Molding Kit for Layered Polymeric Articles
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Solution Overview
Problem
The existing methods for molding layered articles made of polymeric materials, such as shoe soles, often result in irregular demarcation lines between distinct layers due to material mixing during the molding process, leading to aesthetic issues and high discard rates.
Innovation Solution
A molding kit comprising a male mold part, a female mold part, and an intermediate insert, where the components are heated to a temperature above the softening point of the polymers, allowing separate injection into perimetric seats with grooves that prevent mixing, ensuring a sharp and regular demarcation line between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional injection molding is used to produce layered articles, then the molding process is simple and efficient, but the demarcation lines between layers become irregular due to material mixing
Solution Approach 1:
The mold is segmented into multiple independent cavities (first cavity, second cavity, etc.) that are isolated from each other by partition walls. Each cavity receives a specific polymeric material independently, preventing mixing between different materials while maintaining efficient injection molding processes. The segmentation of the mold structure allows layered articles to be formed with sharp demarcation lines between layers.
Solution Approach 2:
Partition walls act as intermediary structures between different mold cavities. These walls physically separate the polymeric materials during injection and molding, preventing direct contact and mixing. The partition walls maintain the integrity of each material layer while allowing the overall molding process to proceed efficiently, thus resolving the contradiction between productivity and demarcation line regularity.
2Ease of manufacture
If polymeric materials are heated to cross-linking temperature, then the materials become viscous and injectable, but material mixing occurs during injection leading to irregular layer boundaries
Solution Approach 1:
The mold is divided into separate cavities with partition walls that prevent mixing of heated polymeric materials. Each cavity independently receives and processes its designated material, allowing the materials to reach cross-linking temperature and become injectable without compromising layer boundary definition. The segmentation maintains both ease of manufacture through proper material heating and manufacturing precision through physical separation.
Solution Approach 2:
Different regions of the mold (different cavities) are assigned different polymeric materials with specific properties. Each local region processes its designated material independently, ensuring that the local quality (material composition and layer boundary) is maintained while still allowing overall ease of manufacture through the heating and injection process.
3Device complexity
If a simple two-part mold is used, then the device complexity is low and production is efficient, but the demarcation between layers becomes irregular
Solution Approach 1:
The mold is segmented into multiple cavities separated by partition walls, creating a multi-cavity mold structure. While this increases device complexity compared to a simple two-part mold, the segmentation is achieved through relatively simple vertical partition walls that divide the mold into independent sections. This segmentation enables sharp layer demarcation while maintaining reasonable structural simplicity and production efficiency.
Solution Approach 2:
The partition walls are arranged vertically within the mold, adding a vertical dimension of separation rather than requiring complex horizontal or radial arrangements. This vertical segmentation approach maintains relative structural simplicity while effectively preventing material mixing and ensuring sharp layer demarcation in the final 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 method ensures a sharp and regular line of demarcation between layers, reducing production waste and maintaining consistent article quality, while being cost-effective and easy to implement.
Implementation Method 1
heating at least one component of said kit, constituted by a male mold part, a female mold part and at least one intermediate insert, to a temperature higher than said softening temperature of said polymers
Implementation Method 2
at least two distinct polymeric materials are brought to a respective softening temperature, at which point they become viscous and therefore injectable
Implementation Method 3
injecting the heated mixture of a polymeric material into a cavity defined between a pair of components of said kit, filling a perimetric seat of said cavity
Implementation Method 4
the polymer is solidified (when the cross-linking takes place), which occurs by virtue of the high temperatures imposed inside the mold
Implementation Method 5
the sharp increase in volume determined by the blowing agents present in the mass of polymeric material brings the molded product to dimensions that are actually larger than the final dimensions
Implementation Method 6
filling a perimetric seat of said cavity, said perimetric seat being defined between a perimetric groove of the receptacle present in one of the two components and a proximate flat surface of the other component
Data Source
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AI summary
A method for molding layered manufactured articles (100) made of polymeric material using a kit (1) which is constituted by a male mold part (2), a female mold part (3) and at least one intermediate insert (4). At least two distinct polymeric materials are brought to the respective softening temperature, at which point they become viscous and therefore injectable, and, subsequently, they are injected separately, each one into a respective cavity defined between the components of the kit (1). The method consists of: heating at least one component of the kit (1) to a temperature higher than the softening temperature of the polymers and corresponding to their cross-linking temperature; injecting the heated mixture of a polymeric material into a cavity defined between a pair of components of the kit (1), filling a perimetric seat of the cavity, the perimetric seat being defined between a perimetric groove (5) of the receptacle (6) present in one of the two components and a proximate flat surface (7) of the other component, which faces it; injecting the heated mixture of at least one other polymeric material into at least one further cavity defined between a further pair of components of the kit (1), filling a respective perimetric seat of the cavity, the perimetric seat being defined between a perimetric groove (8) of the additional receptacle (9) present in one of the two components and a proximate flat surface (10) of the other component, which faces it; separating the components of the kit (1); removing at least one intermediate insert (4); mating the remaining components of the kit (1), making the portion (11) of manufactured article (100) that is present in a receptacle (6) of a first component match up with the additional portion (12) which is present in a corresponding receptacle (9) of a second component, juxtaposing the border part (13) of a first portion of manufactured article (11), present in the perimetric groove (7) of the receptacle (6) of the respective component, against the border part (14) of a second portion of manufactured article (12), present in the perimetric groove (8) of the receptacle (9) of the corresponding component; keeping the remaining components mated for a predefined cross-linking time; separating the remaining components and extracting the manufactured article (100), including a respective perimetric border (15); removing the perimetric border (15) in order to obtain the manufactured article (100), now finished.