JPH09104201A - Cast wheel of motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cast wheel of motorcycle, which can enhance the draining performance while the worsening of appearance is avoided. SOLUTION: A cast wheel 5 of a motorcycle is formed from a hub 7, rim 8, and spoke parts 9 through a single piece casting process, wherein each spoke part 9 is structured hollow. In this cast wheel 5, the inner surface (d) of the rim side undermost part 9a of the hollow (b) of each spoke is positioned nearer the wheel center than the inside circumferential surface (c) of the bottom wall 8a of the rim 8, and through holes 9b, 9c which penetrate each hollow (b) from the outside and are left as the mark of supporting a core, are positioned in such a way as contacting the inner surface (d) of the rim side undermost part 9a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast wheel for a motorcycle in which a hub portion, a spoke portion and a rim portion are integrally cast.

[0002]

2. Description of the Related Art Conventionally, as a motorcycle wheel, there is a cast wheel in which a hub portion, a spoke portion, and a rim portion are integrally cast so that the spoke portion is hollow. In such a cast wheel, it is desired that the cleaning liquid in the pre-painting process can be quickly drained and the shot balls used in the deburring process can be quickly drained.

In order to secure the above-mentioned drainage property, there is one in which a through hole is formed in the spoke portion so that the inside of the hollow communicates with the outside (see, for example, JP-A-62-74701).

[0004]

By the way, in order to improve the drainage property, etc., as shown in FIG.
The through hole 32 is formed in the bottommost rim-side portion 31a forming the outer peripheral wall of the hollow b. In this case, the through hole 32 connects the rim portion 33 and the spoke portion 31 ( Since it is formed on the bottom wall) a of the rim portion, the corner R portion of the connection portion a is shaved, and there is a problem that the appearance is deteriorated.

The present invention has been made in view of the above conventional circumstances, and an object of the present invention is to provide a cast wheel for a motorcycle capable of improving drainage while avoiding deterioration of appearance.

[0006]

According to a first aspect of the present invention, a hub portion into which an axle is inserted, a rim portion to which a tire is mounted,
In a cast wheel of a motorcycle, wherein a plurality of spoke portions connecting the rim portion and the hub portion to form a concentric circle are integrally cast so that each spoke portion is hollow, the spoke hollow rim side The innermost position of the bottom portion is located closer to the wheel center than the inner peripheral surface of the bottom wall of the rim portion, and a through hole that penetrates into the hollow from the outside and is a trace of the core support is the bottom portion on the rim side. It is characterized in that it is located so as to contact the inner surface of the.

According to a second aspect of the present invention, in the first aspect, the portion of the bottom wall of the rim portion corresponding to the bottom portion on the rim side is offset to the wheel center side from the other portion of the bottom wall. The inner surface of the bottom of the rim portion is located closer to the center of the wheel, and the invention of claim 3 is characterized in that, in claim 2, the bottom of the hollow portion on the rim side is a curved surface convex toward the hub. It is characterized by having a shape.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 are views for explaining a cast wheel of a motorcycle according to an embodiment of the present invention, and FIG. 1 is a right side view of a front wheel portion of a motorcycle equipped with the cast wheel of the present embodiment, 2 is a left side view of the cast wheel, and FIG. 3 is a sectional front view (II in FIG. 2).
4 and 5 are enlarged sectional front views of the rim portion, and FIG. 6 is a sectional view of the spoke portion (sectional view taken along the line VI-VI of FIG. 2).

In the drawing, reference numeral 1 denotes a front fork supported by a head pipe 2a at a front end of a vehicle body frame 2 so as to be rotatable left and right. A steering handle 3 is fixed to an upper end of the front fork 1 and a lower end thereof is fixed to a lower end thereof. Has a front wheel 4 rotatably supported. The front wheel 4 includes a cast wheel 5 having the features of the present invention, and a tire 6 mounted on the outer peripheral portion of the wheel 5. The arrow A indicates the direction of rotation during forward movement.

The cast wheel 5 has a hub portion 7 through which an axle is inserted through bearings, a rim portion 8 on which the tire 6 is mounted, and the rim portion 8 and the hub portion 7 form a concentric circle. The three spoke portions 9 connected to the above are integrally cast so that the inside of the spoke portion 9 is hollow.

The hub portion 7 has an axle support portion 7a in the center thereof, and the axle support portion 7a is surrounded by a thin drum portion 7b. Between the drum portion 7b and the axle support portion 7a. A lightening space a is formed.

The rim portion 8 comprises a bottom wall 8a having a dish-shaped cross section, and ears 8b and 8c to which the tire 6 fits, which are integrally formed on the left and right sides of the bottom wall 8a, and the bottom wall 8a. An annular rib 8d for reinforcement is integrally formed on the inner peripheral surface c of the.

In the side view, the spoke portion 9 is inclined so that the outer peripheral side portion thereof is located on the rear side in the rotational direction, is slightly arcuate, and has a hollow b inside. The hollow b communicates with the lightening space a of the hub portion 7, and the rim portion 8 side is closed.

The rim portion 8 among the wall portions forming the hollow b.
The rim-side bottommost portion 9a located on the side (outer peripheral side) is deviated to the wheel center side from the connection point between the rim portion 8 and the spoke portion 9, that is, the bottom wall 8a of the rim portion 8. As a result, the inner surface d of the bottom portion 9a on the rim side is the bottom wall 8a of the rim portion 8.
It is located closer to the wheel center than the inner peripheral surface c. Furthermore, the rim-side bottom portion 9a is formed in a slightly arcuate shape so as to be convex toward the wheel center side. Through holes 9b and 9c are formed on the front side of the bottom portion 9a on the rim side and on the front side and the back side of FIG. The through holes 9b and 9c are formed by the traces of the core support pieces for forming the hollow b and the lightening space a.

As shown in FIG. 6, each of the three spoke portions 9 has a wing shape when viewed in a transverse section, and any spoke portion is formed on the inner surface of the side wall 10 forming the hollow b. 9 also has upper and lower grooves 10a, 10b for reducing the weight by making the wall thinner than the basic portion.
The depth of these grooves depends on the lower groove 1 located on the lower side during casting.
0b is set deeper than the upper groove 10a located on the upper side. The reason for setting such a depth is as follows.

That is, in order to further reduce the weight, the groove may be deepened to have a thin wall, but if the wall is too thin, there is a limit because the flow of molten metal deteriorates during casting. On the other hand, the pressure of the molten metal at the time of casting is higher than that of the upper portion due to the weight of the molten metal. Therefore, in this embodiment, the lower groove 10b located on the lower side at the time of casting is set deeper to make the lower side thinner, thereby ensuring the supply of hot water and promoting the weight reduction.

The casting die of the cast wheel 5 of the present embodiment has a lower portion forming the periphery of the hub portion 7, the spoke portion 9 and the inner peripheral surface portion of the rim portion 8, as shown by the chain double-dashed line in FIG. The mold 21, the upper mold 22, and the left that forms the outer peripheral surface of the rim portion 8,
It is composed of right molds 23 and 24. Lower mold 2
1, the upper die 22 is divided into upper and lower portions on a plane A perpendicular to the axis, and the left die 23 and the right die 24 are divided into left and right portions on a plane B including the axis.

Here, the bottom portion 9 on the rim side forming the hollow b.
Since a is deviated from the bottom wall 8a of the rim portion 8 toward the wheel center side, the left and right dies 23, 24 for forming the outer peripheral surface of the rim portion may be divided depending on the arrangement position. A so-called undercut occurs. In the present embodiment, as shown in FIG. 2, the parting line B is formed so as not to be caught by the bottom portion 9a on the rim side when viewed in the splitting direction (see arrow C), that is, to be opened. Since the setting is made, the bottom portion 9a on the rim side does not hinder the mold cutting.

Next, the function and effect of the cast wheel 5 will be described. In the present embodiment, the rim-side bottom portion 9a forming the hollow b is formed in a curved shape slightly convex toward the wheel center side, and the through holes 9b, 9c are formed in the front corner portion and the rear corner portion of the bottom portion 9a. Is formed so as to be in contact with the inner surface d, the drainage property of the cleaning liquid in the hollow b and the discharge property of the shot balls can be secured, and the cleaning liquid or the shot balls can be quickly discharged. Further, since the core support pieces are positioned at the front and rear corners, the through holes 9b and 9c are formed by the traces of the support pieces, so that separate hole machining is not required.

Since the bottom portion 9a on the rim side is deviated to the wheel center side from the bottom wall 8a of the rim portion 8 which is a connection point between the rim portion 8 and the spoke portion 9, the through holes 9b, 9 are formed.
While forming c so as to contact the inner surface d of the bottom portion 9a on the rim side, the corner R of the connecting portion between the rim portion and the spoke portion is not scraped off, and deterioration of the appearance can be avoided.

Further, since the rim-side bottom portion 9a is deviated to the wheel center side, the rim-side bottom portion 9a is more than the bottom wall 8a of the rim portion 8 when viewed as a cast product (material) before machining. It can be made thin, and the weight and cost of the material can be reduced.

That is, in the case of a cast wheel, as shown in FIGS. 4 and 5, the cast wheel is cast into a shape indicated by a chain double-dashed line to ensure fitting at the portion where the tire of the rim is mounted and to prevent air leakage. In order to prevent this, and in order to ensure the thickness of the member required to secure the strength with precision, it is necessary to cut into the shape indicated by the solid line. In the case where the conventional bottom portion on the rim side is at the same position as the bottom wall 8a of the rim portion 8 (see the broken line in FIG. 4), the bottom portion is also machined, so that the bottom portion includes the machining allowance e. Is set to On the other hand, in the case of this embodiment, the bottom portion 9a on the rim side is deviated to the wheel center side, and therefore is not machined. Therefore, the rim-side bottom portion 9a is set to a thickness that does not include the machining allowance, and the weight and the wasteful material are reduced accordingly.

In the casting of the cast wheel 5, it is desirable to cool the spoke portion 9, the bottom wall 8a, and the ears 8b and 8c in this order in order to prevent sink marks. However, in the conventional cast wheel, the portions corresponding to the spokes of the bottom wall 8a are thicker by the machining allowance, and the heat capacity is large, so that the ears 8b, 8c precede the bottom wall 8a. There is a tendency to cool and then the bottom 8a, so that the bottom wall 8a
The hot water is not replenished from the surroundings during the cooling of the
There is a problem that sink marks are likely to occur in a. Conventionally, in order to avoid this problem, for example, the ridge 8c is provided with a feeder 8d for delaying cooling, and the feeder 8d is also a cause of wasted material.

In the case of the present embodiment, as described above, the portion corresponding to the bottom wall 8a of the spoke portion 9, that is, the rim-side bottommost portion 9a, is thin because the machining allowance is unnecessary. The bottom 9a cools before the ears 8b, 8c,
The occurrence of the sink mark is prevented, and as a result, the feeder 8d
Can be eliminated, and in this respect as well, wasteful materials can be reduced.

In the above embodiment, the rim-side bottom portion 9
Although a is formed in a convex curved shape toward the wheel center side, the rim-side bottommost portion does not necessarily have to be formed in a curved surface. For example, as shown in FIG. 7, the rim-side bottommost portion 9d is linear and inclined. You may form in.

Further, in the above embodiment, the rim-side bottom portion 9
Although a is deviated from the bottom wall 8a of the rim portion 8 to the wheel center side, it is not always necessary to deviate, and for example, as shown in FIG. 8, it corresponds to the hollow b of the bottom wall 8a of the rim portion 8. The portion 8a 'to be formed is set thick, that is, the bottom face f of the hollow b
May be raised, and the through hole 9e may be formed so as to contact the raised bottom surface 9f.

Furthermore, for example, as shown in FIG.
It is also effective to combine the method of displacing the bottommost portion on the rim side with the method of raising the bottommost surface depending on the position of the spoke portion. In this example, the bottom surface 4 on the rim side of the spoke portion 41 located on the split surface B of the left and right molds 23, 24.
1a is a bottom-up type, and the rim-side bottommost portion 42a of the spoke portion 42 located on a line perpendicular to the split surface B is deviated to the wheel center side.

In this case, the spokes 9 are
Even though it has a book, it does not interfere with mold splitting,
In any of the spokes, the through hole can be arranged so as to be in contact with the hollow bottom surface and closer to the wheel center side than the connecting portion between the spoke portion and the rim portion.

Further, the bottom surface 41 of the rim side of the above-mentioned bottom-up type
a, 41a, and rim-side bottom parts 42a, 4 of the displacement method
Since the two wheels 2a are located symmetrically with respect to the wheel center, there is no problem that the weight balance is lost.

[0030]

As described above, according to the cast wheel for a motorcycle of the first aspect of the invention, the inner surface of the rim-side bottom portion of the hollow spoke is located closer to the wheel center than the inner peripheral surface of the bottom wall of the rim portion. Since the through hole which is a trace of the core support is formed so as to be in contact with the inner surface of the bottom portion on the rim side, the inside of the spoke portion can be formed without cutting the corner R of the connection portion between the rim portion and the spoke portion. It has the effect of improving the drainage performance of

According to the invention of claim 2, the portion of the bottom wall of the rim portion corresponding to the bottom portion on the rim side is displaced to the wheel center side from the other portion of the bottom wall, whereby the rim portion is formed. Since the inner surface of the bottom portion is located closer to the center of the wheel, the thickness of the bottom portion of the rim side at the time of casting can be set to a thin thickness that does not require a machining allowance, and the weight and cost can be reduced.

According to the third aspect of the present invention, since the bottommost portion on the rim side of the hollow portion is set to the curved surface convex to the hub side, there is an effect that the above-mentioned drainage property can be further improved.

[Brief description of the drawings]

FIG. 1 is a right side view of a motorcycle including a cast wheel according to an embodiment of the present invention.

FIG. 2 is a left side view of the cast wheel of the embodiment.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is an enlarged sectional front view of a rim portion of the cast wheel according to the embodiment.

FIG. 5 is an enlarged sectional front view of a rim portion of the cast wheel according to the embodiment.

FIG. 6 is a sectional view taken along the line VI-VI of FIG. 2;

FIG. 7 is a side view of a modified example of the rim bottom portion of the cast wheel of the embodiment.

FIG. 8 is a side view of a modification of the bottommost rim portion of the cast wheel of the embodiment.

FIG. 9 is a side view of a modified example of the cast wheel of the embodiment.

FIG. 10 is a side view of a bottom portion of a rim portion of a conventional cast wheel.

[Explanation of symbols]

 5 cast wheel 6 tire 7 hub part 8 rim part 8a bottom wall 9 spoke part 9a rim side bottom part 9b, 9c through hole b hollow c inner peripheral surface d inner surface

Claims (3)

[Claims] 1. A hub portion into which an axle is inserted, a rim portion to which a tire is mounted, and a plurality of spoke portions connecting the rim portion and the hub portion so as to form a concentric circle. In a cast wheel of a motorcycle integrally cast to form a hollow, the inner surface position of the bottom of the spoke hollow rim side is located closer to the wheel center than the inner peripheral surface of the bottom wall of the rim portion, and The cast wheel for a motorcycle according to claim 1, wherein a through hole that penetrates through the hollow and is a trace of the core support is located so as to contact the inner surface of the bottom portion on the rim side. 2. The bottom portion of the rim portion according to claim 1, wherein a portion of the bottom wall of the rim portion corresponding to the bottom portion on the rim side is offset from the other portion of the bottom wall toward the wheel center. The cast wheel of a motorcycle characterized in that the inner surface of the is located closer to the center of the wheel. 3. The cast wheel for a motorcycle according to claim 2, wherein the bottom portion of the hollow portion on the rim side has a curved surface convex toward the hub.