Several misunderstandings about fasteners

Several misunderstandings about fasteners

One, thickened nut

Some people often mistakenly believe that thickening the nut can increase the number of working turns of the thread, thereby improving the reliability of the coupling. In fact, the thicker the nut, the more uneven the load distribution between the threads of each circle, and the easier it is to cause the coupling. Loose.

Two, improper locking

Important bolts should be locked with anti-loosening device after assembly. When using a split pin to lock, the common mistake is to use a thin split lock or a half-piece split lock to lock; when using a spring washer to lock, the common mistake is that the gap of the washer opening is too small and loses elasticity; the lock is used to lock Yes, the common mistake is to lock the lock plate at the corners of the nut; the double nut is used to lock, the common mistake is to install the thinner nut on the outside and not tighten it tightly.

3. False and solid (Guide: Analysis of the reasons for the blackening of screw fasteners)

There are rust stains, scales, iron filings, sand and other impurities in the threads of bolts, nuts or screw holes, or there are burrs, sand and other impurities on the joint surface of the joints, which have not been removed before assembly. When tightening the bolts, Due to the blocking effect of impurities, the surface is tightened very tightly, and the torque value meets the requirements, but in fact the couplings are not really compressed; in addition, there is another situation, due to the top of impurities such as sludge and scale in the screw holes. The supporting effect, although the bolt torque complies with the regulations, the work piece is not compressed. Under such false solidity, vibration, load shock and temperature changes often cause the bolts to loosen quickly.

Four, one female with multiple pads

During installation, sometimes the bolts after assembly are too long, so someone installs many spring washers on one bolt. In this way, the spring washers are not evenly stressed during the solidification process, and some will break, causing the bolts The pre-tightening force decreases; or eccentric load is generated, which reduces the reliability of the bolt connection.

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