JP2002059277A - Structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint shape for suppressing degradation of the strength of a welded joint part when a hollow shape is friction-agitation-welded. SOLUTION: The thickness of a face plate 101 (111) between a rib 103 (113) and a rib 105 (115) at an end of the hollow shape 100 (110) is t2 (t5) on the rib 105 (115) side, and t1 on the rib 103 (113) side, and t2 (t5) is larger than t1. The part between the parts of different thickness is smoothly changed. The thickness of t2 (t5) is provided by the protrusion on the other face plate side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint shape of a hollow material used for friction stir welding. For example, the present invention relates to an aluminum alloy hollow profile used for railway vehicles, buildings, and the like.

[0002]

2. Description of the Related Art In a friction stir welding method, a round bar (referred to as a rotary tool) inserted into a joint is moved along a joining line while rotating, so that the joint is heated, softened, plastically fluidized, and solid-phased. It is a joining method. The rotary tool has a small diameter portion inserted into the joint and a large diameter portion located outside. The small diameter part and the large diameter part are coaxial. The boundary between the small diameter portion and the large diameter portion is slightly inserted into the joint. The rotary tool is tilted backward with respect to the direction of joining.

[0003] When the member to be joined is a hollow profile, the joint at the end has a rib connecting two face plates at the end of one hollow profile, and the rib at the end of the other hollow profile. A face plate is overlaid on the rib. In addition, each face plate has a convex portion protruding to the outer surface side with the rib as a center. This part is friction stir welded.

This is disclosed in Japanese Patent Application Laid-Open No. 09-508073 (EP 0 759 926 B2) and Japanese Patent Application Laid-Open No. 09-30916.
No. 4 (EP0797043A2).

[0005]

When joining a structure using a hollow member, the structure of the joint has a complicated shape unlike other parts. For this reason, it is necessary to prevent a decrease in the strength of the joint.

[0006] In order to prevent a reduction in strength due to welding, it is known that the joint is made thicker than other parts regardless of the welding method. However, in general parts, the plate thickness is reduced as much as possible for the purpose of weight reduction. As a result, a large difference in rigidity occurs between a general part of the structure and the joint. The difference in rigidity between adjacent parts is
Out-of-plane bending deformation occurs due to stress concentration and bending moment. For this reason, a complicated stress field is formed, and the strength is reduced.

Furthermore, when the friction stir welding method is used, a large load acts in the insertion direction because the rotary tool is inserted into the hollow profile. This load is received by the rib connecting the two face plates. Further, a force acts not only in the insertion direction but also in the radial direction. For this reason, the ribs are provided in order to bear the load generated by the insertion, and the thickness of the ribs is increased. In addition, the shape of the joint becomes complicated. If the joint shape is complicated to increase the strength in this way, the difference in rigidity between the joint and a general part constituting the hollow section is further increased. This increases the out-of-plane bending moment and reduces the mechanical strength of the joint. As described above, in the case where the structure can withstand the load generated at the time of joining in terms of strength, there is a trade-off relationship that the mechanical strength required for practical use is reduced due to the difference in rigidity.

Further, when tensile or out-of-plane bending deformation occurs in the hollow extruded profile of the structure, the load is mainly borne by the face plate. Here, at the intersection of the face plate and the rib, the cross section changes suddenly and stress concentrates, and a high stress is generated as compared with other general parts. For this reason, at the intersection of the face plate and the rib, a higher stress is generated as compared with the stress generated at a general portion of the face plate, which causes a decrease in strength.

[0009] In addition to the above, it is known that the strength of the heat-affected zone for welding becomes the lowest regardless of welding methods such as friction stir welding and MIG welding. Even in the case of friction stir welding in which the width of the heat-affected zone is narrower than that of MIG welding, a report that the width of the heat-affected zone is about 13 mm from the center of the tool has been reported.
-10), p332-p333. According to this report, it can be said that almost all joints with complicated shapes are heat affected zones.

As described above, in the joint for friction stir welding,
(1) bending moment induced by the difference in rigidity (plate thickness), (2) stress concentration due to the unique complicated shape of the joint,
(3) The thermal effect of welding and (4) the effect of stress concentration due to the connection between the rib and the face plate are synergistic.

[0011] An object of the present invention is to provide friction stir welding with:
An object of the present invention is to provide a joint structure whose strength does not decrease.

[0012]

SUMMARY OF THE INVENTION According to the present invention, face plates of two hollow profiles are friction stir welded to each other, and each hollow profile is composed of two substantially parallel face plates and the face plate. A first rib for connecting the face plates at an end of the first rib, and a second rib for connecting the face plates at the other end side of the first rib. One of the face plates between the first rib and the second rib, wherein a thickness of the face plate near a connecting portion between the first rib and the one face plate is equal to a thickness of the second rib. Thickness is greater than the thickness of the one face plate in the vicinity of the connection portion with the one face plate, and the thicker face plate protrudes toward the other face plate side and is thicker, is there.

[0013]

1 to 3 show an embodiment of the present invention.
It will be explained by. In FIG. 3, a railway vehicle structure 200 is shown.
Is formed with a wife structure 201 that forms a surface that closes both ends in the longitudinal direction of the vehicle body, a side structure 202 that forms left and right surfaces in the longitudinal direction of the vehicle body, a roof structure 203 that forms a roof, and a floor surface It is composed of an underframe 204. The side structure 202 has windows and entrance openings. Railcar structure 2
00 is an aluminum alloy hollow extruded profile (hereinafter referred to as a hollow profile) 100, in whole or in part.
110 are joined. The case where the hollow profiles 100 and 110 are arranged on the side structure 202 and the roof structure 203 is shown. The extrusion direction (longitudinal direction) of the hollow profiles 100 and 110 is arranged in the longitudinal direction of the vehicle body.

In FIG. 2, hollow members 100 to be joined are
1 shows the periphery of the joint 110. Hollow profile 100 (110)
Are two parallel face plates 101, 102 (111, 11
2), a plurality of ribs 103 (113) that connect face plates to each other and are inclined with respect to the face plate,
0 (110), two face plates 101, 10
2 (111, 112) and is composed of ribs 105 (115) perpendicular to the face plate. Rib 103
(113) is arranged in a truss shape. Rib 105
There are face plates 101, 102 (111, 112) between (115) and the rib 103 (113) adjacent thereto.
One of the two face plates may be inclined with respect to the other.

Referring to FIG. 1, the joint will be described. Here, the joint of the hollow members 100 and 110 on the upper surface will be described with reference to FIG. 2, but the same applies to the joint on the lower surface. The configuration of the upper surface and the configuration of the lower surface of the joint shape of another embodiment described later are the same.

The face plate 101 of the hollow profile 100 has ribs 105.
Projecting toward the end. The end of the face plate 101 is located within the range of the thickness of the rib 115. The end of the hollow profile 110 has a concave portion on the side of the face plate 111 so as to receive the face plate 101.

The end of the hollow member 110 has a protruding piece 116 protruding toward the end from the rib 115. The protruding piece 116 is located on the back side of the end of the face plate 101 and serves as a backing.

The face plate 101 of the hollow member 100 (110)
The outer surface of the end of (111) protrudes, and the protrusion 107 (1
17).

The projection 107 (1) of the face plate 101 (111)
The surface at the end of 17) is orthogonal to the face plate. A surface of the recess on the side of the face plate 111 (a face to which the end of the face plate 101 is butted)
Is perpendicular to the face plate 111. The surface of the concave portion on the side of the face plate 111 is within the range of the thickness of the rib 115.

The connection between the ribs 103, 105 (113, 115) and the face plate 101 (111) is arc-shaped. The connecting portion between the rib 115 and the face plate 111 has a protruding portion 118 protruding in an arc shape on the hollow portion side. Rib 103 and face plate 101
The radius R1 of the arc at the connection with the rib 105 and the face plate 10
It is larger than the radius R2 of the circular arc of the connection part on the acute angle side with the first.

The thickness t2 of the face plate 101 at the connection between the rib 105 and the face plate 101 is larger than the thickness t1 of the face plate at the connection between the rib 103 and the face plate 101 and the thickness t1 of the face plate 101 at the general portion. The outer surface of the face plate 101 is flat except for the protrusion 107. The plate thickness t2 is on the hollow portion side (the other face plate 102
Side) to make it thicker. Rib 103 and rib 10
The face plate 101 between 5 is smoothly changed. Sheet thickness t
The distance from 2 to the plate thickness t1 is determined in consideration of the thermal effect of friction stir welding.

The thickness t5 of the face plate 111 on the protrusion 117 side
Is the thickness t of the face plate at the connection between the rib 113 and the face plate 111.
1 and the thickness t1 of the face plate 111 of the general part. The outer surface of the face plate 111 is flat except for the protrusion 117. The plate thickness t5 is made thicker by protruding toward the hollow portion. The distance from the plate thickness t5 to the plate thickness t1 of the face plate 11 is determined in consideration of the thermal effect of friction stir welding. The thickness of the face plate 111 from t5 to t1 is smoothly changed.

The thickness t2 (t) of the face plate 102 (112)
The distance of the face plate 102 from 5) to t1 is the face plate 101
Face plate 1 from plate thickness t2 (t5) to t1 on the (111) side
It is the same as the distance of 01.

The center of the rotary tool for friction stir welding is located on an extension of the thickness of the rib 115. For this reason, the rib 11
5 supports most of the insertion force of the rotary tool.

Although there is no gap in the drawing between the butted portions of the two hollow members 100 and 110 (the butted portion of the end of the hollow member 100 and the end of the hollow member 110), there is a gap. Often.

The rotary tool has a large diameter portion and a small diameter portion at the tip. A part of the boundary between the small diameter portion and the large diameter portion is
And friction stir welding is performed between the outer surface of the protrusion and the outer surface of the protrusion. The tip of the small diameter portion reaches the upper surface of the projecting piece 116. The diameter of the large diameter portion is smaller than the total width of the two protrusions 107 and 117. After the friction stir welding, the protrusion 107,
If 117 is unnecessary, it is cut. This flattens the outer surface of the structure.

According to this configuration, the section modulus can be increased in the face plate near the joint where the out-of-plane bending moment is maximized. The relationship between the section modulus, the out-of-plane bending moment and the generated stress can be expressed by the following equation.

Σ = M / Z (1) σ: generated stress M: out-of-plane bending moment Z: sectional modulus The sectional modulus Z per unit width can be expressed in the following form.

Z = h * h / 6 (2) Z: section modulus h: plate thickness In formula (2), the out-of-plane bending moment M of the molecule is constant, but by increasing the plate thickness. The section modulus Z of the denominator increases in proportion to the square of the plate thickness. For this reason, it is possible to reduce the occurrence of stress due to the out-of-plane bending moment. Furthermore, the out-of-plane bending moment is the largest at the joint between the joint and the face plate, and decreases as the distance increases. For this reason, in the part where the out-of-plane bending moment is large, the plate thickness is greatly improved and the stress is greatly reduced, and in the part where the out-of-plane bending moment is small, the plate thickness is slightly increased and the stress is slightly reduced, thereby reducing the weight. Can be measured. Further, by increasing the thickness inside the face plate, the rigidity between the face plate and the joint can be smoothly changed. For this reason, it is possible to reduce the stress concentration caused by the joint shape and the presence of the rib. Furthermore, since a smooth surface can be obtained in appearance, the appearance is good.

The radius R1 of the arc at the connection between the rib 105 and the face plate 101 is also large. Therefore, it is possible to reduce stress concentration in a portion where the strength is reduced due to the thermal influence of the friction stir welding, and to improve the strength.

The embodiment shown in FIG. 4 will be described. The thicknesses of the face plates 101 and 111 near the joint (near the ribs 105 and 115) are all t2 and t5. On the side of the face plate 102 (112), the distance of the face plate having the thickness t2 (t5) is
From the rib 105 (115) on the (111) side to the rib 103
This is the same as the distance to (113).

Since the shape near the joint is complicated, it is difficult to specify the distribution of stress and the deformation mode. However, according to this embodiment, the strength can be improved irrespective of the stress distribution and the deformation mode.

The embodiment shown in FIG. 5 will be described. A plurality of fins 109, 1 on the outer surface side of the face plates 101, 111 near the joint.
19 are provided integrally.

According to this, since the heat generated by the bonding is radiated from the fins 109 and 119, the area where the strength is reduced due to the heat is narrowed, and the strength can be improved.

The embodiment shown in FIG. 6 will be described. The ribs 105 and 115 are located at the same distance from the ends (end surfaces of the protruding portions) of the face plates 101 and 111 to be butted. The diameter of the large-diameter portion of the rotary tool is larger than the distance from the rib 105 to the rib 115 (not the distance between the centers of the plate thicknesses of the ribs 105 and 15 but the distance between the surfaces of the ribs 105 and 115 on the hollow side). Is big. Thus, the two ribs 105 and 115 support the insertion force of the rotary tool. The plate thicknesses t2 and t5 of the face plate and the radius of the arc R2 are the same as those in the above embodiment.

In the embodiment shown in FIG. 7, the end of the hollow member is different between the upper surface and the lower surface. Face plate thickness t
2, t5, and the radius of the arc R2 are the same as those in the above embodiment.

The technical scope of the present invention is not limited to the language described in each claim or the language described in the section for solving the problem, and is easily replaced by those skilled in the art. It extends to a range.

[0038]

According to the present invention, it is possible to provide a hollow member whose strength does not decrease when a friction stir welding method is applied to joining members.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a pair of hollow profiles according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a joint on the upper surface side in FIG. 1;

FIG. 3 is a perspective view of a railway vehicle structure to which the present invention is applied.

FIG. 4 is an enlarged sectional view of an upper surface side of a joint according to another embodiment of the present invention.

FIG. 5 is an enlarged sectional view of the upper surface side of a joint according to another embodiment of the present invention.

FIG. 6 is an enlarged sectional view of the upper surface side of a joint according to another embodiment of the present invention.

FIG. 7 is an enlarged sectional view of the upper surface side of a joint according to another embodiment of the present invention.

[Explanation of symbols]

100, 110 ... hollow shape members, 101, 102, 111,
112 ... face plate, 103, 105, 113, 115 ... rib, 107, 117 ... protrusion, 109, 119 ... fin

Continued on the front page (72) Inventor Toshiaki Makino 794, Higashi-Toyoi, Katsumatsu-shi, Yamaguchi Prefecture F term in the Kasado Plant of Hitachi, Ltd. 4E067 AA05 BG00 DA13 EA00 EB00

Claims (4)

[Claims] 1. A face plate of two hollow profile members is friction stir welded to each other, and each of said hollow profile members includes two substantially parallel face plates and said face plates at an end of said face plate. A first rib that connects the first rib and a second rib that connects the face plates on the other end side of the first rib. The first rib and the second rib The thickness of the face plate near the connection between the first rib and the one face plate is greater than the connection between the second rib and the one face plate. The thickness is greater than the thickness of the one face plate in the vicinity of, and the thicker face plate protrudes toward the other face plate side and is thicker. 2. The structure according to claim 1, wherein the thickness of the face plate between the first rib and the second rib decreases as going toward the second rib. A structure. 3. The structure according to claim 1, wherein the other face plate between the first rib and the second rib is a connection portion between the first rib and the other face plate. Is thicker than the thickness of the other face plate near the connection between the second rib and the other face plate, and the thicker face plate is on one of the face plate sides. The structure is characterized by being protruded and thicker. 4. The structure according to claim 1, wherein a thickness of each of the one face plate and the other face plate between the first rib and the second rib is closer to the second rib. A structure characterized in that the plate thickness decreases as going.