WO2024069758A1

WO2024069758A1 - Laser machining device and laser machining method

Info

Publication number: WO2024069758A1
Application number: PCT/JP2022/035960
Authority: WO
Inventors: 磊郭
Original assignee: ファナック株式会社
Priority date: 2022-09-27
Filing date: 2022-09-27
Publication date: 2024-04-04

Abstract

This laser machining device and laser machine method irradiate a plate-shaped workpiece with a laser beam to machine a welding groove in the workpiece. The laser processing device includes: a laser oscillator for emitting a laser beam; a machining head for guiding the laser beam such that the laser beam irradiates the workpiece perpendicular to the surface thereof; an air supply mechanism for supplying compressed air to the machining head as an assist gas; a workpiece holding mechanism for holding and moving the workpiece relative to the machining head; and a control device for controlling the operation of the components of the laser machining device. When a groove is machined, the control device outputs a beam-mode change command signal for changing the intensity distribution of the laser beam in accordance with the shape of the groove.

Description

Laser processing device and laser processing method

The present invention relates to a laser processing device and a laser processing method, and in particular to a laser processing device and a laser processing method for processing grooves for welding on plate-shaped workpieces.

When metal plates (especially thick plates) are butt-welded, a groove may be formed in advance at the butt joint. In the case of relatively thin plates, this groove can be formed by finishing the machined cross section, such as by shear cutting, but when forming a groove on the end face of a thick plate, it is generally processed using thermal cutting techniques such as gas cutting, electron beam cutting, and laser cutting.

In processing the grooves on the butt end faces of such thick plates, it is known that various shapes such as Y-shape, V-shape, U-shape, or J-shape are used depending on the plate thickness. In this case, when processing a groove that requires a constituent surface that is oblique to the original surface such as a Y-shape or V-shape, the cutting torch (processing head) needs to be inclined at a specified inclination angle in order to cut the inclined constituent surface, so an additional component for setting the inclination angle of the cutting torch is essential for the groove processing device.

In an attempt to solve these problems, for example, Patent Document 1 discloses a method of forming a groove by irradiating a laser beam perpendicularly onto the surface of a plate-shaped workpiece to form a continuous groove of a predetermined width on the workpiece surface, and then irradiating the inside of the groove with a further laser beam to cut the workpiece.

International Publication No. 2022/037797

As mentioned above, there is conventional technology for processing grooves on thick plate workpieces without tilting the processing head, but when trying to form the deep grooves required for the groove, it is necessary to use combustion-supporting oxygen gas or a mixed gas whose main component is oxygen as an assist gas in order to deepen the molten pool formed at the irradiation point of the laser beam. This makes the assist gas expensive and requires management of the surrounding atmosphere against fire.

On the other hand, when trying to form a deeper groove or a groove with a special cross-sectional shape, multiple passes of groove processing are required to form the groove shape, which creates the problem of an increase in the total processing time for groove processing.

In light of these circumstances, there is a demand for a laser processing device and a laser processing method that can reduce the cost of assist gas and the number of passes required for groove preparation.

In one aspect of the present invention, a laser processing device that irradiates a laser beam onto a plate-shaped workpiece to process a groove for welding in the workpiece includes a laser oscillator that emits a laser beam, a processing head that guides the laser beam so that it is irradiated perpendicularly to the surface of the workpiece, an air supply mechanism that supplies compressed air as an assist gas to the processing head, a workpiece holding mechanism that holds the workpiece and moves it relative to the processing head, and a control device that controls the operation of each component of the laser processing device, and the control device outputs a beam mode change command signal that changes the intensity distribution of the laser beam depending on the shape of the groove when processing the groove.

In accordance with one aspect of the present invention, a laser processing method for processing a welding groove in a plate-shaped workpiece by irradiating the workpiece with a laser beam includes a cutting kerf processing step for forming a cutting kerf in the workpiece using compressed air as an assist gas, and a groove processing step for forming a groove by irradiating the workpiece surface with a laser beam perpendicularly after the cutting kerf processing step, and in the groove processing step, the intensity distribution of the laser beam is changed according to the shape of the groove.

1 is a schematic diagram showing a configuration of a laser processing apparatus according to a first embodiment. 2 is a partial cross-sectional view showing an example of a specific configuration of the processing head shown in FIG. 1 . 2B is a partial cross-sectional view showing an example of the configuration of an advancing and retreating mechanism in the processing head shown in FIG. 2A. 2 is a block diagram showing an example of a specific configuration of the control device shown in FIG. 1 and a relationship between the control device and each component of the laser processing device. FIG. 3A to 3C are schematic diagrams showing a typical example of intensity distribution of a laser beam in the laser processing method according to the first embodiment. 3A to 3C are schematic diagrams showing a typical example of intensity distribution of a laser beam in the laser processing method according to the first embodiment. 5A to 5C are partial cross-sectional views showing an example of a processing procedure in the laser processing method according to the first embodiment. 5A to 5C are partial cross-sectional views showing an example of a processing procedure in the laser processing method according to the first embodiment. 5A to 5C are partial cross-sectional views showing an example of a processing procedure in the laser processing method according to the first embodiment. 5A to 5C are partial cross-sectional views showing an example of a processing procedure in the laser processing method according to the first embodiment. FIG. 11 is a block diagram showing an example of a specific configuration of a laser oscillator included in a laser processing apparatus according to a second embodiment. 13 is a block diagram showing an example of a specific configuration of a control device included in a laser processing apparatus according to a second embodiment, and a relationship between the control device and each component of the laser processing apparatus. FIG. 13 is a schematic diagram showing an example of intensity distribution of a laser beam in the laser processing method according to the second embodiment. FIG. FIG. 11 is a partial cross-sectional view showing a specific example of a transmission path from a laser oscillator according to a modified example of the second embodiment. 13 is a schematic diagram showing an example of intensity distribution of a laser beam in the laser processing method according to the modified example of the second embodiment. FIG.

Below, an embodiment of a laser processing device and a laser processing method according to a representative example of the present invention will be described with reference to the drawings.

First Embodiment
Fig. 1 is a schematic diagram showing the configuration of a laser processing apparatus according to a first embodiment, which is a representative example of the present invention. Fig. 2A is a partial cross-sectional view showing an example of a specific configuration of a processing head shown in Fig. 1. Fig. 2B is a partial cross-sectional view showing an example of a configuration of an advance/retract mechanism in the processing head shown in Fig. 2A. Fig. 3 is a block diagram showing an example of a specific configuration of a control device shown in Fig. 1 and the relationship between the control device and each component of the laser processing apparatus.

As shown in FIG. 1, the laser processing device 100 includes, as an example, a laser oscillator 110 that oscillates a laser beam LB for processing, a processing head 120 that irradiates the laser beam LB onto a workpiece W, a workpiece holding mechanism 130 that holds the workpiece W, a head transport mechanism 140 that moves the processing head 120 relative to the workpiece holding mechanism 130, a gas supply mechanism 150 that supplies assist gas to the processing head 120, and a control device 160 that controls the laser processing operation on the workpiece W based on a processing program.

The laser oscillator 110 is applied with an oscillation source of a wavelength with high absorption rate according to the material of the workpiece W to be processed. Examples of such a laser oscillator 110 include a gas laser oscillator using a laser gas such as _CO2 gas as a laser medium, a solid-state laser oscillator using a solid medium such as a YAG rod, a fiber laser oscillator, or a laser diode (LD). The laser beam LB emitted from the laser oscillator 110 is transmitted to the processing head 120 via an arbitrary transmission path 112.

2A, the machining head 120 introduces a laser beam LB from an introduction section 114 on one end (upper end) side and emits it from a nozzle 122 on the other end (lower end) side toward the workpiece W. Between the introduction section 114 and the nozzle 122, the machining head 120 includes a lens holder 124 that holds a first condenser lens CL1, a lens holder 126 that holds a second condenser lens CL2, a mode changing element holder 128 that holds a mode changing element AL that changes the intensity distribution (beam mode) of the laser beam LB, and an advance/retract mechanism 129 that advances and retracts the mode changing element holder 128 relative to the optical axis of the laser beam LB.

2B, the advance/retract mechanism 129 includes a drive unit (not shown) that drives the mode change element AL and the mode change element holding unit 128 to advance and retract between an insertion position P1 and a retraction position P2 relative to the laser beam LB in a manner that crosses the optical axis of the laser beam LB, and a slider 129a that guides the mode change element holding unit 128 along a line connecting the insertion position P1 and the retraction position P2, and an enclosed space S is formed inside. The advance/retract mechanism 129 is controlled to change the position of the mode change element holding unit 128 based on a beam mode change command signal from an intensity distribution control unit 164 of the control device 160, which will be described later.

In the example shown in FIG. 2B, a structure for inserting or retracting one mode-changing element AL is illustrated, but a structure in which two retraction positions P2 are provided on either side of the optical axis of the laser beam LB to drive two mode-changing element holders 128 forward and backward, or a structure in which a disk-shaped rotating mechanism is used instead of the slider 129a, and multiple mode-changing element holders 128 can be inserted or removed from the optical axis of the laser beam LB, etc. may also be used.

The mode-changing element AL is, for example, composed of an aspheric lens or a diffractive optical element (DOE). When the mode-changing element AL is inserted into the optical path of the laser beam LB, it has the property of changing the intensity distribution in the beam spot of the laser beam LB from the initial distribution emitted from the laser oscillator 110.

In addition, the lens holder 126 that holds the second focusing lens CL2 has the function of moving the second focusing lens CL2 in a direction along the optical axis of the laser beam LB. This makes it possible to change the focal length of the laser beam LB without changing the distance of the machining head 120 from the workpiece W.

Furthermore, a gas supply pipe 152 from a gas supply mechanism 150 described later is connected to the nozzle 122, and an assist gas that assists the laser processing by the laser beam LB is supplied at a predetermined pressure and flow rate through the gas supply pipe 152. The assist gas supplied to the processing head 120 is then sprayed from the nozzle 122 as a gas flow GF coaxially with the laser beam LB.

With the machining head 120 constructed in this way, it is possible to change the intensity distribution of the laser beam LB by moving the mode change element AL in and out of the laser beam LB based on commands from the control device 160, thereby controlling the focal point FP, i.e., the focal position, of the laser beam LB.

As an example, the workpiece holding mechanism 130 includes a chuck mechanism (not shown) for mounting the workpiece W, and is configured to grip and fix the workpiece W. The workpiece holding mechanism 130 may also include a rotation mechanism, in addition to a mechanism for moving the workpiece W in three axial directions of X, Y, and Z.

As an example, the head transport mechanism 140 includes a linear actuator 142 that moves relatively in three mutually orthogonal axial directions, XYZ, and the processing head 120 is attached to one end of the linear actuator 142. The head transport mechanism 140 may also be configured as a 6-axis or 7-axis industrial robot equipped with a robot arm having the processing head 120 attached to one end.

As an example, the gas supply mechanism 150 may be a gas supply source (not shown) that temporarily stores air as an assist gas. Alternatively, the gas supply mechanism 150 may be an air compressor that takes in air, compresses it, and supplies it. This eliminates the need to replace the gas supply source.

As shown in FIG. 3 as an example, the control device 160 includes a main control unit 161 that receives detection data from various sensors etc. provided in the laser processing apparatus 100 and controls the operation of each unit described later, a program analysis unit 162 that reads a processing program stored in a database etc. and analyzes the processing program, an irradiation position control unit 163 that outputs an irradiation position command signal to the work holding mechanism 130 and the head transport mechanism 140 to command the irradiation position of the laser beam LB on the work W based on the analysis result of the processing program, an intensity distribution control unit 164 that determines the intensity distribution (beam profile) in the beam spot of the laser beam LB based on the analysis result of the processing program and outputs a beam mode change command signal to the processing head 120, an output control unit 165 that outputs an output command signal such as the emission timing and output value of the laser beam LB to the laser oscillator 110 based on the analysis result of the processing program, a display unit 166 that displays operation information of the laser processing apparatus 100 such as the above-mentioned detection data, and an interface 167 for the operator to input various information. Note that while FIG. 3 illustrates an example in which the display unit 166 and the interface 167 are configured separately, the display unit 166 may be configured to be a panel display means capable of receiving touch input, and the two may be integrated.

The main control unit 161 sends the control commands analyzed by the program analysis unit 162 (described later) to the irradiation position control unit 163, the intensity distribution control unit 164, the output control unit 165, or the display unit 166 according to their contents, and is also connected to various sensors (not shown) of the laser processing device 100 and receives their detection signals. As an example, the main control unit 161 may be configured to receive position information of the workpiece W and the processing head 120 from position sensors provided in the workpiece holding mechanism 130 and the head transport mechanism 140, or to receive the output value of the laser beam LB from an output detector (not shown), and perform feedback control based on these detection data.

As an example, the program analysis unit 162 reads and analyzes blocks of a machining program from an external storage device (not shown) such as a database, thereby determining control commands such as the machining path and the output or beam profile of the laser beam LB contained in the machining program, and temporarily stores and saves the read machining program blocks. The program analysis unit 162 then sends the determined control commands of the machining program to the main control unit 161.

As an example, the irradiation position control unit 163 receives control commands including the optical axis and focal position of the laser beam LB and the movement position of the workpiece W based on the machining program from the main control unit 161, and outputs irradiation position command signals individually to the workpiece holding mechanism 130 and the head transport mechanism 140. The irradiation position control unit 163 may also be configured to have the function of calculating the irradiation coordinate values (x, y, z) of the focal point FP when the laser beam LB is irradiated onto the workpiece W based on the command position for the workpiece holding mechanism 130 and the movement position for the head transport mechanism 140, and sending them back to the main control unit 161.

As an example, the intensity distribution control unit 164 determines the intensity distribution of the beam spot of the laser beam LB on a specified machining path based on the machining program from the main control unit 161, and outputs a beam mode change command signal to the machining head 120. The intensity distribution control unit 164 also has a function of determining the height of the focal point FP of the laser beam LB with respect to the workpiece W, i.e., the focal position, and outputting a focal position control signal that controls the position of the second focusing lens CL2 to the lens holding unit 126.

As an example, the output control unit 165 receives a control command from the main control unit 161, which includes an output value of the laser beam LB corresponding to the irradiation coordinate values (x, y, z) on the machining path based on the machining program, and outputs an output command signal to the laser oscillator 110.

Next, a specific example of the operation of the laser processing method according to the first embodiment will be described with reference to Figures 4A to 5D.

FIGS. 4A and 4B are schematic diagrams showing a representative example of the intensity distribution of a laser beam in the laser processing method according to the first embodiment. Also, FIGS. 5A to 5D are partial cross-sectional views showing an example of the processing procedure in the laser processing method according to the first embodiment.

In the laser processing method according to the first embodiment, air is used as an assist gas, and a laser beam LB with appropriately controlled diameter and intensity distribution (beam profile) at the beam spot is formed on the surface of the workpiece W. At this time, the air used as an assist gas contains oxygen, which accounts for approximately 20% of the gas, and promotes the oxidation reaction between the metal of the workpiece W and the laser beam LB, while the majority of the gas, nitrogen, accounts for approximately 80%, acts to blow away the molten molten pool MP.

As a result, compared to when a combustion-supporting gas (such as oxygen gas or a gas containing oxygen as the main component) is generally used as an assist gas, it is possible to process grooves of any shape at a lower cost. In addition, since no combustion-supporting gas is used, there is no need to control the surrounding atmosphere against fire.

As an example of a characteristic process of the laser processing method according to the first embodiment described above, for example, as shown in FIG. 4A, when a laser beam LB showing a cross-sectional intensity distribution simulating a so-called normal distribution (Gaussian distribution) with respect to the beam spot radius r is irradiated onto a workpiece W on which a cutting kerf has been formed in advance, a gas flow GF from the assist gas blows away the molten pool MP generated by the irradiated laser beam LB. By performing this continuously along the processing path, a continuous groove (a so-called "V-shaped groove") including a groove surface GS with a cross-sectional shape approximating a shape obtained by inverting the intensity distribution upside down is formed in the workpiece W in one pass.

On the other hand, as described above, when the intensity distribution control unit 164 of the control device 160 outputs a beam mode change command signal, the advance/retract mechanism 129 of the machining head 120 is driven to insert the mode change element AL into the optical path of the laser beam LB, thereby changing the intensity distribution (beam profile) at the beam spot of the laser beam LB. Then, by performing groove machining using the laser beam LB with the changed intensity distribution, a groove having a shape different from the V-groove described above can be formed in the workpiece W.

In other words, as an example, as shown in FIG. 4B, when a laser beam LB showing an intensity distribution with a cross-sectional shape simulating a so-called top hat shape, in which the peak intensity is low but the peak range is wide relative to the beam spot radius r, is irradiated onto a workpiece W on which a cutting kerf has been formed in advance, the gas flow GF of the assist gas blows away the molten pool MP created by the irradiated laser beam LB, as in the case of FIG. 4A. By performing this continuously along the machining path, a continuous groove (a so-called "J-shaped groove") including a groove surface GS with a cross-sectional shape approximating the shape obtained by upside down the intensity distribution is formed in the workpiece W in one pass.

In light of the above, a typical procedure for the laser processing method according to the first embodiment is to first perform a cutting kerf processing step in which a cutting kerf that will become the butt end surface of the groove to be formed is formed. That is, as an example, as shown in FIG. 5A, a laser beam LB irradiated with the surface of the workpiece W as the focal position forms a molten pool MP, and an assist gas (air) injected coaxially with the laser beam LB blows away the molten pool MP.

Then, by continuously performing this type of processing while moving in a specified groove forming direction (not shown), a continuous groove (cutting kerf K) is formed on the processing path of the workpiece W, as shown in FIG. 5B. At this time, by providing a recess 132 along the processing path in advance in the workpiece holding mechanism 130 located on the back side of the workpiece W, the molten pool MP is blown to the back side by the assist gas.

In FIG. 5A, the cutting kerf processing step is exemplified as a case in which the operation of blowing away the molten pool MP formed by the laser beam LB along the processing path and processing a groove is repeated multiple times, but the output and focal position of the laser beam LB may be appropriately adjusted to form a molten pool MP that is narrow in the thickness direction of the workpiece W and spans the entire thickness (i.e., a so-called "piercing process" is performed), and the cutting kerf K may be formed by moving the molten pool along the processing path while blowing it away.

Next, a groove processing step is performed on the workpiece W on which the cutting kerf K has been formed, to process a predetermined groove surface GS. That is, as an example, as shown in FIG. 5C, a laser beam LB adjusted to a predetermined intensity distribution (beam profile) is irradiated along the formed cutting kerf K to form a beam spot of radius r.

Then, the molten pool MP formed by the irradiated laser beam LB is blown away by the gas flow GF of the assist gas sprayed from the nozzle 122 of the processing head 120. By continuously performing such an operation along the cutting kerf K on the processing path, a V-shaped groove having a continuous groove surface GS is formed in the workpiece W, as shown in FIG. 5D.

By being provided with the above-described configuration, the laser processing device and laser processing method according to the first embodiment use a processing head including a beam mode changing element that changes the intensity distribution in the beam spot of the laser beam, and perform groove processing using air as an assist gas while irradiating a laser beam that has been adjusted to an intensity distribution according to the groove shape to be processed, thereby reducing the cost of the assist gas and the number of passes for groove processing.

Second Embodiment
Fig. 6 is a block diagram showing an example of a specific configuration of a laser oscillator included in a laser processing apparatus according to a second embodiment of the present invention. Fig. 7 is a block diagram showing an example of a specific configuration of a control device included in the laser processing apparatus according to the second embodiment, and a relationship between the control device and each component of the laser processing apparatus. Fig. 8 is a schematic diagram showing an example of an intensity distribution of a laser beam in a laser processing method according to the second embodiment.

In the second embodiment, in the schematic diagrams shown in Figures 1 to 5D, components that may be the same as or in common with the first embodiment are given the same reference numerals and repeated explanations of these components are omitted.

As shown in FIG. 6, the laser processing device according to the second embodiment differs in configuration from the laser processing device according to the first embodiment in that, instead of inserting a mode changing element AL in the optical path of the laser beam LB as a means for changing the intensity distribution in the beam spot of the laser beam LB, a laser oscillator 210 including multiple

laser oscillation sources

214a, 214b is used to change the intensity distribution by superimposing multiple laser beams LBa, LBb.

That is, as described above, the laser oscillator 210 in the laser processing device according to the second embodiment includes, as an example shown in FIG. 6, a first laser oscillation source 214a that emits a first laser beam LBa, a first driving power supply 215a that supplies driving power to the first laser oscillation source 214a, a first transmission path 216a that transmits the first laser beam LBa emitted from the first laser oscillation source 214a, a second laser oscillation source 214b that emits a second laser beam LBb, a second driving power supply 215b that supplies driving power to the second laser oscillation source 214b, a second transmission path 216b that transmits the second laser beam LBb emitted from the second laser oscillation source 214b, and a coupling optical system 218 that coaxially superimposes the transmitted first laser beam LBa and second laser beam LBb. The laser beam LB combined by the coupling optical system 218 is transmitted to the processing head 120 via the transmission path 212.

The oscillation control unit 213 receives an output command signal from the control device 260, which will be described later, and performs oscillation control to continuously output a drive command signal to the first drive power supply 215a or the second drive power supply 215b in accordance with the emission timing contained in the output command signal. In addition, the oscillation control unit 213 can output drive command signals to the first drive power supply 215a and the second drive power supply 215b separately and independently. This makes it possible to control both to oscillate simultaneously, or to oscillate only one of them.

As an example, as shown in FIG. 7, the control device 260 includes a main control unit 261, a program analysis unit 262, an irradiation position control unit 263, an output control unit 265, a display unit 266, and an interface 267. Note that the control device 260 may also be configured to integrate the display unit 266 and the interface 267.

As an example, the output control unit 265 in the second embodiment receives a control command from the main control unit 261, which includes a power distribution in the beam spot of the laser beam LB corresponding to the irradiation coordinate values (x, y, z) on the machining path based on the machining program, determines which of the multiple laser oscillation sources is to be driven to obtain the power distribution, and outputs an output command signal to the laser oscillator 210, which includes the timing and output value of the laser oscillation source to be driven.

In the laser processing method according to the second embodiment, air is used as the assist gas as in the first embodiment, and when performing the groove processing step, a designated laser oscillation source is selectively driven based on an output command signal from the output control unit 265.

Specifically, as an example, as shown in FIG. 8, when a drive command signal is output only to the first laser oscillation source 214a, a first laser beam LBa having an intensity distribution with a cross-sectional shape that imitates a normal distribution (Gaussian distribution) is emitted. On the other hand, when a drive command signal is output only to the second laser oscillation source 214b, a second laser beam LBb having an intensity distribution with a cross-sectional shape that imitates a so-called top hat shape is emitted.

Furthermore, when a drive command signal is output to both the first laser oscillation source 214a and the second laser oscillation source 214b, a laser beam LB having an intensity distribution obtained by superimposing the two is emitted. In this way, the intensity distribution in the beam spot of the laser beam LB can be arbitrarily selected according to the groove shape to be processed.

Next, an embodiment of a laser processing device and a laser processing method according to a modified example of the second embodiment will be described with reference to Figures 9 and 10.

FIG. 9 is a partial cross-sectional view showing a specific example of a transmission path from a laser oscillator according to a modified example of the second embodiment. Also, FIG. 10 is a schematic diagram showing an example of the intensity distribution of a laser beam in a laser processing method according to a modified example of the second embodiment.

In the laser processing device according to the modified example of the second embodiment, the transmission path 212, which is the exit of the laser beam LB from the laser oscillator 210, is configured as an optical fiber having multiple light guide paths. Specifically, as an example, as shown in FIG. 9, the transmission path 212 includes a first core layer 212a that transmits the first laser beam LBa at the center, a second core layer 212b that is arranged to surround the first core layer 212a and transmits the second laser beam LBb, a cladding layer 212c that is arranged to further surround the second core layer 212b, and a coating layer 212d that protects the surface of the cladding layer 212c.

As an example of the laser processing method according to a modified example of the second embodiment, as shown in FIG. 10, the first laser beam LBa transmitted through the first core layer 212a has an intensity distribution concentrated near the center of the beam spot, while the second laser beam LBb transmitted through the second core layer 212b has an intensity distribution in a substantially ring shape outside the first laser beam LBa. When the first laser beam LBa and the second laser beam LBb are emitted simultaneously, a beam spot is obtained in which the beams are combined to have an intensity distribution in a substantially top hat state. In this way, by overlapping the regions rather than overlapping the intensities of multiple laser beams LB, it is possible to obtain a beam spot with an arbitrary intensity distribution.

By being configured as described above, the laser processing device and laser processing method according to the second embodiment uses air as an assist gas, and a laser oscillator equipped with multiple laser oscillation sources is used, and the output control unit of the control device selects which of the multiple laser oscillation sources to drive and overlaps the laser beams. This makes it possible to reduce the cost of assist gas and reduce the number of passes for groove processing.

The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the invention. Any of the components of the embodiment can be modified or omitted within the scope of the invention.

REFERENCE SIGNS LIST 100 Laser processing device 110 Laser oscillator 112 Transmission path 114 Introduction section 120 Processing head 122 Nozzle 124 Lens holding section 126 Lens holding section 128 Mode change element holding section 129 Advance/retract mechanism 129a Slider 130 Work holding mechanism 132 Recess 140 Head transport mechanism 142 Linear drive body 150 Gas supply mechanism 152 Gas supply pipe 160 Control device 161 Main control section 162 Program analysis section 163 Irradiation position control section 164 Intensity distribution control section 165 Output control section 166 Display section 167 Interface 210 Laser oscillator 212 Transmission path 212a First core layer 212b Second core layer

212c Cladding layer

212d Covering layer 213 Oscillation control section 214a First laser oscillation source 214b Second laser oscillation source 215a First driving power supply 215b Second driving power supply 216a First transmission path 216b Second transmission path 218 Coupling optical system 260 Control device 261 Main control unit 262 Program analysis unit 263 Irradiation position control unit 265 Output control unit 266 Display unit 267 Interface AL Mode change element CL1 First condenser lens CL2 Second condenser lens FP Focus point GF Gas flow GS Groove surface K Cut kerf LB Laser beam LBa First laser beam LBb Second laser beam MP Molten pool P1 Insertion position P2 Evacuation position W Workpiece

Claims

A laser processing apparatus that irradiates a plate-shaped workpiece with a laser beam to process a welding groove in the workpiece,
a laser oscillator that emits the laser beam;
A processing head that guides the laser beam so as to irradiate the surface of the workpiece perpendicularly;
an air supply mechanism for supplying compressed air as an assist gas to the processing head;
a workpiece holding mechanism that holds the workpiece and moves it relative to the machining head;
A control device for controlling the operation of each component of the laser processing device;
Including,
The control device is a laser processing device that outputs a beam mode change command signal that changes the intensity distribution of the laser beam in accordance with the shape of the groove when processing the groove.
The laser processing apparatus according to claim 1 , wherein the air supply mechanism includes a compressor.
3. The laser processing apparatus according to claim 1, wherein the processing head has a function of inserting a mode changing element for changing an intensity distribution of the laser beam into an optical path of the laser beam based on the beam mode change command signal.
4. The laser processing apparatus according to claim 3, wherein the mode-changing element is an aspheric lens.
4. The laser processing apparatus according to claim 3, wherein the mode changing element is a diffractive optical element.
3. The laser processing apparatus according to claim 1 or 2, wherein the laser oscillator includes a plurality of laser oscillation sources and has a function of changing the intensity distribution of the laser beam by coaxially overlapping the plurality of laser beams emitted from the plurality of laser oscillation sources based on the beam mode change command signal.
7. The laser processing apparatus according to claim 6, wherein the plurality of laser beams are transmitted through an optical fiber having a plurality of light guide paths.
A laser processing method for irradiating a plate-shaped workpiece with a laser beam to process a welding groove in the workpiece,
Compressed air is used as the assist gas.
A cutting kerf processing step of forming a cutting kerf on the workpiece;
After the cutting kerf processing step, a groove processing step of irradiating the laser beam perpendicularly to the surface of the workpiece to form the groove;
Including,
A laser processing method in which, in the groove processing step, an intensity distribution of the laser beam is changed according to a shape of the groove.
The laser processing method according to claim 8 , wherein the compressed air is supplied by a compressor.
10. The laser processing method according to claim 8, wherein the intensity distribution of the laser beam is changed by inserting a mode changing element in an optical path of the laser beam.
The method of claim 10 , wherein the mode-changing element is an aspheric lens.
The laser processing method according to claim 10 , wherein the mode-changing element is a diffractive optical element.
10. The laser processing method according to claim 8, wherein the change in intensity distribution of the laser beam is performed by coaxially overlapping a plurality of laser beams.
The laser processing method according to claim 13, wherein the plurality of laser beams are transmitted through an optical fiber having a plurality of light guide paths.