Process monitoring unit and method for acquiring laser welding information

Abstract

To acquire information capable of determining the quality of a welded portion, even when a welding state of laser welding transmits.SOLUTION: A process monitor unit comprises: a conversion unit that receives light generated during laser beam irradiation for laser welding, and converts it into an electrical signal; a first amplification unit that amplifies the electrical signal by a first gain; a second amplification unit that amplifies the electrical signal by a second gain larger than the first gain; and an acquisition section that acquires and outputs either the first electrical signal amplified by the first amplification unit or the second electrical signal amplified by the second amplification unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a process monitor unit and a method for obtaining laser welding information. [Background technology]

[0002] For example, Patent Document 1 discloses a laser welder that performs welding by irradiating a workpiece with a laser torch with a laser beam. The laser welder has a condenser lens disposed in the housing of the laser torch for condensing the welding beam emitted from the welding point so as to be coaxial with the optical axis of the laser beam irradiated to the workpiece, receives the beam condensed by the condenser lens with a plurality of light receiving means arranged adjacent to each other, and detects defects in the welding point based on the intensities of the beams received by the plurality of light receiving means.

[0003] Patent Document 2 discloses a laser welding monitoring device that judges whether or not laser welding of materials to be welded is performed normally. The laser welding monitoring device receives radiated light, which is generated at the irradiation position of the laser beam when the laser beam emitted by a processing head provided in a laser welding machine is irradiated on the materials to be welded, and includes reflected light of the laser beam and monitoring light due to thermal radiation, which is light different from the reflected light, and separates the reflected light and monitoring light included in the radiated light by a spectroscopic unit, converts the dispersed monitoring light into a first electric signal, converts the dispersed reflected light into a second electronic signal by a trigger unit, outputs a trigger signal when the level of the second electric signal is equal to or higher than a predetermined threshold, and starts judging whether or not laser welding of the materials to be welded is performed normally based on the first electric signal when the trigger signal is input by the laser welding monitor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-42769 A [Patent Document 2] JP 2021-137867 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure has been devised in consideration of the above-described conventional circumstances, and aims to provide a process monitor unit and a method for acquiring laser welding information that acquires information that enables determination of the quality of a welded point even when the welding state of laser welding transitions. [Means for solving the problem]

[0006] The present disclosure provides a process monitor unit including a conversion unit that receives light generated during laser beam irradiation for laser welding and converts it into an electrical signal, a first amplification unit that amplifies the electrical signal by a first gain, a second amplification unit that amplifies the electrical signal by a second gain greater than the first gain, and an acquisition unit that acquires and outputs either the first electrical signal amplified by the first amplification unit or the second electrical signal amplified by the second amplification unit.

[0007] The present disclosure also provides a method for acquiring laser welding information performed by a computer, which receives light generated during laser beam irradiation for laser welding, converts it into an electrical signal, amplifies the electrical signal by a first gain and a second gain greater than the first gain, and acquires one of the first electrical signal amplified by the first gain and the second electrical signal amplified by the second gain. Effect of the Invention

[0008] According to the present disclosure, even when the welding state of laser welding is transitioning, information that allows determination of the quality of the welded portion can be obtained. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing an example of the overall configuration of a laser processing head system according to an embodiment; [Diagram 2]FIG. 13 is a diagram showing an example of a voltage signal waveform obtained by a first amplifier circuit when transitioning from heat conduction welding to keyhole welding. [Diagram 3] FIG. 13 is a diagram showing an example of a voltage signal waveform obtained by the second amplifier circuit when transitioning from heat conduction welding to keyhole welding. [Figure 4] FIG. 13 is a diagram showing an example of a voltage signal waveform obtained by a first amplifier circuit when transitioning from keyhole welding to heat conduction welding. [Diagram 5] FIG. 13 is a diagram showing an example of a voltage signal waveform obtained by the second amplifier circuit when transitioning from keyhole welding to heat conduction welding. [Figure 6] 1 is a flowchart showing an example of an operation procedure of a process monitor unit according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Background to this disclosure) Conventionally, there is a technique for detecting defects in a welded portion based on welding light emitted from a portion irradiated with a laser beam (i.e., a welded portion). Here, a laser welder can perform laser welding in different states, such as heat conduction welding or keyhole welding, depending on the welded portion or the power density of the laser. However, the state of the laser welding may change during welding due to factors such as deformation of the workpiece and deviation of the laser focal position. In such a case, the intensity of the welding light emitted from the welded portion changes significantly during welding. Therefore, if the current gain setting when converting the welding light into an electrical signal is not a gain setting corresponding to the state of laser welding, the electrical signal based on the welding light may saturate or the intensity of the electrical signal may become insufficient, making it difficult to obtain a correct electrical signal, which may make it difficult to detect defects in the welded portion.

[0011] One possible solution is to change the gain of the electrical signal in accordance with the state of laser welding. However, when changing the gain, the laser welding machine has a problem in that the man-hours required for changing the gain are added to the series of processes, increasing the man-hours in the process.

[0012] Alternatively, a method of using a plurality of laser welders or laser welding monitoring devices each adjusted to a gain corresponding to each laser welding state can be considered. However, in such a case, a laser welder or laser welding monitoring device must be prepared corresponding to each laser welding state, which increases the equipment cost.

[0013] Therefore, in the following embodiment, an example of a process monitor unit and a method of acquiring laser welding information that acquires information that enables determination of the quality of a welded portion even when the welding state of laser welding transitions will be described.

[0014] Hereinafter, with reference to the drawings as appropriate, an embodiment specifically disclosing a process monitor unit and a method for acquiring laser welding information according to the present disclosure will be described in detail. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following explanation and to facilitate understanding by those skilled in the art. Note that the attached drawings and the following explanation are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0015] <Terminology> In the following description, the term "laser welding" is intended to have the broadest possible meaning, unless expressly stated otherwise, and includes welding, soldering, melting, joining, annealing, softening, tackifying, resurfacing, peening, heat treating, fusing, sealing, and stacking.

[0016] A laser processing head system 100 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing an example of the overall configuration of the laser processing head system 100 according to the embodiment. It should be noted that the laser processing head system 100 shown in Fig. 1 is merely an example and is not limited thereto.

[0017] The laser processing head system 100 includes a head control unit S1, an oscillator S2, a laser head S3, a process monitor unit PM, and a monitor MN. The monitor MN may be configured integrally with a terminal device P3.

[0018] The laser processing head system 100 performs laser welding by driving the oscillator S2 based on a control command from the head control unit S1 and irradiating a laser beam from the laser head S3 toward a welding point of the workpiece. The laser processing head system 100 outputs the reflected light of the laser beam irradiated to the welding point, the plasma light generated at the welding point, and the thermal radiation light generated from the welding point to the spectroscopic unit P1 via optical fibers.

[0019] The laser processing head system 100 amplifies the electrical signal input by the spectroscopic unit P1 and outputs the amplified electrical signal to the terminal device P3 via the relay board P2. The laser processing head system 100 records the amplified electrical signal by the terminal device P3, and judges whether or not a welding defect has occurred (i.e., judges whether the laser welding is good or bad) based on a comparison between the amplified electrical signal and an electrical signal obtained when the welding quality is good.

[0020] The head control unit S1 is connected to each of the relay board P2, the oscillator S2, and the laser head S3 so as to be able to carry out data communications therebetween.

[0021] The head control unit S1 generates control commands for controlling the laser head S3 and transmits them to the laser head S3, and supplies power to the laser head S3. The head control unit S1 acquires information related to the sensors (not shown) and control of the laser head S3 transmitted from the laser head S3 (for example, information acquired by various sensors provided in the laser head S3, various control completion notifications, etc.). The head control unit S1 also acquires the control results of the oscillator S2 transmitted from the oscillator S2.

[0022] The oscillator S2 is connected to the head control unit S1 and the relay board P2 so as to be able to communicate data with each other. The oscillator S2 is also connected to the laser head S3 using an optical fiber. The oscillator S2 acquires information on the power command value (output value) of the laser light irradiated by the oscillator S2, which is transmitted from the head control unit S1 via the relay board P2. The oscillator S2 outputs the laser light based on the acquired information on the power command value. The output laser light is output to the laser head S3 via the optical fiber.

[0023] Here, the laser light emitted by the oscillator S2 may be a so-called blue laser light having a wavelength of blue (i.e., 400 nm to 500 nm), or may be a laser light of another wavelength. In particular, blue laser light has a characteristic that it is absorbed by copper at a high absorption rate (up to about 65%), and is therefore effective when laser welding laminated metal foils.

[0024] Additionally, the term "copper" as used herein, unless expressly stated otherwise, is intended to have the broadest possible meaning and includes copper, copper materials, copper metal, materials electroplated with copper, metallic materials containing at least about 10% to 100% copper by weight, metals and alloys containing at least about 10% to 100% copper by weight, metals and alloys containing at least about 20% to 100% copper by weight, metals and alloys containing at least about 50% to 100% copper by weight, metals and alloys containing at least about 70% to 100% copper by weight, and metals and alloys containing at least about 90% to 100% copper by weight.

[0025] The laser head S3 is connected to the head control unit S1 so as to be able to communicate data with it, and is connected to the oscillator S2 and the spectroscopic unit P1 so as to be able to transmit and receive optical signals via optical fibers. The laser head S3 irradiates the laser light output from the oscillator S2 to the welding point of the workpiece based on a control command sent from the head control unit S1, thereby performing laser welding. The laser head S3 also focuses the reflected light of the laser light, the plasma light, and the thermal radiation light, and sends them to the spectroscopic unit P1 via the optical fibers.

[0026] The process monitor unit PM is connected to the head control unit S1, the oscillator S2, the laser head S3, and the monitor MN so as to be able to transmit and receive data or optical signals between them. The process monitor unit PM executes a pass / fail judgment of the laser welding based on signals (voltage signals to be described later) corresponding to the light intensities of the reflected light of the laser light, the plasma light, and the thermal radiation light focused by the laser head S3. The process monitor unit PM includes a spectroscopic unit P1, a relay board P2, and a terminal device P3.

[0027] The spectroscopic unit P1 is connected to the laser head S3 so as to be able to exchange various kinds of light with the laser head S3, and to the relay board P2 so as to be able to exchange signals with the relay board P2. The spectroscopic unit P1 is configured, for example, by one or more integrated circuits including sensors 10A-10C, an I / V conversion circuit 11, a first amplifier circuit 12, and a second amplifier circuit 13. The first amplifier circuit 12 may be realized by three amplifier circuits that respectively amplify the three types of light (the reflected light, the plasma light, and the thermal radiation light). Similarly, the second amplifier circuit 13 may be realized by three amplifier circuits that respectively amplify the three types of light (the reflected light, the plasma light, and the thermal radiation light).

[0028] Each of the sensors 10A-10C (an example of a conversion unit) is realized by a photoelectric element such as a photodiode. Each of the sensors 10A-10C receives the reflected light of the laser light, the plasma light, and the thermal radiation light transmitted from the laser head S3 via an optical fiber. Sensor 10A converts the reflected light of the received laser light into a first current corresponding to the light intensity of the reflected light. Sensor 10B converts the received plasma light into a second current corresponding to the light intensity of the plasma light. Sensor 10C converts the received thermal radiation light into a third current corresponding to the light intensity of the thermal radiation light. Each of the sensors 10A-10C outputs the converted first current, second current, and third current to the I / V conversion circuit 11.

[0029] The I / V conversion circuit 11 acquires the first current, the second current, and the third current output from each of the sensors 10A to 10C, and converts them into voltage signals. Specifically, the I / V conversion circuit 11 converts the first current into a first voltage signal, the second current into a second voltage signal, and the third current into a third current signal. The I / V conversion circuit 11 outputs the converted first voltage signal, second voltage signal, and third voltage signal to the first amplifier circuit 12 (an example of laser welding information).

[0030] The first amplifier circuit 12 is set with a first gain that is different from that of the second amplifier circuit 13 and is smaller than the second gain set in the second amplifier circuit 13. The first amplifier circuit 12 amplifies each of the first voltage signal, the second voltage signal, and the third voltage signal output from the I / V conversion circuit 11 with the first gain. The first amplifier circuit 12 outputs each of the amplified first voltage signal, the second voltage signal, and the third voltage signal (an example of laser welding information) to the second amplifier circuit 13 and the terminal device P3 via the relay board P2. The first amplifier circuit 12 may have individual amplifier circuits that correspond one-to-one to the first voltage signal, the second voltage signal, and the third voltage signal. In such a case, the first amplifier circuit 12 may amplify the first voltage signal, the second voltage signal, and the third voltage signal with three different gains that are smaller than the second gain set in the second amplifier circuit 13.

[0031] The second amplifier circuit 13 is set with a second gain that is different from that of the first amplifier circuit 12 and is larger than the first gain set in the first amplifier circuit 12. The second amplifier circuit 13 amplifies each of the first voltage signal, the second voltage signal, and the third voltage signal output from the first amplifier circuit 12 with the second gain. The second amplifier circuit 13 outputs each of the amplified first voltage signal, the second voltage signal, and the third voltage signal (an example of laser welding information) to the terminal device P3 via the relay board P2. The second amplifier circuit 13 may have individual amplifier circuits that correspond one-to-one to the first voltage signal, the second voltage signal, and the third voltage signal. In such a case, the second amplifier circuit 13 may amplify the first voltage signal, the second voltage signal, and the third voltage signal with three different gains that are larger than the first gain set in the first amplifier circuit 12.

[0032] The relay board P2 is connected to the head control unit S1, the oscillator S2, the spectroscopic unit P1, and the terminal device P3 so as to be able to transmit data between the relay board P2 and each of the head control unit S1, the oscillator S2, the spectroscopic unit P1, and the terminal device P3. The relay board P2 transmits or outputs various data or various signals transmitted or input from the head control unit S1, the oscillator S2, the spectroscopic unit P1, and the terminal device P3 to a predetermined destination.

[0033] The terminal device P3 is realized by, for example, a personal computer (PC), a notebook PC, a tablet terminal, etc. The terminal device P3 is connected between the relay board P2 and the monitor MN so as to be able to perform data communication. The terminal device P3 includes a communication unit 30, a processor 31, and a memory 32.

[0034] The communication unit 30 transmits and receives data between the relay board P2 and the monitor MN. The communication unit 30 outputs various signals transmitted from the relay board P2 to the processor 31. The communication unit 30 also transmits a voltage signal screen (not shown) or a pass / fail judgment result screen (not shown) generated by the processor 31 to the monitor MN for display.

[0035] The processor 31 (an example of an acquisition unit and a determination unit) is configured using, for example, a Central Processing Unit (CPU) or a Field Programmable Gate Array (FPGA), and performs various processes and controls in cooperation with the memory 32. Specifically, the processor 31 refers to the programs and data stored in the memory 32, and executes the programs to realize various functions of the processor 31, which will be described later.

[0036] The processor 31 acquires each of the first voltage signal, the second voltage signal, and the third voltage signal output from the first amplifier circuit 12, and each of the first voltage signal, the second voltage signal, and the third voltage signal output from the second amplifier circuit 13. The processor 31 determines whether each of the first voltage signal, the second voltage signal, and the third voltage signal output from the second amplifier circuit 13, that is, each voltage signal amplified with the second gain, is equal to or higher than a measurement upper limit UL (an example of a saturation value, see FIG. 2).

[0037] The processor 31 determines whether to use the signal output from the second amplifier circuit 13 or to acquire one of the voltage signals output from the first amplifier circuit 12 based on whether each voltage signal output from the second amplifier circuit 13 is equal to or greater than the measurement upper limit UL (see Figure 2).

[0038] The measurement upper limit UL here is an upper limit value (saturation value) of each voltage signal output from the second amplifier circuit 13, and is a value that is arbitrarily set by the user. When the signal level of the voltage signal is equal to or higher than the measurement upper limit UL, the processor 31 determines that the voltage signal output from the second amplifier circuit 13 is in a saturation state.

[0039] When the processor 31 determines that each voltage signal output from the second amplifier circuit 13 is equal to or greater than the measurement upper limit UL, the processor 31 acquires the signal output from the first amplifier circuit 12, and when the processor 31 determines that each voltage signal is not equal to or greater than the measurement upper limit UL, the processor 31 acquires the signal output from the second amplifier circuit 13. That is, the processor 31 acquires a signal suitable for determining the quality of laser welding from the first amplifier circuit 12 or the second amplifier circuit 13 for each voltage signal. Therefore, it goes without saying that the processor 31 may acquire signals output from different amplifier circuits for each voltage signal.

[0040] The processor 31 acquires electrical signals suitable for determining whether the laser welding is good or bad from among the voltage signals amplified by the first amplifier circuit 12 or the second amplifier circuit 13, which correspond to the reflected light of the laser light, the plasma light, and the thermal radiation light, respectively, and records the acquired electrical signals in a storage device (not shown) such as a solid state drive (hereinafter referred to as "SSD") or a hard disk drive (hereinafter referred to as "HDD"), and performs a determination of whether the laser welding is good or bad using the voltage signals. Note that the standard used for determining whether the laser welding is good or bad may be the measurement upper limit UL, or may be an arbitrary value newly set by the user.

[0041] In such a case, the processor 31 may delete data of the voltage signal that was output from the first amplifier circuit 12 or the second amplifier circuit 13 to the processor 31 but was not used to determine the quality of the laser welding.

[0042] In addition, the processor 31 may generate a voltage signal screen (not shown) that visualizes the voltage signal waveform of the voltage signal used to determine whether the laser welding is good or bad, among the first voltage signal, the second voltage signal, and the third voltage signal output from the first amplifier circuit 12 and the second amplifier circuit 13, or a pass / fail judgment result screen (not shown) that includes the pass / fail judgment result of the laser welding, and output it to the monitor MN.

[0043] The memory 32 has, for example, a Random Access Memory (RAM) as a work memory used when executing each process of the processor 31, and a Read Only Memory (ROM) for storing programs and data that define the operation of the processor 31. The RAM temporarily stores data or information generated or acquired by the processor 31. The ROM has written therein programs that define the operation of the processor 31.

[0044] The monitor MN is connected to the terminal device P3 so as to be able to perform data communication with the terminal device P3. The monitor MN is configured using a display such as a Liquid Crystal Display (LCD) or an organic electroluminescence (EL). The monitor MN displays a voltage signal screen (not shown) or a pass / fail judgment result screen (not shown) generated and output by the terminal device P3.

[0045] 1 shows an example of the spectroscopic unit P1 having a configuration in which the first amplifier circuit 12 and the second amplifier circuit 13 are connected in series, but is not limited to this. For example, the first amplifier circuit 12 and the second amplifier circuit 13 may be connected in parallel to the I / V conversion circuit 11. In such a case, each of the first voltage signal, the second voltage signal, and the third voltage signal outputted from the second amplifier circuit 13 is amplified by only the second gain.

[0046] Next, the electrical signal amplified by the first amplifier circuit 12 when transitioning from heat conduction welding to keyhole welding will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a diagram showing examples of voltage signal waveforms SG11, SG21 obtained by the first amplifier circuit 12 when transitioning from heat conduction welding to keyhole welding. Fig. 3 is a diagram showing examples of voltage signal waveforms SG12, SG22 obtained by the second amplifier circuit 13 when transitioning from heat conduction welding to keyhole welding.

[0047] For ease of explanation, the voltage signal waveforms SG21 and SG22 shown in Fig. 2 and Fig. 3 are illustrated as a single voltage signal waveform that combines the voltage signal waveform corresponding to the plasma light and the voltage signal waveform corresponding to the thermal radiation light. In addition, in order to make it easier to understand the difference in gain set in each of the first amplifier circuit 12 and the second amplifier circuit 13, the voltage signal waveforms SG12 and SG22 shown in Fig. 3 show an example in which the voltage signal is amplified to a signal level equal to or higher than the measurement upper limit UL around time T1, but it goes without saying that the voltage signal amplified by the second amplifier circuit 13 is not necessarily equal to or higher than the measurement upper limit UL.

[0048] The voltage signal waveform SG11 is a voltage signal corresponding to the reflected light, and is a first voltage signal amplified with a first gain by the first amplifier circuit 12. The voltage signal waveform SG21 is a voltage signal corresponding to the plasma light and the thermal radiation light, and is a second voltage signal and a third voltage signal amplified with a first gain by the first amplifier circuit 12. In each of the voltage signal waveforms SG11 and SG21, the horizontal axis indicates time, and the vertical axis indicates the magnitude of the signal level of the voltage signal.

[0049] The voltage signal waveform SG12 is a voltage signal corresponding to the reflected light, and is a first voltage signal obtained by amplifying a first voltage signal by a first gain by the first amplifier circuit 12 and further amplified by a second gain by the second amplifier circuit 13. The voltage signal waveform SG22 is a voltage signal corresponding to the plasma light and the thermal radiation light, and is a second voltage signal and a third voltage signal obtained by amplified by a first gain by the first amplifier circuit 12 and further amplified by a second gain by the second amplifier circuit 13. In each of the voltage signal waveforms SG12 and SG22, the horizontal axis indicates time and the vertical axis indicates the magnitude of the signal level of the voltage signal.

[0050] 2 and 3, the state of laser welding changes from heat conduction welding to keyhole welding at time T1. In this case, the signal levels of the voltage signal waveforms SG11 and SG12 corresponding to the first voltage signal decrease after time T1. On the other hand, the signal levels of the voltage signal waveforms SG21 and SG22 corresponding to the second and third voltage signals, respectively, increase after time T1.

[0051] Next, the electrical signal amplified by the first amplifier circuit 12 when transitioning from keyhole welding to heat conduction welding will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is a diagram showing examples of voltage signal waveforms SG13, SG23 obtained by the first amplifier circuit 12 when transitioning from heat conduction welding to keyhole welding. Fig. 5 is a diagram showing examples of voltage signal waveforms SG14, SG24 obtained by the second amplifier circuit 13 when transitioning from heat conduction welding to keyhole welding.

[0052] For ease of explanation, the voltage signal waveforms SG23 and SG24 shown in Fig. 4 and Fig. 5 are illustrated as a single voltage signal waveform that combines the voltage signal waveform corresponding to the plasma light and the voltage signal waveform corresponding to the thermal radiation light. Also, in order to make it easier to understand the difference in gain set in each of the first amplifier circuit 12 and the second amplifier circuit 13, the voltage signal waveforms SG14 and SG24 shown in Fig. 5 show an example in which the voltage signal is amplified to a signal level equal to or higher than the measurement upper limit UL around time T1, but it goes without saying that the voltage signal amplified by the second amplifier circuit 13 is not necessarily equal to or higher than the measurement upper limit UL.

[0053] The voltage signal waveform SG13 is a voltage signal corresponding to the reflected light, and is a first voltage signal amplified by a first gain by the first amplifier circuit 12. The voltage signal waveform SG23 is a voltage signal corresponding to the plasma light and the thermal radiation light, and is a second voltage signal and a third voltage signal amplified by a first gain by the first amplifier circuit 12. In each of the voltage signal waveforms SG13 and SG23, the horizontal axis indicates time, and the vertical axis indicates the magnitude of the signal level of the voltage signal.

[0054] The voltage signal waveform SG14 is a voltage signal corresponding to the reflected light, and is a first voltage signal obtained by amplifying a first voltage signal by a first gain by the first amplifier circuit 12 and further amplified by a second gain by the second amplifier circuit 13. The voltage signal waveform SG24 is a voltage signal corresponding to the plasma light and the thermal radiation light, and is a second voltage signal and a third voltage signal obtained by amplified by a first gain by the first amplifier circuit 12 and further amplified by a second gain by the second amplifier circuit 13. In each of the voltage signal waveforms SG14 and SG24, the horizontal axis indicates time and the vertical axis indicates the magnitude of the signal level of the voltage signal.

[0055] 4 and 5, the state of laser welding changes from keyhole welding to heat conduction welding at time T1. In this case, the signal levels of the voltage signal waveforms SG13 and SG14 corresponding to the first voltage signal increase after time T1. On the other hand, the signal levels of the voltage signal waveforms SG23 and SG24 corresponding to the second and third voltage signals, respectively, decrease after time T1.

[0056] Next, an example of an operation procedure of the process monitor unit PM will be described with reference to Fig. 6. Fig. 6 is a flowchart showing an example of an operation procedure of the process monitor unit PM in the embodiment.

[0057] The spectroscopic unit P1 receives the reflected light of the laser light, the plasma light, and the thermal radiation light transmitted from the laser head S3 by the sensors 10A-10C corresponding to each light. The spectroscopic unit P1 converts the received reflected light of the laser light, the plasma light, and the thermal radiation light into a first voltage signal, a second voltage signal, and a third voltage signal, respectively, by the I / V conversion circuit 11, thereby obtaining voltage signals corresponding to the reflected light of the laser light, the plasma light, and the thermal radiation light, respectively (St11).

[0058] The spectroscopic unit P1 amplifies the acquired first voltage signal, second voltage signal, and third voltage signal by the first amplifier circuit 12 to which a first gain is set, and outputs the amplified first voltage signal, second voltage signal, and third voltage signal to the second amplifier circuit 13 and the terminal device P3. The spectroscopic unit P1 amplifies the amplified first voltage signal, second voltage signal, and third voltage signal by the second amplifier circuit 13 to which a second gain is set, and outputs the amplified first voltage signal, second voltage signal, and third voltage signal to the terminal device P3 (St12). Here, the first gain is smaller than the second gain.

[0059] The terminal device P3 acquires the voltage signals amplified by either the first amplifier circuit 12 or the second amplifier circuit 13 for each of the first voltage signal, the second voltage signal, and the third voltage signal as voltage signals suitable for determining whether the laser welding is successful or not (St13).

[0060] Specifically, the terminal device P3 determines whether the first voltage signal amplified by the first amplifier circuit 12 or the first voltage signal amplified by the second amplifier circuit 13 is a voltage signal suitable for determining whether the laser welding is successful or not, based on whether the first voltage signal amplified by the second amplifier circuit 13 corresponds to the reflected light and has a signal level equal to or higher than the measurement upper limit UL (St14).

[0061] When the terminal device P3 determines that the first voltage signal amplified by the second amplifier circuit 13 has a signal level equal to or higher than the measurement upper limit UL (St14, YES), it determines that the first voltage signal amplified by the first amplifier circuit 12 is a voltage signal suitable for determining the quality of laser welding, and acquires the first voltage signal amplified by the first amplifier circuit 12 and records it in the memory 32 (St15). In such a case, the terminal device P3 deletes the first voltage signal amplified by the second amplifier circuit 13.

[0062] When the terminal device P3 determines that the first voltage signal amplified by the second amplifier circuit 13 is not at a signal level equal to or higher than the measurement upper limit UL (St14, NO), it determines that the first voltage signal amplified by the second amplifier circuit 13 is a voltage signal suitable for determining the quality of laser welding, and acquires the first voltage signal amplified by the second amplifier circuit 13 and records it in the memory 32 (St16). In such a case, the terminal device P3 deletes the first voltage signal amplified by the first amplifier circuit 12.

[0063] The terminal device P3 performs the above-mentioned processing of steps St14 to St16 on the second electrical signal corresponding to the plasma light and the third electrical signal corresponding to the thermal radiation light, respectively, and obtains the second electrical signal and the third electrical signal suitable for determining whether the laser welding is successful or not.

[0064] As a result, even if the state of laser welding changes during laser welding, the process monitor unit PM in the embodiment can obtain voltage signals that are more suitable for determining whether the laser welding is good or bad from the voltage signals corresponding to the reflected laser light, the plasma light, and the thermal radiation light. Also, the process monitor unit PM can obtain voltage signals that are equal to or lower than the measurement upper limit UL and are higher than the measurement upper limit UL by comparing each electrical signal amplified by the second amplifier circuit 13 with the measurement upper limit UL.

[0065] Moreover, by amplifying the first voltage signal, the second voltage signal, and the third voltage signal with different gains, the process monitor unit PM does not need to adjust the gain during laser welding, and an increase in the number of steps required for adjusting the gain can be prevented. Also, the process monitor unit PM does not need to have a plurality of process monitor units each adjusted to a different gain.

[0066] Moreover, the process monitor unit PM in the embodiment can delete unnecessary voltage signals that are determined to be unsuitable for determining the quality of laser welding, thereby recording only the voltage signals corresponding to the reflected light of laser light, plasma light, and thermal radiation light, which are necessary for determining the quality of laser welding. This allows the process monitor unit PM to more effectively prevent a shortage of capacity in the storage device that is the recording destination, and also supports the user who manages the process monitor unit PM in checking the voltage signals more efficiently.

[0067] As described above, the process monitor unit PM in the embodiment includes sensors 10A-10C (an example of a conversion unit) that receive light generated when laser light is irradiated for laser welding and convert it into an electrical signal, a first amplifier circuit 12 that amplifies the electrical signal by a first gain, a second amplifier circuit 13 that amplifies the electrical signal by a second gain different from the first gain, and a processor 31 (an example of an acquisition unit) that acquires and outputs either the first electrical signal amplified by the first amplifier circuit 12 (specifically, each of the first voltage signal, second voltage signal, and third voltage signal output from the first amplifier circuit 12) or the second electrical signal amplified by the second amplifier circuit 13 (specifically, each of the first voltage signal, second voltage signal, and third voltage signal output from the second amplifier circuit 13).

[0068] As a result, the process monitor unit PM in the embodiment can acquire a voltage signal (an example of laser welding information) that is suitable for the current laser welding state and that can determine whether or not laser welding is necessary, by amplifying the voltage signal with two different gains, even if the signal level of each acquired voltage signal changes as the laser welding state transitions between heat conduction welding and keyhole welding.

[0069] Furthermore, when the processor 31 of the process monitor unit PM in the embodiment determines that the first electric signal is equal to or lower than the measurement upper limit UL (an example of a saturation value) of the first electric signal, the processor 31 acquires the first electric signal, which allows the process monitor unit PM in the embodiment to acquire a voltage signal (laser welding information) that is suitable for the current state of laser welding and that can determine whether laser welding is necessary or not.

[0070] Furthermore, when the processor 31 of the process monitor unit PM in the embodiment determines that the first electric signal is not equal to or lower than the measurement upper limit UL of the first electric signal, it acquires the second electric signal, which allows the process monitor unit PM in the embodiment to acquire a voltage signal (laser welding information) that is suitable for the current state of laser welding and can determine whether laser welding is necessary or not.

[0071] Moreover, the processor 31 of the process monitor unit PM in the embodiment omits and deletes the acquisition of either the other electric signal, thereby enabling the process monitor unit PM in the embodiment to effectively prevent a shortage of capacity of a storage device or storage medium such as the memory 32, HDD, or SSD caused by recording a voltage signal (laser welding information) that is not necessary for determining the quality of laser welding.

[0072] The process monitor unit PM in the embodiment further includes a processor 31 (an example of a judgment unit) that executes pass / fail judgment of laser welding that can transition to a plurality of different welding states (i.e., each of heat conduction welding and keyhole welding) based on one of the electrical signals acquired by the processor 31, and outputs the result of the pass / fail judgment. As a result, the process monitor unit PM in the embodiment can execute pass / fail judgment of laser welding based on the acquired first electrical signal or second electrical signal, even when the laser welding state transitions between heat conduction welding and keyhole welding.

[0073] Moreover, the laser light of the process monitor unit PM in the embodiment is a blue laser. As a result, the process monitor unit PM in the embodiment can obtain a voltage signal capable of determining whether or not laser welding is required, the voltage signal having a wavelength of blue light (i.e., 400 nm to 500 nm). Blue laser light has a characteristic that it is absorbed by copper at a high absorption rate (up to about 65%), so it is particularly effective when laser welding copper.

[0074] Although various embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications, corrections, substitutions, additions, deletions, and equivalents within the scope of the claims, and it is understood that these also belong to the technical scope of the present disclosure. In addition, the components in the various embodiments described above may be arbitrarily combined within the scope of the invention. [Industrial Applicability]

[0075] INDUSTRIAL APPLICABILITY The present disclosure is useful as a process monitor unit and a method for acquiring laser welding information that can acquire information that enables determination of the quality of a welded portion even when the welding state of laser welding transitions. [Explanation of symbols]

[0076] 10A, 10B, 10C Sensor 11 I / V conversion circuit 12 First amplifier circuit 13 Second amplifier circuit 100 Laser Processing Head System MN Monitor P1 Spectroscopic Unit P2 Relay board P3 terminal equipment PM Process Monitor Unit S1 Head Control Unit S2 Oscillator S3 Laser Head

Claims

1. A conversion unit that receives light generated when a laser beam is irradiated during laser welding and converts the light into an electrical signal; a first amplifier that amplifies the electrical signal by a first gain; a second amplifier that amplifies the electrical signal by a second gain that is greater than the first gain; an acquisition unit that acquires and outputs either a first electrical signal amplified by the first amplifier unit or a second electrical signal amplified by the second amplifier unit; Process Monitor Unit.

2. When the acquisition unit determines that the second electrical signal is equal to or less than a saturation value of the second electrical signal, the acquisition unit acquires the second electrical signal.

2. The process monitor unit according to claim 1.

3. the acquiring unit acquires the first electrical signal when it is determined that the second electrical signal is not equal to or less than a saturation value of the second electrical signal.

3. The process monitor unit according to claim 2.

4. The acquisition unit omits and deletes acquisition of the other electrical signal.

2. The process monitor unit according to claim 1.

5. A determination unit that performs a quality determination of the laser welding that transitions to a plurality of different welding states based on any one of the electrical signals acquired by the acquisition unit, and outputs a result of the quality determination.

2. The process monitor unit according to claim 1.

6. The laser light is a blue laser.

2. The process monitor unit according to claim 1.

7. A method for acquiring laser welding information by a computer, comprising: The light generated during laser welding is received and converted into an electrical signal. amplifying the electrical signal by a first gain and a second gain greater than the first gain; acquiring one of a first electrical signal amplified by the first gain and a second electrical signal amplified by the second gain; How to obtain laser welding information.

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