Jahresbericht 2017

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Metal Forming and Casting
cutting processes are characterized by a high plastic
deformation and thus induce residual stresses in the pro-
duced part. Up to now, residual stresses induced by metal
forming operations have not been subject to focused
investigations in the sense of a suitable use of their
tensile and compressive components to ensure targeted
part-specific residual stress profiles, especially when a
cost and time-intensive heat treatment should be avoided.
By a variation of the process parameters the influence on
the formation of the residual stress state is identified and
used for a targeted utilization. To that end, experimental
as well as numerical experiments are performed. On the
basis of the residual stress states generated and their
time-stability in the produced parts, the component
strength is derived by a residual stress model. Core of
the investigation is a predictive residual stress model for
closed cutting lines to determine process parameters for
part specific load requirements. This allows an increase in
the quality as well as the lifetime of parts manufactured by
NNSBPs.
Projects
■■Reduction of Sliver During Trimming of Aluminum
Sheets (AiF)
■■Wear Curves of Cutting Punches through Targeted
Fatigue (AiF)
■■Influence of Edge Manufacturing on the Fatigue Behav-
ior of Different Steel Grades Under Cyclic Load (AVIF)
■■Influence of Process-related Altering Die Clearance on
Tool Wear (AiF)
■■Improvement of Tool Life Through Adjustment of the Tip
Clearance of Punching Dies to the Breakthrough-force
(AiF)
■■HyBMS – Punching of Hybrid Components with a
Minimal Degree of Damage (AiF)
■■Lubricant-free Forming by Affecting Thermoelectric
Currents (DFG)
■■Manufacturing of Electromagnetic Components from
Non-grain Oriented Electrical Steels (DFG)
■■Geometry and Feasibility Prediction of Sheet Metal
Parts with Embossings Made of High-strength and
Ultra-high-strength Steels (AiF)
■■Sources and Prediction of Slug Pulling (AiF)
■■Characterization and Utilization of Process-induced
Residual Stresses for the Manufacturing of Functional
Surfaces by Near-Net-Shape-Blanking Processes (DFG)
■■Thermomechanical Interaction in the Shear Cutting
Affected Zone (DFG)
■■Formability Improvement of Shear Cut Surfaces of
Iron-manganese
■■Sheet Metal by Optimized Cutting Parameters (FOSTA
Stahlanwendung e.V.)
■■Focused Use of Residual Stress in Electrical Steel as
Means of Improving the Energy Efficiency (DFG)
Metal Forming
The research group ‘Metal forming’ focuses on:
■■Qualification of materials
■■Qualification of processes, tools and machinery
The qualification of materials is a key topic of this
research group. In this area, especially the determination
of quasi-static properties as well as the investigation of
the strain rate and temperature sensitivity of the materials
are focused on. The knowledge gained is the basis for
the understanding of the material behavior in forming
processes and high quality finite element simulations.
The latter helps to gain deeper process insights and
understanding of the forming processes. They are part of
nearly every project in the metal forming group and are the
starting point for the qualification of processes, tools and
machinery. As an example for our work, our part within the
research initiative ‘Lightweight Forging’ -
leichtbau.de) is presented in more detail.
Research Project Lightweight Forging
Motivation
The continuous pressure in the automotive industry to
reduce a car’s weight forces the engineers to look for new
areas to which apply lightweight design. Therefore, power
train, chassis and with them the gear box, are being
focused on. Today, gear wheels within the gear box are
solid components.
Approach
We investigate along the gear wheels’ whole process
chain. Beginning with the design phase, heading over
to production phase and ending with the final product,
we look for possibilities to apply lightweight design. This
leads to the proposal of gear wheels in differential design
(figure 1 and 2). Numerical investigations on the combi-
nations of different designs, materials and manufacturing
techniques detect and allow us to understand interde-
pendencies. Subsequently to the numerical investigations,
prototypes are manufactured for real world testing.