Laser welding system and laser welding method

Abstract

To provide a laser welding system capable of suppressing occurrence of defective welding.SOLUTION: A laser welding system 1 includes a welding device 2, and a control device 4 for controlling the welding device 2 by a predetermined welding parameter, wherein the control device 4 changes the welding parameter on the basis of an abutting interval between a first metal member M1 and a second metal member M2 at a predetermined position on a Dx upstream side in a welding direction rather than a welding reference position. The welding reference position is a processing point on a member M to be welded when the surface Ms of the member M to be welded is irradiated with a laser beam L1 from a laser irradiation part in a Z direction vertical to the surface Ms, and a distance between the predetermined position in the welding direction Dx and the welding reference position is 5 mm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laser welding system and a laser welding method capable of suppressing the occurrence of welding defects.

Background Art

[0002] Conventionally, in laser welding in which laser light is irradiated onto the butted portion of metal members for joining, a method of securing a wide bead width by wobbling and scanning the laser light has been adopted. Further, since the presence of a gap (butt interval) in the butted portion may cause welding defects such as insufficient welding strength and perforation, in order to solve such problems, a method has been proposed in which the butt interval is detected and the wobbling amplitude is changed so that the wobbling amplitude increases as the butt interval increases (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in wobbling welding, it may not be possible to sufficiently suppress welding defects only by adjusting the amplitude of the laser light according to the butt interval. For example, when the metal member is thin, increasing the scanning amplitude (wobbling amplitude) of the laser light according to the butt interval may rather easily cause perforation. Further, the butt interval easily fluctuates due to the influence of welding heat or the like, and the butt interval may deviate between the measurement time and the welding time.

[0005] Here, the following experiment was conducted to confirm such a variation in the butting interval. Referring to FIG. 10, a slit SL (through-hole) with a width of 0.4 mm was formed in a metal plate B with a thickness of 1.6 mm, and this slit SL was regarded as the butting interval, and the width G1 (butting interval) of the slit SL was measured three times. For the first and second times, only measurement was performed without welding, and for the third time, measurement was performed while laser welding was carried out along the slit SL. The measurement position of the slit width G1 was set at a position 2 mm upstream in the welding direction Dx from the welding reference position (the intersection of the optical axis of the condenser lens provided in the laser irradiation part and the metal plate B).

[0006] The measurement results of the slit width G1 are shown in FIG. 11. As can be understood from FIG. 11, as the laser welding progresses, the slit width G1 (gap) decreases. This means that the metal plate B is deformed in the direction in which the slit SL closes.

[0007] Also, in this experiment, since welding was performed in a state where both sides of the slit SL were closed (that is, the metal plate B was not separated), the change amount of the slit width G1 was relatively suppressed. However, in actual welding, since two mutually separated metal plates are used, it is expected that the change amount of the slit width G1 will be even larger.

[0008] Whether the metal plate B deforms in the direction in which the slit SL closes or in the direction in which the slit SL expands depends on conditions such as the plate thickness.

[0009] An object of the present invention is to provide a laser welding system and a laser welding method capable of more effectively suppressing the occurrence of welding defects.

Means for Solving the Problems

[0010] The laser welding system according to the present invention includes a welding device for laser-welding a member to be welded, and a control means for controlling the welding device with predetermined welding parameters. The member to be welded has a first metal member and a second metal member that are abutted against each other. The welding device irradiates the surface of the member to be welded while two-dimensionally scanning a laser beam, thereby welding the first metal member and the second metal member. The welding device includes a laser oscillator for oscillating a laser beam, and a laser irradiation unit for scanning the laser beam and irradiating the member to be welded. The control means changes the welding parameters based on the butting interval between the first metal member and the second metal member at a predetermined position on the upstream side in the welding direction from a welding reference position. The welding reference position is a processing point on the member to be welded when the laser beam is irradiated from the laser irradiation unit in a direction perpendicular to the surface of the member to be welded. The distance from the predetermined position in the welding direction to the welding reference position is 5 mm or less.

[0011] The laser welding method according to the present invention is a laser welding method in which a laser beam is irradiated based on welding parameters on the surface of a member to be welded composed of a first metal member and a second metal member that are abutted against each other, and laser welding is performed. The method includes a step of detecting a butting interval of the member to be welded at a predetermined position on the upstream side in the welding direction from a welding reference position, and a step of changing the welding parameters according to the butting interval. The laser beam has a center beam and a ring beam surrounding the center beam. The welding parameters include an output value of the center beam, an output value of the ring beam, a scanning amplitude of the laser beam, and a scanning frequency of the laser beam. The welding reference position is a processing point on the member to be welded when the laser beam is irradiated in a direction perpendicular to the surface of the member to be welded. The distance from the predetermined position in the welding direction to the welding reference position is 5 mm or less.

Effect of the Invention

[0012] According to the laser welding system and the laser welding method according to the present invention, the welding parameters are changed based on the butting interval between the first metal member and the second metal member at a predetermined position, and the distance from the predetermined position in the welding direction to the welding reference position is 5 mm or less. Therefore, it is possible to prevent the butting interval from greatly deviating between the measurement time and the welding time, and perform welding with more appropriate welding parameters according to the butting interval, thereby suppressing the occurrence of welding defects such as perforation.

Brief Description of Drawings

[0013]

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Figure 11

Best Mode for Carrying Out the Invention

[0014] With reference to the accompanying drawings, a laser welding system and a laser welding method according to an embodiment of the present invention will be described. Referring to FIG. 1, a laser welding system 1 according to the present embodiment irradiates a laser beam L onto a member M to be welded installed on a stage T for welding, and includes a welding device 2, an optical interferometer 3, and a control device 4 as a control means.

[0015] The member M to be welded has a first metal member M1 and a second metal member M2 that are abutted against each other. The welding device 2 irradiates the laser beam L in a predetermined scanning pattern so as to repeatedly cross the butting line A between the first metal member M1 and the second metal member M2, thereby welding the first metal member M1 and the second metal member M2. Here, the scanning pattern refers to a locus pattern drawn by the laser beam L on the member M to be welded, and examples thereof include a spiral scanning pattern Pa1 by wobbling as shown in FIG. 2(b) and a zigzag scanning pattern Pa2 by weaving as shown in FIG. 3(b).

[0016] In the following description, the direction in which the butting line A extends is defined as the X direction, the direction perpendicular to the X direction and parallel to the surface Ms of the member M to be welded is defined as the Y direction, and the direction perpendicular to the X direction and the Y direction is defined as the Z direction. The Z direction is parallel to the height direction of the welding device 2 and also parallel to the thickness direction of the member M to be welded.

[0017] In the present embodiment, laser welding is performed while the welding parameters are corrected in real time according to the welding conditions and the butting interval (more specifically, the width dimension of the butting interval in the Y direction) G (FIG. 4) between the first metal member M1 and the second metal member M2. Details will be described later.

[0018] The welding device 2 includes a drive mechanism 5, a laser oscillator 6 that oscillates the laser beam L, and a laser irradiation unit 7 as a laser head that irradiates the member M to be welded while two-dimensionally scanning the laser beam L oscillated by the laser oscillator 6.

[0019] The drive mechanism 5 moves the laser irradiation unit 7 and the interferometer 3 relative to the stage T (welded member M) in the welding direction Dx parallel to the X direction at a predetermined welding speed. As the drive mechanism 5, the stage T may be the fixed side, and a robot arm (not shown) or the like to which the laser irradiation unit 7 and the interferometer 3 are attached may be moved in the welding direction Dx, or the laser irradiation unit 7 and the interferometer 3 may be the fixed side, and the stage T may be moved in the direction opposite to the welding direction Dx.

[0020] The laser oscillator 6 includes a first laser oscillator 61 that oscillates a first laser beam, a second laser oscillator 62 that oscillates a second laser beam, a laser controller 63, and an optical system (not shown). The optical system (not shown) synthesizes the first laser beam and the second laser beam as required to form a laser beam L. As shown in FIG. 4, the laser beam L synthesized by the optical system is composed of a center beam L1 corresponding to the first laser beam and a ring beam L2 corresponding to the second laser beam, and the ring beam L2 surrounds the outside of the center beam L1 in a ring shape. It is known that by using such a laser beam L, the generation of spatter during laser welding can be suppressed. The laser controller 63 includes a laser driver (not shown) and outputs and controls the first and second laser oscillators 61 and 62 based on a control signal from the control device 4.

[0021] The laser irradiation unit 7 includes a laser scanner 71 and a condenser lens 72. The laser scanner 71 is, for example, a galvanometer scanner, and includes an X-axis motor 71a connected to an X-axis mirror (not shown), a Y-axis motor 71b connected to a Y-axis mirror (not shown), and a scanner controller 71c for driving the X and Y axis motors 71a and 71b. The scanner controller 71c includes a scanner driver (not shown) and changes the directions of the X-axis mirror (not shown) and the Y-axis mirror (not shown) by driving the X-axis motor 71a and the Y-axis motor 71b.

[0022] In the example shown in FIG. 1, the laser controller 63 and the scanner controller 71c are provided separately. However, the present invention is not limited to such a configuration, and a configuration in which the first and second laser oscillators 61 and 62, the X-axis motor 71a, and the Y-axis motor 71b are controlled by a single controller may be used.

[0023] The laser beam L oscillated by the laser oscillator 6 is transmitted to the laser irradiation unit 7 using an optical fiber or the like, and after being reflected by the X-axis mirror and the Y-axis mirror, it is irradiated onto the surface Ms of the welded member M through the condenser lens 72. The condenser lens 72 condenses the laser beam L scanned by the laser scanner 71 and forms an optical spot on the surface Ms of the welded member M.

[0024] Here, the X-axis mirror (not shown) is a mirror for scanning the laser beam L along the X direction, and the Y-axis mirror (not shown) is a mirror for scanning the laser beam L along the Y direction. By rotating the X-axis motor 71a and the Y-axis motor 72b respectively, the laser beam L can be two-dimensionally scanned in the XY plane as described above.

[0025] In such a configuration, as shown in FIG. 2(a), when the laser beam L is irradiated from the laser irradiation unit 7 in an annular irradiation pattern N1, the trajectory pattern (scanning pattern) of the laser beam L drawn on the surface Ms of the welded member M that is relatively moved with respect to the laser irradiation unit 7 becomes a spiral pattern Pa1 as shown in FIG. 2(b). Similarly, as shown in FIG. 3(a), when the laser beam L is irradiated in a linear irradiation pattern N2 extending in the Y direction, the trajectory pattern (scanning pattern) drawn on the surface Ms of the welded member M becomes a zigzag pattern Pa2 as shown in FIG. 3(b).

[0026] The interferometer 3 is an OCT (Optical Coherence Tomography: This uses the technology of optical coherence tomography, and includes a light source (not shown), a splitter, a reference mirror, and a detection unit. It generates interference light between the reference light and the measurement light that is irradiated onto and reflected from the member M to be welded, and the detection unit detects this as an optical interference signal. The optical interference signal detected by the detection unit is converted from an analog signal to a digital signal by an A / D converter (not shown) and input to the control device 4. Since the specific configuration of the optical interferometer 3 is known, a detailed description thereof is omitted.

[0027] The control device 4 includes a control unit 41, a memory 42, an input operation unit 43, and a display unit 44. The memory 42 stores various programs for executing laser welding processing and the like, and various databases including a welding database DB.

[0028] The welding database DB stores, for example, a welding condition data table TA shown in FIG. 5 and a plurality of performance data tables TB (TB1 to TBn) shown in FIG. 6.

[0029] Referring to FIG. 5, in the welding condition data table TA, information regarding welding conditions, information indicating the performance data table TB, and information indicating the initial values of welding parameters are stored in association with each other. Here, the welding conditions are welding conditions set and input in advance by the user, and include the material and thickness of the first metal member M1, the material and thickness of the second metal member M2, the scanning pattern of the laser beam L, and the welding speed. Laser welding is performed under the set welding conditions.

[0030] Examples of the materials of the metal members M1 and M2 include, but are not limited to, copper and aluminum. The thicknesses of the first and second metal members M1 and M2 refer to the height dimensions (dimensions in the Z direction) T1 and T2 of the first and second metal members M1 and M2 in the state where they are installed on the stage T as required as shown in FIG. 1. The scanning pattern refers to the locus pattern drawn by the laser beam L on the member M to be welded as described above.

[0031] The welding parameters include the "output value of the center beam L1", the "output value of the ring beam L2", the "scanning amplitude of the laser beam L", and the "scanning frequency of the laser beam L". The scanning amplitude of the laser beam L means the size of the scanning pattern drawn by the laser beam, and the scanning frequency of the laser beam L means the number of times the laser beam L draws the scanning pattern per second. The initial value of the welding parameters refers to the value of the welding parameters adopted at the start of laser welding.

[0032] Referring to FIG. 6, each performance data table TB is constructed by the user inputting data regarding the laser welding performed on the welded member M or the test material, including the welding conditions, welding parameters, butting interval, and welding result (weld quality). In each performance data table TB, information indicating the "butting interval" and information indicating one or more "welding performances" are stored in association with each other.

[0033] In the "welding performance", information indicating the "welding parameters" and information indicating the "weldability" are stored in association with each other. The information regarding the "welding parameters" includes information regarding the "output value of the center beam L1", the "output value of the ring beam L2", the "scanning amplitude of the laser beam L", and the "scanning frequency of the laser beam L" as described above.

[0034] The information indicating the "weldability" is information input based on the result of laser welding. When the welding result is good, information indicating "weldable" (indicated by "○" in the example of FIG. 6) is recorded, and when the welding result is not good, information indicating "unweldable" (indicated by "×" in the example of FIG. 6) is recorded. That is, each performance data table TB stores not only the welding performances with good welding results but also the welding performances with poor welding results.

[0035] The control unit 41 comprehensively controls the entire laser welding system 1 and includes functional units such as an interval detection unit 41a, a parameter determination unit 41b, and a signal generation unit 41c. Each function of the control unit 41 is realized by an arithmetic processing device (not shown) such as a CPU included in the control unit 41.

[0036] The gap detection unit 41a analyzes the optical interference signal input from the optical interferometer 3 to detect the butting gap G at a predetermined position P1 (Fig. 7) of the welded member M. Here, as shown in Fig. 7, the predetermined position P1 is located on the upstream side in the welding direction Dx with respect to the welding reference position P2 on the welded member M of the laser beam L, and the distance D1 from the predetermined position P1 to the welding reference position P2 in the welding direction Dx is set to, for example, 2.0 mm. Here, the welding reference position P2 refers to the processing point on the welded member M when the laser beam L is irradiated from the laser irradiation unit 7 in a direction perpendicular to the surface Ms of the welded member M (a direction parallel to the Z direction), and usually coincides with the intersection of the butting line A and the optical axis of the condenser lens 72. And the welding reference position P2 corresponds to the centers C of the irradiation patterns N1, N2 as shown in Figs. 2 and 3, and the welding reference position P2 is the center of the scanning pattern of the laser beam L.

[0037] The parameter determination unit 41b refers to the welding database DB and determines welding parameters based on the welding conditions and the butting gap G detected by the gap detection unit 41a. The signal generation unit 41c generates and outputs a control signal based on the welding parameters determined by the parameter determination unit 43. The control signal generated by the signal generation unit 41c includes a center output control signal indicating the output value of the center beam L1, a ring output control signal indicating the output value of the ring beam L2, and a scanning control signal indicating the scanning amplitude and scanning frequency of the laser beam L. These control signals are converted from digital signals to analog signals (voltage signals) by a D / A converter (not shown) and input to the welding apparatus 2. More specifically, the center output control signal and the ring output control signal are input to the laser oscillator 6, and the scanning control signal is input to the laser irradiation unit 71.

[0038] As a result, in the laser oscillator 6, the first and second laser oscillators 61 and 62 are controlled based on the input center beam control signal and ring beam control signal. From the first laser oscillator 61, a center beam L1 (first laser beam) with an output value corresponding to the voltage value of the center beam signal represented by the center beam control signal is oscillated. From the second laser oscillator 62, a ring beam L2 (second laser beam) with an output value corresponding to the voltage value of the ring beam control signal represented by the ring beam control signal is oscillated. Further, in the laser irradiation unit 7, the X-axis motor 71a and the Y-axis motor 71b are controlled based on the input scanning control signal, and the laser beam L is scanned on the member M to be welded with a scanning amplitude and a scanning frequency indicated by the scanning control signal (a scanning amplitude corresponding to the amplitude of the scanning control signal and a scanning frequency corresponding to the frequency of the scanning control signal).

[0039] Next, the operation of the laser welding system 1 according to this embodiment will be described. FIG. 8 is a flowchart showing the welding condition setting process executed in the laser welding system 1, and this welding condition setting process is realized by the control unit 41 executing a predetermined program read from the memory 42.

[0040] In the welding condition setting process, first, a welding condition input screen (not shown) is displayed on the display unit 44 to allow the operator to input welding conditions (S1). These welding conditions include the material and thickness T1 of the first metal member M1, the material and thickness T2 of the second metal member, the scanning pattern of the laser beam L, and the welding speed, and the operator can set and input the welding conditions via the operation input unit 43.

[0041] When welding conditions are input (S2: YES), the welding database DB (welding condition data table TA) is referred to, and the performance data table TB corresponding to the input welding conditions is selected (S3). At the same time, the initial values of the welding parameters corresponding to the input welding conditions are selected (S4), and the process ends. The information regarding the thus input and selected welding conditions, performance data table TB, and initial values of the welding parameters is stored in the memory 42. In the subsequent laser welding process, the control device 4 controls the laser irradiation unit 7 to scan the laser beam L in the scanning pattern set and input in S1, and controls the drive mechanism 5 to move the laser irradiation unit 7 relative to the member M to be welded at the welding speed set and input in S1.

[0042] Figure 9 is a flowchart for explaining the welding parameter adjustment process executed during laser welding. The flowchart shown in Figure 9 is executed by the control unit 41 when the laser welding system 1 is performing laser welding under the welding conditions set and input in the welding condition input process. Note that the initial welding parameters at the start of laser welding are the welding parameters selected in S4 of Figure 8, and the performance data table TB referred to in each step of the welding parameter adjustment process is the performance data table TB selected in S3 of Figure 8. Here, it will be described assuming that the performance data table TB1 shown in Figure 6 is the currently selected performance data table TB.

[0043] In the welding parameter adjustment process, first, the interference signal acquired from the interferometer 3 is analyzed to detect the butting interval G (S11). Next, it is determined whether the currently detected butting interval G has changed from the previously detected butting interval G (S12). If there is no change in the butting interval G, that is, if the currently detected butting interval G matches the previously detected butting interval G (S12: NO), the process returns to S11, and the welding parameters are not changed, and the current welding parameters are continuously maintained.

[0044] On the other hand, if there is a variation in the butting interval G (S12: YES), the value of the butting interval G detected this time is set to the variable i (S13), and it is determined whether the welding record corresponding to the butting interval i is stored in the selected record data table TB1 (S14). As a result, if it is determined that it is stored (S14: YES), it is determined whether there is a "weldable" one (one with "○" for weldability) in the welding record corresponding to the butting interval i (S15). If there is a "weldable" one (S15: YES), it is determined whether there is only one "weldable" welding record (S16). If there is only one (S16: YES), the welding parameters are changed to the welding parameters in the one welding record (S17). As a result, the control device 4 controls the welding device 2 with the changed welding parameters. Then, it returns to S11.

[0045] For example, if the butting interval G detected in S11 is 0.5 mm and is different from the previous detection value (S12: YES), the welding record corresponding to the butting interval i = 0.5 is stored in the record data table TB1 (Fig. 6) (S14: YES). Since there is one "weldable" one in the welding record corresponding to the butting interval i = 0.5 (only the welding record of "NO.1" is "○") (S15: YES, S16: YES), the welding parameters are changed to the welding parameters in the welding record (S17).

[0046] On the other hand, if it is determined in S16 that there are multiple "weldable" welding records (S16: NO), among the multiple welding records, the one with the highest output value of the center beam is searched for (S18), and it is determined whether there is only one with the highest output value of the center beam (S19). As a result, if there is only one (S19: YES), the welding parameters are changed to the welding parameters in the one welding record (S17). On the other hand, if there are multiple welding records with the highest output value of the center beam (S19: NO), the welding record with the highest output value of the ring beam is searched for among the multiple welding records (S20).

[0047] Next, it is detected whether there is only one welding result with the highest output value of the ring beam (S21). If there is only one (S21: YES), the process proceeds to S17, and the welding parameters are changed to the welding parameters of the single welding result (S17). On the other hand, if there are multiple welding results with the highest output value of the ring beam (S21: NO), among the multiple welding results, the one with the largest scanning amplitude is searched for (S22), and it is determined whether there is only one with the largest scanning amplitude (S23).

[0048] As a result, if only one welding result is searched (S23: YES), the process proceeds to S17, and the welding parameters are changed to the welding parameters in the single welding result (S17). On the other hand, if it is determined in S23 that multiple welding results are searched (S23: NO), among the multiple welding results, the welding result with the highest scanning frequency is searched for (S24), the process proceeds to S17, and the welding parameters are changed to the welding parameters of the welding result (S17).

[0049] For example, in the example of FIG. 6, since there are three welding results corresponding to the butting interval i = 0.15 and determined to be "weldable" (S15: YES, S16: NO), the one with the highest output value of the center beam is searched for among these three welding results (S18). Among these three welding results, the highest output value of the center beam is "460.0", and since there is only one (welding result of No. 2) with the output value of the center beam being "460.0" (S21: YES), the welding parameters are changed to the welding parameters of the single welding result (S17).

[0050] Also, in the example of FIG. 6, since there are three welding records corresponding to the butting interval i = 0.1 and marked as "weldable" (S15: YES, S16: NO), the one with the highest output value of the center beam is searched for among these three welding records (S18). Among these three welding records, the highest output value of the center beam is "460.0", and since there are two welding records (NO.2 and NO.3) with the center beam output value of "460.0" (S19: NO), the one with the highest output value of the ring beam is searched for among these two welding records (S20). Among these two welding records, the highest output value of the ring beam is "550.0", and since there is only one welding record (NO.3 welding record) with the ring beam output value of "550.0" (S21: YES), the welding parameters are changed to the welding parameters of the said one welding record (S17).

[0051] On the other hand, in S15, when there is no welding record marked as "weldable" (i.e., all are "×") (S15: NO), it is determined whether there is a butting interval larger than the butting interval i stored in the performance data table TB1 being selected (S25). As a result, if it is determined that there is no such storage (S25: NO), the process returns to S11, and if it is determined that there is such storage (S25: YES), the value of the butting interval one level higher than the butting interval i is set to the variable i (S26), and the process returns to S15.

[0052] Here, the "butting interval one level higher than the butting interval i" refers to the butting interval that is larger than the butting interval i among the butting intervals stored in the performance data table TB1 being selected and is the butting interval closest to the butting interval i. For example, in the example of FIG. 6, the butting interval one level higher than the butting interval i = 0.15 is the butting interval 0.2.

[0053] Also, in S14, when it is determined that there is no welding record corresponding to the butting interval i stored (S14: NO), the process proceeds to S25.

[0054] Thus, in this embodiment, by repeatedly executing the processes of S11 to S26 during laser welding, the welding parameters are adjusted in real time according to the butting interval G. That is, when the welding parameters are changed at S17 in FIG. 9, the center beam control signal, the ring beam control signal, and the scanning control signal output to the welding apparatus 2 reflect the changed welding parameters, and the laser oscillator 6 and the laser irradiation unit 7 are driven with the changed welding parameters. As a result, the center beam L1 with an output value corresponding to the center beam control signal is oscillated from the first laser oscillator 61, the ring beam L2 with an output value corresponding to the ring beam control signal is oscillated from the second laser oscillator 62, and the laser beam L is scanned on the workpiece M at the scanning amplitude and the scanning frequency indicated by the scanning control signal.

[0055] And since the distance D1 from the predetermined position P1, which is the detection location of the butting interval G, to the welding reference position P2 is set short (for example, to 2.0 mm), it is possible to suppress a large difference in the butting interval G between the measurement time and the welding time, and welding can be performed with more appropriate welding parameters according to the butting interval G.

[0056] Further, since the welding parameters include the output value of the center beam L1, the output value of the ring beam L2, the scanning amplitude of the laser beam L, and the scanning frequency of the laser beam L, laser welding can be performed better as compared with the case where only the scanning amplitude is adjusted, for example. Also, since the welding speed is maintained constant even when the butting interval G fluctuates, the welding speed is not sacrificed due to the butting interval G.

[0057] In this embodiment, the distance D1 from the predetermined position P1 to the welding reference position P2 is set to 2.0 mm, but the present invention is not limited thereto. However, the distance D1 is preferably 5.0 mm or less, and more preferably 2.0 mm or less. This is because if the distance D1 exceeds 5.0 mm, there is a high possibility that the butting interval G will deviate between the measurement time and the welding time, and welding with suitable welding parameters may not be possible.

[0058] That is, the shorter the time (hereinafter referred to as "conveying time") required for the welded member M to move relative to the laser irradiation unit 7 by a distance D1, the lower the possibility that the butting interval G will deviate between the measurement time and the welding time due to the influence of processing heat. The conveying time varies depending on the welding speed. For example, when the distance D1 is set to 2.0 mm, if the welding speed is 2 m / min, the conveying time is 60 ms, and if the welding speed is 5 m / min, the conveying time is 24 ms, and the occurrence of the deviation of the butting interval G as described above can be effectively reduced.

[0059] Here, although it takes a certain processing time to change the welding parameters based on the butting interval G, it is preferable that the conveying time and the processing time match, and for this purpose, speeding up the processing time is required. In this regard, in the present embodiment, since the butting interval G is detected based on the optical interference signal from the optical interferometer 3, it is possible to speed up the processing time as compared with, for example, a method of detecting the butting interval G by image processing. Further, since the three control signals (center beam control signal, ring beam control signal, scanning control signal) to the welding apparatus 2 are each output as an analog signal, the processing time is also speeded up thereby. Note that the predetermined position P1 (distance D1 from the welding reference position P2 to the predetermined position P1) is preferably set as appropriate according to the processing time and the welding speed.

[0060] As described above, the laser welding system and the laser welding method according to the embodiment of the present invention have been described. However, the present invention is not limited to such an embodiment, and various modifications and corrections can be made without departing from the scope of the present invention.

[0061] For example, in the above embodiment, the welding condition data table TA and a plurality of performance data tables TB are stored in the welding database DB, but the data structure of the database DB is not limited to this, and any data structure may be used as long as the welding parameters can be determined based on the welding conditions and the butting interval G.

[0062] In addition, the determination of the welding parameters based on the butting interval G is not limited to the method described above, and it may also use artificial intelligence constructed using an expert system, a neural network, or the like.

[0063] Furthermore, in the above embodiment, the welding parameters adjusted according to the butting interval G include the output value of the center beam L1, the output value of the ring beam L2, the scanning amplitude of the laser beam L, and the scanning frequency of the laser beam L. However, the present invention is not limited thereto, and the welding parameters adjusted according to the butting interval G may include at least one of the output value of the center beam L1, the output value of the ring beam L2, the scanning amplitude of the laser beam L, and the scanning frequency of the laser beam L.

[0064] Also, the laser welding system 1 according to the above embodiment may be provided with a seam tracking function.

Explanation of Signs

[0065] 1 Laser welding system 2 Welding device 3 Interferometer 4 Control device (control means) 6 Laser oscillator 7 Laser irradiation unit A Butting line G Butting interval L Laser beam M Welded member M1 First metal member M2 Second metal member P1 Predetermined position P2 Welding reference position

Claims

1. A welding apparatus for laser-welding a workpiece to be welded, and control means for controlling the welding apparatus with predetermined welding parameters, comprising: The workpiece to be welded has a first metal member and a second metal member that are abutted against each other, The welding apparatus irradiates the surface of the workpiece to be welded while two-dimensionally scanning a laser beam, thereby welding the first metal member and the second metal member, The welding apparatus includes a laser oscillator for oscillating a laser beam, and a laser irradiation unit for scanning the laser beam and irradiating the workpiece to be welded, The control means changes the welding parameters based on the butting interval between the first metal member and the second metal member at a predetermined position upstream of the welding reference position in the welding direction, The welding reference position is a processing point on the workpiece to be welded when the laser beam is irradiated from the laser irradiation unit in a direction perpendicular to the surface of the workpiece to be welded, A laser welding system in which the distance from the predetermined position in the welding direction to the welding reference position is 5 mm or less.

2. The laser welding system according to claim 1, further comprising an optical interferometer that generates interference light between measurement light and reference light that are irradiated to and reflected from the workpiece to be welded, and detects the interference light as an optical interference signal, The control means detects the butting interval between the first metal member and the second metal member at the predetermined position based on the optical interference signal.

3. The laser beam has a center beam and a ring beam surrounding the center beam, The welding parameters include an output value of the center beam, an output value of the ring beam, a scanning amplitude of the laser beam, and a scanning frequency of the laser beam according to claim 1 or 2.

4. The control means changes the welding parameters based on the butting interval at the predetermined position and welding conditions set in advance by the user, The welding conditions include the plate thickness and material of the first metal member, the plate thickness and material of the second metal member, the welding speed, and the scanning pattern of the laser beam according to claim 3.

5. The control means has a database, In the database, the butting interval, the welding parameters, and information indicating the possibility of welding are stored in association with each other, The control means When welding parameters corresponding to the butting interval at the predetermined position are stored in the database in association with information indicating weldability, the welding apparatus is controlled with the welding parameters. The welding system according to claim 1 or 2, wherein when welding parameters corresponding to the butting interval at the predetermined position are not stored in the database in association with information indicating weldability, the welding apparatus is controlled with welding parameters corresponding to a butting interval larger than the butting interval at the predetermined position and stored in association with information indicating weldability.

6. The control means according to claim 5, wherein when welding parameters corresponding to the butting interval at the predetermined position are not stored in the database in association with information indicating weldability and welding parameters corresponding to a butting interval larger than the butting interval at the predetermined position are not stored in the database, the welding apparatus is continuously controlled with the current welding parameters.

7. A laser welding method for laser-welding by irradiating a surface of a weldment composed of a first metal member and a second metal member butt-jointed to each other with laser light based on welding parameters, detecting a butting interval of the weldment at a predetermined position on the upstream side in the welding direction from a welding reference position; changing the welding parameters according to the butting interval, wherein the laser light has a center beam and a ring beam surrounding the center beam, the welding parameters include an output value of the center beam, an output value of the ring beam, a scanning amplitude of the laser light, and a scanning frequency of the laser light, the welding reference position is a processing point on the weldment when the laser light is irradiated in a direction perpendicular to the surface of the weldment, and a distance from the predetermined position in the welding direction to the welding reference position is 5 mm or less.

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