Overall project: Method development for mechanical joinability in versatile process chains
Term: 1. July 2019 - 30. June 2027
Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
URL: https://trr285.uni-paderborn.de/
The aim of this project is to conduct fundamental scientific research into joining without auxiliary element using metallic pin structures produced by forming technology, which are pressed into the joining partner or caulked after insertion into a perforated joining partner, and the joint properties that can be achieved with this. This includes the development of a fundamental understanding of the acting mechanisms with a focus on feasibility in phase 1, the optimisation of the pin structure with regard to geometry and arrangement as well as the joining process for the targeted adjustment of joining properties in phase 2 and the transferability of the technology to an extended range of applications in phase 3. The aim in phase 1 is therefore to develop a fundamental understanding of the extrusion of defined metallic pin geometries from the sheet plane using local material accumulation in order to be able to determine local changes in the material properties, such as strength. Simultaneously, different process control strategies for joining metal and FRP as well as different metals will be fundamentally researched and process windows will be derived.In the case of FRP, various process routes will be investigated with a focus on fibre-friendly injection of the pin structures or hole forming for caulking of the pin structures without delamination of the FRP. Ultrasound, vibration, infrared radiation or combinations of these methods are used to melt the matrix with the goal of identifying suitable process routes and generating an understanding of the mechanisms at work. Based on the findings of the pin manufacturing and the results regarding the joining processes, a fundamental understanding of the process will be developed, which will allow the further development of the pin geometry and the definition of suitable simple, regular pin arrangements and dimensions in the next step. In order to meet the different requirements of the pin manufacturing process and the joining method, the adaptability of the tool and joining technology is essential. Accordingly, the adaptation on the tool side and the specific process control during pin production will be investigated in order to demonstrate the possible variations. In addition, the adaptability of the joining operation will be achieved by adapting the process control, especially in the case of metal-FRP joints, in order to react to different conditions, such as the fibre layer and layer structure of the FRP. Finally, the direction-dependent joint properties and the application behaviour of the multi-material joints joined with the developed pin geometries will be characterised and evaluated depending on the pin dimensioning and arrangement in order to identify the decisive influencing factors on the joint properties.
Research projects
Prediction of tool fatigue in cold forging processes
(Third Party Funds Group – Sub project)
Term: 1. April 2025 - 30. September 2027
Funding source: Bayerische Forschungsstiftung
The goal of the project partners is to develop concepts forextending tool life of cold forging tools. Using numerical simulation models,it is possible to analyse tool loads in detail. To achieve this objective,geometric and mechanical component properties are analysed and used as adatabase for tool stress. Integrated into a simulation model, this data is usedto determine the tool life. In order to validate the accuracy of thepredictions, the methods are transferred to industrial processes.
The calculation and subsequent extension of tool lifecontribute to more economical production of cold forged components and promotethe spread of eco-friendly manufacturing technologies in Bavaria as a businesslocation.
Forming tailored hybrid semi-finished products - Tailored Additive Blanks
(Third Party Funds Group – Sub project)
Term: 1. October 2024 - 30. September 2027
Funding source: Bayerische Forschungsstiftung
The aim of TP 3 is therefore to develop a holistic understanding of the material-efficient production and forming of customised, hybrid semi-finished sheet metal products. The integration of the hybrid manufacturing approach into generative design enables a continuous, economical product development process, which also allows the reduced CO2 footprint of the technology to be quantified by recording the process data in advance.
Basic research and determination of process limitations in bulk forming processes of microgears from sheet metal - phase 2
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Theobjective of the second project phase is the fundamental analysis of anextended process chain for the manufacturing of microgears with a module of0.1 mm. This includes the investigation of functional interactions ofsingle process steps as well as the forming-related properties on theapplication behavior of the microgears. Based on the findings of the firstproject phase with regard to the three-stage process chain, the process chainwill be extended in the second phase by an additional VFP stage and by theextrusion of a cup as a gear holder. The aim of the process extension by amulti-stage VFP is to identify effects and interactions between the influencingvariables punch diameter and penetration depth in order to analyze the effectson the material flow and the homogeneity of the deformation on the basis of theeffect mechanism determined in the first phase. The process understandinggained will subsequently be used to adjust required pin properties throughtargeted material flow control for subsequent forming of the gear holder, aswell as to reduce the process forces identified as critical in the first phase.Another sub-objective is to develop a substantial process understanding formulti-stage microforming process chains through the integration of cup formingas well as through the final separation from the sheet metal strip. For thispurpose, a suitable forming strategy for the integration of a cup extrusion isdeveloped and interactions between the forming stages are identified, resultingin a fundamental process knowledge. In addition, the forming possibilities ofthe process chain and the component spectrum will be significantly expanded. Afurther sub-objective is to evaluate the application behavior of the impactextruded microgears on the basis of the analysis of runnability in a practical laboratorytest on a gear test rig. Finally, functional relationships are determined andthe findings from both phases are evaluated to derive a process window anddevelop a detailed understanding of the process.
Analysis of the elastic-plastic material behavior of higher-strength steel materials under cyclic and swelling loading depending on the relaxation behavior
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Investigation of internal stress-relevant mechanisms along the process chain of the production of cup extruded parts
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Tailor Alloyed Blanks - Manufacturing of high-strength process-adapted semi-finished parts by a local laser-based adaption of the alloying system
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Investigations on the process combination of DED-LB/M and forming
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Data-based identification and prediction of the die surface condition and interactions in sheet bulk metal forming processes from coil
(Third Party Funds Group – Sub project)
Term: 1. November 2023 - 31. October 2026
Funding source: DFG / Schwerpunktprogramm (SPP)
Optical strain rate control in material characterization
(Third Party Funds Group – Overall project)
Term: 1. February 2023 - 31. July 2025
Funding source: Bayerische Forschungsstiftung
URL: https://forschungsstiftung.de/Projekte/Details/Optische-Dehnratenregelung-in-der-Werkstoffcharakterisierung.html
A fundamental knowledge of material behavior is necessary for the targeted forming of metallic materials. Characterization tests, such as the tensile test, are used to determine specific material parameters such as yield stress, tensile strength, uniform elongation and elongation at break. In addition, the elastic-plastic material behavior can be analyzed. Through the appropriate choice of a material model, this material behavior is mapped in a simulation. Formingsimulations represent the manufacturing process and are used for the design of tools and sheets and contribute to the safe and resource-saving design of parts.
Most metallic materials exhibit strain rate sensitivity. This means that the material behavior changes depending on the forming speed. In particular, quasi-static characterization tests carried out at low strain rates, which hardly ever occur in real forming processes, lead to deviations from the real material behavior. Thus, the consideration of the actual strain rate sensitivity leads to an improved material modeling and thus simulative representation of the material behavior.
The aim of the research project is therefore to develop, in cooperation with the project partners, a robust method for carrying out optically strain-rate-controlled tests and to analyze the influence on the prediction quality of simulations. This will reduce the difference between the nominally selected strain rate and the actual strain rate. By this method, more accurate material parameters are measured, which in turn enables an improved component and process design.
Notch Rolling and Cyclic Bending - Basic Investigations for the Production of Bulk Materials with a Low Aspect Ratio out of Strip Material
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Mechanical joining without auxiliary elements
(Third Party Funds Group – Sub project)
Term: 1. July 2019 - 30. June 2027
Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
URL: https://trr285.uni-paderborn.de/
Center for Nanoanalysis and Electron Microscopy
(FAU Funds)
The support of the core facility CENEM by the German Science Foundation (DFG) and the Cluster of Excellence EXC 315 “Engineering of Advanced Materials” is gratefully acknowledged.
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2020
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