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The working principle of gear pump

Author : Xiong Date : 8/18/2012 5:02:21 AM

The working principle of gear pump
The structure of the gear pump is very simple, that is, it is the most basic form of two dimensions of the same gear in a tight fit the shell body of a mesh with each other in the rotation, the shell of internal similar "8" glyph, two gear installed inside, outside diameter of gear on both sides and the shell and tight fit. From extruder material in the inlet into the two gear intermediate, and full of this one space, with the rotation of the tooth along the shell movement, finally in two tooth out.

In terms of speaking, gear pump is also called positive displacement device, that is like a cylinder in the cylinder piston, when a tooth into another tooth fluid space, liquid was mechanical way discharged. Because the liquid is incompressible, so the liquid and tooth can't occupy the same space at the same time, such, liquid was ruled out. Due to the tooth continuous mesh, this phenomenon is continuous in to occur, thus in pump export provides a continuous exclude quantity, pump every one revolution, the amount of discharge is the same. With the drive shaft uninterruptedly rotation, the pump will unremittingly discharge fluid. Pump flow directly with the pump speed about. In fact, in pump has a small amount of fluid loss, the pump efficiency can reach 100%, because these fluid is used to lubrication bearing and gear two side, and pump body is impossible without clearance fit, therefore, cannot make fluid from the 100% export discharge, so a small amount of fluid loss is inevitable. However pump can still operating well, for most extrusion material, it can still reach 93% ~ 98% efficiency. For viscosity and density in the process have change of fluid, the pump will not be too much influence. If there is a damper, such as in the outlet side put a screen or a limiter, the pump will promote fluid through them. If this damper in the work changes, i.e. if screen dirty, blocked, or limiter back pressure increased, the pump will still maintain a constant flow, until it reaches the most weak parts in the device of the mechanical limit (usually equipped with a torque limiter).
For a pump speed, is actually limited, it mainly depends on process fluid, if transfer is oils, pump, can at a high speed rotation, but when the fluid is a kind of high viscosity of the polymer melt, the restrictions will be greatly reduced. Promote viscous fluid into the suction side of the two tooth space is very important, if this one space not fill, the pump can discharge accurate flow, so PV value (pressure × velocity) is also a limiting factor, and is a process variable. Because these limits, pump manufacturers will provide a series of products, that is, different specifications and delivery (every turn a week discharge quantity). The pump will and specific application process with phase, in order to make the system capacity and price to achieve optimal.

Pump by an independent motor drive, can effectively block in the upper reaches of the pressure pulsation and flow fluctuation. In the pump at the exit of pressure pulsation can be controlled within 1%. In the extrusion line is a gear pump, can improve the flow output speed, reduce material in the extruder in shear and resident time, reduce the extrusion temperature and pressure pulsation to enhance productivity and product quality.
PEP - II pump gear and shaft for a total is a perfect hardening process, we can obtain a longer working life. "D" type bearing combined with forced lubrication mechanism, make polymer the bearing surface, and back to the pump inlet side, in order to ensure the effective lubrication axis. The characteristics of polymer retention and reduce the possibility of degradation. Precision processing of pump body can make the "D" type bearing and gear shaft precise fit, ensure gear shaft don't eccentric, in case gear wear. Parkool seal structure and ptfe lip type seal constitute water seal. This seal actually does not contact shaft surface, its sealing principle is to polymer cooling to half a molten state and form since the seal. Also can use Rheoseal seal, it in the shaft seal inside list processing have reverse screw groove, can make the polymer was back pressure back to import. For ease of installation, manufacturers design a ring bolt mounting surface, in order to make and other equipment installation of flange suitably, this makes barrel flange manufacturing more easily. PEP - II gear pump with and pump specification matching heating element for user selection, this can guarantee fast heating and heat control. And the pump body heating mode is different, the element damage to a board, and the whole pump has nothing to do.

Above : pressure switch main performance