The rubber extrusion melt pump is the core equipment in rubber extrusion systems, primarily used for the conveyance, pressurization, pressure stabilization, and metering of high-temperature, high-viscosity rubber melts. Its core functions, working principles, structural features, and performance advantages are outlined as follows:
I. Core Functions
Melt Conveyance: Uniformly transports rubber melt from the extruder to the die, ensuring continuous production.
Pressurization and Pressure Stabilization: Generates high pressure through gear meshing, eliminating pressure fluctuations in the extruder and controlling them within ±1%, thereby enhancing dimensional accuracy of finished products.
Precise Metering: Flow rate is strictly proportional to rotational speed, enabling high-precision control of melt flow (accuracy up to ±0.5%), suitable for products with stringent dimensional tolerances (e.g., medical catheters, optical films).
Low-Temperature Extrusion: Allows the extruder to operate under low-pressure, low-temperature conditions, reducing mechanical energy conversion heat, lowering energy consumption by 30%-50%, and extending equipment lifespan.
II. Working Principle
Based on the positive displacement conveyance principle, a closed working volume is formed through the mutual engagement of the driving gear and driven gear inside the pump housing:
Suction Phase: As the gears rotate, melt enters the feed zone tooth grooves.
Conveyance Phase: Gear rotation carries the melt into the conveyance zone, preventing backflow.
Discharge Phase: The gears re-engage, compressing the melt and pressing it into the outlet pipeline.
Characteristics: As long as the pump shaft rotates, the gears continuously pressurize and convey the melt, achieving high outlet pressure (e.g., 40 MPa) while requiring low inlet flow and pressure, even enabling vacuum suction.
III. Structural Features
Core Components:
Pump Head: Composed of the pump housing, front/rear side covers, gear shafts, sliding bearings, shaft seals, etc.
Gears: Designed with straight or helical teeth for efficient transmission; crafted from special tool steel or alloy materials with mirror-finished surfaces (near-mirror gloss) to accommodate thermally sensitive materials.
Bearings: Sliding bearings made of special alloy materials offer excellent wear and corrosion resistance.
Shaft Seals: Feature a spiral external discharge design to prevent melt leakage.
Auxiliary Systems:
Heating/Cooling: Circulating water heating and shaft-end cooling systems control operating temperatures ≤350°C.
Drive Unit: Includes motors, reducers, universal couplings, etc., supporting multiple installation methods (vertical or horizontal input shaft arrangements).
Flow Channel Optimization: Mirror-finished internal flow channels minimize residue and provide self-cleaning functionality.
IV. Performance Advantages
Efficiency and Stability:
Optimized gear design reduces shear stress under high pressure, ensuring constant melt flow.
Linear extrusion characteristics facilitate coordination between upstream and downstream equipment, enabling full-process online monitoring and feedback control.
Safety and Durability:
Wear-resistant bearings and dynamic lubrication technology enhance load capacity and impurity tolerance, accommodating high-viscosity materials (e.g., rubber with viscosity up to 40,000 Pa·s).
Special alloy gears and bearings extend service life, reducing downtime and maintenance.
Energy Conservation:
Reduces extruder backpressure and screw axial force, prolonging equipment lifespan.
Precise temperature control lowers heating power, cutting overall energy consumption by 30%-50%.
Versatility:
Processes materials such as PVC, BR, CR, EPDM, NBR, SBR, natural rubber, and even easily degradable substances.
Supports high-pressure operations (outlet pressure up to 40 MPa, pressure differential 25 MPa) to meet demands for premium products.
V. Typical Applications
Rubber Extrusion: Enhances dimensional accuracy and surface quality of products like tire treads, rubber hoses, and sealing strips.
Chemical Fiber Spinning: Stably conveys high-temperature melts (e.g., polyester, nylon), reducing filament breakage and improving fiber uniformity.
Plastic Recycling: Homogenizes viscosity fluctuations in recycled materials, elevating regenerated plastic quality (e.g., narrowing HDPE melt index fluctuation range from ±15% to ±3%).
High-Performance Engineering Plastics: Processes high-temperature materials like polyether ether ketone (PEEK) and polyimide (PI), with a temperature resistance rating of up to 400°C.
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