Bolt classification
Time：2022/4/29 Browse：1742
According to the stress mode of connection: ordinary and reamed holes. According to the shape of the head: hexagonal head, round head, square head, countersunk head and so on. The hexagonal head is the most commonly used. Generally, countersunk head is used where connection is required. [1]
The English name of riding bolt is U-bolt. It is a non-standard part and its shape is U-shaped, so it is also called U-bolt. There are threads at both ends and can be combined with nuts. It is mainly used to fix tubular objects such as water pipes or sheet objects such as leaf springs of cars. It is called riding bolt because its way of fixing objects is the same as that of people riding on horses. According to the length of thread, it can be divided into full thread and non full thread. [2]
According to the thread profile, it is divided into coarse tooth and fine tooth. The coarse tooth profile is not displayed in the mark of the bolt. Bolts are divided into eight grades according to their performance grades: 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 heat treated (quenching + tempering), which are generally referred to as high-strength bolts, and bolts below grade 8.8 (excluding grade 8.8) are generally referred to as ordinary bolts. [2]
Ordinary bolts can be divided into three grades A, B and C according to the manufacturing accuracy. Grade A and B are refined bolts and grade C is rough bolts. Unless otherwise specified, connecting bolts for steel structures are generally ordinary coarse grade C bolts. The bolt is made of Grade A and grade B with the following processing methods: ① the bolt is made of Grade 8 and grade B with the following precision processing methods, and the price is very high; ② Grade C bolts are made of raw round steel, the size is not accurate enough, and the material property grade is grade 4.6 or 4.8. The deformation of shear connection is large, but the installation is convenient and the production cost is low. It is mostly used for tensile connection or temporary fixation during installation.
