DRILL Russian patent published in 2012 - IPC B23B51/02 

FIELD: material treatment.

SUBSTANCE: invention refers to material treatment by cutting and can be used in hole making. The drill has shank and operating part at which chip clearance grooves are made separating body clearance and situated symmetrical to drill axis. The crossing of two main back surfaces of the drill with bottom of chip clearance grooves creates main cutting edges. Drill cutting edge crosses the drill axis and two additional cutting edges are located at the crossing of chip clearance grooves bottoms and edge surface of operating part. Cutting edge crossing the drill axis is located in the projection on plane with normal cross-section of drill axis and parallel to projections on the plane of the main cutting edges and overhang the plane with normal cross-section of drill axis and contacting cup point of main cutting edge, in the direction of drill feed. Ends of main cutting edges situated close to drill axis are cupped in the plane parallel to drill axis.

EFFECT: increase of effectiveness and quality of hole treatment by reduction of axial force by improving drill geometry.

1 dwg, 4 dwg