KEYWAY BROACH WITH SPECIAL CALIBRATING PART Russian patent published in 2020 - IPC B23D43/00 B23D43/02 

FIELD: methods and devices for metal processing.

SUBSTANCE: invention relates to metal working, in particular, to metal cutting tools: to grooves for machining of key slots in openings of articles made from structural materials, including with high hardness (parts of cars, drilling machines, agricultural equipment, machine building, and so forth). In the design of calibrating part (1) of the drawing tool for machining of key slots in the holes, three teeth (3, 4, 5) with geometrical parameters are additionally introduced, equal to size of calibrating teeth, on side surfaces of which there are small-size chip-splitting grooves (6) located in staggered order relative to each other. Value of lifting on the first additional calibrating tooth shall ensure the value of contact loads within the limits of allowable for the material of the working part of the drawing. Use of ternary row of small-size chip split grooves arranged on side surfaces of three additional teeth, with geometrical parameters, equal to the calibrating teeth size, will ensure the required roughness of the inner base surfaces of the key slot of the hole.

EFFECT: technical result is higher quality of elongated side surface of key slot.

1 cl, 2 dwg