JP2000085358A - Composite door beam material and composite door beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent buckling of a cross section without affecting reduction in weight and to improve energy-absorbing capacity by filling a space part of an aluminum alloy structural angle with resin foam having fine closed cells. SOLUTION: A space part of an aluminum alloy structural angle is filled with resin foam 1. Preferably, the space of the structural angle is closed, and then, the resin is foamed inside the space for filling the space and the resin foam tightly adhering to the space part inside face is provided, however, the space may be filled with previously foamed resin alternatively. A resin having closed-cell structure is desirable, and the density of the resin foam is about 0.12-0.5 g/cm3, and for emphasizing energy-absorbing capacity, a density of about 0.3-0.5 g/cm3 is desirable. In a typical one, its cross section is a closed cross section constructed of upper and lower flanges and a pair of webs connecting both flanges together or a solid cross section. In this way, energy- absorbing capacity can be increased in comparison with increase in weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a door beam material used as a reinforcing member of a vehicle for improving safety in a vehicle collision.

[0002]

2. Description of the Related Art An automatic door beam is required to have a function of absorbing a load at the time of a collision. For example, FMVSS
(U.S. Federal Safety Standards) states that when a load is ultimately applied from the side of an actual vehicle, a certain reference value is applied to the bending load value for that load and the energy absorption represented by the area of the load-deformation relationship. At the laboratory level, they are generally assumed to collide with a vehicle, and support both ends of a door beam material as shown in FIG. 1 (a), and press the central portion thereof with a load jig. It is evaluated by the bending performance of the three-point bending test. In the load (P) -displacement (δ) curve (see FIG. 1B) obtained by the bending test, the maximum load and
It is considered that it is desirable that the displacement before buckling or breaking is large and the energy absorption amount is large. Conventional door beam materials are generally made of high-strength and inexpensive steel or extruded aluminum alloy, which has low strength compared to steel but has a complicated cross-sectional shape and can be reduced in weight.

In recent years, aluminum extruded profiles have been frequently used from the viewpoint of weight reduction, and door beam materials using aluminum extruded profiles have been disclosed, for example, in Japanese Patent Laid-Open No. 5-3 / 1993.
Various patents have been filed, such as JP-A-11309, JP-A-5-247575, and JP-A-7-164880. JP-A-10-94444 describes a door beam in which a functional resin is attached to the inner surface of a hollow portion, and JP-A-9-202138 describes that a resin is attached to the outside for reinforcement and decoration. ing.

[0004]

On the other hand, the demand for improving the collision safety of automobiles has been demanded not only for large luxury cars but also recently for small public cars. Therefore, it has become necessary to develop a door beam material that is lighter and has a higher energy absorption capacity. However, the cross section of a conventional metal door beam is tubular for weight reduction, and if the radius of curvature of bending is too small, the cross section buckles due to concentration of strain, so the amount of energy absorption is drastically reduced, and the worst case In some cases, it was broken. In the case of small cars and small cars with small door thickness, the height of the door beam in the load direction cannot be increased.
To that extent, the secondary moment of area becomes small, and the bending strength becomes insufficient. However, if the thickness of the profile is increased to compensate for this, there is a problem that the weight increases, and it is not possible to meet the demand for weight reduction.

[0005] The energy absorption of the door beam material greatly differs depending on whether or not the cross section buckles. If this buckling can be prevented, the energy absorption will be dramatically improved. Therefore, the present invention prevents buckling of the cross section of the door beam material,
It is an object of the present invention to obtain a door beam material that improves energy absorption and does not impair weight reduction.

[0006]

In order to prevent buckling of the cross section of the door beam material, it is necessary to prevent stress from being locally concentrated even when the radius of curvature of the bending is small. Therefore, in the present invention, a foamed resin is filled in the space of the aluminum alloy profile to form a composite door beam material. When the door beam material is filled with foamed resin with fine closed cells, the foam resin is constrained at its periphery.When the bending load is applied and the door beam material starts to deform, the foamed resin gradually compresses. Load is applied. Closed cells can easily deform up to a certain compressive load, but it becomes difficult to deform when the pressure inside the closed cells increases with an increase in compressive load, so the deformation of the door beam material propagates around the periphery with low resistance, resulting in As a result, the stress concentration is reduced, and the load can be uniformly dispersed. Further, since the strength is improved by this foamed resin, a lightweight and high-strength door beam material can be obtained. These effects of foamed cells with closed cells are more pronounced when dynamic (shock) deformations such as actual side impacts are applied than when static deformations are applied. .

[0007] As an application of the above invention, it is conceivable that after the door beam material is screwed with bolts, the end screw portion is filled with a foamed resin. By filling the foamed resin, it is possible to prevent moisture from entering the door beam, and to prevent a local battery from being formed between dissimilar metals (aluminum alloy and bolts / nuts) to cause electrolytic corrosion. in this case,
A foamed resin having closed cells is desirable, and a foamed resin other than the screwed portion may be filled.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As a composite door beam material of the present invention in which a foamed resin is filled in the space of an aluminum alloy profile, a known foamed resin can be used, and a known foaming method can be used. Available. Regarding the method of filling the foamed resin, it is preferable to close the space of the shaped material, foam and fill the inside, and obtain a foamed resin in a state of being in close contact with the inner surface of the space. It can also be inserted and filled in the part. In any case, it is desirable that the foamed resin has a closed cell structure. Generally speaking, the density of foamed resin is about 0.12 g / c.
When m ³ or more, the cells have closed cells, and the energy absorption performance is improved. On the other hand, when it exceeds 0.5 g / cm ³ , problems such as an increase in cost and an increase in door beam weight arise. Therefore, the density of the foamed resin is 0.12 to 0.5 g / c.
m ³ , especially when emphasis is placed on energy absorption performance, 0.3
0.5 g / cm ³ is desirable.

Heating when the foamed resin is foamed and filled in the space of the profile may be performed also as a heat treatment of the aluminum alloy profile. That is, as the shape of the composite door beam material of the present invention, 7000 series (Al-Zn-Mg series) or 60
When a heat-treated aluminum alloy such as a 00-series (Al-Mg-Si-based) alloy is used, an artificial aging treatment may be performed after solution heat treatment or press quenching (quick cooling immediately after hot extrusion). By performing both the aging treatment and the heating of the foaming, the process can be made more efficient and the heat treatment cost can be reduced.

[0010] As shown in Fig. 2 (a), a typical profile used for a door beam has a cross section composed of upper and lower flanges and a pair of webs connecting both flanges. In addition to the closed cross section (hollow cross section), for example, a solid cross section as shown in FIG. 2B is also conceivable. In this case, the space portion in the present invention refers to a range surrounded by the flange and the web. means. In order to fill such a space with the foamed resin 1, for example, a method of closing the space between both flanges with a masking material 2 and causing foaming in the space can be considered. After the foaming molding, the masking material 2
It can be removed as needed.

Further, instead of filling the entire cross section of the space portion with the foamed resin 1 as shown in FIG.
As shown in (d), the foamed resin 1 may be filled in one direction. Also in this case, a method of closing with the masking material 2 and foaming therein can be used. Alternatively, when the spaces are partitioned by middle ribs as shown in FIGS. 2E and 2F, only one of the spaces may be filled with the foamed resin 1. When a part of the cross section of the space is filled with the foamed resin as described above, an increase in weight of the door beam material can be suppressed and a corresponding effect can be obtained. Therefore, it is effective particularly when weight reduction is important. When importance is placed on the effect of preventing breakage of the door beam material, it is preferable to fill the inside (occupant side) with a foamed resin as shown in FIGS. 2C and 2E. As shown in 2 (d) and 2 (f), the outer side (the side to which a load is applied) may be filled with a foamed resin.

The filling of the foamed resin may be performed over the entire length of the door beam material, but may be performed only on a part thereof. For example, it may be filled over a predetermined length only in the central portion where the cross section is likely to buckle due to distortion concentrated when receiving a load. This is advantageous in terms of weight reduction of the composite door beam material.

It is efficient and advantageous to fill the foamed resin in the composite door beam material before mounting it on the door mounting seat, but it is also possible to fill it after mounting.
When filling after mounting, there are the following advantages.
For example, FIG. 3 (a) shows a structure in which both ends of an aluminum alloy profile are attached to a mounting seat of a door with bolts and nuts and then filled with foamed resin having closed cells over the entire length of the profile. Prevents water from entering from both ends of the door beam, and prevents the formation of a local battery between dissimilar metals (aluminum alloy and bolts / nuts) to prevent electrolytic corrosion. Also, as shown in FIG.
In particular, only both ends can be filled with the foamed resin. At this time, a masking material may be used to limit the filling of the foamed resin to both ends. Also, use a composite door beam material in which foam resin is pre-filled in the center in the longitudinal direction of the profile or a composite door beam material in which foam resin is pre-filled in its entire length excluding both ends, and attach it to the mounting seat, The portion may be filled with a foamed resin.

[0014]

EXAMPLE Two extruded aluminum alloy members having the cross-sectional shape shown in FIG. 4 were prepared, and one of them was formed by foaming urethane resin inside the space and filling the entire cross section of the space with the foamed resin over the entire length. Door beam materials were manufactured. The foamed resin had a density of 0.35 g / cm ³ and had fine closed cells. This door beam material was subjected to a three-point bending test with a span of 800 mm (up to δ = 10 inches). The load (P) -displacement (δ) curves of each door beam material are shown in FIGS. 5 and 6, and the obtained characteristics are shown in Table 1.

[0015]

[Table 1]

No. 1 was not filled with a foamed resin. In No. 1, the inner flange (occupant side) was broken at an early stage, and the amount of absorbed energy was small. 2 is δ = 1
At 0 inches, there is no buckling of the web or breakage of the inner flange, and the rate of increase in the amount of absorbed energy is greater than the increase in weight.

[0017]

According to the present invention, it is possible to obtain a door beam member which prevents buckling of the cross section of the door beam member, improves energy absorption, and at the same time does not impair weight reduction. In addition, when foaming resin is filled into the screwed portions at both ends, there is also an effect of preventing electrolytic corrosion.

[Brief description of the drawings]

FIG. 1 is a diagram showing a bending test method and a load-displacement curve of a door beam material.

FIG. 2 is a diagram illustrating a filling mode of a foamed resin.

FIG. 3 is a diagram illustrating a door beam in which a foamed resin is filled into an end of an aluminum alloy profile.

FIG. 4 is a view showing a cross section of the aluminum alloy profile used in the examples.

FIG. 5 is a load-displacement curve of a door beam material in which a space is not filled with a foamed resin.

FIG. 6 is a load-displacement curve of a door beam material in which a space is filled with a foamed resin.

[Explanation of symbols]

 1 Foam resin

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hiroyuki Yamashita 14-1, Nagafuminatocho, Shimonoseki City, Yamaguchi Prefecture F-term in Kobe Steel, Ltd. Chofu Works (reference) 2E016 HA09 JA01 JA11 JC09 KA05 LB02 LB05 LC02 NA07 4F100 AB10B AB31B AK01A AK51 BA02 BA07 BA10B DC25B DD25B DD31 DD32B DJ01A DJ02A EH31 EJ02 GB32 JK04 JL00 YY00

Claims (4)

[Claims] 1. A composite door beam material wherein a foamed resin is filled in a space of an aluminum alloy profile. 2. The composite door beam material according to claim 1, wherein the foamed resin has closed cells. 3. A composite door beam wherein an end screwed portion of a door beam made of an aluminum alloy material is filled with a foamed resin. 4. The composite door beam according to claim 3, wherein said foamed resin has closed cells.