A gripper for everything

The palletizing system for the Rosnerski company had to save space and be able to handle two completely different product types with just one gripper. Because both sacks with gravel and cartons should be packed fully automatically on EURO pallets without changing the gripper. The solution: The compact MRZ from de Man with a width of only 2.46 meters and a specially developed fork gripper for safe transport of the products. Buffer areas for both light and pallet conveyor technology ensure a smooth palletizing process. And Rosnerski is also well prepared for future changes in the product range: customers can create new packing schemes themselves in just a few steps in the de Man packing scheme generator.

The company Rosnerski Building Materials & Zool. Requirement is a family business founded in Königslutter in 1976. His focus is on the extraction, processing and packaging of bulk materials (sand, gravel, lime, salt, pellets, etc.) for various areas of application. In order to keep up with the constant growth of the company, Rosnerski continuously invests in the automation of its processes. In a new palletizing system, both gravel packs and cartons were to be packed fully automatically on Euro pallets. Rosnerski opted for the MRZ 2.1 from Man Automation + Service GmbH & Co. KG. The palletizing cell is characterized by its particularly compact design as well as high precision and flexibility. Since this is a standard product that only has to be adapted to the respective customer requirements, the MRZ can also be delivered and ready for use quickly.

Fork gripper for optimal handling
In order to start a packing order, the operator first selects the item to be palletized on the HMI PC. A packing scheme is assigned to each item, in which the packing sequence is stored like a recipe. The corresponding products are conveyed into the palletizing cell via a roller conveyor belt and positioned at the pick-up point by a stopper and lifters for the robot's gripper. The robot – a Kawasaki RD080N was used – now removes the gravel packs or cartons from the roller conveyor and places them on the pallet according to the previously defined palletizing scheme. Since the gravel packs cannot be sucked up, de Man developed a fork gripper for this system with a lateral clamping plate and a hold-down device that can safely transport both types of product. This was dimensioned in such a way that containers up to the maximum dimensions of 365mm x 235mm x 220mm can be handled. The maximum product weight is 25 kilograms. The system is only designed for single-variety palletizing. While the robot is packing the products onto the pallet, the next ones are already entering the cell to ensure a continuous palletizing process. Intermediate and top layers are not laid. The gravel bundles with the highest throughput are produced at 5 pieces per minute, resulting in a cycle time of 12 seconds for the palletizing process. The boxes with the highest throughput are produced at 7 pieces per minute, resulting in a cycle time of 8.5 seconds per box.

Fast changeover time thanks to buffer space
The empty pallets (EURO pallets) are manually fitted with a base layer and placed on the loading area of ​​the pallet conveyor system using a forklift. The conveyor system first transports the empty pallet to an empty pallet buffer location. If necessary, it is conveyed from there to the palletizing station, aligned and packed. The finished pallet is finally delivered to the full pallet buffer area, conveyed to the acceptance point and picked up by a forklift truck on the long side of the 500 mm high roller conveyor. While the full pallet runs out, the next empty pallet is already moving from the empty pallet buffer location to the palletizing location. This achieves the shortest possible pallet changeover time. The facility is surrounded by a protective fence. Access to the system parts is via a protective door, which must be requested. The safety lock with guard locking only allows opening when the dangerous movements have been safely stopped. Trapped persons can leave the cell thanks to an emergency release. A light barrier with muting function allows the pallets to be ejected in automatic mode, but prevents unauthorized access to the system.

Create packing schemes yourself
The system was delivered with three pre-installed packing schemes. Additional packing schemes can be created by the customer himself in the de Man packing scheme generator after appropriate training. An S7 1510F is used as the central controller. It controls the fieldbus system (Profinet) and supplies the robot controller with data. For its part, the PLC receives product data and control data from the HMI, a PC with an SQL server as a database. There are no network interfaces to an ERP system. For remote maintenance, the PC is integrated into the company network, access is via VPN via VNC. The proven and clear de Man visualization is used as the user interface. It includes the clear representation of the system layout on a touch screen. All relevant operating elements are located directly on the main screen, the operator can get a quick overview of the status of all system parts and display complex components in more detail. It is operated intuitively and with a “click” as you are used to from smartphones. Of course, the view is customized in each case and can also be flexibly expanded. For Rosnerski, the user interface was subsequently supplemented with another menu item requested by the customer.

Standard and yet individual
The modular robot cell MRZ used is part of de Man's "M-Series". The automation specialist offers its customers a range of pre-planned modular robot cells for various applications: the MKA for erecting boxes, the MPZ for packing goods into boxes, the MRZ for palletizing and the MEZ for labeling. All cells are controlled by the MFR material flow computer. The "M-Series" is characterized by a compact footprint, great flexibility and high precision and speed. All cells can be individually adapted to specific requirements and expanded with options such as camera technology or additional conveyor lines. All products in the series can also be combined with one another to form a complete packaging line. In addition to the advantages mentioned, customers also benefit from a faster planning phase and delivery time as well as lower costs compared to individual solutions.