Solid hard metal head for a drill

Abstract

A solid hard metal head for a drill, including two main cutting edges ( 2 ) arranged substantially diametrially opposite each other, and two auxiliary cutting edges ( 3 ) likewise arranged substantially diametrically opposite each other, with associated main cutting edge ( 2 ) and auxiliary cutting edge ( 3 ) form an acute angle (α) there between, and with the auxiliary cutting edges ( 3 ) being arranged, with respect to the rotational direction (ω) of the drill, in front of the respective, associated therewith, main cutting edge ( 2 ).

What is claimed is:  
     
         1 . A solid hard metal head for a drill, comprising two main cutting edges ( 2 ) arranged substantially diametrically opposite each other, and two auxiliary cutting edges ( 3 ) likewise arranged substantially diametrically opposite each other, wherein associated main cutting edge ( 2 )and auxiliary cutting edge ( 3 ) form an acute angle (α) therebetween, and wherein the auxiliary cutting edges ( 3 ) are arranged, with respect to the rotational direction (ω) of the drill, in front of the respective, associated therewith, main cutting edges ( 2 ).  
     
     
         2 . A solid hard metal head according to    claim 1   , wherein the acute angle (α) between the associated main and auxiliary cutting edges ( 2 ;  3 ), which lies in a plane extending transverse to a drill rotational axis, lies in a range between 40 and 90°.  
     
     
         3 . A solid hard metal head according to    claim 1   , wherein a recess ( 4 ;  5 ) is formed between each two adjacent main and auxiliary cutting edges ( 2 ;  3 ) in a circumference of a cross-sectional surface, and wherein the recess ( 4 ;  5 ) has somewhat prismatic shape and extends along an entire axial extent of the head ( 1 ).  
     
     
         4 . A solid hard metal head according to    claim 3   , wherein a portion of a side surface ( 6 ) of the recess ( 5 ), which is arranged, with respect to the rotational direction (ω), in front of a respective auxiliary cutting edge ( 3 ) and extends in an axial direction along the rotational axis (A), has a chamfer ( 7 ) at an end surface of the head ( 8 ).  
     
     
         5 . A solid hard metal head according to    claim 1   , wherein at the tip, the main cutting edge ( 2 ) ends at a chisel edge ( 9 ).  
     
     
         6 . A solid hard metal head according to    claim 1   , wherein the main cutting edges ( 2 ) have, in an axial direction, a slightly concave shape.  
     
     
         7 . A solid hard metal head according to    claim 1   , wherein the auxiliary cutting edges ( 3 ) have, in an axial direction, a pronounced concave shape.  
     
     
         8 . A solid hard metal head according to    claim 1   , wherein an axial spacing of the auxiliary cutting edges ( 3 ) is so selected that a highest point of a generating curve of the auxiliary cutting edges ( 3 ) does not project above an axial generating curve of the main cutting edges.  
     
     
         9 . A solid hard metal head according to    claim 1   , wherein the auxiliary cutting edges ( 3 ) are radially displaced with respect to a generating curve of the main cutting edges ( 2 ).  
     
     
         10 . A solid hard metal head according to    claim 1   , wherein a transitional surface ( 12 ), in a sector between adjacent main and auxiliary cutting edges ( 2 ;  3 ), has a circumferentially concave shape in an axial direction.