한국윤활학회:학술대회논문집 (Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference)
- 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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- Pages.289-290
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- 2002
THERMAL FRICTION TORQUE CHARACTERISTICS OF STAINLESS BALL BEARINGS
- Lee, Jae-Seon (Mechanical Systems Development Department, Korea Atomic Energy Research Institute) ;
- Kim, Ji-Ho (Mechanical Systems Development Department, Korea Atomic Energy Research Institute) ;
- Kim, Jong-In (Mechanical Systems Development Department, Korea Atomic Energy Research Institute)
- 발행 : 2002.10.21
초록
Stainless steel ball bearings are used in the control element drive mechanism and driving mechanisms such as step motor and gear boxes for the integral nuclear reactor, SMART. The bearings operate in pressurized pure water (primary coolant) at high temperature and should be lubricated with only this water because it is impossible to supply greases or any additional lubricant since the whole nuclear rector system should be perfectly sealed and the coolant cannot contain ingredients for bearing lubrication. Temperature of water changes from room temperature to about 120 degree Celsius and pressure rises up to 15MPa in the nuclear reactor. It can be anticipated that the frictional characteristics of the ball bearings changes according to the operating conditions, however little data are available in the literature. It is found that friction coefficient of 440C stainless steel itself does not change sharply according to temperature variation from the former research, and the friction coefficient is about 0.45 at low speed range. In this research frictional characteristics of the assembled ball bearings are investigated. A special tribometer is used to simulate the axial loading and the bearing operating conditions, temperature and pressure in the driving mechanism in the nuclear reactor. Highly purified water is used as lubricant ‘ and the water is heated up to 120 degree Celsius and pressurized to 15MPa. Friction force is monitored by the torque transducer.