Leak-proof tube fitting assembly structure

A leak-proof tube fitting assembly structure, comprising a liquid tube, a liquid tube fitting, and a nut for locking and connecting the liquid tube and the liquid tube fitting;

• the liquid tube fitting having a first connecting end, a first threaded connecting portion and a second connecting end that are axially arranged in sequence in a forward direction, the first threaded connecting portion having a first external thread, the first connecting end having an outer diameter less than that of the first threaded connecting portion;
• an interior of the nut being provided with a first sealing member, a second sealing member and a first internal thread that are axially arranged in sequence in the forward direction;
• one end of the liquid tube being sleeved on a periphery of the first connecting end, the nut being sleeved on a periphery of the liquid tube and screwed to the first threaded connecting portion, the first internal thread being mated with the first external thread, the first sealing member and the second sealing member being respectively deformed and sealed between an inner wall surface of the nut and an outer wall surface of the liquid tube by a locking and pressing action of the nut to prevent liquid leakage, the second sealing member and the first sealing member being located at front and rear ends of the first connecting end, respectively;
• wherein the nut has a pressing portion that extends axially and is located between the first sealing member and the second sealing member, the interior of the nut is formed with a first positioning groove and a second positioning groove that are axially arranged in sequence in the forward direction and spaced apart from each other, the first sealing member and the second sealing member are respectively positioned in the first positioning groove and the second positioning groove and partially extend out of the pressing portion, and the pressing portion is pressed against the outer wall surface of the liquid tube.