부산대학교 도서관

This paper describes a seal and seal shield assembly for a rotary drill bit of the type comprising: a main bit body having at least one leg extending downwardly therefrom the leg having a generally cylindrical journal extending radially inward therefrom comprising a first bearing member of the bit, the journal having end bearing surface on the surface of the leg at the juncture of the journal therewith, a hollow roller cutter with an open end rotatably mounted on each journal, having a bore forming a bearing surface cooperable with the journal, and having a counterbore at the open end thereof defining an annular seal cavity in cooperation with the peripheral surface of the journal and the journal end bearing surface with a peripheral opening therefrom. The annular seal cavity has a fixed end wall comprising the journal end bearing surface, a journal end wall on the roller cutter spaced from the journal end bearing surface and movable relative thereto, a fixed side wall comprising the peripheral surface of the journal, and a side wall on the roller cutter spaced from the journal peripheral surface and movable relative thereto, and means for introducing lubricant into the space between the hollow cutter and the journal.