DRILL WITH POLYHEDRAL CUTTING TIP Russian patent published in 1999 - IPC

FIELD: metal cutting tool for drilling and boring. SUBSTANCE: drill has elongated body with lengthwise axis. On working end of drill body at least one cutting tip is mounted in seat. Cutting tip has several cutting edges arranged between two abutting cutting angles of tip. At least one cutting edge includes at least one set of buildup cutting edges consisting of two pairs of edges. Each pair includes first and second buildup edges. First buildup edges of both pairs join in common point and they are inclined in such a way that extremity of second buildup cutting edge the most inner relative to above mentioned common point is arranged nearer to tip center than extremity of first buildup cutting edge the most outer relative to said common point. Said extremities are mutually joined by bridge directed to tip center and inclined relative to mean line of tip in such a way that extremity of second buildup cutting edge is arranged nearer to mean line than extremity of first buildup cutting edge. EFFECT: balance of cutting efforts acting upon tool, chip breaking. 30 cl, 18 dwg