Friction Ring for Push-Turn Child Resistant Closure
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Solution Overview
Problem
Existing two-piece push and turn child resistant closures require excessive downward force due to low friction between polypropylene surfaces, making it difficult to translate rotational force onto the under cap effectively.
Innovation Solution
Incorporating a bi-injected highly frictional material, such as a rubber and polypropylene blend, with a friction ring between the over cap and under cap, and using slide rails with low friction surfaces for handling, to reduce the force required for rotational movement while maintaining child resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If polypropylene surfaces are used for the over cap and under cap, then the closure maintains chemical resistance and structural integrity, but the friction between surfaces is too low to effectively translate rotational force onto the under cap
Solution Approach 1:
The patent applies composite materials by bi-injecting a rubber elastomer layer onto the polypropylene over cap. This creates a composite structure where the polypropylene provides structural integrity and chemical resistance, while the rubber elastomer provides high friction surfaces that enable effective rotational force translation to the under cap, resolving the contradiction between maintaining material properties and improving force transmission.
Solution Approach 2:
The patent changes the friction parameter by introducing a rubber elastomer material with high coefficient of friction onto the over cap surface. This parameter change transforms the low-friction polypropylene-polypropylene interface into a high-friction rubber-polypropylene interface, allowing rotational force to be effectively translated into downward force for closure removal.
2Force
If a high friction material is applied to the over cap to improve rotational engagement, then force transmission is improved, but the closure becomes difficult to handle with normal closure machine operations
Solution Approach 1:
The patent applies local quality by providing high friction rubber elastomer surfaces only at specific locations on the over cap where rotational engagement occurs (the circumferential surface engaging the under cap), while leaving other surfaces smooth and suitable for machine handling. This localized application of frictional properties enables effective force transmission during closure removal without interfering with normal machine handling operations.
Solution Approach 2:
The patent segments the over cap into different functional zones: a high-friction rubber elastomer portion for rotational engagement with the under cap, and a smooth polypropylene portion for machine handling. This segmentation allows each zone to perform its specific function optimally without compromising the other.
3Ease of operation
If downward force is increased to overcome low friction between caps, then rotational movement can be imparted to the under cap, but excessive force is required making the closure difficult to remove
Solution Approach 1:
The rubber elastomer composite material on the over cap creates high friction engagement with the under cap, transforming the force transmission mechanism. This allows rotational movement to be imparted to the under cap with reduced downward force, making closure removal easier while maintaining child resistance through the push-and-turn mechanism.
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 reduces the necessary downward force for removing the closure by increasing frictional engagement between the caps, allowing easier rotational movement and improved handling without compromising child resistance.
Implementation Method 1
a friction ring interposed between the over cap and under cap to aid in removal of the push and turn child resistant closure and more readily impart rotational from downward force
Implementation Method 2
slide rails on the closure in combination with gripping surfaces, the slide rails allowing for more ready handling of the closure
Data Source
AI summary
A push and turn child resistant closure is provided which includes a combined over cap and under cap, the under cap freely rotational within the over cap and the combined closure installed on the container. For removal of the combined closure, both downward and counter-clockwise rotational force is applied to the over cap, the rotational force imparted on the under cap more readily by utilization of a friction ring at the engagement area between the over cap and the under cap while also having an outer gripping ring of highly frictional material making it much more easily rotatable and graspable by a user. The use of a highly frictional material more readily imparts rotational force on the under cap when utilized as depicted herein.