Investigation of internal stress-relevant mechanisms along the process chain of the production of cup extruded parts

Third party funded individual grant


Start date : 01.02.2024

End date : 31.01.2026


Project details

Short description

Increasing complexity due to functional integration of components in moving systems is still overshadowed by requirements for lightweight construction. From a production technology perspective, major challenges also lie in high energy and material costs. For large series parts, forming manufacturing processes are therefore preferred when the geometry is suitable. For components with high complexity, small wall thicknesses and high geometric requirements, machining production is often unavoidable, as it enables production with final dimensions without the challenge of high process forces. Since exclusively forming production is usually not possible for complex components and exclusively machining does not make sense for efficiency reasons, combined process chains are used in industrial environments in which different manufacturing processes are used.

During their production, the preliminary product is first produced by cup extrusion, from which the target geometry is then created by turning and milling. Due to the material flow and the inhomogeneous stress states, residual stresses remain in the pressed part after forming. These are distributed over the component volume with different signs and amounts and are in balance with one another. If component areas subject to internal stress are removed, for example through subsequent machining steps, a new state of equilibrium is formed in the remaining material. As a result, distortion can occur, particularly on flanges or with small wall thicknesses, which results in rejects due to non-compliance with the required geometric specifications. Machining post-processing steps lead to an extension of the process chain and reduce the material efficiency of the manufacturing process. Reducing the machining volume through near-net-shape processes, i.e. forming close to the final shape, therefore makes sense from both ecological and economic points of view.

The results developed as part of the 2013 priority program prove that the residual stress state of the component resulting from extrusion can be fundamentally influenced by the process control. Against this background, the overarching goal of the present research project is to identify general residual stress-relevant processes in the production of cup extruded parts and to use them in industry-related process chains to improve the component's residual stress state.

Scientific Abstract

Increasing complexity due to functional integration of components in moving systems is still overshadowed by requirements for lightweight construction. From a production technology perspective, major challenges also lie in high energy and material costs. For large series parts, forming manufacturing processes are therefore preferred when the geometry is suitable. For components with high complexity, small wall thicknesses and high geometric requirements, machining production is often unavoidable, as it enables production with final dimensions without the challenge of high process forces. Since exclusively forming production is usually not possible for complex components and exclusively machining does not make sense for efficiency reasons, combined process chains are used in industrial environments in which different manufacturing processes are used.

During their production, the preliminary product is first produced by cup extrusion, from which the target geometry is then created by turning and milling. Due to the material flow and the inhomogeneous stress states, residual stresses remain in the pressed part after forming. These are distributed over the component volume with different signs and amounts and are in balance with one another. If component areas subject to internal stress are removed, for example through subsequent machining steps, a new state of equilibrium is formed in the remaining material. As a result, distortion can occur, particularly on flanges or with small wall thicknesses, which results in rejects due to non-compliance with the required geometric specifications. Machining post-processing steps lead to an extension of the process chain and reduce the material efficiency of the manufacturing process. Reducing the machining volume through near-net-shape processes, i.e. forming close to the final shape, therefore makes sense from both ecological and economic points of view.

The results developed as part of the 2013 priority program prove that the residual stress state of the component resulting from extrusion can be fundamentally influenced by the process control. Against this background, the overarching goal of the present research project is to identify general residual stress-relevant processes in the production of cup extruded parts and to use them in industry-related process chains to improve the component's residual stress state.

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Funding Source