JP3144504B2 - Closed section structure for automobile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a closed structure for an automobile.

[0002]

2. Description of the Related Art As a structural material for an automobile, for example, Japanese Utility Model Laid-Open No.
Japanese Patent Application No. 1193191 proposes a structure in which a square pipe-shaped outer shell 2 is filled with a foam (core 3) such as foamed urethane.

That is, a so-called closed section structure represented by a square pipe is suitable as a strength member because of its large section modulus and second moment of area and easy filling of the inside with a vibration absorbing material.

The outer shell 2 is generally made of carbon steel or aluminum because plastic has insufficient strength. At present, aluminum is extremely expensive in terms of material cost and processing cost as compared with carbon steel, and is difficult to adopt easily.

[0005] On the other hand, the above-mentioned closed cross-section structure is tough, but is also required to have a shock absorbing ability for the purpose of protecting an occupant in a collision. For that purpose, we adopt a closed section structure with different plate thickness,
A technique is used to deform the thin part.

[0006]

In a closed cross-section structure combining carbon steel sheets, the joint is generally bonded by spot welding. This is because the oxide remains in the heat-affected zone and the rust-preventive paint typified by the cation is difficult to adhere to the oxide, so spot welding with a small heat-affected zone is adopted.
At the expense of employing spot welding, the joint strength at the joint is much lower than that of continuous welding.
Therefore, an object of the present invention is to provide a steel closed-section structure that can be continuously welded.

[0007]

In order to achieve the above object, the present invention provides a method of laminating plated stainless steel sheets,
A first closed cross-section structure obtained by joining the joints by a continuous welding method and a plated stainless steel sheet having a thickness different from that of the first closed cross-section structure are overlapped, and the joined portion is subjected to a continuous welding method. interposed in a second closed section structure formed by joining in, superimposing them and first closed section structure and the second closed section structure in the longitudinal direction, the plating surface in the gap of the portion superposed
In this state, the joints are joined by a continuous welding method to form a closed cross-section structure for an automobile.

[0008]

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a closed cross-section structure for an automobile according to the present invention. A closed cross-section structure 1 for an automobile is obtained by combining a first closed cross-section structure 10 and a second closed cross-section structure 20. Become. The first closed sectional structure 10 is made of SUS430, SU
A zinc-coated stainless steel lid 12 of the same thickness is superimposed on a channel member 11 formed by press-forming a zinc-coated stainless steel plate of a constant thickness of S410 or SUS304 series, and the joint 13 is formed of MIG (inert gas). It is continuously welded by the metal arc method.

In the second closed-section structure 20, a zinc-plated stainless steel lid 22 is superimposed on a channel member 21 having a different plate thickness from that of the closed-section structure 10, and a joint 23 is formed by MI.
The second closed cross-section structure 20 is formed by continuous welding using the G method.
1 sandwiches the first closed structure 10 as shown in FIG.
After the channel member 21 and the lid 22 are aligned with the closed structure 10 described above, the joint 23 may be joined.

[0011] The above-mentioned MIG has high equipment efficiency, but has extremely high thermal efficiency, small distortion and heat-affected zone, and is non-flux, so there is no need to worry about corrosion caused by residual flux. Suitable for continuous welding.

FIG. 2 is a partial sectional view of FIG. 1, and shows that the channel member 11 and the channel member 21 are overlapped by a dimension L and are continuously welded with fillets. The plating films 14 and 24 near the bead B are burned out by welding heat, but the dimension L is sufficiently long, so that the plating films 14 and 24 in the gap 16 sufficiently remain.

Moisture and gas enter and remain in the gap 16 generated by the continuous welding, resulting in corrosion.
This corrosion is called crevice corrosion. However, according to this embodiment, as described above, the gap 16 is formed between the plating films 14 and 24.
There is no worry about crevice corrosion because it is protected by. That is, it can be said that if the type of the joint is overlapped, the internal corrosion resistance is excellent.

FIG. 3 is a reference view, and shows the channel member 11.
And the channel member 21 are butt-butted and continuously welded, and the first closed-section body 10 and the second closed-section body 20 can be connected by a butt joint. The butt joint is somewhat disadvantageous in terms of corrosion resistance as compared with the lap joint, but has the characteristic that the weight can be reduced.

FIG. 4 is a view showing another embodiment of the closed sectional structure for an automobile according to the present invention.
Channel members 31 and 32 formed by press-forming a zinc-coated stainless steel plate having a constant thickness of S430 series, SUS410 series or SUS304 series, and channel members 33 of a zinc-drawn stainless steel sheet thinner than the channel members 31 and 32. 34 are overlapped as shown in the figure, and the joints 35, 36, 37 are continuously welded by the MIG method. As described in comparison between FIGS. 2 and 3, the structure of FIG. 4 is preferable because the lap joint has good corrosion resistance.

FIG. 5 is a sectional model diagram of an embodiment of the present invention and a conventional example. A is a comparative example 1 in which a channel member having a relatively large thickness is opened at a lower portion so that water does not collect. B is Comparative Example 2, in which the lid member was spot-welded to the channel member. C is Example 1, which is the same as the automotive closed-section structure 1 described in FIG. 1, and is joined by a continuous welding method. D is Example 2, 2
The channel members are overlapped with each other and are joined by a continuous welding method. E is Example 3 in which a lid member bent at the edge is joined to the channel member, and joined by a continuous welding method.

FIGS. 6A and 6B show comparative examples 1 and 2 of FIG.
And Examples 1 to 3 are plotted with symbols A to E. In FIG. 6A, the x-axis is the thickness cross-sectional area of the member, and in Comparative Example 1 indicated by A, although the cross-sectional area is large,
Large rotation angle and low torsional rigidity. In Comparative Example 2 indicated by B, although this point is considerably improved, the torsional rigidity is still small because the joining is performed by spot welding. On the other hand, in Examples 1 to 3 indicated by C to E, the cross-sectional area is equal to or smaller than B, but has a torsional rigidity twice or more as large as B.

FIG. 6B is a graph in which the value obtained by dividing the maximum generated stress by the tensile strength is plotted on the y-axis. Since the tensile strength is a constant value for each material, the value on the y-axis is small. This indicates that the member is not overloaded. CEs (Examples 1 to 3) have extremely lower maximum generated stresses than A and B (Comparative Examples 1 and 2). If the maximum generated stress is small, the member can be made thinner, smaller and lighter by that much, which is preferable.

The closed cross-section structure having the above structure is suitable for a beam such as a front beam, a center beam, and a rear beam for an automobile, an arm, and a frame.

Furthermore, since the base material is stainless steel, there is no fear of rusting, and the joints are protected by galvanization, so that the possibility of corrosion is extremely small.

The plating is preferably zinc plating of this embodiment in terms of cost, but nickel plating, aluminum plating, and tin plating may be used. In the present embodiment, the first closed-section structure 10 is replaced with the second closed-section structure 20.
However, the present invention is not limited to this, and the third, fourth,... Closed cross-section structures may be combined therewith.

[0022]

As described above, the present invention realizes continuous welding by employing a stainless steel plate in a structure in which members having different thicknesses are combined in the longitudinal direction to enhance the absorption of impact force. Protecting the gap between the joints with plating prevents the occurrence of corrosion such as crevice corrosion. Further, by adopting a cylindrical closed cross section, it is possible to increase the bending rigidity and the flexural rigidity, and it is possible to fill the inside with a vibration absorbing material.

Since the joint types in the longitudinal direction are overlapped with each other and the plating surface is interposed in the gap between them, the corrosion resistance inside the joint is good .

[Brief description of the drawings]

FIG. 1 is a sectional view of a closed sectional structure for an automobile according to the present invention.

FIG. 2 is a partial sectional view of FIG. 1;

FIG. 3 Reference diagram

FIG. 4 is a view showing another embodiment of the closed sectional structure for an automobile according to the present invention.

FIG. 5 is a cross-sectional model diagram of an embodiment of the present invention and a conventional example.

FIG. 6 is a strength comparison diagram between an embodiment of the present invention and a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Automotive closed cross-section structure, 10 ... First closed cross-section structure, 11 ... Channel member, 12 ... Lid, 13 ... Junction, 14 ... Plating film, 20 ... Second closed cross-section structure, 21
... channel members of different plate thicknesses, 22 ... lids of different plate thicknesses, 23 ... joints, 24 ... plating films, B ... welding beads.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-53-34209 (JP, A) JP-A-3-45374 (JP, U) JP-B-63-59910 (JP, B2) (58) Survey Field (Int. Cl. ⁷ , DB name) B62D 21/00

Claims (1)

(57) [Claims] 1. A first closed cross-sectional structure formed by laminating plated stainless steel plates and joining the joints by a continuous welding method, and a plated closed plate having a thickness different from that of the first closed cross-sectional structure. In a second closed-section structure obtained by laminating stainless steel plates and joining the joints by a continuous welding method, the first closed-section structure and the second closed-section structure are overlapped in the longitudinal direction. Plating surface in the gap between the overlapped parts
A closed cross-section structure for an automobile, wherein a joint is joined by a continuous welding method in a state of being interposed .