Lamborghini - Alcoa Forged Wheel

The tire size is 245/35 ZR 18 front, the rear tires 335/30 ZR 18. The standard tires are Pirelli P Zero Corsa. The braking system consists of four carbon-ceramic discs with ABS anti-lock technology. Thats Lamborghini Murcielago LP 670-4 SuperVeloce the Fastest Lamborghini in the World.

What are " Forged Wheels " ?

Forged wheels are strong, dense, yet very light wheel that high performance car enthusiasts use for their cars almost exclusively. The term “forged” refers to making an alloy wheel by forcing a raw block of metal into a shape with extreme pressure. Forging is an expensive,
 multi-stepped process.

Most of the alloy wheels on the market are one-piece cast wheels, not forged wheels. The difference between the two processes is that casting involves placing liquefied aluminum
into a mold. As the aluminum cools, it is formed into a wheel. There are several different ways to accomplish this, including gravity casting and low-pressure casting.

The main benefit of forged wheels over cast wheels is the weight. To understand the benefits of lighter wheels, it is necessary to understand the differences between “sprung weight” and “unsprung weight” in relation to your vehicle. Sprung weight is supported by the suspension, including the transmission, engine and chassis. On the other hand, unsprung weight refers to everything else, including the suspension system and the components attached to it. Surface imperfections in the roads place force on unsprung weight, which then reacts with its own movement. The less unsprung weight in a vehicle, the less it is affected by the road and other outside forces.

Reducing unsprung weight increases vehicle performance and the easiest place to do that is in the wheels of the vehicle. The vehicle handling and maneuverability is increased, including faster breaking and acceleration times. Lighter wheels will also cut back on the wear and tear of the vehicle’s tires, as well as increase the vehicle’s fuel efficiency. Since forged wheels are significantly lighter than most cast wheels, all of these benefits can be achieved by replacing cast wheels.

Forged wheels also have other benefits. Forged wheels sport a higher density of grain structure than cast wheels. Cast wheels tend to be more porous than forged wheels. This means that a forged wheel will hold a polished shine longer than a similarly polished cast wheel. They are also up to 300 times stronger than cast wheels and can take more damage while lasting for a longer time.

Refer to : Wisegeek / What are Forged Wheels ?

Think about the relationship below :

Football Player : Shoes :: Sports Car : Forged Wheels

You can think the lighter shoes would give the player or sprinter better acceleration due to
the less inertial force, so the less unsprung weight (forged wheels) also gives the car better
acceleration and deceleration.

Process of Manufacturing One-Piece Forged Wheels / United States Patent

Abstract :

A one-piece forged vehicle wheel manufactured from a single piece of metal material
thereby forming a strong, lightweight wheel. The wheel is manufactured as a result of extrusion,
forging and machining a metal blank to provide the desired contours and configuration.

The integral nature of the rim and hub eliminates the need to weld components, improving
integrity while reducing the manufacturing costs.

Description :

In the past, wheels for vehicles have been cast or forged of multiple pieces and then
assembly to form the wheel. In the typical construction, the central disc or hub is formed
independently of the rim which itself may be formed of one or more components.
The components of the wheel are then assembled and welded together to form the integral
assembly.

The wheel typically comprises the central disc or hub having plurality of vent openings and
a plurality of lug openings to facilitate mounting of the wheel to the vehicle axle. Attached to
the peripheral edge of the disc is the rim which retains the vehicle tire, particularly the sealing
bead of the tire.

Summary of the Present Invention

The manufacturing process begins with a ring-shaped blank cut from tube stock of aluminum
or forged and machined into a doughnut-shape desire. The rim section of the wheel is
extruded co-axially from the rim while containing the inward radial flow along the hub section.
By containing the inward radial flow during the extrusion of the rim section, much small tonnage
presses cab be used since without such containment material will flow cross the hub face area
and consume all of the force of a small press before the rim can be extruded longitudinally to a
sufficient length. Once the rim section properly extruded, the containment is no longer necessary and the hub design can be forged radially inwardly to its desired configuration.

As the hub is forged, alternating convex and concave area are formed radially about the
central hub openings. Subsequently, the concave areas are machined away from the interior
side of the wheel to form the vent openings of the wheel. This leaves the convex areas as
" spokes " of the wheels and avoids the use of the piercing tools in the hub face. 

Withe the hub section substantially formed, the forged wheel assembly will include inboard
and outboard sections of the rim flared away from the axis of the wheel. The wheel is clamped
into the rotary tool and the wheel is rotated about its axis. As the wheel spins, a roller is
applied to the rim to form the rim configuration according to the configuration of the roller and
the tool mold.

In this manner, the rim contour is precisely formed without machining resulting in a thin,
strong rim and a lightweight wheel. The extrusion, forging, and rolling process form a one-piece
wheel with improved durability and reduced weight.  

Fig.1 and Fig.2 show an aluminum blank. 10 in the form of the ring or doughnut from which

the wheel is forged. 10 is preferably cut to proper length from a tube of aluminum stock. As an

alternative, the ring-shaped blank may be produced by a forging operation which flattens a

section of a solid aluminum bar and then piercing or boring the forged blank to remove the

center of the ring. 

For reference purpose, the blank 10 has the inner surface 12, an outer radial surface 14,
an outboard side 16, and inboard side 18 all of which correspond to the reference position of
the finished wheel.

A rim section 20 is extruded co-axially to the axis of the ring 10 while containing the inward
radial 12 along the hub area (arrow a). By containing the inward radial surface 12a much
smaller tonnage can be utilized since the tonnage requirement is a factor of a cross-sectional
area perpendicular to the press force.

Without such containment, the material will tend to flow radial inwardly across the hub face and
" consume " all of the force of smaller press before the ring section 20 could be extruded to a
sufficient length.

In a preferred embodiment, the rim section 20 is hot extruded to the desired length and then
trimmed to the required length.

After the rim section is properly extruded and trimmed, the containment tools is no longer
needed and may be removed from forging of the hub section 22.

The hub section 22 is hot forged to the desired configuration in accordance with the
configuration of the mold.Typically, the hub section 22 will include a hub openings 24 and
a mounting face 26 surrounding the opening 24 to facilitate mounting of the wheel to the axle
of the vehicle. With the hub section 22 formed and machined, the inboard leg 40 and outboard leg 42 of the rim section 20 are flared radially outward. 

Any ornamental configuration is forged in the peripheral area 28 between the rim section
and the mounting face 26. With the hub section 22 formed and machined, the inboard leg 40
and the outboard leg 42  of the rim section

Once formed, final machining of the wheel is conducted. The outboard of the hub face 26 is
machined to the proper contour.

The inboard side of the hub section 22 is machined.

Lug holes 44 are drilled in the hub face 26.

A valve hole 46 is drilled through inboard leg 42 of the rim section 20.

The wheel is polished and clear coat finish is applied forming the finished product.

 

In a preferred embodiment of the present invention, alternating concave 30 and convex 32

zones are forged radially about the hub face 22. In order to avoid the use of pierce tools which

may deform the hub face, the concave zones 30 are utilized to form vent openings or 

windows 34 in the hub section 22. 

The concave zones 30 are machined away from the inboard side 18 of the hub section 22 using an appropriate machining tool T until the appropriate  opening 34 is formed at the bottom of the concave zone 20.

The alternating opening 34 and convex zone 32 provide the appearance of spoke-like bodies

in the hub 22 of the wheel. In alternative embodiment, the wheel face may be formed with 

alternating sections of the thick and thin material wherein the thin sections are pierced to form

windows creating vent openings in the wheel 10.

the wheel 10 is then place in the mandrel of a spinning machine M and clamped into the
position by clamping against the hub section 22 of the wheel. The spinning machine M includes
a molding surface S. With the wheel clamped in the machine M which incorporated a contour
of the molded rim section. Similarly, a roller tool R has mating molding surface S'.

With the wheel clamped in the machine M, the wheel is spun about its axis and the roller tool
R is applied to the rim section 20 to precisely form the rim contour. As the result, no machining
is necessary except to trim the ends 40 and 42 and a very thin yet sturdy rim is produced using
the extrusion and rolling processes as shown in Fig.7

In application where extremely close tolerances are required, the rim rolling operation may
be conducted as a two-steps process wherein preliminary rolling operation is followed by a
solution heat treatment operation and a final rolling operation. The final rolling operation
removes the distortional effects of the solution heat treatment bath.

The wheel made in the U.S.A. Cleveland Ohio.

Alcoa

Aluminium Column

Before to the forged process, the aluminium went into the furnace to heat
and to be softened.

Forged the aluminium.

1.Oil lubricant is sprayed onto the mold and ignited by heat.
   The oil keeps the aluminium from stcking to the steel mold.
   Lubricants greatly influence friction and wear.
   Then 4.5 million kilograms of pressure slam down on the wheel from high above and,
   shaping the aluminium into something resembling a wheel.
2.The aluminium went into a second to refine its shape further
    with 4.5 million kilograms of pressure.
3. Pistons manufacturing used the same way. Refer to "McLaren MP4"

Advantage and Know-How

The Murcielago's wheel are forged, a process invented by Alcoa in 1984. With forging, aluminium is not melted into liquid like casting. Instead, it's stamped by the mold. Forging makes a stronger, lighter wheel than casting. Because it has less imperfections inside the material. I could have a thinner cross section, and make a light part with the same final mechanical properties.

Outline of forging
 
1.Billet Slug Preform (Shearing Sawing, Cutting off Machining)
2.Furnaces ( Hot Warm Isothermal ) Heated dies
3.Forgeability ( Open die ) Presses, Forging machines, Die design and manufacturing, Lubrication
4.Trimming, Machining, Heat treating, Finishing, Cleaning, Inspection.


After the forged, and then shape the wheel.

Punch the center out.

K-M-S Industries. Ship the wheel to machine.

CAM (Computer Assist Engineering)

Machine the wheel.
Five nut holes--> Five Double-Spokes

One piece forged wheel featured the lightest and strongest structure.
Compared to the Die-Casting.

Install the wheel to the Lamborghini.