Process Chain for Industrialized Rotor Blade Production set in Motion
Following commissioning of the production portal last spring, Fraunhofer IWES has now reached the next milestone in the BladeMaker joint research project: the integration of the process steps as the basis for a prototypical end-to-end process is now under way. The first step is production of the first shear web with direct infusion, followed by shear web manufacturing with PUR foam core elements, the production of the first half of the form tool, and the testing of a new gripper principle for the handling of cuttings. By completion of the project at the end of this year, all of the optimized processes will be merged and adapted to the production sequence. The 16 project partners have set them-selves the goal of savings of at least 10 percent in rotor blade production along with noticeable quality improvements.
Furthermore, the degree of automation in the production workflow should be increased to around 60 percent. To do so, the industrial approach developed in the project draws on new materials as well as optimized processes and illus-trates the advantages of this production method taking a blade design developed by IWES itself by way of example. The blade design was based on a simplified turbine model with a capacity of 1.5 MW developed by IWES scientists. A prime example from the field of process technology is the production of the blade mold without a master plug, which allows considerable time savings of several weeks. The production of the mold for a rotor blade generally requires the creation of a master plug. Following this stage, the next step requires the form to be shaped manually in accordance with the blade geometry.
In combination with a project partner’s corresponding CAD-CAM tools, the use of a computerized numerical control makes it possible to pass the design data on to the production planning team directly. The same should occur for all hardware-dependent processes. In the BladeMaker project, the mold for the 18-meter-long root segment of a rotor blade measuring 40 meters in total has just been produced without a master plug. This direct tooling approach allows time savings totaling approximately two weeks. The mold is completed with a carbon fiber-based electrical heating system.
Shear web core made of PUR cuts costs
The shear web is often manufactured as a sandwich construction, which results in high rigidity and low weight. This component is one of the central parts em-ployed to increase the buckling strength of a blade. The aim in the BladeMaker project is to produce the core of the shear web from polyurethane (PUR). In-stead of kits made from PVC, for example, large-scale elements are prefabri-cated and inserted. The advantage: cost savings. The shear webs produced in Bremerhaven, both conventional and adapted versions, will be finished in the next few weeks and then inserted with a special tool (shear web positioner) which ensures optimal positioning within the half shell.
Innovative gripper principle for positioning cuttings
Yet another approach has been developed for the handling of stacked cuttings with high surface weights and fixed preforms: A gripper grasps multiple flat cuttings and places them on a support, where the next step of the shaping is performed. The shaped stack is then positioned precisely in the form tool using the gripper system. "Robot-assisted cutting positioning, either directly or as a preform, translates to noticeable time savings, increases the precision, and ensures a consistent level of quality,” said Christian Dörsch, the team lead, sum-ming up the advantages of the technique.
Completion of the integration and demonstration of all of the sub-processes is planned by the end of the project at the end of 2017: The machines need to be set precisely: The changing of the process heads and thus the changeover to the next production step, performed at the same machine space, demands exact coordination. There is still a way to go before the proprietary BladeMaker blade segment can enjoy its “maiden voyage” along the entire process chain. The demonstration center is already opening its doors to blade manufacturers, suppliers of materials for rotor blade production, and the mechanical engineering industry for test runs with their own or provided molds and materials, with the aim of identifying potential for additional cost savings in the production chain.
Key project data:
Project partners: BASF, EMG, EEW Protec, Faserinstitut Bremen (FIBRE), Fibre-tech composites, Fraunhofer IFAM, Fraunhofer IWES, Henkel, Hexion, PD Group, Schmalz, Siemens AG and Siemens Industry Software, Sinoi, University of Bremen/BIK, 2KM
BMWi grant: € 8 million, contribution from industry: € 6 million