Static Mixer Supports Crosshead in Annular Extrudate Device
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Solution Overview
Problem
Existing methods for manufacturing annular extrudates from polymeric materials face challenges in achieving uniform temperature and velocity distribution, leading to inconsistent foam quality, mechanical properties, and increased pressure drop, which affects the cellular structure and dimensional stability of the extrudates.
Innovation Solution
A device comprising a stationary jacket and a stationary crosshead with a static mixer that supports the crosshead, allowing for at least 20% of the supporting forces to be absorbed by the static mixer, thereby reducing the need for conventional supporting elements and enhancing mixing and temperature homogenization within the annular passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional supporting elements are used to support the crosshead in the annular passage, then the structural stability is maintained, but the device complexity increases and the mixing efficiency decreases
Solution Approach 1:
The patent combines the supporting function and the mixing function into a single integrated static mixer structure. The static mixer elements serve dual purposes: they provide structural support for the crosshead while simultaneously performing the mixing function, thereby reducing device complexity without compromising structural stability
Solution Approach 2:
The static mixer is designed to perform multiple functions: it supports the crosshead structurally, mixes the polymer melt, and maintains flow homogeneity. This multi-functionality eliminates the need for separate supporting elements, reducing overall device complexity while maintaining reliability
2Temperature
If the flow velocity near the wall of the annular gap is lower than in the central portion, then the pressure drop is reduced, but the temperature distribution becomes non-uniform
Solution Approach 1:
The static mixer introduces localized mixing elements at specific positions within the annular passage where flow velocity differences create temperature non-uniformities. These elements provide enhanced mixing locally to compensate for the velocity gradient effects without requiring a complete redesign of the flow profile
Solution Approach 2:
The patent modifies the flow parameters by introducing static mixing elements that create controlled turbulence and enhance radial mixing. This changes the flow regime to improve temperature distribution while the design optimizes the mixing element geometry to minimize excessive pressure drop
3Manufacturing precision
If the crosshead is supported by multiple conventional supporting elements, then the structural stability is ensured, but the mixing homogeneity decreases
Solution Approach 1:
The supporting elements are merged with the static mixer structure, creating an integrated component that performs both support and mixing functions. This eliminates the need for separate supporting elements and improves mixing homogeneity by ensuring the supporting structure itself contributes to flow uniformity
Solution Approach 2:
The static mixer structure serves itself by providing both structural support and mixing functionality. The supporting elements are designed to inherently promote flow homogeneity through their geometry and positioning, eliminating the need for additional mixing components
4Temperature
If helical distributors or spiral redirecting devices are used to equalize temperature, then the temperature homogeneity is improved, but a spiral flow is created that cannot equalize temperature variations across the width of the annulus
Solution Approach 1:
The static mixer is divided into multiple mixing elements or zones arranged along the annular passage. Each segment addresses specific local temperature variations, including those across the width of the annulus, providing comprehensive temperature equalization without creating problematic spiral flows
Solution Approach 2:
Instead of using helical or spiral redirecting devices that create rotational flow, the patent employs static mixing elements that promote radial and axial mixing without inducing spiral motion. This inverted approach achieves temperature equalization across the width of the annulus without the drawbacks of spiral flow patterns
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 results in a more compact and cost-effective device that ensures uniform temperature and velocity distribution across the annular cross-section, improving the mechanical properties and dimensional stability of the extrudates, and achieving higher product quality with a uniform cell structure and reduced foam density.
Implementation Method 1
The annular passage (5) contains a static mixer (3), whereby the crosshead (1) is supported at least partially by the static mixer (3) in the jacket (2)
Data Source
AI summary
A device (4) for the manufacture of an annular extrudate comprises a jacket (2), a crosshead (1) arranged inside of the jacket. The jacket contains a melt passage, whereby the crosshead is arranged in the melt passage, such that the melt passage extends et least at the outlet of the device as an annular melt passage around the crosshead (1). An annular passage (5) is formed between the crosshead and the jacket. The annular passage contains a static mixer (3), whereby the crosshead is at least partially supported by the static mixer in the jacket. The static mixer comprises a plurality of inserts, whereby at least a portion of the inserts is connected to the crosshead and/or the jacket.