02.04.18

Well packed

de Man develops palletizing system for ready meals: lasagna, casseroles or currywurst - in the supermarkets, the finished menu dishes for quick meals from the microwave are becoming increasingly popular. In order for the products to be transportable, they first have to be palletized. At Prima Menu GmbH, this happens recently in an automatic palletizing system from de Man from Borgholzhausen. Special features of the project were the enormous range of products to be palletized and the specially developed combination gripper.

Since its foundation in 1995, Prima Menu GmbH has developed into one of the leading providers of high-quality, high-convenience frozen meals. The range includes classics from German and international cuisine as well as vegetarian and vegan products. The family company attaches particular importance to a consistent focus on sustainability. In his plant in Leopoldshöhe, Prima Menu wanted to automate the palletizing of different boxes with finished menu trays. One of the challenges of the project was the enormous range of products: 18 different boxes with a length between 183 and 630 centimeters, a width between 155 and 281 centimeters, a height between 51 and 251 centimeters and a weight between 2.5 and 12 kilograms should be palletized on EURO pallets in the system. The contract was awarded to de Man Automation + Service GmbH & Co. KG from Borgholzhausen, which had already supplied the company with a system for automatic lasagna production in 2011.

Two types of products palletized in parallel
In order to guarantee a speedy palletizing process with the large product variety and quantity and to adhere to the specified cycle times, de Man developed a palletizing system with two infeed roller conveyors, palletizing stations and pallet conveyor lines on both sides of the robot. In this way, two different types of product can be palletized in parallel. The infeed roller conveyors take the boxes from two on-site production lines and convey them into the robot cell. Both roller conveyors are identical in structure and function. Photoelectric sensors installed in segments recognize the position of the products, which are stopped at the end of the roller conveyor by a pneumatically extendable stopper. Now they are removed by the handling robot and stacked on EURO pallets. A Smart-5 NJ4 robot from Comau was used here with a payload of 140 kilograms.

Faster processes thanks to combination grippers
The robot's combination gripper was specially developed for the customer. It combines the performance of the vacuum gripper with that of the mechanical gripper and can handle both the different box sizes and the intermediate layers made of cardboard without any problems. In this way, a time-consuming and therefore costly gripper change is no longer necessary. The boxes are clamped laterally by a tensioning element, the bottom is located on a pivoting support plate. In this way, all cardboard formats can be transported safely. The gripper is divided in the middle and can therefore pick up one or two boxes and place them independently. The intermediate layers are sucked in by rotating the gripper by means of vacuum suction cups on the side. The fill level of the intermediate layer magazine integrated in front of the robot is determined via a light barrier. Built-in control queries also check whether the gripper has been placed on an intermediate layer or a box and whether the box has been gripped correctly.

Pallet conveyor technology lowered
The full pallets are transported out of the robot cell via the pallet roller conveyors and then removed manually with a pallet truck. New empty pallets are placed in the loading areas and conveyed from here to the palletizing positions, where they are positioned by a pneumatically extendable stopper. The pallet conveyor technology has been lowered and runs at a height of 80 millimeters so that the pallets can be removed and loaded by the employees with a pallet truck. The entire system is surrounded by a protective fence, access is via a protective door. Comprehensive safety devices such as several emergency stop buttons and safety light grids ensure optimal protection for employees. The light grids on the pallet roller conveyors are equipped with muting sensors that allow a temporary interruption when the product range is discontinued. The system is operated via a touch panel, in the main view of which a clear, schematic representation of the system enables the operator to quickly access all functions.