Laser welding equipment, and laser welding method

Abstract

To provide laser welding equipment and a laser welding method, each enabling a user to easily know the internal state of a weld zone.SOLUTION: Laser welding equipment according to an embodiment comprises: a laser irradiation portion which irradiates a welding position of a member with a laser beam; a shielding gas supply portion which supplies shielding gas to the welding position of the member; a photographing portion which photographs an image of a molten pool formed by irradiating the welding position of the member with the laser beam; and a controller which estimates the internal state of the weld zone formed by solidifying the molten pool on the basis of the captured image of the molten pool. The controller estimates the internal state of the weld zone on the basis of at least one of the variance of the change amount of brightness on the surface of the molten pool, the number of spatters on the surface of the molten pool, and the number of bubbles on the surface of the molten pool.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a laser welding apparatus and a laser welding method. [Background technology]

[0002] For example, there is a case where two members are arranged side by side, and a laser beam is irradiated onto an end of one member and an end of the other member adjacent to the one member, thereby welding the ends of the two members together.

[0003] Here, a shielding gas such as nitrogen gas is supplied to the welding position of the members to shield the welding position of the members. However, gas in the environment (e.g., air) may be mixed into the shielding gas and may be caught in the molten pool formed by the irradiation of the laser light. When gas is caught in the molten pool, blowholes may occur inside the weld. If a blowhole is present inside the weld, the effective cross-sectional area of ​​the weld is reduced, so that the tensile strength of the weld is reduced or varies. In this case, if an X-ray measurement or cutting of the weld is performed to check the state inside the weld, a new problem of time and effort is created.

[0004] In addition, a technique for detecting defects in welds has been proposed that uses a CCD camera or the like to measure the external dimensions of a weld. However, even if the external dimensions of a weld are measured, it is not possible to know the internal condition of the weld.

[0005] Therefore, there has been a need to develop a technology that can easily ascertain the internal condition of a weld. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2008-246536 A Summary of the Invention

Problems to be Solved by the Invention

[0007] The problem to be solved by the present invention is to provide a laser welding apparatus and a laser welding method capable of easily knowing the internal state of a welded portion.

Means for Solving the Problems

[0008] The laser welding apparatus according to the embodiment includes a laser irradiation unit that irradiates a laser beam onto a welding position of a member, a shielding gas supply unit that supplies a shielding gas to the welding position of the member, an imaging unit that captures an image of a molten pool formed by irradiating the laser beam onto the welding position of the member, and a controller that estimates the internal state of a welded portion formed by hardening of the molten pool based on the captured image of the molten pool. The controller estimates the internal state of the welded portion based on at least any one of the variance of the change amount of the luminance of the surface of the molten pool, the number of spatters on the surface of the molten pool, and the number of bubbles on the surface of the molten pool.

Brief Description of the Drawings

[0009]

Figure 1

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Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be exemplified with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0011] The laser welding apparatus and the laser welding method according to the present embodiment can be used, for example, for welding the butted portion of two plate materials, welding the ends of linearly arranged members, and the like. However, the uses of the laser welding apparatus and the laser welding method according to the present embodiment are not limited to those exemplified. Hereinafter, as an example, the case of welding the ends of flat wires containing copper will be described.

[0012] FIG. 1 is a schematic diagram for exemplifying the laser welding apparatus 1 according to the present embodiment. As shown in FIG. 1, the laser welding apparatus 1 includes, for example, a holding unit 2, a laser irradiation unit 3, a shielding gas supply unit 4, a detection unit 5, and a controller 6.

[0013] The holding part 2 holds, for example, two linear members 100 arranged side by side. The cross-sectional shape of the linear member 100 in a direction orthogonal to the axial direction is, for example, a quadrilateral. The linear member 100 is, for example, a straight wire. The cross-sectional dimension of the linear member 100 in a direction orthogonal to the axial direction is, for example, about 1 mm to 4 mm. The linear member 100 contains a material with high conductivity. The linear member 100 contains, for example, so-called pure copper or a material mainly composed of copper.

[0014] Also, the side surface of the linear member 100 (for example, a plane parallel to the axial direction) may be covered with an insulating film. The insulating film contains, for example, enamel or the like. However, in the vicinity of the end where the linear member 100 is welded, no insulating film is provided, and the end and side surface of the linear member 100 are exposed.

[0015] The laser irradiation part 3 irradiates laser light at the welding position of the linear member 100. The laser irradiation part 3 can be, for example, a fiber laser welding device, a disk laser welding device, or the like. The laser irradiation part 3 is preferably a CW laser (Continuous wave laser) welding device capable of continuously emitting laser light 101. Also, the irradiation position of the laser light 101 of the laser irradiation part 3 is movable. For example, the laser irradiation part 3 can be provided with a scanning device such as a galvano mirror.

[0016] Also, the laser irradiation part 3 can be capable of emitting laser light 101 with a wavelength in the infrared region or a wavelength in the blue to green region. In this case, if the laser irradiation part 3 is capable of emitting laser light 101 with a wavelength in the infrared region, it becomes easy to irradiate laser light 101 with a relatively high output. For example, the output of the laser irradiation part 3 can be about 4 kW.

[0017] The shielding gas supply unit 4 supplies the shielding gas 102 to the welding position of the linear member 100. For example, the shielding gas supply unit 4 supplies the shielding gas 102 to the ends of two linear members 100 arranged side by side. The shielding gas 102 can be, for example, an inert gas such as nitrogen gas. The shielding gas supply unit 4 has, for example, a gas source 41, a gas control unit 42, and a nozzle 43. The gas source 41 is connected to the gas control unit 42 via a pipe or the like. The gas source 41 can be, for example, a high-pressure cylinder storing the shielding gas 102 or a factory pipe. Also, the gas source 41 may be capable of selectively supplying a plurality of types of shielding gas 102. For example, the gas source 41 can be capable of selectively supplying nitrogen gas and helium gas.

[0018] The gas control unit 42 can adjust at least any one of the pressure, flow rate, and type of the shielding gas 102 supplied from the nozzle 43 to the welding position of the linear member 100. Also, the gas control unit 42 can control the start and stop of the supply of the shielding gas 102.

[0019] The nozzle 43 injects the shielding gas 102 toward the welding position of the linear member 100. Also, an adjusting device 43a for adjusting at least any one of the supply position and supply range of the shielding gas 102 can be provided in the nozzle 43. For example, the adjusting device 43a can adjust the supply position of the shielding gas 102 with respect to the welding position of the linear member 100 by changing the opening position or angle of the nozzle 43. For example, the adjusting device 43a can adjust the supply range of the shielding gas 102 with respect to the welding position of the linear member 100 by changing the opening dimension of the nozzle 43.

[0020] That is, the shielding gas supply unit 4 can adjust at least any one of the supply position, supply range, pressure, flow rate, and type of the shielding gas 102.

[0021] The imaging unit 5 captures an image of the position where the laser beam 101 is irradiated. The imaging unit 5 captures, for example, an image of a molten pool formed by irradiating the ends of the two linear members 100 with the laser beam 101. The imaging unit 5 can be configured to include, for example, a CCD sensor or a CMOS sensor. Further, the imaging unit 5 can also be provided with, for example, a lens for magnifying the image of the molten pool to be captured, a filter for transmitting light in a predetermined wavelength range included in the light emitted from the molten pool, etc. Also, the imaging unit 5 may capture a moving image of the molten pool image, or may continuously capture a still image of the molten pool image.

[0022] The controller 6 controls the operations of the respective elements provided in the laser welding apparatus 1. The controller 6 has, for example, an arithmetic unit such as a CPU and a storage unit such as a semiconductor memory. The controller 6 is, for example, a computer. In the storage unit, for example, a control program for controlling the operations of the respective elements provided in the laser welding apparatus 1 is stored. The arithmetic unit controls the operations of the respective elements provided in the laser welding apparatus 1 based on the control program stored in the storage unit.

[0023] For example, the controller 6 controls the laser irradiation unit 3 to irradiate the ends of the two linear members 100 with the laser beam 101. At this time, the controller 6 controls a scanning device such as a galvanometer mirror to move the irradiation position of the laser beam 101.

[0024] For example, the controller 6 controls the gas control unit 42 to control the start and stop of the supply of the shielding gas 102. Also, the controller 6 controls the gas control unit 42 to control at least one of the pressure and the flow rate of the shielding gas 102 supplied from the nozzle 43 to the welding position of the linear member 100. Further, the controller 6 controls the adjustment device 43a to control at least one of the supply position of the shielding gas 102 with respect to the welding position of the linear member 100 and the supply range of the shielding gas 102 with respect to the welding position of the linear member 100.

[0025] For example, based on the image of the molten pool captured by the imaging unit 5, the controller 6 estimates the internal state of the welded portion formed by the hardening of the molten pool. For example, the controller 6 estimates the internal state of the welded portion based on at least any one of the variance of the change amount of the luminance on the surface of the molten pool, the number of spatters on the surface of the molten pool, and the number of bubbles on the surface of the molten pool. The internal state of the welded portion is, for example, the number of blowholes inside the welded portion. Further, the controller 6 can perform a defect determination of the welded portion based on the estimated internal state of the welded portion.

[0026] For example, when the controller 6 determines that there is a defect in the welded portion, it controls the shielding gas supply unit 4 to adjust at least any one of the supply position of the shielding gas 102, the supply range of the shielding gas 102, the pressure of the shielding gas 102, the flow rate of the shielding gas 102, and the type of the shielding gas 102. That is, when the controller 6 determines that there is a defect in the welded portion, it performs optimization of the shielding at the welding position of the linear member 100 by the shielding gas 102.

[0027] Further, when the controller 6 determines that there is a defect in the welded portion, it can also perform rework on the welded portion determined to have a defect. For example, when the controller 6 determines that there is a defect in the welded portion, it controls the laser irradiation unit 3 to perform rework of irradiating the welded portion determined to have a defect with the laser light 101 to melt the welded portion. Further, when melting the welded portion, the controller 6 causes the laser light 101 to reach the linear member 100 under the welded portion. Note that details regarding the estimation of the internal state of the welded portion, the defect determination of the welded portion, and the rework of the welded portion determined to have a defect will be described later.

[0028] Next, the laser welding method according to the present embodiment will be exemplified. The laser welding method according to the present embodiment can be implemented, for example, using the laser welding apparatus 1 described above. FIG. 2 is a schematic diagram for exemplifying laser welding of the ends of two linear members 100. In FIG. 2, the case where a gap 100a is formed between the ends of the two linear members 100 is exemplified. However, for example, when the two linear members 100 are held by the holding portion 2 described above, the case where the ends of the two linear members 100 are in contact with each other (when there is no gap 100a) can be treated in the same manner.

[0029] First, a shielding gas 102 is supplied to the ends of the two linear members 100. Next, as shown in FIG. 2, the laser beam 101 is alternately irradiated to the end of one linear member 100 and the end of the other linear member 100 adjacent thereto. By alternately irradiating the laser beam 101, the ends of the two linear members 100 are melted respectively, and two molten pools 100b are formed. As the melting of the ends of the two linear members 100 progresses, the molten pools 100b gradually become larger. When the two molten pools 100b become larger, the two molten pools 100b merge, and a molten pool 100c straddling the two ends is formed. At this time, the opening of the gap 100a is covered by the molten pool 100c.

[0030] In this case, the irradiation of the laser beam 101 can be performed, for example, according to the following procedure. First, as shown in FIG. 2, at the end of one linear member 100, the laser beam 101 is irradiated along the movement path 101a of the irradiation position of the loop-shaped laser beam 101. Next, the irradiation of the laser beam 101 is stopped, and the irradiation position of the laser beam 101 is moved from the end of one linear member 100 to the end of the other linear member 100 along the movement path 101b of the irradiation position of the linear laser beam 101.

[0031] Next, at the end of the other linear member 100, the irradiation of the laser beam 101 is restarted, and the laser beam 101 is irradiated along the movement path 101a of the irradiation position of the loop-shaped laser beam 101. Next, stop irradiating the laser beam 101, and move the irradiation position of the laser beam 101 from the end of the other linear member 100 to the end of one linear member 100 along the movement path 101b of the irradiation position of the linear laser beam 101. The movement of the irradiation position of the laser beam 101 can be performed by a scanning device such as a galvanometer mirror provided in the laser welding apparatus 1, for example.

[0032] By repeating the above procedure a plurality of times, a molten pool 100b is formed at each of the ends of the two linear members 100. As the melting of the ends of the two linear members 100 progresses, the two molten pools 100b gradually become larger, so that the two molten pools 100b merge to form a molten pool 100c straddling the two ends. At this time, the opening of the gap 100a is covered by the molten pool 100c.

[0033] Next, after the molten pool 100c is formed, stop irradiating the laser beam 101. The formation of the molten pool 100c can be determined, for example, from an image captured by the imaging unit 5. When the irradiation of the laser beam 101 is stopped, the molten pool 100c is cooled and hardened, and a welded portion that joins the ends of the two linear members 100 is formed.

[0034] Here, a small space called a blowhole may be generated inside the welded portion. FIGS. 3(a) and (b) are photographs for exemplifying the blowhole 200. FIGS. 3(a) and (b) are photographs of the welded portion taken using X-rays. As can be seen from FIG. 3(a), there may be a case where the number of generated blowholes 200 is small, and as can be seen from FIG. 3(b), there may be a case where the number of generated blowholes 200 is large. When the blowholes 200 are inside the welded portion, the substantial cross-sectional area of the welded portion will decrease, so that the tensile strength of the welded portion will decrease or the tensile strength of the welded portion will vary. For example, in the case of FIG. 3(a), since the number of blowholes 200 is small, the tensile strength was about 301 N. In the case of FIG. 3(b), since the number of blowholes 200 is large, the tensile strength was about 178 N.

[0035] Here, it is considered that the blow hole 200 is generated by the gas (for example, air, etc.) in the vicinity of the linear member 100 being mixed into the shielding gas 102 supplied to the welding position of the linear member 100 when irradiating the end of the linear member 100 with the laser beam 101 to form the molten pools 100b and 100c. That is, it is considered that the blow hole 200 is generated by the gas in the vicinity of the linear member 100 being drawn into the inside of the molten pools 100b and 100c.

[0036] FIG. 4 is a graph for exemplifying the relationship between the ratio of air mixed into the shielding gas 102 and the number of blow holes 200 generated. As can be seen from FIG. 4, as the ratio of air mixed into the shielding gas 102 increases, the number of blow holes 200 increases. Also, if the vicinity of the end of the linear member 100 is covered with the shielding gas 102, the generation of the blow hole 200 can be prevented.

[0037] As described above, by adjusting at least either the supply position or the supply range of the shielding gas 102 to the welding pools 100b and 100c by the adjustment device 43a, the vicinity of the end of the linear member 100 can be covered with the shielding gas 102. Also, by adjusting at least either the pressure, the flow rate, or the type of the shielding gas 102 by the gas control unit 42, the vicinity of the end of the linear member 100 can be covered with the shielding gas 102. If the vicinity of the end of the linear member 100 is covered with the shielding gas 102, as can be seen from FIG. 4, it is considered that the generation of the blow hole 200 can be suppressed.

[0038] However, it is difficult to know whether the vicinity of the end of the linear member 100 is covered with the shielding gas 102. Therefore, it is necessary to estimate the generation of the blow hole 200. FIG. 5 is a photograph for exemplifying a method of confirming the generation of the blow hole 200. FIG. 5 is a photograph of the cut welded portion. As can be seen from FIG. 5, if the welded part is cut, the blow hole 200 can be visually recognized. However, if the welded part is cut, it will no longer be a product. Therefore, it is impossible to know the occurrence of the blow hole 200 for all welded parts.

[0039] In this case, as shown in FIGS. 3(a) and (b), if the welded part is photographed using X-rays, the occurrence of the blow hole 200 can be known. However, since photographing takes time and effort, it is difficult to know the occurrence of the blow hole 200 for all welded parts.

[0040] Therefore, in the laser welding method according to the present embodiment, the occurrence of the blow hole 200 is estimated as follows.

[0041] As described above, the blow hole 200 is generated by gas being entrapped inside the molten pools 100b and 100c. In this case, at least a part of the gas inside the molten pool 100c is discharged to the outside from the surface of the molten pool 100c. Therefore, from the state of the surface of the molten pool 100c, it can be estimated that there is gas inside the molten pool 100c, and thus a blow hole 200 is generated inside the welded part.

[0042] For example, when the gas inside the molten pool 100c is discharged to the outside from the surface of the molten pool 100c, the surface of the molten pool 100c is locally deformed. Therefore, by obtaining the amount of change in the luminance of the surface of the welding pool 100c, it is possible to estimate the discharge of gas from the molten pool 100c, and thus the occurrence of the blow hole 200.

[0043] FIG. 6 is a photograph for exemplifying the luminance of the surface of the molten pool 100c. The luminance of the surface of the molten pool 100c can be obtained, for example, from the image data of the molten pool 100c photographed by the photographing unit 5 described above.

[0044] FIG. 7 is a graph for exemplifying the amount of change in the luminance of the surface of the molten pool 100c. FIG. 7 is a graph plotting the amount of change from the luminance in the frame photographed immediately before. In the case illustrated in FIG. 7, the variance of the amount of change in luminance was 0.488.

[0045] FIG. 8 is a graph for exemplifying the relationship between the variance of the amount of change in luminance and the number of blowholes 200. As can be seen from FIG. 8, as the variance of the amount of change in luminance increases, the number of blowholes 200 increases. In the case illustrated in FIG. 8, the correlation function between the variance of the amount of change in luminance and the number of blowholes 200 was 0.98. For example, in the case illustrated in FIG. 7, since the variance of the amount of change in luminance is 0.488, the number of blowholes 200 generated can be estimated to be about 300.

[0046] For example, the controller 6 calculates the variance of the amount of change in luminance from the image data of the molten pool 100c photographed by the photographing unit 5. Then, the controller 6 estimates the number of blowholes 200 generated from the correlation function between the variance of the amount of change in luminance and the number of blowholes 200 obtained in advance. As described above, there is a negative correlation between the number of blowholes 200 and the tensile strength of the welded portion. Therefore, the controller 6 can obtain the tensile strength of the welded portion from the estimated number of blowholes 200, and when the obtained tensile strength is equal to or less than a predetermined threshold value, it can be determined that there is a defect in the welded portion.

[0047] Also, when gas is discharged from the molten pool 100c, spatter (scattering of molten metal) may occur. FIG. 9 is a photograph for exemplifying spatter 100d. Spatter 100d can be detected, for example, from the image data of the molten pool 100c photographed by the photographing unit 5 described above.

[0048] FIG. 10 is a graph for exemplifying the relationship between the number of spatter 100d and the number of blowholes 200. As can be seen from FIG. 10, as the number of sputters 100d increases, the number of blowholes 200 increases. In the case illustrated in FIG. 10, the correlation function between the number of sputters 100d and the number of blowholes 200 was 0.99.

[0049] For example, the controller 6 obtains the number of sputters 100d from the data of the image of the molten pool 100c photographed by the photographing unit 5. Then, the controller 6 estimates the number of blowholes 200 to be generated from the correlation function between the number of sputters 100d and the number of blowholes 200 obtained in advance. As described above, there is a negative correlation between the number of blowholes 200 and the tensile strength of the welded portion. Therefore, the controller 6 can obtain the tensile strength of the welded portion from the estimated number of blowholes 200, and determine that there is a defect in the welded portion when the obtained tensile strength is equal to or less than a predetermined threshold value.

[0050] In addition, when gas is discharged from the molten pool 100c, bubbles may occur on the surface of the molten pool 100c. FIG. 11 is a graph for exemplifying the relationship between the number of bubbles and the number of blowholes 200. As can be seen from FIG. 11, as the number of bubbles increases, the number of blowholes 200 increases. In the case illustrated in FIG. 11, the correlation function between the number of bubbles and the number of blowholes 200 was 0.98.

[0051] For example, the controller 6 obtains the number of bubbles from the data of the image of the molten pool 100c photographed by the photographing unit 5. Then, the controller 6 estimates the number of blowholes 200 to be generated from the correlation function between the number of bubbles and the number of blowholes 200 obtained in advance. As described above, there is a negative correlation between the number of blowholes 200 and the tensile strength of the welded portion. Therefore, the controller 6 can obtain the tensile strength of the welded portion from the estimated number of blowholes 200, and determine that there is a defect in the welded portion when the obtained tensile strength is equal to or less than a predetermined threshold value.

[0052] In addition, it is also possible to appropriately combine the estimation of the number of blowholes 200 based on the variance of the amount of change in luminance, the estimation of the number of blowholes 200 based on the number of sputters 100d, and the estimation of the number of blowholes 200 based on the number of bubbles, to determine whether there is a defect in the welded part.

[0053] In addition, the detection of the luminance on the surface of the molten pool 100c, the sputter 100d, and the bubbles can be performed after the molten pool 100c is formed and the irradiation of the laser beam 101 is stopped, until the molten pool 100c is hardened and the welded part is formed.

[0054] Here, the sputter 100d and the bubbles are small in size and also appear for a short time. Therefore, it is difficult to detect the sputter 100d and the bubbles. On the other hand, the luminance on the surface of the molten pool 100c can be detected relatively easily. Therefore, if the number of blowholes 200 is estimated based on the variance of the amount of change in luminance, the number of blowholes 200 can be estimated easily and accurately. As a result, the reliability for determining whether there is a defect in the welded part can be improved.

[0055] When it is determined that there is a defect in the welded part, the above-described adjustment is performed, and the shielding at the welding position of the linear member 100 by the shielding gas 102 is optimized. However, if only the shielding is optimized, the product determined to have a defect in the welded part will be discarded. In this case, if the shielding is optimized and the product determined to have a defect in the welded part is reworked, the yield of the product can be improved.

[0056] For example, the rework can be performed as follows. When it is determined that there is a defect in the welded part, after performing the above-described adjustment to optimize the shielding, the welded part determined to have a defect is irradiated with the laser beam 101 to melt the welded part. After the welded part is melted, the irradiation of the laser beam 101 is stopped, and the melted welded part is hardened to form the welded part again.

[0057] Figure 12 is a photograph for exemplifying a cross-section of a reworked welded part. As can be seen from Figure 12, if rework is performed, the number of blowholes 200 inside the welded part can be reduced. In the case of the reworked welded part exemplified in Figure 12, the number of blowholes 200 remaining in the lower part of the welded part is larger than the number of blowholes 200 remaining in the upper part of the welded part. The number of blowholes 200 remaining in the lower part of the welded part can be reduced by making the melted welded part reach the linear member 100 when performing rework. For example, when the controller 6 melts the welded part, the laser beam 101 is made to reach the linear member 100 under the welded part. The position of the melted welded part can be controlled, for example, by the output of the laser beam 101 and the irradiation time of the laser beam 101.

[0058] Figure 13 is a graph for exemplifying the effect of rework. ■ in Figure 13 indicates the case where rework was not performed. ● in Figure 13 indicates the case where rework was performed. Also, sample number 1 is the case where the proportion of air mixed into the shielding gas 102 in Figure 4 is 0%. Sample number 2 is the case where the proportion of air mixed into the shielding gas 102 in Figure 4 is 25%. Sample number 3 is the case where the proportion of air mixed into the shielding gas 102 in Figure 4 is 50%. Sample number 4 is the case where the proportion of air mixed into the shielding gas 102 in Figure 4 is 75%. Sample number 5 is the case where the proportion of air mixed into the shielding gas 102 in Figure 4 is 100%. That is, it is the case where the shielding gas 102 was not supplied. As can be seen from Figure 13, if rework is performed, the number of remaining blowholes 200 can be significantly reduced.

[0059] Also, when performing rework, for example, the output of the laser beam 101 emitted from the laser irradiation unit 3 can be decreased to increase the time during which the welded part is melted. If the time during which the welded part is melted is increased, the opportunity for the gas contained in the melted welded part to be discharged can be increased. Therefore, the number of blowholes 200 remaining in the reworked welded part can be reduced.

[0060] Also, when performing rework, for example, the irradiation position of the laser beam 101 can be moved to discharge the gas contained in the melted welded part to the outside.

[0061] FIG. 14 is a schematic diagram for exemplifying the movement path of the irradiation position of the laser beam 101 when performing rework. As shown in FIG. 14, for example, the start point 101c of the irradiation of the laser beam 101 can be set at a position between the end of one linear member 100 and the end of the other linear member 100 (for example, the center of the gap 100a). Note that the end point of the irradiation of the laser beam 101 can be, for example, the position of the end of one linear member 100 or the position of the end of the other linear member 100.

[0062] Next, the irradiation position of the laser beam 101 is moved. In this case, as shown in FIG. 14, as the irradiation position of the laser beam 101 rotates around the start point 101c, it can be made to gradually move away from the start point 101c. In this case, the shape of the movement path of the irradiation position of the laser beam 101 can be made into a shape that gradually moves away from the start point 101c as it rotates around the start point 101c. For example, as shown in FIG. 14, the shape of the movement path of the irradiation position of the laser beam 101 can be made into a spiral shape.

[0063] Note that there is no particular limitation on the turning direction in the movement path. The turning direction may be, for example, clockwise or counterclockwise. Also, the shape of the movement path and the number of turns can be changed as appropriate.

[0064] If the shape of the movement path of the irradiation position of the laser beam 101 gradually moves away from the starting point 101c as it rotates around the starting point 101c, a flow from the center toward the periphery can be formed inside the melted welded portion 103. Therefore, the gas contained inside the melted welded portion 103 can be discharged to the outside of the melted welded portion 103.

[0065] Also, due to the flow inside the melted welded portion 103 (the flow from the center toward the periphery) and the impact when the laser beam 101 is incident, the gas contained inside the melted welded portion 103 can also be discharged to the outside of the melted welded portion 103.

[0066] As described above, the laser welding method according to the present embodiment can include the following steps. A step of irradiating a laser beam 101 at the welding position of the linear member 100 where the shielding gas 102 is supplied. A step of photographing an image of the molten pool 100c formed by irradiating the laser beam 101. A step of estimating the internal state of the welded portion formed by hardening the molten pool 100c based on the photographed image of the molten pool 100c. In the step of estimating the internal state of the welded portion, the internal state of the welded portion is estimated based on at least any one of the variance of the change amount of the luminance on the surface of the molten pool 100c, the number of spatters on the surface of the molten pool 100c, and the number of bubbles on the surface of the molten pool 100c.

[0067] Also, the laser welding method according to the present embodiment can further include the following steps. A step of performing a defect determination of the welded portion based on the estimated internal state of the welded portion. In the step of performing a defect determination of the welded portion, when it is determined that there is a defect, a step of irradiating the laser beam 101 to the welded portion determined to have a defect to melt the welded portion.

[0068] Also, the laser welding method according to the present embodiment can further include the following steps. A step of performing a defect determination of a welded portion based on the presumed internal state of the welded portion. In the step of performing a defect determination of a welded portion, when it is determined that there is a defect, at least any one of the supply position of the shielding gas 102, the supply range of the shielding gas 102, the pressure of the shielding gas 102, the flow rate of the shielding gas 102, and the type of the shielding gas 102 is adjusted, and a step of optimizing the shielding at the welding position of the linear member 100 by the shielding gas 102 is executed.

[0069] Further, in the laser welding method according to the present embodiment, in the step of melting the welded portion, the melted welded portion reaches the linear member 100.

[0070] As described above, some embodiments of the present invention have been illustrated. However, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, changes, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope. Further, the above-described embodiments can be implemented in combination with each other.

Explanation of Reference Numerals

[0071] 1 Laser welding apparatus, 2 Holding portion, 3 Laser irradiation portion, 4 Shielding gas supply portion, 5 Detection portion, 6 Controller, 42 Gas control portion, 43 Nozzle, 43a Adjusting device, 100 Linear member, 100b Molten pool, 100c Molten pool, 100d Spatter, 101 Laser beam, 102 Shielding gas, 200 Blow hole

Claims

1. a laser irradiation unit that irradiates a laser beam onto a welding position of a member; a shielding gas supply unit that supplies a shielding gas to the welding position of the member; a photographing unit that photographs an image of a molten pool formed by irradiating the welding position of the member with the laser beam; a controller that estimates a state inside a welded portion formed by hardening of the molten pool based on the photographed image of the molten pool; comprising The controller is a laser welding apparatus that estimates a state inside the welded portion based on at least any one of a variance of a change amount of luminance on a surface of the molten pool, a number of spatters on the surface of the molten pool, and a number of bubbles on the surface of the molten pool.

2. The controller performs a defect determination of the welded portion based on the estimated state inside the welded portion, and when it is determined that there is a defect in the welded portion, controls the laser irradiation unit to irradiate the welded portion determined to have a defect with the laser beam to melt the welded portion. The laser welding apparatus according to claim 1.

3. The shielding gas supply unit can adjust at least any one of a supply position of the shielding gas, a supply range of the shielding gas, a pressure of the shielding gas, a flow rate of the shielding gas, and a type of the shielding gas, The controller performs a defect determination of the welded portion based on the estimated state inside the welded portion, and when it is determined that there is a defect in the welded portion, controls the shielding gas supply unit to perform the adjustment and execute optimization of shielding at the welding position of the member by the shielding gas. The laser welding apparatus according to claim 1 or 2.

4. The controller according to claim 2, wherein when melting the welded portion, the melted welded portion reaches the member. The laser welding apparatus.

5. a step of irradiating a laser beam onto a welding position of a member while a shielding gas is being supplied; a step of photographing an image of a molten pool formed by irradiation with the laser beam; a step of estimating a state inside a welded portion formed by hardening of the molten pool based on the photographed image of the molten pool; comprising In the step of estimating the internal state of the welded portion, based on at least any one of the variance of the change amount of the luminance of the surface of the molten pool, the number of spatters on the surface of the molten pool, and the number of bubbles on the surface of the molten pool, a laser welding method for estimating the internal state of the welded portion.

6. A step of performing a defect determination of the welded portion based on the estimated internal state of the welded portion, In the step of performing a defect determination of the welded portion, when it is determined that there is a defect, a step of irradiating the welded portion determined to have a defect with the laser beam to melt the welded portion, The laser welding method according to claim 5, further comprising the above.

7. A step of performing a defect determination of the welded portion based on the estimated internal state of the welded portion, In the step of performing a defect determination of the welded portion, when it is determined that there is a defect, at least any one of the supply position of the shielding gas, the supply range of the shielding gas, the pressure of the shielding gas, the flow rate of the shielding gas, and the type of the shielding gas is adjusted to perform optimization of the shielding at the welding position of the member by the shielding gas. The laser welding method according to claim 5 or 6, further comprising the above.

8. In the step of melting the welded portion, the laser welding method according to claim 6, wherein the melted welded portion reaches the member.

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