Laser welding apparatus, laser welding method, and machining program generation method

Abstract

To stably obtain a constant welding depth in the whole length of a welding section.SOLUTION: A laser welding apparatus includes an oscillator that oscillates a laser beam having a wavelength used for laser welding of a welding object that is a metal having thermal conductivity, an irradiation unit that irradiates the welding object with the laser beam from the oscillator, and a control device that performs at least division processing of dividing a welding section of the laser welding on the welding object into at least two, determination processing of determining a machining condition of the laser welding for each of two or more welding sections obtained by the division processing, and generation processing of generating a machining program based on the machining condition for each of the two or more welding sections obtained by the determination processing. The control device controls irradiation of the object to be welded with the laser beam based on a processing program.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a laser welding apparatus, a laser welding method, and a processing program generation method. [Background technology]

[0002] Patent Document 1 discloses a laser welding method in which a laser beam and a measurement beam having a different wavelength from the laser beam are superimposed coaxially and irradiated onto a weld, and the penetration depth of the weld is repeatedly measured based on the measurement beam reflected by the weld. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7320703 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure has been devised in view of the conventional circumstances, and aims to provide a laser welding apparatus, a laser welding method, and a processing program generation method that can stably obtain a constant welding depth over the entire length of a welding section. [Means for solving the problem]

[0005] The present disclosure provides a laser welding apparatus comprising: an oscillator that emits laser light of a wavelength used for laser welding of a welding object that is a thermally conductive metal; an irradiation unit that irradiates the laser light from the oscillator onto the welding object; and a control device that performs at least a division process that divides a welding section of the laser welding of the welding object into at least two sections; a determination process that determines processing conditions for the laser welding for each of the two or more welding sections obtained by the division process; and a generation process that generates a processing program based on the processing conditions for each of the two or more welding sections obtained by the determination process, wherein the control device controls the irradiation of the laser light onto the welding object based on the processing program.

[0006] The present disclosure also provides a laser welding method executed by a laser welding device, the laser welding method comprising at least the steps of: oscillating, by an oscillator, laser light of a wavelength used for laser welding of a welding object that is a thermally conductive metal; a division process that divides a welding section of the welding object for the laser welding into at least two sections; a determination process that determines processing conditions for the laser welding for each of the two or more welding sections obtained by the division process; and a generation process that generates a processing program based on the processing conditions for each of the two or more welding sections obtained by the determination process; and a step of controlling the irradiation of the laser light onto the welding object based on the processing program.

[0007] The present disclosure also provides a processing program generation method, the method comprising: an oscillator that emits laser light of a wavelength used for laser welding of a welding object that is a thermally conductive metal; an irradiation unit that irradiates the laser light from the oscillator onto the welding object; a division process executed by a connected control device, which divides a welding section of the laser welding on the welding object into at least two sections; a determination process that determines processing conditions for the laser welding for each of the two or more welding sections obtained by the division process; and a generation process that generates a processing program based on the processing conditions for each of the two or more welding sections obtained by the determination process. [Effects of the Invention]

[0008] According to the present disclosure, a constant weld depth can be stably obtained over the entire length of the welded section. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of a schematic configuration of a laser welding device according to each embodiment; [Figure 2] Graph showing an example of the relationship between the light absorption rate of metals and wavelength [Figure 3] (a) An example of the change in weld depth over time when laser welding mild steel. (b) An example of the change in weld depth over time when laser welding copper. [Figure 4] (a)(b) Diagram showing an example of variation in welding depth due to differences in copper plate thickness [Figure 5] FIG. 1 is a diagram showing an example of an outline of the operation of a laser welding method according to the first embodiment; [Figure 6] An example of the processing conditions screen displayed on the teaching pendant [Figure 7] A diagram showing an example of the learning operation procedure for the welding result estimation model in chronological order. [Figure 8] A diagram showing an example of the relationship between the welding section and the laser beam preheating effect and laser beam postheating effect. [Figure 9] An example of the temperature dependence of the optical absorptance of copper for near-infrared wavelengths. [Figure 10] 1 is a flowchart showing an example of an operation procedure of a laser welding method according to a first embodiment in chronological order. [Figure 11] FIG. 10 is a diagram showing an example of an experimental result under first experimental conditions using the laser welding method according to the first embodiment. [Figure 12] FIG. 10 is a diagram showing an example of an experimental result under a second experimental condition using the laser welding method according to the first embodiment. [Figure 13] FIG. 10 is a diagram showing a first modified example of test data. [Figure 14] FIG. 2 shows a second modified example of test data. [Figure 15] FIG. 10 is a diagram showing a schematic diagram of butt welding of three plates according to the second embodiment; [Figure 16] 16 is a diagram showing an example of a welding location when butt welding the three plates of FIG. 15. [Figure 17] FIG. 10 is a diagram schematically illustrating butt welding of four plates according to a second embodiment. [Figure 18] FIG. 17 shows an example of a welding location when butt welding the four plates of FIG. 16. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Background to the first embodiment) Welding sites require a consistent, consistent penetration depth across the weld zone. To achieve a consistent penetration depth, welding workers (hereafter referred to as "workers") must find optimal processing conditions through repeated trial and error. While demand for copper processing using lasers has been increasing in recent years, workers have struggled to find the optimal processing conditions due to the lack of demand for copper processing. Copper has high thermal conductivity and, compared to other metals, its optical absorption rate varies significantly depending on the wavelength of light, such as laser light (see Figure 2), resulting in significant thermal impact on the surrounding area around the weld. Figure 2 shows an example of the relationship between optical absorption rate and wavelength for metals. Copper has a high optical absorption rate of approximately 60% in the blue wavelength band of 440 nm, but a low optical absorption rate of approximately 10% in the near-infrared wavelength band of 975 nm. This variation in optical absorption rate can lead to unstable molten pools and spatter. In other words, because the optical absorption rate of metals varies depending on the wavelength of the laser light, the weld depth (penetration depth) also varies depending on the wavelength of the laser light used. As shown in FIG. 2, it can be seen that the light absorptance does not vary significantly with wavelength for metals other than copper (for example, iron, nickel, aluminum, and silver).

[0011] As such, it is known that it is difficult to maintain a constant penetration depth throughout the welded section of copper processing. Because the penetration depth is unstable, for example, if the penetration depth is shallow, the weld strength may be insufficient, and if the penetration depth is deep, full-penetration welding may occur even though non-penetration welding is required, damaging the appearance of the workpiece. Patent Document 1 discloses a technology for monitoring penetration depth, but Patent Document 1 does not anticipate identifying optimal processing conditions for copper processing.

[0012] This is particularly evident with copper, which has high thermal conductivity. Even when welding under the same processing conditions, differences in welding results (e.g., penetration depth) can occur between welded sections due to thermal effects (see Figures 3 and 4). Figure 3(a) shows an example of the change in weld depth over time when laser welding mild steel, and Figure 3(b) shows an example of the change in weld depth over time when laser welding aluminum. Figures 4(a) and 4(b) show examples of weld depth variation due to differences in copper plate thickness. As shown in Figure 3(b), with aluminum, which has high thermal conductivity, the penetration depth tends to be shallow in the first welded section due to thermal effects, and to deepen as the weld progresses. This tendency is also observed with copper, which has high thermal conductivity like aluminum. On the other hand, with mild steel, which has low thermal conductivity, the penetration depth tends to remain stable throughout almost the entire length of the welded section, from the first to the last welded section (see Figure 3(a)).

[0013] As shown in Figure 4(a), when copper with a thickness of 0.5 mm is processed with a blue laser (output 800 W) and a processing speed of 6.0 m / min, the penetration depth is not deep in the first welding section, so no traces of laser irradiation remain, but as the welding section progresses, the penetration depth becomes deeper and traces of laser irradiation begin to remain.On the other hand, as shown in Figure 4(b), when copper with a thickness of 3.0 mm is processed with a blue laser (output 400 W) and a red laser (output 4000 W) and a processing speed of 3.0 m / min, the higher power and slower processing speed compared to the processing conditions in Figure 4(a) make it more susceptible to heat effects, but the penetration depth in the first welding section differs from that in the second welding section, indicating that the penetration depth is not stable.

[0014] For these reasons, when laser welding metals such as aluminum and copper, which have high thermal conductivity and are easily affected by heat, there is a need for a technology that is non-destructive and reduces the effort required to determine complex processing conditions in order to ensure a stable, consistent penetration depth along the entire length of the weld.

[0015] Therefore, in the following first embodiment, an example of a laser welding device, a laser welding method, and a laser welding program that can stably obtain a constant welding depth over the entire length of the welding section will be described.

[0016] Hereinafter, with reference to the accompanying drawings, detailed embodiments of the laser welding apparatus, laser welding method, and laser welding program according to the present disclosure will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or redundant description of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

[0017] (Embodiment 1) 1. Laser welding equipment configuration First, the configuration of a laser welding apparatus 100 according to each embodiment will be described with reference to FIG. 1. In the following description, the terms "welding" and "processing" will be used interchangeably and will be referred to as "welding" and "processing." FIG. 1 is a diagram showing a schematic configuration example of a laser welding apparatus 10 according to each embodiment. The laser welding apparatus 10 includes a laser oscillator 11 that outputs laser light L, an optical interferometer 12 that outputs measurement light S, a laser irradiation head 20 that irradiates the laser light L and measurement light S toward a workpiece 30, a robot 18 to which the laser irradiation head 20 is attached and that moves the laser irradiation head 20, and a control device 16 that controls the laser oscillator 11, the optical interferometer 12, the laser irradiation head 20, and the robot 18 to perform laser welding. Hereinafter, the "workpiece" may also be simply referred to as a "work."

[0018] The laser oscillator 11 oscillates to generate and output laser light L based on commands from the control device 16 (for example, commands for an operating procedure defined in a processing program described below). The laser oscillator 11 and the laser irradiation head 20 are connected by an optical fiber 19. The laser light L is transmitted from the laser oscillator 11 to the laser irradiation head 20 via the optical fiber 19. The laser oscillator 11 may include two oscillators, a first oscillator 11a that oscillates blue laser light with a wavelength in the 440 nm band and a second oscillator 11b that oscillates near-infrared laser light with a wavelength in the 975 nm band, or may include only one of them. In the following description, except for the description of the use of two oscillators (i.e., the first oscillator 11a and the second oscillator 11b), the description will be given assuming the use of the first oscillator 11a, in which case the laser light L will be blue laser light.

[0019] The optical interferometer 12 has a measurement light oscillator 13 that oscillates to generate and output measurement light S having a different wavelength from the laser light L, and a measurement unit 14 that measures the penetration depth of the weld 35, which will be described later. The measurement light oscillator 13 outputs the measurement light S based on commands from the control device 16 (for example, commands for an operating procedure defined in a processing program, which will be described later). The optical interferometer 12 and the laser irradiation head 20 are connected by an optical fiber 19. The measurement light S is transmitted from the optical interferometer 12 to the laser irradiation head 20 via the optical fiber 19. After being reflected by the weld 35, the measurement light S is incident on the optical interferometer 12 again via the laser irradiation head 20.

[0020] The laser irradiation head 20 is attached to the tip of the arm of the robot 18, and based on commands from the control device 16 (for example, commands for an operating procedure defined in a processing program described below), irradiates the laser light L and the measurement light S so as to form an image at the welding point of the welded portion 35 of the workpiece 30. For example, the laser irradiation head 20 has a built-in beam splitter (see Patent Document 1), and the beam splitter can be used to superimpose the laser light L and the measurement light S concentrically and coaxially, and irradiate them onto the welding point of the welded portion 35 of the workpiece 30.

[0021] Based on instructions from the control device 16 (for example, instructions for the operating procedure specified in the processing program described below), the robot 18 moves the laser irradiation head 20 to a specified position and scans the laser light L and measurement light S, targeting the welded portion 35 of the welding object 30.

[0022] The control device 16 is connected to the laser oscillator 11, the optical interferometer 12, the robot 18, and the laser irradiation head 20, and is configured using at least one of a central processing unit (CPU) and a graphical processing unit (GPU). The control device 16 functionally includes a determination unit 17a, a control unit 17b, and a processing unit 17c. The determination unit 17a determines the penetration depth of the welded portion 35 based on multiple measurements taken by the measurement unit 14. The control unit 17b controls not only the movement speed of the laser irradiation head 20 (i.e., the processing speed described below) but also the start and stop of the output of the laser light L, the irradiation diameter, wavelength, output power, etc. of the laser light L. The processing unit 17c calculates the optimal movement speed of the laser irradiation head 20 for each welding section (hereinafter also referred to as the "processing speed") based on input from the teaching pendant TP1 (see FIG. 6 or FIG. 10) and a welding result estimation model previously generated for each welding section by machine learning or the like. An example of the relationship between the welding section, the welding result estimation model, and the processing speed will be described later with reference to FIG.

[0023] The object to be welded 30 is what is called a workpiece, and includes an upper metal plate 31 and a lower metal plate 32 stacked one on top of the other. Both the upper metal plate 31 and the lower metal plate 32 are made of a thermally conductive metal, such as a copper plate. Note that an example of a thermally conductive metal is not limited to a copper plate, and may be, for example, an aluminum plate. The laser welding device 10 welds (e.g., joins) the upper metal plate 31 and the lower metal plate 32 together by irradiating the upper surface of the upper metal plate 31 with laser light L.

[0024] Furthermore, the laser welding apparatus 10 according to the present embodiment can measure the penetration depth of the weld 35 of the work-piece 30 formed by the irradiation of the laser light L, simultaneously with the laser welding of the work-piece 30. The details of the measurement principle of this penetration depth and the details of the internal configuration of the laser irradiation head 20 are disclosed in Patent Document 1, and therefore will not be described in detail here. In measuring the penetration depth, in order to sufficiently separate the laser light L and the measurement light S, it is desirable that the wavelength difference between the laser light L and the measurement light S be 100 nm or more.

[0025] For example, when laser light L is irradiated onto a weld 35, the weld begins to melt from its top, forming a molten pool (not shown) in the weld 35. As the weld 35 melts, molten metal evaporates from the molten pool, and a keyhole (not shown) is formed by the pressure of the vapor generated during evaporation. Here, the molten pool and the keyhole are collectively referred to as the weld 35. A solidified portion (not shown) is formed behind the molten pool in the welding direction as the molten pool solidifies. At this time, the measurement light S emitted from the optical interferometer 12 is superimposed concentrically with the laser light L from the laser oscillator 11 by a beam splitter (not shown) built into the laser irradiation head 20, and is then irradiated into the inside of the keyhole. The irradiated measurement light S is reflected off the bottom of the keyhole (not shown) and enters the optical interferometer 12 via the beam splitter.

[0026] The optical path length of measurement light S incident on optical interferometer 12 is measured by measurement unit 14. Measurement unit 14 identifies the depth of the keyhole from the measured optical path length as the penetration depth (measured value) of welded portion 35. In this way, laser welding device 10 can determine the quality of welded portion 35 based on the measured penetration depth.

[0027] The teaching pendant TP1 is an example of a display device, and is connected to the control device 16 to display a processing condition screen WD1 (see FIG. 6) generated by the control device 16 and to receive inputs from the operator.

[0028] 2. Overview of the series of processes from dividing the welding section to generating the machining program Next, an overview of a series of processes from dividing the welding section to generating the processing program will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of an outline of the operation of the laser welding method according to embodiment 1. For example, when a copper material such as a copper plate is used as the welding object 30, the processing conditions are assumed to be an output power of the near-infrared laser light of 3.5 kW and a constant moving speed (processing speed) of 3.0 (m / min) for moving the laser irradiation head 20.

[0029] The top row, the first row, shows that the penetration depth of the workpiece 30 gradually increases as time elapses from the start of laser welding (see the horizontal axis), and although it reaches the desired penetration depth h0 along the way, it does not reach the desired penetration depth h0 immediately after the start of laser welding. In other words, if the processing speed remains constant at 3.0 (m / min), the penetration depth varies from one welding section to another (in other words, depending on the time elapsed from the start of laser welding).

[0030] Therefore, in the first embodiment, processing unit 17c of control device 16 of laser welding apparatus 10 performs a division process to divide the welding section based on a first correction coefficient α based on the number of divisions of the welding section for laser welding and the wavelength of the laser light, a second correction coefficient β based on the irradiation speed (processing speed) which is the movement speed of laser irradiation head 20, and the output power of the laser light. For example, as shown in the second row of Fig. 5, processing unit 17c divides the entire length of the welding section into four welding sections PR1, PR2, PR3, and PR4. Details of the first correction coefficient α, the second correction coefficient β, and the division method will be described later.

[0031] Processing unit 17c refers to a welding result estimation model generated in advance by machine learning or the like for each of the four welding sections PR1, PR2, PR3, and PR4 obtained by the division process, and performs a determination process to calculate and output an optimal machining speed (an example of a machining condition) for each welding section. That is, processing unit 17c calculates the machining speed for welding section PR1 using the welding result estimation model for welding section PR1. Similarly, processing unit 17c calculates the machining speed for welding section PR2 using the welding result estimation model for welding section PR2. Processing unit 17c calculates the machining speed for welding section PR3 using the welding result estimation model for welding section PR3. Processing unit 17c calculates the machining speed for welding section PR4 using the welding result estimation model for welding section PR4. Details of a method for learning the welding result estimation model for each welding section will be described later with reference to FIG. 7.

[0032] Using the results of the determination process, processing unit 17c changes the processing speed of welding section PR1 from 3.0 m / min to 2.5 m / min, the processing speed of welding section PR2 from 3.0 m / min to 3.1 m / min, the processing speed of welding section PR3 from 3.0 m / min to 3.2 m / min, and the processing speed of welding section PR4 from 3.0 m / min to 2.8 m / min. As a result, in welding section PR1, where the desired penetration depth h0 could not be obtained, the desired penetration depth h0 can be more easily obtained by slowing the processing speed. In welding sections PR2 and PR3, the desired penetration depth h0 can be stably secured by increasing the processing speed. In welding section PR4, where the penetration depth h0 tended to be larger than the desired penetration depth h0, the desired penetration depth h0 can be maintained by increasing the processing speed. In other words, the laser welding apparatus 10 according to the first embodiment performs a generation process to generate a processing program after variably changing (editing) the processing speed for each welding section, thereby making it possible to more stably obtain the desired penetration depth h0 during laser welding.

[0033] FIG. 6 shows an example of a processing condition screen WD1 displayed on the teaching pendant TP1. The processing condition screen WD1 may be generated by the control device 16 (e.g., processing unit 17c) when the welding speed (processing speed) for each welding section is calculated and displayed on the teaching pendant TP1. Alternatively, if the control device 16 has a built-in display device, the processing condition screen WD1 may be displayed on the display device. The processing condition screen WD1 includes a processing condition input field IPF1 and a processing condition output field OPF1. The processing condition input field IPF1 includes items such as the material of the workpiece 30 (e.g., pure copper), the type of joint (e.g., lap joint), the plate thickness (e.g., the thickness of two plates), the irradiation pattern of the laser light L (e.g., circle), and the circle diameter (e.g., 0.01 mm). The processing condition output field OPF1 includes items such as the welding speed (processing speed) and the weld length for each divided welding section (e.g., welding sections PR1 to PR4). When the control device 16 (e.g., the processing unit 17c) detects that the "OK button" has been pressed by an operator for the values ​​displayed in the machining condition input field IPF1 and the machining condition output field OPF1 of the machining condition screen WD1, the control device 16 generates a machining program that employs the various values ​​displayed on the machining condition screen WD1 as machining conditions. The control device 16 (e.g., the processing unit 17c) may also accept operator-operated editing (modification) of the values ​​displayed in the machining condition input field IPF1 and the machining condition output field OPF1 of the machining condition screen WD1. This allows the operator to individually modify the machining conditions by operating the machining condition screen WD1.

[0034] 3. Learning of welding result estimation model and welding section division rules Next, learning of the welding result estimation model and the rules for dividing the welding section will be described with reference to Figs. 7 to 9. Fig. 7 is a diagram showing an example of the learning operation procedure of the welding result estimation model in chronological order. Fig. 8 is a diagram showing an example of the relationship between the welding section and the laser beam preheating effect and the laser beam postheating effect. Fig. 9 is a diagram showing an example of the temperature dependency of the light absorptance of copper for near-infrared wavelengths.

[0035] <Learning of welding result estimation model> Prior to machine learning of the welding result estimation model, preliminary machining tests are conducted under a plurality of different machining conditions, and test data EXP1 showing the relationship between the target welding section, the machining conditions, and the machining results is prepared (step St1). The test data EXP1 includes the order of the preliminary machining tests, the type of the target welding section (e.g., welding sections PR1 to PR4), the machining conditions having a plurality of operating parameters, and the machining results (e.g., the average penetration depth of the target welding section), all of which are associated with each other. The machining conditions include, for example, the operating parameters of the workpiece material, workpiece thickness, irradiated laser beam focal diameter, irradiated laser wavelength, irradiated laser power, and machining speed.

[0036] Next, from the test data EXP1 prepared in step St1, each data is classified and extracted for each target welding section, and target welding section test data PR1DT1 extracted for each target welding section is generated (step St2). In the example of FIG. 7, there are four target welding sections, namely welding sections PR1 to PR4. Therefore, a total of four target welding section test data PR1DT1 are generated. FIG. 7 illustrates only the target welding section test data PR1DT1 for welding section PR1. Machine learning is performed using this target welding section test data PR1DT1 as default learning data, and a welding result estimation model, which is a machine learning model for welding section PR1, is generated (step St2).

[0037] Furthermore, the same process as step St2 is performed for the other welding sections PR2, PR3, PR4, etc., and a welding result estimation model, which is a machine learning model for the other welding sections PR2, PR3, PR4, etc., is generated (step St3). This makes it possible to calculate a processing speed that will achieve a consistent weld depth (penetration depth) throughout the entire welding section, even for metals with different thermal conductivities. Furthermore, the laser welding device 10 can calculate optimal processing conditions (e.g., processing speed) for each welding section, based on the wavelength of the laser light L used for laser welding and the type of workpiece (metal). In other words, this is expected to significantly reduce the time it takes for an operator to identify processing conditions, which previously required a considerable amount of trial and error effort.

[0038] <Rules for dividing welding sections> Processing unit 17c performs a division process to divide the total length of the welding section to be laser-welded on work-piece 30 into a plurality of (in other words, at least two) welding sections based on the number of divisions input by the operator via teaching pendant TP1. Here, the rules that processing unit 17c refers to when performing the division process will be described below with reference to FIG. 8.

[0039] [Split processing rules] Step 1: First, set the welding section PR1, which will be the welding start side. The welding length of this welding section PR1 is set to Xs. The unit of Xs is time (min). Order 2: Next, set the welding section PR4, which will be the welding end side. The welding length of this welding section PR4 is set to Xf. The unit of Xf is time (min). Step 3: Divide the remaining welding sections equally and assign numbers to the welding sections starting from the welding start point. In the example of Figure 8, welding sections PR1 and PR4 have already been set, so two welding sections PR2 and PR3 are set by dividing them equally. When the input division number is "2" and the total length of the welding section is divided into two sections, the section excluding the welding section PR1 at the time of the above-mentioned order 2 is set as the welding section PR2.

[0040] The advantages of adopting these rules are explained below. Simply put, the advantage is that it allows you to set sections according to the degree to which thermal effects (e.g., preheating, post-heating) affect the penetration depth.

[0041] In other words, as shown in the bottom table of Figure 8, welding sections PR2 and PR3 are consistently subjected to the same degree of preheating and postheating effects, so there is no fluctuation in the thermal effect and the penetration depth tends to be stable. This is based on the fact that the penetration depth in welding sections PR2 and PR3 in the top graph of Figure 8 is the same as or even exceeds the desired penetration depth h0. Note that the top graph of Figure 8 is the same as the top and second graphs of Figure 5.

[0042] In addition, the starting point of the weld is where laser welding begins, and it is difficult to obtain the preheating effect of irradiating the laser light L on the welded sections PR2 and PR3. In the case of a copper workpiece 30, the energy must be stored while the laser light L is being irradiated from room temperature to the melting point (1085°C), and as a result, the penetration depth of the workpiece 30 tends to be shallow (see the penetration depth of the welded section PR1 in Figure 8).

[0043] Furthermore, it becomes difficult to maintain the post-heating effect on the welding end side for welding sections PR2 and PR3, and in the case of copper welding object 30, the time required to maintain the temperature above the melting point (1085°C) becomes shorter, resulting in a shallow penetration depth (see the penetration depth of welding section PR4 in Figure 8).

[0044] As described above, the welding start point is in the process of changing the copper material from solid to liquid. However, the laser beam L energy is required to heat the copper welding object 30 from room temperature to its melting point by 1085°C or more. Furthermore, because copper has low light absorption in solid form (see FIG. 9), a large amount of laser beam L energy is required to reach the melting point, and it takes a long time to achieve a sufficient and stable penetration depth. For this reason, in the first embodiment, the processing unit 17c divides the entire welding section into multiple welding sections (e.g., welding sections PR1 to PR4 shown in FIG. 8) based on the above-mentioned rules. FIG. 9 shows that the light absorption rate when copper is irradiated with laser beams in the near-infrared wavelength range changes depending on the temperature, and that the light absorption rate jumps threefold at around 1250°C.

[0045] As a result, the laser welding device 10 can determine the length of time until the penetration depth stabilizes regardless of fluctuations in the factors by correcting the minimum factors (e.g., energy of the laser light L, difference in light absorption rate, processing speed) that affect the weld length at the welding start side (welding section PR1) and the welding end side (welding section PR4), where fluctuations in the penetration depth are large.

[0046] Next, the time length of the welding section set by the division process will be described.

[0047] [Time length of welding section determined during division process] It is known that the amount of copper melted correlates with how much energy the laser beam L has given to the copper (in other words, how much energy has been given to change it from a solid to a liquid). Utilizing this, the energy of the laser beam L irradiated onto the welding section PR1 is shown in equation (1). A shown in equation (1) is a variable that changes depending on the number of divisions input into the teaching pendant TP1 by the operator.

[0048] Laser power output [W] × laser irradiation time in welding section PR1 [sec] = A [W S] (1)

[0049] Next, because the light absorption rate (energy) varies depending on the wavelength of the laser light L, processing unit 17c multiplies A in equation (1) by a wavelength correction coefficient α (an example of a first correction coefficient) to correct for this variation. For example, the blue band has a higher light absorption rate (energy) than the near-infrared band, even if the "laser irradiation time [sec] in welding section PR1" in equation (1) is the same, resulting in deeper penetration. Therefore, processing unit 17c selects a wavelength correction coefficient α corresponding to the wavelength of the laser light L used for laser welding and multiplies A in equation (1) by this coefficient.

[0050] Furthermore, because the welding length (length of time) until the penetration depth stabilizes varies depending on the processing speed, processing unit 17c multiplies A in equation (1) by a speed correction coefficient β (an example of a second correction coefficient) to correct for this. For example, a faster processing speed increases the welding length until the penetration stabilizes. Therefore, processing unit 17c selects a speed correction coefficient β corresponding to the processing speed used in laser welding (assumed processing speed) and multiplies it by A in equation (1). This assumed processing speed is not the processing speed calculated by the welding result estimation model for each welding section in FIG. 5, but is a processing speed that is assumed in advance to be used in laser welding (for example, the "processing speed of 3.0 m / min" in the processing conditions at the top of FIG. 5).

[0051] From the above, during the division process, processing unit 17c calculates "A × α × β" by multiplying A in equation (1) for welding section PR1 by the wavelength correction coefficient α and the speed correction coefficient β, and calculates the time length (Xs) of welding section PR1 by dividing it by the value of "laser power output" in the processing conditions used for laser welding.

[0052] Similarly, processing unit 17c calculates not only the time length of welding section PR1 on the welding start side but also the time length of welding section PR4 on the welding termination side. In this case, processing unit 17c calculates the time length (Xs) of welding section PR1, and then calculates B for welding section PR4 as equation (2) corresponding to equation (1). B shown in equation (2) is a variable that similarly changes depending on the number of divisions input to teaching pendant TP1 by operator operation.

[0053] Laser power output [W] × laser irradiation time in welding section PR4 [sec] = B [W S] (2)

[0054] Processing unit 17c calculates "B × α × β" by multiplying wavelength correction coefficient α and speed correction coefficient β, and calculates the time length (Xf) of welding section PR4 by dividing the result by the value of "laser power output" in the processing conditions used for laser welding. Note that processing unit 17c can calculate the time lengths of welding sections PR2 and PR3 based on the time required to laser weld the entire length of the welding section at the assumed processing speed and the number of divisions and time length (Xs, Xf) input by the operator to teaching pendant TP1.

[0055] 4. Operational procedure of laser welding method and example of laser welding experiment results Next, an example of the operation procedure of the laser welding method using the laser welding apparatus 10 according to the first embodiment and an example of experimental results of the laser welding will be described with reference to Figs. 10 to 12. Fig. 10 is a flowchart showing an example of the operation procedure of the laser welding method according to the first embodiment in chronological order. Fig. 11 is a diagram showing an example of experimental results under first experimental conditions using the laser welding method according to the first embodiment. Fig. 12 is a diagram showing an example of experimental results under second experimental conditions using the laser welding method according to the first embodiment. The series of processes shown in Fig. 10 is mainly executed by the control device 16 of the laser welding apparatus 10.

[0056] In FIG. 10, the control device 16 receives input of various processing conditions input to the teaching pendant TP1 by an operator (step St11). The various processing conditions include, but are not limited to, the material of the workpiece, the joint type, the plate thickness, the pattern, the irradiation diameter, the irradiation laser wavelength, the irradiation laser power (see FIG. 6), and the desired penetration depth. The control device 16 receives input of the number of divisions for dividing the entire length of the welding section into two or more welding sections input to the teaching pendant TP1 by an operator (step St12). The processing unit 17c divides the entire length of the welding section into multiple welding sections based on the various processing conditions input in step St11 and the number of divisions input in step St12, and calculates the time lengths (Xs, Xf, etc.) of the welding sections according to the number of divisions for each divided section (step St13). Steps St12 and St13 correspond to the division process performed by the processing unit 17c.

[0057] The processing unit 17c reads out from a memory (not shown in FIG. 1) and refers to the welding result estimation model corresponding to each welding section divided in step St13, and infers (calculates) the optimal machining speed for the corresponding welding section using the welding result estimation model corresponding to the welding section (step St14). The processing unit 17c generates a machining condition screen WD1 (see FIG. 6) including the results calculated in step St14, and outputs it to a display device (e.g., the teaching pendant TP1) for display (step St15). If the processing unit 17c detects that the machining condition screen WD1 displayed on the teaching pendant TP1 has not been approved (e.g., by pressing the OK button) by the operator (step St16, NO), the processing unit 17c corrects the time length or machining speed of the corresponding welding section by directly inputting a correction by the operator (step St17). After this, the processing by the processing unit 17c returns to step St14.

[0058] On the other hand, when the processing unit 17c detects that the processing condition screen WD1 displayed on the teaching pendant TP1 has been approved by the operator (e.g., by pressing the OK button) (step St16, YES), the processing unit 17c generates a processing program that reflects the inferred results of the optimal processing speed for each welding section (step St18). The control device 16 (e.g., the control unit 17b) starts laser welding of the work-piece 30 based on the processing program generated in step St18 (step St19). The control device 16 (e.g., the determination unit 17a) monitors the penetration depth of the work-piece 30 as the laser welding started in step St19 and displays the monitoring results on a display device (e.g., the teaching pendant TP1) (step St20).

[0059] The experimental results shown in Figure 11 were based on the following assumptions: the workpiece (the object to be welded) was pure copper, the plate thickness was 3.0 mm, the beam focal diameter of the irradiated blue laser light was 200 μm, the wavelength of the irradiated blue laser light was 445 nm, the wavelength of the irradiated near-infrared laser light was 975 nm, the laser power of the irradiated blue laser light was 400 W, and the laser power of the irradiated near-infrared laser light was 4000 W. The results also show the results of measuring the bead width and penetration depth as the processing speed increased in increments of 3.0 m / min from 3.0 m / min to 24.0 m / min. The experimental results indicated that the slower the processing speed, the deeper the penetration depth.

[0060] The experimental results shown in Figure 12 were based on the following assumptions: the workpiece (to be welded) was pure copper, the plate thickness was 1.0 mm, the beam focal diameter of the irradiated blue laser was 400 μm, the beam focal diameter of the irradiated near-infrared laser was 200 μm, the wavelength of the irradiated blue laser was 445 nm, the wavelength of the irradiated near-infrared laser was 975 nm, the laser power of the irradiated blue laser was 200 W to 800 W, and the laser power of the irradiated near-infrared laser was 1000 W to 1500 W. The graph also shows the measurement results of bead width and penetration depth at a constant processing speed of 3.0 m / min. These experimental results indicated that the penetration depth increased with increasing irradiated laser power and also varied depending on the wavelength of the laser light.

[0061] As described with reference to Fig. 7, prior to machine learning of the welding result estimation model, a preliminary machining test is conducted under a plurality of different machining conditions to prepare test data EXP1 that indicates the relationship between the target welding section, the machining conditions, and the machining result. This test data EXP1 is not limited to that shown in Fig. 7 and may be, for example, the test data shown in Fig. 13 or 14, and machine learning may be performed using these as learning data. Fig. 13 is a diagram showing a first modified example of the test data. Fig. 14 is a diagram showing a second modified example of the test data.

[0062] The test data shown in Figure 13 includes additional processing conditions and results compared to the test data shown in Figure 7. Specifically, the processing conditions include wobbling processing conditions, laser hybrid processing conditions, pulse processing conditions, and other conditions. The wobbling processing conditions include the wobbling pattern, wobbling frequency, and wobbling amplitude. The laser hybrid processing conditions include the secondary irradiation laser beam focal diameter, secondary irradiation laser wavelength, and secondary irradiation laser power. The pulse processing conditions include the pulse frequency, pulse duty, and pulse peak laser power. Other conditions include the workpiece size (width x length), welding length, welding angle, assist gas type, and assist gas usage. The processing results also include the average bead width of the target section, the arithmetic mean roughness Ra of the target section, the maximum height roughness Rz of the target section, the number of spatters generated in the target section, and the joint strength. A "- (hyphen)" in Figure 13 indicates that the item is not included (i.e., not used). For example, if no wobbling processing is performed, a "-" is listed in the item for the conditions for wobbling processing.

[0063] In Figure 13, the "Conditions for Wobbling Processing" section lists three conditions for processing while moving the laser light (laser beam) with the laser irradiation head 20. The "Wobbling Pattern" section specifies the trajectory of the laser light (laser beam). For example, the most basic trajectory is a circle, which processes while drawing a circle. The "Conditions for Hybrid Laser Processing" section specifies the conditions for hybrid processing using both blue and near-infrared laser light. The "Conditions for Pulse Processing" section specifies the ratio of ON time to one cycle of the laser light. For example, a pulse duty of 50% means that the ON time during which the laser light is irradiated is the same as the OFF time during which the laser light is not irradiated. A pulse duty of 90% means that the ON time during which the laser light is irradiated is 90% of the time, and the remaining 10% is the OFF time during which the laser light is not irradiated.

[0064] The test data shown in Figure 14 has the same items as the test data shown in Figure 13. Compared to Pre-Processing Test 1, Pre-Processing Test 5 adds data on the processing conditions when wobbling processing was performed. Compared to Pre-Processing Test 2, Pre-Processing Test 6 adds data on the processing conditions when laser hybrid processing was performed. Pre-Processing Test 7 contains data on pulse processing. Pre-Processing Test 8 contains data on lap welding. In Pre-Processing Test 8, processing is performed to join two pieces of metal, so a numerical value is included in the joint strength item in the processing results.

[0065] (Background to the second embodiment) Conventionally, when butt welding multiple plates, end tabs are placed on both ends of the plates to ensure a consistent penetration depth throughout the entire length of the weld, and the end tabs are included in the laser welding. This is because welding defects are likely to occur at the start and end of the weld, and by using the end tabs to prevent these defects from occurring, the quality of the weld on the base material (workpiece) is ensured. However, this conventional method requires the installation of end tabs for each butt welding, which is not only time-consuming but also unavoidable due to the lack of reusability, resulting in increased costs due to the need to install end tabs each time.

[0066] Therefore, in the following second embodiment, an example of a butt welding method that can stably obtain a constant welding depth over the entire length of the welding section without preparing end tabs will be described.

[0067] (Embodiment 2) In the second embodiment, laser welding (here, butt welding) of workpieces will be described in accordance with the processing program generated in the first embodiment. Specifically, in the flowchart shown in FIG. 10, laser welding is started in accordance with the processing program in step St19, and then butt welding of three plates and four plates, which will be described later, is performed. In the following description, a case will be described in which the workpieces 30 are plates made of copper, a thermally conductive metal (hereinafter referred to as "copper plates"). Note that the laser welding apparatus according to the second embodiment has the same configuration as the laser welding apparatus 10 according to the first embodiment, and therefore, a description of the same parts will be omitted, and only the differences will be described.

[0068] <Three-plate butt welding> First, a method of butt-welding three plates (i.e., three copper plates) will be described with reference to Fig. 15 and Fig. 16. Fig. 15 is a diagram schematically showing butt-welding of three plates according to embodiment 2. Fig. 16 is a diagram showing an example of welding locations when butt-welding the three plates of Fig. 15. Fig. 15 shows an oblique view of the arrangement of three copper plates PLT1, PLT2, and PLT3, while Fig. 16 shows a side view of the arrangement of the three copper plates PLT1, PLT2, and PLT3. Copper plate PLT1 is an example of a first plate, copper plate PLT2 is an example of a second plate, and copper plate PLT3 is an example of a third plate.

[0069] The copper plates PLT1 and PLT2 are stacked vertically. The copper plate PLT3 is positioned adjacent to both sides (for example, on the left side) of the copper plates PLT1 and PLT2. The copper plates PLT1 to PLT3 are positioned so that the processing surfaces PSL1 of the copper plates PLT1 and PLT2, where the laser light L is irradiated, and the end surface ESF1 of the copper plate PLT3 are aligned on the same plane (i.e., flush). The thickness of the copper plate PLT3 in the direction parallel to the irradiation direction of the laser light (processing direction) is t1. As shown in FIG. 16, the laser welding device 10 irradiates the laser light L successively to the end surface ESF1 of the copper plate PLT3, and the weld line WDL1 of the copper plates PLT1 and PLT2, in that order. In particular, when irradiating this laser light L, the thickness (plate thickness) of the copper plate PLT3 along the irradiation direction (processing direction) of the laser light L is t1, and the irradiation distance t at which the laser light L is irradiated on the end face ESF1 of the copper plate PLT3 is t1 or less.

[0070] As a result, the optimal processing speed is determined for each welding section as described in the first embodiment, and then butt welding is performed by the laser welding device 10, so it is possible to stably obtain a constant penetration depth over the entire length of the welding section of the copper plates PLT1 to PLT3 (i.e., the entire distance irradiated with the laser light L). Furthermore, it is possible to obtain sufficient joint strength for the copper plates PLT1 to PLT3, which are the objects to be welded.

[0071] <Four-plate butt welding> Next, a method of butt-welding four plates (i.e., four copper plates) will be described with reference to Fig. 17 and Fig. 18. Fig. 17 is a diagram schematically showing butt-welding of four plates according to embodiment 2. Fig. 18 is a diagram showing an example of welding locations when butt-welding the four plates of Fig. 16. Fig. 17 shows a perspective view of the arrangement of four copper plates PLT11, PLT12, PLT13, and PLT14, while Fig. 18 shows a plan view (top view) of the arrangement of the four copper plates PLT11, PLT12, PLT13, and PLT14. Copper plate PLT11 is an example of a first plate, copper plate PLT12 is an example of a second plate, copper plate PLT13 is an example of a third plate, and copper plate PLT14 is an example of a fourth plate.

[0072] The copper plate PLT11 serves as a base plate for butt welding. That is, copper plates PLT12, PLT13, and PLT14 are stacked on top of the copper plate PLT11, and copper plate PLT12 is in contact with both copper plates PLT13 and PLT14. The copper plates PLT11 to PLT14 are arranged so that the processing surface PSL11, where the laser light L is irradiated on the copper plates PLT11 and PLT12, and the end surface ESF11 of the copper plate PLT13 and the end surface ESF12 of the copper plate PLT14 are aligned on the same plane (i.e., flush). The thickness of the copper plate PLT13 in the direction parallel to the irradiation direction of the laser light (processing direction) is t1. The thickness of the copper plate PLT14 in the direction parallel to the irradiation direction of the laser light (processing direction) is t2. 17, the laser welding apparatus 10 irradiates the laser beam L successively in this order onto an end face ESF11 of the copper plate PLT13, a weld line WDL11 between the copper plates PLT11 and PLT12, and an end face ESF12 of the copper plate PLT14. In particular, in this irradiation of the laser beam L, the thickness (plate thickness) of the copper plate PLT13 along the irradiation direction (processing direction) of the laser beam L is t1, and the thickness (plate thickness) of the copper plate PLT14 is t2, and the irradiation distance L1 over which the laser beam L is irradiated onto the end face ESF11 of the copper plate PLT13 is t1 or less, and the irradiation distance L2 over which the laser beam L is irradiated onto the end face ESF12 of the copper plate PLT14 is t2 or less. In other words, the effective welding length w1 of the butt welding of the copper plates PLT11 to PLT14 based on the irradiation of the laser beam L is longer than the length w2 of the copper plate PLT12 in the direction parallel to the irradiation direction (processing direction) of the laser beam L (w1>w2).

[0073] As a result, the optimal processing speed is determined for each welding section as described in the first embodiment, and then butt welding is performed by the laser welding device 10, so that a constant penetration depth d1 can be stably obtained over the entire length of the welding section of the copper plates PLT11 to PLT14 (i.e., the entire distance irradiated with the laser light L). Furthermore, the copper plates PLT11 to PLT14, which are the objects to be welded, can have sufficient joint strength.

[0074] <About the technology of the present disclosure> As described above, the present disclosure discloses the following technical ideas.

[0075] (Item A1) an oscillator (laser oscillator 11) that emits a laser beam having a wavelength used for laser welding of a welding object (30) that is a thermally conductive metal; an irradiation unit (laser irradiation head 20) that irradiates the laser light from the oscillator onto the welding object; a control device (16) that performs at least a division process (see the second row of FIG. 5) of dividing the welding sections (PR1 to PR4) of the laser welding on the welding object into at least two sections, a determination process (see the third row of FIG. 5) of determining processing conditions for the laser welding for each of the two or more welding sections obtained by the division process, and a generation process (see the fourth row of FIG. 5) of generating a processing program based on the processing conditions for each of the two or more welding sections obtained by the determination process, the control device controls irradiation of the laser light onto the work-pieces based on the processing program. Laser welding equipment. As a result, when using a laser welding device to laser weld a welding object that is a thermally conductive metal, the entire length of the welding section can be divided into multiple welding sections and appropriate processing conditions can be set for each welding section, making it possible to stably obtain a constant welding depth over the entire length of the welding section.

[0076] (Item A2) the control device includes a processing unit (17c) having a welding result estimation model trained using predetermined training data for each of the welding sections, the processing unit determines, for each of the corresponding welding sections, processing conditions for the laser welding based on the welding result estimation model corresponding to the welding section. 3. The laser welding device according to item A1. As a result, the laser welding device can appropriately calculate processing conditions according to the role of the welding section using a welding result estimation model learned using learning data for each welding section, thereby obtaining processing conditions that match the positioning of each welding section.

[0077] (Item A3) The processing conditions of the laser welding include an irradiation speed, which is the moving speed of the irradiation part, 3. The laser welding device according to claim A1 or A2. As a result, the laser welding device can appropriately calculate the processing speed, which is an important processing condition for stably obtaining a constant penetration depth, for each welding section.

[0078] (Item A4) The welding result estimation model is generated by machine learning using, for each welding section, the material and plate thickness of the workpiece to be welded, the focal diameter, wavelength, and output power of the laser light, and the desired penetration depth in the welding section as the predetermined learning data, and outputs an irradiation speed which is the moving speed of the irradiation part. The laser welding device according to any one of items A1 to A3. As a result, the laser welding device can easily and highly accurately obtain the processing speed (movement speed of the laser irradiation head 20) by using a welding result estimation model for each welding section that has been generated in advance by machine learning.

[0079] (Item A5) the control device determines division lengths (Xs, Xf) of each of the welded sections after the division process based on the number of divisions of the welded section of the laser welding, a first correction coefficient based on the wavelength of the laser light, a second correction coefficient based on the irradiation speed which is the moving speed of the irradiation unit, and the output power of the laser light. The laser welding device according to any one of items A1 to A4. As a result, the laser welding device can calculate the division length (time length) of the welding section after an appropriate division process, taking into account corrections to mitigate the effect of fluctuations in light absorption rate depending on the wavelength of the laser light used, as well as corrections to mitigate the effect on the penetration depth of the processing speed, which is the movement speed of the irradiation part (laser irradiation head 20).

[0080] (Item A6) the control device displays, on a display device (teaching pendant TP1), a processing condition screen (WD1) in which the processing conditions for each of the two or more welding sections obtained by the determination process are associated with an irradiation speed, which is the moving speed of the irradiation unit, and starts the generation process based on an operation on the processing condition screen. The laser welding device according to any one of items A1 to A5. As a result, the laser welding device allows the operator to visually and easily understand a list of the division lengths (time lengths) calculated for each welding section and the processing speeds for the welding sections.

[0081] (Item A7) A laser welding method performed by a laser welding apparatus, comprising: a step of oscillating a laser beam having a wavelength used for laser welding of a welding object that is a thermally conductive metal by an oscillator; a process of performing at least a division process of dividing a welding section of the laser welding on the welding object into at least two sections, a determination process of determining processing conditions for the laser welding for each of the two or more welding sections obtained by the division process, and a generation process of generating a processing program based on the processing conditions for each of the two or more welding sections obtained by the determination process; and controlling irradiation of the laser light onto the workpiece based on the processing program. Laser welding method. As a result, according to the laser welding method, when laser welding a welding object that is a thermally conductive metal, the entire length of the welding section can be divided into multiple welding sections and appropriate processing conditions can be set for each welding section, so that a constant welding depth can be stably obtained over the entire length of the welding section.

[0082] (Item A8) The method is executed by a control device connected to an oscillator that oscillates a laser beam having a wavelength used for laser welding of a welding object that is a metal having thermal conductivity, an irradiation unit that irradiates the laser beam from the oscillator onto the welding object, and a dividing process of dividing a welding section of the laser welding on the welding object into at least two sections; a determination process for determining the laser welding processing conditions for each of the two or more welding sections obtained by the division process; a generation process for generating a machining program based on the machining conditions for each of the two or more welding sections obtained by the determination process, A method for generating a machining program. As a result, according to the processing program generation method, when laser welding a welding object that is a thermally conductive metal, the entire length of the welding section can be divided into multiple welding sections and appropriate processing conditions can be set for each welding section, so that a consistent welding depth can be stably obtained over the entire length of the welding section.

[0083] (Item B1) A butt welding method for joining at least two plates using a laser welding device (10) in which a penetration depth is set so as to satisfy the penetration depth, a step of butting a first plate (copper plate PLT1) and a second plate (copper plate PLT2); a step of adjoining the third plate to at least one of the first plate and the second plate so that a processing surface (PSL1) having a weld line (WDL1) between the first plate and the second plate and an end surface (ESF1) of the third plate are aligned in the same plane; and irradiating the end surface of the third plate and the weld line with laser light from the laser welding device in this order. When the thickness of the third plate along the irradiation direction of the laser light is t1, the irradiation distance of the laser light irradiated on the end surface of the third plate is t1 or less. Butt welding method. As a result, according to the butt welding method, when butt welding three copper plates together, a constant weld depth can be stably obtained along the entire length of the welded section without the need to prepare and place end tabs on both ends of the entire length of the welded section.

[0084] (Item B2) before the irradiation of the laser light, the fourth plate is adjacent to at least one of the first plate and the second plate so that the lamination surface and an end surface of the fourth plate are aligned in the same plane, the laser light is irradiated successively to the end face of the third plate, the weld line, and the end face of the fourth plate in this order; When a thickness of the fourth plate along the irradiation direction of the laser light is t2, an irradiation distance at which the laser light is irradiated on the end surface of the fourth plate is t2 or less. The butt welding method described in item B1. As a result, according to the butt welding method, when butt welding four copper plates together, a constant weld depth can be stably obtained along the entire length of the welded section without the need to prepare and place end tabs on both ends of the entire length of the welded section.

[0085] (Item B3) The first plate, the second plate, and the third plate are made of an aluminum-based material or a copper-based material. The butt welding method according to item B1 or B2. As a result, with this butt welding method, even when butt welding multiple plates made of copper or aluminum, which are metals with high thermal conductivity, it is possible to stably obtain a constant weld depth over the entire length of the welded section without preparing and placing end tabs at both ends of the entire length of the welded section.

[0086] (Item B4) The wavelength range of the laser light has a wavelength in the wavelength range of at least 420 to 460 (nm). The butt welding method according to any one of items B1 to B3. As a result, according to the butt welding method, even when butt welding multiple copper-based plates, it is possible to perform high-quality butt welding by taking advantage of the high light absorption rate of copper, which is achieved by using a laser beam with a wavelength in the so-called blue wavelength range (420 to 460 (nm)), compared to when using laser beams with a wavelength in the near-infrared range.

[0087] (Item 5) The penetration depth is 50 (μm) or more. The butt welding method according to any one of items B1 to B4. As a result, according to the butt welding method, when performing butt welding using multiple plates, it becomes possible to easily measure penetration depths of 50 μm or more, improving the work efficiency of monitoring penetration depth.

[0088] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present disclosure is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications, alterations, substitutions, additions, deletions, and equivalents within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure. Furthermore, the components of the various embodiments described above may be combined in any manner without departing from the spirit of the invention. [Industrial Applicability]

[0089] The present disclosure is useful as a laser welding device, a laser welding method, and a laser welding program that can stably obtain a constant welding depth over the entire length of a welding section. [Explanation of symbols]

[0090] 10 Laser welding equipment 11 Laser oscillator 12 Optical Interferometer 13 Measurement light oscillator 14 Measuring part 16 Control device 17a Judgment part 17b Control section 17c Processing section 18. Robot 19 Optical Fiber 20 Laser irradiation head 30 Welding object 31 Upper metal plate 32 Lower metal plate 35 Welded section TP1 Teaching Pendant

Claims

1. an oscillator that emits laser light of a wavelength used for laser welding of a welding object that is a thermally conductive metal; an irradiation unit that irradiates the workpiece with the laser light from the oscillator; a control device that performs at least a division process of dividing a welding section of the laser welding on the welding object into at least two sections, a determination process of determining processing conditions for the laser welding for each of the two or more welding sections obtained by the division process, and a generation process of generating a processing program based on the processing conditions for each of the two or more welding sections obtained by the determination process; the control device controls irradiation of the laser light onto the work-pieces based on the processing program. Laser welding equipment.

2. the control device includes a processing unit having a welding result estimation model trained using predetermined training data for each of the welding sections, the processing unit determines, for each of the corresponding welding sections, processing conditions for the laser welding based on the welding result estimation model corresponding to the welding section.

2. The laser welding apparatus according to claim 1.

3. The processing conditions of the laser welding include an irradiation speed, which is the moving speed of the irradiation part, 3. The laser welding apparatus according to claim 2.

4. The welding result estimation model is generated by machine learning using, for each welding section, the material and plate thickness of the workpiece to be welded, the focal diameter, wavelength, and output power of the laser light, and the desired penetration depth in the welding section as the predetermined learning data, and outputs an irradiation speed which is the moving speed of the irradiation part.

3. The laser welding apparatus according to claim 2.

5. the control device determines a division length of each welding section after the division process based on the number of divisions of the welding section of the laser welding, a first correction coefficient based on the wavelength of the laser light, a second correction coefficient based on an irradiation speed which is the moving speed of the irradiation unit, and the output power of the laser light.

2. The laser welding apparatus according to claim 1.

6. the control device displays, on a display device, a processing condition screen in which the processing conditions for each of the two or more welding sections obtained by the determination process are associated with an irradiation speed, which is the moving speed of the irradiation unit, and starts the generation process based on an operation on the processing condition screen.

2. The laser welding apparatus according to claim 1.

7. A laser welding method performed by a laser welding apparatus, comprising: a step of oscillating a laser beam having a wavelength used for laser welding of a welding object that is a thermally conductive metal by an oscillator; a process of performing at least a division process of dividing a welding section of the laser welding on the welding object into at least two sections, a determination process of determining processing conditions for the laser welding for each of the two or more welding sections obtained by the division process, and a generation process of generating a processing program based on the processing conditions for each of the two or more welding sections obtained by the determination process; and controlling irradiation of the laser light onto the workpiece based on the processing program. Laser welding method.

8. The method is executed by a control device connected to an oscillator that oscillates a laser beam having a wavelength used for laser welding of a welding object that is a metal having thermal conductivity, an irradiation unit that irradiates the laser beam from the oscillator onto the welding object, and a dividing process of dividing a welding section of the laser welding on the welding object into at least two sections; a determination process for determining the laser welding processing conditions for each of the two or more welding sections obtained by the division process; a generation process for generating a machining program based on the machining conditions for each of the two or more welding sections obtained by the determination process, A method for generating a machining program.

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