Precautions for daily use vacuum furnace to prevent leaks
Vacuum furnace generally leak more failures during the spring and autumn, when long idle leakage failure prone. I plant to take monthly load rate of rise (at room temperature, turn off all the vacuum valve and stop the vacuum system operation, after reading a few 1Omin, 1h after reading a number of two numbers is the numerical difference between the rate of pressure rise). leakage control device trends, such as the vacuum device continuously shut down for a week, for a dry run once.
(1) the preparation of maintenance procedures, the establishment of operating records and repair records, statistics run cumulative operation time, strengthen maintenance, technical state control equipment trends, early detection of signs of malfunction damage, avoid thermal properties belonging to repair accident repair, and according to furnace load and working conditions, prepared in advance targeted repair materials, preparation of repair processes. The alloy element length of life and many factors working temperature, the furnace medium quality components and operating conditions, etc., and its fluctuation life 6000 ~ 10000h.
Leak in the vacuum system, in addition to blocking the use of vacuum mud paste, but also can be used for medical needle aspiration leak ether shoot at suspected sword, watching the vacuum gauge reading without changes. Can also be produced silicon vacuum left plugged in blind holes, segmented block the vacuum line. Diffusion pump has coke chemical pickling method available cleaning.
(2) brick oven repaired should always check check table after use oven temperature and the furnace temperature is too high, the heating element if overheating blown, temperature unevenness or whitening phenomenon. For three-phase high-temperature furnace, as well as resistance furnace capacity exceeding 100kW, each phase, each heating zone should be equipped with a meter, furnace and instrument instruction found is not normal, timely analysis and processing. Tube furnace
(3) can not overload did not prepare, the maximum temperature of the alloy element refers to the element allowed in the surface temperature of the drying air itself, does not mean the substance of heating temperature or temperature surrounding the heating element. Pay attention to the temperature of an electric heating element itself around it than the medium temperature or high heating temperature 100 ℃.
(4) To avoid heat deletion products, in particular foot copper, aluminum, zinc, tin, lead and electrical contact with the heating element, whether it is a fine powder, molten liquid or steam, electric heating to prevent the formation of surface erosion "pits "smaller cross-section, and finally blown overheating.
(5) The measured temperature uniformity, temperature should be noted that the positioning of the bundle and contacts, as well as the distance from the heating element. Furnace regularly (at least monthly) with a brush, broom or compressed air, vacuum cleaners and other cleaning furnace and put the brick, to prevent the furnace oxide and other impurities off the heating element, short circuit, and even burn put bricks. Floor, crucibles, furnaces and other heat-resistant steel tank member per period of time, it is best to lift percussion, remove its oxide. Iron oxide and other impurities, if not removed, it will melt and react firebrick, the furnace melting wire.
(6) When the stove to heat up, you can not open the door for a long time. When the temperature is higher than 400 ℃, it can not be rapidly cooled. For the heating element at high temperature, large changes in hot and cold conditions, prone to oxidation peel. For molybdenum furnace, EI regular maintenance attention should be cooled to below 200 ℃ before the stop transmission protective gas.
After the furnace were larger area hermitages, to oven. Before the oven, use a shake table testing equipment insulation, usually not less than 2MΩ. Brick oven oven divided into three stages:
① water discharge of O ~ 200 ℃, moisture and mud masonry discharge of moisture, you must open the door, while a longer holding time.
② expansion of masonry is masonry began to swell and swell deformation period, then warming does not exceed 50 ℃ / h.
③ incubation period over 600 ℃, every increase of 100 ~ 200 ℃, for a holding period of time, too fast easily damaged masonry.