There are many types of high-strength bolts, and their shapes are not the same. The external dimensions are ever-changing, but their main structure and the overall external shape are similar to each other. Based on these similarities, we divided it into three main parts: the head, the stem, and the threaded part.
1. Head: The main role of the head is to apply a reverse torque when the nut cooperates with the bolt to ensure that the nut has a sufficient tightening torque. There are many types of forms, mainly square, semi-circular and hexagonal heads. In addition, some non-standard high strength bolt head forms are specially designed by the designer according to the assembly needs.
2. Rod: The rod mainly plays a guiding role, especially the guide bolt. After assembly, it bears a certain radial shear force. It is required to cooperate with a small gap in the hole. Some bolts that only withstand the axial tensile force after assembly have less stringent requirements on the rod and larger tolerances on the outer circle size. For high-strength bolts, the contact portion between the rod and the head requires a certain rounded corner to avoid fracture of the part when subjected to large tensile forces, and to avoid cracks during heat treatment and cooling, which are important factors for processing.
3. Threaded part: The threaded part is the main part of the bolt, which mainly plays a role of fastening the connection. It can be divided into effective thread part, finishing part (retracting part) and thread end three parts; the three main elements of the thread: pitch, half-angle and pitch, directly affect the accuracy of the thread fit, but also important factors for processing attention.