Gas leakage detection method of the hottest ion ni

Air leakage detection method of ion nitriding furnace

ion nitriding furnace belongs to the category of low vacuum equipment. Generally, after a period of use, the equipment will have air leakage. In the case of slight air leakage, the air leakage generally will not have a great impact on the nitriding quality of the workpiece. Finally (except for the stainless steel series), but if the air leakage of the equipment is serious, the air leakage will affect the nitriding quality of the workpiece and must be overhauled

leakage detection of vacuum equipment is relatively difficult, and the method of "section by section" inspection is usually adopted, that is, section by section inspection

step 1: first, separate the furnace body and the gas supply system from the research and development of rare earth technology, in order to distinguish whether the leakage is caused by the furnace body or the gas supply system

separate the intake pipe from the bell jar, and then seal the intake joint (you can use the special plug or vacuum sealing mud provided by me). Start the vacuum pump to vacuum, close the butterfly valve after pumping to a higher vacuum degree (such as about 30Pa or higher), and observe the air leakage of the equipment after a pause for a period of time (minutes)

step 2: after the completion of the first step, if the furnace body leaks, check each sealing part that may cause gas leakage one by one (including the observation window, the charging device, the sealing flange surface at the lower part of the bell jar, the large sealing ring on the chassis, the sealing part of the pressure measuring part, the sealing part of the cathode part, the connecting flange surface between the butterfly valve and the extraction pipe, etc.) until the furnace body is basically free of gas leakage

note: when implementing the following inspection steps, the principle of "subsection" inspection method should be followed, that is, one step at a time. After each inspection step is completed, vacuum and observe the inspection effect. If the air leakage problem is solved, no other inspection will be carried out. Otherwise, check in sequence (the inspection steps can be carried out in disorder.)

1. Check whether the glass mirror of the observation window is broken. If it is broken, replace it

2. Check whether the socket head cap screw fastening the glass mirror on the observation window is loose. If it is loose, it should be tightened, but it must be tightened symmetrically and evenly, and the force must not be too large to avoid crushing the glass

3. Check whether the inner and outer sealing rings (white) of the observation window are aging. If they are aging, replace them with new ones

4. Remove the automatic inflation device on the base of the furnace body, remove the ash on the sealing rubber and inflation sealing surface with a clean cloth stained with gasoline, and reinstall it as it is

5. Check the sealing condition of the pressure measuring part on the furnace chassis, tighten the screw, and clearly express the abstract concept in a simple, intuitive and visual way. If the nut is loose, tighten it, and if the sealing ring is damaged, replace it

6. Check the sealing condition of the cathode, tighten the fastening nut if it is loose, and replace it if the sealing ring is damaged

7. Check the sealing flange surface at the bottom of the bell cover of the furnace body. If there is rust, pits and other damage, it should be handled in time. (Note: after lifting the bell cover each time, it should be placed on the rubber plate, wooden square or other soft supports to prevent damage to the sealing flange surface.)

8. Check the large sealing ring on the furnace chassis, and repair or replace it in time if it is damaged. (Note: after lifting the bell jar every time and before putting it on again, first remove the ash on the chassis and the large sealing ring with a clean brush, and then wipe the ash on the sealing flange surface and the large sealing ring with a clean cloth stained with gasoline, said Wang Liping, deputy general manager of Tongling jingsai Electronics Co., Ltd., in order to prevent the ash from embedding into the large sealing ring and causing air leakage.)

9. Check the fastening of each connecting flange face of the air extraction hard elbow. If it is loose, tighten it evenly. If the sealing ring is damaged, it should be replaced in time

10. Check whether there is ash on the sealing ring in the butterfly valve. If there is ash, the butterfly valve pipe may not die and leak. If such situation is found, clean it up with a clean cloth stained with gasoline in time, and then apply vacuum grease. Note: when cleaning the sealing ring of the butterfly valve, do not immerse the sealing ring in gasoline, otherwise the sealing ring will swell and the butterfly valve will not be able to be opened and closed

step 3: after completing the work of step 1, if the furnace body does not leak, it indicates that all sealing parts of the furnace body are in good condition. Then slowly open the butterfly valve. At this time, the following two situations may occur

1. The vacuum degree decreases slightly at the moment of opening the butterfly valve, but does not continue to decline thereafter (that is, the pressure rise rate is within the specified range of the equipment or the pressure rise rate is within the allowable range of the process), indicating that the stainless steel air extraction hose, solenoid valve and their connecting parts are in good condition

2. If the vacuum degree continues to decline after opening the butterfly valve, it indicates that the electromagnetic vacuum belt inflation valve, the exhaust stainless steel corrugated hose or the connecting sealing parts at both ends of the hose may leak. In this case, the leakage can be detected according to the following procedures

(1) first check the sealing parts at both ends of the bellows. If the sealing flange is loose, it should be tightened evenly. If the sealing ring is damaged, it should be replaced in time

(2) then check whether the sealing ring in the solenoid valve is adhered with ash, if so, it may cause air leakage. If this situation is found, clean the ash with a clean cloth stained with gasoline

(3) finally check the corrugated hose. The inspection can be carried out by sealing and pressurization (the pressure is 0.1MPa). After pressurization, the pipe body is immersed in water in sections, and the air leakage part is observed. (avoid bellows elongation when pressurizing)

Step 4: after completing the first three steps, the problem of gas leakage in the furnace body has been solved or it is confirmed that the gas leakage is not caused by the furnace body, reconnect the air inlet pipe separated from the furnace body in the first step to the furnace bell cover (and ensure that the joint is well sealed), turn off all flow meters first, and then start the vacuum pump to vacuum the furnace body. The purpose of this step is to check the air leakage of the air supply system

if the equipment is found to have air leakage again, check the sealing of the air inlet joint, the air pipe, and the connections of various air source flow confluence tees until the air leakage problem is eliminated

(1) check the sealing of the intake pipe and the intake connector and the outlet connector of the flowmeter. If there is suspected of air leakage, the connector can be sealed with vacuum sealing mud

(2) check whether the flowmeter can be closed. The method is to block the inlet end of the flowmeter and compare the leakage difference between blocking and closing the flowmeter only. If the flowmeter cannot be closed, it needs to be repaired or replaced

(3) check whether the ammonia delivery hose has air leakage. If aging and air leakage are found, it should be replaced

generally, the problem of gas leakage in the furnace body can be solved after the inspection of the above steps. (end)