Einfluss der Wellenlauffläche auf das Dichtverhalten von Radial-Wellendichtringen

FKM 1998
Booklet No. 239
Project No. 211

Abstract:

In this study, the influence of differently manufactured shaft running surfaces (WLF) on the sealing behavior of radial shaft seals (RWDR) was investigated. The investigations focused on the conveying behavior of the WLF due to conveying structures and their effects on the sealing quality of the sealing system. Periodic conveying structures were detected by means of topography measurements and evaluation using correlation functions. The tests with RWDRs with neutral conveying properties on the conveying behavior of differently manufactured shaft surfaces showed that the goal of a direct determination of the conveying value of the WLF could not be achieved with these sealing rings. However, the results obtained were of decisive importance with regard to the further procedure in the project. The qualitative conveying behavior of certain manufacturing processes for shaft running surfaces could be identified. Based on the results with the RWDRs with neutral conveying properties, a new method for determining the conveying value of a shaft running surface was developed using commercially available standard RWDRs. In this method, the conveying value of the RWDR is mathematically eliminated in the evaluation and thus the conveying value of the WLF is determined. In tests with hard-turned WLFs, which show a clear conveying structure, results consistent with the expected conveying direction were achieved. Differences in the fineness of the structure are reflected in the level of the conveying value of the WLF. Shaft running surfaces ground in the recess almost always show conveying. This indicates conveying structures on the surface, even if no periodic twist structures can be detected. In the tightness tests, various alternatives to the conventional, groove-ground shaft running surfaces proved to be suitable. Suitable hard-turned shaft surfaces are in principle suitable for sealing with RWDR. WLFs ground in a groove can be controlled in terms of sealing technology despite conveyor structures. In order to understand the mode of operation on the different surfaces and to achieve a reliable production process in terms of sealing technology, further investigations are necessary, particularly with regard to turning. Wear tests with commercially available RWDR show no significant differences on hard and soft shaft surfaces. The manufacturing process of the shaft running surface also has no significant influence on shaft wear. Tests with different abrasive oil additives have shown that the particle size is decisive for shaft wear. Only very small particles that get under the sealing edge during operation become effective there. The aim of the investigations, to determine the change in surface roughness and surface structure in the direction of movement, has not yet been achieved. A measurement technique for detecting and visualizing regular twist structures on shaft surfaces was introduced during the project and pursued further in order to gain additional insights into twist structure detection. The limitations of this method are that only periodic coarse structures can be detected, but not stochastically distributed fine structures. However, these seem to be decisive in terms of effectiveness. The thread method used to date is an unreliable method for detecting twist structures on the shaft. A quantitative statement is hardly possible with it. The objective of the project was achieved. Scope of report:
149 pp., 90 illustrations, 22 plates, 9 references Start of work:
01.05.1996 End of work:
30.06.1998 Funding body:
BMVVi/AIF-Nr.10670 Research center:
Institute for Machine Elements at the University of Stuttgart Head: Prof. Dr.-lng. G. Lechner Project management:
Privatdozent Dr.-lng. habil. W. Haas
Editor and author:
Dipl.-lng. H. Raab Chairman of the working group:
Dr.-lng. D. Frey, Zahnradfabrik Friedrichshafen Chairman of the advisory board:
Prof. Dr.-lng. H. Kipphan, Heidelberger Druckmaschinen AG