The non-uniformity of the instantaneous flow of the melt gear pump will produce flow pulsation, if the output flow of the melt pump is directly fed into the actuator, the speed of the actuator will be invariable; if the outlet of the melt pump is connected in parallel with the flow-feeding valve, for example, the melt pump is applied in the throttling speed-regulating circuit composed of the flow-feeding valve, the throttling valve and the hydraulic cylinder. When the pulsating flow passes through the nozzle valve, pressure fluctuation or misoperation of the pressure relay will occur. Another reason is that the pressure fluctuation of melt may also cause vibration and noise of hydraulic system; in severe cases, if the fluctuation frequency is the same as the natural frequency of hydraulic system, it will cause resonance of hydraulic system, which is harmful to the use of transmission shaft and bearing of melt pump, as well as the use of pipe joints and seals. Impact. All these will destroy the performance of the hydraulic system and shorten the service life of the hydraulic components in the system, thus affecting the operation of the hydraulic system.
The relationship between flow pulsation and teeth number of external meshing melt pump is as follows: as a whole, with the increase of teeth number, flow pulsation decreases, especially when the number of teeth of driving wheel and driven wheel is the same; when the number of teeth of main and driven wheel is different, flow pulsation decreases with the increase of teeth number.
