Vertical conveyors for cassettes holding long articles

The extrusion plant at Aluminium Laufen AG in Liesberg, Switzerland, has completely automated its in-house material flow. When the capacity of the plant was enlarged with an additional production line, there was not enough space available for the additional areas required. The answer was to provide extra space 5.5 and 2.75 metres above ground level. The new areas had to be integrated into the automated material flow system.

Task assignment

In the plant all the section production operations are arranged at ground level. The material is transported in racks (maximum length 8,500 mm, maximum weight 2,000 kg).

• The load carriers are stored intermediately in stacks on the mezzanine level (+2.75 metres).
• All further processing activities are accommodated on the upper storey (+5.50 metres) of the new shed.

For the two newly provided levels vertical conveyor equipment had to be installed for the incoming and outgoing transport of the load carriers.

Conveyor concept

The choice of the conveyor equipment is orientated toward the material flow and to the details of the jobs to be done in each case. For the transport of long articles in the extrusion plant of Aluminium Laufen AG various methods for transporting material vertically are used:

• Automatic cranes. These take up the filled racks at ground level and move them to the intermediate store on the mezzanine level at +2.75 m.
• Shear tables. Return transport from the intermediate store at mezzanine level back to level 0 is carried out by three shear tables arranged next to one another. Owing to the large dimensions involved, each of these is equipped with double shear drive units.
• Four-column vertical conveyors. For transport between section processing stations on the upper storey (+5.5 m) and level 0, two vertical conveyors are provided.

Vertical conveyors

The two vertical conveyors, each of four-column design and modern construction, transmit the movement by way of chains. The technical features of the two components are identical, namely:

• Payload 2,000 kg
• Lifting height around 5,500 mm
• Lifting speed (frequency-controlled) 0 to 0.3 m/s
• Powered by frequency-controlled, three-phase alternating current asynchronous motors
• End-position disconnection
• End-position buffer
• Path measurement by absolute-value indicators on the motor shaft

In the two vertical conveyors the transport equipment installed on the lifting platform is different. The aggregate provided for rack transport is equipped with a telescopic fork-lift that can be extended in both directions, in each case by 1,500 mm (movement speed 0.1 m/s). The fork can be inserted under the load carrier, lift it, and transport it in the transverse direction. On the upper level the transport fork deposits the load carrier directly onto a conveyor stretch.

The second vertical conveyor transports the components made from extruded sections back to level 0. On the lifting platform of this conveyor there is installed a transverse chain conveyor that can move in both directions over a path of 1,600 mm with a track width of 4,200 mm. Here too the movement speed is 0.1 m/s. This transport solution is appropriate at the point concerned because the necessary change of transport direction can be carried out without problems by the load carriers used for transporting the components away.