Classification Of Bolts

 

Based on the force-bearing mode of the connection, they are divided into ordinary and reamed bolts. Based on the shape of the head, they are divided into hexagonal, round, square, countersunk, etc. Among them, the hexagonal head is the most commonly used. The countersunk head is generally used in places where a connection is required.
The English name of the riding bolt is U-bolt. It is a non-standard part. It is U-shaped, so it is also called U-bolt. There are threads on both ends that can be combined with nuts. It is mainly used to fix tubular objects such as water pipes or sheet objects such as car leaf springs. Because the way it fixes objects is like a person riding on a horse, it is called a riding bolt. Based on the length of the thread, it is divided into full thread and non-full thread. [2]
Based on the thread type, it is divided into coarse thread and fine thread. The coarse thread type is not shown in the bolt logo. Bolts are divided into eight grades according to performance level: 3.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9. Bolts above grade 8.8 (including grade 8.8) are made of low-carbon alloy steel or medium-carbon steel and are heat-treated (quenched + tempered), commonly known as high-strength bolts, and bolts below grade 8.8 (excluding grade 8.8) are generally known as ordinary bolts.
Ordinary bolts can be divided into three grades: A, B, and C according to manufacturing accuracy. Grades A and B are refined bolts, and grade C is rough bolts. For connecting bolts for steel structures, unless otherwise specified, they are generally ordinary rough grade C bolts. There are differences in the processing methods of different grades, and the corresponding processing methods are usually as follows: ① The bolt rods of grade A and B bolts are processed by lathes, with smooth surfaces and precise dimensions. The material performance grade is 8.8, which is complicated to manufacture and install, and the price is high, so they are rarely used; ② Grade C bolts are made of unprocessed round steel, the size is not precise enough, and the material performance grade is 4.6 or 4.8. The deformation is large during shear connection, but it is easy to install and has low production cost. It is mostly used for tensile connection or temporary fixation during installation.