First of all, let’s take a look at what is the definition of a vacuum furnace. Vacuum furnace refers to the use of a vacuum system to exhaust the gas in the furnace cavity in the specific space of the furnace cavity so that the gas pressure in the furnace cavity is less than a standard atmospheric pressure. A special heating device that realizes the vacuum state in the inner space of the furnace cavity.
Vacuum furnaces can be divided into vacuum quenching furnaces, vacuum brazing furnaces, vacuum annealing furnaces, vacuum magnetic furnaces, vacuum tempering furnaces, vacuum sintering furnaces, vacuum diffusion welding furnaces, vacuum carburizing furnaces, etc. according to their applications.
Most vacuum furnaces are composed of the following seven systems:
The furnace body adopts a double-layer cylindrical structure, and water cooling is passed between the inner and outer walls to keep the inner and outer walls of the furnace at a lower temperature, preventing the heat generated by the heating element from escaping and causing danger. The side of the furnace body is equipped with a vacuum pumping interface, a vacuum charging and discharging valve, etc.
2. Furnace cover
The lid of the horizontal vacuum furnace is opened on the side, and the lid of the vertical vacuum furnace can be opened up or down. The furnace cover also uses a double-layer water-cooling structure, and water cooling is passed between the inner and outer walls.
3. Heating and heat preservation system
A variety of heating elements can be used for heating, such as resistance wire, silicon carbide rod, silicon molybdenum rod, graphite, molybdenum plate and electron beam, laser, induction heating, etc. The heating electrode is specially designed for vacuum sealing to ensure good sealing and insulation with the furnace body. In order to maintain temperature stability, save energy and reduce consumption, a heat preservation furnace is generally set in the vacuum chamber. Heat-resistant heat preservation materials can choose aluminum oxide fiber, high-purity graphite board and graphite fiber, molybdenum board and stainless steel board.
4. Temperature measurement system
According to different temperature ranges, K-type, N-type, S-type, B-type thermocouple or infrared thermometer can be used for temperature measurement.
The vacuum system is used to achieve the vacuum environment in the furnace. According to different vacuum requirements, mechanical pumps, roots pumps, diffusion pumps, molecular pumps, etc. can be used alone or in combination, with vacuum baffle valves, high vacuum butterfly valves, and digital displays. Vacuum gauge, vacuum pressure gauge, vacuum vent valve, vacuum pipeline, etc. form a vacuum system, and there is an air-filling interface. In order to reduce the vibration of the furnace body, a metal bellows is used for the connection between the vacuum pipeline and the pump, and the vacuum degree is displayed by a digital vacuum gauge and a vacuum pressure gauge.
6. Water cooling system
The water cooling system is composed of chillers, water collectors, inlet pipes, return pipes, valves, pipelines, etc. The vacuum unit, furnace body, furnace door, etc. are supplied through pipelines to ensure that the equipment is cooled and insulated in time to ensure safety. For example, the spare circulating water system of the customer's production site can also be directly connected to the circulating water for cooling.
7. Control system
The temperature is controlled by the temperature program controller according to the process curve set by the user to automatically control the temperature, and has the PID self-tuning function. The temperature can also be controlled manually according to the user's needs. The human-computer interaction interface generally adopts LCD touch screen, which can realize the functions of temperature curve setting, temperature display, heating and vacuum system control, alarm display, data recording and so on.