What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
In mechanical devices, there are many ways to install and connect two components, such as bolt connection, welding, etc., but for installation and connection in a narrow space, such as the socket of two hollow cylinders with smaller diameters, due to the relatively small space It is very difficult to use this method, and it is extremely inconvenient to install and connect.
1. Ordinary outer hexagon - widely used, characterized by relatively large tightening force, the disadvantage is that there must be enough operating space during installation, and adjustable wrench, open-end wrench or glasses wrench can be used during installation, all of the above wrenches require a large amount of space. operating space. 2. Cylindrical head hexagon socket - is the most widely used of all screws, because it has a relatively large tightening force, and can be operated with a hexagon wrench. It is very convenient to install and is used in almost all kinds of structures. The appearance is more beautiful and neat. The disadvantage is that the tightening force is slightly lower than the outer hexagon, and the inner hexagon is easily damaged due to repeated use and cannot be disassembled. 3. Pan head inner hexagon - rarely used mechanically, the mechanical properties are the same as above, mostly used in furniture, the main function is to increase the contact surface with wooden materials and increase the ornamental appearance. 4. Headless inner hexagon - must be used in certain structures, such as the top wire structure that requires a large top-tight force, or where the cylindrical head needs to be hidden. 5. Countersunk head hexagon - mostly used in power machinery, the main function is the same as the inner hexagon. 6. Nylon lock nut - a nylon rubber ring is embedded in the hexagonal surface to prevent the thread from loosening, and it is used on strong power machinery. 7. Flange nuts - mainly play the role of increasing the contact surface with the workpiece, mostly used in pipes, fasteners, some stamping parts and casting parts. 8. Ordinary hex nut - the most widely used and one of the most common fasteners.
When the nut is tightened on the stud, there will inevitably be an empty upstroke. That is, when the nut has not reached the part that needs to be tightened, the nut needs to be twisted on the non-locking (working) part of the front end of the stud by hand or tool, so that the nut runs along the axial direction of the stud and reaches the part to be locked. . When the idling stroke of the thread at the front end of the stud is long or the thread pitch is small, the idling stroke before locking will waste a lot of time, resulting in a huge occupation of personnel or tools.
GB 3098.1 Mechanical Properties of Fasteners Bolts, Screws, Studs and Nuts GB 3098.6 Mechanical Properties of Fasteners Stainless Steel Bolts, Screws, Studs and Nuts GB 3103.1 Tolerances of Fasteners Bolts, Screws and Nuts GB 5267 Electroplating of Threaded Fasteners GB 5779.1 Surface Defects of Fasteners - Bolts, Screws and Studs - General Requirements GB 5779.3 Surface Defects of Fasteners - Bolts, Screws and Studs - Special Requirements
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