development process
Locknut originated in foreign countries, it is a special engineering plastic permanently attached to the thread, so that the internal and external threads in the tightening process, engineering plastics are squeezed to produce a strong reaction force, greatly increased the internal and external threads Friction provides absolute resistance to vibration.
This resistance is completely distributed in the entire meshing section of the internal and external threads, and the frictional force is independent of the contraction pressure between the internal and external threads, unlike the previous retraction method, relying on the friction generated by the tightened pressure of the screw. From the stop and retreat function, once the screw is slightly loose, the pressure decreases, the friction quickly disappears and loses the back-stopping effect, so that the screw is loosened. However, the plastic anti-loose method is affected by the environment and cannot meet the requirements of high temperature and severe cold. It is necessary to explore a new anti-loose technology.
The locknut was invented 35 years ago in the United States. There is a 30 degree wedge surface at the tip of the traditional 60-degree tooth tip. This structure makes the male and female threads get larger than traditional threads after tightening the nut. Friction in order to achieve anti-looseness.
Due to the change in the angle of the conical shape, the normal force generated by the contact between the threads is made at an angle of 60 degrees with the axis of the bolt, instead of 30 degrees like the normal thread. The normal pressure of the thread is far greater than the fastening pressure, and therefore, the resulting locking friction force must be greatly increased. When the male thread crest is engaged with the female thread, the tip of the crest is easily deformed, so that the load is evenly distributed over the entire length of the contacted helix. When the common standard thread is occluded, more than 80% of the total load concentrates. The phenomenon of the thread surface of the first and second teeth. Therefore, the threaded coupling pair not only overcomes the disadvantage that the common standard coupling pair tends to loose under vibration conditions, but also can prolong the service life.
Due to this special way of preventing tooth deformation, it can be re-detached 5 to 50 times, and the anti-loosening function is still persistent. Because this kind of anti-loose method has high vibration resistance, light weight, and repetitive disassembly, it has become the most reliable anti-loose product today.
After the anti-loose screws are called locking screws, they are best applied to the fastening of moving parts. They were first used on NASA, and later they were promoted to the US automobile manufacturing industry. With the maturity of manufacturing technology and the reduction of costs, It is widely used in 3C, bicycles, skating skiing equipment, furniture, sports equipment, medical equipment and many other industries. It completely replaces the traditional anti-return washers and fully demonstrates the reliability of the locking and anti-loosening effect of the locking screws.
Anti-loose method
The lock nut is a nut, which is screwed together with a bolt or a screw to play a fastening part. All production machinery must use an original, and the lock nut is a part that closely connects the mechanical equipment through the inside. Threads, the same size locknuts and screws, can be connected together, the following details for you to explain the pine nuts to avoid slack four ways.
Mechanical locking
The relative rotation of the lock nut pair is directly limited by the lock nut stopper. Such as the use of tooth pin, series wire and locking washers. Since the lock nut stopper has no pretightening force, the lock-up nut works only when the lock nut nut is loosened to the stop position. Therefore, in this way, the lock nut is not loosened in practice but prevented from falling off.
Riveting
After being tightened, punching points, welding, bonding, etc. are adopted so that the lock nut pair loses the motion auxiliary characteristics and the connection becomes inseparable. The drawback of this method is that the bolt can only be used once, and the disassembly is very difficult. The bolt must be destroyed before it can be disassembled.
Friction-proof
This is the most widely used anti-loosening method, which generates a positive pressure that does not change with the external force between the lock nut pairs to generate a frictional force that can prevent relative rotation of the lock nut pair. This positive pressure can be accomplished by axially or simultaneously compressing the lock nut pair in both directions. Such as the use of elastic washers, double nuts, self-locking nuts and insert lock nuts.
Structure protection
It is the application of a duplicated body of the locking nut, which means that Down's locking nut prevents loosening.
The three advantages of locknuts:
First, superior anti-vibration performance: When the thread is tightened, the thread angle of the thread of the screw head is tightened tightly into the 30° wedge bevel of the nut, and the normal force generated by the bolt applied to the wedge bevel is The axis is at an angle of 60° instead of 30°. Therefore, the normal force generated when the locknut is tightened is much larger than that of an ordinary standard nut, and it has a great ability to prevent looseness and vibration.
Secondly, it has strong wear-resistance and shear resistance: 30° bevel of the nut thread bottom can evenly distribute the tightening force of the nut on the threads of all the teeth, because the pressing force on each thread surface is evenly distributed. Nuts can better solve the problem of thread wear and shear deformation.
Third, the repeated use of good performance: a large number of uses show that the locking nut after repeated fastening and disassembly, the locking force is still not reduced, can maintain the original locking effect.
Today's commonly used self-locking loose thread fasteners are:
1. Use a variety of self-locking bolts or ring groove rivets to achieve self-locking;
2. Install various spring washers in the screw connection to achieve self-locking;
3, glue on the thread to achieve self-locking.