Introduction to the basic knowledge of aerospace parts processing of stainless steel aviation parts
We know that a lot of parts are needed in aerospace equipment, among which fasteners are indispensable parts. Without fasteners, thousands of parts of an aircraft will not be able to be combined together. Today, stainless steel aviation parts processing will briefly introduce the basic knowledge of fasteners.
1. Thread type
There are many standards for threads, including:
1. For coarse threads and fine threads of the same size and number, if the threads are the same, the nominal diameter of the threads is the same, but the number of teeth per inch is different.
2. The distribution of tolerances is different. The specific regulations for threads with a diameter of 1 inch are different. For example, NF stipulates that 14 teeth are used per inch, generally expressed as 1-14NF, and UNF stipulates that 12 teeth are used per inch, expressed as 1-l2UNF.
2. Fit level
Threads are divided into different levels. These different levels of threads indicate the degree of fit tightness that the threads should have.
Generally speaking, it has five levels. Level 1 means loose fit. When using it, you can easily turn the nut by hand. Level 2 means free fit, which is suitable for aviation screws. Level 3 means medium fit, and most aviation bolts need to reach this level. Levels 4 and 5 are tight fits, which require special tools. The larger the level, the tighter the thread pair fits.
III. Identification symbols
Generally, the bolt diameter, length, and material parameters of the fasteners are marked. The unit of measurement for the diameter is 1/16in, and the unit of measurement for the length of the fuselage bolt rod is 1/8 in. The manufacturing material of the bolt is generally marked with English letters or symbols. "C" indicates that the material used is stainless steel; "DD" indicates that the material used is 2024 aluminum alloy; "-" indicates that the material used is nickel alloy steel.
3. Nuts
There are many types of nuts used in aerospace. Here are some commonly used nuts:
1. Standard aviation nuts
For example, AN310 slot top nuts are generally used with AN3~AN2O fuselage bolts. Its thread standard is NF (fine thread). Nickel alloy steel, stainless steel and 2024 aluminum alloy materials can be used to produce this nut.
2. Self-locking nuts
The conventional models of low-temperature self-locking nuts are AN365, AN364, etc. When locking, insert an elastic ring in the thread. The inner diameter ratio is slightly smaller than the thread. Turn the nut to let the bolt pass through the bottom thread. When it needs to enter the top thread, the resistance of the elastic ring should be overcome, so that the bolt thread and the nut can be coordinated. There are requirements and restrictions when using this fastener on the aircraft, and it should be used according to the requirements.
4. Washers
The main functions of washers in aerospace fasteners are: to make the force under the nut or bolt head more uniform, adjust the distance between the thread and the component surface, and also play the role of locking, anti-loosening and pre-tightening indication. The more commonly used washers are AN960 ordinary washers, AN935 open elastic washers, AN936B type external tooth elastic washers, etc.
The basic knowledge of aerospace parts is introduced here first. I hope everyone can have a general understanding of aerospace fasteners after reading it.
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