Vacuum Heat Treatment and Aluminum Processing (2): Protective Atmosphere Vacuum Heat-treatment Technology

Protective Atmosphere Vacuum Heat-treatment Technology

In the previous article Vacuum Heat Treatment and Aluminum Processing (1), we talked about the defects of traditional vacuum annealing technology. How can we solve the problem? This article will give you the answer.

Protective Atmosphere Vacuum Heat-treatment Technology

Protective atmosphere vacuum annealing is a three-stage vacuum pumping system consisting of a slide valve pump, Roots pump and oil diffusion pump to pump the furnace to a working vacuum of <5×10-2Pa (the ultimate vacuum can reach <5×10-3Pa), and then filled with high-purity inert gas of 99.99% or more (pressure range 0.05~0.07Mpa), and under convection stirring conditions of heating, holding and cooling, and finally out of the furnace.

The characteristics of the protective atmosphere annealing furnace and production process are: the outer shell is a steel shell and ceramic insulation structure. The heating area is a sealed inner steel tank, the heating wires are arranged on the outer wall of the inner steel tank.

The production method is as follows: the outer shell and the inner steel tank between the atmosphere – aluminum products into the inner steel tank, close the inner steel tank door – the inner steel tank vacuum – after the completion of vacuum the inner steel tank is filled with protective atmosphere – heating band heats the inner steel tank, which in turn heats the protective atmosphere in the inner steel tank – the inner steel tank is equipped with convection stirring fan, which stirs the heated protective atmosphere strongly, so that the aluminum products at various points in the furnace are evenly After heating – reaches the process material temperature requirements – strong blowing cold air through the furnace shell between the inner steel tank to cool the inner steel tank, and then cool the protective atmosphere, and then cool the aluminum products, and then out of the furnace.

Protective atmosphere vacuum heat-treatment main technical parameters

The main equipment of protective atmosphere vacuum annealing furnace includes vacuum system, external heating tank, internal steel tank, forced cooling system, workpiece conveying system, water cooling system, compressed air system, protective gas partial pressure control system, electrical control system.

The system process control adopts PLC automatic control. The power supply of the heater adopts silicon controlled regulator, and the temperature control meter adopts an imported temperature control instrument.

The paperless recorder is responsible for recording the vacuum degree and temperature of the working process and controlling the over-temperature alarm. The vacuum valve is equipped with power-off protection and a safety interlock. The water system is equipped with a pressure controller. There is an indicator light simulation display of the equipment running process on the electrical control cabinet. Automatic control of partial pressure process, etc.


The heating process is filled with a protective atmosphere and convection fan strong convection stirring heating method, that is, to avoid the impact of oxidation on the internal and external quality of the product. At the same time, the heating efficiency and effect of improving can make the furnace temperature uniformity to ≤ 4 ℃, product quality consistency greatly improved. Filled with protective gas annealing method, also makes the traditional vacuum annealing caused by loose layer, string layer, and other problems have been greatly improved, production efficiency has been greatly enhanced.


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