Insert spacer assembly

Abstract

A center vacuum rotary drill bit including a rotary drill bit body, an insert and an insert spacer assembly. The rotary drill bit body includes a top working surface having a slot extending transversely across the top working surface. The slot includes a first sidewall, an opposite second sidewall and a generally horizontal bottom surface extending between the first sidewall and the second sidewall. The insert includes a pair of oppositely facing generally parallel side surfaces, a pair of oppositely facing generally parallel end surfaces extending between and interconnecting the side surfaces, a pair of oppositely inclined top surfaces extending between and interconnecting the side and end pairs of surfaces, and a bottom surface extending transversely to and interconnecting the side and end pairs of surfaces. The insert spacer assembly includes a shim and a spacer bar. The shim has a pair of upstanding spaced sidewalls and a bottom wall extending in transverse relation between and integrally connecting the sidewalls. The spacer bar is of a generally parallelogram configuration and has a coefficient of expansion 10 micro in./in./degree C. The insert spacer assembly is interposed between the insert and the slot to elevate the insert with respect to the top working surface of the rotary drill bit body.

Dependencies are inferred from the claim text.