Roots Vacuum Pump Sealing Device
No matter what type of vacuum pump, the sealing performance is the most important in its design and manufacture, Roots vacuum pump is no exception. The sealing device of the pump mainly considers the following parts: one is the sealing of the outer part of the transmission shaft head through the pump cover, that is, the inner part of the shaft protection sleeve; the other is the static seal between the gear box cover and the end cover and the pump body; the other is the outer part of the transmission shaft head. The extension part passes through the dynamic seal at the pump cover, which is the seal on the outer surface of the shaft protective sleeve that we often see.
There are many kinds of sealing devices, such as mechanical seal, asbestos disk root seal, leather bowl seal and anti-screw seal. The extension part of the shaft head of the transmission shaft uses the above sealing methods to perform a sealing function. Mechanical seals have many configurations. Double-end friction ring mechanical seals are widely used. The mechanical seals have reliable operation, low power consumption, high allowable linear speed, but complex structure and high manufacturing cost. The sealing structure of asbestos disk root seal is very simple, low cost and easy to replace, but it needs cooling and lubrication. Otherwise, the high temperature generated by friction heating will cause shaft burnout. In order to avoid damaging the shaft, the shaft protective sleeve should be installed at this place. In order to reduce friction, the surface hardness and smoothness of the axle protective sleeve are required to be very high. The surface of the axle protective sleeve is often quenched or carburized and then polished. This kind of sealing with reinforcing ring consumes a little more power, but it is simple in structure and easy to replace. Generally, spare parts are often attached when it is out of the factory. The square bowl is lubricated with vacuum pump oil or dry oil. The leather bowl is made of butadiene-eye rubber. Its linear speed is allowed to be below 12 rn/s, the temperature is below 120 C. When using fluorine rubber, the linear speed can be up to 30 rn/s and the temperature can be up to 250 C. The drive shaft of Roots pump with reverse spiral seal structure can also be used to fling the reverse spiral seal through the seal at the pump cover. Reverse spiral seal is to use the sleeve with thread on the outer diameter to rotate along the shaft, which acts as a seal like a screw pump.
The lubrication of Roots vacuum pump mainly has three parts: oil cup is commonly used for lubrication of shaft seal, gear and bearing are guaranteed by splashing oil with gear or oil disc, and pressure oil slippage of oil pump is used for some large pumps.
Static Sealing of Pump Body End Face: Static Sealing of Pump Body End Face with End Cover and End Cover with Gear Box Cover. One method is to use vacuum oil-resistant rubber ring seal, which is reliable and convenient to disassemble and assemble. But because Roots Pump End Face is not circular, it is very inconvenient to process rubber ring groove. The other is the use of silicone room temperature vulcanized rubber film seals, reliable seals do not need to add rubber grooves, but users must have this material when self-disassembly, and some use of anaerobic rubber or paper pads can still solve the problem.
Sealing of shaft protective sleeve and shaft: Because the shaft protective sleeve rotates with the shaft, there is no relative movement, so it becomes similar to the state of static seal. Generally, one or two annular grooves are cut on the inner wall of the protective sleeve, and the "0" type sealing ring is installed to seal it.
Although different types and models of pumps have certain differences, the actual structure principle is still the same, Roots vacuum pump is no exception. There are also two axes in the pump, namely, the active axle and the driven axle. There are left and right screw seals at both ends of the rotor of the same shaft soil. When the axle rotates, the screw seals also rotate along with the axle. But when designing and assembling, attention should be paid to the left and right rotation of screw seals. Rolling bearings are installed on the end caps of Roots vacuum pumps. When rolling bearings rotate, sufficient oil is needed to ensure lubrication so as to make the pumps run continuously for a long time. Structurally, the pump chamber is close to the bearing, but oil is not allowed to enter the pump chamber.
This special structure puts forward special requirements, although the bearing is close to the pump chamber, there is enough oil, practice has proved that only the reverse helical seal used in this special occasion can achieve remarkable results.
After repeated use, it can be concluded that several characteristics of reverse helical seal: the first is to ensure that the bearings are fully lubricated, Roots vacuum pump, in the work, when the shaft rotates, the screw seal works like a screw, the oil is continuously sent to the bearings to ensure the lubrication of bearings. Secondly, it can reduce power consumption, especially in high-speed operation, which can reduce its heating and improve service life, because when the screw seal rotates with the shaft at the same time, there is a certain radial clearance between the screw seal and the stationary parts, and there is no friction loss. Of course, it also has a high-quality performance, pumps after high-speed operation, the speed is increasing, sealing performance is constantly improving, which makes full use of the nature of its sealing effect.