Development history of vacuum furnace
Release date： 2014-04-19 00:00 source： http://www.emilyhammann.com Click：
The creation and development of vacuum furnace plays a very important role in human progress. In the Shang Dynasty, a relatively perfect copper smelting furnace appeared in China, and the furnace temperature reached
1200 ℃, the inner diameter of the furnace is 0.8m. In the spring and Autumn period and the Warring States period, people further mastered the technology of increasing furnace temperature on the basis of copper melting furnace
And produced cast iron.
In 1794, a cupola with a straight barrel for melting cast iron appeared in the world. By 1864, the French Martin used the savings of the British Siemens
Based on the principle of hot furnace, the first steel-making open hearth furnace heated by gas fuel was built. He uses the regenerator to preheat the air and gas at high temperature
The temperature above 1600 ℃ required for steelmaking is ensured. Around 1900, the power supply was gradually sufficient, and various resistance furnaces and electric arcs were used
Furnace and cored induction furnace.
In 1950s, coreless induction furnace developed rapidly. Then there was the electron beam furnace, which used the electron beam to impact the solid fuel
It can strengthen the surface heating and melting of materials with high melting point. The earliest furnace for forging heating was hand forging furnace, whose working space was a concave groove
, the tank is filled with coal, the air for combustion is supplied from the lower part of the tank, and the workpiece is buried in the coal for heating. The heat efficiency of this furnace is very low, heating
The quality is not good, and it can only heat small workpieces. Later, it will be developed into a semi closed or fully closed chamber furnace built of refractory bricks
Coal, gas or oil can be used as fuel and electricity can also be used as heat source. The workpiece is placed in the furnace for heating.
For the convenience of heating large workpieces, a trolley type furnace suitable for heating ingots and large billets has appeared, and a well has also appeared for heating long bars
Furnace. After 1920s, there appeared various mechanized and automatic furnace types that could improve productivity and labor conditions. Industry
With the development of fuel resources and the progress of fuel conversion technology, the fuel of the boiler has been gradually changed from solid fuel such as lump coal, coke and pulverized coal
Gas and liquid fuels such as producer gas, city gas, natural gas, diesel oil, fuel oil, etc. are used, and they are suitable for the fuel used
All kinds of combustion devices.
The structure of vacuum furnace, heating technology, temperature control and atmosphere in the furnace will directly affect the product quality after processing. Heating in forging
In the furnace, increasing the heating temperature of metal can reduce the deformation resistance, but too high temperature will cause grain growth, oxidation or overburning, which will seriously affect
Workpiece quality. In the process of heat treatment, if the steel is heated to a point above the critical temperature and then cooled suddenly, the hardness of the steel can be improved
If it is heated to a point below the critical temperature and cooled slowly, the hardness of the steel will be reduced and the toughness will be increased.
In order to obtain the workpiece with accurate size and smooth surface, or to reduce metal oxidation to protect the mold, reduce machining allowance, etc
Can use all kinds of less non oxidation heating furnace. Reducing gas is produced by incomplete combustion of fuel in open flame non oxidation heating furnace
When the workpiece is heated, the oxidation loss rate can be reduced to less than 0.3%.
The controlled vacuum furnace uses the atmosphere prepared manually, which can be gas carburized, carbonitriding, bright quenching, normalizing and annealing
Equal heat treatment: to change the metallographic structure and improve the mechanical properties of the workpiece. In a flowing particle furnace, the combustion gas of the fuel is used,
Or other fluidizing agent applied externally, forcibly flows through the graphite particles or other inert particles layer on the hearth, and the workpiece buried in the particle layer can achieve strong
Chemical heating can also be used for carburizing, nitriding and other non oxidation heating. In the salt bath furnace, the molten salt liquid is used as the heating medium to prevent working
Oxidation and decarburization of parts.
The melting of cast iron in cupola is often affected by the quality of coke, the way of air supply, the condition of charge and the temperature of air
It is difficult to obtain high quality molten iron. The hot blast cupola can effectively raise the temperature of molten iron, reduce the burning loss of alloy and reduce the oxidation of molten iron
Therefore, high grade cast iron can be produced.
With the appearance of coreless induction furnace, cupola will be replaced gradually. The smelting work of this induction furnace is not subject to any cast iron grade
The limitation is that the quality of molten iron can be improved from smelting one grade of cast iron to smelting another grade of cast iron. some
Special alloy steel, such as ultra-low carbon stainless steel, as well as steel for rolls and turbine rotors, needs to be melted from open hearth furnace or general electric arc furnace
In the refining furnace, impurities are removed by vacuum degassing and argon agitation to further refine high-purity and large capacity high-quality molten steel.
The flame furnace has a wide range of fuel sources and low price. It is convenient to adopt different structures according to local conditions, which is conducive to reducing production costs, but it is difficult to use the flame furnace
In order to achieve accurate control, the environmental pollution is serious and the thermal efficiency is low. The characteristics of electric furnace are uniform furnace temperature, easy to realize automatic control and high heating quality
Good quantity. According to the way of energy conversion, electric furnace can be divided into resistance furnace, induction furnace and electric arc furnace. Furnace calculated in unit time unit furnace bottom area
Heating capacity is called furnace productivity. The faster the furnace temperature rises and the larger the furnace load, the higher the furnace productivity. In general,
The higher the furnace productivity, the lower the unit heat consumption per kilogram of material heated. Therefore, in order to reduce the energy consumption, we should produce at full load
Increase the productivity of furnace as much as possible, and implement fuel for combustion device at the same time
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