P 546 - Development of a spur gear differential with internal gearing in sheet metal construction

P 547 - Manufacture of a flangeless fuel tank with complex geometry The aim of the research project was the production of a package-optimised fuel tank made of steel. This was based on the results of research project P 410 "Production of a fuel tank with complex geometry made of steel using hydroforming". The package optimisation aimed for in this research project was achieved by designing the tank as a flangeless (laser) welded tank using forming and joining technology. A major problem in the production of a flangeless tank made of stainless steel is the uneven, moulding-related spring-up and spring-back, particularly in the frame areas. This makes the positioning and orientation of the tank halves required for joining very difficult. In this project, the residual stress state in the formed sheet metal half-shells was therefore first analysed using the drill hole method and the disassembly method. From this, design and tooling measures (increasing the rigidity through appropriate embossing) were derived in order to minimise the forming-related springback. In the field of joining technology, a special welding process (based on the use of a special robot head) and a corresponding clamping device were developed and realised, which was able to achieve precise trimming and joining. However, it turned out that the shape deviations caused by springback could not be fully compensated for by increasing the rigidity and by the clamping technology used. For this reason, the tank half-shells were ultimately successfully joined using piece-by-piece laser welding and manual TIG welding. Finally, the manufactured tanks were subjected to component tests in accordance with the VW factory standard. The knowledge gained can initially make the manufacture of modern tank systems with complex geometries from steel materials considerably easier. In addition, the findings can also be transferred to other potential areas of application, for example in rail and aircraft construction, apparatus engineering, sanitary engineering or the household appliance industry. Authors: M. Kleiner, W. Homberg, A. Wellendorf, M. Gösling, F. Trösken, F. Behr, T. Langhammer Publication: 2006

P 544 - Prospective study to determine requirement profiles and application potentials for roll profiles from tailored strips Due to their wide range of shapes and economic manufacturability, rolled steel profiles have established themselves as construction elements in a wide variety of industries. Currently, only strip steel of uniform thickness is processed for this purpose. Expanding the process by processing tailored strips - strips of different thicknesses welded together - could make rolled profiles even more attractive for existing and new applications. Ideally, profile cross-sections could be produced that are individually adapted to the load of the components manufactured from them. The aim of this study was to find out what requirements such profiles should fulfil and what possible applications they have. The investigations focussed on the technological and economic aspects of various processes for manufacturing profiles. Extrusion moulding and roll forming were examined in detail. In general, technical constraints limit the use of steel compared to aluminium for the production of extruded profiles with thin-walled segments. However, it is clear that rolled profiles made from tailored strips could compensate for the design deficits of rolled profiles made from conventional steel strip compared to extruded aluminium profiles. This opens up new areas of application. Roll-formed profiles are already ideally suited for effective and economical lightweight fabric construction when high-strength steel grades are used. In addition, roll-formed profiles, whose thickness can be varied across the cross-section, open up innovative design and application possibilities for steel in lightweight moulded construction. Data research, user surveys and product analyses have shown that load-adapted, lightweight rolled profiles made from tailored strips have very good potential applications, particularly in road and rail vehicle construction, and have met with great interest from manufacturers. STUDIENGESELLSCHAFT STAHLANWENDUNG e.V. Publication: 2002 Authors: Dipl.-Ing. A. Istrate, Prof. Dr.-Ing. P. Groche

P 549 - Material flow control through optimised design of a burr geometry that varies in circulation Components with good mechanical properties can be produced relatively cost-effectively in large quantities using the forging manufacturing process. Nevertheless, this manufacturing process is also subject to the economic pressure of a large number of competing processes. This is because, apart from the quality of the component, costs are the decisive factor for the customer when placing production orders. It is therefore important to pursue the goal of producing high-quality components even more cost-effectively. In order to improve the economic boundary conditions, the reduction of forming force and input mass is particularly suitable in the forging process, as these factors are ultimately reflected to a large extent in the overall costs of the components. Although the precision forging process makes it possible to produce forged parts without excess material, this is difficult to realise for many components. Due to the combination of technological and economic factors, the majority of forged components are produced with excess material. This excess material must flow between the moulding dies via the so-called flash path. The design of the shape of this flash path has a significant influence on the tool stress, the flow behaviour within the engraving and the required excess material. As the flow behaviour of complex forged parts is not constant, it is advisable to design the flash path variably according to the flow conditions. At present, the design is mainly based on individual empirical values. Systematic design methods and solutions to support the design process within CAD systems do not yet exist. As part of this project, various methods for designing variable burr geometries were developed. In order to compensate for the higher design effort of variable burr geometries modelling concepts were also developed in various CAD systems to simplify and partially automate the design of burr paths. To verify the positive effects of variable flash paths on the insertion mass or forming force, variable flash paths for forging tools were designed iteratively, checked with the aid of FEM simulation (finite element method) and the analysed improvements verified by means of test forging operations. RESEARCH ASSOCIATION FOR STAHLANWENDUNG e.V. Publication: 2004 Authors: Prof. Dr.-Ing. E. Doege, Prof. Dr.-Ing. B.-A. Behrens, Dipl.-Ing. G. Klawitter

P 540 - Flanging thin-walled sheet steel components The aim of the research project was to develop batteries with increasingly higher amounts of storable energy while reducing the weight and volume of the battery can and optimising this flanging process, which is important for battery production. The external sizes to be used are fixed by the available installation space in the devices, so that an increase in performance through an increase in volume can only be achieved by reducing the wall thickness of the battery cans. The desired reduction in sheet thickness leads to an increase in battery capacity of up to 12% as a result of the increase in volume. In the research project, the flanging process was carried out on different cup materials with wall thicknesses of 0.18 mm, 0.15 mm and 0.13 mm. The process was systematically analysed in order to identify the influencing variables and to make modifications, e.g. to the tool geometry, in order to flange thinner sheet materials more reliably. The flanging process was simulated using the FEM programme package ABAQUS. In the simulation, individual parameters, such as the tool geometry, were specifically varied in order to be able to estimate their influence on the flanging process. The results from the experimental and FEM analyses have shown that batteries with a cup wall thickness of 0.13 mm can be realised in laboratory operation. The simulation calculations with varied mould geometries have also shown that the geometries of the moulds used already represent an optimum in the technically relevant range. According to the current state of knowledge, a stable production process cannot be guaranteed with the flanging process used when using a newly developed flat seal and a cup wall thickness of 0.13 mm. Authors: E. Doege, O. Pösse , M. Milch Publication: 2004