Metering Device Segmented Porous Elements High Pressure
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Solution Overview
Problem
Existing metering devices for additives in plastic melts, particularly in high-pressure processes, face challenges such as limited pressure resistance, shear sensitivity, and the risk of crack formation due to pressure cycling, which affects the quality of molded parts and the durability of metering elements.
Innovation Solution
A metering device with a die-cast static mixing element and channel sections connected via a welded inseparable connection, featuring a circular or elongated inlet cross-section with convex/concave edges, and a pore-like structure, designed to minimize surface area occupancy under high pressure, ensuring robustness and efficient mixing without introducing excessive shear forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous cylinder is used to introduce blowing agent into the melt stream, then the blowing agent can be metered and homogenized, but the cylinder lacks sufficient pressure resistance in high-pressure processes
Solution Approach 1:
The single porous cylinder is segmented into multiple separate porous metering elements (at least two) that are arranged in series within the flow channel. Each metering element handles a portion of the blowing agent introduction, distributing the functional load and reducing the stress concentration on individual elements, thereby improving overall pressure resistance while maintaining metering reliability.
Solution Approach 2:
The porous metering elements are positioned specifically in regions where the melt flow velocity is lower, optimizing the local conditions for blowing agent introduction. This local optimization allows the porous structure to function effectively at lower stress points while avoiding high-stress regions, thereby maintaining metering reliability without requiring excessive overall pressure resistance.
2Reliability
If the proportion of channel section occupied by metering elements is increased, then the blowing agent entry surface is increased, but the pressure resistance of the channel section decreases
Solution Approach 1:
The channel section is segmented into multiple zones with porous metering elements distributed throughout, rather than using a single large porous structure. This segmentation increases the total surface area for blowing agent introduction while maintaining sufficient material between elements to preserve the overall structural strength and pressure resistance of the channel section.
Solution Approach 2:
Porous metering elements are strategically positioned in specific local regions of the channel section where they can effectively introduce blowing agent without compromising the global structural integrity. The distribution and sizing of elements are optimized to achieve adequate blowing agent introduction efficiency while maintaining the channel section's ability to withstand high pressures.
3Stability of the object's composition
If a static mixing element is provided in the flow space, then the polymer/blowing agent system is homogenized, but additional stresses are introduced into the cylinder jacket
Solution Approach 1:
The static mixing element is merged with the channel section to form an integrated, inseparable structure. This combination eliminates the need for separate attachment mechanisms that would introduce additional stresses and potential failure points into the cylinder jacket. The mixed polymer/blowing agent system achieves homogeneity through this integrated design without compromising the structural integrity of the cylinder.
Solution Approach 2:
The static mixing element and channel section are designed as a composite inseparable connection, combining the mixing function with the structural function in a single integrated component. This composite approach allows the structure to withstand high pressures while simultaneously providing effective mixing, avoiding the stress concentration that would result from separate attached components.
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 enhances the metering device's resistance to pressure loads, prevents crack formation, and ensures homogeneous mixing, even under long-term loading, improving the quality and consistency of molded parts across both low and high-pressure processes.
Implementation Method 1
The metering device (3) comprises a first channel section (29) which receives the fluid, viscous or flowable pasty mass, the fluid flowing through the channel section (29). The channel section (29) contains at least one metering element (31). The additive is introduced into the polymer melt via the pores in the hollow body
Implementation Method 2
The additive is fed under pressure into the metering device via at least one channel (36) for additive supply. The proportion of the surface of the channel section that is occupied by metering elements is a maximum of 20% at a maximum operating pressure of 1000 bar
Data Source
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AI summary
A metering device (3) for introducing additives into a viscous fluid or a pasty mass, in particular a polymer melt, comprises a channel section (29) for receiving the fluid, wherein the fluid flows through the channel section (29), and/or a further channel section (30) around which the fluid can flow. The channel section (29) through which the fluid flows and/or around which the fluid flows contains at least one metering element (31). The channel section (29, 30) includes a recess (32) for receiving the metering element (31), wherein the recess (32) is bounded on all sides by the channel section (29, 30) and the metering element (31) is held in the recess (32).