Mould and process for the extrusion of metallic materials
The invention describes moulding tools, which enable the production of extruded metallic parts with predominantly isotropic properties. In addition, a process is proposed, which favours the production of largely isotropic extruded parts with conventional extrusion presses.
Extrusion is a compression forming process that can be used to produce tubes, wires, rods and/or (irregularly) shaped profiles. The workpiece is inserted into a feed channel and pressed through a mould with a punch. The material is plastically deformed and an extruded part in the desired shape is created. The extruded parts produced in this way (made of, for example, magnesium materials) often show strongly anisotropic (direction-dependent) mechanical properties, such as a tensile-compressive and/or bending anisotropy. Hence, their application as structural components is severely limited. In order to achieve an improved isotropic (direction-independent) mechanical behaviour of the extruded parts, alloy components/elements can be added to the extruded material. However, the extrudability is degraded due to strongly increasing pressing forces. Multiple extrusion of the same profile with an angled feed channel also allows the creation of workpieces/parts with an increased isotropy. However, with the currently available presses this is not easily feasible.
Scientists from the Leuphana University of Lüneburg and Helmholtz-Center Geesthacht have developed moulding tools, which overcome the aforementioned limitations and enable the production of metallic extruded parts with isotropic properties. According to the present invention, the forming process of the metallic material takes place within the extrusion die of the moulding tools. In contrast to conventional extrusion presses, the entire material flow in the inner and outer laminar layers is moved vertically and transversely to the extrusion direction. According to the invention, a mould with a die with at least one die channel wall is used, which is curved into the die channel. The sewer cross-sectional surfaces defined by the die channel walls remain essentially constant in size. Fig. 1 and Fig. 2 show examples of possible embodiments of extrusion matrices for the production of isotropic, metallic workpieces/parts, according to the present invention.
- Production of extruded metallic parts with isotropic mechanical properties
- Flexible adaptation to the manufacturing of metallic sheet plate, L-type and hollow profiles available
- Adaptation of the process to conventional presses possible
- Extrusion moulding dies can be easily fabricated by e.g. 3D metal printing
- Production of parts/components made of magnesium, aluminium as well as magnesium and aluminium alloys with isotropic properties
- Exploitation of the technology in the metal and automotive industry
The moulding tools have been successfully developed and tested. The production process of metallic parts with the moulding tools have been approved.
Dr. Mirza Mackovic
Patent Manager Technology
Phone: +49 551 30724 153