Multi-Point Injection Moulding for Uniform Packaging Walls
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Solution Overview
Problem
Conventional injection and compression moulding technologies face challenges in achieving uniform distribution of plastic melt in the cavity, leading to instability and uneven material thickness in the production of thin-walled packaging container parts, especially when manufacturing multiple parts simultaneously.
Innovation Solution
The apparatus features an inner and outer mould element with at least one partly freely suspended, allowing for injection of plastic melt at multiple points within the cavity, with the distribution of these points optimized to ensure the compression force acts through a defined surface, maximizing stability and force balance by adjusting to differences in melt quantity and guiding errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional injection moulding is used to mould thin-walled package parts, then the production cycle time can be kept short, but the plastic melt is not uniformly distributed in the cavity leading to uneven material thickness
Solution Approach 1:
The injection system is divided into multiple independent injection units, each capable of injecting melt into a specific region of the cavity. This segmentation allows simultaneous injection at multiple points, filling the cavity more uniformly and achieving even material thickness distribution while maintaining short production cycle times.
Solution Approach 2:
Multiple injection units are merged into a single integrated moulding system that operates simultaneously. The combined action of multiple injection points working in parallel achieves uniform melt distribution throughout the cavity, resolving the contradiction between fast production and uniform material thickness.
2Productivity
If multiple package parts are manufactured simultaneously in the same moulding tool, then productivity increases, but the balance and uniformity of moulding becomes more difficult to attain
Solution Approach 1:
The moulding tool is segmented into multiple independent cavities, each with its own injection unit. This allows simultaneous moulding of multiple parts with independent control over each cavity's filling process, ensuring uniformity is maintained even as productivity increases through multi-cavity operation.
Solution Approach 2:
Each injection unit can be independently adjusted to provide optimal injection parameters for its specific cavity. This local quality control ensures that each part receives the precise amount of melt needed, maintaining uniformity across all parts produced simultaneously.
3Stability of the object's composition
If stable suspension of moulding tools is used, then symmetry is achieved, but the system is sensitive to disruptions such as uneven melt quantity and tool guiding errors
Solution Approach 1:
The moulding tools are designed with dynamic suspension capabilities, allowing them to adjust their position during the injection process. This dynamic adjustment compensates for variations in melt quantity and guiding errors, maintaining symmetry while increasing reliability and immunity to disruptions.
Solution Approach 2:
The moulding system incorporates self-adjusting mechanisms that automatically compensate for disruptions without external intervention. The tools can self-correct positioning errors and adapt to melt quantity variations, maintaining stable suspension and symmetry while being reliable against disruptions.
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 approach enables the production of thermoplastic packaging parts with uniform material thickness and improved stability, maintaining high accuracy and short production cycle times even under conditions of uneven melt distribution and tool guiding errors.
Implementation Method 1
a first number of injection units (42) are provided for injecting a plastic material in a molten state into the mould cavity (30)
Implementation Method 2
means for injecting in a plastic melt into the cavity, means for converging said mould elements so that the cavity is closed and for applying a compression force on the mould elements in order to press out the plastic melt in the cavity
Data Source
Figure 1
Figure 2~3
Figure 4a~4b
AI summary
The present invention relates to an apparatus and a method for moulding one or more thermoplastic package parts in association each to an end portion (20) of a packaging container body (12). The apparatus is of the type which includes an inner mould element (24) and an outer mould element (26) between which a mould cavity (30) per package part is formed. At least one of these mould elements is at least partly freely suspended. In the case when one package part is moulded with the mould elements, the apparatus is characterised in that a plastic melt (32) is injected in a first number > 1 of points (42) in the cavity (30), an island (45) of plastic melt for each point being formed inside the cavity, and that the distribution of said points (42) is such that a force centre (F) may be caused to pass through a surface (92) which is defined by a parallel projection (45', 45') of each one of said first number of islands (45) on a plane (P) which is orthogonal to a direction (D) of the compression force and, when said first number > 1, a second number of imaginary straight lines (90) which interconnect a third number of the parallel projections (45', 45') in such a manner that the surface (92) will be at its maximum.