Flexible Inner Bag Syringe Cartridge Manufacturing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing syringe cartridges with flexible inner bags often result in complex coextrusion and visible seams, which are undesirable, and the inner bag material tends to bond with the outer container, making detachment difficult.
Innovation Solution
A method involving the production of a container without a bottom wall using a first plastic material, followed by inserting a mandrel to create an annular gap, where a second non-bonding material is injected to form a flexible inner bag with a desired wall thickness distribution, allowing easy detachment and integration of an annular groove for secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If coextrusion method is used to produce inner bag and container simultaneously, then production efficiency is improved, but the process becomes complex and visible seams appear on the bottom of the container
Solution Approach 1:
The manufacturing process is divided into two independent stages: first producing the container without bottom, then separately forming the inner bag by injection molding. This segmentation eliminates the complexity of simultaneous coextrusion while avoiding visible seams, as each component is manufactured independently with its own optimized process parameters.
Solution Approach 2:
The container is pre-formed without a bottom wall before the inner bag is injected. This preliminary preparation allows the inner bag material to be injected directly into the container cavity, eliminating the need for complex coextrusion equipment and processes while ensuring seamless integration of the inner bag with the container interior.
2Strength
If inner bag material bonds with outer container material, then structural integrity is improved, but detachment of the inner bag becomes difficult
Solution Approach 1:
The container design incorporates a specific geometric feature (undercut annular groove or flared outlet) at the outlet opening area, while the main body of the container maintains a smooth cylindrical shape. This local modification creates a mechanical interlock that provides structural integrity during use while allowing easy detachment by pulling the inner bag outward, as the flared geometry provides a release mechanism.
Solution Approach 2:
The undercut annular groove or flared outlet opening acts as an intermediary mechanical feature between the inner bag and outer container. It provides localized engagement that maintains structural integrity during dispensing, while simultaneously serving as a release mechanism that facilitates easy detachment when needed, mediating between the conflicting requirements of strength and ease of operation.
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
This method enables the production of syringe cartridges with flexible inner bags that are easily detachable, minimize residual contents, and ensure efficient dispensing without the issues of bonding and complex coextrusion, while maintaining effective sealing and reduced friction during use.
Implementation Method 1
a second material, which does not bond to the first material of the container, is injected into the annular gap and into the cavity remaining under the end of the mold core
Data Source
AI summary
The method for manufacturing a container with a flexible inner bag is characterized by the following steps: a) manufacturing a container, preferably from a first plastic material; b) arranging the container in an injection mold; c) inserting a smaller-diameter core into the container such that an annular gap remains between the core and the inner wall and a cavity at the end of the core; d) closing the injection mold and injecting a second material for the inner bag, which does not bond with the first material, into the annular gap and the cavity; e) opening the injection mold, withdrawing the core from the container, and removing the container with an attached inner bag.