Mixer Shaft with Continuous Screw Section for Polymer Additive Mixing
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Solution Overview
Problem
Existing mixers with multiple zones face challenges in preventing back-mixing of additives, especially those with solid or oily properties like soot, which contaminates polymer granulates undesirably, leading to economic inefficiencies and poor product quality.
Innovation Solution
A mixer design featuring helically arranged non-permanent conveying pattern shapes on the mixing shaft with a continuous screw conveyor section between mixing zones, preventing the back-mixing of additives by ensuring they cannot return from the subsequent mixing zone, thus maintaining additive separation and improving mixing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional mixer with single mixing zone is used, then the structure is simple and easy to clean, but additives back-mix into previous zones causing contamination and poor product quality
Solution Approach 1:
The mixer is divided into multiple mixing zones (first mixing zone, second mixing zone, etc.) separated by partition walls with slots. Each zone handles specific additives independently, preventing back-mixing while maintaining structured complexity for better additive separation precision.
Solution Approach 2:
Different sections of the mixer have different structures: some areas have open helical conveyors for mixing, while partition walls with slots create restricted flow paths. This local differentiation ensures that each zone maintains its additive separation while contributing to overall mixing functionality.
2Manufacturing precision
If multiple mixing zones are created with partition walls, then additive back-mixing is prevented, but the device becomes more complex and harder to clean
Solution Approach 1:
The partition walls are segmented with slots rather than being completely solid, creating controlled pathways that allow material flow while maintaining separation. This segmentation approach prevents back-mixing without creating fully enclosed complex chambers that would be difficult to clean.
Solution Approach 2:
The slots in partition walls act as intermediaries that control material flow between zones. They allow necessary material passage while preventing direct back-mixing, and their open structure facilitates easier cleaning compared to solid partitions with small openings.
3Productivity
If solid additives like soot are mixed in conventional mixers, then the mixing process is simple, but soot contaminates polymer granulate causing economic inefficiency and quality issues
Solution Approach 1:
Soot mixing is isolated in a dedicated second mixing zone downstream from the first mixing zone. The partition wall with slots between zones creates a unidirectional flow that prevents soot from back-mixing into the polymer granulate in the first zone, maintaining both mixing efficiency and product quality.
Solution Approach 2:
The polymer granulate is pre-mixed with non-soot additives in the first mixing zone before entering the second mixing zone where soot is added. This preliminary action ensures that the polymer matrix is prepared and protected from soot contamination before the soot mixing operation occurs.
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 allows for the effective addition of multiple additives without contamination, enhancing product quality and economic efficiency by preventing undesired mixing, especially when using soot or other difficult-to-handle additives, and maintaining the benefits of multiple mixing zones over extended periods.
Implementation Method 1
at least one mixer shaft (3), having non-continuous conveying pattern shapes (5a), helically arranged, mounted on its surface
Implementation Method 2
The mixing shaft (3) together with the screw conveyors is then rotated, whereby the polymer granulate and the additive are being moved within the housing
Implementation Method 3
between at least two mixing zones on the surface of the mixing shaft one section featuring a continuous screw conveyor instead of the non-continuous conveying pattern shapes
Data Source
AI summary
The invention focuses on a device for sequentially introducing additives in a polymer granulate and the use of the device for mixing the polymer granulate with the additives. The device consisting of a mixer with housing, comprising at least one mixer shaft attached in helix arranged non-continuous conveying pattern shapes, being rotated by a drive for the transport, whereby the mixer in the housing featuring an inlet for the polymer granulate to be mixed and each of the several subsequent inlets for the additive is followed by an outlet for the polymer granulate mixed with the additive, so that two or several mixing zones being formed in the mixer and whereby at least between at two mixing zones on the surface of the mixing shaft one section featuring a continuous screw conveyor instead of the non-continuous conveying pattern shapes, the section not being penetrable for returning solids from the subsequent mixing zone.