The working principle of gear pump

The working principle of gear pump is very simple, that is its most basic form is two identical gear in a closely intermeshing rotary shell, the shell is similar to the figure "8", the two gear is installed on the inside, outside and two sides of the gear housing in tight fit. From an extruder material in a suction port into the two intermediate gear, and fill this space, with the teeth rotate along the casing movement, finally in two teeth from. In terms of speaking, the gear pump is also called positive displacement device, that is like a cylinder piston, when a tooth into another tooth fluid space, fluid is mechanical to squeeze out. Because the fluid is incompressible, so the liquid and the tooth cannot at the same time to occupy the same space, so that, the liquid has been ruled out. Because of the constant mesh gear, this phenomenon occurs on a row, and also in the outlet of the pump provides a continuous excluded volume, a turn each pump, the volume of discharge is the same. Along with the continuous rotation of the driveshaft, pump fluid is continuously discharged. Pump flow directly to the speed of the pump. In fact, the pump has a small amount of fluid loss, which makes the operation of the pump efficiency can reach 100%, because the fluid is used to lubricate the bearing and gear on both sides, and the pump body may not gapless fit, so it can not make the body 100% is discharged from the outlet, so a small amount of fluid loss is inevitable. However, a good pump can be run, out of material for the majority, still can reach 93% ~ 98% efficiency. For the viscosity or density change in the process of fluid, the pump will not be affected too much. If there is a damper, for example in the export side, a filter and a limiter, the pump will push fluid through them. If the damper in the job changes, i.e. if the filter is dirty, blocked, or limiter pressure increased, the pump will continue to maintain a constant flow device, until it reaches the weakest parts mechanical limit ( usually with a torque limiter ). For a pump speed, there is a virtual limit, which depends mainly on the process fluid, if the transmission is oil, pump can rotate at high speed, but when the fluid is a high viscosity of the polymer melt, such restrictions will be greatly reduced. Promote blood flow into the intake side of the two tooth space is very important, if not fill in this space is full, the pump will not be able to discharge the flow of accurate, so the value of PV ( pressure x velocity ) is a limiting factor, but also a process variable. Because of these limitations, the gear pump manufacturers will provide a series of products, different specifications and displacement ( one week per revolution of the discharged amount ). These pumps will fit the specific application of technology, to enable the system to achieve optimal capacity and price. PEPII pump shaft gear and a total of one, the surface hardening process, will be a longer working life. " D " type bearing a combination of forced lubrication mechanism, so that the polymer surface by the bearing, and returns to the inlet of the pump side, in order to ensure the effective lubrication of the rotation axis. This characteristic reduces the polymer retention and degradation of possibility. Precision machining of the pump body can cause the " D " - type gear shaft with precision bearings, ensure non-eccentric gear shaft, to prevent gear wear. Parkool sealing structure and PTFE lip type sealing together constitute the water seal. This shaft seal does not actually contact surface, it is the principle of the sealing polymer to a semi-molten state cooling and forming a seal. Also can use Rheoseal seal, seal it inside the table are reverse spiral groove processing, the polymer can be imported back to back pressure. For ease of installation, manufacturers to design a ring bolt mounting surface, so that the flange mounted with other equipment matching, which makes the cylinder flange manufacturing easier. PEPII gear pump with pump size matched to the heating element, for the user to choose, which can ensure the quick heating and heat control. With the pump body heat in different ways, the damage to these components is limited to a board, and the pump. Gear pump is driven by an independent motor, can effectively block the upstream pressure pulsation and flow fluctuations. In the gear pump outlet pressure pulsation can be controlled within 1%. In the extrusion production line adopts a gear pump, can increase the output flow rate of material in the extruder, reduce the shear and residence time, reduce the extrusion temperature and pressure pulsation in order to improve productivity and product quality.