Robin Kleinwort’s research while affiliated with Technical University of Munich and other places

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Publications (19)


Experimental comparison of different automatically tuned control strategies for active vibration control
  • Article

November 2021

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28 Reads

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13 Citations

CIRP Journal of Manufacturing Science and Technology

R. Kleinwort

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J. Herb

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P. Kapfinger

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[...]

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M.F. Zaeh

Abstrac Chatter is the main limiting factor affecting the material removal rates of machine tools and is caused by the machine's most flexible structural mode shapes. The use of active vibration control systems can damp the structural mode shapes and, in turn, significantly increase the chatter-free depth of cut. In order to reduce the commissioning effort, previous publications have introduced methodologies to automatically tune various control strategies for active damping. This paper presents a new automatic tuning approach for a robust model-based controller, which uses particle swarm optimization to find the best-performing control parameters. The proposed method was tested on both a 5-axis milling machine and a vertical lathe, together with an automatically tuned direct velocity feedback controller and an adaptive controller. The performance was evaluated by conducting extensive cutting tests under industrial operating conditions. All controllers and automatic tuning methodologies led to notable increase in chatter-free material removal rates, reduced vibration amplitudes, and improved surface roughness.


Types of vibration-assisted milling
Images of the bottom surface for slot milling for LVAM and LTVAM at a cutting speed of vc = 30 m/min with different magnifications
Images of the side wall surface for peripheral milling for LVAM and LTVAM at a cutting speed of vc = 30 m/min with different magnifications
Residual stresses in feed direction and normal to feed direction for different vibration amplitudes in LVAM; left: bottom surface for slot milling; right: side surface for peripheral milling
Vickers hardness at the bottom surface and at the side wall for LVAM

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Experimental investigations on longitudinal-torsional vibration-assisted milling of Ti-6Al-4V
  • Article
  • Full-text available

June 2020

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915 Reads

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37 Citations

The International Journal of Advanced Manufacturing Technology

In vibration-assisted milling (VAM), an additional high-frequency oscillation is superimposed on the kinematics of a conventional machining process. This generates oscillations of the cutting edge in the range of a few micrometers, thereby causing a high-frequency change in the cutting speed and/or the feed. Consequently, a reduction of cutting forces, an increase of the tool life, and an improvement of the workpiece quality can be achieved. This paper shows and compares the effects of longitudinal and longitudinal-torsional (L-T) vibrations on the cutting force, the tool life, and the surface quality when milling Ti-6Al-4V. In comparison with the conventional milling process, the cutting forces are significantly reduced and the surface finish of the workpiece can be improved by introducing ultrasonic vibrations to the milling process. Longitudinal-torsional vibration assistance showed better overall process performance than the pure longitudinal vibration assistance.

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Predictive Maintenance in der Produktion/Predictive Maintenance within the industrial value chain

January 2020

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122 Reads

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2 Citations

wt Werkstattstechnik online

Ungeplante Maschinenausfälle führen zu Stillständen in der Produktion, die große Auswirkungen auf die Wertschöpfungskette eines Unternehmens haben. Der Einsatz von Predictive Maintenance (PdM) entlang dieser Kette erhöht die Maschinenverfügbarkeit und sichert einen reibungslosen Produktionsablauf. Im Rahmen verschiedener Forschungsprojekte am iwb werden Anwendungsfälle für PdM in der Fertigung, der Montage und der Produktionssteuerung betrachtet. Dieser Beitrag beleuchtet individuelle Herausforderungen, Lösungsansätze und Grenzen von PdM im produktionstechnischen Umfeld. Unplanned machine downtimes can have a big impact on the value chain of a company. Predictive Maintenance (PdM) shows the potential to increase machine availability and secures smooth production processes. Different research projects at iwb examine applications of PdM within manufacturing and assembly, as well as the integration of such approaches in production planning. This article highlights individual challenges, solutions and limits of PdM within production.


Fig. 4. Results of the stripe light detection of the ground surface according to the CAD model
Numbers of applied measuring points
Results of measuring the circular ring in z-direction
Results of the measurement of the repetitive accuracy Axis Standard deviation σ in µm
On-Machine Measuring Method for the Reconstruction of Additively Manufactured Near-Net Shaped Parts

January 2020

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69 Reads

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7 Citations

Procedia CIRP

Additive manufacturing brings along many chances like functional integration or light-weight construction. Because of distortion and poor surface roughness, however, machining is required to produce high quality parts out of metal. Depending on the position on the build tray, there is a variation of the deformation so that the exact part geometry after the additive manufacturing process is unknown. Hence, there is a big challenge for the mechanical post-processing. In this paper, a strategy to measure additively manufactured parts made by Laser Beam Melting directly in a milling machine using the touch trigger probe was developed. Therefore, a test specimen was machined, that includes a selection of the most relevant geometric features like holes, cones, different chamfers and a free-form surface. Subsequently, a number of measuring points was chosen for every feature. In order to select the positions of the measuring points, different algorithms from literature were evaluated. As a result, the Hammersley algorithm was determined as the most suitable algorithm for this use case. A special measuring test cycle was implemented in a Computer Aided Manufacturing (CAM) software and tested on a five-axis milling machine. The measuring results were edited in the CAM so that an accurate geometric model of the real part could be created. Based on this model, an adaption of the tool paths is possible, with the effect of a reduction of the machining time and an optimized utilization of the tool. The results were also compared with an optical strip light projection. It was shown, that the discrepancy between the tactile and the optical measuring strategy was minimal. This means that the tactile measurement results have a sufficient accuracy. In a second step, the developed measuring strategy was applied to turbine blades made by Laser Beam Melting. Again, the turbine blades were measured using the touch trigger probe in a five-axis milling machine and the results were validated.





Additive Fertigung für Flugzeug-Strukturkomponenten

August 2019

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27 Reads

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4 Citations

ZWF Zeitschrift fuer Wirtschaftlichen Fabrikbetrieb

Kurzfassung Hohe Werkzeugkosten und ein geringer Materialausnutzungsgrad führen zu hohen Produktionskosten für die Fertigung von Flugzeug-Strukturkomponenten aus der Legierung Ti 6Al 4V. Das Forschungsprojekt REGULUS hat zum Ziel, eine Prozesskette zu entwickeln, welche die Situation bezüglich dieser Kostentreiber signifikant verbessert. Dazu wird mittels WAAM ein endkonturnahes Rohteil aufgebaut. Die Zielgeometrie wird anschließend mit speziell für die Zerspanung unter ungleichmäßigen Eingriffsverhältnissen entwickelten Frässtrategien erzeugt.



Zustandsüberwachung von Vorschubantrieben mithilfe eingebetteter Sensoren: Erkennung von verschleißbedingten Vorspannungsverlusten anhand des dynamischen Verhaltens des Vorschubantriebs

March 2019

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111 Reads

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2 Citations

ZWF Zeitschrift fuer Wirtschaftlichen Fabrikbetrieb

Kurzfassung Um spanende Werkzeugmaschinen möglichst profitabel betreiben zu können, muss der aktuelle Verschleißzustand der Maschinen hinreichend genau bekannt sein. Dies kann durch kontinuierliche Zustandsüberwachung erreicht werden. Neuartige, direkt in die Komponenten des Antriebsstranges von Werkzeugmaschinen integrierte Sensoren bieten die Möglichkeit, dies auf einfache und kostengünstige Weise durchzuführen. Als Indikator für Verschleiß kann dabei direkt das dynamische Verhalten des Antriebsstranges herangezogen und so eine hohe Anlagenverfügbarkeit sichergestellt werden.


Citations (13)


... Do ponto de vista científico e tecnológico, a pesquisa e desenvolvimento de compósitos como o de PVDF e ZnO têm o potencial de impulsionar inovações significativas em várias áreas, contribuindo para avanços na eficiência energética e na criação de soluções sustentáveis para desafios contemporâneos, como absorver energia proveniente de vibrações mecânicas no ambiente [6][7] ou até mesmo monitoramento de umidade [8]. ...

Reference:

PRODUO DO FILME COMPSITO DE PVDF E ZNO PARA GERAO DE ENERGIA SUSTENTVEL
Experimental comparison of different automatically tuned control strategies for active vibration control
  • Citing Article
  • November 2021

CIRP Journal of Manufacturing Science and Technology

... In the pursuit of sustainability, it transcends the reactive realm of maintenance to undertake continuous, proactive measures that curtail anomalies (Dalzochio et al. 2020). For instance, Predictive Maintenance (PdM) helps increase machine availability and ensures smooth production processes by identifying and preventing potential problems before they occur (Maataoui et al. 2023;Nentwich et al. 2020). This proactive approach minimizes unplanned machine downtimes and reduces the impact on the value chain of a company. ...

Predictive Maintenance in der Produktion/Predictive Maintenance within the industrial value chain
  • Citing Article
  • January 2020

wt Werkstattstechnik online

... Workpiece localization (or workpiece referencing) has always been an engineering problem to be solved as part of subtractive machining processes; it involves locating the to-bemachined workpiece in the workspace of the machine. In the early days of machining, contact-based solutions were the only available methods and those are still a popular choice, even in combination with modern production technologies like additive manufacturing [6]. Non-contact methods based on vision systems [7] or 3D measurements [2,13,16] are popular because of their versatility, speed and high accuracy. ...

On-Machine Measuring Method for the Reconstruction of Additively Manufactured Near-Net Shaped Parts

Procedia CIRP

... 29,30 Furthermore, the bone LTVUM reduces the effects of bone anisotropy and cutting speed, while enhancing the impacts of feed rate. 29 Rinck et al. 31,32 found that the Ti-6Al-4V of LTVUM significantly reduces cutting force, improves cutting surface smoothness, and it has a better cutting performance compared to longitudinal assisted milling. Besides, Niu et al. 33 investigated the tool edge trajectory and cutting force of LTVUM, and reported that the cutting forces of the x and y directions decreased by 24.8% and 29.9%, respectively. ...

Experimental investigations on longitudinal-torsional vibration-assisted milling of Ti-6Al-4V

The International Journal of Advanced Manufacturing Technology

... Gai et al. introduced the permissioned blockchain technique in terms of group signatures as well as hidden channel authorization to prevent the sensitive information being violated [21]. Giehl et al. proposed a privacy-aware EC framework in order to utilize the applications, i.e., optimizing the production ability, promoting industrial safety on the shap-floor [22]. Zhao et al. proposed a decentralized system in mobile edge computing with privacy preservation which keeps high reputation for IoV [23]. ...

Edge-computing enhanced privacy protection for industrial ecosystems in the context of SMEs
  • Citing Conference Paper
  • November 2019

... The dynamic structural behavior of machine tools greatly influences the success of cutting processes, making it the objective of numerous modeling efforts. Fundamentally, two modeling strategies can be distinguished [1]: On the one hand, there is the so-called experimental approach, which is based on measurements of the real system's behavior and results in a gray-box or black-box model replicating the input-output behavior (e.g., in the form of transfer functions [2,3]). Their identification, that is the process of determining values for the involved model parameters, is often referred to as "system identification" or, in case in situ machining measurements are used, as "rapid identification". ...

FEED DRIVE CONDITION MONITORING USING MODAL PARAMETERS
  • Citing Article
  • November 2019

MM Science Journal

... The main drawbacks of WAAM are the high surface roughness and the distortion of the part. Hence, the subtractive machining of functional surfaces is an integral part of the WAAM process chain (Fuchs et al., 2019). ...

Additive Fertigung für Flugzeug-Strukturkomponenten
  • Citing Article
  • August 2019

ZWF Zeitschrift fuer Wirtschaftlichen Fabrikbetrieb

... In the past, many researchers used machine learning classifiers for condition monitoring of ball screw drives [10][11][12][13][14][15][16]. This approach can be followed when fault data is available (supervised anomaly detection). ...

Estimating remaining useful life of machine tool ball screws via probabilistic classification
  • Citing Conference Paper
  • June 2019

... Although these approaches can reduce vibrations, they do not satisfy the requirements. Active vibration control approaches have also been applied to suppress chatter vibrations (Zaeh et al., 2017;Kleinwort et al., 2018aKleinwort et al., , 2018bKonigsberg et al., 2018;Mancisidor et al., 2018). In these studies, additional sensors and actuators were added to the spindle or mechanical structures. ...

Simulation-Based Dimensioning of the Required Actuator Force for Active Vibration Control
  • Citing Article
  • September 2018

International Journal of Automation Technology

... [32] proposed a particle swarm optimisation-based automatic tuning method for active vibration control, comparing its performance with existing control methods in cutting tests. Validation of controller performance were carried out for DVF, ∞ and a novel adaptive FxLMS control [33]. Significantly improved chatter stability was achieved by implementing the active control methods. ...

Adaptive Active Vibration Control for Machine Tools with Highly Position-Dependent Dynamics
  • Citing Article
  • September 2018

International Journal of Automation Technology