Sensors key for automated high-bay warehouse

A two-aisle warehouse with 2,016 storage places for containers with dimensions of 1740 x 1240 x 540mm and a one-aisle warehouse with 648 storage places for Euro-pallets and for cloth pallets with dimensions of 1200 x 1600 x 1600mm were constructed.

Important project objectives were to maximise storage density and minimise the error rate during re-storage. The warehouse includes two combined storage and retrieval lines and a conveyor system with contour inspection based on the Leuze electronic VARIO B light curtain. Leuze products installed also included numerous retro-reflective photoelectric sensors of types PRK 25B and PRK 46B, but also devices such as light scanners of the 96B series for the precision positioning of racking equipment and of the 46B series for detection tasks on the high-bay storage device and hand-held scanners for manual code reading in the order picking area.

The positions of high-bay storage devices are monitored by AMS 348i optical distance measurement systems. In addition to position determination, they can also perform tasks for speed measurement and speed monitoring. Operating ranges of up to 300m are possible with high accuracies of up to +/-2mm with a reproducibility of up to 0.3mm (1 sigma statistical error) as verified by the Physikalisch-Technische Bundesanstalt, Germany’s national metrology institute.

The AMS 300i very accurately and quickly makes available the distance data for dynamic control via a unique selection of fieldbus interfaces. The AMS 348i model, in particular, is equipped with a Profinet interface for transferring distances, speeds and various status messages. The data are transferred on the Profinet network in accordance with standard RT (standard real time).

The Leuze electronic bar code readers are also at work in the new Mehler warehouse on the Profinet network. The new BCL 348i model with integrated Profinet interface and integrated 2-port switch is used there in a line structure. Configuration of the BCL 348i is performed via a GSDML file. In the Mehler solution, Walberer opted for the modular connector hood with M12 plugs that is optionally available for this bar code reader, since ready-made cables are used at Mehler.

Due to its modularity, the BCL 300i scanner family offers practical connection options both for preassembed cables as well as for the installation of cables from the reel. In other projects with BCL 348i devices, Walberer uses the optional modular terminal hood with the large terminal compartment. As a result, wiring on site is simple, fast and convenient, even if a Profinet cable “from the reel” is used.

At the container transfer station in front of the warehouse – a type of gate system for inserting the rolls of fabric in the container – the warehouse clerk on site is exposed to a risk of crushing. For this reason, Safety Light Curtains of type SOLID were installed there. These sensors reliably protect the point of operation and ensure a high level of safety at work in these dangerous surroundings.

Of particular importance in this context are the used Multiple Light Beam Safety Devices of the MLD series. These also safeguard the pallet transfer station at the entrance with integrated muting function. The MLD sensors are housed in UDC Device Columns that can easily be fastened to the hall floor and facilitate simple alignment. Combinations of Light Barriers and Device Columns as well as Deflecting Mirror Columns and Transceivers are available from Leuze electronic as various preconfigured sets (MLDSET, MLD-UDC). As a result, ordering and installation can be completed even faster.

Contour inspection was integrated in the pallet conveyor system. This task is performed by the VARIO B light curtain. The system, which consists of transmitter and receiver, generates a monitoring field of many infrared light beams and produces a reliable switching signal as soon as pallets penetrate this monitoring field. Easy installation, its small design as well as the integrated, configurable evaluation unit make the VARIO B an economical and flexible sensor solution.

With the help of sensors from Leuze electronic, Mehler cut inventory costs, and increased the level of automation meaning lower personnel costs and fewer booking errors.