The workspace is a groove. The tank was full of coal. The air for incineration is supplied from the lower part of the storage tank, and the workpiece is buried in the coal for heating. The furnace has low thermal efficiency, poor heating quality and can only heat small workpieces. Later, it was an indoor furnace, a semi enclosed or fully enclosed furnace made of firebrick. It can be used as a fuel for coal, natural gas or oil. It is also possible to use electricity as a heat source and heat the workpiece in the furnace

The emergence and development of annealing furnace plays an important role in human progress. A relatively perfect copper smelting furnace appeared in Shang Dynasty. The furnace temperature reaches 1200 ° C and the inner diameter reaches 0.8m. In the spring and Autumn period and the Warring States period, people further mastered the technology of raising furnace temperature on the basis of copper furnace, so as to produce cast iron.

Precautions before and after the use of trolley type annealing furnace for heat treatment equipment in 1794, the world launched a straight cylindrical cupola with molten cast iron. Later, in 1864, French Martin made a steel-making open hearth furnace heated by gaseous fuel based on the regeneration furnace principle of Siemens. He used an accumulator to preheat air and gas at high temperatures to ensure that the steel-making temperature was higher than 1600 ° C. around 1900, various resistance furnaces, electric arc furnaces and core induction furnaces were gradually used in power supply.

Precautions before and after use of annealing furnace? In 1950s, coreless induction furnace developed rapidly. Later, an electron beam furnace was used, which used an electron beam to impinge on a solid fuel, thereby enhancing the appearance of heating and melting high melting point materials. The furnace used for casting heating is a hand forging furnace.