Generally speaking, in the hot exchange of trolley furnaces, it is usually divided into three different temperature zones: furnace gas, furnace wall and metal that is melted (or heated). Among them, the temperature of the furnace gas is the highest; the temperature of the furnace wall is second; the temperature of the molten metal is the lowest. Thus, heat exchange is performed between the furnace gas and the furnace wall, between the furnace wall and the metal, and between the furnace gas and the metal by radiation and convection, and heat loss due to heat conduction of the furnace wall.
The molten metal has the following heat transfer methods in obtaining heat in the trolley furnace.
1. Radiation heat transfer from the furnace gas to the metal. After the heat radiated from the furnace gas is transmitted to the surface of the furnace wall and the metal, part of it is absorbed and the other part is reflected back. The reflected heat is passed through the furnace gas in the furnace, a part of which is absorbed by the furnace gas, and the remaining part is radiated to the opposite furnace wall or metal, so that the radiation is repeated.
2, The furnace wall and the top of the furnace to the metal radiation heat transfer, its radiation is somewhat similar to the previous one. The difference is that the inner surface of the furnace wall also absorbs heat in a convective manner, and this heat is still radiated.
3, Convection heat transfer of furnace gas to metal, in the existing trolley furnace furnace, the temperature of the furnace gas is mostly in the range of 600 ~ 1200 °C. When the furnace gas temperature is 600 ° C, the convective heat transfer is reduced, and the radiation heat transfer is sharply increased.
Trolley furnace operation and maintenance procedures
1. Open the trolley door. When opening the furnace door, it should be noted that when the furnace door leaves the end surface of the furnace, the furnace door should be stopped for a while. After the furnace door swings, the furnace door will be raised to the maximum height at full speed.
2, Into the furnace, note that when the trolley type tempering furnace all enter the furnace, the furnace door will fall, at this time can start the control cabinet heating. The maximum size of the placed workpiece should be less than the corresponding effective size of the furnace. Its width and height should be less than the effective size of 300mm, the length can be increased by 200mm, rigorously super wide, super high, overloaded furnace.
3. Heating, the number of processing processes is programmed into the 708P number display table, and several control parameters are set according to the installed capacity, and the over-temperature operation equipment is strictly prohibited.
4. Lift the workpiece off the trolley at the fastest speed and quickly drive the trolley into the furnace, and drop the furnace door to avoid excessive temperature drop in the furnace, and a large amount of cold air intrusion affects the service life of the furnace and reduces the furnace door. And the time when the wires and other components on the door are heated.
