METHOD OF MAKING CENTER HOLES Russian patent published in 2019 - IPC B23B35/00 B23B49/04 

FIELD: technological processes.

SUBSTANCE: invention relates to machining of materials by cutting and plastic deformation and can be used in making center holes in parts, for example shafts to be machined at lathes, cylindrical grinding machines, thread grinding machines, spline milling machines and other machines, as well as for rolling rim, rifles, splines on them. Method comprises drilling center holes with carbide centering drills with arc-shaped cutting edges, on which a multilayer wear-resistant coating is applied, and subsequent plastic deformation of working surfaces of holes by polished hard-alloy center with cone angles 59°40'–59°50' and with multilayer wear-resistant coatings.

EFFECT: higher stiffness, coaxiality and durability of center holes.

1 cl, 3 dwg