Abstract: A tool holder fixing structure is arranged to fix a tool holder for holding a tool attached with a throwaway tip to a tool-holder holding part of a machine tool so that a foreign-matter receiving clearance is provided between the tool holder and the tool-holder holding part. The foreign-matter receiving clearance is defined in a range of +30° to ?30° from a cutting-edge position of the throwaway tip assumed as an original point and in a range of 150° to 210° from the original point, respectively.

Abstract: A tool holder fixing structure is arranged to fix a tool holder for holding a tool attached with a throwaway tip to a tool-holder holding part of a machine tool so that a foreign-matter receiving clearance is provided between the tool holder and the tool-holder holding part. The foreign-matter receiving clearance is defined in a range of +30° to ?30° from a cutting-edge position of the throwaway tip assumed as an original point and in a range of 150° to 210° from the original point, respectively.

Abstract: A drill including a cutter member and a shank which are formed separately from each other and fixed to each other for rotation as a unit, wherein the shank has an engaging groove formed in a distal end face thereof such that the engaging groove extends in an axial direction of the shank and is aligned with a center of the distal end face, and the cutter member consists of a rectangular plate including a proximal end portion fixed to the shank by engagement thereof with the engaging groove, and a distal end portion which is remote from the shank and which has at least one cutting edge.

Abstract: A burnishing drill includes a cylindrical shank and a drill body connected to the shank. Drilling edges, first reaming edges and second reaming edges are formed on a first reduced diameter portion, a second reduced-diameter portion and a third reduced-diameter portion respectively located at a foremost end of the drill body. Each of the reaming edges is inclined with respect to the longitudinal axis of the drill at an angle which is set so as to be within a range of between 5.degree. and 30.degree.. During a boring operation using the drill, a hole is drilled by the drilling edges and the drilled hole is then worked by the first reaming edges and the second reaming edges to provide a smooth inner wall in the drilled hole. Since each of the reaming edges is formed to extend radially outward from the foremost end of the drill and incline axially in the rearward direction at a relatively small angle, the centering property can be greatly improved.

Abstract: A burnishing drill includes a cylindrical shank and a drill body connected to the shank. Drilling edges, reaming faces and reaming edges are formed on a first reduced-diameter portion, a second reduced-diameter portion and a third reduced-diameter portion located at a foremost end of the drill body respectively. The reaming faces which are located axially at backward positions of the drilling edges and the reaming edges extend radially outward from the foremost end of the drill and incline axially in the rearward direction, and also extend radially outward and incline in the rearward direction with respect of the rotational direction. Since an inner surface of the hole drilled and reamed by the drilling edges and the reaming edges can be further smoothed by the reaming faces, the surface roughness of the finished hole can be much improved.

Abstract: A high speed burnishing drill having drilling edges and reaming edges provided at the forward end of a cylindrical drilling body. The drilling edges are inclined diametrically from the center of the forward end to the axially rearward direction, while the outermost peripheral wall of the drilling edges are on a reduced-diameter portion of the maximum external diameter of the drill body. The reaming edges extend from the plane intersecting the drilling edges radially from a position inward of the outermost peripheral of the drilling edges, outwards, so as to incline axially in the forward direction with a second cutting angle. A reduced diameter portion extends axially backward from the outermost peripheral wall of the drilling edges. An enlarged-diameter guide face extends axially from a slope behind the corresponding drilling edge in the rotational direction, and the forwardmost end of the enlarged guide face is located axially behind the corresponding reaming edge.

Abstract: A burnishing drill includes a cylindrical drill body connected at its forward end integrally with a shank. The forward end of the drill body includes a first pair of cutting edges inclined radially and rearwardly from the forwardmost central end of the drill body toward the shank at a first cutting angle. A second pair of cutting edges formed of diamond chips are disposed in a plane intersecting the plane in which the first pair of cutting edges are located. The second pair of cutting edges are inclined radially and rearwardly from a position inside a circle including the maximum external margins of the first pair of cutting edges toward the shank at a second cutting angle.

Abstract: A burnishing drill having a drill body, the forward end of which is formed with a reduced-diameter portion having its external diameter smaller than the maximum external diameter of the drill body. The forward end of the drill body includes a pair of first cutting edges formed in the reduced-diameter to include with a first cutting angle, and a pair of second cutting edges formed to extend radially in a direction perpendicular to the first cutting edges at least from the inward position of a plane including the outermost peripheral walls of the first cutting edges to the position of another plane including the outermost peripheral wall of the drill body.Each of the first cutting edges extends radially outward from the center of the forward end of the dril body and includes axially in the rearward direction while each of the second cutting edges inclines extends radially outward from the drill body and inclines axially in the forward direction.