Corrugated Crown Closure Die for Pressure Resistance and Flexibility
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Solution Overview
Problem
Existing moulding dies for crown closures struggle to produce shells with both high pressure resistance and flexibility, particularly when made from thin metal sheets, while maintaining hermetic sealing and efficient capping operations.
Innovation Solution
A moulding die comprising an external and internal part with interlocking teeth and protrusions, an internal core, and elastic means that facilitate plastic deformation to create corrugated skirt walls, enhancing sealing performance and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a thin sheet of metal is used to make the crown closure shell, then the device complexity and material usage are reduced, but the strength and pressure resistance deteriorate
Solution Approach 1:
The die body is segmented into multiple functional components: an external part with circumferential recesses for forming corrugations, an internal part with corresponding protrusions, and a movable internal core. This segmentation allows each component to contribute specifically to creating the corrugated structure that provides strength while using thin material.
Solution Approach 2:
The die creates a corrugated skirt wall with alternating ridges and grooves - a curved, non-uniform surface structure. This corrugation pattern enhances the mechanical strength and pressure resistance of the thin metal shell by distributing stresses more effectively than a flat surface would.
2Strength
If the crown closure is made with high rigidity to withstand pressure, then the strength improves, but the flexibility and ease of operation during capping deteriorate
Solution Approach 1:
The corrugated skirt wall with its alternating ridges and grooves provides a unique mechanical property: it can resist radial pressure forces while maintaining flexibility for axial deformation. The curved corrugation pattern allows the structure to flex during capping operations while withstanding internal pressure when sealed.
3Manufacturing precision
If the corrugations are formed with high precision to ensure sealing, then the manufacturing precision improves, but the device complexity increases
Solution Approach 1:
The die is divided into external and internal parts with complementary features (recesses and protrusions). This segmentation allows the corrugation pattern to be formed through the relative movement and interaction of simpler components rather than requiring a single complex tooling piece.
Solution Approach 2:
The external part with circumferential recesses and the internal part with protrusions work together as a unified molding system. Their combined action during die closure creates the precise corrugation pattern, merging two simpler components to achieve the precision that would be difficult with a single complex component.
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 enables the production of crown closures with optimal sealing performance, high pressure resistance, and flexibility, while maintaining a simple and cost-effective construction, ensuring effective sealing and capping operations.
Implementation Method 1
elastic means that operates with an axial elastic force on the core
Implementation Method 2
improve the features of the plastic deformation that produces the corrugations
Data Source
Figure 1~3
Figure 2
Figure 4
AI summary
A moulding die and a moulding apparatus are disclosed that comprises the moulding die, in which the die defines a cavity for moulding a shell of a crown closure for containers along a moulding axis, in which the die comprises a number N of recesses arranged circumferentially around the moulding axis to form corrugations of a corrugated skirt wall of the shell, in which the die comprises an external part with a number N of teeth and an internal part with a number N of protrusions, in which each protrusion is arranged in a space comprised between two adjacent teeth, and in which the external part and the internal part are moved axially in relation to one another during moulding.