Welding structure of T-type welded joint

Abstract

A welding structure for a T-shaped welded joint, wherein a second substrate is welded to a first substrate in a T-shape, the welding structure of the T-shaped welded joint may include: a first substrate including a first flat portion, a second flat portion, and a bent portion formed between the first flat portion and the second flat portion; a second substrate having a bent portion formed at the end of a main body portion such that the bent portion is configured to face the first substrate; and a weld bead disposed between the bent portion of the first substrate and the bent portion of the second substrate.

Description

Technical Field

[0001] This invention relates to a welding structure for a T-type welded joint, and more specifically, to a welding structure for a T-type welded joint that can reduce stress concentration in the weld area to improve durability. Background Technology

[0002] Typically, the car body is made by welding and assembling various panels.

[0003] Welding is commonly used for vehicle body lightweighting and strength enhancement.

[0004] Depending on the properties and shape of the substrates to be welded, various welding methods can be used. One of the most typical welding methods is T-welding, in which the substrates are arranged in a T-shape relative to each other.

[0005] Figure 1 and Figure 2 This is a view showing a typical T-shaped welded structure. Figure 1 T-type flat welds are shown, and Figure 2 The example shows a flared bevel weld.

[0006] exist Figure 1 and Figure 2 Both methods illustrate the following: a second substrate 2, positioned perpendicular to the direction of gravity, is T-welded to a first substrate 1, positioned along the direction of gravity, and a weld bead 3 is formed by welding the area where the side of the first substrate 1 contacts the upper part of the second substrate 2 based on the direction of gravity. In the current case, for... Figure 2 The flared bevel welding shown in the diagram, with the end of the second substrate 2 bent into... The shape is formed to create a bent portion 2a and a vertical portion 2b.

[0007] At the same time, for Figure 1 and Figure 2 In the two types of welding shown, the first substrate 1 is linearly formed along the direction of gravity. Due to this shape, the weld bead 3 formed between the first substrate 1 and the second substrate 2 has a relatively small weld toe angle (θa) or θb relative to the first substrate 1. The reason why the weld bead 3 has a small weld toe angle θa or θb relative to the first substrate 1 is that the molten metal used for welding is concave downward under the action of gravity.

[0008] In addition, such as Figure 2 As shown, when performing bevel welding, the molten metal is not introduced into the root, so there may be an unwelded root A that does not form weld bead 3.

[0009] When the weld toe angle θa or θb is small, or when an unwelded root A appears as described above, stress may concentrate in that area, and therefore, fracture may occur.

[0010] The information disclosed in the background section of this invention is only for enhancing the understanding of the overall background of this invention, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0011] Various aspects of the present invention aim to provide a welding structure for a T-type welded joint, which is configured to reduce stress concentration in the weld area to improve durability.

[0012] According to various exemplary embodiments of the present invention, a welding structure for a T-shaped welded joint is provided, wherein a second substrate is welded to a first substrate in a T-shape. The welding structure includes: a first substrate including a first flat portion, a second flat portion, and a bent portion formed between the first flat portion and the second flat portion; a second substrate, wherein a bent portion is formed at the end of a main body portion such that the bent portion is configured to face the first substrate; and a weld bead disposed between the bent portion of the first substrate and the bent portion of the second substrate.

[0013] The first substrate can be arranged along the direction of gravity, the second substrate can be arranged in a direction perpendicular to the direction of gravity, and the bent portion of the second substrate can be bent downward along the direction of gravity.

[0014] The second substrate may have a vertical portion formed from the end of the bent portion parallel to the first substrate. The first flat portion of the first substrate may merge with the vertical portion of the second substrate. The second flat portion may extend above the first flat portion through a bent portion between the first flat portion and the second flat portion. The first flat portion and the second flat portion may be formed parallel to each other while being spaced apart from each other by a predetermined offset u.

[0015] The predetermined offset u and the thickness t of the first substrate can satisfy the following relationship 1:

[0016]

Relationship 1

[0017] u≥0.3×t.

[0018] The curved portion formed in the first substrate can be divided into: a first curved portion, which extends from the first flat portion while bending at a first curvature R1; and a second curved portion, which extends from the first curved portion while bending at a second curvature R2 and is connected to the second flat portion.

[0019] The first curvature R1 of the first bend and the second curvature R2 of the second bend, relative to the thickness t of the first substrate, can satisfy the following relationships 2 and 3, respectively:

[0020]

Relationship 2

[0021] R1≥2×t

[0022]

Relationship 3

[0023] R²≥t.

[0024] The first curved portion can be bent to protrude toward the second substrate, and the second curved portion can be bent to be recessed away from the second substrate.

[0025] The methods and apparatus of the present invention have other features and advantages that will be apparent from or set forth in more detail in conjunction with the accompanying drawings and the following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0026] Figure 1 and Figure 2 This is a view showing a typical T-shaped welded structure.

[0027] Figure 3 This is an illustrative view showing the welding structure of a T-joint according to an exemplary embodiment of the present invention.

[0028] Figure 4 This is an exemplary view showing the structure and arrangement of a first substrate and a second substrate according to various exemplary embodiments of the present invention.

[0029] Figure 5A and Figure 5B These are photographs of the cross-sections of welded products, based on comparative and example examples, after undergoing individual part durability tests.

[0030] Figure 6A and Figure 6B This is a view showing the analysis results of the stress distribution of the welded products according to the comparative example and the example when a load is applied to the welded products for stress comparison.

[0031] It should be understood that the accompanying drawings are not necessarily drawn to scale, but rather present a simplified representation of various features illustrating the basic principles of the invention. Specific design features of the invention, such as specific dimensions, orientations, positions, and shapes, as disclosed herein, will be determined in part by the particular intended application and environment of use.

[0032] In the accompanying drawings, reference numerals throughout the multiple figures indicate the same or equivalent parts of the invention. Detailed Implementation

[0033] Reference will now be made in detail to various embodiments of the invention, examples of which are shown in the accompanying drawings and described below. While the invention will be described in conjunction with exemplary embodiments thereof, it should be understood that this description is not intended to limit the invention to these exemplary embodiments. Rather, the invention is intended to cover not only these exemplary embodiments thereof, but also various alternatives, modifications, equivalents and other embodiments that may be included within the spirit and scope of the invention as defined by the appended claims.

[0034] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the exemplary embodiments described below, but may be embodied in different forms. Exemplary embodiments are provided only to complete the present invention and to enable those skilled in the art to fully understand the scope of the invention. Throughout the drawings, similar reference numerals are used to denote similar elements.

[0035] Figure 3 These are views exemplarily illustrating the welded structure of a T-joint according to various exemplary embodiments of the present invention, and Figure 4 This is an exemplary view showing the structure and arrangement of a first substrate and a second substrate according to various exemplary embodiments of the present invention.

[0036] like Figure 3 and Figure 4 As shown, a welding structure of a T-shaped weld joint in which a second substrate is T-welded to a first substrate according to various exemplary embodiments of the present invention includes: a first substrate 10, wherein bent portions 12 and 13 are formed between a first flat portion 11 and a second flat portion 14; a second substrate 20, wherein a bent portion 22 is formed at the end of a main body portion 21 such that the bent portion 22 faces the bent portions 12 and 13 of the first substrate 10; and a weld bead 30 formed between the bent portions 12 and 13 of the first substrate 10 and the bent portion 22 of the second substrate 20.

[0037] In the current context, various weldable plates can be used as the first substrate 10 and the second substrate 20, regardless of the type of material. For example, plates made of steel, aluminum (Al), magnesium (Mg), or titanium (Ti) can be used.

[0038] Meanwhile, before welding, the curved portions 12 and 13 are formed on the first substrate 10 by stamping, so that the molten metal can be well aggregated while flowing along the direction of gravity during welding.

[0039] More specifically, the first substrate 10 is disposed perpendicularly to the direction of gravity. In the present case, the first substrate 10 is divided from the bottom side into: a first flat portion 11, curved portions 12 and 13, and a second flat portion 14. In addition, the first curved portion 12 and the second curved portion 13 have different curvatures from each other.

[0040] Therefore, the first substrate 10 includes, starting from the bottom side: a first flat portion 11, a first curved portion 12, a second curved portion 13, and a second flat portion 14.

[0041] Meanwhile, the curved portions 12 and 13 formed in the first substrate 10 include: a first curved portion 12 that extends from the first flat portion 11 while bending with a first curvature R1; and a second curved portion 13 that extends from the first curved portion 12 while bending with a second curvature R2 and is connected to the second flat portion 14.

[0042] In the current configuration, the first bend 12 bends to protrude toward the second substrate 20, and the second bend 13 bends to recess away from the second substrate 20. Thus, the first bend 12 and the second bend 13 are connected to each other, for example, in an approximately “S” shape.

[0043] Furthermore, in the first substrate 10, due to the formation of the first curved portion 12 and the second curved portion 13, the first flat portion 11 and the second flat portion 14 are formed parallel to each other and spaced apart from each other by an offset (u). Therefore, the first flat portion 11 and the second flat portion 14 extend through the first curved portion 12 and the second curved portion 13 interposed therebetween.

[0044] Meanwhile, the second substrate 20 is disposed in a direction perpendicular to its direction of gravity. Therefore, the second substrate 20 is in contact with the first substrate 10 in its vertical direction.

[0045] In the current situation, the end of the second substrate 20 is bent downwards according to the direction of gravity to form a bent portion 22 and a vertical portion 23. Here, the second substrate 20 is bent into approximately... The shape is such that the vertical portion 23 is formed parallel to the first substrate 10.

[0046] Meanwhile, in various exemplary embodiments of the present invention, the first flat portion 11 and the second flat portion 14 of the first substrate 10 are formed parallel to each other, and the first flat portion 11 of the first substrate 10 and the vertical portion 23 of the second substrate 20 are formed parallel to each other. This does not mean that they are completely parallel to each other, but can mean that the first flat portion 11, the second flat portion 14 and the vertical portion 23 are formed relatively parallel to each other, although they are not completely parallel to each other.

[0047] Therefore, when the vertical portion 23 of the second substrate 20 merges with the first flat portion 11 of the first substrate 10, a welding area is formed above it, surrounded by the first curved portion 12 and the second curved portion 13 of the first substrate 10 and the bent portion 22 of the second substrate 20.

[0048] The weld bead 30 is formed by the molten metal generated when the first substrate 10 and the second substrate 20 are welded together. In the present case, the shape of the weld bead 30 is determined according to the shape of the welding area surrounded by the first bend 12 and the second bend 13 of the first substrate 10 and the bend 22 of the second substrate 20.

[0049] Meanwhile, in various exemplary embodiments of the present invention, in order to increase the weld toe angle θc formed by the weld bead 30, the relationship between the offset u and the thickness t of the first substrate is limited to the following relationship 1.

[0050]

Relationship 1

[0051] u≥0.3×t

[0052] That is, the offset u is preferably maintained at least 0.3 times the thickness t of the first substrate 10 on which the bends 12 and 13 are formed. If the offset u is less than 0.3 times the thickness t of the first substrate 10, the first substrate 10 will be almost straight and the weld toe angle θc will not be formed as desired.

[0053] Furthermore, the first curvature R1 of the first curved portion 12 and the second curvature R2 of the second curved portion 13 are respectively limited to the thickness t of the first substrate 10 according to the following relationships 2 and 3.

[0054]

Relationship 2

[0055] R1≥2×t

[0056]

Relationship 3

[0057] R2≥t

[0058] By limiting the first curvature R1 of the first bent portion 12 and the second curvature R2 of the second bent portion 13 as described above, the following effect can be achieved: during welding, molten metal can be well concentrated in the welding area surrounded by the first bent portion 12 and the second bent portion 13 of the first substrate 10 and the bent portion 22 of the second substrate 20.

[0059] The invention will now be described by way of comparative examples and illustrations.

[0060] The comparative example is Figure 1 The result shown is a typical T-shaped flat weld, while the example is... Figure 3 The results of T-welding according to various exemplary embodiments of the present invention are shown.

[0061] After undergoing a single-part durability test, cross-sections of the welded products according to the comparative example and the example welded products were photographed. Figure 5A and Figure 5B The results are shown in the figure.

[0062] Figure 5A and Figure 5B These are photographs of the cross-sections of welded products, based on comparative and example examples, after undergoing individual part durability tests.

[0063] from Figure 5A and Figure 5B It can be seen that the weld toe angle of the weld in the comparative example is 115°, while the weld toe angle of the weld in the example is 150°.

[0064] In addition, the weld bead in the comparative example is formed with a weld leg length of 28 mm, while the weld bead in the example is formed with a weld leg length of 40 mm.

[0065] In addition, for stress comparison, the stress distribution in the weld area of ​​the welded product was analyzed according to the comparative example and the example when a unit load was applied to the weld area of ​​the welded product. Figure 6A and Figure 6B The results are shown in the figure.

[0066] Here, the maximum stress was compared when the first flat portion of the first substrate was fixed while the same load was applied to each of the second flat portion of the first substrate and the main body portion of the second substrate. When the comparative example, representing a general T-welded structure, was set to 100%, it was confirmed that the welded structure according to various exemplary embodiments of the present invention was at 55% of the level compared to the comparative example. Therefore, it was confirmed that the stress concentration in the weld bead was reduced in the example compared to the comparative example.

[0067] Meanwhile, based on the durability test of a single part, the lifespan in the comparative example was 261,000 cycles, while the lifespan in the example increased to 392,000 cycles.

[0068] Here, before the actual vehicle evaluation steps of manufacturing and evaluating the whole vehicle, individual part durability tests are performed by manufacturing only the part to be inspected and some of the surrounding components that make up the vehicle.

[0069] Clearly, the cost and time required to manufacture an entire vehicle for durability assessment is enormous. Therefore, it is common practice to manufacture and assess only the parts to be inspected and closely related components to reduce costs and time. Based on the results confirmed in the individual part durability testing steps, the actual vehicle test results can also be predicted. Individual part durability testing is a method widely used not only in this field but also in general manufacturing.

[0070] According to an exemplary embodiment of the present invention, the bend is formed in the welding area of ​​the first substrate before welding. Therefore, when the molten metal flows downward under the action of gravity during welding, the shape of the bend allows the molten metal to be effectively concentrated, thereby facilitating the stable introduction of the molten metal into the root. Furthermore, the weld toe angle and weld leg length can be increased, thereby reducing stress concentration in the welding area.

[0071] Therefore, it is expected to improve the weldability and durability of the product, thereby improving the product's quality and marketability.

[0072] For ease of description and precise definition in the appended claims, the terms “upper,” “lower,” “internal,” “external,” “up,” “lower,” “upward,” “downward,” “front,” “rear,” “rearward,” “internal,” “external,” “inward,” “outward,” “internal,” “external,” “inner side,” “outer side,” “forward,” and “backward,” etc., are used to describe features in the positions shown in the accompanying drawings with reference to the features of the exemplary embodiments. It should also be understood that the term “connection” or its derivatives refer to both direct and indirect connections.

[0073] For purposes of illustration and description, the foregoing description of specific exemplary embodiments of the invention has been provided. This description is not intended to be exhaustive or to limit the invention to the exact forms disclosed, and various modifications and variations are apparent from the foregoing teachings. Exemplary embodiments were chosen and described to explain the specific principles of the invention and its practical application, thereby enabling others skilled in the art to implement and utilize various exemplary embodiments of the invention and their various alternatives and variations. The scope of the invention is intended to be defined by the appended claims and their equivalents.

Claims

1. A welding structure for a T-type welded joint, wherein, The second substrate is T-welded to the first substrate, the welding structure comprising: The first substrate includes a first flat portion, a second flat portion, and a curved portion formed between the first flat portion and the second flat portion; The second substrate includes a main body and a bent portion, wherein the bent portion is formed at an end of the main body such that the bent portion is configured as a curved portion facing the first substrate; and The weld bead is disposed between the bent portion of the first substrate and the bent portion of the second substrate. The first flat portion and the second flat portion are formed parallel to each other while being spaced apart by the curved portion between them. The first substrate is arranged along the direction of gravity. The second substrate is disposed in a direction perpendicular to the direction of gravity. In this embodiment, the bent portion of the second substrate bends downward along the direction of gravity. The second substrate has a vertical portion that extends from the end of the bent portion and is parallel to the first substrate. Wherein, the first flat portion of the first substrate merges with the vertical portion of the second substrate. The second flat portion extends above the first flat portion via the curved portion located between the first flat portion and the second flat portion. The curved portion formed in the first substrate includes: The first curved portion extends from the first flat portion while bending with a first curvature R1; and The second curved portion extends from the first curved portion while bending at a second curvature R2 and connects to the second flat portion. Wherein, the first bent portion is bent to bulge toward the second substrate, and The second bent portion is bent in a way that it is recessed away from the second substrate.

2. The welded structure according to claim 1, wherein, The bent portion of the second substrate is bent downward relative to the main body portion.

3. The welded structure according to claim 1, in, The first flat portion and the second flat portion are formed parallel to each other while being spaced apart from each other by a predetermined offset u.

4. The welded structure according to claim 3, wherein, The predetermined offset u and the thickness t of the first substrate satisfy the following relationship: Relation 1 u≥0.3×t.

5. The welded structure according to claim 1, wherein, The first curvature R1 of the first curved portion and the second curvature R2 of the second curved portion satisfy the following relationships 2 and 3 with respect to the thickness t of the first substrate, respectively: Relation 2 R1≥2×t; Relation 3 R²≥t.

6. The welded structure according to claim 1, in, The first curved portion bends from the first flat portion to bulge toward the second substrate, and The second bent portion is bent from the first bent portion and recessed away from the second substrate.

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