Multi-Edge Working Surfaces for Polycrystalline Diamond Cutting Elements

Abstract

A polycrystalline diamond cutting element for earth boring drill bits presents at least three regions of different abrasion resistance to the earthen formation when in operation. The cutting element has an end working surface and the regions, which are substantially free of catalyzing material, form a series of at least three layers. In operation, these layers wear at different rates causing a series of protruding lips. The end working surface may be substantially planar or frusto-conical in form.

1 . A cutting element for an earth boring drill bit comprising a facing table of a polycrystalline diamond material integrally bonded to a tungsten carbide substrate, the facing table comprising a generally planar, generally circular end working surface, and a generally cylindrical peripheral working surface,
 the polycrystalline diamond material comprising layers of differing diamond constituency, arranged one adjacent the other to form a multiple of discreet layers;   wherein in operation an outermost, first layer is exposed at the end working surface and a least a plurality of the other layers are exposed at the cylindrical peripheral working surface such that at least three of the discreet layers of the polycrystalline diamond material are exposed, and wherein adjacent layers have different abrasion resistances.   
   
   
       2 . The cutting element of  claim 1  wherein the diamond material in the outermost, first layer is treated to remove a catalyzing material from the polycrystalline diamond material, forming a new layer on the working surface that is substantially free of the catalyzing material. 
   
   
       3 . The cutting element of  claim 1  wherein at least two of the layers have different thicknesses 
   
   
       4 . The cutting element of  claim 2  wherein a plurality of the layers have differing volume densities. 
   
   
       5 . The cutting element of  claim 4  wherein, in operation, at least three protruding lips form along the generally cylindrical peripheral working surface. 
   
   
       6 . The cutting element of  claim 5 , wherein the peripheral working surface is substantially perpendicular to the end working surface. 
   
   
       7 . The cutting element of  claim 2  wherein at least two of the layers are comprised of diamond crystals of differing particle size. 
   
   
       8 . The cutting element of  claim 7  wherein, in operation, at least three protruding lips form along the generally cylindrical peripheral working surface. 
   
   
       9 . The cutting element of  claim 8 , wherein the peripheral working surface is substantially perpendicular to the end working surface. 
   
   
       10 . The cutting element of  claim 9  wherein the layers contain encapsulated diamond material which has been pre-synthesized. 
   
   
       11 . The cutting element of  claim 9  wherein a portion of the diamond material is made with powdery carbonates. 
   
   
       12 . The cutting element of  claim 6  wherein, in operation, the protruding lips form on a worn portion of the end working surfaces. 
   
   
       13 . A method of using a cutting element comprising:
 forming a continuous table of polycrystalline diamond material having at least three different layers, each layer having a different diamond constituency, the diamond material bonded to a tungsten carbide substrate comprising a facing table having a generally planar, generally circular end working surface, and a generally cylindrical peripheral working surface;   treating at least part of each of the end working surface and the peripheral working surface to remove catalyzing material therefrom;   exposing untreated superhard material between the end and peripheral working surfaces, and   preferentially wearing the exposed, untreated polycrystalline diamond material of the cutting element to expose at least three protruding lips.   
   
   
       14 . The method of  claim 13 , wherein the step of preferentially wearing the exposed, untreated polycrystalline diamond material comprises machining away the polycrystalline diamond material. 
   
   
       15 . The method of  claim 13 , wherein the step of preferentially wearing the exposed, untreated polycrystalline diamond material comprises wearing away the polycrystalline diamond material during a drilling operation. 
   
   
       16 . A PDC cutting element for use in earth boring, comprising a continuous facing table of a polycrystalline diamond material integrally bonded to a tungsten carbide substrate, the facing table comprising a generally planar, generally circular end working surface, and a generally cylindrical peripheral working surface,
 the polycrystalline diamond material remote from the working surfaces comprising a first series of interstices containing a catalyzing material and having a first wear resistance,   the polycrystalline diamond material adjacent the working surfaces forming a region at the surface of the facing table comprising a second series of interstices adjacent at least part of the end working surface and at least part of the peripheral working surface,   the second series of interstices are substantially free of the catalyzing material to a depth of between about 0.02 mm and 0.25 mm,   whereby the region formed at the surface of the facing table adjacent the working surfaces has a thickness from the surface of between 0.02 mm and 0.25 mm and has at least three different layers polycrystalline diamond material, each layer having a different wear resistance, and all the layers having a higher wear resistance than the polycrystalline diamond material remote from the working surfaces.   
   
   
       17 . The cutting element of  claim 16 , wherein the peripheral working surface is substantially perpendicular to the end working surface. 
   
   
       18 . The cutting element of  claim 16  wherein at least two of the layers have different thicknesses. 
   
   
       19 . The cutting element of  claim 17  wherein a plurality of the layers have differing volume densities. 
   
   
       20 . The cutting element of  claim 19  wherein, in operation, at least three protruding lips form along the generally cylindrical peripheral working surface. 
   
   
       21 . The cutting element of  claim 20 , wherein the peripheral working surface is substantially perpendicular to the end working surface. 
   
   
       22 . The cutting element of  claim 17  wherein at least two of the layers are comprised of diamond crystals of differing particle size. 
   
   
       23 . The cutting element of  claim 22  wherein, in operation, at least three protruding lips form along the generally cylindrical peripheral working surface. 
   
   
       24 . The cutting element of  claim 23 , wherein the peripheral working surface is substantially perpendicular to the end working surface. 
   
   
       25 . The cutting element of  claim 24  wherein the layers contain encapsulated diamond material which has been pre-synthesized. 
   
   
       26 . The cutting element of  claim 24  wherein a portion of the diamond material is made with powdery carbonates. 
   
   
       27 . The cutting element of  claim 23  wherein, in operation, the protruding lips form on a worn portion of the end working surfaces.