The lifting and lowering of the furnace cover is completed by a hydraulic lifting mechanism, and its power is provided by a 10/25 hydraulic device. When the furnace cover needs to be raised, as long as the hydraulic device is activated, the furnace cover is slowly raised; if the furnace cover is lowered, as long as the internal thread stop valve in the hydraulic device is loosened, the furnace cover is slowly lowered. At the lifting shaft, there are two limit switches. When the lifting shaft rises, the lower limit switch automatically cuts off the power of the electric fan to avoid danger to the operation. When the furnace cover is raised, the upper limit automatically cuts off the power of the hydraulic device. To prevent accidents when the lifting shaft ejects the cylinder. A water-cooled sample tube, air intake hole and exhaust hole are provided above the furnace cover. If it is combined with the infrared co2 analyzer and modified, the carbon potential can be automatically controlled.
In the furnace, a heat-resistant plate is welded into the furnace tank and the material basket, and the workpiece to be processed is placed in the material basket. In order to make the workpiece to be uniformly contacted with the carburizing gas, a ventilator is installed on the furnace shell to force the air circulation to make the temperature and gas in the furnace uniform. There is a sealing device on the fan shaft sleeve to prevent air leakage, and it is cooled by cooling water. The liquid drip system of this electric furnace is equipped with a dropper that can simultaneously drip three liquids, and the flow rate can be controlled by a flow meter and a needle valve.
RQ well type carburizing furnace process operation: 1. Temperature rise: Before the temperature rise, the ammonia should be vented. The ammonia flow rate is more than twice the normal use flow rate, and the deformation is strictly required. The temperature rise should be stepwise, and the temperature should be kept at 200 ~ 250 & ordm; c, 400 ~ 450 & ordm; c for 1 ~ 2h each. It is also possible to make the heating rate lower than 50 & ordm; c / h. When approaching the holding time, the amount of ammonia should be increased so that the decomposition rate is controlled to the lower limit of process requirements. Exhaust: Generally exhaust while heating up, and evacuate within 150 ~ 200 & ordm; c. During the exhaust process, you can use ph test paper (soak the test paper with water, it turns blue when ammonia gas) or glass rod (glass rod with salt In case of ammonia, there will be white smoke emission) Method to check the seal of the furnace tank and pipeline. During the exhaust phase, ammonia gas is continuously passed in to make the furnace gas pressure reach 200 ~ 400pa. Because ammonia gas is easily soluble in water, the ammonia decomposition rate is measured. The u-tube is usually filled with oil. In the nitriding tank, the air is not clear, and the exhaust pipe cannot be ignited. The ammonia decomposition rate can reach 70% during the heating stage. When the ammonia volume fraction in the furnace gas is greater than 95%, the ammonia flow rate can be reduced and the positive temperature in the furnace can be maintained. Press 3. Insulation: When the temperature reaches the required temperature of the process, adjust the ammonia flow rate to control the ammonia decomposition rate at 18% ~ 35%, and start to calculate the insulation time. At this time, the furnace pressure is 200 ~ 600pa. During the nitriding process, the adjusted ammonia is used. The flow rate method is used to control the ammonia decomposition rate. Generally, the ammonia decomposition rate is measured every 15 ~ 30min. During the heat preservation process, the upper and lower deviations of the furnace temperature should be less than 5 & c.m. When the heat preservation is near the end, the sample should be taken out from the sampling hole. Perform necessary analysis. Denitrification cooling: After the entire nitriding phase is completed, the exhaust valve is closed to reduce the ammonia flow, and the heat is kept for 2 hours, so that the ammonia decomposition rate is greater than 70%, the nitrogen concentration on the surface of the part is reduced, and the surface brittleness is reduced. After that, the power supply was reduced to reduce the temperature, and a small amount of ammonia gas was continuously introduced into the furnace to keep the furnace at a positive pressure. The furnace temperature dropped below 150 & ordm; c to stop the supply of ammonia, and parts should be avoided from collision.
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