TOOTH LOADING FOR EARTH BORING BITS

摘要

Deformable pads are inserted under the hard metal inserts used to form the earth removing teeth of an earth boring bit. The inserts are typically formed of sintered tungsten carbide, with a cylindrical body beveled at the lower end to facilitate insertion into an interferringly sized drilled hole. The volume of the deformable pad or plate is greater than the remaining voids between the hole, the plate and the assembled insert upon initial assembly. Repetitive loading of the insert during drilling deforms the plate to fill said space to evenly distribute stress between the insert and the wall of its retaining hole. A radius between the corner of the wall and bottom of the hole minimizes stress at this corner.