牙轮钻头浮动套轴承的机理研究

A STUDY ON THE MECHANIZM OF FLOATING RING BEARING IN A TRICORNE ROCK BIT

由于浮动套轴承的浮动套可以转动,降低了摩擦功率,从而可以提高牙轮钻头的转速。使浮动套转动的主要参数是浮动套的内、外间隙值。根据牙轮钻头轴固定,牙轮转动的工作特点,进行牙轮钻头浮动套轴承单元实验,发现按国内、外现用内小外大的间隙值配置参数,浮动套不会转动。通过对重载低速工况下的牙轮钻头浮动套轴承的润滑状态进行理论分析,得出属于混合润滑或边界润滑状态的结论。并证明全膜润滑状态下的浮动套轴承计算公式,不适用于牙轮钻头浮动套轴承,后者需考虑金属接触及弹性变形的影响,间隙配置应使外间隙远小于内间隙。实验结果与理论分析相一致。本文得出的间隙配置原则,可供牙轮钻头浮动套轴承设计使用。

Floating ring bearing contributes to an increased rotary speed of drill bit, which is the result of reduced friction power loss by the rotation of the floating ring. It is generally believed that the principal parameters are the gaps in the inside and the outside of the floating ring. An experiment of a floating ring bearing unit in a rock bit has been conducted under simulated operating conditions and with the outside gap greater than the inside gap that is commonly used at home and abroad. However, the floating ring was hardly able to rotate. Theoretical analysis of the lubrication state for rock bit under heavy load and low speed has been made in order to find out the suitable gaps. The lubrication state is a mixed or boundary one, so equations of floating ring bearing with full oil film lubrication are not suitable for rock bit′s bearings, and the effect of metal contact and elastic deformation on the surface should be consi-dered. The experimental results agree with theoretical analysis that the outside gap of a floating ring should be much smaller than the inside gap to keep the floating ring rotate satisfactorily. The results can be used in the design of floating ring bearing of a rock bit.