High-tensile, thin-wall differential threaded coupling

Abstract

The disclosed embodiments include a differential coupling system, a method of coupling a first mandrel to a second mandrel and a coupler. In one embodiment, the system includes a first mandrel having a first external thread about an external surface of the first mandrel. The system also includes a second mandrel having a second external thread about an external surface of the second mandrel. The system further includes a coupler that includes a first internal thread that complements the first external thread of the first mandrel and a second internal thread that complements the second external thread of the second mandrel. The system further includes an aligning pin configured to engage a first aligning hole of the first mandrel and a second aligning hole of the second mandrel to restrict axial rotation between the first mandrel and the second mandrel when the first mandrel is engaged to the second mandrel.

We claim: 
     
         1 . A differential threaded coupling system comprising:
 a first mandrel having a first external thread about an external surface of the first mandrel;   a second mandrel having a second external thread about an external surface of the second mandrel;   a coupler comprising a first internal thread that complements the first external thread of the first mandrel and a second internal thread that complements the second external thread of the second mandrel; and   an aligning pin configured to engage a first aligning hole of the first mandrel and a second aligning hole of the second mandrel to restrict axial rotation between the first mandrel and the second mandrel when the first mandrel is engaged to the second mandrel.   
     
     
         2 . The system of  claim 1 , wherein each tooth of the first external thread and second external thread has a reverse lead flank angle of approximately −3 to −30 degrees and a trailing flank angle of approximately 30 to 60 degrees. 
     
     
         3 . The system of  claim 2 , wherein the reverse lead angle is approximately −7 degrees and the trailing flank angle is approximately 45 degrees. 
     
     
         4 . The system of  claim 1 , wherein the first external thread and first internal thread have a first thread pitch and the second internal thread and second external thread have a second thread pitch, the second thread pitch being less than the first thread pitch, such that rotation of the coupler results in an engagement rate of the coupler to the second mandrel that is greater than a disengagement rate of the coupler to the first mandrel. 
     
     
         5 . The system of  claim 1 , wherein the coupler comprises a window for viewing the first mandrel and second mandrel when the first and second mandrels are coupled to the coupler. 
     
     
         6 . The system of  claim 1 , further comprising a plurality of port interfaces, each port interface forming a coupling between a first conduit of the first mandrel and a second conduit of the second mandrel. 
     
     
         7 . The system of claim of  claim 6 , wherein the plurality of port interfaces comprises an electrical connector, and wherein the electrical connector is coupled to a first conduit comprising an electrical conduit, and a second conduit comprising an electrical conduit. 
     
     
         8 . The system of claim of  claim 6 , wherein the plurality of port interfaces comprises a hydraulic connector, and wherein the hydraulic connector is coupled to a first conduit comprising a fluid conduit, and a second conduit comprising a fluid conduit. 
     
     
         9 . A method of coupling a first mandrel to a second mandrel, the method comprising:
 aligning a first end of a first mandrel to a second end of a second mandrel, the first mandrel having a first external thread about an external surface of the first mandrel and the second mandrel having a second external thread about an external surface of the second mandrel;   threading a coupler to the first mandrel to engage a first internal thread of the coupler to the first external thread of the first mandrel, wherein the first internal thread and first external thread have a first thread pitch; and   threading the coupler to the second mandrel to engage a second internal thread of the coupler to the second external thread of the second mandrel, wherein the second internal thread and second external thread have a second thread pitch,   wherein the second thread pitch is less than the first thread pitch, such that rotating the coupler relative to the first mandrel and second mandrel simultaneously results in the coupler engaging the second mandrel at a faster rate than the coupler disengages the first mandrel, and the second mandrel being drawn towards the first mandrel until the first end of the first mandrel engages the second end of the second mandrel.   
     
     
         10 . The method of  claim 9 , wherein aligning the first end of the first mandrel to the second end of the second mandrel comprises aligning an aligning pin with a first aligning hole of the first mandrel and a second aligning hole of the second mandrel, wherein the aligning pin is configured to restrict axial rotation between the first mandrel and the second mandrel when the first mandrel is engaged to the second mandrel. 
     
     
         11 . The method of  claim 9 , wherein aligning the first end of the first mandrel to the second end of the second mandrel comprises aligning a plurality of port interfaces, the method further comprising coupling a first conduit of the first mandrel to a second conduit of the second mandrel at each of the plurality of port interfaces. 
     
     
         12 . The method of  claim 11 , wherein the plurality of port interfaces comprises an electrical connector, and wherein each electrical connector is coupled to a first conduit comprising an electrical conduit, and a second conduit comprising an electrical conduit. 
     
     
         13 . The method of  claim 11 , wherein the plurality of port interfaces comprises a hydraulic connector, and wherein each hydraulic connector is coupled to a first conduit comprising a fluid conduit, and a second conduit comprising a fluid conduit. 
     
     
         14 . The method of  claim 9 , further comprising aligning a first visual indicator of the first mandrel to a second visual indicator of the second mandrel to align the first end of the first mandrel to the second end of the second mandrel. 
     
     
         15 . The method of  claim 14 , further comprising visually determining if the first end of the first mandrel is aligned with the second end of the second mandrel by observing the first mandrel and second mandrel through a window of the coupler. 
     
     
         16 . The method of  claim 9 , wherein each of the first external thread and second external thread has a reverse lead flank angle of approximately −3 to −30 degrees and a trailing flank angle of approximately 30 to 60 degrees. 
     
     
         17 . The method of  claim 16 , wherein the reverse lead angle is approximately −7 degrees and the trailing flank angle is approximately 45 degrees. 
     
     
         18 . A coupler comprising:
 a cavity having a first end for receiving a first mandrel and a second end for receiving a second mandrel;   a first internal thread at the first end, the first internal thread having a thread profile that complements a first external thread of the first mandrel, wherein the first internal thread and first external thread have a first thread pitch; and   a second internal thread having a thread profile that complements a second external thread of the second mandrel, wherein the second internal thread and second external thread have a second thread pitch, the second thread pitch being less than the first thread pitch such that rotating the coupler relative to the first mandrel and second mandrel simultaneously results in the coupler engaging the second mandrel at a faster rate than the coupler disengages the first mandrel.   
     
     
         19 . The coupler of  claim 18 , further comprising a window to provide a view of the first mandrel and second mandrel when the first mandrel and second mandrel are engaged by the coupler. 
     
     
         20 . The coupler of  claim 18 , further comprising at least one visual indicator indicative of a rotational position of the coupler with respect to at least one of the first mandrel and the second mandrel.