The hottest screw family is so huge

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The screw family is so large

it is mostly used for the connection of smaller parts. It has pan head screws, cheese head screws, half countersunk head screws and countersunk head screws. Pan head screws and cheese head screws have higher head strength, which are connected with ordinary parts; The head of the countersunk head screw is curved, and its top is slightly exposed after installation, which is beautiful and smooth. It is generally used in instruments or precision machinery; Countersunk screws are used where the nail head is not allowed to be exposed

II. Hexagon socket and hexagon socket Torx screws

the head of this kind of screw can be embedded in the component, which can apply large torque and have high connection strength, and can replace hexagon bolts. It is often used at joints with compact structure and smooth appearance

III. cross recessed ordinary screw

it has the same function as slotted ordinary screw and can be replaced with each other, but the cross recessed ordinary screw has high groove strength, is not easy to screw bald, and has a beautiful appearance. When in use, the matched cross screwdriver must be used for loading and unloading

IV. eyebolt

eyebolt is a kind of hardware accessory for bearing during installation and transportation. When in use, the screw must be screwed into the position where the bearing surface fits closely. It is not allowed to use tools to tighten it, nor is it allowed to have a load perpendicular to the plane of the lifting ring acting on it

v. set screw

set screw is used to fix the relative position of machine parts. Screw the set screw into the screw hole of the part to be tightened, and press its end tightly on the surface of another part, that is, fix the former part on the latter part

set screws are usually made of steel or stainless steel, and their end shapes include conical, concave, flat head, cylindrical and stepped shapes. The end of the conical end or concave end set screw is directly used to tighten the parts, which is generally used for places that are not often disassembled after installation; The end of the flat end set screw is smooth, and will not damage the surface of the part after tightening. It is used at the connection where the position needs to be adjusted frequently, and can only transmit small loads; The cylindrical end fastening screw is used in the fixed position that needs to be adjusted frequently. It can bear a large load and effectively pull the market demand of new energy materials, but the anti loosening performance is poor, so anti loosening measures need to be taken when fixing; Step set screws are suitable for fixing parts with large wall thickness

VI. self tapping screw

when the self tapping screw is used on the connected part, the connected part can not be threaded in advance. When connecting, use screws to directly tap out the threads. It is often used to connect thin metal plates. There are two kinds of self tapping screws: cone end self tapping screws and flat end self tapping screws

VII. Self tapping locking screw

self tapping locking screw not only has self tapping effect, but also has low screwing torque and high locking performance. Its thread has a triangular cross-section, and the surface of the screw has been hardened with high hardness. Its thread specifications are m2-m12. [2]

specification and model

screw specification and model

example: 4 x 10 PW a H C (+)

① ② ③ ④ ⑤ ⑥ ⑦

① screw diameter ② screw length ③ screw head type

b: spherical cylindrical head; C: Cylindrical head; F (k): countersunk head; H: Hexagon head; HW: Hexagon head with washer; O: Semi countersunk head; P: Pingyuan head; R: Half yuan head; PW: flat head with washer; T: Big flat head; 5: Mushroom head

④ screw tooth type

a: self tapping sharp tail (Japanese standard type 1) sparse AB: self tapping sharp tail (Japanese standard type 4) dense; B: Self attack flat tail (Japanese standard type 2) sparse; C: Self attack flat tail (Japanese standard type 3) dense; P: Double filar teeth HL: high and low teeth U: pineapple teeth; T: Self tapping flat tail cutting foot at: self tapping screw tip tail cutting foot M: mechanical tooth; Btt:b triangle teeth cct:c triangle teeth ptt:p triangle teeth stt:s triangle teeth

⑤ heat treatment H: with heat treatment n: without heat treatment

⑥ surface treatment

zn: white zinc C with the rapid increase of vehicle ownership: Color zinc B: blue zinc F: black zinc o: black oxide Ni: nickel Cu: green copper br: red copper P: phosphating

(+): cross groove (-): slot (T): Chrysanthemum groove(h) : hexagonal socket (PZ): M-shaped groove

(+ -): +- groove (y): Y-shaped groove (H): H-shaped groove (L): knurled tooth (WIS): single movable spring washer

(WIF): single movable flat washer (wit): single movable external tooth washer (w2sf): double movable spring washer

(w=6mm): washer outer diameter equal to 6mm (SUS): stainless steel (Cu): brass (BR): red copper (8.8): grade 8.8 screw (10.9) : grade 10.9 screw (12.9): grade 12.9 screw (R): other notes

① nominal thread outer diameter (thread specification): there are two kinds: metric system and British system

metric thread → common specifications are 2; 2.3 ; 2.5 ; 2.6 ; 2.9 ; 3 ; 3.1 ; 3.5 ; 4 ; 4.2 ; 4.5 ; 4.8 ;

5 ; 6 ; 8 ; 10 ; 12 ; 14; 16; 20 。 Unit: mm

inch thread → common specifications are 2 #; 4#; 6#; 8#; 10#; 12#; 1/4; 7/32; 5/16; 3/8; 1/2 ; 9/16; 3/4 。 Only adhere to the legal administration position in (English)

② number of teeth/pitch:

definition of number of teeth → number of teeth contained in one inch (25.4mm) length

pitch definition → distance value between two adjacent threads

number of teeth, pitch conversion → pitch =1 inch/number of teeth

③ nominal length: metric system and British system

metric nominal length → common values are 5, 6, 6.5, 7, 8, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20,

21, 25, 28, 30, 31, 32, 35, 40, 42, 45, 50, 55, 60, 65, 70, 75, 80, 85,

90, 95, 100, 110, 120. Unit: mm

British nominal length → common values are 1/4, 5/16, 3/8, 7/16, 1/can fill thin molds 2, 5/8, 3/4, 1, 2, 3. Unit: inch

④ head type: use letters to indicate the type of head type. See the classification of commonly used screw head types above

⑤ tooth type/tail type: use letters to indicate the type of tooth type/tail type. See the previous "classification of common screw tooth type/tail type"

⑥ groove type: refer to the previous "classification of groove types of our company's commonly used screws", cross groove or non groove (such as punching hexagon head screws) do not need to be marked here, and other groove types

need to be explained in words

⑦ special annotation: generally, there is no need to annotate. When expressing its characteristics, it is described in words at this position

for example, the screw specification name is described as ".7x70pm ± tooth length 35", which means that "4" is the nominal diameter of the screw thread, "0.7" is the tooth

distance, 70 "is the nominal length value of the screw," P "indicates that its head type is Pan head," m "indicates that its tooth type/tail type is machine thread tooth type," ± "

indicates that its groove type is" ± groove ", which can also be represented by" addition and subtraction groove ". "Tooth length 35" is a special mark, which specifies the tooth pattern length value of this screw

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