Load optimized sheet metal components made of high-strength aluminium

RAmP- Subproject

The “KMU-collaborative project” RAmP is affiliated to the LOEWE 2 focal point ALLEGRO and serves to implement and test the technological leaps made in ALLEGRO in an industry-oriented environment. This is implemented by means of a new qualification model for young scientists, in which half of the project staff are employed by the Institute for Production Technology and Forming Machines (PtU) at the TU Darmstadt and the other half by one of the project partners. The industrial partner for this sub-project is Werner Schmid GmbH in Fulda, whose core competencies include the design and construction of multi-stage progressive and transfer tools as well as the series production of complicated stamped and drawn parts.

Motivation

Due to increasing legal requirements, the topic of lightweight construction continues to be of great importance in the mobility industry in order to reduce fuel and energy consumption as well as CO2-emissions. Especially for commercial vehicles, loading capacities can be increased. Strongly growing sectors such as the e-bike and automation industry also benefit from lightweight construction measures. In addition to increases in operational efficiency, the focus here is on the benefits of use: these result from higher dynamics (especially automation) and handling advantages (especially e-bike).

The high-strength aluminium alloy EN AW-7075 offers one possibility for lightweight construction, but it only permits low degrees of forming during cold forming and thus only simple component geometries. Temperature-assisted forming processes or process routes are used for the manufacture of more complex components, which are often cost-intensive and have limited reproducibility. Furthermore, process-integrated heat treatment routes for high-strength aluminium components with graded strength properties are investigated. These topics are already covered in the LOEWE 2 focal point ALLEGRO (High-performance components made of aluminium alloys through resource-optimized process technologies) and the completed LOEWE 3 project “WarmAp” (Hot forming of aluminium sheets for high-performance components of future mobility concepts, HA project no.: 548/19-30).

Objective

The RAmP project (Robust forming of high-strength aluminium alloys through multi-dimensional process windows) aims at extending the process understanding for temperature-supported forming of high-strength aluminium alloys. The aim is to further develop the previous investigations on laboratory scale in order to obtain stable process windows for later series applications. For this purpose, the description and control of multi-dimensional process windows is essential, in which both single-stage and multi-stage forming processes are considered for the respective optimized temperature control. The tribology and the quality of numerical simulations of temperature-supported forming processes play an important role for the process capability.

[1] Process window of a deep drawing process; left: conventional two-dimensional [Source: K. Lange – Blechbearbeitung], right: two-dimensional considering additional influencing variables, but without their interaction (schematic)

In the sub-project with the Werner Schmid GmbH, the focus is on multi-stage forming processes for the production of components with adapted wall thicknesses, whereby optimized force application and thus also material utilization can be achieved. The test tool developed in WarmAp serves this purpose.

[2] Multi-stage forming tool with temperature-controlled active parts and the planned demonstrator geometry

Approach

In order to achieve the planned goals, a process-specific increase in the robustness of the temperature-supported process routes is required first. This is done by numerical simulations and experimental sensitivity analyses of individual process parameters. In parallel, a friction and wear test method for elevated temperatures is being developed with the aim of increasing the tribological robustness of temperature-supported forming processes. With the help of these data and findings, the design of multi-dimensional process windows for the functional verification of process chains under near-series laboratory conditions will be made possible. In addition, a systematic analysis of tribological systems and cluster formation with functional verification and application recommendations is carried out. The topic is concluded with the formulation of guidelines for the design of temperature-supported forming processes and their application to potential components.

[3] Overview of the work packages and their interfaces

Institutions and companies involved

In addition to the PtU, the Institute for Materials Science and the Fraunhofer Institute for Structural Durability and System Reliability in Darmstadt are involved in the overall ALLEGRO project. Three institutes of the University of Kassel are also involved. These include the Institute for Materials Technology / Metallic Materials, the Institute for Forming Technology and the Institute for Separating and Joining Manufacturing Processes.

In RAmP, the tribology service provider Filzek TRIBOtech GmbH acts as a further project partner. In addition, the Hörmann Automotive Gustavsburg GmbH as a specialist for large structural components and the lubricant manufacturer MKU-Chemie GmbH as associated partners are involved.

Acknowledgment

This project (HA project no. 822/19-142) is financed with funds of LOEWE – Landes-Offensive zur Entwicklung Wissenschaftlich-ökonomischer Exzellenz, Förderlinie 3: KMU-Verbundvorhaben (State Offensive for the Development of Scientific and Economic Excellence).

Furthermore, the Institute of Production Engineering and Forming Machines would like to thank all institutes and industrial partners involved in ALLEGRO and RAmP for their support in the implementation of this project, but above all the Werner Schmid GmbH, which makes this dual-oriented research unit possible.