Univ. Prof. Dr. Ing.

Bergs, Thomas

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  • Publication
    Additiv gefertigte Gewindewerkzeuge aus HSS
    ( 2023-07-17)
    Tobias Kelliger
    ;
    Meurer, Markus
    ;
    Bergs, Thomas
    Eine verlängerte Werkzeuglebensdauer bei der Gewindefertigung ist durch eine Neugestaltung der inneren Kühlschmierstoffzufuhr am Werkzeug möglich. Der Einsatz additiver Fertigungsverfahren wie dem Laser Powder Bed Fusion erlaubt die Fertigung innen liegender und komplexer Kanal- und Düsengeometrien. In umfangreichen Einsatztests konnten Prozesssicherheit und Potenziale additiv gefertigter Gewindeform- und Gewindeschneidwerkzeuge aus Schnellarbeitsstahl nachgewiesen werden.
  • Publication
    Knowledge-Based Process Design Optimization in Blisk Manufacturing
    ( 2022)
    Landwehr, Markus
    ;
    Ganser, Philipp
    ;
    Vinogradov, Georg
    ;
    Bergs, Thomas
    The manufacturing process of blade-integrated disks (blisks) represents one of the most challenging tasks in turbomachinery manufacturing. The requirement is to machine complex, thin-walled blade geometries with high aspect ratios made of difficult-to-cut materials. In addition, extremely tight tolerances are required, since the smallest deviations can lead to a reduction in efficiency of the blisk in the later use. Nowadays, the ramp-up phase for the manufacturing of a new blisk is time and cost-intensive. To find a suitable manufacturing process that meets the required tolerances of the blisk, many experimental tests with different process parameters and strategies are necessary. The used approach is often trial and error, which offers limited testing opportunities, is time-consuming and waste of resources. Therefore, the objective of this paper is to develop a knowledge-based process design optimization in blisk manufacturing. For this purpose, this paper picks up the results from our previous work. Based on these results, an experimental validation of the two process design tasks “number of blocks” and “block transition” is conducted. As part of the validation, the results of machining tests on a demonstrator blisk made of Inconel 718 are presented and discussed.
  • Publication
    Investigations on five-axis milling and subsequent five-axis grinding of gears
    ( 2022)
    Bergs, Thomas
    ;
    Schneider, Sebastian A. M.
    ;
    Janßen, Christopher
    ;
    Jahnel, Kirk
    ;
    Ganser, Philipp
    ;
    Brimmers, Jens
    High-productivity processes such as gear hobbing and gear grinding are normally used in the manufacturing of gears. In some applications, however, the use of these processes is not possible due to accessibility. One example is the production of planetary gears with double helical teeth for the gear box in modern aircraft engines. The gear boxes are used to increase the efficiency of the engines but should be as light and compact as possible. Thus, the tool runout area for gear hobbing or gear grinding tools is too small. One way of manufacturing these gears is five-axis machining. While five-axis milling of gears has been the subject of several publications, five-axis grinding of gears has hardly been a topic. This paper presents the results of investigations on five-axis milling and subsequent five-axis grinding of gears in comparison to conventionally manufactured gears. For this purpose, after hardening, gears were first five-axis milled and then five-axis ground using different process parameters and then investigated on back-to-back test rigs regarding load carrying capacity. In addition, the dimensional accuracy was measured and the surfaces were examined metallographically. The dimensional accuracy became worse after five-axis grinding. However, in terms of gear life, the five-axis milled and then five-axis ground variant showed an increase of 8.2 % compared to the conventionally manufactured gear which indicates a high potential for further research in regard to the presented five-axis machining process chain of gears.
  • Publication
    Investigation of cutting mechanisms in the machining of Ceramic Matrix Composites (CMCs)
    ( 2021)
    Bergs, Thomas
    ;
    Ganser, Philipp
    ;
    Fruh, Daniel
    ;
    Reisberg, Jannik
    Ceramic Matrix Composites (CMCs) are increasingly used in numerous engineering fields, e.g. the aerospace, automotive, energy & nuclearindustry due to their higher permissible material temperature and their lower weight compared to metallic materials. Thanks to the quasi-ductilematerial behaviour, it is possible to carry out time- and cost-efficient finishing with a geometrically defined cutting edge.In this study the cutting mechanisms are analysed in fundamental cutting tests on an orthogonal cutting test bench by variance of the undeformedchip thickness. For the evaluation cutting force measurements, high-speed recordings, surface qualities measurements and chip analyses were conducted.
  • Publication
    Pulsed Laser Influence on Temperature Distribution during Dual Beam Laser Metal Deposition
    ( 2020)
    Gipperich, Marius
    ;
    Riepe, Jan
    ;
    Arntz, Kristian
    ;
    Bergs, Thomas
    Wire-based Laser Metal Deposition (LMD-w) is a suitable manufacturing technology for a wide range of applications such as repairing, coating, or additive manufacturing. Employing a pulsed wave (pw) laser additionally to the continuous wave (cw) process laser has several positive effects on the LMD process stability. The pw-plasma has an influence on the cw-absorption and thus the temperature distribution in the workpiece. In this article, several experiments are described aiming to characterize the heat input during dual beam LMD. In the first setup, small aluminum and steel disks are heated up either by only cw or by combined cw and pw radiation. The absorbed energy is then determined by dropping the samples into water at ambient temperature and measuring the waters temperature rise. I n a second experiment, the temperature distribution in the deposition zone under real process conditions is examined by two-color pyrometer measurements. According to the results, the pw plasma leads to an increase of the effective absorption coeffcient by more than 20%. The aim of this work is to achieve a deeper understanding of the physical phenomena acting during dual beam LMD and to deploy them selectively for a better and more flexible process control.
  • Publication
    Digital image processing with deep learning for automated cutting tool wear detection
    ( 2020)
    Bergs, Thomas
    ;
    Holst, Carsten
    ;
    Gupta, Pranjul
    ;
    Thorsten Augspurger
    Tool wear is a cost driver in the metal cutting industry. Besides costs for the cutting tools themselves, further costs appear - equipment downtime for tool changes, reworking of damaged surfaces, scrap parts or damages to the machine tool itself in the worst case. Consequently, tools need to be exchanged on a regular basis or at a defined tool wear state. In order to detect and monitor the tool wear state different approaches are possible. In this publication, a deep learning approach for image processing is investigated in order to quantify the tool wear state. In a first step, a Convolutional Neural Networks (CNN) is trained for cutting tool type classification. This works well with an accuracy of 95.6% on the test dataset. Finally, a Fully Convolutional Network (FCN) for semantic segmentation is trained on individual tool type datasets (ball end mill, end mill, drills and inserts) and a mixed dataset to detect worn areas on the microscopic tool images. The accuracy metric for this kind of task, Intersect over Union (IoU), is around 0.7 for all networks on the test dataset. This paper contributes to the perspective of a fully automated cutting tool wear analysis method using machine tool integrated microscopes in the scientific and industrial environment.