Addtime： 2020-07-16 Browse times： 3173
There are no lack of testing instruments and professional technicians in vacuum equipment manufacturers, and they have rich maintenance experience. Therefore, there should be no problem in the inspection and maintenance of vacuum equipment. As users, unless the technical force is strong, but many users generally do not have or do not fully have the conditions to carry out the maintenance of vacuum equipment.
Q: what are the key points of repairing vacuum equipment?
Answer: the key point of repairing vacuum equipment is to judge the fault. There may be several reasons why the vacuum can not be pumped up. It is necessary to find out the reasons, such as the insufficient pumping capacity of the vacuum unit or the high leakage rate, or both. At this time, we should observe and record patiently to find out the fault. For example, if the evacuation time is the same and the vacuum degree is low, close the high-pressure valve. If the pointer of the vacuum gauge drops quickly, the vacuum chamber leaks in most cases. At this time, the leakage point should be found out first. If the pointer of the vacuum gauge drops slowly, most of the time, the vacuum unit's pumping capacity is not enough. At this time, the focus can be put on finding the vacuum pump and valve to see where there is leakage, or the diffusion pump oil is contaminated and oxidized; or the front stage pipeline seal is not well sealed and the pump oil is insufficient; or the pump oil emulsification, shaft seal oil leakage, valve plate damage and other faults.
Q: what's the biggest headache for users?
A: the most troublesome problem for users is the detection leakage rate. Leakage is divided into internal leakage and external leakage; external leakage is better to detect, while internal leakage is more difficult to handle. The larger leakage point can be used by flame method. According to the principle that air flow can make the flame deviate, vacuum is pumped first, and then the candle or lighter is used to search the suspicious point step by step. If the flame moves towards the leakage point, the leakage point can be found. We can use the self-made leak detector to detect the leakage within the working range of the rotary vane pump. Now we have produced ZHC. 1 type instrument. The instrument uses ZJ. 2 ionization gauge, which is connected to the suction port of rotary vane pump. If the diffusion pump unit, the leakage rate of l0pa level can be detected.
Q: how to check small leakage and micro leakage?
A: small leakage and micro leakage are more difficult to check. The common method is to use the ionization tube sensitive to certain gases in high vacuum state to detect leakage, such as acetone or ethanol. Use a medical syringe to spray acetone or ethanol to suspicious places. When spraying to the leakage point, the pointer of the ionization meter will swing obviously. In this way, we must be patient and wait until the indication value of the ionization meter is stable, that is, the suction capacity and leakage rate of the vacuum unit are balanced before spraying. It is best to repeat several times to confirm the leakage. Zhc-1 instrument can also use the above method to detect leakage. The difference is that ZHC. 1 instrument can detect leakage within the working range of rotary vane pump and is not afraid to be exposed to the atmosphere.
Q: how to check internal leakage and external leakage?
A: the internal leakage mostly occurs on the equipment with water cooling jacket, and no doubt is found in the external leakage. However, there are the following phenomena: the pumping speed of mechanical pump is obviously low, the indication value of vacuum gauge is low, the oil of mechanical pump is quickly emulsified, and the iron-based parts in vacuum chamber are obviously rusted. If the above conditions are met, it can be determined that there is internal leakage. There is a 25kg medium frequency furnace. The 2x-70 rotary vane pump and 150 roots pump can only pump 10 Pa when they are pumped together. The function of 150 roots pump is not obvious, and there is no leakage. However, it has the conditions that the mechanical pump oil emulsifies quickly and the iron base parts in the vacuum chamber are obviously rusted. After the equipment is disassembled and cleaned, it is found that the furnace cover is leaking. The rest is to find the leak. Wet the inner wall, and then clean it to see if there is any leakage.
Q: how to deal with the fault point after it is found out?
Answer: find out the fault point can be dealt with according to local conditions, the simple way is to change parts, small to rubber ring, bolt, large to valve, vacuum pump, as long as there is on hand can be replaced; for the parts need to be welded, it should be carried out according to the requirements, and it is also necessary to confirm that the requirements are met after welding.
Q: what should be paid attention to in maintenance?
Answer: maintenance should pay attention to several links, disassembly, cleaning, inspection, assembly. It is very important that vacuum equipment, regardless of its size, belongs to precision mechanical equipment. Disassembly should follow the principle of handle with care, do not be reckless, must not use a sledge hammer to knock; cleaning parts to be clean, thorough, in order to find problems and hidden dangers; vacuum pump products and general mechanical products have a big difference, general mechanical products are more chamfered, and vacuum pump corner is clear, easy to hurt hands, should be more careful, remember.
Inspection is a meticulous work, every detail should not be left out, let alone fluke psychology. There is an equipment which has been stored for 4 years by the user. After the routine cleaning work has been completed, the pipeline has been connected step by step and the vacuum has been pumped. However, it can not meet the factory standard. Everything has been checked, but a vacuum hose for gas supply has not been checked. At that time, it was considered that the vacuum hose will not leak. On the contrary, the problem lies in this vacuum hose.
What's more, the vacuum pump parts cleaned with gasoline or other solvents must wait until the gasoline or solvent evaporates completely before assembly. If the vacuum pump oil is mixed with other oil or solvent or water, its performance will be damaged and the performance index of vacuum pump will be affected. The rubber ring should be cleaned and checked carefully for defects, such as cracks. If the size is correct, pay special attention to the diameter of similar size, such as 3.1 mm and 3 mm; if the size of 5.7 mm and 6 mm is not correct, the sealing will be affected. The rubber ring with heating position must be replaced every time it is disassembled and cleaned, such as each interface of oil booster pump. When assembling, the pump parts also need to be handled with care; when tightening the screws, the force should be even and should be tightened from the opposite angle. Shaft seal is often used for dynamic seal. Be careful when installing the shaft seal. First check whether the shaft seal itself has defects, whether the sealing surface is flat, and how elastic the shaft seal spring is. A thin layer of vacuum grease can be applied on the inner side of the shaft seal. The force should be even when the shaft seal is put on. If the framework shaft seal is not pressed too far, oil leakage and air leakage will occur; if the shaft seal spring is not squeezed out, the shaft seal will be invalid without the shaft seal spring. Pay attention to the concentricity of the shaft seal and the shaft. Some pumps are connected with the wheel, the coaxiality requirements of the wheel is very strict, assembly to the four sides of the shaft to ensure parallel consistency.
The key to the gear adjustment of roots pump is that the two 8-type gears do not collide. After the inner wall of diffusion pump and jet tower are cleaned, it is better to dry them with electric spinning. Since the temperature of pump oil is controlled by the length of electric furnace wire in domestic production, the injection amount of diffusion pump oil should be increased or decreased according to the actual situation of local power grid. If the oil injection of k.400 pump is 10 mm on the shunt tank, K150 pump can be installed on the diversion tank for 6 Mm, the diameter of the pump is different, the amount of oil injection is different; the voltage of the grid is low, the oil injection can be reduced by 2 mm, as long as the clean steel ruler or wire can be used for measurement. Due to the differences in manufacture and use, the amount of oil injected into the diffusion pump can only be used for reference. Don't rush to repair. If you don't know the fault clearly, you will take it for granted and start to dismantle it. It will add new disease to the old one. Complicated the original simple problem.
Q: how to deal with equipment failure under emergency conditions?
A: routine maintenance can be done step by step. Under emergency conditions, the equipment fails and the production task is urgent. In this case, as long as the fault is judged accurately, all available materials, such as vacuum sealing mud, vacuum sealing wax, 704 silica gel and vacuum cavity plate, can be used. As long as there is no conflict with work in process, the repair can be carried out. There was a new mirror plating machine which was produced by foreign company. After a normal working month, it was shut down for one day. The vacuum chamber door was opened by itself. The user was eager to resume production. He was busy dismantling and inspecting for two days without solving the problem. After our inspection, it was found that there was a defect in the vacuum chamber door. The defect was blocked by vacuum sealing mud, so that the user could resume production as soon as possible. A medium frequency furnace works normally under low vacuum and discharges at 6pa. After inspection, it is found that it is caused by L-Tip discharge. The fundamental solution to the problem is overhaul, which takes one week. According to the user's urgent requirement, 704 silica gel was used to seal the tip of L discharge, and normal production could be achieved the next day. There is a vacuum equipment, the heating seal adopts knife edge flange, the user carelessly makes the oxygen free copper pad appear "double eyelid", resulting in air leakage. The temperature of the sealing part is lower than 100 ℃, and the user needs it urgently. The oxygen free copper pad is welded flat with soldering tin, and then the rosin is cleaned by ethanol. The sealing problem is solved. The emergency principle is to ensure the normal production of the equipment under the condition of not damaging the equipment and not affecting the products in process.
Q: what is the relationship between the host and the accessories?
A: another important problem is that there is an ion nitriding furnace which works for a certain period of time. The equipment does not move and the operation process remains unchanged, which means that the workpiece can not be plasma nitrided. Users and manufacturers can not find out where the problem is, confused. After testing and searching, it is determined that there is something wrong with the matching gas supply pipeline. The user uses the oxygen pipe. The user thinks that the oxygen pipe can withstand positive pressure and negative pressure. In fact, it is not. After the tube was replaced, the problem was solved. We suggest that domestic manufacturers should provide corresponding supporting devices for users while producing the main engine. Sometimes the problem of the matching device will affect the host.
Q: vacuum equipment is widely used. How to deal with complicated problems?
A: now vacuum equipment is more and more widely used, many of which are related to electricity, electromagnetism, water, gas source and refrigeration. Both vacuum furnace and coating equipment will encounter electrical problems. Quite a lot of the time, it's not a problem with the power supply, which is hard to understand. Some of them are caused by carelessness in mechanical assembly, and some are problems in insulating materials or structure. At this time, do not rush to a conclusion, do not rush to dismantle the equipment, should carefully analyze the fault phenomenon or consult the personnel specialized in this work. Avoid unnecessary loss caused by wrong dismantling and unloading. There is a special equipment, the discharge phenomenon occurred during the work. Through the analysis of the work record and the communication with the operator, different conclusions are drawn. Some people think that there is a problem with the power supply, while others think it is a problem in the assembly process. Finally, the equipment was disassembled and the discharge phenomenon was eliminated after reassembly. There is a magnetron sputtering coating machine. The product in the lower half is obviously better than that in the upper half. There is no problem with the surface of the target. Take a Gauss meter and the upper half of the magnetic ring is demagnetized. After inspection, it turned out that there was something wrong with the waterway. By adjusting the water circuit and replacing the magnetic ring, the problem of consistency between the upper and lower parts of the product has been solved.
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