Classification of fasteners
1. What is fastener?
Fastener is the general name of a kind of mechanical parts used to fasten and connect two or more parts (or components) into a whole. Also known as standard parts in the market.
2. It usually includes the following 12 types of parts:
Bolts, studs, screws, nuts, self tapping screws, wood screws, washers, retaining rings, pins, rivets, assemblies and connecting pairs, welding nails.
(1) Bolt: a kind of fastener composed of head and screw (cylinder with external thread), which needs to be matched with nut to fasten and connect two parts with through holes. This connection form is called bolt connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolt connection is a removable connection.
(2) Stud: a kind of fastener with no head and only external threads on both ends. When connecting, one end of it must be screwed into the part with internal thread hole, and the other end must pass through the part with through hole, and then screw on the nut, even if the two parts are firmly connected as a whole. This connection form is called stud connection, which is also a removable connection. It is mainly used when one of the connected parts is thick and requires compact structure, or bolt connection is not suitable due to frequent disassembly.
(3) Screw: it is also a kind of fastener composed of head and screw. It can be divided into three categories according to its purpose: steel structure screw, set screw and special purpose screw. Machine screws are mainly used for the fastening connection between a part with a threaded hole and a part with a through hole, without nut matching (this connection form is called screw connection, which also belongs to removable connection; it can also be matched with nuts, which is used for the fastening connection between two parts with a through hole.) The set screw is mainly used to fix the relative position between two parts. Special purpose screws, such as eyebolts, are used for hoisting parts.
(4) Nut: with internal thread hole, it is generally in the shape of flat hexagonal column, or flat square column or flat cylindrical. It is used to fasten and connect two parts into a whole with bolts, studs or steel structural screws.
(5) Self tapping screw: similar to screw, but the thread on the screw is a special thread for self tapping screw. It is used to fasten and connect two thin metal components to make them a whole. Small holes need to be made on the components in advance. Because this screw has high hardness, it can be directly screwed into the holes of the components to form corresponding internal threads in the components. This type of connection is also a removable connection.
(6) Wood screw: it is also similar to the screw, but the thread on the screw is a special thread for wood screw, which can be directly screwed into the wooden component (or part) to firmly connect a metal (or non-metal) part with a through hole with a wooden component. This connection is also a detachable connection.
(7) Washer: a kind of fastener with flat circular shape. It is placed between the support surface of bolts, screws or nuts and the surface of connecting parts, which plays a role in increasing the contact surface area of connected parts, reducing the pressure per unit area and protecting the surface of connected parts from damage; Another kind of elastic washer can also prevent the nut from loosening.
(8) Retaining ring: it is installed in the shaft groove or hole groove of steel structure and equipment, and plays the role of preventing the parts on the shaft or hole from moving left and right.
(9) Pin: it is mainly used for positioning parts, and some can also be used for connecting parts, fixing parts, transmitting power or locking other fasteners.
(10) Rivet: a kind of fastener composed of head and nail rod, which is used to fasten and connect two parts (or components) with through holes to make them a whole. This connection form is called rivet connection, which is called riveting for short. It is a non removable connection. Because to separate the two parts connected together, the rivets on the parts must be destroyed.
(11) Assembly and connecting pair: assembly refers to a kind of fastener supplied by combination, such as the combination of a certain machine screw (or bolt, self supplied screw) and flat washer (or spring washer, lock washer); Connection pair refers to a kind of fastener that combines some special bolts, nuts and washers, such as high-strength large hexagon bolt connection pair for steel structures.
(12) Welding nail: as a heterogeneous fastener composed of a bare rod and a nail head (or no nail head), it is fixedly connected to a part (or component) by welding, so as to connect with other parts.