JP2000240707A - Metallic shock-absorbing hollow member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a metallic shock-absorbing hollow member which is able to fully absorb impact energy and also excellent in strength. SOLUTION: An aluminum shock-absorbing hollow member made up with a thin-walled part 2 in the axial one side part by means of applying the working of spinning to the hollow member, is manufactured. When any compressive load is applied to the shock-absorbing hollow member 1 in the axial direction, a thick-walled part 3 is deformed after the thin-walled part 2 is deformed first. Therefore, the hollow member 1 is suppressed its load peak, and it maintains the sufficient mean load, whereby it is able to fully absorb the impact energy, and thus it comes to be so excellent in strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal shock absorbing hollow material used for, for example, a frame material or a bumper of an automobile.

[0002]

2. Description of the Related Art In recent years, in the automobile industry and the like, in consideration of environmental issues, in order to reduce fuel consumption by reducing the weight of a vehicle, it is necessary to use aluminum as a material for a frame or a bumper, etc. Is actively pursuing. At the same time, in order to protect the occupant in the event of a collision, a crushable zone is provided in the front and rear of the vehicle body (in the engine room and trunk room), where the bellows deform by bellows, making it easier to collapse, and absorbing the impact energy at the time of the collision. Improves safety.

However, the conventional shock absorbing hollow members used for frame members, bumpers, and the like have a uniform thickness in all portions in the axial direction. There was a problem.

That is, when a compressive load is applied to a hollow material in the axial direction, as shown in a load-displacement curve (W) in FIG. 6, the hollow material has a load peak after an initial stage of deformation. Shows the characteristic of maintaining the average load within a certain range,
When a load peak occurs at the stage of such initial deformation, there is a problem that absorption of collision energy immediately after collision becomes insufficient.

Further, in order to suppress a load peak at an early stage of deformation, as shown in FIG.
When the thickness t5 of 1) is formed thin, there is a problem that the average load is reduced as shown by the load-displacement curve (W1) in FIG. 6 and the strength (load resistance) of the hollow material is reduced. On the other hand, when the thickness t6 of the hollow member (21) is formed thick as shown in FIG. 5B in order to keep the average load high, the load peak becomes as shown in the load-displacement curve (W2) in FIG. And the absorption of the collision energy immediately after the collision becomes insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem, and it is possible to sufficiently absorb impact energy by suppressing a load peak in an early stage of deformation and maintaining a sufficient average load. It is an object of the present invention to provide a metal shock absorbing hollow material that is made and has excellent strength.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide a metal shock absorber characterized in that a thin part having a relatively small thickness is formed over the entire circumference at a part or a plurality of parts in the axial direction. It is solved by a hollow material.

According to this, when a compressive load is applied in the axial direction, the thin portion is deformed first, so that the load peak in the initial stage of deformation can be reduced. Further, when a compressive load is further applied in the axial direction, portions other than the thin portion are deformed, so that the average load can be sufficiently maintained. For this reason, this shock absorbing hollow material has a small load peak,
In addition, since it has a load-displacement characteristic in which an average load is sufficiently maintained, it is possible to sufficiently absorb impact energy with respect to an axial compressive load and to maintain the strength of the hollow material as a whole. Can be.

Also, from one end in the axial direction to the other end,
It is desirable to form the thin portion by continuously reducing the wall thickness. According to this, when a compressive load is applied to the hollow member in the axial direction, the hollow member is continuously deformed from the minimum thin portion, and the impact energy can be more smoothly absorbed with respect to the compressive load in the axial direction.

[0010]

Next, an embodiment of the present invention will be described.

In FIG. 1, (1) is a shock absorbing hollow member made of aluminum (including its alloy) having a circular cross section according to an embodiment of the present invention. The hollow material for shock absorption (1) has an inner peripheral surface formed on a cylindrical surface (1a) parallel to the axis, and an outer peripheral surface on an upper small-diameter cylindrical surface (1b) and other large-diameter cylindrical surfaces. (1c) is formed. In other words, one portion (upper portion) in the axial direction of the hollow member has a thickness t1.
And the other portion is a thick portion (3) having a thickness t2. For this reason, this shock absorbing hollow material (1) has the characteristic that the load peak at the stage of the initial deformation is suppressed by the thin portion (2), and a sufficient average load is maintained by the thick portion (3). Will have properties.

The thin portion (2) is generally formed by subjecting a hollow material obtained by extrusion or the like to spinning, swaging, pressing, or cutting. It may be formed by a forging method, a variable cross-section extrusion method, or the like.

Next, deformation when a compressive load is applied to the shock absorbing hollow member (1) in the axial direction will be described.

When a compressive load is applied to the shock absorbing hollow member (1) in the axial direction, first, the thin portion (2) having a small thickness undergoes bellows deformation in the axial direction. Then, when a compressive load is further applied in the axial direction, the thick portion (3) is subjected to bellows deformation in the axial direction, and the thick portion (3) near the other end where the thin portion (2) is not formed is completely formed. When the bellows are deformed, the entire hollow member (1) is completely deformed. At this time, hollow material for shock absorption (1)
Is a state in which each bellows deformed portion is axially folded over the entire side wall.

As described above, when a compressive load is applied to the shock absorbing hollow member (1) in the axial direction, the thin portion (2) having a small thickness is deformed first, so that the load peak in the initial stage of deformation is suppressed. be able to. Further, when a compressive load is further applied in the axial direction, the thick portion (3) is deformed, so that the average load can be sufficiently maintained. For this reason, the shock absorbing hollow member (1) has a load-displacement curve (W ′) shown in FIG.
As shown in the above, since the load peak in the initial stage of deformation is suppressed, and the average load is sufficiently maintained, the impact energy can be sufficiently absorbed with respect to the axial compressive load, The strength of the entire hollow material can be maintained.

In this embodiment, the thin part (2) is formed at one end in the axial direction of the shock absorbing hollow member (1). However, the thin part is formed at both ends, or as shown in FIG. As shown in FIG. 2, one or a plurality of thin portions (5) may be formed in the middle of the hollow member (4).

Next, another embodiment of the present invention will be described.

As shown in FIG. 4, this hollow material for shock absorption (6) has a circular cross section. The inner peripheral surface is formed into a cylindrical surface (6a) parallel to the axis by the same processing as described above, and the outer peripheral surface is formed. The surface is formed as a tapered surface (6b) similar to the outer peripheral surface of the cone. That is, the shock absorbing hollow member (6) has a thickness t.
4 is formed so that the thickness is continuously reduced from one axial end (lower end) to the other axial end (upper end) of the thickness t3, thereby forming one end in the axial direction. The side part (upper part) is a thin part (7), and the other part (lower part) is a thick part (8).
The shock absorbing hollow member may have an outer peripheral surface formed into a cylindrical surface and an inner peripheral surface formed into a tapered surface.

Next, the deformation when a compressive load is applied to the shock absorbing hollow member (6) in the axial direction will be described.

When a compressive load is applied to the shock absorbing hollow member (6) in the axial direction, one end having the minimum thickness t3 is subjected to bellows deformation in the axial direction. Then, when a compressive load is further applied in the axial direction, the hollow material (6) is continuously deformed toward the other end having the maximum thickness t4, and when the vicinity of the end of the maximum thickness t4 is subjected to bellows deformation. The entire transformation ends. At this time, the shock absorbing hollow member (6) is in a state where the bellows deformed portions are folded in the axial direction.

As described above, since the shock absorbing material (6) is formed so that the thickness thereof is continuously reduced in the axial direction, the shock absorbing material (6) is continuously deformed when a compressive load is applied in the axial direction, and is continuously deformed in the axial direction. The impact energy can be more smoothly absorbed with respect to the compression load.

In each of the embodiments, the cross section of the shock absorbing hollow members (1) and (6) is circular.
It may be a polygon. In addition, hollow material for shock absorption (1)
Although (6) is made of aluminum, it may be made of other metals such as copper.

The minimum thickness t of the shock absorbing hollow material _{m i
n} is the maximum thickness t _{m a It} is desirable that _x is set within the following range. These minimum thicknesses t _{m i n} and maximum thickness t _{m a In} the embodiment shown in FIGS. 1 and 2, _x corresponds to the thickness t1 of the thin portion (2) and the thickness t2 of the thick portion (3) of the hollow member (1), and is shown in FIG. In the embodiment, the thickness corresponds to the thickness t3 of one end in the axial direction of the hollow member (6) and the thickness t4 of the other end.

[0024] 0.05t _{m a x} <t _{m i n} <0.95t _{m a x} t _{m i n} : minimum thickness t _{m a x} : Maximum thickness The range was set as the minimum thickness t. _{m i n} is 0.0
5t _{m a When the} thickness is less than _x , the thickness becomes too thin, and it becomes difficult to form a thin portion of the hollow material, and the minimum thickness t _{m i n} is 0.95t _{m a This is because if} it is not less than _x , the effect of suppressing the load peak at the stage of the initial deformation can hardly be secured.

In order to avoid the difficulty of forming a thin portion and more effectively suppress the load peak, the minimum thickness t _{m i n} is the maximum thickness t _{m a} Most preferably, _x is within the following range.

0.30t _{m a x} <t _{m i n} <0.70t _{m a x}

[0027]

The hollow material for shock absorption according to the present invention has a load-displacement characteristic in which the load peak is small and the average load is sufficiently maintained. Energy can be sufficiently absorbed, and the strength of the hollow material as a whole can be maintained. Therefore, if this metal hollow material for impact absorption is applied to an automobile frame, a bumper, or the like, the collision safety performance can be further improved, and the occupant can be more reliably protected from impact.

According to the second aspect of the present invention, when a compressive load is applied to the hollow member in the axial direction, the hollow member is continuously deformed, and the impact energy can be more smoothly absorbed by the compressive load in the axial direction. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view and a longitudinal sectional view of a shock absorbing hollow member according to an embodiment of the present invention.

FIG. 2 is a perspective view and a longitudinal sectional view of a shock absorbing hollow member according to another embodiment of the present invention.

FIG. 3 is a view showing load-displacement characteristics of the shock absorbing hollow member of FIG. 1;

FIG. 4 is a perspective view and a longitudinal sectional view of a shock absorbing hollow member according to still another embodiment of the present invention.

FIG. 5 is a perspective view of a conventional shock absorbing hollow material.

FIG. 6 is a view showing a load-displacement characteristic of the shock absorbing hollow member of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hollow material for shock absorption 2 ... Thin part 3 ... Thick part

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // B60R 19/04 B60R 19/04 M B62D 1/19 B62D 1/19 (72) Inventor Shoichi Sato Kaiyamacho, Sakai City 6-224 Address Showa Aluminum Co., Ltd. F-term (reference) 3D030 DE33 3J066 AA02 BA04 BB01 BC01 BD07 BF04 BG01

Claims (2)

[Claims] 1. A metal shock absorbing hollow material characterized in that a thin portion having a relatively small thickness is formed over the entire circumference at a part or a plurality of parts in an axial direction. 2. The hollow material for a metal shock absorber according to claim 1, wherein the thickness is continuously reduced from one end to the other end in the axial direction.