Bolt in detail
There is a specific terminology, without which it will be difficult to understand when discussing bolts. Therefore it is necessary to get acquainted with such definitions as thread, thread pitch, etc.
Thread is a spiral cut on the surface of the bolt's core part along a helical line with a constant pitch. There are many types of threading, methods and GOSTs. The most popular carving, which is widely used and used - is the metric carving.
Thread pitch is the height measured from one turn in the thread to the other. In thread the thread pitch is constant, it is observed according to GOSTs, measured in millimeters.
Threading - one thread rotation.
The length of the screwing is the length of the entire thread on the surface of the bolt's core.
Use of the bolt
The bolts are classified according to their intended purpose, they are: plowshare, machine-building, road and furniture. Depending on the place of application, the type of bolt and its strength class are different. For example, it is impossible to screw a furniture bolt for a unit in the power unit of the machine, if it is also less durable. And as a rule, the furniture bolts are made of less durable metal, which is not adapted to work under extreme conditions.
This means that it is necessary to clearly distinguish the types of bolts and their application areas. In addition to the four types listed, there is another classification for use.
Classification of bolts depending on application
- Black bolts. Manufactured by stamping. Typically, the material for stamping is high-carbon steel. These bolts are used for connecting in non-essential parts of the machine. This class is designed for rough assembly, only in those nodes where there will not be a heavy load, long monotonous fluctuations. The machining in the manufacture of rough bolts is carried out only when threading.
- Semi-clean bolts. Here, first, stamping is performed, and then the surface is machined. At the same time, not the entire bolt is machined, the bolt head is not subjected to machining, but this should not influence the appearance and mechanical properties. The head must exactly meet the requirements of GOST.The material for the bolts is medium carbon steel. This bolt is used in most joints, it can withstand continuous monotonous fluctuations, non-weak loads.
- Clean bolts. The material for the production can be alloyed steel, non-ferrous alloys and low-carbon steel. The processing of a clean bolt is carried out to the fullest, which means that all parts of the bolt pass through the machining. Due to the use of high-quality durable metals and alloys, the bolt can be used in important assemblies. And thanks to complete processing, they can be used in open places where the appearance is important.
To the listed it is necessary to add some explanations. One of the properties by which the quality of metal is classified is the amount of carbon in the steel. Accordingly, the less carbon in the steel, the better the steel itself turns out. In steels with a low carbon content, the level of durability and strength significantly increases.
To the note. To improve the quality of steel, to improve the structural strength is doping. This process involves the incorporation into the steel alloying elements, which can be: tungsten, vanadium, titanium, chromium, manganese, nickel and other metals and non-metals.
Classification by strength
The studs, bolts and screws have a subdivision for 11 classes of strength: 3.6;4.6;4.8;5.6;5.8;6.6;6.8;8.8;9.8;10.9;12.9.The first number to the point determines the nominal time resistance, it is measured in, to find is multiplied by 100. The second number, after the point, is the ratio of the yield stress to the time resistance in percent, is also measured in, to find is multiplied by 10. Accordingly,, the stronger the detail. In Russia, according to GOST, it is considered to be high-strength bolts that are in the range of strength from 6.8 to 12.9.
Bolt shapes
Thanks to a wide range of shapes, it is possible to do various design complexity, implement various designs. Depending on the situation and the type of connection, a completely non-standard bolt may be required. However, it is not difficult to find a suitable type, it is enough to determine the basic form first.
- Hexagonal head screws
- Hexagon bolts
- Eye bolts
- Anchor bolts
- Bolted flanges
- Bolts with a semicircular head
- Hinged bolts
This article will detail the last option in the list of bolt shapes.
Bolt of folding
It differs in its purpose and design. As in all bolts, there is a metal rod on which the thread is carved, but in contrast to all the known hexagon head bolt, here, instead of the head, a ring. The hole inside the ring allows the carabiner to be used in the attachment.
The head of the folding bolt is not only in the form of a ring, but also in the form of a hemisphere and fork. The design of the bolt and plug is designed specifically for articulated joints. The head in the form of a hemisphere allows you to make a fairly tight pressure when connecting with flexible and resilient surfaces. The main area of application of folding bolts is rigging.
Basically, the material for punching this type of bolt is steel with high or medium carbon content, as well as alloy steels, much less often low-carbon steels.
A particular advantage of the flap bolts is the strength and speed of the connection. For example, flap bolts are used in furniture connection points, even in the field, when you need to quickly fix the machine or device to the platform.
