SEALED BEARING ROLLER CONE BIT HAVING ANTI-PLUGGING DEVICE

摘要

A roller cone drill bit is disclosed which includes a bit body having at lea st one leg depending from the bit body. The leg has a journal formed on its at a lower end. The bit body includes an air channel extending at least from an interior of the bit body to the seal area of the journal. A roller cone is sealingly, rotatably mounted on the journal. The cone has a plurality of cutting elements dispose d on it. The bit includes a backflow valve disposed in the bit body, so that an intake end of the air channel is disposed upstream of the backflow valve. In one embodiment, the backflow valve is disposed in a connection end of the bit body, and the air channel includes a flow tube extending from the air passage in t he bit body to the backflow valve so that its intake end is upstream of the backflo w valve.