Metal founding – Process – Shaping liquid metal against a forming surface
Reexamination Certificate
1999-10-20
2001-11-20
Dunn, Tom (Department: 1725)
Metal founding
Process
Shaping liquid metal against a forming surface
C164SDIG001, C164S342000, C249S056000
Reexamination Certificate
active
06318446
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to vehicle wheels and in particular to a one piece cast vehicle wheel having a lightener pocket formed beneath the outboard tire bead seat and an apparatus and process for casting the one piece wheel.
It is known in the art to cast one piece wheels from an alloy of a light weight metal, such as, for example, an alloy of aluminum, magnesium or titanium. Conventional highly automated and high volume casting machines can be used to gravity cast such wheels. Such machines typically include a rotatable carousel which carries a plurality of multi-piece wheel molds. As the carousel is indexed, each wheel mold is sequentially rotated toward a charging station. Upon reaching the charging station, molten metal is poured into the mold. As the carousel continues to be indexed, the metal cools to form a wheel casting. Once the metal is completely solidified, the mold is opened and the wheel casting removed. Risers and gates are removed from the casting and the casting is machined to a final shape.
A typical cast wheel includes a generally cylindrical wheel rim which is adapted to carry a pneumatic vehicle tire. The rim has a recessed center portion which is called a deepwell. Extending from the deepwell toward the inboard end of the wheel is a tapered portion called a leg. The leg terminates in a circumferential inboard tire safety bead which retains an inboard tire wall bead upon the wheel rim. Adjacent to the inboard tire safety bead is an inboard tire bead seat which carries the inboard tire wall bead. The inboard end of the wheel rim terminates in an inboard tire retaining flange.
The outboard end of the deepwell ends at a deepwell wall which extends radially to a circumferential outboard tire safety bead which retains an outboard tire wall bead upon the wheel rim. Adjacent to the outboard tire safety bead is an outboard tire bead seat which carries the outboard tire wall bead. The outboard end of the wheel rim terminates in an outboard tire retaining flange.
The wheel further includes a circular wheel disc which is typically formed across the outboard end of the wheel rim to provide a sufficient volume within the wheel to receive the larger disc brake assemblies used on current cars and steering and drive components which are included in front wheel drive vehicles. The wheel disc typically includes a central wheel hub which is supported within the wheel rim by plurality of wheel spokes. A pilot hole is formed through the center of the wheel hub and a plurality of wheel lug holes are formed through the wheel hub on a bolt-circle which is concentric with the pilot hole. The outboard end of the wheel rim supports the wheel spokes and is commonly referred to as a wheel sidewall.
Alternately, a wheel spider comprising a wheel hub and a plurality of spokes can be formed within the wheel rim.
SUMMARY
This invention relates to a one piece cast wheel having a lightener pocket formed beneath the outboard tire bead seat and an apparatus and process for casting the one piece wheel.
As described above, it is known to cast a one piece wheel from an alloy of a light weight metal. The geometry of such wheels typically causes the wheel to have a sidewall which includes a large volume of metal. Accordingly, the sidewall adds to the total weight of the wheel and the unsprung weight of the associated vehicle suspension. Thus, it would be desirable to form lightener pockets in the sidewall of such wheels to reduce the wheel weight.
The present invention contemplates a one piece vehicle wheel which includes an annular wheel rim having an inboard and an outboard end and a wheel disc formed integrally with the wheel rim. The wheel disc extends radially across an end of the wheel rim and has an outer edge joining the outboard end of the wheel rim to form a wheel sidewall. The wheel also includes an annular lightener recess formed in the sidewall.
Additionally, the wheel further includes an outboard tire bead seat formed in the sidewall with the recess extends axially into the sidewall beneath the outboard tire bead seat. It is further contemplated that a portion of the sidewall extends transversely across the recess to form a bridge portion, with an aperture being formed through the bridge portion. The aperture being adapted to receive a tire valve. The recess can be either continuous or can include a plurality of webs extending transversely thereacross.
The invention also contemplates that the recess includes at lease one pocket formed therein which extends further into the sidewall from the recess. In the preferred embodiment, the pocket is formed in the recess adjacent to the outer end of a wheel spoke.
The invention further contemplates a method for forming a one piece vehicle wheel which includes providing a multi-piece mold for a one piece wheel. The mold includes a base member which supports a plurality of side members and a top core, the members and top core defining a wheel cavity having a rim cavity joining a disc to define a sidewall cavity. The mold defining a generally vertical axis and further including an annular lightener recess core which extends axially into the sidewall cavity. The mold is charged with molten metal to form a one piece wheel. The mold is then cooled to solidify the molten metal into a one piece wheel casting with the annular core forming a lightener recess in the sidewall of the wheel casting. The mold is opened and the recess core removed to release a one piece wheel casting having an annular lightener recess formed in the sidewall.
The method further contemplates that the mold includes a plurality of upper side members and a plurality of lower side members with the lightener recess core includes a plurality of segments integrally formed as a portion of the lower side members. Additionally, when the mold is opened, the upper and lower side members are sequentially withdrawn to extract the lightener core segments from the wheel casting.
Alternately, the mold can include a separate ring annular lightener recess core which is carried by the mold members. After opening the mold the wheel casting and core are removed together. Subsequently, the core is removed from the wheel casting.
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.
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Nichols John J.
Nitz John D.
Prieto Romulo A.
Dunn Tom
Hayes Lemmerz International Inc.
MacMillan Sobanski & Todd LLC
McHenry Kevin
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