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What are the classification and use of high-strength bolts?

High-strength bolts are special bolts made of high-quality carbon steel or low-alloy steel. They are called high-strength bolts because of their high strength. High-strength bolt connections have the advantages of simple and fast installation, good mechanical performance, assembly and disassembly, high pressure bearing, safety and reliability, etc. High-strength bolts are a new type of steel structure connection method developed after riveting connection, and have now developed into one of the main means of steel structure connection today. 1. Classification of high-strength bolts High-strength bolts can be divided into two types: large hexagonal head type and torsion shear type in appearance; if they are divided into 8.8, 10.9, 12.9, etc., according to the performance grade, the large hexagonal head high-strength bolts currently used in our country have 8.8 and 10.9 grades, while the torsion shear type high-strength bolt strength bolt is only 10.9 grades. The large hexagonal head high-strength bolt connection pair consists of a bolt, a nut and two washers (the screw head and the nut each have a washer): the torsion shear type high-strength bolt connection pair consists of bolts, nuts and washers. When bolts, nuts and washers form a connection pair, their performance levels must match. 2. According to the connection method, high-strength bolts can be divided into three types: friction connection, tensile connection and pressure connection. Friction connection and pressure-bearing connection are both shear connection. Bolt friction connection trans

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What should be paid attention to when installing bolts during steel structure installation?

High-strength bolts are most used in the installation of steel structures, and the following problems often occur in practice: Bolts are less exposed or lower than nuts; The bolts are not tightened, and the plum blossom head is screwed off during the twisting and shearing process, and the large hexagonal shape is not marked with the initial and final screwing; During the actual installation process, the original layer of protective paper on the friction surface was not completely torn off; Use high-strength bolts for temporary fixing, and do not paint seal within two days and two nights after installation; The torque and axial force were not re-tested, and the fastening torque was not calculated in strict accordance with the relevant regulations;

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Precautions for on-site welding of steel structure bolt balls

1. When it comes to welding, everyone is very worried. The welding of the ball handle is carried out in the factory, and it is the welding of the same base material, which is carried out according to the conventional process, which is no problem. On-site welding, such as the welding of the connecting plates of the rods, the welding of supports such as roofs, carriages, light bridges, and the welding of reinforcement parts when the grid is reinforced, etc., are welded after the grid is installed or during the use of the grid. There are three concerns about on-site welding: first, whether the internal force will change after the grid components are welded and heated, resulting in structural instability and damage; second, whether the welding of different base materials of Q235B steel plate and 45 #steel bolt ball is possible; third, after the welding of components heats up, especially on the bolt ball, will the welding cause high-strength bolt annealing and the strength will decrease.

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How much do you know about the correct use of high-strength bolts?

Bolts made of high-strength steel, or bolts that need to be used with greater force, are called high-strength bolts. High-strength bolts are a special type of bolts, and there are certain usage methods and precautions. Do you know how to use this kind of bolt correctly? 1. Before installation of high-strength bolts Before installation, it is necessary to clean up the oil stains, rust, burrs, welding tumors, dust and other impurities attached to the surface of the bolt surface, so as not to affect normal use. Before installation, it is necessary to check whether the connecting parts between them are deformed or otherwise damaged. The treated contact surface should meet the specified anti-slip coefficient standards, and should be equipped with corresponding nuts, washers and other parts during use, which are used together and cannot be replaced with each other. 2. When installing high-strength bolts During installation, the surface of the component should be kep

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How to divide the strength grade of bolts

How bolts are divided into strength grades: The performance grades of steel structure connecting bolts are divided into more than 10 grades, such as 3.6, 4.0, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9. The specific meaning of bolt grades is, for example, bolts of grade 4.8 representing tensile strength. 0.8 represents the ratio of strength divided by tensile strength, that is, the tensile strength of grade 4.8 bolts is 400MPa, and the strength is 400 × 0.8 = 320MPa. Other bolt grades have the same meaning.

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What is the standard and acceptance for installing steel structure bolts?

Steel structure bolts play a linking role in machinery. Bolts are needed in many places to fix, so what are the standards and acceptance for installing steel structure bolts? Please take a look with the editor of Xinmo Fasteners. What is the standard and acceptance for installing steel structure bolts? 1. Hit the high-strength bolts with a 0.3kg hand hammer for census to check whether there is any leakage; the tightening of the high-strength bolts with large hexagon heads should be divided into initial and final screwing; the tightening of torsion shear type high-strength bolts should be divided into initial screwing and final screwing. For large nodes, it should be divided into initial screwing, re-screwing, and final screwing, and the re-screwing torque is equal to the initial screwing torque.

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What are high-strength bolts, the characteristics of high-strength bolts and their transportation requirements

High-strength bolts (referred to as high-strength bolts) refer to bolts made of high-strength steel or that need to be prestressed. They are one of the main connection methods of bridge steel structures. High-strength bolts are mostly used for the connection of bridges, rails, high-pressure and ultra-high-pressure equipment. High-strength bolts used in ultra-high-pressure equipment need to be prestressed to ensure the sealing of containers. In recent years, due to the influence of many factors such as the use environment, some bridges have experienced high bolt delay fracture and fall off. The fracture of such bolts is mostly brittle fracture, which may lead to slippage of the connecting nodes, instability and damage of the main structure of the steel bridge, and risk of hitting vehicles and pedestrians. Different from ordinary bolts, high-strength bolts are fasteners with strong fastening ability, and the requirements for storage, transportation and storage are relatively high. According to its fastening principle, it is required that every link of high-strength bolt connections from factory to installation must be maintained in the factory state, that is, the torque coefficient and standard deviation of the same batch of large hexagon head high-strength bolt connections remain unchanged. Keep the axial force and standard deviation of the torsional shear type high-strength bolt connection pair unchanged. It should be said that for the large hexagonal head bolt connection pair, if the state changes, it can be remedied by adjusting the construction torque, but the torsional shear type high-strength bolt connection pair has no chance of remediation, and can only be solved by the torque method or the angle method.

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How to effectively avoid rusting of hot-dip galvanized bolts

Hot-dip galvanized bolts are a relatively good anti-rust surface, but in the face of weathering and corrosion in nature, rust appears. In order to avoid this phenomenon, the following measures will be taken.

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Difference between stainless steel photovoltaic bolts and iron bolts

Stainless steel is more and more loved by people because of its corrosion resistance and not easy damage. So what is the difference between stainless steel photovoltaic bolts and iron bolts? Today, the editor of hot-dip galvanized screws will take everyone to understand:

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Application of hot-dip galvanized expansion bolt

In the application of hot-dip galvanized expansion bolts, there are many names for bolts, and everyone may call them differently. Some people call them screws, some call them bolts, and some call them fasteners. Although there are so many names, they all have the same meaning, they are all bolts. Bolts are a common term for fasteners. Bolts are tools that use the physical and mathematical principles of the circular rotation and friction of the bevel of an object to gradually tighten utensils and parts.

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