The structure of the vacuum furnace
An overview of the structure and composition of the vacuum furnace:
First of all, let's look at the definition of a vacuum furnace. A vacuum furnace refers to the use of a vacuum system to discharge the gas in the furnace cavity in a 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 a 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.
Most vacuum furnaces are composed of the following seven systems:
1. Furnace body
The furnace body adopts a double-layer cylindrical structure, and water is passed between the inner and outer walls for cooling, so that the inner and outer walls of the furnace body are kept at a lower temperature, so as to prevent 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 and a vacuum charging and discharging valve.
2. Furnace cover
The lid of the horizontal vacuum furnace can be opened sideways, and the vertical vacuum furnace can be opened by the upper lid or the lower lid. The furnace cover also adopts a double-layer water-cooling structure, and the inner and outer walls are cooled by water.
3. Heating and heat preservation system
A variety of heating elements can be used for heating, such as resistance wire, silicon carbon rod, silicon molybdenum rod, graphite, molybdenum plate and electron beam, laser, induction heating, etc. The heating electrode is specially designed to be vacuum sealed to ensure good sealing and insulation with the furnace body. In order to maintain temperature stability, save energy and reduce consumption, a thermal insulation furnace is generally installed in the vacuum chamber. The heat-resistant thermal insulation materials can be selected from alumina fibers, high-purity graphite plates and graphite fibers, molybdenum plates and heat shields made of stainless steel plates.
4. Temperature measurement system
According to different temperature ranges, K-type, N-type, S-type, B-type thermocouples or infrared thermometers can be used to measure temperature.
5. Vacuum system
The vacuum system is used to realize 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, together with vacuum baffle valve, high vacuum butterfly valve, digital display Vacuum gauge, vacuum pressure gauge, vacuum release 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, the connection between the vacuum pipeline and the pump adopts a metal bellows, and the vacuum degree is displayed by a digital vacuum gauge and a vacuum pressure gauge.
6. Water cooling system
The water cooling system consists of a chiller, a water collector, a water inlet pipe, a return water pipe, a valve, and a pipeline. Supply the vacuum unit, furnace body, furnace door, etc. through pipelines to ensure that the equipment is cooled and insulated in time for safety. For example, the spare circulating water system of the customer's production site can also be directly connected to the circulating water to achieve cooling.
7. Control system
The temperature is controlled by the temperature program controller according to the process curve set by the user, to implement the automatic temperature control, and has the PID self-tuning function, and the temperature can also be manually controlled according to the user's needs. The human-computer interaction interface generally adopts an LCD touch screen, which can realize the functions of temperature curve setting, temperature display, heating and vacuum system control, alarm display, data recording and other functions.