Child-Resistant Closure With Ribbed Base Wall
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing child-resistant closures require simultaneous axial and rotational forces to open, which can be cumbersome and may not effectively prevent access by children, as the lugs on the outer shell can cam over without rotating the inner shell if only rotated.
Innovation Solution
A two-piece push-and-turn child-resistant closure design featuring a plastic outer shell with internal L-shaped lugs and a plastic inner shell with external lugs, where the outer shell's central portion has ribs and a thinner central area, and the inner shell has a rib array and thinner central portion, enhancing engagement and alignment while reducing weight and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lugs on the outer shell are designed to cam over the lugs on the inner shell when rotated without axial force, then the closure can be removed easily by rotation alone, but the child-resistant mechanism fails because the inner shell does not rotate with respect to the container neck finish
Solution Approach 1:
The closure requires the user to perform axial pushing action before rotational movement can effectively engage the lugs. This preliminary axial action ensures the inner shell is properly positioned and engaged with the container, preventing children from simply rotating the closure to open it. The axial push activates the child-resistant mechanism by forcing the inner shell to rotate with the outer shell, while still allowing authorized users to remove the closure by continuing the pushing motion.
2Strength
If the base wall of the outer shell is made with uniform thickness, then the closure is stronger and more durable, but the weight and manufacturing cost increase
Solution Approach 1:
The base wall of the outer shell is designed with non-uniform thickness, featuring a thinner central portion and a thicker peripheral portion. This local quality variation provides sufficient structural strength at the periphery where the lugs engage with the container, while reducing material usage and weight in the central area where less structural support is needed. The design optimizes the balance between strength and weight by placing material only where structurally necessary.
3Strength
If the base wall of the inner shell is made with uniform thickness, then the closure is more durable, but the weight and manufacturing cost increase
Solution Approach 1:
The base wall of the inner shell is designed with non-uniform thickness, featuring a thinner central portion and a thicker peripheral portion. This local quality variation provides sufficient structural strength at the periphery where the lugs engage with the outer shell, while reducing material usage and weight in the central area. The design optimizes the balance between strength and weight by placing material only where structurally necessary for lug engagement.
4Strength
If more material is used in the base walls of both shells, then the closure is more durable and robust, but the manufacturing cost and material usage increase
Solution Approach 1:
Both the inner and outer shells feature base walls with non-uniform thickness distribution, with thinner central portions and thicker peripheral portions. This local quality approach ensures durability at the periphery where mechanical engagement occurs, while minimizing material usage in the central areas. The design achieves optimal durability-to-material ratio by concentrating material only where structurally necessary for lug engagement and overall closure integrity.
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
A plastic shell (42 or 44) for a two-piece push-and-turn child-resistant closure includes a peripheral skirt (48 or 76), and a base wall (46 or 74) from which the peripheral skirt depends. The base wall has a peripheral portion (50 or 80) having a first thickness, a plurality of lugs (58 or 84) disposed at least in part on the peripheral portion adjacent to the peripheral skirt, and a central portion (52 or 81) having a second thickness less than the first thickness. A plurality of ribs (66 or 84) having a third thickness greater than the second thickness and substantially equal to the first thickness extend from the first peripheral portion toward a center of the base wall.