On 2018-08-08 14:48:54
Notes before and after use of trolley annealing furnace
The notes before and after using the trolley annealing furnace are introduced in detail
The invention and development of the trolley annealing furnace play an important role in human progress. In the Shang Dynasty, there appeared a relatively perfect copper smelting furnace with an inner temperature of 1200℃ and an inner diameter of 0.8 meters. During the Spring and Autumn period and the Warring States Period, people further mastered the advanced furnace temperature technology on the basis of copper smelting furnace, thus producing the heat treatment equipment of cast iron.
In 1794, the world appeared for the smelting of iron cylindrical cuplaster. Later, in 1864, Martin, a Frenchman, made use of the regenerative furnace principle of Siemens, a British company, to create the world's first open-hearth furnace heated by natural gas fuel. He USES a regenerator to preheat the air and gas at high temperatures, ensuring that the temperature of the steel is above 1,600 degrees Celsius. Around 1900, electric energy supply gradually sufficient, began to use a variety of resistance furnace, arc furnace, hollow induction furnace.
In the 1950s, the coreless induction furnace developed rapidly. Later came the electron beam furnace, which used electron beams to impact solid fuel to enhance surface heating and high melting point materials. The first furnace used for casting heating was the hand forge. Its working space is a trough filled with coal. The burning air is supplied by the lower part of the tank and the work is buried in the coal to be heated. This type of furnace has low thermal efficiency, poor heating quality, can only be small heat workpiece, later developed into a semi-closed or completely closed box furnace and firebrick, can use coal, oil or natural gas as fuel, but also can use electricity as a heat source, the workpiece in the furnace heating.
In order to facilitate the heating of large workpiece, a trolley type heating furnace and a well type heating furnace suitable for the heating of ingot and billet are presented. Since the 1920s, a variety of mechanized and dynamic furnace types have appeared, which can improve furnace productivity and working conditions.
With the development of resource development and fuel conversion technologies, wagon annealing fuels are also used to gradually convert coal, coke, coal and other solid fuels to produce natural gas, urban gas, natural gas and other gases and liquid fuels such as diesel and fuel oil, and to develop and adapt to the use of various fire-fighting equipment.
The structure, heating process, temperature control and atmosphere of trolley annealing furnace will directly affect the quality of processed products. In the casting furnace, increasing the heating temperature of metal can reduce the deformation resistance, but too high temperature will cause grain growth, oxidation or overburning, seriously affecting the quality of the workpiece.
During heat treatment, if the steel is heated to a point above the critical temperature and then cooled suddenly, the hardness and strength of the steel can be improved. When the heating temperature is lower than the critical temperature, the hardness of steel can be reduced and its toughness can be improved.
In order to obtain accurate scale and smooth appearance of the workpiece, or in order to reduce metal oxidation to protect the mold, reduce the machining allowance and other purposes, you can choose a variety of low-oxidation non-oxygen heating furnace. In open-flame low-oxidation furnace, incomplete combustion of fuel is used to produce recovery gas, and the oxidation loss rate can be reduced to less than 0.3% by heating workpiece.
Controllable atmosphere furnace is artificially prepared atmosphere, through the furnace can be gas carburizing, carbonitride, bright quenching, normalizing, annealing and other heat treatment: change the metallographic structure, improve the mechanical properties of the workpiece. In an active pellet furnace, combustion gases of fuel or other fluidized agents are applied outside the furnace, forcing the flow of graphite particles or other inert particles through the hearth. The workpiece can be buried in the particle layer to complete the intensified heating or carburizing, nitriding and other non-oxidation heating.
Molten salt is used as heating medium in salt bath furnace to prevent oxidation and decarburization of workpiece. Cupola smelting of cast iron is usually affected by coke quality, air supply mode, charging conditions and air temperature, which makes it difficult to stabilize the smelting process and obtain high quality molten iron.
The hot air cupola can effectively increase the temperature of molten iron, reduce the loss of alloy and reduce the oxidation rate of molten iron.
With the appearance of coreless induction furnace, cupola tends to be replaced gradually. This induction furnace smelting operation is not limited by any cast iron grade, it can be quickly from one grade of cast iron to another grade of cast iron smelting, is conducive to improve the quality of molten iron.
Special alloy steels, such as ultra-low carbon stainless steels and those used in rollers and turbine rotors, require vacuum degassing and argon mixing in a refining furnace to further refine high-quality steel of high purity and capacity.