Fastener is characterized by many different specifications, performance of different purposes, and standardization, high serialization, universal level, so it was also been the national standard for a class of fasteners called standard fasteners, or simply standard parts.
Internationally, the fastener according to fields of use can be divided into two categories, one is a general purpose fasteners, another type of aerospace fasteners. General purpose applications very broad, such as machinery, electronics, transportation, furniture, construction, chemicals, shipbuilding, toys, etc., life everywhere. Aerospace fasteners are designed for aerospace vehicle design fasteners.
Where will mainly use these fasteners? First, the automotive industry is the largest user, accounting for 23.2% of total sales fastener; the second is the maintenance of the industrial market and construction industry, together accounting for 20%; the third is the electronics industry accounted for 16.6%.
Fastener is used as the basis of industrial components, its wide range of performance of the structure varied, different assembly environment, different requirements,
Its structure and performance requirements are also different.
12 generally comprises the following parts:
1) Bolt: the head and the screw (externally threaded cylinder) connected to form a class of fasteners, and need the nut for fastening two parts with hole. This connection type called bolt connection. As to unscrew the nuts from the bolts, so that the two parts can be separated, so bolting belongs detachable connection.
2) Stud Bolt or Thread Rod: No head, only both ends of the threaded fastener packed a class. Connection, it must be screwed into the end piece with the threaded hole in the other end with a hole through the parts, and then screw on the nut, so that the two parts into a whole fastening. This connection form is called stud connection, also belongs to the detachable connection. Is mainly used to connect one of the larger part thickness, requires compact, or due to frequent disassembly, and the bolt should not be used in place.
3) Screw: is composed of a class and the screw fastener head of two parts, according to the purpose can be divided into three categories: machine screws, set screws and special screws. The main parts for machine screws a tight set screw hole, and a fastening between the parts with hole, no mating nut (This connection form is called the screw connection and also a detachable connection; and to be and the nut for fastening two parts with a hole between the connections.) set screw is mainly used for fixing the relative position between the two parts. Special purpose screws for example, eye bolts and other parts used for lifting.
4) Nut: with an internal thread hole, general shape is substantially flat hexagonal column, there Chengbian square cylindrical or flat cylindrical, with bolts, studs or machine screws for fastening two parts, so that become a whole. Special categories of high-strength nuts self-locking nut is self-locking nut of a tree, with a high strength, high reliability side. Mainly the introduction of European technology as a prerequisite for used road construction machinery, mining machinery, vibrating machinery and equipment, the current domestic production of such products manufacturers very little. Nylon self-locking nut nylon self-locking nut is a new high-vibration-resistant locking fasteners, it can be applied to a variety of mechanical temperature -50 ~ 100 ℃, and electrical products. Currently, aerospace, aviation, tanks, mining machinery, motor transport machinery, agricultural machinery, textile machinery, electrical products and a variety of mechanical self-locking nut nylon demand surge, because of its much higher performance vibration-resistant locking in a variety of other locking devices, and vibration to life several times or even several times. The current accident machinery and equipment more than 80% is due to the loosening of the fastener caused, particularly in the mining machinery is particularly serious, and nylon self-locking nuts can prevent a major accident due to the loose fasteners caused.
5) Self-tapping screw: machine screws similar, but the screw threads for special self-tapping screw threads. For fastening two thin metal components, making it a whole, the members need to make a small hole in advance, because of this screw has high hardness, can be screwed directly into the hole member, so that members formed in response to the thread. This connection also form part of a detachable connection.
6) Wood screw: machine screws and is also similar, but the screw threads on wood screws with a dedicated rib, can be directly screwed into the wood element (or part), and for a metal band through hole (or non-metallic) Part of a wood elements fastened together. This connection also belongs detachable connection.
7) Washer: oblate shape of a ring-type fasteners. Disposed between the bolts, screws or nuts with a support surface connected to the part surface, plays an increasing part is connected contact surface area, reducing the pressure per unit area and the surface of the connection member is protected from damage effects; another elastic washer, also plays a role to prevent the nut loose back.
8) Ring: for shaft mounting slots or holes slot machines, equipment or parts to play to prevent the shaft hole on the left and right to move in.
9) Pin: mainly for positioning parts, and some parts are also available for connecting fixed parts, transmission power or other fastener locking purposes.
10) Rivet: by a class of the fastener head and shank of two parts for fastening two parts with through holes (or members) to become a whole. This connection form is called rivet connection, referred to as riveting. Not the case with detachable connection. Because the two parts together to make the connection separately, you must destroy the rivet part.
11) Assembly and connection pair: assembly is a combination of the supply of a type fasteners, as will be some kind of machine screws (or bolts, screws confession) and the flat washers (or spring washers, lock washers) combination of supply; connection Vice refers to some kind of special bolts, nuts and washers supplied by a combination of a class of fasteners, such as high-strength steel structure with large hexagonal head bolts connecting deputy.
12) Welding screw: Due to light and stud (with or without screwhead) heterogeneous fasteners constituted by welding him fixedly connected to a part (or member) above, in order to re-connect with the other parts.