Fasteners are a type of mechanical parts used for fastening connections, which should be extremely extensive. The characteristics of fasteners: a wide variety of specifications, different performance and uses, and a high degree of standardization, serialization, and generalization. Therefore, some fasteners that have national (industry) standards are called standard fasteners, or standard parts for short.

Because the specifications, dimensions, tolerances, weight, performance, surface conditions, marking methods of each specific fastener production, as well as the specific requirements for acceptance inspection, marking and packaging, are specified in several countries ( Industry) standards, such as the metric system, the German system, and the imperial system. Fasteners are the most widely used mechanical basic parts. With my country's accession to the WTO in 2001, it has entered the ranks of major international trading nations. my country's fastener products are exported in large quantities to countries around the world, and fastener production outlets from all over the world are also pouring into the Chinese market. Fasteners, as one of my country’s largest import and export products, are in line with international standards, which is of great significance to promote Chinese fastener companies to the world and to promote fastener companies to fully participate in international cooperation and competition. Strategic significance.

Fasteners usually include the following 12 types of parts:

1. Bolt: a type of fastener consisting of two parts, a head and a screw (cylinder with external threads), which need to be matched with a nut to fasten and connect two parts with through holes. This type of connection is called bolt connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolt connection is a detachable connection.

2. Studs: There are no heads, only fasteners with threads on both ends. When connecting, one end of it must be screwed into the part with internal threaded hole, the other end must pass through the part with through hole, and then the nut is screwed on, even if the two parts are tightly connected as a whole. This type of connection is called a stud connection, which is also a detachable connection. It is mainly used where one of the connected parts has a large thickness, requires a compact structure, or is not suitable for bolt connection due to frequent disassembly.

3. Screws: It is also a type of fasteners composed of two parts, a head and a screw, which can be divided into three categories according to their uses: machine screws, set screws and special purpose screws. The machine screw is mainly used for a tightening connection between a part with a threaded hole and a part with a through hole, without the need of a nut. (This connection form is called a screw connection, which is also a detachable connection. Cooperate with the nut, used for the fastening connection between two parts with through holes.) The set screw is mainly used to fix the relative position between the two parts. Special purpose screws such as eyebolts are used for lifting parts.

4. Nut: with internal threaded hole, the shape is generally flat hexagonal cylinder, there are also flat square cylinder or flat cylinder, with bolts, studs or machine screws, used to fasten and connect two Parts to make it a whole.

5. Self-tapping screws: similar to machine screws, but the thread on the screw is a special thread for self-tapping screws. It is used to fasten and connect two thin metal components to make them into a whole. Small holes need to be made in the component in advance. Because this kind of screw has high hardness, it can be directly screwed into the hole of the component to form the component. Responsive internal thread. This type of connection is also a detachable connection.

6. Wood screws: They are also similar to machine screws, but the thread on the thread is a special wood screw thread, which can be screwed directly into the wooden component (or part) to use a metal with a through hole (or Non-metal) parts are fastened together with a wooden component. This connection is also a detachable connection.

7. Washer: A type of fastener with an oblate ring shape. It is placed between the supporting surface of bolts, screws or nuts and the surface of the connected parts, which increases the contact surface area of ​​the connected parts, reduces the pressure per unit area and protects the surface of the connected parts from damage; another type of elastic washer, It can also prevent the nut from loosening.

8. Retaining ring: It is installed in the shaft groove or hole groove of the machine and equipment, and it prevents the parts on the shaft or hole from moving left and right.

9. Pins: Mainly used for parts positioning, and some are also used for connecting parts, fixing parts, transmitting power or locking other fasteners.

10. Rivet: A type of fastener composed of two parts, a head and a nail shaft, used to fasten and connect two parts (or components) with through holes to make them into a whole. This type of connection is called rivet connection, or riveting for short. Belong to and non-detachable connection. Because to separate the two parts connected together, the rivets on the parts must be broken.

11. Assemblies and connection pairs: Assemblies refer to a type of fastener supplied in combination, such as a combination of a certain machine screw (or bolt, self-supplied screw) and a flat washer (or spring washer, lock washer) Supply; connection pair refers to a type of fastener supplied by a combination of a certain special bolt, nut and washer, such as a high-strength large hexagon head bolt connection pair for steel structures.

12. Welding nails: Because of the heterogeneous fasteners composed of light energy and nail heads (or no nail heads), they are fixedly connected to a part (or component) by welding so as to be connected with other parts. .