Melt pump for PP hollow sheet extrusion line

The melt pump in a PP hollow sheet extrusion line serves as a crucial element, primarily responsible for conveying, pressurizing, and metering high-temperature, high-viscosity polymer melts, thereby ensuring the stable operation of the production line and the quality of the product. Below is a detailed analysis of the melt pump in a PP hollow sheet extrusion line:

I. Functions of the Melt Pump

Conveying and Pressurizing: The melt pump receives high-temperature plastic melt from the extruder, pressurizes and stabilizes it, and then smoothly feeds it into the extruder head, ensuring that the melt maintains a consistent pressure and flow rate during transportation.

Metering and Control: The melt pump boasts precise metering capabilities, enabling the adjustment of melt delivery volume according to production requirements, thereby enhancing product dimensional accuracy and consistency.

Stable Extrusion: By eliminating fluctuations in the extrusion process, the melt pump facilitates stable extrusion, ultimately reducing scrap rates.

II. Structure and Working Principle of the Melt Pump

Structural Composition: The melt pump primarily comprises a pump casing, a driving gear, a driven gear, sliding bearings, front and rear end plates, and gland seals. The tooth profiles of the gears, the pump body, and the side covers collectively form the feed zone, conveying zone, and discharge zone of the pump.

Working Principle: As a positive displacement device, the melt pump functions by utilizing the volumetric changes caused by the meshing of the driving and driven gears to convey the melt. When the gears rotate in a specified direction, the melt enters the tooth spaces of the gears in the feed zone. As the gears continue to rotate, the melt is carried into the conveying zone and ultimately extruded out of the discharge zone into the outlet piping.

III. Application of the Melt Pump in PP Hollow Sheet Extrusion Lines

Improved Production Efficiency: The application of the melt pump ensures stable pressure and flow rate of the melt during extrusion, thereby enhancing the overall efficiency of the production line.

Enhanced Product Quality: With its precise metering and stable extrusion capabilities, the melt pump significantly reduces product dimensional tolerances and scrap rates, leading to an overall improvement in product quality.

Extended Equipment Lifespan: By sharing part of the workload with the extruder, the melt pump allows the extruder to operate at lower pressures and temperatures, thereby extending its service life.

IV. Selection and Maintenance of the Melt Pump

Selection Criteria: When selecting a melt pump, it is crucial to consider the specific needs of the production line, the characteristics of the melt, and the pump's performance parameters. Additionally, attention should be paid to the pump's brand, quality, and service.

Maintenance: Regular maintenance of the melt pump is essential for ensuring its long-term stable operation. Maintenance tasks include cleaning the pump body, checking the wear of the gears, and replacing the lubricating oil.

In conclusion, the melt pump in a PP hollow sheet extrusion line is an indispensable component that plays a vital role in improving production efficiency, enhancing product quality, and extending equipment lifespan. Therefore, when designing and selecting a production line, it is imperative to give full consideration to the performance and configuration requirements of the melt pump.

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