The reason for the locking of stainless steel bolts
A. The deflection point of thread cooperation and the soft characteristics of stainless steel are easy to cause the locking of stainless steel bolts
1. The cooperation of stainless steel bolts and stainless steel nuts belongs to vacant cooperation, and there are international standard public service plans implemented by themselves. Therefore, the center axis of the inner and outer threads is not on the same line when they cooperate, and the contact between the inner and outer threads should be reduced due to skewness. noodle.
2. The larger the deflection angle of the stainless steel bolt and the stainless steel nut, the smaller the force-bearing area of the thread cooperation, and the easier the tooth pattern is damaged.
3. The force during the locking process is uneven or skewed, and the central axis of the stainless steel bolt and stainless steel nut is skewed to the maximum extent, so that the working surface of the stainless steel bolt and the stainless steel nut thread is not completely touched, and the surface force is changed to point force. The force or the force on each unit increases.
4. The stainless steel bolt is softer than the carbon steel screw. If the iron scraps fall off during the locking process, it will stick and not fall off, and then the thread will enter and exit smoothly, causing the bottom of the tooth to die on the top of the tooth.
B. Excessive locking force and low thermal conductivity of stainless steel can easily lead to thread locking
1. During the rotation of the screw and nut, due to the heat generated by the conflict, the thermal conductivity of stainless steel is relatively low. When the pressure and heat generated destroy the chromium oxide layer (the oxide layer that makes stainless steel not easy to rust), the metal tooth pattern occurs directly. Blockage, coupled with the soft characteristics of stainless steel, and then the phenomenon of sticking occurs. The greater the locking force, the greater the heat generated, and the easier it is for the stainless steel of the screw teeth to stick.
2. When locking the stainless steel nut, the torque (locking force) must be greater than the conflicting force of the stainless steel bolt and the stainless steel nut itself before the nut can be rotated. When the nut rotates and descends along the thread line, the stainless steel bolt will extend due to the action of the reaction force. When the torque (locking force) exceeds the yield point (ie safe torque) of the screw, the screw will generate residual strain and maintain the elongation state. . When the screw stretches beyond its elastic design, permanent deformation occurs and the thread locks
The treatment method of stainless steel bolt locking
1. Keep the central axis of the stainless steel bolt and stainless steel nut straight with the locked surface to reduce the deflection angle.
2. Try to use a manual wrench to slow down the locking speed, keep the threads clean, use lubricating oil to reduce the friction coefficient, reduce heat energy, and then reduce adhesion.
3. Use a torque wrench or socket wrench as much as possible to avoid excessive force and control the torque within the safe torque plan.
4. Select products with relatively high hardness to reduce thread shearing.
5. The use of stainless steel anti-locking agent has a significant effect on reducing the lock-up share.
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Post time: May-23-2022
