Type and Characteristics of Heat Treatment Furnace
Type of heat treatment furnace
The commonly used heat treatment furnaces include salt bath, gas carburizing, well type resistance, and box-type resistance.
Salt bath furnace - The salt bath furnace is a type that utilizations molten salt as a heating medium. The salt bath has the upsides of straightforward structure, advantageous assembling, ease, great heating quality, and quick heating rate, and in this manner is broadly utilized.
However, when heating in a salt bath furnace, there are processes, for example, clamping and binding of parts, poor working conditions, high labor intensity, complicated operation, and shortcomings such as the long heating time at startup.
In this way, a salt bath furnaces is regularly utilized for parts that are medium to little and have high surface quality necessities.
Well resistance furnace - The working rule of the well type resistance furnace is equivalent to that of the box type resistance furnace, and its furnaces mouth is named upwards and is named as a well. Usually utilized are medium temperature wells, low-temperature well furnace, and gas carburizing furnace. The well type of resistance furnace receives crane lifting parts, which can diminish the workforce, so it is broadly used.
The medium temperature well type furnace - Its maximum working temperature is 950 °C mainly applies heat treatment such as normalizing of dry long parts, annealing, and quenching. As compared to the box furnace, the well type furnace has better heat transfer, And the top of the furnace can be equipped with a fan to equalize the temperature distribution. The vertical part of the elongated part can overcome the bending deformation caused by self-weight when the part is placed horizontally.
Box type resistance furnace - It is a widely used heating device in heat treatment workshops. The working principle is to use electric current to generate heat through the electric heating elements arranged in the furnace, and to heat the parts by radiation & current. Suitable for tempering, quenching, normalizing, annealing, and solid carburizing of steel materials and non-ferrous metals. The utility model has the advantages of good working conditions, access to protective gas to prevent oxidation when parts are heated, accurate temperature control, and simple operation.
Characteristics of heat treatment furnace
(1) The temperature scope of the heat treatment furnace is huge. The fundamental design is to acquire austenitic steel with great plasticity, the temperature range is 900 ~ 1200 ° C; heat treatment because of various process necessities, the temperature is high up to 1300 ° C, the low is just around 100 ° C.
The temperature distinction is incredible to such an extent that the furnace structure is additionally altogether different.
The furnace temperature is higher than 650 °C, called high-temperature heat treatment furnace, the warmth move is essentially founded on radiation, enhanced by convection; the heater temperature is lower than 650 °C, called low-temperature heat treatment furnace, the warmth move chiefly relies upon convection.
The heat treatment requires uniform furnace temperature to avoid exorbitant nearby temperature, so the furnace of the heat treatment furnace is now and then isolated from the combustion chamber.
(2) The furnace temperature control of the heat treatment furnace is generally exacting. The warming before the weight handling, the metal temperature vacillates by a couple of degrees, and for the most part, doesn't have a lot of effect on the quality.
Nonetheless, regardless of whether the heat treatment furnace can guarantee the temperature needed for the heat treatment measure affects the item quality, and for the most part, doesn't surpass 3~10 °C.
The temperature appropriation on the segment of the item to be heated should to be as uniform as could be expected under the circumstances, and the temperature contrast must not surpass 5 to 15 °C.
Regarding controlling the temperature of the furnace, the electric furnace is predominant.
So as to accomplish the reason for precisely controlling the temperature, it is desirable to consistently organize the flameless burner and the flat flame burner with little force, so the division control is encouraged, the burner is excessively little, the concentration is excessively concentrated, and nearby overheating is probably going to happen.
Simultaneously, the arrangement of the burner or the electric furnace and the structure of the heater should be helpful to the dissemination of the furnaces gas, so the temperature inside the heater will in general be uniform, and a fan can be utilized in the furnace for this reason.
(3) The heat treatment furnace should be limit the decarburization & oxidation of the metal.
For the heat treatment of steel, decarburization and oxidation of the surface are not permitted, and the surface ought to be kept clean.
Heat treatment furnaces frequently expect fixing to control the composition of the furnace gas, and now and some time to keep up a particular environment inside the furnace.
For instance, the bright annealing of cold-worked steel is generally completed in a defensive gas medium or in a vacuum, so the muffle cover and the radiant tube are utilized in many heat treatment furnaces.
At the point when the workpiece or steel is exposed to substance heat treatment, for example, carburizing, nitriding, cyanidation, and so forth, it must be kept in a specific medium of the dynamic medium, and a stifle heater or a muffle furnaces is required.
(4) The profitability and thermal efficiency of the heat treatment furnace are low. In the heat treatment, so as to make the temperature of the metal cross-area uniform and transform the crystal structure into complete, it is important to leave the metal in the furnaces for quite a while.
Despite the heat treatment, the material has one or a few absorbing heats the furnace or During the warmth safeguarding stage, the cooling cycle is likewise frequently done in the furnace. A few assortments are heat-treated and even warmed, protected, and cooled.
Many heat treatment furnaces are worked intermittently. For the above reasons, the profitability and thermal productivity of the heat treatment furnace are a lot of lower than those of the heating and forging furnace.
