Bell annealing furnaces are used for the most demanding annealing of coiled wires and sheets, as well as of small forgings and pressings made of steel and nonferrous metals. Due to its design, the furnace will allow heat treatment within a wide range of temperature curves, normally up to 850 °C (charge temperature).
The advantage of these furnaces is that bright annealing can be carried out with a broad range of materials thanks to the protective atmospheres used. Besides its standard nitrogen protective atmosphere, the furnace can also be operated under 100% hydrogen atmosphere.
A single furnace unit will mostly contain:
- two bases – a highly efficient circulation fan is built into such stands
- two protective covers – used to seal the space with the charge and protective gas, separating this space from the heated space
- one heating bell with a gas-fired or electrically-fired heating system
- one cooling bell for intense charge cooling after annealing
These bell furnaces are normally supplied with signed protective hatches that offer not only increased convection surfaces, but also much longer service life in demanding operation in cycles.
For quick subcooling of the charge, the cooling bell, the structure of the protective cover and the furnace bases are designed and built for water-cooling of the protective cover by a water shower.