Metal founding – Means to shape metallic material – Including means to assemble mold parts
Reexamination Certificate
1999-12-28
2002-10-15
Elve, M. Alexandra (Department: 1725)
Metal founding
Means to shape metallic material
Including means to assemble mold parts
C164S340000, C164S137000
Reexamination Certificate
active
06463994
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to motorcycle wheels and in particular to an apparatus and method for casting motorcycle wheels.
One piece motorcycle wheels formed from alloys of light weight metals such as aluminum, magnesium and titanium are becoming increasingly popular. Such wheels can be formed by conventional gravity casting processes which utilize highly automated casting machines. A type of automated casting machine has a plurality of multiple piece wheel molds mounted upon a carrousel. The carrousel is rotationally indexed to move the molds into a charging position where a charge of molten metal is poured into the mold. As the carrousel continues to be indexed, the molten metal cools and solidifies into a wheel casting. The wheel mold is then opened and the casting removed. The mold is reclosed and returned to the charging position. Other types of automated casting machines also can be used. Sprues and risers are removed from the wheel casting and the casting machined to a final shape.
Referring now to
FIG. 1
, there is shown generally at
10
, a typical prior art motorcycle wheel mold. The mold includes a base member
11
which is mounted upon a casting machine carrousel (not shown) and supports the other mold components. The mold
10
also includes a plurality of horizontally movable side members. As shown in
FIG. 1
, the mold
10
includes a left side member
12
and a right side member
13
. The mold
10
further includes a vertically movable cup shaped top core
14
. A ball member
15
, which has an inverted cup shape, is attached to the upper surface of the center of the top core
14
.
As shown in
FIG. 1
, the side members
12
and
13
and top core
14
are in their extended positions and cooperate to define a mold cavity
20
. The mold cavity includes an annular rim cavity
21
connected by a plurality of radial spoke cavities
22
(one shown) to a central hub cavity
23
. The ball member
15
defines a ball riser
24
which is adjacent to the upper end of the hub cavity
23
. Similarly, an axially extending annular rim riser
25
is formed in the side members
12
and
13
adjacent to the upper end of the rim cavity
21
. As shown in
FIG. 1
a gate
30
is formed in the right side member
13
. The gate
30
includes a conical inlet chamber
31
which receives the molten metal. The inlet chamber
31
communicates through a passageway
32
with an intermediate chamber
33
. An axial slot
35
provides communication between the intermediate chamber
33
and the mold cavity
20
.
To cast a motorcycle wheel, a charge of molten metal is poured into the gate
30
. The molten metal flows into the rim cavity
21
and through the spoke cavities
22
into the hub cavity
23
. Additional molten metal is accumulated in the ball riser
24
and the rim riser
25
. As the metal in the wheel cavity
20
cools, the metal contracts and gravity causes additional molten metal to flow from the ball and rim risers
24
and
25
into the mold cavity
20
. Once the metal has solidified, the top core
14
and ball member
15
are raised and the side members
12
and
13
retracted to allow removal of the wheel casting. The ball and rim risers are cut from the casting and the casting machined to a final shape, which is shown by the dashed outline labeled
37
in FIG.
1
. In order to minimize machining, the shape of the rim cavity
21
closely approximates the shape of the finished motorcycle wheel rim.
SUMMARY OF THE INVENTION
This invention relates to an improved apparatus and method for casting motorcycle wheels.
Due to the geometry of motorcycle wheels, the wheel rim and spokes have small cross-sectional areas. Accordingly, the metal in the spoke and rim cavities tends to cool more rapidly than the metal in the hub cavity. Referring again to
FIG. 1
, as explained above, the rim cavity is shaped to closely follow the final rim shape of the wheel. This is done to minimize the amount of machining needed to finish the wheel. However, as the metal in the spoke cavities
22
solidifies, the flow of molten metal from the hub ball riser
24
to the rim cavity
21
is blocked. Similarly, as the metal in the rim cavity
21
solidifies, the flow of molten metal from the rim riser
25
can be blocked. Thus, shrinkage in the rim and spoke cavities
21
and
22
may not be replaced with additional molten metal and might lead to rejection of the wheel casting. Therefore, it would be desirable to provide an improved mold which would assure that additional molten metal can be supplied to the rim and spoke cavities
21
and
22
.
The present invention contemplates a mold for casting a motorcycle wheel which includes a base member and a plurality of side members with at least one of the side members including a gate adapted to receive molten metal. The mold also includes a top core and the mold has a central axis. The top core cooperates with the base member and side members to define a mold cavity having an annular portion which defines a rim cavity for casting a motorcycle wheel rim. The mold cavity communicates with the gate formed in the side member. An annular rim riser is formed upon an end of the rim cavity. The rim cavity has a gently undulating outer surface between the annular rim riser and spoke cavities so that there are no more than two changes of direction relative to the mold central axis and the rim cavity has a sufficient width to facilitate the flow of molten metal from the rim riser into the mold cavity. The mold members further define a central hub cavity which communicates with the rim cavity through at least one radial spoke cavity. The central hub cavity communicates with a hub riser.
The invention also contemplates that a slot is formed in the side member, the slot communicating either between the gate and the rim riser cavity or between the gate and the rim cavity. Alternately, a first slot can be formed in the side member which communicates between the gate and the rim riser cavity and a second slot can be formed in the side member which communicates between the gate and the rim cavity.
The invention further contemplates a process for casting a motorcycle wheel which includes providing the motorcycle wheel mold described above. Molten metal is poured into the mold gate, the molten metal filling the rim cavity and flowing through at least one of the wheel spoke cavities fill the central hub cavity. The molten metal is allowed to cool sufficiently to solidify into a motorcycle wheel casting. The mold is then opened and the casting removed.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.
REFERENCES:
patent: 4035895 (1977-07-01), Lester
patent: 4047764 (1977-09-01), Lester
patent: 4118073 (1978-10-01), Marwitz
patent: 4256348 (1981-03-01), Lester et al.
patent: 5320160 (1994-06-01), Kato et al.
patent: 5647426 (1997-07-01), Prieto et al.
patent: 6186218 (2001-02-01), Prieto
patent: 402041737 (1990-02-01), None
patent: 404200842 (1992-07-01), None
Nitz John D.
Shi Jiang Z.
Hayes Lemmerz International Inc.
MacMillan Sobanski & Todd LLC
McHenry Kevin
LandOfFree
Apparatus and method for gravity casting a motorcycle wheel does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for gravity casting a motorcycle wheel, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for gravity casting a motorcycle wheel will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2924458