Vacuum equipment is widely used in aviation, food, biotechnology, medical industry, manufacturing, metallurgy, petrochemical, construction and other fields. Magnetron sputtering ion plating technology refers to the vaporization and ionization of the material to be plated in the vacuum chamber. Under the action of bias, particles accelerate and bombard the surface of the workpiece, and finally form a continuous film on the surface of the workpiece. The whole coating process is carried out in vacuum environment. Therefore, it is very important to obtain a stable and high vacuum system for the coating process. The vacuum obtaining equipment is mainly composed of vacuum pump, various valves, pipes and vacuum measuring instruments. Generally, the vacuum system requires less parts, which is convenient for installation, disassembly and operation; the unit is compact in structure and occupies as little space as possible; the working performance is stable and reliable.
Vacuum pump can be regarded as a kind of gas transportation device. It draws the gas out of the container and reduces the pressure in the container. It is an important part of the vacuum obtaining equipment. The limit vacuum range of vacuum pump is very large, from coarse vacuum to 10-12pa high vacuum, and the pumping speed is from 0.0l/s to hundreds of thousands of liters / s. Each kind of vacuum pump has a pumping speed range, and the vacuum pump that meets the requirements is often selected according to different working requirements. Sometimes all kinds of vacuum pumps are combined to meet the needs of different vacuum processes. The selection of vacuum pump can not only be based on one index, but also should be considered from many aspects. There are two main bases for selecting the vacuum pump type:
(1) The limit vacuum required for no-load vacuum chamber. When selecting a vacuum pump, it is necessary to ensure that the limit vacuum degree of the vacuum chamber is lower than that of the selected vacuum pump.
(2) Working pressure of vacuum chamber. The pumping range of vacuum pump is an important technical index to select the type of vacuum pump. Therefore, it is necessary to ensure that the working pressure is within the pumping range of the selected vacuum pump. According to the limit vacuum, the vacuum acquisition equipment can be divided into high vacuum acquisition equipment and low medium vacuum acquisition equipment.
The pumping range of the low and medium vacuum equipment is about 10 to the fifth power of 10 to the first power of PA, which is characterized by low pumping rate, large exhaust volume and high working pressure. Low vacuum equipment is mainly used in vacuum drying, vacuum impregnation, vacuum conveying and vacuum filtration.
Frequently used vacuum pumps include roots vacuum pump, water ring vacuum pump, oil seal mechanical pump, reciprocating vacuum pump, air jet pump, water vapor jet pump, molecular sieve adsorption pump, etc. Most of these pumps can be used alone, but some pumps can not be directly vented to the atmosphere, and need to be equipped with pre-stage pumps, such as roots vacuum pump and oil steam jet pump.
Roots vacuum pump evolved from roots blower and is generally used under low pressure. It is widely used in oil, cutting tools, chemical industry, metallurgy, medical treatment, food and other industries. As early as 1954, roots vacuum pump was invented abroad. China’s roots vacuum pump has a history of more than 30 years. However, compared with the foreign roots vacuum pump, the roots vacuum pump produced in China generally has the problems of high noise, poor reliability and high failure rate, and its comprehensive performance is not good. Because roots vacuum pump can not directly exhaust the atmosphere, it is usually used in series with the former vacuum pump to form a vacuum unit in the vacuum field. For example, roots pump rotary vane vacuum pump unit, roots vacuum pump water ring vacuum pump unit, roots vacuum pump slide valve vacuum pump unit, etc.
The rotary vane vacuum pump is a kind of positive displacement vacuum pump, which realizes the vacuum pumping by changing the volume of the cavity through the rotation of the sliding vane and the stator in the rotor slot. In vacuum technology, rotary vane vacuum pump is one of the basic vacuum acquisition equipment. The rotary vane vacuum pump is often used as the front pump of other vacuum pumps, but the rotary vane vacuum pump can also be used alone in the low vacuum environment with low vacuum requirement. Because of its low price, simple structure and small space, rotary vane vacuum pump is widely used in petroleum, machinery and metallurgy.