Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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Performance analysis of an adaptive cooling system with primary and secondary heat paths for linear direct drives in machine tools

2022 , Uhlmann, Eckart , Salein, S.

Machine tools subjected to high demands regarding productivity and accuracy are faced with the challenge that thermal losses influencing the accuracy negatively. Due to high requirements regarding thermal stability of precision related machine tool components, the focused linear direct drives (LDD) must be tempered by active cooling systems. In machine tools, a sufficient cooling capacity is available, but the cooling is insufficiently adjusted to the process and the individual demand of the heat-inducing as well as precision related components. With the intention to achieve a demand-oriented cooling, the use of thermoelectricity in machine tools is one research objective at the Institute for Machine Tools and Factory Management (IWF). Inspired by the concept of thermoelectric self-cooling (TSC)-systems for electronic devices, an Adaptive Cooling (AC)-system with thermoelectric generators (TEG) for LDD in machine tools is developed and experimentally investigated. In order to enhance the performance of AC-systems, in this research a reduction of the global thermal resistance is focused. A promising approach to achieve this goal is the division of the induced heat flow into a primary and a secondary heat path. For a model-based performance analysis of this approach, a system simulation is presented. To acquire experimental data for model validation, a test bench of the AC-system with primary as well as primary and secondary heat path is put into operation. The comparison of simulative and experimental determined data indicates a predominantly high model prediction accuracy. As a result, the implementation of a secondary heat path enables a reduction of the temperature on the upper surface of the heat source by 24.6% and thus a decrease of the global thermal resistance by 38.1%. Compared to the initial state of the AC-system only with primary heat path, the achieved thermal stability in the precision related machine tool component as well as the self-starting capability is improved.

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Automated 3D scan based CAD-repositioning for design and verification in one-off construction

2021 , Mönchinger, Stephan , Schröder, Robert , Stark, Rainer

The presented engineering discipline one-off construction is characterized by a multiplicity of manual processes. As almost all modern product developments, the manufacture is based on the creation and consistent use of digital models. Quality of underlying data can vary greatly and it is not certain that digital models match the actual state of construction. This can result in the need for rework after production or installation. Especially challenging in the area of premium products, for which high quality, scarce materials are used and tight schedules are defined. If physical products are reworked, the corresponding digital models must be manually maintained. At present, attempts are being made to counteract these late adjustments by means of physical mock-ups or visual inspection of 3D scan data. Such scan data is used for automated adaptation of underlying digital models to the actual state of the physical construction. Existing Point Cloud Library functionalities were adapted and further algorithms were designed. The developed software backend was integrated into the existing software architecture. During the software development, great care was taken to ensure that the backend is based on open source content. The results show significant improvements of the data basis for the subsequent engineering activities. This will lead to a significant reduction of manual effort and rework, ensuring development cycles and even shorten delivery times. It reduces costs in the product creation process and sustainably strengthens confidence in digital models used. It has been shown that automation of design processes can have productivity-enhancing effects in one-off construction.

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Increasing resource efficiency with an engineering decision support system for comparison of product design variants

2019 , Buchert, Tom , Ko, Nathanael , Graf, Roberta , Vollmer, Thomas , Alkhayat, Moritz , Brandenburg, Elisabeth , Stark, Rainer , Klocke, Fritz , Leistner, Philip , Schleifenbaum, Johannes Henrich

The development of sustainable and resource-efficient products requires consideration of multiple design targets concerning the whole product life cycle. Taking these factors into account leads to complex decision situations with conflicting targets and trade-offs. To support design engineers in these situations an Engineering Decision Support System (EDSS) has been developed. In this article, the overall concept of the EDSS is presented. Furthermore, one function of the EDSS to assist a systematic comparison of product variants is introduced in detail. It is based on combining an existing PLM solutions (in particular Siemens Teamcenter 11/Siemens NX9) and software for Life Cycle Assessment (GaBi 7). Beyond a proof of concept for information exchange between both systems a methodology is presented which enables design engineers to systematically assess and select multiple product variants based on their resource utilization. The approach is complemented with a comprehensive case study for different design options of a core slide. In the scope of this study, variations of geometry (solid vs. hollow design), materials (hot-working steel vs. nickel-based superalloy) and manufacturing processes (laser metal deposition vs. milling) were considered. Furthermore, a usability study of the decision support tool is shown.

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