What are the reasons for the wear of sliding bearing end face of melt gear pump?

Bearing is one of the core components of melt metering pump. Materials and designs must be carefully selected and coordinated to ensure safe and efficient operation of the metering pump. The melt gear pump starts to run smoothly. After a period of time, the gear pump vibrates. Under the condition that the outlet pressure remains unchanged, the pump speed increases continuously, and the motor current increases accordingly. After a period of time, the motor trips due to current overload. The disc pump is easy without jamming. It was found that the wear of the gear end face and the bearing end face exceeded 1mm.

It can be concluded from the above phenomena that the end face of the gear and the sliding bearing is worn, resulting in the increase of the end face clearance. The leakage flow of the end face clearance is proportional to the third power of the end face clearance value, causing the leakage of the high-pressure melt to the low-pressure suction chamber or the bearing chamber through the clearance at both ends of the gear to increase sharply, resulting in the decrease of the volumetric efficiency of the melt gear pump. End gap leakage is the main internal leakage path of melt gear pump, accounting for 75% - 80% of the total leakage of gear transmission parts.

To transport polymer melts with high viscosity and high pressure, involute helical gears are mostly used in melt gear pumps to increase the coincidence degree of gear meshing, which can continuously and smoothly extrude materials during meshing and reduce pressure fluctuations. However, this type of gear generates axial force during operation. The axial force acting on the driven helical gear shaft is generated by the hydraulic pressure and the meshing force, which are equal in size and opposite in direction, so the axial force acting on the driven shaft is zero. The axial force acting on the driving helical gear shaft also comes from the hydraulic pressure and meshing force, and the direction is the same, so the axial force acting on the driving shaft is the resultant force of hydraulic pressure and meshing force; The size is directly proportional to the pressure difference between the suction and discharge ports. The reason for the wear of gear and sliding bearing end face is the imbalance of axial force. The drive gear is subject to the axial force from the cross shaft universal coupling at the same time. If the universal coupling is damaged, the axial force is greater. The end face wear of all drive gears is consistent with the axial force. info@battemachinery.com