국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	TRIBOLOGICAL CHARACTERISTICS OF SOLID-LUBRICATED BALL BEARINGS AT HIGH LOAD CONDITIONS IN A VACUUM
저자	Mineo SUZUKI, Maoto NISHIMURA
Keyword	Ball bearing; MoS2 film; PTFE composite; Vacuum; Space applications
URL	http://send.nal.go.jp/send/jpn/dlpdf.php3/naltr0001389.pdf?id=NALTR0001389
보고서번호	NAL TR-1389
발행년도	1999.08
출처	NAL (National Aerospace Laboratory of Japan)
ABSTRACT	The performance of solid-lubricated ball bearings was examined under high load conditions in vacuum. The bearings had a sputtered MoS2 film on races and balls, and a PTFE-based composite retainer, and demonstrated low frictional torque of about 1.5 N갋cm even at a high load of 3 kN걁the maximum Hertz contact pressure at the inner raceway of 2 Gpa걂갅indicating that they were well lubricated with the sputtered MoS2 film. In some tests, torque spikes of 30 times higher value and with a duration of about 10 sec were observed at intervals of several hundred hours. When the MoS2 film wore out, frictional torque increased dramatically and the bearing temperature also rose to a high level, however the bearings did not seize. The wear life of the MoS2 film decreased drastically as the load increased, however the bearings had a long life of 3?107 revolutions even at the maximum Hertz stress of 2 Gpa at the inner raceway. In the case of the ball bearings without MoS2 film, frictional torque was high, almost of the same level as that of the bearings with MoS2 film after the MoS2 film failure, and the bearing temperature also rose. Again no seizure occurred even after 1400 hours' operation. X-ray Photoelectron Spectroscopy걁XPS걂analyses of the tested balls revealed a metal fluoride on the surface. The fluoride appears to have formed during operation and had a role in the prevention of surface wear and damage. These results suggest that the torque rise observed at the MoS2 film failure was caused by the transition from MoS2-film-lubrication to metal-fluoride-lubrication. The performance of lead-lubricated ball bearings was also examined.?Full ball type bearings without a retainer demonstrated a long life of more than 800 hours at a load of 3 kN, although the torque was 10 times higher than the bearings with a sputtered MoS2 film. It appears that lead-lubricated bearings are also feasible in high load applications.