Tube-Forming Sleeve With Eccentric Melt Mixing for Clean Preforms
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Solution Overview
Problem
Existing extrusion techniques for forming polymer preforms with variable wall thickness suffer from material residues at dead spots during material or color changes, leading to contamination and limited wall thickness variation, resulting in inhomogeneous products.
Innovation Solution
The extrusion technique includes a melt receiving device with an eccentrically rotated stirring body to minimize dead water zones, a tube-forming device with embedded guiding passages to prevent sedimentation, a profiling device for variable wall thickness adjustment, and a throttling device for precise flow control, all integrated into an extruder unit for improved homogeneity and rapid material changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional extrusion techniques are used, then the extrusion device can be simple in design, but material residues remain at dead spots during material or color changes causing contamination
Solution Approach 1:
The melt passage is designed with asymmetric geometry including an eccentric stirring body that rotates off-center within the passage. This asymmetric configuration eliminates dead spots by ensuring continuous contact and movement of the melt against all surfaces, preventing material residues from accumulating during changes in material or color.
Solution Approach 2:
The stirring body is designed to rotate dynamically within the melt passage, creating continuous motion that prevents stagnation. This dynamic element ensures that the melt flows continuously through the passage, eliminating dead zones where material could accumulate and causing contamination during material or color changes.
2Adaptability or versatility
If conventional extrusion techniques are used, then the device structure can be simple, but wall thickness variation is limited to single type
Solution Approach 1:
The extrusion device incorporates dynamically adjustable components including a movable profiling device that can change the wall thickness profile during operation. This dynamic adjustment capability allows the same device to produce various wall thickness variations (e.g., variable thickness, thickened sections, thinned sections) without requiring multiple dedicated devices.
Solution Approach 2:
The extrusion device is designed with universal components that can handle multiple wall thickness profiles through adjustable profiling devices and可控 throttling mechanisms. This multi-functional design enables a single device to produce diverse preform geometries including constant thickness, variable thickness, and localized thickening or thinning sections.
3Productivity
If material changes are performed in conventional extrusion, then production can continue, but contamination occurs due to residues in dead spots
Solution Approach 1:
The rotating stirring body creates continuous dynamic motion in the melt passage that prevents material stagnation. This continuous movement ensures that when material or color changes occur, the melt flows continuously through the passage without forming residues, allowing production to continue without contamination.
Solution Approach 2:
The extrusion process maintains continuous flow of melt through the passage with the rotating stirring body ensuring uninterrupted movement. This continuous action prevents the formation of dead zones and residues, allowing rapid material or color changes without contamination while maintaining production continuity.
4Manufacturing precision
If dead water zones are present in the melt passage, then the passage geometry can be simple, but inhomogeneity occurs in the extruded product
Solution Approach 1:
The melt passage employs asymmetric geometry with an eccentric stirring body that creates non-uniform flow patterns. This asymmetric design eliminates dead water zones by ensuring the melt continuously contacts all passage surfaces, preventing inhomogeneity and ensuring uniform material distribution in the extruded product.
Solution Approach 2:
The rotating stirring body introduces mechanical motion that creates dynamic flow patterns and prevents stagnation in the melt passage. This mechanical action eliminates dead water zones and ensures homogeneous material distribution, preventing inhomogeneity in the final extruded product.
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
The solution effectively reduces contamination and inhomogeneity, enables universal usability for various preform designs, and facilitates rapid and error-free material changes, enhancing production quality and efficiency.
Implementation Method 1
a stirring body, which converges to a point in the flow direction of the polymer melt, is arranged, which stirring body can be or is rotated about a rotation axis. The stirring body has a tip arranged eccentrically relative to the rotation axis. Due to the eccentricity of the tip, during a rotation of the stirring body, an additional mixing in the transition region between the annular gap and the full-surface cross section is generated
Implementation Method 2
A polymer melt can be or is introduced into the hollow guide body from one side (inlet side) in a flow direction. On the inlet side of the melt receiving device, between the guide body and the stirring body, the melt passage has a cross section in the shape of an annular gap. On the outlet side of the melt receiving device, the melt passage has a full-surface cross section.
Data Source
AI summary
Methods, apparatuses, systems, and techniques relate to a tube-forming device for an extruder unit or an extrusion device and a tube-forming process. The tube-forming device comprises at least one shaping sleeve, which is designed to shape a supplied stream of polymer melt from a substantially strand-like cross section into a tubular cross section. The shaping sleeve has a guiding passage embedded in the sleeve wall, such that the guiding passage is a cavity which lies within the sleeve wall and, in the radial direction of the shaping sleeve, is enclosed in a sealed manner with respect to the outer surfaces.