Patent ID: 6776440
Filing Date: 2004-08-17
Classification: F16L

Abstract:
A structure for preventing slipping-off of a tube in a pipe joint made of resin, in which said structure comprises: a joint body (1) which has a receiving port (6) in one end portion, and in which an external thread portion (9) is disposed on an outer periphery of said receiving port; a tube (3) made of resin; and a union nut (2) which is loosely fitted onto an outer periphery of said tube, and in which an internal thread portion (18) that is to be screwed to said external thread portion (9) of said joint body (1) is disposed on an inner periphery, an annular flange portion (19) that is inward projected is disposed on one end, and a pressing edge portion (19a) is disposed in an inner diameter portion of said flange portion, andone end portion of said tube (3) is inserted into said receiving port (6) of said joint body (1) in a state where a diameter-increased portion (16) is formed and a diameter-increased root portion (17) where an opposite-insertion direction side inclination (16a) of said diameter-increased portion meets a tube outer face (30) which is parallel to an axial direction of said tube is formed, wherein a recess (20) is shaped in said diameter-increased root portion (17) of said tube (3), said recess being smaller in radius of curvature or angle than said diameter-increased root portion, said internal thread portion (18) of said union nut (2) is screw-fastened to said external thread portion (9) to cause said pressing edge portion (19a) to abut against said recess (20) of said tube (3), thereby pressing said one end portion of said tube (3) toward said joint body (1), an inner ring (4) having a bulge portion (11a) and a connecting portion (11b) at said one end said recess (20) is shaped into a curved portion (21) which is drawn by a radius of curvature that is smaller than a radius of curvature of said diameter-increased root portion (17).