Brief introduction of large hexagon bolts for steel structure

1. Application of steel structure large hexagon
11. Scope of application:
Railway and highway bridges, boiler steel structures, industrial plants, high-rise civil buildings, tower mast structures, hoisting machinery and other steel structure friction-type high-strength bolt connections.
1.2. Principle of action:
The bolting system applies the friction force generated by the bolt assembly to tightly join two or more structural parts to withstand the external force
2. Process flow of steel structure large hexagon
2.1. Classification and comparison of forging processes:
?Hot forging: Hot forging is mainly performed by hammers
?Cold forging: cold forging system uses a punch or continuous forging machine to perform operations
2.2. Head and tooth rolling molding
Heading-whole head-rolling-heat treatment-supporting assembly-packaging-delivery-shipment
3. Technical conditions of steel structure large hexagon
3.1 Materials
20MnTiB/ML20MnTiB ≤M24
35VB ≤M30
3.2 Application technical specifications
GB/T1228-2006 Type and size of large hexagon head bolts for steel structure
GB/T1229-2006 Type and size of large hexagon head nuts for steel structure
GB/T1230-2006 Type and size of washers for steel structure
GB/T1231-2006 Technical requirements for large hexagon head bolts, large hexagon nuts and washers for steel structure
3.3 High-strength large hexagon head bolt connection pairs should be supplied according to the guaranteed torque coefficient. The average value of the torque coefficient of the same batch of connection pairs is 0.110~0.150, and the standard deviation of the torque coefficient should be less than or equal to 0.010. Each connection pair includes 1 bolt, 1 nut, and 2 washers, and should be manufactured in the same batch
4. Installation and use of steel structure large hexagon
4.1. The installation and use of high-strength fasteners is directly related to the quality and service life of the fasteners. The safety of the bolts is the primary consideration.
4.2. The main factors affecting high strength:
The selection of material, steel plate thickness, processing and cutting, surface painting and installation of steel structural parts must be carried out in accordance with the design and construction specifications, otherwise the pre-loading capacity of the steel structure will be reduced or lost, and the safety of the bolts will be reduced at the same time .