Melt pump and screen changer

The application of melt pumps in PE foam sheet extrusion lines primarily demonstrates their advantages in conveying, pressurizing, and metering high-temperature, high-viscosity polymer melts. Below is a detailed elaboration on the specific roles of melt pumps in this production line:

I. Basic Functions and Characteristics of Melt Pumps

A melt pump in extruder is a positive displacement conveying device, with its flow rate strictly proportional to the pump's rotational speed. It mainly consists of a pump casing, a driving gear, a driven gear, sliding bearings, front and rear end plates, gland seals, etc. The melt is conveyed through the change in working volume caused by the meshing of the driving and driven gears. The melt pump can continuously and stably pump an accurate flow of material to the extruder die, thereby ensuring that the dimensional tolerance of the extruded product is minimized.

II. Application of Melt Pumps in PE Foam Sheet Extrusion Lines

Stable Extrusion and Improved Product Precision:

During the extrusion of PE foam sheets, the melt pump can eliminate feeding errors from the feeding system and significantly reduce fluctuations transmitted from upstream processes, enabling the extrusion process to quickly enter a stable working state. This helps improve the dimensional accuracy of the extruded products and reduce scrap rates, thereby saving raw materials and production costs.

Increased Production and Reduced Energy Consumption:

The melt pump can transfer the decompression function of the extruder to the gear pump, allowing the extruder to operate at lower pressure and temperature, thereby reducing leakage flow and increasing production. Simultaneously, the melt pump is more effective than the extruder in establishing die pressure, reducing the backpressure on the extruder, extending its service life, and lowering overall energy consumption.

Low-Temperature Extrusion and Extended Machine Lifespan:

Since the melt pump can stabilize the pressure and flow of the melt, the extruder can operate at lower temperatures, reducing machine wear and failure rates. This helps extend the service life of the extruder and the entire production line, lowering maintenance costs.

Simplified Production Process and Shorter Production Cycle:

With the addition of a melt pump to the PE foam sheet extrusion line, the pelletizing process can be eliminated, allowing direct extrusion of products. This simplifies the production process, shortens the production cycle, and improves production efficiency.

Simultaneous Feeding from Multiple Extruders

The melt pump can also enable multiple small to medium-sized extruders to simultaneously feed into a single melt pump. The melt is combined, pressurized, and metered by the melt pump before being supplied to the die for the extrusion of large products (such as large-diameter pipes, wide sheets, films, etc.). This configuration results in a compact production line with a small footprint, and the cross-sectional dimensions of the extruded products are more accurate and easier to control.

III. Selection and Considerations for Melt Pumps

When selecting a melt pump, factors such as the properties of the material (e.g., viscosity, temperature), the type and specifications of the extruder, the production capacity requirements of the line, and budget must be considered. Additionally, attention should be paid to the maintenance and upkeep of the melt pump to ensure its long-term stable operation.

In summary, polymer melt pumps have significant application advantages in PE foam sheet extrusion lines. They not only improve product precision and production output, reduce energy consumption and production costs, but also simplify the production process, shorten the production cycle, and extend machine lifespan. Therefore, installing melt pumps in PE foam sheet extrusion lines is a wise choice.

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