Abstract: A cutting bit includes a steel body on which a carbide cutting tip is brazed. Disposed rearwardly of a rearwardmost end of the tip, on a tapered side surface of a head of the bit body is an annular ledge which extends laterally outwardly sufficiently far to deflect cuttings laterally away from the bit. The ledge can be formed integrally with the bit body as the result of a machining operation, or the ledge can comprise a split ring that is elastically held in a groove formed in the tapered side surface. The ledge extends perpendicularly to a center axis of the bit, or is inclined slightly forwardly, in order to trap cuttings, such as asphalt, to cause a protective ring of asphalt to be formed in front of the ledge.

Abstract: A cutting bit includes a steel body on which a carbide cutting tip is brazed. Disposed rearwardly of a rearwardmost end of the tip, on a tapered side surface of a head of the bit body is an annular ledge which extends laterally outwardly sufficiently far to deflect cuttings laterally away from the bit. The ledge can be formed integrally with the bit body as the result of a machining operation, or the ledge can comprise a split ring that is elastically held in a groove formed in the tapered side surface. The ledge extends perpendicularly to a center axis of the bit, or is inclined slightly forwardly, in order to trap cuttings, such as asphalt, to cause a protective ring of asphalt to be formed in front of the ledge.

Abstract: A rotatable tool for breaking hard material includes an elongated tool body and a cutting cap mounted on the tool body. The cutting cap includes a generally conical front tip having a maximum first diameter (d), and a rear base portion having an outer peripheral surface defining a maximum second diameter (D). An intermediate portion extends from the tip to the base, and at least a part of the intermediate portion has a concave outer peripheral surface. A longitudinal extent (H) of the cap extends from a front end of the tip to a rear end of the outer peripheral surface of the base. A ratio of d to D is equal to or greater than 0.7. A ratio of H to D is equal to or greater than 1.0.

Abstract: A rotary roof mine bit for drilling holes in the roof of a mine, comprises a bit body and an insert mounted in the bit body. The insert is formed of a hard material such as carbide or diamond. A top surface of the insert comprises two top sections which intersect a respective main surface of the insert to define first and second non-linear cutting edge. In one embodiment each cutting edge comprises a plurality of mutually angled segments. In another embodiment each cutting edge is continuously curved. Preferably an axial notch is disposed at a center of the top surface.

Abstract: A rotary roof mine bit for drilling holes in the roof of a mine, comprises a bit body and an insert mounted in the bit body. The insert is formed of a hard material such as carbide or diamond. A top surface of the insert comprises two top sections which intersect a respective main surface of the insert to define first and second non-linear cutting edge. In one embodiment each cutting edge comprises a plurality of mutually angled segments. In another embodiment each cutting edge is continuously curved. Preferably an axial notch is disposed at a center of the top surface.

Abstract: An insert for use in a roof bit for drilling bolt holes in a mine roof includes a pair of cutting edges interconnected by a chisel edge. Each cutting edge is formed by an intersection of front and side faces of the insert. Each side face further includes at least one chamfer intersecting the respective cutting edge and the chisel edge to divide that cutting edge into inner and outer sections, each of which being sharper than the chisel edge.

Abstract: A roof drill bit for drilling a bolt hole in a mine roof comprises a body defining a longitudinal axis of rotation and having an external periphery and a front face. A longitudinal fluid channel is formed in the external periphery for conducting a flow of flushing fluid to the front face. An imaginary longitudinal plane which contains the axis of rotation serves to bisect the front face into first and second sides. A cutting edge arrangement is defined by at least one cutting insert mounted on the body. The insert is positioned to be acted upon by the flow of flushing fluid. At least one support pad is mounted on the external periphery for balancing cutting forces acting on the drill bit. The cutting arrangement is asymmetrical with respect to the axis of rotation such that the cutting edge arrangement is disposed on one of the sides, and the other side is substantially free of the cutting edge arrangement.