BIT (VERSIONS) Russian patent published in 2010 - IPC B23B51/00 

FIELD: process engineering.

SUBSTANCE: proposed borer comprises body with chips escape flute and shank. Cutting plate and central element comprising cutting head and tail part are arranged and secured on aforesaid body, said central element being fitted in the body bore with its axis aligned with the borer lengthwise axis. To facilitate machining, borer is furnished with a support arranged in aforesaid body bore and rigidly jointed therewith. Note here that said central element can axially displace and revolve in the body bore in machining together with cutting head representing a right pyramid with axis of symmetry aligned with the borer lengthwise axis. Note also that central element tail part end face has radial ledges that fair smoothly with separating recesses to interact with mating recesses and ledges made on the support end face that faces said central element. In compliance with one version, pyramid base is displaced towards shank with respect to lengthwise apex of at least one cutting plate, while, in compliance with another version, said pyramid base is displaced in direction from shank with respect to closer cutting plate apex lengthwise axis.

EFFECT: improved machining conditions.

2 cl, 9 dwg