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Precautions in annealing silicon steel sheet EI stress relief annealing process
Jan 17, 2019

In the EI annealing process of annealed silicon steel sheet, if the laminated core is annealed before assembly, the single-piece annealing has a wider heating surface and more voids, which is favorable for convection and temperature uniformity is easier to control, but most of them are stacked and annealed.

The three-dimensional roll core material frame is specially protected. Some enterprises only use the jig without the rack and directly put it on the stove, while some enterprises have three clips annealed together.

If the vacuum silicon annealing furnace is used to vacuum-anneal the annealed silicon steel sheet EI, there is no air in the furnace after vacuuming, and the iron core is completely heated by the heat, and there is no air convection.

In some enterprises, the iron core is firstly vacuumed and then filled with nitrogen, which can shorten the holding time and extend the life of the furnace. When nitrogen enters the furnace, convection exists.

When the nitrogen is filled into the furnace, a bottom-up flow will be formed. The heat flow will agitate the entire furnace with each other, and the air in the furnace will be static. After the temperature rises to the temperature required for annealing, after the constant temperature process, nitrogen is added to the cooling process. Once the nitrogen enters the furnace, the furnace collapses.

Annealed silicon steel sheet EI annealing temperature rise and heat preservation stage is a vacuum state, only begin to enter the cooling stage, nitrogen filling, nitrogen filling is not completed in one time, only 500 degrees below, pressure 80000 Pa and above to start the fan, accelerate nitrogen flow, otherwise high temperature When the temperature is rapidly cooled, the cold is too fast, which causes the iron core to generate stress, which in turn affects the core air loss.

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