Johnson Controls, a global multi-industry company, is investing in an automotive research project that combines two approaches to lightweight construction for the first time. The partners from science and industry are working on tailored tubes made of a hybrid of steel and aluminium. The result could be a 10 to 20% reduction in weight, which would be beneficial for fuel and emissions balance.
Tailored tubes are already used to a great extent in the large series production of vehicle seats, but here they consist of steel and aluminium of various wall thicknesses. As part of the research project 'Hydroforming of laser-brazed tailored hybrid tubes of a steel-aluminium blend for automotive lightweight construction (IHU-THT)' underway since March 2014, project partners are researching the opportunity to make use of the significant weight advantages of aluminium by combining it with steel in the hollow components.
"The primary challenge is first connecting the steel and aluminium tube segments," explained Andreas Eppinger, group vice president technology management, Johnson Controls Automotive Seating. "The hollow components are given their final geometry by means of hydroforming. Conventional bonding processes such as welding are not suited for the connecting welds between aluminium and steel because they cannot withstand the extreme pressure from the fluid medium during the hydroforming process."
The research team, consisting of scientists from the Institute for Integrated Production (IPH) and the Hanover Laser Center (LZH), is using laser-brazing to create a sturdy and durable weld. During the project's 24-month duration, scientists, companies in the field of laser technology, and automotive suppliers and manufacturers will be working intently to optimise the production process and prepare for industrial applications such as automotive body parts, impact protection for doors and seat cross members.