Abstract: A segmental hard material insert for a working tool has a planar polycrystalline diamond layer (13) having, in its layer plane, a main cutting element (16, 36) and a contact edge (15) located opposite the main cutting element, with the main cutting element (16, 36) having two, facing outwardly, convex cutting sections (17, 27; 37, 47) and a smooth, facing outwardly, concave transitional region (19; 39, 49) connecting the two convex cutting sections (17, 27; 37, 47), and with the apex (20; 40) of the transitional region (19; 39, 47) being located on a central line of the main cutting element (16; 36).

Abstract: A cutting portion structure of a core drill having diamond grains may affect deformation of a tip end portion of a cutting blade after extended use. A core drill A comprises cutting blades 2 formed at an opening end portion 4 of a cylindrical core body 1 and arranged in a circumferential direction of the core body to have gaps 3 between the cutting blades 2. As viewed from a direction substantially perpendicular to a cross-sectional view in a radial direction of the core body 1, the opening end portion 4 has an end face 4A which is rounded without edges, and diamond grains are bound on the opening end portion 4 which is rounded without edges from an inner peripheral side to an outer peripheral side, thereby forming the cutting blades 2.

Abstract: A rotary drag bit including an inverted cone geometry proximate the longitudinal axis thereof is disclosed. The inverted cone region may include a central region, the central region including a plurality of cutting structures affixed thereto and arranged along at least one spiral path. The at least one spiral path may encircle its center of revolution at least once within the inverted cone region. A cone region displacement and a method for manufacturing a rotary drag bit therewith are disclosed. At least one groove may be formed within the cone region displacement along a respective at least one spiral path, the at least one spiral path encircling its center of revolution at least once. A plurality of cutting structures may be placed within the at least one groove and the cone region displacement may be placed within a mold for filling with an infiltratable powder and infiltrating with a hardenable infiltrant.

Abstract: In one aspect of the invention a drill bit assembly has a body portion intermediate a shank portion and a working portion. The working portion has a recess with a side wall which is substantially coaxial with the shank portion. At least one cutting element is attached to the side wall and an indenting member is disposed within the closed end. In another aspect of the invention a method includes providing a drill bit assembly with a recess formed in a working portion of the assembly. The working portion has a plurality of cutting elements and the recess has at least one cutting element. The method further has steps of cutting a formation with the plurality of cutting elements and also of penetrating a conical profile of the formation which is formed by the recess.

Abstract: A core drill having a shank and a cup shaped base metal section constructed of a disk shaped top wall and a cylindrical side wall provided on a fore-end of the shank. A grinding stone portion is mounted on an outer end part of the base metal section, with abrasive grains fixed to the outer end part of the base metal section. Abrasive grain layers are formed in a spiral pattern on inner and outer side surfaces of the cylindrical side wall of the base metal section, with abrasive grains fixed to the inner and outer side surfaces of the cylindrical side wall thereof. When the grinding stone portion is put into rotational contact with a workpiece, the workpiece is ground through to form a circle hole in section leaving a cylindrical core therein.

Abstract: A drill bit including a bit body and a plurality of blades formed in the bit body. The blades are formed, at least in part, from a base matrix material that on one embodiment is impregnated with abrasive particles. One side of the bit is formed, with respect to its axis of rotation, to a smaller radius than the opposite side of the bit. The asymmetry of the bit enables the bit to drill a larger diameter hole than a pass through diameter of the bit. The opposite side defines a contact angle between the bit and a formation. In one embodiment, the contact angle is at least 140 degrees. In one embodiment, a plurality of inserts may be located on the blades to provide gage protection. In another embodiment, the bit may also include a gage sleeve that helps keep the bit stabilized in the wellbore.

Abstract: A drill and/or core tool, in particular for oil drilling and/or coring, comprising a body (2) showing a substantially cylindrical peripheral surface (3) and a front (4), blades (5) which extend from the front (4) till over the peripheral surface (3) and which show each a leading edge (6), possibly PDC cutting elements (7) which are situated at least in a central area (15A) of the front (4) and the longitudinal axes of which are transverse to the rotation axis of the tool (1), and comprising moreover, on at least one blade (5), outside said central area (15A): PDC (7C) and/or secondary (10) cutting elements which show each a cutting edge (8), forming together the leading edge (6) of the blade (5), and the longitudinal axis of which is transverse to the rotation axis, and at least one associated cutting element (10A) which is situated behind at least one of the PDC (7C) or secondary (10) cutting elements, which shows a cross-section of the same shape, at least for its portion protruding from the blade (5), than