JP4221540B2 - Laser processing method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser processing method and apparatus, and more particularly to a laser processing method and apparatus for a workpiece whose surface is covered with a protective sheet.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a method of cutting a workpiece into a required shape by irradiating a workpiece having a protective sheet attached to the surface with a laser beam is known. In such a conventional laser processing method, a workpiece is cut into a required shape by irradiating a laser beam while injecting an assist gas to a cutting processing position. Therefore, in the conventional laser processing method, when the workpiece is cut so that the protective sheet is on the upper surface, the assist gas blown to the cutting processing position during the cutting processing is used to change the position of the already cut position. It has been pointed out that the protective sheet is peeled and turned up, and it comes into contact with the touch sensor to cause cutting failure.
In view of this, there has been proposed a laser processing method that further eliminates such drawbacks (for example, JP-A-2-295688 and JP-A-7-241688).
That is, in the processing method disclosed in Japanese Patent Application Laid-Open No. 2-295688, the workpiece is irradiated with a laser beam through a special condensing lens having a flat surface and a convex surface. Thereby, the protective sheet is melted and evaporated by the laser beam condensed by the flat surface of the condenser lens, and at the same time, the inner side of the protective sheet covered by the laser beam condensed by the convex surface of the condenser lens The base material on the side is cut.
On the other hand, in the processing method disclosed in Japanese Patent Application Laid-Open No. 7-241688, a workpiece is irradiated with a laser beam, and the protective sheet is first baked on the surface of the base material so that the protective sheet does not peel off during the subsequent cutting process. . In this way, after the protective sheet is baked on the surface of the base material, the base material is irradiated with a laser beam having a high output to perform a necessary cutting process.
[0003]
[Problems to be solved by the invention]
By the way, the former processing method (Japanese Patent Laid-Open No. 2-295688) described above has a drawback in that the cost required for laser processing increases because a processing head equipped with a special condenser lens is required. .
On the other hand, in the latter processing method described above (Japanese Patent Laid-Open No. 7-241688), the protective sheet is difficult to peel off when the protective sheet originally baked on the surface of the base material is peeled off after the cutting process is completed. was there.
In view of the above-described circumstances, the present invention provides a laser processing method and apparatus capable of performing laser processing while preventing the protective sheet from turning up.
[0004]
[Means for Solving the Problems]
That is, the laser processing method according to the first aspect of the present invention includes an inner nozzle that is disposed on the inner side and through which a laser beam passes, an outer nozzle that surrounds the inner nozzle, and an inner space of the inner nozzle. Gas is supplied to the formed first gas passage, the second gas passage formed in the space between the outer peripheral portion of the inner nozzle and the inner peripheral portion of the outer nozzle, and the first gas passage and the second gas passage. A gas supply source,
A workpiece having a protective sheet affixed to the surface thereof is supported so that the protective sheet is on the upper surface, and the workpiece is injected into the workpiece while injecting gas through the first gas passage and the second gas passage. A laser processing method for irradiating a laser beam to cut the workpiece into a required shape,
The pressure of the gas supplied to the second gas passage is set higher than the pressure of the gas supplied to the first gas passage, and a part of the gas injected from the second gas passage passes through the cutting groove of the workpiece. Adjusting the pressure of the gas supplied to both the gas passages so that the workpiece is pulled out downward.
Further, when an abnormality is detected such that the gas supplied to the second gas passage flows backward to the first gas passage, the supply of the gas to the second gas passage is stopped.
[0005]
According to a third aspect of the present invention, there is provided a laser processing apparatus comprising: an inner nozzle disposed on the inner side and through which a laser beam passes; an outer nozzle provided to surround the inner nozzle; and an inner space of the inner nozzle. 1 gas passage, a second gas passage formed in a space portion between the outer peripheral portion of the inner nozzle and the inner peripheral portion of the outer nozzle, and the pressure of the gas supplied to the second gas passage are the first gas A gas supply source capable of supplying gas to the first gas passage and the second gas passage at a pressure higher than the pressure of the gas supplied to the passage, and the gas supplied to the second gas passage is the first gas passage And an abnormality detection means for stopping the supply of gas to the second gas passage when an abnormality such as reverse flow is detected.
[0006]
According to the method of the present invention and the device of the present invention described above, the gas pressure in the second gas passage is higher than the gas pressure in the first gas passage on the inner side during the cutting process. Therefore, the gas injected from the first gas passage flows downward through the cut groove of the workpiece cut by the laser beam. On the other hand, part of the gas injected from the second gas passage flows inward, flows downward through the cutting groove, and flows in the other direction so as to diffuse toward the outer side. Therefore, the edge part which becomes the adjacent position of the cutting groove in a protection sheet will be pressed on the surface of the base material of a workpiece by the gas injected from a 2nd gas path. Therefore, it is possible to prevent the edge of the protective sheet cut during the cutting process from turning up.
In this way, when the cutting is good, the gas injected from the nozzle passes through the cutting groove to the lower part of the workpiece, but when a cutting failure occurs due to a discharge failure or a program setting error, the cutting groove is It may not be molded. In this case, the gas from the second passage set to a high pressure is reflected by the workpiece and enters the first passage set to a low pressure, that is, into the inner nozzle. Since the sputter generated in the portion also enters the inner nozzle together with the above gas, there arises a problem that the sputter adheres to the condensing lens in the laser processing apparatus and stains the condensing lens.
However, in the method of the present invention, when an abnormality is detected such that the gas supplied to the second gas passage flows back to the first gas passage, the supply of gas to the second gas passage is stopped, so Intrusion into the nozzle and adhesion to the condenser lens can be prevented.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, a processing head 1 of a laser processing apparatus is attached to a movable frame (not shown), and a laser beam L is condensed on the upper side inside the processing head 1. A condenser lens FL is provided. The machining head 1 is supported vertically downward, and a nozzle 2 is attached to the lower end of the machining head 1.
A machining table (not shown) is provided below the machining head 1, and a plate-like workpiece 3 is placed horizontally on the machining table.
The workpiece 3 of this embodiment is composed of a plate-shaped stainless steel base material 4 and a vinyl protective sheet 5 attached to the entire surface (upper surface) of the base material 4. In this embodiment, the workpiece 3 is supported on the processing table so that the protective sheet 5 is on the upper side, and the workpiece 3 is cut.
The laser processing apparatus includes a laser oscillator (not shown), and a laser beam L oscillated from the laser oscillator is guided to the processing head 1 by a plurality of reflecting mirrors (not shown) and then condensed by a condenser lens FL. The workpiece 3 is irradiated from the lower end opening of the nozzle 2.
[0008]
A movable frame (not shown) to which the processing head 1 is attached can be moved up and down by a lifting mechanism (not shown), and the movable frame and the processing table can be moved relative to each other on a horizontal plane.
The nozzle 2 of this embodiment is composed of a cylindrical inner nozzle 2A located on the inner side, and a cylindrical outer nozzle 2B provided to surround the inner nozzle 2A.
The lower portions of the inner nozzle 2A and the outer nozzle 2B are formed in a tapered shape having a reduced diameter on the lower end side. In particular, the outer nozzle 2B is preferably installed so as to be directed near the inner processing position.
An inner space of the inner nozzle 2A is defined as a first gas passage 6, and an annular space between the inner nozzle 2A and the outer nozzle 2B is defined as a second gas passage 7.
Further, the laser processing apparatus includes a gas supply source 11 of assist gas (nitrogen), and this gas supply source 11 is connected to the first gas passage 6 of the processing head 1 through a first conduit 12. . The first conduit 12 is provided with a first regulator 13A and a first electromagnetic on-off valve 13B, and the operation of the first electromagnetic on-off valve 13B is controlled by a control device (not shown).
[0009]
The assist gas supply source 11 is also connected to the second gas passage 7 via the second conduit 14. A second regulator 15A and a second electromagnetic opening / closing valve 15B are provided in the second conduit 14, and the operation of the second electromagnetic opening / closing valve 15B is also controlled by a control device (not shown).
Note that the gas supply source 11 for the gas supplied to the first gas passage 6 and the gas supply source 11 for the gas supplied to the second gas passage 7 may be provided separately. The type of gas to be supplied may be different.
When performing cutting by irradiating the workpiece 3 with the laser beam L from the processing head 1, the control device opens the first electromagnetic on-off valve 13B and the second electromagnetic on-off valve 15B. The assist gas is injected from the lower end opening of the inner nozzle 2 </ b> A through the gas passage 6 to the cut portion 3 </ b> A of the workpiece 3. At the same time, the assist gas is supplied to the position adjacent to the machining location 3A in the workpiece 3 through the second conduit 14 and the second gas passage 7 and the lower end opening thereof. The pressure of the assist gas supplied to the first gas passage 6 and the second gas passage 7 can be adjusted as appropriate by the first regulator 13A and the second regulator 15A.
[0010]
Next, an abnormality detecting means for detecting when an abnormal state occurs such that the gas supplied to the second gas passage 7 flows backward to the first gas passage 6 on the upstream side of the first regulator 13A. 16 is provided. A flow meter 17 is used as the abnormality detection means 16 in the present embodiment, and the flow meter 17 is attached to a branch pipe 12 ′ branched from the first conduit 12. The branch pipe 12 ′ to which the flow meter 17 is attached is joined to the first conduit 12.
The signal from the flow meter 17 is input to the control device (not shown) described above. The place where the flow meter 17 is installed may be an arbitrary position where the flow rate can be measured between the gas supply source 11 and the tip of the inner nozzle 2 </ b> A. Instead of the branch pipe 12 ′ from the conduit 12, the first conduit 12 may be provided directly.
[0011]
In the above configuration, when the control device performs the cutting process, both pressures are set so that the pressure of the assist gas supplied to the second gas passage 7 is higher than the pressure of the assist gas supplied to the first gas passage 6. The electromagnetic on-off valves 13B and 15B are controlled.
As already described above, in the present embodiment, the workpiece 3 is supported on the processing table so that the protective sheet 5 is on the upper side, and is cut into a required shape.
Therefore, during the cutting process, the assist gas injected from the second gas passage 7 has a higher pressure than the pressure of the assist gas injected from the first gas passage 6, and the portion to be processed by the laser beam L (cutting) Groove) The assist gas in the second gas passage 7 is injected from the upper side toward the vicinity of the edge portions 5A and 5A of the protective sheet 5 that is adjacent to the groove 3A.
Here, FIG. 2 shows an enlarged view of the flow of gas injected from both the gas passages 6 and 7 into the processing portion (cutting groove) 3A. As shown in FIG. 2, the gas G <b> 1 injected from the inner nozzle 2 </ b> A flows downward through the processing portion 3 </ b> A of the workpiece 3 cut by the laser beam L. On the other hand, since the gas G2 injected from the outer nozzle 2B is higher in pressure than the gas G1 injected from the inner nozzle 2A, a part of the gas G2 flows inward and flows downward through the machining location 3A. The others flow to diffuse toward the outside.
Thereby, since the edge parts 5A and 5A of the protection sheet 5 are strongly pressed toward the base material 4, it can prevent favorably that the edge parts 5A and 5A turn up.
[0012]
Next, as shown in FIG. 3, when a defective cutting portion 3 </ b> A ′ where the processed portion 3 </ b> A is not completely formed for some reason is generated during the above-described normal laser processing, the gas G <b> 1 injected from the inner nozzle 2 </ b> A is generated. A part of the gas G2 injected from the outer nozzle 2B is reflected by the defective cutting portion 3A ′.
At this time, since the pressure of the gas G2 ejected from the outer nozzle 2B is higher than the pressure of the gas G1 ejected from the inner nozzle 2A, the gas G2 from the outer nozzle 2B pushes the gas G1 back to the first gas. It enters into the passage 6.
Then, the gas G2 enters the first gas passage 6 so that the flow rate of the gas in the first gas passage 6 and the first conduit 12 is reduced as compared with the case where the cutting is performed well. Become. When the control device (not shown) detects that the flow rate in the first conduit 12 is lower than a predetermined value by the flow meter 17, the first electromagnetic on-off valve 13B is closed to supply the gas to the second gas passage 7. While stopping, the irradiation of the laser beam L is stopped.
Next, when a predetermined time, for example, 1 second elapses, the second electromagnetic opening / closing valve 15B is continuously closed to stop the gas supply to the first gas passage 6. As described above, the second electromagnetic on / off valve 15B is closed after the first electromagnetic on / off valve 13B is closed, if the first electromagnetic on / off valve 13B and the second electromagnetic on / off valve 15B are closed at the same time. This is because the gas injected from the outer nozzle 2B may flow back into the first gas passage 6 due to the gas pressure remaining in the second gas passage 7 after closing.
As described above, when the abnormality detection unit 16 detects an abnormality in which the gas supplied to the second gas passage 7 flows back to the first gas passage 6 as in the case where the defective cutting portion 3A ′ occurs, the abnormality detection means 16 Since the gas supply to the two gas passages is stopped, it is possible to prevent the sputter generated in the cut portion due to the reverse flow from entering the inner nozzle 2A together with the reverse flow gas and contaminating the condenser lens FL. .
[0013]
In the above-described embodiment, the entire space between the inner nozzle 2A and the outer nozzle 2B is the second gas passage 7. However, the following configuration may be used. That is, as shown in a horizontal sectional view in FIG. 4, the plate-like member 21 is provided so as to close the space between the inner nozzle 2 </ b> A and the outer nozzle 2 </ b> B at a lower position in the nozzle 2. A plurality of through holes 21a may be formed in the plate member 21 so as to surround the inner nozzle 2A. Also in such an embodiment, the assist gas injected from the first gas passage 6 can be surrounded, and the assist gas can be injected from the lower end portion of the second gas passage 7 toward the workpiece 3.
Moreover, in the said Example, although plate-shaped stainless steel was used as the base material 4 of the to-be-processed object 3, if this is the to-be-processed object 3 which stuck the protective sheet 5 on the surface of the base material 4, this invention is applied. Can be cut. In addition, when the protective sheet 5 is not used for the workpiece 3, it is not necessary to perform the setting as in the present embodiment, and the supply of gas to the second gas passage 7 is stopped or the second gas passage 7 is stopped. What is necessary is just to set the pressure of the gas in the same as the pressure of the gas of the 1st gas passage 6.
Furthermore, although the above-described embodiment has described the case where the present invention is implemented by a laser processing apparatus that does not include a touch sensor, a laser processing apparatus including a touch sensor that contacts the surface of the workpiece 3 may be used. good.
Further, in the above embodiment, nitrogen is supplied from the same gas supply source 11 into both the gas passages 6, 7, but depending on the material of the workpiece 3, The type of gas to be supplied may be different.
[0014]
Further, the abnormality detecting means 16 is not limited to the flow meter 17, and a pressure gauge 18 may be provided in the inner nozzle 2A as shown by an imaginary line in FIG. In this case, it is desirable to provide the pressure gauge 18 at a position close to the tip of the inner nozzle 2A.
In the abnormality detecting means 16 using the pressure gauge 18, the abnormality detecting means 16 detects the gas pressure in the first gas passage 6, and when the gas pressure exceeds a predetermined value, the second gas passage. The supply of gas to 6 is stopped.
[0015]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent the edge of the protective sheet cut during the cutting process from turning up, and the gas supplied to the second gas passage due to cutting failure or the like enters the first gas passage. If an abnormal state such as reverse flow occurs, the supply of gas to the second gas passage can be stopped by the abnormality detection means, so that the effect of preventing contamination of the condenser lens due to the reverse flow is obtained. It is done.
[Brief description of the drawings]
FIG. 1 is a partial sectional front view showing an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view showing a gas flow in the main part of FIG.
FIG. 3 is a partial sectional front view showing a state of cutting failure.
FIG. 4 is a horizontal sectional view of a nozzle showing another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Processing head 2 Nozzle 2A Inner nozzle 2B Outer nozzle 3 Work piece 4 Base material 5 Protection sheet 6 1st gas passage 7 2nd gas passage 11 Gas supply source 12 1st conduit | pipe 13B 1st electromagnetic on-off valve 14 2nd conduit | pipe 15B Second electromagnetic on-off valve 16 Abnormality detection means 17 Flow meter 18 Pressure gauge

Claims (6)

An inner nozzle that is disposed on the inner side and through which the laser beam passes, an outer nozzle that surrounds the inner nozzle, a first gas passage formed by the inner space of the inner nozzle, and an outer peripheral portion and an outer side of the inner nozzle A second gas passage formed in a space between the inner peripheral portion of the nozzle and a gas supply source for supplying gas to the first gas passage and the second gas passage;
A workpiece having a protective sheet affixed to the surface thereof is supported so that the protective sheet is on the upper surface, and the workpiece is injected into the workpiece while injecting gas through the first gas passage and the second gas passage. A laser processing method for irradiating a laser beam to cut the workpiece into a required shape,
The pressure of the gas supplied to the second gas passage is set higher than the pressure of the gas supplied to the first gas passage, and a part of the gas injected from the second gas passage passes through the cutting groove of the workpiece. Adjusting the pressure of the gas supplied to both the gas passages so that the workpiece is pulled out downward.
Further, when an abnormality is detected such that the gas supplied to the second gas passage flows back to the first gas passage, the supply of the gas to the second gas passage is stopped. The gas supply to the second gas passage is stopped at the same time as the irradiation of the laser beam is stopped, and the supply of the gas to the first gas passage is stopped after a predetermined time has elapsed. The laser processing method as described. An inner nozzle that is disposed on the inner side and through which the laser beam passes, an outer nozzle that surrounds the inner nozzle, a first gas passage formed by the inner space of the inner nozzle, and an outer peripheral portion and an outer portion of the inner nozzle The second gas passage formed in the space between the inner periphery of the nozzle and the pressure of the gas supplied to the second gas passage is set to be higher than the pressure of the gas supplied to the first gas passage. The gas supply source capable of supplying the gas to the first gas passage and the second gas passage, and the second gas if an abnormality is detected such that the gas supplied to the second gas passage flows back to the first gas passage. A laser processing apparatus comprising: an abnormality detection unit that stops supply of gas to the passage. The abnormality detecting means detects a gas supply amount into the first gas passage, and stops the gas supply to the second gas passage when the gas supply amount falls below a predetermined value. Item 4. The laser processing apparatus according to Item 3. The said abnormality detection means detects the gas pressure in the said 1st gas passage, and if the gas pressure exceeds predetermined value, it will stop supply of the gas to a 2nd gas passage. Laser processing equipment. The abnormality detecting means stops the supply of the laser beam simultaneously with stopping the supply of gas to the second gas passage, and further stops the supply of gas to the first gas passage after a predetermined time has elapsed. The laser processing apparatus according to any one of claims 3 to 5.

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