Classification of bolts
According to the way of connection, it is divided into ordinary and reamed holes. According to the shape of the head: there are hexagonal heads, round heads, square heads, countersunk heads, etc. The hexagonal head is the most commonly used. Generally, the countersunk head is used where the connection is required.
The English name of the riding bolt is U-bolt. It is a non-standard part. It is U-shaped and is also called U-bolt. The two ends are threaded and can be combined with the nut. It is mainly used to fix tubular objects such as water pipes or sheets such as automobile plates. The spring is called a riding bolt because it fixes the object like a person riding on the horse. According to the length of the thread, it is divided into two types: full thread and non-full thread.
The type of thread according to the thread is divided into two types: coarse teeth and fine teeth. The coarse tooth type is not displayed in the bolt symbol. Bolts are classified into 3.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9 grades according to performance grades. Among them, grades 8.8 or higher (including grade 8.8) are made of low carbon alloy steel or medium carbon steel and heat treated (quenched). + tempering), commonly known as high-strength bolts, below 8.8 (excluding 8.8) is commonly called ordinary bolts.
Ordinary bolts can be divided into three grades A, B, and C according to the production precision. Grades A and B are refined bolts, and grade C is thick bolts. For the connection bolts for steel structures, unless otherwise specified, they are generally ordinary C-class bolts. There are differences in the methods of different grades. Generally, the corresponding processing methods are as follows: The bolts of 1A and B bolts are machined by lathe, the surface is smooth and the size is accurate. The material performance grade is 8.8, the production and installation are complicated, and the price is relatively high. High, rarely used; Class 2C bolts are made of unprocessed round steel and are not accurate enough to have a material performance rating of 4.6 or 4.8. The deformation is large when the shear connection is made, but the installation is convenient, the production cost is low, and it is mostly used for the temporary connection of the tensile connection or the installation.