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PublicationDesign of freeform optic module creating a ring-shaped laser beam profile for localized heating of sheet metals( 2023-09-28)Laser-based preheating is an energy-efficient method to locally enhance the formability of a metal sheet. A ring-shaped beam can be used for preheating in the flange forming process. According to the tailored heat principle, only the area to be formed is heated. In this paper, a method is presented to design modules with reflective freeform optics (FFO) that converts a collimated Super-Gaussian beam into a ring-shaped beam at a working distance of e.g. 170 mm and deflects the laser beam by 90° simultaneously. The FFO design is based on a 2D geometric model of the optical system and is iteratively optimized according to the process requirements. The FFO was manufactured by fast tool diamond turning and placed into an integration model within a progressive die tool. The design was verified by beam profile measurement as well as by analyzing the formed part quality.
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PublicationSystem development for active deviation compensation in laser-based wire micro deposition using image recognition( 2023-09-13)Gold plating is used to protect electrical components from corrosion and enhance functionality. A sustainable alternative is localized laser-based wire deposition: Using a laser scanning system, micro gold wires are welded into gold spots locally on the component surface. However, process and system tolerances lead to deviations between the target and actual weld positions. This paper presents a system for active deviation compensation using an on-axis camera and image recognition algorithms. Different adaptive thresholding methods and image processing algorithms are used to determine the welding target position on the part. The actual welding point of the wire on the component is calculated and transferred to the scanner as the new welding position. An approach for designing such a system for active deviation compensation and the possibility of higher-level communication with industrial controls is presented.
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PublicationScalable Production of Energy Storage Systems( 2023-05-05)
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PublicationSkalierbare Produktion von Energiespeichern( 2023-05-05)
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PublicationA Digital Twin for estimating Process Quality during Automated Fiber Placement of Thermoplastic Composites( 2022)The digital twin (DT) is a methodology accelerating process knowledge for the automated fiber placement (AFP) of unidirectional thermoplastic tape with in-situ consolidation. It implies a continuous assessment and evaluation of data allowing a faster process optimization and reducing ramp-up times. This study visualizes measured data within an automated digital shadow and combines it with analytical models for the AFP of thermoplastic composite blanks with in-situ consolidation. A DT combining analytical and experimental data is created visualizing quality indicators of a thermoplastic composite blank during manufacturing. In this study, a model predicting the degree of bonding is selected calculated based on the measured temperature data. The results show how a DT enables an easy and systematic method to analyse and optimize the AFP processing. It is a promising tool for automatizing process analysis and part quality estimation during the manufacturing of composite parts.
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PublicationAn energy efficient production technology for the recycling of thermoplastic tape into a new semi-finished product for further use( 2022)To use fibre reinforced plastics in a sustainable and economic way recycling processes have to be an integral part of the product life cycle. Existing recycling processes for composite materials, however, have low energy efficiency, do not consider fibre orientations or use environmentally harming chemicals. In this study, a solution is developed for the recycling of fibre reinforced thermoplastic tape material in the form of tape offcuts, which accrue in production processes. This new process produces recycled tape material, so called "rTape", for further use. In the study, application scenarios for the rTape are defined and a structure for the tape is developed to fulfil these requirements. The main focus of the development process is to realise an energy efficient process by minimizing the separation of fibres and matrix material as this bond can be used further in the recycled product. The rTape uses non-continuous fibres in the tape and a defined fibre orientation for good material properties. Material tests show that tensile strength values of rTape tested in this study has the potential to be in a range up to 76 % compared to new, unrecycled tape. The results of the study are a basis for further development of the proposed recycling process and an automated system to produce such rTape.
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PublicationManufacturing of Bio-Based Thermoplastic Fiber-Metal-Laminates Using a Novel Consolidation Process( 2022)Hybrid materials made of fiber-reinforced polymers (FRP) and metals offer great potential for a wide range of applications by synergistic combination of each material’s benefits. Compared to monolithic materials and traditional FRP, fiber-metal laminates (FML) can provide more versatile functionality, better insulation capability and higher weight-specific mechanical properties like impact strength and damage tolerance. However, the production of thermoplastic FML is currently based either on discontinuous manufacturing processes or resource-intensive impregnation presses. In addition, the combination of dissimilar materials results in difficult material separation or recycling. The Fraunhofer IPT has developed a continuous and resource-effective consolidation process to manufacture thermoplastic FML that are fully recyclable. During the impregnation and joining process, thin metal belts serve as tools for heat and pressure transfer, which finally form the top layers of the sandwich material. To achieve a strong bond between the core and top layers, a laser-based structuring process for metal surface treatment is used, eliminating the need for poorly recyclable bonding agents. This paper describes the developed process and compares it with traditional production methods. Experimental test results for flax-PLA based FML are presented to show the feasibility of the developed process and the potential for industrial applications.
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PublicationCost-effective production of glass fibre reinforced towpregs( 2022)
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PublicationThermoplastic laser assisted tape placement development for processing a novel carbon fiber reinforced polyphtalamide tape( 2022)
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PublicationWertschöpfungskette Brennstoffzelle( 2022)
