METALS | APPLICATION REPORT
R Demag’s charging crane at Baden-Wurttemburg; the manual hand wheel has been replaced by automatic control
All parts of the mechanical and electrical equipment are designed so that they are easily accessible from permanent service platforms for adjustment, lubrication, inspection, maintenance and repair. Out-of-service times must be reduced to a minimum, so emphasis is placed upon quick replacement of faulty or worn parts as opposed to repair. Illustrating the challenges of these conditions is a charging crane installed by Konecranes for steel company Rautaruukki in Finland. Its Raahe plant produces 2.8 mmt of
hot rolled steel and special steel products a year. The existing charging crane in its foundry was installed in 1975 and was reaching the end of its useful life. Konecranes designed a 220/60t
replacement crane. The crane is central to the manufacturing process, so reliability and near-constant availability were essential. The replacement also needed to be able to fulfil the increased production rates planned for the plant.
38 | October 2022 |
www.hoistmagazine.com The new crane was equipped with
several redundant features; for example the variable frequency drive and network braking units were both given redundancies. fitted. State-of-the-art motion control technology gave safe operation at higher speeds to address the capacity requirements. The operator emphasised maintenance and user-friendly operator interface as important. Here again digital technology came into play: the crane is equipped with Konecranes’ crane monitoring system for efficient maintenance and smart control features such as sway control and semi-automatic positioning for user-friendliness in operation. Everything was designed and carried out with close cooperation with the customer. The crane has now been installed; demand needs have been met, as have the needs of reliability and maintainability. A lifespan of at least 30 years is expected from the crane. On top of the extreme environmental demands on them, foundry cranes
have to do the job quickly. Matthias Meisberger, is head of technical planning at SLR Giesserei St.Leon-Rot in Baden-Württemberg, Germany. It is a foundry that specialises in sophisticated components made of spheroidal-graphite cast iron – an iron casting material whose properties match that of steel and with which SLR produces, for example, high-strength travel unit components for construction and agricultural machinery. “If the cranes fail, the foundry will come to a standstill,” says Meisburger. “And that doesn’t just apply in the event of a lengthy period of downtime. We have a maximum period of 15 minutes to transport the material from the melting furnace to the mould line. If the spheroidal-graphite cast iron has not been cast by then, the treatment effect wears off and it turns into conventional grey iron, which is of no use to us.” His foundry uses two Demag foundry
cranes to transport molten cast iron from the melting furnaces to the casting cars that take the material to the mould line.
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