(1) considering the working efficiency of processing and assembly, the varieties of standard parts used in the same machinery or project shall be reduced as far as possible.
(2) in consideration of economy, the standard parts should be preferred.
(3) according to the expected use requirements of standard parts, the type, mechanical performance, precision and thread shall be selected.
① General purpose bolt: there are many kinds of bolts, including hexagon head and square head. See the national standard gb5780-gb5790.
② Bolt for reaming hole: when using, the bolt shall be inserted into the reamed hole to prevent the workpiece from dislocation, see GB27, etc.
③ Anti rotation bolt: it can be divided into square neck and vertebrae, see gb12-15, etc.
④ Special purpose bolts: for example, for T-groove bolts, see GB37; for loose joint bolts, see gb798; for anchor bolts, see gb799, etc.
⑤ High strength bolt connection pair for steel structure: it is generally used for friction type connection of steel structures such as buildings, bridges, towers, pipe supports and hoisting machinery. See gb3632, etc.
① General purpose nut: mainly refers to hexagon nut, and there are many kinds of square nut, see gb41, gb6170-6177, etc.
② Slotted nut: mainly refers to the hexagon slotted nut, that is, it is machined on the top of the hexagon nut. It can be used together with screw hole bolt and split pin to prevent relative rotation of bolt and nut, see gb6178-6181, etc.
③ Lock nut: refers to the nut with locking function, including nylon insert hexagon lock nut, see gb889, gb6182, gb6183 and all metal hexagon lock nut, see gb6184-6187.
④ Special purpose nuts: such as disc nut, see gb62; ring nut, see gb63; cap nut, see gb802, gb923; knurled nut, see gb806, gb807 and embedded nut, see gb809, etc.
① Machine screw: it is divided into many varieties due to different head and groove types. The head types include cylindrical head, pan head, countersunk head and half countersunk head, and the head is slotted (slotted) and cross grooved. See gb65, gb67-69 and gb818-820, etc.
② Set screw: the setting screw uses its tail end to prevent mutual displacement between workpieces and transfer less torque. See gb71, gb73-75, gb77, gb78, etc.
③ Hexagon socket screw: it is suitable for small installation space or the screw head needs to be embedded. See gb70, gb6190, gb6191 and gb2672-2674.
④ Special purpose screws: for example, see gb72, gb828 and gb829 for positioning screws; see gb827-839, gb948, gb948 and lifting eye screws, see gb825 for non pulling out screws.
① Unequal length double head stud: it is applicable to the occasions where one end is screwed into the body of parts to connect or fasten. See gb897-900, etc.
② Equal length double head stud: it is suitable for connecting end and nut to connect or fix distance. See gb901, gb953, etc.
① Flat washer: used to overcome the uneven bearing surface and increase the stress area of the bearing surface. See gb848, gb95-97 and gb5287.
② Spring (elastic) washer: see gb93 and gb859 for spring washer and gb860, gb955 for elastic washer.
③ Retaining washer: locking washer with internal teeth, see GB861; locking washer with external tooth, see gb862; locking washer with single lug, see gb854; retaining washer with double lug, see gb855; locking washer with round nut, see gb858, etc.
④ Bevel washer: in order to adapt to the inclination of the workpiece bearing surface, the inclined washer can be used. See gb852 for I-shaped steel and gb853 for channel steel.
(6) self tapping screw:
① Ordinary self tapping screw: the thread conforms to gb5280 (thread for self tapping screw), with large pitch, and is suitable for use on thin steel plate, copper, aluminum and plastic. See gb845-847, gb5282-5284, etc.
② Self tapping locking screw: the thread conforms to the general metric coarse thread, which is suitable for vibration resistance. See gb6560-6564.
① Hot forging forming rivets: generally large in size, they are mostly used in locomotives, ships and boilers, etc. the head is usually shaped by hot forging. See gb863-866.
② Cold upsetting forming rivet: the general diameter specification is ≤ 16mm, and the head is usually formed by cold heading. See gb867-870, GB 109, etc.
③ Hollow and semi hollow rivets: hollow rivets, see gb976; semi hollow rivets, see gb873-875, etc.
④ Special purpose rivet: head rivet, see GB 1016; tubular rivet, see gb975; label rivet, see gb827, etc.
⑤ Core pulling rivet: it belongs to single side riveting rivet. It is a new type of rivet widely used in recent years. It has the characteristics of rapidity, safety and convenience, and has the advantages of waterproof and anti leakage.
① Cylindrical pin: see gb119 for threaded cylindrical pin, see gb120 for internal thread cylindrical pin, see gb878 for external thread cylindrical pin, gb879 for elastic cylindrical pin, and gb880 for cylindrical pin with hole.
② Taper pin: see gb117 for threaded cylindrical pin, see GB118 for internal thread cylindrical pin, see gb881 for threaded tapered pin, and see gb877 for open ended tapered pin.
③ Split pin: generally with screw hole bolt and slotted nut to prevent bolt and nut from loosening. See gb91.
(9) retaining ring:
① Elastic ring: elastic ring with hole. See GB893; elastic retaining ring for shaft. See gb894 and shaft split ring gb896.
② Steel wire retaining ring: steel wire retaining ring with hole, see gb895.1; steel wire retaining ring for shaft, see gb895.2 and steel wire lock ring, see gb921.
③ Locking ring for shaft parts: refer to gb883 for retaining ring locked with taper pin; see gb884 and gb885 for retaining ring locked with screw.
④ Shaft end retaining ring: shaft end retaining ring fixed with screws, see gb891 and bolt tightening