Cold Forged Stub End

Abstract

Apparatus for forming and shaping a stub end fitting and methods for forming the stub end fitting, are provided. The apparatus can include application of a multi-part die including first and second die parts which both together contain a preformed stub end fitting having an annular shaped flange, and a third die part (“push bullet”) used to land upon an end of a tubular member opposite the flange of the stub end fitting in order to cause portions of the stub end fitting to extrude into a cavity between the first and second die portions not already filled by the stub end fitting during initial containment. The resulting stub end fitting has enhanced material and operational properties. Additional material can be added to the outer diameter portion of the stub end fitting between the tubular main body and the flange to build or enhance an existing annular fillet to further enhance the material and operational properties of the stub end fitting.

1 . A method of forming a metal stub end fitting for a pipe, comprising:
 (a) bending a distal end of a tubular member to create a flange, the flange and the tubular member defining a junction with an interior radius; and   (b) placing the flange within a cavity of a die and applying a distally directed force to a proximal end of tubular member while restraining inward deformation of the tubular member, causing the flange to conform to dimensions of the cavity and decreasing the interior radius.   
     
     
         2 . The method as defined in  claim 1 , wherein the cavity has a distal face that is frusto-conical, causing a distally facing surface of the flange to become frusto-conical. 
     
     
         3 . The method as defined in  claim 2 , further comprising the step of machining the distally facing surface of the flange to a flat surface. 
     
     
         4 . The method as defined in  claim 1 , wherein during step (b) the cavity restrains expansion of an outer diameter of the flange. 
     
     
         5 . The method as defined in  claim 1 , further comprising the step of applying a weld bead around an exterior fillet joining the flange with the tubular member. 
     
     
         6 . The method as defined in  claim 5 , further comprising the step of machining the weld bead to a desired external radius for the exterior fillet. 
     
     
         7 . The method as defined in  claim 1 , wherein step (a) comprises deforming the distal end of the tubular member with a conically shaped punch to create a conical flange, then deforming the conical flange with a flat punch to flatten the flange. 
     
     
         8 . The method as defined in  claim 1 , wherein step (b) creates a sharp interior corner at the junction. 
     
     
         9 . A method of forming a metal stub end fitting for a pipe, comprising:
 (a) forming a circumferentially extending flange on a distal end of a tubular member, the flange and the tubular member defining a junction with an interior radius;   (b) providing a die having a cylindrical chamber with proximal and distal ends, the distal end being surrounded by a distally facing surface;   (c) inserting the tubular member into the distal end of the chamber with the flange in contact with the distally facing surface;   (d) securing a closure plate to a distal side of the die, trapping the flange within a cavity between the distally facing surface and a face on the closure plate;   (e) providing a plunger having a cylindrical portion and an external annular shoulder, the cylindrical portion of the plunger having an outer diameter substantially equal to an inner diameter of the tubular member; and   (f) inserting the cylindrical portion of the plunger into the tubular member and past the flange, engaging a proximal end of the tubular member with the external shoulder and applying a force that shortens a length of the tubular member and causes metal at the junction to flow, decreasing the interior radius.   
     
     
         10 . The method as defined in  claim 9 , wherein the face of the closure plate is frusto-conical, causing the distally facing surface of the flange to become frusto-conical. 
     
     
         11 . The method as defined in  claim 10 , wherein the conical area of the face of the closure plate has a slope in the range from 8 to 15 degrees. 
     
     
         12 . The method as defined in  claim 10 , further comprising the step of machining the distally facing surface of the flange to a flat surface. 
     
     
         13 . The method as defined in  claim 9 , wherein the distal end surrounded by the distal facing surface is located within an annular chamber having a cylindrical inner diameter substantially equal to an outer diameter of the flange. 
     
     
         14 . The method as defined in  claim 9 , further comprising the step of applying a weld bead around an exterior fillet joining the flange with the tubular member. 
     
     
         15 . The method as defined in  claim 14 , further comprising the step of machining the weld bead to a desired radius for the exterior fillet. 
     
     
         16 . The method as defined in  claim 9 , wherein step (a) comprises deforming the distal end of the tubular member with a conically shaped punch to create a conical shape to create conical flange, then deforming the conical flange with a flat punch to create the a flat shape for the flange. 
     
     
         17 . The method as defined in  claim 9 , wherein step (f) creates a sharp interior corner at the junction. 
     
     
         18 . A method of forming a metal stub end fitting for a pipe, comprising:
 (a) forming a circumferentially extending flange on a distal end of a tubular member, the flange and the tubular member defining a junction with an interior radius;   (b) providing a die having a cylindrical chamber with proximal and distal ends, the distal end being surrounded by a distally facing surface, the distally facing surface surrounding the distal end being located within an annular chamber having a cylindrical inner diameter substantially equal to an outer diameter of the flange;   (c) inserting the tubular member into the distal end of the chamber with the flange in contact with the distally facing surface;   (d) securing a closure plate to a distal side of the die, trapping the flange within a cavity between the distally facing surface and a face on the closure plate, the face of the closure plate being frusto-conical;   (e) providing a plunger having a cylindrical portion and an external annular shoulder, the cylindrical portion of the plunger having an outer diameter substantially equal to an inner diameter of the tubular member;   (f) inserting the cylindrical portion of the plunger into the tubular member and past the flange, engaging a proximal end of the tubular member with the external shoulder and applying a force that shortens a length of the tubular member and causes metal at the junction to flow, decreasing the interior radius and causing the distally facing surface of the flange to become frusto-conical;   (g) machining the distally facing surface of the flange to a flat surface;   (h) applying a weld bead around an exterior fillet joining the flange with the tubular member; and   (i) machining the weld bead to a desired radius for the exterior fillet.   
     
     
         19 . The method as defined in  claim 18 , wherein step (f) creates a sharp interior corner at the junction. 
     
     
         20 . The method as defined in  claim 19 , wherein the conical area of the face of the closure plate has a slope in the range from 8 to 15 degrees.