Bi-injected Closure Moulding with Rotated Phase
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Solution Overview
Problem
Current bi-injection moulding processes face challenges in achieving a secure and efficient method for forming closures with integrated sealing areas and anti-rotation features, particularly in transitioning between mould phases and ensuring proper bonding between different materials.
Innovation Solution
A method involving bi-injection moulding with a first phase forming a cap with external sealing areas, followed by a second phase forming an outer ring around the cap sidewall, using different injection directions and materials, and incorporating anti-rotation ribs and tamper-evident features, with natural demoulding and rotation of the mould to facilitate secure sealing and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bi-injection moulding process is used to form a closure with integrated sealing areas and anti-rotation features, then the sealing and anti-rotation properties are enhanced, but the process complexity increases due to transitioning between mould phases and ensuring proper bonding between different materials
Solution Approach 1:
The closure is divided into two distinct parts formed in separate injection phases: a cap formed first with integrated sealing areas, and an outer ring formed second around the cap. This segmentation allows each part to be optimized for its specific function while maintaining reliable sealing through the dedicated sealing areas on the cap.
Solution Approach 2:
The outer ring is formed by injecting material around the already-formed cap, creating a nested structure where the cap is embedded within the outer ring. This nesting approach ensures proper bonding between the two materials while enhancing the sealing and anti-rotation properties of the closure.
2Strength
If material is injected axially in the first phase and laterally in the second phase, then the bonding between different materials is improved, but the device complexity increases due to requiring mould rotation and changing mould parts
Solution Approach 1:
The mould system is made dynamic by rotating the mould approximately 90 degrees between the first and second injection phases. This dynamic adjustment allows the mould to transition from an axial injection configuration to a lateral injection configuration, optimizing the bonding between different materials while managing the complexity through automated rotation.
Solution Approach 2:
The cap is formed first with integrated sealing areas and anti-rotation ribs in the initial axial injection phase. This preliminary action prepares the cap structure to receive the outer ring material in the subsequent lateral injection phase, ensuring proper bonding surfaces are already in place before the second material is introduced.
3Strength
If the mould is rotated approximately 90 degrees between phases, then the injection directions can be optimized for bonding, but the manufacturing complexity increases
Solution Approach 1:
The injection process transitions from a single-dimensional axial injection to a two-dimensional approach by rotating the mould 90 degrees and introducing lateral injection. This dimensional change allows optimized material flow and bonding between the cap and outer ring, while the rotation mechanism manages the manufacturing complexity through automated repositioning.
Data Source
AI summary
A method of forming a bi-injected closure, comprising the steps of: forming a cap with a top plate and a depending sidewall, in a first injection moulding phase using a first mould part, the cap formed so as to include one or more external sealing areas; changing the first mould part for a second mould part, the second mould part sealing against the or each sealing area on the cap; and forming an outer ring around the cap sidewall whilst the second mould part is sealed against the sealing area/s in a second moulding phase.