DEEP HOLE DRILLING METHOD Russian patent published in 2010 - IPC B23B41/02 

FIELD: mechanical engineering.

SUBSTANCE: method involves the blank mounting on the machine tool rotary bench, guide holes pre-drilling and deep holes final treatment. To improve accuracy and reduce deep holes drilling labour intensity one arranges a technological boss on the blank whose axis is positioned at equal distance from the blank butt ends; after the blank mounting with the technological boss fitted in the machine tool rotary bench hole the boss axis is aligned with its centre. One first drills a guide hole and then - a deep hole without run from one butt end of the blank. Then the machine tool rotary bench is turned 180° and the drilling operation is repeated. Then the technological boss is cut off.

EFFECT: improved accuracy and reduced deep holes drilling labour intensity.