Abstract

Landing gear doors / traps are usually composed of sandwich structures manufactured by hand lay up and cured in autoclave. In the present development, this type of construction and its associated manufacturing process have been replaced by a monolithic design manufactured by liquid composite moulding. Specifically, the selected process has been RTM (Resin Transfer Moulding) in a single process of impregnation / curing (one shot) with the objective of eliminating subsequent operations. In order to obtain a 3D integrated preform close to the final shape, pre-forming processes have been developed for the sub-elements of the part (skin, double T stiffeners, C stiffeners, etc.) as well as the processes of integration of the various preforms until obtaining an integrated preform. The preforming and manufacturing processes have been fully validated by obtaining real-size prototypes of the target part. This work is included within the ATEAERO project, with the support of the ETORGAI program (SPRI - Basque Government).

Abstract

The use of polymer matrix composites and, in particular, based on carbon fiber, is awakening more and more interest in the automotive sector, due to the great weight reduction potential they offer for the lightening of vehicle structures. The case of the BMW (with the i3, i8 and 7 Series) and some other manufacturers, represent the first cases of use of "large scale production" with these materials, with a growth perspective provided by the electric vehicle. To achieve a mass implementation of these new materials it is a key factor the development of processes and equipment that allow manufacturing with very short cycle times.

Preforming is the key stage where the fiber stacking takes the form of the injection mold in which it will be introduced later. This stage of the process is the one that has a greater impact on the cost of the overall process, so it is especially necessary to develop optimization and automation techniques for rapid preforming.

In this context, Fagor Arrasate, with the aim of offering its customers a competitive installation, has created and led a project in which it has collaborated with Tecnalia to develop pre-forming installations for the automotive sector.. A fast preforming process based on preheating and cold stamping has been developed combined with an automatic material feeding based on a transfer system and also completed with the automation of the initial stacking and the trimming of the final preform. The capabilities of this installation have been validated for an automotive demonstrator.