Composite seal for rotary cone rock bits

Abstract

An elastomeric o-ring rock bit seal is disclosed with two or more integrally bonded elastomers or phenolic type materials joined together to form the seal. The dynamic sealing face adjacent the journal bearing is fabricated from an elastomer/phenolic engineered specifically for wear resistance The bulk of the seal adjacent the static seal retention cavity typically formed in the rotary cone is molded from an elastomer engineered specifically for precise control of the seal contact force adjacent the dynamic seal face when the seal is compressed against the dynamic face by the seal retention cavity in the cone.

What is claimed is: 
     
       1. A composite O-ring seal for a sealed bearing rotary cone rock bit, the seal being confined within a seal cavity formed between a rotary cutter cone and a .Iadd.bearing .Iaddend.journal .[.bearing.]. comprising: a first elastomer integrally bonded to at least a second elastomer, said first elastomer .Iadd.forming a wear resistant sealing surface .Iaddend.in contact with a dynamic .[.bearing.]. .Iadd.rotary .Iaddend.surface .[.being wear resistant.]., the first elastomer material consists of about 55 percent by .[.wht..]. .Iadd.weight .Iaddend.of HSN polymer, about 0.8 percent by .[.wht..]. .Iadd.weight .Iaddend.of an antioxidant, about 3 percent by .[.wht..]. .Iadd.weight .Iaddend.of an activator, about 22 percent by .[.wht..]. .Iadd.weight .Iaddend.of carbon black, about 8 percent by .[.wht..]. .Iadd.weight .Iaddend.of a curative and about 8 percent by .[.wht..]. .Iadd.weight .Iaddend.of graphite, said second elastomer .Iadd.being different from the first material and forming a second sealing surface in contact with a surface of the seal cavity, said second elastomer .Iaddend.having properties adapted for precise control of seal contact force while resisting compression set when the seal is squeezed within said seal cavity, and   means for applying contact pressure to said composite seal.   
     
     
       2. .[.The invention as set forth in claim 1 wherein the second elastomer material consists of about 66 percent by wht. of HSN polymer, about 0.8 percent by wht. of an antioxidant, about 3 percent by wht. of an activator, about 20 percent by wht. of carbon black, and about 8 percent by wht. of a curative.]. .Iadd.A composite O-ring seal for a sealed bearing rotary cone rock bit, the seal being confined within a seal cavity formed between a rotary cutter cone and a bearing journal comprising:   a first elastomer integrally bonded to at least a second elastomer, said first elastomer having a wear resistant sealing surface in contact with a dynamic rotary surface, said second elastomer being different from the first material and forming a second sealing surface in contact with a surface of the seal cavity, wherein the second elastomer material comprises about 66 percent by weight of HSN polymer, about 0.8 percent by weight of an antioxidant, about 3 percent by weight of an activator, about 20 percent by weight of carbon black, and about 8 percent by weight of a curative; and   means for applying contact pressure to said composite seal.Iaddend..   
     
     
       3. .[.The invention as set forth in claim 1 further comprising.]. .Iadd.A composite O-ring seal for a sealed bearing rotary cone rock bit, the seal being confined within a seal cavity formed between a rotary cutter cone and a journal .Iaddend.comprising: .Iadd.a first elastomer integrally bonded to at least a second elastomer, said first elastomer in contact with a dynamic surface being wear resistant, said second elastomer having properties adapted for precise control of seal contact force while resisting compression set when the seal is squeezed within said seal cavity, and   means for applying contact pressure to said composite seal, and .Iaddend.a third wear resistant elastomer bonded to said first elastomer and to said second elastomer, said first and third elastomers being in contact with said dynamic .[.bearing.]. surface, said third elastomer being positioned adjacent an exterior side of said seal, said third elastomer containing a tear and abrasion resistant ingredient to further inhibit admittance of detritus into the .[.dynamic.]. bearing surfaces.   
     
     
       4. .[.The invention as set forth in claim 3.]. .Iadd.A composite O-ring seal for a sealed bearing rotary cone rock bit, the seal being confined within a seal cavity formed between a rotary cutter cone and a journal comprising: a first elastomer integrally bonded to at least a second elastomer, said first elastomer in contact with a dynamic surface being wear resistant, said second elastomer having properties adapted for precise control of seal contact force while resisting compression set when the seal is squeezed within said seal cavity,   means for applying contact pressure to said composite seal, and   a third wear resistant elastomer bonded to said first elastomer and to said second elastomer, said first and third elastomers being in contact with said dynamic surface, said third elastomer being positioned adjacent an exterior side of said seal, .Iaddend.wherein the third elastomer material consists of about 55 percent by .[.wht..]. .Iadd.weight .Iaddend.of HSN polymer, about 0.8 percent by .[.wht..]. .Iadd.weight .Iaddend.of an antioxidant, about 3 percent by .[.wht..]. .Iadd.weight .Iaddend.of an activator, about 22 percent by .[.wht..]. .Iadd.weight .Iaddend.of carbon black, about 8 percent by .[.wht..]. .Iadd.weight .Iaddend.of a curative, about 8 percent by .[.wht..]. .Iadd.weight .Iaddend.of graphite.Iadd., .Iaddend.and about 3 percent by .[.wht..]. .Iadd.weight .Iaddend.of a tear and abrasion resistance material.   
     
     
       5. The invention as set forth in claim 1 further including a barrier material bonded to said first elastomer in contact with said dynamic bearing surface, said barrier material being adjacent an exterior area exposed to detritus material generated during operation of said rock bit in an earthen formation. 
     
     
       6. The invention as set forth in claim 5 wherein said barrier material is a screen mesh. 
     
     
       7. The invention as set forth in claim 6 wherein the barrier material is selected from the group consisting of steel, brass and bronze. .[. 
     
     
       8.  The invention as set forth in claim 6 wherein the barrier material is a thermo-plastic..]. 
     
     
       9. .[.The invention as set forth in claim 6.]. .Iadd.A composite O-ring seal for a sealed bearing rotary cone rock bit, the seal being confined within a seal cavity formed between a rotary cutter cone and a journal comprising: a first elastomer integrally bonded to at least a second elastomer, said first elastomer in contact with a dynamic surface being wear resistant, said second elastomer having properties adapted for precise control of seal contact force while resisting compression set when the seal is squeezed within said seal cavity, and   means for applying contact pressure to said composite seal, and   a barrier material bonded to said first elastomer in contact with said dynamic surface, said barrier material being adjacent an exterior area exposed to detritus material generated during operation of said rock bit in an earthen formation .Iaddend.wherein the .Iadd.barrier material is selected from the group of .Iaddend.thermo-plastic .[.is polyamide or.]. .Iadd.materials consisting of polyimide and .Iaddend.polytetraflouroethylene.   
     
     
       10. .[.The invention as set forth in claim 6 wherein the barrier material is graphite.]. .Iadd.A composite O-ring seal for a sealed bearing rotary cone rock bit, the seal being confined within a seal cavity formed between a rotary cutter cone and a journal comprising: a first elastomer integrally bonded to at least a second elastomer, said first elastomer in contact with a dynamic surface being wear resistant, said second elastomer having properties adapted for precise control of seal contact force while resisting compression set when the seal is squeezed within said seal cavity, and   means for applying contact pressure to said composite seal, and   a graphite barrier material bonded to said first elastomer in contact with said dynamic surface, said barrier material being adjacent an exterior area exposed to detritus material generated during operation of said rock bit in an earthen formation.Iaddend..   
     
     
       11. The invention as set forth in claim 1 wherein the durometer hardness of the first wear resistance elastomeric material is about 90. 
     
     
       12. The invention as set forth in claim 1 wherein the durometer hardness of the second elastomeric material is from 65 to 70. .Iadd.13. A sealed bearing rotary cone rock bit comprising: a bit body;   at least one rotary cutter cone mounted for rotation on the bit body;   a composite O-ring seal being confined within a seal cavity forced between the rotary cutter cone and a journal on the bit body, the seal comprising a first wear resistant elastomer integrally bonded to at least a second elastomer different from the first elastomer, the first wear resistant elastomer forming a sealing surface in contact with a dynamic rotary surface, the second elastomer forming a second sealing surface and having properties adapted for control of seal contact force while resisting compression set when the seal is squeezed within the seal cavity, and   a second surface for applying contact pressure to the second sealing surface of the composite seal. .Iaddend..Iadd.14. The sealed bearing rotary cone rock bit as recited in claim 13 wherein the dynamic surface has a first radius of curvature in a transverse cross section, and the second surface has a second radius of curvature in a transverse cross section which is different from the radius of curvature of the dynamic   
     
     
        surface. .Iaddend..Iadd.15.  A sealed bearing rotary cone rock bit comprising: a bit body;   at least one rotary cutter cone mounted for rotation on the bit body;   a composite O-ring seal being confined within a seal cavity formed between the rotary cutter cone and a journal on the bit body, the seal comprising a first wear resistant elastomer integrally bonded to at least a second elastomer, the first wear resistant elastomer forming a first sealing surface and being in contact with a dynamic rotary surface, the second elastomer being formed from a material different than the first elastomer and forming a second sealing surface, wherein the second elastomer has properties adapted for control of seal contact force while resisting compression set when the seal is squeezed within the seal cavity, and   a second surface for applying contact pressure to the composite seal,   wherein the second sealing surface has a radius of curvature adjacent to the second surface different from a radius of curvature of the first sealing surface adjacent to the dynamic rotary surface. .Iaddend..Iadd.16. A sealed bearing rotary cone rock bit comprising:   a bit body;   at least one rotary cutter cone mounted for rotation on the bit body;   a composite O-ring seal being confined within a seal cavity formed between the rotary cutter cone and a journal on the bit body, the seal comprising a first wear resistant elastomer integrally bonded to at least a second elastomer, the first wear resistant elastomer forming a first sealing surface in contact with a dynamic rotary surface, the second elastomer forming a second sealing surface and being formed from a material different than the first elastomer, the second elastomer having properties adapted for control of seal contact force while resisting compression set when the seal is squeezed within the seal cavity, and a second surface for applying contact pressure to the composite seal, and wherein   the seal cross section has a greater width in a radial direction, between the second surface and the dynamic rotary surface, than a width in an axial direction. .Iaddend..Iadd.17. The sealed bearing rotary cone rock bit as recited in claim 16 wherein the dynamic surface has a first radius of curvature in a transverse cross section, and the second surface has a second radius of curvature in a transverse cross section which is different from the radius of curvature of the dynamic surface. .Iaddend..Iadd.18. A sealed bearing rotary cone rock bit comprising:   a bit body;   at least one rotary cutter cone mounted for rotation on the bit body; and   a composite O-ring seal disposed within a seal cavity formed between the rotary cutter cone and a journal on the bit body, the seal comprising:   a dynamic sealing surface rotatable bearing against one of the bit body and cutter cone, the dynamic sealing surface formed from a first wear resistant elastomer; and   a second sealing surface bearing against a relatively static surface of the other of the cutter cone and bit body, the second sealing surface formed from a second elastomer that is different than the first elastomer and that extends from the second sealing surface to the dynamic sealing surface, the second elastomer having a lower hardness than the first elastomer. .Iaddend..Iadd.19. The sealed bearing rotary cone rock bit as recited in claim 18 wherein the seal cross section has a greater width in a radial direction, between the second and dynamic surfaces, than a width in an axial direction. .Iaddend..Iadd.20. The sealed bearing rotary cone rock bit as recited in claim 18 wherein the dynamic surface has a first radius of curvature in a transverse cross section, and the second surface has a second radius of curvature in a transverse cross section which is different from the radius of curvature of the dynamic surface. .Iaddend..Iadd.21. The sealed bearing rotary cone rock bit as recited in claim 18 wherein the dynamic surface has a first radius of curvature in a transverse cross section, and the second surface has a second radius of curvature in a transverse cross section which is different from the radius   
     
     
        of curvature of the dynamic surface. .Iaddend..Iadd.22.  A sealed bearing rotary cone rock bit comprising: a bit body;   at least one rotary cutter cone mounted for rotation on the bit body; and   a composite O-ring seal disposed within a seal cavity formed between the rotary cutter cone and a journal on the bit body, the seal comprising a dynamic first sealing surface formed from a first elastomer and a second sealing seal surface formed from a second elastomer, wherein at least one of the first and second elastomers includes a non-elastomeric polymeric constituent. .Iaddend..Iadd.23. The rock bit as recited in claim 22 wherein the non-elastomeric polymeric constituent of the O-ring seal is selected from the group of fiber materials. .Iaddend..Iadd.24. The rock bit as recited in claim 22 wherein the non-elastomeric polymeric constituent of the O-ring seal is an aromatic polyamide fiber. .Iaddend.