MULTIFLUTE DRILL Russian patent published in 1995 - IPC

FIELD: metal working. SUBSTANCE: drill has cutter plates 9. When cutter plates grow blunt, heat emission from cutting zone is increased and tool temperature rises, with cutter plate most distant from axis of rotation by eccentricity being worn to maximum extent. When washer 5 contacting with annular protrusion 6 of rod 7 is heated to temperature at which memory effect is revealed, its diameter is increased and becomes larger than that of annular protrusion and washer 5 extends beyond annular protrusion 6. Head 2 of drill is axially movable till annular protrusion comes into contact with subsequent washer. Since drill head rotates in eccentric threaded opening, in the process of rotation of head less blunt cutter plates 9 are extended into zone, where worn cutter plate had previously been. As a result self-adjustment occurs. When other washers having higher memory effect temperature interval and positioned in the order of increasing temperature intervals, reveal memory effect, drill head is rotated in similar way. EFFECT: increased efficiency and enhanced reliability in operation. 3 dwg, 1 tbl