The article discloses the concept of a bolted connection, a screw connection. The main fasteners are considered.
The main threaded fasteners are screws, bolts, nuts and studs. A bolt is a product in the form of a cylindrical rod, with an external thread at one end, and a turnkey head at the other. Fixture is carried out thanks to a nut or a threaded hole in the connected products. The details of the bolted connection are the bolt itself , the nut and the washer.
The washer serves to protect the surface of the part from damage that may be caused by the rotating parts of the bolt and nut, as well as to prevent unwinding of the connection.
To perform multiple assembly and disassembly of products without violating the integrity of their individual parts, a bolt connection is used, which refers to detachable connections. Its main advantage is that it does not require sophisticated machine tools.
The bolted connection is used to assemble parts of small thickness. To make the connection, it is enough to make cylindrical holes of a slightly larger diameter so that the bolt rods freely pass through them and not damage the thread. Bolted connection requires a lot of space, it increases the weight and dimensions of the structure. But if necessary, for example, in case of failure, it is easy to replace. It provides significant reliability and structural strength.
Bolting can be done in two ways. First: a bolt with a gap is inserted into the holes of the parts to be connected. Next, the nut is tightened, which creates pressure between the parts - this prevents their divergence and shear under the action of axial and transverse forces due to friction. The second method is used less frequently, and consists in the tight penetration of the bolt into the hole of the connection parts, which prevents a shift under the influence of transverse forces. In this case, the hole of the part and the bolt shaft are machined with high accuracy, and the bolt is thinner with the same lateral force.
The manufacture of bolts is carried out from a shaped bar, which can be hexagonal or of another profile, on automatic machines or screw-cutting lathes. The thread of the bolts is cut or rolled on the workpieces that are obtained from the rod by hot heading. The length of the thread on the bolts is directly related to the thickness of the washer, the height of the nut, the thread reserves below and above the joint.
A screw is a cylindrical rod that has thread at one end and a conical, cylindrical or hemispherical head at the other. Compared to a bolted connection, the role of the nut in the screw connection is assigned to the last joined part, in which a threaded hole is made. Other components of the connection are between it and the screw head. A washer can be installed under the semicircular or cylindrical head. By appointment, the screws are divided into installation and mounting, that is, connecting.
Screw connection is common and quite often used in instrumentation. Screw connection parts - for example, a housing and a part to be attached to it, a flange or a cover.
When making a screw connection, the screw is screwed into the housing and requires little space, which reduces the weight and dimensions of the structure. But during assembly, the thread in the housing, if it is made of cast iron or aluminum, may be damaged. Therefore, in the event of a break, it is difficult to remove the remaining part of the screw from the thread.
Bolt and screw connections are standardized and replace each other. Therefore, they are widely used in many engineering industries to obtain detachable joints.