Rigid Containers with Nonlinear Pinch Seams for Pressure Equalization
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Solution Overview
Problem
Existing containers with a rigid outer container and deformable inner bag require complex manufacturing steps and additional costs due to the need for creating wall openings in the outer container to facilitate pressure equalization during use, which can damage the thin inner bag.
Innovation Solution
A non-linear pinch seam is implemented at the bottom of the container, allowing air slit openings to form naturally during the manufacturing process, eliminating the need for additional wall openings and ensuring pressure equalization through capillary openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wall openings are created in the outer container to facilitate pressure equalization, then pressure equalization is improved, but the inner bag is damaged and manufacturing complexity increases
Solution Approach 1:
The pinch seam acts as an intermediary structure that provides pressure equalization functionality without requiring direct openings in the container wall. The capillary channels within the folded seam structure serve as the mediating pathway for air flow, eliminating the need for harmful wall openings while maintaining pressure balance between the inner bag and ambient environment
Solution Approach 2:
The pinch seam is designed with a folded structure that creates capillary-sized porous channels. These micro-channels allow controlled air flow for pressure equalization while maintaining the integrity of the outer container wall and preventing damage to the inner bag. The porous structure of the folded seam provides the necessary permeability without compromising structural strength
2Reliability
If wall openings are created in the outer container, then pressure equalization is improved, but manufacturing complexity and production time increase
Solution Approach 1:
The pressure equalization function is merged into the existing pinch seam structure at the bottom of the container. Instead of adding separate wall openings as an additional manufacturing step, the seam itself is designed with a folded configuration that inherently provides capillary channels for air flow. This integration eliminates the need for post-manufacturing modifications and reduces production complexity
Solution Approach 2:
The folded pinch seam structure is self-sufficient for pressure equalization without requiring additional manufacturing steps. The capillary channels are formed automatically during the sealing process, and the structure itself provides the necessary air flow pathways. This self-service approach eliminates the need for complex post-processing operations to create wall openings
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 non-linear pinch seam effectively equalizes pressure without requiring complex manufacturing steps, reducing production time and costs while protecting the inner bag from damage.
Implementation Method 1
the pinch seam runs alternately on both sides of the previous straight pinch seam, which bisects the bottom region. This pinch seam can have a jagged course, at least over part of its extent... the considerably longer length of the pinch seam creates a sufficient number of air slit openings
Implementation Method 2
When the blow mold closes, it pinches the base of the preform, with the pinch line adhering to the hot preform. When the blow mold is opened, the opening blow mold exerts a tensile force on the pinch line to separate itself from the pinched preform. The applicant has discovered that this causes the pinch line to expand slightly, forming capillary-sized air slot openings.
Data Source
Figure 1~3
AI summary
The container, which consists of a rigid outer container and a deformable inner bag made of thermoplastics which do not form a welded connection with one another, wherein a preform consisting of at least two tubes is co-extruded and arranged between the open halves of a blow mold, and the blow mold is closed when the preform has the length required to produce the container, wherein excess material from the bottom region of the container to be produced is squeezed off and a pinch seam is formed from welded material of the outer container, in which the welded bottom seam of the inner bag is clamped and held in the axial direction, and the preform is inflated by a pressure medium to rest against the wall of the blow mold and is removed after the blow mold has been opened, is characterized in that the pinch seam at the bottom of the container has a non-linear course,whereby the pinch seam is longer than in a linear course, and that by opening the blow mold, tiny air slit openings are formed in the seam of the outer container, through which ambient air can enter the space between the inner bag and the outer container to equalize the pressure.