Author(s)

B. Pinedo, M. Conte, J. Aguirrebeitia & A. Igartua

Abstract

The most common failure mechanism of pneumatic cylinders is related to wear of head seals. It usually occurs due to excessive radial loads or vibrations (dynamic run-out) or as consequence of an incorrect mounting (rod to bore misalignment). Sealing behaviour has been the object of several analytical and numerical studies orientated to reproduce actual working conditions but perfect rod alignment has been often considered. A tri-dimensional quasi-static numerical model of rod radial misalignment and its effect on facing seal behaviour is herein presented as a first step of a study concerning mounting effects on head seal performances. In the specific, a thermoplastic polyurethane (TPU) rod lip seal has been considered. An analytical model was also developed considering the characteristics of the rubber-like material and stiffness variation of the lip seal versus deformation. A non-linear dependence of stiffness on deformation of rubber-like material was found. A cross validation between analytical and numerical models is provided. Keywords: lip seal, rod misalignment, eccentricity, stiffness.

Keywords

lip seal, rod misalignment, eccentricity, stiffness