JPH07145843A - Energy absorbing member made of aluminum alloy for automobile - Google Patents

Abstract

PURPOSE:To provide an energy-absorbing member made of aluminum alloy for automobile which effectively absorbs the impact energy by forming in the transverse direction of a shape material a soft part which is the starting point of the bellows-shaped deformation of the shape material when the compressive stress is applied to the longitudinal direction of the shape material at the end part of the shape material. CONSTITUTION:An energy-absorbing member made of aluminum alloy for automobile is composed of the hollow extruded material made of tempered, heat-treated aluminum alloy, and a soft part A which can be the bellows-shaped deformation or the starting point of the bellows-shaped deformation when the compressive stress is applied to the longitudinal direction of the shape material is formed in the transverse direction of the shape material at the end part in the longitudinal direction of the shape material. The thickness of the shape material is >=2mm, and the total sectional area including the hollow part of the shape material is 3000-8000mm<2>. One or two or more hollow parts with the sectional area of 1000-4000mm<2> respectively are provided in the section of the shape material. This constitution allows the free design of the shape of a hollow extruded material made of aluminum alloy according to the place to be applied, and the productivity is also excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy automobile energy absorbing member, and more particularly, to a vehicle upper structure for absorbing the collision energy in the event of collision of the automobile to ensure the safety of passengers. To an energy absorbing member made of an aluminum alloy hollow profile attached to the.

[0002]

2. Description of the Related Art Conventionally, an energy absorbing member for absorbing energy at the time of a collision and protecting an occupant is formed by pressing a steel plate material into a box shape by spot welding or the like. When a vertical compressive load is applied to the member due to an impact, the load rapidly decreases when the maximum load is reached, as shown in the model diagram of impact load-member deformation amount in FIG. The ideal energy absorption form is that it is deformed into a bellows shape and plastic buckling proceeds to absorb impact energy.

In order to realize such an energy absorption mode, when a collision load is applied to a steel plate box-shaped member, a bellows-like buckling deformation must be surely caused from the load-loaded end of the member. I have to. Therefore, a design method for promoting buckling by providing a bead portion or a hole portion in the steel plate box-shaped member has been studied. (Mitsubishi Heavy Industries Technical Report, Vol.8, No.1, No.12
(Pp. 4-130)

In recent years, it has been proposed to reduce the weight of automobile bodies due to environmental problems, and the use of lighter aluminum alloys and plastics for the body and the members constituting the body instead of conventional steel plates has been studied. Its use has been realized. In this case, in the vehicle body structure formed by material replacement,
Instead of the conventional steel plate box member, a member that is lighter in weight and has higher energy absorption is required.

[0005]

DISCLOSURE OF THE INVENTION The present invention focuses on an aluminum alloy hollow extruded shape member which is lightweight and can be easily attached to a structure by welding in order to develop an energy absorbing member which meets the above-mentioned requirements. Various experiments were conducted based on the research results of steel plate box-shaped members, and the maximum load when compressive stress was applied was approximately equal to the product of the cross-sectional area of the profile and the proof stress of the material, and the pitch of deformation was hollow. It is almost equal to (vertical length + horizontal length) / 2 of the material, and if the bellows deformation starts at one point of the shape member, it will continue to deform like a bellows unless cracked. Etc.,
Based on these test results, it was made as a result of diligent examination of the combination of the optimum member material, shape, size, form of deformation starting point, etc. as an energy absorbing member made of an aluminum alloy, and its purpose is to be lightweight and (EN) It is possible to provide an aluminum alloy energy absorbing member for an automobile, which has a high energy absorption degree and buckles and is deformed sequentially from a terminal portion when an impact load is applied to thereby effectively absorb the impact energy.

[0006]

To achieve the above object, an aluminum alloy automatic energy absorbing member according to the present invention comprises a heat-treated aluminum alloy hollow extruded material having a tempered length. At the end of the profile, a soft part that can be the origin of the bellows deformation of the profile when a compressive stress is applied in the length direction of the profile is formed in the lateral direction of the profile, and the wall thickness of the profile the 2mm or more, the total sectional area including the hollow portion of the profile is 3000～8000Mm ^2, a hollow portion having a cross-sectional area of each of the cross-section 1000～4000Mm ² of profile 1
One or two or more are provided, and at the end of the profile in the length direction,
It is a basic structural feature that a soft portion, which can be a starting point of the bellows-like deformation of the shape member when a compressive stress is applied in the length direction of the shape member, is formed in the lateral direction of the shape member.

Further, the soft portion is formed by locally heating the profile, the profile is a rectangular hollow profile having a partition wall in the central portion in the long side direction, and the profile is long. The third, fourth and fifth characteristics of the structure are that the material is made of a hollow shape member having partition walls at positions symmetrical with respect to the center lines in the side direction and the short side direction.

The heat-treatable aluminum alloy constituting the hollow profile of the present invention is, for example, 7000 series Al-Zn-M.
A g-based alloy or a 6000-based Al-Mg-Si-based alloy is applied. These aluminum alloys have T as a temper after extrusion.
5 treatment or T6 treatment is preferable, and the elongation rate is 17% or more. As the hollow shape member, the total cross-sectional area including the hollow portion is 3000 to 8000 mm ² , preferably 3500 to
It is 6500 mm ^2, a round tube or square tube hollow portion is provided one or more, each having a cross-sectional area of 1000～4000Mm ² is preferably used. The lower limit of the cross-sectional area of the hollow part is 2500 mm ² or more for one hollow part and 10 for two or more.
More preferably, it is set to 00 mm ² or more. Each cross section is 4000
A hollow material with a size of more than mm ² will have insufficient strength and energy absorption will decrease. With a hollow shape member having a large number of hollow portions having a small cross-sectional area, the deformation becomes complicated and the bellows deformation hardly occurs. The profile of less than 3000 mm ² total cross section including a hollow portion,
When the strength is not sufficient and a compressive stress is applied, the maximum load becomes low, and the desired average load cannot be obtained, and the energy absorption capacity decreases. Even if it exceeds 8000 mm ² , the energy absorption effect cannot be expected to be significantly improved, and it becomes impractical.

A feature of the present invention is that the end portion in the longitudinal direction of the shape member is provided with a soft portion which can be a starting point of the bellows-like deformation of the shape member when a compressive stress is applied in the longitudinal direction of the shape member. Forming in the lateral direction. It is preferable that the soft part which can be the starting point of the bellows-like deformation is provided at one position of the end of the profile as shown in FIG. 1 by locally heating the profile. When many soft parts are arranged in parallel, the maximum load when compressive stress is applied is too low to obtain the desired average load during deformation, and the energy absorption amount is decreased because it does not match the deformation pitch. The soft portion is formed by adjusting the conditions of local heating so that the proof stress of that portion becomes a value obtained by dividing the maximum load required when a compressive stress is applied by the total cross-sectional area of the profile.

As the hollow profile applied in the present invention, a round tube or a square tube is preferably used as described above. In the case of a round tube, for example, a hollow portion having a cross-sectional area of 2500 to 4000 mm ² is used. For hollow tubes and square tubes, the total cross-sectional area is 4000 ~
It is preferable that a hollow square tube of 8000 mm ² is partitioned into two to four hollow portions so as to be symmetrical, and each hollow portion has a cross-sectional area of 1000 to 3000 mm ² .

[0011]

In the present invention, due to the specified combination of constituent materials, material characteristics, cross-sectional shape, dimensions, form of deformation starting point, etc., it is lightweight and has high energy absorption, and can be easily welded to an automobile body. It is possible to obtain an energy absorbing member that can be applied to front and rear side members, steering shafts, side doors, impact members, and the like.

[0012]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. Example 1 Zn6.0% (weight%, the same applies hereinafter), Mg0.8%, Mn0.
An aluminum alloy billet containing 17% and Zr 0.18% and the balance Al was extruded under the conditions of an extrusion temperature of 500 ° C. and an extrusion ratio of 10, and as shown in FIG. 1, FIG. 2 and FIG.
0mm, width 60mm, thickness 2.6mm, bulkhead thickness 2.6mm, cross-section rectangular rectangular tube, 100mm length, width 60mm, thickness 2.3mm, bulkhead 2.3mm rectangular rectangular tube And vertical 100mm,
A rectangular rectangular tube with a cross section of 60 mm in width and 3.5 mm in thickness was used.
After air cooling, T5 treatment was carried out at 120 ° C. for 24 hours, and a soft portion A was formed on the outer surface of the end of the rectangular tube 30 mm below the upper end by heating at 410 ° C. for 5 minutes by a high frequency induction heating method and air cooling. These square tubes are cut to a length of 380 mm and the compression speed is 20 m.
A static compression test was performed at m / min. The test results are shown in Table 1 and FIG.

[0013]

[Table 1]

In the test material No. 1 of the energy absorbing member according to the present invention, the maximum load was reduced by about 25% due to the formation of the soft portion, but it could be suppressed to about 21 tf and deformed into a bellows shape at a small pitch, The load-displacement diagram is as shown in Fig. 4, and the absorbed energy up to a compression displacement amount of 200 mm was 24 kJ or more, indicating excellent energy absorption capacity. Test material No. 2 also deformed into a bellows shape with a small pitch, and the absorbed energy up to a compression displacement amount of 200 mm showed a high value of 28.6 kJ. On the other hand, the rectangular square tube with a cross section of B-shaped (Comparison 1) started to deform from the soft side, but the deformation was irregular and the average load in the load-displacement diagram decreased and sufficient energy absorption was not achieved. It was

Comparative Example 1 An aluminum alloy billet having the same composition as in Example 1 was extruded in the same test as in Example 1 to obtain a rectangular rectangular tube having a cross-section of the same size as that of Example 1, and a cross-section of rectangular cross section. A rectangular rectangular tube and a rectangular rectangular tube having a cross-section of square shape were used. These square tubes were cut into a length of 380 mm, and a static compression test was performed at a compression speed of 20 mm / min. The test results are shown in Table 2.

[0016]

[Table 2]

As shown in Table 2, the energy absorbing members according to the comparative examples were not stable in the starting point of deformation at the central portion or the opposite end portion. When such a member is actually used, the bellows deformation becomes unstable as the collision speed increases, and the member is easily bent and deformed.

[0018]

As described above, according to the present invention, there is provided an energy absorbing member which is lightweight, weldable, and has a high energy absorbing ability. Since a hollow extruded shape of aluminum alloy is used, the shape can be freely designed according to the place of use and is excellent in productivity.

[Brief description of drawings]

FIG. 1 is a simplified perspective view showing a soft part of a hollow profile used in the present invention.

FIG. 2 is a simplified perspective view showing a soft part of another embodiment of the hollow mold member used in the present invention.

FIG. 3 is a simplified perspective view showing a soft part of a hollow frame shown as a comparative example.

FIG. 4 is a load-displacement diagram in a static compression test of a rectangular rectangular tube having a Japanese cross section used as an energy absorbing member of the present invention.

FIG. 5 is a diagram showing an impact load-deformation amount relationship for explaining impact energy absorption in an energy absorbing member.

[Explanation of symbols]

 A soft part

Claims (5)

[Claims] 1. A bellows-shaped deformation of a heat-treatable aluminum alloy hollow shaped material which is subjected to a compressive stress in the longitudinal direction of the shaped material at the end of the shaped material in the longitudinal direction. An energy absorbing member for an automobile made of an aluminum alloy, characterized in that a soft portion which can be a starting point of is formed in a lateral direction of the profile. 2. A heat-treated aluminum alloy hollow profile material, which has been heat-treated, has a wall thickness of 2 mm or more and a total cross-sectional area including the hollow portion of the profile of 3000 to 8000 mm ^2. of the cross-section hollow portion having a cross-sectional area of 1000～4000Mm ² each are provided one or more, the longitudinal end of the profile, when loaded with compressive stress in the longitudinal direction of the profile An aluminum alloy energy absorbing member for an automobile, characterized in that a soft portion which can be a starting point of a bellows-like deformation of the profile is formed in a lateral direction of the profile. 3. The energy absorbing member for an automobile made of an aluminum alloy according to claim 1, wherein the soft portion is formed by locally heating the profile. 4. The shape member is a rectangular hollow shape member having a partition wall at the center in the long side direction.
The energy-absorbing member for automobiles made of an aluminum alloy according to 1 to 3. 5. The shape member according to claim 1, wherein the shape member is a hollow shape member having a partition wall at a position symmetrical with respect to a central portion in the long side direction and a center line in the short side direction. Aluminum alloy energy absorbing member for automobiles.