JP2006035283A - Laser processing method and laser processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a melt from scattering and adhering to a surface of a workpiece when piercing a workpiece, and to provide a protective film when piercing a workpiece having a protective film attached to the surface. Prevent fear of peeling.
The workpiece W is irradiated with laser light from a nozzle 16 of a machining head 15 and an assist gas is injected to pierce the workpiece W. In this case, the shielding sheet 23 is interposed between the nozzle 16 and the workpiece W, and piercing is performed through the shielding sheet 23 in a state where the shielding sheet 23 is in contact with the workpiece W.
[Selection] Figure 2

Description

  The present invention relates to a laser processing method and a laser processing apparatus for performing laser processing on a workpiece with laser light.

  In this type of laser processing apparatus, when laser processing such as piercing or cutting is performed on a workpiece, an assist gas is injected along with the irradiation of laser light from the nozzle of the processing head.

  However, for example, when laser processing is performed on a workpiece made of stainless steel or the like having a mirror-finished surface, if oxygen is used as the assist gas, the processed portion of the workpiece and its surroundings change to black due to oxidation, and the workpiece The commercial value of the product is significantly reduced. For this reason, when performing laser processing on such a mirror-finished workpiece, an inert gas such as nitrogen is used as an assist gas. Here, in the case of piercing, the melt rises to the upper surface side of the workpiece, but when an inert gas is used as an assist gas, the melt is formed to continue in a branch shape starting from the piercing portion. Is done. For this reason, it is necessary to remove it after the completion of piercing, but at this time, it is necessary to prevent the surface of the work from being damaged, which is troublesome. This is the first conventional problem.

  In addition, a stainless steel or the like mirror-finished as described above is generally protected by attaching a protective film made of synthetic resin or the like to the surface so as not to damage the surface. When piercing is applied to a workpiece having such a structure, the protective film is melted by the laser beam, and the protective film is peeled off from the workpiece by a large amount of assist gas flowing so as to be reversed to the upper surface side of the workpiece in that state. Then, the assist gas may enter between the protective film and the workpiece, and the peeling area of the protective film may be expanded. This is the second conventional problem.

  In order to deal with the first problem as described above, for example, laser processing apparatuses disclosed in Patent Document 1 and Patent Document 2 have been proposed. That is, in the processing apparatus of Patent Document 1, a cylindrical hood is disposed on the outer periphery of the processing head so as to be movable up and down. When the workpiece is pierced, the hood is moved from the raised position to the lowered position so as to surround the peripheral area in the vicinity of the laser irradiation position on the workpiece, and the melt generated during piercing is confined in the hood. It is designed not to scatter around.

  Further, in the laser processing apparatus of Patent Document 2, a short cylindrical mask having a through-hole in the processing head can be moved between a processing position that contacts the workpiece in correspondence with the nozzle and a standby position away from the processing position. It is supported. When piercing the workpiece, the workpiece is irradiated with laser light from the nozzle through the through hole of the mask while the mask is moved to the processing position, and the melt generated during the piercing is received on the mask. It is supposed to be done.

  Further, in order to cope with the second problem, for example, laser processing apparatuses and processing methods disclosed in Patent Document 3 and Patent Document 4 have been proposed. That is, in the processing method of Patent Document 3, when piercing a workpiece with a protective film, first, the laser beam is moved to the workpiece processing position with the processing head spaced apart from the workpiece by a predetermined amount as compared with normal processing. A protective film is baked on the work by irradiating light weakly. Subsequently, piercing is performed by irradiating the processing position of the workpiece with laser light in a state where the processing head is disposed opposite to the normal processing state with respect to the workpiece. Thereby, peeling of the protective film accompanying spraying of the assist gas at the time of piercing is prevented.

In the processing apparatus of Patent Document 4, a fixed nozzle is attached to the tip of the processing head, and an idle nozzle is disposed in the fixed nozzle so as to be able to advance and retreat in the axial direction by the pressure of the assist gas. An ejection port through which laser light and assist gas can pass is formed at the tip of the floating nozzle, and a discharge port that communicates and crosses the ejection port is formed at the outer periphery of the floating nozzle. When piercing a workpiece with a protective film, the floating nozzle is advanced from the fixed nozzle, the tip of the floating nozzle is brought into contact with the surface of the workpiece, and the discharge port is protruded from the fixed nozzle. In this state, the workpiece is pierced in a state where the protective film is pressed by irradiating the work piece with laser light and jetting the assist gas from the injection nozzle of the idle nozzle, and the protective film is peeled off. It is to be prevented.
JP-A-9-136177 JP 11-314189 A JP-A-7-241688 Japanese Patent Laid-Open No. 9-192871

  However, these conventional laser processing apparatuses and processing methods have the following problems. That is, in the laser processing apparatus of Patent Document 1, since the melt generated during piercing adheres to the surface of the work within the range surrounded by the hood, it is necessary to remove the melt and the melt is removed after piercing. However, there has been a problem that the adhesion of the melt is attached to the surface of the workpiece. Further, in the laser processing apparatus of Patent Document 2, since the mask has a small diameter, the melt generated during piercing crosses over the upper surface of the mask and scatters to the surface of the workpiece, and it is necessary to remove the melt in the same manner as described above. As a result, there was a problem that the adhesion of the melt was attached to the surface of the workpiece.

  Furthermore, in the laser processing method of Patent Document 3, the same processing position on the workpiece is irradiated twice with the laser beam, and the protective film is baked and the workpiece is pierced. There was a problem. Moreover, in the laser processing apparatus of Patent Document 4, the workpiece is pierced in a state where the tip of the floating nozzle is in contact with the surface of the workpiece in the vicinity of the outer periphery of the processing position. For this reason, there is a problem that the idle nozzle becomes an obstacle and the melt is not easily discharged from the processing position in the circumferential direction, and piercing cannot be performed smoothly in a short time.

  The present invention has been made paying attention to such problems existing in the prior art. Its purpose is to prevent the melt from scattering and adhering to the surface of the workpiece when piercing the workpiece, and to protect the workpiece with a protective film affixed to the surface. An object of the present invention is to provide a laser processing method and a laser processing apparatus capable of preventing the possibility of peeling.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a laser processing for performing processing such as piercing on a workpiece by irradiating a workpiece with laser light from a nozzle of a processing head and injecting an assist gas. In the method, a shielding sheet is interposed between the nozzle and the workpiece, and piercing is performed through the shielding sheet in a state where the shielding sheet is in contact with the workpiece.

  According to a second aspect of the present invention, there is provided a laser processing apparatus in which a laser beam is irradiated onto a workpiece from a nozzle of a processing head and an assist gas is injected to perform processing such as piercing on the workpiece. A shielding sheet is disposed between the workpiece and the workpiece so as to be movable between a processing position that contacts the workpiece and a retracted position away from the workpiece in response to the movement of the nozzle, and the shielding sheet is moved to the processing position. In this state, piercing is performed through a shielding sheet.

According to a third aspect of the present invention, in the second aspect of the present invention, an inert gas is used as the assist gas.
According to a fourth aspect of the present invention, in the invention according to the second or third aspect, the shielding sheet is made of a fluororesin.

The invention according to claim 5 is the invention according to claim 2 or 3, wherein the shielding sheet is made of paper.
According to a sixth aspect of the present invention, in the invention according to any one of the second to fifth aspects, the shielding sheet is formed in a band shape, and both ends thereof are wound around a reel and piercing is performed. The sheet feeding means is provided for intermittently feeding the shielding sheet in the longitudinal direction every time the operation is performed and changing the position corresponding to the nozzle.

  According to a seventh aspect of the present invention, there is provided a laser processing apparatus in which a laser beam is irradiated to a workpiece from a nozzle of a processing head and an assist gas is injected to perform processing such as piercing on the workpiece. A cylindrical body is attached to the processing head around the nozzle so that it can be placed at a processing position and a retracted position, and the shielding sheet is stretched at the end of the cylindrical body, A discharge port is provided on the peripheral surface of the body, and piercing is performed through the shielding sheet while the shielding sheet is in contact with the workpiece.

(Function)
In this invention, with the shielding sheet in contact with the workpiece, the workpiece is irradiated with laser light from the shielding sheet, and assist gas is injected to perform piercing. At this time, as the shielding sheet, for example, a sheet having a thickness of 0.1 mm or less is used, so there is almost no influence due to the burden of punching the sheet. For this reason, the melt generated at the time of piercing is scattered and received on the shielding sheet without adhering to the surface of the workpiece. Therefore, it is not necessary to carry out the troublesome work of cleaning and removing the melt adhering to the surface of the work after processing, and the work surface is damaged due to the cleaning and removal of the melt, and the appearance of the product is impaired. Can be prevented. Furthermore, when piercing a workpiece with a protective film for preventing scratches on the workpiece surface, the protective film is applied to the workpiece via the shielding sheet by the pressure of the assist gas sprayed onto the shielding sheet. Pressed. For this reason, it is possible to prevent the assist gas from entering between the protective film and the workpiece and peeling off the protective film.

  If the shielding sheet can be moved between the processing position that contacts the workpiece in response to the movement of the nozzle and the retreat position that is spaced from the processing position, the processing position that contacts the workpiece in correspondence with the nozzle during piercing Piercing can be performed without adhering a melt on the surface of the workpiece in the state of being moved and arranged. In addition, when a work such as cutting is performed on the workpiece, the work such as cutting can be performed without the shielding sheet interfering in a state where the shielding sheet is moved to the retracted position away from the processing position.

If an inert gas is used as the assist gas, the shielding sheet and the protective film on the workpiece surface can be prevented from burning.
If the strip-shaped shielding sheet is intermittently fed in the longitudinal direction every time the workpiece is pierced, the corresponding position of the shielding sheet with respect to the nozzle is changed. For this reason, even if a hole is made in the shielding sheet along with the piercing, a portion without a hole on the shielding sheet is arranged corresponding to the nozzle during the next piercing. Therefore, the melt generated during piercing can be reliably received on the shielding sheet.

  In a configuration in which a cylindrical body is detachably attached around the nozzle, a shielding sheet is stretched around the end of the cylindrical body, and a discharge port is provided on the peripheral surface of the cylindrical body, In the state where the cylindrical body is attached around the nozzle and the shielding sheet is in contact with the workpiece, piercing can be performed without adhesion of the melt to the surface of the workpiece via the shielding sheet. In addition, when a work such as cutting is performed on the work, the work such as cutting can be performed without the shielding sheet interfering with the cylindrical body removed from the periphery of the nozzle.

  As described above, according to the present invention, when the workpiece is pierced, it is possible to prevent the melt from scattering and adhering to the surface of the workpiece. Moreover, when piercing the workpiece | work which stuck the protective film on the surface, a possibility that a protective film may peel can be prevented.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, in the laser processing apparatus of this embodiment, a table 12 is supported on a bed 11 so as to be movable in the X direction, and a workpiece W is set on the table 12 in a detachable manner. ing. A column 13 is erected on the bed 11, and a saddle 14 is supported on the side of the column 13 so as to be movable in the Y direction. A processing head 15 is supported on the saddle 14 so as to be movable in the Z direction, and a nozzle 16 is provided below the processing head 15. Then, by moving the table 12 in the X direction, moving the saddle 14 in the Y direction, and moving the machining head 15 in the Z direction, the nozzle 16 is placed on the workpiece W from the nozzle 16 in a state where the nozzle 16 is arranged corresponding to a predetermined machining position on the workpiece W. While the laser beam is irradiated, an assist gas such as nitrogen is injected, and the workpiece W is subjected to laser processing such as piercing and cutting.

  As shown in FIGS. 1 and 2, a cylinder 17 is attached to the saddle 14 via a bracket 18, and a shielding device 19 is attached to a piston rod 17 a of the cylinder 17. Then, as the cylinder 17 moves in and out, the shielding device 19 is disposed close to the surface of the workpiece W below the nozzle 16 corresponding to the movement range of the nozzle 16 as indicated by a solid line in FIG. As indicated by a chain line in the figure, the machining position is moved to a retreat position that is spaced obliquely upward from the machining position.

  A feeding reel 21 and a take-up reel 22 are supported on the mounting plate 20 of the shielding device 19 so as to be rotatable in the horizontal direction at predetermined intervals. Both reels 21 and 22 have both ends of a belt-shaped shielding sheet 23 made of, for example, fluororesin (tetrafluoroethylene resin) or flame-retardant paper having high heat resistance and flame resistance. It is taken and stretched between the reels 21 and 22. When the shielding device 19 is moved to the processing position, the shielding sheet 23 is brought into contact with the surface of the workpiece W corresponding to the nozzle 16. In this state, the workpiece W is irradiated with laser light from the nozzle 16 of the machining head 15 via the shielding sheet 23 and the assist gas is jetted to pierce the workpiece W.

  A feeding motor 24 constituting sheet feeding means is attached to the mounting plate 20 and is operatively connected to the take-up reel 22. Each time piercing is performed on the processing position on the workpiece W, the take-up reel 22 is rotated by a predetermined amount by the feed motor 24, and the shielding sheet 23 is fed from the feed reel 21 to the take-up reel 22 side. Intermittent feed. Thereby, the corresponding position of the shielding sheet 23 with respect to the nozzle 16 is changed.

Next, a processing method in the case of performing piercing in the laser processing apparatus configured as described above will be described.
When piercing a workpiece W made of stainless steel or the like whose surface is mirror-finished, as shown in FIGS. 1 and 2, the shielding device 19 is moved to the machining position by the protruding operation of the cylinder 17, and the shielding is performed. The sheet 23 is disposed at a position corresponding to the nozzle 16 and in contact with the workpiece W. In this state, the workpiece W is irradiated with laser light from the nozzle 16 of the machining head 15 through the shielding sheet 23 and an assist gas made of an inert gas such as nitrogen is injected to pierce the workpiece W. Is done. At the time of this piercing, the melt is generated so as to rise from the processing position on the workpiece W, but the melt is received on the shielding sheet 23 arranged in contact with the workpiece W. For this reason, the melt 25 does not scatter and adhere to the surface of the workpiece W, and it is not necessary to perform a troublesome work of cleaning and removing the melt adhered to the surface of the workpiece W after processing. There is no possibility that the surface of the workpiece W is scratched by the cleaning removal, and the aesthetic appearance of the product is not impaired. In addition, since the sheet | seat of the thickness of 0.1 mm or less is used for the shielding sheet 23, for example, the burden of perforation to this shielding sheet 23 is negligible, and there is almost no influence by presence of the shielding sheet 23 at the time of piercing. . Moreover, since the assist gas used at the time of laser beam irradiation is an inert gas, it can prevent that the shielding sheet 23 and the protective film F of the upper surface of the workpiece | work W burn.

  Further, when assist gas is injected onto the shielding sheet 23 during piercing, the shielding sheet 23 is pressed against the workpiece W by the gas pressure. For this reason, when the work W has a protective film in which a protective film F made of synthetic resin or the like is attached to the surface of the work made of stainless steel or the like, when assist gas is jetted onto the shielding sheet 23, The protective film is pressed against the workpiece side through the shielding sheet 23 by the gas pressure. For this reason, there is almost no possibility that a large amount of assist gas enters between the protective film F and the workpiece, and the protective film F is peeled off from the workpiece.

  When the piercing of the workpiece W is completed, as shown by a chain line in FIG. 1, the shielding device 19 is moved to the retracted position by the immersing operation of the cylinder 17, and the shielding sheet 23 is arranged at a position away from the workpiece W. The Therefore, if processing such as cutting is continued with respect to the workpiece W in this state, the processing such as cutting can be performed without any problem without the shielding sheet 23 being in the way. Further, when piercing is repeatedly performed at different processing positions on the workpiece W, the shield sheet 23 is rotated from the supply reel 21 to the take-up reel 22 by a predetermined amount each time the piercing is performed. The corresponding position of the shielding sheet 23 with respect to the nozzle 16 is changed intermittently. For this reason, even if a hole is made in the shielding sheet 23 due to piercing, a new portion without a hole on the shielding sheet 23 is arranged corresponding to the nozzle 16 at the time of the next piercing and is generated along with the piercing. The melt can be reliably received on the shielding sheet 23.

(Second Embodiment)
Next, a second embodiment of the present invention will be described focusing on the differences from the first embodiment.
In the second embodiment, as shown in FIG. 3, the cylindrical body 26 is formed on the lower peripheral side of the machining head 15 by a plurality of shafts 27 so as to surround the nozzle 16. It is attached so that it can be placed at a position and a retracted position above the processing position. Although not shown, a holding means for holding the cylindrical body 26 at the machining position and the retracted position is provided. A shielding sheet 23 made of the same material as that of the first embodiment is stretched at the lower end of the cylindrical body 26, and a discharge port 28 is formed on the peripheral surface of the cylindrical body 26. Further, a suction device (not shown) is connected to the discharge port 28. The shielding sheet 23 is wound around the outer periphery of the cylindrical body 26 by a ring 29, and is replaced with a new one by removing the ring 29.

When piercing the workpiece W, the cylindrical body 26 is disposed at the machining position below the machining head 15 and the shielding sheet 23 at the lower end thereof is disposed in contact with the workpiece W. In this state, the workpiece W is irradiated with laser light through the shielding sheet 23, and assist gas is injected to perform piercing. At the time of this piercing, the molten material is scattered and received on the shielding sheet 23 in the cylindrical body 26 and then discharged from the discharge port 28 to the outside of the cylindrical body 26 by the suction action of the suction device. For this reason, it is possible to prevent the melt from adhering to the surface of the workpiece W. Further, when the workpiece W is processed such as cutting, if the cylindrical body 26 is disposed at the retracted position on the upper side of the processing head 15, the processing such as cutting is performed without the shielding sheet 23 being in the way. be able to.
(Example of change)
In addition, this embodiment can also be changed and embodied as follows.

In the embodiment, other sheet material such as aluminum foil is used as the shielding sheet 23.
In the first embodiment, the shielding sheet 23 is manually fed.

The principal part front view which shows the laser processing apparatus of 1st Embodiment. The partial expanded sectional view in the 2-2 line of FIG. The fragmentary sectional view which shows the laser processing apparatus of 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 15 ... Processing head, 16 ... Nozzle, 17 ... Cylinder, 19 ... Shielding device, 21 ... Feeding reel, 22 ... Winding reel, 23 ... Shielding sheet, 24 ... Feed motor which comprises sheet feeding means, 26 ... Cylindrical shape Body, 28 ... discharge port, W ... work.

Claims (7)

In the laser processing method of irradiating the workpiece with laser light from the nozzle of the processing head and injecting assist gas to perform processing such as piercing on the workpiece,
A laser processing method, comprising: interposing a shielding sheet between the nozzle and the workpiece, and performing piercing through the shielding sheet in a state where the shielding sheet is in contact with the workpiece. In the laser processing apparatus that irradiates the workpiece with laser light from the nozzle of the processing head and injects assist gas to perform processing such as piercing on the workpiece.
Between the nozzle and the workpiece, a shielding sheet is disposed so as to be movable between a processing position in contact with the workpiece and a retracted position away from the processing position corresponding to the movement range of the nozzle, and the shielding sheet is processed. A laser processing apparatus characterized in that piercing is performed through a shielding sheet in a state of being moved to a position. The laser processing apparatus according to claim 2, wherein an inert gas is used as the assist gas. The laser processing apparatus according to claim 2, wherein the shielding sheet is made of a fluororesin. 4. The laser processing method according to claim 2, wherein the shielding sheet is made of paper. A sheet feeding means for forming the shielding sheet in a belt shape, winding both ends of the shielding sheet on a reel, intermittently feeding the shielding sheet in the longitudinal direction every time piercing is performed, and changing a corresponding position with the nozzle. The laser processing apparatus according to any one of claims 2 to 5, wherein the laser processing apparatus is provided. In the laser processing apparatus that irradiates the workpiece with laser light from the nozzle of the processing head and injects assist gas to perform processing such as piercing on the workpiece.
A cylindrical body is attached to a processing head around the nozzle so as to surround the nozzle in a processing position and a retracted position, and the shielding sheet is stretched on an end of the cylindrical body. A laser processing apparatus, wherein a discharge port is provided on the peripheral surface of the cylindrical body, and piercing is performed through the shielding sheet while the shielding sheet is in contact with the workpiece.

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