What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
From the perspective of use: The bolted connection of the main components of the building structure is generally connected by high-strength bolts. Ordinary bolts can be reused, but high-strength bolts cannot be reused. High-strength bolts are generally used for permanent connections. The high-strength bolts are prestressed bolts. The friction type uses a torque wrench to apply the specified prestress, and the pressure type screw off the torx head. Ordinary bolts have poor shear performance and can be used in secondary structural parts. Ordinary bolts just need to be tightened. Ordinary bolts are generally 4.4, 4.8, 5.6 and 8.8. High-strength bolts are generally 8.8 and 10.9, of which 10.9 is mostly. Level 8.8 is the same level as 8.8S. The mechanical properties and calculation methods of ordinary bolts and high-strength bolts are different. The stress of high-strength bolts is firstly by applying a pre-tension force P inside, and then generating frictional resistance on the contact surface between the connected parts to bear the external load, while ordinary bolts directly bear the external load.
Usually, the pumped storage unit adjusts the opening of the guide vane through the movable guide vane to control the power generation output and the pumping head of the unit. The torque of the guide vane rotation depends on the relay to act on the control ring, and the torque is transmitted to the guide vane rotating shaft through the connecting rod and the arm. The torque transmission between the crank arm and the rotating shaft all acts on the pin located between them. When the unit is overhauled, it is necessary to remove the pin between the arm and the rotating shaft of the guide vane in advance when it comes to the replacement of the guide vane. However, due to the special position of the pin and the limited inspection space, the conventional method is not only time-consuming and laborious, but also has the risk of damaging the pin. Maintenance work brings inconvenience.
The tie rod and joint of the high-voltage isolating switch are often connected by driving an elastic cylindrical pin into the connecting pin hole. The traditional assembly method is to prevent the tie rod and joint from the V-block, and hold the elastic cylindrical pin to align the connecting pin hole. Then hit it with a hammer. Since the elastic cylindrical pin is small, it is easy to injure people's hands by adopting this assembly method, and at the same time, the elastic cylindrical pin is not positioned accurately, which causes large assembly errors and low assembly efficiency.
Fasteners are a class of mechanical parts that are used for fastening connections and are widely used. It is used in a wide range of industries, including energy, electronics, electrical appliances, machinery, chemical industry, metallurgy, mold, hydraulic and other industries, in various machinery, equipment, vehicles, ships, railways, bridges, buildings, structures, tools, instruments, chemicals, instruments And supplies, etc., you can see all kinds of fasteners, which are widely used mechanical basic parts. In the fields of listed rails, construction machinery, etc., due to the harsh application environment, the requirements for fasteners are more stringent. If the fasteners are loosened, it may lead to serious consequences, resulting in a large amount of property damage, even serious life cost.
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