Classification and introduction of fasteners for mechanical design, rich in content, recommended collection!

1. What are fasteners?

Fastener is the general name of a kind of mechanical parts used to fasten and connect two or more parts (or components) into a whole. Also known as standard parts in the market.

2. It usually includes the following 12 types of parts:

Bolts, studs, screws, nuts, self tapping screws, wood screws, washers, retaining rings, pins, rivets, assemblies and connecting pairs, welding nails.

(1) Bolt: it is a kind of fastener composed of head and screw (cylinder with external thread), which needs to be matched with 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 removable connection.

As shown below:

(2) Stud: it is a kind of fastener without head and only with external threads at both ends. When connecting, one end 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 when one of the connected parts has a large thickness, requires compact structure, or is not suitable for bolt connection due to frequent disassembly.

As shown below:

(3) Screw: it is also a kind of fastener composed of head and screw. It can be divided into three categories according to its purpose: steel structure 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 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.) The set screw is mainly used to fix the relative position between two parts. Special purpose screws, such as lifting eye screws, are used for hoisting parts.

As shown below:

(4) Nut: with internal thread hole, it is generally in the shape of flat hexagonal column, or flat square column or flat cylindrical. It is used to fasten and connect two parts together with bolts, studs or steel structure screws to make them a whole.

As shown below:

(5) Self tapping screw: similar to the screw, but the thread on the screw is a 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 the screws have high hardness, they can be directly screwed into the holes of the components to form corresponding internal threads in the components. This type of connection is also a detachable connection.

(6) Wood screw: it is similar to the screw, but the screw thread on the screw is a special thread for wood screw, which can be directly screwed into the wooden component (or part) to firmly connect a metal (or non-metal) part with a through hole with a wooden component. This connection is also a detachable connection.

(7) Washer: a kind of fastener with flat circular shape. It is placed between the support surface of the bolt, screw or nut and the surface of the connecting parts, which plays a role in increasing the contact surface area of the connected parts, reducing the pressure per unit area and protecting the surface of the connected parts from damage; Another kind of elastic washer can also prevent the nut from loosening.

(8) Retaining ring: it is installed in the shaft groove or hole groove of steel structure and equipment to prevent the 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, transmitting power or locking other fasteners.

(10) Rivet: a kind of fastener composed of head and nail rod, which is used to fasten and connect two parts (or components) with through holes to form a whole. This connection form is called rivet connection, or riveting for short. It is a non removable connection. Because to separate the two parts connected together, the rivets on the parts must be destroyed.

As shown below:

(11) Assembly and connection pair: assembly refers to a type of fastener supplied by combination, such as a machine screw (or bolt, self supplied screw) and a flat washer (or spring washer, lock washer); Connection pair refers to a kind of fastener that combines a special bolt, nut and washer, such as high-strength large hexagon bolt connection pair for steel structure.

(12) Welding nail: as a heterogeneous fastener composed of a bare rod and a nail head (or no nail head), it is fixedly connected to a part (or component) by welding, so as to connect with other parts.

As shown below: