The production process is generally preceded by a screw shape, which is what we call the screw industry. After that, it is the screw thread, which is what we often say. Or called silk. After the gums are good, they become natural screws, and the natural screws, such as the iron color screws, generally need to be plated.
The profile of the thread is referred to as a tooth profile on a section through the axis of the screw thread. The angle between the adjacent sides of the teeth is called the angle of the teeth. Commonly used threads have a triangular shape with a tooth angle of 60°.
The large diameter refers to the diameter of an imaginary cylinder or a tapered surface that coincides with the root of the external thread of the screw and the root of the internal thread. The large diameter of the external thread is denoted by d, and the large diameter of the internal thread is denoted by D. The small diameter refers to the diameter of the imaginary cylinder or the tapered surface which coincides with the root of the external thread and the crest of the internal thread. The small diameter of the external thread is denoted by d1, and the small diameter of the internal thread is denoted by D1.
Between the large diameter and the small diameter, a cylindrical surface (or a tapered surface) is assumed. In the axial section, the tooth width and the groove width on the plain line are equal, and the diameter of the imaginary cylinder is called the medium diameter, and d2 is used. Or D2) Number of lines: The number of threads forming a thread is called the number of lines. There are single and multi-thread threads, and the multi-thread threads are evenly distributed in a section perpendicular to the axis.