Abstract

The seal failure of an elastomer rotary shaft seal is often caused due to lead on the shaft counterface. In sealing technology, the term ‘lead’ includes all structures on sealing counterfaces that are capable of transporting fluid in axial direction through the sealing contact and thus disrupting the sealing mechanism. Lead structures are created during the manufacturing process of the shaft surface or throughout the handling. They occur in various shapes and sizes. Depending on the characteristics of the lead structures, several specialized measurement and evaluation methods exist which have to be applied in combination. However, not all types of lead can be covered with the methods known so far. State of the art are frequency-based and model-based analysis methods, which are only able to detect periodic lead structures. Aperiodic and stochastically distributed lead structures cannot be detected due to the functional principle. This article provides an approach for a structure-based evaluation of macroscopic lead structures based on optical topography measurement data. This allows to detect all known types of macroscopic lead on the shaft surface and in future to measure microscopic and macroscopic lead with a single measurement procedure.

Highlights

  • Elastomer rotary shaft seals are widely used to seal the passage of a rotating shaft and a housing

  • The dynamic leak tightness of the sealing system is due to the formation of an active back-pumping effect of the rotary shaft seal

  • The fluid in the sealing gap is constantly exchanged with fluid in the housing because of the back-pumping effect

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Summary

Introduction

Elastomer rotary shaft seals are widely used to seal the passage of a rotating shaft and a housing. Macroscopic lead structures which are classified in terms of size between the micro lead and regular waviness on sealing counterfaces, are located in the topography resulting from Gaussian low-pass filtering. They are created during manufacture by transferring and superimposing the contour of the grinding wheel or other tools to the shaft surface [8]. One type of macroscopic surface structures occurs axially periodically These structures circulate the shaft continuously in circumferential direction and are known as macro lead. The loss of information between each measurement leads to a resolution in circumferential direction that is determined by the shaft diameter It is significantly lower than the resolution in axial direction. This requires a trained expert to interpret the evaluation results

Structure-based lead analysis based on optical measurement data
Surface segmentation À watershed transformation and basic considerations
New procedure for the reduction of over-segmentation
Results and analysis
Conclusion
International Organization for Standardization
11. Mercedes-Benz

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