TECHNOLOGY REPORT | PROCESS CRANES
material. Digital control and feedbacks of data have increased this interdependence to the point where crane, factory and process have become a single indivisible unit. ‘Holistic’ is an overused buzzword, but it does describe the way in which the entire production operation can be regarded as a single process rather than as a series of connected units. Consider, for example, Demag’s recent contribution to steel fabrication company Stahlo. Stahlo Stahlservice processes sheet steel into customer-specific strips, blanks and cut-to-size sheets at its plant at Gera near Leipzig in Germany. The plant presses steel for automobile bodies; for further steel processing and refining at the site the company has just completed an entirely new steel service centre there. Stahlo has built five more production bays and has invested in, among other areas, another pressing line with a contours press that can deliver 800 tonnes of force. Stahlo’s intention was to double the capacity of the plant. To achieve this the material flow needed to be restructured. That is why 12 new cranes have been installed in the new production bays. Demag Cranes &
Components won the tender for the project. Stahlo did not buy just the cranes from Demag. In with the cranes came the Demag Warehouse Management System (WMS), which will control the entire material flow through the plant. The production process begins in the
central coil store. Here aluminium coils weighing up to 30 tonnes and steel coils, up to 40 tonnes, are stowed. The two process cranes in the coil store
have a load capacity of 48 tonnes each, and a beam length (track gauge) of 41.10 meters. They travel on a 126 metre runway. The coils arrive by rail or by truck; after unloading them the cranes are operated manually. The coils are placed first on one of three motorised roller tables, which makes it possible to easily remove the packaging. After quality control the process cranes
– now in fully automatic mode – lift and deposit the coils at the storage location specified by Demag’s WMS warehouse management system. Aluminium coils are moved by grabs, steel coils are moved by magnets. The cranes need therefore to be able to change their load
handling attachment easily, quickly and automatically: the changeover is made via a permanently reeved spreader. Handling by magnet offers the
advantage that the coils can be stacked with smaller spaces left between them. As a result, the necessary distance between the coils is reduced from 800 mm to 400 mm. The cranes sense which type of coil is being handled, and therefore how close together they should be stored. They are equipped with automatic position measuring systems for setting down the loads with absolute precision at the spot required. Accordingly, the intake capacity of the warehouse is increased. The next set of cranes deliver the coils on demand to defined transfer points in production bays numbered two to six. The bays are arranged transversely to the central warehouse and are where processing and refining takes place. The performance of these cranes was designed for high handling rates. Their duties also include re-storage of residual amounts from processing, which is also performed at high speeds. The production bays themselves, where
R The Demag process crane lifts a steel coil with a magnet, at the Stahlo plant
www.hoistmagazine.com | June 2021 | 37
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49
