Joining structure and joining method for vehicle member

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 technology]

[0002] The following Patent Document 1 discloses a technique for welding a member having a ridgeline to a flat member. In this prior art, a reinforcing bead extends from a fillet bead at the position of the ridgeline in the welded portion, thereby suppressing the occurrence of cracks due to fatigue in the welded structural members joined together. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. WO2014 / 084317 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above prior art, a component having a ridge line is welded to a flat component, and when components having ridge lines are welded together, the rigidity at the ridge line is higher than the surrounding area, so the load shared at the weld at the ridge line becomes large, and cracks may occur in the weld starting from the ridge line.

[0005] Therefore, an object of the present invention is to provide a joining structure and joining method for vehicle components that can suppress the occurrence of cracks originating from welds in ridge lines. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the joining structure for vehicle components described in claim 1 comprises a first vehicle component having a first ridge line along an extension direction, and a second vehicle component having a second ridge line along an extension direction overlapping the first ridge line and provided with a first weld portion overlapping and fillet welded from the outside to the first vehicle component, and is configured to include a cut-out portion formed in the second vehicle component and cut along the second ridge line so that the first ridge line is exposed, and a second weld portion in which the second vehicle component is fillet welded to the first vehicle component along the cut-out portion with the first ridge line between them.

[0007] The joining structure for vehicle components according to claim 1 includes a first vehicle component and a second vehicle component. The first vehicle component has a first ridgeline formed along the extension direction of the first vehicle component. The second vehicle component has a second ridgeline overlapping the first ridgeline formed along the extension direction of the second vehicle component, and the second vehicle component is overlapped from the outside of the first vehicle component and fillet welded (first welded portion).

[0008] Here, in the present invention, the second vehicle component is configured to include a cut portion and a second weld portion. The cut portion is formed in the second vehicle component, and is cut along the second ridge line so that the first ridge line is exposed. In addition, the second weld portion is formed by fillet welding the second vehicle component to the first vehicle component along the cut portion with the first ridge line in between. In other words, the first weld portion is a portion where the first vehicle component and the second vehicle component are fillet welded at a portion other than the cut portion, and the second weld portion is a portion where the first vehicle component and the second vehicle component are fillet welded at the cut portion. In the present invention, the vehicle components are integrated by the first weld portion and the second weld portion.

[0009] In addition, in the present invention, a second weld is provided along the cutout with the first ridgeline in between. That is, the second weld is not provided on the first ridgeline. Since the rigidity of the ridgeline portion is higher than the surrounding area and the load sharing is also large, by not providing the second weld on the first ridgeline, the present invention makes it possible to prevent the occurrence of cracks originating from the ridgeline portion. On the other hand, the insufficient joint strength caused by the absence of the second weld on the first ridgeline can be compensated for by lengthening the weld length by fillet welding along the cutout.

[0010] A joining structure for a vehicle member according to a second aspect of the present invention is the joining structure for a vehicle member according to the first aspect, wherein the second welded portion includes a pair of weld lines provided opposite each other.

[0011] In the joining structure of a vehicle component described in claim 2, the second weld portion is configured to include a pair of welding lines arranged opposite each other, so that the welding lines can be parallel to a line along the direction in which stress acts at the root portion of the ridge line where the shared load is large, making it possible to strengthen the fatigue strength in the direction in which stress acts.

[0012] The joining structure for vehicle components described in claim 3 is the joining structure for vehicle components described in 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 component, straddling the first ridge line at the entrance of the notch.

[0013] In the joining structure for vehicle components 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 component across the first ridgeline at the entrance of the notch, making it possible to make the weld length longer than a weld that is welded across the ridgeline without providing a notch, as a comparative example. This makes it possible in the present invention to compensate for the shortfall in joining strength caused by not providing the second weld at the first ridgeline, and also makes it possible to increase fatigue strength by making the weld length longer.

[0014] A joining structure for vehicle members according to a fourth aspect of the present invention is the joining structure for vehicle members according to the first aspect, wherein the first vehicle member and the second vehicle member are formed of an aluminum alloy.

[0015] In the joining structure of vehicle members according to claim 4, the first vehicle member and the second vehicle member are formed of 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 at the root than in iron, but according to the present invention, cracks can be effectively prevented at the root even in aluminum arc welding.

[0016] The method of joining vehicle components described in claim 5 is a joining method using vehicle components described in any one of claims 1 to 4, and includes a notch forming process of forming a notch portion along the second ridge line in the second vehicle component, a component overlapping process of overlapping the second vehicle component on the outside of the first vehicle component so that the second ridge line overlaps the first ridge line, and a welding process of performing a fillet weld at the portion where the first vehicle component and the second vehicle component overlap.

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

[0018] As described above, according to the joining structure and joining method for vehicle components of the present invention, it is possible to suppress the occurrence of cracks originating from the welded portion of the ridge line portion. [Brief description of the drawings]

[0019] [Figure 1A] 2 is an enlarged perspective view of a main portion showing a welded portion of a frame member provided with a joining structure for a vehicle member according to the present embodiment; FIG. [Figure 1B] FIG. 1B is a plan view of FIG. 1A. [Figure 1C] FIG. 1B is a right side view of FIG. 1A. [Diagram 2] 1 is a side view showing a state in which a load is input to a free end of a frame member having a joint structure for a vehicle member according to an embodiment of the present invention. [Figure 3A] FIG. 13 is a diagram showing the stress distribution analyzed by an analytical solver acting on a skeleton member with a ridge angle of 90 degrees. [Figure 3B] 3B is a development view centered on the ridge line of a skeletal member serving as a comparative example corresponding to the horizontal axis in FIG. 3A. FIG. [Figure 3C] 3B is a development view of the ridge line of the skeletal member according to the present embodiment, which corresponds to the horizontal axis in FIG. 3A. FIG. [Figure 4A] FIG. 13 is a diagram showing the stress distribution analyzed by an analytical solver acting on a skeleton member with a ridge angle of 130 degrees. [Figure 4B] 4B is a development view centered on the ridge line of a skeletal member serving as a comparative example corresponding to the horizontal axis in FIG. 4A. FIG. [Figure 4C] 4B is a development view of the ridge line of the skeletal member according to the present embodiment, which corresponds to the horizontal axis in FIG. 4A. FIG. [Diagram 5] FIG. 11 is a partially exploded perspective view showing a modified example of the joining structure of vehicle members according to the embodiment; [Figure 6A] FIG. 1B is an enlarged perspective view of a main portion corresponding to FIG. 1A and showing a welded portion of a skeleton member as a comparative example. [Figure 6B] FIG. 6B is a cross-sectional view taken along line AA in FIG. 6A. [Figure 6C] FIG. 6B is a right side view of FIG. 6A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

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

[0022] As shown in Figures 1A to 1C, a vehicle skeleton member 10 to which the joining structure for vehicle components of this embodiment is applied includes a skeleton member (first vehicle component) 12 and a skeleton member (second vehicle component) 14.

[0023] The skeletal members 12 and 14 are each formed of, for example, an aluminum alloy. The skeletal member 14 is formed so that its outer shape is larger than that of the skeletal member 12 by approximately the plate thickness of the skeletal member 12. 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 tube shape, and are each provided with, for example, four ridges (first ridge) 12A and four ridges (second ridge) 14A. When the skeletal member 12 is inserted into the skeletal member 14, the ridges 12A of the skeletal member 12 and the ridges 14A of the skeletal member 14 overlap each other vertically, and in this state, the skeletal members 12 and 14, including the end face 14C of the skeletal member 14, are fillet welded (lap fillet welded) (weld portion 16).

[0025] Here, as shown in FIG. 2, in the skeletal member 10 in which the skeletal members 12, 14 are fillet welded, when a load F is input to the free end in a cantilevered state, a bending stress acts on the skeletal member 10 at the welded portion 16.

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

[0027] 1A and 1B, in this embodiment, h is the weld length L. In the case of welding, although it depends on the conditions, for example, it is assumed that the weld penetration is insufficient in a section of about 10 mm at the start of welding and about 5 mm at the end of welding compared to the middle of welding. In this way, when the penetration is insufficient, cracks may occur in the welded portion 16 when stress acts on it (so-called end cracks). For this reason, the length (weld length L) of the weld line 16B1 described later is set in this embodiment taking this into consideration.

[0028] As shown in Fig. 2, in consideration of the fact that bending stress acts on the skeletal member 10, in this embodiment, as shown in Figs. 1A to 1C, in the skeletal member 14, a cutout portion 18 is formed along at least two ridge lines 14A on the upper wall portion 14B. The cutout portion 18 is cut out in the shape of an elongated hole with the ridge lines 14A therebetween. Therefore, when the skeletal member 12 is inserted into the skeletal member 14, a part of the ridge line 12A of the skeletal member 12 is exposed through the cutout portion 18.

[0029] The cutout portion 18 is configured to include a pair of straight line portions 18A that are formed from the entrance portion of the cutout portion 18 toward the back and are arranged opposite each other, and a circular hole portion 18B that is provided at the back of the cutout portion 18 and connects the pair of straight line portions 18A in an arc shape. The length of the straight line portion 18A is set to be longer than a dimension L1 measured along the outer shape of the skeleton member 100 across the ridge line 100A of the skeleton member 100 when no cutout is provided in the skeleton member 102, as shown in Figures 6A and 6C.

[0030] 1A to 1C, in this embodiment, in a state where notches 18 are formed along two ridgelines 14A in an upper wall portion 14B of a skeleton member 14, fillet welding (weld portion 16) is performed along an end face 14C of the skeleton member 14. The weld portion 16 is configured to include a weld portion (first weld portion) 16A and a weld portion (second weld portion) 16B, where the weld portion 16A is provided in a portion other than the notch portion 18, and the weld portion 16B is provided in the portion of the notch portion 18.

[0031] In this embodiment, the welded portion 16B is formed by a pair of weld lines 16B1. That is, fillet welding is performed at a pair of straight portions 18A that form the cutout portion 18, and the weld lines 16B1 are divided by the circular hole portion 18B.

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

[0033] 1A to 1C, a vehicle frame member 10 to which a joining structure for vehicle members is applied includes a frame member 12 and a frame member 14. In this embodiment, the joining method for vehicle members includes, for example, a notch forming step, a member overlapping step, and a welding step.

[0034] In the notch forming process, notches 18 are formed along two ridge lines 14A in 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 so that the ridge line 12A overlaps the ridge line 14A from the outside. Then, in the welding process, fillet welding is performed including the end face 14C of the skeletal member 14 at the portion where the skeletal member 12 and the skeletal member 14 overlap (weld portion 16).

[0035] By the joining method described above, the skeletal member 14 is fillet welded to the skeletal member 12 via the welded portion 16 in a state where it overlaps the skeletal member 12 from the outside, and is integrated with the skeletal member 12 (skeletal member 10).

[0036] More specifically, in this embodiment, the skeletal member 10 is configured to include a cut portion 18 and a weld portion 16B, and the cut portion 18 is formed in the skeletal member 14 and cut along the ridge line 14A so as to expose the ridge line 12A. The weld portion 16B is formed by fillet welding the skeletal member 14 to the skeletal member 12 along the cut portion 18 with the ridge line 12A therebetween.

[0037] Here, the welded portion 16 is configured to include a welded portion 16A where the skeletal member 12 and the skeletal member 14 are fillet welded at a portion other than the notched portion 18, and a welded portion 16B where the skeletal member 12 and the skeletal member 14 are fillet welded at a portion at the notched 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 described above, since the welded portion 16B is provided along the cut portion 18 with the ridge line 12A therebetween, in this embodiment, the welded portion 16B is not provided at the ridge line 12A. Since the rigidity of the ridge line portion is higher than the surrounding area and the load sharing is also large, by not providing the welded portion 16B at the ridge line 12A, in this embodiment, it is possible to prevent the occurrence of cracks starting from the ridge line portion.

[0039] Furthermore, in this embodiment, since the weld portion 16B is configured to include a pair of welding lines 16B1 arranged opposite each other, the welding lines 16B1 can be made parallel to a line along the direction in which stress acts at the root portion of the ridge line which bears a large load, thereby making it possible to strengthen the fatigue strength in the direction in which stress acts.

[0040] Generally, when comparing the strength of crack modes in a weld, which are root cracks that occur at the base (root) of the weld, end cracks that occur at the start and end of the weld, and toe cracks that occur at the interface where the base material and the weld meet, the order is root crack < end crack < toe crack. In other words, root cracks have the lowest strength. For this reason, it is possible to effectively improve the strength of the weld by improving the strength of the root.

[0041] In this embodiment, as shown in Figures 1A and 1B, the weld 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 at the weld 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 FIG. 1A, the insufficient joint strength caused by not providing welded portion 16B at ridge line 12A can be compensated for by making weld length L longer than dimension L1 (see FIG. 6A), and by making weld length L longer than in the comparative example, it is possible to strengthen the fatigue strength.

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

[0044] FIG. 3B is an exploded view centered on ridge line 102A of skeletal member 105 as a comparative example shown in FIG. 3A, and FIG. 3C is an exploded view centered on ridge line 14A of skeletal member 10 as the present embodiment shown in FIG. 3A, with ridge lines 102A and 14A each forming an angle of approximately 90 degrees.

[0045] Moreover, Figure 4B is an expanded view centered on ridge line 102A of skeletal member 105 as a comparative example shown in Figure 4A, and Figure 4C is an expanded view centered on ridge line 14A of skeletal member 10 as the present embodiment shown in Figure 4A, with ridge lines 102A and 14A each forming an angle of approximately 130 degrees.

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

[0047] In this embodiment, the skeletal members 12 and 14 are made of an aluminum alloy. In aluminum arc welding, the strength difference between the base metal and the bead is large, and cracks are more likely to occur at the root than in iron, but according to this embodiment, cracks can be effectively prevented at the root even in aluminum arc welding. However, the skeletal members 12 and 14 do not necessarily have to be made of an aluminum alloy, and may be made of other metals.

[0048] In addition, in the above embodiment, the skeletal members 12 and 14 each having a rectangular cylindrical shape are used as the skeletal member 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, but this is not limited to this.

[0049] For example, briefly explaining a modified example, as shown in FIG. 5, a vehicle skeletal member 50 may be composed of skeletal members 52, 54 as first vehicle members each having a rectangular cylindrical shape, and plate-like members 56, 58 as second vehicle members each having a U-shaped cross-sectional shape when abutted against the outer surfaces of the skeletal members 52, 54 and cut along the width direction.

[0050] The plate-like members 56, 58 have cut-outs 60, 62 formed with the ridgelines 56A, 58A therebetween, and the plate-like member 56 is welded to the skeletal members 52, 54 including the cut-out 60 (excluding the arc portion) with the ridgelines (first ridgelines) 52A, 54A on the upper sides of the skeletal members 52, 54 overlapping with the ridgeline (second ridgeline) 56A of the plate-like member 56 in a state where the skeletal members 52 and 54 are in contact with each other. Furthermore, the plate-like member 58 is welded to the skeletal members 52, 54 including the cut-out 62 (excluding the arc portion) with the ridgelines 52A, 54A on the lower sides of the skeletal members 52, 54 overlapping with the ridgeline (second ridgeline) 58A of the plate-like member 58.

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

[0052] In addition, the skeleton member 10 may be, for example, a joint between a crash box and a front (rear) side member. In addition, in the case of a rear floor side member, a side member, a suspension member, a cross member, etc., these members may be configured such that a plurality of skeleton members are integrated by welding. Furthermore, in the case of a vehicle skeleton configured to be divided into left and right in the vehicle width direction, the modified example is particularly applicable when welding the right skeleton member and the left skeleton member. In addition, this embodiment may be applied when either the right skeleton member or the left skeleton member needs to be replaced.

[0053] In addition, in the above embodiment, an example has been described in which the frame members 12, 14 are formed in a square tube shape, but the shape of the vehicle members is not limited to this, as long as the 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 such an embodiment, and one embodiment may be appropriately combined with various modified examples, and the present invention may of course be embodied in various forms without departing from the gist of the present invention.

[0055] <Additional Notes> The vehicle underbody structure according to the present invention may be formed by appropriately combining the following configurations.

[0056] (Configuration 1) The joining structure for vehicle components comprises a first vehicle component having a first ridge line arranged along an extension direction, and a second vehicle component having a second ridge line arranged along the extension direction overlapping the first ridge line, overlapping the first vehicle component from the outside and fillet welded via a first weld, the second vehicle component including a notch formed in the second vehicle component and cut along the second ridge line so that the first ridge line is exposed, and a second weld where the second vehicle component is fillet welded to the first vehicle component along the notch with the first ridge line in between.

[0057] (Configuration 2) The second welded portion includes a pair of weld lines disposed opposite each other.

[0058] (Configuration 3) The length of the weld line is set to be longer than a distance measured along the outer shape of the first vehicle component, straddling the first ridge line at the entrance of the notch.

[0059] (Configuration 4) The first vehicle member and the second vehicle member are formed of an aluminum alloy. [Explanation of symbols]

[0060] 10. Frame components (vehicle components) 12 Frame member (first vehicle member) 12A Ridge (First Ridge) 14 Frame member (second vehicle member) 14A Ridge (Second Ridge) 16 Welding 16A Welding Part (First Welding Part) 16B1 Welding wire 16B Welding section (second welding section) 18 Cutting section 50 Frame parts (vehicle parts) 52 Frame member (first vehicle member) 52A Ridge (First Ridge) 54 Frame member (first vehicle member) 54A Ridge (First Ridge) 56 Plate-shaped member (second vehicle member) 56A Ridge (Second Ridge) 58 Plate-shaped member (second vehicle member) 58A Ridge (Second Ridge) 60 Cutting section 62 Cutting section L Weld length (length of weld line)

Claims

1. A first vehicle member having a first ridge line along an extension direction; a second vehicle component having a second ridge line overlapping the first ridge line along an extension direction, the second vehicle component being provided with a first welded portion overlapping and fillet-welded from an outside to the first vehicle component; Equipped with a notch formed in the second vehicle component and cut along the second ridge line so that the first ridge line is exposed; a second welded portion formed by fillet welding the second vehicle component to the first vehicle component along the cut portion with the first ridge line therebetween; A joining structure for vehicle components comprising:

2. The joining structure for vehicle members according to claim 1 , wherein the second welded portion includes a pair of weld lines provided opposite each other.

3. The joining structure of vehicle components as described in claim 2, wherein the length of the weld line is set to be longer than a dimension measured along the outer shape of the first vehicle component across the first ridge line at the entrance of the notch portion.

4. The joining structure of vehicle members 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, a notch forming step of forming a notch along the second ridge line in the second vehicle component; a member overlapping step of overlapping the second vehicle component on the outer side of the first vehicle component such that the second ridge line overlaps the first ridge line; a welding step of performing fillet welding at an overlapping portion of the first vehicle component and the second vehicle component; A method for joining vehicle components comprising the steps of:

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