What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The common types of wood screws are iron and copper, and the types are divided into round head type and other samples of wood screws according to different nail heads. There are two types of slotted screws and cross recessed screws. Generally, the round head screws are made of mild steel and are blue, and the flat head screws are polished. The oval head screws are usually plated with cadmium and chrome, and are often used to install hinges, hooks and other hardware accessories. Specifications are determined by rod diameter, length and nail head type. [1]
screw is a type of fastener that cooperates with threaded holes for combining various parts into one assembly and making the parts easy to assemble or disassemble. However, when the assembly containing the screw is used in a special environment, such as outdoor use or use in a liquid environment, there are requirements for preventing the leakage of liquid through the screw joint and preventing the screw from loosening at the screw joint. The screw structure does not have such a function. In the prior art, when there is a need for leakage prevention and loosening of the screw, a rubber washer is usually added between the screw head of the screw and the locking surface of the locked part, or the thread part of the screw is wrapped to prevent Leakage tape and then add anti-loose washers between the screw head of the screw and the locking surface of the locked part, so as to achieve the purpose of preventing leakage and loosening. However, the use of washers not only increases the thickness and weight of the assembly, but also requires an additional process during assembly, which is labor-consuming and labor-intensive. In the process of screwing, it is easy to cause uncertainty to the rubber washers due to the shear stress of the screws. Leakage occurs due to damage and deformation, and the practice of wrapping leak-proof tape around the screw teeth is often prone to damage to the threaded holes.
On the surface of the mounting hole on the connector, a 90-degree conical socket is machined, and the head of the flat machine screw is in the socket and is flush with the surface of the connector. Flat machine screws are also used in some occasions with semi-circle head flat machine screws, which are more beautiful and are used for places where a little protrusion is allowed on the surface. Screws play the role of connecting two or more objects and are an indispensable necessity in daily life or industrial manufacturing. There are countersunk head bolts (with grooves) and countersunk head bolts (with tenon).
GB bolts are generally divided into two types: GB30 bolts and GB21 bolts. The difference is that the hexagonal head of GB30 is larger than that of GB21. The materials are all used: Q235. The grade is 4.8, the hardness is weak, and it is used for parts with low hardness requirements and infrequent activities, which are called ordinary bolts. The most typical use: machinery, construction, fixing, fastening.
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