China Turbomolecular Pumps
China Turbomolecular pump is a kind of mechanical vacuum pump which obtains ultra-high vacuum by high-speed rotating rotor pulling gas molecules. The working pressure ranges from 1 Pa to 10-8 Pa, and the pumping rate is generally below 5000L/s. Advanced pumps can obtain the ultimate pressure of 10-9Pa. The speed of the pumps is 10,000 r/min-50,000 r/min. The pumping speed range of the pumps is very wide. The pumping speed of the pumps is constant among nine f-stages. Molecular pumps are mainly used as ultra-high vacuum pumps and high vacuum pumps, but they can not directly exhaust the atmosphere. They need to be equipped with front-stage pumps, and their main performances (such as limit pressure and pumping speed) are related to the capacity, speed of the front-stage pumps and the types of gases pumped. Molecular pumps have a higher pumping speed for lighter gases, and the pumping speed for groups is 20% higher than that for air. In China, the research and production of molecular pumps with fatal wheels are progressing rapidly. On the basis of the horizontal turbomolecular pump developed in the 1960s, two series of vertical turbomolecular pumps with milling and twisting blades were developed rapidly. The pumping speed range is 11OL/s, 150L/s, 45OL/s, 55OL/s, 60OL/s, 120OL/s, 1500L/s and 3500L/s. China has formulated the industry standard of vertical turbomolecular pump (JB/T 9125-95) and the national standard of side test method of turbomolecular pump performance (GB7774-87), and magnetic suspension bearing is used in turbomolecular pump.
Over the past 10 years, due to the continuous development of bearings, high-speed rotation and numerical control processing technology, great progress has been made in the development of turbomolecular pumps in the world. The pumping speed has developed from 50L/s to 25000L/s (Japan) and even to 40000L/s (Russia). Molecular pump is a kind of pump with precise structure and high technology requirement in all kinds of vacuum pumps with mechanical movement. The geometrical shape of the dynamic and static blades of the pump is closely related to the pumping speed, and special process is needed to ensure the size and accuracy of the blades. At the same time, the rotor is required to have good dynamic balance, and the moving blade should have high strength to withstand the centrifugal force produced by high-speed rotation, so as to ensure the reliable operation of the pump.
Molecular pump is driven directly by medium frequency motor inside the pump body, and the turbine rotor is integral structure. The pump has a high compression ratio for high molecular weight gas, and if the medium frequency motor is placed in the front space, it can obtain high vacuum and ultra-high vacuum for cleaning. Its performance features are compact structure, wide working pressure range, stable pumping speed in the range of 10-1Pa-10-7Pa, stable operation, and stable pumping speed in the range of 10-1Pa-10-7Pa. Precision bearing, strict dynamic balancing technology and a series of vibration reduction measures are adopted, so that the pump has low vibration, low noise and short start-up time, and can generally reach full pumping speed within 4-15 minutes. Standardized flange connection size and vertical structure make it easy to connect with the vacuum system.
With the continuous improvement of the structure of turbomolecular pumps, they are used more and more widely. There is a tendency to replace oil diffusion pumps in some applications. It is suitable for use in instruments and equipment requiring clean high vacuum and ultra-high vacuum, such as high-energy accelerator, nuclear fusion reactor, aerospace simulation, vacuum coating, vacuum smelting, semiconductor purification, large-scale electronic tube exhaust, etc.
At present, the magnetic suspension turbomolecular pump has reached the practical level, which makes the turbomolecular pump develop towards the direction of high flow rate and high outlet pressure. In this way, molecular pumps can be used not only in extremely high and ultra-high vacuum range, but also in high and medium vacuum range. Now it has become the main equipment to obtain clean vacuum (such as the emergence of dry molecular pumps), and its application field is expanding.
FB Grease Lubricated (Hybrid) Molecular Pump