Oscillating Gap Twin-Screw Extruder for Recycled Plastic Mixing
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Solution Overview
Problem
Existing twin-screw extruders are not entirely satisfactory in achieving a high degree of mixing and processing quality, especially for recycled plastics used in food packaging, due to varying material conditions and contamination, and they require significant technical outlay and cost.
Innovation Solution
A conical twin-screw extruder design with oscillating gap between screw threads, driven by a motor, where the screw diameter is larger at the intake end than at the outlet, enhancing material compaction and friction, and featuring a periodic change in gap width to improve mixing and self-cleaning, while maintaining low operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional twin-screw extruders are used, then material processing is possible, but the degree of mixing is insufficient
Solution Approach 1:
The patent applies the dynamics principle by making the gap between screw threads oscillating instead of static. The gap width varies periodically during operation, creating dynamic mixing conditions that significantly improve the degree of mixing while maintaining processing quality. This is achieved through an oscillating mechanism that periodically changes the clearance between the co-rotating screws.
2Productivity
If large quantities of material are accommodated in the intake area, then throughput is sufficient, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by varying the gap width between screw threads during operation. This dynamic parameter adjustment improves material processing efficiency and mixing quality without requiring a larger intake area, thereby maintaining throughput while avoiding increased device complexity.
3Stress or pressure
If screw threads are designed for high friction, then material compaction is improved, but the risk of breakage increases
Solution Approach 1:
The patent applies dynamics by implementing an oscillating gap between screw threads. This dynamic variation in gap width creates periodic changes in friction and compaction forces, achieving effective material compaction while reducing the continuous high stress that would lead to breakage. The oscillating motion distributes stress more evenly over time.
4Adaptability or versatility
If longer screw lengths are used, then mixing is improved, but the cost of the device increases
Solution Approach 1:
The patent applies periodic action through the oscillating gap mechanism between screw threads. This periodic variation in gap width creates repeated cycles of compression and expansion that enhance mixing efficiency. As a result, shorter screw lengths can achieve the same mixing quality as longer screws, thereby reducing device manufacturing cost.
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 design achieves a high degree of mixing and improved processing of diverse materials, including recycled plastics, with reduced risk of breakage and increased throughput, using shorter screw lengths and a self-cleaning effect, while maintaining low costs.
Implementation Method 1
the conditions in the plastic material to be processed are not always the same, particularly with regard to the size of the material parts to be processed, but also their material type, contamination degree of extraction, etc.
Implementation Method 2
These quantities of material must then be plasticized or agglomerated to the desired extent during the transport from the intake opening to the outlet opening by the screws
Implementation Method 3
the screw diameter is larger at the intake end than at the outlet, enhancing material compaction and friction
Implementation Method 4
featuring a periodic change in gap width to improve mixing and self-cleaning
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The invention relates to a device for processing material by mixing and/or plasticisation and/or agglomeration. Said device comprises a screw housing (6), in which at least two screws (1, 2) are arranged next to one another. The screw threads (7) are intermeshed. The screws rotate by means of at least one motor (3). The material is supplied to the screws (1, 2) through a feed opening (39) of the screw housing (6) and the processed material exits the screw housing through at least one exit opening (51). The device is equipped with a unit (19), which alternately and periodically causes the gap that exists between the adjacent screw threads (7) of the screws (1, 2) to increase and decrease, said increase and decrease being superimposed on the rotational motion of the two screws (1, 2). According to the associated method for processing material, the material is also subjected to periodic compression, to achieve compaction obtained by the delivery action of the screws (1, 2).