High performance fitting

Claim 1

A tube fitting comprising: a body member having a through bore and a recess at one end of the boRe defining an axially inwardly narrowing flared camming surface extending at an angle to the axis of the bore of approximately 12* to 15* and an annular shoulder for abutment of a tube end extended coaxially inwardly through said recess; a nut member having a through bore defined by an axially inwardly widening flared camming surface and an axially outer cylindrical surface for coaxial extension of the tube end therethrough, the diameter of said cylindrical surface being greater than the outer diameter of the tube end to define an annular clearance space therebetween, said nut member being associated with said body member for selective advancement of said nut member camming surface toward said body member; and a sleeve member coaxially received in said nut member bore and body member recess, said sleeve member having a deflectible nose portion provided with an annular tube biting means having an inner diameter of approximately 0.004 to 0.006 inch larger than the nominal outer diameter of the tube end, a substantially rigid annular mid-portion, a rear portion including a forward end defining a radially outer flared reaction surface and a radially inner tube supporting surface, said nut member camming surface and sleeve reaction surface being at an angle of approximately 37* to 40* to the axis of the nut and sleeve, and a plurality of annularly spaced fingers cantilevered fully rearwardly from said forward end and provided with distal radially outturned shoulder means having an unconstricted outer diameter greater than the diameter of said cylindrical nut member surface, said fingers having an unconstricted inner diameter throughout their length approximately 0.006 to 0.010 inch larger than the nominal outer diameter of the tube end and the difference between said finger inner diameter and tube end outer diameter being at least the difference between said outer diameter of said shoulder means and the diameter of said cylindrical nut member surface, said nut camming surface, sleeve member reaction surface, and body member camming surface being arranged angularly to the axis of the fitting suitably to cause as a result of make-up of the fitting said tube supporting surface to be constricted sufficiently to constrict the tube end therein to a preselected amount, said tube biting means concurrently to bite into the tube end to a preselected amount, and said fingers to be deflected radially inwardly an amount less than that of said tube supporting surface and at least equal to said difference between said outer diameter of said shoulder means and the diameter of said cylindrical nut member surface while maintaining the diameter of said nut member cylindrical surface substantially constant whereby said sleeve is sealingly secured to said tube end with said shoulder means being arranged to pass said nut member freely axially outwardly as desired.