Herma specialises in the manufacture of self-adhesive labels and label machines. It operates one of the world’s most advanced coating plants and this facility is supported by a high-bay warehouse where manufactured material on rolls is stored and subsequently conveyed to the cutting machines and the packaging lines for ultimate despatch to global customers. The entire warehouse is automated and its operation is reliant on a large network of sensors and safety devices supplied by Leuze electronic.
Following the flow of materials through the warehouse starts at the goods receiving area where paper and foil rolls are unloaded from trucks and placed on a lifting table by a clamping truck. A Leuze Solid-2E safety light curtain with a protected field height exceeding 2m can be seen on the right of this picture, as can a Leuze BCL 80 high-speed barcode reader, mounted on the ceiling.
Precision positioning of the rolls is achieved with the aid of a Leuze BPS 34 barcode positioning system, which is entirely optical in operation and thus avoids any mechanical wear and slippage issues, and removes the need for reference points.
A vertical conveyor transports the roll to the interior of the goods receiving hall where a fully automatic gripper gently places it on a transport system pallet. This transport system pallet uses Leuze 46B series retro-reflective photoelectric sensors to detect presence, exact position and to supply signals to the fire door control. Solid-2E light curtains are also deployed in this area.
Storage in the high-bay warehouse
Transport carts, the position of which is determined by another BPS 34 barcode positioning system, transport the rolls to the storage hall, where they are received by one of the two high-bay storage cranes. Here a Leuze DDLS 200 data transmission photoelectric sensor (visible on the wall and the side of the high-bay crane in Figure 3) continuously transmits the position data of the high-bay storage crane directly to the control system PLC. The position of these high-bay cranes is also ascertained using the BPS 34 barcode positioning system.
Another feature oft the high-bay storage area, is the use of Rotoscan RS4 safety laser scanners to protect maintenance staff when entering the storage aisle danger area. An RS4 laser scanner mounted on the high-bay crane close to floor level reliably safeguards the traversing area and, if a person enters the danger area of a moving crane the system shuts down. Thus if one high-bay crane is shut down for maintenance, the other is able to continue to work, providing that the safety laser scanner does not detect it approaching the maintenance worker's location, in which case it will also be shut down.
Transport portal and distribution cars
The raw materials required for an order are retrieved from the high-bay storage unit on a ‘channel car’ and delivered to the roll-out conveyor. Here, the roll is unpacked and transferred via a fully automatic transport portal, which was specially designed for Herma. This portal either stores the roll in a buffer or transports it directly to the roll unwinding/winding machine via a distribution car.
At the transport portal/distribution car interface, Leuze’s Robust series multiple light beam safety devices are used to safeguard the access points to the danger areas.
Numerous Leuze PRK 96 retro-reflective photo-electric sensors control the start/stop function at the transfer station. The grippers for the rolls are also equipped with retro-reflective photoelectric sensors and BPS positioning systems.
Jak Pluder, who is responsible for technology and maintenance at the Herma facility believes the co-operative relationship built over a number of years with Leuze personnel really has paid dividends on this latest project. He expresses particular satisfaction with the company’s ability to come up with novel technical solutions to the many problems that present themselves during the course of such a complicated project. “For all of the special tasks and exceptional requirements in automation, be it detection, positioning or safety-related sensor systems, we can count on Leuze’s employees to be at our side with help and advice.”