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2023

Analysis of temperature effect on strength and microstructure in friction induced recycling process (FIRP)

T. Borgert, W. Homberg, in: Materials Research Proceedings, Materials Research Forum LLC, 2023

DOI

<jats:p>Abstract. In order to reduce global energy consumption in production and industry along with the associated CO2 emissions, existing resources must be used more efficiently. This includes the energy-efficient and comprehensive recycling of a wide range of metals. Especially for the production of aluminium, there is a large potential for saving energy using efficient recycling processes. With regard to the recycling of aluminium studies have shown that solid-state recycling processes are significantly more efficient considering the used energy and resources compared to the conventional, smelting-metallurgical recycling process. In this paper, the direct and energy-efficient friction-induced recycling process (FIRP) based on the conform process is further described and analysed in terms of the temperature-property relationships. For this purpose, the influence of the processing temperature on the microstructure and properties of the recycled semi-finished products is investigated using the toll system that enables an ECAP forming. Specific sections of the (in theory) infinite, recycled semi-finished product are taken and analysed at different process temperatures of the solid state recycling process. Based on these sections, the properties in terms of mechanical hardness, strength, ductility and grain size are analysed and a degressive relationship between process temperature and mechanical hardness up to a temperature of 270 °C can be shown. Applying the Hall-Petch relationship, it is analysed whether there is a correlation between the strength and the microstructure in the form of the grain size. </jats:p>

Numerische Untersuchung von Oberflächensrukturierung zur Erhöhung der Effizienz von Kissenplatten-Wärmeübertragern

R. Afsahnoudeh, M. Holzmüller, F. Bader, W. Homberg, E.Y. Kenig. Numerische Untersuchung von Oberflächensrukturierung zur Erhöhung der Effizienz von Kissenplatten-Wärmeübertragern. In: Jahrestreffen der DECHEMA-Fachgruppen Computational Fluid Dynamics und Wärme- und Stoffübertragung, Frankfurt am Main, 2023.

Energy and Resource-efficient Forming of Gas Cylinders by Friction-Spinning

F. Dahms, W. Homberg, in: Materials Research Proceedings, Materials Research Forum LLC, 2023

Abstract

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DOI

<jats:p>Abstract. Friction-spinning as an innovative incremental forming process enables large degrees of deformation in tube and sheet metal-forming due to a self-induced heat generation in the forming zone. This paper presents new process designs for energy and resource-efficient forming of gas cylinders by friction-spinning without the use of an external heat supply. The self-generated heat enables friction-spinning process to reduce the energy demand in the manufacture of gas cylinders, which are usually manufactured with external heat (mostly fossil fuels), by 95 %. Typical gas cylinder contours, such as flattened and spherical bottom ends and cylinder necks, are manufactured by friction-spinning of AW 6060 tubular profiles with specifically designed tool path strategies. It is shown that friction-spinning enables the manufacture of typical gas cylinder contours with sufficient wall thickness and the required gas tightness without the input of external heat. Thus, this process can contribute to an increase in the energy and resource efficiency of forming processes. </jats:p>

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Echtzeitfähige Modellierung eines innovativen Drückwalzprozesses für die eigenschaftsgeregelte Bauteilfertigung

L. Kersting, B. Arian, J. Rozo Vasquez, A. Trächtler, W. Homberg, F. Walther, at - Automatisierungstechnik (2023), 71(1), pp. 68-81

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<jats:title>Zusammenfassung</jats:title> <jats:p>Aufgrund aktueller Transformationsprozesse kommt der automatisierten und ressourceneffizienten Fertigung hochfester Leichtbauteile eine steigende Bedeutung zu, beispielsweise im Flugzeug- und Fahrzeugbau. Für kleine Losgrößen bietet sich hier insbesondere das Fertigungsverfahren des Drückwalzens an. Der konventionelle, industriell genutzte Drückwalzprozess stößt allerdings aufgrund der Prozesskomplexität hinsichtlich der Reproduzierbarkeit an seine Grenzen. Dies wird in der Praxis teilweise durch personengebundenes Erfahrungswissen kompensiert. Auch ist es nicht möglich, Bauteileigenschaften definiert einzustellen. Aus diesem Grund bietet der Einsatz einer neuartigen Eigenschaftsregelung Chancen zur Weiterentwicklung des Fertigungsprozesses und die Möglichkeit zur Prozessautomatisierung. Hier werden die Werkzeugbahnen abhängig einer Online-Eigenschaftsmessung über eine zusätzliche Reglerkaskade manipuliert. Die Entwicklung einer solchen Eigenschaftsregelung erfordert den Einsatz geeigneter, modellbasierter Entwurfsmethoden. In diesem Beitrag wird daher ein regelungstechnisches Systemmodell für das Drückwalzen metastabiler austenitischer Edelstähle vorgestellt. Das Simulationsmodell weist aufgrund seiner Echtzeitfähigkeit neben dem Einsatz als reines Entwurfsmodell weitere Nutzungsmöglichkeiten z.B. in Beobachtern auf und grenzt sich somit von domänenspezifischen Simulationstools wie der FEM ab.</jats:p>

Control strategy for angular gradations by means of the flow forming process

L. Kersting, B. Arian, J. Rozo Vasquez, A. Trächtler, W. Homberg, F. Walther, in: Materials Research Proceedings, Materials Research Forum LLC, 2023

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<jats:p>Abstract. Climate change, rare resources and industrial transformation processes lead to a rising demand of multi-complex lightweight forming parts, especially in aerospace and automotive sectors. In these industries, flow forming is often used to produce cylindrical forming parts by reducing the wall thickness of tubular semifinished parts, e.g. for the production of hydraulic cylinders or gear shafts. The complexity and functionality of flow forming workpieces could be significantly increased by locally graded microstructure and geometry structures. This enables customized complex hardness distributions at wear surfaces or magnetic QR codes for a unique, tamper-proof product identification. The production of those complex, 2D (axial and angular) graded forming parts currently depicts a great challenge for the process and requires new solutions and strategies. Hence, this paper proposes a novel control strategy that includes online measurements from an absolute encoder to determine the angular workpiece position. Workpieces of AISI 304L stainless steel with 2D-graded structures are successfully manufactured using this new strategy and analyzed regarding the possible accuracy and resolution of the gradation. At this point, a dependency of the gradations on the sensor and actuator dynamics, accuracy and geometry could be noted. It is further evaluated how the control strategy could be extended by an observer-based closed-loop property control approach to enhance the accuracy of the suggested strategy. </jats:p>

Cryogenic reverse flow forming of AISI 304L

B. Arian, W. Homberg, L. Kersting, A. Trächtler, J. Rozo Vasquez, F. Walther, in: Materials Research Proceedings, Materials Research Forum LLC, 2023

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<jats:p>Abstract. Workpiece property-control permits the application-oriented and time-efficient production of components. In reverse flow forming, for example, a control of the microstructure profile is not yet part of the state of the art, in contrast to the geometry control. This is, due to several reasons, particularly challenging when forming seamless tubes made of metastable austenitic stainless AISI 304L steel. Inducing mechanical and/or thermal energy can cause a phase transformation from austenite to martensite within this steel. The resulting α’-martensite has different mechanical and micromagnetic properties, which can be advantageous depending on the application. For purposes of local property control, the resulting α’-martensite content should be measured and controlled online during the forming process. This paper presents results from the usage of a custom developed cryo-system and different application strategies to use liquid nitrogen as a coolant for local enhancement of the forming-temperature depending α’-martensite content. </jats:p>

Softsensor model of phase transformation during flow forming of metastable austenitic steel AISI 304L

J. Rozo Vasquez, B. Arian, L. Kersting, F. Walther, W. Homberg, A. Trächtler, 2023

Detection of phase transformation during plastic deformation of metastable austenitic steel AISI 304L by means of X-ray diffraction pattern analysis

J. Rozo Vasquez, B. Arian, L. Kersting, F. Walther, W. Homberg, A. Trächtler, Metals (2023)

Proof of concept for incremental sheet metal forming by means of electromagnetic and electrohydraulic high-speed forming

M. Holzmüller, M. Linnemann, W. Homberg, V. Psyk, V.. Kräusel, J. Kroos, in: Materials Research Proceedings, Materials Research Forum LLC, 2023, pp. 11-18

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<jats:p>Abstract. The combination of incremental sheet metal forming and high-speed forming offers new possibilities for flexible forming processes in the production of large sheet metal components of increased complexity with relatively low forming energies. In this paper, the general feasibility and process differences between the pulse-driven high-speed forming technologies of electrohydraulic and electromagnetic forming were investigated. An example component made of EN AW 6016 aluminum sheet metal was thus formed incrementally by both processes and the forming result evaluated by an optical 3D measurement system. For this purpose, a forming strategy for electromagnetic incremental forming (EMIF) was developed, tested and adapted to the electrohydraulic incremental forming process (EHIF). The discharge energy, the tool displacement and the pressure field of the forming zone were determined as relevant parameters for the definition of an adequate tool path strategy. It was found that the EHIF process is less affected by larger distances between the tool and the blank, while this is a critical variable for force application to the component during EMIF. On the other hand, the more uniform pressure distribution of the EMIF process is advantageous for forming large steady component areas. </jats:p>

Investigation of Pressure Fields Generated by Two Simultaneous Discharges in Liquid Initiated by Wires

M. Knyazyev, M. Holzmüller, W. Homberg, Journal of Manufacturing and Materials Processing (2023), 7(1), 40

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<jats:p>The pressure fields generated by two simultaneous discharges have not been investigated on any notable scale for the electrohydraulic impulse forming method. In this study, the synchronicity of two discharges is ensured by the sequential connection of two wires mounted in two spark gaps in a common volume of liquid. The objective is to experimentally confirm the equilibrium of the energies evolved in two spark gaps by means of pressure measurements. In addition, multipoint membrane pressure gauges demonstrated the feasibility of easily recording detailed pressure maps. Based on the membrane deformation mechanism and material strengthening under static and impulse conditions, the processing procedure is further developed so as to achieve better accuracy in the determination of pressure field parameters. The practical equality of the pressure fields on the left and right halves of the flat-loaded area confirms the equality of energies evolved in the two spark gaps. The direct shock waves create zones with the most intensive loading. These results provide a basis for the development of new electrohydraulic technologies involving the application of two simultaneous discharges with equal energy and pressure parameters.</jats:p>

Influence of thermo-mechanical joining process on the microstructure of a hypoeutectic aluminium cast alloy

T. Borgert, M. Neuser, E. Wiens, O. Grydin, W. Homberg, M. Schaper, in: Materials Research Proceedings, Materials Research Forum LLC, 2023, pp. 187-194

Abstract

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<jats:p>Abstract. Requirements of multi-material construction involve adjustments to standard joining techniques. Especially the growing importance of integral cast components poses additional engineering challenges for the industry. One approach to achieve these goals are adaptable joining elements formed by friction spinning. This approach uses friction-induced heat to form customisable joining elements to join sheets for different boundary conditions, even for brittle cast materials. It is possible to react immediately to adapt to the joining process inline and reduce the amount of different joining elements. As the joining partner serve casting plates of the aluminium casting alloy EN AC–AlSi9, which is processed in the sand casting. Joining hypoeutectic AlSi alloys constitutes a challenge because the brittle character of these cause cracks in the joint during conventional mechanical joining. Furthermore, the friction-induced heat of the novel joining process causes a finer microstructure in the hypoeutectic AlSi9 casting alloy. In particular, the eutectic Si is more fine-grained, resulting in higher joint ductility. This study indicates the joining suitability of a hypoeutectic aluminium casting alloy in combination with adaptive manufactured additional joining elements. Here, various mechanical and microstructural investigations validate the influence of the thermomechanical joining technique. In conclusion, the potential of this joining process is presented regarding the joinability of cast aluminium components. </jats:p>

2022

Assessment of mechanical and optical properties of Al 6060 alloy particles by removal of contaminants

P. Vieth, T. Borgert, W. Homberg, G. Grundmeier, Advanced Engineering Materials (2022)

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Review on mechanical joining by plastic deformation

G. Meschut, M. Merklein, A. Brosius, D. Drummer, L. Fratini, U. Füssel, M. Gude, W. Homberg, P. Martins, M. Bobbert, M. Lechner, R. Kupfer, B. Gröger, D. Han, J. Kalich, F. Kappe, T. Kleffel, D. Köhler, C. Kuball, J. Popp, D. Römisch, J. Troschitz, C. Wischer, S. Wituschek, M. Wolf, Journal of Advanced Joining Processes (2022), 5, 100113

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Mechanical joining technologies are increasingly used in multi-material lightweight constructions and offer opportunities to create versatile joining processes due to their low heat input, robustness to metallurgical incompatibilities and various process variants. They can be categorised into technologies which require an auxiliary joining element, or do not require an auxiliary joining element. A typical example for a mechanical joining process with auxiliary joining element is self-piercing riveting. A wide range of processes exist which are not requiring an auxiliary joining element. This allows both point-shaped (e.g., by clinching) and line-shaped (e.g., friction stir welding) joints to be produced. In order to achieve versatile processes, challenges exist in particular in the creation of intervention possibilities in the process and the understanding and handling of materials that are difficult to join, such as fiber reinforced plastics (FRP) or high-strength metals. In addition, predictive capability is required, which in particular requires accurate process simulation. Finally, the processes must be measured non-destructively in order to generate control variables in the process or to investigate the cause-effect relationship. This paper covers the state of the art in scientific research concerning mechanical joining and discusses future challenges on the way to versatile mechanical joining processes.

Energy saving potentials of an efficient recycling process of different aluminum rejects

T. Borgert, W. Homberg, Energy Reports (2022), 8, pp. 399-404

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Hot Spinning of Cutting Blades for Food Industry

D. Engemann, W. Homberg, 2022

Abstract

The spinning process is a flexible incremental forming process for the manufacturing of axially-symmetric sheet metal or tubular components with functionally graded properties. It is characterized by the utilization of universal tooling geometries and quite low forming forces. The process has a high potential to reduce material waste, to extend the forming limits and to achieve more complex geometries as well as favorable part properties [1]. Current research work at the Chair of Forming Technology (LUF) is focused on innovative flow-turning processes that have a high potential for producing flat components with excellent geometrical and mechanical properties while keeping process times short [2]. In combination with process-integrated local heat treatment, the new spinning process is predestined for the efficient forming of ultra-high-strength steel or tailored materials. Due to the desired field of food industry only food-safe materials such as special stainless steels are being investigated. This paper presents an innovative machine layout as well as an adequate process design for the production of high-performance circular knives with optimized mechanical hardness. In this context, particular attention is paid to various areas of temperature control as well as process-related challenges during the process.

Identification of Requirements for FE Modeling of an Adaptive Joining Technology Employing Friction-Spun Joint Connectors (FSJC)

A. Oesterwinter, C. Wischer, W. Homberg, Metals (2022), 12(5), 869

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<jats:p>The adaptive joining process employing friction-spun joint connectors (FSJC) is a promising method for the realization of adaptable joints and thus for lightweight construction. In addition to experimental investigations, numerical studies are indispensable tools for its development. Therefore, this paper includes an analysis of boundary conditions for the spatial discretization and mesh modeling techniques, the material modeling, the contact and friction modeling, and the thermal boundary conditions for the finite element (FE) modeling of this joining process. For these investigations, two FE models corresponding to the two process steps were set up and compared with the two related processes of friction stir welding and friction drilling. Regarding the spatial discretization, the Lagrangian approach is not sufficient to represent the deformation that occurs. The Johnson-Cook model is well suited as a material model. The modeling of the contact detection and friction are important research subjects. Coulomb’s law of friction is not adequate to account for the complex friction phenomena of the adaptive joining process. The thermal boundary conditions play a decisive role in heat generation and thus in the material flow of the process. It is advisable to use temperature-dependent parameters and to investigate in detail the influence of radiation in the entire process.</jats:p>

Further Development of an Adaptive Joining Technique Based on Friction Spinning to Produce Pre-Hole-Free Joints

C. Wischer, W. Homberg, Key Engineering Materials (2022), 926, pp. 1468-1478

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Mechanical joining processes are an essential part of modern lightweight construction. They permit materials of different types to be joined in a way that is suitable for the loads involved. These processes reach their limits, however, as soon as the boundary conditions change. In most cases, these elements are specially adapted to the joining point and cannot be used universally. Changes require cost-intensive adaptation of both the element and the process control, thus making production more complex. This results in high costs due to the increased number of auxiliary joining element variants required and reduces the economic efficiency of mechanical joining. One approach to overcoming this issue is the use of adaptive auxiliary joining elements formed by friction spinning. This article presents the current state of research on pre-hole-free joining with adaptive joining elements. The overall process chain is illustrated, explained and analyzed. Special attention is paid to demonstrating the feasibility of pre-hole-free joining with adaptive joining elements. The chosen mechanical parameters are subsequently listed. Finally, a comprehensive outlook of the future development potential is derived.</jats:p>

Comparative Analysis of Electrohydraulic and Electromagnetic Sheet Metal Forming against the Background of the Application as an Incremental Processing Technology

T. Heggemann, V. Psyk, A. Oesterwinter, M. Linnemann, V. Kräusel, W. Homberg, Metals (2022), 12(4)

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High-speed forming processes such as electromagnetic forming (EMF) and electrohydraulic forming (EHF) have a high potential for producing lightweight components with complex geometries, but the forming zone is usually limited to a small size for equipment-related reasons. Incremental strategies overcome this limit by using a sequence of local deformations to form larger component areas gradually. Hence, the technological potential of high-speed forming can be exploited for large-area components too. The target-oriented process design of such incremental forming operations requires a deep understanding of the underlying electromagnetic and electrohydraulic forming processes. This article therefore analyzes and compares the influence of fundamental process parameters on the acting loads, the resulting course of deformation, and the forming result for both technologies via experimental and numerical investigations. Specifically, it is shown that for the EHF process considered, the electrode distance and the discharge energy have a significant influence on the resulting forming depth. In the EHF process, the largest forming depth is achieved directly below the electrodes, while the pressure distribution in the EMF depends on the fieldshaper used. The energy requirement for the EHF process is comparatively low, while significantly higher forming speeds are achieved with the EMF process.

Innendrückwalzen – Ein innovatives Umformverfahren zur inkrementellen Formgebung von wanddickenkonturierten Rohren mit lokal einstellbaren mechanischen Eigenschaften

E. Wiens, 2022

Manufacture of Defined Residual Stress Distributions in the Friction-Spinning Process: Driven Tool and Subsequent Flow-Forming

F. Dahms, W. Homberg, Key Engineering Materials (2022), 926, pp. 683-689

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<jats:p>Friction-spinning as an innovative incremental forming process enables large degrees of deformation in the field of tube and sheet metal forming due to a self-induced heat generation in the forming zone. This paper presents a new tool and process design with a driven tool for the targeted adjustment of residual stress distributions in the friction-spinning process. Locally adapted residual stress depth distributions are intended to improve the functionality of the friction-spinning workpieces, e.g. by delaying failure or triggering it in a defined way. The new process designs with the driven tool and a subsequent flow-forming operation are investigated regarding the influence on the residual stress depth distributions compared to those of standard friction-spinning process. Residual stress depth distributions are measured with the incremental hole-drilling method. The workpieces (tubular part with a flange) are manufactured using heat-treatable 3.3206 (EN-AW 6060 T6) tubular profiles. It is shown that the residual stress depth distributions change significantly due to the new process designs, which offers new potentials for the targeted adjustment of residual stresses that serve to improve the workpiece properties.</jats:p>

Manufacture of Defined Residual Stress Distributions in the Friction-Spinning Process: Investigations and Run-to-Run Predictive Control

F. Dahms, W. Homberg, Metals (2022), 12(1), 158

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<jats:p>Friction-spinning as an innovative incremental forming process enables high degrees of deformation in the field of tube and sheet metal forming due to self-induced heat generation in the forming area. The complex thermomechanical conditions generate non-uniform residual stress distributions. In order to specifically adjust these residual stress distributions, the influence of different process parameters on residual stress distributions in flanges formed by the friction-spinning of tubes is investigated using the design of experiments (DoE) method. The feed rate with an effect of −156 MPa/mm is the dominating control parameter for residual stress depth distribution in steel flange forming, whereas the rotation speed of the workpiece with an effect of 18 MPa/mm dominates the gradient of residual stress generation in the aluminium flange-forming process. A run-to-run predictive control system for the specific adjustment of residual stress distributions is proposed and validated. The predictive model provides an initial solution in the form of a parameter set, and the controlled feedback iteratively approaches the target value with new parameter sets recalculated on the basis of the deviation of the previous run. Residual stress measurements are carried out using the hole-drilling method and X-ray diffraction by the cosα-method.</jats:p>

Innovative assistance system for setting up a mechatronic straightening machine

L. Bathelt, F. Bader, E. Djakow, C. Henke, A. Trächtler, W. Homberg, 2022

Abstract

DOI

High-strength wire materials are usually available as strip material which is further processed in a forming process (e.g. punch-bending). For storage and transport of the semi-finished wire to the customer, the material is wound onto coils. The manufacturing and coiling process introduces plastic deformations into the wire, which lead to undesirable residual stresses and wire curvature of the semi-finished product. These residual stresses and curvatures cause variations in the material properties of the semi-finished product, which have a negative impact on the subsequent product quality. Straightening machines are used to compensate the residual stresses and the curvature in the wire. At the beginning of the straightening process, the straightening machines must be set up in such a way that residual stresses and curvatures are optimally compensated. This setup process is usually a manual and iterative process, where a lot of material is wasted until the optimal settings for the straightening machine are found.In order to reduce the amount of material waste, the operator must be supported in the setup process. In this context, a new and innovative setup assistance system was developed to support the operator during the setup process. The setup assistant system automatically detects the wire curvature by means of an optical measuring system. Based on the optically detected measuring points, the wire curvature is determined by a robust calculation algorithm. Based on a database built up through the carried out experimental and numerical research work, the optimum setting parameters for the straightening machine are suggested to the operator without lengthy trial and error. After confirmation by the operator, the roller settings are automatically adjusted by the mechatronic straightening machine. With the presented method, the conventional iterative setup procedure can be made more resource-efficient and a high straightening quality can be reproducibly achieved.

An approach for an innovative 3d steel strip straightening machine for curvature and saber compensation

F. Bader, L. Bathelt, E. Djakow, C. Henke, W. Homberg, A. Trächtler, 2022

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Due to increasing globalization and rising quality requirements, the steel and metal processing industry is facing growing cost and innovation pressure. Not least because of their high lightweight potential, high-strength steel materials are meeting the growing material requirements of steel and metal processing in areas such as aerospace and medical technology. In particular, the tight tolerance limits of applicable shape and dimensional accuracies pose a challenge in the processing of high-strength steel strip materials. Improving the processability of high-strength steel materials through the use of straighteners with set-up assistance systems significantly increases the potential for competing with other materials such as aluminum or magnesium alloys.

Mechatronische Richtapparate: Intelligente Richttechnik von hochfesten Flachdrähten

L. Bathelt, F. Bader, E. Djakow, C. Henke, A. Trächtler, W. Homberg, in: Fachtagung VDI MECHATRONIK 2022 , 2022, pp. 19-24

Coupled microscopic and micromagnetic depth-specific analysis of plastic deformation and phase transformation of metastable austenitic steel AISI 304L by flow forming

J. Rozo Vasquez, H. Kanagarajah, B. Arian, L. Kersting, W. Homberg, A. Trächtler, F. Walther, Practical Metallography (2022), 59(11), pp. 660-675

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<jats:title>Abstract</jats:title> <jats:p>This paper presents the characterization of the microstructure evolution during flow forming of austenitic stainless steel AISI 304L. Due to plastic deformation of metastable austenitic steel, phase transformation from γ-austenite into α’-martensite occurs. This is initiated by the formation of shear bands as product of the external stresses. By means of coupled microscopic and micromagnetic investigations, a characterization of the microstructure was carried out. In particular, this study shows the distribution of the strain-induced α’-martensite and its influence on material properties like hardness at different depths. The microstructural analyses by means of electron backscattered diffraction (EBSD) technique, evidence a higher amount of α’-martensite (ca. 23 %) close to the outer specimen surface, where the plastic deformation and the direct contact with the forming tool take place. In the middle area (ca. 1.5 mm depth from the outer surface), the portion of transformed α’-martensite drops to 7 % and in the inner surface to 2 %. These results are well correlated with microhardness and micromagnetic measurements at different depths. EBSD and atomic force microscopy (AFM) were used to make a detailed characterization of the topography and degree of deformation of the shear bands. Likewise, the mechanisms of nucleation of α’-martensite were discussed. This research contributes to the development of micromagnetic sensors to monitor the evolution of properties during flow forming. This makes them more suitable for closed-loop property control, which offers possibilities for an application-oriented and more efficient production.</jats:p>

Innovative Online Measurement and Modelling Approach for Property-Controlled Flow Forming Processes

L. Kersting, B. Arian, J.R. Vasquez, A. Trächtler, W. Homberg, F. Walther, Key Engineering Materials (2022), 926, pp. 862-874

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<jats:p>The production of complex multi-functional, high-strength parts is becoming increasingly important in the industry. Especially with small batch size, the incremental flow forming processes can be advantageous. The production of parts with complex geometry and locally graded material properties currently depicts a great challenge in the flow forming process. At this point, the usage of closed-loop control for the shape and properties could be a feasible new solution. The overall aim in this project is to establish an intelligent closed-loop control system for the wall thickness as well as the α’-martensite content of AISI 304L-workpieces in a flow forming process. To reach this goal, a novel sensor concept for online measurements of the wall thickness reduction and the martensite content during forming process is proposed. It includes the setup of a modified flow forming machine and the integration of the sensor system in the machine control. Additionally, a simulation model for the flow forming process is presented which describes the forming process with regard to the plastic workpiece deformation, the induced α’-martensite fraction, and the sensor behavior. This model was used for designing a closed-loop process control of the wall thickness reduction that was subsequently realized at the real plant including online measured feedback from the sensor system.</jats:p>

Soft sensor concept for micromagnetic depth-specific analysis of phase transformation during flow forming of AISI 304L steel.

J. Rozo Vasquez, F. Walther, B. Arian, W. Homberg, L. Kersting, A. Trächtler, in: Proceedings of the 14th International Conference on Barkhausen Noise and Micromagnetic Testing, 2022

Produktkennzeichnung durch lokal definierte Einstellung von ferromagnetischen Eigenschaften beim Drückwalzen von metastabilen Stahlwerkstoffen

B. Arian, W. Homberg, L. Kersting, A. Trächtler, J. Rozo Vasquez, in: 36. Aachener Stahlkolloquium – Umformtechnik “Ideen Form geben“, 2022, pp. 333-347

A flow forming process model to predict workpiece properties in AISI 304L

B. Arian, A. Oesterwinter, W. Homberg, J. Rozo Vasquez, F. Walther, L. Kersting, A. Trächtler, in: 19th Int. Conference on Metal Forming 2022, 2022

Echtzeitfähige Modellierung eines innovativen Drückwalzprozesses für die eigenschaftsgeregelte Herstellung gradierter Bauteile.

L. Kersting, A. Trächtler, B. Arian, W. Homberg, J. Rozo Vasquez, F. Walther, Diedrich, 2022

Innendrückwalzen – Ein innovatives Umformverfahren zur inkrementellen Formgebung von wanddickenkonturierten Rohren mit lokal einstellbaren mechanischen Eigenschaften

E. Wiens, Shaker, 2022

2021

Experimental and Numerical Investigations into the Influence of the Process Parameters During the Deep Drawing of Fiber Metal Laminates

T. Heggemann, H. Sapli, W. Homberg, in: Forming the Future, 2021

DOI

Improving the Accuracy of Deep Drawn Fiber-Metal Laminate Parts by Preliminary Surface Treatment

D. Voswinkel, H. Sapli, D. Kloidt, T. Heggemann, W. Homberg, O. Grydin, M. Schaper, IOP Conference Series: Materials Science and Engineering (2021), 012028

DOI

Innovative Measurement Of Stress Superposed Steel Strip For Straightening Machines

F. Bader, L. Bathelt, E. Djakow, W. Homberg, C. Henke, A. Trächtler, ESAFORM 2021 (2021)

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<jats:p>Higher quality requirements by customers demand higher precision and accuracy from manufacturing processes. Application oriented preparation of semi-finished materials is key for subsequent forming operations, therefore, straightening machines are employed. Straightening strengthens the material by increasing plastic deformation by means of strain hardening, resulting in undesirable reduction in formability when processing high strength materials, in particular. Conventional roll-type straightening machines process either bars or strips. This is achieved upon passing material between rolls arranged in two staggered rows. However, conventional straightening processes do not adapt to the local varying distortion of coiled strips. Innovative, self-correcting process control techniques, which adapt to the initial geometric characteristics of the strip, present a promising approach to fix this issue through optimization of the leveling process. Here, an innovative strategy to improve straightening of high strength steel materials (1.4310) is presented. This implements optimized leveling, adding minimal plastic deformation and, thus, strain hardening. To operate an intelligent straightening machine, a reliable online measurement of the surface defects is fundamentally essential. The MagnaTest, which is developed for material testing, is made feasible for such purposes after calibrating for curvature measurement. Preliminary results are promising in regards to measuring the curvature online, so that the following straightening process can be close loop controlled. The bending measurement is linked to open/closed loop control, therefore providing an optimal straightening result in regards to formability, leveling, and reduced strain hardening.</jats:p>

Self-optimized, Intelligent Open-Loop-Controlled Steel Strip Straightening Machine for Advanced Formability

F. Bader, L. Bathelt, E. Djakow, W. Homberg, C. Henke, A. Trächtler, in: Forming the Future, 2021

Abstract

DOI

Innovative self-correcting process control techniques which adapt to the initial geometric characteristics of the strip are a promising approach to fix the local varying distortion of coiled strips by optimizing the leveling process. This paper presents an innovative strategy to improve straightening of AHSS materials (1.4310). This implies optimized leveling, adding minimal plastic deformation, and, thus, strain hardening. Therefore, an “intelligent straightening machine” is being developed which will be presented. To operate an intelligent straightening machine a reliable online measurement of the surface defects is fundamentally essential. This paper describes an approach towards the measurement of a bent steel strip for an automatic straightening process. Therefore, various ways of measuring the bending curvature are investigated. Optical, tactile, and the electromagnetic induction testing MagnaTest are compared with each other. The bending measurement is linked to open-loop control, providing an optimal straightening result in regards of formability, leveling, and reduced strain hardening.

Joining with Friction Spun Joint Connectors – Manufacturing and Analysis

C. Wischer, C. Steinfelder, W. Homberg, A. Brosius, IOP Conference Series: Materials Science and Engineering (2021), 1157, pp. 012007

Abstract

DOI

Nowadays, the production of modern lightweight structures, like a body in white structure requires a wide variety of mechanical joining processes. To fulfill the various demands, mechanical joining processes and joining elements (JE) are used. Very often, they are adapted to the application, which leads in turn to a numerous of different variants, high costs, and loss of the process chain versatility. To overcome this drawback, an innovative approach is the usage of individually produced and task-adapted JE, the so-called friction spun joint connectors (FSJC). These connectors can be modified in shape as well as in material properties. This flexibility offers high potential for lightweight design but also increases the necessary analytical effort regarding the forming process as well as the manufactured joint's properties. Therefore, a new analysis strategy based on the Finite-Element-Method (FEM) is proposed, which numerically determines the local load bearing capacity within a given joint in order to identify the critical regions for load transfer. The process of joining element manufacturing and the analysis strategy will be described in detail and optimization results of the joints are shown. Numerical results are discussed and possible recommendations for joint manufacturing are derived.

A contribution on versatile process chains: joining with adaptive joining elements, formed by friction spinning

C. Wischer, W. Homberg, Production Engineering (2021)

DOI

Friction-Induced Recycling Process for User-Specific Semi-Finished Product Production

T. Borgert, W. Homberg, Metals (2021), 663

Abstract

DOI

<jats:p>Modern forming processes often allow today the efficient production of complex parts. In order to increase the sustainability of forming processes it would be favorable if the forming of workpieces becomes possible using production waste. At the Chair of Forming and Machining Technology of the Paderborn University (LUF) research is presently conducted with the overall goal to produce workpieces directly from secondary aluminum (e.g., powder and chips). Therefore, friction-based forming processes like friction spinning (or cognate processes) are used due to their high efficiency. As a pre-step, the production of semi-finished parts was the subject of accorded research work at the LUF. Therefore, a friction-based hot extrusion process was used for the full recycling or rework of aluminum chips into profiles. Investigations of the recycled semi-finished products show that they are comparable to conventionally produced semi-finished products in terms of dimensional stability and shape accuracy. An analysis of the mechanical properties of hardness and tensile strength shows that a final product with good and homogeneously distributed properties can be produced. Furthermore, significant correlations to the friction spinning process could be found that are useful for the above-mentioned direct part production from secondary aluminum.</jats:p>

Cutting Blades for Food Processing Applications Manufactured Using Innovative Spin Forming

T. Rostek, H. Makeieva, W. Homberg, in: Proceedings of the 13th International Conference on the Technology of Plasticity, Springer, Cham, 2021, pp. 2115-2125

DOI

Investigations and Improvements in 3D-DIC Optical Residual Stress Analysis—A New Temperature Compensation Method

F. Dahms, W. Homberg, in: Forming the Future, Springer, Cham, 2021, pp. 2249-2259

DOI

Magnetic Barkhausen noise analysis for microstructural effects separation during flow forming of metastable austenite 304L.

J. Rozo Vasquez, B. Arian, M. Riepold, F. Walther, W. Homberg, A. Trächtler, in: Proceedings of the 11th International Workshop NDT in Progress, 2021

Forming of metastable austenitic stainless steel tubes with axially graded martensite content by flow-forming

B. Arian, W. Homberg, M. Riepold, A. Trächtler, J. Rozo Vasquez, F. Walther, ULiège Library, 2021

Abstract

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One of the main objectives of production engineering is to reproducibly manufacture (complex) defect-free parts. To achieve this, it is necessary to employ an appropriate process or tool design. While this will generally prove successful, it cannot, however, offset stochastic defects with local variations in material properties. Closed-loop process control represents a promising approach for a solution in this context. The state of the art involves using this approach to control geometric parameters such as a length. So far, no research or applications have been conducted with closed-loop control for microstructure and product properties. In the project on which this paper is based, the local martensite content of parts is to be adjusted in a highly precise and reproducible manner. The forming process employed is a special, property-controlled flow-forming process. A model-based controller is thus to generate corresponding correction values for the tool-path geometry and tool-path velocity on the basis of online martensite content measurements. For the controller model, it is planned to use a special process or microstructure (correlation) model. The planned paper not only describes the experimental setup but also presents results of initial experimental investigations for subsequent use in the closed-loop control of α’-martensite content during flow-forming.

https://popups.uliege.be/esaform21/index.php?id=2759

Model approaches for closed-loop property control for flow forming

M. Riepold, B. Arian, J.R. Vasquez, W. Homberg, F. Walther, A. Trächtler, Advances in Industrial and Manufacturing Engineering (2021), 100057

Abstract

DOI

The implementation of control systems in metal forming processes improves product quality and productivity. By controlling workpiece properties during the process, beneficial effects caused by forming can be exploited and integrated in the product design. The overall goal of this investigation is to produce tailored tubular parts with a defined locally graded microstructure by means of reverse flow forming. For this purpose, the proposed system aims to control both the desired geometry of the workpiece and additionally the formation of strain-induced α′-martensite content in the metastable austenitic stainless steel AISI 304 L. The paper introduces an overall control scheme, a geometry model for describing the process and changes in the dimensions of the workpiece, as well as a material model for the process-induced formation of martensite, providing equations based on empirical data. Moreover, measurement systems providing a closed feedback loop are presented, including a novel softsensor for in-situ measurements of the martensite content.

Forming of Parts with Locally Defined Mechanical and Ferromagnetic Properties by Flow-Forming

E. Wiens, W. Homberg, B. Arian, K. Möhring, F. Walther, in: Forming the Future, Springer International Publishing, 2021

DOI

Joining with versatile joining elements formed by friction spinning

C. Wischer, E. Wiens, W. Homberg, Journal of Advanced Joining Processes (2021), 3, 100060

DOI

Development of a novel adaptive joining technology employing Friction-Spun Joint Connectors (FSJC)

E. Wiens, C. Wischer, W. Homberg, 2021

2020

Combined Curing and Forming of Fiber Metal Laminates

T. Heggemann, W. Homberg, H. Sapli, Procedia Manufacturing (2020), pp. 36-42

DOI

Combined Curing and Deep Drawing of Fiber Metal Laminates to Spherical Hybrid Components

H. Sapli, T. Heggemann, W. Homberg, 2020

Microstructural investigation on phase transformation during flow forming of the metastable austenite AISI 304

J. Rozo Vasquez, B. Arian, M. Riepold, W. Homberg, A. Trächtler, F. Walther, in: 54. Metallographie-Tagung, 2020, pp. 75-81

Joining with Versatile Friction-Spun Joint Connectors

T. Rostek, E. Wiens, W. Homberg, Procedia Manufacturing (2020), 47, pp. 395-399

DOI

Some ideas for the further development of hydroforming process chains

E. Wiens, E. Djakow, W. Homberg, in: Nebu/Nehy 2020, 2020

Abstract

Even though the spectrum of parts is expected to shift over the long term as a result of increasing e-mobility, there is still an extremely high demand for complex components made of high-strength materials which can only be produced by hydroforming technologies. The innovative combination of hydroforming processes with other forming processes, as well as the improvement of the processes themselves, offers considerable potential for improvement. A number of promising ways of improving the hydroforming process chain are therefore the subject of this contribution. The focus of the article is on possible approaches for combining (incremental) pre- and post-forming operations, which can permit considerable improvements in both quality and features at a reduced cost. Furthermore, a novel combination of quasi-static and high-speed forming processes is presented, leading to an improved overall forming process (with a high application potential) for the production of complex parts.

2019

Deep drawing of fiber metal laminates for automotive lightweight structures

T. Heggemann, W. Homberg, Composite Structures (2019), pp. 53-57

Abstract

DOI

Current challenges in the automotive industry are the reduction of fuel consumption and the CO2 emissions of future car generations. These aims can be achieved by reducing the weight of the car, which further improves the driving dynamics. In most currently mass-produced cars, the body accounts for one of the largest parts by weight, and hence designing a lightweight car body assumes great importance for reducing fuel consumption and CO2 emissions. Extremely lightweight designs can be achieved by using purely composite materials, which are very light but also highly cost intensive and not yet suitable for large scale production due to the necessity of manual processing. A promising approach for the automated, large-scale production of lightweight car structures with a high stiffness to weight ratio is the combination of high strength steel alloys and CFRP prepregs in a special hybrid material/fiber metal laminate (FML) – which can be further processed by forming technologies such as deep drawing. In current research work at the Chair of Forming and Machining Technology (LUF) at the University of Paderborn, innovative manufacturing processes are being developed for the production of high strength automotive structural components made of fiber metal laminates. This paper presents the results of technological and numerical research that is currently being performed at the LUF into the forming of hybrid fiber metal laminates. This paper focuses on the results of basic research and the individual measures (tool, process and material design) necessary for achieving the desired part quality.

Intrinsically lubricated tool inserts for deep drawing applications generated by selective laser melting

F. Bader, F. Hengsbach, K. Hoyer, W. Homberg, M. Schaper, in: PROCEEDINGS OF THE 22ND INTERNATIONAL ESAFORM CONFERENCE ON MATERIAL FORMING: ESAFORM 2019, 2019

Abstract

DOI

Abstract. Within the scope of this study, an intrinsically lubricated deep drawing die fabricated via laser beam melting (LBM) is investigated. In contrast to the common objective of generating highly dense LBM components, this work endeavors to achieve intended micro-scale porosity. By utilizing permeable structures, in-process closed-loop control of lubrication during the forming operations is feasible. Based on a modified AM scan strategy, the required filigree, porous structures can be generated. Thus, in the present work three permeable specimens are additively generated from the maraging steel 1.2709. The cylindrical specimens are then analyzed via light microscopy (LM), microcomputer tomography (microCT), and with regard to the oil throughput rate. Subsequently, an intrinsically lubricated, AM deep drawing tool die is manufactured and experimentally tested. The findings reveal interesting results for deep drawn specimens with AM deep drawing dies.

Al2O3/ZrO2-8Y2O3 and (Cr,Ti)AlSiN tool coatings to influence the temperature and surface quality in friction-spinning processes

W. Tillmann, A. Fehr, D. Stangier, M. Dildrop, W. Homberg, B. Lossen, D. Hijazi, Production Engineering (2019), pp. 449-457

Abstract

DOI

Friction-spinning is an incremental forming process, which is accompanied by complex thermal and mechanical loads in the tool and the formed part. To influence the process temperature, two main process parameters, i.e. the rotation speed and the feed rate, can be adapted. With the objective to improve the tool performance and the quality of the workpiece, this study focuses on a coating concept for friction-spinning tools made of high speed steel (HS6 5 2C, 1.3343). On the one hand, atmospheric plasma sprayed (APS) Al2O3 and ZrO2-8Y2O3 coatings serve as a thermal insulator, and, on the other hand, physically vapor deposited (PVD) TiAlSi7.9N and CrAlSi7.5N films are applied to increase the hardness and wear resistance of the tools. In addition, duplex coatings, combining the APS and PVD technique, are synthesized to influence both the heat transfer and the tribological properties of friction-spinning tools. Subsequently, all coated tools are tested in a friction-spinning process to form flanges made of AW-6060 (AlMgSi 3.3206) tube materials. The tool temperatures are determined in-situ to investigate the impact of the tool coating on the process temperature. Compared to an uncoated tool, the alumina and zirconia coatings contribute to a reduction of the tool temperature by up to half, while the PVD films increase the hardness of the tool by 20 GPa. Furthermore, it is shown that the surface quality of thermally sprayed (TS) or PVD coated tools is directly related to the surface roughness of the resulting workpiece.

Ein Beitrag zur kombinierten (quasi-)statischen und dynamischen Umformung von blechförmigen Halbzeugen

E. Djakow, Shaker, 2019

Abstract

DOI

Working-media-based forming processes (WMBF) represent a great potential regarding the production of complex sheet-metal lightweight components with excellent surface quality, shape accuracy and dimensional stability. The working-media-based forming processes characterize the sheet-metal forming process, where the sheet metal blank is formed during the forming process by means of a (quasi-)static or dynamic working media pressure into a contouring forming tool. Although the WMBF offers improved utilization of the formability of the used materials compared to conventional sheet metal forming processes, there are limits in the production of complex deeper or sharp edged components with (quasi-)static and dynamic WMBF processes, which can not be overcome by using these methods alone. In order to overcome this, multi-level WMBF process sequences for components with spherical and stepped geometries are developed in this work. Here the developed strategies combine the advantages of (quasi-)static and dynamic WMBF processes. Furthermore, based on analytical, experimental and numerical investigations, innovative process management strategies were derived, which completely compensate the local wall thickness changes, make better use of existing material resources and thus enable the safe production of mentioned geometries.

High-Speed Incremental Forming – New Technologies For Flexible Production Of Sheet Metal Parts

M. Linnemann, V. Psyk, E. Djakow, R. Springer, W. Homberg, D. Landgrebe, Procedia Manufacturing (2019), pp. 21-26

DOI

Heat transfer enhancement in pillow-plate heat exchangers with dimpled surfaces: A numerical study

M. Piper, A. Zibart, E. Djakow, R. Springer, W. Homberg, E. Kenig, Applied Thermal Engineering (2019), pp. 142-146

DOI

Ein Beitrag zur kombinierten (quasi-)statischen und dynamischen Umformung von blechförmigen Halbzeugen

E. Djakow, 2019

Simulationsgestützte Analyse und Optimierung der Umformung geschlossener Stahlprofile mittels Hamburger Verfahren

D. Tabakajew, 2019

Ein Beitrag zum stoffschlüssigen Fügen durch plastische Deformation: partielles Kaltpressschweißen durch inkrementelles Walzen

H.C. Schmidt, 2019

Ein Beitrag zur Herstellung von hybriden Bauteilen mittels Reibdrücken

B. Lossen, 2019

Improved set up strategies for steel strip straightening machines

T. Rostek, W. Homberg, in: AIP Conference Proceedings 2113, 170018, AIP Publishing, 2019

DOI

Forming analysis of tailored tubes with an internal contoured wall thickness and external axial ribs manufactured by internal flow-turning

E. Wiens, W. Homberg, in: PROCEEDINGS OF THE 22ND INTERNATIONAL ESAFORM CONFERENCE ON MATERIAL FORMING: ESAFORM 2019, 2019

DOI

2018

Optimization of Tooling Design for Hot Mandrel Bending of Pipe Elbows

U. Diekmann, W. Homberg, J. Prehm, T. Rostek, N. Schönhoff, D. Tabakajew, A. Trasca, H. Uysal, in: Materials Science Forum, Trans Tech Publications Ltd, 2018, pp. 159-164

Abstract

DOI

<jats:p>This paper presents the finite element model developed for the simulation of pipe elbow production by the so-called ‘Hamburg process’ in order to improve productivity and resource efficiency. To optimize the tooling design, a sensitivity analysis of the tool parameters that influence the quality of pipe elbows, such as mandrel height and length, is conducted. Different materials data sets including damage models were considered. Using numerical simulations, it is possible to determine an optimized tool geometry for the production of specific pipe elbow dimensions. Furthermore, as a result of the experiments and numerical simulations conducted, it is possible to increase the production velocity of the serial plant. Along with deformation, damage models are included in simulations in order to identify the right process boundaries. Finally, an experimentally validated model is developed for increasing resource efficiency in pipe elbow fabrication.</jats:p>

Grading Technologies for the Tanufacture of Innovative Cutting Blades

T. Rostek, W. Homberg, in: AIP Conference Proceedings 1960, 100013, AIP Publishing, 2018

DOI

Hybride Verbundstrukturen aus Aluminium und Titan für Leichtbauanwendungen

W. Homberg, T. Rostek, M. Schaper, O. Grydin, A. Andreiev, A. Brosius, C. Guilleaume, Universität Paderborn, 2018, pp. 28-33

Herstellung innovativer Stahlhalbzeuge mit wanddicke- und festigkeitsveränderlichen Eigenschaften für den Leichtbau durch Innendrückwalzen (IDW)

E. Wiens, W. Homberg, 2018

Internal Flow-Turning – extended manufacturing possibilities in tailored tube production

E. Wiens, W. Homberg, MATEC Web of Conferences (2018), 11002

DOI

LHYBS – Lightweight Design by Novel Hybrid Materials

A.A. Camberg, T. Tröster, T. Heggemann, H. Homberg, M. Schaper, J. Dietrich, W. Bremser, L. Achterberg, M. Kabst, M. Wille, V. Peckhaus, 2018

Friction-spinning—Grain structure modification and the impact on stress/strain behaviour

B. Lossen, A. Andreiev, M. Stolbchenko, W. Homberg, M. Schaper, Journal of Materials Processing Technology (2018), pp. 242-250

DOI

Liste im Research Information System öffnen

Veröffentlichungen

Jahr 2017: Schmidt, H.C.; Grydin, O.; Stolbchenko, M.; Homberg, W.; Schaper, M.: „Manufacturing of thin-walled clad tubes by pressure weldings of roll bonded sheets“. AIP Conference Proceedings, Volume 1896, 2017

Homberg, W.; Rostek, T.; Schaper, M.; Grydin, O.; Andreiev, A.; Brosius, A.; Tulke, M.:” Development of hybrid directionally reinforced structural parts for lightweight applications”. AIP Conference Proceedings, Volume 1896, 2017

Djakow, E.; Springer, R.; Homberg, W.; Piper, M.; Tran, J.; Zibart, A.; Kenig, E.: „Incremental electrohydraulic forming - A new approach for the manufacture of structured multifunctional sheet metal blanks”. AIP Conference Proceedings, Volume 1896, 2017

Spoelstra, P.; Djakow, E.; Homberg, W.: “Rubber pad forming - Efficient approach for the manufacturing of complex structured sheet metal blanks for food industry”. AIP Conference Proceedings, Volume 1896, 2017

Lossen, B.; Andreiev, A.; Homberg, W.; Schaper, M.: „Friction-spinning-possibility of grain structure adjustment“. Procedia Engineering, Volume 207, Seiten 1749-1754, 2017

Tabakajew, D.; Homberg, W.: “Increasing the efficiency of hot mandrel bending of pipe elbows”, Procedia Engineering Volume 207, Seiten 2310-2315, 2017

Wiens, E.; Homberg, W.: “Internal Flow-Turning – a new approach for the manufacture of tailored tubes with a constant external diameter”. Procedia Engineering Volume 207, Seiten 1755-1760, 2017

Rostek, T.; Homberg, W.: “Locally Graded Steel Materials for Self-Sharpening Cutting Blades”. rocedia Engineering Volume 207, Seiten 2185-2190, 2017
Jahr 2016: Djakow, E.; Homberg, W.; Tabakajew, D.: 'Combined working media-based forming on a pneumo-mechanical high speed forming machine'. Proceedings of the ICHSF 2016, Dortmund, Germany

Homberg, W. & Lossen, B. (2016), Reib-Drücken – Neue Möglichkeiten im Bereich der inkrementellen Umformung, Hrsg. Brosius, A., '23. Sächsische Fachtagung Umformtechnik SFU 2016 - Tagungsband', S. 82-90

Hordych, I.; Rodman, D.; Nürnberger, F.; Hoppe, C.; Schmidt, H. C.; Grundmeier, G.; Homberg, W. & Maier, H. J. (2016), 'Effect of Pre-Rolling Heat Treatments on the Bond Strength of Cladded Galvanized Steels in a Cold Roll Bonding Process', steel research int.

Schmidt, H. C.; Homberg, W.; Hoppe, C.; Grundmeier, G.; Hordych, I. & Maier, H. J. (2016), 'Cold pressure welding by incremental rollng: deformation zone analysis', AIP Conference Proceedings 1769, 100013 (2016), S. 100013-1 - 100013-6.

Hoppe, C. & Schmidt, H. C. (2016), Elektrochemisch unterstütztes Fügen von blechförmigen Werkstoffen durch Umformen (ECUF), ILH Insight 2, Universität Paderborn, S. 22-24.

Lossen, B; Homberg, W: Friction spinning – Twist phenomena and the capability of influencing them. AIP Conference Proceedings 1769, 070001 (2016), S. 070001-1 - 070001-6.

Rostek, T.; Homberg, W.: Layered Steel Materials for the Manufacture of Self-Sharpening Cutting Blades. In: Chinestra, F.: International Journal of Material Forming, AIP Conference Proceedings, Nantes, France, 2016.
Jahr 2015: Homberg, W. & Lossen, B.Tekkaya, A. E.; Homberg, W. & Brosius, A., ed., (2015), 60 Excellent Inventions in Metal Forming, Springer Vieweg, chapter Friction Spinning - Innovative Opportunity for Overcoming Process Limits in Spinning Processes, pp. 149-154.

Homberg, W.; Rostek, T. & Wiens, E. (2015), 'Internal Flow-Turning - An Innovative Technology for the Manufacture of Tailored Tubes', Key Engineering Materials 639, 65--70.

Lossen, B. & Homberg, W. (2015), 'Friction-Spinning - Influence of Tool and Machine Parameters on the Surface Texture', Key Engineering Materials 651-653, 1109--1114.

Schmidt, H. C.; Ebbert, C.; Rodman, D.; Homberg, W.; Grundmeier, G. & Maier, H. J. (2015), 'Investigation of Cold Pressure Welding: Cohesion Coefficient of Copper', Key Engineering Materials 651-653, 1421--1426.

Homberg, W. & Rostek, T. (2015), Innovative Processing Techniques for the Manufacture of High-Performance Active Elements from Ultra High-Strength Steel Plate, in NN, ed., 'Proceedings of METEC & 2nd ESTAD'.

Rostek, T. (2015), 'Ein Beitrag zur Verarbeitung von Dickblech aus ultrahochfesten Stahlwerkstoffen', PhD thesis, Universität Paderborn.
Jahr 2014: Homberg, W.; Djakow, E. & Damerow, O. (2014), Process reliability and reproducibility of pneumomechanical and electrohydraulic forming processes, in NN, ed., 'International Conference on high speed forming 2014'.

Damerow, U.; Borzykh, M.; Tabakajew, D.; Schaermann, W.; Homberg, W. & Trächtler, A. (2014), 'Analysis of High Speed Bending Operations as Basis for Integrating Self-correcting Components to Increase Process Reliability', Procedia Engineering 81(0), 831 - 836.

Hess, S.; Lossen, B.; Biermann, D.; Homberg, W. & Wagner, T. (2014), 'Analysis of the surface roughness obtained in a friction spinning process based on empirical models', The International Journal of Advanced Manufacturing Technology Vol. 74(Issue 9 - 12), 1655 – 1665.

Damerow, U.; Tabakajew, D.; Borzykh, M.; Schaermann, W.; Homberg, W. & Trächtler, A. (2014), 'Concept for a Self-correcting Sheet Metal Bending Operation', Procedia Technology 15(0), 439 - 446.

Lossen, B. & Homberg, W. (2014), Friction-Spinning – Interesting approach to the manufacture of complex sheet metal parts and tubes, in Takashi Ishikawa & Ken ichiro Mori, ed., 'Procedia Engineering of the 11th ICTP', Elsevier, Nagoya, Japan, pp. 2379 - 2384.

Homberg, W.; Djakow, E. & Damerow, O. (2014), Process reliability and reproducibility of pneumomechanical and electrohydraulic forming processes, in A E. Tekkaya & H. Huh, ed., '7th International Conference on High Speed Forming, 26th - 29th May 2014', pp. 217-228.

Ebbert, C.; Schmidt, H. C.; Rodman, D.; Nürnberger, F.; Homberg, W.; Maier, H. J. & Grundmeier, G. (2014), 'Joining with electrochemical support (ECUF): Cold pressure welding of copper', Journal of Materials Processing Technology 214(10), 2179-2187.

Schmidt, H. C.; Rodman, D.; Grydin, O.; Ebbert, C.; Homberg, W.; Maier, H. J. & Grundmeier, G. (2014), 'Joining with electrochemical support: cold pressure welding of copper - weld formation and characterization', Advanced Materials Research 966-967, 453-460.

Stein, T.; Brueckner-Foit, A.; Lossen, B. & Homberg, W. (2014), 'Fatigue Crack Extension in an Incrementally Formed Tube', Procedia Materials Science of 20th European Conference on Fracture Vol. 3, 1884 - 1889.
Jahr 2013: Homberg, W.; Djakow, E. & Akst, O. (2013), 'The investigation of a pneumo-mechanical high speed forming process with respect to the forming of complex sheet and tube components', Journal of mechanical engineering (Vesnik) 67, 180-188.

Homberg, W. & Lossen, B.Heim, H. P.; Biermann, D. & Homberg, W., ed.,(2013), Thermal assisted incremental forming of tubes and sheets with process-integrated heat generation, Verlag Wissenschaftliche Scripten, Auerbach, chapter 2.6, pp. 113-128.

Homberg, W. & Lossen, B.Homberg, W.; Biermann, D. & Heim, H.-P., ed.,(2013), Thermal assisted incremental forming of tubes and sheets with process-integrated heat generation - Fundamentals, Verlag Wissenschaftliche Scripten, Auerbach, chapter 2.2.3, pp. 43-76.

Homberg, W.; Lossen, B. & Struwe, A. (2013), 'An Innovative Incremental Forming Process for the Manufacturing of Functional Graded Parts', Key Engineering Materials 554-557, 1368-1374.

Hornjak, D. (2013), 'Grundlegende Untersuchung der Prozess- und Werkzeugparameter und ihrer Wechselwirkung für das thermo-mechanisch unterstützte inkrementelle Umformverfahren des Reib-Drückens', PhD thesis, Universität Paderborn.

Schmidt, H. C.; Homberg, W.; Grundmeier, G. & Maier, H. J. (2013), 'Partial joining of blanks with electrochemical support (ECUF)', Key Engineering Materials 554-557, 1091-1095.

Schmidt, H. C. & Homberg, W. (2013), Hybrid - Neue Werkstoffe und Prozesse für den Leichtbau, in Alexander Brosius, ed., '20. Sächsische Fachtagung Umformtechnik - Tagungsband', pp. 25-32.

Schmidt, H. C. & Lauter, C. (2013), 'Stahl-CFK-Strukturen wie Tiefziehteile fertigen', Maschinen Markt – Composites World Ausgabe März, 22-25.
Jahr 2012: Damerow, U.; Borzykh, M.; Homberg, W. & Trächtler, A. (2012), 'A Self-Correcting Approach for the Bending of Metal Parts', Key Engineering Materials 504-506, 907-912.

Borzykh, M.; Damerow, U.; Henke, C.; Trächtler, A. & Homberg, W. (2012), 'Model-Based Design of Self-Correcting Strategy for a Punch Bending Machine', Information Control Problems in Manufacturing 14(1), 1551-1555.

Hankeln, F.; Schmidt, H. C.; Damerow, U.; Mahnken, R.; Maier, H. J.; Troester, T. & Homberg, W. (2012), 'Simulation and Manufacturing of Deep Drawn Parts Reinforced by Carbon Fibre Prepregs', in NN, ed., Turin, Italien.

Homberg, W.; Schmidt, H. C.; Struwe, A. & Akst, O. (2012), 'New Materials - Driver for Innovative Production Processes', in NN, ed., Mumbai, Indien.

Homberg, W.; Djakow, E. & Akst, O. (2012), 'Some aspects regarding the use of a pneumomechanical high speed forming process', in NN, ed., 'Proceedings of the 5th International Conference on High Speed Forming', Dortmund, pp. 23-32.

Homberg, W.; Lossen, B. & Hornjak, D.Spur, G.; Neugebauer, R. & Hoffmann, H., ed.,(2012), Wärmeeintrag durch Reibung (Reib-Drücken), Hanser Fachbuchverlag, Muenchen, chapter 9.1.2.2, pp. 648-649.

Homberg, W.; Hornjak, D. & Lossen, B. (2012), Friction-Spinning - A New Innovative Thermal Assisted Incremental Forming Process for the Manufacture of Complex Functionally Graded Workpieces, in Hans Peter Heim; D. Biermann & Hans Jürgen Maier, ed., '1st International Conference on Thermo-Mechanically Graded Materials', pp. 115-120.

Homberg, W.; Hornjak, D.; Lossen, B. & Struwe, A. (2012), New Innovative Tool Systems for the Production of Workpieces with Tailor-made Properties by Friction Spinning, in J. Kusiak; J. Majta & D. Szeliga, ed., 'Metal Forming 2012 - 14th International Conference', Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, pp. 619-622.

Homberg, W. & Lossen, B. (2012), 'Reib-Drücken - Ein innovativer Ansatz zur effizienten Herstellung von funktional gradierten Bauteilen aus Aluminium- und Stahlwerkstoffen', in NN, ed., , Pforzheim, Deutschland.

Homberg, W. & Djakow, E. (2012), 'The investigation of a pneumomechanical high speed forming process', Journal of mechanical engineering (Vesnik) 64, 172-177

Schmidt, H. C.; Damerow, U. & Homberg, W. (2012), Effiziente Herstellung hybrider Strukturbauteile aus Stahl und CFK - Gemeinsame Umformung von Einzel- und Doppelblechen mit CFK-Prepregs, in R. Neugebauer & W.G. Drossel, ed., '19. Sächsische Fachtagung Umformtechnik SFU 2012 - Tagungsband', pp. 195-203.

Schmidt, H. C.; Damerow, U. & Homberg, W. (2012), 'Manufacturing of Hybrid Reinforced Structures: Combined Forming of Double Blanks with Carbon Fibre Prepregs', in NN, ed., 'Proceedings of the 3rd International Conference on New Forming Technology', Harbin (China).

Schmidt, H. C.; Damerow, U.; Lauter, C.; Gorny, B.; Hankeln, F.; Homberg, W.; Troester, T.; Maier, H. J. & Mahnken, R. (2012), 'Manufacturing processes for combined forming of multi-material structures consisting of sheet metal and local CFRP reinforcements', Key Engineering Materials 504-506, 295-300.
Jahr 2011 und älter: Dau, J.; Lauter, C.; Damerow, U.; Homberg, W. & Tröster, T. (2011), 'Multi-material systems for tailored automotive structural components', in NN, ed., , Jeju, South Korea.

Homberg, W.; Dau, J. & Damerow, U. (2011), 'Combined Forming of Steel Blanks with Local CFRP Reinforcement', steel research international Special Edition, 441-446.

Homberg, W.; Damerow, U. & Beerwald, C. (2010), Hydroforming von Blechen und Rohren - Ansatzpunkte für eine effiziente Fertigung von Leichtbaustrukturen, in R. Kawalla, ed., 'SFU, 17. Sächsische Fachtagung Umformtechnik', pp. 202-211.

Vollertsen, F. & Beckmann, M. (2006), Umformen strukturierter Platinen mit Mehrfachmembranen im Sinne eines robusten Fertigungsprozesses, in M. Kleiner, ed., 'Abschlussbericht zum DFG-Schwerpunktprogramm SPP 1098 'Wirkmedienbasierte Fertigungstechniken zur Blechumformung'', Shaker Verlag, Aachen.

Göbel, R.; Brosius, A.; Muresan, C. I.-O.; Jadhav, S.; Homberg, W. & Kleiner, M. (2004), Modellierung inkrementeller Blechumformprozesse mit kinematischer Gestalterzeugung, in NN, ed., 'Kolloquium DFG SPP 1146 Modellierung Inkrementeller Umformverfahren am 30.3.2004 in Saarbrücken'.

Homberg, W.; Marré, M. & Kleiner, M. (2004), 'Umformtechnisches Fügen leichter Tragwerkstrukturen', Aluminium 80(12), 1396-1399.

Kleiner, M.; Kopp, R.; Homberg, W.; Krahn, M.; Krux, R. & v. Putten, K. (2004), 'High-Pressure Sheet Metal Forming of Tailor Rolled Blanks', Annals of the WGP, Production Engineering 11(2), 109-114.

Kleiner, M.; Krux, R. & Homberg, W. (2004), 'Analysis of Residual Stresses in High-Pressure Sheet Metal Forming', CIRP Annals - Manufacturing Technology 53(1), 211 - 214.

Kleiner, M. & Homberg, W. (2004), 'Prozessführung und Werkzeuggestaltung bei der elektromagnetischen Blechumformung'(433), Technical report, Universität Dortmund, 'Untersuchung der Wirkmechanismen der Elektromagnetischen Blechumformung'.

Kleiner, M.; Homberg, W. & Trompeter, M. (2004), Prozessführungsstrategien für die Hochdruck-Blech-Umformung großflächiger und schwer umformbarer Blechformteile, in NN, ed., 'Tagungsband zum EFB-Kolloqium 'Lösungen für die Verarbeitung moderner Blechwerkstoffe' am 23./24.3.2004 in Fellbach'.

Kleiner, M.; Homberg, W. & Trompeter, M. (2004), Prozessführungsstrategien für die Hochdruck-Blech-Umformung großflächiger und schwer umformbarer Blechformteile, in NN, ed., 'EFB-Kolloquium 'Lösungen für die Verarbeitung moderner Blechwerkstoffe' am 23./24.3.2004 in Fellbach'.

Kleiner, M.; Homberg, W. & Trompeter, M. (2004), Process and Material Flow Control for High Pressure Metal Forming Operations, in NN, ed., 'Proceedings of the IDDRG-Conference 'Forming the Future' 24.-26.5.2004 in Sindelfingen (Germany)', Verlag Stahleisen GmbH, Düsseldorf.

Krux, R.; Homberg, W. & Kleiner, M. (2004), Hochdruck-Blech-Umformung von flexibel gewalzten Blechen mittels steuerbarem Dichtungssystem, in NN, ed., 'Tagungsband zum 3. Kolloquium 'Wirkmedien-Blechumformung' am 10.12.2003 in Stuttgart'.

Krux, R.; Brosius, A.; Homberg, W. & Kleiner, M. (2004), 'Mehr Prozesssicherheit beim wirkmedienbasierten Lochen – Verwendung einer Stempelprofilierung', Stahl 2, 76-77.

Krux, R.; Kleiner, M.; Homberg, W. & Trompeter, M. (2004), Herstellung von großflächigen Strukturbauteilen aus Platinen mit optimiertem Blechdickenverlauf mittels der Hochdruck-Blech-Umformung, in NN, ed., 'Tagungsband zum 10. IHU-Forum am 25./26.2.2004 in Darmstadt'.

Psyk, V.; Beerwald, C.; Homberg, W. & Kleiner, M. (2004), 'Electromagnetic Forming of Tube and Sheet Metal for Automotive Parts'(EMF GRD2-2001-50057), Technical report, LFU, TU Dortmund.

Psyk, V.; Beerwald, C.; Homberg, W. & Kleiner, M. (2004), Electromagnetic Compression as Preforming Operation for Tubular Hydroforming Parts, in NN, ed., 'Proceedings of the 1st International Conference on High Speed Forming, March 31 - April 1 2004, University of Dortmund', pp. 171-180.

Trompeter, M.; Homberg, W. & Kleiner, M. (2004), Grundlagenuntersuchung zur Prozessführung bei der wirkmedienbasierten Blechumformung, in DFG, ed., 'Tagungsband zum 3. Kolloquium 'Wirkmedien-Blechumformung' am 10.12.2003 in Stuttgart'.

Wellendorf, A.; Homberg, W. & Kleiner, M. (2004), Thin Sheet Metal Hydroforming, in NN, ed., 'Proceedings of the IDDRG-Conference 'Forming the Future' 24.-26.5.2004 in Sindelfingen (Germany)', Verlag Stahleisen GmbH, Düsseldorf.

Wellendorf, A.; Schikorra, M.; Homberg, W. & Kleiner, M. (2004), Investigations in the Field of Conventional and Working Media Based Forming of Complex Thin Sheet Metal Parts, in NN, ed., 'Proceedings of the IDDRG-Conference 'Forming the Future' 24.-26.5.2004 in Sindelfingen (Germany)', Verlag Stahleisen GmbH, Düsseldorf, pp. 374-378.

Beerwald, C.; Brosius, A.; Homberg, W. & Kleiner, M. (2003), Extended finite element modelling of electromagnetic forming, in NN, ed., 'Proceedings of the 10th International Conference on Sheet Metal'.

Homberg, W.; Kleiner, M. & Trompeter, M. (2003), Blecheinzugsensoren für die Hochdruck-Blech-Umformung, in NN, ed., 'Tagungsband zum 2. Kolloquium 'Wirkmedien-Blechumformung' am 11.12.2002 in Dortmund'.

Jadhav, S.; Goebel, R.; Homberg, W. & Kleiner, M. (2003), Process Optimization and Control for Incremental Sheet Metal Forming, in NN, ed., 'Proceedings of the Conference of the IDDRG 2003'.

Kleiner, M.; Homberg, W.; Beerwald, C. & Trompeter, M. (2003), Flange Draw-in Sensor for the High Pressure Sheet Metal Forming, in NN, ed., 'Proceedings of the 10th International Conference on Sheet Metal'.

Kleiner, M.; Homberg & Trompeter, M. (2003), Hochdruck-Blech-Umformung großflächiger Blechformteile, in NN, ed., 'Tagungsband zur Konferenz 'Hydroumformung' am 28./29.10.2003 in Fellbach', DGM Verlagsgesellschaft, Fellbach.

Krux, R.; Homberg, W. & Kleiner, M. (2003), 'Prozesskette für das Rapid Tooling mit lamellierten Tief- und Streckziehwerkzeugen', Stahl 1, 42-44.

Krux, R.; Brosius, A.; Kleiner, M. & Homberg, W. (2003), 'Prozessintegriertes Lochen und Trennen bei Hochdruckumformprozessen'(446), Technical report, Studiengesellschaft Stahlanwendung e.V., Düsseldorf.

Krux, R.; Homberg, W. & Kleiner, M. (2003), 'Prozesskette für das Rapid Tooling mit lamellierten Tief- und Streckziehwerkzeugen', Stahl 1, 42-44.

Theymann, O.; Homberg, W. & Kleiner, M. (2003), Prozessführungsstrategie zur Halbwarm-Blechumformung mit gasförmigen Druckmedien, in DFG, ed., '3. Kolloquium DFG-SPP 1098 'Wirkmedien-Blechumformung', 10.12.2003, Stuttgart'.

Trompeter, M.; Homberg, W. & Kleiner, M. (2003), Hochdruck-Blech-Umformung großflächiger Blechformteile mit schwer herstellbaren Nebenformelementen, in DFG, ed., '3. Kolloquium DFG-SPP 1098 'Wirkmedien-Blechumformung', 10.12.2003, Stuttgart', pp. 13-20.

Homberg, W.; Gather, U.; Kleiner, M.; Klimmek, C. & Kuhnt, S. (2002), Parameter Design for Sheet Metal Hydroforming Processes, in J. Yanagimoto M. Kiuchi, H. Nishimura, ed., 'Proceedings of the 7th ICTP'.

Kleiner, M.; Göbel, R.; Kantz, H.; Klimmek, C. & Homberg, W. (2002), Combined Methods for the Prediction of Dynamic Instabilities in Sheet Metal Spinning, in NN, ed., 'Proceedings of the 52th CIRP General Assembly'.

Kleiner, M.; Homberg, W. & Wellendorf, A. (2002), Sheet metal hydroforming for car body applications, in NN, ed., 'Tagungsband des 3. Chemnitzer Karosseriekolloquium CBC 2002 am 25./26.09.2002 in Chemnitz'.

Klimmek, C.; Homberg, W.; Kantz, H.; Kleiner, M. & Reitmann, V. (2002), Finite Element Analysis of Sheet Metal Forming by Spinning, in J. Yanagimoto M. Kiuchi, H. Nishimura, ed., 'Proceedings of the 7th ICTP'.

Friebe, E.; Langhammer, T.; Corsten, P.; Kleiner, M.; Homberg, W.; Wellendorf, A.; Birkert, A.; Trösken, F.; Carl, M.; Krautschick, J. & Papaiacouvou, P. (2001), 'Herstellung eines Kraftstofftanks komplexer Geometrie aus Stahl mit Hilfe der Hydroumformung'(410), Technical report, Studiengesellschaft Stahlanwendung e.V., Düsseldorf.

Homberg, W. & Kleiner, M. (2001), Wirkmedienbasierte Umformung von Stahlblechen, in NN, ed., 'Tagungsband zum Kolloquium 'Wirkmedienbasierte Umformung von Rohren und Blechen Fertigungsverfahren für intelligente Leichtbauteile' am 08./09.05.2001 in Essen'.

Homberg, W.; Klimmek, C.; Kleiner, M. & Strauch, A. (2001), 'Wirkmedienbasierte Blechumformung Umformtechnologien für die Anforderungen von morgen', Stahl 10.

Homberg, W. & Kleiner, M. (2001), Verfahren, Werkzeuge und Werkzeugmaschine zur Hochdruck-Blech-Umformung, in NN, ed., 'Tagungsband des Kolloquiums 'Wirkmedien-Blechumformung' am 11.12.2001 in Dortmund'.

Kleiner, M.; Homberg, W.; Göbel, R. & Klimmek, C. (2001), 'Process Optimisation in Sheet Metal Spinning', WGP Production Engineering - Research and Development 8(2).

Kleiner, M.; Homberg, W.; Klimmek, C.; Röntgen, P. & Matter, H. (2001), 'Statusbericht zur Forschung und Anwendung der wirkmedienbasierten Blechumformung'(520), Technical report, Studiengesellschaft Stahlanwendung e.V., Düsseldorf.

Kleiner, M. & Homberg, W. (2001), Hochdruck-Blech-Umformung - Verfahren, Werkzeugsystem und Umformmaschine, in F. Vollertsen & M. Kleiner, ed., 'Idee - Vision - Innovation – Festschrift anläßlich des 60. Geburtstags von Professor Manfred Geiger', Verlag Meisenbach, Bamberg, pp. 315-320.

Kleiner, M.; Beerwald, C. & Homberg, W. (2001), Machine Tools and Process Strategies for Sheet Metal Hydroforming, in NN, ed., 'Proceedings of the 9th International Conference On Sheet Metal'.

Kleiner, M.; Homberg, W.; Warnke, E.-P. & Voß, W. (2001), 'Vorgespannter Gussrahmen für eine 100 MN Hydroformpresse', ZWF Zeitschrift für wirtschaftlichen Fabrikbetrieb 9, 474-476.

Kleiner, M. & Homberg, W. (2001), Neue 100.000 kN-Presse für die Hydro-Blechumformung, in NN, ed., 'Tagungsband zur Konferenz 'Hydroumfomung' am 6. und 7.11.2001 in Fellbach'.

Krux, R.; Homberg, W. & Kleiner., M. (2001), 'Verwendung von Zwischenlagenwerkstoffen für lamellierte Tief- und Streckziehwerkzeuge', UTF Science 2(1), 15-19.

Wellendorf, A.; Homberg, W.; Kleiner, M.; Langhammer, T. & Birkert, A. (2001), Methodenplanung für die Wirkmedien-Blechumformung am Beispiel eines Stahltanks, in NN, ed., 'Tagungsband des Kolloquiums 'Wirkmedien-Blechumformung' am 11.12.2001 in Dortmund'.

Birkert, A.; Homberg, W.; Kleiner, M. & Langhammer, T. (2000), Herstellung eines Kraftstofftanks komplexer Geometrie aus rostfreiem Stahl, in NN, ed., 'Tagungsband zum Kolloquium 'Stahl für moderne Automobile' am 16.3.2000 in Frankfurt am Main'.

Homberg, W. (2000), 'Untersuchungen zur Prozessführung und zum Fertigungssystem bei der Hochdruckblechumformung', PhD thesis, Universität Dortmund.

Kleiner, M. & Homberg, W. (2000), Perspektiven der wirkmedienbasierten Umformung von Stahlblechen, in NN, ed., 'Tagungsband zum Kolloquium Stahlblechumformung 2000 am 08./09.05.2000 in Bad Nauheim'.

Kleiner, M.; Homberg, W. & Beerwald, C. (2000), Aspekte der wirkmedienbasierten Blechumformung, in NN, ed., 'Tagungsband zur 7. Sächsische Fachtagung Umformtechnik SFU 2000, vom 24./25.10.2000 in Chemnitz', Verlag Wissenschaftliche Scripte, Chemnitz, pp. 439-444.

Kleiner, M.; Homberg, W.; Neubert, J.; Birkert, A.; Friebe, E. & Langhammer, T. (2000), Anwendung der Hydroblechumformung zur Herstellung eines PKW-Kraftstofftanks, in NN, ed., 'Tagungsband zur 7. Sächsische Fachtagung Umformtechnik SFU 2000, vom 24.-25.10.2000 in Chemnitz', Verlag Wissenschaftliche Scripte, Chemnitz, pp. 173-186.

Beerwald, C.; Brosius, A.; Homberg, W.; Kleiner, M. & Wellendorf, A. (1999), New Aspects of Electromagnetic Forming, in NN, ed., 'Proceeding of the 6th ICTP', Springer-Verlag, Berlin, pp. 2471-2476.

Finckenstein, E. v.; Gartzke, A.; Homberg, W.; Kleiner, M.; Kollek, R.; Szücs, É. & Weidner, T. (1999), 'Entwicklung von Verfahren und Werkzeugsystemen zur Hydroumformung höherfester Stahlbleche'(274), Technical report, Studiengesellschaft Stahlanwendung e.V., Düsseldorf.

Homberg, W.; Beerwald, C. & M., K. (1999), Innovative Umformverfahren im Automobilbau durch Wirkmedien und Wirkenergien, in NN, ed., 'Tagungsband zu 'Karosserie 2000 neue Fertigungsverfahren' am9.-10.12.1999 in Essen, Haus der Technik'.

Kleiner, M.; Finckenstein, E. v.; Homberg, W. & Beerwald, C. (1999), Umformen mit Wirkmedien und Wirkenergie, in NN, ed., 'Umformtechnik 2000+ Festschrift zu Ehren von Prof. K. Lange', Meisenbach-Verlag, Bamberg.

Kleiner, M.; Hellinger, V.; Homberg, W. & Klimmek, C. (1999), Möglichkeiten der wirkmedienbasierten Blechumformung, in NN, ed., 'Tagungsband zur Internationalen Konferenz 'Hydroumformung' am 12. und 13.10.1999 in Fellbach', pp. 291-303.

Kleiner, M.; Homberg, W. & Brosius, A. (1999), Processes and Control of Sheet Metal Hydroforming, in M. Geiger, ed., 'Advanced Technology of Plasticity 1999: Proceedings of the 6th International Conference on Technology of Plasticity Nuremberg, 19.-24. September 1999', Springer, Berlin, pp. 1243-1252.

Kleiner, M.; Homberg, W.; Brosius, A. & Wellendorf, A. (1999), Pneumomechanisches Tiefziehen höherfester Stahlbleche zur Verbesserung des Formänderungszustandes bei Karosserieteilen, in V. Thoms, ed., 'Vom Umformverfahren zum Umformprozß. Tagungsband zur 6. Sächsischen Fachtagung Umformtechnik SFU 1999', pp. 82-91.

Kleiner, M.; Wellendorf, A.; Homberg, W.; Brosius, A. & T., W. (1999), Innovation durch Hydroformen von Stahlbauteilen, in NN, ed., 'Tagungsband zum DVM-Tag vom 05.-07.05.1999 in Berlin', DVM, Berlin, pp. 159-174.

Neubert, J.; Kleiner, M.; Homberg, W. & Langhammer, T. (1999), Perspektiven des Hydroformens zur Herstellung eines PKW-Treibstofftankes, in NN, ed., 'Tagungsband zum DVM-Tag vom 05.-07.05.1999 in Berlin', DVM, Berlin, pp. 217-226.

Finckenstein, E. v.; Gartzke, A.; Homberg, W. & Kleiner, M. (1998), Chancen und Perspektiven der Hydroumformung im Bereich blechförmiger Halbzeuge, in NN, ed., 'Tagungsband zum Aachener Stahlkolloquium 98 am 27.03.1998 in Aachen', pp. 6.3-1-6.3-14.

Finckenstein, E. v.; Kleiner, M.; Homberg, W. & C., S. (1998), Uma nova abordagem para a flexibilizacao da producao de pecas a partir de chapas, in NN, ed., 'Maquinas e Metais MM Janeiro 1998', Aranda Editora Tecnica Ltda, Sao Paulo, pp. 28-35.

Finckenstein, E. v.; Kleiner, M.; Szücs, É.. & Homberg, W. (1998), In-process punching with pressure fluids in sheet metal forming, in NN, ed., 'Proceedings of the 47th CIRP General Assembly', pp. 207-212.

Kleiner, M.; Schwefel, H.-P.; Heller, B.; Homberg, W. & Naujoks, B. (1998), Optimized Control of the CNC-Spinning of Hollow Bodies Based on Nonlinear Dynamics, in NN, ed., 'Tagungsband zum COST P4 - Workshop am 05/06.11.1998 in Dortmund'.

Finckenstein, E. v.; Gartzke, A.; Homberg, W. & Kleiner, M. (1997), Konstruktive und fertigungstechnologische Aspekte einer Verfahrensentwicklung im Bereich der hydromechanischen Blechumformung - Technologie, in NN, ed., 'Tangungsband zum Kolloquium 'Innenhochdruckumformung - innovative Fertigungstechnik für den Superleichtbau' im Haus der Technik, Essen am 29./30.01.1997'.

Finckenstein, E. v.; Homberg, W.; Kleiner, F.; Smatloch, C. & Szücs, É... (1996), Hochdruckblechumformung (HBU) - Ein Verfahren zur hydromechanischen Blechumformung, in NN, ed., 'Tagungsband zum Kolloquium 'Innenhochdruckumformen - eine Alternative in der Fertigungstechnik' am 05./06.03.1996 in Fellbach', pp. 1-14.

Finckenstein, E. v.; Gorbauch, S.; Herold, G. & Homberg, W. (1995), 'Möglichkeiten zur Qualitätsverbesserung an Drückwalzteilen', Blech Rohre Profile 42, 466-472.

Kleiner, M.; Homberg, W.; Smatloch, C. & Gartzke, A. (1995), 'Verfahren zur Herstellung von Blechformteilen durch die Beaufschlagung von Blechhalbzeugen mit einem Druckmedium'(OS DE4417460), München.

Herold, G.; Finckenstein, E. v.; Kleiner, M.; Dierig, H. & Homberg, W. (1994), 'Erhöhung der Werkstückqualität beim Formdrücken und Abstreckdräcken von Aluminiumwerkstoffen'(56), Technical report, Europäische Forschungsgesellschaft für Blechverarbeitung e.V., Hannover.

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