Frohn-Sörensen, Peter
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Publication Access status: Metadata only , Additive manufacturing of polymeric pressure die for rotary draw bending process3D printing or additive manufacturing (AM) possesses enormous potential to benefit the manufacturing industry. Presently, rotary draw bending (RDB) is one of the most commonly used cold-forming industrial process for bending metal tubes. Pressure die is a fundamental forming tool in RDB processes, and it is conventionally made by various grades of comparatively expensive alloy steels. This research presents a novel design of a pressure die which can be 3D printed by using inexpensive polymeric filaments. In this research paper, the 3D-printed pressure die is named as “FFF-pressure die.” The material used to fabricate the FFF-pressure die is a thermoplastic polymer known as “ecoPLA.” The mechanical properties of ecoPLA are studied in relation to the process conditions of a RDB process. Firstly, an initial feasibility of using the FFF-pressure die in a RDB process is obtained by conducting a quick static stress analysis with actual process conditions. After initial feasibility, a complete RDB process is developed and simulated with actual process conditions and material properties. The FFF-pressure die is then practically fabricated by FFF 3D printer and experimentally tested on an industrial RDB machine. The results of practical experiments are compared with the simulation results. In order to make a comparison of the FFF-pressure die with the conventional metal pressure die, the simulation and practical process is also conducted with the conventional metal pressure die. A performance and cost comparison is made between the polymeric FFF-pressure die and the conventional metal pressure die. Von Mises stresses, contact forces, failure risk, and elastic deformations are analyzed. The advantages and limitations of using the FFF-pressure die in a RDB process are discussed in the end. This research intends to widen the avenue of using cost-effective and lightweight forming tools in metal forming industries.Source Type:Article5 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Beeinflussung der Umformzone durch segmentierte Niederhalter beim inkrementellen ProfilbiegenDie Industrie befindet sich im Wandel. Sinkende Losgrößen bei gleichzeitig steigender Variantenvielfalt erfordern Produktionstechnologien, die eine wirtschaftliche Fertigung niedriger bis mittlerer Stückzahlen ermöglichen. Parallel dazu stellt die Transformation der Mobilität, insbesondere der Übergang vom Verbrennungs- zum Elektroantrieb, die Automobilindustrie vor zusätzliche Herausforderungen bei der Entwicklung und Fertigung neuer Crashstrukturen und Lastpfade. Konventionelle Werkzeugtechnologien mit starren, produktspezifischen Funktionsflächen stoßen hierbei zunehmend an ihre Grenzen. Zukünftige Produktionssysteme erfordern daher flexible Fertigungsprozesse und Werkzeuge, die eine wirtschaftliche Herstellung vom Einzelteil bis hin zu mittleren Losgrößen ermöglichen und gleichzeitig eine lastorientierte Bauteilauslegung unterstützen. Das inkrementelle Schwenkbiegen (ISB) stellt in diesem Kontext ein vielversprechendes Biegeumformverfahren dar. Das Biegemoment wird hierbei reibschlüssig über die Klemmflächen des Niederhalters in das Halbzeug eingeleitet, wodurch eine hohe Flexibilität hinsichtlich der umformbaren Halbzeuggeometrien erreicht wird. Der inkrementelle Charakter des Prozesses eröffnet zudem Freiheitsgrade zur Herstellung variabler Biegeradien und -winkel. Darüber hinaus wird in diesem Beitrag anhand etablierter Analysemethoden ein Werkzeugkonzept vorgestellt, das es ermöglicht, die Verteilung der Klemmkraft durch einstellbare, segmentierte Niederhalteflächen mit vertikalem Freiheitsgrad gezielt anzupassen und dadurch die Größe und Form der Umformzone zu beeinflussen. Anschließend wird das Potenzial zur Erweiterung der Grenzen der Umformtechnik im Hinblick auf die numerisch ermittelte lokale Dehnungsverteilung durch die dynamische Be- und Entlastung der Klemmflächensegmente während der inkrementellen Umformung untersucht. Das übergeordnete Ziel der Arbeit ist die Realisierung eines prozessintegriert steuerbaren Materialflusses in der Blechumformung. Die aktive Beeinflussung der Umformzone im ISB eröffnet damit neue Möglichkeiten zur flexiblen und lastorientierten Herstellung von Strukturbauteilen, beispielsweise von Längsträgern im Fahrzeugbau, und stellt einen vielversprechenden Ansatz für die wirtschaftliche Produktion zukünftiger lasttragender Strukturelemente dar.Source Type:InProceedings6 9 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Brittle fracture of notched components fabricated by stereolithographySince additive manufacturing (AM, i.e., 3D printing) has been widely used for production of end-used products, the mechanical strength of parts fabricated by this technology have gained considerable significance. The current study presents fracture load assessment of 3D-printed components fabricated by the stereolithography (SLA) technique using UV sensitive resin material. In this context, dumbbell-shaped specimens were printed and tested to determine basic mechanical properties. Moreover, V-notched semi-circular bending test coupons with various notch opening angles (i.e., 15°, 30°, 45°, 60°, 75°, and 90°) were printed and examined. Parallel to the experimental tests, we developed a finite element model to simulate the load carrying performance of 3D-printed parts. Moreover, we used the digital image correlation technique to determine displacement and strain field on the surface of the examined specimens. Since the mechanical strength and fracture behavior of 3D-printed parts are investigated in the current study, the presented outcomes can be utilized for innovative designs of parts fabricated by SLA with a higher mechanical strength, and improved load-carrying capacity.Source Type:Article7 11 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Datengestützte Umformtechnik: Künstliche Intelligenz zwischen Prozesswissen, Regelung und ProduktionsrealitätWith the 7th Biegeforum, the Chair of Forming Technology at the University of Siegen once again offers researchers the opportunity to present their topics and findings to a specialist audience from industry and academia. This conference volume brings together current research findings and innovative developments in forming technology, highlighting the broad scope of the research field. The Biegeforum thus underscores its role as a key platform for exchange between research and industry — a role it has fulfilled since its first edition in 2011.Source Type:Conference ProceedingsSeries:Forschungsberichte des Lehrstuhls für Umformtechnik7 12 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Erweiterung der Prozessgrenzen für hochfestes mikrolegiertes Kaltband durch inkrementelles Profil-SchwenkbiegenMikrolegiertes Kaltband im Zugfestigkeitbereich zwischen 500 und 1000 MPa ist seit langem ein etablierter Werkstoff im Bereich automobiler Anwendungen. Die als CR500LA bis CR1000LA bezeichneten Werkstoffe werden aufgrund ihres hohen Streckgrenzenverhältnisses z.B. für Profil-Anwendungen wie Sitzschienen verwendet. Im Rahmen des hier vorgestellten Projektes wurde untersucht, in wieweit durch eine Kombination aus inkrementellem Schwenkbiegen und hochfestem mikrolegierten Kaltband die Prozessgrenzen für Stahlprofile erweitert werden können. Durch das vergleichsweise gute Lochaufweitverhältnis der mikrolegierten Sorten sind schon beim kontinuierlichen Biegen von Profilen gute Ergebnisse erzielbar. Durch die inkrementelle Verfahrensvariante und das sehr gute lokale Umformvermögen dieser Werkstoffgruppe konnten die Prozessgrenzen noch einmal erheblich erweitert werden.Source Type:InProceedings300 109 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Fracture behavior of double edge notch AlSi10Mg alloy fabricated by laser powder bed fusionIn the present study, the fracture behavior of additively manufactured (AM) metal parts has been investigated. To this aim, double edge notch tension (DENT) specimens have been printed using AlSi10Mg alloy based on the laser powder bed fusion (PBF) technique. Particularly, DENT specimens have been fabricated with three different ligament lengths and three different printing directions for each ligament length. In this study, we used the concept of essential work of fracture to describe the fracture behavior AMed parts. According to a series of tests under static loading conditions, influences of the ligament length and printing direction on the structural integrity of the DENT specimens have been determined. According to the experimental practices, levels of ductility and size of plastic zone in the ligament region have been documented. Here, we utilized digital image correlation technique to measure strain fields on the surface of the examined samples. Moreover, numerical simulations have been conducted to simulate the stress distribution from DENT specimens. In addition, visual inspection of the fracture surfaces has been conducted using a free-angle observation system. The outcome of this study can be used for future designs of PBF printed parts with a better structural performance.Source Type:Article3 - Some of the metrics are blocked by yourconsent settings
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Publication Access status: Open Access , Mixed mode brittle fracture of stereolithographic 3D-printed partsTechnical advances in additive manufacturing (AM), also known as three-dimensional (3D) printing, have led to applications of this technology in creation of end-use items. Consequently, performance and the mechanical strength of AMed parts have become of significant importance. In this research, fracture behavior and crack propagation of AMed cracked plates are investigated. To this aim, the stereolithography (SLA) technique is used to fabricate square plate specimens with a hole in the center and radial cracks that started at the perimeter of the central hole. Here, full range of mixed-mode fracture (from pure mode I to pure mode II) are obtained by altering the angle between the crack and the applied load. We used the finite element method to determine stress intensity factors. This study deals with a series of experiments on 3D-printed cracked plates to study mixed-mode fracture and crack propagation in brittle fracture of SLA 3D-printed components. Additionally, the digital image correlation technique was used to determine strain field on the surface of the specimens. As SLA is one of the most commonly used concepts in polymer 3D printing and has garnered significant attention for fabrication of complex structural elements, the outcomes of this study are useful for next developments and innovative designs of 3D-printed polymeric components.Source Type:Article326 174 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Process Development of Incremental Swivel Bending − ISB(2023)Flexible metal forming processes advance in association with the megatrend of mass customization. Kinematic processes provide high potential for product variations and production on demand, given by their degrees of freedom and a geometrically independent tooling. Incremental forming processes add up another variable by a freely adjustable density of incremental steps. Yet, both processes require an in-depth understanding to determine the process parameters in relation to the dimensional properties of the product. Incremental Swivel Bending (ISB) is a promising profile bending process which has been suggested in the past for a flexible production of structural parts from high-strength steels in the context of highly variable production demands with respect to derivatives as well as lot sizes. This thesis presents the development of a holistic analytical model to layout the kinematic process parameters of ISB, which is validated by numerical and practical bending increments. The results demonstrate the application of the process layout for incremental profile bending of variable arcs from a variety of high-strength materials. A solution for the characteristic optimization problem of incremental forming processes is developed for the key question if a target geometry should be manufactured in large but coarse steps or by rather small but numerous steps. In the light of a future-oriented highly variable production, the number of reconfigurations of the process parameters for flexible manufacturing technologies such as ISB will severely increase. The presented work provides a process model to layout these parameters for given product variants without the needs for empirical trial and error approaches. This allows to save time and preserve material resources in an industrial application of the ISB process.Source Type:Doctoral ThesisSeries:Forschungsberichte des Lehrstuhls für UmformtechnikVolume number:155 12
