The bearing of Metering melt pump usually adopts sliding bearing, and the spiral channel is specially designed on the non-bearing surface of the inner wall of the bearing. The rotation direction of the spiral groove is the same as that of the gear shaft. The outer end of the bearing is communicated with the liquid inlet of the Metering melt pump, and the spiral groove of the inner end of the bearing is communicated with the root of the gear teeth (the vacuum part). When the shaft rotates, the low-temperature liquid outside the bearing is sucked into the bearing by means of the screw action and the pressure difference between the two ends of the bearing. After lubricating and cooling the bearing, it flows into the teeth which have just been separated and meshed to form a spiral self-priming low-pressure lubrication system with sufficient lubrication and fast heat dissipation.
The advantage of this lubrication method is that all the lubricants entering the bearing are low temperature medium, and viscous lubricants are easy to form dynamic pressure oil film with strong load-bearing capacity. A large number of lubricants circulate continuously to take away the heat of the bearing, which has a good lubrication and cooling effect on the bearing. Because there is enough liquid to fill the root of gear teeth which are just separated from meshing, the self-priming performance of gear pump is greatly improved, and the phenomenon of suction is avoided. It can not only improve the volumetric efficiency, but also help to reduce cavitation erosion and noise. Sichuan Institute of Mechanical Research and Design adopted the technology of soaking sliding bearings in medium and forced lubrication through special channels. The technology has been successfully applied to gear pumps in the fields of vinylon, polyester, rubber, resin and fertilizer.