Rock-Cutting Tool and Method for Mine and Oil Drilling

Abstract

The invention relates to a rock-cutting tool and a method for manufacturing this tool, which comprises knives comprising a layer of polycrystalline synthetic diamond (PSD), a diamond impregnation layer with diamond particles and bonding cobalt, characterized in that the PSD layer is supported directly, along a planar interface, on the diamond impregnation layer whose interface surface is planar by machining and with which the diamond particles are flush.

1 . A rock-cutting tool with knives ( 3 ) comprising at least one front layer ( 5 ) of polycrystalline synthetic diamond (PSD), a rear diamond impregnation layer ( 6 ) with diamond particles ( 7 ) and bonding cobalt, characterized in that the PSD layer is supported directly, along a planar interface ( 8 ), the diamond impregnation layer whose interface surface ( 8 ) is planar by machining and with which the diamond particles ( 12 ) are flush, and the diamond particles ( 12 ) flush with the impregnation layer ( 6 ) are covalently bonded with the polycrystalline synthetic diamond ( 5 ). 
     
     
         2 . The rock-cutting tool according to  claim 1 , wherein it is provided to alternate diamond impregnation layers ( 61 ,  62 ,  63 ) and PSD layers ( 51 ,  52 ,  53 ). 
     
     
         3 . The rock-cutting tool according to  claim 1 , wherein the diamond particles ( 7 ) of the diamond impregnation layer ( 6 ) are distributed homogeneously and are not in contact with one another. 
     
     
         4 . The rock-cutting tool according to  claim 1 , wherein the diamond impregnation layer ( 6 ) comprises tungsten carbide. 
     
     
         5 . A method for manufacturing a knife of a rock-cutting tool, the method comprising:
 preparing diamond pellets ( 10 ) with a powder ( 9 ) containing tungsten, carbon and cobalt;   preforming a diamond impregnation layer ( 11 ) by cold pressing said diamond pellets ( 10 ) in a mold;   sintering the preformed diamond impregnation layer ( 11 ) to set the diamonds ( 7 );   machining the sintered diamond impregnation layer ( 11 ) until obtaining a planar surface ( 8 ) with flush diamonds ( 12 );   depositing a layer of diamond powder ( 13 ) on said planar surface ( 8 ); and   converting the layer of diamond powder ( 13 ) into a layer of polycrystalline synthetic diamond (PSD) ( 5 ) covalently bonded to said flush diamonds ( 12 ).   
     
     
         6 . The method according to  claim 5 , wherein each pellet ( 10 ) contains only one diamond particle ( 7 ). 
     
     
         7 . The method according to  claim 5  or  6 , wherein the sintering of the diamond impregnation layer ( 11 ) is done by a hot isostatic method. 
     
     
         8 . The method according to  claim 5 , wherein the conversion of the layer of diamond powder ( 13 ) into a PSD layer ( 5 ) is catalyzed by cobalt. 
     
     
         9 . The method according to  claim 5 , wherein the diamond impregnation layer ( 11 ) is machined on several faces until obtaining planar surfaces ( 8 ) with flush diamonds ( 12 ).