Dual-Edge Working Surfaces for Polycrystalline Diamond Cutting Elements

Abstract

A PCD cutting element, which in operation (and as it wears to a worn condition) presents at least two cutting lips to the material being cut. One particularly advantageous use of this new PDC cutting element is as cutting elements for earth boring drill bits.

1 . A cutting element comprising a table of superhard material bonded to a substrate of less hard material, the table of superhard material defining a plurality of interstices containing a catalyzing material, the table of superhard material defining an end working surface and a peripheral working surface, wherein at least part of the end working surface and at least part of the peripheral working surface are substantially free of catalyzing material.  
   
   
       2 . An element according to  claim 1 , wherein an edge of the part of the end working surface which is substantially free of catalyzing material defines a first protruding lip, and an edge of the part of the peripheral working surface which is substantially free of catalyzing material defines a second protruding lip.  
   
   
       3 . An element according to  claim 1 , wherein the end working surface is substantially planar, and the peripheral working surface is substantially perpendicular thereto.  
   
   
       4 . An element according to  claim 1 , wherein the peripheral working surface is of substantially frusto-conical form.  
   
   
       5 . An element according to  claim 1 , wherein the superhard material is polycrystalline diamond.  
   
   
       6 . An element according to  claim 1 , wherein the table of superhard material comprises regions of different abrasion resistance.  
   
   
       7 . An element according to  claim 6 , wherein the regions comprise a series of layers.  
   
   
       8 . An element according to  claim 6 , wherein the regions comprise a series of concentric rings.  
   
   
       9 . An element according to  claim 1 , wherein the table of superhard material incorporates encapsulated diamond material.  
   
   
       10 . An element according to  claim 9 , wherein the encapsulated diamond material is made with powdery carbonates.  
   
   
       11 . An element according to  claim 1 , wherein a region of superhard material containing catalyzing material is exposed between the parts of the peripheral working surface and the end working surface which are substantially free of catalyzing material.  
   
   
       12 . An element according to  claim 11 , wherein a first protruding lip is formed adjacent said region at an edge of the part of the end working surface which is substantially free of catalyzing material and a second protruding lip is formed adjacent said region at an edge of the part of the peripheral working surface which is substantially free of catalyzing material.  
   
   
       13 . An element according to  claim 11 , wherein said region is formed by machining away of material.  
   
   
       14 . An element according to  claim 11 , wherein said region is formed, in use, by part of the cutting element wearing.  
   
   
       15 . An element according to  claim 1 , wherein the said parts of the working surface which are substantially free of catalyzing material extend to a depth in the range of about 0.02 mm to about 0.70 mm.  
   
   
       16 . An element according to  claim 15 , wherein the said parts extend to a depth in the range of about 0.15 mm to about 0.25 mm.  
   
   
       17 . A method of manufacturing a cutting element comprising forming a table of superhard material bonded to a less hard substrate, the table of superhard material defining a plurality of interstices containing a catalyzing material, the table defining an end working surface and a peripheral working surface, and treating at least part of each of the end working surface and the peripheral working surface to remove the catalyzing material therefrom.  
   
   
       18 . A method according to  claim 17 , further comprising exposing untreated superhard material between the end and peripheral working surfaces.  
   
   
       19 . A method according to  claim 18 , wherein the step of exposing comprises machining away material.  
   
   
       20 . A cutting element comprising a table of superhard material bonded to a substrate of less hard material, the superhard material defining a plurality of interstices containing a catalyzing material, the surface of the superhard material having been treated to remove catalyzing material from parts thereof to define edge constituting first and second protruding lips.