In November 2006, the Sindelfingen plant began building a pilot installation with which the Daimler engineers are currently further improving the flexible roll forming process while simultaneously making it suitable for production. The participants in the project include not only the Ulm researchers but also engineers from passenger car and commercial vehicle development, production planning, and series production. As early as 2009, the pilot system will be used for the series production of a sill for the E-Class; plans call for the production of CLS-Class components beginning in 2010.

Ideal for vans

One broad area of application is pickup trucks and vans, because a large variety of profiles can be used in their floor structures and box-shaped superstructures. “We’ve studied a great many roll-formable parts that are now constructed as pressed panels and discovered that the new method is more cost-efficient,” says Klaus-Jürgen Benzinger, superstructure manager at the Van Technology Center in Untertürkheim. Here, engineers not only carefully investigate the potential for the current production models but also examine how roll forming can be used for future generations of vans and pickup trucks.

Roll-formed parts with a simple geometry can already be found in Daimler vehicles. “The Mercedes-Benz A-Class has roll-formed sills, the Sprinter has longitudinal members, and the Chrysler brand has bumpers and roof rails,” says Karl-Heinz Füller. However, most of the components of a body-in-white still consist of pressed panels.

Deep-drawing or stamping is still the most commonly used metal forming technique in automotive construction. In this process, a sheet blank is placed in a female die, where it is shaped using a male die and a blank holder. One major advantage of deep-drawing is that it allows manufacturers to create complex shapes. But a number of work steps are usually involved, and that means high tool costs. In addition, these tools are highly susceptible to wear and tear, particularly when super high-strength steels are worked. The net result is that the tool costs for deep-drawing a component are about twice as high as the tool costs for roll-forming a comparable part.