Compared with nitrogen, hydrogen has the advantages of good thermal conductivity, low density, low dynamic viscosity and strong reduction, and gradually replaces the nitrogen-hydrogen mixture as the protective gas. At the same time, it puts forward more stringent requirements for the safety control of bell furnaces.
First of all, the protective cover and the metal shell of the stove are all X-ray flaw detection to strictly ensure the processing quality of each equipment. Secondly, at the beginning of the annealing cycle, all the gauges and switch positions are checked so that they are placed in the correct set position. After the inner cover is fastened to the prepared stove, the leak detection of the hydrogen inlet valve is carried out, and then the leakage test of the furnace space is carried out to ensure that the furnace and inner cover system are completely sealed, and a tightness test is also carried out on the main gas opener and the hydrogen main opener. After passing the leak test, the furnace space is purged with nitrogen. Nitrogen purging must meet 3 conditions to end, a certain amount of nitrogen purging, the minimum nitrogen purge time: oxidation content less than 1%.
Bell furnaces are mostly used for annealing steel wires, steel pipes, copper strips, copper wires and silicon steel sheets in the metallurgical industry. Among them, copper strip is mainly suitable for heat treatment of brass strip, bronze strip, special-shaped copper strip, copper strip and other materials.
