Bolt, nut, screw basic knowledge

In fact, the standard statement is no screw and nut.

Screws are commonly known as “screws” with external threads.

The shape of the nut is usually hexagonal, and the inner hole is inner thread, which is used to cooperate with the bolt to tighten the correlation.

Naruts are commonly known as “nuts”.

The head of the bolt is generally hexagonal, with external threads.

The screws are small, the head is flat, cross head, etc., and the pole has external threads.

The thread should actually be called “double -headed snail”, with external threads on both ends, and the middle is generally a bolt. The ends of the thread length are used to connect to the deep hole, and the short section is connected to the nut.

Standard fastening components are divided into twelve categories. When selection, according to the use of fasteners and their use functions.

1 bolt

The bolt is widely used in dismantling connections in mechanical manufacturing. Generally, it is used with nuts (usually with one pad or two cushions).

2 nut

Use of nuts with bolts.

3 screws

Screws are usually used alone (sometimes adding cushions). Generally, it is tight or fixed.

4 snails

The thread is mostly used for one of the thickness of the connection parts, and it is necessary to use a compact structure or a bolt connection due to the frequent disassembly. Nails are generally carried on both ends (single -headed threads are single -ended with threads). Usually, one thread is firmly screwed into the component body, and the other end is matched with the nut. To a large extent, it has a fixed -distance effect.

5 wood screws

Wood screws are used to twist into wood, connecting or fastening.

6 Self -attack screw

The working threads that match the self -attack screw do not need to attack in advance. While twisting into the self -attack screw, the inner thread will be formed.

7 cushion

The pads are used between the supporting surfaces of the bolt, screw and nut and the workpiece support surface to play a role in preventing loosening and reducing support for support.

8 block

The block is mainly used to locate, lock or stop the parts on the shaft or hole.


Sales are usually used for positioning, can also be used to connect or lock parts, and can also be used as overload shear components in a safety device.

10 rivets

There is a head at the end of the rivet, and there is no thread at the pole. When using, insert the pole into the hole of the connector, and then riven the end of the rod to the connection or fastener.

11 Connect

Connect the combination of a sub -screw or bolt or self -attack screw and pad. After the cushion is installed after the screw, it must be freely rotated on the screw (or bolt) without falling off. It mainly plays a tight or fixed effect.

12 others

It mainly includes welding nails and other content.

Determine the variety

(1) Principles of varieties

① From the efficiency of processing and assembly work, in the same machinery or engineering, you should try to minimize the variety of fasteners;

② From economic consideration, the variety of commodity fasteners should be preferred.

③ According to the requirements of fasteners, the selection varieties are determined according to the type, mechanical performance, accuracy and thread aspects.

(2) Type

① bolt

a) General use bolts: There are many varieties, there are six -horn head and square head. Hexagonal bolts are the most common. According to manufacturing accuracy and product quality, they are divided into product grades A, B, C and other products. They are mostly used in A and B -grade, and they are mainly used for important, high assembly accuracy, great impact, vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration or vibration. Where the load is loaded. The hexagonal bolts can be divided into two types: hexagonal head and large hexagonal head according to their head support area and installation position size. The square head of the square bolts has a large size and surface surface, which is convenient for the wrench port or relying on other parts to start and stop the turning effect. It is often used in a relatively rough structure, and sometimes it is also used in the T -shaped slot, which is convenient for the bolts to be in the T -shaped bolt. The position of loosening in the slot. See GB8, GB5780 ~ 5790, etc.

b) Bolt of hinge holes: When using, the bolt is tightly inlaid into the hinge to prevent the workpiece from misalignment, see GB27 and so on.

c) Anti -rotor bolt: there are square necks and tenon, see GB12-15, etc.;

d) Special use bolts: include T -shaped groove bolts, live bolts and ground foot bolts. The T -shaped bolts are mostly used to open the connection where the connection is often used; the ground foot bolts are used for fixed racks or motor bases in the cement foundation. See GB798, GB799, etc.;

e) High -strength bolts connect to the steel structure: Generally used for friction -type connections of steel structures such as building, bridge, tower, pipeline brackets, and lifting machinery, see GB3632, etc.

② nut

a) General use nuts: there are many varieties, there are hexagonal nuts, square nuts, etc. Hexagonal nuts are most commonly used with hexagonal bolts. According to manufacturing accuracy and product quality, it is divided into product grades such as A, B, and C. The hexagonal thread is used as an secondary nut in the anti -loose device. The hexagonal thick nut is mostly used in the connection of frequent disassembly. The square nut and square bolt are used. The wrench stuck is not easy to slip, and is mostly used for rough and simple structures. See GB41, GB6170 ~ 6177;

b) slot nut: mainly refers to the hexagonal slot nut, that is, processing the slot above the hexagonal nut. It is used in conjunction with the screw bolt bolt and opening to prevent the bolts from relative rotation of the bolts and nuts. See GB6178 ~ 6181, etc.;

c) Locking nut: Refers to nuts with locking function, nylon embedded hexagonal lock nuts and all -metal hexagonal locking nuts. The hexagonal nylon ring locking nut has very reliable anti-pine capability. Under the temperature of -60 ~+100 ℃ and certain media conditions, it has no damage bolts and connecting parts and can be frequently loaded and unloaded. See GB889, GB6182 ~ 6187;

d) Special use nuts: such as butterfly nuts, cover -shaped nuts, rolling nuts and embedded nuts. The butterfly nuts are generally unpacked without tools, which are usually used in places where it needs to be disassembled and stressed; See GB62, GB63, GB802, GB923, GB806, GB807, GB809, etc.

③ screw

a) Machine screws: Different from the head shape and groove shape, it is divided into many varieties. There are two types of head shapes, plate heads, imperial heads, and semi -semi -headed heads. The head grooves are generally three types: slot (one -word slot), cross groove and inner hexagonal groove. When the cross screw is applied to the neutrality, the head strength is larger than that of a slot, which is not easy to twist, and is generally used in large quantities. Inner hexagonal screws and inner hexagonal screws can apply a large tightening torque. The connection intensity is large, and the head can be buried in the body to require a compact and smooth connection of the structure. See GB65, GB67 ~ 69 and GB818 ~ 820;

b) The screw is tightly fixed: the screw is used for the relative position of the fixed parts, and the head has a type of slot, the inner hexagonal and square head. The square head can apply a large tightening torque. The tight force is large and it is not easy to twist, but the head size is large, and it is not safe to bury into the parts. It is not safe, especially the motion site should not be used. Those with a slot, the inner hexagonal ends are easy to sink into the parts. The end of the screw is different according to the requirements of the use. Generally, the most commonly used is three types: cone, flat, and cylindrical end. The cone end is suitable for parts with small hardness; when using a sharp -end screw, the pits should be hit on the top of the part, and the cone surface is pressed on the pit eyes. The end is the screw of the flat end. The contact area is large. It does not hurt the surface of the parts after tightness. It is used to top the plane with large hardness or frequently adjust positions. The end of the end is the surface of the cylindrical end. The surface of the part is mostly used for fixing parts installed on the pipe axis (thin wall parts). Essence See GB71, GB73 ~ 75, GB77 ~ 78;

c) Inner hexagonal screws: Inner hexagonal screws are suitable for occasions where the installation space is small or the screw head needs to be buried.

d) Screws of special uses: such as positioning screws, non -cutting screws and suspension screws, see GB72, GB828 ~ 829, GB837 ~ 839, GB948 ~ 949, and GB825.

④ Nail

a) Do not wait for long double -headed threads: suitable for the occasion of the part of the part of the component body to connect or fastener, see GB897 ~ 900;

b) Waiting for long double -headed threads: suitable for connecting or fixed -spatial effects for both ends with nuts. See GB901, GB953, etc.

⑤ Wood screw

Many varieties are divided into many varieties due to different head shapes and slot shapes. There are several types of head shapes, hubs, and semi -semi -headed heads. The head grooves are two types: slot (one -word slot) and cross grooves. See GB99 ~ 101, GB950 ~ 952.

⑥ Self -attack screw

a) Ordinary self -attack screws: The thread is in line with GB5280, and the thread is large. It is suitable for use on thin steel plates or copper, aluminum, and plastic.

b) Self -attack lock screw: The thread is in line with ordinary rice -made thick tooth threads, which is suitable for use in need of vibration resistance. See GB6560 ~ 6564.


a) Flat padding circle: used to overcome the stress area of ​​the inheritance of the workpiece support and increase the support area. See GB848, GB95 ~ 97 and GB5287;

b) Spring (elastic) cushion: The spring pad is elastic and oblique friction to prevent the loosening of the fastener. It is widely used for frequent disassembly connections. The internal teeth elastic cushion and elastic elastic pads of the outer tooth have a lot of sharp elastic teeth on the round weeks. The thorns are pressed on the support surface, which can prevent the loosening of the fastener. The internal teeth elastic pads are used under the screw head with smaller head size; the elastic pads of the outer tooth are mostly used for bolt heads and nuts. The elastic cushion with teeth is smaller than the ordinary spring pad. The fastener is uniform and reliable to prevent loosening, but it is not suitable for the regular disassembly. See GB93, GB859 ~ 860 and GB955;

c) Anti -retreat cushion ring: there are inner tooth lock pads, outer tooth lock pads, single -ear stopped pads, binocular stopped pads, and round nuts. Single -ear and binocular stopped pads are allowed to tighten the nuts to lock in any position, but the fastener should be based on the edges.

d) Cingard ring: In order to adapt to the obliqueness of the working support surface, the oblique cushion ring can be used. The square diagonal cushion ring flattes the tilt surface of slot steel and the wing margin of the workers, so that the thread support surface is perpendicular to the nail pole, and the screw is bent when the nut is tightened. See GB852 ~ 853, etc.

Blocked circle

a) Elastic gear: The shaft and the elastic ring of the hole are stuck in the shaft groove or the hole groove for rolling shafts. Positioning, but not axial force. See GB893 ~ 894 and GB896;

b) Steel wire transmission: Pole (shaft) steel wire transmission and steel wire lock ring. The steel wire is installed in a shaft groove or hole slot for parts of the parts for positioning of the parts. See GB895.1 ~ .2, GB921;

c) The shaft parts with a tight gear: The gear that is locked with a tight -selling and lock -locked gear is mainly used to prevent the axial movement of the parts on the axis. See GB883 ~ 892.

d) Axial end gear: The shaft end of the screw tightening and the shaft end of the axis tightened with bolts are mainly used to lock the parts fixed at the axis end. See GB883 ~ 982.


a) Cilum sales: Cilum sales are mostly used for fixed parts on the axis, transmitting power, or positioning components. Cilum sales have different diameter tolerances, which can be used for different cooperation requirements. The cylindrical sales generally rely on the over -profile fixing in the hole, so it should not be disassembled. See GB119 ~ 120, GB878 ~ 880;

B cone sales: cone sales have a cone of 1:50, which is convenient for installation to the eye, and can also ensure self -locking. It is generally used as a positioning element and connection element, which is mostly used to require frequent disassembly places. Internal thread cone sells and threaded tail cone sales, for not being connected or used in holes that are difficult to make nails. Open the tail cone and the end of the hole can be opened to prevent the nails from slipping out of the hole. See GB117 ~ 118, GB881 and GB877.

The cylindrical sales and various cone sales holes are generally required to be processed by the rectus holes. After multiple installations, the accuracy of the positioning and the tightening of the connection will only be transmitted. The elastic cylinder sales itself has elasticity. It maintains tension in the holes. It is not easy to loosen, easy to disassemble, and does not affect the complexity. Bringing holes and sales axes are used for hinge integration;

c) Open sales: Open sales are anti -loose devices for connecting parts. When using, penetrate the bolts of nuts, bolts with holes or other connectors, and then separate the feet. See GB91.


a) Hot forging rivets: The general specifications are large, mostly used for locomotives, ships and boilers, etc., usually need to make the head formed by the hot forging, see GB863 ~ 866;

b) Cold 镦 rivets: Generally, the diameter specifications are 16mm. Usually, the head is formed by the coldness. See GB867 ~ 870, GB109, etc.

c) Halogican and semi -air heart rivets: hollow rivets are used for small shear, and are often used to connect non -metal parts such as plastic, leather, wood, canvas.

Product Recommendation: china nylon insert flange nut

You might also enjoy: