CRANES & HOISTS I INTERVIEW The start of a revolution in crane engineering The “Red Dot Award: Product Design 2015” is already the second design award won by the Demag V-type crane. Andreas Hambrock, Head of Universal Cranes business line at Terex Material Handling, gives an insight into a development process which ended in an unusual surprise. Mister Hambrock, you were involved in the development of the new crane girder. Where did the idea for this come from? We are always looking for opportunities to match our products even more closely to the needs of our customers and to develop innovations that offer even more customer benefits. For this reason, we continuously maintain a close dialogue with our customers and also incorporate our wealth of experience from almost 200 years of our involvement in crane engineering. Consequently, we continuously work on upgrading our blue crane components, such as hoist units or geared motors with travel units. But we also asked ourselves: what aspects have we not yet explored? That is why we took a look at our yellow crane girders and analysed the steel superstructure on the basis of the state of the art and ground-breaking technology. What approach did you take to improve the crane girder? rigidity, stability as well as reduced oscillations and, as a result, improved handling rates. Using these specifications, we developed various concepts, which were individually analysed and evaluated by our strong team of development engineers. Not every innovative concept makes it through to becoming a series product. Ultimately, we also have to consider what can be feasibly manufactured – particularly with reference to our suppliers. We found the first promising signs of success when we conducted a stress analysis of a conventional box-section girder using a refined finite element method. What did this stress analysis reveal? It turned out that in certain areas, the panels of the box-section girder were subjected to no or only extremely low stress. This knowledge inspired us to take a look at nature and follow a bionic principle. For bones, nature utilises a structure similar to a honeycomb to ensure maximum strength, for example, and material is only employed where it is actually needed. Those were the first ideas that led to the new V-type girder. How did this new design affect the distribution of loads on the crane girder? A macro-analysis showed that the nodes were subjected to higher loads. To achieve a better distribution of these loads, we first used specially formed and folded metal that is shaped by means of state-ofthe-art laser or plasma cutters. We then also tapered the struts at the nodes and stiffened them at specific points. This results in a tapered diaphragm joint which can accommodate the pressure and tensile forces at the points where the loads occur and can channel the loads in a specified direction. This is also supported by a special slotted connection arrangement at the joints. This means that our Demag V-type crane combines the latest fabrication technologies, which we have patented. We based our considerations on the technical demands of our customers handling processes, such as improved torsional About Terex Material Handling Terex MHPS is one of the world’s leading suppliers of crane technology with Demag industrial cranes and crane components. The core competence of the Terex Material Handling business group lies in the development, design and production of technically sophisticated cranes, hoists and components and the provision of services for these products. The business group manufactures in 19 countries on five continents and is present in more than 60 countries, reaching customers in more than 100 countries.
INTERVIEW I CRANES & HOISTS Andreas Hambrock uses the model to explain the difference between the classic crane girder and the newly developed V-profile Did this new design also meet all of the requirements? That had to be seen. To do this, we not only tested the design in theoretical simulations, but also on an actual prototype that had a crane girder length which is typical for the market. As a comparison, we also used a crane that had a box-section girder with the same span dimension and load capacity. This enabled us to show that our crane system weighs less than its equivalent with a box-section girder. Consequently, we achieved an average weight saving of 17 per cent for a crane design that is ready for series production. We now know that we can even save up to 25 per cent of the weight in some cases. But the weight was not the only thing that you tested. We also used the comparison between the two crane designs – the box-section girder and the V-type crane – to test the oscillation characteristics of the crane. For a single change of load, we evaluated the amplitude of the generated and stimulated horizontal oscillation as well as the time needed until the crane had fully settled – Membrane joints at the ends of the stiffend struts ensure uniform distribution of the compressive and tensile forces that is its settling properties. This showed that the new design reduces the oscillation amplitude by up to 30 per cent, which meant that we had set another milestone in the history of crane engineering. The new crane girder design also produced impressive results on the vibration test system. From a theoretical point of view, we certainly expected to see the 250,000 load changes of a box-section girder to be exceeded. But even after 500,000 actual changes of load, namely lifting and lowering operations with a standard industrial load, the V-type crane still did not display any signs of material fatigue. Did that mark the end of the tests? To verify these benefits also in practical applications, we selected a group of customers from various industries and supplied them with prototypes. Together with these customers, we carried out tests under realworld conditions, evaluated the results and compared them with cranes that have boxsection girders and which were installed in the same way. The results were an exact match to our laboratory tests. But we still had not reached our goal. Many teams at various locations invested another year’s worth of their expertise, passion and innovative ideas in our crane system to make it ready for series production. Just before we were finished, there was a surprise. We had developed the Demag V-type crane as a single-girder crane. A team member had the idea to analyse how it could be used for our entire Universal crane product range. It quickly became obvious that a V-type girder could also offer our customers added value when it is used on other types of crane, such as suspension cranes, wall-mounted travelling cranes, portal cranes and double-girder overhead travelling cranes. This means that the patented V-type design can be easily used for double-girder cranes. For this reason, we can already market a corresponding doublegirder overhead travelling crane from the middle of this year. And we are confident that it will also be a complete success. Especially in view of the fact that many single-girder variants of our V-type crane are already in operation. In addition, the Demag V-type crane has already won two prestigious design awards. Thank you for talking to us. Andreas Hambrock was interviewed by Manfred Weber, editor of f+h Intralogistics. Photos: Holger Seybold, Terex www.terex.com MULTIMEDIA CONTENT Internal video: Learn more about the achievement spectrum of the enterprise. Click to read previous issues. Inspiration is just one click away. News about the following markets: f+h Intralogistics 3/2015 39