METHOD FOR APPLYING HARDFACING TO A SUBSTRATE AND ITS APPLICATION TO CONSTRUCTION OF MILLED TOOTH DRILL BITS

摘要

A method for applying hardfacing to teeth on a drill bit is disclosed. The method includes applying the hardfacing to at least one of the teeth so as to have a thickness selected to correspond to a position about exterior surface of the tooth. In one embodiment, the hardfacing thickness is increased near the crest of the tooth, and is decreased near the root of the tooth on at least one flank of the tooth. In one embodiment, the thickness is selected by controlling the powder flow rate in a plasma transferred arc welding system. In another embodiment an angle subtended by flanks of the tooth is selected to provide increased strength to the tooth, and the hardfacing is applied to the tooth to cause exterior surfaces of the hardfacing corresponding to the flanks to subtend an angle selected to provide increased penetration of the tooth through earth formations while drilling.