What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
When using ordinary hexagon head bolts or ordinary T-bolts with the oval groove structure, the bolts need to be inserted from the back of the groove. When the bolts cannot be inserted from the back of the groove due to the structural limitations of the steel base or the platform itself, it is often necessary to open the installation surface. Large diameter hand holes allow for easy mounting of bolts, which weakens the inherent strength and rigidity of a steel base or platform.
Therefore, in order to obtain fasteners that meet the requirements, it is usually necessary to anneal the middle sections of bolts, rivets, etc. to reduce the hardness of the middle sections, while ensuring the hardness of the heads of bolts, rivets, etc. At present, the existing process adopts ultra-high frequency induction heating equipment to instantly heat the middle section and reduce the hardness. However, this process requires a lot of control, and the heating time is slightly longer, which affects the hardness of the head, and the mass production is very unstable, which is easy to cause the rivet to fail. At the same time, the cost of ultra-high frequency equipment is high and the power consumption is large, which is not conducive to mass production and energy saving. Environmental friendly.
Bolts made of high-strength steel, or bolts that require a large pre-tightening force, can be called high-strength bolts. High-strength bolts are mostly used for the connection of bridges, rails, high-voltage and ultra-high-voltage equipment. The fracture of this kind of bolt is mostly brittle fracture. High-strength bolts applied to ultra-high pressure equipment need to be prestressed to ensure the sealing of the container.
Generally, we have to divide the fine thread nut and the coarse thread nut first, but in fact, no matter what kind of fine thread, coarse thread, their specifications are the same, their specifications are M3, M4, M5, M6, M8, M10, etc. . But there is another kind of hexagonal nut, which is divided into English and American, which is only a different national standard. Made in China, it is called the national standard hexagon nut
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