Rock core drill bit

Abstract

A core drill bit ( 1 ) for working brittle material has an axially extending tubular shaft ( 2 ) with a rotation driver ( 4 ) coaxially fitted to a trailing end portion ( 3 a ) and a plurality of had material inserts ( 5 a, 5 b ) arranged on the opposite open leading end portion ( 3 b ), which are formed with a defined cutting edge, whereby each individual hard material insert ( 5 a, 5 b ) is fitted on precisely one intermediate carrier members ( 6 a, 6 b ) associated therewith, which is fitted on the leading open end portion ( 3 b ) of the tubular shaft ( 2 ).

What is claimed is:  
     
         1 . A core drill bit for working brittle materials such as rock, concrete and masonry comprises an axially extending tubular shaft ( 2 ) having an open leading end ( 3   b ) and a trailing end ( 3   a ), a coaxial rotation driver secured to the trailing end ( 3   a ) of said tubular shaft ( 2 ) and a plurality of hard material inserts ( 5   a ,  5   b ) arranged on the leading end thereof, said hard material inserts having a defined cutting edge, each of said hard material inserts ( 5   a ,  5   b ) is fitted on a separate intermediate carrier members ( 6   a ,  6   b ) associated therewith, and said intermediate carrier members are fitted to the leading end ( 3   b ) of said tubular shaft.  
     
     
         2 . A core drill bit, as set forth in  claim 1 , wherein said intermediate carrier members ( 6   a ,  6   b ) are formed of a plastically deformable metal.  
     
     
         3 . A core drill bit, as set in  claim 1 , wherein at least two different said intermediate carrier members are secured to said tubular shaft being different in the axial and radial arrangement of said hard materials inserts ( 5   a ,  5   b ).  
     
     
         4 . A core drill bit, as set forth in  claim 1 , wherein the plurality of said intermediate carrier members ( 6   a ,  6   b ) are secured to a completely flat leading end face ( 2   a ) of said tubular shaft.  
     
     
         5 . A core drill bit, as set forth in  claim 1 , wherein a side ( 7 ) of said intermediate carrier members ( 6   a ,  6   b ) mounting said hard material inserts ( 5   a ,  5   b ) is partially concave extending in a rotation direction (R).  
     
     
         6 . A core drill bit, as set forth in  claim 1 , wherein at least one of an axial height (H) and a radial thickness (D) of said intermediate carrier members ( 6   a ,  6   b ) decrease in a direction opposite to a direction of rotation (R) of said core drill bit.  
     
     
         7 . A core drill bit, as set forth in  claim 6 , wherein the radial thickness (D) of said intermediate carrier members ( 6   a ,  6   b ) corresponds substantially to a radial width (B) of the corresponding said hard material inserts ( 5   a ,  5   b ).  
     
     
         8 . A core drill bit, as set forth in  claim 1 , wherein said intermediate carrier members ( 6   a ,  6   b ) are thicker in the radial direction than a radial wall thickness (W) of said tubular shaft to which said intermediate carrier members ( 6   a ,  6   b ) are secured.