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Products and solutions, 2000-06-13, 02:00 AM

Thyssen Umformtechnik + Guss wins Steel Innovation Prize for newly developed wheel knuckle

The Brackwede plant of Thyssen Umformtechnik und Guss GmbH (TUG) has won the 2000 Steel Innovation Prize in the Innovative Steel Products category. The award was made for a newly developed stamped steel wheel knuckle for multi-link axles, which allows a 30 to 40 percent weight reduction and 50 percent lower production costs versus conventionally manufactured knuckles. "The low weight and manufacturing costs of the component make it possible to use multi-link axles - previously the preserve of luxury automobiles - in small and mid-size models," was the jury's verdict in awarding first prize to TUG Brackwede.

This was the fifth year in which the Steel Innovation Prize was awarded by Stahl-Informations-Zentrum, a joint organization of the German steel industry, this time under the patronage of Germany's education and research minister Edelgard Bulmahn. In all, 369 entries were received in the categories Innovative Steel Products, Research and Development, Steel in Housing Construction, and Steel Design. The new wheel knuckle from TUG was selected from 78 projects submitted in the category Innovative Steel Products.

On multi-link axles, the wheel knuckle is the link coupling the wheel and the axle beam and is joined to the latter via several individually fastened arms. This design offers significantly better handling than twist-beam or rigid axles because each wheel can react independently to uneven road surfaces or other problems. However, the relatively complex design increases both weight and costs, which is why multi-link suspensions are mainly used on larger cars.

In the past, wheel knuckles have generally been made from cast parts which require additional machining to achieve the required dimensional accuracy. TUG's new development comprises two steel stampings, an inner and an outer shell joined by shielded arc welding. A further special feature is that the trailing arm - a separately manufactured add-on part of conventional cast components - is integrated in TUG's knuckle design as an extension of the inner shell. The housing for the knuckle bearing seat, conventionally also a separate add-on, is formed directly in the sheet metal of the trailing arm on the TUG wheel knuckle.

Without sacrificing safety, the hollow sheet metal design provides weight reductions of 30-40 percent depending on vehicle model. With no additional machining required, manufacturing costs are around 50 percent lower. The new, highly compact and low cost component gives automobile manufacturers the option of using multi-link suspension on small and mid-size models. Car buyers benefit from enhanced ride comfort and safety.

TUG Brackwede has its own in-house testing facilities in which extensive strength and endurance tests were performed on the wheel knuckle as early as the design and prototype phase. TUG engineers simulated the load profile of the component under driving conditions. Prototypes were tested under loads way beyond those encountered on the road.

The new wheel knuckle is already being used in the volume production of two mid-size vehicles. Tests with high-strength steels such as the dual-phase steel H 33 X or the stainless grades X8 CrMnNi 19-6-3 and X13 CrMnNi 19-7-2 reveal further weight reduction potential.

Thyssen Umformtechnik + Guss GmbH is part of ThyssenKrupp Automotive and employs around 1,700 people at its Brackwede facility. In addition to chassis components such as integral subframes, engine cradles, wheel knuckles, rear axle beams and twist-beam axles, products include side beams for light and heavy trucks as well as body parts such as doors, fenders and side impact bars.

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