Method and device for detecting contamination on protective glass

Abstract

To more accurately detect contamination on protective glass comprised in a laser head.SOLUTION: A method for detecting contamination on protective glass includes: acquiring temperature data output from at least one temperature sensor that measures the temperature of protective glass comprised in a laser head, and dispersion light intensity data output from at least one dispersion light sensor that measures the intensity of dispersion light scattered on the protective glass; calculating a score for evaluating a contamination degree of the protective glass, on the basis of the temperature data and the dispersion light intensity data; and outputting a notification to the effect that contamination has been detected on the protective glass when determined that contamination has been detected on the protective glass, according to the score.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to a method for detecting dirt on a protective glass and an apparatus for detecting dirt on a protective glass. [Background technology]

[0002] For example, Patent Document 1 discloses a protective glass dirt detection device that includes a differential conversion circuit fixed to a holder for the protective glass, which converts the current output of a photosensor that detects scattered light from the side of the protective glass of a processing laser light that is incident approximately perpendicularly on the protective glass of a laser welding machine using a scanner head into a voltage that can withstand low-noise transmission using a multi-core cable, and differentially converts the converted voltage output to output a differential signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-179405 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure has been devised in consideration of the above-mentioned conventional circumstances, and aims to provide a method and device for detecting dirt on a protective glass that detects dirt on a protective glass provided in a laser head with greater accuracy. [Means for solving the problem]

[0005] The present disclosure provides a method for detecting dirt on a protective glass performed by a computing device, which acquires temperature data output from at least one temperature sensor that measures the temperature of a protective glass provided in a laser head and scattered light intensity data output from at least one scattered light sensor that measures the intensity of scattered light scattered by the protective glass, calculates a score for evaluating the degree of dirt on the protective glass based on the temperature data and the scattered light intensity data, and if it is determined based on the score that dirt on the protective glass has been detected, outputs a notification that dirt on the protective glass has been detected.

[0006] The present disclosure also provides a protective glass dirt detection device comprising: an acquisition unit that acquires temperature data output from at least one temperature sensor that measures the temperature of a protective glass provided in a laser head and scattered light intensity data output from at least one scattered light sensor that measures the intensity of scattered light scattered by the protective glass; a calculation unit that calculates a score for evaluating the degree of dirt on the protective glass based on the temperature data and the scattered light intensity data; and an output unit that outputs a notification that dirt on the protective glass has been detected when it is determined that dirt on the protective glass has been detected based on the score. Effect of the Invention

[0007] According to the present disclosure, dirt on the protective glass provided on the laser head can be detected with higher accuracy. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing an example of the overall configuration of a laser head system according to an embodiment; [Diagram 2] FIG. 1 is a block diagram showing an example of the internal configuration of a head control unit according to an embodiment. [Diagram 3] FIG. 1 shows an example of a laser head. [Figure 4] AA cross section of protective glass [Diagram 5] 1 is a flowchart showing an example of an operation procedure of a head control unit according to an embodiment. [Figure 6] FIG. 1 is a diagram showing an example of a temperature graph acquired by a temperature sensor; [Figure 7] FIG. 13 is a diagram showing an example of a scattered light intensity graph acquired by a scattered light sensor; [Figure 8] FIG. 13 is a diagram showing an example of a dirt detection graph. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Background to this disclosure) Conventionally, the scanner head of a laser welding machine (hereinafter referred to as the "laser head") has a technology that uses a temperature sensor to measure the temperature inside the laser head to prevent damage to the parts inside the laser head during welding, and a scattered light sensor to detect dirt on the protective glass to prevent deterioration of welding quality.

[0010] However, the method of managing damage to the laser head using a temperature sensor requires time to detect the temperature inside the laser head, so the laser head may already be in a high temperature state by the time an abnormality is determined based on the detected temperature. Also, when the laser head is repeatedly irradiated with the output of a laser beam for a short period of time, a defective weld may occur or the laser head may be damaged, although an abnormality based on the temperature may not be determined.

[0011] Furthermore, the method for detecting dirt on a protective glass using a scattered light sensor has a problem in that the detection result of the scattered light intensity varies depending on the temperature characteristics of the scattered light sensor itself. Therefore, in the method for detecting dirt on a protective glass using a scattered light sensor, there is a possibility that the accuracy of detecting dirt on the protective glass may decrease due to temperature changes inside the laser head.

[0012] Therefore, in the following embodiment, an example of a method and device for detecting dirt on a protective glass that can detect dirt with high accuracy regardless of the type of dirt in damage management of a laser head in laser welding will be described.

[0013] Hereinafter, with reference to the drawings as appropriate, an embodiment specifically disclosing a method for detecting dirt on a protective glass and an apparatus for detecting dirt on a protective glass 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 and 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.

[0014] <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.

[0015] A laser 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 head system 100 according to the embodiment. It is needless to say that the laser head system 100 shown in Fig. 1 is merely an example and is not limited thereto.

[0016] The laser head system 100 includes an oscillator OS, a laser head LH, a workpiece Wk, a head control unit HC, and an output section 33. Note that the output section 33 may be configured integrally with the head control unit HC.

[0017] The laser head system 100 performs laser welding by irradiating a laser beam oscillated by an oscillator OS toward a welding spot on a workpiece Wk via a laser head LH. The laser head system 100 detects dirt on each of the protective glasses 21A, 21B based on sensing results from a plurality of temperature sensors 22A, 22B, ... and a plurality of scattered light sensors 23A, 23B, ... provided on each of the protective glasses 21A, 21B of the laser head LH.

[0018] The oscillator OS outputs a laser beam used for laser welding. The oscillator OS is connected to the laser head LH by a fiber 10 capable of transmitting a laser beam, such as an optical fiber. The oscillator OS outputs a laser beam to the laser head LH via the fiber 10.

[0019] Here, the laser light emitted by the oscillator OS may be a so-called blue laser light having a wavelength of blue (that is, 400 nm to 500 nm), or may be a laser light of another wavelength.

[0020] The laser head LH irradiates the workpiece Wk with the laser light transmitted through the fiber 10. The laser head LH has optical components such as a collimation lens 11, a focus lens 12, and a protective glass unit 21. The laser head LH has these optical components housed inside the housing of the laser head LH while maintaining a predetermined positional relationship.

[0021] The laser head LH acquires the temperatures in the vicinity of each of the protective glasses 21A and 21B and the scattered light intensity in the vicinity of each of the protective glasses 21A and 21B, and converts them into electrical signals. The laser head LH transmits the temperature data (electrical signal) and scattered light intensity data (electrical signal) corresponding to each of the protective glasses 21A and 21B to the head control unit HC.

[0022] The head control unit HC (an example of a calculation device and a dirt detection device for a protective glass) is connected to the protective glass unit 21 so as to be able to perform data communication with the protective glass unit 21. The head control unit HC detects dirt on each of the protective glasses 21A, 21B and determines the type of dirt based on the temperature data and scattered light intensity data transmitted from the laser head LH. The head control unit HC outputs the detection result of dirt on each of the protective glasses 21A, 21B or the determination result of the type of dirt to the output section 33.

[0023] Next, the head control unit HC will be described with reference to Fig. 2. Fig. 2 is a block diagram showing an example of the internal configuration of the head control unit HC in this embodiment.

[0024] The communication unit 30 (an example of an acquisition unit) is connected to each of the multiple temperature sensors 22A, ... and each of the multiple scattered light sensors 23A, ... so as to be able to communicate data with each other. The communication unit 30 outputs the temperature data transmitted from each of the multiple temperature sensors 22A, ... and the scattered light intensity data transmitted from each of the multiple scattered light sensors 23A, ... to the processor 31. The communication unit 30 outputs the various data output from the processor 31 to the output unit 33.

[0025] The processor 31 (an example of a calculation unit and an output 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 calculation unit 31A, the processing unit 31B, and the determination unit 31C.

[0026] The calculation unit 31A processes the temperature data transmitted from each of the plurality of temperature sensors 22A, ... and the scattered light intensity data transmitted from each of the plurality of scattered light sensors 23A, ... into data usable by the determination unit 31C described below. The calculation unit 31A outputs the processed temperature data or scattered light intensity data to the determination unit 31C.

[0027] The processing unit 31B performs temperature correction processing for each of the multiple scattered light sensors 23A, ... based on temperature data transmitted from each of the multiple temperature sensors 22A, ... or scattered light intensity data transmitted from each of the multiple scattered light sensors 23A, ..., and performs data processing for executing dirt detection processing and dirt type determination processing.

[0028] The determination unit 31C executes a dirt detection process and a dirt type determination process for each protective glass 21A, ... based on the temperature data or scattered light intensity data after arithmetic processing output from the calculation unit 31A. The determination unit 31C generates and outputs the results of the dirt detection process and the dirt type determination process.

[0029] 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.

[0030] The output unit 33 is connected to the communication unit 30 of the head control unit HC so as to be able to communicate data with it. The output unit 33 is configured using, for example, a display such as a Liquid Crystal Display (LCD) or an organic electroluminescence (EL), or a speaker, etc. The output unit 33 outputs a screen or sound, etc., which notifies the result of the dirt determination or the result of the dirt type determination output from the head control unit HC.

[0031] Next, the laser head LH will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a diagram showing an example of the laser head LH. Fig. 4 is a cross-sectional view of the protective glass 21A taken along line AA.

[0032] 3 and 4 will be described as an example in which the temperature and scattered light intensity of protective glass 21A are measured by each of two temperature sensors 22A, 22B and each of three scattered light sensors 23A, 23B, 23C. It goes without saying that the number and arrangement of temperature sensors that measure the temperature of each protective glass 21A, 21B and the number and arrangement of scattered light sensors that measure the intensity of scattered light diffracted and scattered by each protective glass 21A, 21B are not limited to this.

[0033] The temperatures and scattered light intensities of protective glass 21A and protective glass 21B are acquired by similar configurations and methods. Therefore, this disclosure will only describe the configurations of two temperature sensors 22A, 22B and three scattered light sensors 23A, 23B, 23C provided on protective glass 21A, the method of acquiring the temperature and scattered light intensity of protective glass 21A acquired by these sensors, and the detection of dirt on protective glass 21A and the determination of the type of dirt.

[0034] The collimation lens 11 converts the laser light incident via the fiber 10 into parallel light and causes the parallel light to be incident on the focus lens 12. Note that the collimation lens 11 may be capable of adjusting the focal position of the incident laser light along the irradiation direction of the laser light.

[0035] The focus lens 12 focuses the laser light, which has been converted into parallel light by the collimation lens 11, on the surface (welding location) of the workpiece Wk. The laser light passes through each of the two protective glasses 21A and 21B provided in the protective glass unit 21 in the process of being focused on the surface (welding position) of the workpiece Wk.

[0036] The protective glass unit 21 includes a plurality of protective glasses 21A, 21B, a plurality of temperature sensors 22A, ..., and a plurality of scattered light sensors 23A, .... Each of the protective glasses 21A, 21B has a substantially circular shape when viewed from the direction of irradiation of the laser light (the upper side of the paper surface). The multiple temperature sensors 22A, 22B and the scattered light sensors 23A to 23C are arranged in a substantially straight line along the height at which the protective glass 21A is arranged. Each of the protective glasses 21A, 21B may include at least one temperature sensor and at least one scattered light sensor.

[0037] Each of the multiple temperature sensors 22A-22B is disposed in the vicinity of the protective glass 21A at equal distances from and equidistant from a center position 21AA (an example of a center position) of the protective glass 21A. For example, since there are two temperature sensors 22A, 22B shown in Fig. 4, they are disposed at the same distance from the center position 21AA of the protective glass 21A and facing each other with the protective glass 21A in between.

[0038] Each of the temperature sensors 22A to 22B is a sensor capable of measuring temperature. Each of the temperature sensors 22A to 22B measures the temperature at a position near the protective glass 21A. Each of the temperature sensors 22A, 22B generates temperature data (electrical signal) indicating the measured temperature and transmits it to the head control unit HC.

[0039] The multiple scattered light sensors 23A-23C are disposed at equal intervals from each other and at the same distance from the center position 21AA of the protective glass 21A. The multiple scattered light sensors 23A-23C may be disposed at the same distance from the center position 21AA of the protective glass 21A as the temperature sensors 22A-22B, that is, on a concentric circle on which the temperature sensors 22A-22B are provided. For example, since there are three scattered light sensors 23A-23C shown in Fig. 4, they are disposed at the same distance from the center position 21AA of the protective glass 21A and are disposed at equal intervals of 120° each on a concentric circle centered on the center position 21AA of the protective glass 21A.

[0040] Each of the scattered light sensors 23A-23C is a sensor capable of measuring the intensity of scattered light when laser light, such as a photodiode, is irradiated onto the workpiece Wk. Each of the scattered light sensors 23A-23C generates scattered light intensity data (electrical signal) indicating the intensity of the measured scattered light by photoelectric conversion, and transmits the data to the head control unit HC.

[0041] Next, an example of the operation procedure of the head control unit HC will be described with reference to Fig. 5. Fig. 5 is a flowchart showing an example of the operation procedure of the head control unit HC in the embodiment. Fig. 5 also describes an example of detecting dirt on protective glass 21A and determining the type of dirt, and omits a description of protective glass 21B.

[0042] The oscillator OS starts outputting a laser beam based on a control command to start a welding process by laser welding. The laser head LH irradiates the laser beam outputted by the oscillator OS onto the surface (welding position) of the workpiece Wk, thereby achieving laser welding (St11).

[0043] Processing unit 31B determines whether the temperatures measured by temperature sensors 22A-22B are equal to or higher than threshold value T_a° C. (an example of a predetermined temperature) based on each of the plurality of temperature data (St12). Note that threshold value T_a may be set to an arbitrary value based on the temperature characteristics of each of scattered light sensors 23A, 23B.

[0044] When processing section 31B determines that the temperatures measured by multiple temperature sensors 22A-22B are equal to or higher than threshold value T_a° C. (St12, YES), it executes temperature characteristic correction of the scattered light sensor (St13).

[0045] When the temperature sensors and scattered light sensors are arranged in the vicinity of protective glass 21A in a one-to-one correspondence, processing unit 31B performs temperature characteristic correction only on the scattered light sensor corresponding to the temperature sensor whose measured temperature is equal to or higher than T_a° C. On the other hand, when the temperature sensors and scattered light sensors are not arranged in the vicinity of protective glass 21A in a one-to-one correspondence, processing unit 31B performs temperature characteristic correction on all scattered light sensors that measure the intensity of scattered light incident on protective glass 21A.

[0046] On the other hand, when processing unit 31B determines that the temperatures measured by the plurality of temperature sensors 22A-22B are not equal to or higher than threshold value T_a° C. (St12, NO), it omits the process of correcting the temperature characteristics of the scattered light sensor.

[0047] The calculation unit 31A acquires temperature data transmitted from the plurality of temperature sensors 22A-22B that measure the temperature of the protective glass 21A, and scattered light intensity data transmitted from the plurality of scattered light sensors 23A-23C that measure the intensity of scattered light incident on the protective glass 21A (St14). The calculation unit 31A performs calculation processing on the acquired plurality of temperature data and the plurality of scattered light intensity data into data that can be processed by the judgment unit 31C, and outputs the data to the judgment unit 31C (St14).

[0048] The judgment unit 31C acquires a temperature rise value f (an example of a temperature score) and a scattered light intensity g (an example of a scattered light intensity score) of the protective glass 21A based on the acquired temperature data and scattered light intensity data. The judgment unit 31C calculates a dirt judgment value P (=αf+βg) (an example of a score) for detecting dirt on the protective glass 21A based on a value αf obtained by multiplying the temperature rise value f by a predetermined coefficient α and a value βg obtained by multiplying the scattered light intensity g by a predetermined coefficient β. The judgment unit 31C judges whether the calculated dirt judgment value P is equal to or greater than a threshold value K_sh (an example of a predetermined value) (St15). The threshold value K_sh here is a value for judging whether the protective glass 21A is dirty or not.

[0049] The temperature rise value f used in calculating the dirt determination value P may be the average value of the temperatures measured by each of the multiple temperature sensors 22A-22B, or the highest temperature. The scattered light intensity g used in calculating the dirt determination value P may be the average value of the scattered light intensities measured by each of the multiple scattered light sensors 23A-23C, or the highest scattered light intensity among the scattered light intensities measured by each of the multiple scattered light sensors 23A-23C.

[0050] If the judgment unit 31C determines that the dirt judgment value P is greater than or equal to the threshold value K_sh (St15, YES), it determines that dirt has been detected on the protective glass 21A, and generates a notification screen or notification sound, etc. to notify the detection of dirt on the protective glass 21A, and outputs it to the output unit 33 (St16).

[0051] On the other hand, when the judgment unit 31C judges that the dirt judgment value P is not equal to or greater than the threshold value K_sh (St15, NO), the process returns to step St12.

[0052] The judgment unit 31C calculates a judgment value Q (=γf / δg) for judging the type of dirt on the protective glass 21A based on a value γf obtained by multiplying the acquired temperature rise value f by a predetermined coefficient γ and a value δg obtained by multiplying the scattered light intensity g by a predetermined coefficient δ (St17). The judgment unit 31C judges whether the calculated judgment value Q is Q≧1 or not (St18).

[0053] When the processor 31B determines that the judgment value Q is equal to or larger than 1 (St18, YES), it determines that the dirt type is “dirt particles: large” and that the dirt is caused by accidental dirt on the protective glasses 21A and 21B. The processor 31B generates a notification screen or notification sound or the like notifying the user of the dirt type “dirt particles: large” on the protective glass 21A and outputs the generated notification screen or notification sound to the output unit 33 (St19).

[0054] On the other hand, when the processor 31B determines that the judgment value Q is not equal to or greater than 1 (St18, NO), it determines that the dirt type is “dirt particles: small” and that the dirt on the protective glasses 21A and 21B over time is the cause of the dirt. The processor 31B generates a notification screen or notification sound or the like notifying the user of the dirt type “dirt particles: small” on the protective glass 21A and outputs the generated notification screen or notification sound to the output unit 33 (St20).

[0055] The dirt type "dirt particles: large" indicates large foreign matter such as spatter generated during laser welding or visible particles. The dirt type "dirt particles: small" indicates small foreign matter such as fume adhesion during laser welding or particles that are difficult to see. The temperature change of protective glass 21A and the change in scattered light sensor intensity due to the size of the dirt particles will be described later.

[0056] As a result, the head control unit HC in the embodiment can improve the measurement accuracy of the scattered light intensity by the scattered light sensors 23A-23C by correcting the temperature characteristics of each of the scattered light sensors 23A-23C corresponding to the temperature sensors or all of the scattered light sensors 23A-23C based on the temperature data obtained by the multiple temperature sensors 22A-22B.

[0057] In addition, by using the dirt judgment value P, the head control unit HC can detect dirt on each of the protective glasses 21A, 21B regardless of the type of dirt on each of the protective glasses 21A, 21B, and can more effectively suppress damage to the inside of the laser head LH due to temperature increases inside the laser head LH and poor welding or deterioration of welding quality due to dirt on each of the protective glasses 21A, 21B.

[0058] Moreover, the head control unit HC can use the determination value Q to detect the type of dirt on each of the protective glasses 21A and 21B.

[0059] In addition, the head control unit HC can collect learning data for machine learning or deep learning used to detect dirt on each protective glass 21A, 21B by recording in memory 32 the detection results of the dirt type in correspondence with the temperature data and scattered light intensity at the time of dirt detection.

[0060] Next, the temperature data obtained by the temperature sensors 22A and 22B will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of temperature graphs f1 and f2 obtained by the temperature sensors 22A and 22B. It goes without saying that the temperature graphs f1 and f2 shown in Fig. 6 are merely examples and are not limited thereto.

[0061] 6 are graphs showing changes in temperature data obtained by temperature sensors 22A and 22B, with the horizontal axis showing the degree of dirt on protective glasses 21A and 21B and the vertical axis showing the temperature rise of protective glasses 21A and 21B. Temperature graph f1 shows the relationship between the degree of dirt on protective glasses 21A and 21B and the temperature rise when the dirt on protective glasses 21A and 21B is of the dirt type "dirt particles: large". Temperature graph f2 shows the relationship between the degree of dirt on protective glasses 21A and 21B and the temperature rise when the dirt on protective glasses 21A and 21B is of the dirt type "dirt particles: small".

[0062] Here, dirt particles have the property of absorbing light. Therefore, the temperature graph f1 when the dirt particles are large is more likely to absorb light than the temperature graph f2 when the dirt particles are small, and the temperature rise relative to the degree of dirt is greater. Therefore, when the dirt particles are large, the dirt generates heat by absorbing the laser light when the laser light is irradiated, which can cause a sudden rise in temperature, and it is therefore necessary to detect dirt at a stage when the degree of dirt is low.

[0063] Next, the scattered light intensity data obtained by the scattered light sensors 23A-23C will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example of scattered light intensity graphs g1, g2 acquired by the scattered light sensors 23A-23C. It goes without saying that the scattered light intensity graphs g1, g2 shown in Fig. 7 are merely examples and are not limiting.

[0064] 7 are graphs showing changes in scattered light intensity data obtained by scattered light sensors 23A-23C, with the horizontal axis showing the degree of dirt on protective glasses 21A, 21B and the vertical axis showing scattered light intensity. Scattered light intensity graph g1 shows the relationship between the degree of dirt on protective glasses 21A, 21B and scattered light intensity when the dirt on protective glasses 21A, 21B is of the dirt type "dirt particles: large". Scattered light intensity graph g2 shows the relationship between the degree of dirt on protective glasses 21A, 21B and scattered light intensity when the dirt on protective glasses 21A, 21B is of the dirt type "dirt particles: small".

[0065] Here, the smaller the dirt particles are, the stronger the intensity of the diffracted scattered light becomes, and the wider the area in which the diffracted scattered light is distributed. Therefore, when the dirt particles are small, the dirt diffracts and scatters the scattered light with stronger intensity and over a wider range, so the scattered light intensity graph g1 obtained relative to the degree of dirt is greater than that of the scattered light intensity graph g2 when the dirt particles are large.

[0066] Next, the dirt determination value P will be described with reference to Fig. 8. Fig. 8 is a diagram showing an example of dirt detection graphs P1 and P2. Note that the dirt detection graphs P1 and P2 shown in Fig. 8 are merely examples, and needless to say, the invention is not limited to these.

[0067] 8 are graphs showing changes in the dirt determination value P, with the horizontal axis showing the dirt degree of protective glasses 21A, 21B and the vertical axis showing the dirt determination value P. Dirt detection graph P1 shows the relationship between the dirt degree of protective glasses 21A, 21B and the dirt determination value P when the dirt on protective glasses 21A, 21B is of the dirt type "dirt particles: large". Scattered light intensity graph g2 shows the relationship between the dirt degree of protective glasses 21A, 21B and the dirt determination value P when the dirt on protective glasses 21A, 21B is of the dirt type "dirt particles: small".

[0068] Here, the dirt determination value P is calculated based on the sum of the variables of temperature and scattered light intensity. Therefore, as shown in Fig. 8, the dirt detection graphs P1 and P2 output the dirt determination value P for the dirt level in the same way regardless of whether the dirt on the protective glasses 21A and 21B is of the dirt type "dirt particles: large" or "dirt particles: small."

[0069] This allows the head control unit HC to detect dirt on the protective glasses 21A, 21B regardless of whether the dirt type is “dirt particles: large” or “dirt particles: small.” Furthermore, even if the dirt particles are small and the temperature rise inside the laser head LH is small, the head control unit HC can detect dirt on the protective glasses 21A, 21B at an earlier stage and more effectively prevent damage to the protective glasses 21A, 21B or the inside of the laser head LH.

[0070] As described above, the head control unit HC (an example of a calculation device) in the embodiment acquires temperature data output from at least one temperature sensor 22A-22B that measures the temperature of the protective glasses 21A, 21B provided in the laser head LH, and scattered light intensity data output from at least one scattered light sensor 23A-23C that measures the intensity of scattered light scattered by the protective glasses 21A, 21B, calculates a dirt determination value P (an example of a score) that evaluates the degree of dirt on the protective glasses 21A, 21B based on the temperature data and the scattered light intensity data, and if it determines that dirt on the protective glasses 21A, 21B has been detected based on the dirt determination value P, outputs a notification that dirt on the protective glasses 21A, 21B has been detected.

[0071] As a result, the head control unit HC in the embodiment can detect dirt on the protective glasses 21A and 21B with higher accuracy by using the temperature data and the scattered light intensity data. Also, the head control unit HC can detect dirt on each of the protective glasses 21A and 21B regardless of the type of dirt on each of the protective glasses 21A and 21B by using the temperature data and the scattered light intensity data, and can more effectively suppress damage to the inside of the laser head LH based on the temperature inside the laser head LH and welding defects or deterioration of welding quality due to the dirt on each of the protective glasses 21A and 21B.

[0072] Furthermore, the head control unit HC in the embodiment outputs a notification when it determines that the dirt determination value P is equal to or greater than the threshold value K_sh (an example of a predetermined value). As a result, the head control unit HC in the embodiment can detect dirt on each of the protective glasses 21A, 21B regardless of the type of dirt on each of the protective glasses 21A, 21B by using the temperature data and the scattered light intensity data, and can more effectively suppress damage to the inside of the laser head LH based on the temperature inside the laser head LH and welding defects or deterioration of welding quality due to the dirt on each of the protective glasses 21A, 21B.

[0073] Furthermore, the head control unit HC in the embodiment determines whether the temperature of the protective glasses 21A, 21B is equal to or higher than a threshold value T_a° C. (one example of a predetermined temperature) based on the temperature data, and corrects the temperature characteristics of the scattered light sensors 23A-23C if it determines that the temperature of the protective glasses 21A, 21B is equal to or higher than the threshold value T_a° C. In this way, the head control unit HC in the embodiment can improve the measurement accuracy of the scattered light intensity by the scattered light sensors 23A-23C by correcting the temperature characteristics of the temperature sensors based on the temperature data obtained by the multiple temperature sensors 22A-22B.

[0074] Furthermore, when the head control unit HC in the embodiment determines that the temperature of the protective glasses 21A, 21B is equal to or higher than the threshold value T_a° C., it corrects the temperature characteristics of the scattered light sensors 23A-23C corresponding to the temperature sensors 22A-22B that measured a temperature equal to or higher than the threshold value T_a° C. In this way, the head control unit HC in the embodiment can improve the measurement accuracy of the scattered light intensity by the scattered light sensors 23A-23C by correcting the temperature characteristics of each of the scattered light sensors 23A-23C provided at positions corresponding to the temperature sensors based on the temperature data obtained by the multiple temperature sensors 22A-22B.

[0075] Furthermore, when the head control unit HC in the embodiment determines that the temperature of the protective glasses 21A, 21B is equal to or higher than the threshold value T_a° C., it corrects the temperature characteristics of all the scattered light sensors 23A-23C. In this way, the head control unit HC in the embodiment can improve the measurement accuracy of the scattered light intensity by the scattered light sensors 23A-23C by correcting the temperature characteristics of all the scattered light sensors 23A-23C based on the temperature data obtained by the multiple temperature sensors 22A-22B.

[0076] Furthermore, the dirt determination value P of the head control unit HC in the embodiment is calculated by adding the temperature rise value f (an example of a temperature score) based on the temperature data and the scattered light intensity g (an example of a scattered light intensity score) based on the scattered light intensity data. As a result, the head control unit HC in the embodiment can detect dirt on each of the protective glasses 21A, 21B regardless of the type of dirt on each of the protective glasses 21A, 21B by using the temperature data and the scattered light intensity data, and can more effectively suppress damage to the inside of the laser head LH based on the temperature inside the laser head LH and welding defects or deterioration of welding quality due to the dirt on each of the protective glasses 21A, 21B.

[0077] Furthermore, when the head control unit HC in the embodiment detects dirt on the protective glasses 21A, 21B, it determines the type of dirt based on the ratio between the temperature data and the scattered light intensity data (i.e., the judgment value Q) and outputs the judgment result of the type of dirt. In this way, the head control unit HC in the embodiment can detect the type of dirt on each of the protective glasses 21A, 21B by using the temperature data and the scattered light intensity data.

[0078] Furthermore, if the head control unit HC in the embodiment determines that the ratio between the temperature data and the scattered light intensity data (i.e., the judgment value Q) is 1 or greater, it outputs a judgment result that the dirt particles are large, and if it determines that the ratio between the temperature data and the scattered light intensity data (i.e., the judgment value Q) is not 1 or greater, it outputs a judgment result that the dirt particles are small. In this way, the head control unit HC in the embodiment can detect and notify the type of dirt on each of the protective glasses 21A, 21B by using the temperature data and the scattered light intensity data.

[0079] Furthermore, the multiple temperature sensors 22A-22B in the head control unit HC in the embodiment are disposed at equal intervals on a first concentric circle based on the center position 21AA (an example of the center position) of the protective glasses 21A, 21B. The multiple scattered light sensors 23A-23C are disposed at equal intervals on a second concentric circle based on the center position 21AA (an example of the center position) of the protective glasses 21A, 21B. This allows the head control unit HC in the embodiment to detect dirt on each of the protective glasses 21A, 21B even when there is a temperature change in the protective glasses 21A, 21B or when the scattered light is partially diffused by the protective glasses 21A, 21B, and more effectively prevents damage to the inside of the laser head LH based on the temperature inside the laser head LH and welding defects or deterioration of welding quality due to dirt on each of the protective glasses 21A, 21B.

[0080] As described above, the head control unit HC (an example of a protective glass dirt detection device) in the embodiment includes a communication unit 30 (an example of an acquisition unit) that acquires temperature data output from at least one temperature sensor 22A-22B that measures the temperature of the protective glasses 21A, 21B provided in the laser head LH, and scattered light intensity data output from at least one scattered light sensor 23A-23C that measures the intensity of scattered light scattered by the protective glass, a processor 31 (an example of a calculation unit) that calculates a dirt judgment value P (an example of a score) that evaluates the degree of dirt on the protective glass based on the temperature data and the scattered light intensity data, and a processor 31 (an example of an output unit) that outputs a notification that dirt on the protective glass 21A, 21B has been detected when it is determined that dirt on the protective glass 21A, 21B has been detected based on the dirt judgment value P.

[0081] As a result, the head control unit HC in the embodiment can detect dirt on the protective glasses 21A and 21B with higher accuracy by using the temperature data and the scattered light intensity data. Also, the head control unit HC can detect dirt on each of the protective glasses 21A and 21B regardless of the type of dirt on each of the protective glasses 21A and 21B by using the temperature data and the scattered light intensity data, and can more effectively suppress damage to the inside of the laser head LH based on the temperature inside the laser head LH and welding defects or deterioration of welding quality due to the dirt on each of the protective glasses 21A and 21B.

[0082] 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]

[0083] The present disclosure is useful as a method and device for detecting dirt on a protective glass that detects dirt on a protective glass provided in a laser head with higher accuracy. [Explanation of symbols]

[0084] 10 Fiber 11 Collimation lens 12 Focus Lens 21 Protective Glass Unit 21A, 21B Protective glass 22A, 22B Temperature Sensor 23A, 23B, 23C Scattered Light Sensor 30 Communications Department 31 Processors 31A Arithmetic unit 31B Processing section 31C Judgment section 32 Memory 33 Output section 100 Laser Head System HC Head Control Unit LH laser head

Claims

1. A method for detecting dirt on a protective glass performed by a computing device, comprising: Acquiring temperature data output from at least one temperature sensor that measures the temperature of a protective glass provided in the laser head, and scattered light intensity data output from at least one scattered light sensor that measures the intensity of scattered light scattered by the protective glass; calculating a score for evaluating a degree of contamination of the protective glass based on the temperature data and the scattered light intensity data; when it is determined based on the score that dirt on the protective glass has been detected, a notification that dirt on the protective glass has been detected is output. A method for detecting dirt on protective glass.

2. When it is determined that the score is equal to or greater than a predetermined value, the notification is output. A method for detecting dirt on a protective glass according to claim 1.

3. determining whether the temperature of the protective glass is equal to or higher than a predetermined temperature based on the temperature data; when it is determined that the temperature of the protective glass is equal to or higher than the predetermined temperature, the temperature characteristics of the scattered light sensor are corrected. A method for detecting dirt on a protective glass according to claim 1.

4. when it is determined that the temperature of the protective glass is equal to or higher than the predetermined temperature, correcting the temperature characteristics of the scattered light sensor corresponding to the temperature sensor that measured a temperature equal to or higher than the predetermined temperature. The method for detecting dirt on a protective glass according to claim 3.

5. when it is determined that the temperature of the protective glass is equal to or higher than the predetermined temperature, the temperature characteristics of all of the scattered light sensors are corrected. The method for detecting dirt on a protective glass according to claim 3.

6. The score is calculated by adding a temperature score based on the temperature data and a scattered light intensity score based on the scattered light intensity data. A method for detecting dirt on a protective glass according to claim 1.

7. if dirt on the protective glass is detected, determining a type of the dirt based on a ratio between the temperature data and the scattered light intensity data, and outputting a determination result of the type of the dirt. A method for detecting dirt on a protective glass according to claim 1.

8. outputting a determination result indicating that the dirt particles are large when it is determined that the ratio between the temperature data and the scattered light intensity data is equal to or greater than 1; when it is determined that the ratio between the temperature data and the scattered light intensity data is not equal to or greater than 1, a determination result indicating that the dirt particles are small is output. The method for detecting dirt on a protective glass according to claim 7.

9. The temperature sensors are arranged at equal intervals on a first concentric circle based on a center of the protective glass, the plurality of scattered light sensors are disposed at equal intervals on a second concentric circle based on the center of the protective glass; A method for detecting dirt on a protective glass according to claim 1.

10. an acquisition unit that acquires temperature data output from at least one temperature sensor that measures the temperature of a protective glass provided in the laser head and scattered light intensity data output from at least one scattered light sensor that measures the intensity of scattered light scattered by the protective glass; a calculation unit that calculates a score for evaluating a degree of contamination of the protective glass based on the temperature data and the scattered light intensity data; and an output unit that outputs a notification that dirt on the protective glass has been detected when it is determined that dirt on the protective glass has been detected based on the score. A device for detecting dirt on protective glass.

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