Laser processing method, processing program, and control device

Abstract

The present invention is a laser processing method for forming a bottomed hole by irradiating a workpiece with a laser beam to remove a part of the workpiece. The laser processing method repeatedly executes a first irradiation step in which a combustion-supporting gas is injected to an irradiation point when the laser beam is irradiated, and a second irradiation step in which the combustion-supporting gas is injected to the irradiation point after the first irradiation step until the depth of the bottomed hole reaches a predetermined depth. When the laser beam is irradiated, an inert gas is jetted toward the irradiation point.

Description

Technical Field

[0001] The present invention relates to a laser processing method for forming a bottomed hole by irradiating a workpiece with a laser beam to remove a portion of the workpiece. Background Art

[0002] Laser processing devices such as laser cutting machines and laser welding machines transmit a processing laser beam output from a laser oscillator and irradiate the workpiece, and move the processing laser beam and the workpiece relative to each other, thereby enabling predetermined processing. When such a laser processing device is used to process a thick metal plate, it is known that in order to achieve a deeper penetration depth at the irradiation point of the laser beam, a combustion-supporting gas such as oxygen is sprayed as an auxiliary gas to the irradiation point while processing is performed.

[0003] When laser processing is performed while injecting combustion-supporting gas, the oxidation reaction between the metal material of the metal plate and the oxygen contained in the combustion-supporting gas is used to promote heat generation, thereby achieving a deeper penetration. On the other hand, when the thickness of the metal plate to be processed becomes thicker or the processing speed becomes faster, there is a limit to the penetration depth, so processing sometimes becomes difficult.

[0004] As laser processing devices for improving such problems, for example, devices disclosed in the following Patent Documents 1 and 2 are known. In the laser processing devices disclosed in these documents, an inert gas is injected before the laser beam for main processing while irradiating the laser beam for pre-processing processing, thereby adjusting the surface of the workpiece and improving the absorption rate of the laser beam for main processing.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 11-104879

[0008] Patent Document 2: Japanese Patent Application Publication No. 2001-314986 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In the above-mentioned prior art, thicker workpieces can be processed compared to the case where no pretreatment is performed. However, when processing thicknesses that require multiple paths in cutting and drilling, and when processing recessed portions such as bottomed holes and grooves, an oxide film will remain on the surface of the workpiece after processing due to the oxidation reaction during processing by the laser beam.

[0011] Such an oxide film has a higher melting point than the base metal material, and the melt solidifies as it cools, so the surface is rough, which reduces the absorption rate of the laser beam. Therefore, when the same part is repeatedly laser processed through multiple paths, there is a problem that the desired penetration depth (processing depth) cannot be obtained due to the oxide film remaining on the surface of the workpiece after the previous path processing.

[0012] On the other hand, in previous laser processing, as a pretreatment for processing using an auxiliary gas as an auxiliary gas, attempts were made to perform laser processing while spraying an inert gas, or to perform laser processing using a mixed gas of an auxiliary gas containing an auxiliary gas and an inert gas, thereby suppressing the remaining oxide film after the above-mentioned processing. However, in either case, an auxiliary gas containing an auxiliary gas containing an auxiliary gas is used in the final processing, and therefore, there is still the problem that the oxide film cannot be avoided at the bottom after processing.

[0013] Based on such experience, a laser processing technology for forming bottomed holes is required, which can obtain a sufficient processing depth and a bottom without residual oxide film after processing when processing a hole or a recessed portion (bottomed hole) with a bottom remaining after processing through multiple paths.

[0014] Means for solving problems

[0015] A laser processing method according to one embodiment of the present invention forms a bottomed hole by removing a portion of the workpiece by irradiating a laser beam to the workpiece, wherein the laser processing method repeatedly performs a first irradiation step and a second irradiation step until the depth of the bottomed hole reaches a specified depth, wherein the first irradiation step is to spray a combustion-supporting gas toward the irradiation point when irradiating the laser beam, and the second irradiation step is to spray an inert gas toward the irradiation point when irradiating the laser beam after the first irradiation step.

[0016] In addition, another mode of the processing program of the present invention is used to enable a control device of a laser processing device to implement the steps shown below, wherein the laser processing device removes a portion of the workpiece by irradiating a laser beam to the workpiece to form a bottomed hole, and the processing program repeatedly executes a first irradiation step and a second irradiation step until the depth of the bottomed hole reaches a specified depth, wherein the first irradiation step is to spray a combustion-supporting gas toward the irradiation point when irradiating the laser beam, and the second irradiation step is to spray an inert gas toward the irradiation point when irradiating the laser beam after the first irradiation step.

[0017] In addition, a control device of another embodiment of the present invention controls the operation of a laser processing device, wherein the laser processing device removes a portion of the workpiece by irradiating a laser beam to the workpiece to form a bottomed hole. The control device includes a processing program for controlling the operation of the laser processing device, and the processing program repeatedly executes a first irradiation step and a second irradiation step until the depth of the bottomed hole reaches a specified depth. The first irradiation step is to spray a combustion-supporting gas toward the irradiation point when irradiating the laser beam, and the second irradiation step is to spray an inert gas toward the irradiation point when irradiating the laser beam after the first irradiation step.

[0018] Effects of the Invention

[0019] According to one method of the present invention, a first irradiation step and a second irradiation step are repeatedly performed until the depth of the bottomed hole reaches a specified depth. The first irradiation step is to spray a combustion-supporting gas toward the irradiation point when irradiating a laser beam. The second irradiation step is to spray an inert gas toward the irradiation point when irradiating a laser beam after the first irradiation step. Thus, a sufficient processing depth and a bottom without residual oxide film after processing can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram showing the configuration of a laser processing apparatus including a control device that executes the laser processing method according to the first embodiment, which is a representative example of the present invention.

[0021] Figure 2 Yes means Figure 1 A block diagram showing an example of the structure of the gas supply mechanism shown.

[0022] Figure 3 Yes means Figure 1 A block diagram showing an example of the structure of the control device shown.

[0023] Figure 4A It is a partial cross-sectional view showing a processing state when the first irradiation step of the laser processing method according to the first embodiment is performed.

[0024] Figure 4B It is a partial cross-sectional view showing a processing state when the first irradiation step of the laser processing method according to the first embodiment is performed.

[0025] Figure 5A It is a partial cross-sectional view showing a processing state when the second irradiation step of the laser processing method according to the first embodiment is performed.

[0026] Figure 5B It is a partial cross-sectional view showing a processing state when the second irradiation step of the laser processing method according to the first embodiment is performed.

[0027] Figure 6This is a flowchart showing a control operation executed by the main control unit of the control device according to the first embodiment.

[0028] Fig. 7A It is a partial cross-sectional view showing a continuous processing state when the laser processing method according to the first embodiment is performed.

[0029] Figure 7B It is a partial cross-sectional view showing a continuous processing state when the laser processing method according to the first embodiment is performed.

[0030] Figure 7C It is a partial cross-sectional view showing a continuous processing state when the laser processing method according to the first embodiment is performed.

[0031] Fig.7D It is a partial cross-sectional view showing a continuous processing state when the laser processing method according to the first embodiment is performed.

[0032] Fig. 8A This is a partial cross-sectional view showing a continuous processing state when a laser processing method according to a second embodiment as another example of the present invention is performed.

[0033] Figure 8B This is a partial cross-sectional view showing a continuous processing state when a laser processing method according to a second embodiment as another example of the present invention is performed.

[0034] Fig. 9A This is a partial plan view showing an example of a processing trajectory of a laser beam in the laser processing method according to the second embodiment.

[0035] Fig. 9B This is a partial plan view showing an example of a processing trajectory of a laser beam in the laser processing method according to the second embodiment.

[0036] Fig. 10A It is a partial plan view showing an example of a processing trajectory of a laser beam in a laser processing method according to a modified example of the second embodiment.

[0037] Fig. 10B It is a partial plan view showing an example of a processing trajectory of a laser beam in a laser processing method according to a modified example of the second embodiment.

[0038] Fig.11A It is a partial cross-sectional view showing a continuous processing state when the laser processing method according to the modified example of the second embodiment is executed.

[0039] Fig. 11B It is a partial cross-sectional view showing a continuous processing state when the laser processing method according to the modified example of the second embodiment is executed.

[0040] Fig. 11CIt is a partial cross-sectional view showing a continuous processing state when the laser processing method according to the modified example of the second embodiment is executed.

[0041] Fig.12 This is a schematic diagram showing the configuration of a laser processing apparatus including a control device that executes a laser processing method according to a third embodiment which is still another example of the present invention.

[0042] Fig.13 Yes means Fig.12 A block diagram showing an example of the structure of a machining head and a gas supply mechanism shown. DETAILED DESCRIPTION

[0043] The following, with the attached Figure 1 First, embodiments of a laser processing method, which is a representative example of the present invention, a processing program for executing the laser processing method, and a control device will be described.

[0044] <First embodiment>

[0045] Figure 1 This is a schematic diagram showing the structure of a laser processing device including a control device that executes the laser processing method of the first embodiment as a representative example of the present invention. Figure 2 Yes means Figure 1 A block diagram of an example of the structure of the gas supply mechanism shown. Figure 3 Yes means Figure 1 A block diagram showing an example of the structure of the control device shown.

[0046] like Figure 1 As shown, as an example of a laser processing device 100, it includes: a laser oscillator 110, which oscillates a laser beam LB for processing; a workpiece holding mechanism 120, which holds the workpiece W; a processing head 130, which irradiates the laser beam LB to the workpiece W; a head conveying mechanism 140, which moves the processing head 130 relative to the workpiece holding mechanism 120; a gas supply mechanism 150, which supplies auxiliary gas to the processing head 130; and a control device 160, which controls the laser processing action on the workpiece W according to the processing program.

[0047] The laser oscillator 110 uses an oscillation source with a wavelength having a high absorption rate according to the material of the workpiece W to be processed. As such a laser oscillator 110, as an example thereof, a laser oscillator capable of optical fiber transmission, such as a YAG laser, a YVO4 laser, an optical fiber laser, a disk laser, etc., can be exemplified. In addition, the laser beam LB output from the laser oscillator 110 can use either continuous oscillation or pulse oscillation, and can be transmitted to the processing head 130 via a transmission path 134 such as an optical fiber, for example.

[0048] As an example, the work holding mechanism 120 includes a chuck mechanism (not shown) for mounting the work W, and is configured to hold and fix the work W. The work holding mechanism 120 may include a rotation mechanism in addition to a mechanism for moving the work W in the XYZ three-axis directions.

[0049] As an example of the processing head 130, the laser beam LB is introduced from one end (upper end) side via a transmission path 134 such as an optical fiber, and is emitted from a nozzle 132 on the other end (lower end) side toward the workpiece W. At this time, the laser beam LB is converged to a predetermined beam diameter at a focal point FP on the workpiece W by a focusing lens (not shown) arranged inside the processing head 130.

[0050] Assist gas for assisting laser processing by laser beam LB is supplied to processing head 130 from gas supply mechanism 150 described later via gas supply pipe 152 at a predetermined pressure and flow rate. Assist gas supplied to processing head 130 is ejected from nozzle 132 coaxially with laser beam LB.

[0051] As an example of the head conveying mechanism 140, a linear drive body 142 is provided which is relatively movable in three axes X, Y, and Z which are orthogonal to each other, and a processing head 130 is mounted on one end of the linear drive body 142. In addition, the head conveying mechanism 140 may be configured as a 6-axis or 7-axis type industrial robot having a robot arm with a processing head 130 mounted on one end.

[0052] As an example of the gas supply mechanism 150, Figure 2 As shown, the combustion-supporting gas supply source 154a temporarily stores the combustion-supporting gas; the inert gas supply source 154b temporarily stores the inert gas; supply paths 155a and 155b respectively guide the supplied combustion-supporting gas and the inert gas; pressure sensors 156a and 156b respectively provided in the supply paths 155a and 155b; and a switching unit 158 ​​selectively switches the combustion-supporting gas or the inert gas supplied from the two supply paths 155a and 155b and delivers them to the gas supply pipe 152. The switching unit 158 ​​includes, for example, a switching valve, etc., and is configured to receive a supply instruction from the control device 160 and deliver the specified type of gas to the gas supply pipe 152.

[0053] In this specification, as the "combustible gas", pure oxygen (O2) gas, oxygen containing a small amount of nitrogen (N2), etc. can be used. On the other hand, as the "inert gas", nitrogen (N2) gas, helium (He) gas, argon (Ar) gas, etc. can be used. In addition, Figure 2 The pressure sensors 156a and 156b shown as examples may also be flow rate sensors, for example.

[0054] As an example of the control device 160, Figure 3 As shown, the control device 160 includes: a main control unit 162, which outputs drive instructions to the components of the laser processing device 100 according to the processing program; a display unit 164, which displays various parameters, etc.; and an input interface 166, which can manually input information for modifying the processing program and various parameters. In addition, in the control device 160, the main control unit 162 is connected to the laser oscillator 110, the workpiece holding mechanism 120, the head conveying mechanism 140, and the gas supply mechanism 150 in a wired or wireless manner, and exchanges signals with these peripheral devices to control the overall operation of the laser processing device 100.

[0055] As an example of the main control unit 162, it has the following functions: extracting information such as the processing path and processing conditions from the processing program, and outputting an output command signal for instructing the output of the laser beam LB to the laser oscillator 110. In addition, the main control unit 162 also has the following functions: 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 of the workpiece W and the processing head 130 to the workpiece holding mechanism 120 and the head conveying mechanism 140. In addition, the main control unit 162 also has the following functions: extracting information such as the type of auxiliary gas injected along with 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.

[0056] Next, use Figures 4A to 7D , a specific implementation of the laser processing method of the first embodiment is described.

[0057] Figure 4A and Figure 4B 1 is a partial cross-sectional view showing a processing state when the first irradiation step of the laser processing method of the first embodiment is performed. Figure 5A and Figure 5B 1 is a partial cross-sectional view showing a processing state when the second irradiation step of the laser processing method of the first embodiment is performed. Figure 6 is a flowchart showing the control operation performed by the main control unit of the control device of the first embodiment. FIG. 7A to FIG. 7D It is a partial cross-sectional view showing a continuous processing state when the laser processing method according to the first embodiment is performed.

[0058] In the laser processing method of the first embodiment, the first irradiation step is to spray the combustion-supporting gas Ga to the irradiation point FP when irradiating the laser beam LB, and the second irradiation step is to spray the inert gas Gb to the irradiation point FP when irradiating the laser beam LB after the first irradiation step until the depth of the bottomed hole BH reaches a predetermined depth. As a result, a part of the workpiece W is removed, and the bottomed hole BH of the predetermined depth is formed.

[0059] In the first irradiation step, as Figure 4A As shown, machining is performed while high-speed and high-pressure combustion-supporting gas Ga is ejected as 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 of a depth Da.

[0060] Here, the combustion-supporting gas Ga is injected as an auxiliary gas together with the irradiation of the laser beam LB, whereby the molten pool MP becomes hotter due to the effect of oxygen contained in the combustion-supporting gas Ga, thereby increasing the penetration depth Da. Furthermore, the combustion-supporting gas Ga injected at a high speed blows the molten molten pool MP away from the workpiece W, resulting in the following: Figure 4B As shown, a bottomed hole BH having a depth Da is formed in 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 an oxidation reaction between the workpiece W and the combustion-supporting gas Ga.

[0061] On the other hand, in the second irradiation step, as Figure 5A As shown, machining is performed while high-speed and high-pressure inert gas Gb is ejected as 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 of a depth Db.

[0062] Here, the inert gas Gb is injected as an auxiliary gas together with the irradiation of the laser beam LB, and thus, the vicinity of the molten pool MP becomes an inert gas atmosphere under the action of the inert gas Gb, so that no oxidation reaction occurs with the molten workpiece W. In addition, the inert gas Gb injected at a high speed blows the molten molten pool MP away from the workpiece W, as shown in FIG. Figure 5B As shown, a bottomed hole BH having a depth Db is formed in the workpiece W. As a result, a bottomed hole BH having almost no oxide film MO remaining on the bottom surface can be obtained although the hole depth is small.

[0063] In the laser processing method of the first embodiment in which the above-mentioned first irradiation step and second irradiation step are applied, Figure 6 As shown, first, the main control unit 162 of the control device 160 reads a processing program including the size and depth of the bottomed hole to be processed, the irradiation conditions of the laser beam, etc. from an external database or storage medium (not shown) (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 device 100.

[0064] Next, the main control unit 162 outputs a supply command signal to the gas supply mechanism 150 to switch to spraying the combustion-supporting gas Ga according to the gas supply conditions specified in the processing program (step S102). Next, the main control unit 162 outputs an irradiation command signal to the laser oscillator 110, the workpiece holding mechanism 120, and the head conveying mechanism 140 according to the irradiation conditions of the laser beam LB (step S103). Through the actions of these two steps, the above-mentioned "first irradiation step" is performed, as shown in FIG. Fig. 7A As shown in FIG. 1 , a bottomed hole BH having a depth Da is formed in the workpiece W. As shown in FIG.

[0065] Next, the main control unit 162 outputs a supply command signal to the gas supply mechanism 150 to switch to spraying the inert gas Gb according to the gas supply conditions specified in the processing program (step S104). Next, the main control unit 162 outputs an irradiation command signal to the laser oscillator 110, the workpiece holding mechanism 120, and the head conveying mechanism 140 according to the irradiation conditions of the laser beam LB (step S105). Through the actions of these two steps, the above-mentioned "second irradiation step" is performed, as shown in FIG. Figure 7B As shown, a bottomed hole BH having a depth (Da+Db) is formed in the workpiece W.

[0066] Next, the main control unit 162 obtains the hole depth (cumulative hole depth) of the bottomed hole BH formed in the previous processing (step S106). In the processing up to this point, as described above, the cumulative hole depth is (Da+Db).

[0067] Next, the main control unit 162 determines whether the hole depth of the bottomed hole BH obtained in step S106 has reached the final hole depth specified by the machining program (step S107). In step S107, if it is determined that the hole depth of the bottomed hole BH obtained has reached the specified hole depth, the main control unit 162 determines that the machining of the specified bottomed hole BH is completed, and ends the control operation based on the machining program.

[0068] On the other hand, in step S107, when it is determined that the hole depth of the bottomed hole BH obtained does not reach the designated 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 combustion-supporting gas Ga (step S102), and then outputs an irradiation command signal to the laser oscillator 110, the workpiece holding mechanism 120, and the head conveying mechanism 140 (step S103).

[0069] Through these actions, the second first irradiation step is repeated, such as Figure 7CAs shown, a bottomed hole BH having a depth of (2Da+Db) is formed in 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 an oxidation reaction between the workpiece W and the combustion-supporting gas Ga.

[0070] Next, the main control unit 162 outputs a supply command signal to switch the auxiliary gas to the inert gas Gb (step S104), and then outputs an irradiation command signal to the laser oscillator 110, the workpiece holding mechanism 120, and the head conveying mechanism 140 (step S105). Through these actions, the second irradiation step is repeated for the second time. Fig.7D As shown in FIG. 1 , a bottomed hole BH having a depth (2Da+2Db) is formed in the workpiece W where almost no oxide film MO remains.

[0071] Next, the main control unit 162 obtains the hole depth (cumulative hole depth) of the bottomed hole BH formed in the previous processing (step S106), and determines whether the obtained hole depth of the bottomed hole BH has reached the final hole depth specified by the processing program (step S107). In the repeatedly executed step S107, similarly to the first case, when it is determined that the obtained hole depth of the bottomed hole BH has reached the specified hole depth, the main control unit 162 determines that the processing of the specified bottomed hole BH is completed, and ends the control operation based on the processing program.

[0072] On the other hand, in step S107, if it is determined that the hole depth of the bottomed hole BH obtained does not reach the specified hole depth, the main control unit 162 returns to step S102 and performs the second repetitive operation. In this way, in the laser processing method of the first embodiment, the first irradiation step using the combustion-supporting gas Ga as the auxiliary gas and the second irradiation step using the inert gas Gb as the auxiliary gas are repeatedly performed, and as a result, a bottomed hole BH of a specified depth is formed in the workpiece W.

[0073] At this time, it is also possible to configure so that, when the hole depth of the bottomed hole BH specified by 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 laser irradiation conditions in the first irradiation step and the second irradiation step that are repeatedly performed can be appropriately adjusted. However, the laser irradiation conditions are adjusted so that the last machining that is repeatedly performed is machining based on the second irradiation step. Thus, a bottomed hole BH having a surface with almost no oxide film MO remaining is formed in the workpiece W.

[0074] By having the above-mentioned structure, the laser processing method of the first embodiment repeatedly performs the first irradiation step and the second irradiation step until the depth of the bottomed hole reaches a predetermined depth, thereby obtaining a sufficient processing depth and a bottom without a residual oxide film after processing. The first irradiation step is to spray a combustion-supporting gas to the irradiation point when irradiating the laser beam, and the second irradiation step is to spray an inert gas to the irradiation point when irradiating the laser beam after the first irradiation step. In addition, in the above-mentioned first embodiment, a specific mode of the representative laser processing method of the present invention is described, but as another mode, it is also possible to configure a processing program that causes the control device to execute each step of the above-mentioned laser processing method, and a control device that causes the laser processing device to execute the operation of the laser processing method described above including the processing program.

[0075] <Second embodiment>

[0076] Fig. 8A and Figure 8B 1 is a partial cross-sectional view showing a continuous processing state when executing the laser processing method of the second embodiment as another example of the present invention. Fig. 9A and Fig. 9B 1 is a partial top view showing an example of a processing trajectory of a laser beam in the laser processing method of the second embodiment. Fig. 10A and Fig. 10B 1 is a partial top view showing an example of a processing trajectory of a laser beam in a laser processing method according to a modified example of the second embodiment. Figures 11A to 11C It is a partial cross-sectional view showing a continuous processing state when the laser processing method according to the modified example of the second embodiment is executed.

[0077] Furthermore, in the second embodiment, Figure 1 to Figure 7D In the schematic diagrams and the like shown in the drawings, portions that can employ the same or common configurations as those of the first embodiment are denoted by the same reference numerals, and their repeated descriptions are omitted.

[0078] In the laser processing method of the second embodiment, the optical axis of the laser beam LB irradiated to the workpiece W is scanned while repeatedly performing Figure 4A and Figure 4B The first irradiation step shown and after the first irradiation step Figure 5A and Figure 5B The second irradiation step shown is performed until the bottomed hole BH reaches a predetermined depth. Thus, a portion of the workpiece W corresponding to the irradiation area of ​​the laser beam LB is removed, and a bottomed hole BH of a predetermined depth is formed.

[0079] In the first irradiation step, as Fig. 8AAs shown, while high-speed and high-pressure combustion-supporting gas Ga is sprayed as auxiliary 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 with a depth Da is formed on the workpiece W at the irradiation point FP of the laser beam LB, and the molten pool MP moves by the scanning of the laser beam LB.

[0080] Here, the combustion-supporting gas Ga is injected as an assist gas together with the irradiation of the laser beam LB, whereby the combustion-supporting gas Ga injected at a high speed blows off the molten weld pool MP from the workpiece W, and 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 an oxidation reaction between the workpiece W and the combustion-supporting gas Ga.

[0081] On the other hand, in the second irradiation step, as Figure 8B As shown, while high-speed and high-pressure inert gas Gb is sprayed as an auxiliary gas toward the irradiation point FP of the laser beam LB so as to overlap with the area 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 with a depth Db is formed on the workpiece W at the irradiation point FP of the laser beam LB, and the molten pool MP moves by scanning the laser beam LB.

[0082] Here, an inert gas Gb is injected as an assist gas together with the irradiation of the laser beam LB, whereby the inert gas Gb injected at a high speed blows off the molten weld pool MP from the workpiece W, and forms a bottomed hole BH with a depth Db in a predetermined area of ​​the workpiece W. As a result, a bottomed hole BH with almost no oxide film MO remaining on the bottom surface can be obtained. In the laser processing method of the second embodiment, the first irradiation step and the second irradiation step are repeatedly performed until the hole depth specified by the processing program is reached, as in the case of the first embodiment.

[0083] As an example of the scanning process of the laser beam LB in the above-mentioned predetermined area, the following can be adopted: Fig. 9A As shown in FIG. 1 , the optical axis of the laser beam LB is moved left and right in a roughly sawtooth shape in a rectangular area, or as shown in FIG. Fig. 9B As shown in FIG. 1 , the optical axis of the laser beam LB is shifted from left to right in the same rectangular area and moved at the same time. In addition, the scanning of the laser beam LB may be set to pass through a curved track in addition to a straight line.

[0084] For example, Fig. 10A As shown in FIG. 1 , a circular bottomed hole BH can also be formed by scanning the laser beam LB in a circular trajectory that becomes a concentric circle. Fig. 10B As shown, the laser beam LB may be configured to scan in a spiral trajectory from the center of the circle.

[0085] As a specific application example of forming the above-mentioned circular bottomed hole BH, for example Fig.11A As shown in FIG. 1 , a through hole TH having a predetermined inner diameter is formed in the workpiece W, and then, as shown in FIG. Fig. 11B As shown in FIG. 1 , a first irradiation step is performed in which the laser beam LB is scanned in a circular area centered on the through hole TH. Thus, a bottomed hole BH having a depth Da and communicating with the through hole TH is formed.

[0086] Then, if Fig. 11C As shown in FIG. 1 , a second irradiation step is performed in which the laser beam LB is scanned in the same irradiation area (track) as in the first irradiation step. Thus, while removing the oxide film MO remaining in the bottomed hole BH formed in the first irradiation step, a bottomed hole BH having a depth (Da+Db) connected to the through hole TH is formed. Then, as in the case of the first embodiment, the first irradiation step and the second irradiation step are repeated until the hole depth specified by the processing program is reached.

[0087] According to such an application example, the bottomed hole BH formed by the laser processing method of the second embodiment can be applied as a countersink when the head of a bolt or a nut is fastened to the workpiece W. At this time, the bottom surface of the bottomed hole BH is formed into a surface with almost no oxide film MO remaining by the second irradiation step, so the blackened appearance surface caused by the oxide film MO is not exposed, and finishing after processing is not required.

[0088] By having the above-mentioned structure, the laser processing method of the second embodiment, in addition to the effects described in the first embodiment, can form a bottomed hole with any bottom shape because the processing is performed while scanning the optical axis of the laser beam in a predetermined area. In particular, by forming a bolt hole or a through hole in the workpiece and forming a bottomed hole connected thereto, it can also be applied to countersinking with the bottom surface of the formed bottomed hole as a support surface.

[0089] <Third Embodiment>

[0090] Fig.12 : is a schematic diagram showing the structure of a laser processing device including a control device for executing the laser processing method according to the third embodiment as another example of the present invention. Fig.13 Yes means Fig.12 A block diagram of an example of the structure of the processing head and the gas supply mechanism shown in FIG. Figure 1 to Figure 11C In the schematic diagrams and the like shown in the drawings, portions that can employ the same or common configurations as those of the first and second embodiments are denoted by the same reference numerals, and their repeated descriptions are omitted.

[0091] In the third embodiment, instead of the processing head 130 shown in the first embodiment, which coaxially emits (injects) the laser beam LB and the auxiliary gas (combustion-supporting gas Ga, inert gas Gb) from the nozzle, a structure including a scanning head 330 for scanning the optical axis of the laser beam LB by an optical system such as a reflector and a gas injection nozzle 354 for injecting the auxiliary gas toward the irradiation point FP of the laser beam LB is used. Specifically, Fig.12 As shown, as an example of a laser processing device 300, it includes: a laser oscillator 110; a workpiece holding mechanism 120; a scanning head 330, which scans the optical axis of the laser beam LB in a specified area of ​​the workpiece W and irradiates it; a head conveying mechanism 140, which moves the scanning head 330 relative to the workpiece holding mechanism 120; a gas supply mechanism 350, which supplies auxiliary gas to the irradiation point FP of the laser beam LB irradiated on the workpiece W; and a control device 160, which controls the laser processing action on the workpiece W according to the processing program.

[0092] As an example of the scanning head 330, Fig.13 As shown, it includes: a housing 332; a connector 334a, which connects the transmission path 334 to the housing 332; a pair of scanning mirrors 336a, 336b, which reflect the processing laser beam LB introduced from the connector 334a and set the scanning angle of the optical axis of the laser beam LB; and a focusing optical system 338, which is arranged on the emission side of these scanning mirrors 336a, 336b and irradiates the laser beam LB onto the workpiece W. With such a structure, Fig.13 As shown, the laser beam LB emitted from the scanning head 330 can move the irradiation point FP of the laser beam LB to any position within a predetermined scanning area. In addition, the scanning head 330 may also have a known structure such as a cooling mechanism for cooling various built-in optical systems.

[0093] The pair of scanning mirrors 336a and 336b, for example, includes a mirror surface that totally reflects the laser beam LB, and has a function of moving (scanning) the optical axis of the laser beam LB by swinging these scanning mirrors at a small angle. Such scanning mirrors 336a and 336b may be, for example, a galvanometer scanner that swings a total reflection mirror at an arbitrary angle by rotating the total reflection mirror around a predetermined galvanometer motor shaft, or a piezoelectric scanner that mounts a total reflection mirror on an actuator using a piezoelectric film and finely adjusts the angle of the total reflection mirror by energizing it.

[0094] The focusing optical system 338 is an optical system that focuses the laser beam LB deflected by the pair of scanning mirrors 336a and 336b at a predetermined position on the workpiece W, and is configured as an optical system composed of, for example, a focusing lens, an fθ lens, etc. Thus, the laser beam LB scanned within a predetermined scanning range is incident on the surface of the workpiece W substantially vertically. In addition, the focusing optical system 338 also has a function as a cover that seals the inside of the scanning head 330.

[0095] An example of the gas supply mechanism 350 includes: Figure 2 The shown combustion-supporting gas supply source 154a, inert gas supply source 154b, supply paths 155a, 155b, pressure sensors 156a, 156b and a switching unit 158 ​​(not shown), and also include: a gas supply pipe 352 for guiding the gas supplied from the switching unit 158, a gas injection nozzle 354 installed at one end of the gas supply pipe 352, and a nozzle moving mechanism 356 for moving the gas injection nozzle 354 to an arbitrary position and direction.

[0096] As an example of the nozzle moving mechanism 356, a robot arm or the like having a gas injection nozzle 354 mounted on one end is used to move the gas injection nozzle 354 so that its injection port is directed toward the irradiation point FP of the laser beam LB according to an irradiation command signal from the main control unit 162 of the control device 160. Thus, the auxiliary gas (combustible gas Ga, inert gas Gb) is injected toward the irradiation point FP of the scanned laser beam LB at a desired timing.

[0097] The laser processing apparatus 300 implementing the laser processing method of the third embodiment uses a scanning head 330 for scanning the laser beam LB, and therefore does not need to move the scanning head 330 significantly, so that the size of the head conveying mechanism 140 can be reduced or the structure can be simplified. In addition, the laser processing apparatus 300 uses the scanning head 330 and the gas supply mechanism 350 for injecting an auxiliary gas toward the irradiation point FP of the laser beam LB together, thereby, for example, making the laser beam LB a so-called long-focus laser, and thus, it is possible to realize remote processing by scanning the laser beam LB at a high speed.

[0098] With the above-described configuration, the laser oscillator of the third embodiment can reduce or simplify the size of the scanning head and the head transport mechanism by using a scanning head capable of scanning the optical axis of the laser beam at high speed, in addition to the effects described in the first and second embodiments.

[0099] The present invention is not limited to the above-described embodiment, and can be appropriately modified without departing from the gist of the invention. The present invention can modify any structural element of the embodiment or omit any structural element of the embodiment within the scope of the invention.

[0100] For example, in the first to third embodiments described above, specific embodiments of the laser processing method are respectively described, but the present invention can be interpreted that a processing program for enabling a control device to implement the laser processing method, a control device including the processing program, or a storage medium storing the processing program are also included in the scope of the invention.

[0101] Description of Reference Numerals

[0102] 100 Laser processing equipment

[0103] 110 Laser Oscillator

[0104] 120 Workpiece holding mechanism

[0105] 130 Processing head

[0106] 132 Nozzle

[0107] 134 transmission lines

[0108] 140 head conveying mechanism

[0109] 142 Linear drive

[0110] 150 Gas supply mechanism

[0111] 152 Gas supply pipe

[0112] 154a Combustion-supporting gas supply source

[0113] 154b Inert gas supply source

[0114] 155a, 155b supply road

[0115] 156a, 156b pressure sensor

[0116] 158 Switching Unit

[0117] 160 Control Device

[0118] 162 Main control unit

[0119] 164 Display

[0120] 166 Input Interface

[0121] 300 Laser processing device

[0122] 330 Scanning Head

[0123] 332 Shell

[0124] 334 transmission lines

[0125] 334a Connector

[0126] 336a, 336b scanning mirrors

[0127] 338 Focusing optical system

[0128] 350 Gas supply mechanism

[0129] 352 Gas supply pipe

[0130] 354 Gas Injection Nozzle

[0131] 356Nozzle moving mechanism.

Claims

1. A laser processing method, wherein a portion of a workpiece is removed by irradiating a laser beam to the workpiece, thereby forming a bottomed hole, wherein: The laser processing method repeatedly performs a first irradiation step and a second irradiation step until the depth of the bottomed hole reaches a predetermined depth. The first irradiation step is to spray a combustion-supporting gas toward the irradiation point when irradiating the laser beam. The second irradiation step is performed after the first irradiation step, and an inert gas is sprayed toward an irradiation point while irradiating the laser beam.

2. The laser processing method according to claim 1, characterized in that: performing the first irradiation step while moving the irradiation point, The second irradiation step is performed while moving the irradiation point along the same path as that of the first irradiation step.

3. The laser processing method according to claim 2, characterized in that: The movement of the irradiation point in the first irradiation step and the second irradiation step is performed by moving a processing head that irradiates the laser beam.

4. The laser processing method according to claim 2, characterized in that: The movement of the irradiation point in the first irradiation step and the second irradiation step is performed by a scanning head that scans the optical axis of the laser beam.

5. The laser processing method according to claim 3 or 4, characterized in that: The irradiation points in the first irradiation step and the second irradiation step move so as to describe a circular or spiral trajectory.

6. A processing program for causing a control device of a laser processing device to implement the following steps, wherein the laser processing device forms a bottomed hole by removing a portion of the workpiece by irradiating the workpiece with a laser beam, wherein: The processing program repeatedly performs the first irradiation step and the second irradiation step until the depth of the bottomed hole reaches a predetermined depth. The first irradiation step is to spray a combustion-supporting gas toward the irradiation point when irradiating the laser beam. The second irradiation step is performed after the first irradiation step, and an inert gas is sprayed toward an irradiation point while irradiating the laser beam.

7. The processing program according to claim 6, characterized in that: performing the first irradiation step while moving the irradiation point, The second irradiation step is performed while moving the irradiation point along the same path as that of the first irradiation step.

8. The processing program according to claim 7, characterized in that: The movement of the irradiation point in the first irradiation step and the second irradiation step is performed by moving a processing head that irradiates the laser beam.

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

10. The processing program according to claim 8 or 9, characterized in that: The irradiation points in the first irradiation step and the second irradiation step move so as to describe a circular or spiral trajectory.

11. A control device for controlling the operation of a laser processing device, wherein the laser processing device forms a bottomed hole by removing a portion of a workpiece by irradiating a laser beam to the workpiece, wherein: The control device includes a processing program for controlling the operation of the laser processing device. The processing program repeatedly performs the first irradiation step and the second irradiation step until the depth of the bottomed hole reaches a predetermined depth. The first irradiation step is to spray a combustion-supporting gas toward the irradiation point when irradiating the laser beam. The second irradiation step is performed after the first irradiation step, and an inert gas is sprayed toward an irradiation point while irradiating the laser beam.

12. The control device according to claim 11, characterized in that: The processing program executes the first irradiation step while moving the irradiation point, and executes the second irradiation step while moving the irradiation point along the same path as the first irradiation step.

13. The control device according to claim 12, characterized in that: The processing program executes movement of the irradiation point in the first irradiation step and the second irradiation step by moving a processing head that irradiates the laser beam.

14. The control device according to claim 12, characterized in that: The processing program executes movement of the irradiation point in the first irradiation step and the second irradiation step by a scanning head that scans an optical axis of the laser beam.

15. The control device according to claim 13 or 14, characterized in that: The processing program moves the irradiation point in the first irradiation step and the second irradiation step so as to draw a circular or spiral trajectory.

Images