Images

Vertical conveyor with integrated turning station for a three-sided roller conveyor connection. © HaRo

Conveniently located at the port, the Kehl site offers Raiffeisen Kraftfutterwerke (RKW) optimal conditions for the supply of raw materials by ship, rail and for up to 20 trucks, which are handled daily at the loading ramp. Founded in 1963 as a subsidiary of ZG Raiffeisen, RKW Kehl has been producing compound feed for livestock for over 60 years. Since 1987, the company has also specialized in the production of high-quality dry pet food products.

Pallet feed for automated transport to several levels. © HaRo

The task of this conveyor system is to quickly, efficiently and reliably distribute the flow of goods arriving by truck in the form of big bags, buckets and bagged goods on different pallet types to the six storage areas on three levels. The employee selects the destination for the current pallet at a control panel and places the goods on the galvanized roller conveyor in the incoming goods area. Flat bars mounted in the set-down area support the depositing and positioning process.

Incoming goods inspection for a reliable material flow

"With a system of this size, extensive inspection processes are essential before the goods are fed into the goods cycle to avoid faults," explains Markus Löseke, Head of Design. After being fed into the incoming goods department, the conveyed goods first undergo a contour and skid check in order to detect any safety-relevant damage to the pallets.

The next step is the legally required overload detection with a mechanical scale underneath the roller conveyor. This ensures that the maximum load of the vertical conveyor is not exceeded. If the result of one of the tests is negative, the pallet moves back. If the feedback is positive, the pallet is released for onward transportation. The driven roller conveyor transports the pallet fully automatically to the preselected storage level in the desired building section and floor.

In addition to automated transport, the entire roller conveyor section can also be used as a short-term pallet buffer. Here, the conveyor system works according to the block accumulation principle. A block of up to three pallets is formed on the first roller conveyor segment, which is then transported in one piece to the furthest free roller conveyor. This process avoids gaps forming on the roller conveyor and ensures the highest possible buffer capacity. As a result, the section up to the first vertical conveyor can accommodate a complete truck load of 36 pallets. On the driven roller conveyors between the two vertical conveyors, the PLC control system also stores the destination addresses of the conveyed goods and tracks them along the conveyor line to their destination.

Installation of the vertical conveyor on the outside of the building.

To ensure trouble-free operation, additional guide rails were integrated along the roller conveyors as a passive safety component. This central guide ensures that the different pallet formats reach their destination in a straight line on the conveyor section, which can be up to 70 m long. This prevents the pallets from "getting lost" due to different runners and dimensions.

Facts, figures and data

The conveyor system installed by HaRo has a total length of 141 m and is divided into two sections of 68 and 70 m plus the vertical conveyors that can be driven through. The total sections were divided into 22 segments of 6 m each. Only one drive unit per roller conveyor segment is required to transport the goods, which weigh up to 4.5 t in total. This reduces investment costs and saves energy in the long term.

Roller conveyors with a low overall height were used on the individual storage levels. At only 80 mm in the storage levels, they enable easy removal of the incoming pallets using a pallet truck. To increase the vertical conveyor's cycle times, several buffer spaces were created on the storage levels for the incoming and outgoing goods. In this way, the vertical conveyor can unload its load at any time and pick up new goods on the adjacent floor. Empty runs of the car are thus minimized.

The roller conveyors were installed on the existing truck loading ramp; only the vertical conveyors had to be placed on a lower foundation due to their own weight of 6 tons and a height of 14 m.

The customer's specifications stipulated an output of 60 pallets per hour with a maximum lifting height of 8.6 m. In order to achieve these values, the vertical conveyors were each equipped with a drive power of 11 kW. This power enables a vertical travel speed of up to 37 m/min with a maximum load capacity of 2,000 kg.

Vertical conveyor with integrated turning station

The special feature of the vertical conveyors is the T-shaped arrangement of the adjacent roller conveyors. Given that the pallets can only be transported lengthways on a roller conveyor, the pallets are already rotated by 90° in the vertical conveyor. A specially integrated turning station in the cage enables the pallets to be correctly aligned so that they can be removed smoothly from the storage levels.

The demand for complete systems on this scale is constantly increasing. Project coordination requires the utmost attention. "Particularly when extending existing buildings, close cooperation with the customer and other trades is essential," says Markus Löseke. "We were in close contact with the structural engineer and the steel constructor of the external cladding throughout the entire construction phase." Managing Director and Project Manager Maximilian Hackländer adds: "We would like to take this opportunity to thank the Project Manager at RKW Kehl, Hans-Peter Luhr, who provided exemplary support to everyone involved and was always available as a point of contact."