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Publication Access status: Open Access , Ein datengetriebenes Verfahren zur robusten und zuverlässigen Auslegung des Niederdruck-Kokillen-Gießprozesses(2026)Ensuring product quality while maintaining high productivity and energy efficiency are key aspects and therefore levers for optimization measures in companies. In many sectors, including light metal foundries, data-driven methods based on machine learning are already being used in the context of Industry 4.0 to continuously improve process efficiency. Many studies are focused on analyzing process data during serial production. A holistic, data-based strategy for determining a robust and reliable process design that considers any process fluctuations that occur has not yet been developed for low pressure die casting. This paper therefore presents a novel, automated method for determining a robust and reliable operating point during the development phase of the low pressure die casting process. The focus is on the process parameters for a given casting and mold design but can easily be extended to include design parameters. Within the framework of design of experiments, the procedure includes the needs-based adjustment of the number of experiments as well as compliance with input and output restrictions, the modelling of both static and dynamic system behavior and, within the multi-criteria optimization, the consideration of both uncertainties in the process parameters and uncertainties due to limited metrological accessibility. A selection mechanism, which supports the user in the rapid analysis of robust and reliable Pareto-optimal solutions, rounds off the procedure. The performance is demonstrated using a real low pressure die casting process at MARTINREA HONSEL GERMANY GMBH. The results show that the approach enables a robust and reliable casting process design with comparatively low energy input, considering the boundary conditions of short cycle times.Source Type:Doctoral ThesisSeries:Forschungsberichte des Lehrstuhls für UmformtechnikVolume number:211 4 - 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 Umformtechnik1 1 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Design and Development of Hybrid Tools for Rotary Draw Bending Using Digital Twin and Additive Manufacturing Processes(2026)Rotary draw bending (RDB) process is a profile bending process mostly used in industrial practices for bending metal tubes. Presently, RDB process is conducted by using geometry specific bending tools. The fundamental tools used in RDB process are pressure-die, bend-die, clamp-dies, wiper-die, collet and mandrel. These tools have simplified geometries with a semi-circular tool surface which corresponds to only one specific tube diameter. This makes RDB process inflexible because different tube diameters cannot be used with a specific set of bending tools. In addition to process-flexibility, the modern production regime of present era needs bending tools to be cost effective and light weight. This doctoral thesis is aimed to utilize modern manufacturing techniques, i.e., 3D printing processes and digital twin of RDB process, to develop the geometric design of bending tools which should be cost effective, light weight and provides process-flexibility to RDB process. A digital twin of the RDB process is developed and the accuracy of the digital twin is verified by comparing the FE-simulation results with practically conducted experiments. The design factors which critically influence the tool design are identified through digital twin prototyping. The digital twin prototyping method encompasses systematic development and testing of 3D printed polymeric tools in RDB process. Topology optimization of a conventional tool geometry is conducted in order to identify minimum material required within the tool. The results obtained from digital twin prototyping and topology optimization envisioned the development of a hybrid tool. A hybrid tool consists of two different materials i.e., polymers and metals. The materials of a hybrid tool are selected from Ashby material charts on the basis of requirements resulting from process parameterization and topology optimization. A model of the hybrid tool is developed according to material properties of selected materials and identified tool design factors. The model is imported in digital twin of RDB process and tool performance is investigated by conducting process simulations with different tube diameters. After obtaining process feasibility through digital twin, the hybrid tool consisting of polymer - PLA and metal - stainless steel is practically 3D printed and experimentally tested in an actual RDB process. The experimental results demonstrates that a 3D printed hybrid tool is capable of conducting bending operations with different tube diameters while enabling significant material saving within the tool. A comparison is made between the novel 3D printed hybrid tools and conventional steel tools. A design formula is presented that determines the efficiency of bending tools through Tool Efficiency index (TEi). For practical applications, the geometry of 3D printed hybrid tools is standardized through aspect ratio and corresponding upscale size factors.Source Type:Doctoral ThesisSeries:Forschungsberichte des Lehrstuhls für UmformtechnikVolume number:2028 49 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Methode zur Gestaltung segmentierter Werkzeuge für die Flexibilisierung von Biegeprozessen(2026)The megatrends of neo-ecology, connectivity, and individualization are fundamentally transforming manufacturing technology. From the perspective of sheet and profile forming processes, these megatrends generate the need for resource-efficient and highly flexible production methods. Common industrial bending processes with geometric-specific tools, such as rotary draw bending or compression bending, have limited flexibility because the final contour of the bent part is predetermined by the tool shape. Approaches to enhance flexibility include the segmentation of closed tool surfaces, allowing for adjustable tool contours. Previous investigations in this area have been limited to large sheet metal components or profile bending parts with large bending radii in the context of multi-point forming. This work presents a systematic methodology for designing segmented bending tools, using compression bending as the example process. This methodology focuses on investigating the cause-effect relationships between surface topology of the forming tools, the mechanical and geometric properties of the semi-finished product, and the resulting forming phenomena and mechanisms. Segmented tools affect nearly all geometric characteristics of the bent components. This is primarily due to a combination of cross-sectional ovalizations and free bending over the segment gaps, which superimpose base bending. Despite these unavoidable limiting forming mechanisms, high-quality parts can be produced through an appropriate process and tool setup. The developed design methodology provides a solid knowledge base and characteristic diagrams for determining gap dimensions, segment geometries, and process parameters. Furthermore, in-process adjustments to the segments demonstrate the tools' expanded range of applications. This enables for the targeted suppression of limiting forming mechanisms that are typically active in statically segmented tools. Looking ahead, such adaptive tools will require load-bearing structures that can withstand process forces and facilitate necessary segment movements. As a first step towards this aspect, the investigations conducted in this research work introduce a novel approach of topology optimization of forming tool structures based on the mathematical optimization of truss-like structures using mixed-integer programming.Source Type:Doctoral ThesisSeries:Forschungsberichte des Lehrstuhls für UmformtechnikVolume number:1940 1552 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Verfahrensentwicklung 3D-Schwenkbiegen(2025)With increasing individualization, mass production is evolving towards personalized manufacturing, which is characterized by smaller batch sizes and a greater variety of variants. This increases the need for flexible manufacturing technologies. 3D-swivel-bending is an innovative approach to the low-tool production of complex profile components, particularly due to its ability to realize non-linear and three-dimensional bending edges and free-form surfaces. The development of this process aims to create more efficient and flexible methods for the manufacturing of components with variable cross-sections and load-adapted components. An important aspect is the extension of the swivel-bending principle by additional degrees of freedom to enable the shaping of non-linear bending edges and free-form surfaces. The process is based on a modified process instruction in which the axis of rotation of the bending tool is shifted relative to the bending edge, and adapted tool geometries are developed. The forming mechanisms and effects of 3D-swivel-bending are analyzed in a process design in order to describe the properties of the manufactured parts and the process limits analytically. Various methods for characterizing the mechanical behavior are presented in the process modelling to derive a process window for 3D-swivel-bending. This enables precise characterization of the forming mechanisms. The process window shows the working field of 3D-swivel-bending and can be used to evaluate and design future geometries. A validation of the developed methods evaluates the applicability of 3D-swivel-bending in industrial contexts and demonstrates technological and economic advantages. It shows that 3D-swivel-bending is particularly suitable for small and medium batch sizes in the automotive and aerospace industries, as well as in the construction sector. The process extension focusses on improvements in flexibility and applicability. Hybrid bending kinematics and new technologies for tool production and bending sequence planning are being developed. In addition, a process generator for digital planning and optimization of the production process is introduced. Thanks to its flexibility and efficiency, 3D-swivel-bending offers an innovative solution for complex components. It is particularly suitable for small batch sizes in industrial sectors and combines technological and economic advantages.Source Type:Doctoral ThesisSeries:Forschungsberichte des Lehrstuhls für UmformtechnikVolume number:181 2 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Biegen von endlosfaserverstärkten thermoplastischen Verbundrohren(2024)In this thesis, a process is developed to bend continuous fiber-reinforced thermoplastic composite pipes. The process includes heating, forming, reconsolidation and cooling of the composite tube. Basic material tests and bending tests provide insights into the reorientation of the reinforcing fibers during bending. These results are incorporated into a kinematic model that describes the resulting fiber angle in the bent tube and is validated by measurement data.Source Type:Doctoral ThesisSeries:Forschungsberichte des Lehrstuhls für UmformtechnikVolume number:17253 184 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Entwicklung einer Methode zur Formsimulation faserverstärkter Thermoplaste(2023)Fabric-reinforced thermoplastics are used for lightweight parts within automotive components. They can be formed using thermoforming processes after heating above the melting temperature of the thermoplastics. The fiber angles and the wrinkling of the final parts influence the mechanical properties. Thus, there is a great interest in the development and improvement of simulation methods for the prediction of fiber angles and wrinkling. The present work focuses on the development of an FE model to represent the forming behavior of fabric-reinforced polyamides and polypropylene with ABAQUS/EXPLICIT and the implementation of material tests for the shear, tensile, compressive and bending stiffnesses at forming temperature within a heating chamber. Currently, there is no standardization for the material tests. To validate the model, forming tests of a double dome demonstrator are carried out on a press and the fiber angles and wrinkling of the final parts are measured. This includes the development of a program to determine the fiber angles of the components and samples of the material tests. The influence of the individual input parameters of the material cards and their interactions are examined using sensitivity analyzes of the FE model. On this basis, a holistic method for the forming simulation of fiberreinforced thermoplastics is being developed. The method includes the determination of material parameters and their implementation into the FE model up to the forming simulation of the component. Finally, the method will be validated within the simulation of a bumper cross member.Source Type:Doctoral ThesisSeries:Forschungsberichte des Lehrstuhls für UmformtechnikVolume number:16894 167 - 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:151 336 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Transformation in der BiegetechnikMit dem 6. Biegeforum hat der Lehrstuhl für Umformtechnik an der Universität Siegen ein neues Format geschaffen, in dem neben der Industrie nun auch den Forschenden ein eigener Schwerpunkt am Forum gegeben wird. Im vorliegenden Tagungsband sind Fachvorträge zum aktuellen Stand der Forschung sowie von Innovationen in der Umformtechnik zusammengefasst. Sie geben einen spannenden Einblick in hochaktuelle Forschungsergebnisse zum Biegen. Seit seiner erstmaligen Auflage im Jahr 2011 hat sich das Biegeforum zu dem etablierten Treffpunkt für Wissenschaft und Praxis entwickelt. Es findet fortan im zweijährigen Rhythmus statt.Source Type:Conference ProceedingsSeries:Forschungsberichte des Lehrstuhls für Umformtechnik696 317 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Regelung des Werkstoffflusses zur Erhöhung der Bauteilqualität beim Rotationszugbiegen(2021)Rotary draw bending is a forming process used for bending tubular profiles with small wall thicknesses and small bending radii. Wrinkling as a process boundary is an instability that can only be calculated to a limited extent due to the variety of influences. Up to now, only experienced machine operators designed the bending process to be wrinkle-free by carrying out adjustment trials. If corrections are made to prevent wrinkles, there is a risk that the process will lead to cracking. In this work, a knowledge-based method is presented that automatically prevents wrinkling during the bending process. A fuzzy controller was implemented that allows dosed parameter corrections to prevent wrinkles while considering the risk of cracking. Countermeasures to prevent the wrinkles are introduced as much as necessary and as little as possible. In-situ measurement systems detect the first wrinkle as it forms. Both moving the pressure die toward the tube and reducing the feed rate of the transport unit counteract the wrinkles and serve as actuators of the controller. Experience-based knowledge was integrated in the development of the control system. The derived process model can be applied to other problem solving systems, such as case-based reasoning systems, in addition to the system of a closed-loop control. In practical bending tests to prove the controller, wrinkle-free tube bends were produced. The controller, which is integrated into the machine and permanently activated, reacts to fluctuations caused, for example, by temperature fluctuations, batch changes and changes in the bending task. The use of the controller eliminates time-consuming and cost-intensive adjustment trials and reduces the reject rate. The targeted process control avoids unnecessarily high tool forces, which can reduce tool wear.Source Type:Doctoral ThesisSeries:Forschungsberichte des Lehrstuhls für UmformtechnikVolume number:14647 1057
