P 457 - Investigations into the production of lightweight steel tubes by means of moulding with active media

Low manufacturing, transport and processing costs compared to other possible methods should result in a very favourable price-performance ratio. The following steps were developed to produce a steel hose suitable for such purposes. Strip steel is formed into a strip with double thickness on both sides towards the centre in four stages by means of sliding draw bending. This is followed by roll seam welding with a butt joint. A continuously operating line for a strip width of up to 500 mm and a thickness of up to 1.2 mm was designed and realised for this purpose. At the beginning, the strip is unrolled from the coil, then formed and welded. At the end, the double strip is rolled up using a coiler. It also handles the entire strip tension through the system. The pre-material produced in this way can then be cut into the lengths required later and the connections for moulding into the pipe can be attached using an active medium (liquid or gaseous) either afterwards or at the point of use. Pre-material for welded double pipes was produced on the prototype system in a continuous process up to a length of 50 metres. The length limitation is plant-related and not process-related. By splitting the starting material, it is also possible to produce starting material for two pipes of the same length at the same time using simple means. The possibility of using, for example, a fire extinguishing screw that rolls itself out under water pressure to form an extinguishing spike for fires has been demonstrated with material thicknesses of 0.32 and 0.5 mm. For use as a transport line, the pre-material for the steel hose can be inflated on site with the medium to be transported if necessary. As part of the research work, an inexpensive and effective process for the continuous production of a welded tubular steel hose moulded with active media was developed and brought to prototype maturity. The process is particularly suitable when the quality requirements for the product are low and roll forming is too costly due to small batch sizes. Possible applications are primarily seen in emergencies when transporting water, fighting fires, constructing emergency bridges or floatable pontoon segments, but also in the construction sector, e.g. as permanent formwork and for installation ducts. STUDIENGESELLSCHAFT STAHLANWENDUNG e.V.