuration, as shown in FIG. Insert the melt recovery nozzle 25 from the part 9 and process the part 6.
The melt recovery window 29 of the liquid recovery nozzle 25 is positioned directly below the melt recovery nozzle 25 . During machining, the laser beam 5 is irradiated onto the machining area 6 for cutting. During this cutting, a liquid 21 that absorbs or scatters and attenuates the passing laser beam 15 that is not absorbed by the machining area 6 is supplied to the liquid discharge pipe 2.
Processing is performed while discharging liquid from the liquid discharge port 33 of No. 6.

The liquid 21 discharged from the liquid discharge port 33 cools and solidifies the melt 13 entering from the melt recovery window 29 of the melt recovery nozzle 25. And liquid 2
1 is collected into a liquid recovery tank through a liquid recovery pipe 27 connected to a suction pump in a state in which the solidified melt 13 is mixed therein. As a result, the molten material 13 generated during processing is collected into the liquid recovery tank without adhering to the inner surface 14 of the pipe material, the surface of the liquid discharge pipe 26, the inside of the liquid recovery pipe 27, etc.

At this time, the amount of liquid 21 to be discharged and the amount of suction for recovering liquid 21 are as follows:
Adjust so that 1 does not overflow. In addition, assist gas is used during cutting, but in that case, the assist gas that has passed through the processing point causes the liquid surface to ripple, causing the molten material collection window 29
If the liquid 21 overflows to the outside, move the outer diameter of the melt recovery nozzle 25 closer to the inner surface of the pipe material 3, which is the workpiece, or move the melt recovery window 29 closer to the processing point.
It is preferable to prevent the liquid 21 from overflowing.

Furthermore, the passing laser beam 15 that is not absorbed by the processing area 6 is absorbed or attenuated by scattering by the liquid 21, and although it may damage the liquid recovery pipe 27, it is unlikely to cause a through hole to be formed. . Therefore, the laser beam 1 that passed through the inner surface 14 of the pipe material and was not absorbed by the processed portion 6
5 will not cause any damage.

According to this embodiment, since the liquid 21 mixed with the cooled and solidified melt 13 is recovered by the liquid recovery pipe 27 of the melt recovery nozzle 25, there is a tray for the liquid 21 near the processing point. This is no longer necessary, and the device is no longer contaminated by splashes of the liquid 21. Also, liquid 2 is applied to the inner surface 14 of the pipe material.
1 does not come into contact with the inner surface 14 of the pipe material wetted by the liquid 21, the solidified molten material 13 adheres to the inner surface 14 of the pipe material and there is no contamination due to the liquid 21 itself, so there is no need to clean the workpiece after processing. It can be passed on to the next process, which has a great effect on reducing man-hours.

Furthermore, after the workpiece processing is completed, if the supply of the liquid 21 is stopped and all of the liquid 21 in the liquid discharge pipe 26 and the liquid recovery pipe 27 is recovered by the liquid recovery pipe 27,
As in the past, by connecting the melt recovery nozzle 25 to an arm of a robot (not shown) or the like, the melt recovery nozzle 25 can be operated while the workpiece after cutting is hooked to the melt recovery nozzle 25. It is also possible to respond to automation by using the rod as a collection rod member for the workpiece after cutting and delivering the workpiece after cutting and separation to the discharge section and the stocker section.

In this embodiment, an example of cutting has been described, but it goes without saying that the present invention can also be applied to hole drilling, complete penetration welding, and the like.

Further, in this embodiment, ordinary water is used as the liquid 21, but the liquid is not limited to water as long as it absorbs or scatters and attenuates the laser beam 5. Further, the liquid recovery pipe 27 is not limited to an annular cross section, and may be a square or other hollow tubular body. The lid member 28 is not limited to a rubber stopper or the like, and the lid member 28 is not limited to a rubber plug or the like, and the lid member 28 is used to store the liquid 2 discharged from the liquid discharge pipe 26.
Any material, shape, etc. may be used as long as it can withstand the pressure of 1. The melt recovery window 29 may be provided above the main body of the liquid discharge tube 26 instead of being provided between the tip of the liquid discharge tube 26 and the lid member 28. Furthermore, the liquid 21 recovered by the liquid recovery pipe 27 is passed through a filter or the like to remove the melt 13, and the liquid 21 is purified.
It may be regenerated and returned to the liquid tank for use again.

In this embodiment, the structure of the melt recovery nozzle 25 is such that the liquid recovery tube 27 is disposed outside the liquid discharge tube 26, but on the contrary, the liquid discharge tube is disposed outside the liquid recovery tube. I don't mind. In addition, in this embodiment, the liquid discharge pipe 2
6 and the liquid recovery tube 27 are constructed with a double structure of two hollow tubular bodies, but if they have the same function, the maximum outer diameter of the melt recovery nozzle is the inner diameter of the hollow tubular body that is the workpiece. If the melt recovery nozzle has a smaller diameter than the molten metal recovery nozzle, and has a melt recovery window (recess) that opens upward at its tip, and two pipes leading to the melt recovery window are provided in the melt recovery nozzle. , the pipes may be arranged in parallel. One of the two pipes is used as a liquid discharge pipe to supply liquid to the melt recovery window, and the other pipe is used as a liquid recovery pipe to collect the liquid by suction. Alternatively, two or more pipes may be provided, and one of the pipes may function as a liquid discharge pipe or a liquid recovery pipe.

[0036]

[Embodiment 2] The apparatus used in this embodiment is completely the same as in Embodiment 1 except for the structure of the melt recovery nozzle 25, so a description thereof will be omitted.

The structure of the melt recovery nozzle 25 in this embodiment will be explained using FIG. 4. The melt recovery nozzle 25 of this embodiment differs from that of the first embodiment in that the liquid discharge port 33 faces upward. In order to make such a configuration possible, the liquid discharge pipe 34 is arranged to the back side of the melt recovery window 29, and the end of the liquid discharge pipe 34 is closed with a lid member 35. The upper part of the liquid discharge pipe 34 located below the melt recovery window 29 is open, and a liquid discharge port 33 is formed.

In the first embodiment, when the suction amount is too large for the discharge amount of the liquid 21, the amount of the liquid 21 existing below the melt recovery window 29 decreases, and the melt does not enter the melt recovery nozzle 25. 13 or the passing laser beam 15 that is not absorbed by the processing area 6 is not sufficiently attenuated by the liquid 21 and damages and penetrates the melt recovery nozzle 25, damaging the pipe material 3 that is the workpiece. There is a risk. Therefore, it is necessary to appropriately adjust the amount of discharge and suction of the liquid 21.

However, in this embodiment, since the liquid discharge port 33 is configured to open upward, only the liquid 21 overflowing from the liquid discharge port 33 is suctioned and collected by the liquid recovery pipe 27. be done. Therefore, even if the amount of liquid 21 to be discharged is small, as long as the liquid 21 is discharged, the liquid 21 below the melt recovery window 29 is secured to the liquid discharge port 33 . Further, the suction amount may be set to a certain level or more so that the liquid 21 does not overflow from the melt recovery window 29. That is, in this embodiment, compared to the first embodiment, there is an effect that the amount of discharge and suction of the liquid 21 can be easily adjusted.

[0040]

Embodiment 3 The apparatus used in this embodiment is completely the same as in Embodiment 1 except for the structure of the melt recovery nozzle 25, so a description thereof will be omitted.

The structure of the melt recovery nozzle 25 in this embodiment is characterized in that the opening area of the liquid discharge port 33 in the second embodiment is increased. There are two methods of increasing the opening area of the liquid discharge port 33: a method of simply increasing the opening area of the liquid discharge port 33, and a method of providing a plurality of liquid discharge ports 33 or more.
There is a method of increasing the area of the liquid discharge ports 33 as the total area.

The configuration of the melt recovery nozzle 25 in this embodiment will be explained using FIG. 5. Simply liquid discharge port 33
The case where the opening area is enlarged is the same as Example 2 except for the area of the liquid ejection ports 33, so the case where a plurality of liquid ejection ports 33 or more are provided will be described with reference to FIG. In FIG. 5, the number of liquid discharge ports 33 provided upward in the liquid discharge pipe 36 is two, but there may be three or more. Furthermore, any one of the plurality of liquid discharge ports 33 may be located below the melt recovery window 29 .

In the second embodiment, when attempting to adjust the discharge amount, if the discharge flow rate is increased more than necessary, the liquid 21 will be spouted upward from the liquid discharge port 33 which is opened upward. . Further, even if the discharge pressure fluctuates and the discharge flow rate increases due to some reason, such as a fluctuation in the output of the discharge pump, the liquid 21 will be spouted upward from the liquid discharge port 33.

However, as in this embodiment, the liquid discharge port 3
By enlarging the opening area of 3, even when the discharge flow rate increases, the ejection height of the liquid 21 can be kept lower than in the case of the second embodiment. Therefore, it becomes easier to adjust the discharge amount, and there is an effect that an increase in the discharge flow rate due to fluctuations in the discharge pressure can be tolerated.

[0045]

As described above, according to the present invention, when laser processing a hollow tubular body, which is a workpiece having a relatively small diameter, it is possible to prevent melt from adhering to the inner surface of the hollow tubular body and to improve the processing area. Although liquids such as water are used to prevent damage caused by transmitted laser light that is not absorbed by the device, there is no need to add waterproofing to the positioning device or its peripheral devices, so it is possible to use inexpensive laser processing when designing and manufacturing the device. equipment can be provided. In addition, since the inside of the pipe material is not filled with liquid, it is necessary to close one opening of the pipe material with a lid member,
Additional work such as drying the workpiece after processing and draining liquid from inside the pipe material when replacing the pipe material is no longer necessary, and a large amount of man-hours can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the vicinity of a processing portion of a melt recovery nozzle of a melt recovery device in a processing apparatus used in Example 1 of the present invention.

FIG. 2 is a perspective view showing the main components of a laser processing device and a melt recovery device in the processing device used in Example 1 of the present invention.

FIG. 3 is a partially cutaway perspective view of the melt recovery nozzle used in Example 1 of the present invention.

FIG. 4 is a partially cutaway perspective view of a melt recovery nozzle used in Example 2 of the present invention.

FIG. 5 is a partially cutaway perspective view of a melt recovery nozzle used in Example 3 of the present invention.

FIG. 6 is a perspective view showing the main components of a laser processing device and a pipe inner surface protection device in the processing device used in the first conventional technique.

7 is a longitudinal cross-sectional view showing the vicinity of a processing region of the apparatus shown in FIG. 6. FIG.

8 is a longitudinal cross-sectional view showing the vicinity of a processing region of the apparatus shown in FIG. 6. FIG.

9 is a longitudinal cross-sectional view showing the vicinity of a processing region of the apparatus shown in FIG. 6. FIG.

FIG. 10 is a perspective view showing the main components of a laser processing device and a pipe inner surface protection device in the processing device used in the second prior art.

FIG. 11 is a longitudinal sectional view showing the vicinity of a processing region of the apparatus shown in FIG. 10;

FIG. 12 is a perspective view showing the main components of a laser processing device and a pipe inner surface protection device in a processing device used in the third conventional technique.

FIG. 13 is a longitudinal sectional view showing the vicinity of a processing region of the apparatus shown in FIG. 12;

[Explanation of symbols]

1 Laser processing equipment 3 Pipe material 4 Positioning device 5 Laser light 6 Processing part 7 Opening 8 Lid member 9 Opening 13 Melt 14 Inner surface of pipe material 15 Passing laser beam 21 Liquid 24 Melt recovery device 25 Melt collection nozzle 26 Liquid discharge pipe 27 Liquid recovery pipe 28 Lid member 29 Melt collection window 31 Liquid discharge hose 32 Liquid recovery hose 33 Liquid discharge port 34 Liquid discharge pipe 35 Lid member 36 Liquid discharge pipe

Claims (1)

[Claims] [Claim 1] A method for laser processing a hollow tubular body, in which a hollow tubular body is irradiated with a laser beam to perform processing such as cutting,
A melt recovery nozzle having a melt recovery window opened upward at its tip is inserted into the hollow tubular body through an opening at one end of the hollow tubular body, and the melt recovery window is inserted into the hollow tubular body. Supplying a liquid that absorbs or scatters and attenuates laser light to the melt recovery window from at least one liquid discharge pipe provided in the melt recovery nozzle and communicated with the melt recovery window after being positioned below the processing area. At the same time, at least one liquid recovery pipe connected to the melt recovery window and provided inside the melt recovery nozzle sucks and discharges the liquid containing the melt collected through the melt recovery window, while the laser A method for laser processing a hollow tubular body.