OCLV carbon-fiber bike tops Tour de France

OCLV carbon-fiber bike tops Tour de France

Vertical grinding of cylindrical parts

Armstrong pumped this Madone SL 5.9 to his recent sixth-straight Tour de France win.
The bike's aerodynamic design directs air around the OCLV frame, while maintaining the stiffness required for hard sprints and climbs.

Madone racing bicycles, built by Trek Bicycles at its factory in Waterloo, Wis., feature the company's OCLV carbon-fiber and epoxy composite frames that are strong, yet lightweight. These qualities were of key benefit to Lance Armstrong as he pumped a Madone SL 5.9 to his recent sixthstraight Tour de France win.

Zapata Espinoza, brand manager at Trek, explains, "The damping qualities of the OCLV carbon frame provides a much smoother ride than possible with steel, aluminum, or titanium frames, critical in such a long, grueling race. In choosing the bike, weight was an important consideration, but so were handling and ride characteristics."

The bike's OCLV 110 carbon frame withstood beatings on wet cobblestones, leapt quickly when Armstrong stomped on the pedal, and helped speed him to first place over the three-week, 2110-mi race, replete with the formidable climbs and fearsome descents of France's serpentine mountain roads.

Espinoza adds that although there is currently a boom of commercial carbon manufacturing in Taiwan and China, and, over the past three years, an explosion in carbon-fiber popularity, Trek has been manufacturing its patented Optimum Compaction Low Void (OCLV) frames since 1992. Reportedly, the company is the only manufacturer using this technology to make bike frames.

In this process, the company lays carbon fibers impregnated with epoxy in a frame mold. It closes the mold over an air bag, which is inflated, forcing out air pockets, or voids, between the fiber layers. These pockets must be eliminated because they are potential weak points in the frame structure.

The number after OCLV, in this example "110," refers to the grams of carbon in one square meter of frame tubing. This is the same grade of carbon used in recent space satellite construction.

Espinoza continues, "Where company stress tests showed other grades weren't the optimum material for specific frame areas, OCLV 110 was used to ensure the necessary durability. This means high-stress areas take advantage of the dense, tightly woven fibers' strength, whereas low-stress areas can afford to skimp on materials, thus further reducing the bike's weight."

Carbon-fiber technology also allows for other design fine-tuning. For example, framebuilders can orient the carbon fibers to create directionspecific strength in varying stress-load areas.

The finished aerodynamic frames sport air fairing behind the seat tubes and specially shaped down and toptubes. Trek also sells bikes with these same frames to the public.

Engineers at Trek design the molds with Solid Works 3D mechanical-design software and employ CosmosWorks designanalysis software to virtually test bikes on-the-fly before manufacturing them. The software lets engineers preview how frame design changes may effect the stresses and strains involved in a cyclist pounding up a steep mountainside. This finite-elementanalysis program saves the company money, freeing it from physical prototypes until the models are deemed workable.

At 14.96 lb, the Madone just squeaks past the minimum weight limit set by the International Cycling Union, the professional-cycling governing body. During the race, team mechanics swapped components based on performance objectives and the day's terrain. For example, during the flat stages, they equipped the bike with durable, aerodynamic aluminum wheels, whereas during mountain stages, they mounted lightweight, OCLV carbon-fiber wheels.

Vertical grinding of cylindrical parts

The 750 Series grinder from Campbell Grinding Co., Spring Lake, Mich., machines cylindrical parts in a vertical orientation, greatly reducing the effects of gravity. According to the builder, the vertical setup increases rotational stability and part quality. The machine can also integrate hard turning, which complements the grinding process and increases productivity.

Standard models feature 24-in.-high part capacity and 12 to 44-in. swing diameters. The grinder's frame design and quartz-epoxy filling combine to increase rigidity, thermal mass, and dampening qualities.

Advanced materials boost fuel-system performance

Metering plungers made from Carpenter's new ZrX-GBP zirconia have boosted performance, reliability, and durability for high-pressure diesel-fuel systems at Cummins Inc.
A cutaway of Cummins' Celect fuel injector shows a white metering plunger (shorter part) made from Carpenter's ZrX-GBP zirconia and a longer white timing plunger made from a conventional zirconia material. The complex metering plunger requires greater strength and fracture toughness than the timing plunger.

Demanding applications often call for advanced materials that withstand harsh operating conditions. Take, for instance, a dieselfuel-system at Cummins Inc., Columbus, Ind. The company boosted system performance, reliability, and durability by using a new zirconia grade from Carpenter Advanced Ceramics, Auburn, Calif.

The magnesia partially stabilized zirconia — known as ZrX-GBP (grain boundary pinned) — has the strength and fracture toughness needed for a fuel-injector metering plunger. ZrXGBP zirconia can be matched to a small plunger-bore clearance ( singledigit microns). This property allows tight-tolerance, high-pressure applications with metal components. The Carpenter zirconia has provided such high-contact stress resistance, or "damage resistance," as Cummins puts it, that it is particularly suited for the complex geometry of the metering plunger.

Carpenter provides Cummins with partially ground zirconia blanks with a drain hole in one end that intersects a cross drilling. Precisely located edges and other features are precision ground at the other end by Cummins.

Carpenter follows a production process strictly controlled by QS9000 procedures in preparing its ZrX-GBP zirconia blanks for Cummins. Carpenter grinds the outside diameter and taper of these blanks to tolerances as tight as the low single-digit micron size for cylindricity. The finished blanks undergo extensive testing and inspection for quality control before shipping.

After it receives the ground zirconia metering plunger blanks from Carpenter, Cummins completes the finishing of the O.D. surface, spring post, and groove on specialized infeed and throughfeed centerless grinders. Machine operators achieve submicron tolerances on cylindricity, which is then match-fit to similar diametrical tolerances. After surface finishing, the plungers are assembled into Cummins' Celect diesel fuel injectors.

In addition to its other benefits, the zirconia has eliminated all scuffing and adhesion problems formerly encountered with mating metal components. A monolithic metering plunger of the newly developed zirconia has proved to be a cost-effective alternative to coating.

Carpenter reports that the mean coefficient of thermal expansion for its new zirconia over a temperature range of 25 to 400 C is comparable to that of metal and distinctly higher than for most ceramics.

Five-axis laser competes against EDM

Winbro's Lasemill lasermachining system, which uses Delcam software, readily competes against EDMs in turbine blade and vane applications.

An innovative 5-axis lasermachining process lets aerospace and industrial-gas-turbine manufacturers machine complex geometries into turbine blades and vanes. Previously, the laser's quality and accuracy levels were only possible with EDM. In addition, the Lasemill process is reportedly faster and cheaper than EDMing the parts.

The Winbro Group, the Leicestershire, UK-based firm that developed Lasemill, plans to supply the technology as a complete turnkey package, comprising the 5-axis laser center, the machining program, and the jigs and fixtures for specific components. The software, Power Solution CAD/CAM software from Delcam Inc., Windsor, Ont., imports component designs, models arrays of required holes, and develops machining paths. Full visualization and process simulation within the software ensures user confidence in the final process.

The main application of the Lasemill process is expected to be in the precision drilling of holes for the air cooling of components made from stainless steel, titanium, and nickel. This is a critical part of the manufacturing operation since the aim is to create the maximum possible number of holes in the part without jeopardizing its structural integrity. Furthermore, it is usually one of the final stages in making the components, so each part already has a high built-in value. For example, in one project, it was estimated that the cost of scrapping a single part would be $20,000.

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