Biaxial melt pump in the HDPE pipe extrusion line has significant technical advantages and application value, its core role is reflected in the stabilization of pressure and flow, improve the quality of plasticization, reduce the load on the equipment in three aspects, specific analysis is as follows:
First, stabilize the melt pressure and flow, to ensure the precision of pipe size
HDPE pipe production is extremely sensitive to melt pressure fluctuations, pressure fluctuations of more than ± 5% will lead to pipe wall thickness deviation, ellipticity exceeds the standard and other issues. Biaxial melt pump through the double gear synchronous drive design, the extruder output of the melt for the second pressurization and pressure stabilization, the pressure fluctuations can be controlled within ± 1%. For example, in the small diameter five-layer HDPE pipe production line of Suzhou Jinwei, the melt pump is connected in series with five single-screw extruders to ensure the precise matching of melt flow in the five-layer structure (PE/adhesive/EVOH/adhesive/PE), so that the cutting accuracy of the pipes with diameters of 50-125mm is ≤5mm, and the error of meter counting of the chipless cutting is only ±0.3%.
Second.Enhance the uniformity of melt plasticization and optimize the performance of pipeline.
The gear meshing structure of the double shaft melt pump can force the mixture of melt, eliminating the dead space of plasticization caused by the uneven shear of the extruder screw. In 1200 HDPE pipe extrusion line, melt pump and CE120-36 single-screw extruder, through the spiral feeder barrel and separate screw design, melt uniformity increased by 30%, effectively reduce the concentration of stress in the pipeline, so that the ring stiffness (SDR9-SDR21) and impact resistance of HDPE pipes (such as the passing rate of the impact test of the falling hammer) to meet the requirements of the industry standard.
Third, reduce the extruder load, prolong the life of the equipment
Biaxial melt pump can undertake 60%-70% of the extruder's pressurization task, so that the extruder screw speed is reduced by 20%-30%, thus reducing mechanical wear and energy consumption. Take ZB biaxial drive melt pump as an example, it adopts high temperature tool steel gears and screw sealing technology, which can run continuously for more than 20,000 hours under the working conditions of temperature ≤ 400℃ and viscosity ≤ 40,000 Pa-s, and the gear wear is 50% less than that of the single-axis pumps, which significantly reduces the maintenance cost of the equipment.
In PP/PE/PA and other pipe production, the flow range is 20-3200CC, temperature control accuracy ±1℃, suitable for Φ630-1200mm large diameter pipe extrusion.
Biaxial melt pump is the core auxiliary equipment of HDPE pipe extrusion line, its stabilizing pressure, improving quality and reducing load characteristics can significantly improve the pipe size accuracy, mechanical properties and production efficiency. For production scenarios of large diameter (≥630mm), multi-layer composite (e.g. five-layer structure) or high viscosity materials (e.g. special materials for pipes), biaxial melt pumps are the key choice to optimize the process and reduce costs.
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