Medical cutting instrument

Abstract

A medical cutting instrument which stably exhibits high joint strength obtained by brazing. A cutting instrument (A) is configured by providing a working section ( 2 ) to the front end of a shank section ( 1 ), the working section ( 2 ) consisting of a carbide or a ceramic, the shank section ( 1 ) being constructed from a round stainless steel bar or a round tool steel bar. The shank section ( 1 ) and the working section ( 2 ) are connected through a brazed section ( 3 ). The brazed section ( 3 ) is the portion at which the shank section ( 1 ) and the working section ( 2 ) are brazed together while brazing surfaces, which are provided with protrusion sections formed on the shank section ( 1 ) and/or the working section ( 2 ), are caused to be in contact with each other. The protrusion sections provided on the brazing surfaces each comprise sloped surfaces ( 5 b ) having an apex ( 5 a ), and the height of the sloped surfaces ( 5 b ) is set in the range of 0.5%-8%, inclusive, of the diameter of the brazing surface of the shank section ( 1 ).

1 . A medical cutting instrument comprising a working portion formed of cemented carbide or ceramic at a leading end of a shank portion formed by a round stainless steel bar or a round tool steel bar,
 wherein stainless steel or tool steel forming the shank portion and the cemented carbide or ceramic forming the working portion are bonded to each other through a brazing portion, and the brazing portion is brazed while brazing surfaces, which are provided with protrusion portions formed on one or both of the shank portion and the working portion, are brought into contact with each other.   
     
     
         2 . The medical cutting instrument according to  claim 1 , wherein the protrusion portion provided on the brazing surface is formed as a sloped surface including an apex, and brazing is performed while the apex is in contact with a flat surface or a sloped surface including an apex in a sloped surface including an apex provided on an opposing brazing surface. 
     
     
         3 . The medical cutting instrument according to  claim 2 , wherein the sloped surface including the apex is formed on a brazing surface formed at an edge in an axial direction of the round stainless steel bar or the round tool steel bar forming the shank surface, and a height of the sloped surface is set in a range of 0.5% to 8% of a diameter of the brazing surface of stainless steel or tool steel.