NEWS
Make an unqualified bolt, and your head will bleed on the spot, and you will be horrified to see it!
In just five minutes, the short video "Luo Si"
It is said that the embankment of thousands of miles collapses in the ant's nest. Don't look at the small size of the screw (relative to the equipment where it is located). If it really starts a fire, the temper is not small. If it is light, it will lead to unplanned downtime and reduce production efficiency, and if it is heavy, it will cause a catastrophe and cause huge losses.
Accidents that require screws to back the pot abound in history。
Case one
On June 10, 1990, during the flight of British Airways flight 5390, a piece of the windshield of the cabin suddenly flew off, and the upper body of the captain was sucked out of the aircraft. Fortunately, with the efforts of the co-pilot, it landed safely at Southampton Airport.
Case two
During the lunch rush in September 2009, a ceiling fan in the cafeteria of Guangzhou University of Technology suddenly fell from the ceiling. The rapidly rotating electric fan injured and scratched two students. The cause of the accident was that the screws fixing the electric fan fell.
Case three
Case four
Case five
。。。。
There are still many bloody lessons
Every time I see such an accident
We who eat melons will always be angry and courageous.
Isn't it just a matter of screwing a screw?
What do maintenance workers do?
Why does such an accident always happen?
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Let's take a look at the working principle of bolts
They use the circular rotation and friction of the bevel of the object
Gradually tighten the parts of the artifact step by step
Therefore, whether the bolts are fastened or not is to a large extent
It depends on whether it is tightly engaged with the threaded area of the fixture
However, is the bolt really tightened once and for all?
The teeth are hard, it's okay to touch the tongue
It will only ring if you knock on a hard object, and it will break and loosen if you knock hard.
Whether it is a bolt, nut, or a fixed material
Most of the surfaces are hard and will not accommodate each other.
Most of the working state of the machinery is repetitive movement
Some movements are accompanied by severe vibration and shock
Under frequent vibration
The thread that was originally tightly clamped
It will produce tiny gaps and even deformation
Accumulated to a certain extent
It will cause subtle displacement and spin
So the bolts that were originally tightened slowly loosened.
Therefore, sometimes you can't rely on maintenance workers
Machinery must be maintained regularly to avoid accidents
Prevent sudden shutdown due to loose bolts
Sometimes the cost of downtime is also very expensive, okay?
Loose rail bolts, potential derailment factors
The properties of bolt shake M are also used for testing
To detect the fasteners under certain frequency and amplitude conditions
Self-locking performance under applied transverse dynamic load (anti-loosening performance)
This is the Juncker vibration test
Comparison of Juncker vibration tests on different bolts
Servo automatic tightening device is used during the test
Automatically tighten the bolt/nut according to the set initial clamping force or torque
After that, the vibration environment is simulated according to the set test parameters and conditions
Analyze fasteners through recorded technical indicators
Changes in axial force, loosening angle, amplitude, horizontal thrust, etc.
Which is the strongest nut washer?Below is a video of the Junker vibration test of 13 kinds of nut washers.
Video data
Obviously it looks very reliable
I actually shook it a few times and it loosened.
Most of the nuts and washers in the video are still relatively fast.
Oh yeah, it's so scary to think about it
Isn't there no screw in the world that won't loosen?