服务热线: 400-117-8816




来源: 日期:2022-12-28 发布人:wanzhong

Correct screwing method of high-strength bolts for steel structures
High strength bolts of steel structures can be divided into friction type connection and pressure bearing type connection from the mechanical characteristics. The connection surface of high-strength bolt pressure bearing connection only needs to be treated with rust prevention. However, the friction type of high-strength bolt has the advantages of tight connection, good stress resistance, fatigue resistance, and suitable for bearing dynamic load. However, the friction surface treatment is required for the connection surface, which is generally treated by sandblasting and coating inorganic zinc rich paint after sandblasting.
High strength bolts of steel structure can be divided into large hexagon head high strength bolts and torsional shear type high strength bolts due to different bolt structures and construction methods. The big hexagon head type is the same as the common hexagon head rough bolt, and the twist shear type bolt head is similar to the rivet head, but the twist shear type thread end is provided with a quincunx clip head and an annular groove that can control the tightening torque, which requires attention.
A bolt connection pair includes three parts: bolt, nut and washer. The construction and arrangement requirements of high-strength bolts are the same as those of ordinary bolts. Then it must be used in accordance with the specifications. Only 8.8 high strength bolts can be used for large hexagon heads, and only 10.9 high strength bolts can be used for torsional shear type high strength bolts.
The pretension of high-strength bolts of steel structures is achieved by tightening the nuts. Usually, torque method, angle method or torquing off the quincunx clamp at the end of the bolt are used to control the pretension.
At present, there is a special wrench that shows the torque. By measuring the relationship between the torque and the bolt tension, the torque can be applied to achieve the necessary overstretching value.
Angle method The angle method is divided into two steps: first, initial tightening, and second, final tightening. In simple terms, the initial tightening is generally the workers use ordinary wrenches to make the connected components closely fit each other, while the final tightening is the final tightening angle determined according to the bolt diameter and the thickness of the plate stack, using a powerful wrench to rotate the nut. When the nut is tightened to the preset angle value, the bolt tension can reach the required pre tension value. In order to prevent the high strength bolts from being affected by the external environment and changing the torque coefficient, the initial tightening and final tightening should be completed in the same day.
The stress characteristics of torsional shear high-strength bolts are the same as those of ordinary high-strength bolts, except that the method of applying pretension is to control the pretension value by unscrewing the section at the notch of the bolt quincunx head.
Friction type high-strength bolt connection completely relies on the friction resistance between the connected components to transmit force, and the friction resistance is determined by the friction surface anti slip coefficient determined by the surface treatment of the materials and contact surfaces of the connected components in addition to the pretension of the bolts.
The above is a detailed introduction to the special wrench for torsional shear bolts, and we hope it will be helpful to you. If you have any questions, please contact us. We will provide services for you with our attitude