Although the spring pad is relatively common, there will be some problems in the use process, affecting the use effect, such as the open expansion ring. Many people in the discovery of this problem will be attributed to the quality of the spring washer, in fact, this is not necessarily the product quality caused by the spring washer in the use of the force situation and matching the use of the flat washer is not suitable and other reasons will lead to the spring washer expansion ring.
Under normal circumstances, the spring pad of the expansion ring must be subject to a radial external tension, the external tension is derived from the clamping axial force generated by the tightening torque, mainly because the external chamfer of the nut support surface makes the axial clamping force produce this component, resulting in the expansion of the spring washer opening, the smaller the diameter of the nut support surface chamfer, the higher the possibility of the spring pad expanding.
In addition, in order to slow down or prevent the expansion of the ring phenomenon, we usually add a flat washer between the nut and the spring washer, but if the flat washer we add is too thin or too soft, it can not prevent the expansion of the ring.
