High-temperature vacuum atmosphere furnaces generally have more leakage failures in spring and autumn. Long-term idle are more prone to leakage failures when they are used for the first time.
Vacuum leak detection must be performed at this time. Vacuum leak detection generally adopts a monthly pressure rise rate (at normal temperature, close all vacuum valves, stop the operation of the vacuum system, read a number after 10 minutes, and then read a number after 1 hour, two The difference between the numbers is the value of the pressure rise rate), to grasp the change trend of equipment leakage, such as vacuum equipment continuously shut down for a week, to be run empty (for oven).
Precautions for using high temperature vacuum atmosphere furnace
1. The workpiece truck must be washed and dried before entering the furnace to prevent moisture and dirt from entering the furnace.
2. When the transmission parts find stuck position, inaccurate limit position, control failure and other phenomena, they should be eliminated immediately, and do not operate forcefully, so as not to damage the machine parts.
3. The high-temperature vacuum atmosphere furnace cannot be overloaded. The maximum operating temperature of the high-temperature vacuum atmosphere furnace refers to the surface temperature of the element itself allowed in the vacuum, not the temperature of the heating substance or the temperature around the heating element.
It should be noted that the temperature of the vacuum electric heating element itself is 100 ° C higher than the temperature of the medium or the temperature around it.
4. When measuring the temperature uniformity of the high temperature vacuum atmosphere, attention should be paid to the positioning and binding method of the temperature measuring contact and the distance from the heating element.
In the high-temperature vacuum atmosphere furnace, often (at least every day or before each shift) use a brush, broom, compressed air, vacuum cleaner, etc. to clean the furnace chamber. It is necessary to prevent impurities such as oxide scale in the furnace from falling on the heating elements, short circuit, or even burn out molybdenum Heater.
Heat-resistant steel components such as bottom plates, molybdenum heating rods, and furnace insulation layers should be cleaned every time they are used. Knocking is strictly prohibited, and their scales can be removed carefully.
If the impurities such as iron oxide scale are not removed in time, the melting place and the insulation layer will catch fire and melt the molybdenum wire.
5. To avoid the reaction between the heating element and the product, especially the copper, aluminum, zinc, tin, lead, etc. contact with the vacuum heating element, whether it is fine powder, melt or steam, etc., to prevent the formation of "hemp" on the surface of the electric heating body. "Pit", the cross-section becomes smaller, and finally overheated and burned out.
6. After the high-temperature vacuum atmosphere furnace is heated up, the vacuum system must not be suddenly damaged, nor should the high-temperature vacuum atmosphere furnace door be opened.
Note that before filling the atmosphere, the vacuum gauge switch should be turned off to prevent the vacuum gauge from aging.
When the temperature is higher than 400 ℃, no rapid cooling is allowed. For the vacuum heating element, it is easy to cause oxidation in the case of high temperature, bad vacuum and large changes in heat and cold.
For the molybdenum heating furnace, it should be cooled to below 200 ℃ during normal use and maintenance to stop the protection of nitrogen. Only under 80 ℃ can the furnace door be opened.
7. The cooling system is an important part of the high-temperature vacuum atmosphere furnace. The cooling water channel should be kept clear, otherwise the water temperature will rise and cause shutdown.
This is a problem that is often overlooked when working in high-temperature vacuum atmosphere furnaces.The biological decomposition chemical auxiliary method is used to treat the cooling water, the purpose is to keep the minerals in a suspended state and reduce the accumulation of sediments in the rubber tube, the serpentine tube and the water jacket to make the water flow smoothly.
This is generally done with an automatic device, which can monitor the conductivity of the water, automatically replenish chemical agents, flush the waterway, and add fresh water. In conjunction with the attached vapor filtration system, this method can also ensure the pH control of the water and prevent the deposition of excess minerals in the cooling water system. After the system is stable, a water quality test should be conducted at least once a month to prevent over-treatment or over-treatment.
The test samples of the high temperature vacuum atmosphere furnace shell and heat exchanger materials should also be placed in the waterway system, and a weight loss test should be done once a year to check the effect of the treatment. Special attention must be paid to the serpentine cooler of the diffusion pump.
It should be checked frequently. If clogged, the diffusion pump will overheat and lose its function, and it will further cause the diffusion pump heater to burn out, causing expensive and time-consuming repairs. When the serpentine cooling water pipe is blocked, disconnect the water channel from the water source, drain the water and blow it through with compressed air or rinse with dilute acetic acid solution.
8. The cooling system is an important part of the high-temperature vacuum atmosphere furnace. The cooling water channel should be kept clear, otherwise the water temperature will rise and cause shutdown. This is a problem that is often overlooked when working in .
The biological decomposition chemical auxiliary method is used to treat the cooling water, the purpose is to keep the minerals in a suspended state and reduce the accumulation of sediments in the rubber tube, the serpentine tube and the water jacket to make the water flow smoothly. This is generally done with an automatic device, which can monitor the conductivity of the water, automatically replenish chemical agents, flush the waterway, and add fresh water.
In conjunction with the attached vapor filtration system, this method can also ensure the pH control of the water and prevent the deposition of excess minerals in the cooling water system. After the system is stable, a water quality test should be conducted at least once a month to prevent over-treatment or over-treatment.
The test samples of the high temperature vacuum atmosphere furnace shell and heat exchanger materials should also be placed in the waterway system, and a weight loss test should be done once a year to check the effect of the treatment. Special attention must be paid to the serpentine cooler of the diffusion pump. It should be checked frequently.
If clogged, the diffusion pump will overheat and lose its function, and it will further cause the diffusion pump heater to burn out, causing expensive and time-consuming repairs. When the serpentine cooling water pipe is blocked, disconnect the water channel from the water source, drain the water and blow it through with compressed air or rinse with dilute acetic acid solution.
