Products and solutions, 2003-09-09, 02:00 AM
From materials supplier to systems partner: ThyssenKrupp Stahl presents the NewSteelBody
At the 2003 Frankfurt International Motor Show, ThyssenKrupp Stahl AG will be unveiling the results of its NewSteelBody project (NSB®): On its own initiative, the company designed a complete weight-optimized steel body-in-white, analyzed and documented its key structural data using recognized methods, drew up a viable production schedule and calculated the material and manufacturing costs. ThyssenKrupp Stahl AG is now offering the results of its open source project to interested auto manufacturers for joint further development. In so doing, the Duisburg, Germany-based company has proved its credentials not only as a creative initiator of alternative concepts for lightweight construction with steel but also as a fully qualified systems partner.
The reference vehicle for the NewSteelBody is the Opel Zafira compact van, which is currently produced in volumes of about 200,000 per year and has received top ratings in particular for its crash performance. The main aims of the NSB® project were to show that the design can achieve maximum weight savings while remaining comparable with the reference model in every detail, and also that the concept is suitable for volume production. The body developed under the project - for which full process planning has been drawn up including clamping and fixing concepts for assembly welding - is 24% lighter than the reference vehicle. The components used have been verified as viable for volume production. The project also incorporated an examination of the tolerance chain. The design of the body allows the powertrain and chassis of the reference model to be integrated without difficulty. Key structural data such as crash performance and durability ascertained under realistic conditions were verified as matching or improving on those of the reference model.
The NewSteelBody achieves its 24% weight saving mainly through an intelligent combination of conventional stamped design and innovative profile construction. Around half the body-in-white is made from stampings, the other half on the basis of closed thin-walled hollow sections. The front and rear side members and the roof frame of the NSB® are made from thin-walled hydroformed tubes. The rear side members comprise Tailored Tubes, featuring a combination of different strength steels to meet load requirements. One technical highlight are the front side members: made from Tailored Tubes with tapered geometry, these components offer significantly higher collision energy absorption than cylindrical steel sections. The B, C, and D pillars of the NSB® design are made from laser welded, hydroformed blanks.
The intensive use of hollow sections in the NSB® design harnesses the full potential of high-strength steels and in some areas utilizes the available packaging space far more effectively than stamped designs, since no welding flanges are required. It also enhances vehicle stiffness and crash safety. In addition to hydroformed tubes, the NewSteelBody also features numerous components which can be produced at low cost by roll forming. The dash panel cross member is one example, a closed rolled profile with a central inner web - made during roll forming - for added stability. Straight rolled profiles are also used for the side sills, A-pillar and the cross members for the floor panel assembly. Examples of bent rolled profiles include the roof cross member and two girders joining the A-pillar and side member.
The NSB® design not only reduces weight, it also facilitates numerous production processes. For example, the body`s frame structure is so stable that it can be moved in the manufacturing process without the roof, floor or dash panel modules, allowing these parts to added at the optimum time during the production process. What`s more, it becomes much easier to produce model variants: shortening the wheelbase is relatively uncomplicated, requiring only the cutting of the sills and the use of modified floor models and side panels.
Front, rear and side-on collisions were simulated on the basis of Euro NCAP standards. The manufacturer of the reference vehicle provided ThyssenKrupp Stahl with authentic data to ensure comparisons were completely realistic. Doors and the engine hood were also developed under the NSB® project to an extent that guaranteed close-to-reality crash simulations. The technological capabilities available within the ThyssenKrupp Group were also used in verifying the production viability of the NSB®: Key contributions to the success of the NSB® were delivered by ThyssenKrupp Drauz (Automotive segment), a technology leader in the manufacture of demanding hydroformed components, and the Nothelfer Group (Technologies segment), which has a wealth of experience in prototyping parts and entire autobodies.
The NewSteelBody is of modular design, which means that it can be introduced gradually using existing production equipment to a large extent. At the Frankfurt Motor Show, ThyssenKrupp Stahl is displaying part of the front of the body with examples of the key innovations.
ThyssenKrupp Steel AG
Tel.: +49 203 / 52 - 2 62 67
Fax: +49 203 / 52 - 2 57 07
Tel.: +49 203 / 52 - 4 51 85
Fax: +49 203 / 52 - 2 57 07