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Vacuum Tempering Furnace Manufacturers and Applications

Application of Vacuum Tempering Furnace

The purpose of adopting vacuum tempering is to keep the advantage of vacuum quenching surface brightness. If conventional equipment (air furnace, etc.) is used for tempering after vacuum quenching, especially high temperature and medium temperature tempering, the surface of the workpiece will be oxidized, If the surface is not bright and other defects, if salt bath tempering, oil bath tempering, etc. are used, the overall color will no longer be bright, and cleaning and other processes need to be added. Therefore, vacuum tempering after vacuum quenching can keep the surface of the workpiece bright. It is an important aspect of process requirements.

The maximum operating temperature of the vacuum tempering furnace is generally 700°C, and the air cooling pressure is 2×10^-5Pa. The vacuum tempering furnace is composed of a furnace body, a heating chamber, a thermal stirring device and an air cooling device. The furnace body and the furnace cover are double-layer water-cooled structures, and the seal between the furnace body and the furnace cover adopts a double-layer sealing structure to ensure that the vacuum furnace is safe and reliable during negative pressure and positive pressure operation. The heating element is a nickel-chromium alloy strip, and the heat shield is a full metal screen or a sandwich structure. When heating, close the front and rear doors of the heating chamber, and start the hot mixing device to ensure uniform heating; when cooling, open the front and rear doors and start the air cooling device, and the heat of the air flow is removed by the radiator. The gas in the vacuum tempering furnace is a non-oxidizing atmosphere, such as argon, nitrogen and nitrogen-hydrogen mixed gas.

Structural characteristics of vacuum tempering equipment

①The furnace shell is composed of a furnace body and a furnace door. The furnace body is a double-layer cylinder with a hollow structure in the middle, and cooling water is passed through the inside. Hinge connection to ensure the sealing of the furnace door. The furnace door is a double-layer carbon steel structure, which is cooled by water.

The heating chamber has a box-shaped structure, and there are wheels at the bottom to move back and forth. When the fan, heat exchanger, heating body parts and temperature measuring thermocouples are removed, the heating chamber can be pulled out of the furnace body, which is convenient for equipment maintenance and adjustment and replacement of parts.

②The feeding mechanism is a guide rail trolley type feeding mechanism, and the transmission mechanism is a screw guide wheel cantilever fork lifting mechanism, which adopts PC

The machine controls the progress of the feeding car and the movement of the station, thus realizing the semi-automatic operation of loading.

③The heating chamber adopts graphite rod heating elements, and 9 graphite rods are evenly distributed in three groups. The furnace temperature is uniform, the temperature rises quickly, the price is cheap, and the service life is long.

④The heating chamber is equipped with a motor fan with adjustable speed in two gears, a wind deflector for changing the direction and flow of gas flow, and a heat exchanger that can be raised and lowered, which is conducive to changing and adjusting the circulating air flow. The inflation pressure is 0.6×10⁵-0.7×10⁵Pa when heating, and 1.2×10⁵Pa when cooling. Powerful circulating cooling realizes rapid heating and cooling of vacuum tempering, shortens the process time, saves energy and material consumption, and avoids the second type of temper brittleness of some steel materials; the orientation of the air deflector can be adjusted to achieve the best airflow guidance and distribution for optimum furnace temperature uniformity. The air-cooling system is arranged in the heat exchanger in the furnace, the impeller of the air guide screen and the centrifugal fan or behind the impeller and the electrode furnace shell, and the fan is directed at the heat exchanger.

⑤The vacuum system is to make the surface color of the parts qualified after vacuum tempering, and the product quality is stable. The vacuum degree reaches 6.6×10^-5Pa, and the working vacuum degree is 1.3×10^-2Pa.

⑥The gas filling system is to eliminate the non-oxidation of the parts during the heating process. When the parts are heated, the high-purity nitrogen (99.999%) below one atmospheric pressure is filled, or the mixed gas of 90%N₂+10%H₂ is filled to make the furnace The inner atmosphere is weakly reducing, to neutralize the remaining oxidative atmosphere in the furnace, the purity of N₂ is 99.999%, and the filled H₂ should be dehumidified and dried to obtain the best effect of tempering brightness above 90%. And should be higher than atmospheric pressure when cooling. In order to prevent some materials from being oxidized during the heating process, generally about 10% of hydrogen with a purity of 99.9% is filled, and an inflation system is equipped. That is, it is composed of a gas storage tank, a manual butterfly valve, a pressure reducing valve, a pneumatic butterfly valve, a solenoid valve and pipelines.

⑦Water cooling system In order to ensure the normal operation of each part of the furnace body, water cooling must be carried out on the furnace door, furnace shell, heat exchanger, electrode handle, vacuum pump, etc. There are separate water towers or tanks.

⑧Furnace temperature uniformity is high, ±3°C, and the heat shield is made of all-metal five-layer stainless steel plate, which is beneficial to improve the brightness of tempering and is conducive to obtaining products with uniform hardness.

⑨The electric control system uses a PC to control the heating system and cooling system of the vacuum furnace. The automatic instrument for temperature control has high reliability. Using computer control, it can realize the automatic control of mechanical actions, process procedures and technical parameters, and realize the automatic operation of the vacuum tempering furnace.