Connection structure of internal thread of dumbell-like shaped symmetrical bidirectional tapered thread and traditional thread

A connection structure of an internal thread of a dumbbell-like shaped symmetrical bidirectional tapered thread and a traditional thread, comprising an external thread (9) and an internal thread (6) in mutual thread fit, wherein:

• a complete unit thread of the dumbbell-like shaped symmetrical bidirectional tapered internal thread (6) is a helical dumbbell-like shaped symmetrical bidirectional tapered hole (41) small in the middle and large in both ends;
• a thread body of the internal thread (6) is the helical bidirectional tapered hole (41) on an inner surface of a cylindrical body (2), and exists in a form of a “non-entity space”;
• a thread body of the external thread (9) is a helical special tapered body (7) on an outer surface of a columnar body (3) formed by a tooth body of the original traditional external thread (9) which is assimilated by the bidirectional tapered internal thread (6) due to cohesive contact with the bidirectional tapered internal thread (6), and exists in a form of a “material entity”;
• a left taper (95) is formed on a left conical surface of the symmetrical bidirectional tapered internal thread (6) and corresponds to a first taper angle (α1), and a right taper (96) is formed on a right conical surface of the symmetrical bidirectional tapered internal thread (6) and corresponds to a second taper angle (α2);
• the left taper (95) and the right taper (96) have opposite directions, and same and/or approximately same tapers;
• and
• the internal thread (6) and the external thread (9) contain the special tapered body by the bidirectional tapered hole till an inner conical surface of the bidirectional tapered hole and an outer conical surface of the special tapered body bear each other.