Diamond drills

Claim 2

A diamond drill bit assembly comprising a diamond drill bit having an annular cutting portion at the front end thereof and a cylindrical shank extending rearwardly therefrom and having a lead portion adjoining and of a diameter less than said cutting portion and a screw-threaded trailing portion of further reduced diameter engageable with a reaming shell; and a guide sleeve formed of wear resistant material dimensioned to be received upon said trailing portion and be held thereon during operation by the forward end of said reaming shell in screw-threaded engagement with said trailing portion, retainer means in said shank cooperating with said guide sleeve to prevent rotation thereof relative to said shank, said guide sleeve having an outer diameter which is of the order of from about one one-thousandth of an inch to about ten one-thousandths of an inch less than the outer diameter of said annular cutting portion.

Claim 3

A diamond drill bit as defined in claim 1 wherein means are provided establishing communication for circulation of water between the interior of the bit and the exterior of the bit immediately behind said annular cutting portion.

Claim 4

A diamond drill bit assembly as defined in claim 1 wherein reaming shell has a screw-threaded lead portion engageable with said diamond drill bit and a screw-threaded trailing portion of reduced diameter engageable with a core rod; a reaming sleeve having an outwardly facing cylindrical cutting face, said reaming sleeve being engageable upon said trailing portion of the reaming shell at the forward end thereof; retaining means in said reaming shell co-operating with said reaming sleeve to prevent relative rotation thereof; and a second guide sleeve engageable upon said trailing portion of the reaming shell behind said reaming sleeve whereby said reaming sleeve and said second guide sleeve may be secured in position on said trailing portion by the forward end of a core rod screw-threadably connected with said trailing portion of the reaming shell, the outer diameter of said second sleeve guide being of the order of from about one one-thousandth of an inch to about ten one-thoUsandths of an inch less than the outer diameter of said reaming sleeve.

Claim 5

A diamond drill bit assembly as defined in claim 3 wherein said guide sleeve on said bit, said reaming sleeve, and said second guide sleeve are provided with spiral grooves in the outer surfaces thereof having a pitch direction which is the same as the direction of rotation of said diamond drill bit assembly during operation thereof.

Claim 6

A diamond drill bit assembly as defined in claim 3 wherein said guide sleeve on said bit, said reaming sleeve, and said second guide sleeve are provided with spiral grooves in the outer surfaces thereof having a pitch direction which is the same as the direction of rotation of said diamond drill bit assembly during operation thereof and wherein said drill bit assembly is screw-threadably mounted at the forward end of a drill string comprising sections of core bar having a plurality of spiral grooves in the outer surface thereof having a pitch direction which is the same as the direction of rotation of said diamond drill bit assembly during operation thereof.

Claim 7

A diamond drill bit assembly as defined in claim 5 wherein the ends of all components on which there are spiral grooves are circumferentially cut away to slightly reduced diameter to provide a space for circumferential flow of water.

Claim 8

A diamond drill bit assembly as defined in claim 5 wherein said spiral grooves are 1/64 inch deep and 3/16 inch wide.

Claim 9

A diamond drill bit assembly as defined in claim 1, wherein said annular cutting portion and said guide sleeve define spiral grooves in their outer cylindrical surfaces said grooves having a pitch direction which corresponds to the direction of rotation of said drill bit assembly in operation.

Claim 10

A diamond drill bit assembly as defined in claim 8 further comprising a reamer sleeve carried on said reaming shell and a second guide sleeve formed of wear resistant material carried on and fixed to rotate with said reaming shell immediately axially behind said reamer sleeve and having an outer diameter which is of the order of from about one one-thousandth of an inch to about ten one-thousandth of an inch to about ten one-thousandth of an inch less than the outer diameter of said reamer sleeve.

Claim 11

A diamond drill bit assembly as defined in claim 9 wherein the outer cylindrical surfaces of said reamer sleeve and said second guide sleeve define spiral grooves having a pitch direction the same as that of said spiral grooves on said annular cutting portion and said first-mentioned guide sleeve.