Vacuum Heat Treatment Furnace Features
Characteristics of vacuum heat treatment furnace
(1) strict vacuum sealing: as we all know, metal parts for vacuum heat treatment are carried out in the closed vacuum furnace, therefore, to obtain and maintain the original leakage rate of the furnace, to ensure the working vacuum of the vacuum furnace, to ensure the quality of parts vacuum heat treatment has a very important significance. So one of the key issues of vacuum heat treatment furnace is to have a reliable vacuum sealing structure. In order to ensure the vacuum performance of the vacuum furnace, a basic principle must be followed in the design of the vacuum heat treatment furnace structure, that is, the furnace body should be gas-tight welded, and at the same time, there should be as few or no holes as possible in the furnace body, and the dynamic sealing structure should be used sparingly or avoided in order to minimize the chance of vacuum leakage. The parts and accessories installed on the vacuum furnace body, such as water-cooled electrodes, thermocouple export devices must also be designed to seal the structure.
(2) Most of the heating and insulation materials can only be used under vacuum: the heating and insulation lining of the vacuum heat treatment furnace is working under vacuum and high temperature, so the requirements for these materials are high temperature resistance, low vapor pressure, good radiation effect, small thermal conductivity, etc. The requirements for oxidation resistance performance are not high. Therefore, the vacuum heat treatment furnace widely used tantalum, tungsten, molybdenum and graphite for heating and heat insulation structure material. These materials in the atmospheric state is very easy to oxidation, therefore, the conventional heat treatment furnace is not to use these heating and insulation materials.
(3) water-cooled devices, vacuum heat treatment furnace shell, furnace cover, electric heating elements, respectively, disposal (water-cooled electrodes), intermediate vacuum insulation door and other components, are in the vacuum, the heat state work. Working under such extremely unfavorable conditions, it is necessary to ensure that the structure of each part is not deformed or damaged, and the vacuum seal is not overheated or burned. Therefore, each component should be set up with water cooling device according to different situations to ensure that the vacuum heat treatment furnace can operate normally and have sufficient service life.
(4) Use low voltage and high current: In the vacuum vessel, when the vacuum vacancy is within the range of a few torr a lxlo-1 torr, the energized conductor in the vacuum vessel will produce glow discharge phenomenon under the higher voltage. In the vacuum heat treatment furnace, serious arc discharge will be generated, burning electric heating elements, thermal insulation, etc., causing major accidents and losses. Therefore, the working voltage of the electric heating element of the vacuum heat treatment furnace is generally not more than 80-100 volts. At the same time in the structure of the electric heating element design to take effective measures, such as trying to avoid the tip of the components, electrodes between the spacing can not be too small narrow, in order to prevent the glow discharge or arc discharge occurs.
(5) High degree of automation: The reason for the high degree of automation of the vacuum heat treatment furnace is that the heating and cooling of the metal workpiece requires a dozen or even dozens of actions to complete. These actions are carried out inside the vacuum heat treatment furnace and are not accessible to the operator. At the same time, some actions such as heating and holding after the end of the metal workpiece for quenching process requires six actions and to be completed in less than 15 seconds. In such rapid conditions to complete many actions, it is very easy to cause operator tension and constitute a misoperation. Therefore, only a high degree of automation can accurately and timely coordinate the movement according to the program.