JP3845785B2 - Drilling method - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a wheel rim made of a light alloy such as aluminum, and relates to a valve mounting hole, a bead stopper fixing hole, and a drilling method for the rim.
[0002]
[Prior art]
In many cases, a hole is made in an aluminum alloy material or the like, and in this case, punching is performed by a press. In general, the punch is pushed by placing a material on a punching die, but the punched surface is not a complete sheared surface due to the clearance between the die hole and the punch, and a fracture surface remains. Thus, the fracture surface remains in the hole, which greatly affects the strength of the entire member. That is, a crack is generated from the fractured portion, resulting in fatigue failure.
[0003]
Several processing methods are known to eliminate the fractured surface from the punched hole having such a fractured surface, but the most general processing method is a shaving method performed after punching, in which a slightly large punch is press-fitted. Thus, the broken portion is scraped off. Also, the precision punching method is often used. In this precision punching method, the die hole and punch have zero clearance, and the fracture surface is cut because the member is punched in a state of being constrained by a plate press with a projection and a reverse presser. Does not occur.
[0004]
Furthermore, a counter-die punching method is known. This counter-die punching method is a method in which a member is cut by pressing with a die having a protrusion, and thereafter punching is performed, and in this case, no fracture surface is generated. The precision punching method and the counter die cutting method locally compress the member to be punched to increase the hydrostatic pressure and prevent the occurrence of a fracture surface by utilizing the ductility of the material under high hydrostatic pressure.
[0005]
In this way, the hole formed in the member can be punched without leaving a broken surface, but depending on the function required for the member, the required strength can be obtained even for a hole without a broken surface. It may not be satisfied. For example, a valve mounting hole formed in a wheel rim made of an aluminum alloy is one of them, and a crack may occur due to surface pressure acting even if there is no fracture surface on the inner peripheral surface of the hole. In addition, the thickness of the rim is reduced as much as possible in order to reduce the weight of the rim, but the peripheral area of the hole for attaching the bubble penetrating the thin rim base material is reduced accordingly, and the acting surface pressure is necessarily increased.
[0006]
[Problems to be solved by the present invention]
In this way, cracks may occur due to surface pressure acting on the inner peripheral surface even if the punched hole formed in the member does not have a fractured surface, especially if the wall thickness is reduced for weight reduction. The pressure increases significantly and the frequency of cracking increases. The problem to be solved by the present invention is this problem. A punching method capable of punching by making the thickness of the hole portion larger than the thickness of the member, and a wheel rim having a hole formed by the punching method I will provide a.
[0007]
[Means for Solving the Problems]
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, and the thickness of these holes is made larger than that of other parts. That is, the valve mounting hole and the bead stopper fixing hole are not simply punched into the member surface, but the hole is punched when the thickness of the hole is increased. Accordingly, the peripheral area of the inner periphery of the hole is increased, and the surface pressure acting on the inner surface is reduced. As a result, the strength of the hole is increased.
[0008]
By the way, the means for increasing the thickness of the hole portion is punched when the meat located in the hole to be punched is preliminarily processed around the hole. That is, a seat is formed around the hole, and the surface of the seat may be a flat surface or a curved surface depending on the mounting part.
[0009]
In the hole drilling, a member is sandwiched and compressed by a receiving mold and a wedge-shaped mold having a protrusion at the center. As a result, the thickness of the member rises around the wedge-shaped mold having a small outer diameter, and the thickness increases. However, the hole does not penetrate and the upper and lower surfaces of the hole are recessed in a concave shape. Thereafter, the hole is punched out by the die and the punch with a shoulder, and at the same time, the raised portion is compressed by the shoulder portion of the punch to form a flat surface or a curved seat. Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.
[0010]
【Example】
FIG. 1 shows a cross section of a wheel rim, and the rim is made of an aluminum alloy having an ear 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, but the valve mounting hole 4 penetrates the drop portion 3. FIG. 2 shows a part of the front view showing the cross section of the hole, but the thickness around the hole is larger than the other parts.
[0011]
FIG. 3 is an enlarged view of the hole, and a seat 6 is formed to protrude inward from the inner peripheral surface 5 of the drop portion 3. Therefore, the length t ₁ from the outer peripheral surface 7 of the drop part 3 to the surface 8 of the seat 6 is larger than the thickness t ₂ of the rim base material 9 in the drop part. The hole 4 is formed in the seat 6 and 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 raising the rim base material 9 to the inner peripheral surface 5 by plastic deformation. By forming the seat 6 in this way, the peripheral area of the hole 4 is expanded, and as a result, the surface pressure acting on the inner peripheral surface of the hole is reduced, and fatigue failure due to cracks can be prevented.
[0012]
By the way, the seat 6 is formed by a series of steps of processing the hole 4 in the drop portion 3, and a part of the chip punched during the hole processing is formed as a seat. Although a specific processing method is not particularly limited, an example of the processing is shown in FIGS. FIG. 4A shows a state before processing. A receiving mold 10 is disposed below the rim base material 9 and a wedge-shaped mold 11 is disposed above the rim base material 9. 9 is inserted.
[0013]
The receiving mold 10 has a conical protrusion 13 formed on the upper surface 12, and one wedge-shaped mold 11 has a spherical tip. 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 front end is difficult to fit into the rim base material 9, and at the same time, the conical protrusion 13 of the receiving mold 10 is also difficult to fit under the rim base material 9. As a result, a bulge 15 is formed around the wedge-shaped mold on the upper surface side of the rim base material 9, and the peripheral portion of the hole is thicker than the rim base material 9.
[0014]
In this way, the conical protrusion 13 of the receiving mold 10 and the spherical wedge 14 of the wedge-shaped mold 11 are press-fitted into the rim base material 9 to form a conical recess on the lower side and a spherical recess on the upper side, In this state, a hole is punched by the die 16 and the shoulder punch 17 shown in FIG. The punch 18 is press-fitted into the spherical recess of the bulge 15 to punch out the remaining member, and the upper surface of the bulge is compressed by the shoulder lower surface 19. If the lower surface of the shoulder is a flat surface, the raised upper surface is also a flat surface, and if it is a curved surface, it is also formed as a curved surface.
[0015]
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 of the present invention has an increased inner peripheral area of a mounting hole for a valve or the like, and the wall thickness at the periphery of the hole is increased, and the following effects can be obtained. I can do it.
[0016]
【The invention's effect】
In the wheel rim of the present invention, the peripheral part of the valve mounting hole or the peripheral part of the bead stopper fixing hole is thick, so that the inner peripheral area of the hole increases and the surface pressure acting on the hole decreases. To do. As a result, there is less risk of cracking from the hole and fatigue failure. The processing method of the present invention for increasing the thickness of the peripheral portion of the hole is to compress a chip to be removed at the time of punching before punching to process a compact seat in the peripheral portion. Even if it is a material, the strength of the hole is ensured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a rim in which a hole periphery is thick.
FIG. 2 is a partial front view of a rim including a cross section of a hole.
FIG. 3 is an enlarged view of a thick portion formed by forming a seat around the hole.
FIG. 4 shows an embodiment of a method for raising a seat before punching holes.
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 mold
11 Wedge mold
12 Top view
13 Conical protrusion
14 Spherical wedge
15 Excitement
16 die
17 Punch with shoulder
18 punches
19 Underside of shoulder

Claims (2)

  In a processing method of penetrating a hole in a light alloy member such as aluminum, the member is sandwiched between a receiving mold having a convex portion at the center of the upper surface and a wedge-shaped mold with a narrow tip, and the outer diameter is small. A bulge is formed around the wedge-shaped mold by compression, and then the above-mentioned member is placed on the die, a hole is punched out by a shoulder punch, and the above-mentioned bulge is compressed by the lower surface of the shoulder to form a predetermined seat. A drilling method characterized by that.   The drilling method according to claim 1, wherein a conical protrusion is provided at the center of the receiving mold, and a spherical wedge is formed at the tip of the wedge-shaped mold.

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