Joint structure

Abstract

A depression (11) is formed in a first member (10). A third member (30) is welded to the first member (10) through a perforation (21) in a second member (20). The third member (30) has an expanded portion (32) that expands outward in the radial direction on the interior of the depression (11). The second member (20) is compressed and affixed between the first member (10) and the third member (30) by the solidification shrinkage of the third member (30).

Description

[Technical Field]

[0001] The present disclosure relates to a joint structure. [Background technology]

[0002] Patent Document 1 discloses a joining structure in which a first metal material and a dissimilar material that is difficult to weld to the first metal material are overlapped, and a filler material (welding wire) is arc-welded through a penetration part of the dissimilar material.

[0003] At this time, the molten filler metal forms a flange that covers the outer periphery of the upper surface of the penetration part of the dissimilar material, thereby fixing the dissimilar material and the first metal material together by the compressive fixing force between the flange and the first metal material caused by the solidification and shrinkage of the filler metal relative to the first metal material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 030272 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the invention of Patent Document 1, for example, if the hole diameter of the through portion is small, the joining area of ​​the filler material in the first metal material also becomes small, which may result in insufficient joining strength.

[0006] The present disclosure has been made in consideration of the above points, and its purpose is to increase the joining area of ​​the filler material so as to ensure joining strength. [Means for solving the problem]

[0007] A first invention relates to a joining structure in which a first member made of a metallic material, a second member made of a material that is difficult to weld to the first member, and a third member made of a filler metal welded to the first member are joined together, wherein at least one of the first member and the second member has a recessed portion formed on a mating surface of the first member and the second member, the second member has a through portion that opens at a position corresponding to the recessed portion and has an inner diameter smaller than the opening width of the recessed portion, the third member is welded to the first member via the through portion and has a protruding portion that protrudes radially outward from the through portion inside the recessed portion, and the second member is compressed and fixed between the first member and the third member due to solidification and shrinkage of the third member relative to the first member. The third member is made of the same metal material as the first member. .

[0008] In a first aspect of the present invention, a recess is formed in at least one of the first member and the second member. The third member is welded to the first member through a through-hole in the second member. The third member has a protruding portion that protrudes radially outward within the recess. The second member is compressed and fixed between the first member and the third member due to solidification and shrinkage of the third member.

[0009] In this way, by providing a recess in at least one of the first member and the second member and welding the molten third member to the first member while spreading radially outward inside the recess, the bonding area of ​​the third member can be increased, thereby ensuring the bonding strength of the first member, second member, and third member.

[0010] A second invention is based on the first invention, wherein the recessed portion is formed in the first member.

[0011] In the second aspect of the present invention, a recess is formed in the first member, which allows the thickness of the first member to be reduced and allows the heat input required for melting of the first member to be obtained.

[0012] A third invention is the first or second invention, wherein the recessed portion is formed in the second member.

[0013] In the third invention, a recess is formed in the second member. This makes it possible to increase the bonding area of ​​the third member by providing a recess in the second member and spreading the molten third member inside the recess, even when the first member is too thin to form a recess in the first member.

[0014] A fourth invention is the device according to any one of the first to third inventions, wherein the recessed portion has a curved portion that curves toward the bottom of the recessed portion.

[0015] In a fourth aspect of the present invention, a curved portion is provided in the recess. The curved portion is curved toward the bottom of the recess. This allows the bonding area of ​​the third member to be increased compared to when the bottom of the recess is flat. In addition, the molten third member is more likely to flow toward the center of the through-hole.

[0016] A fifth invention is the device according to any one of the first to third inventions, wherein the recessed portion has an inclined portion inclined toward the bottom of the recessed portion.

[0017] In a fifth aspect of the present invention, the recessed portion is provided with an inclined portion. The inclined portion is inclined toward the bottom of the recessed portion. This allows the bonding area of ​​the third member to be increased compared to when the bottom of the recessed portion is flat. In addition, the molten third member is more likely to flow toward the center of the through-hole.

[0018] A sixth invention is related to any one of the first to third inventions, wherein the recessed portion has a first recessed portion and a second recessed portion formed in the bottom of the first recessed portion.

[0019] In the sixth aspect of the present invention, the second recess is formed at the bottom of the first recess, thereby increasing the bonding area of ​​the third member compared to when the bottom of the first recess is a flat surface. [Effects of the Invention]

[0020] According to the present disclosure, the joining area of ​​the filler material can be increased to ensure joining strength. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a side cross-sectional view for explaining a joint structure according to the first embodiment. [Figure 2] FIG. 2 is a side cross-sectional view for explaining a joint structure according to the second embodiment. [Figure 3] FIG. 3 is a side cross-sectional view for explaining a joint structure according to the third embodiment. [Figure 4] FIG. 4 is a side cross-sectional view for explaining a joint structure according to the fourth embodiment. [Figure 5] FIG. 5 is a side cross-sectional view for explaining a joint structure according to the fifth embodiment. [Figure 6] FIG. 6 is a side cross-sectional view for explaining a joint structure according to the sixth embodiment. [Figure 7] FIG. 7 is a side cross-sectional view for explaining a joint structure according to the seventh embodiment. [Figure 8] FIG. 8 is a side cross-sectional view for explaining a joint structure according to the eighth embodiment. [Figure 9] FIG. 9 is a side cross-sectional view for explaining a joint structure according to the ninth embodiment. [Figure 10] FIG. 10 is a plan view showing the configuration of the first member according to the tenth embodiment. [Figure 11] FIG. 11 is a side cross-sectional view for explaining the joining structure. [Figure 12] FIG. 12 is a plan view showing the configuration of the first member according to the eleventh embodiment. [Figure 13] FIG. 13 is a side cross-sectional view for explaining the joining structure. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0023] First Embodiment FIG. 1 shows a joining structure for joining together a first member 10 made of a metal material, a second member 20 made of a material that is difficult to weld to the first member 10, and a third member 30 made of a filler material.

[0024] The first member 10 is a plate-like member made of a metal material. The first member 10 has a recessed portion 11 formed to a depth that does not penetrate the first member 10 in the thickness direction. The recessed portion 11 is formed on the overlapping surface of the first member 10 and the second member 20. In the example shown in FIG. 1, the recessed portion 11 is formed as a circular recess that opens upward. The opening width of the recessed portion 11 is larger than the inner diameter of the through portion 21 of the second member 20, which will be described later. The recessed portion 11 is formed by, for example, lathe processing or laser processing.

[0025] The second member 20 is a plate-like member made of a material that is difficult to weld to the first member 10. The second member 20 is placed on top of the first member 10. The second member 20 has a circular through-hole 21. The through-hole 21 opens at a position corresponding to the recess 11 of the first member 10. The inner diameter of the through-hole 21 is smaller than the opening width of the recess 11.

[0026] In this embodiment, the through portion 21 is described as a circular through hole, but it may be a through groove, or an elliptical or elongated through hole.

[0027] The third member 30 is made of a filler metal that is the same type of metal as the first member 10. Here, the term "homogeneous metal" refers to metals that can be welded to each other, and refers to metals that have good weldability, such as not only metals of the same material but also ferrous metals and non-ferrous metals. In other words, the term "homogeneous metal" refers to materials of the same type that are compatible for welding.

[0028] Specifically, the following combinations of the first member 10 and the third member 30 during welding can be cited. For example, combinations of ferrous metal materials include mild steel and mild steel, stainless steel and stainless steel, mild steel and high-tensile steel (high-tensile steel), and high-tensile steel and high-tensile steel. Furthermore, combinations of non-ferrous metal materials include aluminum and aluminum, aluminum and aluminum alloy, and aluminum alloy and aluminum alloy.

[0029] Furthermore, the second member 20 as a dissimilar material is made of a material different from the first member 10 and the third member 30 as the same type of metal material, and is made of a material that is difficult to weld to the first member 10 and the third member 30.

[0030] For example, if the first member 10 and the third member 30 as the homogeneous metal material are made of an iron-based metal material, the second member 20 as the dissimilar material is made of a non-ferrous metal material such as copper or aluminum.

[0031] In the following description, a case will be described in which mild steel is used as the first member 10, aluminum is used as the second member 20, and mild steel is used as the third member 30, which is a filler metal.

[0032] The arc welding machine 1 includes a nozzle 2 and a tip 3. The nozzle 2 supplies a shielding gas or the like to a welding point of an object to be welded. The tip 3 supplies a welding current to a third member 30.

[0033] The arc welding machine 1 generates an arc 5 by supplying a welding current while feeding a third member 30 as a welding electrode into the recess 11 through the through-hole 21. The third member 30 melted by the arc welding is fused and bonded to the first member 10, and is layered inside the through-hole 21. Inside the recess 11, the molten third member 30 spreads outward in the radial direction beyond the through-hole 21.

[0034] Furthermore, after the molten third member 30 completely fills the inside of the through portion 21, it flows out onto the periphery on the upper surface side of the through portion 21 and spreads out in a flange shape.

[0035] In the process of the molten third member 30 becoming a bead, a flange portion 31 and a protruding portion 32 are formed on the third member 30.

[0036] The flange portion 31 protrudes radially outward from the through portion 21 on the surface of the second member 20 opposite to the first member 10 (the upper surface in FIG. 1). The flange portion 31 presses the peripheral edge of the through portion 21.

[0037] The protruding portion 32 protrudes radially outward beyond the through portion 21 inside the recessed portion 11 of the first member 10. The protruding portion 32 is welded to the first member 10.

[0038] In this embodiment, the first member 10 defines a recess 11 formed on the overlapping surfaces of the first member 10 and the second member 20, and has an inner circumferential surface 11a that determines the area of ​​the recess 11 that contacts the overlapping surfaces of the first member 10 and the second member 20, and a bottom surface 11b that defines the bottom side of the recess 11. The protruding portion 32 is located within the recess 11. A gap 11c is formed between the protruding portion 32 and the inner circumferential surface 11a.

[0039] Then, as the third member 30 solidifies and shrinks relative to the first member 10, the second member 20, which is a different material, is compressed and fixed between the flange portion 31 and the first member 10.

[0040] Furthermore, the molten third member 30 becomes a bead, and the part that becomes the flange portion 31 may melt even slightly at the contact point with the second member 20, forming an intermetallic compound and possibly resulting in the presence of brittle parts; however, strength is not ensured by the molten surface that is the contact point, but by the rigidity of the flange portion 31 pressing down on the peripheral portion of the penetration portion 21.

[0041] As described above, according to the joining structure of this embodiment, the first member 10 is provided with a recess 11, and the molten third member 30 is welded to the first member 10 while spreading radially outward inside the recess 11, thereby increasing the joining area of ​​the third member 30. In particular, when the thickness of the first member 10 is thicker than the thickness of the second member 20, it is possible to ensure penetration into the first member 10 while minimizing the thermal effects on the second member 20.

[0042] This ensures the bonding strength between the first member 10, the second member 20, and the third member 30.

[0043] Second Embodiment Hereinafter, the same parts as those in the first embodiment will be denoted by the same reference numerals, and only the differences will be described.

[0044] 2, the second member 20 has a through portion 21 that opens at a position corresponding to the recessed portion 11 of the first member 10. The through portion 21 has a tapered portion 22 that tapers toward the first member 10. The inner diameter of the lower end side of the through portion 21 is smaller than the opening width of the recessed portion 11.

[0045] The third member 30 is melted by arc welding. The molten third member 30 flows along the tapered portion 22 of the through portion 21 toward the recessed portion 11 and is fused and bonded to the first member 10. Inside the recessed portion 11, the molten third member 30 spreads so as to protrude radially outward beyond the through portion 21.

[0046] Furthermore, the molten third member 30 fills up the inside of the through portion 21 and spreads onto the upper surface of the tapered portion 22 in a flange shape.

[0047] As the molten third member 30 becomes a bead, a flange portion 31 and a protruding portion 32 are formed on the third member 30. The flange portion 31 presses against the tapered portion 22 of the through portion 21. The protruding portion 32 protrudes radially outward beyond the through portion 21 inside the recessed portion 11 of the first member 10. The protruding portion 32 is welded to the first member 10.

[0048] Then, as the third member 30 solidifies and shrinks relative to the first member 10, the second member 20, which is a different material, is compressed and fixed between the flange portion 31 and the first member 10.

[0049] As described above, according to the joining structure of this embodiment, by providing the tapered portion 22 in the through portion 21, the molten third member 30 can easily flow toward the recessed portion 11. Furthermore, by solidifying the flange portion 31 into a shape that follows the tapered portion 22, the thickness of the flange portion 31 that protrudes from the second member 20 can be reduced.

[0050] Third Embodiment 3, the second member 20 has a step portion 25 that opens on the surface opposite to the first member 10 (the upper surface in FIG. 3), and a through portion 21 formed on the bottom surface of the step portion 25. The inner diameter of the through portion 21 is smaller than the opening width of the recessed portion 11.

[0051] The third member 30 is melted by arc welding. The melted third member 30 is melt-bonded to the first member 10. Inside the recess 11, the melted third member 30 spreads so as to protrude radially outward beyond the through-hole 21.

[0052] Furthermore, after the molten third member 30 completely fills the inside of the through portion 21, it flows out onto the periphery on the upper surface side of the through portion 21, that is, onto the bottom surface of the step portion 25, and spreads out in a flange shape.

[0053] As the molten third member 30 becomes a bead, a flange portion 31 and a protruding portion 32 are formed on the third member 30. The flange portion 31 presses the peripheral edge of the through-hole 21. The protruding portion 32 protrudes radially outward beyond the through-hole 21 inside the recess 11 of the first member 10. The protruding portion 32 is welded to the first member 10.

[0054] Then, as the third member 30 solidifies and shrinks relative to the first member 10, the second member 20, which is a different material, is compressed and fixed between the flange portion 31 and the first member 10.

[0055] As described above, according to the joining structure of this embodiment, the flange portion 31 of the third member 30 is disposed within the step portion 25, and the flange portion 31 can be prevented from protruding from the second member 20.

[0056] Fourth Embodiment As shown in Fig. 4, the second member 20 has a step portion 25 that opens on the surface opposite to the first member 10 (the upper surface in Fig. 4), and a through portion 21 formed on the bottom surface of the step portion 25. The bottom surface of the step portion 25 is inclined toward the through portion 21. The inner diameter of the through portion 21 is smaller than the opening width of the recess portion 11.

[0057] The third member 30 is melted by arc welding. The melted third member 30 is melt-bonded to the first member 10. Furthermore, when the melted third member 30 falls on the inclined surface of the step portion 25, it flows along the inclined surface of the step portion 25 toward the through-portion 21 and is melt-bonded to the first member 10. Inside the recess portion 11, the melted third member 30 spreads so as to protrude radially outward beyond the through-portion 21.

[0058] Furthermore, after the molten third member 30 fills the inside of the through-hole 21, it flows out onto the peripheral portion on the upper surface side of the through-hole 21, i.e., onto the bottom surface of the step portion 25, and spreads out in a flange shape onto the inclined surface of the step portion 25.

[0059] As the molten third member 30 becomes a bead, a flange portion 31 and a protruding portion 32 are formed on the third member 30. The flange portion 31 presses the inclined surface of the step portion 25. The protruding portion 32 protrudes radially outward beyond the through portion 21 inside the recessed portion 11 of the first member 10. The protruding portion 32 is welded to the first member 10.

[0060] Then, as the third member 30 solidifies and shrinks relative to the first member 10, the second member 20, which is a different material, is compressed and fixed between the flange portion 31 and the first member 10.

[0061] As described above, according to the joining structure of this embodiment, by inclining the bottom surface of the step portion 25 toward the through portion 21, the molten third member 30 can easily flow toward the through portion 21.

[0062] Furthermore, by arranging the flange portion 31 of the third member 30 within the step portion 25, it is possible to prevent the flange portion 31 from protruding from the second member 20.

[0063] Fifth Embodiment 5, the second member 20 has a through portion 21 that opens at a position corresponding to the recessed portion 11 of the first member 10. The inner diameter of the through portion 21 is smaller than the opening width of the recessed portion 11.

[0064] The third member 30 is melted by arc welding. The melted third member 30 is melt-bonded to the first member 10. Inside the recess 11, the melted third member 30 spreads so as to protrude radially outward beyond the through-hole 21.

[0065] Then, the nozzle 2 of the arc welding machine 1 is rotated along the peripheral edge of the penetration portion 21, thereby supplying the molten third member 30 to the peripheral edge of the penetration portion 21. As a result, the molten third member 30 fills up the inside of the penetration portion 21 and spreads in a flange shape around the peripheral edge on the upper surface side of the penetration portion 21.

[0066] As the molten third member 30 becomes a bead, a flange portion 31 and a protruding portion 32 are formed on the third member 30. The flange portion 31 presses the peripheral edge of the through-hole 21. The protruding portion 32 protrudes radially outward beyond the through-hole 21 inside the recess 11 of the first member 10. The protruding portion 32 is welded to the first member 10.

[0067] Then, as the third member 30 solidifies and shrinks relative to the first member 10, the second member 20, which is a different material, is compressed and fixed between the flange portion 31 and the first member 10.

[0068] As described above, according to the joining structure of this embodiment, the nozzle 2 of the arc welding machine 1 is rotated and arc welding is performed on the peripheral portion of the penetration portion 21 in a spiral trajectory using AC welding or short-circuit welding, which has low heat input, thereby making it possible to form the flange portion 31 while suppressing heat input.

[0069] Sixth Embodiment 6, the second member 20 has a through portion 21 that opens at a position corresponding to the recessed portion 11 of the first member 10. The inner diameter of the through portion 21 is smaller than the opening width of the recessed portion 11.

[0070] The third member 30 is melted by arc welding. The third member 30 has a first joint portion 35 welded to the first member 10 and a second joint portion 36 welded to the first joint portion 35 to form the flange portion 31.

[0071] Specifically, when the molten third member 30 is welded to the first member 10 through the through-hole 21, short-circuit arc welding is performed with a heat input required for penetration, with the arc 5 spreading only slightly, to form the first joint 35. The first joint 35 has a protruding portion 32. The protruding portion 32 is formed when the molten third member 30 protrudes radially outward beyond the through-hole 21 inside the recess 11.

[0072] Thereafter, pulse welding is performed using a pulse waveform that alternates between peak current and base current in positive polarity DC welding or polarity-switching AC welding, so that the arc 5 spreads widely and the amount of deposition can be increased by increasing the heat input to the filler metal side as the welding electrode with a low heat input that does not melt the second member 20. In pulse welding, a molten metal droplet generated at the tip of the filler metal detaches from the filler metal and migrates to the flange portion 31 or the second member 20 once per pulse consisting of the peak current and the base current.

[0073] Here, positive polarity DC welding refers to welding using DC current, in which the filler metal as the welding electrode is the negative electrode (minus) and the first member 10 and the second member 20 as the base metal are the positive electrode (plus), thereby increasing the heat input to the filler metal as the welding electrode. This reduces the heat input to the base metal and promotes melting of the filler metal as the welding electrode.

[0074] Furthermore, AC welding using AC with switched polarity is a welding method in which, for example, peak current is negative and base current is positive, so that the filler metal as the welding electrode is negative and the first member 10 and second member 20 as the base metal are positive, thereby increasing the heat input to the filler metal as the welding electrode at the peak current and performing welding. This reduces the heat input to the base metal and promotes melting of the filler metal as the welding electrode.

[0075] Although pulse welding with positive polarity is described above, short-circuit arc welding, in which an arc state and a short-circuit state are repeated, may be performed as a welding method in which the spread of the arc 5 is small but the heat input to the second member 20 is suppressed.

[0076] As the molten third member 30 becomes a bead, a first bonding portion 35 and a second bonding portion 36 are formed on the third member 30. The first bonding portion 35 is melt-bonded to the first member 10 inside the recess 11. The second bonding portion 36 is melt-bonded to the first bonding portion 35 to form a flange portion 31 that presses against the peripheral edge of the through portion 21.

[0077] It is preferable to weld the upper part of the first bonding portion 35 so that the center is recessed. This makes it easier to determine the welding position when welding the second bonding portion 36 to the first bonding portion 35. Furthermore, the molten second bonding portion 36 tends to gather at the recessed center of the first bonding portion 35, making it possible to more uniformly shape the second bonding portion 36.

[0078] Then, as the third member 30 solidifies and shrinks relative to the first member 10, the second member 20, which is a different material, is compressed and fixed between the flange portion 31 and the first member 10.

[0079] As described above, according to the joining structure of this embodiment, by forming the third member 30 into the first joining portion 35 and the second joining portion 36, it is possible to select welding methods or welding conditions that take into account the material properties of the second member 20.

[0080] Seventh Embodiment 7, the second member 20 has a step portion 25 that opens on the surface opposite to the first member 10 (the upper surface in FIG. 7), and a through portion 21 formed on the bottom surface of the step portion 25. The inner diameter of the through portion 21 is smaller than the opening width of the recessed portion 11.

[0081] The third member 30 is melted by arc welding. The third member 30 has a first joint portion 35 welded to the first member 10 and a second joint portion 36 welded to the first joint portion 35 to form the flange portion 31.

[0082] The first joint portion 35 is melt-bonded to the first member 10. Inside the recess 11, the molten third member 30 spreads so as to protrude radially outward beyond the through-hole 21. The first joint portion 35 has a protruding portion 32 welded to the first member 10.

[0083] The second bonding portion 36 is melt-bonded to the first bonding portion 35. The second bonding portion 36 flows out onto the peripheral edge portion on the upper surface side of the through portion 21, i.e., onto the bottom surface of the step portion 25, and spreads out in a flange shape. The second bonding portion 36 has a flange portion 31 that presses against the peripheral edge portion of the through portion 21.

[0084] As the molten third member 30 becomes a bead, a first bonding portion 35 and a second bonding portion 36 are formed on the third member 30. The first bonding portion 35 is melt-bonded to the first member 10 inside the recess 11. The second bonding portion 36 is melt-bonded to the first bonding portion 35 to form a flange portion 31 that presses against the peripheral edge of the through portion 21.

[0085] Then, as the third member 30 solidifies and shrinks relative to the first member 10, the second member 20, which is a different material, is compressed and fixed between the flange portion 31 and the first member 10.

[0086] As described above, according to the joining structure of this embodiment, the flange portion 31 of the third member 30 is disposed within the step portion 25, and the flange portion 31 can be prevented from protruding from the second member 20.

[0087] Eighth Embodiment As shown in Fig. 8, the first member 10 has a recessed portion 11 formed to a depth that does not penetrate the first member 10 in the thickness direction. The recessed portion 11 is formed on the overlapping surfaces of the first member 10 and the second member 20. In the example shown in Fig. 8, the recessed portion 11 is formed as a circular recess that opens upward.

[0088] The second member 20 has a recessed portion 11 formed to a depth that does not penetrate the second member 20 in the thickness direction, and a through portion 21. The recessed portion 11 is formed on the overlapping surface of the first member 10 and the second member 20. In the example shown in FIG. 8, the recessed portion 11 is formed as a circular recess that opens downward. The recessed portion 11 of the first member 10 and the recessed portion 11 of the second member 20 are formed with the same opening width.

[0089] The through portion 21 opens at a position corresponding to the recessed portion 11 of the first member 10 and the second member 20. The inner diameter of the through portion 21 is smaller than the opening width of the recessed portion 11.

[0090] The third member 30 is melted by arc welding. The melted third member 30 is melt-bonded to the first member 10. Inside the recess 11, the melted third member 30 spreads so as to protrude radially outward beyond the through-hole 21.

[0091] Furthermore, after the molten third member 30 completely fills the inside of the through portion 21, it flows out onto the periphery on the upper surface side of the through portion 21 and spreads out in a flange shape.

[0092] As the molten third member 30 becomes a bead, a flange portion 31 and a protruding portion 32 are formed on the third member 30. The flange portion 31 presses the peripheral edge of the through-hole 21. The protruding portion 32 protrudes radially outward beyond the through-hole 21 inside the recessed portion 11 of the first member 10 and the second member 20. The protruding portion 32 is welded to the first member 10.

[0093] Then, as the third member 30 solidifies and shrinks relative to the first member 10, the second member 20, which is a different material, is compressed and fixed between the flange portion 31 and the first member 10.

[0094] As described above, according to the joining structure of this embodiment, by providing recesses 11 in the first member 10 and the second member 20 and spreading the molten third member 30 inside the recesses 11, the joining area of ​​the third member 30 can be increased.

[0095] If the thickness of the first member 10 is so thin that it is difficult to form the recessed portion 11 in the first member 10, the recessed portion 11 may be provided only in the second member 20.

[0096] Ninth Embodiment 9, the first member 10 has a recessed portion 11 formed to a depth that does not penetrate the first member 10 in the thickness direction. The recessed portion 11 has a curved portion 12 that curves toward the bottom of the recessed portion 11.

[0097] The second member 20 has a through portion 21 that opens at a position corresponding to the recessed portion 11 of the first member 10. The inner diameter of the through portion 21 is smaller than the opening width of the recessed portion 11.

[0098] The third member 30 is melted by arc welding. The molten third member 30 flows along the curved portion 12 of the recessed portion 11 and is fused and bonded to the first member 10. Inside the recessed portion 11, the molten third member 30 spreads so as to protrude radially outward beyond the through portion 21.

[0099] In this embodiment, the first member 10 defines a recess 11 formed on the overlapping surfaces of the first member 10 and the second member 20, and has an inner circumferential surface 11a that determines the area of ​​the recess 11 that contacts the overlapping surfaces of the first member 10 and the second member 20, and a bottom surface 11b that defines the bottom side of the recess 11 (the inner surface of the curved portion). Note that if the inner circumferential surface 11a and the bottom surface 11b that define the recess 11 are configured as a single curved line, the inner circumferential surface 11a and the bottom surface 11b may be expressed as a single surface, or the inner circumferential surface 11a and the bottom surface 11b may be combined to define the recess 11 as the inner circumferential surface 11a. Specifically, the area of ​​the recess 11 that contacts the overlapping surfaces of the first member 10 and the second member 20 is defined by the boundary where the recess 11 contacts the overlapping surfaces of the first member 10 and the second member 20. The protruding portion 32 is located within the recessed portion 11. A gap 11c is formed between the protruding portion 32 and the inner peripheral surface 11a.

[0100] Furthermore, the molten third member 30 fills up the inside of the through-hole 21 and spreads onto the upper surface of the second member 20 in a flange shape.

[0101] As the molten third member 30 becomes a bead, a flange portion 31 and a protruding portion 32 are formed on the third member 30. The flange portion 31 presses against the tapered portion 22 of the through portion 21. The protruding portion 32 protrudes radially outward beyond the through portion 21 inside the recessed portion 11 of the first member 10. The protruding portion 32 is welded to the first member 10.

[0102] Then, as the third member 30 solidifies and shrinks relative to the first member 10, the second member 20, which is a different material, is compressed and fixed between the flange portion 31 and the first member 10.

[0103] As described above, according to the joining structure of this embodiment, by providing a curved portion 12 in the recessed portion 11, the joining area of ​​the third member 30 can be increased compared to when the bottom of the recessed portion 11 is a flat surface.

[0104] Tenth Embodiment 10 and 11, the first member 10 has a recess 11 formed to a depth that does not penetrate the first member 10 in the thickness direction. The recess 11 has an inclined portion 13 that is inclined toward the bottom of the recess 11.

[0105] The second member 20 has a through portion 21 that opens at a position corresponding to the recessed portion 11 of the first member 10. The inner diameter of the through portion 21 is smaller than the opening width of the recessed portion 11.

[0106] The third member 30 is melted by arc welding. The molten third member 30 flows along the inclined portion 13 of the recessed portion 11 and is fused and bonded to the first member 10. Inside the recessed portion 11, the molten third member 30 spreads so as to protrude radially outward beyond the through portion 21.

[0107] In this embodiment, the first member 10 defines the recess 11. The recess 11 has an inner circumferential surface 11a, which determines the area of ​​the recess 11 that contacts the overlapping surfaces of the first member 10 and the second member 20, and a bottom surface 11b, which defines the bottom side of the recess 11, as the inner surface of the inclined portion. When the inner circumferential surface 11a and the bottom surface 11b that define the recess 11 are continuous inclined surfaces with a predetermined inclination angle, the inner circumferential surface 11a and the bottom surface 11b may be expressed as a single inclined surface, or the inner circumferential surface 11a and the bottom surface 11b may be combined to define the recess 11 as the inner circumferential surface 11a. Specifically, the area of ​​the recess 11 that contacts the overlapping surfaces of the first member 10 and the second member 20 is defined by the boundary where the recess 11 contacts the overlapping surfaces of the first member 10 and the second member 20. The protrusion 32 is located within the recess 11. A gap 11c is formed between the protruding portion 32 and the inner peripheral surface 11a.

[0108] Furthermore, the molten third member 30 fills up the inside of the through-hole 21 and spreads onto the upper surface of the second member 20 in a flange shape.

[0109] As the molten third member 30 becomes a bead, a flange portion 31 and a protruding portion 32 are formed on the third member 30. The flange portion 31 presses against the tapered portion 22 of the through portion 21. The protruding portion 32 protrudes radially outward beyond the through portion 21 inside the recessed portion 11 of the first member 10. The protruding portion 32 is welded to the first member 10.

[0110] Then, as the third member 30 solidifies and shrinks relative to the first member 10, the second member 20, which is a different material, is compressed and fixed between the flange portion 31 and the first member 10.

[0111] As described above, according to the joining structure of this embodiment, by providing an inclined portion 13 in the recessed portion 11, the joining area of ​​the third member 30 can be increased compared to when the bottom of the recessed portion 11 is a flat surface.

[0112] Eleventh Embodiment 12 and 13, the first member 10 has a recess 11 formed to a depth that does not penetrate the first member 10 in the thickness direction. The recess 11 has a first recess 14 that opens upward, and a plurality of second recesses 15 formed at the bottom of the first recess 14. The second recesses 15 are formed in a tapered shape that tapers downward.

[0113] The second member 20 has a through portion 21 that opens at a position corresponding to the recessed portion 11 of the first member 10. The inner diameter of the through portion 21 is smaller than the opening width of the recessed portion 11.

[0114] The third member 30 is melted by arc welding. The molten third member 30 flows toward the bottom of the first recess 14, disperses into the multiple second recesses 15, and is fused and bonded to the first member 10. Inside the recess 11, the molten third member 30 spreads so as to protrude radially outward beyond the through-hole 21.

[0115] Furthermore, the molten third member 30 fills up the inside of the through-hole 21 and spreads onto the upper surface of the second member 20 in a flange shape.

[0116] As the molten third member 30 becomes a bead, a flange portion 31 and a protruding portion 32 are formed on the third member 30. The flange portion 31 presses against the tapered portion 22 of the through portion 21. The protruding portion 32 protrudes radially outward beyond the through portion 21 inside the recessed portion 11 of the first member 10. The protruding portion 32 is welded to the first member 10.

[0117] Then, as the third member 30 solidifies and shrinks relative to the first member 10, the second member 20, which is a different material, is compressed and fixed between the flange portion 31 and the first member 10.

[0118] As described above, according to the joining structure of this embodiment, by providing multiple second recesses 15 at the bottom of the first recess 14, the joining area of ​​the third member 30 can be increased compared to when the bottom of the first recess 14 is a flat surface.

[0119] Other Embodiments The above embodiment may be configured as follows.

[0120] In the present embodiment, arc welding is performed on the first member 10, but the present invention is not limited to this. Specifically, the filler material used as the third member 30 can be of a consumable electrode type (consumable electrode type) or a non-consumable electrode type (non-consumable electrode type). Therefore, for example, instead of a welding wire used as a consumable electrode type (consumable electrode type) filler material for the third member 30, laser filler welding may be performed on the first member 10 using a filler wire as a non-consumable electrode type (non-consumable electrode type) filler material.

[0121] In laser filler welding, a laser is irradiated onto the first member 10 to ensure thorough penetration of the surface of the first member 10, and then the laser is irradiated only onto the filler wire that is supplied, melting the filler wire that is the third member 30. This makes it possible to completely fill the inside of the penetration portion 21 with the third member 30 while suppressing heat input to the second member 20.

[0122] Furthermore, by defocusing the laser to reduce the power density and ensuring a large beam diameter, the outer periphery of the laser beam diameter can be used to preheat the second member 20. This allows the molten filler wire, which is the third member 30, to easily fit into the second member 20.

[0123] Furthermore, the combination of the shape of the recessed portion 11 of the first member 10 and the shape of the through portion 21 of the second member 20 described in this embodiment is merely an example, and other combinations may be used. [Industrial Applicability]

[0124] As described above, the present disclosure has the highly practical effect of increasing the joining area of ​​the filler material and ensuring joining strength, and is therefore extremely useful and has high industrial applicability. [Explanation of symbols]

[0125] 10 First member 11 Recess 12 Curved section 13 Slope 14 First recess 15 Second recess 20 Second member 21 Penetration 30 Third Member 32 Overhang

Claims

1. A joining structure in which a first member made of a metal material, a second member made of a material that is difficult to weld to the first member, and a third member made of a filler material welded to the first member are joined together, At least one of the first member and the second member has a recessed portion formed on the overlapping surfaces of the first member and the second member, and the second member has a through portion that opens at a position corresponding to the recessed portion and has an inner diameter smaller than the opening width of the recessed portion, the third member has a protruding portion that is welded to the first member through the through portion and that protrudes radially outward beyond the through portion within the recessed portion, A joining structure characterized in that the second member is compressed and fixed between the first member and the third member due to solidification and shrinkage of the third member relative to the first member, and the third member is made of the same type of metal material as the first member.

2. In claim 1, A joining structure, characterized in that the recessed portion is formed in the first member.

3. In claim 1 or 2, A joining structure, characterized in that the recessed portion is formed in the second member.

4. In any one of claims 1 to 3, A joining structure, wherein the recess has a curved portion that curves toward the bottom of the recess.

5. In any one of claims 1 to 3, A joining structure, wherein the recess has an inclined portion inclined toward the bottom of the recess.

6. In any one of claims 1 to 3, A joining structure, wherein the recessed portion has a first recessed portion and a second recessed portion formed at the bottom of the first recessed portion.

7. In any one of claims 1 to 6, At least one of the first member and the second member has an inner circumferential surface and a bottom surface that define the recessed portion, the protruding portion is located within the recessed portion, A joining structure characterized in that a gap is formed between the protruding portion and the inner peripheral surface.

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