Pre -hot furnaces
Preheating furnaces for rolling and oxidation of steel ingots, which are called (Preheating furnace for rolling and oxidation of ingot), are used to heat the ingots before the rolling process and bring the temperature of the ingots to the hot working temperature. Preheat furnaces One of the main factors of ingot rolling is that these furnaces are used to heat the ingots before rolling with a certain temperature and bring the ingots to the working temperature.
The temperature used for preheated furnaces depends on various factors, which include: ingot dimensions, rolling conditions, steel type, number of rolling steps, final rolling temperature, etc. The standard temperature of preheated furnaces for steel ingots is usually between 1100 and 1250 degrees Celsius, which is necessary to roll the ingot at this temperature so that the temperature distribution in all points of the ingot, from the center to the side surfaces, is completely uniform and the same. In order to do this well, isothermal ovens are usually used.
The amount of heat required to heat the ingots depends on its initial temperature. In order to save energy in preheated furnaces, ingots should be sent into preheated furnaces in the shortest possible time. The ability to implement this planning depends on the technical factors and executive factors of the factory.
Pre -hot furnace
There are different types of preheat ovens, but they are usually designed and built with rectangular, square and circular physical shapes. The reason for this structure of preheated furnaces is that the ingots are entered from one side of the preheated furnace and after heating and reaching the desired temperature, they are taken out from the other side of the furnace by means of a suitable mover (throwing skewer or ingot exit pusher from the furnace). In the design of the furnace floor, care is taken to ensure that the ingot does not interact with the preheated furnace floor due to heat, and on the other hand, waste materials and oxides separated from the surface of the ingot can be removed from the furnace. The atmosphere of the preheated furnace should be controlled in such a way that the corrosion and oxidation of the ingot reaches its minimum level and does not change the chemical composition of the steel.
In the process of preheated ovens, it is necessary to pay special attention to several points so that this process is done correctly. The first point is that the temperature of the ingot should reach the standard temperature mentioned in the previous paragraph in the shortest time. The second point is to avoid keeping ingots in preheated furnaces for a long time, because this action causes waste of energy and causes excessive corrosion of ingots and burning of steel. Therefore, the storage time of the ingots in the furnace must be carefully controlled and the work of ingot feeding and unloading must be done in coordination with the hot rolling rack.
The benefits of pre -hot furnaces
Quick and easy to use
Possibility of local heating
Less surface oxidation
Uniform heating of parts in the mass production process
Low temperature difference between the surface and the center of the part
High heating speed
Ability to automate with other production line machines
Reducing pollution and increasing the safety of the work environment
Factors Affecting the oxidation of steel ingot in pre -hot furnace
In the process of oxidation of steel ingots in preheated furnaces, there are factors that influence the rolling process in the absence of any of these factors.
A lot
Depending on the type of furnace, the type of refractory used, the type of fuel consumed, the dimensions of the furnace, etc., it can play an important role in reducing or increasing the corrosion of steel.
Oxidized shells in pre -hot furnaces
In the hot rolling process, when the ingots are subjected to preheat treatment, the surface of the ingots reacts with the surrounding gases and an oxide shell is formed on its surface. Considering that the effect of these shells is determined directly on the final product and the wear of the rollers, it is very important to identify the related factors. Oxide shells directly affect the final product. Among the characteristics of oxide shells related to hot rolling include the composition of oxide shells, the thickness of oxide shells, and most importantly, the adhesion of the formed shells. Examining and evaluating the aforementioned factors through factors such as sheet surface temperature and rolling time are important factors in the hot rolling process.
