Welded joint manufacturing method, welded joint and automotive component

Abstract

To facilitate formation of an appropriate gap between an end face of a general part of a first plate and a top face of a bent part of a second plate in welding in a welding method for forming a weld bead between the end face of the general part of the first plate and the top face of the bent part of the second plate.SOLUTION: A weld joint manufacturing method in the present disclosure includes: a process in which an end face of a general part 11 of a first plate 10 is brought into contact with an irregular shape part 24 of a second plate 20, thereby positioning the first plate 10 and the second plate 20; and a process in which a weld bead is formed between the end face of the general part 11 of the first plate 10 and a top face of a bent part 23 of the second plate 20.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a welded joint, a welded joint, and an automotive component. [Background technology]

[0002] A method of arc welding two metal plates (a first plate and a second plate) is known in which a bent portion is formed in the second plate by bending it downward relative to its general portion, and the upper surface of this bent portion is arc welded to the end surface of the general portion of the first plate (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 008655 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above welding method, forming an appropriate gap between the end surface of the general portion of the first plate and the upper surface of the bent portion of the second plate during welding can be important in order to prevent welding defects. However, forming an appropriate gap requires detailed control of the first and second plates, which increases the equipment costs.

[0005] One object of the present disclosure is to facilitate the formation of an appropriate gap between the end face of the general portion of the first plate and the upper surface of the bent portion of the second plate during welding in a welding method for forming a weld bead between the end face of the general portion of the first plate and the upper surface of the bent portion of the second plate. [Means for solving the problem]

[0006] The gist of the present disclosure is as follows.

[0007] [1] A method of manufacturing a welded joint by arc welding a first plate and a second plate, the first plate has a general portion, the second plate has a general portion, a bent portion bent downward with respect to the general portion, and a non-standard portion having a shape different from that of the bent portion, the non-standard portion is configured such that a gap is formed between the upper surface of the bent portion of the second plate and the end surface of the general portion of the first plate by bringing the end surface of the general portion of the first plate into contact with the non-standard portion, the method includes, a step of determining the positions of the first plate and the second plate by bringing the end surface of the general portion of the first plate into contact with the non-standard portion of the second plate, a step of forming a weld bead between the end surface of the general portion of the first plate and the upper surface of the bent portion of the second plate, A method of manufacturing a welded joint.

[0008] In this aspect, a bent portion is formed on the second plate on the lower surface side with respect to its general portion, and the upper surface of this bent portion and the end surface of the general portion of the first plate are arc welded. As a result, compared with a normal fillet welded joint, it becomes possible to bring the center of the plate thickness of the general portion of the first plate and the center of the plate thickness of the general portion of the second plate closer in the plate thickness direction. That is, in a normal fillet welded joint, the centers of the plate thicknesses of the two plates are displaced by 1 / 2 of the total of the two plate thicknesses, whereas according to the above method, it becomes possible to make the displacement of the centers of the two plate thicknesses less than 1 / 2 of the total of the two plate thicknesses.

[0009] Also, in this aspect, a non-standard portion having a shape different from that of the bent portion is formed on the second plate. The non-standard portion is configured such that a gap is formed between the upper surface of the bent portion of the second plate and the end surface of the general portion of the first plate by bringing the end surface of the general portion of the first plate into contact with the non-standard portion. And the manufacturing method of this aspect includes a step of determining the positions of the first plate and the second plate by bringing the end surface of the general portion of the first plate into contact with the non-standard portion of the second plate, and a step of forming a weld bead between the end surface of the general portion of the first plate and the upper surface of the bent portion of the second plate. This makes it easier to form an appropriate gap during welding. That is, since the gap can be formed by bringing the first plate and the second plate into contact with each other, complex control for forming the gap is not required. Furthermore, by adjusting the shape of the irregularly shaped portion, the gap can be set to an appropriate size.

[0010] [2] The irregularly shaped portion has a non-bent portion connected to the general portion of the second plate without bending. [1] A method for manufacturing a welded joint according to the present invention.

[0011] [3] In the vicinity of the end surface of the general portion of the first plate, a portion to be welded to the bent portion of the second plate and a portion to be in contact with the irregularly shaped portion of the second plate have the same shape. A method for manufacturing a welded joint according to [1] or [2].

[0012] [4] The deviation of the plate thickness center between the general portion of the first plate and the general portion of the second plate is 1 / 4 or less of the total plate thickness of the first plate and the second plate, A method for manufacturing a welded joint according to any one of [1] to [3].

[0013] [5] At least one of the first plate and the second plate is a surface-treated plate that generates gas due to heat during welding. A method for manufacturing a welded joint according to any one of [1] to [4].

[0014] [6] At least one of the first plate and the second plate is a steel plate. A method for manufacturing a welded joint according to any one of [1] to [5].

[0015] [7] In the arc welding, a SUS wire is used. [6] A method for manufacturing a welded joint according to the present invention.

[0016] [8] The welded metal component of the SUS wire is 20% or more chromium by mass, The method for manufacturing a welded joint according to [7].

[0017] [9] The irregular-shaped part is set so that the gap is 15% or more and 100% or less of the thickness of the thinner one of the first plate and the second plate. The method for manufacturing a welded joint according to any one of [1] to [8].

[0018]

[10] The irregular-shaped part is a portion bent upward with respect to the general part of the second plate, and has an upper pressing part that suppresses the upward displacement of the end face of the general part of the first plate by pressing the vicinity of the end face of the general part of the first plate from the upper surface side. The method for manufacturing a welded joint according to any one of [1] to [9].

[0019]

[11] Before the arc welding, the upper pressing part has a plate edge part bent in a direction along the general part of the first plate. The method for manufacturing a welded joint according to

[10] .

[0020]

[12] The method is After the arc welding, the method further includes a step of forming a plate edge part bent in a direction along the general part of the first plate on the upper pressing part. The method for manufacturing a welded joint according to

[10] .

[0021]

[13] The irregular-shaped part has an upper and lower positioning part that determines the position of the end face of the general part of the first plate in the plate thickness direction by pressing the general part of the first plate in the plate surface direction. The method for manufacturing a welded joint according to any one of [1] to [9].

[0022]

[14] The vertical positioning portion is composed of an upper pressing portion bent upward and a lower pressing portion bent downward.

[13] A method for manufacturing a welded joint according to the present invention.

[0023]

[15] A welded joint comprising a first plate, a second plate, and a weld bead joining the first plate and the second plate, the first plate has a general portion; The second plate has a general portion, a bent portion bent downward relative to the general portion, and an irregularly shaped portion having a shape different from that of the bent portion, the weld bead has a first weld bead joining an end surface of the general portion of the first plate and an upper surface of the bent portion of the second plate, The irregularly shaped portion of the second plate and the end surface of the general portion of the first plate are in contact with or close to each other. Welded joints.

[0024]

[16] A welded joint comprising a first plate, a second plate, and a weld bead joining the first plate and the second plate, the first plate has a general portion; The second plate has a general portion, a bent portion bent downward relative to the general portion, and an irregularly shaped portion having a shape different from that of the bent portion, The weld bead is a first weld bead joining an end surface of the general portion of the first plate and an upper surface of the bent portion of the second plate; a second weld bead joining an end surface of the general portion of the first plate and the deformed portion of the second plate, Welded joints.

[0025]

[17] The first weld bead and the second weld bead are formed continuously.

[16] Welded joints as described in

[16] .

[0026]

[18] At least one of the first plate and the second plate is a surface treatment plate that generates gas due to heat during welding. The welded joint according to any one of

[15] to

[17] .

[0027]

[19] At least one of the first plate and the second plate is a steel plate. The welded joint according to any one of

[15] to

[18] .

[0028]

[20] The component of the welding bead is 11% or more of chromium by mass%. The welded joint according to

[19] .

[0029]

[21] An automotive member including the welded joint according to any one of

[15] to

[20] .

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiment for Carrying out the Invention

[0031] The method for manufacturing a welded joint of the present disclosure is a method for manufacturing a welded joint by welding a first plate 10 and a second plate 20, both of which are metal plates. The metal plate is, for example, a steel plate, an aluminum alloy plate, or a titanium alloy plate.

[0032] In the present embodiment, the end of the first plate 10 and the end of the second plate 20 are joined by welding. Note that, in this specification, the "end" of the metal plate means a region with a certain extent near the end of the metal plate.

[0033] [The first plate and the second plate before welding] In FIGS. 1 to 3, the metal plates (first plate 10, second plate 20) before welding are shown.

[0034] The first plate 10 has a general portion 11. The general portion 11 has a flat plate shape. The end face of the general portion 11 of the first plate 10 is welded to the second plate 20. The end face of the general portion 11 of the first plate 10 extends linearly.

[0035] The second plate 20 has a general portion 21. The general portion 21 has a flat plate shape. The second plate 20 has a bent portion 23. The bent portion 23 is a portion formed by bending the end of the second plate 20 toward the lower surface side. The bent portion 23 is composed of a flat plate-shaped inclined portion 231 and a bent portion 232 formed between the inclined portion 231 and the general portion 21. The bent portion 232 extends linearly along the end of the second plate 20. By forming the bent portion 232 between the general portion 21 and the inclined portion 231, the center of the plate thickness of the inclined portion 231 forms an angle of, for example, 30 degrees to 50 degrees with respect to the center of the plate thickness of the general portion 21.

[0036] The second plate 20 has a different-shaped portion 24 having a shape different from that of the bent portion 23. The irregularly shaped portion 24 is a part that determines the relative position of the first plate 10 and the second plate 20 by abutting the end face of the general portion 11 of the first plate 10 before and during welding (see Figures 2 and 3). The irregularly shaped portion 24 is configured so that, by abutting the end face of the general portion 11 of the first plate 10 against it, a gap G (see Figure 3) is formed between the upper surface of the bent portion 23 of the second plate 20 and the end face of the general portion 11 of the first plate 10.

[0037] The irregularly shaped portions 24 are formed in regions (remaining portions) of the end portion of the second plate 20 where the bent portions 23 are not formed. In other words, processed portions 22 are formed in the end portion of the second plate 20 along the direction in which the end portion extends. The processed portions 22 formed along the direction in which the end portion extends are formed as bent portions 23 or irregularly shaped portions 24 depending on their positions in the direction in which the end portion extends. The irregularly shaped portions 24 are formed in multiple locations, and the arrangement intervals between the irregularly shaped portions 24 are, for example, 50 to 150 mm.

[0038] In the first embodiment, the irregularly shaped portion 24 is composed only of a non-bent portion 24A that is connected to the general portion 21 of the second plate 20 without bending. The length (length in the X direction) of the irregularly shaped portion 24 is set so that the gap G between the upper surface of the bent portion 23 of the second plate 20 and the end face of the general portion 11 of the first plate 10 is 15% to 100% (preferably 50% to 100%) of the thickness of the thinner of the first plate 10 and the second plate 20.

[0039] The processing method (manufacturing method) of the processed portion 22 of the second plate 20 is as follows. 1. A cut is made in the end of the second plate 20 to separate the portion that will become the bent portion 23 from the portion that will become the irregularly shaped portion 24. 2. A bent portion 232 is formed at the boundary between the portion that will become the inclined portion 231 and the portion that will become the general portion 21, and the portion that will become the non-bent portion 24A of the irregularly shaped portion 24 is cut to an appropriate length.

[0040] The thickness of both metal plates (first plate 10 and second plate 20) is not particularly limited, but is set to, for example, 0.8 mm or more and 2.5 mm or less.

[0041] [Welded joint manufacturing method] The first plate 10 and the second plate 20 described above are subjected to a positioning step and an arc welding step to manufacture a welded joint.

[0042] In the positioning step, the end face of the general portion 11 of the first plate 10 is abutted against the irregularly shaped portion 24 of the second plate 20 to position it. Specifically, the first plate 10 and the second plate 20 are brought closer together in a state where the general portion 11 of the first plate 10 and the general portion 21 of the second plate 20 are parallel and the deviation between their plate thickness centers is less than half of the total plate thickness of both plates, thereby butting the end face of the general portion 11 of the first plate 10 against the irregularly shaped portion 24 (specifically, the end face of the non-bent portion 24A) of the second plate 20. Preferably, the first plate 10 and the second plate 20 are brought closer together in a state where the general portion 11 of the first plate 10 and the general portion 21 of the second plate 20 are parallel and the plate thickness centers of both plates are aligned, thereby butting the end face of the general portion 11 of the first plate 10 against the irregularly shaped portion 24 of the second plate 20 (specifically, the end face of the non-bent portion 24A).

[0043] In the arc welding step, in a positioned state, arc welding is performed from the upper surface side of the second plate 20. The arc welding method may be, for example, a wire feed control arc welding method described later in the examples, but is not limited to this. Furthermore, the welding position is not limited to downward, and the upper surface of the bent portion can be regarded as the torch surface.

[0044] Welded joint Figure 4 is a cross-sectional photograph showing the welded joint in its completed state.

[0045] A weld bead 30 is formed between the end surface of the general portion 11 of the first plate 10 and the upper surface of the bent portion 23 of the second plate 20. This weld bead corresponds to the "first weld bead" in the present disclosure. The weld bead 30 is exposed on the underside (i.e., a back bead is formed).

[0046] The general portion 11 of the first plate 10 and the general portion 21 of the second plate 20 are approximately parallel. The deviation in the thickness direction between the center of thickness of the general portion 11 of the first plate 10 and the center of thickness of the general portion 21 of the second plate 20 is less than 1 / 2 of the sum of the thicknesses of the first plate 10 and the second plate 20, preferably 1 / 4 or less, and more preferably 1 / 6 or less.

[0047] The portion corresponding to the irregularly shaped portion 24 may or may not be welded (this also applies to the second to fourth embodiments described later).

[0048] When welding is not performed on the portion corresponding to the irregularly shaped portion 24, the irregularly shaped portion 24 of the second plate 20 and the portion of the end face of the general portion 11 of the first plate 10 corresponding to the irregularly shaped portion 24 are not melted and remain in the same state as before welding. Therefore, the end face of the general portion 11 of the first plate 10 and the irregularly shaped portion 24 of the second plate 20 are in contact with or close to each other. The term "contact or proximity" as used herein is understood taking into consideration the following circumstances. That is, for example, if there are multiple deformed portions 24, it is not necessarily the case that the end face of the general portion 11 of the first plate 10 and all of the multiple deformed portions 24 of the second plate 20 abut against each other during arc welding. Furthermore, even if the end face of the general portion 11 of the first plate 10 and the deformed portions 24 of the second plate 20 abut against each other during arc welding, a small gap may be formed between them in the state of the welded members after arc welding. Therefore, a state in which the end face of the general portion 11 of the first plate 10 and the irregularly shaped portion 24 of the second plate 20 are in "contact or proximity" means, for example, a state in which the size of the gap between the end face of the general portion 11 of the first plate 10 and the irregularly shaped portion 24 of the second plate 20 is less than the plate thickness of the first plate 10.

[0049] When welding is also performed on the portion corresponding to the irregularly shaped portion 24, the state where the end face of the general portion 11 of the first plate 10 and the irregularly shaped portion 24 of the second plate 20 are in contact or close proximity cannot be confirmed in the state after welding (the welded member). In the present embodiment, since the portion where the end face of the general portion 11 of the first plate 10 and the end face of the non-bent portion 24A as the irregularly shaped portion 24 of the second plate 20 are in contact or close proximity is arc welded, a butt joint is formed. The weld bead 30 formed in this portion corresponds to the "second weld bead" of the present disclosure.

[0050] When welding is also performed on the portion corresponding to the irregularly shaped portion 24, it is preferable to continuously form the first weld bead 30 and the second weld bead 30.

[0051] <Function and Effect> Next, the function and effect in the present embodiment will be described.

[0052] In the present embodiment, a bent portion 23 is formed on the second plate 20 so as to be bent toward the lower surface side with respect to its general portion 21, and the upper surface of this bent portion 23 and the end face of the general portion 11 of the first plate 10 are arc welded. Thereby, compared with a normal fillet weld joint, it becomes possible to bring the plate thickness centers of the general portion 11 of the first plate 10 and the general portion 21 of the second plate 20 closer in the plate thickness direction. That is, in a normal fillet weld joint, the plate thickness centers of the two plates are displaced by 1 / 2 of the total thickness of the two plates, whereas according to the above method, it becomes possible to make the displacement of the plate thickness centers of the two less than 1 / 2 of the total thickness of the two. By reducing the displacement of the plate thickness centers of the general portion 11 of the first plate 10 and the general portion 21 of the second plate 20, the joint strength can be increased. The displacement of the plate thickness centers is preferably 1 / 4 or less of the total thickness of the two, and more preferably 1 / 6 or less.

[0053] In addition, in the present embodiment, a non - regular - shaped portion 24 having a shape different from that of the bent portion 23 is formed on the second plate 20. By abutting the general portion 11 of the first plate 10 against the non - regular - shaped portion 24, a gap G is formed between the upper surface of the bent portion 23 of the second plate 20 and the end surface of the general portion 11 of the first plate 10. And the manufacturing method of this aspect includes a step of determining the positions of the first plate 10 and the second plate 20 by bringing the end surface of the general portion 11 of the first plate 10 into contact with the non - regular - shaped portion 24 of the second plate 20, and a step of forming a welding bead 30 between the end surface of the general portion 11 of the first plate 10 and the upper surface of the bent portion 23 of the second plate 20. By doing so, it is easy to form an appropriate gap G during welding. That is, since the gap G can be formed by bringing the first plate 10 and the second plate 20 into contact with each other, complicated control for forming the gap G is not required. Also, by adjusting the shape of the non - regular - shaped portion 24, the gap G can be set to an appropriate size.

[0054] In the present embodiment, by bringing the end surface of the non - bent portion 24A of the second plate 20 into contact with the end surface of the general portion 11 of the first plate 10, the deviation of the plate - thickness centers of the general portion 11 of the first plate 10 and the general portion 21 of the second plate 20 can be reduced, and preferably, the plate - thickness centers of both can be made to coincide.

[0055] In the present embodiment, among the vicinity of the end surface of the general portion 11 of the first plate 10, the portion welded to the bent portion 23 of the second plate 20 and the portion abutting against the non - regular - shaped portion 24 of the second plate 20 have the same shape, and no special processing of the first plate 10 is required, which is advantageous in terms of cost.

[0056] In the present embodiment, since welding is performed in a state where a gap G is formed between the end surface of the general portion 11 of the first plate 10 and the upper surface of the bent portion 23 of the second plate 20, even when one or both of the first plate 10 and the second plate 20 are surface - treated plates, pore defects in the welding bead 30 can be suppressed. In other words, when one or both of the first plate 10 and the second plate 20 are surface-treated plates, gas is generated during welding. However, since welding is performed with a gap G formed between the end face of the general portion 11 of the first plate 10 and the upper surface of the bent portion 23 of the second plate 20, the gas can be discharged from the underside, thereby suppressing pore defects. Examples of surface-treated sheets that generate gas due to heat during welding include plated steel sheets (such as zinc-plated steel sheets) and painted steel sheets. Examples of painted steel sheets include steel sheets that are directly painted and zinc-plated steel sheets that are painted. Examples of surface-treated sheets that generate gas due to heat during welding include aluminum alloy painted sheets.

[0057] In this embodiment, preferably, one or both of the first sheet 10 and the second sheet 20 are steel sheets. Steel sheets have higher tensile strength and a larger Young's modulus than other metal sheets, which makes it easier to ensure the rigidity of formed and assembled components. Steel sheets also have good arc weldability and excellent workability, and are less expensive than other metal sheets. For these reasons, this embodiment is preferably used in automotive components that require productivity, cost, and component strength. On the other hand, when using steel sheets in automotive components that require long-term corrosion resistance, it is more preferable that the steel sheets be surface-treated steel sheets such as plated steel sheets or painted steel sheets. This embodiment is preferably used to suppress defects caused by gases generated when welding surface-treated steel sheets. Examples of surface-treated steel sheets include zinc-based plated steel sheets such as galvannealed steel sheets (GA), hot-dip galvanized steel sheets, and highly corrosion-resistant hot-dip galvanized steel sheets (SD). Painted steel sheets include unplated steel sheets coated with a resin and zinc-based plated steel sheets coated with a resin. As described above, by using a surface-treated steel sheet to improve the corrosion durability of the welded member, the corrosion resistance of the non-welded part is ensured. In addition, it is preferable to ensure the corrosion resistance of the surface of the weld metal. For this purpose, it is preferable to use a SUS wire as the welding wire. As another method, it is also conceivable to perform repair painting on the welded part after welding. However, if a SUS wire is used, an increase in cost due to the addition of the repair painting process can be avoided. A SUS wire is a welding wire mainly used for welding stainless steel sheets to each other or a stainless steel sheet and a non-stainless steel sheet, and is a welding wire whose composition is adjusted so that the weld metal becomes a component of stainless steel. Stainless steel is an alloy steel containing at least 11% by mass of chromium in iron, and the formation of a passive film by chromium suppresses the corrosion of the base material on the surface. Therefore, when one or both of the first plate 10 and the second plate 20 are surface-treated steel sheets, by applying a SUS wire to the welding wire, the weld metal exhibits high corrosion resistance due to the stainless steel component, and the non-welded part exhibits high corrosion resistance due to the surface treatment. Therefore, it is more preferable that the corrosion resistance of the entire member is excellent. A preferred example of the SUS wire applied here is a SUS wire in which the chromium in the weld metal is 20% or more by mass. More preferably, the chromium in the weld metal is 20% or more by mass, the carbon is 0.3% or less, and the nickel is 9% or more by mass. Here, the weld metal refers to the weld metal formed by performing buttering welding with the same welding wire as the welding wire used for welding in advance so that the influence of the welding target material can be ignored. Since chromium and nickel are hardly oxidized and most of them remain in the weld metal, the chromium content and nickel content of the weld metal may be read as the chromium content and nickel content of the welding wire. When welding a steel plate with such a SUS wire, a weld metal in which the welding wire and the material to be welded are diluted and mixed is formed, and it becomes possible for the weld metal to contain at least 11% or more of chromium. That is, in the present embodiment, preferably, the component of the weld bead is 11% or more of chromium by mass%. When the weld bead has the first weld bead 30 and the second weld bead 30, it is preferable that the components of both the first weld bead 30 and the second weld bead 30 are 11% or more of chromium by mass%. When welding is also performed on the portion corresponding to the irregular-shaped portion 24, from the viewpoint of productivity, it is preferable to use the same welding wire for forming the first weld bead 30 and the second weld bead 30. When the same welding wire is used, the first weld bead 30 and the second weld bead 30 have substantially equal components even with dilution by the base material. In addition, even when the material to be welded is a non-surface-treated steel plate, it is preferable to use a SUS wire for the welding wire. When a SUS wire is used for the welding wire, rusting from the weld metal surface is suppressed, and rust derived from the weld metal surface spreading to the non-welded portion is suppressed. Therefore, even when the material to be welded is a non-surface-treated steel plate, a corrosion resistance improvement effect can be expected.

[0058] In the present embodiment, the irregular-shaped portion 24 is set so that the gap G is 15% or more and 100% or less of the thickness of the thinner one of the first plate 10 and the second plate 20. Since the irregular-shaped portion 24 is set so that the gap G is within the above range, a welded joint with few welding defects can be obtained. That the above range is an appropriate range will also be explained in the examples described later. The "gap" referred to here means the shortest distance between the end face of the general portion 11 of the first plate 10 and the upper surface of the bent portion 23 of the second plate 20 in a cross-sectional view perpendicular to the welding line.

[0059] In the present embodiment, by properly using the bending structure of the end portion of the second plate 20 according to the position in the welding line direction, a portion for the basic joint form (bent portion 23) and a portion for positioning (irregular-shaped portion 24) are realized. Therefore, by simply devising the bending structure of the end portion of the second plate 20, positioning for forming the gap G is possible and simple.

[0060] <Second Embodiment> Next, a second embodiment of the present disclosure will be described.

[0061] FIG. 5 shows the second plate 120 of the second embodiment, FIG. 6 shows a state in which the first plate 10 and the second plate 120 are positioned, and FIG. 7 shows a cross-sectional view in the positioned state. The irregular-shaped portion 24 of the second plate 120 is composed of a non-bent portion 24A and an upper pressing portion 24B. The upper pressing portion 24B is a portion bent toward the upper surface side with respect to the general portion 21.

[0062] Next, the effects of the present embodiment will be described.

[0063] In the present embodiment, the irregular-shaped portion 24 is a portion bent toward the upper surface side with respect to the general portion 21, and has an upper pressing portion 24B that suppresses the upward displacement of the end surface of the general portion 11 of the first plate 10 by pressing the vicinity of the end surface of the general portion 11 of the first plate 10 from the upper surface side. Here, the “vicinity” of the end surface of the general portion 11 refers to a region including the end surface of the general portion 11 and a portion of the upper surface of the general portion 11 close to the end surface, and is a region where the upward displacement of the end surface of the general portion 11 can be effectively suppressed by bringing the upper pressing portion 24B into contact with the region. Thereby, displacement due to welding deformation (deformation of the metal plate due to heat during welding) is suppressed. Further, the operation of bringing the end surface of the general portion 11 of the first plate 10 into contact with an appropriate position of the irregular-shaped portion 24 of the second plate 20 (positioning operation performed before welding) becomes easy. That is, there is a possibility that the metal plate is deformed so as to be distorted by thermal strain during welding, and the end surface of the general portion 11 of the first plate 10 is displaced upward from an appropriate position. However, the upper pressing portion 24B presses from the upper surface side, so that the position of the end surface of the general portion 11 of the first plate 10 is suppressed from being displaced upward.

[0064] In this embodiment, the upper pressing portion 24B is formed adjacent to the non-bending portion 24A, which effectively prevents the end face of the general portion 11 of the first plate 10 from moving upward relative to the end face of the non-bending portion 24A of the second plate 20, causing the two plates to come loose from butting together.

[0065] (supplementary explanation) In the above, an example has been described in which the upper holding portion 24B is formed adjacent to the non-bending portion 24A, but the upper holding portion of the present disclosure is not limited to this.

[0066] 8, the upper holding portion 24B may have a plate-side portion 24B1 that fits along the general portion 11 of the first plate 10. This prevents the tip of the upper holding portion 24B from pointing outward from the welded member. The plate-side portion 24B1 may be formed before or after welding.

[0067] <Third embodiment> Next, a third embodiment of the present disclosure will be described.

[0068] FIG. 9 is a cross-sectional view showing the state before welding of the first plate 10 and the second plate 220 of the third embodiment.

[0069] The irregularly shaped portion 24 of the second plate 220 has an upper holding portion 24B and a lower holding portion 24C, but does not have a non-bent portion. The upper holding portion 24B is a portion bent upward relative to the general portion 21, and the lower holding portion 24C is a portion bent downward relative to the general portion 21. The general portion 11 of the first plate 10 is pressed between the upper holding portion 24B and the lower holding portion 24C, i.e., the general portion 11 of the first plate 10 is pressed in the plate surface direction, so that the position of the end face of the general portion 11 of the first plate 10 in the plate thickness direction is naturally determined. Note that in this specification, the plate surface direction refers to the direction parallel to the surface of the plate.

[0070] Next, the effects of this embodiment will be described.

[0071] In this embodiment, the second plate 220 has a structure (vertical positioning portion) that naturally determines the position in the plate thickness direction of the end face of the general portion 11 of the first plate 10 by pressing the end face of the general portion 11 of the first plate 10 against the second plate 220. This makes it easy to position the end face of the general portion 11 of the first plate 10 relative to the second plate 220. In addition, positional deviation due to welding deformation is effectively suppressed.

[0072] In this embodiment, the structure in which the position in the plate thickness direction is naturally determined by pressing the end face of the general portion 11 of the first plate 10 is configured by the upper pressing portion 24B bent upward relative to the general portion 21 and the lower pressing portion 24C bent downward relative to the general portion 21. Therefore, it can be realized with a simple structure.

[0073] In this embodiment, the end face of the bent portion 23 and the end faces of the upper pressing portion 24B and the lower pressing portion 24C are all located on the same plane before the bending process is performed. In other words, the length of the portion of the second plate 20 that will become the irregularly shaped portion 24 is not adjusted. Therefore, the process for forming the irregularly shaped portion 24 is simple.

[0074] <Fourth embodiment> Next, a fourth embodiment of the present disclosure will be described.

[0075] FIG. 10 is a cross-sectional view showing the state before welding of the first plate 10 and the second plate 320 of the fourth embodiment.

[0076] The irregularly shaped portion 24 of the second plate 320 has an upper pressing portion 24B and a lower right-angled portion 24D, but does not have a non-bent portion. The upper pressing portion 24B is a portion bent upward relative to the general portion 21, and the lower right-angled portion 24D is a portion bent downward at an angle of approximately 90 degrees relative to the general portion 21. The thickness of the first plate 10 is greater than the thickness of the second plate 20, and the end face of the general portion 11 of the first plate 10 abuts against both the upper pressing portion 24B and the lower right-angled portion 24D.

[0077] Next, the effects of this embodiment will be described.

[0078] In this embodiment, the end face of the bent portion 23 and the end faces of the upper pressing portion 24B and the lower right-angled portion 24D are all located on the same plane before bending. In other words, the length of the portion of the second plate 20 that will become the irregularly shaped portion 24 is not adjusted. Therefore, the process for forming the irregularly shaped portion 24 is simple.

[0079] [Welding material] 11 is a schematic diagram showing an example of a welded member manufactured by the method of the present disclosure, although the deformed portion 24 is not shown in this drawing.

[0080] The welded member is a member with a closed cross-sectional structure and is manufactured by joining a first member and a second member by arc welding. The cross-sectional shape of the first member is approximately U-shaped, and the cross-sectional shape of the second member is also approximately U-shaped. The first member has a processed portion 22 having a bent portion 23 and a deformed portion 24 (not shown), and the second member also has a processed portion 22 having a bent portion 23 and a deformed portion 24 (not shown). The first member and the second member are joined at the upper and lower portions of the figure using the welding method disclosed herein. In the welded member, the bent portion 23 is bent toward the inside of the closed cross-section. In this example, a portion of the first member functions as the first plate 10 and another portion functions as the second plate 20, and a portion of the second member functions as the first plate 10 and another portion functions as the second plate 20.

[0081] Examples of welded components manufactured by the method of the present disclosure include, but are not limited to, automotive components, particularly frame components for the undercarriage of an automobile (such as frame components for suspension members). [Example]

[0082] Hereinafter, an embodiment of the present disclosure will be described. The steel sheets used are shown in Table 1, and the test conditions and results are shown in Table 2.

[0083] [Table 1]

[0084]

Table 2

[0085] As the first plate, a flat steel plate was used, and as the second plate, one with a processing portion 22 formed at the end was used. The processing of the processing portion 22 of the second plate was performed by bending with a bending machine. The processing portion 22 of the second plate used a structure described as the first embodiment and a structure described as the second embodiment selectively. The arrangement interval of the irregular-shaped portion 24 (positioning structure) was 110 mm.

[0086] (Terms in Table 2) The gap means the set value by the non-bent portion. The bending angle is the angle of the inclined portion 231 with respect to the general portion 21 of the second plate 20. No upper pressing portion means the structure of the first embodiment. Having an upper pressing portion means the structure of the second embodiment.

[0087] As welding conditions, the following welding method 1 and welding method 2 were selectively used. (Welding method 1) Welding wire: YM-28 manufactured by Nippon Steel Welding & Engineering Co., Ltd. (diameter 1.2 mm) Welding power source: TPS500i manufactured by Fronius Welding mode: Wire feeding control arc welding method (CMT-MAG) Shielding gas: Ar + 20% CO2 Shielding gas flow rate: 20 l / min (Welding method 2) Welding wire: YM-309L manufactured by Nippon Steel Welding & Engineering Co., Ltd. (diameter 1.2 mm) (The chemical composition of the deposited metal is as follows. C: 0.014%, Si: 0.37%, Mn: 1.78%, Ni: 13.7%, Cr: 23.2%) Welding power source: TPS500i manufactured by Fronius Welding mode: Wire feeding control arc welding method (CMT-MIG) Shielding gas: Ar + 2% O2 Shielding gas flow rate: 20 l / min

[0088] The welding speed, welding current, and arc voltage were as shown in Table 2.

[0089] The porosity defect rate was determined by calculating the ratio of the total length of each pore in the welding direction to the total length of the weld bead including the start and end points of welding, using the X-ray transmission image of the weld bead.

[0090] <Discussion of Results> The following can be said from the results shown in Table 2. · In the example where there is no gap and they are in close contact, lack of fusion occurs, pits are generated, and the porosity defect rate is also high. · In the example where the gap is within the appropriate range (15% or more and 100% or less of the thickness of the thinner of the first and second plates), lack of fusion, melting away, and perforation do not occur, and the porosity defect rate is also low. · In the example where the gap is excessive, melting away and perforation have occurred. From the above, it was confirmed that the welding quality can be ensured by keeping the gap size within the appropriate range. Furthermore, all of Steel Plates A to F are surface-treated steel plates. It was confirmed that the welding quality can be ensured by keeping the gap size within the appropriate range in the places where porosity defects are likely to occur. In particular, Steel Plate C is a painted steel plate, and considering that porosity defects are more likely to occur due to its thick film thickness, it was confirmed that the welding quality can be ensured by keeping the gap size within the appropriate range. Also, in Welding Method 2, SUS wire is used aiming at improving corrosion resistance. It was confirmed that the present invention is also effective with the said SUS wire. Thereby, improvement of the corrosion resistance of the welded part can be expected.

[0091] Also, the following can be said from the results shown in Table 2. · In the example where there is an upper pressing part, the displacement after welding is small, while in the example where there is no upper pressing part, the displacement after welding is large. From the above, it was confirmed that the displacement after welding can be suppressed by the upper pressing part.

[0092] (supplementary explanation) In the above embodiments, an example has been described in which the end face of the general portion 11 of the first plate 10 to be welded to the second plate 20 extends linearly, and the weld line also extends linearly, but the present disclosure is not limited to this. For example, the end face of the general portion 11 of the first plate 10 may extend curvedly, and the weld line may also extend curvedly.

[0093] Furthermore, although an example has been described in which the general portion of the first plate and the general portion of the second plate are parallel to each other after welding, the present disclosure is not limited to this.

[0094] Furthermore, although an example has been described in which a plurality of deformed portions 24 are formed in the weld line direction, the present disclosure is not limited to this.

[0095] Although the example in which the deformed portion 24 and the bent portion 23 are adjacent to each other in the weld line direction in the second plate 20 before welding has been described, the present disclosure is not limited to this. The deformed portion 24 and the bent portion 23 may be spaced apart in the weld line direction.

[0096] Furthermore, although an example in which the general portion 11 and the general portion 21 are flat-plate shaped has been described, the general portion of the present disclosure is not limited to this.

[0097] Furthermore, although an example has been described in which the bent portion 23 is configured with the bent portion 232 and the flat plate-like inclined portion 231, the bent portion of the present disclosure is not limited to this.

[0098] Furthermore, although an example has been described in which the first plate 10 and the second plate 20 are separate bodies, the first plate and the second plate of the present disclosure are not limited to this. That is, the first plate and the second plate may be part of a single plate material. For example, the welding method and welding structure of the present disclosure can also be employed when a single plate material is bent or otherwise processed, and one end of the single plate material is joined to the other end of the single plate material by welding.

[0099] Furthermore, although it is ideal for the end face of the general portion 11 of the first plate 10 to abut against all of the multiple irregularly shaped portions 24 of the second plate 20, the method of the present disclosure is not limited to this.

[0100] Furthermore, although an example has been described in which no special processing is performed on the end of the general portion 11 of the first plate 10, the present disclosure is not limited to this. For example, only the portion of the end of the general portion 11 of the first plate 10 that abuts the irregularly shaped portion 24 of the second plate 20 may have a different structure. For example, only the portion of the end of the general portion 11 of the first plate 10 that abuts the irregularly shaped portion 24 of the second plate 20 may be recessed in a direction away from the second plate 20 (the left side in FIG. 3 , the −X direction). In this case, it may be possible to eliminate the need to adjust the length of the non-bent portion 24A of the irregularly shaped portion 24 of the second plate 20.

[0101] Furthermore, although a welded component having a closed cross-sectional structure has been described as a welded component manufactured by the method of the present disclosure, the welded component of the present disclosure is not limited to this, and does not have to have a closed cross-sectional structure. [Explanation of symbols]

[0102] 10 First board 11 General section of the first board 20 Second board 21 General section of the second plate 22 Processing Department 23 Bend section 24 Irregular shape part 24A Non-bending part (unusual shape part) 24B Upper holding part (irregular shape part) 24B1 Plate side 24C Lower holding part (irregular shape part) 24D Lower right angle part (unusual shape part) 30 Weld Bead 120 Second board 220 Second board 320 Second board

Claims

1. A method for manufacturing a welded joint by arc welding a first plate and a second plate, wherein the first plate has a general portion, the second plate has a general portion, a bent portion bent on the lower surface side with respect to the general portion, and a deformed portion having a shape different from that of the bent portion, the deformed portion is configured such that a gap is formed between the upper surface of the bent portion of the second plate and the end surface of the general portion of the first plate by bringing the general portion of the first plate into contact with the deformed portion, the method comprising: a step of determining the positions of the first plate and the second plate by bringing the end surface of the general portion of the first plate into contact with the deformed portion of the second plate; a step of forming a weld bead between the end surface of the general portion of the first plate and the upper surface of the bent portion of the second plate. A method for manufacturing a welded joint.

2. The deformed portion includes a non-bent portion connected to the general portion of the second plate without bending. The method for manufacturing a welded joint according to claim 1.

3. Among the vicinity of the end surface of the general portion of the first plate, the portion welded to the bent portion of the second plate and the portion in contact with the deformed portion of the second plate have the same shape. The method for manufacturing a welded joint according to claim 1 or claim 2.

4. The deviation of the center of the plate thickness between the general portion of the first plate and the general portion of the second plate is 1 / 4 or less of the total plate thickness of the first plate and the second plate. The method for manufacturing a welded joint according to any one of claims 1 to 3.

5. At least one of the first plate and the second plate is a surface treatment plate that generates gas due to heat during welding. The method for manufacturing a welded joint according to any one of claims 1 to 4.

6. At least one of the first plate and the second plate is a steel plate. The method for manufacturing a welded joint according to any one of claims 1 to 5.

7. In the arc welding, a SUS wire is used. The method for manufacturing a welded joint according to claim 6.

8. The deposited metal component of the SUS wire contains 20% or more of chromium by mass. The method for manufacturing a welded joint according to claim 7.

9. The deformed portion is set such that the gap is 15% or more and 100% or less of the thickness of the thinner one of the first plate and the second plate. The method for manufacturing a welded joint according to any one of claims 1 to 8.

10. The irregular-shaped portion is a portion bent upward with respect to the general portion of the second plate, and has an upper pressing portion that suppresses upward displacement of the end face of the general portion of the first plate by pressing the vicinity of the end face of the general portion of the first plate from the upper surface side. The method for manufacturing a welded joint according to any one of claims 1 to 9.

11. Before the arc welding, the upper pressing portion has a plate edge portion bent in a direction along the general portion of the first plate. The method for manufacturing a welded joint according to claim 10.

12. The method After the arc welding, the method further includes a step of forming a plate edge portion bent in a direction along the general portion of the first plate on the upper pressing portion. The method for manufacturing a welded joint according to claim 10.

13. The irregular-shaped portion has an upper and lower positioning portion that determines the position of the end face of the general portion of the first plate in the plate thickness direction by pressing the general portion of the first plate in the plate surface direction. The method for manufacturing a welded joint according to any one of claims 1 to 9.

14. The upper and lower positioning portion is composed of an upper pressing portion bent upward and a lower pressing portion bent downward. The method for manufacturing a welded joint according to claim 13.

15. A welded joint including a first plate, a second plate, and a welding bead that joins the first plate and the second plate, The first plate has a general portion, The second plate has a general portion, a bent portion bent downward with respect to the general portion, and an irregular-shaped portion having a shape different from that of the bent portion and separated from the bent portion. The welding bead has a first welding bead that joins the end face of the general portion of the first plate and the upper surface of the bent portion of the second plate. The irregular-shaped portion of the second plate and the end face of the general portion of the first plate are in contact with or close to each other. Welded joint.

16. A welded joint including a first plate, a second plate, and a welding bead that joins the first plate and the second plate, The first plate has a general portion, The second plate has a general portion, a bent portion bent downward with respect to the general portion, and an irregular-shaped portion having a shape different from that of the bent portion. The welding bead has a first welding bead that joins the end face of the general portion of the first plate and the upper surface of the bent portion of the second plate, and a second welding bead that joins the end face of the general portion of the first plate and the irregular-shaped portion of the second plate. Welded joint.

17. The first welding bead and the second welding bead are formed continuously. The welded joint according to claim 16.

18. At least one of the first plate and the second plate is a surface-treated plate that generates gas due to heat during welding. The welded joint according to any one of claims 15 to 17.

19. At least one of the first plate and the second plate is a steel plate. The welded joint according to any one of claims 15 to 18.

20. The component of the welding bead is 11% or more of chromium by mass%. The welded joint according to claim 19.

21. An automotive member including the welded joint according to any one of claims 15 to 20.

22. A welded joint including a first plate, a second plate, and a welding bead that joins the first plate and the second plate, The first plate has a general portion. The second plate has a general portion, a bent portion bent downward with respect to the general portion, and a different-shaped portion having a shape different from that of the bent portion. The welding bead has a first welding bead that joins an end face of the general portion of the first plate and an upper surface of the bent portion of the second plate. The different-shaped portion of the second plate and the end face of the general portion of the first plate are in contact or close to each other. At least one of the first plate and the second plate is a surface-treated plate that generates gas due to heat during welding. Welded joint.

23. A welded joint including a first plate, a second plate, and a welding bead that joins the first plate and the second plate, The first plate has a general portion. The second plate has a general portion, a bent portion bent downward with respect to the general portion, and a different-shaped portion having a shape different from that of the bent portion. The welding bead has a first welding bead that joins an end face of the general portion of the first plate and an upper surface of the bent portion of the second plate. The different-shaped portion of the second plate and the end face of the general portion of the first plate are in contact or close to each other. At least one of the first plate and the second plate is a steel plate, The component of the welding bead is 11% or more of chromium by mass%. Welded joint.

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