Pig tail bolt, sheep eye bolt, galvanized pig tail bolt, Dacromet screw

"1. Other names: root nut, anti loosening nut, and nut.
2. Usage: Lock the threaded outer joint or other pipe fittings.
The working principle of a nut is to use the friction force between the nut and the bolt for self-locking. However, the reliability of this self-locking will decrease under dynamic loads. In some important occasions, we will take some anti loosening measures to ensure the reliability of nut locking. Locking nuts are one of the anti loosening measures.
The anti loosening effect of a locking nut mainly depends on the interaction force between the nut and the bolt engagement thread. There are many ways to improve the interaction force between meshing threads, such as improving the structure of nut threads, roughening nylon nuts, and surface treatment of threads"

The process factors that affect the quality of high-strength fasteners include steel design, spheroidizing annealing, shelling and dephosphorization, pulling, cold heading, thread processing, heat treatment, and sometimes a combination of various factors.

Self tapping screws are threaded fasteners that are self drilled and matched with female threads in pre drilled holes of metal or non-metallic materials. When using self tapping screws, a flat pad is often required to protect the fastening surface. Traditional self tapping screws are prone to detachment of the flat pad, resulting in low work efficiency. In view of this, we propose a combination structure of stuck self tapping screws and spring pads to prevent the flat pad from falling off.

A washer is a common component that is circular or compressed into a circular shape. There are various forms of standard washers available, such as flat washers, spring washers, serrated lock washers, saddle washers, etc. The end face is mostly flat or compressed into a flat surface, so it fits in contact with the workpiece as a surface. Generally, when two workpieces are locked with washers, bolts, and nuts, the workpieces cannot move in any direction to achieve the purpose of tightening the two workpieces. In actual production, some workpieces are still required to perform appropriate translation in a certain direction after being locked. To achieve this requirement, the usual practice is to open a waist shaped hole on the workpiece that needs to be moved, and the Y-shaped bushing is inserted into the waist shaped hole and matched with the flat washer, as shown in Figure 8. The edge of the waist shaped hole on the workpiece is located in the space enclosed by the bushing and flat washer, and a gap is formed between the workpiece, the bushing, and the flat washer. This way, even if the bolt passes through the flat washer, the bushing, and the workpiece in sequence and is threaded and locked with the nut, The workpiece can still translate along the length direction of its waist shaped hole. Obviously, adopting this approach can achieve the requirement of proper translation of the workpiece. However, in actual assembly, the following shortcomings can still be found: firstly, before locking, the bushing, washer, and workpiece are separated from each other, making assembly more inconvenient; Secondly, the separation structure between the sleeve and washer is inconvenient to manage, and the disassembled washer and sleeve are easily lost, which affects their reuse.

Washers are divided into different types according to their structure and application: flat washers - Class C, large washers - Class A and C, extra large washers - Class C, small washers - Class A, flat washers - Class A, flat washers - chamfered washers - Class A, high-strength washers for steel structures, spherical washers, conical washers, square bevel washers for I-beams, square bevel washers for channel steels, standard spring washers, light spring washers, heavy spring washers, internal serrated lock washers, internal serrated lock washers Outer toothed lock washer, outer serrated lock washer, single ear stop washer, double ear stop washer, outer tongue stop washer, and stop washer for round nuts.