Busbar and method for manufacturing a busbar

Abstract

The bus bar is, for example, a bus bar having a plurality of members that are plate-shaped, and a welding portion that is linear and extends in a first direction, and that welds two members included in the plurality of members, wherein the welding portion is provided between substantially both ends of at least one of the two members in the first direction. In addition, in the bus bar, for example, it can be that both of the two members extend in the first direction and extend in the same direction that intersects the first direction. In addition, in the bus bar, for example, it can also be that one of the two members extends in the first direction and extends in a second direction that intersects the first direction, and the other of the two members extends in the first direction and extends in a third direction that intersects the first direction and the second direction.

Description

Technical Field

[0001] This invention relates to busbars and a method for manufacturing busbars. Background Technology

[0002] Previously, it was known that a busbar was formed by spot welding multiple components together at their contact points (e.g., Patent Document 1).

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 11-297372 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, in spot welding, there are situations where the joint strength of multiple components becomes insufficient.

[0008] Therefore, one of the objectives of this invention is to obtain, for example, a busbar with a novel improved structure, such as a busbar in which multiple components are joined by welding with higher bonding strength, and a method for manufacturing the busbar.

[0009] Solution for solving the problem

[0010] In the busbar of the present invention, for example, it is a busbar having a plurality of plate-shaped components and a linear welded portion extending along a first direction by welding two of the plurality of components, wherein the welded portion is disposed between approximately both ends of at least one of the two components in the first direction.

[0011] In the busbar, both components may extend along the first direction and in the same direction that intersects the first direction.

[0012] In the busbar, one of the two components may extend along the first direction and along a second direction that intersects the first direction, while the other component extends along the first direction and along a third direction that intersects both the first and second directions.

[0013] Alternatively, in the busbar, at least one of the two components may have a coating on its surface.

[0014] In the busbar, at least one of the two components may have a surface with concave and convex features.

[0015] In the busbar, the welded portion may also have: weld metal; and a heat-affected portion located around the weld metal, the weld metal having a first portion and a second portion, wherein the average cross-sectional area of ​​the crystal grains in the second portion along the depth direction of the welded portion is larger than that of the first portion.

[0016] In the busbar, the plurality of components may be made of either copper-based or aluminum-based metal materials.

[0017] In the busbar, the ratio of the depth of the weld portion in the thickness direction of the thinner component to the thickness of the thinner component may be 0.8 or more.

[0018] In the busbar, the thickness of the component may be 0.5 mm or more.

[0019] The method for manufacturing a busbar according to the present invention is, for example, a method for manufacturing a busbar having a plurality of plate-shaped components and a linear welded portion extending along a first direction by welding two of the plurality of components, wherein the welded portion is formed by irradiation with a laser comprising a plurality of beams.

[0020] In the method for manufacturing the busbar, the plurality of beams may also be formed by a beam shaper.

[0021] In the method of manufacturing the busbar, the plurality of light beams may include a light beam of a first laser with a wavelength of 800 nm or more and 1200 nm or less, and a light beam of a second laser with a wavelength of 550 nm or less.

[0022] In the manufacturing method of the busbar, the wavelength of the second laser may be 400 nm or more and 500 nm or less.

[0023] In the manufacturing method of the busbar, the plurality of components may also be formed by cutting the base material using laser cutting.

[0024] In the manufacturing method of the busbar, the plurality of components may also be formed by cutting a flat extrusion piece.

[0025] In the manufacturing method of the busbar, the welding of the welded part can also be controlled based on the images captured by the camera.

[0026] Invention Effects

[0027] According to the present invention, for example, a busbar with a novel structure that has been further improved, and a method for manufacturing the busbar, can be obtained. Attached Figure Description

[0028] Figure 1 This is an exemplary schematic diagram of the laser welding apparatus according to the embodiment.

[0029] Figure 2 This is a schematic perspective view of an example of a busbar that is being processed by a laser welding apparatus as an embodiment.

[0030] Figure 3 This is a schematic perspective view of an example of a busbar that is being processed by a laser welding apparatus as an embodiment.

[0031] Figure 4 This is a schematic perspective view of an example of a busbar that is being processed by a laser welding apparatus as an embodiment.

[0032] Figure 5 This is an exemplary schematic diagram showing a laser beam (spot) formed on the surface of the workpiece by the laser welding apparatus of the embodiment.

[0033] Figure 6 It is a graph showing the light absorption rate of each metal material relative to the wavelength of the irradiated laser.

[0034] Figure 7 This is an explanatory diagram illustrating the concept of the diffractive optical element included in the laser welding apparatus of the embodiment.

[0035] Figure 8 This is an illustrative and schematic cross-sectional view of the welded portion in the embodiment.

[0036] Figure 9 This is an illustrative and schematic cross-sectional view showing a portion of the welded portion of an embodiment.

[0037] Figure 10 This is an illustrative schematic diagram showing an example of the process of cutting multiple components from a base material by laser cutting in the manufacturing method of the busbar in the embodiment. Detailed Implementation

[0038] The following are exemplary embodiments of the present invention. The structure of the embodiments shown below, as well as the effects and results (effects) brought about by the structure, are examples. The present invention can also be implemented by structures other than those disclosed in the following embodiments. In addition, according to the present invention, at least one of the various effects (including derived effects) obtained by the structure can be obtained.

[0039] The embodiments shown below have the same structure. Therefore, based on the structure of each embodiment, the same function and effect are obtained based on the same structure. In addition, the same reference numerals are sometimes used to refer to these same structures below, and repeated descriptions are omitted.

[0040] Additionally, in each figure, arrow X represents the X direction, arrow Y represents the Y direction, and arrow Z represents the Z direction. The X, Y, and Z directions intersect and are orthogonal. Furthermore, for convenience, each figure illustrates an example where the scanning direction SD of the laser L on the surface Wa is along the X direction, but the scanning direction SD only needs to be along the surface Wa and intersect the Z direction, not just along the X direction.

[0041] In addition, Figures 2-4 In the diagram, the directions D1, D2, and D3 used to represent the directions of the busbar 10, component 11, and welded part 14 are represented by arrows D1, D2, and D3, respectively. The directions D1, D2, and D3 intersect each other and are orthogonal to each other.

[0042] In addition, the ordinal numbers in this specification are used to distinguish parts, components, locations, lasers, directions, etc., and do not indicate priority or order.

[0043] [First Implementation Method]

[0044] Figure 1 This is a schematic diagram of the laser processing device 100. Figure 1 As shown, the laser processing apparatus 100 includes a laser device 111, a laser device 112, an optical head 120, an optical fiber 130, and a controller 141.

[0045] Laser devices 111 and 112 each have a laser oscillator, configured, for example, to output laser power of several kW. Alternatively, laser devices 111 and 112 can be configured to internally contain multiple semiconductor laser elements, and the combined output of these multiple semiconductor laser elements can output a multimode laser with power of several kW. Furthermore, laser devices 111 and 112 can incorporate various laser light sources such as fiber lasers, YAG lasers, and disk lasers.

[0046] Laser device 111 outputs a first laser with a wavelength of 800 nm or more and 1200 nm or less. Laser device 111 is an example of a first laser device. The laser oscillator included in laser device 111 is an example of a first laser oscillator.

[0047] On the other hand, the laser device 112 outputs a second laser with a wavelength of 550 nm or less. The laser device 112 is an example of a second laser device. Preferably, the laser device 112 outputs a second laser with a wavelength of 400 nm or more and 500 nm or less. The laser oscillator included in the laser device 112 is an example of a second laser oscillator.

[0048] The optical fiber 130 guides the lasers output from the laser devices 111 and 112 to the optical head 120, respectively.

[0049] The optical head 120 is an optical device used to direct laser light input from laser devices 111 and 112 toward the workpiece W. The optical head 120 includes a collimating lens 121, a condenser lens 122, a reflector 123, and a filter 124. The collimating lens 121, condenser lens 122, reflector 123, and filter 124 can also be referred to as optical components.

[0050] The optical head 120 is configured to change its relative position to the workpiece W in order to simultaneously irradiate and scan the workpiece W with the laser L. The relative movement between the optical head 120 and the workpiece W can be achieved by moving the optical head 120, moving the workpiece W, or moving both the optical head 120 and the workpiece W.

[0051] It should be noted that the optical head 120 can also be configured to scan the laser L on the surface Wa by means of an electrical scanner (not shown).

[0052] Collimating lenses 121 (121-1, 121-2) collimate the laser light input through fiber optic 130. The collimated laser light becomes parallel light.

[0053] The first laser beam, which becomes parallel light after being reflected by the collimating lens 121-1, is reflected by the mirror 123. The first laser beam reflected by the mirror 123 travels in the opposite direction of the Z-direction toward the filter 124. It should be noted that in a structure in which the first laser beam is input in the opposite direction of the Z-direction within the optical head 120, the mirror 123 is not required.

[0054] Filter 124 is a high-pass filter that allows the first laser beam to pass through but reflects the second laser beam instead. The first laser beam passes through filter 124 and travels in the opposite direction of the Z-direction toward the condenser lens 122. On the other hand, filter 124 reflects the second laser beam, which becomes parallel light after passing through collimating lenses 121-2. The second laser beam reflected by filter 124 travels in the opposite direction of the Z-direction toward the condenser lens 122.

[0055] The focusing lens 122 focuses the first and second lasers, which are parallel beams, so that they are used as laser L (output light) to irradiate the workpiece W.

[0056] In addition, the laser processing apparatus 100 has a controller 141 and a drive mechanism 150 that is controlled by the controller 141.

[0057] The drive mechanism 150 changes the relative position of the optical head 120 with respect to the workpiece W. The drive mechanism 150 may include, for example, a rotating mechanism like a motor, a speed reduction mechanism that reduces the rotational output of that rotating mechanism, or a motion conversion mechanism that converts the reduced rotational speed into linear motion. The controller 141 can control the drive mechanism 150 by changing the relative position of the optical head 120 with respect to the workpiece W in the X, Y, and Z directions.

[0058] The controller 141 can also control, for example, the operation and shutdown switching of the laser devices 111 and 112, and the power of the laser emitted by the laser devices 111 and 112. Furthermore, if the laser processing apparatus 100 is equipped with a gas supply mechanism (not shown) that supplies a gas such as an inert gas to the surface Wa of the workpiece W, the controller 141 can also control the gas supply mechanism by switching the gas supply and shutdown, or by changing the flow rate of the discharged gas.

[0059] Additionally, the laser processing apparatus 100 includes a camera 170, and a filter 127 and a reflector 128 as optical components guiding light to the camera 170. The filter 127 is disposed between the reflector 123 and the filter 124. The filter 127 allows the first laser beam from the reflector 123 to pass through the filter 124 and reflects light (e.g., visible light) from the surface Wa towards the reflector 128. The light reflected by the reflector 128 is input to the camera 170. With this structure, the camera 170 can capture an image on the surface Wa. The image captured by the camera 170 may include, for example, an image of the surface Wa and an image of the beam (spot) formed by the laser L. Therefore, the image captured by the camera 170 can be considered a detection result of the offset of the spot formed on the surface Wa relative to a predetermined position, and the camera 170 can be considered an example of a sensor that detects this offset. It should be noted that when the position of the spot in the field of view of the captured image is fixed, it is sufficient to include the target illuminated by the laser L in the captured image; it is not necessary to include an image of the spot itself.

[0060] Furthermore, the controller 141 can control the laser beam by detecting and correcting any deviation of the spot relative to a predetermined position from the image captured by the camera 170. Alternatively, the controller 141 can perform feedback control, ensuring that the deviation remains within a predetermined threshold. In this case, the controller 141 and the drive mechanism 150 constitute an example of a correction mechanism. This structure improves the accuracy of the laser irradiation position.

[0061] like Figure 1 As shown, the laser processing apparatus 100 irradiates the contact portion of two components 11 with laser L, thereby welding the two components 11. Figure 1 The diagram only shows one point where two of the multiple components 11 constituting the busbar 10 are welded together by the welding portion 14. All the multiple components 11 included in the busbar 10 are made of a conductive metallic material. Components 11 can also be referred to as metallic components or conductors. The welding portion 14 mechanically and electrically connects two components 11 respectively. The busbar 10 is thus constructed by connecting multiple components 11 through the welding portions 14.

[0062] exist Figure 1 In this example, two components 11 are arranged in the Y direction. The Z-direction end faces of the two components 11 are aligned flush in the Y direction, forming the surface Wa of the workpiece W. Surface Wa extends intersecting the Z direction, facing the optical head 120. The laser L emitted from the optical head 120 travels in the opposite direction to the Z direction and irradiates surface Wa. The weld portion 14 extends from surface Wa in the opposite direction to the Z direction. In this example, the depth direction of the weld portion 14 is the opposite direction to the Z direction. It should be noted that in Figure 1 In this example, surface Wa is a plane, but it can also be a stepped surface. Furthermore, surface Wa can also be a convex surface, a concave surface, etc.

[0063] Additionally, the laser L travels along the scanning direction SD on the surface Wa (in... Figure 1 In the area shown, scanning in the X direction, the welded part 14 is also connected to... Figure 1 The roughly identical cross-sectional shape extends along the scanning direction SD. The scanning direction SD, also referred to as the extension direction or length direction of the weld 14, is an example of the first direction. Additionally, there is an orthogonal direction (in...) that is orthogonal to both the Z direction and the scanning direction SD. Figure 1 In the area shown, the Y direction can also be referred to as the width direction of the welded part 14.

[0064] The laser processing apparatus 100 of this embodiment can irradiate the workpiece W with a laser L containing both a first laser and a second laser, and can also irradiate the workpiece W with a laser L containing only the first laser, and can also irradiate the workpiece W with a laser L containing only the second laser. When only the first laser is irradiated, the laser device 112 does not operate; when only the second laser is irradiated, the laser device 111 does not operate. Alternatively, the laser processing apparatus 100 may also be a device that irradiates only the first laser without the laser device 112, collimating lens 121-2, filter 124, etc., and can only irradiate the first laser; or it may be a device that irradiates only the second laser without the laser device 111, collimating lens 121-1, reflector 123, etc.

[0065] Figures 2-4 This is a perspective view of the busbar 10 manufactured by the laser processing device 100. Figures 2-4 In the example, the multiple components 11 constituting the busbar 10 all have a quadrilateral shape and a flat plate shape. This makes it easier to obtain multiple components 11. However, the multiple components 11 are not limited to such shapes.

[0066] Figure 2 The illustrated busbar 10 has four plate-shaped components 11 welded together by welding portions 14 (14-1, 14-2, 14-3). Each welding portion 14 welds two components 11 respectively.

[0067] Welding section 14-1 welds two components 11-1 and 11-2. Component 11-1 extends along directions D1 and D2, and component 11-2 extends along directions D1 and D3. Components 11-1 and 11-2 intersect and are orthogonal to each other. Welding section 14-1 extends linearly along direction D1 at the corner of the two portions extending along direction D1 formed by the butt joint of components 11-1 and 11-2. In welding section 14-1, direction D1 is the width direction of components 11-1 and 11-2. During welding of welding section 14-1, laser L irradiates towards the corner and scans along direction D1. Furthermore, welding section 14-1 is provided between approximately both ends of components 11-1 and 11-2 in direction D1, that is, between approximately one end 11a and the other end 11a. It should be noted that the weld portions 14-1 are provided on both sides of the thickness direction of the component 11-1, but this is not a limitation; they may be provided only on either side of the two weld portions 14-1 locations. When the weld portions 14-1 are provided on both sides of the thickness direction, the joint strength is higher and the resistance can be further reduced compared to when they are provided only on one side of the thickness direction. Furthermore, the weld portions 14-1 on the two locations may overlap. In the weld portions 14-1, direction D1 is an example of a first direction, direction D2 is an example of a second direction, and direction D3 is an example of a third direction.

[0068] Welding section 14-2 welds two components 11-2 and 11-3. Component 11-2 extends along directions D1 and D3, and component 11-3 extends along directions D1 and D2. Components 11-2 and 11-3 intersect and are orthogonal to each other. Welding section 14-2 extends linearly along direction D1 at the corners and boundaries formed by the butt joint of components 11-2 and 11-3. In welding section 14-2, direction D1 is the width direction of components 11-2 and 11-3. During welding of welding section 14-2, laser L is irradiated toward the corners and boundaries, and scans along direction D1. Welding section 14-2 is provided between approximately the two ends of components 11-2 and 11-3 in direction D1, that is, between approximately one end 11a and the other end 11a. It should be noted that the weld portions 14-2 are provided on both sides of the thickness direction of the component 11-3, but this is not a limitation; they may be provided only on either side of the two weld portions 14-2. When the weld portions 14-2 are provided on both sides of the thickness direction, the joint strength is higher and the resistance is reduced compared to when they are provided only on one side of the thickness direction. Furthermore, the weld portions 14-2 on the two parts may overlap. In the weld portions 14-2, direction D1 is an example of a first direction, direction D3 is an example of a second direction, and direction D2 is an example of a third direction.

[0069] Welding part 14-3 welds two components 11-3 and 11-4. Components 11-3 and 11-4 both extend along the D1 and D2 directions. Components 11-3 and 11-4 are arranged and joined in the D1 direction. Welding part 14-3 extends linearly along the D2 direction at the boundary formed by the joining of components 11-3 and 11-4. During welding of welding part 14-3, laser L irradiates towards this boundary and scans along the D2 direction. Furthermore, welding part 14-3 is provided between approximately both ends of component 11-4 in the D2 direction, that is, between approximately one end 11a and the other end 11a. It should be noted that welding part 14-3 may also be provided on both sides of component 11-3 and component 11-4 in the thickness direction. In welding part 14-3, the D2 direction is an example of the first direction, and the D1 direction is an example of the same direction intersecting the first direction.

[0070] With this structure, the weld portion 14 extends linearly along a first direction and is disposed between approximately both ends of at least one of the two components 11 welded by the weld portion 14 in the first direction, so that the joint strength of the weld portion 14 is more likely to be higher than that of spot welding.

[0071] Figure 3The illustrated busbar 10 has two plate-shaped members 11 welded together by a weld joint 14 (14-4). The two members 11 are joined together in a non-orthogonal, obliquely intersecting manner. In this case, the weld joint 14-4 also extends linearly along the D1 direction between approximately both ends of the two members 11 in that direction. In such a structure, it is also possible to achieve [something] through [something]. Figure 2 The same example of weld 14 joining two components 11 results in... Figure 2 The same effect is achieved in the example. It should be noted that the weld portion 14-4 is provided on both sides of the thickness direction of the member 11, but it is not limited to this, and it may be provided only on either side of the two weld portions 14-4. When the weld portion 14-4 is provided on both sides of the thickness direction, the joint strength is higher compared to the case where it is provided only on one side of the thickness direction.

[0072] Figure 4 The illustrated busbar 10 has two plate-shaped members 11 welded together by welded portions 14 (14-5, 14-6) at two locations. Both members 11 extend along both the D1 and D2 directions, with their ends overlapping each other in the D3 direction. In this case, the welded portions 14-5, 14-6 also extend linearly along the D1 direction between approximately both ends of the two members 11. In this structure, a connection with... Figure 2 The same example of weld 14 joining two components 11 results in... Figure 2 The example has the same effect.

[0073] In addition, Figures 2-4 In the example, component 11 can also be an extrusion obtained by extrusion molding. An extrusion is a component with a generally constant cross-sectional shape, such as a wire, flat wire, strip, or flat component. Each component 11 can be obtained by cutting the base material 20 with a cross section intersecting the extrusion direction (length direction). According to such a manufacturing method, for example, it is possible to further reduce manufacturing labor and costs.

[0074] Figure 5 This is a schematic diagram showing a laser beam (spot) L illuminating a planar surface Wa. Beams B1 and B2 each have a power distribution, for example, a Gaussian shape, in the radial direction of a cross-section orthogonal to their optical axes. However, the power distributions of beams B1 and B2 are not limited to a Gaussian shape. Furthermore, as... Figure 5 As shown in the diagrams representing beams B1 and B2 using circles, the diameter of the circle representing beam B1 and B2 is the beam diameter of each beam B1 and B2. The beam diameter of each beam B1 and B2 is defined as the beam containing the peak value of that beam with an intensity equal to 1 / e of the peak intensity. 2The diameter of the region with the above intensity. It should be noted that, although not illustrated, in the case of a non-circular beam, the intensity in the direction perpendicular to the scanning direction SD can be 1 / e of the peak intensity. 2 The length of the region described above is defined as the beam diameter. Additionally, the beam diameter on surface Wa is called the spot diameter.

[0075] like Figure 5 As shown, in this embodiment, as an example, the laser beam L is formed such that, on the surface Wa, the beam B1 of the first laser overlaps with the beam B2 of the second laser, with beam B2 being larger (wider) than beam B1, and the outer edge B2a of beam B2 surrounding the outer edge B1a of beam B1. In this case, the spot diameter d2 of beam B2 is larger than the spot diameter d1 of beam B1. On the surface Wa, beam B1 is an example of a first spot, and beam B2 is an example of a second spot.

[0076] In addition, in this embodiment, such as Figure 5 As shown, on surface Wa, the laser beam (spot) of laser L has a point-symmetric shape with respect to the center point C, therefore the shape of the spot is the same in any scanning direction SD. Therefore, in the case of a moving mechanism that moves the optical head 120 relative to the workpiece W for scanning surface Wa with laser L, this moving mechanism only needs to have at least a mechanism capable of relative translation; sometimes a mechanism capable of relative rotation can be omitted. It should be noted that beams B1 and B2 can both be the first laser or both be the second laser. Alternatively, the beam can be either the first laser or one of the second lasers.

[0077] The two components 11 of the processing object W can each be made of a conductive metallic material. The metallic material can be, for example, copper-based metals, aluminum-based metals, specifically copper, copper alloys, aluminum, aluminum alloys, tin-plated copper, tin-plated copper alloys, tin-plated aluminum, tin-plated aluminum alloys, etc. The two components 11 can be made of the same material or different materials. Furthermore, the plating is not limited to tin plating; for example, other plating such as nickel plating can also be used.

[0078] [Wavelength and light absorption rate]

[0079] Here, we will explain the light absorption rate of metallic materials. Figure 6 This is a graph showing the light absorption rate of each metallic material relative to the wavelength of the irradiated laser L. Figure 6 The horizontal axis of the graph represents wavelength, and the vertical axis represents absorbance. Figure 6 The relationship between wavelength and absorption rate is shown for aluminum (Al), copper (Cu), gold (Au), nickel (Ni), silver (Ag), tantalum (Ta), and titanium (Ti).

[0080] Although properties vary depending on the material, it is understandable that... Figure 6 The metals shown exhibit higher energy absorption rates when using blue or green lasers (second lasers) compared to conventional infrared (IR) lasers (first lasers). This characteristic is particularly pronounced in copper (Cu) and gold (Au).

[0081] When a laser is irradiated onto a workpiece W with a low absorptivity relative to the wavelength used, most of the light energy is reflected, exerting no thermal effect on the workpiece W. Therefore, a higher power is required to obtain a sufficiently deep molten region. In this case, energy is rapidly injected into the center of the beam, resulting in sublimation and the formation of a pinhole.

[0082] On the other hand, when a laser is irradiated onto a workpiece W with a higher absorptivity relative to the wavelength used, most of the applied energy is absorbed by the workpiece W and converted into heat energy. That is, excessive power is not required, and therefore no pinholes are formed, resulting in heat-conductive melting.

[0083] In this embodiment, the wavelengths of the first laser, the second laser, and the material of the workpiece W are selected such that the absorptivity of the workpiece W relative to the second laser is higher than its absorptivity relative to the first laser. In this case, the scanning direction is... Figure 5 In the case of the scanning direction SD shown, the scanning of the laser spot L is performed by the second laser beam B2 located at... Figure 5 The region B2f in front of the SD in the process irradiates the part of the workpiece W to be welded (hereinafter referred to as the welded part) with a second laser. Then, the beam B1 of the first laser irradiates the welded part, and then the region B2b of the second laser beam B2 located behind the scanning direction SD irradiates the welded part again with the second laser.

[0084] Therefore, at the welded area, a heat-conducting molten region is first generated by irradiation with a second laser with high absorptivity in region B2f. Then, at the welded area, a deeper pinhole-type molten region is generated by irradiation with a first laser. In this case, since a heat-conducting molten region is pre-formed at the welded area, a molten region of the desired depth can be formed using a lower-power first laser compared to the case where this heat-conducting molten region is not formed. Subsequently, at the welded area, the molten state changes due to irradiation with a second laser with high absorptivity in region B2b. From this viewpoint, the wavelength of the second laser is preferably 550 nm or less, more preferably 500 nm or less.

[0085] Furthermore, based on the inventors' experimental research, it was confirmed that... Figure 5 When welding is performed using laser beam L, such beams can reduce welding defects such as sputtering and porosity. This can be inferred because the workpiece W is preheated in region B2f of beam B2 before beam B1 arrives, thereby stabilizing the molten pool of workpiece W formed by beams B2 and B1.

[0086] [Welding Method]

[0087] During welding using the laser processing apparatus 100, firstly, the workpiece W, consisting of two integrally and temporarily fixed together, is positioned such that its surface Wa is irradiated by the laser L. Then, with the laser L irradiating the surface Wa, the laser L moves relative to the workpiece W. Thus, while irradiating the surface Wa, the laser L moves along the scanning direction SD on the surface Wa (scanning). The portion irradiated by the laser L melts and then solidifies as the temperature decreases, thereby welding the two components 11 together. The welding of the two components 11 is performed in one or more locations, forming a busbar 10.

[0088] [DOE]

[0089] In addition, such as Figure 1 As shown, the optical head 120 has a DOE 125 between the collimating lens 121-1 and the reflecting mirror 123.

[0090] The shape of the first laser beam B1 formed by the DOE125 (hereinafter referred to as beam shape). For example... Figure 7 As conceptually illustrated, the DOE 125, for example, has a structure in which multiple diffraction gratings 125a with different periods overlap. The DOE 125 can shape a beam by bending or overlapping parallel light in the directions affected by the individual diffraction gratings 125a. The DOE 125 can also be referred to as a beam shaper.

[0091] It should be noted that the optical head 120 may also include a beam shaper disposed after the collimating lens 121-2 to adjust the beam shape of the second laser, or a beam shaper disposed after the filter 124 to adjust the beam shapes of both the first and second lasers. By appropriately adjusting the beam shape of the laser L using the beam shaper, the generation of welding defects can be further suppressed during welding. Furthermore, the DOE 125 can split the beam of the first laser into multiple beams. It should be noted that the optical head 120 may also be without the DOE 125.

[0092] [Cross-section of the welded part]

[0093] Figure 8 This is a cross-sectional view showing an example of a welded portion 14 formed on a workpiece W. Figure 8 This is an example of a laser L that illuminates both a beam B1 based on a first laser and a beam B2 based on a second laser. It should be noted that the shape of the cross-section varies depending on the type of laser illuminating it.

[0094] Figure 8 It is related to the scan direction SD ( Figure 8 This is a cross-sectional view perpendicular to the X direction and along the thickness direction (Z direction, depth direction of weld 14). Weld 14 is also viewed along the scanning direction SD, i.e., perpendicular to the X direction. Figure 8 It extends perpendicularly to the paper surface. It should be noted that... Figure 8 A cross-section of the weld portion 14 formed on a workpiece W with a thickness of 2 mm is shown. The shape of the weld portion 14, which joins the two components 11, can be inferred to be similar to that formed on the workpiece W. Figure 8 The shape of the welded part 14 shown is roughly the same as that of the metal material processing object W.

[0095] like Figure 8 As shown, the weld portion 14 has weld metal 14a extending in the opposite direction from the surface Wa to the Z direction, and a heat-affected zone 14b surrounding the weld metal 14a. The weld metal 14a is the portion that is melted and then solidified by irradiation with laser L. The weld metal 14a can also be referred to as the molten and solidified portion. In addition, the heat-affected zone 14b is the portion of the base material (welding base material) of the workpiece W that is affected by heat, and it is an unmelted portion.

[0096] The further away from the surface Wa, the narrower the width of the weld metal 14a along the Y direction becomes. That is, the cross-section of the weld metal 14a has a conical shape that tapers in the opposite direction toward the Z direction.

[0097] Furthermore, based on the inventors' detailed analysis of the cross-section, it was determined that the weld metal 14a includes a first portion 14a1 separated from the surface Wa, and a second portion 14a2 between the first portion 14a1 and the surface Wa.

[0098] The first region 14a1 is obtained by melting through a small aperture irradiated by a first laser, and the second region 14a2 is obtained by melting through irradiation of region B2b located behind the scanning direction SD in the beam B2 of a second laser. Analysis based on the EBSD (electron backscatter diffraction pattern) method revealed that the grain sizes in the first region 14a1 and the second region 14a2 are different. Specifically, in a cross-section orthogonal to the X direction (scanning direction SD), the average cross-sectional area of ​​the grains in the second region 14a2 is larger than that in the first region 14a1.

[0099] The inventors confirmed that when only the first laser beam B1 irradiates the workpiece W, i.e., without irradiation of the region B2b located behind the scanning direction SD in the beam B2, the second portion 14a2 is not formed, and the first portion 14a1 extends deeper from the surface Wa in the opposite direction to the Z direction. That is, in this embodiment, the second portion 14a2 is formed near the surface Wa by irradiation of the region B2b located behind the scanning direction SD in the beam B2. Therefore, it can be inferred that the first portion 14a1 is formed at a position opposite to the surface Wa relative to the second portion 14a2, in other words, separated from the surface Wa in the opposite direction to the Z direction.

[0100] Figure 9 This is a cross-sectional view showing an example of a portion of the welded part 14. Figure 9 The boundaries of the crystal grains obtained by the EBSD method are shown. Additionally, in Figure 9 In this example, crystal grain A with a diameter of less than 13 μm was painted black. It should be noted that 13 μm is not a threshold for physical properties, but rather a threshold set for the analysis of the experimental results. Furthermore, according to... Figure 9 It can be seen that crystal grains A are more abundant in the first region 14a1 and less abundant in the second region 14a2. That is, the average cross-sectional area of ​​the crystal grains in the second region 14a2 is larger than the average cross-sectional area of ​​the crystal grains in the first region 14a1. The inventors confirmed through experimental analysis that the average cross-sectional area of ​​the crystal grains in the second region 14a2 is more than 1.8 times the average cross-sectional area of ​​the crystal grains in the first region 14a1.

[0101] like Figure 9 As shown in region I, these smaller grains A are densely packed at locations separating from the surface Wa in the Z direction, extending elongatedly along the Z direction. Furthermore, analysis at multiple locations at different positions in the X direction (scanning direction SD) confirmed that the region of dense grain A also extends along the scanning direction SD. Since the welding was performed simultaneously with the scan, it can be inferred that the crystals formed in the same morphology in the scanning direction SD.

[0102] In cases where it is difficult to distinguish between the first part 14a1 and the second part 14a2 based on the appearance or hardness distribution in the cross-section, it is also possible to... Figure 8 , 9The first region Z1 and the second region Z2, geometrically determined based on their positions and widths wb on the surface Wa of the weld metal 14a, are respectively designated as the first part 14a1 and the second part 14a2. For example, the first region Z1 and the second region Z2 are quadrilateral regions extending along the Z direction with a width wm (equal width in the Y direction) in a section orthogonal to the scanning direction SD. The second region Z2 can be defined as a region extending from the surface Wa to a depth d in the Z direction. The first region Z1 can be defined as a region deeper than the depth d, in other words, a region located on the opposite side of the surface Wa relative to the depth d. The width wm can, for example, be set to 1 / 3 of the width wb (average width of the reinforcing ribs) of the weld metal 14a on the surface Wa, and the depth d (height, thickness) of the second region Z2 can, for example, be set to 1 / 2 of the width wb. Furthermore, the depth of the first region Z1 can, for example, be set to 3 times the depth d of the second region Z2. Through experimental analysis of multiple samples, the inventors confirmed that, under the settings of the first region Z1 and the second region Z2, the average cross-sectional area of ​​the grains in the second region Z2 is larger than the average cross-sectional area of ​​the grains in the first region Z1, and is more than 1.8 times larger. This determination can also serve as evidence that the first part 14a1 and the second part 14a2 are formed in the weld metal 14a through welding.

[0103] Furthermore, the inventors' research, including experiments, has determined that in the weld section 14, the ratio of the depth of the weld section 14 (the length of the weld metal 14a in the thickness direction) of the thinner component 11 among the two components 11 welded by the weld section 14 to the thickness of the thinner component 11 is preferably 0.8 or more, more preferably 0.9 or more. By forming such a deep weld penetration, a complex busbar 10 structure can be achieved while ensuring the joint strength, and the resistance can be reduced. Moreover, by irradiating with a laser L containing a first laser and a second laser with different wavelengths, welding defects such as sputtering and porosity can be suppressed.

[0104] Furthermore, the thickness of component 11 is preferably 0.5 mm or more, more preferably 1.0 mm or more, and even more preferably 2.0 mm or more. According to the welding method of this embodiment, a deeper weld penetration can be achieved, thus a stronger bond can be obtained even when welding two thick components 11, and the resistance can be reduced. Moreover, by irradiating with a laser L comprising a first laser and a second laser with different wavelengths, welding defects such as sputtering and porosity can be suppressed even when welding two thick components 11.

[0105] As explained above, in the busbar 10 of this embodiment, the weld portion 14 of the two components 11 extends linearly along a first direction and is disposed between approximately both ends of at least one of the two components 11 in the first direction.

[0106] According to this structure, for example, compared to the case where two components 11 are joined by spot welding, it is advantageous to further improve the joint strength based on the weld 14 or to further reduce the resistance in the weld 14. Furthermore, assuming the busbar 10 is manufactured by stamping, the cost of the stamping die increases, correspondingly increasing the manufacturing cost of the busbar 10 and thus its price. In this respect, according to this embodiment, the busbar 10 can be configured into any shape by welding multiple components 11, thus also providing the advantage of manufacturing the busbar 10 at a lower cost.

[0107] Furthermore, in the busbar 10 of this embodiment, for example, the two components 11-3 and 11-4 welded by the welding portion 14-3 extending along the D2 direction (first direction) can both extend along the D2 direction and along the D1 direction (the same direction) intersecting the D2 direction. Alternatively, one of the two components 11 welded by the welding portion 14-1 can extend along the D1 direction (first direction) and along the D2 direction (second direction) intersecting the D1 direction, while the other component 11-2 extends along the D1 direction and along the D3 direction (third direction) intersecting both the D1 and D2 directions. In this way, the welding portion 14 of this embodiment can be applied to welding two components 11 arranged in various postures, thereby obtaining a busbar 10 of arbitrary shape.

[0108] Furthermore, in the busbar 10 of this embodiment, a plating layer can be provided on the surface of at least one of the two components 11, or a small unevenness (texture) can be provided on the surface of at least one of the two components 11, for example, through surface treatments such as sandblasting, shot peening, laser processing, or chemical etching. The welding part 14 of this embodiment can be applied to the joining of such two components 11. In addition, according to this structure, for example, it is possible to obtain the effect of preventing damage or corrosion by providing a plating layer on the surface of the component 11, and the effect of improving heat dissipation by providing a small unevenness on the surface of the component 11. It should be noted that the surface treatment of forming the plating layer and the unevenness is preferably performed on the flat component 11 before welding by the welding part 14. Therefore, compared with the case of performing surface treatment on the assembled busbar 10, it is easier to perform surface treatment, or it is possible to perform surface treatment under conditions suitable for obtaining the characteristics required for each location.

[0109] Furthermore, in the manufacturing method of the busbar 10 of this embodiment, the weld portion 14 can also be formed by irradiation with a laser containing multiple beams, for example. According to such a manufacturing method, for example, by utilizing the preheating effect of the sub-beam irradiated before the main beam, a higher quality weld portion 14 that suppresses sputtering and porosity can be formed.

[0110] Furthermore, in the manufacturing method of the busbar in this embodiment, for example, multiple beams can also be formed by a DOE125 (beam shaper). According to such a manufacturing method, multiple beams can be formed from a single laser, thus providing advantages such as the ability to weld higher quality welds 14 using a laser processing apparatus 100 with a simpler structure, or sometimes further reducing the energy consumption of the laser processing apparatus 100 during welding.

[0111] Alternatively, in the busbar of this embodiment, the welding part 14 may have welding metal 14a and heat-affected part 14b, the welding metal 14a may have a first part 14a1 and a second part 14a2 in which the average cross-sectional area of ​​the crystal grains in the cross section along the depth direction of the welding part 14 is larger than the first part 14a1.

[0112] Alternatively, in the method for manufacturing the busbar in this embodiment, the plurality of beams B1 and B2 may include a beam B1 based on a first laser with a wavelength of 800 nm or more and 1200 nm or less, and a beam B2 based on a second laser with a wavelength of 400 nm or more and 500 nm or less.

[0113] As described above, the inventors confirmed that when welding is performed on the surface Wa by irradiation with a laser L beam that forms beams B1 and B2 as described above, welding defects can be further reduced. In the welding section 14, welding metal 14a with a first portion 14a1 and a second portion 14a2, and a heat-affected zone 14b are formed. As described above, it can be inferred that this is because by preheating the workpiece W through the region B2f based on the second laser beam B2 before the arrival of the first laser beam B1, the molten pool of the workpiece W formed by the beams B2 and B1 is further stabilized. Therefore, according to the laser L having beams B1 and B2 as described above, welding with fewer welding defects and higher welding quality can be performed, for example. This effect is more significant than the case where a single laser is split by a DOE 125 (beam shaper), and becomes even more significant when multiple beams B1 and B2 are further split by a DOE 125. In addition, according to such a setting of beams B1 and B2, the power of the first laser can also be further reduced, for example. Furthermore, when beams B1 and B2 are irradiated coaxially, the advantage of not requiring relative rotation between the optical head 120 and the workpiece W is also obtained.

[0114] Furthermore, in this embodiment, for example, the two components 11 are made of either a copper-based metal or an aluminum-based metal. When the busbar 10 is used in an environment with significant vibration, such vibration may cause damage to the connection points between the busbar 10 and other components. In such cases, by using a highly elastic material to manufacture at least one of the multiple components 11 constituting the busbar 10, the flexibility of the busbar 10 can be improved, thereby suppressing adverse phenomena caused by vibration in the busbar 10 and other components connected to it. In this case, by appropriately selecting or combining materials according to the required mechanical and electrical characteristics, a better busbar 10 can be manufactured. It should be noted that highly elastic materials include, for example, phosphor bronze, beryllium copper, C7025, C64770, C18142, and C18045.

[0115] Alternatively, in this embodiment, the welding of the welded portion 14 can be controlled based on images captured by the camera 170. According to this manufacturing method, the welded portion 14 can be formed with higher precision.

[0116] [Second Implementation]

[0117] Figure 10 This is a perspective view illustrating a method for manufacturing the plurality of components 11 of this embodiment. For example... Figure 10As shown, multiple components 11 can be formed by cutting the base material 20 (the cut base material) through irradiation by laser L. If the components 11 are formed by stamping, the cost of the stamping die increases, and consequently, the manufacturing cost of the components 11 and the busbar 10, and thus the price of the busbar 10, tends to increase. In this respect, according to this embodiment, since multiple components 11 can be formed by laser cutting of the base material 20, it is also advantageous to manufacture these multiple components 11 more cost-effectively.

[0118] Furthermore, the laser L used to laser-cut the base material 20 to obtain multiple components 11 can be irradiated from the optical head 120 of the laser processing apparatus 100. In this case, the settings of each part of the laser processing apparatus 100 are changed in the case of laser cutting of the base material 20 and in the case of laser welding of two components 11, i.e., the formation of the welded part 14. For example, in the case of irradiating only the first laser (beam B1) during laser cutting, the output of the laser devices 111 and 112 can be set to be smaller compared to the case of irradiating both the first laser (beam B1) and the second laser (beam B2) during laser welding, or when laser cutting is performed during laser welding. In addition, the laser processing apparatus 100 may also be equipped with a gas supply mechanism that can blow inactive gas toward the workpiece W from the optical head 120 or from a nozzle different from the optical head 120 as needed during laser cutting. It should be noted that the differences in the settings of the laser processing apparatus 100 in the cases of laser cutting and laser welding are not limited to these.

[0119] The above embodiments of the present invention have been illustrated, but these embodiments are merely examples and are not intended to limit the scope of the invention. The above embodiments can be implemented in various other ways, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the specifications of various structures, shapes, etc. (construction, type, orientation, form, size, length, width, thickness, height, quantity, arrangement, position, material, etc.) can be appropriately modified for implementation.

[0120] For example, when scanning a workpiece with a laser, scanning can also be performed using known techniques such as oscillation, rocking, and output modulation to adjust the surface area of ​​the molten pool.

[0121] Industrial applicability

[0122] This invention can be applied to busbars and methods for manufacturing busbars.

[0123] Explanation of reference numerals in the attached figures:

[0124] 10…busbars;

[0125] Components 11, 11-1 to 11-4…

[0126] 11a…end;

[0127] 14, 14-1~14-6… Welding sections;

[0128] 14a… Welding metals;

[0129] 14a1…First part;

[0130] 14a2…Second part;

[0131] 14b…Heat-affected zone;

[0132] 20… (cut) parent material;

[0133] 100… laser processing equipment;

[0134] 111…Laser device (first laser oscillator);

[0135] 112…Laser device (second laser oscillator);

[0136] 120… Optical head;

[0137] 121, 121-1, 121-2… collimating lenses;

[0138] 122… Condensing lens;

[0139] 123…reflector;

[0140] 124… filter;

[0141] 125…DOE (Diffractive Optical Element);

[0142] 125a…diffraction grating;

[0143] 127… filter;

[0144] 128…reflector;

[0145] 130… fiber optic cable;

[0146] 141… controller;

[0147] 150… drive mechanism;

[0148] 170… camera;

[0149] A…crystal grains;

[0150] B1…beam (first spot);

[0151] B1a…outer edge;

[0152] B2…beam (second spot);

[0153] B2a…outer edge;

[0154] B2b…area;

[0155] B2f…area;

[0156] C…center point;

[0157] d1…spot diameter (outer diameter);

[0158] d2…spot diameter (outer diameter);

[0159] d… depth;

[0160] D1~D3…direction;

[0161] L…laser;

[0162] SD…scanning direction;

[0163] W…the object being processed;

[0164] Wa...surface;

[0165] wb… (width on the surface of the welded metal);

[0166] wm… (width of the first and second regions);

[0167] X…direction;

[0168] Y...direction;

[0169] Z…direction;

[0170] Z1…First region (first part);

[0171] Z2…Second region (second part).

Claims

1. A busbar having: a plurality of members each of which is plate-shaped; and a linear welding portion which welds two members included in the plurality of members and extends in a first direction, wherein the welding portion is provided between approximately both ends of the first direction of at least one of the two members, the welding portion has: a welding metal; and a heat-affected portion which is located around the welding metal, the welding metal has a first portion which is separated from a surface of the welding portion and a second portion which is located between the first portion and the surface, an average value of cross-sectional areas of crystal grains in a cross section in a depth direction of the welding portion is larger in the second portion than in the first portion, the first portion is a portion obtained by melting in a keyhole type based on irradiation of a first laser, and the second portion is a portion obtained by melting based on irradiation of a region located at a rear in a scanning direction among beams of a second laser.

2. The busbar according to claim 1, wherein the two members each extend in the first direction and extend in the same direction which intersects the first direction.

3. The busbar according to claim 1, wherein one of the two members extends in the first direction and extends in a second direction which intersects the first direction, and the other of the two members extends in the first direction and extends in a third direction which intersects the first direction and the second direction.

4. The busbar according to any one of claims 1 to 3, wherein a plating layer is provided on a surface of at least one of the two members.

5. The busbar according to any one of claims 1 to 3, wherein a concavo-convex surface is provided on a surface of at least one of the two members.

6. The busbar according to any one of claims 1 to 3, wherein the plurality of members are each made of any one of a copper-based metal material and an aluminum-based metal material.

7. The busbar according to any one of claims 1 to 3, wherein a ratio of a depth of the welding portion in a thickness direction to a thickness of a member which is thinner among the two members is 0.8 or more.

8. The busbar according to any one of claims 1 to 3, wherein the thickness of the member is 0.5 [mm] or more.

9. A method of manufacturing a busbar having: a plurality of members each of which is plate-shaped; and a linear welding portion which welds two members included in the plurality of members and extends in a first direction, wherein the welding portion is formed by irradiation of a laser including a plurality of beams, and by scanning of a spot of the laser, a second laser among the plurality of beams is first irradiated to the welding portion through a region located at a front in a scanning direction of a beam of the second laser, thereafter, a first laser among the plurality of beams is irradiated to the welding portion, thereafter, the second laser is again irradiated to the welding portion through a region located at a rear in the scanning direction of the beam of the second laser.

10. The method of manufacturing a busbar according to claim 9, wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The plurality of light beams are formed by a beam shaper.

11. The busbar manufacturing method according to claim 9, wherein The plurality of light beams include a light beam of a first laser based on a wavelength of 800 [nm] or more and 1200 [nm] or less, and a light beam of a second laser based on a wavelength of 550 [nm] or less.

12. The busbar manufacturing method according to claim 11, wherein The wavelength of the second laser is 400 [nm] or more and 500 [nm] or less.

13. The busbar manufacturing method according to any one of claims 9 to 12, wherein The plurality of members are formed by cutting from a base material by laser cutting.

14. The busbar manufacturing method according to any one of claims 9 to 12, wherein The plurality of members are formed by cutting of a flat plate-shaped extrusion.

15. The busbar manufacturing method according to any one of claims 9 to 12, wherein The welding of the weld is controlled based on a captured image captured by a camera.

Images