Apparatus and method for forging premium coupling blanks

Abstract

A method and apparatus for forging a tubular forging stock to produce a forged product, preferably a premium coupling machining blank. The apparatus includes a holding die assembly defining a holding cavity for the forging stock and a press die apparatus including opposed first and second press dies movable within the holding cavity to forge the forging stock to produce the forged product. The holding die assembly may include opposed first and second holding dies defining respective portions of the holding cavity, wherein the holding dies are selectively relatively movable between a closed position for forging the forging stock and an open position for removal of the forged product. Alternately, the apparatus may include a knockout mechanism for dislodging the forged product from the holding cavity. Further, the apparatus may include a mechanism for controlling finning between the first and second press dies while the forged product is being produced.

Description

TECHNICAL FIELD[0001]The present invention is directed at a forging apparatus and a forging method for producing a forged product from a forging stock. Preferably, the forging stock is a standard American Petroleum Institute (“API”) coupling blank and the forged product is a premium coupling machining blank.BACKGROUND OF THE INVENTION[0002]There is a growing demand in the oil and gas industry for Oil Country Tubular Goods (“OCTG”) premium couplings to couple adjacent casing or tubing joints or sections. A typical “premium coupling” includes a central pin seal and opposed threaded end portions. A compatible threaded pin end of the tubing or casing joint is threaded with or screwed into each respective threaded end portion of the premium coupling to abut against the central pin seal. The abutment of the pin end of each tubing or casing joint with the pin seal creates a relatively strong seal upon the application of a sufficient amount of torque.[0003]The threaded connection of the adj...

AI Technical Summary

Benefits of technology

[0037]Further, as indicated, in some embodiments, the first holding die and the second holding die are selectively relatively movable toward each other to a closed position of the holding die assembly and away from each other to an open position of the holding die assembly. Preferably, one of the first holding die and the second holding die is in a fixed position and the other of the first holding die and the second holding die is movable. Preferably, where the holding die interface is substantially horizontal, the first holding die is a bottom holding die and the second holding die is a top holding die, wherein the bottom holding die is fixed and wherein the top holding die is movable. Alternately, the top holding die may be fixed, while the bottom holding die is movable. Further, the first holding die, the second holding die and the holding cavity are configured so that the forged product produced by the forging apparatus may be removed from the holding cavity, preferably readily or relatively easily or efficiently, when the holding die assembly is in the open position.

[0039]The first end retainer and the second end retainer act to retain the forged product in the holding cavity during the release of the press die apparatus, particularly during the withdrawal of one or both of the first press die and the second press die from the holding cavity. In other words, the first and second end retainers prevent or inhibit the forged product from being pulled along by the first and second press dies respectively during the withdrawal thereof, thus facilitating the subsequent removal of the forged product from the forging apparatus.

Problems solved by technology

However, standard API coupling stock and blanks do not provide a sufficient wall thickness to permit the machining of a premium coupling therefrom.

Thc need to utilize premium coupling stock increases the overall cost of production of the premium coupling.

In addition, the varying wall thickness of the premium coupling along its length, particularly the requirement for the central pin seal, presents further challenges for manufacturing the premium coupling efficiently.

As a result, this process for the production of premium couplings involves a large amount of machining, which increases the production costs and tends to result in a relatively large amount of wasted material.

Further, the increased machining time tends to wear the tools faster, which increases the risk of machine down time and increases the tooling expense.

As a result of all of the material inefficiencies, machining inefficiencies and inventory cost inefficiencies arising from the machining of premium couplings, such premium couplings tends to be relatively expensive.

Specifically, forging of the premium coupling blank may eliminate or reduce the need for “rough boring” of the premium coupling stock to produce the premium coupling blank, which may result in a relatively significant decrease in material losses.

However, neither the forging process and machine of Hirano et. al., nor other known forging processes or apparatuses, have been found to be fully satisfactory.

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