TPT May 2011

T echnology U pdate Stainless steel strip accumulator from Italy

and for joining the strip. The FBS Inox accumulator is essentially composed of two groups of rollers that form the inner drum and the outer drum, which are arranged in two concentric circles. The inner drum is fixed, while the loading drum rotates around its axis. The strip is unwound by the decoiler and loaded by a pinch-roll into the machine at a speed that is higher than the line to be fed. The strip is drawn in by the loading roller as the loading drum rotates. Besides drawing the strip, the loading roller also transfers it from the loading drum to the inner drum when the machine is loaded or emptied. As the strip is extracted by the tube formation line, it moves from the inner drum, turns around a centrally mounted roll set, and is pulled over the asymmetrical gap between the entrance and the exit by the entrance and exit rollers and the slanted rollers. During machine operation, the strip is removed from the two (internal and external) coils of accumulated strip with virtually no friction. As a result, the force required for extracting the material from the accumulator is relatively small. The strip is restrained at the sides by lateral guide rollers which rotate on bearings. Strips of any width and thickness (within the operating range of the machine) can be accumulated. However, the thickness and width of the strip must be adequately proportioned, since the accumulation properties of a strip that is thin and also small in size largely depend on the type of material the strip is made of. Oto Mills – Italy The improvements have led to lower stress and power loss in the transistors and the inverter module across the whole frequency range used for tube and pipe welding. The company states that the Weldac has proven so reliable, it warrants the welders’ IGBT inverter modules and driver cards for a total of five years of operation. EFD Induction has manufacturing plants, workshops and service centres in the Americas, Europe and Asia, with corporate headquarters in Norway. EFD Induction – Norway Fax: +47 35 50 60 10 Email: sales@no.efdgroup.net Website: www.efd-induction.com Email: otoinfo@otomills.com Website: www.otomills.com

WITH the growing popularity of plants that produce stainless steel tubes using a laser welding system, which has helped to increase processing speed, there is now a need to create an accumulation system with sufficient capacity for joining the head/tail of the strip and thus to replace obsolete cavity-type or looping accumulation systems. That’s the reason why Oto Mills created the FBS INOX accumulator, which was developed with the company’s thirty years of experience with this type of unit. Besides offering the proven advantages of Oto Mills accumulators, FBS models have a series of additional custom features that were exclusively developed for use with stainless steel. In particular, all the rollers and surfaces that contact the strip have been specially treated so that they maintain the surface of the material intact. Also, a special control system is used that optimises accumulation to prevent the strip from being scratched and ruined, while still maintaining the capacity that is required for joining the coil in a way that is suitable for being fed into any production line placed after the accumulator – even those that are obsolete and which require a great deal of time for preparation Welding frequency up to 500kHz NEARLY 10 years of successful use of a patented switching technology has proven the reliability of EFD Induction’s Weldac IGBT welder. Refinement of existing technology has improved and extended the use of readily available, reliable and standard IGBT transistors up to 500kHz.

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M ay 2011

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