JPH10264602A - Rim for wheel and punching method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce frequency to crack by punching a hole in a hole part whose thickness is enlarged. SOLUTION: Because a seat 6 is formed to project from the inner circumferential part 5 of a drop part 3 to the inside, the length from the outer circumferential face 7 of the drop part 3 to the surface 8 of the seat 6 is larger than the thickness of a rim base material 9 in the drop part. A hole 4 is formed in the seat 6, and penetrated through the rim base material 9. Further, the seat 6 is not fitted to the inner circumferential part of the drop part 3, but it is formed so that the rim base material 9 is plastically deformed and swollen on the inner circumferential face 5. By forming the seat 6 in this way, the circumferential area of the hole 4 is enlarged, as a result, the bearing pressure applied to the hole inner circumferential face is reduced, and hence fatigue breakdown due to a crack can be prevented from generating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel rim made of a light alloy such as aluminum and the like, and more particularly to a hole for mounting a valve and a hole for fixing a bead stopper of the rim, and a method for boring.

[0002]

2. Description of the Related Art There are many cases where holes are made in an aluminum alloy material or the like. In this case, punching is performed by a press. Generally, the punch is pressed by placing the material on the punching die, but the punched surface is not a completely sheared surface but a fractured surface remains due to the clearance between the die hole and the punch. The remaining fracture surface in the hole greatly affects the strength of the entire member. That is, a crack is generated from the fractured portion, resulting in fatigue fracture.

There are known several processing methods for eliminating the fractured surface from a hole having such a fractured surface. The most common processing method is a shaving method performed after punching, and a slightly large punch is used. By press-fitting, the broken portion is scraped off. The precision punching method is also often used, in which the die hole and punch have zero clearance, and the fractured surface is punched out while the member is restrained by a plate holder with projection and a reverse holder. Does not occur.

Further, a counter die punching method is known. The opposing die punching method is a method in which a member is cut by pressing with a die having projections and then punching is performed. In this case, no fracture surface is generated. These precision punching and counter-die punching methods increase the hydrostatic pressure by locally compressing the member to be punched,
By using the ductility of the material under high hydrostatic pressure, the occurrence of fracture surface is prevented.

Although it is possible to perform punching without leaving a fractured surface in the hole formed in the member as described above,
Depending on the function required of the member, the required strength may not be satisfied even with a hole having no fractured surface. For example, a valve mounting hole formed in a wheel rim made of an aluminum alloy is one of them, and even if there is no fracture surface on the inner peripheral surface of the hole, a crack may be generated due to the applied surface pressure. In addition, the thickness of the rim is reduced as much as possible in order to reduce the weight of the rim. However, the peripheral area of the hole for mounting the bubble penetrating the thin rim base material is correspondingly reduced, and the acting surface pressure is inevitably increased.

[0006]

As described above, even if the punched hole formed in the member does not have a fractured surface, a crack may be generated by the surface pressure acting on the inner peripheral surface. If the wall thickness is reduced, the above surface pressure becomes extremely high, and the frequency of occurrence of cracks increases. The problem to be solved by the present invention is this problem, and a punching method capable of punching by making the thickness of the hole larger than the thickness of the member and a wheel rim having a hole formed by the punching method I will provide a.

[0007]

The wheel rim of the present invention is a light alloy rim having a hole for mounting a valve or a hole for fixing a bead stopper. The thickness of these holes is made larger than other portions. ing. That is, in addition to simply punching a hole for mounting a valve and a hole for fixing a bead stopper on the member surface, the hole is punched when the thickness of the hole is increased. Therefore, the peripheral area of the inner periphery of the hole increases, and the surface pressure acting on the inner surface decreases. As a result, the strength of the hole is increased.

The means for increasing the thickness of the hole is punched when the meat located in the hole to be punched is raised in advance around the hole. That is, a seat is formed around the hole, and the surface of the seat may be flat or curved depending on the mounting component.

In the above-mentioned hole processing, the member is sandwiched and compressed by a receiving die having a projection formed in the center and a wedge-shaped die. As a result, the wall thickness of the member rises around the wedge-shaped mold having a small outer diameter, and the wall thickness increases. However, the hole is not penetrated,
The upper and lower surfaces of the hole are recessed. Thereafter, the hole is punched out by the die and the shoulder punch, and at the same time, the raised portion is compressed at the shoulder of the punch to form a flat or curved seat. Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

[0010]

FIG. 1 shows a cross section of a rim for a wheel. The rim is made of an aluminum alloy having a lug 1, a bead 2, and a drop 3. Of course, there are various shapes of the rim and the present invention is not particularly limited. However, the valve mounting hole 4 penetrates the drop portion 3. FIG. 2 shows a part of a front view showing a cross section of the hole, and the wall thickness around the hole is larger than other portions.

FIG. 3 is an enlarged view of the hole, and the seat 6 is formed so as to protrude inward from the inner peripheral surface 5 of the drop part 3.
Therefore, the length t ₁ from the outer peripheral surface 7 of the drop portion 3 to the surface 8 of the seat 6 is larger than the thickness t ₂ of the rim base material 9 at the drop portion. The hole 4 is formed in this seat 6,
It penetrates the rim base material 9. As is clear from the figure,
The seat 6 is not attached to the inner peripheral surface of the drop portion 3, but is formed by plastically deforming the rim base material 9 and embossing the inner peripheral surface 5. By forming the seat 6 in this way, the hole 4
Is increased, and as a result, the surface pressure acting on the inner peripheral surface of the hole is reduced, and fatigue fracture due to cracks can be prevented.

The seat 6 is provided with a hole 4 in the drop portion 3.
Is formed in a series of steps of processing a hole, but a part of a chip punched at the time of drilling is formed as a seat. Although a specific processing method is not particularly limited, one example of the processing is shown in FIG.
It is shown in FIG. FIG. 4A shows a state before processing, in which a receiving mold 10 is arranged below the rim base material 9 and a wedge-shaped mold 11 is arranged above the rim base material 9. 9 is inserted.

The receiving die 10 has a conical projection 1 on an upper surface 12 thereof.
3, and one of the wedge-shaped molds 11 has a spherical end. The receiving mold 10 is considerably larger than the size of the hole to be punched, and the wedge-shaped mold 11 has the size of the hole. Therefore, if the wedge-shaped mold 11 is lowered, the spherical wedge 14 at the tip is stuck in the rim base material 9 and at the same time, the receiving mold 10
Of the rim base material 9 also gets into the lower side of the rim base material 9. As a result, a raised portion 15 of the meat is formed around the wedge-shaped mold on the upper surface side of the rim base material 9, and the periphery of the hole becomes thicker than the rim base material 9.

As described above, the conical projection 13 of the receiving die 10 and the spherical wedge 14 of the wedge-shaped die 11 are press-fitted into the rim base material 9 to form a conical concave portion on the lower side and a spherical concave portion on the upper side. In this state, a hole is punched out by a die 16 and a shoulder punch 17 shown in FIG. The punch 18 presses into the spherical concave portion of the swelling 15 to punch out the remaining member, and the swelling upper surface 19 compresses the swelling upper surface. If the shoulder lower surface is a flat surface, the raised upper surface also becomes a flat surface,
If it has a curved surface, it is similarly shaped as a curved surface.

Here, the shape of the protrusion formed on the upper surface of the receiving mold is not limited to a conical shape, and the tip shape of the wedge-shaped mold is not particularly limited. As described above, the wheel rim according to the present invention has a large thickness at the periphery of the hole for mounting the valve or the like in order to increase the inner peripheral area of the hole, and the following effects can be obtained. I can do it.

[0016]

According to the wheel rim of the present invention, since the peripheral portion of the hole for mounting the valve or the peripheral portion of the hole for fixing the bead stopper is in a thick state, the inner peripheral area of the hole increases, and the wheel rim acts on the hole. Surface pressure is reduced. As a result, the risk of cracking from the hole and causing fatigue failure is reduced. The processing method of the present invention for increasing the thickness of the peripheral portion of a hole is to compress a chip to be removed at the time of punching a hole before punching to form a seat in a peripheral portion at a peripheral portion, and to reduce the weight of the rim base. Even if the material is used, the strength of the hole is ensured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rim having a thicker portion around a hole.

FIG. 2 is a partial front view of a rim including a cross section of a hole.

FIG. 3 is an enlarged view showing a thick portion formed by forming a seat around a hole;

FIG. 4 is an embodiment showing a method of raising a seat before punching a hole;

FIG. 5 shows a method of punching a hole with a shoulder punch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ear part 2 Bead part 3 Drop part 4 Hole 5 Inner peripheral surface 6 Seat 7 Outer peripheral surface 8 Surface 9 Rim base material 10 Receiving die 11 Wedge-shaped die 12 Top surface 13 Conical projection 14 Spherical wedge 15 Rise 16 Die 17 Shoulder Punch 18 Punch 19 Lower shoulder

Claims (3)

[Claims] 1. A rim for a wheel made of a light alloy such as aluminum, wherein a valve mounting hole or a bead stopper fixing hole provided in the rim is made thicker than a rim base material to form a seat. A rim for a wheel, wherein the rim is provided through the hole in the seat. 2. A processing method of penetrating a hole in a member made of a light alloy such as aluminum or the like, wherein said member is sandwiched and compressed by a receiving mold having a convex portion in the center of the upper surface and a wedge-shaped mold having a narrowed tip. A ridge is formed around the wedge-shaped mold having a small outer diameter with compression, and then the above member is placed on a die, a hole is punched out with a punch with a shoulder, and the ridge is compressed by a lower surface of the shoulder to be compressed. Drilling method, characterized by forming a seat. 3. The receiving mold has a conical projection at the center thereof.
3. The drilling method according to claim 2, wherein a spherical wedge is formed at the tip of the wedge-shaped mold.