P 373 - Prefabricated sheet steel panels for shipbuilding and other applications

P 374: Investigation of the relationship between car weight and fuel consumption - measurements on 11 vehicles on the dynamic chassis dynamometer The vehicle weight influences - among other factors - the fuel consumption of motor vehicles. Therefore, in order to reduce fuel consumption and thus to save energy and conserve resources, weight reduction is a particular aim in the further development of road vehicles. In order to be able to evaluate the effect of a wide range of measures, it is desirable to have precise knowledge of the direct correlation between weight reduction and fuel savings. This applies in particular to the present investigation of current vehicles by means of lightweight construction measures, in which a weight reduction of 100 or 200 kg per vehicle is achieved in stages, without a fundamentally new design being considered. In this case, the Institute of Automotive Engineering at the Rheinisch-Westfälische Technische Hochschule Aachen has demonstrated in a comprehensive study that the fuel savings for a number of the vehicles examined and the driving cycles completed are between 0.05 and 0.15 litres per 100 km and 100 kg weight reduction. Measured values above this can often be explained by the driving cycles that increase fuel consumption. In no case have the key figures widely used in public debate to describe the influence of weight reduction on consumption of approx. 0.5 to 0.7 litres per 100 km and 100 kg weight reduction been measured in the scientific study; the study addresses this discrepancy in more detail. As part of the project, the influence of a weight reduction of 100 kg on fuel consumption was determined on 11 selected vehicles by measuring very different driving cycles on a chassis dynamometer. The research results presented enable a quantitative evaluation of lightweight construction measures and the resulting weight reduction in road vehicles. STUDIENGESELLSCHAFT STAHLANWENDUNG e.V. Publication: 2000 Authors: Prof. Dr H. Wallentowitz, Priv.-Doz. Dr J.-W. Biermann, Dipl.-Ing. Ch. Renner

P 376: Development of a drawing device to reduce investment in the pressing plant Automotive companies are also under high cost pressure in the production of niche vehicles due to the small quantities involved. However, the necessary moulded sheet metal parts with less than 100 pieces per day cannot be produced economically with large-format presses. For this reason, a new concept for a weight- and cost-reduced press system was to be developed and tested in the research project. The prototype of such a forming unit was developed and built as part of an interactive collaboration between the Chair of Metal Forming and Foundry Technology, Munich, Schuler-SMG GmbH, Waghäusel, and Nothelfer GmbH, Wadern-Lockweiler. Trial pressings were carried out using a deep-drawing mould for the first drawing stage of an outer door panel. The initial focus of the investigations was on checking the accuracy behaviour of the forming unit and recording the influencing variables responsible for this as well as the elastic interactions during deep drawing. Information on the dimensional accuracy and surface quality of the components was provided by a comparison between the manufactured door panels and the original door from a large-scale press. In addition, a suitable FEM simulation model was generated for the forming unit and compared with the test results. Based on this comparison, the measurement results of the accuracy test could be interpreted and used for improvements. The research results proved that the new press concept can be used to produce moulded sheet metal parts in outer skin quality. The accuracy parameters required by press manufacturers and users are met and in some cases exceeded. Due to its low weight, the press can be used for mobile applications without compromising on quality. The application of this new type of lighter and also more cost-effective press system is aimed at the production of small quantities, for example in line with demand on a production line. The high local flexibility allows cost-optimised adaptation to new production conditions. The new development also allows small production series to be manufactured economically. STUDIENGESELLSCHAFT STAHLANWENDUNG e.V. Publication: 2003 Authors: Prof. Dr.-Ing. H. Hoffmann, Dipl.-Ing. J. Kuschke

P 379 - Modular hybrid design for rail vehicle construction Authors: K. Altenburg, O. Sauer, M. Zimmermann Publication: 2003

P 337: Comparison of the fatigue strength of hard-turned and ground components In competition with grinding, hard turning fulfils the demand for higher economic efficiency with better ecological compatibility. For a broad application of hard turning, it has not yet been proven that at least the performance properties, in particular the fatigue strength of components with a ground surface, can be achieved. This is where the present research project comes in and investigates whether hard turning can replace grinding, which has been the standard hard machining process to date. For the comparative investigation of grinding and turning of case-hardened components, notched round specimens made of 16MnCr5 case-hardening steel were selected as the material and subjected to 4-point alternating bending. A sufficiently small test radius ensured that the cracks only originated from the surface. To investigate the influence of tool wear during hard turning, the test specimens were turned with both new and defined worn inserts at two feed rates. Compared to ground samples, the fatigue strength was determined in the Wöhler test and the fatigue strength test. Cracking was used as the failure criterion for all test series. The fatigue tests were accompanied by metallographic analyses and residual stress measurements. The samples from hard turning with new tools always show a higher fatigue strength than the ground samples in the single-stage test with constant amplitude. The strengths decrease with tool wear; they are only lower than those of ground samples after prolonged tool use. In the fatigue strength tests with different amplitudes, no influence of tool wear was found in the load range investigated. The hard-turned samples always produced better fatigue strength values than the ground samples. With the help of a specially developed calculation concept, the Wöhler and fatigue strength results from the test series with turned specimens can be reproduced well. In contrast, the results of the test series with ground samples could not be determined satisfactorily by calculation due to the different surface topography, which was not adequately captured by the surface parameter used. As long as the tool wear during hard turning does not exceed a certain level, the fatigue strength is generally at least equal to or better than that of ground samples. The fatigue strength of hard turned samples only drops in comparison to ground samples at larger, but technically easily detectable wear mark widths. Up to this limit, hard turning is always more favourable than grinding case-hardened components, a finding that particularly benefits the small and medium-sized manufacturing industry. STUDIENGESELLSCHAFT STAHLANWENDUNG e.V. Publication: 2000 Authors: Dipl.-Ing. F. Renner, Prof. Dr.-Ing. H. Zenner, Dipl.-Ing. Ch. Borbe