The example of transport automation for heavy cable drums has shown how productivity can be almost doubled at reasonable cost.
In industrial cable processing the desired quantity is unwound from the storage unit and cut to length. When the cable rolls are carried in and away using floor conveyor trucks, the time taken for changing the cable drums weighing up to 15 tonnes and for the preparatory work is relatively long.
The entire process can be speeded up if a magazine is positioned upstream from the unwinding machine, by virtue of which the material needed in each case – transported automatically – is brought directly to the machine run-in and at the same time the material to be returned to the store is automatically carried away. A magazine of this type for coils up to a maximum of 15 tonnes was developed by H+H Herrmann + Hieber for a well-known company.
The magazine installed has four deposition positions arranged in a square (2 + 2, respectively next to and behind one another). The four carrying trolleys can each be moved automatically in the longitudinal and transverse directions. One of the magazine’s positions (the transfer position) is associated with the unwinding frame. At that point either the coil recovered from the store is transported to the magazine or the next coil needed is transferred to the frame. Thus, in all three of the four carrying trolleys can be occupied.
On one side of the magazine, easily accessible by floor conveyors, the delivery point and the collection point are next to one another. On the opposite side, also next to one another, are the stand-by position and the transfer point to the frame. To exchange drums the following work steps are then carried out:
the cable drum in the unwinding frame is recovered and moved to the transfer point,
the occupied trolley moves transversely from the transfer position to the collection position,
the next cable drum needed moves longitudinally from the stand-by position to the transfer position,
the trolley with the next drum delivered by the floor conveyor moves transversely from the delivery point to the stand-by position.
The control of the inward and outward transport movements is integrated into the overall plant control system.
The automatic magazine has many advantages. In this specific case, according to information from the operator productivity has been almost doubled. Instead of the previous 20 to 22 work cycles per hour, now around 45 cycles can be completed. There is also the cost-cutting effect of a reduced workforce.