What do you mean by thread profile, large diameter, small diameter and medium diameter?

On the section passing through the thread axis, the outline shape of the thread is called tooth profile. The included angle between two adjacent tooth surfaces is called tooth profile angle. The tooth profile of common thread is triangular, and the tooth profile angle is 60.

2. Large diameter, small diameter and medium diameter

Large diameter refers to the diameter of an imaginary cylinder or cone that coincides with the top of external thread and the bottom of internal thread. The major diameter of the external thread is represented by D, and the major diameter of the internal thread is represented by D. The minor diameter refers to the diameter of an imaginary cylinder or cone which coincides with the tooth bottom of the external thread and the tooth top of the internal thread. The minor diameter of external thread is represented by d 1, and the minor diameter of internal thread is represented by D 1.

Imagine a cylinder (or cone) between a large diameter and a small diameter. In its axial section, the tooth width and groove width on the plane straight line are equal, so the diameter of the imaginary cylinder is called the middle diameter, which is expressed by d2 (or D2).

3. Number of rows

The number of spirals forming a thread is called the number of lines. There are single thread and multi-thread which are evenly distributed on the section perpendicular to the axis.

4. Lead

The axial distance between two adjacent teeth on the pitch line corresponding to two points is called pitch. On the same helix, the axial distance between two adjacent teeth corresponding to two points on the pitch line is called lead. The relationship between the number of rows n, the distance p and the lead s is: s = n p.

5. Direction of rotation

Seen along the axis, a thread that rotates clockwise becomes a right-handed thread, and a thread that rotates counterclockwise is called a left-handed thread.