How Melt Blown Cloth Melt Pumps Could Get You on The Today Show

The melt pump (or gear pump) is known as an accurate metering device that eliminates surging of the extruder screw, reduces back pressure and increases output of the complete line (up to 20%). It is used in a wide range of applications from PET sheet and rubber extrusion to recycling and compounding.  The Cnina company Batte melt pump is a leading manufacturer of gear pumps for extrusion with more than 12 years of experience. In the melt blown cloth production line, the melt pump (melt metering pump) plays an indispensable role. The function of the melt blown cloth melt pump in the melt blown cloth production line is to accurately measure, control the output and fiber fineness, and deliver the melt to the spinneret continuously and evenly. The working principle of melt blown cloth melt pump is as follows:

Principle 1: volumetric conveying-metering, steady flow

Zhengzhou Batte melt blown cloth melt pump has excellent metering function. In the gear meshing area near the outlet of the pump (discharge area), the teeth and tooth grooves of the two gears continuously enter a closed or meshed state. The space in the discharge area is continuously reduced, and the melt in each tooth groove is forced Squeeze out. A well-made gear has a very fine profile. When the gear and the housing are closely matched, the amount of material in each tooth is very accurate; the displacement of the melt blown cloth melt pump gear is stable. In this way, it is carried out repeatedly to realize the continuous discharge and metering of the melt.

Principle 2: Supercharging and pressure isolation-supercharging

When the melt blown cloth melt pump is working, when the material at the outlet of the pump is resisted by the forming die, the gear in the melt pump is like a piston in a cylinder, exerting an squeezing effect on the melt in the discharge zone. Realize the pressurization function of the melt pump. At the same time, the gear in the pump is equivalent to a rotating barrier, which can effectively block the influence of pressure fluctuations and flow fluctuations in the feed zone on the discharge zone.

Monitoring of melt blown cloth melt pump

However, the operation of the melt blown cloth melt pump requires a certain degree of monitoring. The important indicators observed include outlet pressure, suction pressure, inlet and outlet pressure difference, motor current, gear shaft seal, and pump body temperature.

Since the flow of the machine head changes with the outlet pressure, the outlet pressure should be constant. Generally speaking, the fluctuation of outlet pressure cannot exceed ±10psi (1psi=0.00689Mpa). Large fluctuations are usually a transmission problem, requiring motor technicians to adjust transmission parameters. If the melt pump is severely worn, it can also cause such problems.

The change in suction pressure reflects the change in the output of the extruder. Although the main function of the melt pump is to eliminate these fluctuations, the range of fluctuations it can control is limited. Even if the melt pump can continuously keep the output of the polymer constant, the melt temperature will also change. Because in order to keep the suction pressure stable, the screw speed will change, which will cause the melt temperature to fluctuate. The fluctuation of the melt temperature will directly cause the melt flow of the die and the change of the product size.

The fluctuation range of the ideal suction pressure cannot exceed ±100psi, preferably ±50psi. If the fluctuation exceeds this value, the flow rate of the nose will change. For this reason, it is necessary to reduce the sensitivity of the extruder motor to pressure fluctuations. This is usually achieved by increasing the proportional control and detection pressure bandwidth to make the extruder motor have this characteristic. If this method cannot control the fluctuations to a small extent, it is likely to be a problem of the extruder itself, which will have to be analyzed separately.

The power required to rotate the gears of the melt blown melt pump should be constant. Even if a current change of several amperes occurs during driving, it also means that there is a problem. This may be a simple parameter setting problem, or it may be a mechanical problem in the pump body, gear box or drive shaft, or the suction pressure fluctuates too much.

Self-lubricating bearings of melt blown cloth metering pump

The bearings of the melt blown cloth metering pump are lubricated by the melt itself, which is realized by the leakage design from the pump outlet end to the suction end and through the entire bearing. The flow of polymer is necessary to protect the bearing. This kind of flow requires that the outlet pressure and inlet pressure of the pump cannot be the same. It is recommended that the pressure difference between the two ports should be kept at a few hundred psi.

Since the bearings of the melt-blown cloth melt pump are lubricated by the melt, a seal is required on the outside of the bearing to prevent the polymer from flowing out of the gear shaft. In order to be able to adapt to different melt viscosity and pump pressure, most pumps are equipped with water-cooled seals. This requires reasonable adjustment of the water volume to ensure that there is enough water to prevent leakage or reduce the leakage to a trace level. However, the amount of water should not be too much, as this will reduce the lubrication effect of the shaft and increase the load on the melt pump motor.

After the melt blown cloth melt pump is started, its temperature should match the melt temperature or melt set temperature. If the pump temperature is much higher than the set temperature or the actual melt temperature, it means that the mechanical part of the pump or the temperature control instrument is malfunctioning. Practice has proved that it is reasonable for the melt pump temperature to be 3-6℃ lower than the melt temperature.

How to choose the right melt pump?

The most important criteria to chose the right melt pump are:
– Throughput (kg/hr)
– Application (sheet, compounding, recycling, etc.)
– Type of polymer (PET, PE, etc.)
– Filler content (kind of filler and percentage)
– Pressure range

Zhengzhou Batte Melt Pump Co., Ltd. is a professional manufacturer of melt pumps, screen changers and feeders integrating R&D and production. Located in the National University Science and Technology Park of the National High-tech Industrial Development Zone of Zhengzhou City, relying on the scientific research strength of domestic first-class universities, combining European advanced technology and quality control concepts, it integrates production, learning and research. Especially in the application technology of melt pump, has accumulated rich experience. Continuous in-depth research on the working principle, performance optimization, equipment structure optimization, control technology and other aspects of the melt pump has achieved considerable results, and has been recognized and praised by most users in the industry.