JP3032109B2 - Aluminum alloy car door reinforcement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing member for an aluminum alloy automobile door which is suitable as a member for reinforcing an automobile door and the like, and more particularly, to an energy absorbing member which is improved in the event of a collision. The present invention relates to a reinforcing member for an automobile door made of an aluminum alloy. In the present invention, a reinforcing member for an automobile is referred to as an automobile reinforcing member.
Means a reinforcement member for an automobile door.

[0002]

2. Description of the Related Art Recently, aluminum alloys have been used for various members of automobiles in response to the demand for lighter automobiles. For example, this aluminum alloy is also used as a door reinforcing member for protecting an occupant in an automobile side collision or the like.

FIGS. 1 (a) and 1 (b) are cross-sectional views showing a conventional automobile door reinforcing member 4, and FIG. 2 (a) is a view showing an automobile on which the reinforcing member 4 is installed. . As shown in FIG. 2 (a), the reinforcing member 4 is provided inside the automobile door with its longitudinal direction facing the traveling direction of the automobile, and includes a flange 1 parallel to the longitudinal direction for the outer side surface of the automobile door. A flange 2 for the inner side surface, which is parallel to the flange 1 and has the same width, and which connects the flange 1 and the flange 2;
And a pair of webs 3.

[0004] The reinforcing member 4 configured as described above is required to have high bending strength when an automobile collides.
On the other hand, since the reinforcing member 4 is installed inside the automobile door, its width (the length h of the web 3) is restricted by the thickness of the door as shown in FIG. 2B. That is,
The width h of the reinforcing member 4 varies depending on the type of vehicle, but is limited to the thickness of the applicable car door or less.
~ 35 mm is common. In order to reduce the weight of the automobile, it is preferable that the weight of the reinforcing member is lighter. For example, when the reinforcing member is made of an iron plate, it is about 4 kg per one for a two-door car, and an iron pipe is used. When configured, the weight is 1.5 to 2.5 kg per piece.

[0005]

In this case, when an impact force is applied from the side of the flange 1 with both ends of the reinforcing member being supported, the reinforcing member bends as shown in FIG. A compressive force acts on a portion of the flange 1 and the web 3 closer to the flange 1 than the neutral shaft, and a tensile force acts on the flange 2 and a portion of the web 3 closer to the flange 2 than the neutral shaft. In the case of an aluminum alloy reinforcing member in which the strength of the material itself is increased and the thickness of the material is reduced, particularly in order to reduce the weight, when the impact force is large, the tensile stress and the tensile strain exceed the breaking limit value of the material. As shown in FIG. 4, breakage occurs on the side where the tensile stress acts. In this case, the purpose of occupant protection cannot be sufficiently achieved. In a conventional reinforcing member, for example, 1050 kgf
If an attempt is made to obtain the above withstand load (maximum load before breaking), the reinforcing member breaks at a bending displacement of 150 to 170 mm. In order to increase the breaking displacement of a reinforcing member whose cross-sectional area and weight are restricted, it is necessary to reduce the strength of the entire material in order to increase the elongation of the material. However, when the strength of the material itself is reduced in this way, it becomes impossible to obtain a predetermined withstand load (maximum load).

The present invention has been made in view of the above problems, and has a load resistance substantially equal to the conventional one, a shock energy absorption amount equal to or more than the conventional one, and a breaking displacement of the conventional one. An object of the present invention is to provide a reinforcing member for an automobile door made of an aluminum alloy which can be significantly increased.

[0007]

An aluminum alloy automobile door reinforcing member according to the present invention has a pair of flanges and at least one web connecting them.
In an aluminum alloy automobile door reinforcing member composed of an aluminum alloy having a weight per meter in the longitudinal direction of the flange of 3 kg or less and a proof strength of 40 kgf / mm2 or more, locally baked at three or more portions in the longitudinal direction. By refining, the proof stress is reduced to 0.
It is characterized by having an annealed portion which is 85 to 0.90 times.

[0008] In this case, the number of the annealed portions is four or more in the longitudinal direction.
A region having a width of W = L / 50 or less in the longitudinal direction is provided in a region of 0.25 L or less from the end in the flange longitudinal direction, and a region having a width of 0.25 L or less from the end in the longitudinal direction. It is preferable that two or more locations be provided with a width of W = L / 100 or less in the direction.

[0009]

According to the present invention, the present inventors have found that a sufficiently high withstand load (maximum load) can be ensured, a breaking displacement can be increased and a break can be absorbed in a vehicle reinforcing member whose cross-sectional area and weight are restricted. Various experimental studies were performed to increase the amount of energy. As a result, it has been found that the main cause of the fracture is that stress and strain are concentrated near the load point of the inner flange to which a tensile force is applied.

FIG. 5 is a schematic view showing a bending test method for measuring the maximum load and the breaking displacement of the reinforcing member. The reinforcing member 16 is placed on a pair of fulcrums 14 having a distance of, for example, 950 mm.
With the compression side flange 11 receiving the load upward,
With the pull-side flange 12 down, these flanges 1
The web 13 connecting the first and the second 12 is placed with its surface vertical. At the center between the pair of fulcrums 14, a load is applied downward to the reinforcing member 16 via a punch 15 having a radius of curvature (curved surface radius) of, for example, 150 mm.
The relationship between the displacement δ and the load P at the load load point of No. 6 is measured.

When a load is applied to the reinforcing member 16 by the apparatus shown in FIG. 5, when the reinforcing member is homogeneous (when there is no local annealing portion) as shown in FIG. Thus, the reinforcing member is locally distorted along the bending radius of the punch 15.

On the other hand, as in the present invention, the reinforcing member 1
In the case where 6 has a locally annealed portion, as shown in FIG. 7, when a load is applied to the reinforcing member, gentle bending (for example, sinusoidal bending) occurs over the entire length of the reinforcing member. Therefore, the reinforcing member does not bend with a small radius of curvature along the curved surface of the punch.

FIG. 8 shows a bending load-displacement curve in the case of FIGS. In FIG. 8, a curve A represents a load when the strain is locally deformed along the bending radius of the punch as shown in FIG.
A displacement curve is shown, and a curve B shows a load-displacement curve in a case where the whole has a moderate strain state as shown in FIG. As shown in FIG. 8, the maximum load is almost the same in both cases, but the breaking displacement is much larger in the curve B.
Therefore, the curve B has much higher absorbed energy.

Therefore, in the present invention, in order to obtain a bent shape capable of avoiding local distortion concentration, a local strength-reduced portion is positively formed by annealing, and thereby, as shown in FIG. Generate a flexure shape. Note that the annealing can be performed by means such as a laser beam or an ironing iron.

The weight is 3 kg / m or less and the proof stress is 40 kg.
The f / mm ² or more is effective when the present invention is applied to such a thin high-strength material. In the case of a thick-walled material and a medium-strength material, the behavior at the time of bending is different. Because it is difficult.

The reason why the proof stress ratio is set to 0.85 to 0.90 is that if the ratio is less than 0.85, the behavior cannot be determined because the annealed portion becomes too soft. On the other hand, if the proof stress ratio exceeds 0.90, the effect of annealing cannot be obtained. Therefore, the proof stress ratio is 0.85 to 0.90.
To

The number of local annealing portions is three or more, preferably four or more in the longitudinal direction of the flange, and it is preferable that two or more local annealing portions are provided in a region exceeding 0.25 L from the end. These requirements are to create the desired ideal flexure shape when bent.

When the bending moment in the longitudinal direction of the flange is considered, since the applied bending moment is relatively small in the area of 0.25 L or less from the end, the width W can be slightly increased. Is L / 50. W
Exceeds L / 50, the annealed portion becomes too long, and it is difficult to obtain the effect.

On the other hand, the area exceeding 0.25 L from the end is a part that bears the load, and therefore the width W cannot be increased. Therefore, the width W is set to L / 100 or less.

[0020]

Next, examples of the present invention will be described in comparison with comparative examples which are outside the scope of the claims of the present invention. FIG. 9 shows a reinforcing member having the same cross-sectional shape as that shown in FIG. 1 (a). In the drawing, hatched portions indicate annealed portions. FIG.
In the embodiment, the reinforcing member A has an annealed portion at four locations, the reinforcing member B has an annealed portion at five locations, and the reinforcing member C has an annealed portion at only two locations. The reinforcing member D has an annealed portion at four places. As shown in Table 1 below, the proof stress ratio is 0.80.
And the comparative example out of the scope of the present invention, the reinforcing member E is a conventional one having no annealed portion. In addition, the material of these reinforcing members is a ductile material having an elongation of 10% or more in a tensile test using a JIS No. 5 tensile test piece.

For the reinforcing members A to E having different strengths (proof strengths) and smoothing ranges of these materials, the distance between the supporting points is 95%.
A 0 mm three-point bending test was performed to measure the maximum load and breaking displacement. Table 1 below shows the obtained bending performance, and also shows the proof stress ratio. The bending performance is a ratio when the reinforcing member E of the conventional example is set to 1.0, and the evaluation criteria are a maximum load ratio of 0.9 or more, an energy absorption ratio of 1.0 or more, and a breaking stroke ratio, respectively. Is 1.5 or more, and in the comprehensive evaluation column, when all of these characteristics are ○, ○. The proof stress ratio was σy1, the proof stress of the annealed part was σy1, the proof stress before annealing was σy0, and the ratio σy1 / σy0 was taken.

[0022]

[Table 1]

As is apparent from Table 1, the strength of the embodiment (reinforcing members A and B) of the present invention is lower than that of the comparative example E (conventional material) where no annealing is performed. 9
It is almost equal to 0 or more, and the breaking displacement is extremely large at 1.5 times or more. Therefore, the energy absorption amount is 1.1
The number has increased.

On the other hand, in Comparative Example C, the bending strength was 0.90 or more, which is sufficient because the number of the annealed portions was not appropriate at two places, but the breaking displacement was as low as 1.1. Is smaller than the conventional one (Comparative Example E). In Comparative Example D, since the proof stress ratio was not appropriate, the bending strength was as low as 0.82, and the amount of energy absorption was similarly small.

[0025]

As described above, the aluminum alloy automobile reinforcing member according to the present invention has three or more local annealing portions which are annealed in a range of an appropriate proof stress ratio. Compared to the non-reinforcing members
The maximum load is approximately equal to or more than 0.9 times, the amount of energy absorption is equal to or more, and the breaking displacement is as large as 1.5 times or more. For this reason, the reinforcing member of the present invention has a high effect of suppressing the occurrence of breakage against the impact at the time of collision.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an automobile reinforcing member.

FIG. 2A is a schematic view of an automobile showing an arrangement position of an automobile reinforcing member, and FIG. 2B is a schematic view of the inside of a door showing an arrangement position of an automobile reinforcement member.

FIG. 3 is a schematic diagram showing a stress state when an impact force is applied to a reinforcing member.

FIG. 4 is a schematic diagram showing a broken state of a reinforcing member.

FIG. 5 is a schematic view showing a bending test method for a reinforcing member.

FIG. 6 is a schematic diagram showing a state where strain is locally concentrated near a strain load point when a bending test is performed on a conventional reinforcing member.

FIG. 7 is a schematic diagram showing a state in which the reinforcing member flexes gently as a whole and has a uniform strain when a bending test is performed on the reinforcing member of the present invention.

FIG. 8 is a load-displacement curve showing a relationship between a maximum load and a bending displacement.

FIG. 9 is a diagram showing an annealed portion of the reinforcing member.

[Explanation of symbols]

 1, 2, 11, 12; flange 3, 13; web 4, reinforcing member 14, fulcrum 15, punch

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-345517 (JP, A) JP-A-5-247575 (JP, A) JP-A-5-2555751 (JP, A) JP-A-5-257575 345519 (JP, A) JP-A-4-135013 (JP, A) JP-A-5-330342 (JP, A) JP-A-5-32045 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60J 5/00

Claims (2)

(57) [Claims] 1. A pair of flanges and at least one or more webs connecting the flanges, the weight per meter in the longitudinal direction of the flange is 3 kg or less, and the proof stress is 40 kg.
In an aluminum alloy reinforcing member for an automobile door made of an aluminum alloy of f / mm ² or more, the strength is locally refined at three or more portions in the longitudinal direction to reduce the proof strength to 0.85 of the proof strength before annealing. An aluminum alloy automobile door reinforcing member having an annealed portion reduced by a factor of 0.90 to 0.90. 2. The annealing section is provided at four or more locations in the longitudinal direction. When the entire length of the flange is L, an area not more than 0.25L from an end in the longitudinal direction of the flange has W = W in the longitudinal direction. L / 50 or less, and in a region exceeding 0.25L from the end, W
2. The reinforcing member for an aluminum alloy automobile door according to claim 1, wherein the reinforcing member is provided at two or more locations with a width of L / 100 or less. 3.