PREFABRICATED DRILL Russian patent published in 2011 - IPC B23B51/00 

FIELD: technological processes.

SUBSTANCE: drill comprises a body, including a working part and a tail, an axis of symmetry of which matches the drill axis, and two cutting plates of hexagonal shape with three sharp and three blunt angles. The working part has two longitudinal grooves to discharge chips and two seats for installation and fixation of cutting plates, each seat is limited with the lower support wall and side walls, the drill axis crosses one of the seats, the lower support walls of the seats face opposite sides. Each cutting plate has front surface, lower support surface, side support surfaces, arranged between the front surface and the lower support surface, and a central hole arranged between the front and lower support surfaces. At the same time the cutting plate is fixed in the seat by means of a fastening screw passing via its central hole and interacting with a threaded hole coming to the lower support surface of the seat, especially in the fixed position the axis of the fastening screw is displaced from the axis of the hole in the cutting plate. Each cutting plate is installed in the seat with a blunt working angle forward in direction from the drill feed and has a sharp working angle. To increase efficiency due to increased strength of the cutting plate, the lower support surface of each cutting plate is arranged on three ledges made on the cutting plate around sharp angles and limited with side support surfaces of the cutting plate and the convex conical surface, the axis of which is perpendicular to the lower support surface, and the top is arranged at the side of the lower support surface. At the same time in each seat of the working part of the body there is a side support wall in the form of a concave conical surface, designed for interaction with the specified conical support surface of the cutting plate ledge near the working sharp angle, at the side wall of each seat there is a support ledge for interaction with side surface of the cutting plate at the non-working sharp angle, arranged oppositely to the working blunt angle of the cutting plate. At the same time in the seat that crosses with the drill axis, the specified ledge is arranged at the side of the side surface, facing the drill axis, and in the other seat the specified ledge is arranged at the side of the side surface that is turned away from the drill axis.

EFFECT: improved efficiency.

3 cl, 6 dwg