The electromagnetic overhead is specially designed for lifting billet, steel plate and steel scrap, etc. The electromagnetic overhead crane differentiates the ordinary hook beam crane in terms of crane lifting capacity.
The power of the electromagnet is supplied by the trolley through the cable reel or the cable basket to the beam.
For the hanging beam with the outage retentive function, the lifting mechanism should consider to choose direct current electromagnet brake; if the ac hydraulic push rod brake is used, the electromagnetic system should consider to set up ac and dc inverter, otherwise once the power outages, the brake contracts, which will rely on human force to open the brake and to place the loads in the safety zone.
Hanging beams should possess the capability of suspension electro-magnet.
Electromagnet for lifting multiple pieces of steel sheets
When the thickness of the steel sheet is 610mm, the spacing between each of electromagnets must be less than or equal to 3m, and at the same time, the designing and selection of other parts should be based on the 500 mm deviating from the center of the hanging beam or 6 times heavier than that of the lifting capacity unilaterally.
If the electromagnetic overhead crane adopts four block electric magnets, the capacity of the each electric magnet block is 0.3Q. When electromagnetic overhead crane is hanging more than one plates, in general, the air gap between the plates should be not more than 1 mm and the rated lifting capacity of the two electric magnet blocks should be 6 times of the steel plates’ weight. The steel plate may be bended or wrapped during production, therefore, a loose coefficient is used when selecting electromagnet, generally the following formula is used: Quantity of square billets X Width of the billet X 1.1 = Width of the magnet. For lifting long and rigid items, the balance of the magnetic beam is a concern. When four pieces of electric magnetic blocks are used, it can adopts the balance principle of lever, i.e., using a rope or panel pull crank to balance the two electromagnet blocks, making the electromagnet block bear even force. The balance of more than one electromagnet blocks can be realized by increasing the balance spring and rubber mat to solve the problem of height difference.
For the electromagnet with detachable poles, the weight of the magnet does not need to be reduced.
Electromagnet don't magnetize high manganese steel, stainless steel (defined by the non-magnetic quality). Electromagnet maximum heat resistance is 720C, higher temperature will make the magnet non-magnetic. At present, the vacuum suction cups is studied to make up the defects of the electromagnetism overseas.
Hanging beam according to the production requirements can be divided into parallel to girder type and the perpendicular to girder type, which solves the problem that the electromagnet cannot work in 720 C environment. For lifting items with different lengths, the length of the hanging beam is telescopic, which has solved the transportation problem and brought the very considerable economic benefits. The large scale steel mills are used this type of hanging beam crane, which is tends to be developed continually in the future.