Cutting element assemblies comprising rotatable cutting elements insertable from the back of a blade

Abstract

An earth-boring tool is comprised of a body, blade, and cutting element assembly. The sleeve of the cutting element assembly has an interior surface that defines a cavity. A rotatable cutting element fits within the cavity secured by a threaded end cap. The rotatable cutting element is comprised of a polycrystalline hard material bonded to a supporting substrate. The polycrystalline hard material has an end cutting surface on a first end and the supporting substrate has a back surface on a second end opposite the first end. An annular ring has an upper surface in contact with the back surface of the supporting substrate and a lower surface in contact with the upper surface of the end cap. There is a spring in a void defined by an inner surface of the annular ring, the back surface of the supporting substrate, and the upper surface of the end cap.

What is claimed is: 
     
         1 . A cutting element assembly, comprising:
 a sleeve having at least one interior surface defining a cavity therein and helical threads proximate an end of the at least one interior surface;   an end cap having threads engaging the helical threads of the sleeve, the end cap having an upper surface;   a rotatable cutting element within the sleeve, the rotatable cutting element comprising a polycrystalline hard material bonded to a supporting substrate, wherein the polycrystalline hard material has an end cutting surface on a first end of the rotatable cutting element and wherein the supporting substrate has a back surface on a second end of the rotatable cutting element opposite the first end;   an annular ring having an upper surface in contact with the back surface of the supporting substrate and a lower surface in contact with the upper surface of the end cap, the annular ring having an inner surface; and   a spring disposed within a void defined by the inner surface of the annular ring, the back surface of the supporting substrate, and the upper surface of the end cap.   
     
     
         2 . The cutting element assembly of  claim 1 , wherein the back surface of the rotatable cutting element is parallel to the end cutting surface. 
     
     
         3 . The cutting element assembly of  claim 1 , wherein the supporting substrate defines a bearing portion of the back surface, and wherein the bearing portion of the back surface is in rotational sliding contact with the upper surface of the annular ring. 
     
     
         4 . The cutting element assembly of  claim 1 , wherein the lower surface of the annular ring is in rotational sliding contact with the upper surface of the end cap. 
     
     
         5 . The cutting element assembly of  claim 1 , wherein the spring comprises a metal. 
     
     
         6 . The cutting element assembly of  claim 1 , wherein the annular ring comprises a metal. 
     
     
         7 . The cutting element assembly of  claim 1 , wherein the annular ring comprises a ceramic. 
     
     
         8 . The cutting element assembly of  claim 1 , wherein when a compressive longitudinal load is applied to the end cutting surface of the polycrystalline hard material of the rotatable cutting element, the compressive longitudinal load is transferred to the end cap substantially via the annular ring. 
     
     
         9 . The cutting element assembly of  claim 1 , further comprising a lubricant between the sleeve and the rotatable cutting element. 
     
     
         10 . The cutting element assembly of  claim 1 , further comprising a diamond like carbon coating over at least one surface selected from the group consisting of the back surface of the supporting substrate, the upper surface of the end cap, the upper surface of the annular ring, and the lower surface of the annular ring. 
     
     
         11 . An earth-boring tool comprising:
 a body comprising at least one blade extending radially outward to define a face proximate a leading end of the body; and   a cutting element assembly carried by a rotationally leading portion of the at least one blade, the cutting element assembly comprising a sleeve;
 the sleeve having at least one interior surface defining a cavity therein and helical threads proximate an end of the at least one interior surface; 
 an end cap having threads engaging the helical threads of the sleeve, the end cap having an upper surface; 
 a rotatable cutting element within the sleeve, the rotatable cutting element comprising a polycrystalline hard material bonded to a supporting substrate, wherein the polycrystalline hard material has an end cutting surface on a first end of the rotatable cutting element and the supporting substrate has a back surface on a second end of the rotatable cutting element opposite the first end; 
 an annular ring having an upper surface in contact with the back surface of the supporting substrate and a lower surface in contact with the upper surface of the end cap, the annular ring having an inner surface; and 
 a spring disposed within a void defined by the inner surface of the annular ring, the back surface of the supporting substrate, and the upper surface of the end cap. 
   
     
     
         12 . The earth-boring tool of  claim 11 , wherein the back surface of the rotatable cutting element is parallel to the end cutting surface. 
     
     
         13 . The earth-boring tool of  claim 11 , wherein the supporting substrate defines a bearing portion of the back surface, and wherein the bearing portion of the back surface is in rotational sliding contact with the upper surface of the annular ring. 
     
     
         14 . The earth-boring tool of  claim 11 , wherein the lower surface of the annular ring is in rotational sliding contact with the upper surface of the end cap. 
     
     
         15 . The earth-boring tool of  claim 11 , wherein the spring comprises a metal. 
     
     
         16 . The earth-boring tool of  claim 11 , wherein the annular ring comprises a metal. 
     
     
         17 . The earth-boring tool of  claim 11 , wherein the annular ring comprises a ceramic. 
     
     
         18 . The earth-boring tool of  claim 11 , wherein when a compressive longitudinal load is applied to the end cutting surface of the polycrystalline hard material of the rotatable cutting element, the compressive longitudinal load is transferred to the end cap substantially via the annular ring. 
     
     
         19 . The cutting element assembly of  claim 11 , further comprising a lubricant between the sleeve and the rotatable cutting element. 
     
     
         20 . The cutting element assembly of  claim 11 , further comprising, a diamond like carbon coating over at least one surface selected from the group consisting of the back surface of the supporting substrate, the upper surface of the end cap, the upper surface of the annular ring, and the lower surface of the annular ring.