Development of Method and Device for Roller Surface Geometry Measurements

Sammanfattning

This project was carried out in cooperation with Swedish packaging company Tetra Pak Packaging Solutions AB. Their main purpose is to develop the packaging material, process, and machine lines needed to produce the laminate, which is a multi-layered material typically made by combining paper, plastic, and aluminum to create a strong, protective barrier for liquid food packaging. In order to create the laminate, the rollers of the packaging machine must be in good condition. The profile dimensions of the nip rollers, which apply pressure to bond multiple layers of material, are especially important to maintain the performance of the machine. The nip roller works together with a chill roller to create even pressure distribution in the nip, where the layers adhere to each other. Adhesion is necessary for the quality of the paper laminate. Previously, at Tetra Pak’s Factories, the nip rollers have been measured using the current roller profile measuring devices (referred to here as CRPMD-calipers), which is slid along the rollers in cross direction – perpendicular to the machine line direction. However, Tetra Pak has decided to explore other methods to improve the features and functionality of the current measuring method by developing a new concept for a measuring device. This degree project covers the development process of creating a new measuring tool. The project focuses on the new measuring device’s mechanical design, and laser position to get desired accuracy of the measurements. It covers simulation of various concepts to get accurate readings, an assessment of measurement performance at different laser positions and application of different circle fitting algorithms for the use of a Triangulating Line Laser. Test results from the concepts show that the current measuring device still has better measurement accuracy, and that further development of the existing concepts or exploration of new methods is needed. The project also explores reasons for the new concepts’ performance shortcomings and leverages this information to suggest next development steps and different approaches for future development. The project is based on an interpretation of the product development process described by Ulrich and Eppinger, following the steps from information gathering to concept selection. The project began with a clear mission statement and some initial concepts already formulated. The work resulted in an evaluation of the concepts and identified opportunities for further development in relation to the goals set by the project description. Keywords: product development, roller, measurement, crowning, circle fit