船舶 推進軸系 船尾管 베어링의 强制 壓入 피팅 方式에 관한 硏究

Abstract

The Stern tube bearing, which is used to support the propeller shaft and propeller, is installed on the stern tube and stern boss casting. The size of the propulsion shaft system has been increased by being what ships are being bigger and engine power is being larger. When inserting the stern tube bearing to the stern tube and stern boss casting by using the method of the force pressured fitting, the adequate value of the interference between the stern tube bearing and casting should be considered owing to the slip between the bearing and casting. Therefore, the adequate value of the interference is very important. But the difference value of the interference should be suggested each other to ship builder by the maker. So there is occasionally confusion about the fitting force when the stern tube bearing inserted to the casting in the presence of the ship owner and class surveyor.

In this study, to review and compare the fitting force and the contact pressure, the theory of thick walled cylinder is considered to clarify the formula which received from the maker. Also the fitting force and contact pressure are calculated by using the standard value of interference, Young's modulus, Poisson's ratio & friction coefficient by MATLAB software.

As a result of the simulation, it is grasped that the formula which is used for calculating the fitting force is based on the thick walled cylinder. Also the formula which is offered from Kobelco company is in agreement with the thick walled cylinder exactly. But the formula which is offered from JMT and Blohm+Voss company has been modified as time passed.

Compared to the actual fitting force and the result of the simulation, it is grasped that the actual fitting force is existed on a median point line of the result which is applying the formula of Kobelco and Blohm+Voss. In case of JMT, the actual fitting force is existed on the edge of the result of simulation. Therefore, great care is needed to work the stern tube bearing and casting in case of JMT.