The difference between high temperature oil pump and high viscosity pump
2021/03/13 13:32:14
High temperature oil pump is an essential equipment for polyester melt transportation, pressurization and melt metering. Compared with other types of melt pumps, the high temperature oil pump has a compact structure, reliable operation, low energy consumption, high volumetric efficiency, less shearing effect on the melt, stable flow at high viscosity and high pressure, and no outlet pressure fluctuations. The unique advantages of this pump and its key role in the process flow make it play an irreplaceable role in polyester production.
A complete gear pump includes a motor, a reducer, a coupling and a pump head. The pump head is composed of a pump casing, front and rear side covers, gear shafts, sliding bearings and shaft seals. The high-temperature gear pump is a positive displacement pump, which relies on the change of working volume caused by the meshing of the main and driven gears to transport the melt. The working volume is composed of the pump body, the tooth groove of the gear and the bearing with the function of the side plate.
The bearings of high viscosity pumps usually use sliding bearings, and a spiral flow channel is specially designed on the non-load bearing surface of the inner wall of the bearing. The rotation direction of the spiral groove is the same as the rotation of the gear shaft. The outer end of the bearing communicates with the liquid inlet of the pump, and the spiral groove at the inner end of the bearing communicates with the root of the gear tooth (vacuum part). When the shaft rotates, with the help of the spiral action and the pressure difference between the two ends of the bearing, the low-temperature liquid outside the bearing is sucked into the bearing. After the bearing is lubricated and cooled, it flows into the teeth that have just been disengaged to form a spiral with sufficient lubrication and fast heat dissipation. Self-priming low pressure lubrication system. The advantage of this lubrication method is that all the lubricating liquid entering the bearing is a low-temperature medium, and the viscous lubricating liquid is easy to form a dynamic pressure oil film with strong load-bearing capacity. A large amount of lubricating fluid circulates continuously to take away the heat of the bearing, which plays a good role in lubricating and cooling the bearing. Since there is sufficient liquid to fill the tooth roots that have just been out of mesh, the self-priming performance of the gear pump is greatly improved, and the phenomenon of suction is avoided, which not only improves the volumetric efficiency, but also helps reduce cavitation and reduce noise. Sichuan Machinery Research and Design Institute uses sliding bearings immersed in media and forced lubrication through special channels. This technology has been successfully applied to gear pumps in the fields of vinylon, polyester, rubber, resin, and fertilizer.
The material of the bearing is commonly used tool steel, and the surface is hardened to improve its anti-adhesive ability. If the conveying medium contains abrasive particles, a very hard bearing material, such as ceramic, should be used. In recent years, GS-1 polytetrafluoroethylene steel composite material is considered to be an ideal sliding bearing material. It is composed of three layers of cold-rolled steel sheet (base body), sintered spherical porous bronze powder or copper mesh (middle layer), and PTFE (surface layer). It has the advantages of metal and PTFE plastic. On the basis of this material, Shanghai Institute of Materials has developed a better performance SF type three-layer composite self-lubricating material, which replaces the bronze powder layer with bronze wire mesh, and the plastic formula of the surface layer has been carefully selected. This kind of bearing material has fatigue resistance, high bearing capacity, low friction coefficient and long service life. It is a novel bearing material that improves the technical performance of gear pumps.
