| Abstract [eng] |
The study analyses the literature on robotized incremental sheet forming and 3D printing technologies. The main processes and parameters required for proper progressive sheet forming are identified. The polymer material chosen is glycol-modified polyethylene terephthalate, which has good forming properties when heated to a temperature of 65-75 °C. The aim of the study was to compare parts of the same geometry produced by the two technologies. The parts were printed on a 3D printer and the sheets were printed for robotized incremental sheet forming. The shape of the part is a circular part with a sphere in the middle with a flat bottom. For the robotized incremental sheet forming, the main parameters of the tool steps downwards and towards the center were determined by tests. After printing and forming, experimental studies were carried out to determine the different geometric and strength properties changes in the produced parts. Firstly, a manual dimensional measurement was carried out. It was observed that the geometry of the 3D printed parts is closer to the designed part geometry and the dimensional deviation is lower than that of the parts formed by the robotized incremental sheet forming method. Also, surface roughness measurements have been made on the sphere wall. As the forming tool was in direct contact with the wall area during forming, it was desired to measure whether the roughness differs from the printed part. The result was that the roughness of the printed parts on the sphere wall was several times higher than that of the printed parts. A contour measurement of the sphere wall with a contour graph was carried out. The sphere contour of the 3D printed parts had more pronounced waves than the printed parts. 3D scanning equipment was used to scan the incrementally formed and printed parts for more accurate dimensional results. The scan results show that the 3D printed part geometries are almost identical in shape to the formed part model. Further numerical testing of the model was carried out to observe where the highest stresses are generated in the part when the sphere is loaded. The destructive tests showed that the robotized incremental sheet forming parts were able to withstand loads 2-3 times higher than the printed parts. It was also observed that the 3D printed parts rapidly disintegrated when the maximum load was reached, while the robotized incremental sheet forming parts plastically deformed but did not finally disintegrate. The printed parts were found to be more accurate at the geometry but demonstrated poorer performance in load bearing. Future experiments should be carried out with different forming tools, heating methods and materials to determine the more accurate use of the robotized incremental sheet forming. |
