Deformable Bottom Membrane for Thermoplastic Container Stability
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Solution Overview
Problem
Conventional stretch-blowing of thermoplastic containers induces residual stresses leading to deformation during hot filling, particularly when the fill temperature is high, and existing solutions like deformable bottoms or panels either require tools or compromise on blowability.
Innovation Solution
A thermoplastic container design featuring a deformable membrane at the bottom with an annular outer seat and radially extending inner seat, allowing two configurations and incorporating hollow reserves for increased deformability under low pressure, enabling easy transport and maintaining good blowability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a deformable bottom is used to compensate for volume variation during cooling, then container deformation is reduced, but the bottom requires tools to force its return position, reducing manufacturing simplicity and productivity
Solution Approach 1:
The bottom membrane is designed to be dynamically deformable, allowing it to automatically return to its initial position without tools. The membrane can deform under low pressure during cooling and then spontaneously return to its original configuration, eliminating the need for forcing tools while maintaining container stability.
Solution Approach 2:
The bottom membrane performs self-return to its initial position utilizing the pressure differential created during cooling. The system uses its own operational conditions (pressure changes during filling and cooling) to achieve the desired deformation and return without external intervention or additional tools.
2Ease of manufacture
If high blowing pressures are used to form the bottom structure, then blowability is improved, but the teeth formation becomes problematic and manufacturing complexity increases
Solution Approach 1:
The bottom structure is segmented into functional zones: a central deformable membrane area and an annular seat portion. This segmentation allows the membrane to be easily deformed while the annular seat provides structural support, eliminating the need for complex teeth formations and reducing manufacturing difficulty.
Solution Approach 2:
The problematic teeth formation is completely removed from the design. Instead of forming teeth in the annular seat, the invention uses a simplified annular seat structure combined with the deformable membrane, extracting the complex feature while maintaining the necessary functional characteristics.
3Adaptability or versatility
If the bottom is designed with a deployed position to increase displacement, then deformability is improved, but the bottom cannot return spontaneously without strong low pressure, causing body deformation
Solution Approach 1:
The bottom membrane is designed with dynamic deformability, allowing it to automatically return to its initial position without tools. The membrane can deform under low pressure during cooling and then spontaneously return to its original configuration, eliminating the need for forcing tools while maintaining container stability.
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 design allows for significant deformation compensation without tools, minimizing body deformation during cooling and maintaining high blowability, thus addressing the issues of residual stress and deformation in thermoplastic containers.
Implementation Method 1
under the effect of the low pressure accompanying the retraction of the liquid
Implementation Method 2
the bottom has an increased deformability under the effect of low pressure in the filled container
Implementation Method 3
enabling easy transport of the empty container resting on the inner seat
Implementation Method 4
the bi-orientation induces in the material residual stresses that, during hot filling (particularly with a liquid having a temperature above the glass transition temperature of the material), are released, causing a deformation of the container
Data Source
AI summary
Container (1) of plastic material, comprising a body (5) and a bottom (6), the bottom (6) having an annular outer seat (8) defining a principal seating plane (9) for the container (1), and a deformable membrane (10) that extends radially inside the annular outer seat (8) and is arranged to be able to adopt two configurations:a retracted configuration, in which the membrane (10) extends axially above the principal seating plane (9);a deployed configuration, in which the membrane (10) comprises an annular inner seat (14) in the form of an annular bead projecting towards the exterior of the container (1), which extends axially beneath the principal seating plane (9) and defines a secondary seating plane (15),the bottom (6) comprising a series of hollow reserves (20) in the annular inner seat (15) [sic], which form local discontinuities of the secondary seating plane (15).