Melt Spinning Downpipe Air Permeable Sections Turbulence Control
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Solution Overview
Problem
Conventional melt spinning systems face issues with turbulent air flows and backflows in the blower duct/downcomer system, leading to filament breaks and quality issues during the production of coarser yarns like BCF and tire cord, due to uncontrolled air currents and pressure imbalances.
Innovation Solution
The introduction of air-permeable sections in the downpipe, specifically perforated plates or sieves, to control air flow and maintain a stable pressure profile, reducing turbulence and backflows by allowing air to exit laterally, thus matching the air flow to the decreasing cross-section and preventing ambient air intrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air-permeable sections are introduced in the downpipe to control air flow, then turbulence and backflows are reduced, but device complexity increases
Solution Approach 1:
The downpipe is equipped with air-permeable sections (perforated plates or sieves) that allow controlled lateral air exit. This porous structure enables the downpipe to regulate air flow while maintaining structural integrity, reducing turbulence and backflows without requiring complex external control systems.
Solution Approach 2:
The downpipe is divided into air-permeable and air-impermeable sections. This segmentation allows different parts of the downpipe to perform different functions: permeable sections control air exit to prevent backflows, while impermeable sections maintain structural strength and guide filament flow.
2Productivity
If air flow is increased to cool filaments at higher production speeds, then productivity increases, but turbulence and filament breaks increase
Solution Approach 1:
Excess air is extracted laterally through the air-permeable sections of the downpipe at controlled locations. This removes surplus air from the system before it can create harmful turbulence and backflows, allowing high production speeds to be maintained without compromising filament integrity.
Solution Approach 2:
The air-permeable sections act as intermediaries between the main air flow and the external environment. They provide a controlled interface for air to exit the downpipe laterally, mediating the air flow to prevent sudden pressure changes and turbulence that would otherwise occur at the downpipe outlet.
3Productivity
If the downpipe cross-section decreases to match air flow, then air flow efficiency improves, but pressure build-up and backflows occur
Solution Approach 1:
Air exit is enabled in a lateral dimension through the air-permeable sections, rather than only at the downstream outlet. This dimensional change in air discharge allows the downpipe cross-section to decrease for efficiency without creating pressure build-up, as air can escape laterally at multiple points along the downpipe length.
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 design ensures a stable, turbulence-free air flow that minimizes filament contact and breakage, maintaining consistent air conditions and improving yarn quality even at higher production speeds and air volumes.
Implementation Method 1
The introduction of air-permeable sections in the downpipe, specifically perforated plates or sieves, to control air flow and maintain a stable pressure profile
Implementation Method 2
reducing turbulence and backflows by allowing air to exit laterally
Data Source
Figure 1A~1B
Figure 2~3
Figure 4A~5B
AI summary
After emerging from the spinneret, the filaments are cooled by a flow of air in the blowing section (10) and then proceed through the chimney (12B) to the wind-up. The walls (26, 28) of the chimney converge towards the exit. A section (32) is porous e.g. less than 50 % in length and having a porosity of 20 to 40 %, to allow air to escape. With a rectangular chimney only one wall need be porous and additional controlled suction can be provided to assist the flow. Independent claims are included for the following: (1) A chimney in which the access doors have a porosity of less than 20 %, preferably 4 to 8 %; (2) A melt spinning process using such a chimney in which the boundary layer on the inner chimney walls is maintained without interruption along its whole length; (3) A melt spinning process of this kind in which some air can escape from the chimney prior to the exit.