Spring washer is a kind of mechanical equipment installed under the nut to prevent the nut from loosening.
Spring washer is widely used in the bearing and non bearing structures of general mechanical products. It is characterized by low cost, convenient installation and suitable for parts with frequent assembly and disassembly. However, the anti loosing ability of spring washer is very low, especially in the European and American countries which require high reliability products, especially the important load-bearing structure connection parts have been abandoned for many years. In our country, there are some applications in military industry, but the stainless steel materials are improved. It is said that the use of steel spring washer in CASC has been forbidden for a long time. It is said that it is very unsafe. There are two reasons: one is “expansion ring” and the other is hydrogen embrittlement.
The detailed use of this method is described in the national standards.
The hexagon slotted nut is specially used with the bolt with hole at the end of the screw, so as to insert the split pin into the screw hole from the nut groove to prevent the nut from loosening automatically. It is mainly used in the case of vibration load or alternating load.
In the mechanical design and manufacture, the methods to prevent the nut (or bolt) from loosening automatically are as follows:
1. Cushion spring washer; (simple and easy to make)
2. Use hexagon slotted nut + cotter pin; (increased processing procedures compared with the same period)
3. Pad the stop washer; (increased processing procedures compared with the same period)
4. Insert steel wire into hexagon head opening of hexagon bolt. (processing process increased year on year)