Hard material bit

Abstract

A hard material bit for a drilling head ( 2 ) includes at least two cutting edges ( 4 a , 4 b ) over a bit length (L) in a direction transverse to a bit drilling axis (A), with one of the at least two cutting edges ( 4 a ) being located adjacent to a first side surface ( 5 a ) of the bit and another of the at least two cutting edges being located adjacent to the second side surface ( 5 b ) of the bit spaced form the first side surface ( 5 a ) by a thickness (D), the bit further including a base surface ( 6 ) located opposite the cutting edges ( 4 a , 4 b ) at a height (H) along the drilling axis (A), and two recesses ( 7 a , 7 b ) formed in respective longitudinal portions of the base surface ( 6 ) located opposite the one and the another of the at least two cutting edges ( 4 a , 4 b ), respectively, and extending up to the first and second side surfaces ( 5 a , 5 b ), respectively.

1 . A hard material bit for a drilling head ( 2 ), comprising at least two cutting edges ( 4   a ,  4   b ) over a bit length (L) in a direction transverse to a bit drilling axis (A); a first side surface ( 5   a ) and a second side surface ( 5   b ) spaced from the first side surface ( 5   a ) by a thickness (D), one of the at least two cutting edges ( 4   a ) being located adjacent to the first side surface ( 5   a ) and another of the at least two cutting edges being located adjacent to the second side surface ( 5   b ); a base surface ( 6 ) located opposite the cutting edges ( 4   a ,  4   b ) at a height (H) along the drilling axis (A); and two recesses ( 7   a ,  7   b ) formed in respective longitudinal portions of the base surface ( 6 ) located opposite the one of the at least two cutting edges ( 4   a ) and the another of the at least two cutting edges ( 4   b ), respectively, and extending up to the first and second side surfaces ( 5   a ,  5   b ), respectively, which is close to the cutting edge ( 4   a ,  4   b ).  
   
   
       2 . A hard material bit according to  claim 1 , wherein the one and another cutting edges ( 4   a ,  4   b ) are formed directly on the first and second side surfaces ( 5   a ,  5   b ), respectively.  
   
   
       3 . A hard material bit according to  claim 1 , wherein a recess volume (VA) amounts to between a half and a double of a cutting edge volume (VS).  
   
   
       4 . A hard material bit according to  claim 1 , wherein a cross-section across a middle portion of each of the at least two cutting edges ( 4   a ,  4   b ) has a shape of essentially a parallelogram.  
   
   
       5 . A hard material bit according to  claim 1 , wherein both the thickness (D) and the height (H) amount to less than a third of the length (L).  
   
   
       6 . A hard material bit according to  claim 1 , wherein the base surface ( 6 ) is formed over the length (L) as a concave surface.  
   
   
       7 . A hard material bit according to  claim 1 , wherein each of the two recesses ( 7   a ,  7   b ) is limited in a longitudinal direction thereof at opposite sides thereof.