Rotary drill bit with one-piece washer feature

Abstract

[0068] A drill bit comprising a drill bit body and a shank extending from a bottom of the drill bit body. The drill bit body includes a one-piece washer section extending to a rear annular flange. The rear annular flange includes an undercut designed to reduce heat transfer to the front end of the drill bit shank, thereby preventing a reduction in the hardness of the front end of the shank when a drill bit tip insert is brazed to the front end of the drill bit. The drill bit shank may include a segment with an increased diameter adjacent to a front end of the shank, designed to enhance the load-bearing and impact characteristics of the drill bit.The drill bit includes a holder that surrounds the shank, ensuring the drill bit is securely mounted in the holder's bore while still allowing it to rotate freely within the holder's bore. The drill bit can be manufactured in a one- or two-stage process. In the two-stage process: (1) the drill bit body is separately hardened and tempered; and (2) the carbide tip is then brazed to the front end of the drill bit body. Alternatively, in the one-stage manufacturing process, the drill bit body is heat-treated simultaneously with the brazing of the carbide tip to the front end of the drill bit body.