JP3233522B2 - Press bending method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press bending method for manufacturing a metal press bending product such as an engine mount bracket or an upper arm for an automobile, and more particularly, to a method in which a workpiece extrudes a metal extruded material in an extrusion direction. The present invention relates to a press bending method when formed by cutting into slices.

[0002]

2. Description of the Related Art FIG. 6 shows an upper arm (10) for a vehicle manufactured by a conventional press bending method. The upper arm (10) includes a ring-shaped mounting portion (12) having a mounting hole (11) for a vehicle body or the like, and a forked arm portion (13) protruding from an outer peripheral surface of the mounting portion (12). , A thin-walled body integrally formed with an outward U-shaped channel portion (14) provided at the tip of each arm portion (13), and a ring-shaped mounting portion (1).
2) is press-bent in the thickness direction in the shape of a letter F in side view. (15) is a bent portion.

The upper arm (10) is manufactured as follows. That is, first, as shown in FIG. 1, a work (1) to be subjected to bending is prepared. This work (1) is obtained by slicing a metal extruded profile made of aluminum (including its alloy, the same applies hereinafter) or the like to a thickness t0 in a plane perpendicular to the extrusion direction. In FIG. 1, the same reference numerals are given to the same parts as those of the upper arm (10) shown in FIG.

Next, the work (1) is cut into a pair of press bending dies (103) including an upper die (101) and a lower die (102) as shown in FIG. Both sides in the thickness direction are the pressing surfaces (101a) (102) of the upper and lower molds (101) (102).
Then, one or both of the upper and lower dies (101) and (102) are moved in the approaching direction, and the pressed surface is pressed against the work (1). Press surface (101a) of upper mold (101)
Is formed in an inverted convex shape corresponding to the desired bending shape of the upper arm (10), while the press surface (102a) of the lower mold (102) is formed in an inverted concave shape. Is formed. In addition, the distance between the opposing press surfaces (101a) and (102a) in the first gap (106) where the forked arm (13) and the channel (14) of the work (1) are fitted is not limited to the work (1).
The distance between the opposing pressing surfaces (101a) and (102a) in the second gap (105) to which the mounting portion (12) is fitted is also set to the same h0.

When the upper and lower dies (101) and (102) are moved in the approaching direction, the bent portion (15) of the upper arm (10) is moved.
When the convex portion (101b) of the press surface of the upper die (101) that forms the abutment contacts the work (1) and further presses the work (1), the work (1) receives a bending moment and the upper and lower dies Deformation follows the shape of the press surfaces (101a) and (102a) of (101) and (102). The upper and lower dies (101) and (102) are brought close to each other until the distance between the opposing press surfaces (101a) and (102a) matches the thickness t0 of the work. Then, upper and lower molds (101a)
(102a), and separate the upper arm (10) shown in FIG.
Get.

[0006]

Incidentally, since both surfaces in the thickness direction of the work are cut surfaces when the extruded material is sliced, the surface roughness is originally reduced. Specifically, while the surface roughness of the extruded material surface is about Rmax 10 to 20 μm, the surface roughness of the cut surface generally depends on the cutting method.
x is about 50 to 100 μm, and the surface roughness is reduced by cutting.

[0007] In addition to the deterioration of the surface roughness due to such cutting, in the conventional press bending method as described above, the shear deformation due to the bending causes the mounting hole (1) of the mounting portion (12) of the work (1).
1) There is a drawback that the surface roughness around the mounting hole is further deteriorated to the vicinity. In addition, there is a disadvantage that not only the surface roughness is deteriorated but also a macroscopic swelling or dent is generated by bending. Such deterioration in surface roughness results in a decrease in fatigue strength, and macroscopic swelling and dents
This makes it difficult to secure the flatness of the mounting seat surface. For this reason, the fact is that subsequent finish cutting is performed in order to improve the surface roughness and secure a flat surface, and this has caused a cost increase due to an increase in man-hours.

SUMMARY OF THE INVENTION The present invention has been made to solve such a drawback, and suppresses the deterioration of the surface roughness due to cutting and bending, the occurrence of bulges or dents on the surface, and prevents the finish cutting. It is another object of the present invention to provide a press bending method capable of securing a good surface roughness and a flat surface.

[0009]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies and as a result, have crushed a portion where deterioration of surface roughness or swelling of the surface occurs by using a mold, and crushed the portion more than other portions. It has been found that these can be suppressed by reducing the thickness, and the present invention has been completed.

That is, the press bending method according to the present invention comprises:
The work (1) is bent along the mold shape by pressing a press bending mold (5) against a cut surface of the work (1) formed by cutting the metal extruded material into a slice shape in the extrusion direction. A press bending method for forming, wherein at the time of pressing the mold (5), a part of the cut surface of the work (1) is crushed by the mold (5) to reduce the thickness. is there.

The present invention will be described below by taking as an example the case where the present invention is applied to the manufacture of an upper arm for an automobile, similarly to the prior art.

First, a work (1) to be subjected to press bending is prepared. This work (1) is the same as the conventional work and is shown in FIG. The work (1) is formed by slicing an extruded member made of aluminum or the like into a thickness t0 on a plane perpendicular to the extrusion direction, similarly to the related art.

Next, the work (1) is cut into a pair of press bending dies (5) comprising an upper die (3) and a lower die (4) as shown in FIG. Both sides in the thickness direction are sandwiched in such a manner as to face the pressing surfaces (3a) and (4a) of the upper and lower molds (3) and (4), and one or both of the upper and lower molds (3) and (4) are moved in the approaching direction. Then, the press surfaces (3a) and (4a) are pressed against the work (1).

The press surfaces (3a) and (4a) of the upper and lower dies (3) and (4) in the press bending die (5) are formed in an inverted shape so as to correspond to the desired bending shape of the upper arm as in the prior art. Although it is formed in the shape of a curved surface, there is a difference in the distance between the opposing press surfaces (3a) and (4a), unlike the related art. Specifically, the distance between the opposed pressing surfaces (3a) and (4a) in the first gap (6) where the forked arm portion (13) and the channel portion (14) of the work (1) are fitted is h0, Assuming that the distance between the opposing press surfaces (3a) and (4a) in the second gap (7) to which the mounting portion (12) of (1) is adapted is h1, h0> h1 is set.

When the upper and lower molds (3) and (4) are moved in the approaching direction, the work (1) is pressurized and follows the shape of the press surfaces (3a) and (4a) of the upper and lower molds. It transforms. Distance h between the opposing press surfaces (3a) (4a) in the first gap (6) and the second gap (7) of the upper and lower dies (3) and (4).
Since h0 and h1 are set so that h0> h1, when the upper and lower dies (3) and (4) are further approached, the opposing press surfaces in the second gap (7) are first attached to the mounting portion (1) of the work (1). 12)
Abut. When the upper and lower molds (3) and (4) are further approached, the mounting portion (12) of the work (1) is crushed by the upper and lower molds to reduce the thickness. When the upper and lower dies (3) and (4) move in the approaching direction, the opposed pressing surfaces (3a) and (4a) in the first gap (6) are moved by the forked arm (13) and the channel of the work (1). In other words, the distance h0 between the opposed pressing surfaces (3a) and (4a) in the first gap (6) of the upper and lower molds (3) and (4) is equal to the thickness of the work (1) until the workpiece (1) is brought into contact with (14). t0
It is performed until it matches. Therefore, the work mounting part (1
In the case of 2), the thickness is reduced by (h0-h1) from the original thickness t0.

As described above, by reducing the thickness by crushing the mounting portion (12), the surface of the mounting hole (11) is deteriorated due to the surface roughness deterioration and bending which have conventionally occurred due to cutting and bending. Surface swelling and the like due to this can be suppressed. The reason for this is that there is an area that does not come into contact with the die press surface due to the influence of plastic deformation around the bent part, and in that area, the surface roughness has deteriorated and the surface has swelled. It is presumed that this is due to an increase in the area in contact with the die press surface.

Thereafter, the upper and lower molds (3) and (4) are separated from each other to obtain a desired upper arm (2) as shown in FIG. In this upper arm (2), the thickness of the arm portion (13) and the channel portion (14) is t0, the thickness of the mounting portion (12) is t1 (where t0> t1), and t0-t1 =
h0-h1.

FIG. 4 shows the thickness reduction (t0-t) of the mounting portion (12).
It is a graph which shows the surface roughness of the periphery of the mounting hole (11) with respect to 1), and the change state of a flat area. In the present invention, the thickness reduction (t0-t1) of the mounting portion (12) is not particularly limited, but preferably, as can be seen from the graph of FIG. It is good to set to 0.5-0.5 mm. The thickness loss (t0-t1) is 0.05mm
If less, the effect of improving the surface roughness is poor. On the other hand, 0.5m
Even if it exceeds m, not only the effect of improving the surface roughness is saturated, but also
The disadvantage is that the amount of thinning increases and the overall shape changes. The optimal wall thickness is 0.1-0.3 mm.

In the above description, the mounting portion (12) of the work (1) is crushed and reduced in thickness in order to suppress the deterioration of the surface roughness around the mounting hole (11) and the swelling of the surface. However, the part to be reduced in thickness is not limited to this, and the point is that the part in which the surface roughness is deteriorated or swells or the like is reduced.

[0020]

[Function] When the press bending dies (3) and (4) are pressed, a part of the slice cut surface of the work (1) is crushed by the die to reduce the thickness, thereby improving the surface roughness of the reduced thickness portion. In addition, macroscopic swelling and dents are suppressed.

[0021]

EXAMPLE A work (1) for an upper arm shown in FIG. 1 was manufactured by sawing an aluminum extruded material made of A6061-T4 in a slice shape on a plane perpendicular to the extrusion direction. The length L of the work is 250 mm, the thickness t0 is 20 mm, the outer diameter D1 of the mounting portion (12) is 50 mm,
The diameter D2 of the mounting hole (11) was set to 35 mm.

On the other hand, as shown in FIG. 2, an upper mold (3) and a lower mold (4) each having a reverse-shaped press surface (3a) (4a) are provided, and a first gap (6) is formed. The difference (h0) between the distance h0 between the opposing press surfaces (3a) and (4a) in the above and the distance h1 between the opposing press surfaces (3a) and (4a) in the second gap (7).
A plurality of types of press bending dies (5) in which -h1) was set variously were prepared.

Then, between the upper and lower dies (3) and (4) of each press bending die (5), both sides in the thickness direction of the work face the pressing surfaces (3a) and (4a) of the upper and lower dies. The work (2) was arranged, and the upper and lower dies (3) and (4) were brought close to each other to perform press bending to produce the upper arm (2) shown in FIG. The press bending is performed until the opposing press surfaces (3a) and (4a) in the first gap (6) contact the upper and lower surfaces of the work (1), that is, the opposing press surfaces (3a) and (4a) in the first gap (6). The upper and lower dies (3) and (4) were brought close to each other until the distance h0 between them became equal to the thickness t0 of the work.

The thickness t1 of the mounting portion (12) of each upper arm (2) obtained above is the same as the forked arm portion (13).
And (h0-h1) than the thickness t0 of the channel portion (14).
) Has been reduced. Then, the surface roughness around the mounting hole (11) of each upper arm (2) and the degree of increase in the flat area were examined. FIG. 4 is a graph showing the relationship between the surface roughness and the degree of increase in the flat region with respect to the thickness reduction (t0-t1).

Table 1 shows specific numerical values of the surface roughness with respect to the thickness reduction (t1-t2).

[0026]

[Table 1] As can be seen from Table 1, it was confirmed that the product of the present invention in which the thickness of the mounting portion (12) was reduced had a higher surface roughness around the mounting hole (11) than the comparative product in which the thickness was not reduced. I got it. Also,
When the wall thickness is reduced to 0.2 mm, the flat area around the mounting hole (11) is expanded by 5 mm in the radial direction from the opening edge of the mounting hole (11) as compared with the case where the wall thickness is not reduced. Was secured.

[0027]

As described above, according to the present invention, a metal sheet is cut into a slice shape in the extrusion direction by pressing a press-bending die against a cut surface of a work, thereby forming a die shape. A press bending method for bending and forming a work along the work, wherein a part of a cut surface of the work is crushed by the mold to reduce the thickness at the time of pressing the mold. The roughness of the cut surface can be improved in the thinned portion, the deterioration of the surface roughness caused by bending can be suppressed, and the fatigue strength of the thinned portion can be increased. In addition, a flat area without macroscopic bulges or depressions can be enlarged, and a high-precision, high-quality press bent product can be provided.

Further, by setting the thickness reduction to 0.05 to 0.5 mm, it is possible to reliably and effectively suppress the deterioration of the surface roughness and the swelling of the surface without changing the overall shape of the press-bent product. it can.

[Brief description of the drawings]

FIG. 1A is a front view showing an example of a workpiece before press bending, and FIG. 1B is a side view of the same.

FIG. 2 is a front view showing a state where the work of FIG. 1 is press-bent according to the present invention.

FIG. 3A is a front view showing an example of a press-bent molded product to which the present invention is applied, and FIG. 3B is a perspective view of the same.

FIG. 4 is a graph showing the relationship between the thickness reduction during press bending, the surface roughness, and the flat region.

FIG. 5 is a front view showing a state where the work of FIG. 1 is press-bent by a conventional method.

FIG. 6 (a) is a front view showing an example of a press-bent molded product to which a conventional method is applied, and FIG. 6 (b) is a perspective view of the same.

[Explanation of symbols]

 1. Workpiece 2. Upper arm 5. Press bending mold

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasushi Yasushi, Sakai City, 6224, Showa Aluminum Co., Ltd. (72) Inventor Naoshi Yasuoka, 6,224 Kaiyamacho, Sakai City, Showa Aluminum Corporation ( 56) References JP-A-61-237869 (JP, A) JP-A-5-220533 (JP, A) JP-A-52-160645 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , (DB name) B21D 7/06 B21D 53/88 B21D 53/84 B21D 22/02

Claims (2)

(57) [Claims] 1. A cut surface of a workpiece (1) formed by cutting a metal extruded material into a slice shape in an extrusion direction,
A press bending method for bending a work (1) along a shape of a mold by pressing a press bending mold (5), wherein the work (1) is cut when the mold (5) is pressed. A press bending method characterized in that a part of the surface is crushed by the mold (5) to reduce the thickness. 2. The press bending method according to claim 1, wherein the thickness of the work (1) reduced by the press bending die (5) is set to 0.05 to 0.5 mm.