Robotic palletising of building materials

The passion for natural stones can be felt everywhere in the Gandl company – in the landscape design, in the range of products and not least in the motivated team standing behind Rainer Gandl, founder of the company. No stone is like any other, neither with regard to colour and grain nor with regard to its nature. The offer for landscape design includes limestone, basalt, granite, slate, boulders, pillars and paving slabs – as well as kitchen worktops, bottom plates and steps for interiors. Gandl imports the material from all over the world. “Until now the coloured stones were offered merely as bulk material”, reports Rainer Gandl. “However, the intention was to package them and therefore the need of a complete new packaging line arose at our location in Kaisheim, in the Donau-Ries county.”

The natural stones are supplied in huge quantities. They are fed into silos for treatment by paddle wheel loaders. Jets of water are used to remove the dirt particles from the stones. Afterwards, the blank stones are treated for shape, size and surface and sorted by a screening plant. A conveying system leads the stones to the packaging system. Here, they are filled in plastic bags which are then welded.

“If necessary, the capacity can be increased to 400 bags per hour as, depending on package size and packing pattern, several packages can be gripped and moved at the same time to increase capacity”, confirms Schmidt. Owing to its extreme flexibility the BEUMER robotpac® manages even complex processes with varying basic parameters reliably and efficiently. “In addition, it is really resistant. This ensures safe operation even under extreme conditions”, explains Schmidt. The drives work reliably, highly efficiently and quietly.

Equipped with an additional drive axle and an integrated motor connected to the control system, the BEUMER robotpac® is freely movable on a guide rail. “The four-axis path computer is user-friendly and can be adapted flexibly to various conditions of use. The user does not need any robot-specific knowledge”, Schmidt points out. The robotic palletiser contains a multi-programme for all packing patterns. The BEUMER robotpac® can easily be switched to handle other sizes or materials by a mere push of a button or automatically by barcode identification.

Gripping gently and palletising efficiently

Depending on the application, we have developed different load handling modules to enable individual and efficient handling of different packaged goods, utilising for example fork grippers, suction grippers or parallel grippers. These can be exchanged at any time. “We have designed a special combined tool to ensure gentle handling and precise placement of the bags at Gandl”, explains Schmidt. It consists of a fork gripper for bags and a pallet gripping device. “This way we save considerable space and costs”, says Rainer Gandl approvingly. This combined tool does not require a pallet separator. “And, compared to the finger gripper, which would have been used instead, the layer forming is considerably better”, adds Schmidt.

“The fact that only vertical movements are possible ensures a particularly precise stacking process”, explains Schmidt. The forks open and the stripping comb pushes the bag from the fork. The gripping system leaves the pallet vertically and drives toward the roller conveyor with maximum acceleration. The cycle repeats.

An ultrasonic system provides accurate measures of the stacking height, making it possible to calculate the exact placing position of the packaged goods and stack these precisely and carefully. This guarantees an optimal stack configuration. “The latter not only serves as a mark of quality for Gandl, it also ensures high stability during shipping and storage. In addition, it ensures safe integration into the subsequent packaging processes”, says Schmidt. For this, Gandl uses the fully automatic BEUMER stretchpac R. This machine works according to the technique of the rotating pallet: the pallet turns, the stretch film is applied and cut and the film end is tack-welded, all this occurs automatically. The top side of the stack of packed goods is additionally protected by a top film sheet. “This way approximately 36 pallets per day are completed enabling a more rapid delivery to customers”, says Rainer Gandl.