Earth boring bit lubricant chamber barrier member with dispersed fibers

Abstract

An earth boring bit has a body with a depending bearing pin. A cone mounts rotatably on the bearing pin, the cone having cutting elements on its exterior. A lubricant chamber supplies lubricant to the bearing surfaces between the bearing pin and the cone. A barrier in the lubricant chamber has one side exposed to the exterior of the bit for contact by drilling fluid. The barrier member is elastomeric and contains chopped organic polymer fibers. The barrier member may be a seal ring between the cone and bearing pin, or it may be a lubricant compensator.

Description

FIELD OF THE INVENTION [0001] This invention relates in general to earth boring bits, having rotating cones, and in particular to barrier members such as seals for the lubricant system. BACKGROUND OF THE INVENTION [0002] An earth boring bit of the type concerned herein has a body with at least one bearing pin depending from it. Typically, there are three bearing pins, and a cone mounts rotatably to each of the bearing pins. The cones have cutting elements on the exterior that engage the earth formation as the bit body rotates. Drilling fluid pumped from the surface discharges out nozzles of the bit body and returns up the exterior of the drill string along with cuttings. [0003] A lubricant system supplies lubricant to the clearances between the bearing pin and the cone. The lubricant system includes a cavity in the bit body that connects by passages to the clearances between the bearing pin and the cone cavity. Barrier members prevent entry of debris and cuttings into the lubricant....

AI Technical Summary

Benefits of technology

[0008] The bit of this invention is a rotating cone type having a lubricant chamber for supplying lubricant to bearing surfaces between the cone and a bearing pin. The lubricant chamber has at least one barrier with one side exposed to the exterior of the bit for contact by drilling fluid in the well bore. This barrier prevents entry of drilling fluid into the lubricant chamber. The barrier comprises an elastomeric compound containing non-woven, non-cellulose, fibers dispersed therein.

Problems solved by technology

The barrier members, being elastomeric and exposed to drilling fluid, are subject to being cut or torn by drilling cuttings.

In the case of an O-ring seal serving as the barrier member, one side is in dynamic sliding contact, thus is subject to wear.

If worn excessively, drilling fluid can enter.

Tears or cuts on the barrier member can cause drilling fluid to enter.

If the drilling fluid enters the lubricant chamber, the cuttings will damage the bearing surfaces, lubricant will leak out, and the life of the bit will soon be over.

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