Gear pump built-in structure and working principle

The structure of the gear pump is very simple, that is, its most basic form is that two gears of the same size mesh with each other and rotate in a tightly matched housing. The inside of this housing is similar to an "8" shape, with two gears installed inside. , The outer diameter and both sides of the gear are closely matched with the housing. The material from the extruder enters the middle of the two gears at the suction port and fills this space. It moves along the housing with the rotation of the teeth and is finally discharged when the two teeth are engaged.

In terminology, a gear pump is also called a positive displacement device, that is, like a piston in a cylinder, when one tooth enters the fluid space of another tooth, the liquid is mechanically squeezed out. Because the liquid is incompressible, the liquid and the teeth cannot occupy the same space at the same time, so that the liquid is excluded. Due to the continuous meshing of the teeth, this phenomenon occurs continuously, and thus provides a continuous discharge amount at the outlet of the pump. The discharge amount is the same for each revolution of the pump. As the drive shaft rotates without interruption, the pump discharges fluid without interruption. The flow rate of the pump is directly related to the speed of the pump. In fact, there is very little fluid loss in the pump, which makes the pump's operating efficiency cannot reach 100%, because these fluids are used to lubricate both sides of the bearings and gears, and the pump body can never be fitted without clearance, so The fluid cannot be discharged 100% from the outlet, so a small amount of fluid loss is inevitable. However, the pump can still run well. For most of the extruded materials, it can still achieve 93% to 98% efficiency. For fluids whose viscosity or density changes in the process, this pump will not be affected too much. If there is a damper, such as a screen or a restrictor placed on the side of the discharge port, the pump will push the fluid through them. If this damper changes during operation, that is, if the filter is dirty, clogged, or the back pressure of the restrictor increases, the pump will still maintain a constant flow rate until the mechanical limit of the weakest component in the device is reached (Usually equipped with a torque limiter).

The speed of a pump is actually limited, which mainly depends on the process fluid. If the oil is transferred, the pump can rotate at a very high speed, but when the fluid is a high viscosity polymer melt When the system is in use, this limitation will be greatly reduced. It is very important to push the highly viscous fluid into the two-tooth space on the side of the suction port. If this space is not filled, the pump cannot discharge the accurate flow rate, so the PV value (pressure × flow rate) is another limiting factor Is a process variable. Due to these limitations, gear pump manufacturers will provide a range of products, namely different specifications and displacement (the amount discharged per revolution). These pumps will be matched with specific application processes to optimize system capacity and price.

The gear and shaft of the PEP-II pump are integrated, and the whole body hardening process is adopted to obtain a longer working life. The "D" type bearing incorporates a forced lubrication mechanism that allows the polymer to pass through the bearing surface and return to the inlet side of the pump to ensure effective lubrication of the rotating shaft. This feature reduces the possibility of polymer retention and degradation. The precision-machined pump body allows the "D" bearing to precisely match the gear shaft to ensure that the gear shaft is not eccentric to prevent gear wear. The Parkool seal structure and PTFE lip seal together form a water-cooled seal. This kind of seal does not actually contact the surface of the shaft. Its sealing principle is to cool the polymer to a semi-molten state to form a self-sealing. Rheoseal seals can also be used, which are processed with reverse spiral grooves on the inner surface of the shaft seal to allow the polymer to be back pressed back to the inlet. To facilitate installation, the manufacturer has designed a ring bolt mounting surface to match the flange installation of other equipment, which makes the manufacture of cylindrical flanges easier. The PEP-II gear pump has heating elements that match the specifications of the pump, which can be selected by the user, which can ensure rapid heating and heat control. Unlike the heating method in the pump body, the damage to these components is limited to a single board and has nothing to do with the entire pump.

The gear pump is driven by an independent motor, which can effectively block upstream pressure pulsations and flow fluctuations. The pressure pulsation at the outlet of the gear pump can be controlled within 1%. The use of a gear pump on the extrusion production line can increase the flow output speed, reduce the shearing and residence time of materials in the extruder, reduce the extrusion temperature and pressure pulsation to improve productivity and product quality.

Others Clean Room

Iso Class 8,Diy Iso Clean Room,Clean Room Hepa Filters,Clean Room Classification

Dongguan V1 Environmental Technology Co., Ltd. ,