The research carried out at the ZLP site at Stade focuses on the manufacture of very large, complex components in high-production fibre placement processes and sensor-guided component-specific control of thermally inert curing processes in autoclaves and open moulds. The researchers in Stade are also working on fully automated manufacturing of high-volume components using dry textile semi-finished products in the resin transfer moulding (RTM) process. As well as for the aerospace sector, the processes being developed are also intended for applications in the automotive industry and for the production of rotor blades for wind energy systems.
For these research activities, the ZLP site at Stade has been equipped with the following innovative research facilities:
The Center for Lightweight-Production-Technology (ZLP) aligns within the programmatic research approach of the German Aerospace Center (DLR) with its core disciplines in aeronautics, space, transport and energy. ZLP seeks to enhance aeronautical research by taking production technology into account, which complements the interdisciplinary approach of DLR in research on the air transport system. Thus, fundamental assessment capabilities beginning with materials up to maintenance, repair, overhaul (MRO) will be researched. The ZLP in Stade is integrated into the building complex of CFK Nord. It covers part related technologies for fuselage production, wing production, the empennage, rotor blades as well as the automated RTM process as it will be used for both automotive application or the frame production of aircraft.
Credit: DLR (CC-BY 3.0).
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Today’s production of large scale parts out of CFRP is dominated by the use of prepreg material. Machining development has reached a high level of maturity for this purpose, but the existing single layup systems cannot meet the demand of high productivity needed for aircraft production in high quantities. Due to this, a multi layup approach is done within the ZLP to demonstrate high productivity on an industrial scale.
The project covers the development of production processes for large scale, highly integrated components made of composite materials in automated fiber layup technologies. In this regard, a research facility is developed on the basis of several coordinated, robot based layup units that can be moved on a rail system. The rail system is split into a manufacturing loop, that allows a circumferential movement around a double-sided molding tool and a connected maintenance loop. In addition, the robot units are equipped with fiber placement or tape laying heads that can be used simultaneously and enables a high flexibility of the manufacturing process. The aim of the project is the development of a production technology that allows a lay up rate of more than 150 kilograms per
Autoclaves are today and in the longer term an integral part of the chain of production of CFRP components. Through the processes taking place in the autoclave, the system influences the material properties and component geometry. Therefore, procedures are to be designed with respect to the parameter measurement, simulation and presentation of heat transfer processes. One aim of the project is the recording of the exact temperature distribution on the component in order to minimise heating and holding times by new criteria for the autoclave controls. Hence, a procedure for quality-assured production of large structures of carbon fibre will be developed.
To gain a fundamental understanding of industrial processes an industrial scale was considered by the size of the autoclave which was chosen to have an inner diameter of 5.8 metres and a loading length of 20 metres. The overall objective is the most cost-optimised production of high quality large components with small production variations. This should be obtained by using a thermal and pressure management for time optimisation and quality assurance during the process. A representation of the technology on an industrial scale is necessary, because a lot of effects can not be simulated in the laboratory.
Due to their cost effectiveness and good material properties, epoxy resins are used for most high performance composite parts. But those parts have not yet conquered the mass market, as no production technology appears capable in delivering high quantities of parts. This is mainly driven by a still high degree of manual labor in today’s production technology. To introduce composite components in high quantities to the market, process technology has to be created first. Short cycle times, automated handling, material development are in the focus of the current demand. Within the project’s approach the fundamental engineering is done for the development of a production facility with a productivity of 100,000 complex composite parts per annum.
To increase the degree of the technology’s maturity ZLP focuses on:• The fully automated production chain for complex composite parts, • The reduction of manufacturing costs through automation, and • The reduction of process times. Due to the demand of flexibility of the process chain the following different component classes are in the scope of research:• 3D-scale components with complex partial structures, and • Curved, profiled frames. In both the aeronautic and automotive industries an application is provided.