Brief introduction of bell furnace

The traditional hood furnace uses the mixed gas of nitrogen and hydrogen as the protective medium. Compared with nitrogen, hydrogen has the advantages of good thermal conductivity, low density, low dynamic viscosity and strong reducibility, and gradually replaces the mixed gas of nitrogen and hydrogen as protective gas. At the same time, stricter requirements are put forward for the safety control of the bell-type furnace.

First of all, the protective cover and the metal shell of the furnace have undergone X-ray flaw detection to strictly ensure the processing quality of each equipment. Secondly, at the beginning of the annealing cycle, check the positions of all instruments and switches to make them in the correct setting positions. After the inner cover is buckled on the prepared furnace, the leakage detection of the hydrogen inlet valve is carried out, and then the space leakage test of the furnace is carried out to ensure that the furnace and the inner cover system are completely sealed. At the same time, the main gas switch and the main hydrogen switch were tested for leakage. After the leak test is qualified, the space in the furnace is purged with nitrogen. Nitrogen purging must meet three conditions: a certain nitrogen purging amount and the shortest nitrogen purging time; the oxidation content is less than 1%.