High strength flexible ferrule

Abstract

A ferrule ( 120 ) for coupling a tube ( 112 ) to a fitting body ( 114 ) includes an outer cam surface ( 124 ) for bearing against the fitting body or another ferrule; an inner surface ( 126 ) defining a central bore ( 128 ) extending through a length of a body of the ferrule along a longitudinal direction from a bite edge ( 138 ) to a nut end ( 129 ); a recess surface ( 134 ) defining a counter bore extending from a bite end ( 137 ) to the bite edge ( 138 ), the bite edge ( 138 ) thereby recessed from the bite end ( 137 ).

1 . A ferrule for coupling a tube to a fitting body, the ferrule comprising:
 a nose portion including an outer cam surface for bearing against a fitting body or another ferrule to bend radially inward during assembly of the ferrule;   an inner surface defining a central bore extending through a length of a body of the ferrule along a longitudinal direction from a bite edge to a nut end;   a recess surface defining a counter bore extending from a bite end to the bite edge, the bite edge thereby recessed from the bite end a distance, X, along the longitudinal direction toward the nut end; and   a first thin section toward the bite end;   wherein an axially middle portion, between the first thin section and the nut end, is configured to bow radially outwardly during assembly of the ferrule such that the bite edge and a portion of the inner surface opposite the bite edge, relative to the axially middle portion, are engageable with the tube;   wherein a radial distance, A, from the recess surface to the outer cam surface at an axial location of the bite edge is 50% or greater than a radial distance, H, from the inner surface to the recess surface;   wherein the ferrule includes a nose angle, θ, defined by the longitudinal axis and the outer cam surface, the fitting body or the another ferrule includes a body seat angle defined by the longitudinal axis and a radially inwardly facing surface of the fitting body or the another ferrule, and the nose angle, θ, approximately matches the body seat angle of the fitting body or the another ferrule both before and after the nose bends radially inward during assembly of the ferrule, thereby reducing bending stress across a nose thickness, T, during makeup of the ferrule;   wherein the nose thickness, T, extends normal to a portion of the outer cam surface to an axial end, of the recess surface, that is opposite the bite end; and   wherein the entire portion of the outer cam surface is engageable with the radially inwardly facing surface of the fitting body or the another ferrule both before and after assembly of the ferrule.   
     
     
         2 . The ferrule of  claim 1 , wherein the inner surface includes a concave portion, thereby encouraging the axially middle portion of the ferrule to bow radially outwards when assembled. 
     
     
         3 - 7 . (canceled) 
     
     
         8 . The ferrule of  claim 1 , wherein X is between 0.5 and 2 times H. 
     
     
         9 . (canceled) 
     
     
         10 . The ferrule of  claim 1 , wherein an angle between the bite edge and the inner surface is between 75 and 115 degrees. 
     
     
         11 . (canceled) 
     
     
         12 . A fitting assembly for coupling a first tube to a fitting body, the fitting assembly comprising:
 a front ferrule for engagement with the fitting body; and   a back ferrule for engagement with a nut,   wherein, one of the front ferrule or the back ferrule is a ferrule according to  claim 1 .   
     
     
         13 - 19 . (canceled) 
     
     
         20 . The ferrule of  claim 1 , wherein
 a portion of the body of the ferrule has an outer cam surface for bearing against the fitting body or another ferrule and defines a central bore extending through a length of the portion of the body along the longitudinal direction;   wherein the nose portion has an outer cam surface for bearing against the fitting body or another ferrule and defines a bore extending through a length of the nose portion along the longitudinal direction;   and   wherein the outer cam surfaces have respective slopes forming a continuous outer surface, the continuous outer surface being free of an inflection point from at least an outermost axial extent of the nose portion to a position along the portion of the body from the nose portion equal to an axial length of the nose portion, wherein prior to assembly of the ferrule the outer cam surface includes a convex portion that extends along most of a length of the ferrule prior to assembly of the ferrule.   
     
     
         21 - 36 . (canceled) 
     
     
         37 . A fitting assembly for coupling a first tube to a fitting body, the fitting assembly comprising:
 a ferrule including:   a reduced thickness portion near a nut end of the ferrule, the reduced thickness portion being thinner than adjacent portions of the ferrule and configured to flex when the fitting assembly is made up;   a thin section toward the bite end of the ferrule, wherein an axially middle portion, between the thin section and the reduced thickness portion, is configured to bow radially outwardly during assembly of the ferrule such that the bite edge and a portion of an inner surface opposite the bite edge, relative to the axially middle portion, are engageable with the tube; and   a nut having a bearing surface for bearing against a bearing surface of the ferrule;   wherein the reduced thickness portion has a radial thickness less than any other portion of the ferrule between the nut end and a bite edge of the ferrule closest to the nut end.   
     
     
         38 . The fitting assembly of  claim 37 , wherein the ferrule further includes:
 a nose portion including an outer cam surface for bearing against the fitting body or another ferrule to bend radially inward during assembly of the ferrule;   the inner surface defining a central bore extending through a length of a body of the ferrule along a longitudinal direction from the bite edge to the nut end; and   a recess surface defining a counter bore extending from a bite end to the bite edge, the bite edge thereby recessed from the bite end a distance, X, along the longitudinal direction toward the nut end;   wherein a radial distance, A, from the recess surface to the outer cam surface at an axial location of the bite edge is 50% or greater than a radial distance, H, from the inner surface to the recess surface;   wherein the ferrule includes a nose angle, θ, defined by the longitudinal axis and the outer cam surface, the fitting body or the another ferrule includes a body seat angle defined by the longitudinal axis and a radially inwardly facing surface of the fitting body or the another ferrule, and the nose angle, θ, approximately matches the body seat angle of the fitting body or the another ferrule both before and after the nose bends radially inward during assembly of the ferrule, thereby reducing bending stress across a nose thickness, T, during makeup of the ferrule;   wherein the nose thickness, T, extends normal to a portion of the outer cam surface to an axial end, of the recess surface, that is opposite the bite end; and   wherein the entire portion of the outer cam surface is engageable with the radially inwardly facing surface of the fitting body or the another ferrule both before and after assembly of the ferrule.   
     
     
         39 . The fitting assembly of  claim 37 , wherein an angle of the bearing surface of the ferrule is between 3 and 10 degrees different than the an angle of the bearing surface of the nut, the angle mismatch thereby causing the reduced thickness portion to flex in a predetermined direction during make up. 
     
     
         40 . The fitting assembly of  claim 37 , wherein the bearing surface of the ferrule is about 5 degrees more or 5 degrees less than the bearing surface of the nut, the angle mismatch thereby causing the reduced thickness portion to flex in a predetermined direction during make up. 
     
     
         41 - 44 . (canceled) 
     
     
         45 . The fitting assembly of  claim 37 , wherein the ferrule is surface hardened. 
     
     
         46 . (canceled) 
     
     
         47 . The fitting assembly of  claim 37 , wherein the ferrule further includes an undercut between the inner surface and a nose portion. 
     
     
         48 - 49 . (canceled) 
     
     
         50 . The fitting assembly of  claim 37 , wherein a nose thickness, T, is 70% of a radial distance, H, or greater, wherein the radial distance, H, is from the inner surface to a recess surface defining a counter bore extending from a bite end to the bite edge. 
     
     
         51 - 52 . (canceled) 
     
     
         53 . The fitting assembly of  claim 37 , wherein the bite edge is the only bite edge axially opposite the portion of the inner surface relative to the axially middle portion. 
     
     
         54 . The fitting assembly of  claim 37 , wherein a radially inward facing surface of the reduced thickness portion flexes radially inward to compress into the first tube before adjacent portions of the ferrule. 
     
     
         55 . (canceled) 
     
     
         56 . A fitting assembly for coupling a tube to a fitting body, the fitting assembly comprising:
 the ferrule of  claim 1 ;   a fitting body or another ferrule including the radially inwardly facing surface for engaging the portion of the outer cam surface, wherein the radially inwardly facing surface is parallel to the portion of the outer cam surface both before and after assembly of the ferrule.   
     
     
         57 . (canceled) 
     
     
         58 . The ferrule of  claim 1 , wherein the entire portion of the outer cam surface is engaged with the radially inwardly facing surface of the fitting body or the another ferrule. 
     
     
         59 . The ferrule of  claim 1 , wherein prior to makeup of the ferrule, the entire portion of the outer cam surface is parallel to the radially inwardly facing surface; and
 wherein prior to makeup of the ferrule, a continuous portion of the ferrule spans an entire distance extending normally from the portion of the outer cam surface to the inner surface.   
     
     
         60 . The torque nut of  claim 1 , further including a second thin section toward the nut end, wherein an axially middle portion is between the first thin section and the second thin section. 
     
     
         61 . The fitting assembly of  37 , wherein the ferrule further includes:
 a body portion having an outer cam surface for bearing against the fitting body or another ferrule, wherein the inner surface defines a central bore extending through a length of the body portion along a longitudinal direction; and   a nose portion having an outer cam surface for bearing against the fitting body or another ferrule and having a recess surface defining a bore extending through a length of the nose portion along the longitudinal direction;   wherein an inner diameter of the nose portion is greater than an inner diameter of the body portion; and   wherein the outer cam surfaces have respective slopes forming a continuous outer surface, the continuous outer surface being free of an inflection point from at least an outermost axial extent of the nose portion to a position along the body portion from the nose portion equal to an axial length of the nose portion, wherein prior to assembly of the ferrule the outer cam surface includes a convex portion that extends along most of a length of the ferrule.