Sealing structure for a rock drill bit
AssigneeJames Walker & Co. Ltd.
InventorsNigel M. Page, Philip D. Embury
Life of this patent
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Abstract
A sealing structure for a rock drill bit includes an elastomeric diaphragm for installation in the drill bit so as to separate grease from drilling mud. The diaphragm has an aperture extending through it, and a plug is disposed in the aperture so as to form a mechanical seal with a wall of the aperture. The plug has a channel therethrough which is normally held sealed by a face of the aperture in the diaphragm. If the pressure of the grease exceeds pressure in mud on the other side of the diaphragm by more than a critical value, the diaphragm aperture deforms and allows grease to move through the plug channel and escape. The critical value can be varied by using, with the same diaphragm, plugs having different numbers, sizes and axial positions of plug channels.
Claims17
A sealing structure for a rock drill bit, comprising an elastomeric diaphragm for installation in the drill bit so as to separate lubricant from drilling mud, the diaphragm having an aperture therethrough, a plug being disposed in the aperture so as to form a mechanical seal with a wall thereof, the plug having a bore therethrough which is closed by the diaphragm, excess pressure in the lubricant being communicated via the bore to the aperture wall to deform the wall locally and vent the excess pressure.
Dependencies are inferred from the claim text.