JPH07155851A - Bending method - Google Patents

Abstract

PURPOSE:To provide a bending method by which the generation of wrinkles and cracks is suppressed at the time of bending a tubularly formed shape material made of Al or Al alloy and the like. CONSTITUTION:A shape material 10 (materials with deformed section or with an inner rib are included) is placed between a pressing die 3 and a bending die 5; a core 1 is inserted in the material 10; and also a wall part 12 on the bending die 5 side at an end of the material 10 is held in between a clamp side 6 that is fixed on the bending die 5 and a clamp die 7 a part of which is arranged inside the material 10. After that, the bending die 5 is rotated, and bending is performed on the material 10 along the peripheral surface of this bending die 5.

Description

Detailed Description of the Invention

[0001]

The present invention relates to Al (aluminum).
Also, the present invention relates to a bending method for bending a tubular material formed of a metal such as an Al alloy, and particularly to a bending method suitable for a case where the bending radius is small.

[0002]

2. Description of the Related Art Recently, in automobiles and buildings,
The weight reduction of various parts and members tends to be promoted. In particular, weight reduction of automobile parts and members is also important from the viewpoint of preventing global warming and destruction of the ozone layer.
Therefore, as one of the methods for reducing the weight, extruded profiles of Al or Al alloy have come to be widely used in place of the steel plates conventionally used for parts and members of automobiles and buildings. In this case, various shapes of Al or Al alloy extruded profiles are used, but, for example, extruded profile having a hollow cross section is bent by a method such as rotary drawing bending method. There is also.

FIG. 3 is a schematic view showing a conventional method for bending an extruded profile by the rotary drawing bending method. First, the extruded shape material 10 to be bent is placed between the block-shaped pressure die 3 and the cylindrical bending die 5. Then, the rod-shaped core 1 is inserted inside the extruded profile 10 and the wiper (wrinkle preventing metal) 4 is placed in contact with the surface of the extruded profile 10 on the bending die 5 side. Next, the extruded shape member 10 is sandwiched and fixed by the clamp die 2 fixed to the bending die 5 from both sides in the direction orthogonal to the central axis thereof. Next, by rotating the bending die 5, the extruded profile 10 is bend-formed along the peripheral surface of the bending die 5.

By the way, in the case of an Al or Al alloy extruded shape material, since the formability is poorer than that of steel material, wrinkles are likely to occur on the surface which is compressed during bending (the surface on the side of the bending die 5). For this reason, instead of the rod-shaped core, a swing-type core and a beads-type core that can follow the deformation of the extruded profile may be used. There is also a method of preventing the occurrence of wrinkles by arranging a reinforcing material such as a low melting point metal on the side of the wall of the extruded shape to which a compressive force is applied (Japanese Patent Laid-Open No. 5-76943).
issue).

[0005]

However, when the above-described swing-type core or beads-type core is used, it has the effect of suppressing wrinkles, but when the bending radius is small, the extruded profile is obtained. Since the tensile force is locally concentrated on the surface opposite to the surface contacting the bending die, there is a problem that cracking occurs. Also, the more complicated the core shape,
There is also a drawback that workability is reduced. Similarly, the method of arranging the reinforcing material inside the extruded shape also has the effect of preventing wrinkles, but cracks easily occur when the bending radius is small.

The present invention has been made in view of such problems, and it is possible to prevent wrinkles and cracks during bending of a profile without using a core having a complicated shape or a reinforcing material such as a low melting point metal. An object of the present invention is to provide a bending method capable of suppressing the occurrence.

[0007]

In the bending method according to the present invention, a bending member is fixed by fixing a fixing member to a part of the tubular shape member in the longitudinal direction and rotating the fixing member. In the method, the fixing member is fixed only to a wall portion of the shape member on the fixing member rotating shaft side.

In the present application, the tubular profile is a profile having a hollow inside, and also includes a profile having a middle rib (a profile having a cross section of a square or a square).

[0009]

According to the present invention, the fixing member is fixed only to the wall portion of the tubular shape member on the fixing member rotating shaft side (that is, the side receiving the compressive force during bending) and the other side (that is, during bending). The wall on the side that receives the tensile force) shall not be constrained by the fixing member. Then, in this state, the fixing member is rotated about the rotation axis to bend the profile. During this bending process, a tensile force is applied to the wall on the other side of the profile, but since there is no restraint by a fixing member on this wall, the part that receives the tensile force is gradually deformed over a wide range. , The tensile force is dispersed. This makes it possible to suppress cracking even when a tubular shaped material such as Al or Al alloy is bent with a small bending radius, and
The compressive force applied to the rotary shaft side wall is also alleviated, and the occurrence of wrinkles is suppressed.

The fixing member is, for example, the first
And a second fixing portion, and the first and second fixing portions are arranged inside and outside the extruded shape member, and the wall portion of the extruded shape member is sandwiched and fixed by both of them. can do. Further, the present invention can be applied to a shape member having a cross-sectional shape of an eye shape or a square shape, and it is possible to suppress the occurrence of cracks and wrinkles during bending of these shape members.

[0011]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is a schematic view showing a bending method according to an embodiment of the present invention. First, a block-shaped pressure die 3 and a columnar bending die 5 are used to form a shape (tubular shape) 10 to be bent.
Place between and. Then, the bending die 5 inside the shape member 10
The rod-shaped core 1 is arranged at a position aligned with. Further, the wiper 4 is placed in contact with the surface of the shape member 10 on the bending die 5 side.

Next, a part of the clamp die 7 having a U-shaped cross section is inserted into the end of the shape member 10, and the clamp die 7 is fixed to the clamp die 6 fixed to the bending die 5. The wall portion 12 of the profile 10 on the side of the bending die 5 is clamped by the clamp dies 6 and 7. In this case, the wall 11 opposite to the wall 12 is
Not restricted by clamp types 6 and 7.

Then, the bending die 5 is rotated to draw and bend the profile 10. At this time, the bending die 5
Since the wall portion (web) between the wall portion 12 on the side and the wall portion 13 on the opposite side is deformed, the tensile force applied to the wall portion 13 is relaxed, and the occurrence of cracks can be prevented, and The compressive force applied to the wall portion 12 on the bending die 5 side is also alleviated, and the generation of wrinkles is suppressed.

In this embodiment, as described above, it is possible to prevent the tensile force from locally concentrating due to the deformation of the portion (web) which is not constrained by the clamp dies 6 and 7, so that the bending radius is Even with a small bending work, it is possible to avoid the occurrence of cracks. In the method of this example, the shape of the end face of the profile is slightly deformed, but the amount of deformation is almost the same as the amount of end face cutting after normal bending and small, so there is no problem in practical use, and the yield There is no fear that it will decrease. Further, the effect of suppressing the generation of cracks and wrinkles can be further enhanced by using a lubricant together or cooling the extruded profile.

Next, according to the above-mentioned embodiment method, Al is actually
The results of examining the presence or absence of cracks and the degree of wrinkles by bending an extruded profile will be described.

First, a square pipe made of JIS6061 alloy (T6) was prepared as an extruded profile. This square pipe has a square cross section with a side of 60 mm and a wall thickness of 2.
It is 0 mm. The mechanical properties of this extruded profile are shown in Table 1 below.

This square pipe was bent by the method shown in FIG. At this time, the bending radius (inside R) is the same as in Example 1.
Is about 200 mm, and about Example 2 is about 240 mm
The bending angle was 45 ° in all cases. Further, as a comparative example, the extruded profile was bent by the method shown in FIG. The bending conditions are the same as in Example 1 for Comparative Example 1, and the same as for Example 2 for Comparative Example 2.

Then, the presence or absence of cracks and the degree of wrinkles in the bent rectangular pipes were examined by these examples and comparative examples. However, the wrinkle is the maximum wrinkle depth D shown in FIG.
Was measured. The results are summarized in Table 2 below.

[0020]

[Table 1]

[0021]

[Table 2]

As is clear from Table 2, Example 1
In No. 2, cracking did not occur and wrinkles were relatively small. On the other hand, in Comparative Example 2 in which the bending radius was 240 mm, cracks did not occur, but wrinkles larger than those in Examples 1 and 2 occurred. The bending radius is 200m
In Comparative Example 1 in which m was set, cracking occurred. From these results, it is clear that the bending radius can be made smaller than in the conventional case according to the present embodiment. That is, the bending method according to the present invention is extremely excellent as a bending method for an Al or Al alloy extruded profile.

The present invention is not limited to the bending method by the above-mentioned rotary pull bending method, but can be applied to bending methods such as press bending. Also,
INDUSTRIAL APPLICABILITY The present invention can also be applied to bending of a profile having a cross-sectional shape other than a circular shape or a rectangular shape, and further has a middle rib and a tubular shape whose cross-sectional shape is a square or a square. It can also be applied to bending of materials.

[0024]

As explained above, according to the present invention, the tubular member is bent only by fixing only the wall portion of the tubular member on the rotating shaft side of the fixing member and rotating the fixing member. Therefore, local concentration of tensile force and compressive force can be avoided, and wrinkles and cracks can be suppressed. As a result, a shape material such as Al or Al alloy can be bent with a small bending radius. Therefore, the present invention is extremely useful for reducing the weight of various parts and members.

[Brief description of drawings]

FIG. 1 is a schematic view showing a bending method according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a method for measuring wrinkle depth.

FIG. 3 is a schematic view showing a conventional method for bending an extruded profile.

[Explanation of symbols]

 1; Core 2,6,7; Clamp type 3; Pressure type 4; Wiper 5; Bending type 10; Profile

Claims (4)

[Claims] 1. In a bending method of bending a shape member by fixing a fixing member to a part of a tubular shape member in a longitudinal direction and rotating the fixing member, the fixing member comprises:
A bending method, characterized in that the fixing member is fixed only to the wall portion on the rotating member side of the fixing member. 2. The fixing member includes a first fixing portion arranged inside the shape member and a second fixing portion arranged outside the shape member.
2. The bending method according to claim 1, wherein the wall portion is sandwiched by the first and second fixing portions. 3. The bending method according to claim 1, wherein the profile is an extruded profile of aluminum or aluminum alloy. 4. The bending method according to claim 1, wherein the shape member is provided with a middle rib.