Influencing Factors Analysis and Experiments of Friction Coefficient between the End Faces for Contact Mechanical Seals

The effects of the working parameters and the surface topography fractal parameters on friction coefficient between the end faces were studied and analyzed by theoretical calculation and experiments for contact mechanical seals. According to friction coefficient fractal model and the mutual coupling relationship between the friction coefficient and the average temperature of the end face, the influencing factors of friction coefficient were analyzed by simulation calculation for B104a-70 mechanical seal. The results indicate that the friction coefficient increased with the increase of spring pressure, and decreased with the increase of sealed medium pressure. When the rotating speed was low, the friction coefficient increased with the increase of the rotating speed, however, the friction coefficient decreased slightly with the increase of the rotating speed after it reached a certain value. The friction coefficient increased with the increase of fractal dimension and with the decrease of characteristic length scale of the soft ring. The smoother the surface was, the bigger the increasing amplitude of friction coefficient was. A series of tests were conducted on the B104a-70 mechanical seal testing device using water (15 ℃) as sealed medium for validating the theoretical results under different spring pressures and sealed medium pressures as well as at various rotating speeds. The results show that the theoretical values of friction coefficient were basically consistent with those by experiments. The maximum relative error was 21.74% when both the rotating speed and sealed medium pressure were low, while the maximum relative error was as low as 5.08% when the rotating speed reached the routine operating speed of 2 900 r/min.