Laser processing method, processing program, and control device

Abstract

The present invention is a laser processing method for forming a closed-bottom hole by radiating a laser beam onto a workpiece and thereby removing a section of the workpiece. In the laser processing method, the following steps are repeated until the depth of a closed-bottom hole reaches a prescribed depth: a first irradiating step in which when a laser beam is radiated, a combustion-supporting gas is sprayed towards the point of irradiation; and a second irradiating step which follows the first irradiating step and in which when a laser beam is radiated, an inert gas is sprayed towards the point of irradiation.

Description

Technical Field

[0001] The present invention relates to a laser processing method for irradiating a workpiece with a laser beam to form a bottomed hole for removing a part of the workpiece.

Background Art

[0002] Laser processing apparatuses such as laser cutting machines and laser welding machines can perform predetermined processing by transmitting a processing laser beam output from a laser oscillator, irradiating the workpiece with the beam, and relatively moving the processing laser beam and the workpiece. When processing a thick metal plate using such a laser processing apparatus, in order to make the penetration depth at the irradiation point of the laser beam deeper, it is known to perform processing while injecting a supporting combustion gas such as oxygen as an assist gas at the irradiation point.

[0003] When performing laser processing while injecting a supporting combustion gas, deeper penetration can be obtained by promoting heat generation by utilizing the oxidation reaction between the metal material of the metal plate and oxygen contained in the supporting combustion gas. On the other hand, when the thickness of the metal plate to be processed increases or the processing speed increases, there is a limit to the penetration depth, so the processing may become difficult.

[0004] As laser processing apparatuses for improving such problems, for example, those disclosed in Patent Document 1 and Patent Document 2 shown below are known. In the laser processing apparatuses disclosed in these documents, by irradiating a laser beam for preprocessing while injecting an inert gas immediately before the laser beam for main processing, the surface of the workpiece can be adjusted to increase the absorption rate of the laser beam for main processing.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] In the above-described conventional technology, although it is possible to process a thicker workpiece compared to the case where no pretreatment is performed, when performing processing with a thickness that requires multiple passes for cutting or drilling, or when processing concave portions such as blind holes and grooves, an oxide film remains on the surface of the workpiece after processing due to the oxidation reaction during processing with a laser beam.

[0007] Such an oxide film has a higher melting point than the metal material of the base material and is a solidified product of molten metal that has cooled. Therefore, the surface is rough and the absorption rate of the laser beam is reduced. For this reason, when repeatedly performing laser processing on the same location in multiple passes, there has been a problem that the desired penetration depth (processing depth) cannot be obtained due to the oxide film remaining on the surface of the workpiece processed in the previous pass.

[0008] On the other hand, in conventional laser processing, attempts have been made to suppress the remaining of the oxide film after the above-described processing by performing laser processing while injecting an inert gas as a pretreatment for processing using a combustion-supporting gas as an assist gas, or by performing laser processing using a mixed gas of a combustion-supporting gas and an inert gas as an assist gas. However, in both cases, since an assist gas containing a combustion-supporting gas is used in the final processing, there has also been a problem that an oxide film remains at the bottom after processing and cannot be avoided.

[0009] Due to such circumstances, when processing a hole or a concave portion (blind hole) where the bottom remains after processing in multiple passes, a laser processing technique for forming a blind hole capable of obtaining a sufficient processing depth and a bottom where no oxide film remains after processing is required.

MEANS FOR SOLVING THE PROBLEMS

[0010] A laser processing method for forming a blind hole by irradiating a workpiece with a laser beam to remove a part of the workpiece includes a first irradiation step of injecting a combustible gas to an irradiation point when irradiating the laser beam, and a second irradiation step of injecting an inert gas to the irradiation point when irradiating the laser beam after the first irradiation step, which is repeatedly executed until the depth of the blind hole reaches a predetermined depth. Moreover, the first irradiation step is executed while moving the irradiation point, and the second irradiation step is executed while moving the irradiation point along the same path as the first irradiation step. It is specified as such.

[0011] Further, a processing program for causing a control device of a laser processing apparatus for forming a blind hole by irradiating a workpiece with a laser beam to remove a part of the workpiece to perform the following steps according to another aspect of the present invention includes a first irradiation step of injecting a combustible gas to an irradiation point when irradiating the laser beam, and a second irradiation step of injecting an inert gas to the irradiation point when irradiating the laser beam after the first irradiation step, which is repeatedly executed until the depth of the blind hole reaches a predetermined depth. The first irradiation step is executed while moving the irradiation point, and the second irradiation step is executed while moving the irradiation point along the same path as the first irradiation step. It is specified as such.

[0012] Moreover, a control device for controlling the operation of a laser processing apparatus for forming a blind hole by irradiating a workpiece with a laser beam to remove a part of the workpiece according to still another aspect of the present invention includes a processing program for controlling the operation of the laser processing apparatus. The processing program includes a first irradiation step of injecting a combustible gas to an irradiation point when irradiating the laser beam, and a second irradiation step of injecting an inert gas to the irradiation point when irradiating the laser beam after the first irradiation step, which is repeatedly executed until the depth of the blind hole reaches a predetermined depth. The machining program causes the first irradiation step to be executed while moving the irradiation point, and causes the second irradiation step to be executed while moving the irradiation point along the same path as the first irradiation step. It is specified as such.

Effect of the Invention

[0013] According to one aspect of the present invention, a first irradiation step of injecting a supporting combustible gas to an irradiation point when irradiating a laser beam, and after the first irradiation step, a second irradiation step of injecting an inert gas to the irradiation point when irradiating the laser beam are repeatedly executed until the depth of the bottomed hole reaches a predetermined depth, so that a sufficient processing depth and a bottom portion without remaining oxide film after processing can be obtained.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

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Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 6

Figure 7A

Figure 7B

Figure 7C

Figure 7D

Figure 8A

Figure 8B

Figure 9A

Figure 9B

Figure 10A

Figure 10B

Figure 11A

Figure 11B

Figure 11C

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0015] Hereinafter, an embodiment of a laser processing method according to a typical example of the present invention, a processing program for executing the same, and a control device will be described with reference to the drawings.

[0016] <First Embodiment> FIG. 1 is a schematic diagram showing the configuration of a laser processing apparatus including a control device for executing a laser processing method according to a first embodiment which is a typical example of the present invention. Further, FIG. 2 is a block diagram showing an example of the configuration of the gas supply mechanism shown in FIG. 1. Furthermore, FIG. 3 is a block diagram showing an example of the configuration of the control device shown in FIG. 1.

[0017] As shown in FIG. 1, as an example, the laser processing apparatus 100 includes a laser oscillator 110 that oscillates a laser beam LB for processing, a work holding mechanism 120 that holds a work W, a processing head 130 that irradiates the work W with the laser beam LB, a head transfer mechanism 140 that relatively moves the processing head 130 with respect to the work holding mechanism 120, a gas supply mechanism 150 that supplies assist gas to the processing head 130, and a control device 160 that controls the laser processing operation on the work W based on a processing program.

[0018] The laser oscillator 110 applies an oscillation source having a wavelength with a high absorption rate according to the material of the work W to be processed. As such a laser oscillator 110, as an example, those capable of fiber transmission such as a YAG laser, a YVO4 laser, a fiber laser, and a disk laser can be exemplified. Further, the laser beam LB output from the laser oscillator 110 can be applied either in continuous oscillation or pulse oscillation, and is transmitted to the processing head 130 via a transmission path 134 such as an optical fiber, for example.

[0019] The work holding mechanism 120 includes, as an example, a chuck mechanism (not shown) for attaching the work W, and is configured to grip and fix the work W. Further, the work holding mechanism 120 may include, for example, not only a mechanism for moving the work W in the three-axis directions of XYZ, but also a rotation mechanism.

[0020] As an example, a laser beam LB is introduced into the processing head 130 from one end (upper end) side through a transmission path 134 such as an optical fiber, and is emitted from the nozzle 132 on the other end (lower end) side toward the workpiece W. At this time, the laser beam LB is condensed to a predetermined beam diameter at the condensing point FP on the workpiece W by a condensing lens (not shown) disposed inside the processing head 130.

[0021] In addition, an assist gas for assisting laser processing by the laser beam LB is supplied to the processing head 130 from a gas supply mechanism 150 described later through a gas supply pipe 152 at a predetermined pressure and flow rate. Then, the assist gas supplied to the processing head 130 is ejected coaxially with the laser beam LB from the nozzle 132.

[0022] As an example, the head transfer mechanism 140 includes a linear drive body 142 that relatively moves in the three-axis directions of XYZ orthogonal to each other, and the processing head 130 is attached to one end of the linear drive body 142. Further, the head transfer mechanism 140 may be configured as an industrial robot of a six-axis or seven-axis type including a robot arm having the processing head 130 attached to one end.

[0023] As an example, as shown in FIG. 2, the gas supply mechanism 150 includes a supporting combustible gas supply source 154a that temporarily stores a supporting combustible gas, an inert gas supply source 154b that temporarily stores an inert gas, supply paths 155a and 155b that respectively guide the supplied supporting combustible gas and inert gas, pressure sensors 156a and 156b provided in the respective supply paths 155a and 155b, and a switching unit 158 that selectively switches the supporting combustible gas or inert gas supplied from the two supply paths 155a and 155b and sends it to the gas supply pipe 152. The switching unit 158 includes, for example, a switching valve or the like, and is configured to receive a supply command from the control device 160 and send the designated type of gas to the gas supply pipe 152.

[0024] In this specification, as the "support combustion gas", oxygen gas containing pure oxygen (O2) gas, trace nitrogen (N2), etc. can be applied. On the other hand, as the "inert gas", nitrogen (N2) gas, helium (He) gas, argon (Ar) gas, etc. can be applied. Further, the pressure sensors 156a and 156b illustrated in FIG. 2 may be, for example, flow sensors.

[0025] As an example, as shown in FIG. 3, the control device 160 includes a main control unit 162 that outputs a drive command to the components of the laser processing device 100 based on a processing program, a display unit 164 that displays various parameters, etc., and an input interface 166 through which information for correcting the processing program and various parameters can be manually input. And, in the control device 160, the main control unit 162 is connected to the laser oscillator 110, the work holding mechanism 120, the head transfer mechanism 140, and the gas supply mechanism 150 by wire or wirelessly, and exchanges signals with these peripheral devices to control the operation of the entire laser processing device 100.

[0026] As an example, the main control unit 162 has a function of extracting information such as a processing path and processing conditions from a processing program and outputting an output command signal for instructing the output of the laser beam LB to the laser oscillator 110. Further, the main control unit 162 has a function of extracting information such as the position of the irradiation point FP of the laser beam LB and the position of the processing head 130 from the processing program and outputting a processing position command signal for instructing the relative movement between the work W and the processing head 130 to the work holding mechanism 120 and the head transfer mechanism 140. Furthermore, the main control unit 162 has a function of extracting information such as the type of assist gas ejected accompanying the emission and movement of the laser beam LB from the processing program and outputting a gas supply command to the gas supply mechanism 150.

[0027] Next, specific embodiments of the laser processing method according to the first embodiment will be described with reference to FIGS. 4A to 7D.

[0028] Figures 4A and 4B are partial cross-sectional views showing the processing state when the first irradiation step of the laser processing method according to the first embodiment is executed. Further, Figures 5A and 5B are partial cross-sectional views showing the processing state when the second irradiation step of the laser processing method according to the first embodiment is executed. Further, Figure 6 is a flowchart showing the control operation executed by the main control unit of the control device according to the first embodiment. Furthermore, Figures 7A to 7D are partial cross-sectional views showing the continuous processing state when the laser processing method according to the first embodiment is executed.

[0029] In the laser processing method according to the first embodiment, a first irradiation step of injecting a combustion-supporting gas Ga to the irradiation point FP when irradiating the laser beam LB, and after the first irradiation step, a second irradiation step of injecting an inert gas Gb to the irradiation point FP when irradiating the laser beam LB are repeatedly executed until the depth of the bottomed hole BH reaches a predetermined depth. As a result, a part of the workpiece W is removed, and a bottomed hole BH with a predetermined depth is formed.

[0030] In the first irradiation step, as shown in Figure 4A, processing is performed while injecting a high-speed and high-pressure combustion-supporting gas Ga as an assist gas toward the irradiation point FP of the laser beam LB. The irradiated laser beam LB is absorbed by the workpiece W to form a molten pool MP with a depth Da.

[0031] Here, by injecting the combustion-supporting gas Ga as an assist gas together with the irradiation of the laser beam LB, the molten pool MP becomes hotter due to the action of oxygen contained in the combustion-supporting gas Ga, so the penetration depth Da can be increased. Then, the combustion-supporting gas Ga injected at high speed blows the molten molten pool MP away from the workpiece W, and as a result, as shown in Figure 4B, a bottomed hole BH with a depth Da is formed in the workpiece W. At this time, an oxide film MO with a predetermined thickness remains on the bottom surface of the bottomed hole BH due to the oxidation reaction between the workpiece W and the combustion-supporting gas Ga.

[0032] On the other hand, in the second irradiation step, as shown in FIG. 5A, machining is performed while injecting a high-speed and high-pressure inert gas Gb toward the irradiation point FP of the laser beam LB as an assist gas. The irradiated laser beam LB is absorbed by the workpiece W to form a molten pool MP with a depth Db.

[0033] Here, by injecting the inert gas Gb as an assist gas along with the irradiation of the laser beam LB, the vicinity of the molten pool MP becomes an inert gas atmosphere due to the action of the inert gas Gb, so that the oxidation reaction with the molten workpiece W does not occur. Then, the inert gas Gb injected at high speed blows the molten molten pool MP off the workpiece W, and a bottomed hole BH with a depth Db is formed in the workpiece W as shown in FIG. 5B. As a result of these, although the depth of the hole is small, a bottomed hole BH with almost no oxide film MO remaining on its bottom surface can be obtained.

[0034] In the laser processing method according to the first embodiment to which the operations of the above-described first irradiation step and second irradiation step are applied, as shown in FIG. 6, first, the main control unit 162 of the control device 160 reads, for example, from an external database or a storage medium (not shown), a processing program including the size and depth of the bottomed hole to be processed, the irradiation conditions of the laser beam, etc. (step S101). Then, the main control unit 162 analyzes the read processing program and generates various command signals to be output to each component of the laser processing apparatus 100.

[0035] Next, the main control unit 162 outputs a supply command signal for switching the gas supply mechanism 150 to inject the supporting combustion gas Ga based on the gas supply conditions specified in the processing program (step S102). Subsequently, the main control unit 162 outputs an irradiation command signal to the laser oscillator 110, the workpiece holding mechanism 120, and the head transfer mechanism 140 based on the irradiation conditions of the laser beam LB (step S103). By the operations of these two steps, the above-described "first irradiation step" is executed, and a bottomed hole BH with a depth Da is formed in the workpiece W as shown in FIG. 7A.

[0036] Subsequently, the main control unit 162 outputs a supply command signal to switch the gas supply mechanism 150 to inject the inert gas Gb based on the gas supply conditions specified in the machining program (step S104). Subsequently, the main control unit 162 outputs an irradiation command signal to the laser oscillator 110, the work holding mechanism 120, and the head transfer mechanism 140 based on the irradiation conditions of the laser beam LB (step S105). By the operations of these two steps, the above-described "second irradiation step" is executed, and as shown in FIG. 7B, a bottomed hole BH with a depth of (Da + Db) is formed in the work W.

[0037] Next, the main control unit 162 acquires the hole depth (cumulative hole depth) of the bottomed hole BH formed by the machining so far (step S106). In the machining so far, as described above, the cumulative hole depth is (Da + Db).

[0038] Subsequently, the main control unit 162 determines whether the hole depth of the bottomed hole BH acquired in step S106 has reached the final hole depth specified in the machining program (step S107). In step S107, if it is determined that the acquired hole depth of the bottomed hole BH has reached the specified hole depth, the main control unit 162 determines that the machining of the predetermined bottomed hole BH is completed and ends the control operation according to the machining program.

[0039] On the other hand, in step S107, if it is determined that the acquired hole depth of the bottomed hole BH has not reached the specified hole depth, the main control unit 162 returns to step S102 and repeats the subsequent operations. That is, the main control unit 162 outputs a supply command signal to switch the assist gas to the supporting combustion gas Ga (step S102), and subsequently outputs an irradiation command signal to the laser oscillator 110, the work holding mechanism 120, and the head transfer mechanism 140 (step S103).

[0040] By these operations, the second first irradiation step is repeated, and as shown in FIG. 7C, a bottomed hole BH with a depth of (2Da + Db) is formed in the workpiece W. At this time, an oxide film MO with a predetermined thickness remains on the bottom surface of the bottomed hole BH due to the oxidation reaction between the workpiece W and the supporting combustible gas Ga.

[0041] Next, the main control unit 162 outputs a supply command signal for switching the assist gas to the inert gas Gb (step S104), and subsequently outputs an irradiation command signal to the laser oscillator 110, the workpiece holding mechanism 120, and the head transfer mechanism 140 (step S105). By these operations, the second second irradiation step is repeated, and as shown in FIG. 7D, a bottomed hole BH with a depth of (2Da + 2Db) in which almost no oxide film MO remains is formed in the workpiece W.

[0042] Next, the main control unit 162 acquires the hole depth (cumulative hole depth) of the bottomed hole BH formed by the processing so far (step S106), and determines whether the acquired hole depth of the bottomed hole BH has reached the final hole depth specified in the processing program (step S107). In the repeatedly executed step S107, as in the first case, when it is determined that the acquired hole depth of the bottomed hole BH has reached the specified hole depth, the main control unit 162 determines that the processing of the predetermined bottomed hole BH is completed and ends the control operation by the processing program.

[0043] On the other hand, in step S107, when it is determined that the acquired hole depth of the bottomed hole BH has not reached the specified hole depth, the main control unit 162 returns to step S102 and executes the subsequent second repetition operation. Thus, in the laser processing method according to the first embodiment, the first irradiation step using the supporting combustible gas Ga as the assist gas and the second irradiation step using the inert gas Gb as the assist gas are repeatedly executed, and as a result, a bottomed hole BH with a predetermined depth is formed in the workpiece W.

[0044] At this time, when the hole depth of the blind hole BH specified in the machining program is not an integral multiple of the sum of the machining depth Da in the first irradiation step and the machining depth Db in the second irradiation step, the respective laser irradiation conditions in the repeatedly executed first irradiation step and second irradiation step may be configured to be adjustable as appropriate. However, the above laser irradiation conditions are adjusted so that the last machining executed repeatedly is the machining by the second irradiation step. Thereby, a blind hole BH having a surface with almost no remaining oxide film MO is formed on the workpiece W.

[0045] By providing the above configuration, the laser processing method according to the first embodiment includes a first irradiation step of injecting a supporting combustible gas to the irradiation point when irradiating a laser beam, and after the first irradiation step, a second irradiation step of injecting an inert gas to the irradiation point when irradiating a laser beam. By repeatedly executing until the depth of the blind hole reaches a predetermined depth, a sufficient machining depth and a bottom portion with no remaining oxide film after machining can be obtained. In the above first embodiment, although a specific aspect of a typical laser processing method according to the present invention has been described, as another aspect, each step of the above laser processing method can be configured as a machining program executed by a control device, and the control device can also be configured while causing the laser processing device to execute the operation of the above-described laser processing method including the machining program.

[0046] <Second Embodiment> FIGS. 8A and 8B are partial cross-sectional views showing a continuous machining state when a laser processing method according to a second embodiment, which is another example of the present invention, is executed. FIGS. 9A and 9B are partial top views showing an example of a machining locus of a laser beam in the laser processing method according to the second embodiment. FIGS. 10A and 10B are partial top views showing an example of a machining locus of a laser beam in a laser processing method according to a modified example of the second embodiment. Furthermore, FIGS. 11A to 11C are partial cross-sectional views showing a continuous machining state when a laser processing method according to a modified example of the second embodiment is executed.

[0047] In the second embodiment, for components that can adopt the same or common configurations as those in the first embodiment in the schematic diagrams and the like shown in FIGS. 1 to 7D, the same reference numerals are used, and repeated descriptions thereof are omitted.

[0048] In the laser processing method according to the second embodiment, the first irradiation step shown in FIGS. 4A and 4B and, after the first irradiation step, the second irradiation step shown in FIGS. 5A and 5B are repeatedly executed while scanning the optical axis of the laser beam LB irradiated onto the workpiece W until the depth of the bottomed hole BH reaches a predetermined depth. As a result, a part of the workpiece W corresponding to the irradiation region of the laser beam LB is removed, and a bottomed hole BH having a predetermined depth is formed.

[0049] In the first irradiation step, as shown in FIG. 8A, while injecting a high-speed and high-pressure supporting combustion gas Ga as an assist gas toward the irradiation point FP of the laser beam LB, the laser beam LB is scanned in a predetermined direction TD to perform processing. As a result, a molten pool MP having a depth Da is formed at the irradiation point FP of the laser beam LB on the workpiece W, and the molten pool MP moves due to the scanning of the laser beam LB.

[0050] Here, by injecting the supporting combustion gas Ga as an assist gas together with the irradiation of the laser beam LB, the high-speed injected supporting combustion gas Ga blows off the molten pool MP melted from the workpiece W. As a result, a bottomed hole BH having a depth Da is formed in a predetermined region of the workpiece W. At this time, an oxide film MO having a predetermined thickness remains on the bottom surface of the bottomed hole BH due to the oxidation reaction between the workpiece W and the supporting combustion gas Ga.

[0051] On the other hand, in the second irradiation step, as shown in FIG. 8B, while injecting a high-speed and high-pressure inert gas Gb as an assist gas toward the irradiation point FP of the laser beam LB so as to overlap the region processed in the first irradiation step, the laser beam LB is scanned in a predetermined direction TD to perform processing. As a result, a molten pool MP having a depth Db is formed at the irradiation point FP of the laser beam LB on the workpiece W, and the molten pool MP moves due to the scanning of the laser beam LB.

[0052] Here, by injecting the inert gas Gb as an assist gas while irradiating the laser beam LB, the inert gas Gb injected at high speed blows off the molten pool MP melted from the workpiece W, and a bottomed hole BH with a depth Db is formed in a predetermined region of the workpiece W. As a result of these, a bottomed hole BH with almost no oxide film MO remaining on the bottom surface can be obtained. And in the laser processing method according to the second embodiment, as in the case of the first embodiment, the above-described first irradiation step and second irradiation step are repeated until the hole depth specified in the processing program is reached.

[0053] As an example of the scanning procedure of the laser beam LB in the above-described predetermined region, as shown in FIG. 9A, the mode of moving the optical axis of the laser beam LB left and right in a substantially zigzag manner in a rectangular region, or as shown in FIG. 9B, in a similar rectangular region, the mode of moving the optical axis of the laser beam LB while shifting it one by one from left to right can be adopted. Further, the scanning of the laser beam LB may be set to pass through not only a linear but also a curved locus.

[0054] For example, as shown in FIG. 10A, a circular bottomed hole BH can also be formed by scanning the laser beam LB along a circumferential locus that is a concentric circle. Further, as shown in FIG. 10B, the laser beam LB may be configured to be scanned along a spiral locus from the center of the circle.

[0055] As a specific application example in the case of forming the circular bottomed hole BH as described above, for example, as shown in FIG. 11A, a through hole TH having a predetermined inner diameter is formed in the workpiece W, and then, as shown in FIG. 11B, a first irradiation step of scanning the laser beam LB in a circular region centered on the through hole TH is executed. Thereby, a bottomed hole BH with a depth Da communicating with the through hole TH is formed.

[0056] Subsequently, as shown in Fig. 11C, a second irradiation step is performed in which the laser beam LB is scanned over the same irradiation region (locus) as in the first irradiation step. As a result, while removing the oxide film MO remaining in the bottomed hole BH formed in the first irradiation step, a bottomed hole BH with a depth of (Da + Db) communicating with the through hole TH is formed. Then, similar to the case of the first embodiment, the above-described first irradiation step and second irradiation step are repeated until the hole depth specified in the machining program is reached.

[0057] According to such an application example, the bottomed hole BH formed by the laser processing method according to the second embodiment can be applied as a counterbore hole when tightening the head of a bolt or a nut to the workpiece W. At this time, since the bottom surface of the bottomed hole BH is formed as a surface with almost no remaining oxide film MO by the second irradiation step, finishing after processing is not required without exposing the blackened design surface due to the oxide film MO.

[0058] By having the above-described configuration, the laser processing method according to the second embodiment, in addition to the effects described in the first embodiment, performs processing while scanning the optical axis of the laser beam in a predetermined region, so that it is possible to form a bottomed hole with an arbitrary bottom surface shape. In particular, by forming a bolt hole or a through hole in the workpiece and forming a bottomed hole communicating therewith, it can also be applied to a counterbore hole having the bottom surface of the formed bottomed hole as a seating surface.

[0059] <Third Embodiment> Fig. 12 is a schematic diagram showing the configuration of a laser processing apparatus including a control apparatus for executing a laser processing method according to a third embodiment, which is still another example of the present invention. Fig. 13 is a block diagram showing an example of the configuration of the processing head and the gas supply mechanism shown in Fig. 12. In the third embodiment, for those components that can adopt the same or common configurations as those in the first and second embodiments in the schematic diagrams and the like shown in Figs. 1 to 11C, the same reference numerals are given and repeated descriptions thereof are omitted.

[0060] In the third embodiment, instead of the processing head 130 that coaxially emits (ejects) the laser beam LB and the assist gas (combustion-supporting gas Ga, inert gas Gb) from the nozzle as shown in the first embodiment, a configuration including a scanning head 330 that scans the optical axis of the laser beam LB by an optical system such as a mirror and a gas injection nozzle 354 that injects the assist gas to the irradiation point FP of the laser beam LB is used. Specifically, as shown in FIG. 12, as an example, the laser processing apparatus 300 includes a laser oscillator 110, a work holding mechanism 120, a scanning head 330 that scans and irradiates the optical axis of the laser beam LB within a predetermined region of the work W, a head transfer mechanism 140 that relatively moves the scanning head 330 with respect to the work holding mechanism 120, a gas supply mechanism 350 that supplies the assist gas to the irradiation point FP of the laser beam LB irradiated on the work W, and a control device 160 that controls the laser processing operation on the work W based on a processing program.

[0061] As an example, as shown in FIG. 13, the scanning head 330 includes a housing 332, a connector 334a that connects the transmission path 334 and the housing 332, a pair of scanning mirrors 336a, 336b that reflect the processing laser beam LB introduced from the connector 334a and set a scanning angle for scanning the optical axis of the laser beam LB, and a condensing optical system 338 that is disposed on the emission side of these scanning mirrors 336a, 336b and irradiates the laser beam LB onto the work W. With such a configuration, as shown in FIG. 13, the laser beam LB emitted from the scanning head 330 can move the irradiation point FP of the laser beam LB to an arbitrary position within a predetermined scanning region. Further, the scanning head 330 may be provided with a known configuration such as a cooling mechanism that cools various built-in optical systems.

[0062] The pair of scanning mirrors 336a and 336b includes, for example, mirror surfaces that totally reflect the laser beam LB, and by swinging these scanning mirrors at a minute angle, they have the function of moving (scanning) the optical axis of the laser beam LB. Examples of such scanning mirrors 336a and 336b include a galvanometer scanner that rotates a total reflection mirror around a predetermined galvanometer motor axis and swings it to an arbitrary angle, or a piezoelectric scanner that attaches a total reflection mirror to an actuator using a piezoelectric film and finely adjusts the angle of the total reflection mirror by energization, etc.

[0063] The condensing optical system 338 is an optical system that condenses the laser beam LB deflected by the pair of scanning mirrors 336a and 336b so as to form a focus at a predetermined position on the workpiece W, and is configured, for example, by combining a condensing lens, an fθ lens, etc. Thereby, the laser beam LB scanned within a predetermined scanning range is incident on the surface of the workpiece W substantially perpendicularly. Also, the condensing optical system 338 also has a function as a lid that seals the inside of the scanning head 330.

[0064] As an example, the gas supply mechanism 350 includes a combustible gas supply source 154a shown in FIG. 2, an inert gas supply source 154b, supply paths 155a and 155b, pressure sensors 156a and 156b, a switching unit 158 (not shown), a gas supply pipe 352 that guides the gas supplied from the switching unit 158, a gas injection nozzle 354 attached to one end of the gas supply pipe 352, and a nozzle moving mechanism 356 that moves the gas injection nozzle 354 so that it is at an arbitrary position and in an arbitrary direction.

[0065] As an example, the nozzle moving mechanism 356 is configured by a robot arm or the like having a gas injection nozzle 354 attached to one end, and based on an irradiation command signal from the main control unit 162 of the control device 160, moves the gas injection nozzle 354 so that its injection port is directed toward the irradiation point FP of the laser beam LB. Thereby, the assist gas (combustible gas Ga, inert gas Gb) is injected at the necessary timing to the irradiation point FP of the scanned laser beam LB.

[0066] The laser processing apparatus 300 that implements the laser processing method according to the third embodiment uses a scanning head 330 that scans the laser beam LB. Since it is not necessary to move the scanning head 330 significantly, the size of the head transfer mechanism 140 can be reduced or the structure can be simplified. Further, by using the laser processing apparatus 300 in combination with a gas supply mechanism 350 that injects assist gas at the irradiation point FP of the scanning head 330 and the laser beam LB, for example, the laser beam LB can be a so-called long-focus laser, so that remote processing for scanning the laser beam LB at high speed becomes possible.

[0067] By having the configuration as described above, the laser oscillator according to the third embodiment, in addition to the effects described in the first and second embodiments, can reduce or simplify the size of the scanning head and the head transfer mechanism by using a scanning head that can scan the optical axis of the laser beam at high speed.

[0068] Note that the present invention is not limited to the above-described embodiments, and can be appropriately modified without departing from the gist. Within the scope of the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted.

[0069] For example, in the above-described first to third embodiments, specific implementation modes of the laser processing method have been described. However, the present invention can be interpreted as including within the scope of the invention a processing program for causing a control device to implement the laser processing method, a control device including the processing program, or a storage medium storing the processing program.

Description of Reference Numerals

[0070] 100 Laser processing apparatus 110 Laser oscillator 120 Work holding mechanism 130 Processing head 132 Nozzle 134 Transmission path 140 Head transfer mechanism 142 Linear actuator 150 Gas supply mechanism 152 Gas supply pipe 154a Support flammable gas supply source 154b Inert gas supply source 155a, 155b Supply paths 156a, 156b Pressure sensors 158 Switching unit 160 Control device 162 Main control unit 164 Display unit 166 Input interface 300 Laser processing device 330 Scanning head 332 Housing 334 Transmission path 334a Connector 336a, 336b Scanning mirrors 338 Condensing optical system 350 Gas supply mechanism 352 Gas supply pipe 354 Gas injection nozzle 356 Nozzle movement mechanism

Claims

1. A laser processing method for forming a blind hole by irradiating a workpiece with a laser beam to remove a part of the workpiece, a first irradiation step of injecting a supporting combustible gas to an irradiation point when irradiating the laser beam, after the first irradiation step, a second irradiation step of injecting an inert gas to the irradiation point when irradiating the laser beam, and repeatedly executing until the depth of the blind hole reaches a predetermined depth, the first irradiation step is executed while moving the irradiation point, the second irradiation step is executed while moving the irradiation point along the same path as the first irradiation step Laser processing method.

2. The movement of the irradiation point in the first irradiation step and the second irradiation step is executed by moving a processing head that irradiates the laser beam The laser processing method according to claim 1.

3. The movement of the irradiation point in the first irradiation step and the second irradiation step is executed by a scanning head that scans the optical axis of the laser beam The laser processing method according to claim 1.

4. The irradiation points in the first irradiation step and the second irradiation step are moved so as to draw a circumferential or helical locus The laser processing method according to claim 2 or 3.

5. A processing program for causing a control device of a laser processing apparatus for forming a blind hole by irradiating a workpiece with a laser beam to remove a part of the workpiece to perform the following steps: a first irradiation step of injecting a supporting combustible gas to an irradiation point when irradiating the laser beam, After the first irradiation step, a second irradiation step of injecting an inert gas to the irradiation point when irradiating the laser beam, is repeatedly executed until the depth of the bottomed hole reaches a predetermined depth, The first irradiation step is executed while moving the irradiation point, The second irradiation step is executed while moving the irradiation point along the same path as the first irradiation step Processing program.

6. The movement of the irradiation point in the first irradiation step and the second irradiation step is executed by moving a processing head that irradiates the laser beam The processing program according to claim 5.

7. The movement of the irradiation point in the first irradiation step and the second irradiation step is executed by a scanning head that scans the optical axis of the laser beam The processing program according to claim 6.

8. The irradiation points in the first irradiation step and the second irradiation step are moved so as to draw a circular or spiral locus The processing program according to claim 6 or 7.

9. A control device for controlling the operation of a laser processing apparatus that forms a bottomed hole by irradiating a workpiece with a laser beam to remove a part of the workpiece, The control device includes a processing program for controlling the operation of the laser processing apparatus, The processing program is, A first irradiation step of injecting a supporting combustion gas to the irradiation point when irradiating the laser beam, After the first irradiation step, a second irradiation step of injecting an inert gas to the irradiation point when irradiating the laser beam, is repeatedly executed until the depth of the bottomed hole reaches a predetermined depth, The machining program causes the first irradiation step to be executed while moving the irradiation point, and causes the second irradiation step to be executed while moving the irradiation point along the same path as the first irradiation step. Control device.

10. The control device according to claim 9, wherein the machining program executes the movement of the irradiation point in the first irradiation step and the second irradiation step by moving a machining head that irradiates the laser beam.

11. The control device according to claim 10, wherein the machining program executes the movement of the irradiation point in the first irradiation step and the second irradiation step by a scanning head that scans the optical axis of the laser beam.

12. The control device according to claim 10 or 11, wherein the machining program moves the irradiation point in the first irradiation step and the second irradiation step so as to draw a circular or helical locus.

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