| 摘要 |
<p>The process comprises (i)assembling in sealed manner a rotary milling tool on the shaft of the drill bit so as to include passages and spaces for the lubricant, (ii) evacuating air and gas from these passages and spaces and then filling them with a lubricant, (iii) sealing the lubricant in the passages and spaces and limiting the potential lubricant pressure to a value selected in proportion to the hydrostatic pressure. Pref. the lubricant is also degassed by evacuation before being introduced into the passages and spaces in the drill bit. The presence of air or gas occluded or trapped in the passages and spaces of the drill bit interferes with the lubricating system. This is prevented by the prior evacuation of such air or gases both from the drill bit and from the lubricant itself.</p> |
