Joining structure and joining method for vehicle components

Abstract

To provide a joining structure and a joining method for a vehicle member that are able to prevent occurrence of a crack starting from a weld portion of a ridge line portion.SOLUTION: A frame member 10 comprises a cut portion 18 and a weld portion 16B, and the cut portion 18 is formed in a frame member 14 and a cut is made along a ridge line 14A so as to expose a ridge line 12A. Further, at the weld portion 16B, the frame member 14 is fillet-welded to a frame member 12 along the cut portion 18 with the ridge line 12A therebetween. Thus, the weld portion 16B is not provided on the ridge line 12A. Since the rigidity of the ridge line portion is higher than that of a periphery and a shared load is also large, not providing the weld portion 16B on the ridge line 12A makes it possible to prevent occurrence of a crack starting from the ridge line portion.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present invention relates to a joining structure and a joining method for vehicle members.

Background Art

[0002] Patent Document 1 below discloses a technique for welding a member having a ridge line and a flat plate member. In this prior art, in the welded portion, a reinforcing bead extends from the fillet bead at the position of the ridge line, thereby suppressing the occurrence of cracks due to fatigue of the welded structural members joined to each other.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above prior art, a member having a ridge line and a flat plate member are welded. When welding members having ridge lines to each other, the rigidity at the ridge line portion is higher than that of the surroundings, so the shared load becomes large at the welded portion of the ridge line portion, and cracks may occur in the welded portion starting from the ridge line portion.

[0005] Therefore, an object of the present invention is to obtain a joining structure and a joining method for vehicle members capable of suppressing the occurrence of cracks starting from the welded portion of the ridge line portion.

Means for Solving the Problems

[0006] To achieve the above objective, the vehicle member joining structure described in claim 1 comprises: a first vehicle member having a first ridge line along the extending direction; a second vehicle member having a second ridge line overlapping the first ridge line along the extending direction, and provided with a first welded portion that overlaps with the first vehicle member from the outside and is fillet welded; a notch formed in the second vehicle member and cut along the second ridge line so that the first ridge line is exposed; and a second welded portion in which the second vehicle member is fillet welded to the first vehicle member along the notch line with the first ridge line in between.

[0007] The vehicle member joining structure according to claim 1 comprises a first vehicle member and a second vehicle member. The first vehicle member has a first ridge line formed along the extending direction of the first vehicle member. The second vehicle member has a second ridge line that overlaps with the first ridge line formed along the extending direction of the second vehicle member, and the second vehicle member is overlapped and fillet welded to the first vehicle member from the outside (first weld).

[0008] In this invention, the vehicle member is configured to include a notched portion and a second welded portion. The notched portion is formed in the second vehicle member and is cut along the second ridge line so that the first ridge line is exposed. The second welded portion is where the second vehicle member is fillet welded to the first vehicle member along the notched portion with the first ridge line in between. In other words, the first welded portion is the portion where the first vehicle member and the second vehicle member are fillet welded in the portion excluding the notched portion, and the second welded portion is the portion where the first vehicle member and the second vehicle member are fillet welded in the notched portion. In this invention, the vehicle member is integrated by the first welded portion and the second welded portion.

[0009] Furthermore, in this invention, a second weld is provided along the cut portion with the first ridge in between. That is, the second weld is not provided on the first ridge. Because the rigidity of the ridge portion is higher than the surrounding area and the load it bears is also larger, by not providing a second weld on the first ridge, this invention makes it possible to prevent the occurrence of cracks originating from the ridge portion. On the other hand, the deficiency in joint strength due to the absence of a second weld on the first ridge can be compensated for by increasing the weld length through fillet welding along the cut portion.

[0010] The vehicle member joining structure according to claim 2 is the vehicle member joining structure according to claim 1, wherein the second welded portion is configured to include a pair of opposing weld lines.

[0011] In the vehicle member joining structure described in claim 2, the second welded portion is configured to include a pair of opposing weld lines, so that the weld lines can be parallel to lines along the direction in which stress acts at the root portion of the ridge line with a large load, thereby strengthening the fatigue strength in the direction in which stress acts.

[0012] The vehicle member joining structure according to claim 3 is the vehicle member joining structure according to claim 2, wherein the length of the weld line is set to be longer than the dimension measured along the outer shape of the first vehicle member, straddling the first ridge line at the entrance of the cut portion.

[0013] In the vehicle member joining structure described in claim 3, the length of the weld line is set to be longer than the dimension measured along the outer shape of the first vehicle member, straddling the first ridge line at the entrance of the cut portion. As a comparative example, this makes it possible to make the weld length longer than the weld that is welded across the ridge line without a cut portion. In this way, the present invention makes it possible to compensate for the deficiency in joining strength due to the absence of a second weld on the first ridge line, and also makes it possible to strengthen the fatigue strength by making the weld length longer.

[0014] The vehicle component joining structure according to claim 4 is the vehicle component joining structure according to claim 1, wherein the first vehicle component and the second vehicle component are made of an aluminum alloy.

[0015] In the vehicle component joining structure described in claim 4, the first vehicle component and the second vehicle component are formed from an aluminum alloy. In aluminum arc welding, there is a large difference in strength between the base material and the bead, and cracks are more likely to occur in the root portion than with iron. However, according to the present invention, it is possible to effectively prevent cracks in the root portion even with aluminum arc welding.

[0016] The method for joining vehicle members according to claim 5 is a method for joining vehicle members according to any one of claims 1 to 4, comprising: a notch forming step of forming a notch along the second ridge line with respect to the second ridge line between them in the second vehicle member; a member overlapping step of overlapping the second vehicle member on the outside of the first vehicle member such that the second ridge line overlaps with the first ridge line; and a welding step of fillet welding at the overlapping portion of the first vehicle member and the second vehicle member.

[0017] The method for joining vehicle components according to claim 5 includes a notch forming step, a component overlapping step, and a welding step. In the notch forming step, a notch is formed in the second vehicle component along the second ridge line with the second ridge line in between. Next, in the component overlapping step, the second vehicle component is overlapped on the outside of the first vehicle component such that the second ridge line overlaps the first ridge line. Then, in the welding step, fillet welding is performed at the overlapping portion of the first vehicle component and the second vehicle component. [Effects of the Invention]

[0018] As described above, the joining structure and joining method for vehicle components according to the present invention can suppress the occurrence of cracks originating from the welded portion of the ridge. [Brief explanation of the drawing]

[0019] [Figure 1A] It is an enlarged perspective view of a main part showing a welded part of a skeleton member provided with a joining structure of vehicle members according to the present embodiment. [Figure 1B] It is a plan view of FIG. 1A. [Figure 1C] It is a right side view of FIG. 1A. [Figure 2] It is a side view showing a state where a load is input to a free end of a skeleton member provided with a joining structure of vehicle members according to the present embodiment. [Figure 3A] It is a diagram showing a stress distribution analyzed by an analysis solver acting on a skeleton member whose ridge line forms an angle of 90 degrees. [Figure 3B] It is a developed view centered on the ridge line of a skeleton member as a comparative example corresponding to the horizontal axis in FIG. 3A. [Figure 3C] It is a developed view centered on the ridge line of a skeleton member as the present embodiment corresponding to the horizontal axis in FIG. 3A. [Figure 4A] It is a diagram showing a stress distribution analyzed by an analysis solver acting on a skeleton member whose ridge line forms an angle of 130 degrees. [Figure 4B] It is a developed view centered on the ridge line of a skeleton member as a comparative example corresponding to the horizontal axis in FIG. 4A. [Figure 4C] It is a developed view centered on the ridge line of a skeleton member as the present embodiment corresponding to the horizontal axis in FIG. 4A. [Figure 5] It is a partially exploded perspective view showing a modification of the joining structure of vehicle members according to the present embodiment. [Figure 6A] It is an enlarged perspective view of a main part corresponding to FIG. 1A showing a welded part of a skeleton member as a comparative example. [Figure 6B] It is a cross-sectional view when cut along the line A-A of FIG. 6A. [Figure 6C] It is a right side view of FIG. 6A.

Mode for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

[0021] (Configuration of the joining structure for vehicle components) First, the configuration of the joining structure for vehicle components according to this embodiment will be described.

[0022] As shown in Figures 1A to 1C, the vehicle frame member 10 to which the vehicle member joining structure according to this embodiment is applied comprises a frame member (first vehicle member) 12 and a frame member (second vehicle member) 14.

[0023] The skeletal members 12 and 14 are each formed from, for example, an aluminum alloy. The skeletal member 14 is formed to have an outer diameter that is approximately the thickness of the skeletal member 12, and the skeletal member 12 is inserted into the skeletal member 14, so that the skeletal member 14 overlaps the skeletal member 12 from the outside.

[0024] In this embodiment, the skeletal members 12 and 14 are formed in a rectangular tubular shape and are provided with, for example, four ridges (first ridge) 12A and four ridges (second ridge) 14A, respectively. With the skeletal member 12 inserted into the skeletal member 14, the ridges 12A of the skeletal member 12 and the ridges 14A of the skeletal member 14 overlap vertically, and in this state, the skeletal member 12 and the skeletal member 14 are fillet welded (overlap fillet weld) including the end face 14C of the skeletal member 14 (welded joint 16).

[0025] Here, as shown in Figure 2, when a load F is applied to the free end of a skeletal member 10, which is formed by fillet welding of skeletal members 12 and 14, while it is cantilevered, a bending stress acts on the skeletal member 10 at the welded joint 16.

[0026] At this time, the bending stress σ in the welded joint 16 is σ∝M / bh 2 It is represented by h 2It is inversely proportional to . Here, M is the bending moment, and b is the length dimension along the weld perpendicular to the direction in which the stress acts on the cross-section of the skeletal member 10. In the comparative example, h is the throat thickness h1 shown in Figure 6B. When stress acts on the welded joint 104, a crack may occur at the root of the welded joint 104 (so-called root crack). For this reason, the throat thickness h1 is generally set to approximately 0.7 times the base plate thickness t1.

[0027] On the other hand, as shown in Figures 1A and 1B, in this embodiment, h is defined as the weld length L. In welding, depending on the conditions, for example, the penetration of the weld may be insufficient in the section of approximately 10 mm at the beginning of the weld and approximately 5 mm at the end of the weld compared to the middle of the weld. In such cases of insufficient penetration, a crack may occur in the welded section 16 when stress is applied (so-called end-end crack). For this reason, the length of the weld line 16B1 (weld length L), which will be described later, is set in this embodiment taking this into consideration.

[0028] As shown in Figure 2, considering that bending stress acts on the skeletal member 10, in this embodiment, as shown in Figures 1A to 1C, notches 18 are formed in the skeletal member 14 along at least two ridges 14A on the upper wall portion 14B. The notches 18 are cut out in an elongated shape with the ridges 14A in between. Therefore, when the skeletal member 12 is inserted into the skeletal member 14, a part of the ridge 12A of the skeletal member 12 is exposed through the notches 18.

[0029] The notch 18 is composed of a pair of straight sections 18A formed inward from the entrance of the notch 18 and arranged opposite to each other, and a circular hole 18B provided at the back of the notch 18 that connects the pair of straight sections 18A in an arc shape. The length of the straight sections 18A is set to be longer than the dimension L1 measured along the outer shape of the skeletal member 100, crossing the ridge line 100A of the skeletal member 100, when the notch is not provided in the skeletal member 102, as shown in Figures 6A and 6C.

[0030] In this embodiment, as shown in Figures 1A to 1C, a fillet weld is performed along the end face 14C of the skeletal member 14 with a notch 18 formed along two ridge lines 14A on the upper wall portion 14B of the skeletal member 14 (welded portion 16). The welded portion 16 consists of a welded portion (first welded portion) 16A and a welded portion (second welded portion) 16B, with the welded portion 16A being provided in the area excluding the notch 18, and the welded portion 16B being provided in the area of ​​the notch 18.

[0031] In this embodiment, the welded portion 16B is composed of a pair of weld lines 16B1. That is, fillet welding is performed in a pair of straight sections 18A that constitute the cut portion 18, and the weld lines 16B1 are divided by the circular hole portion 18B.

[0032] (Function and effect of the joining structure for vehicle components) Next, the operation and effects of the vehicle component joining structure according to this embodiment will be described.

[0033] In this embodiment, as shown in Figures 1A to 1C, a vehicle frame member 10 to which a vehicle component joining structure is applied includes a frame member 12 and a frame member 14. In this embodiment, the method for joining the vehicle components includes, for example, a notch formation step, a component overlapping step, and a welding step.

[0034] In the notch formation process, notches 18 are formed along the two ridges 14A between them on the upper wall portion 14B of the skeletal member 14. Next, in the member overlapping process, the skeletal member 12 is inserted into the skeletal member 14 such that the ridge 12A overlaps the ridge 14A from the outside. Then, in the welding process, fillet welding is performed on the overlapping portion of the skeletal member 12 and the skeletal member 14, including the end face 14C of the skeletal member 14 (welded portion 16).

[0035] Through the joining method described above, the skeletal member 14 is fillet-welded to the skeletal member 12 from the outside via the welded joint 16, and is integrated with the skeletal member 12 (skeletal member 10).

[0036] Specifically, in this embodiment, the skeletal member 10 is composed of a notch 18 and a welded portion 16B. The notch 18 is formed in the skeletal member 14 and is cut along the ridge line 14A so that the ridge line 12A is exposed. The welded portion 16B is formed when the skeletal member 14 is fillet welded to the skeletal member 12 along the notch 18 with the ridge line 12A in between.

[0037] Here, the welded portion 16 is composed of a welded portion 16A in which the skeletal member 12 and the skeletal member 14 are fillet welded in the portion excluding the cut portion 18, and a welded portion 16B in which the skeletal member 12 and the skeletal member 14 are fillet welded in the portion at the cut portion 18. In this embodiment, the skeletal member 12 and the skeletal member 14 are integrated by the welded portion 16A and the welded portion 16B.

[0038] As mentioned above, the welded portion 16B is provided along the cut portion 18 with the ridge line 12A in between; therefore, in this embodiment, the welded portion 16B is not provided on the ridge line 12A. Since the rigidity of the ridge portion is higher than the surrounding area and the load-bearing portion is also larger, by not providing the welded portion 16B on the ridge line 12A, it is possible to prevent the occurrence of cracks originating from the ridge portion in this embodiment.

[0039] Furthermore, in this embodiment, since the welded portion 16B is configured to include a pair of opposing weld lines 16B1, the weld lines 16B1 can be made parallel to the line along the direction in which stress acts at the root portion of the ridge where the load is large, thereby strengthening the fatigue strength in the direction in which stress acts.

[0040] Incidentally, generally speaking, when comparing the strength of crack modes in a weld, such as root cracks (cracks occurring at the root of the weld), end cracks (cracks occurring at the start and end of the weld), and toe cracks (cracks occurring at the surface where the base metal and the weld meet), the order is root crack < end crack < toe crack. In other words, root cracks have the lowest strength. Therefore, improving the strength of the weld can be effectively improved by improving the strength of the root.

[0041] In this embodiment, as shown in Figures 1A and 1B, the welding length L of the weld line 16B1 is set to be longer than the dimension L1 measured along the outer shape of the skeletal member 100 in the welded portion 104 that is welded across the ridge line 100A without providing a notch, as shown in Figures 6A and 6C.

[0042] As a result, in this embodiment, as shown in Figure 1A, the deficiency in joint strength due to the absence of a welded joint 16B on the ridge line 12A can be compensated for by making the weld length L longer than the dimension L1 (see Figure 6A), and the fatigue strength can be strengthened by making the weld length L longer than in the comparative example.

[0043] Here, Figures 3A and 4A show the analysis results obtained by an analytical solver, which represent the stress distribution acting on the skeletal members 10 and 105. The solid line shows the stress distribution of skeletal member 10 in this embodiment, while the dashed line shows the stress distribution of skeletal member 105 as a comparative example.

[0044] Figure 3B is an unfolded view centered on edge 102A of the skeletal member 105 as a comparative example shown in Figure 3A, and Figure 3C is an unfolded view centered on edge 14A of the skeletal member 10 as this embodiment shown in Figure 3A, with edges 102A and 14A each forming an angle of approximately 90 degrees.

[0045] Furthermore, Figure 4B is an unfolded view centered on edge 102A of the skeletal member 105 as a comparative example shown in Figure 4A, and Figure 4C is an unfolded view centered on edge 14A of the skeletal member 10 as this embodiment shown in Figure 4A, with edges 102A and 14A each forming an angle of approximately 130 degrees.

[0046] As shown in Figures 3A and 4A, in the comparative example, the bending stress acting in the peripheral area including the ridge line 102A is maximum, but in this embodiment, the bending stress is reduced in the peripheral area including the ridge line 14A (indicated by arrows). Thus, in this embodiment, since the bending stress in the peripheral area including the ridge line 14A is reduced in the skeletal member 10 shown in Figures 1A to 1C, it is possible to prevent the occurrence of cracks originating from the ridge line portion where the load shared by the welded portion 16 is large.

[0047] Furthermore, in this embodiment, the skeletal members 12 and 14 are formed from an aluminum alloy. In aluminum arc welding, the strength difference between the base material and the bead is large, and cracks are more likely to occur in the root area than with iron. However, according to this embodiment, it is possible to effectively prevent cracks in the root area even with aluminum arc welding. However, the skeletal members 12 and 14 do not necessarily have to be aluminum alloys and may be formed from other metals.

[0048] Furthermore, in the above embodiment, the skeletal members 12 and 14, each having a rectangular tubular shape, are used as the skeletal members 10, and the skeletal member 12 as the first vehicle member and the skeletal member 14 as the second vehicle member are directly fillet welded together. However, the embodiment is not limited to this configuration.

[0049] For example, as a simple modification, as shown in Figure 5, the vehicle frame member 50 may consist of first vehicle frame members 52 and 54, each having a rectangular tubular shape, and second vehicle frame members 56 and 58, which are plate-shaped members that abut the outer surfaces of the frame members 52 and 54 and have a U-shaped cross-section when cut along the width direction.

[0050] The plate-like members 56 and 58 each have notches 60 and 62 formed between their ridges 56A and 58A, respectively. With the skeletal members 52 and 54 in contact, the plate-like member 56 is welded to the skeletal members 52 and 54, including the notches 60 (excluding the arc portion), with the upper ridges (first ridges) 52A and 54A of the skeletal members 52 and 54 overlapping with the ridge (second ridge) 56A of the plate-like member 56. Furthermore, the plate-like member 58 is welded to the skeletal members 52 and 54, including the notches 62 (excluding the arc portion), with the lower ridges 52A and 54A of the skeletal members 52 and 54 overlapping with the ridge (second ridge) 58A of the plate-like member 58.

[0051] As a comparative example, although not shown in the figures, when butt welding skeletal members 52 and 54, if the base plate thickness and throat thickness cannot be sufficiently secured, the joint strength of the skeletal members 52 and 54 will be reduced. However, according to this embodiment, by fillet welding plate-shaped members 56 and 58 as separate members, it is possible to improve the joint strength of the skeletal members 52 and 54.

[0052] Examples of the skeletal member 10 include the joint between the crash box and the front (rear) side member. In addition, in the case of the rear floor side member, side member, suspension member, cross member, etc., these members may be configured in which multiple skeletal members are integrated by welding. Furthermore, in the case of a vehicle frame that is divided into left and right sides in the vehicle width direction, particularly modified versions can be applied when welding the right skeletal member and the left skeletal member. Moreover, if it is necessary to replace either the right skeletal member or the left skeletal member, this embodiment may be applied.

[0053] Furthermore, although the above embodiments described examples in which the skeletal members 12 and 14 are formed in a rectangular tubular shape, the present invention is not limited to the shape of the vehicle members, as it only requires a configuration in which two vehicle members are fillet welded together.

[0054] Although one embodiment of the present invention has been described above, the present invention is not limited to these embodiments, and various modifications may be used in appropriate combinations with one embodiment, and of course, the invention can be implemented in various forms without departing from the spirit of the present invention.

[0055] <Note> Furthermore, the following configurations may be combined as appropriate to form the vehicle understructure according to the present invention.

[0056] (Composition 1) The vehicle component joining structure comprises: a first vehicle component having a first ridge line provided along the extending direction; a second vehicle component having a second ridge line provided along the extending direction and overlapping the first ridge line, overlapping the first vehicle component from the outside and fillet-welded via a first weld; a notch formed in the second vehicle component and cut along the second ridge line so as to expose the first ridge line; and a second weld where the second vehicle component is fillet-welded to the first vehicle component along the notch line with the first ridge line in between.

[0057] (Configuration 2) The second welded portion is comprised of a pair of opposing weld lines.

[0058] (Composition 3) The length of the weld line is set to be longer than the separation distance measured along the outer shape of the first vehicle member, straddling the first ridge line at the entrance of the cut portion.

[0059] (Composition 4) The first vehicle component and the second vehicle component are made of an aluminum alloy. [Explanation of Symbols]

[0060] 10. Structural components (vehicle components) 12. Structural members (members for the first vehicle) 12A Ridge (First Ridge) 14. Structural components (components for the second vehicle) 14A Ridge (Second Ridge) 16 Welded section 16A Welded section (First welded section) 16B1 Welding Line 16B Weld (Second Weld) 18 Cut section 50. Structural components (vehicle components) 52. Structural members (members for the first vehicle) 52A Ridge (First Ridge) 54. Structural members (members for the first vehicle) 54A Ridge (First Ridge) 56 Plate-shaped member (member for the second vehicle) 56A Ridge (Second Ridge) 58 Plate-shaped member (member for the second vehicle) 58A Ridge (Second Ridge) 60 Cutting section 62 Cut section L Weld length (length of the weld line)

Claims

1. A first vehicle member having a first ridge line along the direction of extension, A second vehicle member having a second ridge that overlaps with the first ridge along the extending direction, and a first welded portion that overlaps with the first vehicle member from the outside and is fillet welded, Equipped with, A notch formed in the second vehicle member, cut along the second ridge so that the first ridge is exposed, A second welded portion is formed by fillet welding the second vehicle member to the first vehicle member along the cut portion with respect to the first ridge line, A joining structure for vehicle components comprising the above.

2. The vehicle member joining structure according to claim 1, wherein the second welded portion includes a pair of opposing weld lines.

3. The vehicle member joining structure according to claim 2, wherein the length of the welding line is set to be longer than the dimension measured along the outer shape of the first vehicle member, straddling the first ridge line at the entrance of the cut portion.

4. The vehicle member joining structure according to claim 1, wherein the first vehicle member and the second vehicle member are formed of an aluminum alloy.

5. A joining method using a vehicle member according to any one of claims 1 to 4, In the second vehicle member, a notch forming step is performed to form a notch along the second ridge between the second ridges, A component overlapping step in which the second vehicle component is placed on the outside of the first vehicle component such that the second ridge line overlaps the first ridge line, A welding process in which fillet welding is performed at the overlapping portion of the first vehicle member and the second vehicle member, A method for joining vehicle components that include [a specific component].

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