Efficient and sustainable rotor blade manufacture enabled by online quality assurance systems in combination with low-waste resin flow control

Abstract

Wind turbine blade manufacturers are confronted with increasing challenges regarding quality assurance and recurrent costs in the production of rotor blades which are getting larger and larger with each design cycle. The increasing size of the blades demands for a guaranteed product quality during production due to the high value which is given by the material costs and the effort in form of labor costs which have to be put into the creation of a rotor blade of the newer generations with length of 80 m and more. Quality assurance methods and equipment feasible for rotor blade production are still hard to find today. DLR has developed a method suitable for blade production based on available sensor technologies and has validated it in several production trials in its prototype blade form of 20 m length. The system consists of a mobile optical measuring cell, which is able to check all quality-relevant parameters during blade manufacture. It consists of a thermographic camera which is mounted on a mobile rack and which, in combination with several thermocouples in the mold, enables the measurement of the temperature distribution of the entire component during the curing process. Furthermore, high-resolution cameras, infrared and laser systems are integrated in order to supplement the process monitoring by means of fibre angle detection, leakage detection and construction thickness measurement. With this set of described measurement systems, it is possible to monitor the relevant quality parameters during infusion and curing of rotor blade components. An appropriate computer and software system allows the collection, processing and analysis of the gathered data, which in combination with a database also takes over its documentation. The system enables a more efficient curing process. Furthermore live data analysis can be used to improve the production regarding repeatability and process reliability. It can also be used as a basis for process automation. Post analysis allows for the application of Industry 4.0 approaches, resulting in an increase in process efficiency and a reduction of production defects and rework actions. This approach for online quality assurance can be combined with an active control of the flow front of the resin using the method of temporary usable channels in the vacuum bagging which can be used to control the resin distribution. To realize this effect specific low cost devices are put on top of the vacuum bagging. A separate, controlled vacuum system is used to create the temporary channels in the vacuum bagging and achieve the guided resin flow. It has been proven that these devices leave no detectable channel marks on the surface of the produced product. An additional advantage is the possibility to abstain from the use of distribution media and other auxiliary production material, including the caught and lost resin inside these materials. In addition the specific low cost devices are reusable several times which in summary leads to a significant reduction of the recurrent costs in production. In the presentation the mentioned supporting systems for efficient and sustainable production will be explained and the proofs of its validities will be discussed in detail.