Laser arc hybrid welding device

Abstract

The laser arc hybrid welding device provided by the present invention for joining dissimilar materials comprises: a laser irradiation device comprising a laser oscillator and a laser welding gun; and an arc welding device comprising a welding power supply and a welding torch. The arc welding device varies the arc output (welding current) at frequencies between f1 and f2. Frequency f1 is the frequency at which the period of output fluctuation in the welding direction is 12 mm when welding at a given welding speed, and frequency f2 is the frequency at which the period of output fluctuation is 2 mm. The welding speed is 0.8 m / min to 2.0 m / min.

Description

Technical Field

[0001] The present disclosure relates to a laser arc hybrid welding device that can be used for joining dissimilar materials. Background Art

[0002] Japanese Patent Application Laid-Open No. 2006-224146 discloses a dissimilar material joining method for joining aluminum or aluminum alloy materials (aluminum-based materials) to steel materials. In this dissimilar material joining method, friction stir welding is performed by inserting the pin of a rotating joining tool from the aluminum-based material side into the overlapping portion of the aluminum-based material and a steel material having an aluminum-based coating formed on its surface.

[0003] In addition, as another method for joining dissimilar materials, a method for joining dissimilar materials using rivets for joining dissimilar materials is described in Japanese Patent Application Laid-Open No. 2019-7623. In addition, a method for joining dissimilar materials using laser brazing is disclosed in Japanese Patent Application Laid-Open No. 2006-167725.

[0004] During welding of dissimilar materials (for example, joining hot-dip galvanized steel sheets such as GI and GA steel sheets to aluminum alloy sheets), intermetallic compounds (IMCs) are formed at the joint interface. Because IMCs are more brittle than the parent metals themselves, there is a risk of delamination of the joint and a reduction in joint strength at the sites where IMCs are formed.

[0005] While the friction stir welding method mentioned above physically destroys the intermetallic compounds, it also leaves a processing mark at the end of the weld. Furthermore, other methods for joining dissimilar materials also suffer from issues such as insufficient joint strength, complex joining processes, and increased operating costs during construction. Summary of the Invention

[0006] The present disclosure is made to solve the above-mentioned problems, and an object of the present disclosure is to achieve joining of dissimilar materials with high joining strength using a laser arc hybrid welding device.

[0007] The laser arc hybrid welding device disclosed herein is used for joining dissimilar materials and comprises: a laser irradiation device configured to irradiate a laser beam toward a joint; and an arc welding device configured to generate an arc between the joint and the joint. At least one of the laser irradiation device and the arc welding device is configured to vary the output from the device between a first frequency and a second frequency. The first frequency is such that, when welding at a given welding speed, the period of output variation in the welding direction is 12 mm. The second frequency is such that, when welding at a given welding speed, the period of output variation in the welding direction is 2 mm. The welding speed is 0.8 m / min to 2.0 m / min.

[0008] This laser arc hybrid welding device is used for joining dissimilar materials. In this process, cracks in the intermetallic compound formed at the joint interface can propagate along the joint interface, potentially causing delamination of the joint. This laser arc hybrid welding device, by welding under the aforementioned conditions, creates irregularities in the weld depth direction at intervals of approximately 2 mm to 12 mm in the welding direction, corresponding to the penetration shape of the base material and the location of the intermetallic compound formation. This reduces the propagation of cracks in the intermetallic compound compared to a situation where no irregularities are formed.

[0009] Furthermore, if the frequency is too low, sufficient irregularities cannot be formed, reducing the crack propagation suppression effect. On the other hand, if the frequency is too high, the heat input is evened out, preventing sufficient irregularities from being formed, reducing the crack propagation suppression effect. This laser arc hybrid welding device, by welding under the above conditions, can form appropriate irregularities. Therefore, this laser arc hybrid welding device can achieve high-strength joining of dissimilar materials.

[0010] The laser irradiation device may include an adjustment mechanism configured to adjust the shape of the irradiation area of ​​the laser beam. The adjustment mechanism may be configured to expand the irradiation area in the weld width direction compared to a case where the adjustment mechanism is not provided. By adjusting the shape of the irradiation area, the heat input from the laser beam in the width direction may have a predetermined distribution curve. The predetermined distribution curve is one in which the heat input in the center of the width direction is less than the heat input at the end portions of the width direction.

[0011] By installing the aforementioned adjustment mechanism, the laser irradiation area is expanded across the weld width, while suppressing heat input in the center of the width. This reduces the formation of intermetallic compounds and enables a wide weld bead width (described in detail later). As a result, joint strength is maintained.

[0012] The laser irradiation device may be configured to change the laser output at the above-mentioned frequency, and the arc welding device may be configured to generate an arc such that the average value of the welding current is constant.

[0013] Because the energy density of a laser is higher than that of an arc, varying the laser output can make the penetration shape and the unevenness of the intermetallic compound formation location rougher (rougher) than when varying the arc output. Therefore, this laser-arc hybrid welding device can effectively create unevenness in the penetration shape and the location where the intermetallic compound is formed.

[0014] Furthermore, the arc welding device may be configured to change the average value of the welding current at the above-mentioned frequency, and the laser irradiation device may be configured to irradiate the joint portion with laser light of a fixed output.

[0015] Arc welding devices generally have easier output adjustment than laser irradiation devices. Therefore, this laser arc hybrid welding device can easily form a penetration shape and irregularities in the formation position of intermetallic compounds.

[0016] Alternatively, the average value of the welding current at the above frequency may vary from 10A to 100A.

[0017] This makes it possible to easily and effectively form the penetration shape and the irregularities of the intermetallic compound generation position.

[0018] The foregoing and other objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a diagram showing the overall configuration of a laser arc hybrid welding device according to the first embodiment.

[0020] Figure 2 This is a diagram showing an example of a cross section of a joint portion in a fillet weld of a lap joint.

[0021] Figure 3 It indicates schematically Figure 2 A cross-section of the contact point along the direction of welding progress is shown.

[0022] Figure 4 This is a diagram showing experimental results showing the effect of suppressing crack propagation in the IMC layer by fluctuation of arc output.

[0023] Figure 5 As a comparative example, it schematically shows a cross section of a contact portion when the arc output and the laser output are fixed.

[0024] Figure 6 This is a diagram explaining the relationship between the frequency at which the arc output is changed and the welding speed.

[0025] Figure 7 This is a diagram showing an example of an output waveform of an arc welding device.

[0026] Figure 8 This is a diagram schematically showing a cross section of a contact portion along the welding progress direction when welding is performed using the laser hybrid welding device according to the second embodiment.

[0027] Figure 9 This is a diagram schematically showing the structure of a laser welding gun in a third embodiment.

[0028] Figure 10It is a diagram showing an example of the planar shape of the irradiation area.

[0029] Figure 11 This is a diagram showing the distribution of heat input in the weld width direction. DETAILED DESCRIPTION

[0030] The following describes the embodiments of the present disclosure in detail with reference to the accompanying drawings. Although multiple embodiments are described below, the idea of ​​combining the structures described in each embodiment as appropriate has been envisioned since the initial application. In addition, the same or corresponding parts in the figures are marked with the same reference numerals and their descriptions will not be repeated.

[0031] [Implementation Method 1]

[0032] Figure 1 : is a diagram showing the overall structure of a laser arc hybrid welding device according to the first embodiment of the present disclosure. Figure 1 The laser arc hybrid welding device 1 (hereinafter referred to as simply “hybrid welding device 1 ”) includes a welding torch 10 , a welding wire 20 , a welding power supply device 30 , a laser welding gun 40 , and a laser oscillator 60 .

[0033] This hybrid welding device 1 can be used for welding dissimilar materials. Dissimilar materials joining refers to the joining of dissimilar materials with different main components. For example, the hybrid welding device 1 can be used for welding hot-dip galvanized steel sheets, such as GI steel sheets and GA steel sheets, to aluminum alloy sheets. Aluminum alloy sheets are suitable not only for soft aluminum but also for hard aluminum, such as those in the JIS 5000 series (e.g., 5052), 6000 series (e.g., 6063), and 7000 series (e.g., 7075). The hybrid welding device 1 joins one and the other of the base materials 70 to be joined, for example, using a stacked fillet weld or a flare weld.

[0034] The welding torch 10 and the welding power supply 30 constitute an arc welding device that performs welding by generating an arc at the joint with the base material 70. The welding torch 10 supplies the welding wire 20 and a shielding gas (not shown) to the joint with the base material 70. The welding torch 10 receives welding current from the welding power supply 30, generates an arc 25 between the tip of the welding wire 20 and the joint with the base material 70, and supplies a shielding gas (argon gas, carbon dioxide gas, etc.) to the weld.

[0035] Welding power supply 30 generates a welding voltage and a welding current for arc welding, and outputs the generated welding voltage and welding current to welding torch 10. Welding power supply 30 also controls the feed speed of welding wire 20 in welding torch 10.

[0036] The laser welding gun 40 and the laser oscillator 60 constitute a laser irradiation device that performs welding by irradiating the joint portion of the base material 70 with laser light. The laser welding gun 40 receives laser light from the laser oscillator 60 and irradiates the joint portion of the base material 70 with laser light. The laser light from the laser welding gun 40 irradiates the vicinity of the arc 25 generated by the welding torch 10. In this hybrid welding device 1, the laser light is irradiated in front of the arc 25 in the welding direction. Irradiating the front of the arc 25 with laser light stabilizes the arc 25.

[0037] In hybrid welding device 1 according to the first embodiment, the output of the arc welding device, which is composed of welding torch 10 and welding power supply 30, is swung at a frequency between frequency f1 and frequency f2 (f2>f1). Specifically, when the welding current fluctuates instantaneously at a high frequency (e.g., approximately 100 Hz) each time a droplet transfer occurs, hybrid welding device 1 swung the average value of the welding current at a frequency between frequency f1 and frequency f2.

[0038] Here, frequency f1 is the frequency at which the period of output fluctuation in the welding direction becomes 12 mm when welding at a given welding speed. Frequency f2 is the frequency at which the period of output fluctuation in the welding direction becomes 2 mm when welding at a given welding speed. The given welding speed is 0.8 m / min to 2.0 m / min.

[0039] In this first embodiment, the fluctuation range of the average welding current is preferably set to a value between 10A and 100A. Furthermore, in this first embodiment, the output of the laser irradiation device, consisting of the laser welding gun 40 and the laser oscillator 60, is set to a fixed value. The following describes the reason for varying the output of the arc welding device in the hybrid welding device 1 as described above. Furthermore, the term "welding current" hereafter refers to the average welding current value unless otherwise specified. The output of the arc welding device may also be referred to simply as "arc output."

[0040] Figure 2 This is a diagram showing an example of a cross section of a joint in a fillet weld of a lap joint. Figure 2 The figure shows the direction of welding ( Figure 1 The cross section of the yz plane is perpendicular to the x direction.

[0041] refer to Figure 2 In this example, the base material (weld material) 70 includes a GI material 71 and an aluminum alloy plate 72 stacked on the GI material 71. A weld bead 73 is formed at the end of the aluminum alloy plate 72 on the GI material 71, where the weld bead 73 is joined to the GI material 71 at a contact portion 74.

[0042] During welding of dissimilar materials, intermetallic compounds are generated at the joint interface (contact area 74) during welding. In the case of dissimilar material joining of GI material 71 and aluminum alloy plate 72, the generated intermetallic compounds are alloys of aluminum and iron (e.g., FeAl, Fe3Al, Fe2Al5, etc.). Because intermetallic compounds are more brittle than the base material 70 (GI material 71 and aluminum alloy plate 72), there is a possibility of delamination of weld bead 73 at contact area 74, leading to a reduction in joint strength. Specifically, cracks propagate along the intermetallic compound generation layer, potentially causing weld bead 73 to delaminate at the boundary of the intermetallic compound generation layer.

[0043] The inventors of the present invention conducted various experiments to suppress cracking along the intermetallic compound formation layer and discovered that by fluctuating the arc output (welding current) between frequencies f1 and f2, with a period of output fluctuation in the welding direction of 2 mm to 12 mm, the progression of cracking along the intermetallic compound formation layer can be suppressed. This is described in detail below.

[0044] Figure 3 It indicates schematically Figure 2 The cross-section of the contact portion 74 shown is along the direction of welding progress. Figure 3 Shown along with Figure 2 The cross section of the xz plane is perpendicular to the y direction.

[0045] refer to Figure 3 An IMC layer 82 of an intermetallic compound is formed between the Fe layer 80 of the GI material 71 and the Al layer 81 of the weld bead 73. As described above, in the first embodiment, when the arc output (welding current) is fluctuated between frequencies f1 and f2, region 91 is a region where welding is performed with a relatively large arc output compared to region 92, and region 92 is a region where welding is performed with a relatively small arc output compared to region 91.

[0046] As shown in the figure, the Fe layer 80 has a deeper penetration in region 91 with high arc output, while the Fe layer 80 has a shallower penetration in region 92 with low arc output. Consequently, the penetration of the Fe layer 80 becomes uneven in response to fluctuations in the arc output, and the formation position of the IMC layer 82 formed between the Fe layer 80 and the Al layer 81 also becomes uneven in response to fluctuations in the arc output. This suppresses crack propagation in the x-direction in the IMC layer 82, which is relatively brittle compared to the Fe layer 80 and the Al layer 81.

[0047] Furthermore, if the frequency of the arc output change is set too low, the interval L between the concavities and convexities of the IMC layer 82 becomes longer, thereby reducing the effect of suppressing the propagation of cracks in the IMC layer 82. On the other hand, if the frequency of the arc output change is set too high, the heat input of the arc is averaged, so sufficient concavities and convexities cannot be formed, and the effect of suppressing the propagation of cracks is reduced.

[0048] Figure 4 This graph shows experimental results demonstrating the effect of arc output fluctuation on suppressing crack propagation in the IMC layer 82. The experiment involved lap fillet welding of a 2.0 mm thick upper plate (A6063) hard aluminum alloy and a 1.6 mm thick lower plate (SGCC). The experiment was conducted under the conditions of a 2 kW laser output, 100 A-18 V arc welding setting, and a welding speed of 1.5 mm / min. Furthermore, the laser output was kept constant while the arc output (welding current) was fluctuated during welding, and microscopic observations of the bottom of the molten zone were performed.

[0049] exist Figure 4 In FIG, an IMC layer 82 is generated in a concave-convex or wavy manner along the joint interface at each swing frequency of the arc output, indicating whether the progress of cracks originating from the intermetallic compound is suppressed and the period of output variation in the welding direction (interval between concave and convex).

[0050] refer to Figure 4 The result "○" indicates that the IMC layer 82 is formed in an uneven or wavy pattern along the joint interface, and the progress of cracks caused by the intermetallic compound is suppressed. The result "△" indicates that although the IMC layer 82 is formed in an uneven or wavy pattern along the joint interface, the progress of cracks caused by the intermetallic compound is not suppressed. The result "×" indicates that sufficient unevenness is not formed at the joint interface, and the progress of cracks caused by the intermetallic compound is not suppressed.

[0051] according to Figure 4 The results indicate that the crack propagation suppression effect in the IMC layer 82 occurs when the cycle of output fluctuations in the welding direction (intervals between bumps and depressions) is approximately 2 mm to 12 mm. Therefore, in the hybrid welding device 1 according to the first embodiment, the arc output is oscillated so that the cycle of output fluctuations in the welding direction is 2 mm to 12 mm.

[0052] In addition, refer again Figure 3When the arc output is varied, if the output variation range is too small, the difference between the penetration depths of region 91 and region 92 becomes small, and no effective unevenness is produced in the formation position of IMC layer 82. In this hybrid welding device 1, since the arc output (welding current) is periodically varied within a variation range of approximately 10A to 100A, unevenness can be effectively produced in the penetration shape and the formation position of IMC layer 82.

[0053] Figure 5 : is a diagram schematically showing a cross section of the contact portion 74 when the arc output and the laser output are fixed as a comparative example. Figure 5 With the above Figure 3 correspond.

[0054] refer to Figure 5 When the arc output and the laser output are constant, the penetration shape (penetration depth) of the Fe layer 80 is constant, and the IMC layer 82 generated between the Fe layer 80 and the Al layer 81 also becomes a flat planar shape. In this case, in the IMC layer 82, which is relatively brittle compared to the Fe layer 80 and the Al layer 81, there is a possibility that the cracks that have occurred once will propagate and progress along the planar IMC layer 82. In response to this, in the first embodiment, as shown in FIG. Figure 3 As shown, since the IMC layer 82 is formed at a concave and convex position, cracks can be suppressed from propagating along the IMC layer 82 .

[0055] Figure 6 This is a graph showing the range of frequencies that cause the arc output to swing. Figure 6 In the figure, the vertical axis represents the frequency (Hz) at which the arc output is swung, and the horizontal axis represents the welding speed (m / min) of the hybrid welding device 1. In this example, the welding speed can be set within a range of 0.8 m / min to 2.0 m / min, and the effective swung frequency of the arc output within this welding speed range is shown.

[0056] refer to Figure 6 Line L1 represents the frequency f1 when the period of output variation in the welding direction (the uneven spacing L of the IMC layer 82) is 12 mm. At a welding speed of 0.8 m / min, the frequency f1 is 1.1 Hz, and at a welding speed of 2.0 m / min, the frequency f1 is 2.8 Hz.

[0057] Line L2 represents frequency f2 when the cycle of output fluctuation in the welding direction (interval L between the unevenness of IMC layer 82) is 2 mm. At a welding speed of 0.8 m / min, frequency f2 is 6.7 Hz, and at a welding speed of 2.0 m / min, frequency f2 is 16.7 Hz. By welding within the conditions within the area S enclosed by the line, the arc output can be swung, creating unevenness in the IMC layer 82 with intervals of 2 mm to 12 mm in the welding direction.

[0058] Furthermore, when varying the arc output, if the output variation is too small, sufficient irregularities may not be formed. In this hybrid welding device 1, the average value of the welding current is periodically varied within a range of approximately 10 A to 100 A, enabling the formation of an IMC layer 82 having sufficient irregularities at the joint interface.

[0059] Figure 7 This is a diagram showing an example of an output waveform of the arc welding device in the first embodiment. Figure 7 In the figure, the waveforms of the welding current Iw and the welding voltage Vw when short-circuit transfer type welding is performed are shown as an example. Figure 7 The term "welding current" in the table does not refer to the average value but the actual current value.

[0060] refer to Figure 7 , welding power supply unit 30( Figure 1 ) performs constant voltage control to adjust welding current Iw so that welding voltage Vw reaches set voltage Vset. In addition, wire feeding speed Wf is determined by set current Iset.

[0061] Welding current Iw and welding voltage Vw fluctuate instantaneously each time a droplet transfers. Specifically, for example, at time t2, welding wire 20 contacts base metal 70, short-circuiting the two. This causes welding voltage Vw to drop to approximately 0V.

[0062] Since welding power supply 30 performs constant voltage control, welding current Iw increases sharply in response to a decrease in welding voltage Vw. Furthermore, as welding current Iw increases, resistance heating occurs in welding wire 20, so welding voltage Vw gradually increases.

[0063] When welding wire 20 begins to melt due to resistance heating, the pinching effect caused by welding current Iw causes the melted wire 20 to become thinner. This increases the resistance of welding wire 20, further accelerating resistance heating. As a result, welding wire 20 melts, generating an arc between welding wire 20 and base material 70.

[0064] When an arc is generated, welding wire 20 is heated during the short-circuit period from time t2 to t3, so that welding wire 20 rapidly ignites. As a result, the arc length increases, and welding voltage Vw rises rapidly at time t3.

[0065] Since welding power supply 30 performs constant voltage control, welding current Iw decreases as welding voltage Vw increases. Furthermore, due to the decrease in welding current Iw and the advancement of welding wire 20, welding wire 20 contacts base material 70 at time t4, and welding wire 20 and base material 70 are short-circuited again.

[0066] Thus, welding current Iw and welding voltage Vw fluctuate instantaneously (e.g., at about 100 Hz) every time droplet transfer occurs. In hybrid welding device 1 according to the first embodiment, the arc welding device operates so that average current Iave, representing the average value of welding current Iw, fluctuates at frequency f.

[0067] Specifically, during the low (L) output period and the high (H) output period, which alternate at a frequency f, the set current Iset is set so that the average current Iave varies by a predetermined amount, and the set voltage Vset is set so that the average current Iave reaches the set current Iset. Furthermore, the welding current Iw is adjusted so that the welding voltage Vw reaches the set voltage Vset. The predetermined variation range of the average current Iave is, for example, 10A to 100A.

[0068] Furthermore, during both the low-output and high-output periods, when constant voltage control (set voltage Vset is constant) is performed while the wire feed speed Wf is constant (i.e., set current Iset is constant), the arc length and average current Iave are maintained constant due to the arc length's self-control. Therefore, by appropriately setting set voltage Vset and set current Iset during both the low-output and high-output periods, average current Iave can be controlled to a constant desired value.

[0069] Furthermore, arc welding is not limited to repeated short circuits and arc short circuit transitions; pulse welding with repeated peak and base periods is also possible. In pulse welding, the set voltage Vset is periodically changed so that the average current Iave varies at a frequency f, with the amplitude varying between 10A and 100A. Furthermore, the peak and base currents are modulated so that the average value Vave of the welding voltage Vw reaches the set voltage Vset, resulting in the average current Iave being controlled to the target value.

[0070] As described above, in this first embodiment, by fluctuating the arc output so that the cycle of output fluctuation in the welding direction is 2 mm to 12 mm, irregularities are formed in the penetration shape of the base material and in the IMC layer 82. This can suppress crack propagation in the intermetallic compound generation layer compared to a case where irregularities are not formed.

[0071] Furthermore, in the first embodiment, the output of the arc welding device is varied to form the unevenness of the penetration shape and the location of intermetallic compound formation. Since arc welding devices generally have easier output adjustment than laser irradiation devices, the first embodiment facilitates the formation of the unevenness described above.

[0072] [Implementation Method 2]

[0073] In the first embodiment, the output of the arc welding device composed of the welding torch 10 and the welding power supply 30 is periodically varied. In the second embodiment, the output of the laser irradiation device composed of the laser welding gun 40 and the laser oscillator 60 is periodically varied.

[0074] Since the energy density of laser light is higher than that of arc light, varying the laser output can make the penetration shape and the unevenness of the intermetallic compound generation position rougher (rougher) than when varying the arc output.

[0075] Reference again Figure 1 In the hybrid welding device 1 according to the second embodiment, the output of the laser irradiation device, which comprises the laser welding gun 40 and the laser oscillator 60, is varied between a frequency f1 and a frequency f2 (f2>f1). To this end, the laser oscillator 60 varies the laser output at the aforementioned frequency. For example, the laser oscillator 60 may oscillate a pulsed laser beam at the aforementioned frequency with a duty cycle of 50%. Furthermore, in this second embodiment, the output of the arc welding device, which comprises the welding torch 10 and the welding power supply 30, is kept constant.

[0076] Figure 8 1 is a diagram schematically showing a cross section of a contact portion 74 along the welding direction when welding is performed using the laser hybrid welding device 1 according to the second embodiment. Figure 8 With the above Figure 3 That is, in this Figure 8 It is also shown that along with Figure 2 The cross section of the xz plane is perpendicular to the y direction.

[0077] refer to Figure 8In the second embodiment, when welding is performed by periodically changing the laser output, region 93 is a region where welding is performed with a relatively large laser output compared to region 94 , and region 94 is a region where welding is performed with a relatively small laser output compared to region 93 .

[0078] As shown in the figure, the Fe layer 80 has a deeper penetration in region 93 where the laser output is high, and a shallower penetration in region 94 where the laser output is low. Consequently, the penetration depth of the Fe layer 80 becomes uneven in response to the periodic changes in laser output, and the position of the IMC layer 82 formed between the Fe layer 80 and the Al layer 81 also becomes uneven in response to the periodicity of the laser output. This suppresses crack propagation in the x-direction in the IMC layer 82, which is relatively brittle compared to the Fe layer 80 and the Al layer 81.

[0079] Furthermore, in this second embodiment, since the laser output, which has a higher energy density than the arc output, is varied, the resulting unevenness changes more steeply (rougher unevenness) compared to the case where the arc output is fluctuated as in the first embodiment. Therefore, the penetration shape and the unevenness of the IMC layer 82 can be effectively formed.

[0080] Furthermore, in this second embodiment, if the frequency of laser output variation is too low, the interval L between the irregularities of the IMC layer 82 becomes longer, thereby reducing the effect of suppressing crack propagation in the IMC layer 82. On the other hand, if the frequency of laser output variation is too high, the heat input of the laser is averaged, and sufficient irregularities cannot be formed, reducing the effect of suppressing crack propagation. In the hybrid welding device 1 according to this second embodiment, by varying the laser output so that the period of output variation in the welding direction is 2 mm to 12 mm, appropriate irregularities can be formed in the penetration shape and the location of the IMC layer 82.

[0081] As described above, according to the second embodiment, the output of the high-energy-density laser light is varied to form the penetration shape of the base material and the irregularities in the IMC layer 82 . Therefore, the penetration shape and the irregularities in the IMC layer 82 can be effectively formed.

[0082] [Implementation Method 3]

[0083] If the heat input (J) to the joint is high, the solidification rate of the molten pool will slow down, resulting in an increase in the amount of intermetallic compounds generated during welding. Lasers are generally adjusted to focus on the irradiated area in order to increase the irradiation energy density in the irradiated area and effectively melt the components. However, in this case, the heat input to the joint increases, and as mentioned above, there is a possibility that the joint strength will decrease due to the increased amount of intermetallic compounds generated.

[0084] To this end, one approach is to reduce the amount of heat input to suppress the formation of intermetallic compounds. However, reducing heat input reduces the joint area between the weld bead and the base metal, potentially reducing joint strength. This reduction in joint strength can be mitigated by increasing the weld bead width.

[0085] To reduce heat input, one approach is to defocus the laser. However, simply defocusing the laser's focus results in a generally circular planar shape of the laser irradiation area. Consequently, heat input distribution across the weld width is highest in the center and decreases toward the ends. Consequently, heat input is insufficient in areas away from the center (e.g., the widthwise ends), potentially leading to insufficient joint strength.

[0086] To this end, in this third embodiment, the laser welding gun 40 includes an adjustment mechanism for adjusting the shape of the irradiation area of ​​the irradiated laser and the distribution of the irradiation energy density of the laser in the irradiation area. This adjustment mechanism expands the irradiation area in the width direction of the weld compared to a case where the adjustment mechanism is not provided. Furthermore, the adjustment mechanism adjusts the shape of the irradiation area and the distribution of the irradiation energy density so that the distribution of the heat input (J) of the laser in the weld width direction becomes a distribution curve in which the heat input in the center of the width direction is less than the heat input in the end portions of the width direction. In this third embodiment, a diffractive optical element (DOE) is provided in the laser welding gun 40 as such an adjustment mechanism. By providing such an adjustment mechanism (DOE), the heat input to the joint portion is suppressed, thereby suppressing the amount of intermetallic compounds generated, and a wide weld bead width can be formed. As a result, the joint strength of the joint portion can be ensured.

[0087] In addition, in this embodiment 3, the output of the laser irradiation device composed of the laser welding gun 40 and the laser oscillator 60 is set to be fixed, and in the arc welding device composed of the welding torch 10 and the welding power supply device 30, the average value of the welding current is caused to fluctuate at a frequency between frequency f1 and frequency f2.

[0088] Figure 9 : is a diagram schematically showing the structure of a laser welding gun 40 in the third embodiment. Figure 9 The laser welding gun 40 includes a DOE 41 and a lens 42 . The laser beam outputted from the laser oscillator 60 is irradiated onto the base material 70 through the DOE 41 and the lens 42 , thereby forming an irradiation region 100 on the base material 70 .

[0089] DOE 41 utilizes diffraction to process the laser light received from laser oscillator 60 into a desired beam pattern. Specifically, DOE 41 geometrically disperses the incident light received from laser oscillator 60 and shapes the irradiated laser light, thereby widening the irradiated area 100 on base material 70 and forming a roughly rectangular shape compared to a case without DOE 41.

[0090] The lens 42 focuses the laser light processed by the DOE 41 and outputs it to the base material 70 .

[0091] Figure 10 1 is a diagram showing an example of the planar shape of the irradiation area 100. Figure 10 In FIG, the X-axis direction represents the traveling direction of the laser welding gun 40, and the Y-axis direction represents the width direction of the weld. Figure 10 , the laser is processed by DOE41 so that the irradiation area 100 becomes a roughly rectangular shape.

[0092] The dotted lines represent the distribution of the laser irradiation energy density. As shown in the figure, in the irradiation area 100, the laser is shaped by the DOE 41 so that the irradiation energy density increases from the center C in the width direction (Y-axis direction) toward the ends in the width direction.

[0093] In addition, in this example, the irradiation area 100 is set as an area in which the opposite sides parallel to the travel direction (X-axis direction) of the laser welding gun 40 are short sides and the opposite sides parallel to the width direction (Y-axis direction) are long sides. The irradiation area 100 can be a roughly square, or the opposite sides parallel to the travel direction (X-axis direction) of the laser welding gun 40 can be set as long sides.

[0094] Figure 11 This is a diagram showing the distribution of heat input in the welding width direction. Figure 11 In the figure, (a) shows the distribution of heat input from the laser, and (b) shows the distribution of heat input from the arc. (c) shows the distribution of the sum of the heat input from the laser and the arc. In other words, (c) shows the distribution of the total heat input from the laser and the arc. In each figure, the vertical axis represents heat input Q, and the Y axis represents the width of the weld. The heat input Q at each point along the width represents the total heat input (J) from the start to the end of the weld.

[0095] refer to Figure 11 , by having Figure 10The distribution of heat input due to laser irradiation in the irradiation area 100 shown in FIG. (a) shows a distribution curve in which heat input is low in the center C in the width direction and increases toward the ends. For reference only, assuming the planar shape of the laser irradiation area is circular, even if the irradiation energy density is low in the center and high in the peripheral portions of the irradiation area, the heat input is likely to increase in the center in the width direction and decrease toward the ends.

[0096] The distribution of heat input from the arc, as shown in (b), is characterized by a high heat input in the center C in the width direction and a decreasing heat input toward the ends. Consequently, the heat distribution of the sum of the heat input from the laser and the heat input from the arc is roughly uniform across the width, as shown in (c).

[0097] In other words, the heat input distribution curve based on the laser is determined by taking into account the heat input distribution curve based on the arc, so that the heat distribution curve of the sum of the heat input by the laser and the heat input by the arc becomes substantially uniform in the width direction. Furthermore, the shape of the laser irradiation area 100 and the irradiation energy density distribution ( Figure 10 The shape and irradiation energy density distribution shown in FIG. 1 determine the structure of DOE 41 that realizes such an irradiation area 100.

[0098] Alternatively, DOE41 can be constructed so that a distribution curve of the laser-based heat input as shown in (a) can be obtained, and the output of the welding torch 10 can be adjusted by the welding power supply device 30 so that the distribution curve of the heat distribution of the sum of the laser-based heat input and the arc-based heat input becomes approximately uniform in the width direction.

[0099] Since the mechanical properties of a weld are determined by the heat input to the weld and the heat distribution of each welding process, adjusting the sum of the heat input from the laser and the arc as described above can achieve the desired mechanical properties in the weld. Furthermore, by making the sum of the heat input from the laser and the arc uniform across the width, a high-quality weld bead can be formed in which the generated intermetallic compounds are not concentrated in one part.

[0100] Furthermore, particularly in welding dissimilar materials (e.g., welding aluminum alloy plates to hot-dip galvanized steel plates), it is necessary to control the amount and distribution of molten metal in addition to controlling the amount and distribution of intermetallic compounds. In this embodiment, by adjusting the distribution curve of the laser-based heat input using the aforementioned adjustment mechanism, it is possible to adjust the melting of the base material, the width of the weld bead, and the depth (penetration depth) of the molten pool and its distribution. Furthermore, by adjusting the output of the welding torch 10 using the welding power supply 30, it is possible to adjust the melting of the welding wire and the amount of molten metal.

[0101] As described above, according to the third embodiment, by setting Figure 10 The widthwise distribution of heat input in the DOE41 of the laser irradiation area shown is Figure 11 The distribution curve shown in FIG. Therefore, the heat input to the joint is suppressed, thereby suppressing the amount of intermetallic compound formation, and a wide weld bead width can be formed. As a result, the joint strength of the joint can be ensured.

[0102] Furthermore, according to this third embodiment, by adjusting the widthwise distribution (distribution curve) of the sum of the heat input from the laser and the heat input from the arc, desired mechanical properties can be obtained in the weld. Furthermore, by making the widthwise distribution of the sum of the heat input from the laser and the heat input from the arc uniform across the width, a high-quality weld bead can be formed without the generated intermetallic compounds being concentrated in one part.

[0103] Furthermore, by adjusting the distribution curve of the laser-induced heat input using the aforementioned adjustment mechanism (DOE 41), the melting of the base material can be adjusted, and the weld bead width, molten pool depth (penetration depth), and their distribution can be adjusted. Furthermore, by adjusting the output of the welding torch 10 using the welding power supply 30, the melting of the welding wire and the amount of molten metal can be adjusted.

[0104] In the third embodiment described above, the arc output (welding current) is periodically changed. However, as described in the second embodiment, the laser output may be periodically changed.

[0105] In the above-mentioned embodiment 3, the DOE 41 is formed Figure 10 Although the laser irradiation area 100 is shown in the figure, a laser scanning device that can scan the laser irradiated on the base material 70 on the base material 70 can be provided on the laser welding gun instead of the DOE. In addition, the irradiation area similar to that of the third embodiment can be formed by scanning the laser with the laser scanning device.

[0106] In addition, in each of the above-mentioned embodiments, arc welding is performed using a consumable electrode method (MAG welding, MIG welding, etc.) using the welding wire 20. However, a non-consumable electrode method (TIG welding, etc.) using a non-consumable electrode (tungsten, etc.) may be used instead of the welding wire 20.

[0107] In addition, in each of the above-described embodiments, while either the arc output (welding current) or the laser output is periodically varied, they can be combined to synchronously vary both the arc output and the laser output. This allows for more effective formation of the penetration profile and the irregularities of the IMC layer 82.

[0108] The embodiments of the present disclosure are described above, but the embodiments disclosed herein are illustrative in all respects and should not be considered restrictive. The technical scope of the present disclosure is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A laser arc hybrid welding device for joining dissimilar materials, characterized in that: have: a laser irradiation device configured to irradiate the joining portion with laser light; and An arc welding device configured to generate an arc between the joint portion, At least one of the laser irradiation device and the arc welding device is configured to change the output from the laser arc hybrid welding device at a frequency between a first frequency and a second frequency. The first frequency is a frequency at which the interval between the concavities and convexities in the welding direction becomes 12 mm when welding is performed at a given welding speed and the intermetallic compound layer generated at the joint interface accompanying welding becomes 12 mm. The second frequency is a frequency at which the interval between the concave and convex portions becomes 2 mm when welding is performed at the welding speed. The welding speed is 0.8 m / min to 2.0 m / min.

2. The laser arc hybrid welding device according to claim 1, characterized in that: The laser irradiation device includes an adjustment mechanism configured to adjust the shape of an irradiation area of ​​the irradiated laser light. The adjustment mechanism is configured to expand the irradiation area in the width direction of the weld compared to a case where the adjustment mechanism is not provided in the laser irradiation device, and to adjust the shape of the irradiation area so that the distribution of the heat input amount based on the laser in the width direction has a predetermined distribution curve. The predetermined distribution curve is a distribution curve in which the heat input amount in the center portion in the width direction is equal to or less than the heat input amount in the end portions in the width direction.

3. The laser arc hybrid welding device according to claim 1 or 2, characterized in that: The laser irradiation device is configured to change the laser output at the frequency. The arc welding device is configured to generate an arc in which the average value of the welding current is constant.

4. The laser arc hybrid welding device according to claim 1 or 2, characterized in that: The arc welding device is configured to cause the average value of the welding current to fluctuate at the frequency. The laser irradiation device is configured to irradiate the joining portion with laser light of a fixed output.

5. The laser arc hybrid welding device according to claim 4, characterized in that: The average value of the welding current at the frequency varies from 10A to 100A.

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