JP2007030647A - Axial compression energy absorbing member for automobile frame made of aluminum alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an axial compression energy absorbing member for an automobile member made of light aluminum alloy free to certainly absorb energy while stably buckling and deforming. <P>SOLUTION: This axial compression energy absorbing member is made of a refined heat treated type aluminum alloy hollow shape, a shape of an outer shell part of the hollow shape is cross-section square or rectangular, a total cross-section area including the hollow part is 3000 to 8000 mm<SP>2</SP>, more than two of the hollow parts respectively having the cross-section areas of 1000 to 4000 mm<SP>2</SP>and divided by a rib are provided on the cross-section of the hollow shape and a relation of 3.2 mm≥t≥1.5 mm, 3.5≥R/t≥1.5 is characteristically satisfied when it is defined that average thickness of each side on the hollow shape is t(mm) and a radius of a corner part of the connecting part of an outline part of the hollow shape and the rib is R(mm). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an axial compression energy absorbing member for an automobile frame made of an aluminum alloy, and more particularly, aluminum attached to a superstructure of a vehicle body in order to absorb the collision energy when the automobile collides to ensure the safety of the passenger. The present invention relates to an axial compression energy absorbing member for an automobile frame made of a hollow alloy material.

  Conventionally, an energy absorbing member for protecting a passenger by absorbing energy at the time of a collision is formed into a box shape by press-molding a steel plate material and spot welding or the like. When this member receives an axial compressive load due to an impact, as shown in the compressive load-member displacement diagram of FIG. 10, when the maximum compressive load is reached, the load decreases rapidly, and the bellows starts from the end of the member. The plastic buckling proceeds and absorbs impact energy. In this case, more energy can be absorbed as the average compressive load (hereinafter simply referred to as the average load) in the compressive load-member displacement diagram is higher.

  In recent years, reduction of automobile body weight has been proposed due to environmental problems, and the impact energy absorbing member, which is a body component, also requires a lighter and higher energy absorbing member in place of the conventional steel plate box member. Attempts have been made to use aluminum alloys to satisfy this requirement. When an aluminum alloy hollow shape member having a high degree of freedom in cross-sectional shape design is used as the energy absorbing member, the amount of energy absorbed per unit mass increases as the weight is lighter and the average load is higher.

  In general, in order to obtain an excellent energy absorption efficiency by increasing the average load, it is desirable that the ratio of the average load to the cross-sectional area of the hollow profile, (average load / hollow profile cross-sectional area) is high. There is a method of providing two or more hollow portions in the cross section of the shape member. For example, in a hollow shape member having a daily cross-sectional shape in which a hollow portion is partitioned by a rib with respect to a rectangular outer portion, as shown in FIG. In addition, good energy absorption characteristics are obtained by the outer bellows being alternately bellows deformed with the rib as a boundary (see Non-Patent Document 1).

  In an aluminum alloy extruded square tube, the inner thickness of the corner of the aluminum alloy extruded square tube is made larger than the thickness of the side portion to increase (average load / hollow section cross-sectional area), that is, average per unit weight It has also been proposed to increase the load to improve the energy absorption characteristics (see Patent Document 1), but the rectangular tube shape has a small amount of energy absorption, and there is a limit to obtaining sufficient improvement in the energy absorption characteristics. There is.

Further, in a hollow extruded material having a rectangular cross section made of an Al-Mg-Si alloy, the thickness ratio of the maximum thickness to the minimum thickness of the four sides is 1 to 1.4, and the width-thickness ratio (average thickness / each side An energy absorbing member excellent in axial crushing characteristics (see Patent Document 2) has also been proposed by setting an average width (= length) of 0.1 or less when an axial compressive load is applied. An extruded material of Al-Mg-Si alloy (see Patent Document 3) having a specific composition and a specific structure capable of deforming bellows without causing crushing cracks has also been proposed, but it is lighter and has higher energy absorption. There is a need for further improvement in order to meet the demands of new members.
Sumitomo Light Metal Technical Report, Vol. 37, No. 3, No. 4 (1996), 190-200 pages JP-A-9-254808 Japanese Patent Laid-Open No. 11-193433 JP 2002-285272 A

In order to solve the above-mentioned conventional problems in the energy absorbing member made of an aluminum alloy extruded profile, the inventors have previously described the thickness, length of each side, As a result of examining the relationship between the cross-sectional area and the like, the absorbed energy, and the deformation form, it is composed of a tempered heat-treatable aluminum alloy hollow shape, and the hollow shape is a square or rectangle having a single hollow part, It has a wall thickness exceeding 2 mm, the cross-sectional area excluding the hollow part is 350 mm ² or more, the average length of each side in the cross section of the hollow profile is a, the radius of the corner part is R, the average thickness of each side When the thickness is t, the following relationships are satisfied: 0 <R / a ≦ 0.2, t / a ≦ 0.2, R / a <5 × (t / a) −0.37 For aluminum alloy car frames An energy absorbing member was proposed (Japanese Patent Application No. 2003-357416).

The present invention is a further improvement of the proposed energy absorbing member, and its purpose is to stably buckle and increase the amount of energy absorption when subjected to an axial compressive load. It is to provide an axial compression energy absorbing member for an automobile frame made of aluminum alloy.

In order to achieve the above object, an axial compression energy absorbing member for an aluminum alloy automobile frame according to claim 1 of the present invention comprises a tempered heat-treated aluminum alloy hollow shape member, and an outer shell portion of the hollow shape member. the shape in cross-section square or rectangular, the entire cross-sectional area including the hollow portion is of 3000～8000Mm ^2, the cross section of the hollow profile is partitioned by the respective ribs have a cross-sectional area of 1000～4000Mm ² Two or more hollow portions are provided, the average thickness of each side of the hollow shape member is t (mm), and the radius of the corner portion of the joint portion between the outer portion and the rib of the hollow shape member is R (mm). In this case, the relationship of 3.2 mm ≧ t ≧ 1.5 mm and 3.5 ≧ R / t ≧ 1.5 is satisfied.

An axial compression energy absorbing member for an automobile frame made of aluminum alloy according to claim 2 has an average load per unit cross-sectional area of 110 N / mm when an axial compression load is applied to the hollow shape member according to claim 1. It is characterized by being ² or more.

  The axial compression energy absorbing member for an automobile frame made of aluminum alloy according to claim 3 is characterized in that, in claim 1 or 2, the hollow section defined by the rib is square or rectangular in cross section.

  ADVANTAGE OF THE INVENTION According to this invention, when the axial compressive load is loaded, the lightweight axial compression energy absorption member for automotive frames made from an aluminum alloy which can absorb energy efficiently, deforming stably is provided. Is done.

  The axial compression energy absorbing member for an automobile frame made of an aluminum alloy according to the present invention is made of a tempered heat-treatable aluminum alloy hollow shape member. As the heat-treatable aluminum alloy, for example, an Al—Zn—Mg alloy or an Al—Mg—Si alloy is applied, and these aluminum alloys are preferably subjected to T5 treatment or T6 treatment as tempering after extrusion.

As shown in FIG. 11, the hollow profile 1 has a square or rectangular cross-sectional shape of the outer shell having two or more (two in FIG. 2) hollow portions 3, 3 partitioned by ribs 2. The total cross-sectional area including the hollow part of the hollow profile 1 is 3000 to 8000 mm ² , the cross-sectional areas of the hollow parts 3 and 3 are 1000 to 4000 mm ² , respectively, and the average thickness of each side of the hollow profile 1 is t (mm ), Where R (mm) is the radius of the corner portion of the joint portion 5 between the outer shell portion 4 and the rib 2, 3.2 mm ≧ t ≧ 1.5 mm, 3.5 ≧ R / t ≧ 1.5 Designed to satisfy the relationship.

  If the average thickness t of each side is larger than 3.2 mm, the weight of the entire member will increase more than necessary, which will hinder weight reduction, and the stress generated in the hollow shape material will increase when the bellows is deformed, and cracking will easily occur. Become. When the average thickness is less than 1.5 mm, each side elastically buckles against compressive deformation in the axial direction and the average load is reduced, and as a result, energy absorption characteristics required for general automobiles are obtained. Becomes difficult. A more preferable average thickness of each side is 3.2 mm ≧ t ≧ 2.4 mm, and energy can be absorbed more effectively.

  The ratio of the radius R of the corner portion of the joint portion 5 between the outer shell portion 4 and the rib 2 and the average thickness t preferably has a relationship of 3.5 ≧ R / t ≧ 1.5. Becomes larger, and it becomes possible to increase the average load at the time of bellows deformation, and as shown in FIG.

  When R / t is larger than 3.5, the rigidity of the coupling portion 5 becomes too high, and the outer shell portion 4 cannot be alternately bellows deformed with the rib 2 as a boundary, thereby obtaining stable energy absorption characteristics. When R / t is less than 1.5, the effect of increasing the rigidity of the connecting portion 5 is insufficient, and the amount of increase in the average load is also reduced.

When the total cross-sectional area including the hollow part 3 is less than 3000 mm ² , when the cross-sectional area of the hollow part 3 exceeds 4000 mm ² , the substantial cross-sectional area of the hollow shape member is reduced and the average load is reduced. As a result, it becomes difficult to obtain energy absorption characteristics required for general automobiles. On the other hand, if the total cross-sectional area that includes a hollow portion 3 exceeds 8000mm ^2, if the cross-sectional area of the hollow portion 3 is less than the 1000 mm ² increases more than necessary total mass member, the effect of weight reduction is small Become.

The hollow part 3 of the hollow shape member 1 is preferably formed in a square or rectangular cross section, and can stably deform bellows and reliably absorb energy. Further, when the hollow member is applied as an energy absorbing member for an automobile frame, the average load per unit cross-sectional area when receiving an axial compressive load is preferably 110 N / mm ² or more.

  Examples of the present invention will be described below in comparison with comparative examples. In addition, these Examples show one embodiment of this invention, and this invention is not limited to these.

  An aluminum alloy billet having the composition shown in Table 1 is extruded into a hollow shape having a shape shown in FIGS. A test material was cut to a thickness of 300 mm. 1 is the invention material 1, FIG. 2 is the invention material 2, FIG. 3 is the invention material 3, FIG. 4 is the invention material 4, FIG. 5 is the comparison material 1, and FIG. 6 is a comparative material 2, FIG. 7 is a comparative material 3, and FIG. 8 is a comparative material 4.

  The obtained test material was subjected to a static axial compression test at a test speed of 1 mm / second. Each test material was placed on a base of an Instron universal testing machine, a compression load was applied by the pressure plate, and a load-displacement diagram applied to the pressure plate was recorded. As long as it is possible to apply a compressive load to the tester used, the same result can be obtained regardless of the tester used. If the contact surfaces are parallel, it has been confirmed that similar results can be obtained regardless of the shape.

The test results are shown in Table 3 and FIG. As shown in Table 3 and FIG. 9, the inventive materials 1 to 4 of the test material according to the present invention stably deformed bellows, and the average load per unit weight also shows a value exceeding 110 N / mm ^2. It was confirmed that it has excellent energy absorption characteristics. In addition, if the cross section of the outer shell portion is a square, a rectangle, or a shape close to these, the effect of the present invention can be obtained regardless of the radius R of the corner of the outer shell portion, and T5 after the extrusion process. It was confirmed that the effects of the present invention can be obtained even when tempering.

  On the other hand, the comparative material 1 of the test material could not obtain stable energy absorption characteristics because the bellows deformation form was disturbed and deformed laterally during axial compression deformation. In Comparative materials 2 to 4, although stable bellows deformation occurred, since R / t was less than 1.5, the rigidity of the joint portion 5 between the outer shell portion 4 and the rib 2 was not sufficient, and the average load was It is low and the energy absorption property is inferior.

It is sectional drawing which shows the Example of the energy absorption member by this invention. It is sectional drawing which shows the Example of the energy absorption member by this invention. It is sectional drawing which shows the Example of the energy absorption member by this invention. It is sectional drawing which shows the Example of the energy absorption member by this invention. It is sectional drawing which shows a comparative material. It is sectional drawing which shows a comparative material. It is sectional drawing which shows a comparative material. It is sectional drawing which shows a comparative material. It is a figure which shows the average load per unit cross-sectional area of a test material. It is a compression load-member displacement diagram in case a hollow energy absorption member receives the compression load of the vertical direction by the impact. It is a figure which shows the deformation | transformation form at the time of receiving the general | schematic cross section of the energy absorption member by this invention, and the axial compressive load.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hollow member 2 Rib 3 Hollow part 4 Outer shell part 5 Coupling part R The radius of the corner part of the coupling part of outer shell part and rib

Claims (3)

It consists of a tempered heat-treated aluminum alloy hollow shape, and the shape of the outer shell of the hollow shape is square or rectangular in cross section, and the total cross-sectional area including the hollow is 3000 to 8000 mm ^2. the cross section of the wood, and hollow portions partitioned by the ribs have a cross-sectional area of 1000～4000Mm ² each are provided two or more, the average thickness of each side of the hollow profile t (mm), the hollow Satisfying the relationship of 3.2 mm ≧ t ≧ 1.5 mm, 3.5 ≧ R / t ≧ 1.5, where R (mm) is the radius of the corner of the joint between the outer portion of the profile and the rib A shaft compression energy absorbing member for an automobile frame made of an aluminum alloy. ^{2. The} axial compression for an aluminum alloy automobile frame according to claim 1, wherein an average load per unit cross-sectional area when an axial compression load is applied to the hollow shape member is 110 N / mm ² or more. Energy absorbing member. 3. The axial compression energy absorbing member for an aluminum alloy automobile frame according to claim 1, wherein the hollow section defined by the rib has a square or rectangular cross section.

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