Rotary diamond core bit

Abstract

Abstract Described is an improved rotary diamond core bit offering longer life in dry and in chip flush drilling. Grade AAAA dodecahedron diamonds within the range of 18 to 22 diamonds per carat size, each having a select rectangular pyramid point region free of internal flaws and with an included angle of 100* to 120*, are anchored in a bit matrix to project such select point regions outwardly a distance of 0.015 + OR - 0.003 inch from a semiround angular bit face in hard-vector face-set orientation in the rotary cutting direction of the bit and with a negative rake angle of nominally 4- 1/2 *. Such bit-face diamonds are arranged in circumferentially spaced-apart rows extending radially outward and backward with respect to rotary motion of the bit. Such ''''snow-plow'''' linear arrays of bit-face diamonds are disposed on respective discrete similarly snow-plow-oriented land areas or cutting segments of the annular bit face, and chip release face grooves extend from inner to outer diameter of the annular bit face between all cutting segments. The diamonds on the annular segmented cutting face are arranged with the tips of their projecting cutting portions at equal radial intervals of 0.010 + OR - 0.001 inch along concentric line circles. Thirty-seven line circles cover the full annular segmented bit face region, and two diamonds are employed in all but the innermost and outermost line circles, which each have four. Axially extending chip release grooves at the inner and outer diameters of the bit register with opposite ends of the bit-face grooves, and axially extending rows of reaming diamonds continue from opposite ends of the rows of bit-face diamonds. A curvature of 0.050 + OR - 0.005 inch at the intersection of each cutting segment surface and the inner and outer diameter portions of the bit enable proper non-girthexposing anchoring and the 0.015 inch projection of the diamonds in the transition region between the bit-face diamonds and the reaming diamonds at the interior and exterior surfaces of the bit. The axially extending chip release grooves in the outer diameter portion of the bit feed into auger grooves formed in a continuing shank portion of the bit for dry or wet chip removal.

Inventors

• 👤 Walter R Hampe
• 👤 Albert B Simon
• 👤 William H Hampton
• 👤 William E Decker

Bibliographic Details