JP2000280702A - Hollow casting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To install a strut in the hollow part of a casting in a satisfactory formability. SOLUTION: An interval between both symmetrical sidewalls 5 constituting the hollow part of a hollow hub in a cast wheel 1 and being opposed to each other is connected together with a tubular strut 8 and constant in wall thickness, controlling each resonance in these sidewalls 5 and in the hollow part and thereby reducing the extent of noise. When casting the wheel, this strut 8 is set up in a cavity so as to be concentric with an axle in a state that it is preset in a core for forming the hollow part and then cast therein whereby it is residually integrated in the hub. Therefore, since the strut 8 gets off without being forming with the core, there is no need to consider any castability to the core and its aligning accuracy, so that formability is improved, and since it is formable into the constant wall thickness at the minimum diameter, the whole lighteningness is thus realizable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow cast structure suitable for a casting wheel, a casting swing arm, and the like of a motorcycle.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 5-85101 discloses a hollow wheel in which a hub and spokes are hollow and integrally cast. A cylindrical portion for penetrating the axle is integrally formed between opposing wall portions constituting a hub of the wheel. The cylindrical portion serves as a support between the opposing wall portions, and is formed by a protruding portion projecting from the left and right dies and a core surrounding the periphery when casting the wheel.

[0003]

In the case where a cylindrical pillar is integrally cast into a hollow portion by a core as in the above-mentioned conventional example, the design must be made in consideration of casting properties and alignment accuracy of the core. Must. That is, it is required that the minimum diameter of the column is equal to or greater than a certain limit, and the thickness must be changed in a tapered shape because a draft angle is required,
That makes the product weight heavier. In addition, when a hollow article is used as a vehicle member, it has been desired to suppress generation of resonance and resonance noise due to resonance of a wall surrounding the hollow part and resonance of the hollow part. The present invention fulfills such a demand.

[0004]

Means for Solving the Problems In order to solve the above problems, a first invention according to the present invention of the present invention relates to a hollow cast structure, wherein a hollow box-shaped portion is integrally formed by casting. A strut for connecting the surrounding wall portions facing each other is disposed on the core at the time of casting and is cast, so that it is left in a state of crossing the hollow portion.

A second invention is characterized in that, in the first invention, the hollow box-shaped portion is a hub of a vehicle wheel, and the support is a cylindrical member having the same center as the axle center.

A third invention is characterized in that, in the first invention, the hollow box-shaped portion is a cross member portion provided at a front portion of a swing arm constituting a rear wheel suspension device for a motorcycle. I do.

[0007]

According to the first aspect of the present invention, when casting the hollow box-shaped portion, the pillars are arranged on the core in advance and cast, so that the pillars cross the hollow portion and surround the hollow portion. It was left in the hollow structure as it was while connecting the opposing walls. As a result, since it is not necessary to form the pillar with the core, it is not necessary to consider the casting ability and the alignment accuracy of the core, so that the formability is improved and the cost can be reduced.

In addition, by connecting the opposing walls surrounding the hollow portion with the support columns, the generation of resonance noise on these walls is prevented, and the generation of resonance noise in the hollow portion is suppressed, so that the weight increases significantly. Resonance of the hollow body without inducing
The generation of resonance noise can be effectively reduced.

According to the second aspect of the present invention, the hollow cast body structure is applied to a hub of a casting wheel, and the column is a cylindrical member having the same center as the center of the axle. It can be formed, and by connecting the opposite left and right wall surfaces of the hub with columns, it is possible to reduce resonance and resonance noise during traveling. In addition, the pillar can be configured with a minimum necessary minimum diameter even though the pillar is cylindrical, and the thickness of the pillar can be made constant without the necessity of a draft angle, so that significant weight reduction can be realized.

According to the third aspect of the invention, the hollow cast member structure is applied to the cross member of the swing arm, so that resonance and resonance noise during traveling in the hollow cross member can be reduced. There is no need to provide a vibration structure or increase the thickness of the entire structure, so that the structure is simple and the overall weight can be made relatively light as compared with the magnitude of the noise reduction effect to be obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS.
1 shows a first embodiment applied to a cast wheel of a wheeled vehicle. FIG.
FIG. 1 is a sectional view taken along line 1-1 of FIG. 2, and FIG. 2 shows an overall appearance of the casting wheel. FIG. 3 shows a mold structure for forming the cast wheel.

First, as shown in FIG. 2, the casting wheel 1 is obtained by integrally casting a hub 2, a spoke 3 and a rim 4 by using an appropriate light alloy such as an aluminum alloy. In the center of the side wall 5 of the hub 2, an axle hole 6 is opened, and a bearing recess 7 is formed so as to surround the axle hole 6.

As is apparent from FIG. 1, the hub 2 is hollow, and side walls 5 surrounding the hollow space are formed to face left and right, and the left and right side walls 5 are connected by a support post 8. . Both ends of the support column 8 are cast and fixed to the left and right side walls 5, respectively.

The support column 8 is a cylindrical body having a minimum necessary diameter so as to form the passage space 9 for the axle. The support column 8 is formed separately from the hub 2 in advance using an appropriate material such as an aluminum alloy. The diameter is constant in the direction and the wall thickness is also constant.

To manufacture the casting wheel 1, FIG.
As shown in the figure, the cavities 13 are formed by the left and right split dies 10, 11 and the outer
Is formed, and the column 8 is arranged in the cavity 13.

This support 8 is provided with another core 1 sandwiching the inside and outside thereof.
4 and 15 are arranged in advance in the cavity 13 together with the cores 14 and 15 such that the center axis of the column 8 and the center axis of the axle (not shown) coincide with each other.
The left and right dies 10 and 11 are fixed by protrusions 16 and 17 formed at the portions corresponding to the axle holes 6 respectively.

In this state, the molten metal is poured into the cavity 13 and solidified by cooling.
When the cores 2 and 15 are opened and the cores 14 and 15 are ejected, the columns 8 remain in the hub 2 and the left and right side walls 5 opposing both ends in the axial direction.
Wheel 1 integrated in a fixed state by being cast between
Is obtained.

In this way, since the column 8 is arranged on the core at the time of manufacture and remains in the product, the column 8 can have the minimum necessary diameter and there is no need to consider the draft angle. . Therefore, manufacturing becomes easy, cost can be reduced, and the overall weight can be reduced.

In addition, since the side walls 5 opposed to the hollow portion are connected by the columns 8, the resonance of the side walls 5 during traveling is suppressed, and the resonance in the hollow portion facing the side walls 5 is suppressed. Although 2 is a hollow body, resonance / resonance noise can be reduced.

FIGS. 4 and 5 show a second embodiment applied to a swing arm. FIG. 4 shows a plan view of the entire swing arm constituting a rear wheel suspension system of a motorcycle.
Shows a sectional view taken along line 5-5.

First, in FIG.
0 has a pair of left and right fork arms 21 and 22 that support the rear wheel at the rear end, and a cross member 23 that connects between the front portions thereof.
Further, a pair of bearing portions 24 and 25 are formed to protrude forward. The front portions of the fork arms 21 and 22 are welded to the left and right rear portions of the cross member portion 23.

The cross member 23 is a hollow body formed integrally with the bearings 24 and 25 using an appropriate material such as an aluminum alloy, and the cross member 23 is sandwiched between the left and right bearings 24 and 25. A buffer (not shown) is provided in the front space S, and is connected to the cross member 23 via a link.

As shown in FIG. 5, a column 28 is cast between the upper wall 26 and the lower wall 27 at the center of the cross member 23 so as to cross the space vertically. The strut 28 is a solid rod having a uniform thickness, and is arranged in the cavity while being arranged in the core 30 forming the internal space 29. It is cast into the part 23 and integrally formed.

In this way, it is possible to suppress the resonance of the hollow portion by using the support column 28 with the minimum necessary size and suppressing the resonance during traveling generated at the upper wall 26 and the lower wall 27. Therefore, resonance and resonance noise can be reduced as in the previous embodiment. In addition, since the thickness of the cross member portion 23 and other special vibration damping structures are not required, the structure can be simplified and the overall weight can be made relatively light as compared with the magnitude of the noise reduction effect obtained. .

It should be noted that the present invention is not limited to the above embodiments, and various applications and modifications are possible.
The present invention can be applied to a hollow cast for a wheeled vehicle or other various vehicles or an application other than a vehicle.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line 1-1 of FIG.

FIG. 2 is a view showing the entire appearance of a casting wheel according to a first embodiment.

FIG. 3 is a view showing a mold structure for molding the wheel.

FIG. 4 is a diagram showing a plan view shape of the entire swing arm according to a second embodiment.

FIG. 5 is a sectional view taken along line 5-5 of FIG.

[Explanation of symbols]

Wheel 1, hub 2, spoke 3, rim 4, side wall 5, support 8, swing arm 20, cross member 23, support 28

Continued on the front page (72) Inventor Tadashi Natsume 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3D011 AF00 AF01 AL14

Claims (3)

[Claims] 1. A hollow cast body in which a hollow box-shaped portion is integrally formed by casting, in which a support for connecting between opposing walls surrounding the hollow is disposed on a core during casting and is cast. And a hollow cast body structure which is left across the hollow portion. 2. The hollow cast body structure according to claim 1, wherein said hollow box-shaped portion is a hub of a vehicle wheel, and said pillar is a tubular member having the same center as the axle center. 3. The hollow cast body according to claim 1, wherein said hollow box-shaped portion is a cross member portion provided at a front portion of a swing arm constituting a rear wheel suspension device for a motorcycle. Construction.