Papers by Keyword: Impact Extrusion

Abstract: Transport industry faces challenges steadily due to rising fuel costs and stricter regulations for the emission of air pollutants. Technological developments that reduce fuel consumption are necessary for sustainable and resource-efficient transport. Innovative production technologies utilising multi-material designs come to the fore in an attempt to fabricate lightweight products with extended functionality. Departing from this motivation, novel process chain concepts for the manufacturing of bi-material forged products are being researched at the Leibniz Universität Hannover in the context of the Collaborative Research Centre (CRC) 1153. The developed technology is referred as Tailored Forming and deals with the deformation and subsequent processing of joined hybrid workpieces to produce application-oriented products. Deformation processes are carried out at elevated temperatures for thermomechanical treatment of the joining zone properties. Researchers make use of numerical simulation in each step in the process chains. This paper explains the challenges associated with induction heating and impact extrusion of bi-material forging billets and presents our solution approaches with the aid of numerical modelling. Experimental validation results and analysis of deformed workpieces are also shown.

Abstract: In the past months due to decreasing fuel prices the brisance of light weight design got lost, however climate change is still continuing and there is an increasing demand for aluminum parts for mobile applications. There is a strong rivalry between well-known materials such as aluminum, steel and plastic, however technical progress features new materials such as carbon fiber laminates (CFK). New competitors in North America and China are increasing the cost pressure, which requires further process optimizations. In this work different fabrication methods for impact extruded parts are analyzed and economical and technological aspects are compared. A comparison between traditional and state-of-the-art production routes is done. Based on an input-output analysis the alternatives are compared by economic and ecologic aspects, allowing a substantiated examination. Through the comprehensive analysis, options for technological optimizations are revealed to attenuate disadvantages of alternatives with economic advantages, ensuring technological leadership.

Abstract: The Collaborative Research Centre SFB/TR 39 PT-PIESA is developing mass production technologies and process chains for the fabrication of aluminium piezo composites, which can be used as raw material for "smart sheet metal" [1]. Microstructuring by forming is a challenging task concerning material flow, tool and process design [2]. In this study, a hybrid forming process combined of micro impact extrusion and shear displacement is presented and discussed. The formed microstructure, depicted in figure 1, consists of ten parallel primary cavities with cross sections of 0.3×0.3 mm² and four larger secondary cavities which are surrounding the primary cavities. High demands are made concerning precision and reproducibility of the cavities' geometry according to the function of the cavities, which is to serve as collets for sensitive piezo rods. The microstructure has to be formed with one stroke of the stamp. Micro backward impact extrusion is chosen for structuring the primary cavities since it allows accurate forming without aligning die plate and stamp due to a flat die plate. Shear displacement forming, which is the selected process for the secondary cavities, requires a structured and aligned die plate but the forming forces are significantly lower than forming the same geometry with an extrusion process which in turn increases the accuracy. The investigations are focused on the characterization of samples formed with the hybrid process in comparison to structures which are formed solely by impact extrusion. Geometric parameters, material flow and process parameters were evaluated to assess the hybrid process. First experiments show promising results, whereas higher degrees of deformation could be reached at lower forming forces. Exemplary, sections for both processes are depicted in figure 2.

Abstract: Aluminium alloy cans are generally used as containers for electrochemical energy systems like capacitors and advanced batteries. Packing efficiency of batteries depends upon their configuration. Containers in prismatic, cylindrical and elliptic-cylindrical shapes are generally used for battery applications. Elliptic-cylindrical shape has the advantage of better heat dissipation and good packing efficiency in battery assembly. Safety device to be provided in the cans requires material in the minimum half hard (H14) condition. In the present work, ellipsoidal cans of Al-Mn alloy were successfully realised by impact extrusion process. Mechanical properties of the cans were analysed through to ensure the adequacy of the process and it has been demonstrated that impact extrusion is a viable process for making cans for batteries with required mechanical properties, for the can in total and for the safety device in particular.