Welding state detection method and welding device

Abstract

The present invention relates to a method and a welding device for detecting a welding state, which have the following functions: detecting in real time the occurrence of a depression caused by the scattering of molten metal during laser welding, estimating the amount of the depression, and judging whether it can be repaired by remelting. The welding state detection method of the embodiment includes: a step of detecting reflected light from a portion irradiated with laser light and luminescence of the portion irradiated with the laser light; and a step of detecting the welding state of the portion irradiated with the laser light based on the detected reflected light and the detected luminescence. In the step of detecting the welding state, it is detected whether the signal level of the luminescence becomes greater than a predetermined first threshold value and the signal level of the reflected light becomes less than a predetermined second threshold value.

Description

Technical Field

[0001] Embodiments of the present invention relate to a method for detecting a welding state and a welding device. Background Art

[0002] There is a welding device that performs welding by irradiating a laser beam to an object. In such a welding device, when the laser beam is irradiated to the object, welding defects may occur due to the material of the object.

[0003] Welding defects include, for example, depressions in the welded part caused by the scattering of molten metal during laser welding. When depressions occur, not only does it damage the appearance, but it may also cause insufficient strength of the joint or leakage in the case of sealed welding. In the case of depressions, depending on the degree of the depression, sometimes it becomes a defective product, but if the target part is melted again by re-irradiating the depressed part with laser, thereby smoothing the surface, it can sometimes become a qualified product. Therefore, it is necessary to know the location and degree of the depression.

[0004] In this case, there is a method that detects the dent by visual or optical observation after the laser welding is completed, and irradiates the laser again after confirming its extent. However, this method has the problem of reduced production efficiency. In addition, a method is proposed to measure the light emitted from the laser irradiation part generated during welding in real time and detect the scattering of the weld metal based on its intensity, but the extent of the dent cannot be known. In addition, a method is proposed to detect the dent by measuring the reflected light from the laser irradiation part generated during welding in real time, but due to the influence of the surface shape of the object at the welding position, there are problems such as over-detection and omission.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-6036 Summary of the invention

[0006] The problem to be solved by the present invention is to provide a welding state detection method and a welding device, which have the following functions: real-time detection of the generation of depressions caused by the scattering of molten metal during laser welding, inference of the amount of depression, and judgment of whether repair can be performed by re-melting.

[0007] The welding state detection method of the embodiment includes: a step of detecting reflected light from a portion irradiated with laser light and luminescence of the portion irradiated with laser light; and a step of detecting the welding state of the portion irradiated with laser light based on the detected reflected light and the detected luminescence. In the step of detecting the welding state, it is detected whether the signal level of the luminescence is equal to or higher than a predetermined first threshold value and the signal level of the reflected light is equal to or lower than a predetermined second threshold value. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram for illustrating a welding device.

[0009] Figure 2 (a) to (c) are schematic cross-sectional views for illustrating the generation of recessed portions.

[0010] Figure 3 (a) is a graph for illustrating changes in the signal level from a sensor that detects visible light. Figure 3 (b) is a graph for illustrating changes in the signal level from the sensor that detects reflected light.

[0011] Figure 4 yes Figure 3 An enlarged view of part A in (b).

[0012] Figure 5 This is a graph for illustrating changes in the signal level of visible light corresponding to irradiation with one pulse of laser light.

[0013] Figure 6 (a) to (d) are schematic diagrams for illustrating determination of a concave portion.

[0014] Figure 7 This is a schematic perspective view for illustrating a film provided near a welding position of a workpiece.

[0015] Figure 8 It is a schematic top view for illustrating the welding position.

[0016] Fig. 9 This is a graph for illustrating changes in the signal level of visible light corresponding to irradiation with one pulse of laser light.

[0017] Fig.10 This is a graph for illustrating the spectrum of light corresponding to irradiation with one pulse of laser light.

[0018] Explanation of symbols

[0019] 1: welding device; 10: welding torch; 20: laser irradiation part; 20a: laser; 20b: reflected light; 20c: light emission; 20c1: light emission; 21: laser oscillator; 30: detection part; 31: sensor; 32a: sensor; 32b: sensor; 40: moving part; 50: controller; 100: workpiece; 100a: workpiece; 100b: workpiece; 101a: workpiece; 101b: workpiece; 101f1: recess. DETAILED DESCRIPTION

[0020] Hereinafter, the embodiments will be described with reference to the accompanying drawings. In addition, in each of the drawings, the same components are denoted by the same reference numerals and detailed descriptions thereof are appropriately omitted.

[0021] First, welding device 1 that can execute the welding state detection method according to the present embodiment will be described.

[0022] Figure 1 It is a schematic diagram for illustrating the welding device 1 .

[0023] The welding device 1 irradiates the workpiece 100 with a laser beam 20a to melt the portion of the workpiece 100 irradiated with the laser beam 20a to perform welding. Figure 1 As shown, the laser beam 20a can be irradiated to the connection part of the workpiece 100a and the workpiece 100b to perform welding. In addition, the method of welding is not particularly limited, and for example, it can be butt welding or fillet welding. Figure 1 The welding method exemplified in the example is butt welding.

[0024] The welding device 1 may include a welding torch 10 , a laser irradiation unit 20 , a detection unit 30 , a moving unit 40 , and a controller 50 .

[0025] The welding torch 10 includes, for example, a housing 11 , a lens 12 , a lens 13 , and a half mirror 14 .

[0026] The housing 11 is cylindrical and has a shape extending in one direction. The central axis of the housing 11 can be inclined relative to the surface of the workpiece 100 to be welded, or can be set to be approximately vertical. Figure 1 As shown, if the central axis of the housing 11 is substantially perpendicular to the surface of the workpiece 100 to be welded, the reflected light 20b of the laser 20a irradiated on the workpiece 100 and the luminous light 20c including visible light and infrared light generated in the portion irradiated by the laser 20a can be detected with high accuracy. In addition, if the laser 20a is irradiated from a direction substantially perpendicular to the surface of the workpiece 100 to be welded, the workpiece 100 can efficiently absorb the laser 20a.

[0027] The lens 12 can be provided inside the housing 11. The lens 12 can be provided at an end portion of the housing 11 on the opposite side to the workpiece 100 side. The lens 12 focuses the laser light 20a emitted from the laser irradiation unit 20.

[0028] The lens 13 can be disposed inside the housing 11. The lens 13 can be disposed at the end of the housing 11 on the workpiece 100 side. The lens 13 further focuses the laser light 20a focused by the lens 12 and irradiates the workpiece 100. When the laser light 20a is irradiated to the workpiece 100, a part of the irradiated laser light 20a is absorbed by the workpiece 100 and welding is performed.

[0029] In addition, part of the laser light 20a irradiated to the workpiece 100 is reflected and enters the lens 13. Therefore, the lens 13 can also focus the reflected light 20b from the workpiece 100. In addition, when the laser light 20a is irradiated, the part irradiated by the laser light 20a melts, generates high-temperature metal vapor 100d, and generates light 20c containing visible light, infrared light, etc. Part of the light 20c enters the lens 13. Therefore, the lens 13 can also focus the incident light 20c1 (part of the light 20c).

[0030] The half mirror 14 can be arranged inside the housing 11. The half mirror 14 can be arranged between the lens 12 and the lens 13. The half mirror 14 can be arranged to be inclined relative to the central axis of the housing 11. The half mirror 14 transmits the laser light 20a incident from the lens 12 side. The laser light 20a that has transmitted the half mirror 14 is incident on the lens 13. In addition, the half mirror 14 reflects the reflected light 20b and the light 20c1 incident from the lens 13 side. The half mirror 14 is inclined relative to the central axis of the housing 11, so that the reflected light 20b and the light 20c1 reflected by the half mirror 14 are emitted to the side of the housing 11.

[0031] The laser irradiation unit 20 includes, for example, a laser oscillator 21 , an irradiation head 22 , and a transmission unit 23 .

[0032] The laser oscillator 21 can be, for example, a YAG (Yttrium Aluminum Garnet) laser oscillator. In this case, the wavelength of the fundamental wave of the laser light 20a emitted from the laser oscillator 21 can be, for example, about 1064 nm.

[0033] In addition, the laser oscillator 21 can perform pulse oscillation of the laser 20a, that is, it can be a pulse laser oscillator. Regarding pulse oscillation, since the irradiation time of one pulse is short, even if the peak power is increased, the heat effect on the surrounding area of ​​the portion irradiated by the laser 20a can be reduced. In addition, since the peak power can be increased, it is beneficial to weld highly reflective materials such as aluminum and aluminum alloys. In this case, the welded portion 100c of the workpiece 100 can be in a spot shape (pulse spot welding), and it can also be as Figure 1 It becomes linear as shown (pulse seam welding).

[0034] The irradiation head 22 irradiates the lens 12 with the laser beam 20 a emitted from the laser oscillator 21 .

[0035] The transmission unit 23 is provided between the laser oscillator 21 and the irradiation head 22, and transmits the laser light 20a emitted from the laser oscillator 21 to the irradiation head 22. The transmission unit 23 can be, for example, an optical fiber or the like.

[0036] As described above, the laser irradiation unit 20 irradiates the workpiece 100 with the laser beam 20 a.

[0037] like Figure 1 As shown in FIG. 1 , the detection unit 30 detects the reflected light 20b and the light emission 20c1 emitted to the outside of the housing 11 via the half mirror 14. That is, the detection unit 30 detects the reflected light 20b from the portion irradiated by the laser 20a and the light emission 20c generated by the irradiation of the portion irradiated by the laser 20a. In this case, as described later, the welding state is detected based on the detection value of the reflected light 20b and the detection value of the light emission 20c1. Therefore, the detection unit 30 can include a sensor 31 for detecting the reflected light 20b and a sensor 32 for detecting the light emission 20c1.

[0038] As described above, the reflected light 20b is the reflected light of the laser light 20a, and therefore has the same wavelength as the laser light 20a. Therefore, the sensor 31 can detect light having the wavelength of the laser light 20a, for example, light having a wavelength of about 1064 nm.

[0039] As described above, the light emission 20c1 is light generated by the irradiation of the laser 20a, and therefore has a wide wavelength band including visible light, infrared light, etc. Therefore, as the sensor 32, at least one of the sensor 32a that can detect visible light and the sensor 32b that can detect infrared light can be provided. In addition, the visible light can be, for example, light having a wavelength in the range of 300nm to 800nm. The infrared light can be, for example, light having a wavelength in the range of 1100nm to 1600nm.

[0040] The moving part 40 moves the position of the workpiece 100 irradiated with the laser 20a. For example, the moving part 40 moves the relative position between the welding torch 10 and the workpiece 100. Figure 1 As shown in the example, when the moving part 40 moves the position of the workpiece 100, the moving part 40 can be a moving table that can carry the workpiece 100. The moving table can be, for example, a single-axis table with a servo motor, an XY table, etc. When the moving part 40 moves the position of the welding torch 10, the moving part 40 can be a multi-joint robot that can hold the welding torch 10. In addition, the moving part 40 can also move the position of the welding torch 10 and the position of the workpiece 100.

[0041] The controller 50 controls the operation of each element provided in the welding device 1. The controller 50 may include, for example, a computing element such as a CPU (Central Processing Unit) and a storage element such as a semiconductor memory. The controller 50 may be, for example, a computer. The storage element may store a control program for controlling the operation of each element provided in the welding device 1. The computing element controls the operation of each element provided in the welding device 1 using the control program stored in the storage element, data input by the operator, and the like.

[0042] In addition, the controller 50 detects the welding state based on the detection signal from the detection unit 30. The controller 50 detects the welding state of the portion irradiated with the laser 20a based on the detected reflected light 20b and the detected light emission 20c1 generated by the irradiation. For example, the computing element can detect the welding state based on the data such as the determination program and threshold value stored in the storage element and the detection signal from the detection unit 30.

[0043] In addition, the details regarding the detection of the welding state will be described later.

[0044] Next, the operation of the welding device 1 will be exemplified.

[0045] In addition, in the following, Figure 1 The butt welding between the workpieces 100a and 100b illustrated in FIG. 1 is described, but the same also applies to the fillet welding between the workpieces 101a and 101b.

[0046] First, the workpiece 100 a and the workpiece 100 b are placed on the moving unit 40 by a conveying device (not shown), an operator, or the like.

[0047] Next, the controller 50 controls the laser oscillator 21 so that the pulsed laser 20a repeatedly oscillates at a predetermined interval. The laser 20a emitted from the laser oscillator 21 is transmitted to the irradiation head 22 via the transmission unit 23, and irradiated from the irradiation head 22 toward the lens 12. The laser 20a incident on the lens 12 is focused by the lens 12, and is incident on the lens 13 after passing through the half mirror 14. The laser 20a incident on the lens 13 is focused by the lens 13, and irradiated to the connection portion (welding position) between the workpiece 100a and the workpiece 100b.

[0048] Furthermore, the controller 50 can control the moving unit 40 to move the relative position between the welding torch 10 and the workpiece 100 to perform the above-mentioned linear welding.

[0049] In addition, for example, in order to prevent the position of the workpiece 100b relative to the workpiece 100a from changing, the workpieces 100a and 100b may be spot welded before linear welding, and then linear welding may be performed. In this case, the pulsed laser 20a may be oscillated at the position where spot welding is performed, and the pulsed laser 20a may not be oscillated between the positions where spot welding is performed.

[0050] When the laser 20a is irradiated to the welding position, reflected light 20b and light 20c are generated. The light 20c includes visible light and infrared light, but the visible light is mainly generated in the metal vapor. Therefore, the visible light is sometimes also called plasma light. The infrared light is mainly generated in the molten pool 101d. The molten pool 101d will be described later. Figure 2 is described in.

[0051] The reflected light 20b and the light emission 20c1 (part of the light emission 20c) enter the detection unit 30 via the lens 13 and the half mirror 14. The detection unit 30 receives a detection signal based on the reflected light 20b and a detection signal based on the light emission 20c1.

[0052] The controller 50 can detect the welding state based on the detection signal based on the reflected light 20 b and the detection signal based on the light emission 20 c 1 .

[0053] In addition, the controller 50 can determine whether the welding state is good based on the detection result of the welding state. Based on the determination result, the controller 50 can repair the defective part, display the information of the defective part (for example, the size and position of the recess 101f1 described later) on the display device, or send the information of the defective part to an external device.

[0054] After a series of operations are completed, the workpieces 100 (the workpieces 100a and 100b) are carried out to the outside of the welding apparatus 1 by a conveyor device (not shown), an operator, etc.

[0055] Next, the welding state detection method according to the present embodiment will be further described.

[0056] First, a defect occurring in a portion irradiated with laser light 20 a will be described.

[0057] Figure 2 (a) to (c) are schematic cross-sectional views for illustrating the generation of the concave portion 101f1.

[0058] In addition, Figure 2 In (a) to (c) of FIG. 1 , fillet welding of workpiece 101a and workpiece 101b is described, but in Figure 1 The same also applies to the butt welding of the workpieces 100a and 100b illustrated in FIG.

[0059] like Figure 2 As shown in (a), sometimes there is a heterogeneous part 101a1 inside the workpiece 101a. For example, when the workpiece 101a is a cast material such as aluminum or magnesium, it often contains inclusions with a low boiling point, resins that are easily vaporized at low temperatures, etc. Figure 2 As shown in (b), when the molten pool 101d reaches the portion 101a1, the portion 101a1 expands all at once. The molten pool 101d is formed by molten metal. Therefore, when the portion 101a1 expands, Figure 2 As shown in (c), the molten metal 101g is splashed. When the molten metal 101g is splashed, a concave portion 101f1 is generated in the welded portion 101f. When the concave portion 101f1 is generated, the appearance is deteriorated, and thus the product value is reduced. In addition, depending on the use of the welded workpiece (for example, when applied to a sealed container), the concave portion 101f1 becomes a major cause of liquid or gas leakage.

[0060] Therefore, in the welding state detection method of the present embodiment, the generation of the recessed portion 101f1 is detected, and information such as the size and shape of the generated recessed portion 101f1 is acquired.

[0061] First, detection of the occurrence of the recess 101f1 will be described.

[0062] When recess 101f1 is generated, regular reflection of laser light 20a is prevented, so the signal level from sensor 31 detecting reflected light 20b decreases. Therefore, if the signal level from sensor 31 is monitored using a predetermined threshold value, the generation of recess 101f1 can be detected.

[0063] When the molten metal 101g is scattered, the intensity of the visible light and the infrared light increases sharply. For example, if at least one of the signal level from the sensor 32a for detecting visible light and the signal level from the sensor 32b for detecting infrared light is monitored using a predetermined threshold value, the generation of the concave portion 101f1 can be detected.

[0064] Here, the signal level from the sensor 31 detecting the reflected light 20b is affected by the surface state of the workpiece before welding, etc. For example, when a recessed portion already exists on the surface of the workpiece before welding, the signal level from the sensor 31 decreases.

[0065] In this case, the signal level from the sensor 32a detecting visible light and the signal level from the sensor 32b detecting infrared light are less likely to be affected by the surface state of the workpiece before welding, etc. Therefore, the signal level from the sensor 32a and the signal level from the sensor 32b are useful for detecting the generation of the recess 101f1.

[0066] Therefore, in the welding state detection method of the present embodiment, at least any one of the signal level from the sensor 32a for detecting visible light and the signal level from the sensor 32b for detecting infrared light, and the signal level from the sensor 31 for detecting the reflected light 20b are used to detect the generation of the recess 101f1 caused by the scattering of the molten metal 101g.

[0067] Figure 3 (a) is a graph for illustrating changes in the signal level from the sensor 32a that detects visible light.

[0068] In addition, Figure 3 In (a), as an example, the change in the signal level from the sensor 32a is used, but the visible light and the infrared light are also emitted due to the irradiation of the laser 20a, so the signal level from the sensor 32b that detects the infrared light also changes in the same way. Therefore, the change in the signal level from the sensor 32b can also be used. In addition, the signal level from the sensor 32a and the signal level from the sensor 32b can also be used. That is, as long as the change in the intensity of the light 20c generated by the irradiation of the laser 20a can be known.

[0069] Figure 3 (b) is a graph for illustrating changes in the signal level from the sensor 31 that detects the reflected light 20b.

[0070] As described above, in order to perform linear welding, the pulsed laser 20a is repeatedly oscillated. In addition, with respect to the irradiation of one pulse of the laser 20a, the reflected light 20b and the light emission 20c generated by the irradiation are generated almost simultaneously. However, if the molten metal 101g is scattered, the intensity of the light emission 20c generated by the irradiation immediately increases, but since the recess 101f1 is formed after the molten metal 101g is scattered, the signal level of the reflected light 20b decreases with a slight delay. For example, a certain time can be used. Figure 3 The signal level of (a) and the time slightly delayed from it Figure 3 The generation of the recess 101f1 is detected by measuring the signal level of (b).

[0071] The generation of the concave portion 101f1 can be detected by using at least one of the increase in the signal level from the sensor 32a detecting visible light and the increase in the signal level from the sensor 32b detecting infrared light. However, if the decrease in the signal level from the sensor 31 detecting the reflected light 20b is used at the same time, the detection accuracy can be further improved.

[0072] Next, information such as the size and shape of the generated concave portion 101f1 will be described.

[0073] Figure 4 yes Figure 3 An enlarged view of part A in (b).

[0074] As described above, the signal level from the sensor 31 that detects the reflected light 20 b is affected by the size and shape of the recess 101 f 1 , etc. Therefore, the signal from the sensor 31 includes information such as the size and shape of the recess 101 f 1 .

[0075] like Figure 4 As shown, the time T1 when the signal level of the reflected light 20b becomes less than the predetermined threshold value S can be obtained, and the approximate value of the length (opening size) of the recess 101f1 can be obtained from the product of the time T1 and the moving speed of the moving unit 40. In addition, since there is a correlation between the signal level and the reflection position, the approximate value of the depth D of the recess 101f1 can be obtained from the difference between the predetermined threshold value S and the minimum value of the signal level.

[0076] In addition, the threshold S and the correlation between the signal level and the reflection position can be obtained in advance by performing experiments or simulations. In addition, the average value of the signal level during a predetermined period can be successively obtained, and the obtained average value can be used as the threshold S. In this way, the average value of the signal level around the concave portion 101f1 can be used as the threshold S, so the calculation accuracy of the length and depth D of the concave portion 101f1 can be improved.

[0077] As described above, by using the signal level from the sensor 31 that detects the reflected light 20 b , it is possible to obtain information such as the size and shape of the recess 101 f 1 .

[0078] Figure 5 This is a graph for illustrating changes in the signal level of visible light corresponding to irradiation with one pulse of the laser light 20 a .

[0079] As described above, since visible light and infrared light are generated by irradiation with the laser beam 20 a , the signal level of the infrared light also changes in the same manner. Therefore, the change in the signal level of the infrared light can also be used.

[0080] also, Figure 5 The waveform 203 in FIG. 1 is a case where the concave portion 101f1 is not generated, and the waveform 204 is a case where the concave portion 101f1 is generated.

[0081] The difference B between the integral value of the waveform 204 and the integral value of the waveform 203 is correlated with the volume of the scattered molten metal. Based on the difference B in the integral value and the correlation between the volume of the scattered molten metal and the difference in the integral value, the approximate value of the size (volume) of the recess 101f1 can be obtained. In addition, the correlation between the volume of the scattered molten metal and the difference in the integral value can be obtained by performing experiments or simulations in advance.

[0082] In addition, the moment when the signal level starts to increase is considered to be the time when the molten metal scatters. If the time T2 between the time when the signal input starts and the time when the signal level starts to increase is obtained, the approximate value of the depth at the time when the molten metal scatters can be obtained. In this case, if the time T2 is short, it can be considered that the depth at the time when the molten metal scatters is shallow, and a shallow recess 101f1 is generated. If the time T2 is long, it can be considered that the depth at the time when the molten metal scatters is deep, and a deep recess 101f1 is generated. The correlation between the time T2 and the depth can be obtained in advance by performing experiments and simulations.

[0083] As described above, by using at least one of the signal level from the sensor 32 a that detects visible light and the signal level from the sensor 32 b that detects infrared light, information such as the size and shape of the recess 101 f 1 can be obtained.

[0084] Figure 6 (a) to (d) are schematic diagrams for illustrating determination of the recessed portion 101f1.

[0085] For example, the greater the amount of scattered matter 205, the deeper the depth to the scattered matter generation position 206. Figure 6 As shown in (a), a larger recess 101f1 is produced.

[0086] For example, even if the amount of scattered matter 205 is large, if the depth to the location 206 where the scattered matter is generated is shallow, it can be considered that Figure 6 As shown in (b), a smaller recess 101f1 is produced.

[0087] For example, even if the depth to the scattering generation position 206 is deep, if the amount of the scattering 205 is small, it can be considered that Figure 6 As shown in (c), a smaller recess 101f1 is produced.

[0088] When the amount 205 of the scattered matter and the location 206 where the scattered matter is generated are taken into consideration, for example, Figure 6 The recess 101f1 is determined as shown in (d).

[0089] For example, in Figure 6In the region C1 of (d), it is considered that the size of the recessed portion 101f1 generated is small, and therefore it can be determined as a non-defective product.

[0090] For example, in Figure 6 In the region C2 of (d), the size of the recessed portion 101f1 generated can be determined to be a size that can be repaired by re-melting.

[0091] For example, in Figure 6 In the region C3 of (d), it can be determined that the size of the recessed portion 101f1 generated is such that it cannot be repaired by re-melting.

[0092] Here, the workpiece is made of a metal such as aluminum or copper, but a component made of a material different from that of the workpiece is sometimes provided near the welding position of the workpiece. For example, a film containing a metal different from that of the workpiece, an organic material such as a resin, or an inorganic material such as a ceramic is sometimes formed near the welding position of the workpiece.

[0093] Figure 7 This is a schematic perspective view for illustrating a film provided near a welding position of a workpiece.

[0094] Figure 7 This is a case where a plate-shaped workpiece 102a and a plate-shaped workpiece 102b are welded by laser welding. In this case, the workpiece 102a and the workpiece 102b are made of, for example, aluminum, copper, or the like.

[0095] Furthermore, a film 103 is formed on the main surface of the workpiece 102a where the recessed portion 102a1 opens. The film 103 can be a coating film made of a material different from that of the workpiece, for example, a resin.

[0096] Figure 8 It is a schematic plan view for illustrating the welding position 102b1.

[0097] Figure 8 This is the case where the above-mentioned spot welding is performed.

[0098] like Figure 8 As shown, welding is performed along the boundary between the workpiece 102a and the workpiece 102b. In this case, the welding position 102b1 is a position where the film 103 is not irradiated with the laser beam 20a.

[0099] However, when the width of the workpiece 102a is small, the laser light 20a may irradiate the film 103. When the laser light 20a irradiates the film 103, the film 103 may be damaged, and the commercial value of the product may be greatly reduced.

[0100] Fig. 9This is a graph for illustrating changes in the signal level of visible light corresponding to irradiation with one pulse of the laser light 20 a .

[0101] Fig. 9 The waveform 102ba in FIG. 1 is a case where only the workpieces 102a and 102b made of aluminum alloy are irradiated with the laser beam 20a.

[0102] Fig. 9 The waveform 103a in FIG. 1 is a case where only the film 103 including resin is irradiated with the laser beam 20a.

[0103] As per Fig. 9 As can be seen, when the laser 20a irradiates the film 103, for example, the peak level of the visible light increases significantly. Therefore, for example, if the signal level from the sensor 32a for detecting visible light is monitored using a predetermined threshold value, it can be known that the laser 20a irradiates an unintended component such as the film 103.

[0104] In this case, for example, the fact that the laser 20a irradiates unintended components such as the film 103 can be displayed on the display device together with the determination result of the welding state. In addition, the position information of the unintended irradiated portion can be displayed on the display device or transmitted to an external device.

[0105] In addition, as an example, the case of using visible light is illustrated, but in the case of infrared light and reflected light 20b, the signal level also changes depending on the material. Therefore, it is sufficient to monitor the signal level from at least one of the sensor 31 detecting reflected light 20b, the sensor 32a detecting visible light, and the sensor 32b detecting infrared light using a predetermined threshold value or the like.

[0106] Fig.10 This is a graph for illustrating the spectrum of the light emission 20c1 corresponding to the irradiation of one pulse of the laser beam 20a.

[0107] The light emission 20c1 is light generated in association with the irradiation of the laser beam 20a, and therefore has a wide wavelength band including visible light, infrared light, and the like.

[0108] Fig.10 The waveform 102bb in FIG. 1 is a case where only the workpieces 102a and 102b made of aluminum alloy are irradiated with the laser beam 20a.

[0109] Fig.10 The waveform 103b in FIG. 1 is a case where only the film 103 including resin is irradiated with the laser beam 20a.

[0110] As per Fig.10As can be seen, the laser light 20a produces different spectra when irradiating the workpieces 102a and 102b and when irradiating the film 103. In this case, the difference in the spectra can be detected by using a spectrometer or the like, and thus it can be detected that the laser light 20a irradiates an unintended component such as the film 103. However, in this case, the structure of the welding device 1 becomes complicated.

[0111] Therefore, in the welding device 1 of this embodiment, by monitoring the signal level from at least one of the sensor 32a for detecting visible light and the sensor 32b for detecting infrared light using a predetermined threshold or the like, it is possible to detect that the laser light 20a has irradiated an unintended member such as the film 103.

[0112] For example, Fig.10 As shown, it is sufficient to monitor the signal level from at least one of the sensor 32a that detects visible light with a wavelength of 450 nm and the sensor 32b that detects infrared light with a wavelength of 730 nm using a predetermined threshold value or the like.

[0113] In this case, for example, the fact that the laser 20a irradiates unintended components such as the film 103 can be displayed on the display device together with the determination result of the welding state. In addition, the position information of the unintended irradiated portion can be displayed on the display device or transmitted to an external device.

[0114] As described above, the welding state detection method of this embodiment can include the following steps. In addition, the content in each step can be the same as the above content, so the detailed description is omitted. In addition, the following first to fourth thresholds can be appropriately determined in advance by performing experiments and simulations.

[0115] A step of detecting reflected light 20b from a portion irradiated with laser light 20a and emitted light 20c from a portion irradiated with laser light 20a.

[0116] A step of detecting the welding state of the portion irradiated with the laser light 20a based on the detected reflected light 20b and the detected light emission 20c.

[0117] In the step of detecting the welding state, it is detected whether the signal level of the light emission 20 c is equal to or higher than a predetermined first threshold value and the signal level of the reflected light 20 b is equal to or lower than a predetermined second threshold value.

[0118] In the welding state detection step, when the signal level of light emission 20c is equal to or higher than a predetermined first threshold and the signal level of reflected light 20b is equal to or lower than a predetermined second threshold, it is determined that recess 101f1 has occurred in the portion irradiated with laser light 20a.

[0119] In the step of detecting the welding state, the length of the recess 101f1 is calculated based on the product of the time T1 when the signal level of the reflected light 20b becomes equal to or lower than the second threshold value and the moving speed of the portion irradiated with the laser light 20a.

[0120] In the step of detecting the welding state, the depth of the recess 101f1 is calculated based on the difference between the second threshold value and the minimum value of the signal level.

[0121] In the step of detecting the welding state, the size of the recess 101f1 is calculated based on the difference between the integrated value of the signal level of the light emission 20c when the recess 101f1 is not generated and the integrated value of the signal level of the light emission 20c when the recess 101f1 is generated, which is obtained in advance.

[0122] In the step of detecting the welding state, the depth of the recess 101f1 is calculated based on the time T2 between the input start time of the signal of the light emitting 20c and the time when the signal level starts to increase.

[0123] In the step of detecting the welding state, when the signal level of the reflected light 20 b becomes equal to or higher than a predetermined third threshold value, it is determined that the laser light 20 a is irradiated onto an unintended portion.

[0124] In the step of detecting the welding state, when the signal level of the light emission 20 c becomes equal to or higher than a predetermined fourth threshold value, it is determined that the laser beam 20 a is irradiated onto an unintended portion.

[0125] Furthermore, the welding state detection method described above can be performed in the welding device 1 described above.

[0126] For example, the controller 50 detects whether the signal level of the light emission 20 c 1 is equal to or higher than a predetermined first threshold value and the signal level of the reflected light 20 b is equal to or lower than a predetermined second threshold value.

[0127] When the signal level of the light emission 20c1 is equal to or higher than a predetermined first threshold and the signal level of the reflected light 20b is equal to or lower than a predetermined second threshold, the controller 50 determines that the recess 101f1 is generated in the portion irradiated with the laser beam 20a.

[0128] The controller 50 calculates the length of the recess 101f1 based on the product of the time T1 when the signal level of the reflected light 20b becomes equal to or lower than the second threshold value and the moving speed of the portion irradiated with the laser beam.

[0129] The controller 50 calculates the depth of the concave portion 101f1 based on the difference between the second threshold value and the minimum value of the signal level.

[0130] The controller 50 calculates the size of the recess 101f1 based on the difference between the integrated value of the signal level of the light emission 20c1 when the recess 101f1 is not generated and the integrated value of the signal level of the light emission 20c1 when the recess 101f1 is generated, which is obtained in advance.

[0131] The controller 50 calculates the depth of the recess 101f1 based on a time T2 between the time when the input of the signal of the light emission 20c1 starts and the time when the signal level starts to increase.

[0132] When the signal level of the reflected light 20 b becomes equal to or higher than a predetermined third threshold value, the controller 50 determines that the laser light 20 a is irradiated onto an unintended portion.

[0133] When the signal level of the light emission 20c1 becomes equal to or higher than a predetermined fourth threshold value, the controller 50 determines that the laser beam 20a is irradiated onto an unintended portion.

[0134] Several embodiments of the present invention have been described above, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the main purpose of the invention. These embodiments and their variations are included in the scope and main purpose of the invention, and are included in the invention described in the scope of the patent claim and the scope equivalent thereto. In addition, the above-mentioned embodiments can be implemented in combination with each other.

Claims

1. A method for detecting a welding state, comprising: The step of detecting reflected light from the portion irradiated with the laser and luminescence of the portion irradiated with the laser; as well as a step of detecting a welding state of a portion irradiated with the laser light based on the detected reflected light and the detected luminescence, In the step of detecting the welding state, it is detected whether the signal level of the light emission is equal to or higher than a first predetermined threshold value and the signal level of the reflected light is equal to or lower than a second predetermined threshold value. In the step of detecting the welding state, when the signal level of the light emission becomes equal to or higher than a predetermined first threshold value and the signal level of the reflected light becomes equal to or lower than a predetermined second threshold value, it is determined that a recess is generated in the portion irradiated with the laser light. In the step of detecting the welding state, the length of the recessed portion is calculated based on the product of the time during which the signal level of the reflected light becomes equal to or lower than the second threshold value and the moving speed of the portion irradiated with the laser beam.

2. The method for detecting welding status according to claim 1, wherein: In the step of detecting the welding state, the depth of the recessed portion is calculated based on the difference between the second threshold value and the minimum value of the signal level.

3. The method for detecting welding status according to claim 1, wherein: In the step of detecting the welding state, the size of the recess is calculated based on the difference between the integrated value of the light emission signal level when the recess is not generated and the integrated value of the light emission signal level when the recess is generated.

4. The method for detecting welding status according to claim 2, wherein: In the step of detecting the welding state, the size of the recess is calculated based on the difference between the integrated value of the light emission signal level when the recess is not generated and the integrated value of the light emission signal level when the recess is generated.

5. The method for detecting welding status according to claim 1, wherein: In the step of detecting the welding state, the depth of the recessed portion is calculated based on a time period between a time when the light emission signal starts to be input and a time when the signal level starts to increase.

6. The method for detecting welding status according to claim 2, wherein: In the step of detecting the welding state, the depth of the recessed portion is calculated based on a time period between a time when the light emission signal starts to be input and a time when the signal level starts to increase.

7. The method for detecting welding status according to claim 3, wherein: In the step of detecting the welding state, the depth of the recessed portion is calculated based on a time period between a time when the light emission signal starts to be input and a time when the signal level starts to increase.

8. The method for detecting welding status according to claim 4, wherein: In the step of detecting the welding state, the depth of the recessed portion is calculated based on a time period between a time when the light emission signal starts to be input and a time when the signal level starts to increase.

9. The method for detecting a welding state according to any one of claims 1 to 8, wherein: In the step of detecting the welding state, when the signal level of the reflected light becomes equal to or higher than a predetermined third threshold value, it is determined that the laser light is irradiated onto an unintended portion.

10. The method for detecting a welding state according to any one of claims 1 to 8, wherein: In the step of detecting the welding state, when the signal level of the light emission becomes equal to or higher than a predetermined fourth threshold value, it is determined that the laser light is irradiated onto an unintended portion.

11. The method for detecting welding status according to claim 9, wherein: In the step of detecting the welding state, when the signal level of the light emission becomes equal to or higher than a predetermined fourth threshold value, it is determined that the laser light is irradiated onto an unintended portion.

12. A welding device comprising: A laser irradiation unit capable of irradiating a laser onto a workpiece; a detection unit capable of detecting reflected light from the portion irradiated with the laser light and luminescence of the portion irradiated with the laser light; and The controller can detect the welding state of the portion irradiated by the laser based on the detected reflected light and the detected luminescence, The controller detects whether the signal level of the light emission is equal to or higher than a first predetermined threshold value and the signal level of the reflected light is equal to or lower than a second predetermined threshold value. The controller determines that a concave portion is generated in the portion irradiated with the laser light when the signal level of the light emission becomes equal to or higher than a predetermined first threshold value and the signal level of the reflected light becomes equal to or lower than a predetermined second threshold value, The welding device further includes a moving part capable of moving a position of the workpiece irradiated with the laser beam. The controller calculates the length of the recessed portion based on a product of a time when the signal level of the reflected light becomes equal to or lower than the second threshold value and a moving speed of the portion irradiated with the laser beam.

13. The welding device according to claim 12, wherein: The controller calculates the depth of the recess based on a difference between the second threshold value and the minimum value of the signal level.

14. The welding device according to claim 12, wherein: The controller calculates the size of the recess based on a difference between a previously calculated integrated value of the signal level of the light emission when the recess is not generated and an integrated value of the signal level of the light emission when the recess is generated.

15. The welding device according to claim 13, wherein: The controller calculates the size of the recess based on a difference between a previously calculated integrated value of the signal level of the light emission when the recess is not generated and an integrated value of the signal level of the light emission when the recess is generated.

16. The welding device according to claim 12, wherein: The controller calculates the depth of the recess based on a time between a time when the light emission signal starts to be input and a time when the signal level starts to increase.

17. The welding device according to claim 13, wherein: The controller calculates the depth of the recess based on a time between a time when the light emission signal starts to be input and a time when the signal level starts to increase.

18. The welding device according to claim 14, wherein: The controller calculates the depth of the recess based on a time between a time when the light emission signal starts to be input and a time when the signal level starts to increase.

19. The welding device according to claim 15, wherein: The controller calculates the depth of the recess based on a time between a time when the light emission signal starts to be input and a time when the signal level starts to increase.

20. The welding device according to any one of claims 12 to 19, wherein: The controller determines that the laser beam is irradiated onto an unintended portion when the signal level of the reflected light becomes equal to or higher than a predetermined third threshold value.

21. The welding device according to any one of claims 12 to 19, wherein: The controller determines that the laser beam is irradiated onto an unintended portion when the signal level of the light emission becomes equal to or higher than a predetermined fourth threshold value.

22. The welding device according to claim 20, wherein: The controller determines that the laser beam is irradiated onto an unintended portion when the signal level of the light emission becomes equal to or higher than a predetermined fourth threshold value.

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