Explosion proof electrical equipment is achieved through explosion-proof enclosures. If the bolts used as fasteners are damaged, the gap between the explosion-proof joint surfaces of the explosion-proof enclosure cannot be guaranteed, resulting in explosion transmission. It can be seen that the role of bolts as fasteners is crucial.
The design of fastening bolts for explosion-proof shells mainly focuses on bolt strength, thread strength of cast aluminum shells, calculation of pre tightening torque of bolts, anti loosening and precision of bolts, and other aspects.
There are generally two types of explosion-proof enclosures: flat and sealed. For planar structures, bolts not only serve as fasteners, but also ensure the clearance between the planes. For the stop structure, when the explosion-proof surface only considers the cylindrical part, the bolts only play a fastening role, while ensuring the clearance effect of the planar part. When threading directly on the casing, it should be noted that the fastener screw holes should not pass through the explosion-proof casing as much as possible. When passing through the casing, there should be a margin of at least 3mm at the bottom of the screw holes. When using lightweight alloy materials such as aluminum alloy for explosion-proof casings, due to the low strength of aluminum alloy, screws should not be directly threaded on the explosion-proof casing that needs to be opened frequently (such as when changing the light source). Instead, embedded anti loosening inner and outer threaded steel sleeves should be used to increase the strength of the screw holes and prevent failure due to thread decay. Do not replace the light source or repair the bolts that have already been installed at the factory. You can directly tap the fastening screw holes on the housing, but do not use fine thread. Try to use coarse thread and have enough meshing threads to meet the fastening requirements.
In short, when designing shell fasteners, it is preferred to distinguish them clearlyExplosion proofThe function within the casing. Is it only for fastening purposes, or is it for both fastening and ensuring plane clearance? Then confirm the maximum axial load of the bolt and select the appropriate bolt.
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