Screw is a more general term.Anything with an external thread can be called a "screw".The exact term should be bolts, screws, and screw caps (nuts).It is a mechanical part used to fasten the connection.Standard fasteners mainly include bolts, studs, screws, set screws, nuts, washers and rivets.Standard fasteners are divided into twelve categories, and the selection is determined according to the use occasion of the fastener and its use function.
(1) Bolts Bolts are widely used in detachable connections in re-machine manufacturing, and are generally used in conjunction with nuts (usually plus a washer or two washers).
(2) Nuts are commonly known as "nuts" and "screw caps".The shape is usually hexagonal, and the inner hole is internal thread. It is used to cooperate with bolts and tighten related parts.
(3) Screws The screws are small, with flat heads, cross heads, etc. on the head, and external threads on the rod.It is usually used alone (sometimes with a washer), usually for tightening or tightening, and should be screwed into the internal thread of the body.
(4) Stud studs should actually be called "double-ended studs". Both ends have external threads. The middle is usually a polished rod screw. It is mostly used to connect one of the connected parts with a large thickness. It requires a compact structure or is not suitable due to frequent disassembly. Where bolts are used.Studs are generally threaded at both ends (single-end studs are threaded at one end). Usually one end of the thread is firmly screwed into the body of the component, and the other end is matched with the nut to play the role of connection and fastening. To a large extent, it also has a fixed distance function.
(5) Wood screws Wood screws are used to screw into wood to connect or fasten.
(6) Self-tapping screw The working screw hole that matches with the self-tapping screw does not need to be tapped in advance. When the self-tapping screw is screwed in, the internal thread is formed.
(7) Washers Washers are placed between the supporting surface of bolts, screws, nuts, etc. and the supporting surface of the workpiece to prevent loosening and reduce the stress on the supporting surface.
(8) Retaining ring Retaining ring is mainly used to locate, lock or stop parts on shaft or hole.
(9) Pin Pins are usually used for positioning, and can also be used to connect or lock parts. They can also be used as overload shearing elements in the device.
(10) Rivets The rivets have a head at one end, and the shank has no thread.When in use, the rod is inserted into the hole of the connected piece, and then the end of the rod is riveted to play the role of connection or fastening.
(11) The connection pair is the combination of screw/bolt/tapping screw and washer.After the washer is installed on the screw, it must be able to rotate freely on the screw (or bolt) without falling off.It is mainly used for tightening or tightening.
(12) Others mainly include welding nails and so on.