Sf50 steel is enough for oil pump
bearings as far as non-corrosive conveying medium is concerned. But when the jacket and green silver impeller are used, corrosion resistant materials or at least rust resistant materials are often used to manufacture the pump shaft. In multistage pumps, this measure is easy to see, because in order to maintain the relative distance between the impeller, the sleeve must be installed on the sleeve, and the material must also protect the pump shaft. The material in the stuffing box will gradually wear the pump shaft, which is often shown as a deep groove. As the groove picks gradually increase, the stuffing box loses its tightness. If the casing at both ends of the filling selenium has a screw shoulder, the whole impeller can be tightened on the pump shaft. Therefore, the rotation direction of leisure lines should be chosen properly, so as not to relax and loose.
If the conveying liquid contains gas or seals that do not perfectly protect the pump sleeve, the whole pump shaft shall be made of a foot corrosion resistant material. Stainless chromium steel is reliable in this respect.
Determine the size of the collar taking into account the critical speed
When determining the size of an oil pump bearing, the following three points must usually be taken as standards.
1. The pump shaft must display the required strength characteristics.
2. The elastic deflection of the co-check impeller shall not exceed a consistent value determined by experience.
S. An unsteady operating condition with the so-called critical speed characteristic cannot enter the normal circle of the original operation or its vicinity.
If the latter condition is satisfied, then in most cases both requirements 1 and 2 are fulfilled. Therefore, we are limited here to solving the critical speed position of the pump shaft whose dimensions have been given in advance
Critical speed
In order to illustrate the nature of critical speed expansion, we first examine a pump shaft conceived as a massless vertical, mass and uniform disk is fixed on the pump shaft, so that the eccentricity of point P through the pump shaft and the center of gravity S is. Because of the centrifugal force when rotating, the deflection of the pump shaft is Y, and the disk can only move in parallel.
