Impressive dimensions
Everything about the palletizing system for tinplate containers from de Man sets great standards: An approximately twelve-meter-long linear robot, seven palletizing stations including the associated pallet conveyor technology, a combined weighing and camera station, two cross-transfer cars and a pallet and bottom layer magazine each ensure a smooth palletizing process for the customer Geholit+Wiemer. The scope of supply also included the light conveyor technology for the product feed, some of which was set up in the potentially explosive area.
Since 1889, GEHOLIT+WIEMER has been a manufacturer of high-quality, versatile and environmentally friendly coating solutions in the fields of corrosion protection and industrial coatings. Since 2021, GEHOLIT+WIEMER has been part of the Swiss KABE Swiss Group, which is represented by several companies throughout Europe. At the main site in Graben-Neudorf, filled tinplate containers were to be conveyed out of the Ex zone, run through a weighing and camera station and finally palletized on Euro pallets. de Man Automation + Service GmbH & Co. KG, a specialist in individual automation solutions from Borgholzhausen, was commissioned with the implementation.
Clearly identified
The system developed by de Man can be divided into two areas: the light conveyor technology in the filling area in the EX zone and the conveying and palletizing area outside the EX zone. In the filling area of the EX zone, the tinplate containers are filled at several filling stations and first pushed off to a link chain conveyor via short, non-driven roller conveyors. This also creates a separation between the manual and automatic areas. The link chain conveyor transports the containers out of the filling area and transfers them to the conveyor system outside the EX zone. For safety reasons, both areas can be separated from each other by a fire protection gate. The containers then first pass through a weighing and camera station. This consists of an enclosure, a roller conveyor mounted on a scale and cameras mounted on the side and above the conveyor system. The scale carries out a 100% check of the weight of all containers in accordance with the prepackaged goods regulations, the cameras recognize the barcode and the position of the snap closure. All information is passed on to the control system so that the products are conveyed to the assigned, single-variety palletizing stations. If necessary, containers can be temporarily buffered in several storage locations in front of the station.
Single-type palletizing at seven palletizing stations
After the weighing and camera station, the tinplate containers are fed to the robot. For efficient and fast single-type palletizing, the system has seven palletizing stations including the respective feeders, so that seven different items can be palletized at the same time. In order to achieve the corresponding range, de Man relied on a linear robot from the manufacturer KUKA (type KR 80L) with an impressive length of around twelve meters. The link chain conveyor transports the containers to the transfer points on the feed belts for the palletizing stations. A discharger pushes them with its pusher onto the feed belt for the respective palletizing station, where they are conveyed to an end stop. The robot then removes the containers with its gripper and places them on the pallet at the corresponding palletizing station in accordance with the previously defined palletizing pattern. To grip, the linear robot positions its gripper with the pressure plate on the lid, then the gripper jaws grip the containers on the side of the casing. The cycle time is eight seconds. Containers that are identified as not OK in the weighing and camera station are not conveyed to the palletizing stations, but are ejected from the system.
Two cross-transfer cars for fast pallet transport
The smooth replenishment of empty pallets for all seven palletizing stations is ensured by a pallet magazine and a cross-transfer car. At the empty pallet loading station, the operator uses a forklift to place a stack of a maximum of twelve empty pallets on the empty pallet roller conveyor. This consists of roller conveyor sections driven in segments with sensors for tracking the pallets. It transports the pallet stack to the empty pallet magazine, where the pallets are separated. The separated empty pallet is fitted with a base layer at the base layer magazine and then transported to the designated palletizing station using a cross-transfer car. To ensure fast pallet transport, the system also has a second cross-transfer car. This transports the full pallets from the palletizing stations to the full pallet roller conveyor, via which they are conveyed out of the system.
Safety is a top priority
There is a multi-beam safety light barrier in the discharge area of the full pallet roller conveyor. When the light barrier is triggered, the system switches to a safe stop, but muting sensors allow a temporary interruption when the pallet is entering and leaving. Several emergency stop buttons installed at regular intervals also bring the system to a safe stop in an emergency. To protect the system areas in the event of a fire, there is a fire protection gate on the system between the palletizing and EX areas. The system is operated using the intuitive de Man visualization. The "Overview" menu offers a schematic representation of the system and provides quick and easy access to all functions. In various windows, all items can be displayed and edited, orders, containers and pallets can be displayed including the associated data, or the various conveyor technologies and the gripper can be operated manually. Particularly practical: In the de Man palletizing scheme generator, the customer can create new palletizing schemes themselves or optimize existing schemes. This means that a service call does not have to be requested for every desired change.