Effect of die groove radius on rim roll forming of paperboard cups : a finite element study
Rehman, Abdur (2026)
Diplomityö
2026
School of Energy Systems, Konetekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe20260623101927
https://urn.fi/URN:NBN:fi-fe20260623101927
Tiivistelmä
Paper cups are popular fibre based packaging products which rely on the correct formation of the bottom seal and drinking rim. The use of the thin paperboard wall makes rim roll forming especially critical since it is bent and rolled under a limited area of tool contact. Defects that can occur due to poor forming include split rim rolls, uneven rim diameter and rim opening at the side seam.
The rim roll forming die groove radius and its effect on the deformation behaviour of paperboard cups is studied by finite element analysis in this thesis. The two die geometries from the LUT packaging lab were modelled with nominal board thicknesses of 0.34 mm and 0.38 mm. The original radius of the groove was R = 1.13 mm and the modified radius was R = 2.00 mm for each die. The simulations were performed in ANSYS 2024 R1 Explicit Dynamics using SolidWorks-based geometries, refined meshing near the rim contact region and displacement-controlled boundary conditions.
The results demonstrate that the original radius resulted in undesirable deformations in both the thickness cases. The board with 0.34 mm was found to be deformed with irregular rims and the board with 0.38 mm was found to be deformed down the cup wall. A band of deformation was more continuous and more localised at the rim when the groove radius (R) was increased to R = 2.00 mm. It is therefore proposed that the ratio R/t (groove to board thickness) is a good design criterion and that boards with R/t greater than about 5 show better behaviour.
The study concludes that increasing the groove radius from R = 1.13 mm to R = 2.00 mm is a promising tool modification for improving rim deformation uniformity in the studied cases. The results should be interpreted as comparative simulation trends, and physical production trials are recommended for validation.
The rim roll forming die groove radius and its effect on the deformation behaviour of paperboard cups is studied by finite element analysis in this thesis. The two die geometries from the LUT packaging lab were modelled with nominal board thicknesses of 0.34 mm and 0.38 mm. The original radius of the groove was R = 1.13 mm and the modified radius was R = 2.00 mm for each die. The simulations were performed in ANSYS 2024 R1 Explicit Dynamics using SolidWorks-based geometries, refined meshing near the rim contact region and displacement-controlled boundary conditions.
The results demonstrate that the original radius resulted in undesirable deformations in both the thickness cases. The board with 0.34 mm was found to be deformed with irregular rims and the board with 0.38 mm was found to be deformed down the cup wall. A band of deformation was more continuous and more localised at the rim when the groove radius (R) was increased to R = 2.00 mm. It is therefore proposed that the ratio R/t (groove to board thickness) is a good design criterion and that boards with R/t greater than about 5 show better behaviour.
The study concludes that increasing the groove radius from R = 1.13 mm to R = 2.00 mm is a promising tool modification for improving rim deformation uniformity in the studied cases. The results should be interpreted as comparative simulation trends, and physical production trials are recommended for validation.