Airless Pump Bag Forming via Vacuum-Blow Moulding
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Solution Overview
Problem
Existing methods for forming deformable bags within rigid containers are laborious, costly, and result in non-homogeneous bag inflation, leading to potential rupture and incomplete volume occupation, as well as requiring delicate handling to avoid tearing during insertion.
Innovation Solution
A method involving a blow moulding process where a preform is heated and inserted into a rigid container, with a blow moulding head applying vacuum and compressed air in a controlled sequence to inflate the bag uniformly, ensuring it adheres to the container walls without adhesion and achieving complete cavity filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a preform is inflated within a rigid container using conventional methods, then the bag is formed inside the container, but the bag inflation is non-homogeneous and may lead to rupture
Solution Approach 1:
The preform is heated to a temperature sufficient to soften the plastic material before inflation. This preliminary thermal softening action allows the material to deform more uniformly during inflation, preventing non-homogeneous wall thickness and reducing rupture risk.
Solution Approach 2:
The inflation process uses a dual-stage pneumatic system: first applying vacuum to draw the preform against the container walls, then applying compressed air to inflate the bag uniformly. This periodic alternation between vacuum and pressure ensures homogeneous inflation without creating weak spots that could lead to rupture.
2Reliability
If the bag is inserted into the rigid container after filling, then the fluid substance can be isolated from the atmosphere, but the insertion operation is very delicate and the bag can be easily torn
Solution Approach 1:
Instead of inserting the filled bag into the container (which is delicate and risky), the invention inverts the sequence by forming the bag directly inside the container using a preform. This reversal eliminates the delicate insertion operation entirely, as the bag is created in situ and naturally adheres to the container walls.
Solution Approach 2:
The preform is prepared in advance with the correct shape and size to fit within the container. By performing the bag formation operation beforehand (during container manufacturing), the need for delicate post-filling insertion is eliminated, making the overall process much easier and more reliable.
3Ease of manufacture
If the bag is formed directly within the rigid container using heating and inflation, then the production process is simplified, but the bag may not occupy the complete cavity volume
Solution Approach 1:
The inflation process uses periodic alternation between vacuum application and compressed air injection. The vacuum phase draws the preform tightly against the container walls to maximize volume occupation, while the compressed air phase inflates the bag to the required volume. This periodic action ensures complete cavity filling while maintaining production simplicity.
Solution Approach 2:
The process controls the pressure parameters dynamically: first applying negative pressure (vacuum) to expand the preform against the container walls, then applying positive pressure (compressed air) to inflate the bag to full volume. By changing the pressure parameters in sequence, the bag occupies the complete cavity volume while keeping the process simple and integrated.
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 method enables rapid, cost-effective production of deformable bags with homogeneous thickness, reduced risk of rupture, and complete cavity occupation, facilitating easier pump operation while maintaining sterility and preventing fluid contact with the atmosphere.
Implementation Method 1
a preform (made of thermoplastic material and having an elongated hollow cylindrical body
Implementation Method 2
with the aid of a blow moulding head applying vacuum and compressed air in a controlled sequence
Implementation Method 3
a blow moulding head applying vacuum and compressed air in a controlled sequence to inflate the bag uniformly
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A method for producing a container associable with airless pumps, in the interior of which container a deformable bag is formed by blow moulding a preform of plastic material. A vacuum is created in the container interior during or slightly before blowing.