The creation and development of industrial furnaces play a very important role in human progress. A relatively complete copper smelting kiln appeared in the Shang Dynasty in China. The temperature of the kiln reached 1200 ° C and the inner diameter of the kiln reached 0.8 meters. During the Spring and Autumn Period and the Warring States Period, people further mastered the technology of increasing the temperature of the kiln on the basis of copper melting furnaces, thereby producing cast iron.
In 1794, a straight cupola furnace for smelting cast iron appeared in the world. Later in 1864, the Frenchman Martin used the British Siemens regenerative kiln principle to build the first steel-making open-hearth furnace heated with gaseous fuel. He uses a thermal storage chamber to preheat air and gas at high temperatures, thereby ensuring a temperature above 1600 ° C required for steelmaking. Around 1900, the power supply gradually became sufficient, and various resistance kilns, arc kilns, and core induction kilns were used.
In the 1950s, coreless induction kilns developed rapidly. Electron beam kilns later appeared, using electron beams to impinge on solid fuels, which could strengthen surface heating and melt high-melting materials.
The first kiln used for forging and heating was a hand forging kiln. Its working space is a concave groove filled with coal. The combustion air is supplied from the lower part of the groove and the workpiece is buried in the coal and heated. This kind of kiln has low thermal efficiency and poor heating quality, and can only heat small workpieces. Later it was developed into a semi-closed or fully closed kiln chamber made of refractory bricks. Coal and gas can be used. Or oil can be used as fuel, and electricity can also be used as heat source. The workpiece is heated in the furnace.
In order to facilitate the heating of large workpieces, trolley-type furnaces suitable for heating steel ingots and large billets have appeared, and well-type furnaces have also appeared for heating long rods. After the 1920s, various mechanized and automated kiln types that could increase kiln productivity and improve labor conditions appeared.
With the development of fuel resources and the advancement of fuel conversion technology, industrial kiln fuels have gradually changed from the use of lump coal, coke, pulverized coal and other solid fuels to kiln gas, city gas, natural gas, diesel, fuel oil, etc. Gas and liquid fuels, and various combustion devices have been developed to suit the fuel used.
The structure of industrial kiln, heating process, temperature control and atmosphere in kiln will directly affect the quality of processed products. In the forging heating kiln, increasing the heating temperature of the metal can reduce the deformation resistance, but too high temperature will cause the grains to grow, oxidize or over-burn, which will seriously affect the quality of the workpiece. In the heat treatment process, if the steel is heated to a certain point above the critical temperature and then suddenly cooled, the hardness and strength of the steel can be increased; if it is slowly cooled after heating to a certain point below the critical temperature, the hardness of the steel can be made again Decrease and increase toughness.
In order to obtain workpieces with precise dimensions and smooth surfaces, or to reduce metal oxidation to protect molds and reduce machining allowances, various non-oxidizing heating furnaces can be used. In the open flame, non-oxidation heating furnace, reducing gas is generated by incomplete combustion of the fuel, and heating the workpiece in it can reduce the oxidation loss rate to less than 0.3%.
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In 1794, a straight cupola furnace for smelting cast iron appeared in the world. Later in 1864, the Frenchman Martin used the British Siemens regenerative kiln principle to build the first steel-making open-hearth furnace heated with gaseous fuel. He uses a thermal storage chamber to preheat air and gas at high temperatures, thereby ensuring a temperature above 1600 ° C required for steelmaking. Around 1900, the power supply gradually became sufficient, and various resistance kilns, arc kilns, and core induction kilns were used.
In the 1950s, coreless induction kilns developed rapidly. Electron beam kilns later appeared, using electron beams to impinge on solid fuels, which could strengthen surface heating and melt high-melting materials.
The first kiln used for forging and heating was a hand forging kiln. Its working space is a concave groove filled with coal. The combustion air is supplied from the lower part of the groove and the workpiece is buried in the coal and heated. This kind of kiln has low thermal efficiency and poor heating quality, and can only heat small workpieces. Later it was developed into a semi-closed or fully closed kiln chamber made of refractory bricks. Coal and gas can be used. Or oil can be used as fuel, and electricity can also be used as heat source. The workpiece is heated in the furnace.
In order to facilitate the heating of large workpieces, trolley-type furnaces suitable for heating steel ingots and large billets have appeared, and well-type furnaces have also appeared for heating long rods. After the 1920s, various mechanized and automated kiln types that could increase kiln productivity and improve labor conditions appeared.
With the development of fuel resources and the advancement of fuel conversion technology, industrial kiln fuels have gradually changed from the use of lump coal, coke, pulverized coal and other solid fuels to kiln gas, city gas, natural gas, diesel, fuel oil, etc. Gas and liquid fuels, and various combustion devices have been developed to suit the fuel used.
The structure of industrial kiln, heating process, temperature control and atmosphere in kiln will directly affect the quality of processed products. In the forging heating kiln, increasing the heating temperature of the metal can reduce the deformation resistance, but too high temperature will cause the grains to grow, oxidize or over-burn, which will seriously affect the quality of the workpiece. In the heat treatment process, if the steel is heated to a certain point above the critical temperature and then suddenly cooled, the hardness and strength of the steel can be increased; if it is slowly cooled after heating to a certain point below the critical temperature, the hardness of the steel can be made again Decrease and increase toughness.
In order to obtain workpieces with precise dimensions and smooth surfaces, or to reduce metal oxidation to protect molds and reduce machining allowances, various non-oxidizing heating furnaces can be used. In the open flame, non-oxidation heating furnace, reducing gas is generated by incomplete combustion of the fuel, and heating the workpiece in it can reduce the oxidation loss rate to less than 0.3%.
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