Cosmetic Applicator Thread Islands for Easier Injection Molding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cosmetic applicators with push-out mechanisms for eyeliner leads face manufacturing challenges due to the need for unscrewing threads during injection molding, leading to complex processes and increased costs.
Innovation Solution
A cosmetic applicator with a lead casing tube featuring non-continuous, locally formed thread islands on its inner surface, allowing easy removal from the mold after injection molding by leveraging the elasticity of the plastic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a continuous thread is formed on the inner circumferential surface of the lead casing tube, then the lead holder can be translationally displaced over a long distance, but the manufacturing process becomes complex and requires unscrewing the sleeve from the injection mold
Solution Approach 1:
The continuous thread is segmented into multiple discrete thread islands distributed along the inner circumferential surface of the lead casing tube. Each thread island is a localized threaded structure that does not require unscrewing from the mold, yet collectively they enable the lead holder to be translationally displaced over the required long distance through cumulative engagement
Solution Approach 2:
The problematic continuous thread structure is extracted and replaced with discrete thread islands. This removes the constraint that forced the thread to be continuous and unscrewable from the mold, while preserving the essential function of translational displacement through the distributed arrangement of multiple localized thread structures
2Length of moving object
If a continuous thread is used in the lead casing tube, then the lead can be pushed out over a long distance, but equipment costs and cycle times increase due to complex molding requirements
Solution Approach 1:
The thread structure is divided into multiple discrete thread islands that can be directly formed during injection molding without requiring subsequent unscrewing operations. This segmentation allows the lead casing tube to be quickly ejected from the mold after a single injection cycle, significantly reducing equipment costs and production cycle times while still enabling the lead to be pushed out over the necessary long distance through the cumulative effect of multiple thread islands
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
Facilitates efficient and cost-effective production by simplifying the mold removal process, reducing equipment costs and cycle times.
Implementation Method 1
Due to the limited, namely only a few, purely local thread engagements between the injection mold or its core and the lead casing tube sprayed onto it, it is possible to remove the lead casing tube from the mold core with the outer thread by simply utilizing the elasticity of the still warm, freshly injected plastic.
Data Source
AI summary
A cosmetic applicator or assembly part for a cosmetic applicator, includes a thread spindle drive for moving a cosmetic mass lead relative to a lead housing tube accommodating the lead, wherein a thread is formed on an inner peripheral surface of the lead housing tube, and the thread interacts with a complementary thread of a lead holder, and the thread moves the lead holder together with the lead relative to the lead housing tube translationally when the lead holder is rotated, wherein said thread of the lead housing tube is not a continuous thread, but consists of a plurality of thread islands that are spaced apart from each other, each of the plurality of thread islands having thread projections extending by less than 121° in a circumferential direction and being shaped and arranged such that an outer thread of the lead holder always engages with at least one thread island.