Patent ID: 6942254
Filing Date: 2005-09-13
Classification: E21B,F16B,Y10T

Abstract:
1. In a sucker rod combination with a coupler interconnecting a pair of oppositely directed pin ends, wherein the sucker rods each include a male threaded end region with a terminal end face, a spaced apart radial shoulder having a flat engagement surface adjacent a different cross-section pin neck intervening between the radial shoulder and the adjacent side of the male thread, and the coupling having an interior female thread matingly receiving the male threads and end surfaces for contacting the engagement surfaces of the radial shoulders on inserted pin ends, wherein the combination comprises: the pin ends having prepared end face to engagement surface dimensions preselected in relation to coupler length dimensions such that oppositely inserted pin ends in the coupling stretch the pin necks to selected tension levels when threaded to a predetermined depth past hand tight engagement of the engagement faces against the associated coupler ends, to compel engagement and lockup of the male and female threads, and concurrently placing the end faces of the pin ends in compressive prestress to force the central region of the coupler in tension to form a unified structure resistant to multiple loading cycles during sucker rod operation.