An article about the bolts

.

Definition and construction of bolts

Definition

A bolt is a fastener consisting of two parts: a head and a screw (a cylinder with external threads). It needs to be used in conjunction with a nut to firmly connect two parts with a through hole. This type of connection is called a bolted connection. If the nut is unscrewed from the bolt, then the two parts can be separated, so the bolt connection is a detachable connection.

Constitute
The bolt is mainly composed of the following two parts:
Head: The head of the bolt has a variety of shapes, such as hexagonal, square, etc., of which the hexagonal head is the most common. The shape and size of the head are designed for easy tightening and removal using tools such as wrenches. The head may also have grooves or other structures to facilitate the application of torque during tightening.
Screw: The screw is the main part of the bolt, which has external threads and can be matched with the internal thread of the nut to achieve tightening. The length and diameter of the screw are determined according to the specific application requirements to meet different fastening requirements.

Scope of application of bolts

Machinery Manufacturing:

Bolts are indispensable fasteners in the manufacture of machinery. They are used to connect and secure various mechanical components such as engines, transmissions, housings, racks, etc. Bolting ensures stability and reliability between mechanical components while facilitating service and replacement.
Construction project:
In construction projects, bolts are often used to connect steel structural parts, such as steel beams, steel columns, steel trusses, etc. Steel structure building has the advantages of high strength, light weight and fast construction speed, and bolt connection is one of the important means to realize these advantages. The bolted connection ensures a tight connection and overall stability between steel structural parts.
Automotive industry:
In the automotive industry, bolts are used to connect various parts of the car, such as the engine, transmission, chassis, body, etc. Bolted connection not only requires tight and reliable, but also requires a certain anti-vibration and anti-fatigue properties. In addition, with the intensification of the trend of automobile lightweight, more and more lightweight materials such as aluminum alloy are applied in automobile manufacturing, which also puts higher requirements on the performance of bolts.
Aerospace:
In the aerospace sector, bolting also plays an important role. Since aerospace spacecraft have extremely high requirements for weight, strength and reliability, it is necessary to use bolts with special properties such as high strength, corrosion resistance and high temperature resistance. These bolts need to be rigorously designed and tested to ensure good fastening performance in extreme environments.
Energy & Chemicals:
In the energy and chemical industries, bolts are also widely used in the connection of various equipment and pipelines. For example, in the oil, gas and other energy fields, bolted connections are used to connect pipelines, valves, pumps and other equipment; In the chemical industry, bolts are used to connect containers and equipment such as reactors and storage tanks. These devices and pipes are often subjected to high temperature, high pressure and corrosive media, which requires the use of high-quality screws

Classification and use of bolts

By head shape:

Hexagon head bolt: The most common type of bolt with six equal-sided heads for easy tightening and removal using tools such as wrenches.
Round head bolt: The head is round and is usually used when the bolt head needs to be hidden.
Square head bolt: The head is square, suitable for some specific occasions, such as the need for a larger contact area connection.
Countersunk bolt: The head is flat, and the diameter is usually smaller than the screw diameter, used in cases where the bolt head is required to sink completely into the surface of the connected piece.

Classified by connection force mode:

Ordinary bolts: for general connection occasions, without special consideration of the force mode.
Bolts for reaming holes: When in use, the bolts are tightly inserted into the holes made of reaming to prevent the dislocation of the workpiece, which is suitable for connections requiring accurate alignment and positioning.
Classification by thread length:
Full screw bolt: The whole screw is threaded.
Non-threaded bolt: The length of the screw part is threaded, and the rest is a plain rod.
Classification by thread type:
Coarse teeth bolt: thread type is large, suitable for general connection occasions.
Fine bolt: Smaller thread type, suitable for connections requiring higher precision and tightness.

Working principle

The working principle of the bolt is based on the physical principles of circular rotation of the inclined plane of the object and friction. When the bolt and nut are matched and tightened, the friction between the two gradually increases, so as to achieve the fastening of the connected part. At the same time, the bolt is subjected to a tensile force, which creates an opposite surface pressure between the bolt and the nut, further increasing the tightness of the connection.