齿轮泵的概念是很简单的,即它的最基本形式就是两个尺寸相同的齿轮在一个紧密配合的壳体内相互啮合旋转,这个壳体的内部类似“8”字形,两个齿轮装在里面,齿轮的外径及两侧与壳体紧密配合。来自于挤出机的物料在吸入口进入两个齿轮中间,并充满这一空间,随着齿的旋转沿壳体运动,最后在两齿啮合时排出。 在术语上讲,齿轮泵也叫正排量装置,即像一个缸筒内的活塞,当一个齿进入另一个齿的流体空间时,液体就被机械性地挤排出来。因为液体是不可压缩的,所以液体和齿就不能在同一时间占据同一空间,这样,液体就被排除了。由于齿的不断啮合,这一现象就连续在发生,因而也就在泵的出口提供了一个连续排除量,泵每转一转,排出的量是一样的。随着驱动轴的不间断地旋转,泵也就不间断地排出流体。泵的流量直接与泵的转速有关。 实际上,在泵内有很少量的流体损失,这使泵的运行效率不能达到100%,因为这些流体被用来润滑轴承及齿轮两侧,而泵体也绝不可能无间隙配合,故不能使流体100%地从出口排出,所以少量的流体损失是必然的。然而泵还是可以良好地运行,对大多数挤出物料来说,仍可以达到93%~98%的效率。 对于粘度或密度在工艺中有变化的流体,这种泵不会受到太多影响。如果有一个阻尼器,比如在排出口侧放一个滤网或一个限制器,泵则会推动流体通过它们。如果这个阻尼器在工作中变化,亦即如果滤网变脏、堵塞了,或限制器的背压升高了,则泵仍将保持恒定的流量,直至达到装置中最弱的部件的机械极限(通常装有一个扭矩限制器)。 对于一台泵的转速,实际上是有限制的,这主要取决于工艺流体,如果传送的是油类,泵则能以很高的速度转动,但当流体是一种高粘度的聚合物熔体时,这种限制就会大幅度降低。 推动高粘流体进入吸入口一侧的两齿空间是非常重要的,如果这一空间没有填充满,则泵就不能排出准确的流量,所以PV值(压力×流速)也是另外一个限制因素,而且是一个工艺变量。由于这些限制,齿轮泵制造商将提供一系列产品,即不同的规格及排量(每转一周所排出的量)。这些泵将与具体的应用工艺相配合,以使系统能力及价格达到最优。 PEP-II泵的齿轮与轴共为一体,采用通体淬硬工艺,可获得更长的工作寿命。“D”型轴承结合了强制润滑机理,使聚合物经轴承表面,并返回到泵的进口侧,以确保旋转轴的有效润滑。这一特性减少了聚合物滞留并降解的可能性。精密加工的泵体可使“D”型轴承与齿轮轴精确配合,确保齿轮轴不偏心,以防齿轮磨损。Parkool密封结构与聚四氟唇型密封共同构成水冷密封。这种密封实际上并不接触轴的表面,它的密封原理是将聚合物冷却到半熔融状态而形成自密封。也可以采用Rheoseal密封,它在轴封内表上加工有反向螺旋槽,可使聚合物被反压回到进口。为便于安装,制造商设计了一个环形螺栓安装面,以使与其它设备的法兰安装相配合,这使得筒形法兰的制造更容易。 PEP-II齿轮泵带有与泵的规格相匹配的加热元件,可供用户选配,这可保证快速加温和热量控制。与泵体内加热方式不同,这些元件的损坏只限于一个板子上,与整个泵无关。 齿轮泵由一个独立的电机驱动,可有效地阻断上游的压力脉动及流量波动。在齿轮泵出口处的压力脉动可以控制在1%以内。在挤出生产线上采用一台齿轮泵,可以提高流量输出速度,减少物料在挤出机内的剪切及驻留时间,降低挤塑温度及压力脉动以提高生产率及产品质量The concept of the gear pump is very simple, it is the most basic form two the same size of gear in a close coordination of casing mutual engagement, the shell of internal similar "8" glyph, two gear, gear inside diameter and bilateral and shell. From the extruder materials in the suction into two gears, and full of a space, with the rotation of the tooth in the shell movement, finally two teeth mesh when eduction.In the term, the gear pump is also called positive displacement device, like a cylinder piston, when a within another gear teeth into the fluid space, liquid was discharged pushing machinery. Because of the liquid is incompressible fluids and tooth, so can occupy the same space at the same time, so that you have been excluded. Because of this phenomenon, constantly mesh is continuous, thereby in pump export provides a continuous, pump out each, the amount of exhaust. With the drive shaft rotation, uninterruptedly pump is uninterrupted eduction fluid. Pump flow directly with the speed of the pump.In fact, there are small amounts of fluid pumps, the loss of the pump efficiency can reach 100%, because these fluid used lubricating bearings and gear pump body side, but also could never non-clearane, cannot make fluid with 100% exported from a fluid, so the loss is inevitable. However pump can still operating well, for most of the extruder, still can achieve materials of efficiency.For viscosity or density in the process of fluid, the change is not much effect on pump. If there is a damper on line, for example, put a screen or export side a limit, pump will promote the fluid through them. If the damper in work change, i.e., if the mesh become dirty, blocked, or limitation of back pressure is increased, the pump will remain constant flow, until it reaches the weakest part of device of mechanical limit (usually contains a torque limiter).For a pump, the speed limit is actually, it mainly depends on technology transfer, if the fluid is oil pump can at high speed rotating, but when the fluid is a kind of high viscosity polymer melt, the restrictions will be greatly reduced.Promote sticky fluid into the suction side of the two tooth space is very important, if the space without fills, the pump can discharge the flow, so precise velocity (PV) is another pressure (a limiting factor, and it is a process variables. Due to the limit, the gear pump manufacturers will provide a series of products of different specifications, and emissions per week turned out (of the). The pump and the concrete application process, in order to make system capacity and achieve optimal price.PEP - II of the gear pump shaft, and the body USES hardening craft, can obtain more long working life. "D" type bearings with the lubrication mechanism of polymer, make the bearing surface, and return to the pump inlet side, in order to ensure the effective axis. This reduces the possibility of degradation of polymer and detained. Precision machining pump body can make "D" type bearings and gear axle, ensure accurate gear axis gear eccentric wear, not to. Parkool seal structure and ptfe lip seal constitute water seal. This fact does not contact the shaft seal surface, it is the sealing principle of polymer cooled to half molten state and forming the seal. Also, it can be used in Rheoseal seal shaft sealing in a table, can make the reverse spiral groove back by the import of polymer. For ease of installation, the manufacturer designs a circular bolts, to install the equipment installation of flange with other match, which makes the cylindrical flange manufacture more easily.PEP - II gear pump and specification of pump matching element, which can ensure the user's choice, fast heating and heat control. The pump body with different heating, these elements damaged, with only a landmark on the pump.By an independent gear pump motor drive, and can effectively block upstream pressure pulsation and flow volatility. In the gear pump outlet pressure pulsation can control in 1%. On the production line adopts a gear pump, can increase the output speed, reduce material flow in the shear and within the extruder, reduce time-resident, extrusion temperature and pressure pulsation in order to improve productivity and quality