The maximum unscrewing torque of the bearing lock nut is affected by many factors.
When the material is cyclically loaded, the phenomenon of “cyclic strain hardening” or “cyclic strain softening” occurs, that is, under the condition of constant cyclic strain, the stress amplitude will increase or decrease with the increase of the number of cycles. After several cycles, the stress amplitude enters a cyclic steady state. The low-cycle fatigue of the bearing lock nut is carried out under the condition that the strain is constant, and the strain hardening or softening of the threaded piece will affect the size of its maximum unscrewing torque. The alloy steel used to manufacture the Lock Nut is a cyclic strain hardening material, and the hardening of the material will increase the elastic restoring force FN of the threaded sheet and increase the unscrewing torque.
Low cycle fatigue means that the fatigue stress is close to or exceeds the yield limit of the material, the material has a certain amount of plastic deformation in each strain cycle, the life is generally in the range of 102 to several times 104, and the fatigue curve is generally expressed by the ε-N curve . The finite element calculation results show that after the bolt is screwed into the bearing lock nut, the stress at the root of the thread piece is large, and part of the surface area is in a yield state, while the strain in the central area of the root of the thread piece is small, and the strain situation is more complicated. The area with high strain at the root of the thread piece experiences reciprocating loading, which is prone to low cycle fatigue, which reduces the pressure of the thread piece and reduces the screw-out torque.
The friction angle is an important factor affecting the torque, and the existence of friction is the basis for the normal operation of the bearing lock nut. When the Lock Nut is working, there is pressure and friction on the contact surface under the action of the elastic restoring force of the thread piece. During repeated use, the rough position and edges and corners of the contact surface are smoothed and smoothed under the action of cyclic friction. The coefficient of friction becomes smaller, which in turn reduces the maximum unscrewing torque of the nut.
Due to the limitations of manufacturing technology and precision, the edge of the thread has sharp corners or the dimensional coordination between parts is not coordinated. During the initial assembly, the torque of screwing in and screwing out may fluctuate or fluctuate to a certain extent, which requires a certain number of running-in times. In order to obtain a more accurate reusability of the bearing lock nut.
After the material and the geometric parameters of the nut are determined, the change of the closing value has an important influence on the repeated use characteristics of the bearing lock nut. When the closing value becomes larger, the deformation of the threaded piece increases, the strain of the threaded piece increases, the strain cycle hardening phenomenon intensifies, and the pressure FN of the threaded piece increases, which has a tendency to increase the unscrewing torque; on the other hand, the width of the threaded piece decreases. , the total area of the threaded piece decreases, the friction with the bolt decreases, the strain of the threaded piece increases, the low-cycle fatigue performance decreases, and the maximum unscrewing torque tends to decrease.
1.The first is to screw two nuts on the bolt of the same anchor and add a tightening torque between the two nuts to make the threaded connection reliable.
2.The second is a special type of bearing locknut that must be used with a lockwasher. The special lock nut is not a hexagon nut, but a medium round nut. There are three, four, six or eight gaps in the nut ring (depending on the nut size and the manufacturer’s product line). These gaps are not only the force point of the special tool for tightening, but also the clamping point of the lock washer interface.
3.The third type is to drill the surrounding threaded holes from the inner hole surface of the nut to the inner thread surface (usually two, and the outer surface is khaki) for screwing small-diameter countersunk head bolts. Its purpose is to release radial force on the threads to avoid loosening the locknut. The lock nut of good quality sold on the market is embedded with a small piece of copper that is consistent with the thread of the lock nut on the inner surface of the nut to prevent the axial top screw from immediately hitting the lock thread and damage the lock thread.
km10 skf 50x70x11mm
Axial static load carrying capacity:91.5 KN
Mass lock nut:0.14 kg
Wheel Bearing Lock Nut Set is ideal for servicing wheel bearing nuts on trucks and heavy equipment quickly and easily.
locknut sockets are designed to tighten and loosen locknuts safely and easily. They are used to secure and adjust the bearings on tapered bearings.
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