ANNULAR BIT Russian patent published in 2011 - IPC B23B51/04 

FIELD: technological processes.

SUBSTANCE: annular bit comprises a tubular body part and multiple cutting plates, arranged at the working end of the body part at previously specified intervals in a circumferential direction, besides, at least one of the cutting plates that serves as an inner cutting plate, has configuration designed for treatment of an inner peripheral side section with cutting, and the remaining cutting plates that serve as external cutting plates have configuration designed for treatment of an outer peripheral side section with cutting. At the same time the thickness of the body part in radial direction is arranged as thin with preservation of resistance to deformation in the body part. At the working end of the body part there are through grooves passing through the body part in radial direction so that they open in direction of the side of the working end of the annular bit. At the same time the cutting plates are fixed in appropriate through grooves, besides, each of the cutting plates has a size in circumferential direction, which is equal to the size in circumferential direction of the through groove, and is made in the form of a unit separated from the body part. Chip grooves, every of which has configuration, designed to remove chips arranged in direction of rotation in front of the cutting plates, besides, every of which is formed by a part of the outer peripheral surface of the body part and has a truncated bent surface, arranged so that the external peripheral surface approaches the inner peripheral surface of the body part, when the outer peripheral surface passes in direction of the working end of the body part. At the same time the cutting plates are arranged in appropriate through grooves so that the end of the section internal in radial direction that is front in axial direction of the end of each of the cutting plates matches or substantially matches the section of the end of the chip groove of radial direction that is front in the axial direction, and configuration, in which the end of the section of radial direction that is inner in axial direction of the end of the cutting plate matches or substantially matches the section of the section end of the chip groove that is front in axial direction, is realised so that the connecting section in circumferential direction between the section of the end of the chip groove that is front in the axial direction and the cutting plate is bent or curved in radial direction so that is corresponds to the position of the cutting plate end that is inner in radial direction.

EFFECT: improved efficiency of annular drilling.

7 cl, 12 dwg