I. Introduction
Hexagon bolts are hexagon-head bolts (partially threaded)-Class C and hexagon-head bolts (fully threaded)-Class C, also known as hexagon-head bolts (coarse), coarse hexagon-head bolts and black iron screws. See: SH3404, HG206 13, HG20634, etc. Hexagon bolts refer to fasteners consisting of head and screws. Bolts are divided into iron bolts and stainless steel bolts according to materials. Iron is divided into grade 4.8 bolts and grade 8.8 bolts. Stainless steel bolts are made of stainless steel SUS20 1 bolts, SUS304 bolts and SUS3 16 bolts.
Second, the standard size
The standard of external hexagon bolt is DIN, ANSI, BS, GB and other materials: stainless steel or carbon steel or the specified diameter is generally 5 mm ~ 20 mm,1/4 "~ 3/4". Length: 8 mm ~ 200 mm, 5/ 16 "~ 8 "? . Thread: metric, thick, thin and English, with mechanical properties of 4.8, 5.8, 6.8, 8.8, 9.8, 10.9, 12.9. Surface treatment methods generally include natural color, zinc plating, blackening and nickel plating. ? The external hexagon bolt M6*30 can accurately describe the bolt with a diameter of 6MM and a thread length of 30MM.
Third, classification
1, according to the stress mode of the connection, there are ordinary holes and reaming holes. Bolts used for reaming should match the size of the hole and be used when subjected to lateral force.
2. According to the shape of the head, there are hexagonal head, round head, square head and countersunk head. Generally, countersunk heads are used where the surface is smooth and there is no protrusion after connection, because countersunk heads can be screwed into parts. Round heads can also be screwed into parts. The tightening force of the square head can be larger, but the size is larger. Hexagons are the most commonly used.
In addition, in order to meet the need of locking after installation, there is a hole in the head and a hole in the rod, which can prevent the bolt from loosening during vibration. Some polished rod unthreaded bolts need to be made thin, which are called thin waist bolts. This kind of bolt is beneficial to the connection under variable force. There are special high-strength bolts on the steel structure. The head will get bigger and the size will change. In addition, there are special uses: T-groove bolts are the most commonly used in machine tool fixtures, which have special shapes and have to be cut off on both sides of the head. Anchor bolts are used to connect and fix the machine and the ground, and they have many shapes, such as U-shaped bolts. There are also special studs for welding. One end is threaded and the other end is not. It can be welded on the part, and the nut can be directly screwed on the other side.
Of course, in our daily use, there will definitely be some faults. What should we do when the external hexagon bolt fails? Generally speaking, bolts in machines such as diesel engines are recommended to be used once. If used many times, accidents may occur. However, some units will also encounter the problem of replacing the external hexagon bolt regularly, but they will still encounter the problem of machine failure, so it is necessary to consider whether the force is too large when installing. The external hexagon bolt introduced by Bian Xiao today is here. I hope I can help you.
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