For the manufacture of prefabricated building elements, MBN Holzelemente GmbH utilises gantry robots that make complete walls and ceiling sections out of basic panels. The production lines are supplied by cranes fitted with special load bars in accordance with the automatic machine cycles. A total of three Demag crane installations are used to manage logistics in the store and are essential to maintain the flow of production.
The storage and production facilities operated by MBN Holzelemente GmbH in Heiligengrabe are located immediately adjacent to the premises of the OSB panel supplier. This means that the panels can be transported only a short distance by truck from production to where they are needed. When they arrive, the panels, which have maximum dimensions of 2.8 m x 15 m, are picked up by a crane installation using a special load bar. This special design picks up complete stacks that weigh up to 23 tonnes, which avoids the need for time-consuming stacking of individual panels.
The crane unit consists of two mechanically connected 16-tonne double-girder overhead travelling cranes, of which one is fitted with control elements. With a span dimension of 30 m, they travel over the entire length of the 120 m-long storage bay. All travel and lifting motions are controlled by frequency inverters, which provide for smooth starting and precise positioning of the load. For the retrieval operation, stacks of panels are placed by the crane on a chain conveyor, which connects the store with the neighbouring production bay.
MBN employs two Demag cranes in the production bay. Both crane units each consist of two EKKE single-girder overhead travelling cranes, of which one each is fitted with the control system. A link arrangement maintains the fixed hook centre distance of nine metres as required for operation of the vacuum spreaders. One crane lifts the top panel from the stack and transports it to one of the four production stations. The entire process takes only a few minutes, in which the crane has to ensure that the required product is replenished. For this reason, fast operating speeds are necessary in order to keep the production facilities continuously replenished.
Besides the inverter-controlled motions on all levels, MBN attached great importance to the travel speeds that can be achieved. Variable-speed long-travel motions from five to 60 m/min and cross-travel speeds of up to 30 m/min were decisive factors for the award of the contract to us. The cranes finally pick up the prefabricated house sections, which are up to 250 mm thick and 10 m long, direct from the machine and place them on the truck.
The crane solutions offer sufficient flexibility for handling all manufactured parts, which also include smaller construction elements such as stair sections and triangular gables. For this purpose, the spreader bar can be quickly disconnected from the crane and the load can be quickly transported on the hook.
The production and storage bays feature mirror-image architectural designs and the crane runways were also rated for identical loads. In this way, MBN retains further flexibility in the basic use of both bays for the future.
OSB panels being placed into stoage with a special load bar. The time-consuming removal of single panels is avoided.
OSB panels being picked up with a vacuum spreader at the interface between store and production.
Demag crane solutions facilitate fast operating speeds and high handling rates.