Solutions for high strength nuts in the manufacture of industrial equipment

High-strength nuts made of high-strength steel, or the need to apply a large preload of nuts, can be called high-strength nuts. High-strength nuts are mainly used for bridges, rails, and high-pressure and ultra-high-pressure equipment connections. The fracture of this nut is mostly brittle. A large pre-stress is needed to apply to the ultra-high pressure equipment on the high-strength nuts to ensure the sealing of the container. High-strength nuts play a crucial role in advanced manufacturing, represented by aircraft manufacturing, large power generation equipment production, automobile production and manufacturing, high-speed trains, large ships, large sets of equipment, etc., as a critical connection solution. High-strength bolts connect necessary machinery, and various high-strength bolts' repeated disassembly or installation torque method is highly demanding. The surface condition and thread accuracy will directly affect the service life and safety of the main machine. The technical requirements stipulate that the surface should be treated with nickel-phosphorus plating to improve the friction coefficient and avoid rusting, galling, or jamming during use. Plating thickness to ensure that the range of 0.02 ~ 0.03mm, uniform plating, dense, no pinhole, etc. Used in high-strength bolts, strength level (after heat treatment) for 10, with 10.9 bolts, high-strength bolts are mainly used in some critical mechanical equipment connections, wildly to disassemble repeatedly, and various assembly methods are extremely high requirements for the nut. The threads' surface condition and accuracy will affect equipment use and safety, such as steel structure bolts and nuts, high strength bolts and nuts, hexagonal bolts, hexagonal nuts, chemical bolts and nuts, and other shaped parts.

The process of nickel-phosphorus plating of high-strength nuts nickel-phosphorus plating consists of three parts.

The first part is the pre-treatment process, including precision and appearance inspection, manual oil removal, oil removal by immersion, pickling, electric activation, and flash nickel plating before plating of high-strength nuts;

The second part is the chemical nickel plating treatment process;

The third part is the post-treatment process, including hydrogen-repellent heat treatment, polishing, and finished product inspection. As follows: nut chemical composition inspection → nut pre-plating precision and appearance inspection → manual oil removal → appearance inspection → immersion oil removal → hot water washing → cold water washing → acid washing → cold water washing → electric activation → cold water washing → flash nickel plating → cold water washing → deionization water washing → chemical nickel plating → deionization water washing → cold water washing → hydrogen repelling → polishing → finished product inspection.

Precautions for high-strength nuts

Quality precautions

(1) Surface floating rust, oil, bolt hole wall with burrs, weld tumor, etc., should be cleaned up.

2. The contact friction surface should reach the required anti-scratch coefficient after treatment. High-strength bolts should have matching nuts and washers when used by the matching use, but they are not interchangeable.

3. The friction surface of the treated component cannot be stained with oil, dirt, and other debris when installed.

4. The friction surface of the components should be kept dry during installation and not be operated in the rain.

5. Strictly check and correct the deformation of the connected steel plates before installation.

6. Hammering into the bolt is prohibited during installation to prevent damage to the bolt fillet.

7. Test the electric wrench regularly to ensure the torque accuracy and operate it in the correct torsion order.

Central safety technical measures.

1. The active wrench size should match the nut size, and no casing should be added to the small wrench. High-altitude operations should use dead wrenches, such as live wrenches with a tethered rope, and people should be tied with a safety belt.

2. When assembling the bolts connecting the steel components, it is strictly forbidden to insert the connecting bolts by hand.