Main classification of bolts?
According to the performance grade, it is divided into 3.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9 and other grades. Bolts of grade 8.8 and above are made of low-carbon alloy steel or medium carbon steel and heat treated (quenched + tempered). They are generally called high-strength bolts, and bolts of grade 8.8 and below are generally called ordinary bolts. The numbers before and after the decimal point are respectively expressed as the nominal tensile strength and yield strength ratio of bolt material.
Common bolts are usually hexagon bolts, stud bolts, anchor bolts, etc. high-strength bolts are divided into torsional shear type high-strength bolts and large hexagon high-strength bolts.
According to the way of force transmission, it can be divided into shear bolt, tensile bolt, shear bolt and tension bolt. Shear connection: it depends on the pressure and shear resistance of the screw to transmit the external force perpendicular to the direction of the rod axis, and there is a tendency of staggered movement between the plates; tensile connection: it depends on the tension of the screw to transmit the external force parallel to the direction of the rod axis, and there is a tendency of separation between the plates; the joint action of tension and shear depends on the screw to transmit the external force perpendicular to the direction of the rod axis as well as the horizontal force The external force in the direction of the rod axis. There is a trend of relative dislocation and separation between plates.