Dynamic Mould Tool for PVC Foam Sealing
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Solution Overview
Problem
The existing methods for producing PVC-based rigid foam polymer embryo bodies result in significant material wastage due to excess paste leakage during the molding process, with conventional solutions only partially addressing the issue of maintaining a sealed mold during heating and expansion.
Innovation Solution
A mould tool with moveable members and a sealing system that creates a hermetic seal during the heating and cooling process, allowing for controlled expansion and minimizing excess material loss, while also enabling efficient temperature control and precise shaping of the embryo bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional closed mould is used for molding PVC-based rigid foam embryo bodies, then the mould can be sealed during heating and cooling, but significant material wastage occurs due to excess paste leakage during the expansion step
Solution Approach 1:
The mould tool employs moveable mould members that can change position between different process stages. During heating and cooling, the members are in a first position providing a sealed closed mould. During expansion, they move to a second position that creates controlled clearance to accommodate paste expansion while preventing excessive leakage. This dynamic adjustment resolves the contradiction between maintaining seal integrity and managing material expansion.
Solution Approach 2:
The invention changes the geometric parameters of the mould cavity during the process by moving the mould members. The clearance between mould members is dynamically adjusted: minimal clearance during heating/cooling for sealing, and increased clearance during expansion to accommodate volume increase. This parameter change allows the system to adapt to different process requirements and eliminate excessive material wastage.
2Loss of substance
If the mould cavity volume is increased to accommodate paste expansion, then material wastage is reduced, but the mould cannot maintain proper sealing during heating and cooling
Solution Approach 1:
Rather than using a static mould with permanently increased volume, the invention uses dynamic movement of mould members to create temporary volume increase only when needed during expansion. The mould members move apart during expansion to provide necessary volume, then return to their original positions for proper sealing during heating and cooling. This dynamic approach resolves the contradiction between volume accommodation and seal maintenance.
3Reliability
If excess paste is allowed to leak out during expansion, then the mould remains sealed, but material wastage increases significantly
Solution Approach 1:
The moveable mould members create a dynamic sealing system that adapts to paste expansion. As the paste expands, the mould members move to maintain optimal contact and sealing while providing sufficient clearance to contain the expansion. This prevents the paste from leaking out excessively while still allowing for necessary volume increase, thus resolving the contradiction between maintaining seal and reducing wastage.
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 proposed mould tool reduces material wastage to less than 8% of the original volume, improves energy efficiency, and enhances the mechanical properties of the final polymer foam by maintaining precise pressure and temperature control, leading to improved production efficiency and reduced material consumption.
Implementation Method 1
a sealing means (40) in the form of a friction grommet
Implementation Method 2
a high pressure is created by the thermal expansion of the plastisol
Implementation Method 3
The plastisol is kept at elevated temperature a predetermined time to allow the plastisol to gelatinize
Implementation Method 4
where after the mould cavity is cooled to a temperature that is low enough to remove the embryo body from the mould
Data Source
Figure 1
Figure 2a~2d
Figure 3
AI summary
Mould tool to be arranged in a press with essentially parallel press surfaces for production of rigid expanded polymer embryo bodies, the mould tool comprises a first mould member and an second mould member that are moveable with respect to each other in a direction perpendicular to the press surfaces, and sealing means providing an essentially hermetic seal between the first and second mould member during at least a portion of such a relative motion, thereby defining a closed mould cavity y o f variable volume, wherein the first mould member defines at least a portion of the mould cavity y volume and comprises an outer peripheral edge, and the second mould member comprises a rim that closely circumscribes the outer peripheral edge of the first mould member and wherein the sealing means is arranged in the gap formed between the rim and the outer peripheral edge.