Melt pump use, internal structure and material requirements

Melt pumps can work continuously at high temperatures up to 350C and pressures up to 35MP or higher. Its main function is to pressurize and stabilize the high temperature plastic melt from the extruder, and keep the melt flow accurately and stably into the extruder head. When the melt at the inlet of the pump produces large pressure fluctuations due to various reasons, the pressure fluctuations caused at the outlet are extremely small. Its ability to stabilize melt pressure and flow is superior to various types of extruders. Its main features are simple and compact structure, reliable operation and long life.

The composition of the melt pump mainly includes the pump body, front and rear side plates, two intermeshing gears, bearings and seals. The space formed by the tooth profile of the two gears, the pump body and the side plate forms the pump's feeding, conveying and discharging areas. Gear is the core part of the melt pump, its structure in various forms, according to the meshing method can be divided into internal and external meshing mode; according to the tooth profile curve can be divided into involute gears, arc gears, cycloid gears, etc.; according to the tooth direction can be divided into straight gears, helical gears and herringbone gears. However, in the process of conveying plastic melt, the most commonly used is involute straight teeth or helical teeth of the external gear pump.

As the melt pump is in high temperature, high pressure conditions of continuous work, and transport of plastic melt generally has a high viscosity, some also has a certain degree of corrosiveness. Therefore, the melt pump material requirements are very high, need to have temperature resistance, wear resistance, corrosion resistance, and to have sufficient strength and dimensional stability. Usually, the melt pump is mainly made of alloy tool steel, gears and shafts into one, so that under high torque conditions more reliable.

Melt pump lubrication and sealing issues are more complex, in order to prevent contamination of the plastic melt, it can not use the general lubricant or grease lubrication, but with the help of transporting the plastic melt for self-lubrication. Therefore, the melt pump bearing and sealing structure must be adapted to the special properties of the plastic melt. For small and medium-sized melt pumps are generally heated and insulated with electric heat, while large melt pumps use jacketed pump body with fluid temperature control.

The company is very familiar with the extrusion process of various plastics and rubber materials, and has a lot of experience in the application of melt pumps for extrusion systems, and is able to provide a wide range of melt pumps for various sheet, plate, pipe, film, wire drawing, underwater pelletizing, masterbatch extrusion pelletizing, rubber preforms and other extrusion systems.

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