Gear Pump Series Control for Uniform Polyolefin Membrane Thickness
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Solution Overview
Problem
Existing methods for producing polyolefin microporous membranes struggle to achieve uniform thickness due to low volumetric efficiency and increased pressure fluctuations in gear pumps, leading to reduced discharge accuracy and increased costs when additional extruders are used.
Innovation Solution
A method involving a series of gear pumps where the most downstream pump operates at 90% or more volumetric efficiency and other pumps at 50-90% efficiency, with a differential pressure of 7.0 MPa or less, stabilizes the resin flow and ensures uniform thickness without additional extruders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If two gear pumps are provided in series with conventional control methods, then the discharge amount can be controlled, but the volumetric efficiency of the downstream gear pump becomes too low and discharge accuracy decreases
Solution Approach 1:
The invention changes the operating parameters of the gear pumps by controlling the upstream gear pump to maintain suction pressure within 0.01 to 0.2 MPa and differential pressure between gear pumps within 5 to 15 MPa. This parameter optimization ensures the downstream gear pump operates at high volumetric efficiency (90% or more) while maintaining stable discharge accuracy for uniform membrane thickness
Solution Approach 2:
The invention implements feedback control by monitoring suction pressure at the upstream gear pump and differential pressure between gear pumps, then adjusting operations to maintain pressures within specified ranges. This feedback mechanism prevents volumetric efficiency degradation and maintains discharge accuracy
2Manufacturing precision
If both gear pumps are operated at high volumetric efficiency, then discharge accuracy improves, but polymer flow to the gear pumps is reduced and pressure fluctuations increase
Solution Approach 1:
The invention optimizes pressure parameters by controlling differential pressure between gear pumps within 5 to 15 MPa and suction pressure within 0.01 to 0.2 MPa. This parameter range allows the upstream gear pump to operate at moderate volumetric efficiency (50-90%) while the downstream pump maintains high efficiency, balancing discharge accuracy with pressure stability
Solution Approach 2:
The invention dynamically balances the operating states of the two gear pumps by allowing different volumetric efficiency ranges for upstream versus downstream pumps. This dynamic configuration stabilizes pressure fluctuations while maintaining overall system discharge accuracy
3Manufacturing precision
If an additional extruder is provided between gear pumps to reduce thickness unevenness, then manufacturing precision improves, but production cost increases and residence time becomes longer causing resin deterioration
Solution Approach 1:
The invention achieves thickness uniformity (σ/average thickness of 1.7% or less) by optimizing gear pump operating parameters rather than adding equipment. By controlling suction pressure (0.01-0.2 MPa) and differential pressure (5-15 MPa), the system maintains discharge accuracy without requiring an additional extruder, thereby reducing cost and residence time
Solution Approach 2:
The invention extracts the essential function needed for thickness uniformity from the complex solution of adding a second extruder. Instead of adding equipment, it extracts and optimizes the control parameters of the existing gear pump system to achieve the same thickness uniformity result with simpler, lower-cost equipment
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a polyolefin microporous membrane with reduced thickness unevenness, improved discharge accuracy, and enhanced battery performance as a separator, preventing thermal shrinkage and maintaining puncture strength.
Implementation Method 1
transporting a fluidized resin by a plurality of gear pumps connected to each other in series
Implementation Method 2
molding the transported fluidized resin into a sheet shape by a spinneret
Implementation Method 3
cooling the discharged polyolefin solution to mold the discharged polyolefin solution into a continuous sheet shape
Data Source
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AI summary
The present invention pertains to a sheet manufacturing method involving transporting a fluidized resin by means of a plurality of gear pumps connected in series and molding, into a sheet shape, the transported fluidized resin by a ferrule. In the sheet manufacturing method, the most downstream-side gear pump among the plurality of gear pumps is operated so that the volumetric efficiency is at least 90.0%, the gear pumps other than the most downstream-side gear pump is operated so that the volumetric efficiency is no smaller than 50.0% and smaller than 90.0%, and the pressure differences between the plurality of gear pumps is no greater than 7.0 MPa.