JP2010019414A - Shock absorbing member - Google Patents

Abstract

A shock absorbing member having higher shock absorption is provided.
SOLUTION: A front plate 2 and a back plate 3 which are arranged to face each other at a distance from each other, and four connecting plates 4 which are arranged between the front plate 2 and the back plate 3 and connect the two. This is an impact absorbing member 1. In the cross-sectional shape, the four connecting plates 4 are inclined with respect to the central axis passing through the center in the width direction of the front plate 2 and orthogonal to the front plate 2, the inclination directions are alternately reversed, and Two sheets are arranged symmetrically with respect to the central axis O. All of both ends of the front plate 2 and the back plate 3 have protrusions 5 extending outward from the intersections with the connecting plate 4. The distance between the inner side surface of the front plate 2 and the inner side surface of the back plate 3 is H, and the half length of the width dimension of the front plate 2 is 20 mm ≦ H ≦ 100 mm, 0.60 ≦ (H /L)≦1.40.
[Selection] Figure 1

Description

  The present invention relates to an impact absorbing member used for a vehicle bumper device or the like that requires impact absorbing performance.

  A vehicle bumper device is attached to the front or rear of the vehicle to absorb as much as possible the impact generated by the collision of the vehicle and reduce damage to the vehicle body. A bumper reinforcement that absorbs impact energy by its own deformation is applied to the vehicle bumper device as an impact absorbing member.

In general, the bumper reinforcement has a front plate on the impact side and a rear plate on the vehicle body side facing each other in a substantially parallel manner at a distance from each other, and connects the front plate and the rear plate. The cross section mainly has a “day” shape or an “eye” shape.
When an impact is applied to the front plate, the load is transferred from the front plate to the connection plate and then to the back plate, and the connection plate buckles as the load increases, thereby mitigating the impact applied to the vehicle body.

In recent years, the above-mentioned bumper reinforcement has been used as an extruded material of an aluminum alloy material from the viewpoint of reducing the weight of the vehicle.
Moreover, about the bumper reinforcement, the technique which improves a shock absorptivity is reported (patent documents 1-3).
However, further improvement in impact absorption and weight reduction are required.

JP 2005-59766 A JP 2006-7828 A Japanese Patent No. 4004924

  This invention is made | formed in view of this conventional problem, Comprising: It aims at providing the impact-absorbing member which has higher impact absorptivity.

The present invention provides an impact absorbing system comprising a front plate and a back plate arranged to face each other at a distance from each other, and four connecting plates that are arranged between the front plate and the back plate and connect the two. A member,
In the cross-sectional shape, the four connecting plates are inclined with respect to a central axis that passes through a center point in the width direction of the front plate and is orthogonal to the front plate, the inclination directions are alternately reversed, and Two pieces are arranged symmetrically with respect to the central axis,
All of both ends of the front plate and the back plate have protrusions extending outward from the intersections with the connecting plate,
A distance H between the inner surface of the front plate and the inner surface of the back plate;
The length L, which is half the width dimension of the front plate,
20 mm ≦ H ≦ 100 mm,
The shock absorbing member has a relationship of 0.60 ≦ (H / L) ≦ 1.40 (claim 1).

  As described above, the four connecting plates of the shock absorbing member of the present invention have a cross-sectional shape (hereinafter, the description will be omitted as appropriate) and pass through the center point in the width direction of the front plate. Are inclined with respect to a central axis perpendicular to the axis. Therefore, the impact energy absorbability can be improved.

In addition, excellent buckling strength and rigidity can be obtained by alternately reversing the inclination direction of the connecting plate and arranging them in line symmetry two by two with respect to the central axis.
Furthermore, the buckling strength and rigidity of the shock absorbing member are improved by forming protrusions on both ends of the front plate and the back plate that extend outward from the intersections with the connecting plate. be able to.

In particular, in the present invention, the distance H between the inner surface of the front plate and the inner surface of the back plate and the length L that is half the width dimension of the front plate are 0.60 ≦ (H / L) ≦ 1.40. This relationship is an optimum value supported by experiments, and by maintaining this relationship, the buckling form of the connecting plate becomes almost symmetrical in the width direction within the practical width dimension range, and shock absorption. Performance can be increased.
When the H / L is less than 0.60, the dimension in the thickness direction is too small compared to the width dimension, and in a practical width dimension range, it is possible to secure a deformation amount sufficient to absorb the impact. It becomes difficult. On the other hand, when the H / L exceeds 1.40, the connecting plate does not buckle symmetrically in the width direction, and tends to buckle in one direction in the width direction, so that the shock absorption becomes worse.

Further, the above H is preferably in the range of 20 mm ≦ H ≦ 100 mm.
When the H is less than 20 mm, the length of the connecting plate is shortened, and it becomes difficult to secure a deformation amount enough to absorb the impact. On the other hand, when the H exceeds 100 mm, the length of the connecting plate becomes long, and the connecting plate does not buckle symmetrically in the width direction, and a buckling form biased to one side in the width direction is likely to occur, and shock absorption The absolute value of the amount (withstand load) becomes low.
Therefore, in the present invention, it is an essential requirement to satisfy the relationship of 20 mm ≦ H ≦ 100 mm and 0.60 ≦ (H / L) ≦ 1.40.

  As described above, since the shock absorbing member is excellent in shock absorbing property, even if the outer dimensions are reduced, the shock absorbing member can have performance equivalent to that of a general shock absorbing member having a “cross-section” shape. Moreover, even if it is the same magnitude | size, even if it thins wall thickness, the performance equivalent to a general cross-section "eye-shaped" impact-absorbing member can be obtained. That is, weight reduction can be achieved by reducing the thickness and size of the shock absorbing member.

  As described above, according to the present invention, it is possible to provide an impact absorbing member having higher impact absorbability.

Sectional drawing which shows the impact-absorbing member in Example 1. FIG. FIG. 3 is an explanatory view showing an impact absorbing member in Example 1. Sectional drawing which shows the impact-absorbing member in the comparative example 1. FIG. Explanatory drawing which shows the method of the 3 point | piece bending test in Experimental example 1. FIG. Explanatory drawing which shows the result of the 3 point | piece bending test in Experimental example 1. FIG. Explanatory drawing which shows the structure of the press apparatus used for the compression test in Example 2. FIG. Explanatory drawing which shows the appropriate buckling form in Example 2. FIG. Explanatory drawing which shows the inappropriate buckling form in Example 2. FIG. FIG. 6 is a load / displacement diagram of the test material E22 of Example and its comparative conventional material CE22 in Example 2. The load / displacement diagram of the test material C21 of the comparative example and its comparative conventional material CC21 in Example 2. FIG. The load / displacement diagram of the test material C22 of the comparative example and its comparative conventional material CC22 in Example 2. FIG.

As described above, the shock absorbing member of the present invention is disposed between the front plate and the back plate, which are arranged to face each other at a distance from each other in a substantially parallel manner, and between the front plate and the back plate. It is an impact-absorbing member comprising a single connecting plate.
The front plate, the back plate, and the connecting plate constituting the shock absorbing member may be made of any material such as a metal material such as an aluminum alloy, an iron alloy, and a magnesium alloy, or a resin material. .
Among these, from the viewpoint of weight reduction, the front plate, the back plate, and the connecting plate are preferably made of an aluminum alloy. Further, among aluminum alloys, it is particularly preferable to be made of an aluminum alloy such as 6000 series or 7000 series excellent in strength characteristics.
Moreover, although it is preferable to obtain the said impact-absorbing member by extrusion molding, you may produce it using other processing methods, such as welding, casting, forging.

Further, the four connecting plates are inclined with respect to a central axis that passes through a central point in the width direction of the front plate and is orthogonal to the front plate, the inclination directions are alternately reversed, and with respect to the central axis. Two pieces are arranged in line symmetry.
In other words, if the four connecting plates are a first connecting plate to a fourth connecting plate in order from one end connecting plate, the inclination directions of the first connecting plate and the third connecting plate are the same, and The inclination directions of the second connecting plate and the fourth connecting plate are the same.
Further, the first connecting plate and the fourth connecting plate are arranged symmetrically with respect to the central axis, and the inclination directions are opposite but the inclination angles are the same. In addition, the second connecting plate and the third connecting plate are arranged symmetrically with respect to the central axis in the cross-sectional shape, and the inclination directions are opposite but the inclination angles are the same.

  Further, the shock absorbing member is formed in a trapezoidal shape by the first connecting plate, the front plate, the second connecting plate, and the back plate in the cross section, and the side of the front plate constituting the trapezoid is the above It is preferable to arrange the connecting plate so as to be longer than the side of the back plate.

The shock absorbing member has an intersection point between the center line in the thickness direction of the inner connecting plate, which is the connecting plate arranged at a position close to the central axis, and the extension line of the inner side surface of the front plate at the point A1, Let the intersection point with the extension line of the inner surface of the back plate be A2 point,
The intersection point between the center line in the thickness direction of the outer connecting plate, which is the connecting plate located far from the central axis, and the extension line of the inner surface of the front plate is B1 point, and the inner surface of the rear plate is If the intersection point with the extension line is point B2,
The distances from the central axis to the points A1, A2, B1, and B2 are preferably in the following relationship with respect to H and L (Claim 2).
A1 point: -0.11H + 0.34L
A2 point: 0.11H + 0.34L
B1 point: 0.025H + 0.755L
B2 point: -0.025H + 0.755L

The distances from the central axis to the intersections (A1, A2, B1, B2) are optimum values derived from experiments by locating the connecting plates that make the propagation of the input load from the collision surface more efficient.
Therefore, in this case, it is possible to obtain an effect that particularly good shock absorption can be obtained.
In addition, in the case of an extruded material, the allowable range of the distance from the central axis to each of the intersections described above is within the tolerance (normal grade) of the cross-sectional dimension of JIS H4100.

The L is preferably in the range of 10 mm ≦ L ≦ 200 mm.
In this case, it can be applied everywhere as a shock absorbing member for a vehicle. For example, the present invention can be applied not only to door impact bars, bumper reinforcements, and the like, but also to truck tilts.

  When the L is less than 10 mm, processing such as extrusion of a high-strength aluminum alloy may be difficult. On the other hand, when the L exceeds 200 mm, there is a risk of exceeding the manufacturable range such as extrusion processing, and even if it can be obtained by welding after processing, it is disadvantageous in terms of cost. Therefore, the range of 20 mm ≦ L ≦ 125 mm is more preferable.

The thickness t of the front plate, the back plate, and the connecting plate is preferably 1 mm ≦ t ≦ 6 mm.
The impact absorbing member can obtain sufficient strength even when the front plate, the back plate, and the connecting plate have a thickness of 1 mm to 6 mm.

When the thickness t is less than 1 mm, the extrudability is poor and it is difficult to produce a product. On the other hand, when the thickness t exceeds 6 mm, the weight of the shock absorbing member increases, and there is a possibility that the weight reduction that is the effect of the present invention is not achieved. Therefore, the range of 1 mm ≦ t ≦ 3 mm is more preferable.
Moreover, although the thickness of the said front board, the said back board, and the said connection board may be all equal, they may differ, respectively.

The impact absorbing member is preferably for a bumper reinforcement incorporated in a vehicle bumper device.
Even when the impact absorbing member is made of an aluminum alloy, the impact absorbing member can have a sufficient strength, and therefore can be suitably used for a vehicle bumper device that is required to be reduced in weight.

Example 1
In this example, an impact absorbing member according to an embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the impact absorbing member 1 of the present example includes a front plate 2 and a back plate 3 that are arranged to face each other at a distance from each other, and between the front plate 2 and the back plate 3. It consists of four connecting plates 4 that are arranged and connect the two. In the cross-sectional shape, the four connecting plates 4 are inclined with respect to the central axis O passing through the center point in the width direction of the front plate 2 and orthogonal to the front plate 2, and the inclination directions are alternately arranged. Inverted and arranged in line symmetry two by two with respect to the central axis O. Further, both ends of the front plate 2 and the back plate 3 have protrusions 5 that extend outward from the intersections with the connecting plate 4. Then, as shown in FIG. 2, the shock absorbing member 1 is manufactured as a long material whose longitudinal direction is a direction orthogonal to the paper surface of FIG.

Specifically, the front plate 2, the back plate 3, and the connecting plate 4 are made of an aluminum alloy (material, quality: 6N01-T5, yield strength: 220 MPa).
Moreover, the thickness t of the said front board 2, the said back board 3, and the said connection board 4 is 2 mm.

And the intersection of the center line of the thickness direction of the inner side connection board 41 which is the above-mentioned connection board 4 distribute | arranged to the position close | similar to the said center axis | shaft O, and the extension line | wire of the inner surface of the said front board 2 is point A1, The point of intersection with the extension line of the inner surface of the back plate 3 was designated as A2.
The distance a1 from the central axis O to the point A1 was 13.8 mm. The distance a2 from the central axis O to the point A2 was 27.0 mm.

Further, the intersection point between the center line in the thickness direction of the outer connecting plate 42, which is the connecting plate 4 arranged at a position far from the central axis O, and the extension line of the inner side surface of the front plate 2 is the B1 point, The intersection point with the extension line of the inner surface of the back plate 3 was designated as B2.
The distance b1 from the central axis O to the point B1 was 46.8 mm. Further, the distance b2 from the central axis O to the point B2 was 43.8 mm.

The distance H between the inner surface of the front plate 2 and the inner surface of the back plate 3 is 60 mm. The length L, which is half the width dimension of the front plate 2, is 60 mm. That is, (H / L) = 1.00.
The distances from the central axis O to the points A1, A2, B1, and B2 are as follows in relation to H and L.
A1 point: -0.11H + 0.34L,
A2 point: 0.11H + 0.34L,
B1 point: 0.025H + 0.755L,
B2 point: -0.025H + 0.755L.

(Comparative Example 1)
In this example, as a comparison with the present invention, a general impact absorbing member 9 shown in FIG. 3 was prepared.
As shown in FIG. 3, the shock absorbing member 9 of this example connects the front plate 91 and the back plate 92 facing each other substantially in parallel with a distance from each other, and connects the front plate 91 and the back plate 92 4. It is composed of a plurality of connecting plates 93 and has a cross section of “eye” shape.

Specifically, the front plate 91, the back plate 92, and the connecting plate 93 are made of an aluminum alloy (material, quality: 6N01-T5, yield strength: 220 MPa).
The thickness t ′ of the front plate 91, the back plate 92, and the connecting plate 93 is 2 mm.

The distance H ′ between the inner side surface of the front plate 91 and the inner side surface of the back plate 92 is 60 mm. The length L ′ of the width dimension of the front plate 91 is 120 mm.
The center line of the connecting plate disposed at a position close to the central axis O ′ passing through the central point in the width direction of the front plate 91 and orthogonal to the front plate 91, and the extension line of the inner surface of the back plate 92 The point of intersection with was designated P point.
The distance p from the central axis O ′ to the point P was 25 mm.

(Experimental example 1)
In this example, the impact absorbing member 1 of Example 1 and the impact absorbing member 9 of Comparative Example 1 were subjected to a load test and evaluated for impact absorbability. This will be described with reference to FIGS.

First, as shown in FIG. 4, the shock absorbing member 1 (9) is arranged with the front plate 2 (91) on the outer side and the rear plate 3 (92) on the inner side and bent to the inner R = 3000 mm along the longitudinal direction. Was supported with a span S = 800 mm using a support base 6 (width = 200 mm), and a test was performed in which a load F was applied to the outer R side (front plate 2 side) via a flat plate 7.
The load was continuously measured with a load cell of a testing machine.
A displacement meter was attached to the point Q on the R side in the center of the span, and the displacement was continuously measured.

  The results are shown in a load / displacement diagram in FIG. In FIG. 5, the vertical axis represents load (N: Newton) and the horizontal axis represents displacement (mm). In FIG. 5, the solid line X shows the result of the shock absorbing member of Example 1, and the broken line Y shows the result of the shock absorbing member of Comparative Example 1.

As can be seen from FIG. 5, the impact absorbing member of Example 1 can reduce the displacement under the same load as compared with the impact absorbing member of Comparative Example 1. On the other hand, the same displacement can withstand high loads. That is, the shock absorbing member of Example 1 is superior in shock absorbing property to the shock absorbing member of Comparative Example 1.
Therefore, when the configuration of the present invention is applied, the weight can be reduced by reducing the thickness or reducing the size when a performance equivalent to that of a general shock-absorbing member having a “cross-section” shape is to be secured. Further, when the structure of the present invention is applied with the same size and thickness as a general shock-absorbing member having a “cross-section” shape, it can have higher shock absorption.
Thus, according to this invention, it turns out that the impact-absorbing member which has higher impact-absorbing property can be provided.

(Example 2)
In this example, with respect to an impact absorbing member having the same cross-sectional shape as in Example 1, a test material in which the values of the distance H and the length L are changed is produced, a compression test is performed, and the buckling is performed. The form and energy absorption ratio were measured and evaluated.
The prepared test materials are three types of test materials E21 to E23 as examples of the present invention and two types of test materials C21 and C22 as comparative examples. These test materials have the same material, quality, and proof stress. The material is 6N01, the quality is T5, and the proof strength is 220 MPa. These dimensional relationships are shown in Table 1. The length of each test material (the length in the depth direction of the cross section) was 20 mm.

  The compression test was performed using a press apparatus 8 as shown in FIG. As shown in the figure, the pressing device 8 is configured such that an elevating part 82 is raised and lowered with respect to the mounting table 81, and a load generated between the two can be measured by a load cell (not shown). In this example, as shown in the figure, a compression test was performed in which the impact absorbing member 1 was sandwiched between the mounting table 81 and the elevating part 82 and the both were gradually compressed.

The evaluation method was as follows.
<Buckling form>
As shown in FIG. 7, the buckling form is a generated buckling form, that is, a deformed form of the connecting plate is an axis of symmetry in the L direction (a center passing through a center point in the width direction of the front plate 2 and perpendicular to the front plate 2. The case where the axis O) is almost symmetric is determined as appropriate (◯). As shown in FIG. 8, the generated buckling form is not symmetrical with respect to the symmetry axis in the L direction (the central axis O that passes through the center in the width direction of the front plate 2 and is orthogonal to the front plate 2) and is biased to one side. The case of asymmetry was regarded as inappropriate (×).

<Energy absorption ratio>
In order to evaluate the energy absorption performance, the amount of energy absorption (N · m) was determined from the load / displacement diagrams obtained for the test materials of Examples and Comparative Examples.
For comparison, the same size as each test material, that is, the dimension of t ′ of the “eye” -shaped shock absorbing member shown in FIG. 3 described above is the same as t, and the dimension of H ′ is the same as H. In addition, the amount of energy absorption was also obtained from the load / displacement diagram for a sample in which the dimension of L ′ was set to twice that of L (hereinafter referred to as “comparative conventional material”).

  As representative examples, the test material E22 of the example and its comparative conventional material, the test material C21 of the comparative example and its comparative conventional material, and the test material C22 of the comparative example and its comparative conventional material are shown in FIGS. -A displacement diagram is shown. In these figures, the horizontal axis represents displacement (mm) and the vertical axis represents load (kN, 20 mm width). In FIG. 9, the comparative conventional material of the test material E22 is denoted by reference numeral CE22, in FIG. 10, the comparative conventional material of the test material C21 is denoted by reference numeral CC21, and in FIG. 11, the comparative conventional material of the test material C22 is denoted by reference numeral CC22. .

The evaluation results are shown in Table 1. The energy absorption amount (N · m) is a value up to a stroke (displacement amount) of 1 mm.
As can be seen from Table 1, all of the test materials E21 to E23 of the examples in which H / L is within the scope of the present invention are symmetric with respect to the symmetry axis in the L direction (see FIG. 7), and It was found that the material has better energy absorption performance than the comparative conventional material.
On the other hand, although the test material C21 of the comparative example showed a substantially buckling shape with respect to the symmetry axis in the L direction, H / L = 0.50 and deviated from the lower limit. In comparison, there was no significant difference in the load / displacement diagram, and a sufficient improvement in energy absorption performance could not be obtained.

Further, the test material C22 of the comparative example has H / L = 1.50, which is outside the upper limit, and H is too large with respect to L, so that the buckling form is asymmetric with respect to the symmetry axis in the L direction (FIG. 8). Reference). Since such an asymmetric buckling form was easily generated, the absolute value of the energy absorption amount (withstand load) was lowered, and sufficient energy absorption performance could not be obtained. However, the comparative conventional material also had a low absolute value of load resistance, and as a result, the energy absorption ratio was an appropriate value due to the shape effect.
Comprehensive evaluation is that the buckling form is appropriate (○), the absolute value of load resistance is relatively high, and the energy absorption ratio is appropriate (○), so that a sufficient improvement effect can be obtained over the conventional shape. That is, both the buckling form and the energy absorption amount ratio must be appropriate.

(Example 3)
In this example, in order to complement the results of Example 2, on the premise that H is in the range of 20 to 100 mm, samples 31 to 41 in which the values of L and H are changed are prepared. The same compression test was conducted. And the energy absorption amount and energy absorption amount ratio were measured similarly to Example 2. FIG. The results are shown in Table 2. The energy absorption was evaluated as 14 N · m or more as acceptable (◯) and less than it as unacceptable (×).

  As can be seen from the results in Table 2, when the value of H / L is less than 0.60, the energy absorption ratio may be less than 1.05, and a sufficient improvement effect of energy absorption performance is obtained. There wasn't. Furthermore, when the value of H / L exceeded 1.40, the absolute value (load resistance) of the energy absorption amount was not sufficiently obtained.

1 Shock absorbing member 2 Front plate 3 Back plate 4 Connecting plate

Claims (5)

An impact-absorbing member comprising a front plate and a back plate arranged to face each other at a distance from each other, and four connecting plates that are arranged between the front plate and the back plate and connect the two. ,
In the cross-sectional shape, the four connecting plates are inclined with respect to a central axis that passes through a center point in the width direction of the front plate and is orthogonal to the front plate, the inclination directions are alternately reversed, and Two pieces are arranged symmetrically with respect to the central axis,
All of both ends of the front plate and the back plate have protrusions extending outward from the intersections with the connecting plate,
A distance H between the inner surface of the front plate and the inner surface of the back plate;
The length L, which is half the width dimension of the front plate,
20 mm ≦ H ≦ 100 mm,
An impact absorbing member having a relationship of 0.60 ≦ (H / L) ≦ 1.40. The intersection of the center line in the thickness direction of the inner connecting plate, which is the connecting plate disposed at a position close to the central axis, and the extension line of the inner side surface of the front plate is defined as the point A1 in claim 1, Let the intersection point with the extension line of the inner surface of the face plate be A2 point,
The intersection point between the center line in the thickness direction of the outer connecting plate, which is the connecting plate located far from the central axis, and the extension line of the inner surface of the front plate is B1 point, and the inner surface of the rear plate is If the intersection point with the extension line is point B2,
The impact absorbing member, wherein the distances from the central axis to the points A1, A2, B1, and B2 are in the following relationship with respect to H and L.
A1 point: -0.11H + 0.34L
A2 point: 0.11H + 0.34L
B1 point: 0.025H + 0.755L
B2 point: -0.025H + 0.755L   3. The impact absorbing member according to claim 1, wherein a thickness t of the front plate, the back plate, and the connecting plate is 1 mm ≦ t ≦ 6 mm.   The shock absorbing member according to any one of claims 1 to 3, wherein the front plate, the back plate, and the connecting plate are made of an aluminum alloy.   5. The impact absorbing member according to claim 1, wherein the impact absorbing member is for a bumper reinforcement incorporated in a vehicle bumper device.

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