A melt gear pump is a positive displacement pump. Its core mechanism relies on the rotation of a pair of high-precision meshing gears to periodically alter the volume of a sealed chamber. This action completes the cycle of melt intake, conveyance, and discharge, enabling high-pressure, stable, and metered melt delivery. It is often referred to as the “precision pressure regulator” of extrusion production lines. The detailed working principle is as follows:
Core Structure and Component Functions
The core structure of a melt gear pump includes the pump body, drive/driven gears, front and rear end caps, bearing assemblies, sealing devices, and the drive system. The gear set is the central component, while the drive system provides power and controls rotational speed to ensure stable delivery.
Step-by-Step Operational Analysis
Suction Phase: The drive system rotates the drive gear, causing the driven gear to rotate synchronously in the opposite direction. The gear teeth on the suction chamber side gradually disengage, expanding the sealed volume formed by the gear teeth, pump body, and end covers. This creates a local vacuum, drawing the melt into the gear teeth under feed pressure or external pressure, completing the melt suction process.
Conveyance Stage: As the gears continue rotating, the melt in the intake grooves is transported to the discharge chamber on the opposite side of the pump body. During this process, the melt moves smoothly guided by the grooves. The sealed chamber consistently isolates the intake and discharge chambers, preventing melt backflow and ensuring conveyance efficiency and stability.
Discharge Stage: On the discharge side, the gears engage in meshing. The enclosed volume progressively decreases, forcing the melt within the gear pockets to be squeezed out and pressurized into the outlet pipeline. This achieves pressurized and stable discharge of the melt. Simultaneously, the tooth contact line formed by the meshing gears effectively separates the suction and discharge chambers, maintaining the pressure differential and ensuring consistent material discharge.
Key Features and Extended Principles
Linear Flow-Speed Relationship: Output flow is strictly proportional to gear rotation speed. Precise adjustment of drive speed enables exact control of melt output volume, adapting to diverse production line requirements.
High-Efficiency Pressure Stabilization: As a positive displacement conveying device, outlet pressure can exceed 35 MPa while flow remains largely unaffected by outlet pressure. This significantly reduces melt pressure fluctuations, enhancing product precision.
Sealed Chamber Leak Prevention: Minimal gear meshing clearance, combined with high-precision pump bodies and sealing structures, minimizes melt leakage, ensuring conveying efficiency and production stability.
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