What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
High-strength bolt connection has the advantages of simple construction, good mechanical performance, disassembly and replacement, fatigue resistance, and no loosening under dynamic load. It is a promising connection method. High-strength bolts use a special wrench to tighten the nut, so that the bolt generates a huge and controlled pre-tension. Under the action of pre-pressure, a large frictional force will be generated along the surface of the connected parts. Obviously, as long as the axial force is less than this frictional force, the components will not slip and the connection will not be damaged. This is the high-strength bolt connection. principle. High-strength bolted connections rely on the friction between the contact surfaces of the connectors to prevent them from sliding each other. In order to make the contact surfaces have sufficient friction, it is necessary to increase the clamping force of the components and increase the friction coefficient of the contact surfaces of the components. The clamping force between the components is achieved by applying pretension to the bolts, so the bolts must be made of high-strength steel, which is why it is called high-strength bolted connections. In high-strength bolted connections, the friction coefficient has a great influence on the bearing capacity. Tests show that the coefficient of friction is mainly affected by the form of the contact surface and the material of the components. In order to increase the friction coefficient of the contact surface, methods such as sandblasting and wire brush cleaning are often used to treat the contact surface of the components within the connection range during construction.
Specification label broadcast representation format: Thread specification d=M12, nominal length L=80mm, and performance level 4.8 equal-length stud bolts are completely marked as: GB 901 M12×80 [1] Product example: Stud studs are generally required After surface treatment, there are many types of bolt surface treatment, commonly used are electroplating, blackening, oxidation, phosphating, electroless zinc flake coating treatment, etc. However, electroplated fasteners account for a large proportion of the actual use of fasteners. Especially in automobiles, tractors, home appliances, instrumentation, aerospace, communications and other industries and fields are more widely used. However, for threaded fasteners, not only a certain anti-corrosion capability is required in use, but also the interchangeability of threads must be ensured, which can also be called screwability here. In order to meet the dual-use performance of anti-corrosion and interchangeability required by threaded fasteners in use, it is very necessary to formulate special plating standards.
Nuts are used as fasteners, and most of them need to be used in conjunction with gaskets in the process of use to adjust the deficiencies of the material itself and strengthen the degree of tightening, while metal materials are used as raw materials for gaskets. The cost is also relatively high, and in the process of use, the end face of the metal gasket and the nut will also be affected by the process, resulting in the defect that the fastening effect is not firm and easy to loosen.
Rivets refer to the parts that use their own deformation or interference to connect the riveted parts in riveting. As a common fixed connector, rivets are fixed by special pull rivets, which are easy to operate and have a wide range of applications.
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