Screw is a kind of commonly used fastener consisting of head and screw, which is mainly used to connect fixed parts, mostly for fastening and easy installation and disassembly. As screws are used more and more widely in our daily life, in addition to their advantages, people begin to pay attention to their classification and specifications.
1. Slotted common screws are usually used for the connection of smaller parts. It has pan head screws, cylindrical head screws, half countersunk head screws and countersunk head screws. The head strength of pan head screws and cylindrical head screws is high, and they are connected to common parts; The head of the half countersunk head screw is curved, and its top is slightly exposed after installation, which is beautiful and smooth, and is generally used for instruments or precision machinery; Countersunk screws are used where the nail head is not allowed to be exposed.
2. The head of such screws as hexagonal socket and hexagonal socket torx can be embedded in the component, which can exert greater torque and have higher connection strength, so they can replace hexagonal bolts. It is often used at the joint with compact structure and smooth appearance.
3. The cross recessed common screw has similar use function with the slotted common screw and can be replaced with each other. However, the cross recessed common screw has high groove strength, is not easy to be unscrewed and has a beautiful appearance. When in use, it must be loaded and unloaded with the matching cross screwdriver.
4. Eyebolt Eyebolt is a kind of hardware fitting for bearing weight during installation and transportation. When using, the screw must be screwed to the position where the bearing surface fits closely. It is not allowed to use tools to tighten it, nor is it allowed to have a load perpendicular to the lifting ring plane acting on it.
5. Set screw The set screw is used to fix the relative position of the machine. Screw the set screw into the screw hole of the part to be tightened, and press its end against the surface of another part, that is, fix the previous part on the next part. Set screws are usually made of steel or stainless steel, with tapered, concave, flat, cylindrical and stepped end shapes. The end of the set screw with cone end or concave end is used to directly tighten the part, which is generally used at the place that is not often disassembled after installation; The end of the flat end set screw is smooth, and the surface of the part will not be damaged after being jacked. It can only transfer small loads when used at the connection where the position needs to be adjusted frequently; The tightening screw part at the cylinder end is used to adjust the fixed position frequently. It can bear large load, but its anti loose performance is poor. Anti loose measures shall be taken when fixing; Stepped set screws are suitable for fixing parts with large wall thickness.
6. When tapping screws are used on the connected parts, the connected parts may not be pre threaded. When connecting, use screws to directly tap threads. It is often used to connect thin metal plates. There are two kinds of tapping screws with tapered end and flat end.