TPT July 2010

T echnology U pdate

Three-roll plate bender that forms plates to pipes and cones without changing rolls

MACHINES with multiple talents are always sought after due to their versatility. The 3-roll plate bending machine made by Gräbener Maschinentechnik from Netphen- Werthenbach, Germany, is one such all- round talent. The smooth and fast production of pipes and half-shells, pressure vessel shells and cones is possible – without having to change rolls. This is ensured by the fully flexible adjustment of the two bottom rolls and the top roll. The bottom rolls can be adjusted individually via a hydraulic system (centre distance between 950mm and 1,500mm), the top roll can be vertically adjusted by up to 320mm, moreover, all three rolls can be set to an inclined position so as to bend conically shaped workpieces. The 3-roll plate bending machine from Gräbener has few rivals in terms of flexibility. This was witnessed by the management of an important pipe manufacturer during a visit at another Gräbener client that operates the most recently built 3-roll plate bending machine. Upon this client’s express request and according to his specific requirements, Gräbener designed a multi-talent machine that is able to bend plates to pipes, half- shells, pressure vessels, and cones. After smartly having pre-bent the plate

The Gräbener 3-roll plate bender in action (and below)

edges, the 3-roll plate bending machine, of compact design, bent the 80mm thick plate to a cone with radii of 2,592 (1) / 2,698 (2) mm – also in near-record time. The decision- makers were caught by surprise when looking at the short straight end because on this Gräbener machine, the bottom roll can approach the top roll to within a distance of 100mm. This is enabled on the one hand by the flexible adjustment of the rolls, and on the other hand by the fact that the conical bending device, which controls the bending of cones, can be slewed away completely. The operator constantly obtains exact information on the relevant position, as well as on the individual contact pressure of the rolls. All data are displayed on instruments integrated in the control panel. The visitors were even more impressed when they were told that the bending capacity (plate thickness) of this machine for plates of material grade S355, over the entire roll length of 3,100mm, is 120mm. Heavier thicknesses of up to 200mm, depending on material grade and plate width, can also be bent efficiently. One of the visitors stated: “The 3-roll bending machine is a genuine multi-talent.” Another product within the Gräbener roll bender family is the 4-roll bending machine

which can be equipped with a supporting yoke. This machine type performs the highest quality requirements, reduces the calibration efforts to a minimum, and will – no less than the 3-roll bending machine – fulfil various bending tasks. With a supporting yoke, it is possible to install a top roll of smaller diameter, which allows the production of smaller pipe diameters. And what is more, a discussion on the top roll camber layout, which would enforce to determine a certain pipe production range in advance, is avoided. With the Gräbener concept, the plate thickness range from small up to the maximum possible sizes can be realised without any restrictions, owing to the fact that the supporting yoke can be hydraulically adjusted to the individually required bending force. The plate edges are in parallel; convexly respectively concavely shaped pipes become a thing of the past. Thus, an optimum precondition for welding is achieved. Graebener – Germany Fax: +49 27379 89109 Email: info@graebener-group.com Website: www.graebener-maschinentechnik.de

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J uly 2010

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