Melt Spinning Spin Pack Assembly with Varying Aperture Diameters
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Solution Overview
Problem
Melt spinning of thermoplastic polyurethane (TPU) fibers faces issues such as polymer crystallization and crosslinking, leading to fiber defects, breakage, and excessive back pressure, which reduces production efficiency and requires frequent equipment cleaning.
Innovation Solution
A spin pack assembly with a breaker plate featuring apertures of varying diameters arranged in concentric circular patterns to ensure first-in/first-out material flow, combined with a recessed fiber exit configuration to slow cooling, minimizing polymer residence time and reducing back pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If melt spinning is used to produce TPU fibers, then environmental friendliness is improved (no solvent), but polymer crystallization and crosslinking occur leading to lumps and defects
Solution Approach 1:
The breaker plate with specifically designed aperture patterns creates controlled flow conditions before the material enters the spinneret, preventing crystallization and crosslinking by ensuring continuous motion and minimizing residence time in the melt state
Solution Approach 2:
The patent modifies flow parameters through the aperture configuration, creating velocity gradients and flow patterns that prevent the material from staying stationary long enough to crystallize or crosslink, while still achieving the desired fiber formation
2Reliability
If material residence time in spin pack assembly is reduced, then lump formation is minimized, but flow uniformity may be compromised
Solution Approach 1:
The breaker plate features apertures of varying sizes at different locations, creating locally optimized flow conditions where material moves through different path lengths and velocities, ensuring all regions experience sufficient motion to prevent lump formation while maintaining overall flow uniformity
Solution Approach 2:
The non-uniform aperture distribution and varying aperture sizes create asymmetric flow patterns that prevent stagnant zones and promote uniform material progression through the spin pack assembly, eliminating preferential flow paths that could lead to lump formation
3Productivity
If fiber cooling rate is increased, then production speed is improved, but fiber modulus becomes too high for circular knitting applications
Solution Approach 1:
The recessed fiber exit creates a dynamic cooling environment where the fiber can be pulled through at high speeds but maintains extended residence in the heated zone, allowing production speed increases while controlling the cooling rate to achieve desired fiber modulus through viscoelastic relaxation
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 configuration enhances material flow, reduces defects, and allows for longer production runs with lower modulus fibers, improving productivity and fiber quality for applications like circular knitting.
Implementation Method 1
The aperture in the center of the breaker plate is the smallest hole and the apertures are progressively larger the farther they are from the center of the breaker plate. This configuration of the holes in the breaker plate provides for first-in/first-out flow of material throughout generally the entire cavity within the spin pack assembly.
Implementation Method 2
The exit is disposed axially inward relative to the body opening. This structure in the exemplary embodiment allows the fibers to cool more slowly relative to prior designs.
Data Source
AI summary
A spin pack assembly for use in melt spinning elastic fibers. The spin pack assembly includes a circular breaker plate having a center aperture and several circular patterns of apertures with each circular pattern having a plurality of apertures. Each circular pattern is located concentrically about an axis of the center aperture. The apertures in the outer circular patterns have a greater diameter than the apertures in the inner circular patterns. The spin pack assembly also has a spinneret plate where the exit aperture of the spinneret plate is recessed in the body of the spin pack assembly.