System, Method and Apparatus for Composite Seal Gland Insert in Roller Cone Rock Bit

Abstract

A composite seal gland insert for a roller cone rock bit is a polymer composite sleeve containing one or more constituents that function to significantly lower the wear of the elastomeric seal ring. A fluid lubricant film also may be used between the elastomer seal and the gland. The outer surface of the insert is profiled to provide a sealing surface against which the elastomer seal runs. The insert is installed over the bearing pin and has a surface that engages the last machined surface of the leg. A static seal, which may comprise an additional elastomeric seal, may be used beneath the gland insert to provide a pressure seal between the insert and the pin. An adhesive also may be used as the pressure seal and also to retain the gland insert in the desired position. In addition, a mechanical anti-rotation device may be used to prevent rotation of the gland insert.

1 . A rock bit, comprising:
 a body having a bit leg extending therefrom;   a bearing pin extending from the bit leg and having a bearing pin axis, a last machined surface adjacent the bit leg;   a roller cone rotatably mounted to the bearing pin;   a gland defined between the bearing pin and the roller cone adjacent the last machined surface;   an elastomer seal located in the gland; and   a gland insert located in the gland between the elastomer seal and one of the bearing pin and the roller cone, the gland insert being formed from a polymer material.   
   
   
       2 . The rock bit according to  claim 1 , wherein the polymer material comprises a polymer composite material having a reinforcing material dispersed within. 
   
   
       3 . The rock bit according to  claim 2 , wherein the reinforcing material comprises fibers within the polymer material. 
   
   
       4 . The rock bit according to  claim 3 , wherein the fiber comprises carbon fiber. 
   
   
       5 . The rock bit according to  claim 1 , wherein the polymer material comprises one of polyetheretherketone (PEEK) and a polyimide. 
   
   
       6 . The rock bit according to  claim 1 , wherein the polymer material has a low friction material dispersed within at least a part thereof. 
   
   
       7 . The rock bit according to  claim 1 , wherein a surface of the gland insert that engages the elastomer seal has a grooved profile. 
   
   
       8 . The rock bit according to  claim 1 , wherein the gland insert is installed on the bearing pin, and a surface of the gland insert engages the last machined surface. 
   
   
       9 . The rock bit according to  claim 1 , further comprising a static seal between the gland insert and said one of the bearing pin and the roller cone. 
   
   
       10 . The rock bit according to  claim 1 , further comprising a mechanical anti-rotation device extending between the gland insert and the last machined surface to prevent rotation of the gland insert relative to the bearing pin. 
   
   
       11 . A rock bit, comprising:
 a body having a bit leg extending therefrom;   a bearing pin extending from the bit leg and having a bearing pin axis, a last machined surface adjacent the bit leg;   a roller cone rotatably mounted to the bearing pin;   a gland defined between the bearing pin and the roller cone adjacent the last machined surface;   an elastomer seal located in the gland and engaging the roller cone; and   a gland insert located in the gland between the elastomer seal and the bearing pin, the elastomer seal slidingly engaging an outer diameter of the gland insert, the gland insert comprising a sleeve formed of a polymer composite material containing a reinforcing material therein.   
   
   
       12 . The rock bit according to  claim 11 , wherein the polymer composite material comprises one of polyetheretherketone (PEEK) and a polyimide. 
   
   
       13 . The rock bit according to  claim 11 , wherein the outer diameter of the gland insert contains a grooved profile. 
   
   
       14 . A rock bit, comprising:
 a body having a bit leg extending therefrom;   a bearing pin extending from the bit leg and having a bearing pin axis, a last machined surface adjacent the bit leg;   a roller cone rotatably mounted to the bearing pin;   a gland defined between the bearing pin and the roller cone adjacent the last machined surface;   an elastomer seal located in the gland and engaging the roller cone for rotation with the roller cone;   a gland insert located in the gland between the elastomer seal and the bearing pin, the gland insert being a sleeve mounted on the bearing pin with an anti-rotation device to prevent any rotational movement of the gland insert relative to the bearing pin, the elastomer seal being in sliding engagement with an outer diameter of the gland insert;   a static seal of elastomeric material between an inner diameter of the gland insert and the bearing pin; and   the gland insert being formed of a polymer containing reinforcing fibers and having a low friction material therein.   
   
   
       15 . The rock bit according to  claim 14 , further comprising a mechanical anti-rotation device extending between the gland insert and the bit leg. 
   
   
       16 . The rock bit according to  claim 14 , wherein the reinforcing fibers are formed of carbon. 
   
   
       17 . The rock bit according to  claim 14 , wherein the polymer comprises a selected one of polyetheretherketone (PEEK) and a polyimide. 
   
   
       18 . The rock bit according to  claim 14 , wherein the gland insert has a greater tensile strength than a tensile strength of the elastomer seal.