This paper presents typical methods for conducting experimental tests on main shaft slide bearings. There are described their possible testing capabilities, advantages, drawbacks and limitations. Various testing methods were analyzed to find a solution able of providing a wide range of possible investigations at possibly acceptable limitations.
This paper reports on a study of the influence of solid particle contamination on the wear process in water-lubricated slide bearings (steel-acrylonitrile-butadiene rubber (NBR) and steel-polytetrafluoroethylene (PTFE)). To compare the wear of the shaft journal and bushes (NBR and PTFE) when lubricated with fresh water and contaminated water, an experiment was carried out to identify key factors that influence the state of wear of slide bearing. The amount of wear was checked by means of geometric structure measurements on the journals, namely, roughness profile measurements using both a contact profilometer and an optical microscope. The obtained results enabled correlations between the material comprising the sliding sleeve, roughness of the journals and contamination inside the water-lubricated slide bearings.
Water lubricated bearings find increasingly wide application in shipbuilding or the hydropower industry, with the popularity stemming from their numerous advantages. Unfortunately, as it turns out, water lubricated bearings do not always meet expectations, because, on occasion, they become subject to intense, premature wear, which requires costly repair. One of the still unexplained phenomena is the process of excessive bearing wear, in particular, that of shaft journal co-working with rubber bushings. The research goal was to evaluate the influence of shaft bending stress on the degree of its wear. Experimental tests were carried out on a purpose-designed test stand. The results of the first test series confirmed that the shaft bending stresses do have impact on the magnitude of wear.
The excessive wear of a journal shaft can be caused by many factors, for example, working conditions (e.g., temperaturę, slip speed, the type of lubricant), pressure, the type of material used on the bearings and shafts and their roughness, as well as contamination remaining in the system. This paper presents the roughness profiles co-operating with a rubber (NBR) and polytetrafluoroethylene (PTFE) bushes. The conditions of cooperation between the two materials tested in the sliding combination with the stainless steel journal were the same in each pair of bearings (PV); therefore, the comparison of their wear depends only on the material properties of the bush and the deformation of the journal shaft caused by the bending moment. To assess the size of the journal shaft, they were tested using a profilograph. In addition to the journal shaft, bearings were also evaluated, the wear level of which was noticed without the use of specialized equipment.
The issue of excessive wear of shaft journals co-working with a rubber bearing has been unexplained so far. Premature and sometimes very intensive wear of ship sliding bearings in water conditions is the reason for carry out very expensive and more frequent than expected repairs. The authors (E. Piątkowska, W. Litwin) made an attempt to find a case that influences the value of this wear described in the paper “Attempt at Evaluating the Influence of Bending Stress on Shaft Wear Process in Water Lubricated Sliding Bearing with Rubber Bush” (TRIBOLOGY 1/2017). These studies, however, did not explain the dependency of the wear process but showed how to progress further to find the answer to the question about the effect of bending stress on shaft wear. The research is continued on a modified test stand, and their results are presented in this paper. The profilographometer was used to evaluate the wear of the journal shaft. To compare wear intensity, roughness profiles have been 'removed' from the journals both before and after co-operation. They were compared in terms of bending stresses and bending moments.
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