Detailed Program of the 22nd ISC 2024
Development and Testing of Sleeve-Type Lip Seals with Stamped Back-Pumping Structures
Summary
The Back-Structured Shaft Seal (B3S) was developed to achieve an optimal balance between static and dynamic tightness, thermal and chemical resistance, as well as high reliability and durability for PTFE shaft seals. Structures on the back of the sleeve create an active pumping mechanism in the sealing contact. These structures are designed as indentations, locally influencing the stiffness of the sealing lip. During assembly, the circumferential strain causes flat channels in the contact area. The shape of these channels can be influenced by the geometry of the structures in terms of their shape, depth, and angle. When the shaft rotates, the channels create a pumping effect that actively prevents leakage. The hydrodynamic pressure in the sealing contact increases the structuring, ensuring its effectiveness even as the surface wears.
The structures were optimized for laser engraving. Due to modifications, it is now possible to also produce it by stamping. The geometry was therefore optimized to create a high-quality impression of the negative. Tests on initial variants demonstrated a similar effect to that of the laser-structured variant. During stamping, the outcome is influenced by temperature, force and duration. The stamping process caused alterations to both the material properties and surface of the seal. The identified factors were analyzed by simulation and compared to the laser engraved variant.
Prototypes with varying stamping parameters were produced and underwent both static and dynamic examination on the test bench. The simulation results were validated based on the measurements of the prototypes.
Simulation and experimental investigation demonstrate that the B3S principle can be implemented in a stamped version. However, the design of the structure must take additional influencing factors into account. The stamped variant's unique features allow for further optimization of the seal. In addition, a more efficient production of the B3S can be achieved.