JP2003048569A - Collision energy absorbing member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automotive collision energy absorbing member that is light, excellent in productivity, high in deformation energy at compressive deformation and inexpensive. SOLUTION: One or two bent sheets of steel are joined in combination to structure a polygonal closed section shape with a partition wall therein. A plurality of partition walls are preferably formed about an axis perpendicular to the polygonal closed section in the polygonal closed section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collision energy absorbing member for an automobile vehicle, and more particularly to a collision energy absorbing member which absorbs a large amount of energy in a collision.

[0002]

2. Description of the Related Art A front side member, a rear side member, and the like, which constitute a vehicle, play an important role as a collision energy absorbing member that is appropriately crushed during a vehicle collision to absorb energy at the time of collision and suppress deformation of a cabin. ing. An example of the front side member directly connected to the bumper of the automobile is shown in FIG. For example, in a frontal collision, a collision load (arrow) is transmitted from the bumper in the axial direction of the front side member. Due to this load, the front side member is crushed in a bellows shape and absorbs collision energy when crushed.

However, if the energy absorption capacity of the front side member is low, it will lead to a serious disaster that damages the occupants. Therefore, a member having a high energy absorbing ability is required for the collision energy absorbing member such as the front side member. To meet such a demand, for example, in Japanese Patent Laid-Open No. 4-310477, a basic member extruded into a closed cross-section structure with a light metal is fitted into the basic member and compressed to at least the tip of substantially the same length. A vehicle side member has been proposed in which a double structure is formed with a reinforcing member provided with a deformation promoting portion, preferably a notch. According to the side member described in Japanese Patent Laid-Open No. 4-310477, bending rigidity, torsional rigidity, and crushing deformation can satisfy characteristics equal to or higher than those of steel side members. However, JP-A-4-3104
The side member described in Japanese Patent Publication No. 77 has a problem that the basic member is extruded from a light metal and is expensive, and the structure of the reinforcing member is complicated, so that the manufacturing cost is high.

Further, in Japanese Laid-Open Patent Publication No. 11-208519, a member which absorbs a shock at the time of collision by plastic deformation in the axial direction is formed of a hollow material, and the hollow material is provided on a surface passing through the central axis of the hollow material. There has been proposed a vehicle body frame structure formed of a light metal material, characterized in that a rib connecting to the inner surface of the vehicle is provided.
The vehicle body frame structure described in Japanese Patent Laid-Open No. 11-208519 uses a light metal material and is preferably manufactured by extrusion molding, and is said to have excellent impact energy absorption characteristics at the time of collision. However, there is a problem that an extrusion molding material of a light metal material such as aluminum is expensive. In addition, when a light metal material is used for the collision energy absorbing member, there is also a problem that there is a restriction in joining with a member made of an adjacent steel plate.

Further, in Japanese Patent Laid-Open No. 2000-254997, a sheet molding compound molded product obtained by mixing an epoxy acrylate resin and a polyisocyanate compound in an appropriate amount is combined with a steel material, and preferably a hat-shaped cross section is formed. Impact energy absorbing members have been proposed. The impact energy absorbing member described in Japanese Patent Laid-Open No. 2000-254997 is lightweight, and the maximum load and average load during compression deformation can be easily adjusted by combining steel materials and sheet molding compound moldings. . However, this member has a problem that the manufacturing cost is high because it requires steps such as forming a sheet molding compound molded product and joining a steel material and the sheet molding compound molded product.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, is lightweight, has excellent productivity, has a high deformation energy at the time of compression deformation, and is inexpensive, and is a collision energy absorbing member for automobiles. The purpose is to provide.

[0007]

[Means for Solving the Problems] The present inventors have conducted extensive studies in order to achieve the above-mentioned objects. In order to enhance the energy absorption capacity at the time of collision of members, measures such as (1) increasing the plate thickness and (2) optimizing the sectional shape of the member can be considered.

Increasing the plate thickness can be realized relatively easily. However, recently, from the viewpoint of global environmental conservation,
It is required to reduce CO ₂ emissions from automobiles, and as a result, the weight of vehicle bodies is being reduced. Therefore, it is not preferable to increase the plate thickness, which leads to an increase in the weight of the vehicle body. on the other hand,
Optimizing the sectional shape of the member is advantageous in that the amount of absorbed energy per unit weight of the member can be increased. Therefore, the present inventors have further researched a measure for optimizing the sectional shape of the member.

First, in order to optimize the cross-sectional shape, members having various shapes of closed cross-section structures were produced. Then, with respect to these members, a test material having a constant length in the axial direction was sampled and crushed and deformed at a high speed. From the relationship between the load and displacement obtained during crush deformation, the absorbed energy absorbed by the member during crush deformation was calculated. As a result, it was found that in the case of a closed cross-section structure, a member having a cross-sectional shape with a partition inside has a much larger absorbed energy during high-speed crushing deformation than a member without a partition inside.

As a method of manufacturing a member having a closed cross-section structure having such a partition wall, a light metal material such as aluminum, which has been widely used in the past, is generally extruded. But cheaper than aluminum alloy,
Applying this extrusion method to steel materials is extremely difficult. Therefore, the present inventors have studied a method of manufacturing a member having a closed cross-section structure having this partition wall by sheet metal working using a thin steel plate. As a result, it was found that a member having a closed cross-section structure having a partition wall can be easily manufactured by joining two or less bent steel plates by spot welding, arc welding or the like.

First, the results of experiments conducted by the present inventors will be described. Collision energy absorption that uses a thin steel plate with a thickness of 1.2 to 1.6 mm that is often used for front side members to make the basic cross-section into a square or hexagonal closed cross-section by bending and joining Material (length: 300
mm) was prepared. In addition, some of the members were members (A type, C type, E type) having a partition wall inside the closed cross-sectional shape. The thin steel sheet used is a high-strength steel sheet with a tensile strength of 440 MPa.

A weight is collided with these members at a speed of 50 km / h,
By integrating the displacement-load curve obtained during this collision deformation, the absorbed energy (J) when deformed 150 mm
FIG. 4 shows the absorption energy of each shape as the ratio of the absorption energy to the reference, with the square cross section (D type) having no partition wall as the reference at each plate thickness. From Fig. 4, the sectional shape with partition walls (A type, C type, E
It can be seen that a member having a type) has a larger absorbed energy at the time of collision deformation than a member having a sectional shape without a partition (type B, type D). Above all, the absorbed energy of a member having a sectional shape (A type, E type) based on a hexagon is large.

Thus, by combining the optimization technology of the cross-sectional shape and the optimization technology of the steel plate processing, the collision energy absorbing member which is excellent in productivity and has high deformation energy at the time of compressive deformation can be manufactured easily and at low cost. I found that I could achieve it. . The present invention has been completed based on the above findings. That is, the present invention is an automobile collision energy absorbing member configured by combining steel plates, wherein the steel plates are two or less bent thin steel plates, and the two or less bent thin steel plates are used. A collision energy absorbing member for an automobile, which is characterized by being configured to have a polygonal closed cross-section shape having a partition wall inside by joining together, and in the present invention, the partition wall has a polygonal closed cross-section. It is preferable that a plurality of them are formed around an axis perpendicular to the closed polygonal cross section.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The collision energy absorbing member for automobiles of the present invention is a collision energy absorbing member for automobiles formed by combining steel plates, and has a polygonal closed cross-sectional shape having a partition wall inside. In addition, it is preferable that a plurality of partition walls formed inside the polygonal closed cross section are formed around an axis perpendicular to the polygonal closed cross section.

The member having a polygonal closed cross-section having a partition inside is formed by using two or less thin steel plates and combining bending work by sheet metal working and joining such as laser welding and arc welding. Examples of the polygonal closed cross-sectional shape having a partition wall therein include basic cross-sectional shapes of A type (hexagonal cross section), C type (square cross section), and E type (hexagonal cross section) as shown in FIG. A member having a polygonal closed cross section having a partition wall inside thereof can be manufactured by bending and joining using one or two thin steel plates.

The method of manufacturing the member of the present invention will be described below.
The type (hexagonal section) will be explained as an example. The outline is shown in FIG. In FIG. 2A, two steel plates (material 1,
Use material 2). First, B ', A, D of material 1
Bend E, F, A'parts by press brake or roll forming. Next, the A portion and the A ′ portion of the material 1 are joined by spot welding, laser welding, arc welding or the like. Then, the D ', C, B, G, F'parts of the material 2 are bent by press brake or roll forming. Then, the B ′ portion of the material 1 and the B portion of the material 2 are joined by laser welding or the like. Since it is difficult to perform spot welding, it is preferable to stack the materials (steel plates) and then perform laser welding from the outside. Then, the D part of the material 1 and the D'part of the material 2, and the F part of the material 1 and the F'part of the material 2 are joined by laser welding, arc welding or the like. By such a procedure, it is possible to manufacture a member having a polygonal closed cross section having a partition wall inside the E type.

In FIG. 2B, as in FIG.
Use one steel plate (material 1, material 2). The D ', C, B, A, D, E, F, and A'parts of the material 1 are bent by press brake or roll forming. At this time, it is preferable that the bending of the B portion is made small from the viewpoint of facilitating the subsequent joining at the A portion. Then, the A portion and the A ′ portion of the raw material 1 are joined by spot welding, laser welding, arc welding or the like. After joining, the part B of the material 1 is bent to a predetermined final shape. Then, the B ', G, F'parts of the material 2 are bent by press brake or roll forming. Next, the D part of material 1 and the D'part of material 2, the B part of material 1 and the B'part of material 2, and the F part of material 1 and the F'part of material 2,
Are joined by laser welding, arc welding, or the like. Also by such a procedure, an E type member having a polygonal closed cross section having a partition wall inside can be manufactured.

In FIG. 2 (c), one steel plate (material 1) is used. Material 1 D ', C, B, A, D, E, F,
The parts A ', B', G, F'are bent by press brake or roll forming. At this time, it is preferable that the B and B'parts are slightly bent to facilitate the joining of the A and A'parts. Then, the A portion and the A ′ portion are joined by spot welding, laser welding, arc welding or the like. Then, laser welding of B part and B'part, D'part and D part, F part and F'part,
Join by arc welding or the like. In the case of FIG. 2 (c),
Since some material overlaps, the weight increases.

Such a method of manufacturing by sheet metal working and joining has an advantage that a flange can be easily attached to a member more easily than extrusion molding and a degree of freedom of joining with another component is large in assembling a vehicle body. FIG. 3 illustrates a case where a flange is attached to the end surface of the member. In order to attach a flange to the end face of the member, a steel plate (material) for producing the energy absorbing member before being formed into the member shape may be additionally provided with the shape for the flange and then bent.

Similarly, a member having an A-type cross-sectional shape and a member having a D-type cross-sectional shape are 2
It is possible to manufacture as shown in FIG. 5 by using sheet metal sheets and combining sheet metal working (bending) and joining. Needless to say, the manufacturing method of the member of the present invention is not limited to the above manufacturing method.

[0021]

EXAMPLES The present invention will be described in more detail based on examples. As shown in Fig. 2 (a) or Fig. 4, using one or two thin steel plates (sheet thickness: 1.2 mm) as a material, bending by rolls (roll forming) and laser welding, arc welding or spot welding 1 was combined to produce a collision energy absorption member (length: 300 mm) having a hexagonal or quadrangular closed cross-section having a partition wall as shown in FIG. 1 and used as an example of the present invention. In addition, so that the weight is the same,
The sum of the cross-section line lengths was the same. The thin steel plate used as the material was a 780 MPa class high strength steel plate or a 980 MPa class high strength steel plate.

A thin steel sheet similar to the example of the present invention is used, and bending (roll forming) and joining by laser welding, arc welding or spot welding are combined to form a hexagonal or quadrangular closed cross-section having no partition wall. A collision energy absorbing member was produced and used as a comparative example. Further, an aluminum alloy member having an A-type cross-sectional shape was produced by extrusion molding, which was used as a conventional example. In the conventional example, the wall thickness of the partition wall was 2 mm.

With respect to these members, the absorbed energy (J) when the weight collides with the weight at a speed of 50 km per hour and is deformed by 150 mm was obtained by integrating the displacement-load curve obtained during the collision deformation. The results are shown in Table 1.

[0024]

[Table 1]

Each of the examples of the present invention exhibits high absorbed energy and has excellent impact energy absorbing ability. If the plate thickness is the same, the larger the tensile strength (TS) of the material, the larger the absorbed energy. Further, since the example of the present invention can be manufactured by simple sheet metal working and simple welding, the manufacturing cost is low. On the other hand, a comparative example having a cross-sectional shape without partitions (members No.1, No.2, No.7, No.8)
In comparison with the examples of the present invention, the absorbed energy is lower and the impact energy absorption capacity is lower. Further, the conventional example made of an aluminum alloy member shows high absorbed energy, but since the aluminum alloy extruded material is expensive, the manufacturing cost becomes very high.

As described above, according to the present invention, it is possible to easily provide a collision energy absorbing member having both high absorbed energy and low manufacturing cost.

[0027]

According to the present invention, a collision energy absorbing member excellent in collision energy absorbing ability can be provided easily and at low cost, and the industrially remarkable effect is exhibited.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a basic sectional shape of a member of the present invention.

FIG. 2 is an explanatory view showing an example of a method of manufacturing a collision energy absorbing member of the present invention.

FIG. 3 is a perspective view schematically showing an example of a collision energy absorbing member of the present invention.

FIG. 4 is a graph showing a relationship between a sectional shape and absorbed energy in collision deformation.

FIG. 5 is an explanatory view showing an example of a method of manufacturing a collision energy absorbing member of the present invention.

FIG. 6 is an explanatory view schematically showing an example of a front side member.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiaki Tamai             1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki             Technical Research Institute of Iron Co., Ltd. (72) Inventor Hideo Abe             1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki             Technical Research Institute of Iron Co., Ltd.

Claims (2)

[Claims] 1. A collision energy absorbing member for an automobile, comprising a combination of steel plates, wherein the steel plates are two or less bent thin steel plates, and the two or less bent thin steel plates are assembled. A collision energy absorbing member for an automobile, which is joined together and configured to have a polygonal closed cross section having a partition wall inside. 2. The collision energy absorbing member for an automobile according to claim 1, wherein a plurality of the partition walls are formed in a polygonal closed cross section around an axis perpendicular to the polygonal closed cross section.