1.six angle bolts: a class of fasteners consisting of two parts, head and screw (cylinder with external thread), which need to be matched with nuts for fastening and connecting two parts with holes. This form of connection is called bolted connection. If the nut is screwed down from the bolt, the two parts can be separated, so the bolt connection belongs to the detachable connection.
2.stud: a type of fastener with no head and only threaded ends. When connecting, one end must be screwed into a part with an inner threaded hole, the other end through a part with a through hole, and then screw on the nut, even if the two parts are fastened and connected as a whole. This type of connection is called stud connection, and it also belongs to removable connection. The utility model is mainly used for occasions where the thickness of a connecting component is large, the structure is compact, or the bolt connection is not suitable for frequent disassembly.
3.screw: it is also a kind of fastener made up of two parts of head and screw. They can be divided into three types according to their usage: machine screw, fastening screw and special purpose screw. The machine is mainly used for fastening a screw thread hole and fastening parts, connection between a part with a through hole, do not need to match the nut (this connection is called screw connection, also belongs to the detachable connection; can also be used for fastening with a through hole between the two parts together with the nut. The fastening screw is mainly used to fix the relative position between the two parts. Special purpose screws, such as rings, screws, etc. for lifting parts.