Types Of Thread

Threads are divided into two categories according to their uses, namely connecting threads and transmission threads. As a professional fastener manufacturer, Xinchi Fastener Company has more than ten years of experience in the fastener field, and we also know a lot about the thread. Today we’d like to share the types of threads.

Connection threads

There are two types of connection threads, a common thread and a pipe thread, which are mainly used for the connection. There are four standard threads commonly used, namely: coarse thread, fine thread, pipe thread, and taper pipe thread.

The tooth shape of the common thread is an equilateral triangle (tooth shape Angle is 60°). The difference between fine thread and coarse thread is that the pitch of the fine thread is smaller than that of coarse thread under the condition of the same large diameter.

The tooth shape of pipe thread and cone thread is an isosceles triangle (tooth shape Angle is 55°). Pipe thread is mainly used for pipe connection of water pipes, oil pipes, gas pipes, etc. Pipe threads are classified into cylindrical pipe threads and conical pipe threads. Both are in inches and the pitch of the thread is expressed by the number of thread teeth in the 25.4mm thread length.

Pipe threads are divided into non-sealed pipe threads and sealing pipe threads.

Non-sealed pipe thread (G), the processing of the inner hole thread is pipe thread tap, and the processing of the external thread is dying.

Sealing pipe thread (R) requires high precision. There are two matching modes for sealing pipe thread: cylindrical internal thread and taper external thread form “column/cone” matching; Conical internal thread and conical external thread form “cone/cone” fit.

The dimension of the pipe thread is an approximation of the diameter of the pipe, not the outside diameter of the pipe. 1/2 DN15.

Pipe thread is how many teeth per inch indicate the thickness of the tooth type, converted to a decimal pitch. For example, the pipe thread of G1 “has 11 teeth along the axis, and its pitch is 25.4 divided by 11, which is 2.309.

The metric thread is expressed in pitch and the American British thread is expressed in thread teeth per inch.

The metric thread is 60 degrees equilateral teeth, the British thread is 55 degrees isosceles teeth, and the American thread is 60 degrees isosceles teeth.

Transmission threads

Transmission threads are threads used to transmit power or motion.

Trapezoidal thread: the tooth type is an isosceles trapezoidal thread, and the tooth type Angle is 30°. It is the most commonly used transmission thread. Compared with rectangular thread, the transmission efficiency of trapezoidal thread is slightly lower, but it has good technology, high root strength and good centering property. The lead screw of the machine tool uses a trapezoidal thread to transfer power in both directions. The thread code is denoted by Tr.

Serrated thread: A unidirectional drive thread with a tooth shape of an isosceles trapezoid. It has an Angle of 30° with the plumb line on one side and 3° on the other side, forming a 33° tooth Angle. Its teeth are serrated and code-named B. It is designed to withstand only one direction of power. Because its transmission efficiency and strength are higher than that of trapezoidal thread, it is often used in screw presses and hydraulic presses and other one-way force mechanism thread.

Rectangular thread: Mainly used for force transfer. Its characteristic is that the transmission efficiency is higher than other threads, but the strength is larger, so the application is limited.

Modular thread: that is, turbo worm thread. The tooth shape is 40 degrees. It has the characteristics of a large transmission ratio, compact structure, smooth transmission and good self-locking performance. It is mainly used for reducing gear.

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