SINO Testing Services| 2020-09-28|Return
Explosion proof electrical equipment is achieved through an explosion-proof casing. If the bolts used as fasteners are damaged, the gap between the explosion-proof joint surfaces of the explosion-proof casing cannot be guaranteed, resulting in explosion transmission. It can be seen that the role played by bolts as fasteners is crucial.
The design of fastening bolts for explosion-proof shells mainly focuses on bolt strength, cast aluminum shell thread strength, calculation of pre tightening torque of bolts, anti loosening and accuracy of bolts, and other aspects.
There are generally two types of explosion-proof shells: flat and sealed. For flat structures, bolts not only play a tightening role, but also ensure the clearance between the planes. For the sealing structure, when the explosion-proof surface only considers the cylindrical part, the bolt only plays a tightening role, while ensuring the clearance effect of the flat part. When threading directly on the casing, attention should be paid to avoiding the threaded holes of fasteners passing through the explosion-proof casing as much as possible. When threading through the casing, there should be a margin of 3mm or more at the bottom of the threaded holes. When using lightweight alloy materials such as aluminum alloy for explosion-proof casing, due to the low strength of aluminum alloy, it is necessary to open it regularly (such as when changing the light source). When tightening the explosion-proof casing with screws, threads should not be threaded directly on the aluminum alloy casing, Use pre embedded anti loosening inner and outer threaded steel sleeves to increase the strength of screw holes and prevent failure due to thread decay. Do not replace the light source or open the bolt that was already installed at the factory during maintenance. You can directly tap the fastening screw hole on the outer shell, but do not use fine thread. Try to use coarse thread and have enough engagement buckles to meet the fastening requirements.
In short, when designing shell fasteners, it is preferable to distinguish clearlyExplosion proofThe role in the shell. Is it only for tightening purposes, or is it for both tightening purposes and ensuring plane clearance, and then confirm that the appropriate bolt is selected for the maximum axial load of the bolt.
The copyright of this article belongs to Zhongnuo Testing. Our company reserves the right to pursue plagiarism and theft. When reprinting, please indicate the source of the original text.