Étude expérimentale et analyse par éléments finis du couple de dévissage des capsules serties sur un contour fileté

Abstract

In the containers also known as «filled closed», the cap removal torque and the sealing of the contents appear to be two crucial criteria in the closing quality, and the consumer perceives these two parameters as being the guarantee of the packaging integrity. This work deals with the experimental study and the finite element analysis of the crown cap removal torque of a beer glass bottle. In order to carry out an in-depth study of the parameters influencing the cap removal torque (twist-off torque), several experiments and simulations were run during this project. A testbench was designed and developed to make it possible to measure the coefficient of static friction (SFC) at the interface liner-glass, the sliding torque of a loose cap pressed on the bottleneck and the removal torque of a crimped cap. In order to characterize the liner, compression tests on elastomer samples in lubricated and dry conditions were run. 24-hour creep tests on some samples were also conducted at various temperatures in a climatic test chamber. The numerical investigation based on the finite element analysis (FEA) was made possible using the commercial softwares «Ansys®». All the tests carried out were numerically reproduced using the FEA in order to recheck the validity of the material properties and the reliability of the models. The sliding torque of a loose cap assembled on the bottleneck was measured in laboratory and also reproduced with the FEA. Thereafter, the three-dimensional modeling of the cap crimping process made possible the determination of the cap removal torque. The modeling of the crimping process is in excellent agreement with the experiment. Then the contribution of the elastomer liner and the threading in the overall removal torque was computed. For example the torque due to the thread accounts for 27% and 33% of the total removal torque, at temperatures of 22°C and 37°C respectively. The correlation of the experimental results with the experiment shows that the numerical model is now reliable, and it is possible to predict the crown cap removal torque according to the multiple parameters of the process, like the pressure applied by the plunger on the cap, the geometry of the cap and the capping tool, the material properties, etc. Finally, the finite element model highlights that the increase of the internal pressure in the assembly reduces the crown cap removal torque.

Date	12 Jan 2010
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Henri Champliaud (Supervisor) & Van Ngan Lê (Co-supervisor)