Method of producing high strength sucker rod coupling
AssigneeLTV Energy Products Company
InventorsDean E. Hermanson, Donald F. Hallden, Horace G. Isom
Life of this patent
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Abstract
A sucker rod coupling 10 having a high ultimate tensile strength, resistance to corrosion, and resistance to surface cracking arising out of a method of making the sucker rod coupling 10, which employs a five-step process of forming a coupling 10. First, a hollow cylindrical core 12 from a heat treatable steel is formed. Second, a thin coating 18 of metallic alloy is applied to the outer surface of the core 12. Third, the core 12 is heat treated. Fourth, threads 20 are partially cut in the inner surface of the core 12. Fifth, the threads 20 are cold worked to transform the partially cut threads 20 into finished threads 20 and to place the thread roots 22 in compression.
Claims9
A method of producing a sucker rod coupling, comprising the steps of:
- a. forming a hollow cylindrical core from a heat treatable steel, said core having an inner surface and an outer surface;
- b. applying a thin layer coating to said outer surface, said coating having a Rockwell hardness of at least 45 HRC;
- c. heat treating said core and said coating to elevate Rockwell hardness of said core to greater than 23 HRC;
- d. cutting partial threads in said inner surface of said core;
- said partial threads having roots;
- and
- e. cold working said partial threads to transform said partial threads into finished threads and to place said thread roots in compression.
A method of producing a sucker rod coupling, comprising the steps of:
- a. forming a hollow cylindrical core from a heat treatable steel, said core having an inner surface and an outer surface;
- b. heat treating said core to give said core an ultimate tensile strength greater than about 117,000 pounds per square inch;
- c. cutting partial threads in said inner surface of said core;
- said partial threads having roots;
- and
- d. cold working said partial threads to transform said partial threads into finished threads and to place said thread roots in compression.
A method of producing a sucker rod coupling, comprising the steps of:
- a. forming a hollow cylindrical core from a heat treatable steel, said core having an inner surface and an outer surface;
- b. heat treating said core to elevate the Rockwell hardness of said core to greater than 23 HRC;
- c. applying a thin layer coating of a plastic material to said outer surface after said core is heat treated;
- d. cutting partial threads in said inner surface of said core;
- said partial threads having roots;
- and
- e. cold working said partial threads to transform said partial threads into finished threads and to place said thread roots in compression.
Dependencies are inferred from the claim text.