JP6535475B2 - Laser processing method and laser processing machine - Google Patents

Description

  The present invention relates to a laser processing method and a laser processing machine for a work having a protective film on the surface, and more specifically, a laser processing method and a laser capable of performing laser processing without peeling the protective film from the work surface. It relates to a processing machine.

  There is a plate-like work provided with a protective film on the surface to protect the surface of the metal plate. When the laser processing of the work is performed, the protective film may be separated from the work by the assist gas injected to the work. Then, various laser processing methods for preventing that a protective film exfoliates from work at the time of laser processing of the above-mentioned work are proposed (for example, refer to patent documents 1 and 2).

Patent No. 3512634 gazette Patent No. 4304808

  In the configuration described in Patent Document 1, when performing laser processing of a work provided with a resin sheet as a protective film on the surface, the resin sheet provided on the surface of the drilling start portion is made circular under the first processing conditions The first processing to remove is performed. And from the part which removed the resin sheet, the cutting process of the workpiece | work as a 2nd process is started.

  In the configuration described in Patent Document 2, laser processing is performed in which only a protective sheet in a predetermined range surrounding a planned drilling point of a piercing hole is cut into a circle. Then, when performing piercing processing, the said circular part is blown away by assist gas.

  That is, in the configurations described in Patent Documents 1 and 2, processing for removing the protective sheet on the surface of the work is performed before performing piercing processing, and thereafter piercing processing is performed. Therefore, there is a problem in improving work efficiency.

The present invention has been made in view of the problems as described above, and is a laser processing method of a work having a protective film on the surface,
(A) At the time of piercing of a work, the gap size between the nozzle provided to the laser processing head and the work is kept larger than the gap size at the time of laser cutting of the work, and the gas of assist gas at the time of the laser cutting Performing piercing with a gas pressure less than the pressure,
(B) When the gap size between the nozzle and the work becomes a size suitable for laser cutting due to the approach operation of the laser processing head to the work, the gas pressure of the assist gas is appropriate for the laser cutting Step up to pressure,
(C) maintaining the gas pressure at a boosted pressure and making the nozzle gap smaller, and keeping the laser output smaller than the laser output at the time of piercing and continuing the laser cutting;
The method is characterized in that each step of

Further, it is a laser processing method of a work having a protective film on the surface,
(A) At the time of piercing of a work, the gap size between the nozzle provided to the laser processing head and the work is kept larger than the gap size at the time of laser cutting of the work, and the gas of assist gas at the time of the laser cutting Performing piercing with a gas pressure less than the pressure,
(B) holding the gas pressure of the assist gas at a substantially constant lower pressure than the gas pressure at the time of laser cutting when the laser processing head is moved close to the work after the end of piercing processing;
(C) When the gap size between the nozzle and the work becomes a size suitable for laser cutting due to the approaching operation of the laser processing head, the gas pressure of the assist gas is made the gas pressure appropriate for laser cutting Step of boosting,
(D) maintaining the gas pressure at a boosted gas pressure, making the nozzle gap smaller, and keeping the laser output smaller than the laser output at the time of piercing and continuing the laser cutting;
The method is characterized in that each step of

  Further, in the laser processing method, the laser output is maintained at zero at the time of the approaching operation of the laser processing head.

  In the laser processing method, the nozzle gap is maintained in the range of 8 mm to 40 mm at the time of piercing processing.

In addition, it is a laser processing machine capable of performing laser processing of a work having a protective film on the surface, which can be moved and positioned in the X, Y, and Z axes relative to the work on the work table. A head, an assist gas supply means for supplying an assist gas into a nozzle provided in the laser processing head, a laser oscillator for oscillating a laser beam to be irradiated to the work, an operation of the laser processing head, a gas pressure of the assist gas And a control device for controlling the output of the laser oscillator,
The control device controls a gap dimension between the nozzle and the workpiece at the time of piercing processing of the workpiece to be larger than a gap dimension at the time of laser cutting of the workpiece, and assist at the time of piercing processing of the workpiece A gas pressure control means for controlling the gas pressure of the gas to a lower pressure than the gas pressure at the time of laser cutting, and an operation for approaching the laser processing head to the work after the piercing is completed. The apparatus further comprises: operation control means; and laser output control means for controlling the output of the laser oscillator to zero when the laser processing head approaches the work, and the gas pressure is maintained at a boosted pressure. Keep the laser gap smaller while keeping the nozzle gap smaller and keep the laser output smaller than the laser output at the time of piercing and continue the laser cutting It is characterized in that it is configured.

  According to the present invention, when performing laser cutting of a plate-like work having a protective film on the surface, the protective film and the work are pierced at the same time in the initial piercing process. Therefore, it is possible to perform piercing processing with one operation, and it is possible to immediately shift from piercing processing to laser cutting processing of a work, and there is no peeling of the protective film from the work surface. Therefore, laser cutting can be performed efficiently.

It is a functional block diagram showing the composition of the laser beam machine concerning the embodiment of the present invention notionally and roughly. It is an explanatory view showing the relation of nozzle gap and the ease of exfoliation of a protective film. It is explanatory drawing of the operation pattern of a nozzle gap, the operation pattern of gas pressure, and the operation pattern of laser output at the time of performing a laser cutting process of a workpiece | work so that a protective film may not peel. It is explanatory drawing which shows the flowchart of operation | movement.

  The laser processing machine according to the embodiment of the present invention will be described below with reference to the drawings, and a laser processing machine capable of performing laser processing of a work having a protective film on its surface is already well known. Therefore, the overall configuration of the laser processing machine will be schematically described, and the detailed description will be omitted.

  Referring to FIG. 1, a laser processing machine 1 according to an embodiment of the present invention performs laser cutting of a work W which is a metal plate provided with a protective film 3 made of resin such as vinyl on the surface (upper surface). It is a laser processing machine that can be used, and is provided with a work table 5 such as a work pallet or a table for mounting and supporting the work W, as in a general laser processing machine. Further, the laser processing machine 1 is provided with a laser processing head 7 which can be moved and positioned relative to the work W in the X, Y and Z axis directions.

  The relative movement positioning of the laser processing head 7 in the X, Y, Z axis directions with respect to the work W controls the rotation of X, Y, Z axis motors (hereinafter simply referred to as motor M) which are servomotors. It is done by doing. The laser processing head 7 is provided with a bend mirror 11 for bending the laser beam LB oscillated (emitted) from the laser oscillator 9 to the tip side, and condenses the laser beam LB to irradiate the work W A condenser lens 13 is provided. Further, the laser processing head 7 is provided with a nozzle 15 for spouting assist gas to the work W, and a reflected light detector 17 for detecting reflected light from the laser processing position of the work W. ing. The nozzle 15 is provided with a gap sensor 19 such as a capacitance sensor for detecting a gap between the tip of the nozzle 15 and the surface of the workpiece W.

  The laser processing machine 1 further includes an assist gas supply unit 21 such as a gas cylinder for supplying an assist gas to the laser processing head 7. A pressure control valve capable of adjusting the gas pressure of the assist gas supplied to the laser processing head 7 is provided in the assist gas supply path 23 such as a pipe or the like connecting the assist gas supply means 21 and the laser processing head 7. The gas pressure control means 25 is provided. Further, in the laser beam machine 1, the motor M is controlled to adjust the gap, the output of the laser oscillator 9 is controlled, and the gas pressure of the assist gas is adjusted. A control device 27 that controls the operation of the control means 25 is provided.

  In the above configuration, the output of the laser oscillator 9 is controlled under the control of the control device 27, and the gas pressure control means 25 is controlled to control the gas pressure of the assist gas, and the motor M is controlled. By moving and positioning the laser processing head 7 relative to W in the X, Y, Z axis directions, laser cutting of the workpiece W is performed. As described above, when the laser cutting process of the workpiece W is performed, the assist gas may enter between the surface of the workpiece W and the protective film 3 and the protective film 3 may be peeled from the workpiece W.

  Therefore, when using a nitrogen gas as the assist gas for laser cutting with a stainless steel plate with a thickness of 2 mm without the protective film 3 on the surface as a work, when performing laser cutting at a normal cutting speed of 4000 to 6000 mm / min. Laser cutting was performed under the following conditions. That is, the gap amount at the time of piercing processing 4.0 mm, the gas pressure of 0.20 Mpa of assist gas, the gap amount of 0.7 mm when the laser processing head 7 is lowered (during approach), the gas pressure 0.7 to 1.0 Mpa The gap amount is 0.3 to 0.7 mm at the time of laser cutting and the gas pressure is 0.7 to 1.0 Mpa. In this case, peeling of the protective film 3 is often observed at the time of piercing processing and approach.

  Here, the factors that the protective film 3 peels off from the work W include the assist gas pressure, the adhesive force of the protective film 3 and the nozzle gap, so the diameter of the nozzles 15 was kept constant and tested for each . According to the results of the test, it was confirmed that the protective film 3 is likely to be peeled off when the assist gas pressure is high, and it is difficult to be peeled off if the adhesive force is strong. In addition, when the adhesive force of the protective film 3 becomes strong, the problem that it becomes difficult to peel off the protective film 3 at the final process of a process arises.

  As the nozzle gap becomes large, the force to peel off the protective film 3 is considered to be weak, so the diameter of the nozzle 15 is kept constant and the gas pressure of the assist gas is kept at 0.15 Mpa and 0.7 Mpa. When the relationship between the nozzle gap and the peelability of the protective film 3 was experimentally examined when the adhesive force of 3 was constant (weak adhesive force 40 g / 20 mm), the results shown in FIG. 2 were obtained. As apparent from FIG. 2, it can be seen that the nozzle gap is most likely to be peeled off when it is about 1 mm, and it becomes gradually difficult to be peeled off if it is 1 mm or more.

  Here, as is apparent from FIG. 2, when the nozzle gap is about 0.3 mm, the gas pressure is 0.15 Mpa and 0.7 Mpa, compared with the case where the nozzle gap is 1.0 mm and protection is provided. The film 3 is difficult to peel off. However, when piercing the work W, the holes are not penetrated, and the amount of spatter scattered to the upper side of the work W is large, and the spatter adheres to the protective glass and the condenser lens installed in the laser processing head 7 It is undesirable to perform the piercing while holding the nozzle gap at about 0.3 mm or less because the number is increased. In addition, when the time when the protective film 3 peels was checked, when piercing processing of the work W is completed (during piercing piercing), when moving down the laser processing head 7 to shift from piercing processing to laser cutting processing of the work W Many were seen (at the time of approach operation).

  So, in this embodiment, when nitrogen gas is used as an assist gas at the time of carrying out the laser cutting process of the stainless steel plate provided with the protective film 3 with a thickness of 2 mm, the laser processing is performed under the conditions shown in FIG. Peeling of the protective film 3 from the work W could be suppressed.

  That is, based on the experimental result of FIG. 2, the nozzle gap was set to 10 mm, and the gas pressure was set to 0.15 Mpa, and piercing was performed. Then, after the end of the piercing, when the laser processing head 7 was gradually lowered to approach the nozzle gap to 0.3 mm, the gas pressure was lowered to 0.10 Mpa and maintained at a substantially constant low pressure. As described in, for example, Japanese Patent Application Laid-Open No. 2001-239388, whether or not piercing processing has been completed detects that the amount of received reflected light has been detected and that sputtering has occurred on the lower surface of the work. It is possible to adopt various configurations, such as the configuration described below. That is, it can be detected by the reflected light detector 17.

  As described above, when the piercing was finished, the laser output was held at zero (output stop). Then, when the nozzle gap became 0.3 mm, the gas pressure was gradually increased to 0.70 Mpa and the laser output was slightly larger than the laser output at the time of piercing processing to start laser cutting. After that, when the nozzle gap becomes 0.2 mm, the gas pressure is maintained at 0.70 Mpa, and the laser output is maintained slightly smaller than the laser output at the time of piercing processing, and the laser cutting processing of the work W is performed The In this case, the laser cutting process could be performed without peeling the protective film 3 from the work W. In addition, the cutting speed in the case of the above is a normal cutting speed.

  In addition, from the experimental result shown by FIG. 2, when a nozzle gap is 8 mm or more, the protective film 3 becomes difficult to peel. However, when the nozzle gap is further increased, the focal position of the condenser lens 13 is largely separated from the upper surface of the work W, and there is a problem that the piercing hole becomes large. Therefore, in consideration of the experimental result of FIG. 2, the range of the nozzle gap at the time of piercing processing is desirably 8.0 mm to 40 mm.

  Although the gas pressure at the time of piercing processing is influenced by the adhesion of the protective film 3 to the work W, when the adhesion is weak (about 40 g / 20 mm), according to various experiments, 0.05 to 0.2 Mpa Is desirable. That is, when the gas pressure is less than 0.05 Mpa, the effect of blowing off the spatter is small, and even when the nozzle gap is large, the spatter at the time of piercing processing easily adheres to the optical system in the laser processing head 7. In addition, when the gas pressure is 0.20 MPa or more, the protective film 3 is easily peeled off at the time of piercing although it depends on the size of the nozzle gap.

  In the case where the adhesive force of the protective film 3 is weak, the gas pressure at the time of lowering the laser processing head 7 after the end of piercing processing is from 0.0 to 0.20 Mpa according to various experiments. Peeling of the protective film 3 could be suppressed. That is, the gas pressure at the time of lowering of the laser processing head 7 may be the same pressure as the gas pressure at the time of piercing, low pressure or high pressure. In addition, as shown in FIG. 3 (B), it is desirable to keep the gas pressure at this time substantially constant. Moreover, when the adhesive force of the protective film 3 was weak, the nozzle gap at the time of approach was able to suppress peeling of the protective film 3 in the range of 0.2-0.5 mm.

  As understood from the above description, the protective film 3 and the work W can be pierced at the same time by performing the piercing process and the laser cutting process of the work W under the conditions shown in FIG. It is possible to immediately shift from the processing operation to the laser cutting processing operation. Moreover, it can suppress that the protective film 3 peels from the workpiece | work W at the time of piercing processing.

  Therefore, in order to control the nozzle gap, the gas pressure of the assist gas and the laser output as in the operation pattern shown in FIG. 3, the operations of the motor M, the laser oscillator 9 and the gas pressure control means 25 are controlled. The control device 27 is provided. The control device 27 is constituted by, for example, a computer, and includes a CPU 29. Furthermore, the control device 27 is provided with a gap memory 31. In this gap memory 31, a memory 31A for piercing is stored as a parameter of workpiece material, plate thickness and opening diameter of the nozzle 15 when plural kinds of nozzle gaps at the time of piercing processing at the time of performing laser cutting of the workpiece W The memory 31B at approach time and the nozzle gaps at cutting time are stored as parameters of work material, plate thickness and opening diameter of the nozzle 15. The material of work, plate thickness, Each of the memory 31C for cutting processing stored as a parameter of the opening diameter of the nozzle 15 is provided.

  Therefore, the operation of the motor M is controlled under the control of the motor operation control means 33 according to the parameters respectively selected from the memories 31A, 31B, 31C, and the detection signal of the rotary encoder E provided in the motor M is fed back. Thus, the gap between the tip of the nozzle 15 and the work W can be controlled to a desired gap in accordance with piercing, approaching and cutting.

  As already understood, the gap between the nozzle 15 and the work W is controlled by the motor operation control means 33. Therefore, the motor operation control means 33 constitutes gap control means for controlling the gap.

  Further, the control device 27 is provided with a laser output memory 35. In this laser output memory 35, a plurality of laser outputs at the time of piercing are stored as work material and plate thickness parameters, and a memory 35A at the time of piercing and plural laser outputs at approach are shown as work material and plate An approach memory 35B stored as a thickness parameter and a cutting memory 35C storing a plurality of laser outputs during cutting processing as parameters of the workpiece material and plate thickness are provided.

  Therefore, by controlling the output of the laser oscillator 9 under the control of the laser output control means 37 in accordance with the parameters respectively selected from the respective memories 35A, 35B, 35C, at the time of piercing, approaching and cutting Accordingly, the laser output can be controlled to a desired output. At the time of piercing, whether or not the piercing is finished can be detected by detecting a change in the amount of reflected light by the reflected light detector 17. Then, when it is detected that the piercing processing is finished, the output of the laser oscillator 9 is controlled to zero.

  Furthermore, the control device 27 is provided with a gas pressure memory 39. In this gas pressure memory 39, the piercing memory 39A and the laser processing head 7 are approached, in which a plurality of gas pressures at the time of piercing processing are stored as parameters of workpiece material, plate thickness and opening diameter of the nozzle 15. The descent memory 39 B and descent pressure at the time of approach are stored as parameters of the workpiece material, plate thickness, and the opening diameter of the nozzle 15 at the time of descent to the nozzle gap of An approach time memory 39C stored as a parameter of the plate thickness and the opening diameter of the nozzle 15 is provided.

  Therefore, by controlling the operation of the gas pressure control means 25 by the gas pressure operation control means 41 in accordance with the parameters respectively selected from the memories 39A, 39B, 39C, the assist gas at the time of spouting from the nozzle 15 The gas pressure can be controlled to a desired gas pressure in accordance with the lowering and approach of the nozzle 15 at the time of piercing.

  In the above-described configuration, in order to perform laser cutting of the workpiece W, in step S1 (see FIG. 4), processing conditions at the time of piercing are set. That is, according to the material and thickness of the work W, appropriate parameters are selected from the memory 31A at the time of piercing processing in the gap memory 31, the memory 31B at the time of approach and the memory 31C at the cutting processing, Appropriate parameters are selected from the processing memory 35A, the approach memory 35B, and the cutting processing memory 35C. Further, appropriate parameters are selected from the memory 39A for piercing processing, the memory 39B for lowering, and the memory 39C for approach in the gas pressure memory 39, and stored in a memory (not shown) provided in the control device 27.

  Then, when piercing is started (step S2), the nozzle gap, the gas pressure and the laser output are controlled in accordance with the selected parameters to obtain the nozzle gap as shown in FIGS. 3 (A), (B) and (C). The laser cutting process of the workpiece W can be performed with the operation pattern of, the operation pattern of the gas pressure, and the operation pattern of the laser output. That is, when the piercing process is started, it is determined in step S3 whether or not the piercing process is finished. Then, as described above, when the end (completion) of piercing processing is detected by the reflected light detector 17, the descent of the laser processing head 7 and the nozzle 15 is started as shown in step S4. That is, Z-axis descent is performed. Thus, when the Z-axis descent is performed, the gas pressure is maintained at a substantially constant gas pressure lower than the gas pressure at the time of laser cutting. Also, the laser output is held at zero.

  Then, in step S5, it is determined whether or not the gap between the nozzle 5 and the workpiece W has reached a previously set approach gap. When the gap reaches the approach gap, the gas pressure is increased (boosted) in step S6, and the laser output is temporarily controlled to the maximum output. Thereafter, in step S7, the gap is controlled to a gap suitable for cutting and the gas pressure is also maintained at a gas pressure suitable for cutting. Then, the laser output is controlled to be slightly lower than the laser output at the time of piercing and laser cutting is performed. Thereafter, the laser cutting process ends in step S8.

  That is, the nozzle gap, the gas pressure and the laser output are controlled to the operation pattern as shown in FIG. 3, and the laser cutting process is performed from the piercing process. Therefore, when performing the laser cutting process of the work W having the protective film 3 on the surface, the piercing process of the protective film 3 and the work W is simultaneously performed, and the laser cutting process is performed with the peeling of the protective film 3 suppressed. It can be done.

  By the way, the present invention is not limited to the embodiment described above, and can be implemented in other forms by making appropriate changes. That is, in the above description, control of the nozzle gap is performed by selecting each parameter stored in the memory 31A at the time of piercing processing in the gap memory 31, at the time of approach memory 31A and at the time of cutting processing 31C to control the gap. did. However, for example, with respect to a standard nozzle gap at the time of cutting, it is also possible to obtain the nozzle gap at the time of piercing and at the time of approach by calculation using parameters experimentally obtained in advance. Also, with regard to gas pressure and laser output, for example, the gas pressure at the time of cutting and processing, and the laser output as the reference gas pressure and laser output, and using experimentally determined parameters in advance, gas pressure and laser at the time of piercing processing etc. It is also possible to calculate the output.

DESCRIPTION OF SYMBOLS 1 laser processing machine 3 protective film 5 work table 7 laser processing head 9 laser oscillator 11 bend mirror 13 condensing lens 15 nozzle 17 reflected light detector 19 gap sensor 21 assist gas supply means 23 assist gas supply path 25 gas pressure control means 27 Control unit 29 CPU
31 gap memory 33 motor operation control means 35 laser output memory 37 laser output control means 39 gas pressure memory 41 gas pressure operation control means

Claims (5)

A laser processing method for a work having a protective film on the surface, comprising:
(A) At the time of piercing of a work, the gap size between the nozzle provided to the laser processing head and the work is kept larger than the gap size at the time of laser cutting of the work, and the gas of assist gas at the time of the laser cutting Performing piercing with a gas pressure less than the pressure,
(B) When the gap size between the nozzle and the work becomes a size suitable for laser cutting due to the approach operation of the laser processing head to the work, the gas pressure of the assist gas is appropriate for the laser cutting Step up to pressure,
(C) maintaining the gas pressure at a boosted pressure and making the nozzle gap smaller, and keeping the laser output smaller than the laser output at the time of piercing and continuing the laser cutting;
A laser processing method comprising the steps of A laser processing method for a work having a protective film on the surface, comprising:
(A) At the time of piercing of a work, the gap size between the nozzle provided to the laser processing head and the work is kept larger than the gap size at the time of laser cutting of the work, and the gas of assist gas at the time of the laser cutting Performing piercing with a gas pressure less than the pressure,
(B) holding the gas pressure of the assist gas at a substantially constant lower pressure than the gas pressure at the time of laser cutting when the laser processing head is moved close to the work after the end of piercing processing;
(C) When the gap size between the nozzle and the work becomes a size suitable for laser cutting due to the approaching operation of the laser processing head, the gas pressure of the assist gas is made the gas pressure appropriate for laser cutting Step of boosting,
(D) maintaining the gas pressure at a boosted gas pressure, making the nozzle gap smaller, and keeping the laser output smaller than the laser output at the time of piercing and continuing the laser cutting;
A laser processing method comprising the steps of   The laser processing method according to claim 1 or 2, wherein the laser output is maintained at zero during the approaching operation of the laser processing head.   The laser processing method according to claim 1, wherein the nozzle gap is maintained in a range of 8 mm to 40 mm at the time of piercing processing. A laser processing machine capable of performing laser processing of a work having a protective film on the surface, wherein the laser processing head is movable relative to the work on the work table in the X, Y, and Z axis directions; An assist gas supply means for supplying an assist gas into a nozzle provided in the laser processing head; a laser oscillator for oscillating a laser beam to be irradiated to the work; an operation of the laser processing head; a gas pressure of the assist gas; A controller for controlling the output of the laser oscillator;
The control device controls a gap dimension between the nozzle and the workpiece at the time of piercing processing of the workpiece to be larger than a gap dimension at the time of laser cutting of the workpiece, and assist at the time of piercing processing of the workpiece A gas pressure control means for controlling the gas pressure of the gas to a lower pressure than the gas pressure at the time of laser cutting, and an operation for approaching the laser processing head to the work after the piercing is completed. The apparatus further comprises: operation control means; and laser output control means for controlling the output of the laser oscillator to zero when the laser processing head approaches the work, and the gas pressure is maintained at a boosted pressure. Keep the laser gap smaller while keeping the nozzle gap smaller and keep the laser output smaller than the laser output at the time of piercing and continue the laser cutting Laser processing machine, which is a configuration.

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