汽车铝应用手册_AAM_roof-and-trim_5_6.pdf

Applications – Car body – Roof and trim Table of contents 5 Roof and roof structure 2 5.1 Aluminium roof on a steel body 2 5.2 Roof structure 4 5.3 Sun roofs 6 5.4 Detachable hardtops 8 5.5 Retractable roofs 9 5.6 Roof rails 11 6 Trims 14 Version 2013 © European Aluminium Association (auto@eaa.be) 1 5 Roof and roof structure The use of aluminium for the car roof is well established in all-aluminium car body designs (see chapter 3.3). But there are also significant aluminium applications in the roof of vehicles with steel car body structures. Weight reduction in the roof (i.e. lowering the centre of gravity) has always been a high priority topic in automotive design. However, the roof is generally an integral part of the body-in-white. Therefore, the integration of structural aluminium components into the roof of a steel body structure requires an in-depth consideration of different aspects (as outlined below). 5.1 Aluminium roof on a steel body The substitution of the steel roof panel by a lightweight aluminium alloy roof panel is an attractive option to optimize the mass distribution in a car. However, if the remainder of the vehicle body structure continues to be fabricated in steel, two major hurdles have to be overcome. The first problem is the realization of a reliable joint between the different materials. Various technologies have been developed to join aluminium to steel; in most cases, adhesive bonding combined with a mechanical joining technique is applied, but also friction stir welding, soldering or fusion welding methods have been developed. If the mixed material joint is properly protected to avoid any danger of galvanic corrosion, a safe and durable joint is achieved. The other problem is the different thermal expansion coefficient of aluminium and steel. The combination of the aluminium alloy roof attached