It usually includes the following 12 types of parts:
Bolt: a kind of fastener consisting of head and screw (cylinder with external thread), which shall be matched with nut to fasten and connect two parts with through hole. This type of connection is called bolt connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolted connection is a removable connection.
Stud: a kind of fastener with no head and only threads on both ends. When connecting, one end of it must be screwed into the part with internal thread hole, and the other end must pass through the part with through hole, and then screw on the nut, even if the two parts are firmly connected as a whole. This type of connection is called stud connection, which is also a removable connection. It is mainly used in the case where one of the connected parts is thicker, requires compact structure, or is not suitable for bolted connection due to frequent disassembly.
Screw: it is also a kind of fastener composed of head and screw. It can be divided into three categories according to the use: machine screw, set screw and special purpose screw. The machine screw is mainly used for the fastening connection between a part with a fixed threaded hole and a part with a through hole, without the need for nut matching (this connection form is called screw connection, which is also a removable connection; it can also be matched with a nut, which is used for the fastening connection between two parts with a through hole.) Set screws are mainly used to fix the relative position between two parts. Special purpose screws, such as eyebolts, are used for hoisting parts.
Nuts: with internal threaded holes, generally in the shape of flat hexagon column, and also in the shape of flat square column or flat cylinder. They are used with bolts, studs or machine screws to fasten and connect two parts to make them a whole.
5. Self tapping screw: similar to machine screw, but the thread on the screw is special thread for self tapping screw. It is used to fasten and connect two thin metal components to make them a whole. Small holes need to be made on the components in advance. Because of the high hardness of this screw, it can be directly screwed into the holes of the components to form a corresponding internal thread in the components
6. Wood screw: It is also similar to the machine screw, but the screw thread on the screw is a special wood screw thread, which can be directly screwed into the wooden component (or part) to fasten a metal (or non-metal) part with a through hole to a wooden component. This connection is also a detachable connection.
7. Washer: a type of fastener with flat circular shape. It is placed between the supporting surface of bolts, screws or nuts and the surface of connecting parts to increase the contact surface area of connected parts, reduce the pressure per unit area and protect the surface of connected parts from damage; Another type of elastic washer can also prevent the nut from loosening.
8. Retaining ring: It is installed in the shaft groove or shaft hole groove of machines and equipment, and plays the role of preventing parts on the shaft or hole from moving left and right.
9. Pin: It is mainly used for positioning parts, and some can also be used for connecting parts, fixing parts, transferring power or fasteners in locking period.
10. Rivet: a kind of fastener consisting of head and rivet rod, which is used to fasten and connect two parts (or components) with holes to make them a whole. This type of connection is called rivet connection, or simply riveting. It is a non detachable link. Because if the two parts connected together are separated, the rivets on the parts must be broken.
11. Assembly and connecting pair: assembly is a type of fastener supplied in combination, such as a machine screw (or bolt, self supplied screw) and a flat washer (or spring washer, lock washer); The connection pair refers to a type of fastener that is supplied by combining some special bolts, nuts and washers, such as the connection pair of high-strength large hexagon bolts for steel structures.
12. Welding nail: a heterogeneous fastener consisting of a nail rod and a nail head (or no nail head), which is fixed and connected to a part (or component) by welding, so as to connect with other parts.