JP2002225651A - Extrusion hollow section for bending - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extrusion hollow section for bending for securing the flatness of a web surface after bending without causing distorting on the web surface. SOLUTION: The aluminum alloy extrusion hollow section 1 having an approximately rectangular cross section formed by flanges 4, 5 and webs 2, 3 perpendicular to each other is joined at its web surface 2a to another member after bending. The flange 4 to be a bent outside in the process of bending, out of the flanges, has a circular arc shape extending toward the bent outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extruded hollow section made of aluminum alloy for bending.

[0002]

2. Description of the Related Art For example, hollow aluminum alloy materials used for automobile bodies such as bumper reinforcements and frame members are mainly manufactured by extruding and tempering (heat treatment) an aluminum alloy. Is done.

[0003] These aluminum alloy extruded hollow profiles
A flange (vertical wall) and a web (horizontal wall) orthogonal to each other form a substantially rectangular cross section that is uniform in the longitudinal direction of the profile (hereinafter simply referred to as a hollow profile). As for the type of the rectangular cross section, in addition to the basic mouth-shaped hollow cross-sectional shape, a cross-sectional shape such as a Japanese shape, a rice shape, an eye shape, etc. reinforced by providing a middle rib is appropriately selected depending on the application.

[0004] These hollow sections are subjected to a bending process in accordance with the shape of a member such as an automobile body to be applied. In some cases, the hollow profile after bending is joined to the surface of the other member on the web (lateral wall) surface and attached to an automobile body or the like as a bumper reinforcing material or a frame member.

[0005] For example, in the case of a bumper reinforcing material, it is attached to a vehicle body frame (vehicle members) of a frame member in the vehicle front-rear direction such as a front side member and a rear side member. In this case, the mounting of the bumper reinforcing member is performed by, as shown in FIG. 10 showing a partial cross-sectional front view of the bumper reinforcing member, the surface 2a of the web 2 of the hollow profile member 1 serving as the bumper reinforcing member. At the front end or rear end of the front or rear side member 8, the front end portions 7a and 7b of the vehicle body connecting member such as the bumper stay 7 are attached to the web surface 2a.

[0006] In FIG. 10, a hollow profile 1 constituting a bumper reinforcing material has flanges orthogonal to each other as described above.
4 (front vertical wall), 5 (rear vertical wall), and webs 2 (upper horizontal wall) and 3 (lower horizontal wall) form a nearly rectangular cross section of the shape of a uniform sun in the longitudinal direction of the profile are doing.

In many cases, the bumper reinforcing member is fixed by fastening or welding a rear flange portion 9 of the bumper stay 7 and a front flange portion 10 of the side member 8 with a mechanical fastener 11. . Although not shown,
Without going through the bumper stay 7
Alternatively, the second surface 2a may be directly attached to the front or rear end of the front or rear side member 8 of the vehicle body.

[0008] Although the case of the bumper reinforcing material has been described here, other shapes such as brackets are often attached to the web surface of the extruded shape used as the frame, such as the A pillar.

On the other hand, with the recent reduction in body weight and diversification or miniaturization of body shapes, hollow shapes have become thinner and bending radii during bending tend to be smaller.

[0010]

However, the thin hollow member is formed so that the flange is bent outside or inside.
When a bending process with a small bending radius is performed, distortion is generated particularly on the web surface, and it becomes difficult to secure the flatness of the web surface after the bending process. If the flatness of the web surface cannot be ensured, it becomes difficult to join the extruded hollow profile after bending to the surface of another member on the web surface, regardless of welding, mechanical joining or joining means such as an adhesive. The problem arises.

This problem will be described more specifically with reference to FIG. FIG. 11 shows a cross-sectional deformation state of a conventional extruded hollow profile at the time of bending (after). Now, when the hollow section 1 is bent from the direction of arrow A so that the flange 4 is bent outside and the flange 5 is bent inside, a horizontal pulling force F1 is applied to the bent outer flange 4. A horizontal compressive force F2 is applied to the bending inner flange 5. This F1 and
F2 increases as the bending radius decreases.

At this time, the bending outer flange 4 expands in the horizontal direction due to the horizontal pulling force F1, and contracts in the width direction (height direction) accordingly. In response to this deformation, the web surfaces 2a and 3a are deformed inside the profile,
Further, in response to this, bending deformation occurs in which the bending outer flange 4 also becomes concave.

On the other hand, the bending inner flange 5 also contracts in the horizontal direction and expands in the width direction (height direction) due to the compressive force F2 in the horizontal direction. However, due to the presence of a web surface holding mold normally used in bending, the bending inner flange 5 is deformed so as to absorb the amount of elongation in the width direction by being recessed inside the profile.

As a result, as shown in FIG.
In 2a and 3b, a large deformation occurs in a flat shape (shown by a dotted line) before bending. As a result, the flatness of the web surfaces 2a and 3b after bending cannot be ensured. The amount of deformation of the bending inner flange 5 is smaller than the amount of deformation of the bending outer flange 4 because it is constrained by the web surface holding mold, and the influence on the deformation of the webs 2 and 3 is small.

If the flatness of the web surface cannot be ensured, the surface 2a of the web 2 of the hollow profile member 1 as the bumper reinforcing material as shown in FIG. It is difficult to attach to the front end or rear end of the vehicle body connecting member such as the bumper stay 7 and join the web surface to the surface of another member. Further, even if joining can be performed, it is not possible to secure or guarantee the joining strength.

In order to solve this problem, methods for improving the bending conditions and the material conditions have been mainly used. Examples of the improvement method include a method of increasing the bending radius, increasing the thickness of the plate, and correcting after bending.

Of these, an increase in the bending radius leads to a change in the design of the vehicle body itself, and is often unacceptable due to the design concept of the vehicle body. Further, increasing the plate thickness leads to an increase in the weight of the vehicle body, and contrary to the above-mentioned demand for weight reduction, the advantage itself of using an aluminum alloy material is impaired. Further, the correction after the bending process complicates the process and increases the cost.

Accordingly, an object of the present invention is to provide a web surface that is thin and has a small bending radius without changing the bending processing conditions and material conditions, and without impairing the advantages of the aluminum alloy material. The present invention is intended to provide an extruded hollow section for bending, in which no distortion occurs and the flatness of the web surface after bending is ensured.

[0019]

In order to achieve this object, the gist of the extruded hollow section for bending according to claim 1 of the present invention is to form a substantially rectangular cross section by mutually orthogonal flanges and webs. An aluminum alloy extruded hollow profile that is later joined to another member on the web surface, wherein, among the flanges, a flange that becomes a bending outside during bending has an arc-shaped shape that protrudes toward the bending outside. That is.

According to the configuration of the present invention, the flange which becomes the outside of the bend at the time of the bending process projects toward the outside of the bend,
The wire length of this flange is longer than the width of the flange. For this reason, even if the flange that becomes the outside of the bend during bending (hereinafter, referred to as the outside flange) shrinks in the width direction (height direction) during bending, there is room to absorb it. When the bending outer flange is displaced toward the inside of the hollow profile, the change in the wire length can be tolerated. Furthermore,
Since the bending outer flange has a shape protruding in the bending outer direction, a load is applied that presses the bending outer end portion of the web against the holding die on the web surface, and the deformation of the web in conjunction with the deformation of the bending outer can be suppressed.

As a result, the web surface is not distorted even when it is thinned and has a small bending radius without changing the bending processing conditions and the material conditions, and without impairing the advantages of the aluminum alloy material. In addition, the flatness of the web surface after bending can be ensured. And, regardless of welding, mechanical joining or joining means such as an adhesive, it is possible to secure and guarantee the joining strength when joining the web surface to the surface of another member. Furthermore, the width of the web surface is shorter in the cross-section of the present invention when compared with a normal rectangular cross-section profile under the condition that the outer dimensions are constant. For this reason, the bending rigidity of the web is also increased, which is effective in suppressing the buckling of the web during bending. That is, compared to a normal rectangular cross section, the thickness that does not buckle the web can be set thinner,
The weight can be reduced.

In order to ensure the required length for the wire length of the bending outer flange to be deformed at the time of bending, there are provided the following.
As described in 2, the wire length S of the bending outer flange is νht / R ≦ (SB) / S (where ν; Poisson's ratio, ht; It is preferable that the radial distance to the outermost portion, R; the bending radius of the hollow shape bending neutral axis) is satisfied.

The aluminum alloy suitable for the hollow material of the present invention is, as described in claim 3, a 7000 series aging aluminum alloy according to AA to JIS standards. By using this aluminum alloy, when the wall thickness of the hollow profile of the present invention is reduced particularly to 5 mm or less, the strength such as pressure-resistant crushing characteristics required for a vehicle body member such as a bumper reinforcing material can be secured.

Further, the hollow member of the present invention is suitable for use as a bumper reinforcing material as described in claim 4.

[0025]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a hollow member according to an embodiment of the present invention. FIG. 1 is a perspective view showing one embodiment of a cross-sectional shape of the hollow profile of the present invention (however, the cross-sectional shape shows a state before bending, and the whole shape shows the meaning of the expression of a preferred embodiment of claim 2 described later). FIG. 2 is a perspective view showing a cross-sectional shape (a cross-sectional deformation state at the time of bending) of the hollow profile of the present invention of FIG. 1 after bending. .

In FIG. 1, a hollow profile 1 is composed of flanges 4 (front vertical walls) and 5 (rear vertical walls) and a web 2 (upper side) orthogonal to each other, similarly to the conventional hollow profile of FIG. (Side wall)
, 3 (lower horizontal wall) constitute a uniform, substantially rectangular cross section of the shape of the shape in the longitudinal direction of the profile. put it here,
The cross-sectional shape in the longitudinal direction of the hollow profile of the present invention is not necessarily the same, but a hollow shape in which the cross-sectional shape changes partially or sequentially can be freely selected from the design side of the vehicle body or the like.

However, the hollow profile of the present invention is different from the conventional hollow profile of FIG. 6 in that the flange 4 which is the outer side of the bend during the bending process has an arcuate shape 6 which protrudes toward the outer side of the bend. And the wire length S of the flange 4 is longer than the width B of the flange 4 by SB.

For this reason, as shown in FIG. 2, the bending outer flange 4 is moved in the width direction (height direction) according to the horizontal extension.
Even if it shrinks, the line length SB necessary for this deformation can be secured.

In other words, in the hollow profile of the present invention, the bent outer flange 4 has an arc-shaped shape 6 projecting outward from the bend by at least the length SB required for this deformation. Is preferred. In addition, it is only necessary that the bending outer flange 4 has an arc-shaped shape 6 that protrudes toward the bending outside by a length corresponding to the necessary length SB for this deformation, and it is not necessary to protrude unnecessarily long. Absent.

The required length SB for this deformation can be obtained quantitatively in relation to the bending conditions. That is, as shown in FIG. 2, the line length S of the bending outer flange is related to the flange width B by νht / R ≦ (SB) / S (where ν; Poisson's ratio,
ht; the radial distance from the bending neutral axis of the hollow profile to the outermost part of the bending, R; the bending radius of the hollow profile bending neutral shaft), the required length for deformation is ensured. You. The bending neutral axis (indicated by the dashed line in FIG. 2)
This is an axis that is set from the viewpoint of all-plastic bending and that has the same cross-sectional area of the shape material inside and outside the bend.

The arc-shaped shape 6 projecting outward from the bend may be a smooth arc as shown in FIG. 3 or a stepped arc as shown in FIGS. Shape. In short, the shape of the arc is appropriately selected according to the type of the cross-sectional shape of the hollow member of the present invention as shown in FIGS. 3, 4, and 5. 3 is a substantially hollow hollow cross-sectional shape, FIG. 4 is a substantially hollow hollow cross-sectional shape provided with one middle rib 12a, and FIG. 5 is a substantially hollow hollow shape reinforced by providing two middle ribs 12b. The cross-sectional shape is shown.

In the hollow shaped material of the present invention, the cross-sectional shape such as the approximate day shape, the approximate shape, or the unillustrated cross shape is appropriately selected according to the application. For example, in a bumper reinforcing material application, it is appropriately selected according to required characteristics such as a cross-sectional size (height) of the bumper reinforcing material by the vehicle body design and the strength or the amount of collision energy absorption. And as the bending outer flange 4 according to the cross-sectional shape of these hollow profiles,
Arc-shaped shapes such as 6a, 6b, and 6c are appropriately selected.

Since the hollow profile of the present invention has the above configuration, the deformation of the web 2 in conjunction with the deformation of the bending outer flange 4 is prevented from occurring, and the same web surface as before bending is formed.
2a flatness can be ensured. And the hollow profile 1
When the surface 2a of the web 2 is joined to the surface of another member, it is possible to secure and guarantee the joining strength. As described above, the deformation of the bending inner flange 5 does not affect or affect the deformation of the webs 2 and 3.

Further, since the hollow profile of the present invention can suppress the deformation or distortion of the web 2, in the case of a vehicle body application such as a bumper reinforcing material, in order to achieve the purpose of weight reduction which is an advantage of adopting an aluminum alloy material, It also has the effect that a thin hollow profile having a wall thickness of 5 mm or less can be obtained. The hollow profile in these thin portions is formed by deformation or distortion of the web 2.
It could not be applied to the body use. Therefore, when the wall thickness is reduced in the present invention, it is a standard for the wall thickness to be 5 mm or less.

The aluminum alloy used for the hollow profile of the present invention is a long hollow profile having a thickness of 5 mm or less. 6000 standardized to AA or JIS
Aluminum alloys are preferred. Also, among the body structural materials, a 7000 series aluminum alloy having a proof stress of 280 MPa or more is preferable as the collision member. However, since the above-described flange deformation outside the bending in the present invention is a constant displacement type deformation, it hardly depends on the strength and tensile properties of the aluminum alloy material, but mainly on only the Poisson's ratio and the r-value.

In order to ensure the required pressure-resistant crushing characteristics of the vehicle body member such as a bumper reinforcing material, an aging aluminum alloy of 7000 series according to AA or JIS is particularly preferable. By using this aluminum alloy, when the hollow profile of the present invention is reduced in thickness particularly to 5 mm or less, the strength such as the crush resistance required for a vehicle body member such as a bumper reinforcing material can be secured.

The aging treatment promotes the age hardening of the Al alloy material by the heat treatment and increases the strength of the Al alloy material (2
80 MPa or more). Aging condition (Temperature ×
The time) is appropriately selected depending on the desired strength of the Al alloy material, from the aging treatment of temperature × time at which the strength becomes the highest, to the overaging treatment performed beyond this condition.

The hollow profile of the present invention is basically composed of an extruded profile made of an aluminum alloy. The production itself of this extruded profile is appropriately produced by a usual method including casting, homogenization heat treatment, hot extrusion, tempering heat treatment and the like as main steps. The design,
Even if the cross section has a complicated shape in terms of design, it can be easily and efficiently manufactured.

(Example) A linear extruded hollow member (2.0 mm in thickness, 1300 mm in length) having the cross-sectional shape shown in FIG. Al
FEM analysis was performed on the maximum strain on the web surface 2c of the web 2 when bending a hollow alloy material (T1 treated material).

As shown in the sectional view of FIG. 6, the cross-sectional condition of the extruded hollow profile is such that the flange width B is 40 mm and the web width 2ht is 60.
mm mouth shape was used. The invention examples (1 to 3) are based on the line length S of the bending outer flange and the degree of overhang x of the bending outer flange.
(mm). For comparison, the conventional mouth shape (SB and x are 0 mm) shown in FIG. 10 was also analyzed. The results are shown in Table 1. The change in cross-sectional shape due to analysis is also shown in FIG.
(Comparative Example 4) and FIGS. 8 and 9 (Inventive Examples 2 and 3). FIG. 7
In ~ 9, the horizontal line represents the web surface, the vertical line on the right side represents the bending outer flange, and the square marks before bending (before deformation),
The circles indicate the cross-sectional shape after bending (after deformation). Also,
The horizontal axis in the drawing indicates the radial distance from the bending center, and the vertical axis indicates the flange width direction distance from the center of the flange width.

Table 1 shows each condition of the extruded hollow profile used as the analysis target, the difference SB (mm) between the wire length S of the bending outer flange and the flange width B, (SB) / S, νht / R, The relationship between νht / R and (SB) / S (provided that the Poisson ratio of ν is 0.3) and the degree of overhang x (mm) of the bending outer flange shown in FIG. 6 are also shown.

The conditions for bending the extruded hollow material are as follows:
With the center of the hollow section bending as the center, the radial distance ht from the hollow section bending neutral axis to the outermost bending section is 30 mm,
The bending radius R of the hollow hollow material bending neutral axis was set to 330 mm.

As is apparent from Table 1, Invention Examples 1 to 3 in which the wire length S of the bending outer flange is longer than the flange width B.
Has a small maximum web distortion (mm).

Further, as is clear from Table 1 and FIGS. 8 and 9, among the invention examples, the line length S of the bending outer flange is a preferable rule in relation to the flange width B and νht / R ≦ (S
-B) The hollow profiles of Invention Examples 2 and 3 satisfying / S are Invention Example 1
The maximum strain (mm) of the web is even smaller than 0.4
0 mm. Normally, the allowable strain that can be welded on the web surface is 0.5 mm or less, and Invention Examples 2 and 3 satisfy this. And, the more preferable significance of the definition of νht / R ≦ (SB) / S has been proved.

On the other hand, the hollow profile of Comparative Example 4 which is a normal rectangular hollow profile having the same wire length S of the bending outer flange as the flange width B, as shown in Table 1 and FIG.
The maximum strain amount (mm) of the web is significantly larger than that of the invention. This indicates that, when the hollow profile of Comparative Example 4 is subjected to a bending load from the lateral direction of the profile during bending, the web is deformed in conjunction with the deformation of the bending outer flange, and the web is particularly thinned and bent. If the radius is small, the distortion of the web surface increases, and the flatness of the web surface after bending cannot be secured, and it has been proved that the bonding strength of the web surface to other members cannot be secured or guaranteed.

From the above results, it can be seen that the present invention can prevent the deformation of the web linked to the deformation of the bending outer flange at the time of bending, reduce the thickness of the web, and even when the bending radius is small, the flatness of the web surface after bending. It has been proved that the bonding strength with other members on the web surface can be secured or guaranteed.

[0047]

[Table 1]

[0048]

According to the present invention, even if the thickness is reduced and the bending radius is small without changing the bending processing conditions and the material conditions, and without impairing the advantages of the aluminum alloy material,
An extruded hollow section for bending can be provided in which no distortion occurs on the web surface and the flatness of the web surface after bending is ensured. For this reason, the use of the aluminum alloy material for vehicle body members is greatly expanded, and the industrial value is great.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an extruded hollow profile for bending according to the present invention.

FIG. 2 is a perspective view showing a deformed state of the hollow section of the present invention shown in FIG. 1 during bending.

FIG. 3 is a cross-sectional view showing another embodiment of the hollow profile of the present invention.

FIG. 4 is a cross-sectional view showing another embodiment of the hollow profile of the present invention.

FIG. 5 is a sectional view showing another embodiment of the hollow profile of the present invention.

FIG. 6 is a cross-sectional view showing a cross-sectional condition of a hollow profile in an example.

FIG. 7 is an explanatory view showing a deformed state of a cross section of a conventional extruded hollow profile in an example.

FIG. 8 is an explanatory view showing a deformed state of a cross section of the extruded hollow profile of the present invention in an example.

FIG. 9 is an explanatory view showing a deformed state of a cross section of the extruded hollow profile of the present invention in an example.

FIG. 10 is a partial cross-sectional front view showing a joined state of a conventional extruded hollow profile that has been bent.

FIG. 11 is a perspective view showing a deformed state during bending of a cross section of a conventional extruded hollow profile.

[Explanation of symbols]

1: Extruded hollow profile, 2, 3: Web, 4, 5: Flange, 6: Arc-shaped flange, 7: Stay, 8: Side member, 9, 10:
Flange, 11: Fastener, 12: Middle rib,

Claims (4)

[Claims] 1. An extruded hollow aluminum alloy material having a substantially rectangular cross-section formed by a flange and a web orthogonal to each other and joined to another member on the web surface after bending, wherein the flange is formed by bending. An extruded hollow section for bending, characterized in that a flange that sometimes becomes the outside of the bend has an arcuate shape protruding toward the outside of the bend, and the wire length of the flange is longer than the width of the flange. 2. The line length S of the flange on the outside of the bending is νht / R ≦ (SB) / S (where,
2. The extrusion for bending according to claim 1, which satisfies ν; Poisson's ratio, ht; radial distance from the neutral hollow shaft to the bending outermost portion, and R: bending radius of the neutral hollow bending shaft. Hollow profiles. 3. AA to JI as the aluminum alloy
The extruded hollow section for bending according to claim 1 or 2, wherein an aging aluminum alloy of 7000 series according to S standard is used. 4. The extruded hollow section for bending according to claim 1, wherein the use of the extruded hollow section after bending is a bumper reinforcing material.