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PublicationHybrid Thermal Error Compensation Combining Integrated Deformation Sensor and Regression Analysis Based Models for Complex Machine Tool Designs( 2023-06)Thermal errors remain the dominant sources of positioning inaccuracies in machine tools. Various methods of reducing them have already been developed, ranging from cooling and air conditioning strategies, thermally optimized machine tool designs and component optimization to accurate model based thermal error estimation methods used for control-integrated compensation. Some reasons for the limited success of these strategies are the general complexity of the thermo-elastic and thermodynamic processes involved and the fact that many models’ effectiveness is dependent on the machine tool type, workpiece, climatic conditions, tool, CAM strategy, condition of the machine tool and other factors. Depending on these circumstances, all model-based estimation and compensation methods have specific strengths and weaknesses, which make them more suitable in some aspects and less suitable in others. A possible way of circumventing this is via the combination of several methods to hybrid compensation. The goal of this investigation is to develop an effective hybrid compensation strategy for the 5-axis machine tool DMU 80 eVo by combining measurement-based compensation using integrated deformation sensors (IDS) with characteristic diagram based compensation. The former is used for the compensation of thermal errors in the vertical column containing the larger assemblies of the x, y, and z-axis and the latter is used for the table, which contains two rotational axes. The IDS placement has been determined through expert knowledge and compared to placement, which minimizes the variance of the TCP displacement. The hybrid compensation is tested on the DMU 80 eVo.
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PublicationSkalierbare Produktion von Energiespeichern( 2023-05-05)
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PublicationScalable Production of Energy Storage Systems( 2023-05-05)
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PublicationDissolvable Film-Controlled Buoyancy Pumping and Aliquoting on a Lab-on-a-Disc( 2023-01-01)Lab-on-a-Disc (LoaD) has great potential for applications in decentralised bioanalytical testing where speed and robustness are critical. Here, a disc-shaped microfluidic chip is rotated to pump liquid radially outwards; thus, all microfluidic structures must be fitted into the available radial length. To overcome this limitation, several centripetal pumping technologies have been developed. In this work, we combine buoyancy pumping, enabled by displacing aqueous samples and reagents centripetally inwards by a dense liquid (fluorocarbon FC-40), with dissolvable film (DF) to automate a multi-step assay. The DF dissolves in the presence of water but is not in contact with the FC-40. Therefore, the FC-40 can be stored behind the DF membranes and is autonomously released by contact with the arriving aqueous sample. Using this technology, tasks such as blood centrifugation can be located on the disc periphery where ‘disc real estate’ is less valuable and centrifugal forces are higher. To demonstrate this, we use the combination of the buoyancy-driven centripetal pumping with DF barriers to implement a fully automated multi-parameter diagnostic assay on the LoaD platform. The implemented steps include plasma extraction from a structure, automatically triggered metering/aliquoting, and the management of five onboard stored liquid reagents. Critically, we also demonstrate highly accurate aliquoting of reagents using centripetal pumping. We also provide a mathematical model to describe the pumping mechanism and apply lumped-element modelling and Monte Carlo simulation to estimate errors in the aliquoting volumes caused by manufacturing deviations.
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PublicationSuitability of stainless steel and plastic belts for digital printing( 2022-11-24)In this study the dynamic characteristics of steel and plastic conveyor belts regarding belt vibrations were carried out. The analysis showed major differences between the different materials as the measured vibrations of the plastic belt were four to six times higher compared to the steel belt. FurtherÂmore, a reduction of vibrations with an increasing belt speed was determined for both belt types. We further investigated whether a local reduction of belt vibrations is possible by using air bearings. The tests showed a reduction for both belt types. The use of air bearings in combination with a steel belt could be carried out successfully. In contrast, running noises were detected with the plastic belt used. This is attributed to a non-stable air film due to a rough running surface. The suitability of alternative plastic belts with a smooth running surface must be examined. In the last part of the study a reduction of belt vibrations has been determined by increasing the of belt tension using a steel belt.
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PublicationIntegration of bio-based insulation materials as a contribution to the biological transformation of production technology( 2022-07-08)In the context of a circular economy, the adoption of biological principles and materials play a decisive role in the transformation to a more sustainable production technology. Ecologically harmful materials such as polystyrene (so-called Styrofoam), for example, has properties for thermal and acoustic isolation. This material has therefore been used in production machinery to control thermal issues and improve product quality. Here, the use of renewable and biodegradable materials can ensure these measures have a minimal environmental footprint while maintaining the intended functionality. This paper serves to open-up opportunities and define requirements for the integration of bio-based isolation materials in production machines. For both thermal and acoustic issues, the place of implementation and the choice of insulation material, as well as its shape and composition, determine the ability to isolate over the required temperature range. In addition, coatings and surface functionalization offer possibilities for using bio-based materials even under demanding process conditions. Concluding, the experimental approach on the effectiveness of bio-based insulation materials within a machine tool is presented. The technologies presented in this work have been developed by the participating Fraunhofer institutes.
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PublicationInvestigation of thermally induced TCP-displacement under load of the machine axes in different areas( 2022)As known, thermally induced displacements can cause up to 75% of workpiece errors. To investigate the structural deformation of the machine, Integral Deformation Sensors (IDS) were developed. With these sensors the deformation of machine parts can be measured, and the resulting tool center point (TPC) displacement can be analyzed and predicted by a mathematical model of the machine. This paper focuses on the analysis and prediction of the machine deviation under load of the machine axes in different areas. As machine tools can hardly be built completely thermically symmetrical, the influence differs, if an axis is only moved in a certain area or along the whole way that the axis can be moved. In this paper, the impact of this fact on thermally induced displacement is investigated in several tests. By doing so, the component deformation is analyzed by IDS. Furthermore, the TCP dislocation is analyzed by modelling it simultaneously by IDS and measuring and the actual displacement using 3D probe. The results show not only the measured displacement of the TCP but also the correct prediction based on the data gathered from the IDS and therefore prove that the compensation method based on the IDS can increase the machines robustness against thermal issues.
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PublicationSelbstlernende Produktionsmaschinen für die automatisierte Fertigung von Lichtsystemen( 2022)Core elements of modern production machines for the automated manufacture of lighting systems are complex algorithms that analyses light distributions inline and actively correct them. This enables products of the highest quality to be manufactured with minimal waste. The Fraunhofer IPT is researching the use of artificial intelligence for industry-ready solutions that are capable of learning complex beam analyses and alignment processes automatically. This reduces the development effort and thus paves the way for innovative products and assembly processes.
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PublicationThe Time Synchronization Problem in data-intense Manufacturing( 2022)Modern production systems rely heavily on data from the machines, processes and other sources. The amount and resolution of the data increases continuously allowing complex models like Machine Learning models to be trained and applied in production. All analytics and models that rely on the production data implicitly require a suitable data quality. Central level of data generation and acquisition is the machine level where data from machine and sensors are generated and need to be aggregated. In this paper, we define the Time Synchronization Problem that arise from the different data sources and technical properties of computerized systems in manufacturing directly impacting the quality of Time-Series data. Further, we cluster current approaches and discuss their applicability in data-intense manufacturing.
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