Leichtbaupotenziale im Fahrwerk – Multi-Material-Design durch simultane Umformung von Metallblechen und Urformung von langfaserverstärkten Thermoplasten (LFT)

Modern vehicle construction follows two overriding goals with customer- and market-related
requirements for comfort and safety on the one hand and the lowest possible fuel consumption
and compliance with emission limits on the other hand. Accordingly, lightweight construction
based on materials must, as a supporting pillar within vehicle development, consider both the
safety aspect and the reduction of vehicle mass and thus contribute to the reduction of fuel consumption
and pollutant emissions. In addition to the development of new, high-strength steel
grades produced by hot forming to reduce sheet thicknesses and mixed construction methods
with aluminum and magnesium, fiber-reinforced plastics are also increasingly being used. The
application of this so-called multi-material construction method down to the component level
simultaneously results in a demand for economic and combined manufacturing processes for
hybrid components made of plastics and metal.
This work describes the development of such a production process called “hybrid forming”,
which combines the cold forming of steel sheets with the compression molding of long fiber reinforced
thermoplastics in a simultaneous process step and at the same time connects both materials
by using an adhesion promoter. The required tool and sealing concepts for different geometries
are developed, the joining properties are determined, and relevant process parameters
are identified and optimized. With the aid of a developed design and optimization method based
on the finite elements method (FEM), it will be possible to make steel components up to 20%
lighter by reducing sheet thickness and simultaneously reinforcing them with a ribbed structure
made of fiber-reinforced plastic without losing any of the components’ mechanical properties.
The entire process, from the component and tool design to the manufacturing on series production
lines, is demonstrated using a real front axle control arm.