Experimental Study on the Design of an Ultra-High Vacuum Differential Rotational Mechanism Based on Dual Rectangular Sealing Rings

To address the operational requirements for ultra-high vacuum (UHV) equipment to achieve a reliable atmospheric-to-UHV transition while enabling 360° continuous and precise rotational motion, a rectangular sealing ring with sharp edges was adopted, and a corresponding rotational differential sealing mechanism was designed herein. Finite element analysis (FEA) software was employed to analyze the surface contact stress of conventional O-rings and the sharp-edged rectangular sealing rings, with a comparison of their rotational resistance under the condition of an equivalent maximum surface contact stress. Furthermore, an experimental system was established to investigate the vacuum sealing performance of single-ring sealing and differential sealing configurations under both static and rotational operating conditions. The results demonstrate that the sharp-edged rectangular sealing ring exhibits superior performance in dynamic sealing applications. Specifically, the rotational resistance of the O-ring is 2.5 times that of the rectangular sealing ring under identical sealing conditions. The leak rate of the single-layer sealing ring is approximately 10⁻⁷ Pa·m³/s, while the double-layer rectangular ring-based differential sealing achieves a leak rate of around 10⁻¹⁰ Pa·m³/s, representing a three-order-of-magnitude reduction compared with the single-layer structure, thus delivering an enhanced sealing effect and improved operational stability.