The conventional spherical bearing composed of a metal-race and metal-ball journal for the elevation driving mechanism (EDM) of guns has the seizure problem between the race and ball since it should support high dynamic load at low rotating speed without oil lubrication.
Carbon composite materials are employed in heavy-duty bearings due to their inherent self-lubricating properties and thermal stability. In this work, a composite spherical bearing (CSB) composed of carbon composite race and steel ball is developed to solve the seizure problem of conventional metal-metal spherical bearings for the elevation driving mechanism (EDM) of a future battle tank. In order to eliminate machining and assembling processes of the composite race, it was manufactured with precise compression molding on the ball surface directly. Self-lubricating layer was formed to improve the tribological properties of the inner surface of the composite race. Also the compressive strength of the carbon composite was measured to verify the applicability of the carbon composite spherical bearing to the future battle tank. In addition, the reliability of the composite race of the EDM under dynamic load induced during firing was investigated with respect to environmental temperature and humidity changes. Finally, the bearing clearance and the friction torque of the CSB, which affected the targeting accuracy and the driving force, were measured by a pneumatic bearing tester that could simulate the ball journal oscillation under compressive bearing load.
전차용 주포의 고저구동장치 (Elevation driving mechanism, EDM)에 적용되어온 금속 구면베어링은 무윤활 상태에서 높은 동하중을 받으며 저속으로 회전하기 때문에 융창문제가 발생하였다.
본 연구에서는 자기윤활특성과 우수한 열안정성을 가진 복합재료를 적용하여 융착문제를 해결하였다. 복합재료 외륜의 가공 및 조립공정을 없애기 위해 정밀 압축성형 공정을 이용하여 금속 볼 외면에 일체형을 성형하는 정형성형법 (Net-shape molding process)을 개발하였다. 복합재료 외륜의 내면 윤활특성을 향상시키기 위해 자기 윤활층을 형성하였으며, 베어링 하중을 지지하기 위한 정적 압축강도를 평가하였다. 또한, 사용온도와 흡습환경 하에서 주포 발사시 작용하는 동하중이 복합재료 외륜의 피로강도에 미치는 영향을 연구하였다. 최종적으로 고저구동창치를 모하사는 공압 내구시험기를 제작하였으며, 고저구동장치의 타격정밀도에 영향을 미치는 복합재료 구면베어링의 베어링 유격과 마찰토크를 측정하였다. 개발된 복합재료 구면 베어링은 융착이 없을 뿐만 아니라, 사용중 마찰토크가 낮고 베어링 유격변화가 없어 고정밀 고저구동장치의 핵심부품으로 평가되었다.
