Now showing 1 - 10 of 160
  • Publication
    Nachhaltige Reinigung und Präparation
    In der Fertigungstechnik lautet aktuell die Devise, innovative Wege für mehr Nachhaltigkeit zu entdecken. Für industrielle Reinigungsprozesse ist das CO2-Strahlen auf dem Vormarsch - im Beitrag wird beschrieben, warum.
  • Publication
    Semi-automatic process control for efficient refurbishment of turbine blades
    ( 2023-06-16) ; ;
    Mühlich, Christopher
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    Ebrahimi, Puya
    The refurbishment of turbine blades requires the precise removal of damaged surface coatings. In manufacturing companies, this usually involves time-consuming activities such as detecting residual coatings and adapting process settings to varying turbine blade geometries. The use of automated systems therefore opens up opportunities to improve the efficiency of turbine blade refurbishment processes by replacing manual tasks. This paper presents an conceptual approach for a semi-automatic decoating process of turbine blades that integrates abrasive blasting technology into a closed loop process control system. The experimental setup consists of a robot for guiding the turbine blade in a blast machine and a nozzle system for local removal of residual coatings using abrasive material. Based on image processing the residual coatings of a turbine blade are labeled by a neural network and mapped to a 3D model of the turbine blade, which is used by a software control system to coordinate the decoating process. Using a prototype setup this paper investigates the applicability of the proposed approach and evaluates its feasibility.
  • Publication
    Cooling Capacity of Oil-in-Water Emulsion under wet Machining Conditions
    ( 2023)
    Nabbout, Kaissar
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    Sommerfeld, Martin
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    Barth, Enrico
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    Bock-Marbach, Benjamin
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    Many industrial machining operations are carried out under wet machining conditions. Modelling and simulating fluid-structure-interactions and conjugate heat transfer are still a challenge nowadays. In this paper, temperature dependent heat transfer coefficients (HTC) h(T) are experimentally estimated for wet machining-like conditions in a jet cooling experiment. The transient temperature is thereby used to solve an Inverse Heat Transfer Problem for HTC function estimation. Determined HTC are applied as input in related jet cooling simulation using the Finite-Pointset-Method (FPM) to validate the modeling approach. Additionally, wet cutting simulations numerically highlight the influence of determined HTC h(T) on turning.
  • Publication
    Enabling of Automatically Generation of Cutting Paths for Three-Dimensional Pre-Contouring with Waterjet Trimming
    ( 2023)
    Reder, Waldemar
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    Abrasive Water Injector Jet Cutting (AWIJC) is a flexible machining process for manufacturing high-performance materials, such as titan-and nickel-base-alloys. Due to the low ductility and thermal conductivity of these materials, conventional machining is struggling with high tool costs and wear. The tool wear in AWIJC is independent of the machined material, and the process has the potential to provide a cost-efficient solution in machining high-performance materials. Trimming, a near-net-shape pre-contouring with multi-stage AWIJC, requires a detailed knowledge of cutting paths for all steps in advance. In order to enable a geometrical flexible manufacturing process, an automatically cutting path generation is necessary. This article presents an application developed with NX Open using Visual Basic. The application TrimCAD is able to provide all necessary geometries for trimming based on the geometries of initial and finished parts. Furthermore, it is possible to adjust the number of cuts and the degree of pre-contouring. All geometries are automatically exported as a standardized three-dimensional STEP-file. The STEP-geometries can be processed to the CAM-processor of the waterjet machine. TrimCAD is an innovative possibility to machine three-dimensional parts made of high-performance materials.
  • Publication
    Deliberate Surface Treatment of Zirconium Dioxide with Abrasive Brushing Tools
    ( 2022)
    Hoyer, Anton
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    Brushing with bonded abrasives is a flexible finishing process used to reduce the roughness of technical surfaces. Although industrially widespread, especially for the finishing of metallic surfaces, insufficient knowledge of the motion, the material removal, and the wear behavior of the abrasive filaments complicates predictions of the work result. In particular, the reliable finishing of ceramics with bonded diamond grains proves difficult due to increased material removal rates, quickly leading to undesirable changes in the workpiece geometry. Based on technological investigations with abrasive brushing tools, this article provides insights into the surface finishing of zirconium dioxide with a focus on finding compromises between reduction in the surface roughness and alteration of the workpiece shape.
  • Publication
    Process behaviour of segmented and actuated tool electrodes for variable shaping in sinking EDM
    ( 2022) ;
    Thißen, Kai
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    Schulte Westhoff, Bela
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    Streckenbach, Jan
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    Ludwig, Jonas
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    Maas, Jürgen
    In sinking electrical discharge machining (S-EDM), many applications such as the manufacturing of injection moulds require numerous tool electrodes due to tool wear compensation. The manufacturing of tool electrodes causes a high cost and time expenditure in the entire process chain. This paper aims for a novel approach to a segmentation of the tool electrode in order to shape it variably. The shaping is realized by actuation of single tool electrode segments (STES) using miniaturized linear actuators. In the future, the roughing process in S-EDM could be carried out by segmenting and variably shaping of the tool electrode. To investigate the process behaviour of a segmented tool electrode in S-EDM, different geometry configurations of the tool electrodes are compared. Experimental results show a similar material removal rate for the different tool electrode configurations. The relative linear wear of a segmented tool electrode is only 7.7 % of the relative linear wear of a monolithic tool electrode. In order to dynamically position the STES, a miniaturized electrical linear drive is developed and constructed. The outer diameter of the actuator must not exceed the edge length of an STES. In the machine tool an actuated STES is tested and the material removal rate and the relative linear wear for different Z-axis lifting motions are analysed. The material removal rate could be increased by 37 % applying actuated Z-axis lifting motions compared to the process without Z-axis lifting motion. In this context the relative linear wear increased slightly. The results of this paper are used for the further development of the system to enable more efficient process chains in the EDM process.
  • Publication
    Investigation of additive manufactured tungsten carbide-cobalt tool electrodes for sinking EDM
    Increasing product complexity and continuous developments in related tool and mould making industry require ongoing advances in manufacturing processes like electrical discharge machining (EDM). To meet the increasing requirements, the development of adapted EDM processes and tool designs is necessary. Additive manufacturing (AM) enables the manufacturing of complex tool electrode geometries with interior flushing channels for EDM processes with very few restrictions regarding the design. This accounts even for tungsten carbide-cobalt (WC-Co), which is a suitable material for EDM tool electrodes with various advantages, e.g. thermal and mechanical stability. This paper shows first results of additive manufactured WC-Co tool electrodes for the use in sinking EDM and the related development process.
  • Publication
    Fundamental study on embedded displacement sensor arrays for ultrasonic-assisted ultraprecision machining
    ( 2022) ; ;
    Bulla, Benjamin
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    Dambon, Olaf
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    Dicke, Clemens
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    Hocke, T.
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    Thißen, Kai
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    Heper, M.
    Ultraprecision machining is a key technology for manufacturing complex steel moulds with dimensional accuracies in sub-micrometer range for mass production of optical components using micro-injection moulding. According to the state of the art, during the machining of carbide-forming metals, such as steel alloys, used single crystal diamond tools suffer from excessive tool wear. In order to overcome this technological und economical limitation, ultrasonic-assisted ultraprecision machining is applied successfully in a broad range of industrial and scientifically applications. Based on the reduction of the contact time between the tool and the workpiece excessive chemical and related tribological tool wear can be avoided. Nevertheless, the cutting speed is strictly limited to deceed critical contact times. Therefore, the monitoring of the tool vibration characteristic and thus the process control is a major challenge and of current industrial and scientifically interest. To overcome these challenges a method for in-situ measurement of the ultrasonic vibration is currently being developed and first results are shown. Using the sophisticated ultrasonic system, developed by SON-X GMBH, Aachen, Germany, up to a frequency fUS= 100 kHz the application of a dedicated eddy current sensor enabled the determination of the real path lines and the exact position of the cutting edge during the whole process with a displacement amplitude AD= 1 µm. The results were subsequently verified by laser vibrometer measurements. As a result of the investigation, an elliptical path movement of the cutting edge in the longitude direction AD,y= ± 1.0 µm and in z-direction AD,z= ± 0.34 µm could be determined using a frequency fUS= 100 kHz. Based on this new measurement method, the vibration characteristic can be specifically varied and adapted to the application. In addition, a comprehensive scientifical knowledge of the process can be gained and used to improve tool wear models.
  • Publication
    Flexible Automatisierung mit Virtuellen Agenten
    ( 2022) ; ;
    Mühlich, Christopher
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    The process automation of hybrid assembly systems presents companies with the challenge of integrating people and machines into a collaborative system while taking socio-economic aspects into account. The transfer of biological principles to the design of production processes, in combination with Industry 4.0, enables the development of self-organizing systems. Inspired by this, a decentralized platform solution for flexible automation is presented in order to use human skills to increase productivity in a targeted manner.
  • Publication
    Precision Finishing of Additive Manufactured Ti-Al-components Using Diamond Slide Burnishing
    Due to the increasing importance of lightweight design in terms of resource management, titanium aluminium (Ti-AI) alloys are gaining more and more significance. To fully exploit light weight design potentials additive manufacturing (AM) has the ability to shift state of the art product design towards maximised resource efficiency and physically minimized weight. Next to material standardization and qualification processes, major limitations for mass scale industrialization of additive manufacturing are high surface roughness values in a range of 5 μm ≤ Ra ≤ 15 urn and remaining tensile residual stress states. A promising approach to overcome these challenges shows a process chain consisting of near-net-shape laser powder bed fusion (LPBF) and subsequent finishing using a dedicate diamond slide burnishing (DSB) process [1]. Within this work plastic deformation induced by DSB and the effects on the workpiece material properties were investigated.