There are three kinds of shaft end seals commonly used in Roots blower: gland type, frame type and mechanical seal. What are the characteristics of these sealing methods?
1、 Gland type
This is a simple and commonly used sealing form, most of which are used for conveying air. There are four gland seals in the connecting part with the cylinder, and several circles of asbestos oil disk root are installed in the gland packing box. In order to reduce the axial length, the seal shall be close to the bearing during the design. During operation. The bolts around the gland can be tightened regularly to keep the air from leaking.
2、 Skeleton type
The framework type seal is generally a framework rubber oil seal. Each group of seals is composed of two or three J-type framework rubber oil seals, two of which are installed back-to-back on the inner side in contact with the transmission medium, the other is installed on the outer side, and grease can be injected in the middle. The whole sealing part is installed in a sealing jacket to form an assembly. The modified structure has good sealing effect and can be used in high speed blower.
3、 Mechanical seal
For the blower conveying special medium (such as the conveying medium is inflammable, explosive, highly corrosive, poisonous and harmful), mechanical seal shall be adopted for the shaft end seal structure. Mechanical seal has the characteristics of reliable sealing performance, small leakage, long service life, small power loss, no need for regular maintenance, and can meet the requirements of production automation, high temperature, low temperature, high pressure, high vacuum, high speed and various flammable, explosive and corrosive media.
Mechanical seal refers to the device that two sealing elements fit each other on the flat and smooth surface perpendicular to the axis and make relative rotation to form a seal. It is usually composed of static ring, dynamic ring, spring loading device and other elements. The anti rotation pin is fixed on the gland to prevent the static ring from rotating.
The common non-metallic materials are pure graphite, impregnated graphite, polytetrafluoroethylene, filled polytetrafluoroethylene, phenolic plastic, ceramics and spraying ceramics. The common metal materials are cast iron, carbon steel, bronze, chromium steel, chromium nickel steel and hard alloy. All kinds of materials have certain characteristics. When choosing the friction pair materials, we should choose them reasonably according to the specific working conditions to ensure the working quality and service life of the friction pair.
Mechanical seal is rarely used in the general sealing of fan products because of its high machining accuracy and assembly accuracy requirements and high process cost. Only a small number of harmful and toxic media can be used.