Sheet material joined body

Abstract

The present invention pertains to a sheet material joined body (1) comprising: a first sheet material (3); a second sheet material (2); a plating layer (4); a plated joint part (7a) that is provided between a third surface (13) of the second sheet material (2) and a second surface (12) of the first sheet material (3) in the plating layer (4) in a portion at which the first sheet material (3) and the second sheet material (2) overlap each other; and a welding part (6) that penetrates through the first sheet material (3) in the thickness direction, is provided inside the second sheet material (2) in the thickness direction, and is in contact with a lateral surface (8) of the plated joint part (7a) so as to sandwich at least a portion of the lateral surface. The material constituting the plating layer (4), which is the outermost layer, has a melting point lower than that of the material constituting portions other than the portion at which the first sheet material (3) and the second sheet material (2) overlap each other.

Description

Plate joints

[0001] The present invention relates to a joined body of plate materials.

[0002] Welding methods have been used as a method for joining different plate materials. Patent Document 1 (JP 2022-126386 A) discloses a method for welding a first plate material and a second plate material, which includes a first welding step in which a laser is irradiated onto a first portion along at least a portion of an annular region to be welded while scanning the laser, a second welding step in which the laser is irradiated onto a second portion along at least a portion of the annular region to be welded while scanning the laser at a constant energy density, and at the end of the first welding step, the laser is irradiated onto a portion overlapping the first portion, and a third welding step in which the laser is irradiated onto a third portion overlapping at least a portion of the second portion while scanning the laser while gradually decreasing the energy density, which is continuous with the second welding step. Patent Document 2 (JP 2016-143656 A) discloses an energy storage element comprising a first plate and a second plate, and a weld formed at a location where the first plate and the second plate overlap, the weld being composed of a linear series of weld marks connecting the first plate and the second plate; the weld has a first portion formed by a weld mark obtained by keyhole welding with a laser having a pulsed output waveform, and a second portion formed by a weld mark obtained by heat conduction welding with the laser, the end of the weld on the second portion side of the weld, which end includes the weld mark most recently formed in the weld, overlaps with the first portion to surround a predetermined region; and the second portion includes at least the weld mark most recently formed.

[0003] Patent Document 3 (JP 2011-173146 A) discloses a laser welding method in which a plurality of metal plates are overlapped and a predetermined weld is irradiated with laser light by a predetermined laser welding device at a predetermined weld to weld the plurality of metal plates together at the weld, the laser welding method comprising: a main welding process in which a laser light with a high heat input capable of welding the metal plates together is irradiated to the weld, and a heat supplementary process in which a laser light is irradiated to the outer periphery of the irradiation range of the laser light in the main welding process, the heat input per unit time of the laser light at the outer periphery being reduced to shallow the irradiation depth. Patent Document 4 (JP 2009-148781 A) discloses a laser welding method for spot welding a plurality of metal plates, including a metal plate on which a low-melting-point metal plating is formed, by overlapping a plurality of metal plates and irradiating the overlapping portions of the metal plates with laser light, the laser welding method comprising: a first step of irradiating a region inside the outer periphery of a portion to be welded, which has a substantially circular outer shape, with laser light to form a first welding pattern that can preheat the entire area of ​​the portion to be welded; and a second step of irradiating a region inside the outer periphery of the portion to be welded with laser light to form a ring-shaped second welding pattern that follows the outer periphery of the portion to be welded.

[0004] JP 2022-126386 A JP 2016-143656 A JP 2011-173146 A JP 2009-148781 A

[0005] In conventional welding methods for plate materials, the current path at the joint is limited to the welded portion. Therefore, there are cases where a sufficient current path cannot be secured by the weld alone to obtain mechanical strength. On the other hand, while it is possible to obtain a large current path by joining a low-melting-point plating layer, the plating layer alone cannot obtain sufficient mechanical strength. Therefore, after extensive research, the inventors discovered that by forming welds so as to sandwich the plated joint, a larger current path can be obtained at the plated joint while ensuring mechanical strength through the weld, and thus completed the present invention. That is, an object of the present invention is to provide a joined body of plate materials that has excellent mechanical joint strength and a large current capacity.

[0006] The present invention provides a metal plate having: a first plate having a first surface and a second surface opposite to the first surface; a second plate having a third surface opposite to the second surface and a fourth surface opposite to the third surface, the second plate being arranged so that a portion of the second plate overlaps a portion of the first plate; a plating layer provided on at least one of the second and third surfaces; a plated joint provided in the plating layer between the second surface of the first plate and the third surface of the second plate in the overlapping portion of the first and second plate; and a weld provided in the overlapping portion of the first and second plate, the weld penetrating the first plate in the thickness direction from the first surface to the second surface and in the thickness direction from the third surface to the fourth surface in the overlapping portion of the first and second plate, the weld contacting at least a portion of the side surface of the plated joint so as to sandwich the side surface of the plated joint. The melting point of at least the material constituting the plating layer (i), (ii), or (iii) below is lower than the melting point of the material constituting the portions of the first and second plates other than the overlapping portions: (i) a plating layer constituting the outermost layer located on the third surface side among the plating layers provided only on the second surface; (ii) a plating layer constituting the outermost layer located on the second surface side among the plating layers provided only on the third surface; (iii) a plating layer constituting the outermost layer located on the third surface side among the plating layers provided only on the second surface, and a plating layer constituting the outermost layer located on the second surface side among the plating layers provided on the third surface. In the joined plate member of the present invention, the weld contacts the side surface of the plated joint so as to sandwich at least a portion of the side surface of the plated joint. Therefore, the presence of the plated joint allows the joined plate member to have superior mechanical joint strength compared to when the first and second plates are simply joined by a weld. Furthermore, the plated joints provide a large current path.

[0007] As an aspect of the present invention, the first plate member and the second plate member may be bus bars.

[0008] In one embodiment of the present invention, the material constituting the plating layers (i) to (iii) is tin, lead, zinc, or an alloy thereof, and the material constituting the portions of the first plate material and the second plate material other than the overlapping portions may be copper, aluminum, or an alloy thereof.

[0009] In one embodiment of the present invention, the thickness of the plating layers (i) to (iii) is preferably 0.3 μm or more.

[0010] In one aspect of the present invention, the welded portion may be a continuous welded portion that surrounds the side surface of the plated joint.

[0011] As an aspect of the present invention, the welded portion may be made up of a plurality of welded portions spaced apart from one another.

[0012] It is possible to provide a joined body of plate materials that has excellent mechanical joining strength and can obtain a large current carrying capacity.

[0013] Fig. 1 is a diagram illustrating a joined body of plate materials according to one embodiment, Fig. 2 is a diagram illustrating a joined body of plate materials according to another embodiment, and Fig. 3 is a diagram illustrating a joined body of plate materials according to another embodiment.

[0014] The bonded assembly of plates of the present invention comprises a first plate having a first surface and a second surface opposite the first surface, a second plate having a third surface opposite the second surface and a fourth surface opposite the third surface, and arranged so that a portion of the second plate overlaps a portion of the first plate, a plating layer provided on at least one of the second and third surfaces, a plated joint, and a weld. The plated joint is provided in the plated layer between the second surface of the first plate and the third surface of the second plate in the overlapping portion of the first and second plates. The weld penetrates the first plate in the thickness direction from the first surface to the second surface and is provided in the second plate in the thickness direction from the third surface to the fourth surface in the overlapping portion of the first and second plates, and contacts at least a portion of the side surface of the plated joint so as to sandwich the side surface. Furthermore, the melting point of at least the material constituting the plating layer of (i), (ii), or (iii) below is lower than that of the material constituting the portions of the first sheet material and the second sheet material other than the overlapping portions: (i) of the plating layers provided only on the second surface, the plating layer constituting the outermost layer (the layer closest to the third surface in the thickness direction) located on the third surface side, (ii) of the plating layers provided only on the third surface, the plating layer constituting the outermost layer (the layer closest to the second surface in the thickness direction) located on the second surface side, (iii) of the plating layers provided on the second surface, the plating layer constituting the outermost layer (the layer closest to the third surface in the thickness direction) located on the third surface side, and of the plating layers provided on the third surface, the plating layer constituting the outermost layer (the layer closest to the second surface in the thickness direction) located on the second surface side. Note that "sandwiching the sides" means that when the plated joint is viewed in a plane at a cross section parallel to any one of the first, second, third, and fourth surfaces, the side of the plated weld is sandwiched between the welds.

[0015] The plating layer may be provided on the second surface of the first sheet, on the third surface of the second sheet, or on both the second surface of the first sheet and the third surface of the second sheet. When the plating layer is provided on the second surface of the first sheet and the third surface of the second sheet, the plating layer provided on the second surface of the first sheet may be composed of the same material as the plating layer provided on the third surface of the second sheet, or may be composed of a different material. The plating layer may be composed of one layer or two or more layers, but the melting point of the material constituting at least the plating layer (i), (ii), or (iii) above is lower than the melting point of the material constituting the portions of the first sheet and the second sheet other than the overlapping portions. That is, when the plating layer is provided only on the second surface, (i) the melting point of the material constituting the outermost layer located on the third surface of the plating layer provided only on the second surface is lower than the melting point of the material constituting the portions of the first sheet and the second sheet other than the overlapping portions. When the plating layer is provided only on the third surface, (ii) the melting point of the material constituting the outermost plating layer located on the second surface side of the plating layer provided only on the third surface is lower than the melting point of the material constituting the portions of the first and second sheets other than the overlapping portions. When the plating layer is provided on both the second and third surfaces, (iii) the melting points of the material constituting the outermost plating layer located on the third surface side of the plating layer provided on the second surface and the outermost plating layer located on the second surface side of the plating layer provided on the third surface are lower than the melting points of the material constituting the portions of the first and second sheets other than the overlapping portions. In the joined sheet material of the present invention, the weld contacts the side of the plated joint so as to sandwich at least a portion of the side of the plated joint. Therefore, compared to when the first and second sheets are joined simply by a weld, the presence of the plated joint provides a larger current path. Furthermore, a joined sheet material joined with excellent joining strength can be provided.

[0016] When forming a joined assembly of plates according to the present invention, a laser is irradiated onto the first and second plates, melting and solidifying the materials that make up the first and second plates to form a weld. When the first and second plates are irradiated with a laser, the portion of the plating layer near the weld becomes hot. Since the plating layer has a lower melting point than the material that makes up the portions of the first and second plates other than the overlapping portions, it melts easily. Therefore, in the portion of the plating layer near the weld, the molten components of the first and second plates and the plating layer diffuse and melt and solidify, forming a plated joint. As a result, a weld is formed that contacts at least a portion of the side surface of the plated joint so as to sandwich the side surface. The size and shape of the weld are not particularly limited as long as it is formed in the overlapping portion of the first and second plates and can sufficiently join the first and second plates. There may be one or more welds. The welds need only be in contact with the side surfaces of the plated joints so as to sandwich at least a portion of the side surfaces (part or all of the side surfaces) of the plated joints. The plated joints need only be located in the overlapping portions of the first and second plates, and the size and number of the plated joints are not particularly limited. The welds and plated joints can be confirmed using Auger electron spectroscopy, electron beam microanalyzers, X-ray fluorescence analysis, etc. The interiors of the welds and plated joints can be confirmed by removing the surfaces of the welds and plated joints by polishing, ion sputtering, etc. to expose their cross sections, and then performing the above-mentioned analysis.

[0017] The first plate material and the second plate material are preferably bus bars. By using the joined plate material of the present invention, a bus bar having excellent mechanical strength and a large current capacity can be obtained.

[0018] The material constituting at least the plating layer (i), (ii), or (iii) (the material constituting the portion other than the plating joint within the plating layer and the outer portion described below) is not particularly limited as long as its melting point is lower than the melting point of the material constituting the portion other than the overlapping portion of the first and second sheets. The material constituting the plating layer is preferably tin, lead, zinc, or an alloy thereof, and the material constituting the portion other than the overlapping portion of the first and second sheets is preferably copper, aluminum, or an alloy thereof. Specific examples of tin-zinc alloys constituting the plating layer include alloys containing 70 to 85% by mass of tin and 15 to 30% by mass of zinc. Specific examples of alloys constituting the portion other than the overlapping portion of the first and second sheets include alloys of copper containing tin, aluminum containing silicon, and aluminum containing magnesium. By using the above-described materials for the plating layer and the first and second sheets, the plating layer can be easily melted during laser irradiation to form a weld, effectively forming a plated joint. Furthermore, a large current capacity can be achieved in the joined sheet metal. The components of the plated joint vary depending on the components of the plating layer and the first and second sheet materials, but examples of the components of the plated joint include components obtained by diffusion between the components of the plating layer and the components of the first sheet material, and components obtained by diffusion between the components of the plating layer and the components of the second sheet material.

[0019] The thickness of the plating layer is preferably 0.3 μm or more, more preferably 1 μm or more, and even more preferably 3 μm or more. When the thickness of the plating layer is within the above range, the components constituting the first and second plate materials are sufficiently diffused into the plating layer during laser irradiation to form the weld, and the plated joint can be effectively formed.

[0020] When there is only one weld, the weld is preferably a continuous weld that surrounds the side surface of the plated joint. In this case, the plated joint is located inside the continuous weld that surrounds the side surface, which protects the plated joint from mechanical loads and ensures a current path between the first plate and the second plate.

[0021] When there are two or more welds, the welds are preferably composed of a plurality of welds spaced apart from one another, with plated joints formed between the welds. In this case, the plurality of welds spaced apart from one another are joined via the plated joints, allowing the first plate and the second plate to be joined with high joining strength.

[0022] An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a schematic diagram showing a joined body 1 of plate materials according to this embodiment. More specifically, Fig. 1(a) is a perspective view of the joined body 1 of plate materials, Fig. 1(b) is a cross-sectional view taken along the line A-A' in Fig. 1(a), and Fig. 1(c) is a cross-sectional view taken along the line B-B' in Fig. 1(b). A first plate material 3 and a second plate material 2 shown in Figs. 1(a) to 1(c) represent the ends of a bus bar.

[0023] 1(a) to 1(c), a first plate 3 having a first surface 11 and a second surface 12 located opposite the first surface 11, and a second plate 2 having a third surface 13 and a fourth surface 14 located opposite the third surface 13 are arranged. In region R, a portion of the first plate 3 and a portion of the second plate 2 are overlapped. In the overlapping portion of region R where the first plate 3 and the second plate 2 are overlapped, a weld 6 is provided so as to penetrate the first plate 3 in the thickness direction D from the first surface 11 to the second surface 12 and to penetrate the second plate 2 in the thickness direction D from the third surface 13 to the fourth surface 14. The second surface 12 of the first plate 3 faces the third surface 13 of the second plate 2, and a plating layer 4 is provided on the third surface 13 of the second plate 2. The melting point of the material constituting the outermost layer on the second surface 12 side of the plating layer 4 other than the plating joint 7a and the outer portion 7b is lower than the melting point of the material constituting the portions of the first plate material 3 and the second plate material 2 other than the overlapping portions of region R.

[0024] In this embodiment, when forming the weld 6, the laser is irradiated from the first surface 11 to the first plate 3 and the second plate 2 so as to scan along the sides of a rectangle. Therefore, a rectangular weld 6 is formed on the first surface 11. The weld 6 is provided in the overlapping portion of the region R, penetrating the first plate 3 and the second plate 2 in the thickness direction D. During laser irradiation, components of the plating layer 4, which is made of a material with a low melting point, diffuse from the plating layer 4. These components then diffuse from the first and second plate 3, 2, melting and solidifying, forming a plated joint 7a. This results in a continuous weld 6 that surrounds the side surface 8 of the plated joint 7a, and the weld 6 is in contact with the side surface 8 of the plated joint 7a. The presence of the plated joint 7a inside the continuous weld 6 in this way strengthens the bond between the first plate 3 and the second plate 2 by the plated joint 7a in addition to the weld 6, forming a strong bond between the first plate 3 and the second plate 2. Furthermore, a current path between the first plate 3 and the second plate 2 can be secured. Note that, outside the weld 6 in the plating layer 4, components of the plating layer 4 and the first and second plate 2 diffuse, melt, and solidify during laser irradiation to form the weld 6, forming an outer portion 7b. Although the outer portion 7b is in contact with the weld 6, it is not located inside the weld 6, and the weld 6 does not sandwich the outer portion 7b. Therefore, the outer portion 7b does not qualify as a plated joint. Furthermore, while FIG. 1 shows an embodiment in which the weld 6 penetrates the second plate 2 in the thickness direction D, the weld 6 does not necessarily have to penetrate the second plate 2 in the thickness direction D.

[0025] FIG. 2 is a diagram illustrating a joined plate assembly 1 according to another embodiment. More specifically, FIG. 2(a) is a perspective view of the joined plate assembly 1, FIG. 2(b) is a cross-sectional view taken along the line A-A' in FIG. 2(a), and FIG. 2(c) is a cross-sectional view taken along the line B-B' in FIG. 2(b). The joined plate assembly 1 of FIGS. 2(a) to 2(c) differs from the joined plate assembly of FIGS. 1(a) to 1(c) in that it has two welds 6 spaced apart and parallel to each other in the overlapping portion of region R where the first plate 3 and the second plate 2 are joined. In the joined plate assembly 1 of FIG. 2, a plated joint 7a is located between two welds 6 spaced apart and parallel to each other in the plating layer 4. The plated joint 7a is sandwiched between the two welds 6, and the weld 6 contacts the side surface 8 of the plated joint 7a. The presence of the plated joint 7a between the two welds 6 strengthens the bond between the first plate 3 and the second plate 2 through the welds 6 and the plated joint 7a, forming a strong bond between the first plate 3 and the second plate 2. Furthermore, a large current path can be secured between the first plate 3 and the second plate 2. In the plating layer 4, an outer portion 7b is formed near the welds 6, except for between the two welds 6, as components of the plating layer 4 and the first and second plate 2 diffuse, melt, and solidify during laser irradiation to form the welds. Although the outer portion 7b is in contact with the welds 6, it is not located between the two welds 6. Therefore, the outer portion 7b is not a plated joint. While FIG. 2 shows an embodiment in which the welds 6 penetrate the second plate 2 in the thickness direction D, the welds 6 do not necessarily have to penetrate the second plate 2 in the thickness direction D.

[0026] FIG. 3 is a diagram illustrating a joined plate assembly 1 according to another embodiment. More specifically, FIG. 3(a) is a perspective view of the joined plate assembly 1, FIG. 3(b) is a cross-sectional view taken along the line A-A' in FIG. 3(a), and FIG. 3(c) is a cross-sectional view taken along the line B-B' in FIG. 3(b). The joined plate assembly 1 of FIGS. 3(a) to 3(c) differs from the joined plate assembly of FIGS. 1(a) to 1(c) in that it has a single weld 6 bent in an inverted L-shape on the first surface 11. In the joined plate assembly 1 of FIG. 3, within the plating layer 4 in the region R where the first plate 3 and the second plate 2 are overlapped, a plated joint 7a is located inside the bent portion of the inverted L-shape so as to be sandwiched between the inverted L-shaped welds 6, and the weld 6 contacts the side surface 8 of the plated joint 7a. The presence of the plated joint 7a sandwiched between the welded portion 6 strengthens the bond between the first plate 3 and the second plate 2 by the welded portion 6 and the plated joint 7a, forming a strong bond between the first plate 3 and the second plate 2. A large current path can also be secured between the first plate 3 and the second plate 2. In the first plate 3 and the second plate 2, an outer portion 7b is formed near the welded portion 6 by diffusing, melting, and solidifying components of the plated layer 4 and the first and second plate materials 3 and 2 into the plated layer 4 during laser irradiation to form the welded portion. Although the outer portion 7b is in contact with the welded portion 6, the outer portion 7b is not located inside the curved portion of the welded portion 6, and the welded portion 6 does not sandwich the outer portion 7b. Therefore, the outer portion 7b does not qualify as a plated joint. Although FIG. 3 shows an embodiment in which the welded portion 6 penetrates the second plate material 2 in the thickness direction D, the welded portion 6 does not have to penetrate the second plate material 2 in the thickness direction D.

[0027] 1... Joint of plate materials, 2... Second plate material, 3... First plate material, 4... Plated layer, 6... Welded portion, 7a... Plated joint portion, 7b... Outer portion, 8... Side surface of plated joint portion, 11... First surface, 12... Second surface, 13... Third surface, 14... Fourth surface

Claims

1. A first plate having a first surface and a second surface opposite the first surface; a second plate having a third surface opposite the second surface and a fourth surface opposite the third surface, the second plate being arranged so that a portion of the second plate overlaps a portion of the first plate; a plating layer provided on at least one of the second and third surfaces; a plated joint provided in the plating layer between the second surface of the first plate and the third surface of the second plate in the overlapping portion of the first and second plates; and a weld provided in the overlapping portion of the first and second plates, the weld penetrating the first plate in the thickness direction from the first surface to the second surface and providing the second plate in the thickness direction from the third surface to the fourth surface, the weld contacting at least a portion of the side surface of the plated joint so as to sandwich the side surface of the plated joint therebetween. At least the melting point of the material constituting the plating layer of (i), (ii), or (iii) below is lower than the melting point of the material constituting the portions of the first and second plate materials other than the overlapping portions: (i) a plating layer constituting the outermost layer located on the third surface side of the plating layers provided only on the second surface; (ii) a plating layer constituting the outermost layer located on the second surface side of the plating layers provided only on the third surface; (iii) a joint of plating layer sheet materials comprising a plating layer constituting the outermost layer located on the third surface side of the plating layers provided on the second surface, and a plating layer constituting the outermost layer located on the second surface side of the plating layers provided on the third surface.

2. The joined plate assembly according to claim 1, wherein the first plate and the second plate are bus bars.

3. A joined body of plates according to claim 1 or 2, wherein the material constituting the plating layers (i) to (iii) is tin, lead, zinc, or an alloy thereof, and the material constituting the portions of the first plate material and the second plate material other than the overlapping portions is copper, aluminum, or an alloy thereof.

4. A joined body of plates according to claim 1 or 2, wherein the thickness of the plating layers (i) to (iii) is 0.3 μm or more.

5. A joint of plate materials as described in claim 1 or 2, wherein the weld is a continuous weld that surrounds the side surface of the plated joint.

6. A joined assembly of plate materials according to claim 1 or 2, wherein the welded portion is composed of a plurality of welded portions spaced apart from one another.

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