Operation of ion nitriding furnace
Ion nitriding furnace is often used in industrial production. The following is a detailed description of the operation steps of ion nitriding furnace:
1. Clean and dry the workpiece, and install the furnace. The work piece is well coiled and has enough clearance.
2. The furnace body is closed.
3. Power on. Instrument setting to process temperature.
4. Vacuum. Start the mechanical pump first, then slowly open the butterfly valve to maximum.
5. Vacuum to ten PASCAL. You can stop a pump. Adjust the valve to fit position.
6. Combined high pressure. (the voltage potentiometer is at zero) through the cooling water. Resistance gear is arc gear. Arc gear resistance value added larger, through the current small, heating when resistance value is small, through the current large. Arc gear is generally about a quarter of the rated current.
7. Slowly adjust the potentiometer to a certain position and shine in the furnace. Workpiece cleaning and arc-striking work in furnace. Do not make the arc of the furnace fierce.
8. In the initial stage, the voltage is about 300 volts.
9. Adjust the potentiometer according to the situation in the furnace. Do not make the arc of the furnace fierce.
10. With the extension of time, the arc point in the furnace decreases. Then gradually increase the electrical pressure, arc point increase. Repeat the process.
11. Adjust the voltage and make arc at the same time according to the state of furnace. Temperatures are also gradually increasing.
12. When the voltage is gradually increased to about 600 volts, a small amount of ventilation is allowed. After ventilation, the voltage decreases and the current increases. And the arc striking process occurs in the furnace.
13. Repeatedly adjust the voltage and gradually adjust the ventilation quantity. This clearing and striking stage time, generally in a few hours. When striking a sharp arc, the gear is striking an arc gear. When the arc light is small, the current increases and the resistance shift is the heating gear.
Composition of vacuum ion nitriding furnace
1. The furnace body is composed of furnace cover, cylinder body, furnace chassis and bottom frame, in which cooling water is passed through the interlayer of furnace cover, cylinder body and furnace chassis. The furnace body is provided with stainless steel and aluminum alloy double layer heat insulation screen, and the furnace body is provided with double layer tempered glass for observation of the furnace during ion nitrification.
2. There are two sets of cathode transmission devices on the furnace cover, and one set of thermocouple hanging column, which is equipped with hanging tray. The user shall design the lifting device according to the processed parts and hoist the workpiece on the hanging tray through the hanger.
3. The vacuum obtaining system of the furnace body is generally composed of two rotary vacuum pumps and a pipeline system with disc valves. The role of disc valves is to adjust the suction quantity at different angles through closing or rotating to maintain the pressure in the furnace under different air intake conditions.
4. The inlet of the gas supply pipe of the furnace body is located on the furnace shell and barrel, one rotor flowmeter for hydrogen calibration/nitrogen calibration
5. The thermocouple is inserted into the furnace through the hanging column of the thermocouple to carry out simulation measurement. The temperature is recorded by the instrument and the temperature is controlled by P, I and D.
How to control the cooling temperature of nitrification furnace?
In the method of gas nitriding carbon or nitrogen altogether permeability, if use under the aegis of the ammonia with furnace cooling below 200 ℃ hot process. After open the lid of the stove furnace gas deflagration, happen from time to tome, just different levels.
The nitrification furnace tries to explain as follows:
1, the basic furnace gas nitriding furnace for ammonia, nitrogen and hydrogen and the hydrogen and ammonia are combustible gas, mixed with air to a certain scale, in the flame (Mars), or reach the ignition temperature (above 510 ℃) can burn, show the explosion in sealed container, exposure of deflagration in the container.
2, the furnace temperature is under 200 ℃, open the lid of the stove, in spite of air into the, in the absence of flame lit, this should not happen gas combustion (explosion).
3, however, there is a problem, namely strong reducing gas, hydrogen is over it will be scattered in the process of furnace cooling in furnace tank of a particle (dust) status of iron nitrides reduction iron powder. We know little of reduced iron powder in the air will be strong oxidation and heat, the temperature rise sharply as Mars, carbon and nitrogen altogether permeability may deposit in the process of powder activated carbon in the air will become oxide Mars. Mars lighting "hydrogen gas (ammonia) - air mixture, then appear deflagration.
4. Prevention methods:
(1) put some nitrogen into the cover before opening it, dilute it so that the gas can be driven out, and then open the cover;
(2) open the furnace cover carefully, keep the operator away from the furnace body, allow the furnace gas to escape for a while, or throw it into the pot with a lighted paper ball, and ignite the gas that may remain, and then lift out the parts after making sure it is safe.