Flip-Top Cap Bistable Living Hinge Design
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Solution Overview
Problem
Existing dental dispensers for flowable materials are not reliable, easy to use, and cost-effective, as they often require complex hinge structures and may be prone to wobbliness and interference during dispensing.
Innovation Solution
A monolithic flip-top cap is injection molded in an open position and then positioned into a closed position using a bistable living hinge with a pivot section and tension spring sections, allowing precise and stable positioning without external locking mechanisms, and is made from a single thermoplastic material like polypropylene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex hinge structure with external locking mechanisms is used, then the flip-top cap can be positioned reliably, but the device complexity increases and manufacturing cost increases
Solution Approach 1:
The patent merges the hinge structure and locking mechanism into a single integrated living hinge component. The living hinge itself performs both the pivoting function and the locking function through its bistable geometry, eliminating the need for separate external locking mechanisms and reducing overall device complexity while maintaining positioning reliability.
Solution Approach 2:
The living hinge is designed to be self-locking through its bistable geometric structure. When the closure is pushed to the closed position, the living hinge automatically locks without requiring external locking mechanisms. The hinge serves its own locking function through its inherent structural design, reducing complexity while ensuring reliable positioning.
2Reliability
If a complex hinge structure with external locking mechanisms is used, then the flip-top cap can be positioned reliably, but the manufacturing cost increases
Solution Approach 1:
The patent merges the hinge structure and locking mechanism into a single integrated living hinge component. The living hinge itself performs both the pivoting function and the locking function through its bistable geometry, eliminating the need for separate external locking mechanisms and reducing overall device complexity while maintaining positioning reliability.
Solution Approach 2:
The living hinge is designed as a simple, inexpensive component made from the same thermoplastic material as the cap body. This monolithic construction eliminates the need for expensive separate locking mechanisms and allows for cost-effective manufacturing through single-material injection molding, while still providing reliable positioning functionality.
3Shape
If the flip-top cap is molded in the closed position, then the closure covers the dropper nose, but the dropper nose cannot be accessed for dispensing
Solution Approach 1:
The patent incorporates a living hinge that enables dynamic movement between closed and open positions. The hinge allows the closure to pivot from the closed position (covering the dropper nose) to the open position (exposing the dropper nose for dispensing), providing both protective coverage and dispensing accessibility as needed.
Solution Approach 2:
The flip-top cap is pre-molded in the open position during manufacturing, with the closure already positioned to expose the dropper nose. This preliminary positioning ensures immediate accessibility for dispensing right after manufacturing, while the living hinge allows the closure to be moved to the closed position for protection when needed.
4Stability of the object's composition
If the living hinge is made with thick pivot section, then the pivot is stable, but the hinge cannot bend easily for bistable positioning
Solution Approach 1:
The living hinge employs local quality differentiation with a thick pivot section at the center for stability and thin tension spring sections at the ends for flexibility. This non-uniform thickness distribution allows the pivot section to provide stable rotation while the thinner sections enable easy bending and elastic deformation for bistable positioning.
Solution Approach 2:
The living hinge is segmented into functionally distinct regions: a thick pivot section for stable rotation and two thin tension spring sections for elastic deformation. This segmentation allows each region to optimize its local function - the pivot section provides stability while the spring sections provide flexibility and bistable behavior.
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 provides a reliable, easy-to-use, and cost-effective dispenser with a stable and precise flip-top cap that can be easily switched between open and closed positions, minimizing material stress and maximizing durability, ensuring accurate dispensing without interference.
Implementation Method 1
a pair of tension spring sections directly connected to the pivot section on opposite ends of the pivot section
Implementation Method 2
injection molded in the open position in an injection molding device
Implementation Method 3
injection molding device is preferably an injection molding machine having an extruder for heating and extruding the thermoplastic material
Data Source
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AI summary
A method of monolithically forming a flip-top cap from a thermoplastic material and a flip-top cap for dispensing a flowable dental substance. The flip-top cap has a base from which a dropper nose protrudes and a closure. The base and the closure are hingedly connected to each other by a living hinge for pivoting between a closed position, in which the closure closes the dropper nose, and an open position, in which the dropper nose is uncovered from the closure. The method has the steps of injection molding the flip-top cap in the open position in an injection molding device and positioning the closure and the base toward the closed position while the flip-top cap is still the injection molding device.