高速度軸承の潤滑と之に使用する油の性状

抄録

Regarding the lubrication of journals there are various experiments already published, since Dr.Osborne Reynolds' theory is announced but they are not applicable directly to the modern high speed journals, for the journals today are running at the higher speed and under the greater load than the journals of that time. And the lubricating oil needs special study with respect to the effect of the emussion or the fuming. The conclusion of the experiments obtaind up-to-date is as follows : -(a) In the high speed journals the moving condition of the axis of the shaft is quite different to those published heretofor ; therefore the theory of lubrication also should be modified. (b) Pressure of oil film is generally high at the lower part of the journal and vacuum at the upper part ; and it differs according to the load, the peripheral speed, the amount of clearance, the kind of oil used, the injecting pressure and the temperature of oil ; and the clearance affects the most of all. (c) Designing the journals, the continuance of oil film should be considerd chiefly ; thus, former emperical formula PV=K must be corrected. P=Pressure on bearing. V=Peripheral speed. K=Constant. (d) Oil clearance is sufficient if there is a room enough to let the lubricating oil enter between the shaft and the bearing, making perfect oil film and carrying away the heat generated by the friction, to keep the temperature that the journal and oil will stand ; but the thickness of the oil film is about one thousandth inch to three thousandth inch, therefor, the cooling area is only necessary to take in consideration. In view of this it is not necessary to take a large clearance as used to. Moreover, making the small clearance smooth running is obtained and even synclonized with the vibration of turbine the effect is less. (e) At the boring of the turbine casing, the moving condition of the shaft in the journal should be take in account and it is desirable to make equal clearance of the blade tips in the running condition. (f) Following changes occur in the lubricating oil while in use and its life decrease gradually. (1) Color of the oil gradually change to dark red. (2) Specific gravity gradually increase. (3) Viscosity increase. (4) Demulsility decrease. (5) Acid increase. (g) The using temperature of the journals are differ by the oil used but commonly about 140°F. is desirable. (h) On the theory of oilness I approve of Mr.H.S. Allens view. (i) Admitted that the pittings on the face of the reduction gear teeth of all geared turbine, now discussed is mainly coused by the breaking-down of the oil film. (j) Specification for lubricating oil of the geared turbine in the vessels and ideal system of the lubrication for the vessels are determined. (stated at the last part of the paper)(k) Used oil may be recreated by washing of water and filtering by Fular's earth. From the economical point of view, this provision is absolutely necessary without regrd to the vessel or the land shop ; especially in this country where the lubricating oil is lacking.