Cosmetic Cap Internal Skirt Variable Thickness
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Solution Overview
Problem
Conventional closure caps made from synthetic materials often develop shrinkage marks or deformations on the upper face due to constant thickness of the internal skirt, affecting the aesthetic appearance and perceived quality.
Innovation Solution
The internal skirt of the cap has a variable thickness, with a minimum thickness at the junction zone with the front wall, forming an undercut part and a connecting portion with a gradual thickness variation, which allows for uniform cooling and reduces the risk of surface defects during demoulding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the internal skirt has a constant thickness, then the manufacturing process is simple, but shrinkage marks or deformations appear on the front wall during cooling
Solution Approach 1:
The internal skirt is designed with variable thickness along its axial length, with a first portion having a first thickness and a second portion having a second thickness different from the first. This local variation in thickness allows different regions to cool at different rates, preventing shrinkage marks on the front wall while maintaining manufacturing simplicity.
Solution Approach 2:
The thickness parameter of the internal skirt is changed along its axial length, transitioning from a first thickness in the first portion to a second thickness in the second portion. This parameter change optimizes the cooling process during moulding, eliminating surface defects while keeping the manufacturing process straightforward.
2Manufacturing precision
If the internal skirt has an undercut part to enable uniform cooling, then shrinkage marks are reduced, but demoulding becomes more difficult
Solution Approach 1:
The undercut part is created locally in the junction zone between the internal skirt and front wall, where the thickness transitions from the first portion to the second portion. This localized undercut enables uniform cooling and reduces shrinkage marks, while the overall cap structure remains suitable for demoulding.
Solution Approach 2:
The undercut part is designed in advance in the junction zone to facilitate uniform cooling during the moulding process. This preliminary structural feature prevents shrinkage marks before they can form, while the cap's overall geometry is maintained to allow subsequent demoulding operations.
3Manufacturing precision
If the axial length of the proximal portion varies around the circumference, then surface defects during demoulding are reduced, but the manufacturing complexity increases
Solution Approach 1:
The axial length of the proximal portion of the internal skirt varies around the circumference, creating an asymmetric structure. This asymmetry reduces surface defects during demoulding by preventing continuous contact between the cap and the outer core of the mould, while the structure remains manufacturable using standard moulding techniques.
Solution Approach 2:
The axial length parameter of the proximal portion is varied around the circumference of the internal skirt. This parameter change creates an asymmetric geometry that reduces demoulding-induced surface defects, while the variation is designed to be compatible with standard manufacturing processes.
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 design minimizes the appearance of shrinkage marks on the front wall, enhancing the aesthetic and perceived quality of the cap by ensuring uniform cooling and reducing demoulding-induced defects.
Implementation Method 1
the local reduction in the thickness of the internal skirt in the junction zone with the front wall makes it possible to enable uniform cooling of the cap after moulding. Thus, the risk of the appearance of shrinkage marks on the front wall of the cap is limited.
Data Source
AI summary
The closure cap for a container comprises an internal fastening skirt (16), an external skirt (18) radially surrounding said internal skirt at least partially, and a front wall (14) from which said skirts extend. The internal skirt (16) has a variable thickness in the direction of its axial length, said thickness being at a minimum at least for a proximal portion (22) of said skirt which extends from the front wall (14). The internal skirt (16) comprises the proximal portion (22) with a thickness E that is substantially constant, a distal portion (24) with a thickness E2 that is substantially constantand greater than the thickness E1, and a connecting portion (26) that connects the proximal portion and thedistal portionand has a variable thickness E3 along its length. The axial length of the proximal portion (22) of the internal skirt varies around the circumference of said skirt.