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Thread Structure Classification

Oct 16, 2019

The thread is divided into a triangular thread, a rectangular thread, a trapezoidal thread, and a zigzag thread according to its sectional shape (tooth shape). The triangular thread is mainly used for coupling (see threaded connection), and the rectangular, trapezoidal and zigzag threads are mainly used for transmission. The external thread of the thread distributed on the outer surface of the mother body is called the internal thread on the surface of the mother body. The thread formed on the cylindrical body is called a cylindrical thread, and the thread formed on the cone body is called a tapered thread. The thread is divided into two types of left-handed and right-handed in the direction of the spiral, and generally uses a right-handed thread. Threads can be divided into single-line and multi-wire, and most of the joints are single-wire; for transmission, fast-moving or high-efficiency is required, and double-line or multi-wire is used, but generally it does not exceed 4 lines.

The triangular thread is mainly used for coupling, and the rectangular, trapezoidal and zigzag threads are mainly used for transmission; the left-hand thread and the right-hand thread are divided into the right-hand thread according to the spiral direction; the right-hand thread is generally used; the single-line thread and the double line are divided according to the number of the spiral line. Thread and multi-thread thread; the connection is mostly single wire, the transmission uses double wire or multi-wire; according to the size of the tooth is divided into coarse thread and fine thread, etc., according to the use occasion and function, can be divided into fastening Thread, pipe thread, drive thread, special thread, etc.

Among the cylindrical threads, the triangular thread has good self-locking performance. It is divided into two types: coarse teeth and fine teeth. Fine teeth have small pitch, small lifting angle and better self-locking performance. They are often used in thin-walled tubes of small parts, vibration or variable load connections and fine-tuning devices. Pipe threads are used for tight fitting of the pipe. Rectangular threads have high efficiency, but they are often difficult to grind, and the inner and outer threads are difficult to screw and center, so they are often replaced by trapezoidal threads. The working edge of the serrated thread is close to the rectangular straight edge and is used to withstand the unidirectional axial force.

The shape of the conical thread is triangular, mainly relying on the deformation of the tooth to ensure the tightness of the thread pair, and is mostly used for the pipe fitting.

Sealing is divided into sealed threads and unsealed threads.


Contact person: Ms. Nancy Yue