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Item type:Publication, Access status: without files , Sensor-guided machining of large-scale CFRP components based on resin transfer molded featuresCarbon fiber-reinforced Plastics (CFRP) are a key factor for achieving a carbon-neutral mobility sector due to their lightweight properties. Despite their near-net-shape manufacturing subsequent precision machining is required. In case of large-scale CFRP components, which are characterized by small quantities and low machining volumes, such processes are difficult to operate economically with conventional systems. Robotic systems offer a suitable solution. Their use in machining, however, requires additional measures to compensate for structural system limitations. In addition, individual deviations of the blanks require time-consuming measuring for referencing the machining system. To enable the use of cost-efficient robotic systems and to eliminate unproductive downtime for measuring, the intended manufacturing of CFRP components by Resin Transfer Molding (RTM) offers a new opportunity. RTM allows for the integration of defined features into the molding tool, which are reproduced inverted on the component and can be referenced by subsequent processes. This is utilized with adapted strategies for time-efficient measuring and high-precision machining. Fundamentals for the corresponding feature design as well as the selection of a suitable measuring device are presented. Focusing on laser-based sensors, the relationship between wavelength and (semi-)transparent surfaces is discussed and validated. Besides the metrological detection, production-specific aspects are also taken into account. Based on the gained knowledge, the main aspects of a proper sensor-feature combination are elaborated and prototypically realized. Finally, an outlook is provided on the challenges involved when implementing a robust algorithm for feature detection.Publicationtype: Conference Paper42 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Accuracy Analysis for a Flow Line Process using a Mobile Holding Fixture for Machining CRFP Components (SAE Paper 2022-01-0041)The aerospace sector is challenged to produce airplanes more efficiently and resiliently in the future. This leads to an increasing demand for improving productivity and flexibility as well as providing solutions for sustainable developments. A bottleneck in production is the machining of large-scale components. Apart from the machining tasks, non-productive operations like fixture adjustment, component handling, referencing and localization are performed within the machining station and can constitute up to 50% of the overall workload. In the UniFix project, Fraunhofer IFAM is participating in the development of a mobile fixture system for large-scale aircraft components, like vertical tail plane and landing flap components of the single aisle aircrafts. By installing components into a mobile holding fixture with an according referencing scheme, a flow line can be established that is composed of specialized workstations discharging the machining station from non-productive processes, leading to higher productivity. This paper focusses on the component localization and referencing strategies for this mobile holding fixture. Here, specific challenges are caused by the transport in between the referencing and the machining process. Therefore, influences that contribute to the overall geometric uncertainty of the referencing process for machining are evaluated in detail. In this work, an automated laser scanner based localization of the components will be presented. Furthermore, estimations on the uncertainty in the involved systems will be conducted and propagated through the localization process.Publicationtype: Conference Paper68 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Sensor based online quality monitoring system for detection of milling defects on CFRP structuresIn the aviation industry, increasing research and applications of carbon fibres have led to a higher demand of carbon fibre reinforced polymer (CFRP) material. The moulding process of CFRP material is not precise enough to be directly moulded into its end form and an additional machining process is required. The machining of CFRP materials can result into generation of defects such as fibre overhang, cracking and delamination. Normally, the visual quality checks are carried out after machining is completed and hence, the damage at the end of the process is significantly more which can result into rework or rejection of the product. To solve this problem, an online quality monitoring system was developed in which the defects were measured, processed and identified online during the milling process. In order to achieve this, a line sensor was mounted behind the tool, which followed the tool and captured the data of the edge while milling. In the end, defects such as fibre overhang and delamination were detected simultaneously during the milling process.Publicationtype: Journal Article17 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Mobile Laser Trackers for Aircraft Manufacturing: Increasing Accuracy and Productivity of Robotic Applications for Large Parts(2019-03-19); ; ; ; The demand for higher production rates of large parts in aircraft industry requests more flexible manufacturing solutions. High-accurate mobile robots show a promising alternative in comparison with high-invest special machines. With mobile robot-based solutions processes can be executed simultaneously which increases the productivity significantly. However, the freedom of mobility results in insufficient positioning accuracy of these machines. Hence fast and accurate referencing processes are required to achieve cost-effectiveness and meet production tolerances. In this publication a Mobile Laser Tracker (MLT) system and a holistic approach for future manufacturing systems with mobile robots will be introduced and discussed.Publicationtype: Journal Article371 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Digital assistance systems for smart drilling units in aircraft structural assembly(Shaker Verlag, 2019-02); ; ; ; Publicationtype: Conference Paper205 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Referencing strategies for high accuracy machining of large aircraft components with mobile robotic systems(Soc., 2017-09-19); ; ; ; The demand for higher production rates in aircraft industry requests more flexible manufacturing solutions. A bottleneck in production is the machining of large components by vast portal machines. Time-consuming referencing processes result in non-satisfying cost-effectiveness of these high-invest-machines. Mobile robot-based solutions are able to operate simultaneously which increases the productivity significantly. However, due to the limited workspace of robots, machining tasks have to be divided and long trajectories are separated in single overlapping segments. Thus high-accuracy referencing strategies are required to achieve desired production tolerances. In this publication different advanced optical reference strategies will be discussed taking the inhomogeneous behavior of a mobile robotic machining system into account. Investigations on the absolute positioning and the machining accuracy will show the impact of different referencing strategies on sub-scale machining especially for large work spaces.Publicationtype: Journal Article174 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , High accuracy mobile robotic system for machining of large aircraft componentsA mobile robotic system is presented as a new approach for machining applications of large aircraft components. Huge and heavy workshop machines are commonly used for components with large dimensions. The system presented in this paper consists of a standard serial robot kinematics and a mobile platform as well as a stereo camera system for optical measurements. Investigations of the entire system show that the mechanical design of the mobile platform has no significant influence on the machining accuracy. With mobile machines referencing becomes an important issue. This paper introduces an optical method for determining the position of the mobile platform in relation to the component and shows its accuracy limits. Furthermore, a method for increasing the absolute accuracy of the robots end-effector with help of stereo camera vision is presented. This publication shows that the mobile robotic system yields an efficient possibility for advanced machining processes of large-scaled aircraft structures in the Factory of the Future.Publicationtype: Journal Article136