Effect of vulcanization on deformation behavior of rubber seals: Thermal–mechanical–chemical coupling model, numerical studies, and experimental validation

Abstract

Vulcanization molding has a significant impact on dimensional changes of rubber seals. Numerical analysis of this process can improve dimensional accuracy of molded sealing products. In this study, a stress–strain relationship model that considers thermal expansion, cold contraction, and shrinkage caused by a crosslinking reaction under the constraint of a mold boundary was established, a transient analysis method for thermal–mechanical–chemical coupling of the process from rubber seal vulcanization to mold opening was developed, and dimensional changes of the rubber seal in the mold and after cooling were predicted. Results calculated by the model were verified by the production of typical seals. The influences of vulcanization process parameters on changes in molded seal size were numerically analyzed. The numerical results showed that the dimensional shrinkage ratio increased nonlinearly from 3.2 % to 3.8 % when the vulcanization temperature increased from 165 to 185 °C, i.e., an increase of 0.206 % for every 1 % increase in shrinkage caused by the vulcanization reaction. These research results can be utilized in the design of vulcanization molds for high-precision rubber seals.