I. Basic Functions: Connecting and Fastening
The core function of a nut is to work with a bolt, generating a preload through thread engagement to securely connect two or more components. For example:
1. Mechanical Assembly: In an automobile engine, an M10 nut can withstand an axial tensile force of approximately 10 kN (refer to the 5th edition of the Mechanical Design Manual), ensuring a stable connection between the cylinder block and the crankcase.
2. Building Structures: High-strength nuts (such as grade 8.8) are used in steel bridges, with a tensile strength of 800 MPa, capable of withstanding wind loads and vibration.
3. Daily Maintenance: When assembling furniture, nylon locking nuts can prevent loosening due to frequent shaking.
II. Advanced Functions: Safety and Special Needs
1. Anti-loosening Protection:
- Spring washer nuts use elastic deformation to offset vibration and are suitable for high-frequency vibration environments such as aircraft engines.
- Using two nuts in a stacked configuration (such as NASA standard MS21042) reduces the probability of loosening to less than 0.1% through secondary tightening.
2. Sealing and Vibration Isolation:
- Rubber-coated nuts (such as M6) are waterproof and dustproof and are commonly used in outdoor electrical boxes.
- In hydraulic systems, copper sealing nuts can withstand pressures up to 30 MPa, preventing oil leaks.
III. Innovative Applications in Special Scenarios
1. Quick Assembly and Disassembly: Butterfly nuts can be tightened manually without tools, making them ideal for emergency repairs of medical equipment.
2. Fine-Tuning Positioning: Precision instruments use fine-thread nuts (such as M1.2×0.25), offering an adjustment accuracy of ±0.01mm.
3. Extreme Environment Compatibility:
- Titanium alloy nuts withstand temperatures ranging from -200°C to 550°C and are used in spacecraft casings.
- Antimagnetic nuts (such as 316L stainless steel) prevent magnetic field interference in MRI equipment.