What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
As a commonly used data communication device, connectors are widely used in computers and TVs. Because common connectors such as D-SUB and DVI are composed of a male seat and a female seat, the iron shell of the male seat and the female seat is The corresponding position is provided with holes, the holes of the male seat are connected with rivets, and the holes of the female seat are correspondingly provided with screws for fixing. After the male seat and the female seat are connected, tighten the screws so that the male seat and the female seat are tightly connected together. When assembling on a computer or a TV, the rivet has a fixed assembly direction, and the fixation of the rivet direction is very important for assembly. However, there is no anti-rotation device on the iron shell hole connected with the rivet on the existing connector, and the rivet cannot be positioned during the assembly process, and it is easy to rotate and dislocate. production efficiency.
ANSI B1.1 Thread Pitch Comparison Table Nominal Diameter (inch〖mm〗) Coarse Thread Pitch (UNC) Fine Thread Pitch (UNF) Ultra Fine Thread Pitch (UNEF) Drilling Diameter (Coarse Thread) Drilling Diameter (Fine Thread) #0 0.060 〖1.524〗 80 1.2 # 1 0.073 〖1.5 1.5 # 2 0.086 〖2.8 # 3 0.099 〖2.515〗 48 56 2.0 2.1 # 4 0.112 〖2.4 # 5 0.125 〖 3.175〗 40 44 2.5 2.6 # 6 0.138 〖3.50〗 32 40 2.7 2.9 # 8 0.164 〖4.166〗 32 36 3.4 3.5 # 10 0.190 〖4.0 # 12 0.216 〖5.486〗 24 28 32 4.5 4.6 1/4 6.35 20 28 32 5.1 5.4 5/16 10.7 11.5 9/16 〖14.288〗 12 18 24 12.3 13.1 5/8 〖15.875〗 11 18 24 13.5 14.7 3/4 〖19.05〗 10 16 20 16.7 17.5 7/8 〖22.125 2.4 9 14 〗 8 12 20 22.2 23.4 The pitch is expressed by the number of teeth per inch, such as: 11 teeth per inch, then the pitch=25.4/11=2.309mm. The unit of pitch in the table is the number of threads per inch. The hole diameter is the recommended hole size for tapping, in millimeters.
Earless retaining ring (known as Constant Section Rings abroad) is also called constant section retaining ring, because the cross section is equal, and there is no ear part protruding from the traditional stamping retaining ring, so it is called earless retaining ring. Earless retaining ring and spiral retaining ring have similarities in production, processing and use characteristics. They are both flattened and wound by steel wire. After heat treatment and surface treatment, they have good elasticity and toughness. Earless retaining ring is divided into two types: shaft use and hole use, and there are various forms of tail ends to choose from. The application of earless retaining ring is the same as that of traditional C-type retaining ring, which is widely used in hydraulic parts assembly, valves, instruments, various lock core components, needle roller bearings, pulleys, connectors, quick connectors and other mechanical assemblies.
The marking format of the thread mark is: Thread code - thread tolerance zone code (pitch diameter, top diameter) - screw length l) Tolerance zone code is represented by numbers plus letters (inner thread with uppercase letters, external thread with lowercase letters) , such as 7H, 6g, etc., it should be specially pointed out that 7H, 6g, etc. represent thread tolerance, while H7, g6 represent cylinder tolerance code. 2) The length of rotation is specified as short (represented by S), medium (represented by N), and long (represented by L). In general, the thread engagement length is not marked, and the thread tolerance zone is determined by the medium engagement length (N). If necessary, add the screw length code S or L, such as M20-5g6g-L. When special needs are required, the value of the screwing length can be indicated, such as M20-5g6g-30.
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