JP4075055B2 - Impact energy absorbing member and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an impact energy absorbing member that is used, for example, as a structural member of an automobile and is used to absorb impact energy and soften the impact while collapsing during a collision.
[0002]
[Prior art]
As the impact energy absorbing member, there is a porous metal which has been attracting attention in recent years. As a conventional method for forming a porous metal, there is a method of obtaining a porous structure of metal by foaming a sintered body using magnesium hydride as an expandable metal powder (see, for example, Patent Document 1). .)
[0003]
As another porous metal molding method, there is a method in which a foaming step is provided after the metal melting step to increase the viscosity of the molten metal and then foam using a foaming aid (for example, , See Patent Document 2).
[0004]
On the other hand, as an impact energy absorbing member other than the above-described porous metal, there is a metal panel having increased rigidity. This metal panel body includes one panel having cone-shaped embossing and the other flat panel, and has a structure in which the embossed bottom of one panel is spot-welded to the other flat panel. (For example, refer to Patent Document 3).
[0005]
[Patent Document 1]
JP 11-012605 A [Patent Document 2]
JP 07-233428 A [Patent Document 3]
JP-A-2002-307117 [0006]
[Problems to be solved by the invention]
However, conventionally, when the impact energy absorbing member is made of a porous metal, there has been a problem that it takes a manufacturing cost because it is necessary to heat the material once to the vicinity of the melting point of the metal at the time of molding.
[0007]
On the other hand, in the metal panel body with increased rigidity as a conventional impact energy absorbing member, since by bonding the embossed bottom of the cone shape in the one panel to the other panel, to form a closed space However, it has a problem that a structure similar to a porous metal cannot be formed, and it has been a conventional problem to solve these problems.
[0008]
OBJECT OF THE INVENTION
The present invention has been made paying attention to the above-described conventional problems, and provides an impact energy absorbing member having the same level of impact energy absorption capability as a porous metal and having a low manufacturing cost, and a method for manufacturing the same. It is an object.
[0009]
[Means for Solving the Problems]
In the impact energy absorbing member of the present invention, the convex portions are directed to the opposite sides so as to form cavities between the multiple convex portions provided on one panel and the multiple convex portions provided on the other panel. A plurality of panel bodies formed by joining flange portions other than the convex portions are provided, and the panel bodies are sequentially stacked by shifting by an amount approximately half the size of the panel body every other layer, and adjacent to each other in the stacking direction . The flange portion other than the convex portion of one panel body is joined to the convex portion of the other panel body, and the configuration of the impact energy absorbing member is a means for solving the above-described conventional problems.
[0010]
【The invention's effect】
Since the impact energy absorbing member of the present invention has the above-described configuration, a structure similar to a porous metal can be obtained by combining panels by press molding , and panel bodies located in the same plane can be directly joined together. Therefore, it is possible to obtain a large-sized impact energy absorbing member, and therefore, it is possible to secure an amount of absorbed energy equivalent to that of a porous metal while realizing a reduction in manufacturing cost. Effect.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, if the convex portion provided on the panel has, for example, a quadrangular cross section, there is a high risk of cracking at the bottom of the punch during embossing by a press molding machine. At this time, increasing R (roundness) at the bottom of the punch can make the distortion uniform and increase the depth with respect to the size of the emboss. It is desirable to have a shape having a cross section.
[0012]
When the convex portion has a substantially semicircular cross section, if the distance between the centers of adjacent convex portions is larger than 2.5 times the diameter of the convex portion, the increase in mass becomes large, If the distance between the centers of the adjacent convex portions is too close, it becomes impossible to form the convex portion having a substantially semicircular cross section by press molding, so the distance between the centers of the adjacent convex portions is 1.5 of the diameter of the convex portion. It is necessary to make it ~ 2.5 times.
[0013]
In addition, the strain-aged steel sheet has a characteristic that the yield strength is low at the time of forming and the yield strength is increased after the heat treatment, so if the strain-aged steel sheet is used as in the present invention, it is regularly aligned. It is possible to achieve both the formability necessary for forming a convex portion, for example, a convex portion having a semicircular cross section, and the characteristics of a material having a high yield strength required for the panel after molding to a higher strength level.
[0014]
【Example】
Hereinafter, examples of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.
[0015]
1 to 4 show an embodiment of an impact energy absorbing member of the present invention. As shown in FIG. 1, the impact energy absorbing member 1 includes a plurality of panel bodies 2.
[0016]
The panel body 2 includes two panels 3 and 3 made of a steel plate having a thickness of 0.5 mm and a tensile strength of 390 MPa. In the panel 3, a large number of convex portions 3a having a substantially semicircular shape with a cross section of about 10 mm in diameter are regularly arranged with a center-to-center distance of about 20 mm. The flanges 3b, 3b other than the respective protrusions 3a are spot welded so that the respective protrusions 3a, 3a face each other in order to form a cavity 4 between the first panel 3 and the plurality of protrusions 3a in the other panel 3. The panel body 2 is formed by joining by the above.
[0017]
In this case, the convex part 3a having a substantially semicircular cross section of the panel 3 is formed by press working. However, in order to facilitate the inflow of the material at the time of press molding and to facilitate the formation of the convex part 3a. In addition, a small slit or hole may be provided around the portion where the convex portion 3a is to be disposed.
[0018]
In the impact energy absorbing member 1, the panel bodies 2 are sequentially laminated, and the adjacent panel bodies 2 and 2 are arranged so that the apexes of the convex portions 3a having a substantially semicircular cross section do not hit each other. In other words, the flange portion 3b other than the convex portion 3a of one panel body 2 and the apex of the convex portion 3a of the other panel body 2 are brought into contact with each other and joined. In this embodiment, a thermosetting adhesive is used for joining the panel bodies 2 and 2 together.
[0019]
When manufacturing the impact energy absorbing member 1 described above, first, as shown in FIG. 1A, a mold P is applied to a steel plate 3 'having a plate thickness of 0.5 mm and a tensile strength of 390 MPa. , D, and as shown in FIG. 1 (b), a panel in which a large number of convex portions 3a having a substantially semicircular cross section having a diameter of about 10 mm are regularly arranged with a center-to-center distance of about 20 mm. A plurality of 3 are formed.
[0020]
Next, after cutting the panel 3 to an appropriate size, as shown in FIG. 1C, a cavity is formed between the convex portion 3a of one panel 3 and the convex portion 3a of the other panel 3. The flanges 3b and 3b are sandwiched between the electrode chips C and C so that the convex portions 3a and 3a are opposed to each other in order to form 4, and the panels 3 and 3 are connected to each other as shown in FIG. The panel body 2 is formed by joining by spot welding.
[0021]
Next, as shown in FIG. 1 (e), the panel bodies 2 are sequentially laminated, and adjacent panel bodies 2 and 2 are arranged so that the vertices of the convex portions 3a having a substantially semicircular cross section do not touch each other. Are bonded by a thermosetting adhesive, that is, the adjacent panel body 2 with the flange 3b other than the projection 3a of one panel body 2 and the apex of the projection 3a of the other panel body 2 in contact with each other. , 2 are joined together by a thermosetting adhesive.
[0022]
Here, when manufacturing the impact energy absorbing member 1 having a size larger than that of the press dies P, D, as shown in FIG. As shown in the enlarged circle of FIG. 2, the panel bodies 2 located in the same plane are directly joined to each other without being directly joined to each other. The impact energy absorbing member 1 can be manufactured.
[0023]
In this impact energy absorbing member 1, the panel 3 is made of a steel plate having a strain aging property of 0.5 mm thickness and a tensile strength of 390 MPa. By heat treatment at 170 ° C. for 20 minutes, the plate material is cured by the strain introduced at the time of press forming and the strength is increased to about 440 MPa, so that the proof stress in the structure when a deformation load is applied can be increased. it can.
[0024]
Accordingly, when the deformation state and strength characteristics of the impact energy absorbing member 1 were examined, as shown in FIGS. 3 and 4, a large number of cavities of the panel body 2 with respect to the load L acting in the direction of the white arrow. 4 was crushed in order and the panel body 2 was sequentially deformed, and it was found that a collapse load of the same level as that of the porous metal can be obtained.
[0025]
In the impact energy absorbing member 1 described above, the panel body 2 having a large number of cavities 4 is formed by using the panel 3 formed by press molding, and the panel bodies 2 are sequentially laminated. Thus, it is possible to easily and inexpensively obtain the structure to be achieved. Therefore, it is possible to secure an amount of absorbed energy equivalent to that of the porous metal while realizing a reduction in manufacturing cost.
[0026]
Moreover, in the above-described impact energy absorbing member 1, as shown in FIG. 5, with respect to the load L in the stacking direction of the panel body 2, the deformation characteristics as shown in FIGS. 3 and 4 are exhibited. Since the flange portion 3b of the panel body 2 in each layer corresponds to the load Lh in the orthogonal direction, the collapse load in this direction is larger than the collapse load in the stacking direction of the panel body 2. That is, the impact energy absorbing member 1 has anisotropic deformation characteristics.
[0027]
In the above-described embodiment, the case where the convex portion 3a formed by pressing on the panel 3 has a substantially semicircular cross section is shown. However, the present invention is not limited to this. For example, the convex portion has a substantially semi-elliptical cross section. It does not matter if it has a shape.
[0028]
Moreover, although the case where spot welding was adopted for joining the panels 3 and 3 was shown in the above-described embodiment, it is not limited to this, and joining by adhesive or caulking as another joining means May be used.
[Brief description of the drawings]
FIGS. 1A to 1E are manufacturing process explanatory views (a) to (e) of an impact energy absorbing member according to an embodiment of the present invention. FIGS.
2 is a partial cross-sectional explanatory view showing a manufacturing procedure of an impact energy absorbing member having a size larger than that of a press mold used for manufacturing the impact energy absorbing member in FIG. 1;
FIG. 3 is a perspective explanatory view showing a deformation state when a load in the stacking direction is applied to the impact energy absorbing member in FIG. 1;
4 is a graph showing deformation characteristics of an impact energy absorbing member in the situation shown in FIG.
FIG. 5 is a cross-sectional explanatory view showing that the impact energy absorbing member in FIG. 1 has anisotropic deformation characteristics.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Impact energy absorption member 2 Panel body 3 Panel 3a Convex part 3b Flange part 4 Cavity

Claims (6)

In order to form a cavity between a large number of convex portions provided on one panel and a large number of convex portions provided on the other panel, the flange portions other than the convex portions are made to face each other on opposite sides. A plurality of panel bodies formed by joining are provided, and the panel bodies are sequentially laminated by shifting by an amount approximately half the size of the panel body every other layer, except for the convex portion of one panel body adjacent in the laminating direction . An impact energy absorbing member, wherein a flange portion and a convex portion of the other panel body are joined.   The impact energy absorbing member according to claim 1, wherein the convex portion has a substantially semicircular cross section, and the distance between the centers of adjacent convex portions is 1.5 to 2.5 times the diameter of the convex portion.   The impact energy absorbing member according to claim 1, wherein the convex portion has a substantially semi-elliptical cross section.   The impact energy absorbing member according to any one of claims 1 to 3, wherein a strain-aged plate is used as the panel material.   The impact energy absorbing member according to any one of claims 1 to 4, wherein a steel plate having strain aging is used as a panel material. In producing the impact energy absorbing member according to any one of claims 1 to 5, after forming a plurality of panels having a large number of convex portions by press working, between the convex portions of one panel and the convex portions of the other panel A panel body is formed by joining flange portions other than the respective convex portions so that the respective convex portions are opposed to each other in order to form cavities, and this panel body is formed at almost half the size of the panel body every other layer. The method of manufacturing an impact energy absorbing member comprising: sequentially laminating by shifting the dimension of the first and second panels, and joining the convex part of the other panel body to a flange part other than the convex part of one panel body adjacent in the stacking direction. .

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